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We study the combined effects of local and nonlocal hybridization on the formation and condensation of the excitonic bound states in the extended Falicov-Kimball model by the density-matrix-renormalization-group (DMRG) method. Analysing the resultant behaviours of the excitonic momentum distribution N(q) we found, that unlike the local hybridization V, which supports the formation of the q=0 momentum condensate, the nonlocal hybridization Vn supports the formation of the q=π momentum condensate. The combined effect of local and nonlocal hybridization further enhances the excitonic correlations in q=0 as well as q=π state, especially for V and Vn values from the charge-density-wave (CDW) region. Strong effects of local and nonlocal hybridization are observed also for other ground-state quantities of the model such as the f-electron density, or the density of unbound d-electrons, which are generally enhanced with increasing V and Vn. The same calculations performed for nonzero values of f-level energy Ef revealed that this model can yield a reasonable explanation for the pressure-induced resistivity anomaly observed experimentally in TmSe0.45Te0.55 compound. © 2017 Elsevier Ltd


Capek I.,Slovak Academy of Sciences
Polymer Bulletin | Year: 2017

The solution polymerizations of acrylamide (AAm) initiated by the photoinitiator DAROCUR 2959 (DAR) and UV light were studied. The kinetics of acrylamide polymerization in the presence of silver salt was investigated. Dilatometry was implemented to follow continuously the fast photopolymerization. The polymerization rate vs conversion curve of the photopolymerization of AAm was described by two nonstationary-state intervals. The abrupt increase in the initial rate was attributed to the accumulation of the reaction loci. The continuous decrease in the polymerization rate with conversion was discussed in terms of the increased termination based on the intra- and intermolecular chain transfer to polymer. The deactivation of the excited states of initiator and initiating radicals by their interaction with reaction products (silver nanoparticle–polymer nanocomposites) is also taken into account. The irradiation of silver salt and AAm led to the formation of silver–polymer nanocomposites. The small silver nanoparticles grow during the photolysis (or polymerization and storing) to microparticles and large agglomerates. © 2017 Springer-Verlag Berlin Heidelberg


Jencova A.,Slovak Academy of Sciences | Jenca G.,Slovak University of Technology in Bratislava
International Journal of Theoretical Physics | Year: 2017

The category Rel is the category of sets (objects) and relations (morphisms). Equipped with the direct product of sets, Rel is a monoidal category. Moreover, Rel is a locally posetal 2-category, since every homset Rel(A,B) is a poset with respect to inclusion. We examine the 2-category of monoids RelMon in this category. The morphism we use are lax. This category includes, as subcategories, various interesting classes: hypergroups, partial monoids (which include various types of quantum logics, for example effect algebras) and small categories. We show how the 2-categorical structure gives rise to several previously defined notions in these categories, for example certain types of congruence relations on generalized effect algebras. This explains where these definitions come from. © 2017 Springer Science+Business Media New York


Agricultural and industrial conditions are not favourable in the uphill and mountain areas of the Zamagurie region, and tourism is often the only opportunity to create new jobs, develop the habitation areas and avoid the emigration of local inhabitants. The Walachian and Sholtys colonization has transformed the landscape and created unique significant spatial landscape elements that are traditionally utilized for agricultural purposes, and create a unique esthetical landscape preserved till the present times. This case study has been aimed at developing and applying the new quantification methods using GIS tools for evaluation of localizing, selective realization and environmental preconditions of the landscape, representing recreational (cultural) services of the landscape ecological systems, based on selected indicators. To evaluate the localizing preconditions of the landscape, we referred to the landscape-ecological complex geo-databases (LEC) (Thematic maps-internal ground document of ZB GIS , 2013), completed with the field survey during the period 2013-2014 and identification of secondary landscape structure elements (SLS) and selected morphometric indicators. While evaluating the selected town-planning, demographical and social-economic indicators, we quantified the selective landscape preconditions of tourism development. The realization preconditions were reviewed according to communication accessibility and material-technical equipment. As for environmental preconditions, we reviewed the presence of protected territory and landscape environmental load. © 2017 by Zdena Krnáčová.


Kalinay P.,Slovak Academy of Sciences
Journal of Chemical Physics | Year: 2017

An algorithm calculating the effective diffusion coefficient D(x) in 2D and 3D channels with periodically varying cross section along the longitudinal coordinate x is presented. Unlike other methods, it is not based on scaling of the transverse coordinates, or the smallness of the width of the channel. The result is expressed as an integral of specific contributions to D(x) coming from the positions neighboring to x. The method avoids the hierarchy of derivatives of the channel shaping function h(x), so it is also suitable for the channels with cusps or jumps of their width. The method describes correctly D(x) in wide channels, giving the expected behavior in the limit of infinite width (no confinement). © 2017 Author(s).


Mesiarova-Zemankova A.,Slovak Academy of Sciences
Information Sciences | Year: 2017

Uninorms continuous on [0, e[2 ∪ ]e, 1]2 are discussed. Archimedean uninorms continuous and cancellative on ]0, e[2 ∪ ]e, 1[2 are characterized and related non-Archimedean uninorms are also discussed. The problem when is the border-continuous projection of a t-norm associative, i.e., a t-subnorm is also answered. © 2017 Elsevier Inc.


Capek I.,Slovak Academy of Sciences
Advances in Colloid and Interface Science | Year: 2017

Noble metal, especially gold nanoparticles and their conjugates with biopolymers have immense potential for disease diagnosis and therapy on account of their surface plasmon resonance (SPR) enhanced light scattering and absorption. Conjugation of noble metal nanoparticles to ligands specifically targeted to biomarkers on diseased cells allows molecular-specific imaging and detection of disease. The development of smart gold nanoparticles (AuNPs) that can deliver therapeutics at a sustained rate directly to cancer cells may provide better efficacy and lower toxicity for treating cancer tumors. We highlight some of the promising classes of targeting systems that are under development for the delivery of gold nanoparticles. Nanoparticles designed for biomedical applications are often coated with polymers containing reactive functional groups to conjugate targeting ligands, cell receptors or drugs. Using targeted nanoparticles to deliver chemotherapeutic agents in cancer therapy offers many advantages to improve drug/gene delivery and to overcome many problems associated with conventional radiotherapy and chemotherapy. The targeted nanoparticles were found to be effective in killing cancer cells which were studied using various anticancer assays. Cell morphological analysis shows the changes occurred in cancer cells during the treatment with AuNPs. The results determine the influence of particle size and concentration of AuNPs on their absorption, accumulation, and cytotoxicity in model normal and cancer cells. As the mean particle diameter of the AuNPs decreased, their rate of absorption by the intestinal epithelium cells increased. These results provide important insights into the relationship between the dimensions of AuNPs and their gastrointestinal uptake and potential cytotoxicity. Furthermore gold nanoparticles efficiently convert the absorbed light into localized heat, which can be exploited for the selective laser photothermal therapy of cancer. We also review the emerging technologies for the fabrication of targeted gold colloids as imagining agents. © 2017 Elsevier B.V.


Sihelska N.,Slovak Academy of Sciences | Glasa M.,Slovak Academy of Sciences | Subr Z.W.,Slovak Academy of Sciences
Journal of Integrative Agriculture | Year: 2017

Plum pox virus (PPV) causes sharka — the most serious viral disease of stone fruit trees. PPV is wide spread in Europe and Mediterranean Basin, its incidence has been further approved in Asia and both Americas. Nine PPV strains have been recognized until now (PPV-D, PPV-M, PPV-Rec, PPV-EA, PPV-C, PPV-T, PPV-W, PPV-CR, and PPV-An), forming molecularly distinct entities, however, only partially differentiable by their biological or epidemiological properties. The most strict virus-host linkages under natural conditions have been detected for strains naturally infecting cherries (PPV-C and PPV-CR). However, although less stringent but still clear host preference is observed also for three epidemiologically most important strains (PPV-D/plum/apricot, PPV-M/peach, and PPV-Rec/plum). So far no genetic marker has been mapped in the PPV genome, which responsibility for the host specificity/preference could be explicitly demonstrated. In this review, we focus on the host preference of three major PPV strains as evidenced by analysis of an extensive dataset of PPV isolates of Slovak and world-wide origin. Together, we discuss several performed relevant experiments and further possible research procedures aimed to better understand the genetic determinants and mechanisms of the host preference of this potyvirus. © 2017 Chinese Academy of Agricultural Sciences


Kristin A.,Slovak Academy of Sciences | Kanuch P.,Slovak Academy of Sciences
Journal of Ornithology | Year: 2017

Many birds exhibit territoriality, which is vital for obtaining resources for survival. Non-migratory birds maintain larger territories in winter than during reproduction, but the degree of their fidelity to these winter home ranges is less well-known. We evaluated the homing success and time of return to home through a field experiment in which we trapped and displaced 1239 individual birds of two tit species, Great Tit (Parus major) and Blue Tit (Cyanistes caeruleus), and retrapped 267 of them over two winters (a total of 40 trapping sessions). Displacement of the birds between two sites 7.8 km apart revealed strong fidelity to the winter home range in both species; birds returned on average within 4 weeks. Greater homing success was found in Blue Tits than in Great Tits (45.7 vs. 32.5 % retraps). More individuals returned home from an ecotone site, which included gardens with feeders, than from a forest site (40.9 vs. 29.2 %). Blue Tits homed approximately 1 week more quickly than Great Tits, and similar mean differences were observed when comparing males with females of both species using Kaplar–Meier survival functions. A parametric survival regression model indicated that the difference in homing time between species was not significant, but males of both species returned significantly sooner than females. Moreover, birds that originated from a site with greater food supply homed more quickly, and interaction of sex and site also showed a significant effect in this model. Our evidence suggests that winter territoriality of these woodland passerines is shaped potentially by all tested factors and is an important behavioural characteristic linked with their ability to find limited resources during the harsh period of the year. © 2016, Dt. Ornithologen-Gesellschaft e.V.


Sadovsky Z.,Bratislava | Krivacek J.,Slovak Academy of Sciences
Journal of Constructional Steel Research | Year: 2017

The paper addresses the ultimate buckling strength of thin-gauge axially loaded lipped channel columns with initial geometrical imperfections related to execution tolerances. For computational modelling of the column strength respecting the tolerance limits a deterministic method employing geometrical and material nonlinear FEM analysis with imperfections (GMNIA) is suggested. The imperfections are assumed in the shapes of eigenmodes of the corresponding linearized buckling problem and their combinations. For comparing their influence on the column strength, the imperfections are normalized by the energy measure. The comparison is carried out on the top energy measure level limited by execution tolerances. Referring to published experimental work three cross-sections and several column lengths are considered in a numerical study. Summarizing the numerical results and abilities of the energy measure to facilitate the treatment, guidance for the use of FEM GMNIA in the estimation of the column least strength is suggested. © 2016 Elsevier Ltd


Mruczkiewicz M.,Slovak Academy of Sciences | Krawczyk M.,Adam Mickiewicz University | Guslienko K.Y.,University of the Basque Country | Guslienko K.Y.,Ikerbasque
Physical Review B - Condensed Matter and Materials Physics | Year: 2017

We study spin-wave excitations in a circular ferromagnetic nanodot in different inhomogeneous, topologically nontrivial magnetization states, specifically, vortex and skyrmion states. Gradual change in the strength of the out-of-plane magnetic anisotropy and the Dzyaloshinskii-Moriya exchange interaction leads to continuous phase transitions between different stable magnetic configurations and allows for mapping of dynamic spin modes in and between the vortex, Bloch-type skyrmion, and Néel-type skyrmion states. Our study elucidates the connections between gyrotropic modes, azimuthal spin waves, and breathing modes in these various stable magnetization states and helps us to understand the rich spin excitation spectrum on the skyrmion background. © 2017 American Physical Society.


Neslusan L.,Slovak Academy of Sciences
Astrophysics and Space Science | Year: 2017

The new possibilities to construct the stable relativistic compact objects were opened by Ni in 2011, after his discovery of new solution of the Einstein field equations for the spherically symmetric distribution of matter. The solution occurs to be the super-class of the well-known Tolman-Oppenheimer-Volkoff solution published in 1939. In the presented work, we consider the equation of state for a radiation fluid and use the Ni’s solution to construct the massive objects consisting of radiation. We describe their fundamental properties. Since there is no upper constraint of energy/mass of the Ni’s object, the formally calculated gravitational mass (from gravitational effects) of these objects can be as high as observed for the super-massive compact objects in the centers of galaxies and even in the most massive quasars. In the solution by Ni, the gravitational acceleration is not linearly proportional to the energy concentrated in the object. Actually, the models indicate that the objects should be extremely luminous, as quasars. The most massive of them can have enough energy to emit the radiation with a quasar luminosity during the age of the universe. And, it is predicted that they must possess an extremely extended “corona” with the gravitational effects resembling those, which are assigned to a dark matter. © 2017, Springer Science+Business Media Dordrecht.


Petrzala J.,Slovak Academy of Sciences | Komar L.,Slovak Academy of Sciences | Kocifaj M.,Slovak Academy of Sciences
Renewable Energy | Year: 2017

The article proposes a clear-sky physical model for the calculation of solar irradiances and illuminances. In contrast to other empirical models, ours takes into account the actual atmospheric pollution conditions, characterized by the optical parameters of atmospheric aerosols. Even if these optical parameters have not been measured directly, the model enables us to estimate their values from routinely measured solar radiation or daylight quantities at actinometric or daylight measurement stations and consequently to predict quantities not directly measured: irradiances and illuminances on arbitrary oriented or inclined surfaces. The software solution we have developed is demonstrated by a set of numerical experiments that are compared against the measurements. © 2017 Elsevier Ltd


Neslusan L.,Slovak Academy of Sciences | Hajdukova M.,Slovak Academy of Sciences
Astronomy and Astrophysics | Year: 2017

Aims. Using IAU MDC photographic, IAU MDC CAMS video, SonotaCo video, and EDMOND video databases, we aim to separate all provable annual meteor showers from each of these databases. We intend to reveal the problems inherent in this procedure and answer the question whether the databases are complete and the methods of separation used are reliable. We aim to evaluate the statistical significance of each separated shower. In this respect, we intend to give a list of reliably separated showers rather than a list of the maximum possible number of showers. Methods. To separate the showers, we simultaneously used two methods. The use of two methods enables us to compare their results, and this can indicate the reliability of the methods. To evaluate the statistical significance, we suggest a new method based on the ideas of the break-point method. Results. We give a compilation of the showers from all four databases using both methods. Using the first (second) method, we separated 107 (133) showers, which are in at least one of the databases used. These relatively low numbers are a consequence of discarding any candidate shower with a poor statistical significance. Most of the separated showers were identified as meteor showers from the IAU MDC list of all showers. Many of them were identified as several of the showers in the list. This proves that many showers have been named multiple times with different names. Conclusions. At present, a prevailing share of existing annual showers can be found in the data and confirmed when we use a combination of results from large databases. However, to gain a complete list of showers, we need more-complete meteor databases than the most extensive databases currently are. We also still need a more sophisticated method to separate showers and evaluate their statistical significance. © ESO 2017.


Caserta A.,The Second University of Naples | Di Maio G.,The Second University of Naples | Hola L.,Slovak Academy of Sciences
Journal of Mathematical Analysis and Applications | Year: 2010

In 1883 Arzelà (1983/1984) [2] gave a necessary and sufficient condition via quasi-uniform convergence for the pointwise limit of a sequence of real-valued continuous functions on a compact interval to be continuous. Arzelà's work paved the way for several outstanding papers. A milestone was the P.S. Alexandroff convergence introduced in 1948 to tackle the question for a sequence of continuous functions from a topological space (not necessarily compact) to a metric space. In 2009, in the realm of metric spaces, Beer and Levi (2009) [10] found another necessary and sufficient condition through the novel notion of strong uniform convergence on finite sets. We offer a direct proof of the equivalence of Arzelà, Alexandroff and Beer-Levi conditions. The proof reveals the internal gear of these important convergences and sheds more light on the problem. We also study the main properties of the topology of strong uniform convergence of functions on bornologies, initiated in Beer and Levi (2009) [10]. © 2010 Elsevier Inc.


Kesa P.,Slovak Academy of Sciences | Antalik M.,Slovak Academy of Sciences | Antalik M.,Pavol Jozef Safarik University
Chemical Physics Letters | Year: 2017

In this work we established three from altogether six proton dissociation constants (pKa) of hydroxyl groups of hypericin in its monomeric form. The monomeric state of hypericin (5.0 × 10−6 mol·L−1) in aqueous solution was stabilised by the presence of hydrotropic drug Cromolyn disodium salt (6.0 × 10−2 mol·L−1). Data show that one acid-base transition occurs with the pKa of 7.8 and the other two are characterised by the apparent single pKa of 11.5. The spectral changes of hypericin above pH 13 indicate that the last two hydroxyls are deporotonized at this high pH values. © 2017 Elsevier B.V.


Halmova D.,Slovak Academy of Sciences | Melo M.,Comenius University
IAHS-AISH Publication | Year: 2010

The future water reservoir ability to ensure the required water demand, as defined by downstream water users (hydropower producers, irrigation, industry) was studied. We utilised data from the coupled general circulation model CCCM2000. Present horizontal resolution of GCMs does not allow identification of regional climate. Thus, we use a statistical method for downscaling of GCM outputs. We take into account model outputs from four gridpoints near to northern Slovakia. The rainfall-runoff model WBMOD calculated the water reservoir operation. The input data series of precipitation, air temperature and the observed reservoir outflows were used to model changes in total runoff and the required reservoir capacity. Deficiency in the required water demand for changed climate conditions was evaluated. In general, it can be concluded that the expected climatic change would influence the certainty of the water supply from the reservoirs. Copyright © 2010 IAHS Press.


Pastircakova K.,Slovak Academy of Sciences | Shin H.-D.,Korea University
Phytotaxa | Year: 2017

This paper presents the first checklist of pathogenic fungi on woody plants in North Korea. The checklist enumerates 146 species of fungi belonging to 79 genera, growing on 108 host plants belonging to 58 genera and 35 families. Two hosts and 57 fungal species represent first records in North Korea. © 2017 Magnolia Press.


Malik P.,Slovak Academy of Sciences
Computing and Informatics | Year: 2016

New hardware FPGA implementations for the efficient computations of division, natural logarithm and exponential function are proposed. The proposed implementations use generic floating-point adder and multiplier with small additional resources that are shared to compute more frequently used multiply and accumulate operations. Hardware sharing improved the resource utilization. The time of the computation has been reduced to only G clock cycles when the natural logarithm and exponential function are calculated. The division is calculated in 5 clock cycles. They are designed as technology independent high throughput computing cores with minimized memory requirements which can be used in higher numbers to significantly increased calculation speed in spectral processing. A new universal arithmetic floating-point unit is also proposed.


Farkasovsky P.,Slovak Academy of Sciences
Physical Review B - Condensed Matter and Materials Physics | Year: 2017

The density-matrix-renormalization-group method and the Hartree-Fock approximation with the charge-density-wave instability are used to study a formation and condensation of excitonic bound states in the generalized Falicov-Kimball model. In particular, we examine effects of various factors, such as the f-electron hopping, the local and nonlocal hybridizations, as well as the increasing dimension of the system on the excitonic momentum distribution N(q) and especially on the number of zero-momentum excitons N0=N(q=0) in the condensate. It is found that the negative values of the f-electron hopping integrals tf support the formation of a zero-momentum condensate, whereas the positive values of tf have the fully opposite effect. The opposite effects on the formation of the condensate exhibit also the local and nonlocal hybridizations. The first one strongly supports the formation of the condensate, whereas the second one destroys it completely. Moreover, it was shown that the zero-momentum condensate remains robust with increasing dimension of the system. © 2017 American Physical Society.


Hricko J.,Slovak Academy of Sciences | Havlik S.,Slovak Academy of Sciences
Mechanisms and Machine Science | Year: 2017

This paper deals with the design of the flexural body for a two axis force/displacement sensor based on electro-magnetic sensing principle. The compact elastic structure consists of two independent parallelograms that provide decoupled flexural motions of sensing elements in two rectangular directions. The procedure proceeds by experimental verification of this new sensing principle for building sensors that exhibit specific functional features. © Springer International Publishing Switzerland 2017.


Rusko M.,Slovak Academy of Sciences | Finke M.,German Aerospace Center
7th IEEE International Conference on Cognitive Infocommunications, CogInfoCom 2016 - Proceedings | Year: 2016

This document describes the concept of an air traffic management security system and current validation activities. This system uses on one hand speech analysis techniques to verify the speaker authorization and measure the stress level within the air-ground voice communication between pilots and air traffic controllers; on the other hand it monitors the current air traffic situation. The purpose of this system is to close an existing security gap by using this multi-modal approach. First validation results are discussed at the end of this paper. © 2016 IEEE.


Vaclav R.,Slovak Academy of Sciences | Kolnikova Z.,Comenius University
Biologia (Poland) | Year: 2017

One of the open problems in evolutionary ecology is signal reliability. While the view that signals need to be costly to be honest has attracted most attention, this type of signals may apply only to some contexts. Also, different views exist about the nature of costs involved in signal honesty, and the classification and examination of these costs remains controversial. Pigmentarybased colouration of animal integuments has received considerable attention among researchers seeking to explain what maintains the honesty of visual signals, but support for existing hypotheses is far from conclusive. Here we use a whole-animal approach and consider a distinct time scale, the period of juvenile growth, to test the effects of different feeding and thermal regimes on different physical parameters and skin colouration in corn snakes Pantherophis guttatus. Postnatal body length growth rate and body mass index (BMI) were sensitive to the thermal, but not to the food regime. The length of intervals between skin shedding was shorter and the short-wavelength reflectance of dorsal skin was higher for snakes receiving food more frequently and having an uninterrupted possibility to thermoregulate. This work suggests that if juvenile corn snakes are environmentally constrained, their preferred life history strategy is to grow at faster rates. The study adds to the growing body of evidence in that BMI may not accurately reflect individual condition in reptiles. Instead, this study demonstrates that the length of shedding intervals and the short-wavelength component of skin colouration may be used in this animal system as proxies of the individual's condition or quality, possibly reflecting exposure to environmental stress or an ability to cope with it. © 2017 Institute of Zoology, Slovak Academy of Sciences.


Pajorova E.,Slovak Academy of Sciences | Hluchy L.,Slovak Academy of Sciences
WMSCI 2016 - 20th World Multi-Conference on Systemics, Cybernetics and Informatics, Proceedings | Year: 2016

In our institute in the scope of lot international projects we have developed some 3D visualization tools for present simulation results for applications on the field of astronomical main research and research in natural disasters or disasters in public buildings, before fire, floods, blackout and bombs. The main off all is form of presentation such results for all community, not only for researchers. One of the communities that it wishes to engage in the research process as any other pupil are hearing impaired people. In simultaneous communication forms of this stage of development it is main problem. The benefit of this article is a draft communication methods for this community with using virtual speaking head and perfect vizemas. Currently we are working in creating the final communication and presentation tool for all. The paper describe the part of them, describe all modules, functionality and usefulness of the final communication tool for hearing impared pupil.


Benko V.,Slovak Academy of Sciences | Benko V.,Comenius University
10th Workshop on Recent Advances in Slavonic Natural Language Processing, RASLAN 2016 - Proceedings | Year: 2016

Our paper is targeted at our experiences with a set of tools developed at the Masaryk University in Brno Faculty of Informatics, and it presents a case study describing our Autumn 2016 web crawl and its subsequent processing for the Araneum Slovacum Maximum web corpus. © Tribun EU 2016.


Lofaj F.,Slovak Academy of Sciences | Nemeth D.,Slovak Academy of Sciences
Journal of the European Ceramic Society | Year: 2017

Stress evolution and subsequent cohesive cracking in the hard and stiff W-C coating on steel substrate during nanoindentation have been investigated using finite element modelling (FEM) and eXtended FEM (XFEM). The FEM simulations showed that the maximum principal stresses in the studied system were tensile and always located in the coating. They evolved in several stages. At indentation depths below 15% of the relative indentation depth, the maximum principal tensile stresses of ∼3. GPa developed at the top surface of the coating along the indenter/coating interface. At relative depths range 15-60%, the maximum tensile stresses of ∼6-8. GPa concentrated under the indenter tip in the coating along the interface with the substrate. At relative depths exceeding 60%, the maximum stresses gradually increased up to 10. GPa and they were located in the sink-in zone outside the indent as well as below the indenter tip. The first and subsequent cohesive cracks developed when the maximum tensile stresses in the sink-in zone at the top surface of the coating (and at the coating/substrate interface under the indenter) repeatedly reached the ultimate tensile strength of the coating. The hardness profile as well as cohesive cracking is controlled by the deformation of the substrate defined by the ration of the yield stresses of the coating and substrate. Very good correlation between the experimentally obtained cracks and multiple cracks predicted by XFEM confirmed the ability of the applied modelling in the prediction of fracture behavior of the studied coating/substrate system. © 2017 Elsevier Ltd.


Svehlikova J.,Slovak Academy of Sciences | Tysler M.,Slovak Academy of Sciences
Computing in Cardiology | Year: 2016

Comparison of the localization error of inverse estimation of the origin of premature ventricular contraction using three different formulations of transfer matrix between the equivalent source and the surface potentials was performed in this study. Body surface potential maps measured in 63 precordial leads during nine spontaneous PVCs in one patient provided by Karlsruhe Institute of Technology in EDGAR database were used as input data. The localization error was evaluated with respect to two reference points PVC1 and PVC2 assigned during the ablation procedure. The transfer matrices for epicardial potentials, transmembrane voltages and dipoles situated on the joined endo-and-epicardial surface were used for inverse computation searching the best single point generator representing the input data For all nine considered PVCs the locations of the inverse results were very stable - for particular transfer matrix they resulted in the same point or in adjoining points for all cases. Mean localization error with respect to PVC1 or PVC2 was from 21.3 to 26.2 mm and from 15.0 to 26.4 mm respectively. The results obtained by inverse solution supposing single point source were similar regardless of the source formulation. © 2016 CCAL.


Jencova A.,Slovak Academy of Sciences
Journal of Physics A: Mathematical and Theoretical | Year: 2017

It is known that a necessary and sufficient condition for equality in the data processing inequality (DPI) for the quantum relative entropy is the existence of a recovery map. We show that equality in DPI for a sandwiched Rényi relative α-entropy with is also equivalent to this property. For the proof, we use an interpolating family of L p-norms with respect to a state. © 2017 IOP Publishing Ltd.


Harencarova H.,Slovak Academy of Sciences
Journal of Cognitive Engineering and Decision Making | Year: 2017

The objective of this article is to improve the understanding of uncertainty in paramedics' work and the strategies they employ to manage uncertainty, and to provide a resource for training novices. Managing uncertainty is an important part of paramedic decision making and may have a direct impact on patient's health. Yet, uncertainty has not been sufficiently examined in the naturalistic decision-making paradigm. Therefore, in this study I looked at the uncertainty paramedics have to deal with in nonroutine situations and the strategies they use to manage it. I conducted critical decision method interviews with nine paramedics from paramedic-only ambulance crews. To study uncertainty and coping strategies, I used the RAWFS (reduction, assumption-based reasoning, weighing pros and cons, forestalling, and suppression) heuristic framework. As hypothesized, types of uncertainty were predicted by incident phase, and the coping strategies were predicted by both incident phase and type of uncertainty. The most prevalent type of uncertainty was inadequate understanding of the situation, and the strategy most used to manage uncertainty was reduction. I describe specific examples of cases of uncertainty and the strategies used by paramedics, with the aim of providing materials for training the novices. © 2016, Human Factors and Ergonomics Society.


Podhorsky D.,Slovak Academy of Sciences | Fabo P.,University of Zilina
Contributions to Geophysics and Geodesy | Year: 2016

The article deals with a method of acquiring the temporal and spatial distribution of local precipitation from measurement of performance characteristics of local sources of high frequency electromagnetic radiation in the 1-3GHz frequency range in the lower layers of the troposphere up to 100 m. The method was experimentally proven by monitoring the GSM G2 base stations of cell phone providers in the frequency range of 920-960MHz using methods of frequential and spatial diversity reception. Modification of the SART method for localization of precipitation was also proposed. The achieved results allow us to obtain the timeframe of the intensity of local precipitation in the observed area with a temporal resolution of 10 sec. A spatial accuracy of 100m in localization of precipitation is expected, after a network of receivers is built. The acquired data can be used as one of the inputs for meteorological forecasting models, in agriculture, hydrology as a supplementary method to ombrograph stations and measurements for the weather radar network, in transportation as part of a warning system and in many other areas. © 2017 by Dušan Podhorský.


Harbulakova V.O.,Technical University of Košice | Estokova A.,Technical University of Košice | Luptakova A.,Slovak Academy of Sciences
Energy Procedia | Year: 2017

The paper presents the results of leaching tests of concrete samples with 5 wt. % cement's replacement by fly ash and applies the statistical approach to an interpretation the results. Concrete samples with of two types of fly ashes, originating from anthracite and lignite burning, respectively were exposed to solution of Al2(SO4)3 to sulphate corrosion testing. Deterioration process was manifested by leaching the elementary components of concrete (Ca, Si, Fe, Al) and particular pH changes of leachates in 5 cycles. The leached-out concentrations of elements from concrete matrix measured by X-ray fluorescence method (XRF) and measured pH values were used for the subsequent statistical analysis. A dependency between pH of leachates and leaching trends of Ca and Al, respectively, was confirmed. The correlation coefficients ranged from 0.79 to 0.85. No significant differences between durability of concrete materials based on black or brown-coal fly ashes regarding to leachability were noticed. © 2017 The Authors.


Czimerova A.,Slovak Academy of Sciences | Sas S.,Comenius University | Ceklovsky A.,Slovak Academy of Sciences
Applied Clay Science | Year: 2017

The present study is primarily focused on the investigation of spectral properties of cationic cyanine dye (1,1′-diethyl-4, 4′-carbocyanine iodide, denoted as “NK5”) adsorbed into the structure of synthetic clay mineral (Sumecton SA, denoted as “SUM”) as a host matrix. The hybrid systems were investigated by means of absorption and fluorescence spectroscopy. Beside the solvent effect, the influence of dye/saponite ratio on the formation of specific dye species was studied in detail. It was found that used solvents have greatly affected the spectral properties of prepared hybrids. The NK5/saponite systems in ethanol and methanol were dominated by isolated dye cations. In the NK5/saponite systems in acetone and acetonitrile, the formation of higher aggregates was significantly suppressed. Moreover, the fluorescence spectra showed evidence of the formation of highly fluorescent J-aggregates. Finally, the fluorescence quantum yields of the NK5/saponite systems in various solvents were calculated. It was found that polar protic solvents as ethanol and methanol could stabilize the hybrid cyanine/saponite system with higher quantum yields as in case of used aprotic solvents. © 2017 Elsevier B.V.


Cherry P.J.,Slovak Academy of Sciences | Rouf S.A.,University of Oulu | Vaara J.,University of Oulu
Journal of Chemical Theory and Computation | Year: 2017

We present a derivation and computations of the paramagnetic enhancement of the nuclear magnetic resonance (NMR) spin-spin coupling, which may be expressed in terms of the hyperfine coupling (HFC) and (for systems with multiple unpaired electrons) zero-field splitting (ZFS) tensors. This enhancement is formally analogous to the hyperfine contributions to the NMR shielding tensor as formulated by Kurland and McGarvey. The significance of the spin-spin coupling enhancement is demonstrated by using a combination of density-functional theory and correlated ab initio calculations, to determine the HFC and ZFS tensors, respectively, for two paramagnetic 3d metallocenes, a CrII(acac)2 complex, a Co(II) pyrazolylborate complex, and a lanthanide system, Gd-DOTA. Particular attention is paid to relativistic effects in HFC tensors, which are calculated using two methods: a nonrelativistic method supplemented by perturbational spin-orbit coupling corrections, and a fully relativistic, four-component matrix-Dirac-Kohn-Sham approach. The paramagnetic enhancement lacks a direct dependence on the distance between the coupled nuclei, and represents more the strength and orientation of the individual hyperfine couplings of the two nuclei to the spin density distribution. Therefore, the enhancement gains relative importance as compared to conventional coupling as the distance between the nuclei increases, or generally in the cases where the conventional coupling mechanisms result in a small value. With the development of the experimental techniques of paramagnetic NMR, the more significant enhancements, e.g., of the 13C13C couplings in the Gd-DOTA complex (as large as 9.4 Hz), may eventually become important. © 2017 American Chemical Society.


Osvald J.,Slovak Academy of Sciences
ASDAM 2016 - Conference Proceedings, 11th International Conference on Advanced Semiconductor Devices and Microsystems | Year: 2016

AlGaN/GaN based heterostructure on which transistor active elements are widely studied may be also used for preparation of devices which protect the circuits against external voltage surge. Such devices are called varactors and consist of two back-to-back connected Schottky diodes. We have studied current-voltage and capacitance-voltage characteristics of two back-to-back connected MIS (Metal Insulator Semiconductor) diodes. It is shown that the C-V curves of such a varactor structure are influenced by the I-V curves since the direct current polarization of both diodes are dependent on the relation between forward and reverse currents flowing through the diodes. © 2016 IEEE.


Ambainis A.,University of Latvia | Iraids J.,University of Latvia | Nagaj D.,Slovak Academy of Sciences
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2017

In the exact quantum query model a successful algorithm must always output the correct function value. We investigate the function that is true if exactly k or l of the n input bits given by an oracle are 1. We find an optimal algorithm (for some cases), and a nontrivial general lower and upper bound on the minimum number of queries to the black box. © Springer International Publishing AG 2017.


Sladek J.,Slovak Academy of Sciences | Sladek V.,Slovak Academy of Sciences | Hrcek S.,University of Zilina | Pan E.,University of Akron
Composite Structures | Year: 2017

The von Karman large deformations are considered in the Mindlin plate theory described by the nonlocal and gradient elasticity for piezoelectric nanoplates. It is shown that electric intensity vector can be expressed by mechanical quantities. The governing equations for bending moments, normal and shear stresses are derived from the variational principle. The finite element method is developed for considered governing equations. Differences of both theories are presented. © 2017 Elsevier Ltd


The study presents descriptions of four new species of mites in the subgenus Pachylaelaps (Longipachylaelaps) Mašán, 2007 (Acari, Pachylaelapidae), based on females and males collected in forest habitats from the Bergamasque Alps and Prealps, Northern Italy. The new species are P. (L.) abludens sp. nov., P. (L.) bergomensis sp. nov., P. (L.) marcovallei sp. nov., and P. (L.) pantinii sp. nov. New species identification keys are provided for males and females. Copyright © 2017 Magnolia Press.


Pogany Simonova M.,Slovak Academy of Sciences | Laukova A.,Slovak Academy of Sciences
World Rabbit Science | Year: 2017

Information concerning the virulence factor genes and antibiotic resistance of rabbit enterococci is limited, so in this study we tested the virulence factor genes in Enterococcus faecalis strains from rabbits. Moreover, their resistance/sensitivity to antibiotics and sensitivity to enterocins was also tested, with the aim of contributing to our enterocin spectra study and to indicate the possibility of enterocin application in prevention or contaminant elimination in rabbit husbandry. A total of 144 rabbit samples were treated using a standard microbiological method. Thirty-one pure colonies of the species Enterococcus faecalis were identified, using the MALDI-TOF identification system and confirmed using phenotyping, among which 15 strains were virulence factor gene absent. The gelE gene was the most detected (42%); however, the expression of gelatinase phenotype did not always correlate with the detection of gelE. Strains did not show .-haemolysis and were mostly resistant to tested antibiotics, but sensitive to enterocins (Ent), mainly to Ents EK13=A (P), 2019 and Ent M. Rabbit E. faecalis strains displayed antibiotic resistant traits and the presence of expressed and silent virulence genes, but they showed high levels of sensitivity to natural antimicrobials-enterocins, which indicates the possible prevention of multidrug and virulent enterococcal contaminants by enterocins. © WRSA, UPV, 2003.


Filip P.,Slovak Academy of Sciences
Journal of Physics: Conference Series | Year: 2017

We suggest that fast neutral meson oscillations may occur in a dense baryonic matter, which can influence the balance of s/s quarks in the nucleus-nucleus and proton-nucleus interactions, if primordial multiplicities of neutral K 0, mesons are sufficiently asymmetrical. The phenomenon can occur even if CP symmetry is fully conserved, and it may be responsible for the enhanced sub-threshold production of multi-strange hyperons observed in the low-energy A+A and p+A interactions. © Published under licence by IOP Publishing Ltd.


Colella D.,CERN | Colella D.,Slovak Academy of Sciences
Journal of Physics: Conference Series | Year: 2017

The main goal of the ALICE experiment is to study the properties of the hot and dense medium created in ultra-relativistic heavy-ion collisions. The measurement of the (multi-)strange particles is an important tool to understand particle production mechanisms and the dynamics of the quark-gluon plasma (QGP). We report on the production of KS0, λ(λ), ξ-(ξ+) and ω(ω+) in proton-lead (p{Pb) collisions at p sNN = 5.02 TeV and lead-lead (Pb{Pb) collisions at p sNN = 2.76 TeV measured by ALICE at the LHC. The comparison of the hyperon-to-pion ratios in the two colliding systems may provide insight into strangeness production mechanisms, while the comparison of the nuclear modification factors helps to determine the contribution of initial state effects and the suppression from strange quark energy loss in nuclear matter.


Sator L.,Slovak Academy of Sciences | Sladek V.,Slovak Academy of Sciences | Sladek J.,Slovak Academy of Sciences
Composite Structures | Year: 2017

New coupling effects are revealed and described in plates with multi-gradation of material coefficients. Three variants of plate bending theory (such as the Kirchhoff-Love theory, the 1st and 3rd order shear deformation plate theory) are considered within unified formulation. It is known that transversal gradation of Young's modulus gives rise to coupling between the bending and in-plane deformation modes in plates under transversal loading. In this paper it is shown that combination of transversal gradation of Young's modulus with in-plane gradation of Young's modulus and/or variation of plate thickness leads to deflections of such plates subject to in-plane loading. The governing equations and boundary conditions for static problems are derived in the unified formulation using the variational principle. For numerical simulations of multi-gradation coupling effects, it is developed the strong formulation with using the meshless approximation of field variables by the Moving Least Square (MLS) approximation. Several numerical examples are presented for illustration of the multi-gradation coupling effects in bending of elastic FGM (Functionally Graded Material) plates. The role of the boundary conditions as well as the thickness and shear deformations is studied via numerical simulations and comparisons of the plate responses obtained in three plate bending theories. © 2017 Elsevier Ltd


Rahmati S.,University of Toronto | Abovsky M.,University of Toronto | Pastrello C.,University of Toronto | Jurisica I.,University of Toronto | Jurisica I.,Slovak Academy of Sciences
Nucleic Acids Research | Year: 2017

Molecular pathway data are essential in current computational and systems biology research. While there are many primary and integrated pathway databases, several challenges remain, including low proteome coverage (57%), low overlap across different databases, unavailability of direct information about underlying physical connectivity of pathway members, and high fraction of protein-coding genes without any pathway annotations, i.e. 'pathway orphans'. In order to address all these challenges, we developed pathDIP, which integrates data from 20 source pathway databases, 'core pathways', with physical protein-protein interactions to predict biologically relevant protein-pathway associations, referred to as 'extended pathways'. Cross-validation determined 71% recovery rate of our predictions. Data integration and predictions increase coverage of pathway annotations for protein-coding genes to 86%, and provide novel annotations for 5732 pathway orphans. PathDIP (http://ophid.utoronto.ca/pathdip) annotates 17 070 protein-coding genes with 4678 pathways, and provides multiple query, analysis and output options. © 2016 The Author(s).


Malik P.,Slovak Academy of Sciences
NORCAS 2016 - 2nd IEEE NORCAS Conference | Year: 2016

New floating-point co-processor computing natural logarithm, division and MACs is presented. The co-processor hardware architecture is optimized to high throughput 32-bit floating-point single precision computations. The co-processor is technology independent. It is implemented in FPGA. The co-processor generates new natural logarithm result in every 6 clock cycles and new division result in every 5 clock cycles. The proposed co-processor is oriented and designed for high computational demanding signal processing applications. © 2016 IEEE.


News Article | May 7, 2017
Site: motherboard.vice.com

This is a series around POWER, a Motherboard 360/VR documentary about nuclear energy. Follow along here. Comic book logic dictates that a high dose of radiation will turn you in the Hulk, Godzilla, Radioactive Man, or any number of other radiation-induced superbeings. In real life, it's more likely to be a cause of deleterious mutations than a shortcut to enhanced abilities, as shown by major ecological damage in nuclear meltdown fallout zones, like Chernobyl and Fukushima. These contaminated regions have become a popular destination for scientists interested in the immediate and long-term impact of radiation on wildlife, which has led to the formation of intriguing niche disciplines, like radioecology and radiobiology. Watch more on Motherboard in 360/VR: Nuclear From Above Understanding how living organisms adapt to radiation doses has a range of applications, from medicine to conservation, but one of the most overlooked is preparation for long-duration human space missions and interplanetary colonization, both of which involve sustained exposure to higher radiation doses than what we experience on Earth's surface. An experiment conducted on the International Space Station (ISS) last year examined this idea with the help of eight fungi species sourced from the Chernobyl exclusion zone. These strains sprung up in the wake of the 1986 meltdown, and two of them— Cladosporium moulds—seem to prefer radioactive surfaces. The fungal samples were curated by a team led by Kasthuri Venkateswaran, a senior research scientist at NASA's Jet Propulsion Laboratory, who goes by Venkat for short. Read More: Chernobyl Microbes Are Heading to the International Space Station "The radiation seen at Chernobyl is high, but this black fungi popped up first [after the meltdown] compared even to the bacteria," Venkat told me over the phone. "That is how we selected those fungi, from such a radiation-rich environment. These fungi persisted due to some sort of protein-coding and biomolecule information that protect against the radiation level." Would ingesting such a hardy mould give one radioactive superpowers? Not quite—or more accurately, not yet. The eventual goal of Venkat's research is to develop a fungi-based "sunblock" for outer space radiation that could be used to protect humans from the harmful effects of long-term exposure. The fungi was returned to Earth just a few months ago, so the results are preliminary, but Venkat and his colleagues are eager to pursue the research further. "We have to take all the precautions before building a human habitation on Mars and beyond," he told me. In addition to helping humans become more radiation-resistant, studying the wildlife in fallout regions can also yield insight into engineering crops that can survive the radiation environment beyond Earth—especially highly irradiated worlds like those in the Jupiter system. The Chernobyl exclusion zone is significantly more radioactive than the interior of proposed long-duration spacecraft, which makes it a bad direct analogy to outer space. But the ways in which crops develop tolerance to contaminated environments is rich with clues about surviving sustained doses of cosmic radiation. "Radiation-resistant genes can be incorporated into yeast cells that produce beer so that humans are willing to go to space—they will have a better beer to drink," Venkat said, as one example. Fallout zones are also useful testbeds for studying astrobiological questions about the search for aliens on other worlds, and the origins of life on our own planet. Flax crops grown at Chernobyl in the decades since the meltdown have demonstrated increasing resistance to contamination, for instance, leading some researchers to wonder if their genes are a kind of vestigial time capsule to the dawn of life on Earth. "My favorite speculation is that when life on Earth was evolving, radioactivity was much more present on Earth's surface than is today," Martin Hajduch, a senior scientist at the Slovak Academy of Sciences' Institute of Plant Genetics and Biotechnology, said of his research into Chernobyl flax. "And so the plants are somehow 'remembering' it, [which is] what helped them to adapt in Chernobyl's radioactive area." In this way, the world's worst nuclear disasters, which have threatened the health of our planet, may now help us understand our origins on Earth, and learn to survive the harsh conditions beyond it. Subscribe to Science Solved It, Motherboard's new show about the greatest mysteries that were solved by science.


Halada L.,Slovak Academy of Sciences | Evans D.,French Natural History Museum | Romao C.,European Environment Agency | Petersen J.-E.,European Environment Agency
Biodiversity and Conservation | Year: 2011

The aim of this paper is to identify the habitat types listed in the Habitats Directive Annex I that require low-intensity agricultural management for their existence. We assessed the link between the Annex I habitat types and agricultural practices in order to identify habitat types that depend on the continuation of agricultural practices or whose existence is prolonged or spatially enlarged via blocking or reducing the secondary succession by agricultural activities. 63 habitat types that depend on or which can profit from agricultural activities-mainly grazing and mowing-were identified. They are classified into 2 groups: (1) habitats fully dependent on the continuation of agricultural management; (2) habitats partly dependent on the continuation of agricultural management. This paper also briefly discusses habitat types for which either doubts remain on their dependence on agricultural management, or the relation to extensive farming practices exists only in part of their area of distribution in Europe or under certain site conditions, respectively. Assessments of the conservation status of habitats of European Importance by 25 EU Member States in 2007 showed that habitats identified by us as depending on agricultural practices had a worse status than non-agricultural habitats. © 2011 Springer Science+Business Media B.V.


Galleano M.,University of Buenos Aires | Pechanova O.,Slovak Academy of Sciences | Fraga C.G.,University of Buenos Aires | Fraga C.G.,University of California at Davis
Current Pharmaceutical Biotechnology | Year: 2010

Fruits and vegetables are key foods whose high ingestion is associated with the improvement of numerous pathological conditions, including hypertension. Such health promoting actions have been increasingly ascribed to the antioxidant characteristics of different polyphenols in fruits and vegetables. Consequently, based on this assumption, many beverages and foods rich in polyphenols, grape, tea, cocoa, and soy products and many of their chemical constituents purified, are being studied both, as antioxidants and antihypertensive agents. This paper reviews the current evidence linking high polyphenol consumption with reductions in blood pressure. Basic chemical aspects of flavanols, flavonols, isoflavones and stilbenes, as possible responsible for the observed effects of those foods on blood pressure are included. Human intervention studies by using grapes and wine, cocoa and chocolate, black and green tea, soy products, and purified compounds ((+)-catequin, quercetin, (-)-epigallocatechin gallate) are summarized. The discussed hypothesis, strongly supported by experimental data in animals, is that by regulating nitric oxide bioavailability, polyphenols present in fruits and vegetables affect endothelial function and as a consequence, blood pressure. Even when data are not definitive and many questions remain open, the whole evidence is encouraging to start considering diets that can provide benefits to hypertensive subjects, and those benefits will be more significant in people that do not have controlled his/her elevated blood pressure. © 2010 Bentham Science Publishers Ltd.


Garcia J.A.,Autonomous University of Madrid | Glasa M.,Slovak Academy of Sciences | Cambra M.,Instituto Valenciano Of Investigaciones Agrarias Ivia | Candresse T.,French National Institute for Agricultural Research
Molecular Plant Pathology | Year: 2014

Summary: Taxonomic relationships: Plum pox virus (PPV) is a member of the genus Potyvirus in the family Potyviridae. PPV diversity is structured into at least eight monophyletic strains. Geographical distribution: First discovered in Bulgaria, PPV is nowadays present in most of continental Europe (with an endemic status in many central and southern European countries) and has progressively spread to many countries on other continents. Genomic structure: Typical of potyviruses, the PPV genome is a positive-sense single-stranded RNA (ssRNA), with a protein linked to its 5' end and a 3'-terminal poly A tail. It is encapsidated by a single type of capsid protein (CP) in flexuous rod particles and is translated into a large polyprotein which is proteolytically processed in at least 10 final products: P1, HCPro, P3, 6K1, CI, 6K2, VPg, NIapro, NIb and CP. In addition, P3N-PIPO is predicted to be produced by a translational frameshift. Pathogenicity features: PPV causes sharka, the most damaging viral disease of stone fruit trees. It also infects wild and ornamental Prunus trees and has a large experimental host range in herbaceous species. PPV spreads over long distances by uncontrolled movement of plant material, and many species of aphid transmit the virus locally in a nonpersistent manner. Sources of resistance: A few natural sources of resistance to PPV have been found so far in Prunus species, which are being used in classical breeding programmes. Different genetic engineering approaches are being used to generate resistance to PPV, and a transgenic plum, 'HoneySweet', transformed with the viral CP gene, has demonstrated high resistance to PPV in field tests in several countries and has obtained regulatory approval in the USA. © 2013 BSPP AND JOHN WILEY & SONS LTD.


Planat M.,FEMTO ST Institute | Saniga M.,Slovak Academy of Sciences | Holweck F.,University of Technology of Belfort - Montbéliard
Quantum Information Processing | Year: 2013

Disregarding the identity, the remaining 63 elements of the generalized three-qubit Pauli group are found to contain 12096 distinct copies of Mermin's magic pentagram. Remarkably, 12096 is also the number of automorphisms of the smallest split Cayley hexagon. We give a few solid arguments showing that this may not be a mere coincidence. These arguments are mainly tied to the structure of certain types of geometric hyperplanes of the hexagon. It is further demonstrated that also an (182, 123) -type of magic configurations, recently proposed by Waegell and Aravind (J Phys A Math Theor 45:405301, 2012), seems to be intricately linked with automorphisms of the hexagon. Finally, the entanglement properties exhibited by edges of both pentagrams and these particular Waegell-Aravind configurations are addressed. © 2013 Springer Science+Business Media New York.


Williams A.M.,University of Surrey | Balaz V.,Slovak Academy of Sciences
Journal of Risk Research | Year: 2014

Migration is a risky behaviour because of the uncertainty about future wages, living conditions, changing relationships with family and friends and cultural adjustment. While there has been some research on risk and uncertainty in migration, this has mostly been approached as a form of rational decision-making: such approaches explain why some groups of individuals are more likely than others to migrate, but are limited in explaining individual variations in behaviour within these groups. Individual migrants vs. non-migrants are self-selected in terms of tolerance of risk and uncertainty but, with very few exceptions, there has been no research on migration within the framework of risk tolerance/aversion and competence to manage risk. Moreover, existing research is based on, and constrained by the limitations of, incumbent data-sets. Drawing on a specially commissioned large-scale survey of the UK population, this paper uses principal component analysis and logistic regression to analyse the extent to which risk and risk-related measures can be used to predict four different types of mobility profiles. There are significant associations between these individual mobility characteristics and general risk/uncertainty tolerance, and competence-based tolerance. These are strongest in terms of the two most polarised mobility types: the least mobile, the Stayers, and the most mobile, the Roamers. Recognising that previous migration is exogenous, a further analysis of migration intentions, with previous migration included as an independent variable, finds the propensity for future migration is, in fact, negatively associated with previous migration, probably due to the importance of pure risk as opposed to acquired competence via migration experience, and to life cycle considerations. © 2013 Taylor and Francis.


Rokstad A.M.A.,Norwegian University of Science and Technology | Rokstad A.M.A.,The Central Norway Health Authority RHA | Lacik I.,Slovak Academy of Sciences | de Vos P.,University of Groningen | And 2 more authors.
Advanced Drug Delivery Reviews | Year: 2014

Cell encapsulation has already shown its high potential and holds the promise for future cell therapies to enter the clinics as a large scale treatment option for various types of diseases. The advancement in cell biology towards this goal has to be complemented with functional biomaterials suitable for cell encapsulation. This cannot be achieved without understanding the close correlation between cell performance and properties of microspheres. The ongoing challenges in the field of cell encapsulation require a critical view on techniques and approaches currently utilized to characterize microspheres. This review deals with both principal subjects of microspheres characterization in the cell encapsulation field: physico-chemical characterization and biocompatibility. The up-to-day knowledge is summarized and discussed with the focus to identify missing knowledge and uncertainties, and to propose the mandatory next steps in characterization of microspheres for cell encapsulation. The primary conclusion of this review is that further success in development of microspheres for cell therapies cannot be accomplished without careful selection of characterization techniques, which are employed in conjunction with biological tests. © 2013 Elsevier B.V.


Sumbalova Z.,University of Sfax | Kucharska J.,University of Sfax | Kristek F.,Slovak Academy of Sciences
Cellular and Molecular Neurobiology | Year: 2010

Increased production of free radicals and impairment of mitochondrial function are important factors in the pathogenesis of hypertension. This study examined the impact of hypertension on mitochondrial respiratory chain function, coenzyme Q 9 (CoQ 9), coenzyme Q 10 (CoQ 10), and α-tocopherol content in brain mitochondria, and the effect of blockade of angiotensin II type 1 receptors (AT1R) in the prehypertensive period on these parameters. In addition, blood pressure, heart and brain weight to body weight ratios, and the geometry of the basilar artery supplying the brain were evaluated. In the 9th week blood pressure and heart weight/body weight ratio were significantly increased and brain weight/body weight ratio was significantly decreased in spontaneously hypertensive rats (SHR) when compared to Wistar rats (WR). The crosssectional area of the basilar artery was increased in SHR. Glutamate-supported respiration, the rate of ATP production, and concentrations of CoQ 9, CoQ 10, and α-tocopherol were decreased in SHR. The succinate-supported function and cytochrome oxidase activity were not changed. The treatment of SHR with losartan (20 mg/kg/day) from 4th to 9th week of age exerted preventive effect against hypertension, heart and arterial wall hypertrophy, and brain weight/body weight decline. After the therapy, the rate of ATP production and the concentration of CoQ increased in comparison to untreated SHR. The impairment of energy production and decreased level of lipid-soluble antioxidants in brain mitochondria as well as structural alterations in the basilar artery may contribute to increased vulnerability of brain tissue in hypertension. Long-term treatment with AT1R blockers may prevent brain dysfunction in hypertension. © Springer Science+Business Media, LLC 2010.


Czachor H.,Polish Academy of Sciences | Doerr S.H.,University of Swansea | Lichner L.,Slovak Academy of Sciences
Journal of Hydrology | Year: 2010

Soil organic matter can modify the surface properties of the soil mineral phase by changing the surface tension of the mineral surfaces. This modifies the soil's solid-water contact angle, which in turn would be expected to affect its water retention curve (SWRC). Here we model the impact of differences in the soil pore-water contact angle on capillarity in non-cylindrical pores by accounting for their complex pore geometry. Key outcomes from the model include that (i) available methods for measuring the Young's wetting angle on soil samples are insufficient in representing the wetting angle in the soil pore space, (ii) the wetting branch of water retention curves is strongly affected by the soil pore-water contact angle, as manifest in the wetting behavior of water repellent soils, (iii) effects for the drying branch are minimal, indicating that both wettable and water repellent soils should behave similarly, and (vi) water retention is a feature not of only wettable soils, but also soils that are in a water repellent state. These results are tested experimentally by determining drying and wetting branches for (a) 'model soil' (quartz sands with four hydrophobization levels) and (b) five field soil samples with contrasting wettability, which were used with and without the removal of the soil organic matter. The experimental results support the theoretical predictions and indicate that small changes in wetting angle can cause switches between wettable and water repellent soil behavior. This may explain the common observation that relatively small changes in soil water content can cause substantial changes in soil wettability. © 2009 Elsevier B.V. All rights reserved.


Tomasovych A.,Slovak Academy of Sciences | Jablonski D.,University of Chicago | Berke S.K.,Siena College | Krug A.Z.,Flint Hill School | Valentine J.W.,University of California at Berkeley
Global Ecology and Biogeography | Year: 2015

Aim: Species living at latitudes that have greater annual temperature variations are expected to achieve broader geographic ranges than species living at latitudes that have smaller annual temperature variations, generating a positive relationship between range size and latitude (Rapoport's rule). However, this prediction fails to take into account the greater latitudinal extent of tropical temperatures relative to those at higher latitudes. Here we model the contributions of the broader latitudinal extent of equal-temperature habitats at low latitudes and the greater annual temperature variation at high latitudes to the range size-latitude relationship, and test whether the latitudinal variation in geographic range size in marine bivalves can be explained by models that account for both annual temperature variation and the steepness of latitudinal thermal gradients. Location: Western Pacific, eastern Pacific and western Atlantic. Methods: We use a null model where geographic ranges are placed on the ocean surface independently of thermal gradients, and a range-expansion model where the minimum and maximum temperatures encompassed by the geographic range of a species (macroecological thermal ranges) are positively related to annual temperature minima and maxima at the location where the species originated. We compare results with a database containing 40,820 occurrences of 4760 marine bivalve species. Result: Models incorporating temperature-limited range expansion along realistic thermal gradients predict an inverse relationship between range size and latitude, in opposition to Rapoport's rule. The distribution patterns of marine bivalves match this prediction. Main conclusions: The poleward trend in latitudinal range size is determined by the nonlinearity of the latitudinal gradient of temperature minima and maxima and less by the latitudinal gradient of the local seasonal range in temperatures. Although tropical species do have narrower macroecological thermal ranges than high-latitude species, the nearly constant temperatures over wide areas of the tropics allow tropical species to achieve broad latitudinal ranges. © 2014 John Wiley & Sons Ltd.


Novak V.,Slovak Academy of Sciences | Knava K.,Slovak Academy of Sciences | Simunek J.,University of California at Riverside
Geoderma | Year: 2011

Mountainous soils usually contain a large number of rock fragments (particle diameter>2mm), which influence soil hydraulic and retention properties. Data characterizing the properties of these soils usually describe only the fine earth (particle diameter<2mm). To quantitatively describe soil water movement in stony soils, their most important characteristic, i.e., the effective saturated hydraulic conductivity (Kse), must be known. The objective of this study was to use a numerical method for estimating the saturated soil hydraulic conductivity that depends on relative stone content (stoniness), and sizes and shapes of stony parts. The method is based on a numerical version of the classical experiment of Darcy. The steady-state water flow under a unit hydraulic gradient through hypothetical soils containing stones was simulated using the two-dimensional simulation model HYDRUS-2D. Four soil textural types were considered. Special attention was paid to the moraine soil from the FIRE site in High Tatras. A relationship between the relative saturated hydraulic conductivity, Kr, and the relative stone content, Rv, was derived. Kr(Rv) function is decreasing slower for larger stones. Numerical results were used to propose an empirical equation to estimate Kr of soils containing rock fragments of a spherical shape of various diameters. © 2011 Elsevier B.V.


Okuliarova M.,Comenius University | Groothuis T.G.G.,University of Groningen | Skrobanek P.S.,Slovak Academy of Sciences | Zeman M.,Comenius University | Zeman M.,Slovak Academy of Sciences
American Naturalist | Year: 2011

In many animal species, embryos are exposed to maternal hormones that affect their development. Maternal hormone transfer varies with environmental conditions of the mother and is often interpreted as being shaped by natural selection to adjust the offspring to prevailing environmental conditions. Such hormone transfer requires genetic variability, which has not yet been experimentally demonstrated. Our study reports direct evidence for additive genetic variance of maternal androgens through a bidirectional selection on yolk testosterone (T) levels in Japanese quail. Lines selected for high egg T (HET) and low egg T (LET) concentration differed in yolk levels of this androgen, resulting in high realized heritability (h2p 0.42). Correlated responses to selection on other gonadal hormones indicated that selection specifically targeted biologically active androgens. Eggs of HET quail contained higher androstenedione and lower estradiol concentrations than did those of LET quail, with no line differences in yolk progesterone concentration. Plasma T concentrations in adult females were not affected by selection, seriously challenging the hypothesis that transfer of maternal hormones to offspring is constrained by hormone levels in a mother's circulation. Our results suggest that transfer of maternal T represents an indirect genetic effect that has important consequences for the evolution of traits in offspring. © 2011 by The University of Chicago.


Csanadi T.,Slovak Academy of Sciences | Bl'Anda M.,Slovak Academy of Sciences | Chinh N.Q.,Eötvös Loránd University | Hvizdos P.,Slovak Academy of Sciences | And 2 more authors.
Acta Materialia | Year: 2015

The orientation dependence of hardness and nanoindentation-induced deformation mechanisms of differently orientated tungsten carbide (WC) grains in WC-Co hardmetal were studied. Electron backscatter diffraction, atomic force microscopy and scanning electron microscopy investigations were performed to determine the grain orientation, and to study the surface morphology and the resulting deformation fields around the indents. The hardness of the differently orientated WC grains showed significant angle dependence from the basal towards the prismatic directions, but there was only a slight change in hardness between the two types of prismatic orientations ((101¯0) and (21¯1¯0)). Sink-in and pile-up effects, together with highly deformed regions and dislocation steps, were revealed around the imprints in the case of basal and prismatic orientations, respectively. A theoretical model is proposed in which the critical force for slip activation is determined as a function of orientation, based on the possible slip systems of WC. The predictions of the present model concerning the measured hardness values and the deformation field around the indents together with the sink-in effect are in good agreement with the experimental results. © 2014 Acta Materialia Inc.


Imrich R.,Slovak Academy of Sciences | Rovensky J.,National Institute of Rheumatic Diseases
Rheumatic Disease Clinics of North America | Year: 2010

The hypothalamic-pituitary-adrenal (HPA) system is a powerful neuroendocrine control mechanism involved in many core body functions including metabolic and energy homeostasis. The HPA axis has been considered an important immune modulator primarily in view of potent anti-inflammatory effects of cortisol in high physiologic and pharmacologic doses. This article describes HPA's role in rheumatoid arthritis. © 2010 Elsevier Inc.


Michalek M.,Slovak Academy of Sciences | Sedlacek J.,Slovak Academy of Sciences | Michalkova M.,Slovak Academy of Sciences | Galusek D.,Slovak Academy of Sciences
Ceramics International | Year: 2014

The alumina/multi-wall carbon nanotubes (MWCNT) and Al2O 3/ZrO2/MWCNT composites with up to 2 vol% of MWCNT were prepared and characterized. The homogeneity of the composite powders was ensured by application of freeze drying and granulation as a method for drying of stabilized aqueous suspensions. The soft spherical granules were hot pressed at 1500 C for 2 h under uniaxial mechanical pressure of 30 MPa to prepare dense composites. The mechanical properties, namely Vickers hardness (HV1) and fracture toughness (K1c), together with DC electrical conductivity (σ) were measured, and compared with the pure alumina reference prepared under similar conditions. Incorporation of 1 vol% of the MWCNT into the alumina, and alumina/zirconia matrices (composites AC and AZC, respectively) lead to the increase of fracture toughness by 8% and 35%, in comparison to the monolithic alumina reference. The electrical conductivity increased from 10-12 S/m in the pure alumina to 2.7×10-1 S/m in the composites containing 2 vol% of the MWCNT. © 2013 Elsevier Ltd and Techna Group S.r.l.


Balaz P.,Slovak Academy of Sciences | Achimovicova M.,Slovak Academy of Sciences | Balaz M.,Slovak Academy of Sciences | Billik P.,Comenius University | And 13 more authors.
Chemical Society Reviews | Year: 2013

The aim of this review article on recent developments of mechanochemistry (nowadays established as a part of chemistry) is to provide a comprehensive overview of advances achieved in the field of atomistic processes, phase transformations, simple and multicomponent nanosystems and peculiarities of mechanochemical reactions. Industrial aspects with successful penetration into fields like materials engineering, heterogeneous catalysis and extractive metallurgy are also reviewed. The hallmarks of mechanochemistry include influencing reactivity of solids by the presence of solid-state defects, interphases and relaxation phenomena, enabling processes to take place under non-equilibrium conditions, creating a well-crystallized core of nanoparticles with disordered near-surface shell regions and performing simple dry time-convenient one-step syntheses. Underlying these hallmarks are technological consequences like preparing new nanomaterials with the desired properties or producing these materials in a reproducible way with high yield and under simple and easy operating conditions. The last but not least hallmark is enabling work under environmentally friendly and essentially waste-free conditions (822 references). © 2013 The Royal Society of Chemistry.


Soltis T.,Slovak Academy of Sciences
Physics of the Earth and Planetary Interiors | Year: 2010

The influence of anisotropic diffusive coefficients on stability of the horizontal fluid planar layer rotating about vertical axis and permeated by a horizontal homogeneous magnetic field is studied. The linear stability analysis is performed using separable solutions in the form of horizontal rolls. Both, stationary and overstable motions, are examined. Two basic cases of anisotropic diffusive processes are considered in the Cartesian coordinate system with the vertical in the z-direction. In the case of stratification anisotropy (SA) the dominant effect on the dynamics is due to density stratification determined by gravity, g = - g over(z, ̂), which is the source of Archimedean buoyancy force. Thus, the diffusive coefficients have different values in the z-direction from those in the horizontal directions, x and y. In the case of Braginsky-Meytlis (BM) anisotropy (Braginsky and Meytlis, 1990) the dominant effect of rotation and magnetic field is supposed. The diffusive coefficients in the z-direction, coinciding with the vector of rotation, Ω = Ω0 over(z, ̂), and in the y-direction of the magnetic field vector, B = Bm over(y, ̂), are greater than in the x-direction. The effect of anisotropy is most evident for values of the Elsasser number similar to those estimated for the Earth's core conditions. Both types of diffusive coefficient anisotropies, SA and BM, are compared and their role either to facilitate or to inhibit rotating magnetoconvection is determined. It was found, that investigated anisotropies influence not only the system stability conditions but also properties of arising instabilities. Two types of anisotropy, SA anisotropy of atmospheric type and BM, facilitate the onset of convection, but SA of oceanic type inhibits it. Our anisotropic studies' results are compared and discussed with isotropic studies by Eltayeb (1972, 1975), Jones and Roberts (2000) and Roberts and Jones (2000). © 2009 Elsevier B.V. All rights reserved.


Gundogdu M.E.,Newcastle University | Kawai Y.,Newcastle University | Kawai Y.,Nara Institute of Science and Technology | Pavlendova N.,Newcastle University | And 6 more authors.
EMBO Journal | Year: 2011

Cytokinesis in bacteria is initiated by polymerization of the tubulin homologue FtsZ into a circular structure at midcell, the Z-ring. This structure functions as a scaffold for all other cell division proteins. Several proteins support assembly of the Z-ring, and one such protein, SepF, is required for normal cell division in Gram-positive bacteria and cyanobacteria. Mutation of sepF results in deformed division septa. It is unclear how SepF contributes to the synthesis of normal septa. We have studied SepF by electron microscopy (EM) and found that the protein assembles into very large (-450 nm diameter) rings. These rings were able to bundle FtsZ protofilaments into strikingly long and regular tubular structures reminiscent of eukaryotic microtubules. SepF mutants that disturb interaction with FtsZ or that impair ring formation are no longer able to align FtsZ filaments in vitro, and fail to support normal cell division in vivo. We propose that SepF rings are required for the regular arrangement of FtsZ filaments. Absence of this ordered state could explain the grossly distorted septal morphologies seen in sepF mutants. © 2011 European Molecular Biology Organization | All Rights Reserved.


Chicardi E.,CSIC - Institute of Materials Science | Torres Y.,University of Seville | Cordoba J.M.,CSIC - Institute of Materials Science | Hvizdos P.,Slovak Academy of Sciences | Gotor F.J.,CSIC - Institute of Materials Science
Materials and Design | Year: 2014

Titanium-tantalum carbonitride, (Ti, Ta)(C, N), based cermets with different Ti and Ta contents were prepared using a mechanically induced self-sustaining reaction and then densified using a pressureless sintering process. Complete microstructural and mechanical characterizations were performed on the materials, which revealed that the size of the carbonitride ceramic particle was significantly reduced when the Ta content was increased. The flexural strength and fracture toughness were measured using the ball on three balls test and the indentation microfracture test, respectively. The strength profile was analyzed under the framework of Weibull theory. The change in the mechanical properties as a function of the Ta content was correlated with the normalized microstructural parameters, such as the binder mean free path. The decrease in toughness and flexural strength was attributed to the presence of intermetallic compounds in the binder phase, which was also corroborated by the nanoindentation tests. © 2013 Elsevier Ltd.


KaluZ S.,Slovak Academy of Sciences
Zootaxa | Year: 2012

Four new oribatid mite species of the superfamily Galumnoidea, Pergalumna paradecoratissima sp. nov., Pergalumna paralongisetosa sp. nov., Pergalumna ecuadorensis sp. nov. and Galumnopsis lanceosensilla sp. nov., are described from Ecuador. The genus Galumnopsis is recorded for the first time for the Ecuador. Pergalumna paradecoratissima sp. nov. is very similar in having the combination of foveolate prodorsum, striate notogaster, setiform sensilli, interlamellar setae shorter than lamellar and rostral setae, absence of anterior notogastral margin and three pairs of notogastral porose areas, to Pergalumna decoratissima Pérez-íñigo and Baggio, 1986 from Brazil, however it differs from the latter by morphology of rostrum, body size, surface of anal plates and length of epimeral setae. Pergalumna paralongisetosa sp. nov. is very similar in having the combination of setiform sensilli, long prodorsal setae, absence of anterior notogastral margin, three pairs of notogastral porose areas and long adanal setae ad1 and ad2 to Pergalumna longisetosa Balogh, 1960 from Central Africa, however it differs from the latter by body size, lengths of sensilli and interlamellar setae, absence of medial pore, length of epimeral setae. Pergalumna ecuadorensis sp. nov. can be distinguished from all similar species by having the round rostrum, setiform sensilli, long and setiform prodorsal setae, absence of anterior notogastral margin, smooth body surface and three pairs of oval notogastral porose areas, and by the very long interlamellar setae. Galumnopsis lanceosensilla sp. nov. can be distinguished from all similar species (with smooth body surface) by the morphology of sensilli which are lanceolate, with tooth in distal part. Copyright © 2012 · Magnolia Press.


Vrabec M.,University of Ljubljana | Janak M.,Slovak Academy of Sciences | Froitzheim N.,Steinmann Institute | De Hoog J.C.M.,University of Edinburgh
Lithos | Year: 2012

Phase relations among the mineral assemblages of UHP kyanite eclogite were investigated in the Pohorje Mountains of the Eastern Alps. Ultrahigh-pressure metamorphism resulted from intracontinental subduction during the Cretaceous (ca. 92Ma). Kyanite-bearing eclogites are associated with meta-ultramafic rocks including UHP garnet peridotites and are embedded in metapelitic gneisses and micaschists. The kyanite eclogites contain a peak metamorphic assemblage of garnet, omphacite, kyanite and phengite. Pyrope-rich garnet is unzoned and almost free of inclusions. The non-stoichiometric supersilicic omphacite contains up to 5mol% of Ca-Eskola molecule. Breakdown of omphacite during decompression resulted in exsolution of oriented rods of silica. Phengite contains up to 3.5 Si a.p.f.u. Polycrystalline quartz inclusions in peak-pressure minerals - garnet, omphacite and kyanite - are surrounded by radial fractures diagnostic of the former presence of coesite. Peak-pressure minerals are replaced by symplectites of diopside+plagioclase+amphibole after omphacite, plagioclase+biotite after phengite and sapphirine+corundum+spinel+anorthite after kyanite. Sapphirine has composition close to (Mg, Fe) 12.4 Al 38.9 Si 4.5 O 80 in average, which is amongst the most aluminous yet reported. Peak metamorphic conditions were constrained from calculated phase equilibria in the NKCFMASH system with the fixed bulk-rock composition, and conventional geothermobarometry. This approach led to consistent results, the calculated peak P-T conditions of 3.0-3.7GPa and 710-940°C, in the stability field of coesite and the same range as metamorphic conditions recorded by the associated garnet peridotites. This implies that eclogites and their host rocks were subducted to depths of about 100km. The relatively high temperature at peak pressure, compared to UHP rocks of Tertiary age in the Western Alps where mostly oceanic crust was subducted, probably resulted from radiogenic heat production by subducting continental crust, in the intra-continental setting of the Cretaceous subduction zone in the Eastern Alps. © 2012 Elsevier B.V.


Grant
Agency: European Commission | Branch: FP7 | Program: CP | Phase: ICT-2011.3.2 | Award Amount: 5.57M | Year: 2011

Highly efficient power electronics is needed for low volume and low weight future power conversion systems. The proposed project aims for the exploitation of novel gallium nitride (GaN) transistors for advanced switched power supplies. High voltage normally-off GaN power devices on Si substrates in vertical device architecture will be developed and its technology transferred to an European industrial environment. The devices are planned to reliably operate at elevated junction temperatures up to 225C. The project covers the full value added chain from substrate technology and epitaxy to complete power electronic system prototypes. It brings together experienced partners in automotive technology, power electronic system and circuit design, power semiconductor technology, high temperature packaging technologies, GaN power device technology including GaN on Si epitaxy as well as sophisticated device characterization and reliability evaluation techniques. Therefore very good prospects for a successful realization of the project targets and for a competitive implementation of the new devices in an industrial environment are seen.


Balaz V.,Slovak Academy of Sciences | Williams A.M.,University of Surrey
Journal of Risk Research | Year: 2011

Although risk and uncertainty are intrinsic to human migration, there is surprisingly little explicit research on the willingness to take risks in this context. This paper analyses whether migrants are more or less likely than non-migrants to be risk tolerant, and whether these differences are gendered. Attitudes are explored in terms of responses under conditions of both risk and uncertainty, and self-assessment of capabilities is also taken into account. The research is based on a sample of students who provide a relatively homogeneous group in socio-economic terms, and relatively large numbers of individuals with experiences of temporary migration. Their attitudes to risk were assessed under experimental conditions, which measured their willingness to take risks on hypothetical gambles under different conditions. While there are some differences between males and females, and between migrants and non-migrants, the outstanding finding is the far greater risk tolerance of female migrants as opposed to female non-migrants, especially when compared to males. © 2011 Taylor & Francis.


Horsak M.,Masaryk University | Hajek M.,Masaryk University | Spitale D.,Museo delle Science | Hajkova P.,Masaryk University | And 4 more authors.
Ecology | Year: 2012

While the effects of contemporaneous local environment on species richness have been repeatedly documented, much less is known about historical effects, especially over large temporal scales. Using fen sites in the Western Carpathian Mountains with known radiocarbon-dated ages spanning Late Glacial to modern times (16 975-270 cal years before 2008), we have compiled richness data from the same plots for three groups of taxa with contrasting dispersal modes: (1) vascular plants, which have macroscopic propagules possessing variable, but rather low, dispersal abilities; (2) bryophytes, which have microscopic propagules that are readily transported long distances by air; and (3) terrestrial and freshwater mollusks, which have macroscopic individuals with slow active migration rates, but which also often possess high passive dispersal abilities. Using path analysis we tested the relationships between species richness and habitat age, area, isolation, and altitude for these groups. When only matrix-derived taxa were considered, no significant positive relation was noted between species richness and habitat size or age. When only calcareous-fen specialists were considered, however, habitat age was found to significantly affect vascular plant richness and, marginally, also bryophyte richness, whereas mollusk richness was significantly affected by habitat area. These results suggest that in inland insular systems only habitat specialist (i.e., interpatch disperser and/or relict species) richness is influenced by habitat age and/or area, with habitat age becoming more important as species dispersal ability decreases. © 2012 by the Ecological Society of America.


Grant
Agency: European Commission | Branch: FP7 | Program: CP | Phase: INFRA-2007-2.1-01 | Award Amount: 6.78M | Year: 2008

This is the project definition for the Conceptual Design Study of the large aperture European Solar Telescope (EST). EST is a pan-European project involving 29 partners from 14 different countries. A consortium EAST (European Association for Solar Telescopes) exists with the aim, among others, of undertaking the development of EST, to keep Europe in the frontier of Solar Physics in the world. EST will be optimised for studies of magnetic coupling between the deep photosphere and upper chromosphere. This will require diagnostics of the thermal, dynamic and magnetic properties of the plasma over many scale heights, by using multiple wavelength imaging, spectroscopy and spectropolarimetry. The EST design will strongly emphasise the use of a large number of visible and near-infrared instruments simultaneously, thereby improving photon efficiency and diagnostic capabilities relative to other existing or proposed ground-based or space-borne solar telescopes. To achieve these goals, EST must specialise in high spatial and temporal resolution using instruments that can efficiently produce two-dimensional spectral information. The study aims at demonstrating the scientific, technical and financial feasibility of EST. It includes key aspects needed for a conceptual design of the whole telescope, such as optomechanical design, cooling mechanisms, adaptive optics, instrumentation and control. Different existing alternatives will be analysed for all systems and subsystems, with decisions taken on the most adequate ones that are compatible with the scientific goals and the technical strategies. Technical specifications will be given at the end of the Design Study for all systems and subsystems.


Grant
Agency: European Commission | Branch: H2020 | Program: RIA | Phase: INFRAIA-1-2014-2015 | Award Amount: 5.00M | Year: 2015

A collective effort is needed to create the environmental research infrastructure for answering pressing questions in a world of rapid social, economic and environmental change. The overall aim of the eLTER project is to advance the European network of Long-Term Ecosystem Research sites and socio-ecological research platforms to provide highest quality services for multiple use of a distributed research infrastructure. eLTERs major objectives and methods are to: (1) identify user needs for the research infrastructure in relation to major societal challenges through consultations with scientific, policy and business stakeholders and horizon scanning; (2) streamline the design of a cost-efficient pan-European network, able to address multiple ecosystem research issues, in collaboration with related global and European research infrastructures, e.g. LifeWatch; (3) develop the organisational framework for data integration and enable virtual access to the LTER data by enabling data publishing through distributed Data Nodes and by providing access to data on key research challenges through a Data Integration Platform; (4) foster the societal relevance, usability and multiple use of information, data and services through new partnerships with the providers of remotely sensed data, analytical services and scenario testing models, and via the adoption of new measurement technologies. The LTER-Europe network and the European Critical Zone community will collaborate to achieve these goals. 162 sites in 22 countries will provide data on long-term trends in environmental change, some reaching back 100 years. Test cases using these data will address a range of environmental and social issues to push innovation in network level services and steer conceptual developments. The envisaged LTER Infrastructure will enable European-scale investigation of major ecosystems and socio-ecological systems, and support knowledge-based decision making at multiple levels.


Grant
Agency: European Commission | Branch: H2020 | Program: CSA | Phase: INFRADEV-02-2016 | Award Amount: 9.05M | Year: 2017

The European Solar Telescope (EST) will be a revolutionary Research Infrastructure that will play a major role in answering key questions in modern Solar Physics. This 4-meter class solar telescope, to be located in the Canary Islands, will provide solar physicists with the most advanced state-of-the-art observing tools to transform our understanding of the complex phenomena that drive the solar magnetic activity. The principal objective of the present Preparatory Phase is to provide both the EST international consortium and the funding agencies with a detailed plan regarding the implementation of EST. The specific objectives of the proposed preparatory phase are: (1) to explore possible legal frameworks and related governance schemes that can be used by agencies to jointly establish, construct and operate EST as a new research infrastructure, with the implementation of an intermediate temporary organisational structure, as a previous step for future phases of the project; (2) to explore funding schemes and funding sources for EST, including a proposal of financial models to make possible the combination of direct financial and in-kind contributions towards the construction and operation of EST; (3) to compare the two possible sites for EST in the Canary Islands Astronomical Observatories and prepare final site agreements; (4) to engage funding agencies and policy makers for a long-term commitment which guarantees the construction and operation phases of the Telescope; (5) to involve industry in the design of EST key elements to the required level of definition and validation for their final production; (6) to enhance and intensify outreach activities and strategic links with national agencies and the user communities of EST. To accomplish the aforementioned goals, this 4-year project, promoted by the European Association for Solar Telescopes (EAST) and the PRE-EST consortium, encompassing 23 research institutions from 16 countries, will set up the Project Office


Grant
Agency: European Commission | Branch: FP7 | Program: CP-IP | Phase: NMP-2007-2.5-1 | Award Amount: 13.86M | Year: 2008

The MORGaN project addresses the need for a new materials for electronic devices and sensors that operate in extreme conditions, especially high temperature, high electric field and highly corrosive environment. It will take advantage of the excellent physical properties of diamond and gallium nitride heterostructures. The association of the two materials will give rise to the best materials and devices for ultimate performance in extreme environments. Both materials possess durability and robustness to high temperature, radiation and electric field. Diamond material exhibits the best mechanical robustness and thermal conductivity, while GaN presents also high electron mobility, giving high power handling and efficiency. III-N systems have other desirable properties for sensor applications in extreme environments. It is the only highly polar semiconductor matrix that has ceramic-like stability and can form heterostructures. It has the highest spontaneous polarisation with a Curie temperature above 1000C for AlN: a lattice matched III-N heterostructure with a built-in polarisation discontinuity is expected to enable transistor action above 1000C. The packaging and metallisation of an electronic device or sensor are important elements in extreme conditions. Metal contacts must be stable and the package must be thermally compatible with the device requirements and chemically stable. MORGaN proposes a novel technological solution to electron device and sensor modules. Advanced 3D ceramic packaging and new metallisation techniques based on the emerging technology of MN\1AXN alloys will also be explored. As such, the vision of MORGaN for materials for extreme conditions is holistic, involving 2 large industrial partners, 2 industrial labs, 6 SMEs and 13 public research partners. The project includes research, demonstration, management, training and dissemination activities.


News Article | February 20, 2017
Site: phys.org

V501 Aur was detected as an X-ray source in 1996 by the ROSAT space observatory. After the discovery, the source was classified as a possible new weak-lined T-Tauri star (WTTS) belonging to the Taurus-Auriga star-forming region. However, subsequent studies of this star provided evidence of its unseen stellar companion, suggesting that V501 Aur could be a single-lined spectroscopic binary. In the latest study, a team of astronomers led by Martin Vaňko of the Astronomical Institute of Slovak Academy of Sciences in Tatranská Lomnica, Slovakia, has found that V501 Aur is a single-lined spectroscopic binary star. "The spectroscopic observations reveal that V501 Aur is a single-lined spectroscopic binary system with a 68.8-day orbital period, a slightly eccentric orbit (e ∼ 0.03), and a systemic velocity discrepant from the mean of Taurus-Auriga," the paper reads. The findings are based on a series of observational campaigns carried out between 1996 and 2016, utilizing telescopes and spectrographs worldwide. These observations allowed the team to reveal more details about the nature of this star. "Information gathered since, as well as observations reported here, paint a rather different picture of the nature of the system that we now describe," the authors wrote. According to the paper, V501 Aur is a rapidly rotating early K star with a radius of more than 26.3 solar radii. The spectroscopic observations also indicate that V501 Aur has a fairly massive unseen companion, making it a binary star. Moreover, the new evidence shows that V501 Aur is not a T-Tauri star, but is instead a field binary far behind the Taurus-Auriga star-forming region. "The scenario that emerges for V501 Aur, aided by a comparison with stellar evolution models that succeed in matching all observational constraints, is one in which it is a background, non-eclipsing spectroscopic binary projected onto the Taurus-Auriga star-forming region, with a luminous, spotted, and fairly rapidly rotating giant star as the primary, and a likely much more rapidly rotating early-type star as the secondary," the researchers wrote in the paper. Furthermore, the scientists estimated the mass of this binary system. Their calculations show that the primary star is about four times more massive than the sun, while its companion has a mass between 1.63 to 2.3 solar masses. The findings also indicate that the system is roughly 180 million years old and is located approximately 2,600 light years away. The team concluded that in order to uncover more details about V501 Aur, a detailed chemical analysis of this system should be performed. It could help us reveal its other parameters and improve our knowledge about its evolutionary state. Explore further: Water detected in the atmosphere of hot Jupiter exoplanet 51 Pegasi b More information: On the nature of the candidate T-Tauri star V501 Aurigae, arXiv:1702.04512 [astro-ph.SR] arxiv.org/abs/1702.04512 Abstract We report new multi-colour photometry and high-resolution spectroscopic observations of the long-period variable V501 Aur, previously considered to be a weak-lined T-Tauri star belonging to the Taurus-Auriga star-forming region. The spectroscopic observations reveal that V501 Aur is a single-lined spectroscopic binary system with a 68.8-day orbital period, a slightly eccentric orbit (e ~ 0.03), and a systemic velocity discrepant from the mean of Taurus-Auriga. The photometry shows quasi-periodic variations on a different, ~55-day timescale that we attribute to rotational modulation by spots. No eclipses are seen. The visible object is a rapidly rotating (vsini ~ 25 km/s) early K star, which along with the rotation period implies it must be large (R > 26.3 Rsun), as suggested also by spectroscopic estimates indicating a low surface gravity. The parallax from the Gaia mission and other independent estimates imply a distance much greater than the Taurus-Auriga region, consistent with the giant interpretation. Taken together, this evidence together with a re-evaluation of the LiI~λ6707 and Hα lines shows that V501 Aur is not a T-Tauri star, but is instead a field binary with a giant primary far behind the Taurus-Auriga star-forming region. The large mass function from the spectroscopic orbit and a comparison with stellar evolution models suggest the secondary may be an early-type main-sequence star.


Grant
Agency: European Commission | Branch: FP7 | Program: CP-CSA-Infra | Phase: INFRA-2012-1.1.26. | Award Amount: 8.20M | Year: 2013

This project aims at integrating the major European infrastructures in the field of high-resolution solar physics. The following actions will be taken: (i) realise Trans-national Access to external European users; (ii) enhance and spread data acquisition and processing expertise to the Europe-wide community; (iii) increase the impact of high-resolution data by offering science-ready data and facilitating their retrieval and usage; (iv) encourage combination of space and ground-based data by providing unified access to pertinent data repositories; (v) foster synergies between different research communities by organising meetings where each presents state-of-the-art methodologies; (vi) train a new generation of solar researchers through setting up schools and an ambitious mobility programme; (vii) develop prototypes for new-generation post-focus instruments; (vii) study local and non-local atmospheric turbulence, their impact on image quality, and ways to negate their effects; (viii) improve the performance of existing telescopes; (ix) improve designs of future large European ground-and space-based solar telescopes; (x) lay foundations for combined use of facilities around the world and in space; (xi) reinforce partnership with industry to promote technology transfer through existing networks; and (xii) dissemination activities towards society. The project involves all pertinent European research institutions, infrastructures, and data repositories. Together, these represent first-class facilities. The additional participation by private companies and non-European research institutions maximizes the impact on the world-wide scale. In particular, the project achievements will be of principal importance in defining the exploitation of the future 4-meter European Solar Telescope.


Samaj L.,Slovak Academy of Sciences | Jancovici B.,University Paris - Sud
Journal of Statistical Physics | Year: 2010

This paper is a continuation of the previous study (Šamaj in J. Stat. Phys. 137:1-17, 2009), where a sequence of sum rules for the equilibrium charge and current density correlation functions in an infinite (bulk) quantum media coupled to the radiation was derived by using Rytov's fluctuational electrodynamics. Here, we extend the previous results to inhomogeneous situations, in particular to the three-dimensional interface geometry of two joint semi-infinite media. The sum rules derived for the charge-charge density correlations represent a generalization of the previous ones, related to the interface dipole moment and to the long-ranged tail of the surface charge density correlation function along the interface of a conductor in contact with an inert (not fluctuating) dielectric wall, to two fluctuating semi-infinite media of any kind. The charge-current and current-current sum rules obtained here are, to our knowledge, new. The current-current sum rules indicate a breaking of the directional invariance of the diagonal current-current correlations by the interface. The sum rules are expressed explicitly in the classical high-temperature limit (the static case) and for the jellium model (the time-dependent case). © 2010 Springer Science+Business Media, LLC.


Sirota M.,King's College London | Kostovicova L.,Slovak Academy of Sciences | Juanchich M.,Kingston University
Psychonomic Bulletin and Review | Year: 2014

Knowing which properties of visual displays facilitate statistical reasoning bears practical and theoretical implications. Therefore, we studied the effect of one property of visual diplays - iconicity (i.e., the resemblance of a visual sign to its referent) - on Bayesian reasoning. Two main accounts of statistical reasoning predict different effect of iconicity on Bayesian reasoning. The ecological-rationality account predicts a positive iconicity effect, because more highly iconic signs resemble more individuated objects, which tap better into an evolutionary-designed frequency-coding mechanism that, in turn, facilitates Bayesian reasoning. The nested-sets account predicts a null iconicity effect, because iconicity does not affect the salience of a nested-sets structure-the factor facilitating Bayesian reasoning processed by a general reasoning mechanism. In two well-powered experiments (N = 577), we found no support for a positive iconicity effect across different iconicity levels that were manipulated in different visual displays (meta-analytical overall effect: log OR = -0.13, 95 % CI [-0.53, 0.28]). A Bayes factor analysis provided strong evidence in favor of the null hypothesis-the null iconicity effect. Thus, these findings corroborate the nested-sets rather than the ecological-rationality account of statistical reasoning. © 2013 Psychonomic Society, Inc.


Sedlak R.,Czech Institute of Organic Chemistry And Biochemistry | Sedlak R.,Charles University | Janowski T.,University of Arkansas | Pitonak M.,Comenius University | And 5 more authors.
Journal of Chemical Theory and Computation | Year: 2013

We evaluate the performance of the most widely used wave function, density functional theory, and semiempirical methods for the description of noncovalent interactions in a set of larger, mostly dispersion-stabilized noncovalent complexes (the L7 data set). The methods tested include MP2, MP3, SCS-MP2, SCS(MI)-MP2, MP2.5, MP2.X, MP2C, DFT-D, DFT-D3 (B3-LYP-D3, B-LYP-D3, TPSS-D3, PW6B95-D3, M06-2X-D3), and M06-2X, and semiempirical methods augmented with dispersion and hydrogen bonding corrections: SCC-DFTB-D, PM6-D, PM6-DH2, and PM6-D3H4. The test complexes are the octadecane dimer, the guanine trimer, the circumcoronene···adenine dimer, the coronene dimer, the guanine-cytosine dimer, the circumcoronene···guanine- cytosine dimer, and an amyloid fragment trimer containing phenylalanine residues. The best performing method is MP2.5 with relative root-mean-square deviation (rRMSD) of 4%. It can thus be recommended as an alternative to the CCSD(T)/CBS (alternatively QCISD(T)/CBS) benchmark for molecular systems which exceed current computational capacity. The second best non-DFT method is MP2C with rRMSD of 8%. A method with the most favorable "accuracy/cost" ratio belongs to the DFT family: BLYP-D3, with an rRMSD of 8%. Semiempirical methods deliver less accurate results (the rRMSD exceeds 25%). Nevertheless, their absolute errors are close to some much more expensive methods, such as M06-2X, MP2, or SCS(MI)-MP2, and thus their price/performance ratio is excellent. © 2013 American Chemical Society.


Balaz P.,Slovak Academy of Sciences | Calka A.,University of Wollongong | Zorkovska A.,Slovak Academy of Sciences | Balaz M.,Slovak Academy of Sciences
Materials and Manufacturing Processes | Year: 2013

In this study, hen eggshell (ES) biomaterial was treated by two mechanochemical methods. Here we show that using of low-current high-voltage electrical impulses during electrical discharge assisted mechanical milling (EDAMM) or high-energy milling (HEM) are proper tools for ES transformation to materials suitable for the further applications. The decomposition of calcite CaCO3 (the main component of ES) into lime CaO (EDAMM treatment) or calcite-aragonite transformation (HEM treatment) were documented by X-ray diffractometry. The applied techniques bring about solid state transformation, high degree of calcite amorphization, and enhancement of specific surface area of ES samples. As examples of using the transformed ES the uptake of cadmium ions during sorption experiments and the dechlorination of polyvinyl chloride are given. In both cases, the technologically accepted recoveries and kinetics have been obtained. Copyright © 2013 Taylor and Francis Group, LLC.


Pritychenko B.,Brookhaven National Laboratory | Betak E.,Slovak Academy of Sciences | Singh B.,McMaster University | Totans J.,Brookhaven National Laboratory
Nuclear Data Sheets | Year: 2014

The Nuclear Science References (NSR) database together with its associated Web interface, is the world's only comprehensive source of easily accessible low- and intermediate-energy nuclear physics bibliographic information for more than 210,000 articles since the beginning of nuclear science. The weekly-updated NSR database provides essential support for nuclear data evaluation, compilation and research activities. The principles of the database and Web application development and maintenance are described. Examples of nuclear structure, reaction and decay applications are specifically included. The complete NSR database is freely available at the websites of the National Nuclear Data Center http://www.nndc.bnl.gov/nsr and the International Atomic Energy Agency http://www-nds.iaea.org/nsr. © 2014 Elsevier Inc.


Janak M.,Slovak Academy of Sciences | Froitzheim N.,University of Bonn | Georgiev N.,Sofia University | Nagel T.J.,University of Bonn | Sarov S.,Research Institute Geology and Geophysics AD
Journal of Metamorphic Geology | Year: 2011

A new occurrence of kyanite eclogite in the Pirin Mountains of southwestern Bulgaria within the rocks belonging to the Obidim Unit of the Rhodope Metamorphic Complex is presented. This eclogite provides important information about the peak-pressure conditions despite strong thermal overprint at low pressure. Textural relationships, phase equilibrium modelling and conventional geothermobarometry were used to constrain the metamorphic evolution. Garnet porphyroblasts with inclusions of omphacite (up to 43mol.% Jd), phengite (up to 3.5 Si p.f.u.), kyanite, polycrystalline quartz, pargasitic amphibole, zoisite and rutile in the Mg-rich cores (XMg=0.44-0.46) record a prograde increase in P-T conditions from ~2.5GPa and 650°C to ~3GPa and 700-750°C. Maximum pressure values fall within the stability field of coesite. During exhumation, the peak-pressure assemblage garnet+ omphacite+phengite+kyanite was variably overprinted by a lower pressure one forming symplectitic textures, such as diopside+plagioclase after omphacite and biotite+plagioclase after phengite. The development of spinel (XMg=0.4-0.45)+corundum+anorthite assemblage in the kyanite-bearing domains at ~1.1GPa and 800-850°C suggests a thermal overprint in the high-pressure granulite facies stability field. This thermal event was followed by cooling at ~0.8GPa under amphibolite facies conditions; retrograde kelyphite texture involving plagioclase and amphibole was developed around garnet. Our results add to the already existing evidence for ultra high pressure (UHP) metamorphism in the Upper Allochthon of the Rhodope Metamorphic Complex as in the Kimi Unit and show that it is more widespread than previously known. Published age data and field structural relations suggest that the Obidim Unit represents Variscan continental crust involved into the Alpine nappe edifice of the Rhodopes and that eclogite facies metamorphism was Palaeozoic, in contrast to the Kimi Unit where age determinations suggest a Jurassic or Cretaceous age for UHP metamorphism. This implies that UHP metamorphism in the Upper Allochthon of the Rhodopes may have occurred twice, during Alpine and pre-Alpine orogenic events, and that two independent HP/UHP provinces of different age overlap in this area. © 2010 Blackwell Publishing Ltd.


Sirotkin A.V.,Animal Production Research Center | Sirotkin A.V.,Constantine the Philosopher University | Laukova M.,Slovak Academy of Sciences | Ovcharenko D.,Altogen Biosystems | And 2 more authors.
Journal of Cellular Physiology | Year: 2010

Previous studies have shown that microRNAs (miRNAs) can control steroidogenesis in cultured granulosa cells. In this study we wanted to determine if miRNAs can also affect proliferation and apoptosis in human ovarian cells. The effect of transfection of cultured primary ovarian granulosa cells with 80 different constructs encoding human pre-miRNAs on the expression of the proliferation marker, PCNA, and the apoptosis marker, Bax was evaluated by immunocytochemistry. Eleven out of 80 tested miRNA constructs resulted in stimulation, and 53 miRNAs inhibited expression of PCNA. Furthermore, 11 of the 80 miRNAs tested promoted accumulation of Bax, while 46 miRNAs caused a reduction in Bax in human ovarian cells. In addition, two selected antisense constructs that block the corresponding miRNAs mir-15a and mir-188 were evaluated for their effects on expression of PCNA. An antisense construct inhibiting mir-15a (which precursor suppressed PCNA) increased PCNA, whereas an antisense construct for mir-188 (which precursor did not change PCNA) did not affect PCNA expression. Verification of effects of selected pre-mir-10a, mir-105, and mir-182 by using other markers of proliferation (cyclin B1) and apoptosis (TdT and caspase 3) confirmed specificity of miRNAs effects on these processes. This is the first direct demonstration of the involvement of miRNAs in controlling both proliferation and apoptosis by ovarian granulose cells, as well as the identification of miRNAs promoting and suppressing these processes utilizing a genome-wide miRNA screen. © 2009 Wiley-Liss, Inc.


Dubecky M.,Palacky University | Jurecka P.,Palacky University | Derian R.,Slovak Academy of Sciences | Hobza P.,Palacky University | And 3 more authors.
Journal of Chemical Theory and Computation | Year: 2013

An accurate description of noncovalent interaction energies is one of the most challenging tasks in computational chemistry. To date, nonempirical CCSD(T)/CBS has been used as a benchmark reference. However, its practical use is limited due to the rapid growth of its computational cost with the system complexity. Here, we show that the fixed-node diffusion Monte Carlo (FN-DMC) method with a more favorable scaling is capable of reaching the CCSD(T)/CBS within subchemical accuracy (<0.1 kcal/mol) on a testing set of six small noncovalent complexes including the water dimer. In benzene/water, benzene/methane, and the T-shape benzene dimer, FN-DMC provides interaction energies that agree within 0.25 kcal/mol with the best available CCSD(T)/CBS estimates. The demonstrated predictive power of FN-DMC therefore provides new opportunities for studies of the vast and important class of medium/large noncovalent complexes. © 2013 American Chemical Society.


Huld T.,European Commission - Joint Research Center Ispra | Cebecauer T.,R.Ø.S.A. | Cebecauer T.,Slovak Academy of Sciences | Suri M.,R.Ø.S.A. | Dunlop E.D.,European Commission - Joint Research Center Ispra
Progress in Photovoltaics: Research and Applications | Year: 2010

We present a method for estimating the energy output from one-axis tracking non-concentrating PV systems and compare the yields from different configurations. The method is based on the use of solar radiation and temperature databases and models for the performance of PV modules under given geographic conditions. In the resulting maps of energy yield for Europe it is found that there are two different one-axis configurations that perform almost as well as a full two-axis suntracking system: one with a vertical axis and inclined modules, and the other with an inclined axis directed north-south and modules in the plane of the axis. When the inclination angles of the modules are optimized, these two configurations have an energy yield compared to an optimal fixed mounting that is approximately 30% higher in southern Europe, about 2025% higher in central Europe, and up to 50% higher in northern Scandinavia. Compared to the two-axis tracking, the yields are only 1-4% lower, making such one-axis tracking systems very attractive in terms of performance relative to technical complexity and price. Copyright © 2010 John Wiley & Sons, Ltd.


Nanjo Y.,Japan National Agriculture and Food Research Organization | Skultety L.,Slovak Academy of Sciences | Ashraf Y.,University Pierre and Marie Curie | Komatsu S.,Japan National Agriculture and Food Research Organization
Journal of Proteome Research | Year: 2010

Gel-based and gel-free proteomics techniques were used to investigate early responses to flooding stress in the roots and hypocotyls of soybean seedlings. Proteins from 2-day-old soybean seedlings flooded for 12 h were extracted and analyzed. Two mass-spectroscopy-based proteomics analyses, two-dimensional fluorescence difference gel electrophoresis, and nanoliquid chromatography identified 32 from 17 spots and 81 proteins, respectively, as responsive to flooding stress. On the basis of the number and function of proteins identified, glycolysis and fermentation enzymes and inducers of heat shock proteins were key elements in the early responses to flooding stress. Analysis of enzyme activities and carbohydrate contents in flooded seedlings showed that glucose degradation and sucrose accumulation accelerated during flooding due to activation of glycolysis and down-regulation of sucrose degrading enzymes. Additionally, the methylglyoxal pathway, which is detoxification system linked to glycolysis, was up-regulated. Furthermore, two-dimensional polyacrylamide gel electrophoresis-based phosphoproteomics analysis showed that proteins involved in protein folding and synthesis were dephosphorylated under flooding conditions. These results suggest that translational and post-translational control during flooding possibly induces an imbalance in the expression of proteins involved in several metabolic pathways including carbohydrate metabolism that might cause flooding injury of soybean seedlings. © 2010 American Chemical Society.


Veselsky M.,Slovak Academy of Sciences | Souliotis G.A.,National and Kapodistrian University of Athens
Nuclear Physics A | Year: 2011

Experimental data from the literature concerning nucleus-nucleus collisions at beam energies of few A MeV above the Coulomb barrier are investigated in this work with emphasis on projectile-like fragment distributions. In peripheral collisions at beam energies below 10 A MeV, deep-inelastic transfer is shown to be the dominant reaction mechanism. In addition, the mechanism may involve an extension of the nuclear profile in the window (neck) region, observed primarily in reactions with very heavy target nuclei. Isoscaling observed at these energies can be used as a tool to predict the production rates of exotic nuclei in reactions induced by exotic secondary beams. © 2011 Elsevier B.V.


Kudela K.,Slovak Academy of Sciences | Mavromichalaki H.,National and Kapodistrian University of Athens | Papaioannou A.,National and Kapodistrian University of Athens | Gerontidou M.,National and Kapodistrian University of Athens
Solar Physics | Year: 2010

The contributions of quasi-periodic variations of cosmic rays for T > 27 days at the primary energies to which neutron monitors are sensitive have a rather complicated character. They were reported in several papers (e. g. Valdés-Galicia, Perez-Enriquez, and Otaola, 1996; Mavromichalaki et al., 2003; Kudela et al., 2002; Caballero and Valdés-Galicia, 2001) from individual stations and for various time intervals covered. The data archive of several neutron monitor stations developed within the NMDB project (www.nmdb.eu) now involves long time series of measurements at neutron monitors situated at different geomagnetic cut-off rigidity positions and at different altitudes. It is updated continuously. Using the daily averages of cosmic-ray intensity at three selected stations within NMDB: i) the temporal evolution of the selected quasi-periodicities, especially those of approximately 1.7 yr, 150 days and 26-32 days respectively, until 2008 are reviewed, ii) the similarities of the spectra are checked and iii) the occurrence of quasi-periodicities with those observed in solar, interplanetary and geomagnetic activities (Moussas et al., 2005; Richardson and Cane, 2005) as well as in energetic particles below the atmospheric threshold are discussed (Laurenza et al., 2009). © 2010 Springer Science+Business Media B.V.


Janisova M.,Slovak Academy of Sciences | Michalcova D.,Masaryk University | Bacaro G.,University of Siena | Ghisla A.,Research and Innovation Center Fondazione Edmund Machinery
Agriculture, Ecosystems and Environment | Year: 2014

We studied how the landscape structure (percentage cover and diversity of surrounding habitats) affects different components of species diversity (alpha, beta and gamma) of vascular plants in semi-natural grasslands in the Slovak Republic. We analyzed all grasslands combined as well as four main types delimited according to their position along a moisture gradient (xerophilous, sub-xerophilous, mesophilous and wet grasslands). We used grassland records stored in the Slovak Vegetation Database. The geographically stratified dataset included 3795 plots with 1221 species of vascular plants. Along with the total number of species in the vegetation plots, we considered the numbers of target grassland species, forest species, archaeophytes, neophytes and species with high fidelity to non-natural habitats. The landscape parameters based on CORINE land cover maps and the National Grassland Inventory, were calculated for plot neighbourhoods of 4km2. Spatially constrained rarefaction curves were constructed to examine how different diversity components behave with changing structure of the surrounding landscape. Our study revealed that alpha diversity was affected by both percentage cover and diversity of different habitats in the plot neighbourhood. It increased with increasing proportion or diversity of different natural and semi-natural habitats and decreased with increasing proportion or diversity of non-natural habitats in the surrounding landscape. Beta and gamma diversities showed opposite pattern to that of alpha diversity for most analyzed factors. Alpha diversity in sub-xerophilous and mesophilous grasslands was more susceptible to changes in landscape structure than alpha diversity in xerophilous or wet grasslands. Regression trees and linear or quadratic regression models revealed that in xerophilous or wet grasslands, high alpha diversity was best predicted by a high proportion of ecologically valuable grasslands in the surroundings. In sub-xerophilous and mesophilous grasslands, the best predictor was proportion of natural and semi-natural habitats followed by the proportion of non-natural habitats. The detected pattern regarding alpha, beta and gamma diversity calculated for grassland target species did not differ from the pattern for the whole species assemblage. However, the surrounding landscape affected the number, proportion and cover of species typical of forest or non-natural habitats (including alien species) in the plots. We explain the results by the interplay of two main mechanisms: species pool and spatial mass effects. In our study, the effect of species pool on alpha diversity was stronger than the spatial mass effect. Based on differences indicated in the responses of various grassland types to the surrounding landscape structure, we suggest adoption of community type specific conservation measures. © 2013 Elsevier B.V.


Samaj L.,University Paris - Sud | Samaj L.,Slovak Academy of Sciences | Trizac E.,University Paris - Sud
Journal of Statistical Physics | Year: 2014

This work contributes to the problem of determining effective interaction between asymmetrically (likely or oppositely) charged objects whose total charge is neutralized by mobile pointlike counter-ions of the same charge, the whole system being in thermal equilibrium. The problem is formulated in two spatial dimensions with logarithmic Coulomb interactions. The charged objects correspond to two parallel lines at distance d, with fixed line charge densities. Two versions of the model are considered: the standard "unconstrained" one with particles moving freely between the lines and the "constrained" one with particles confined to the lines. We solve exactly both systems at the free-fermion coupling and compare the results for the pressure (i.e. the force between the lines per unit length of one of the lines) with the mean-field Poisson-Boltzmann solution. For the unconstrained model, the large-d asymptotic behaviour of the free-fermion pressure differs from that predicted by the mean-field theory. For the constrained model, the asymptotic pressure coincides with the attractive van der Waals-Casimir fluctuational force. For both models, there are fundamental differences between the cases of likely-charged and oppositely-charged lines, the latter case corresponding at large distances d to a capacitor. © 2014 Springer Science+Business Media New York.


Sirota M.,King's College London | Kostovicova L.,Slovak Academy of Sciences | Vallee-Tourangeau F.,Kingston University
Quarterly Journal of Experimental Psychology | Year: 2015

People improve their Bayesian reasoning most when they are trained to represent single-event probabilities as natural frequencies; nevertheless, the underlying mechanism of this representational training remains unclear. Several authors suggested that people learn to shift the initial format to natural frequencies, and improve their reasoning because natural frequencies align with an evolutionary designed frequency-coding mechanism—the format-representation shift hypothesis. Alternatively, people may acquire a generic problem representation in terms of nested sets that is then transferred to similar problems—the problem-representation transfer hypothesis. To disentangle the effect of the format shift from problem representation transfer, we devised two types of training with problems featuring a nonfrequency format and a concealed nested-sets structure. Participants learnt the adequate problem representation in both training manipulations, but in only one did they learn, in addition, to shift the format to frequencies. Substantial evidence (BF01 = 5, where BF = Bayes factor) indicates that both types of training improved reasoning in an immediate and a one-week follow-up posttest to the same extent. Such findings support the problem-representation transfer hypothesis because learning an adequate nested-sets problem representation accounts for the performance improvement, whereas the frequency format per se confers no additional benefit. We discuss the implications of these findings for two dominant accounts of statistical reasoning. © 2014, The Experimental Psychology Society.


Granatier J.,Czech Institute of Organic Chemistry And Biochemistry | Pitonak M.,Comenius University | Pitonak M.,Slovak Academy of Sciences | Hobza P.,Czech Institute of Organic Chemistry And Biochemistry | Hobza P.,Palacky University
Journal of Chemical Theory and Computation | Year: 2012

The proper description of noncovalent complexes is a notoriously difficult problem, especially for complexes dominated by the dispersion energy. Accurate and reliable results can be obtained using computationally demanding methods such as the coupled clusters with iterative treatment of single and double excitations and perturbative triples correction (CCSD(T)), close to the complete basis set (CBS) limit. The sizes of the noncovalent complexes of interest, however, often exceed the computational capability of available computer facilities and software. Computationally efficient yet accurate and reliable theoretical methods are highly desired. In this work, we assembled a small test set of noncovalent complexes of un/saturated a/cyclic hydrocarbon (HC) dimers in order to inspect the accuracy and reliability of several routinely used low-order scaling wave function (WFT) and density functional theory (DFT) methods. The test set comprises dispersion dominated complexes of two different monomer types, saturated and unsaturated. The unsaturated systems are relatively well populated in one of the most popular training data sets for noncovalent complexes, the S22 set of Jurečka et al. The opposite is true for saturated systems, for which rather poor performance of "approximate" methods has been observed. From the results shown is this work, it is clear that unsaturated, e.g., π⋯π stacked, covalent complexes are described more accurately on average. With the exception of a few "balanced methods", such as MP2C, MP2.5, SCS-/SCS(MI)-CCSD, or DFT-D 3 with the TPSS and PBE functionals, a simultaneous description of saturated and unsaturated HCs introduces serious errors (i.e., more than 1 kcal/mol). © 2012 American Chemical Society.


Grant
Agency: European Commission | Branch: FP7 | Program: CP-FP | Phase: ENV.2007.4.1.1.2. | Award Amount: 3.44M | Year: 2008

The key challenge addressed in the present proposal is to develop a biodiversity observation system that is transmissible, cost effective and provides added value to the currently independent data sources of in situ data and EO. There are three requirements: the production of protocols to enable extant data to be placed on a common framework for analysis; the provision of a sound scientific conceptual basis for the system that will provide a robust statistical structure for analytical tests and for the eventual estimates of stock and change and the provision of a system for estimating past change and monitoring as well as enabling forecasting of future options so that policy makers can generate appropriate strategies for mitigation. The present consortium has a major advantage in that the framework is based on existing institutional collaboration which has been developed in the EU project ALTERNET. This framework will ensure continuity of recording and shows an existing commitments of the institutes concerned to long term monitoring. It will also provide the necessary structure for integration of available data.. This network already has long term data sets for biodiversity indicators eg butterflies and birds but the ambition is to convert these from site specific measures through inter-calibration to the wider European picture, using tried and tested statistical procedures. The key work package will involve inter-calibration between EO and in situ data,which will involve habitats that can be linked to specific biodiversity indicators. These will be identified using a conceptual framework developed in another work package. The target is to provide a basis for up and down scaling that can be tested to show the added value of integration. Other work packages will provide protocols to place data onto a common framework tests of validation and stratification procedures for assessing the consistency of data coverage.


Grant
Agency: European Commission | Branch: FP7 | Program: MC-ITN | Phase: FP7-PEOPLE-2010-ITN | Award Amount: 3.06M | Year: 2011

The FUNEA vision is to develop an integrated and multidisciplinary research and training programme in the field of inorganic nitrides for energy applications. In terms of fundamental research, the FUNEA aims to advance the state-of-the-art knowledge and understanding of inorganic nitrides and mixed nitride-anion systems by achieving the ability to synthesise, manipulate, characterize, understand and model binary and ternary nitrides and oxonitrides with functional properties. By this a breakthrough in the nitride chemistry will be achieved steering in a new era for materials with advanced functionality and exceptional levels of performance. In terms of technological applications, the FUNEA focuses on the energetic applications of novel nitride-based materials with this addressing the main needs of the 21st century. To meet this vision, eight European academic research groups with complementary expertise in the synthesis, processing and characterization of materials and five industrial partners, each of whom have made a commitment to study these new functional nitrides, have decided to create a network of scientific cooperation with the following goals: (i) to create an interdisciplinary approach to the synthesis, processing and characterization of novel nitrides for energy applications, (ii) to train high-quality young researchers, experienced in the interdisciplinary science of the nitrides. These young professionals will lead the field forward and onward to its bright future in the European science and technology. Specifically, FUNEA aims to train 11 ESRs and 2 ERs with an overall target of 40% women researchers, and (iii) to establish a European network of scientists in academic institutes and industry in the field of inorganic nitrides, that will continue to grow and enhance European competitiveness over the next years.


Grant
Agency: European Commission | Branch: FP7 | Program: CP-CSA-Infra | Phase: INFRA-2007-2.2-01 | Award Amount: 6.37M | Year: 2008

The Life Watch e-Science and Technology Infrastructure for biodiversity data and observatories will be a large-scale European research infrastructure bringing together: -a system of marine, terrestrial and freshwater observatories; -common access to a huge amount of interlinked, distributed data from databases and monitoring sites; -computational facilities in virtual laboratories with analytical and modelling tools; -targeted user and training support and a programme for public services. The biodiversity research infrastructure will open up new and exciting research opportunities, and will help to enhance the understanding and sustainable management of our natural environment. This preparatory project brings together the interested EU Member and Associated States with the objective to prepare a cooperation agreement on the construction and maintenance of the Life Watch research infrastructure. In addition, the leading networks in biodiversity science and stakeholder institutes are preparing the organisation and logistics for the following construction phase. The current project delivers the technical, legal and financial preparations required for entering and managing the Construction Phase. A range of policy issues are resolved with respect the organisation of the distributed infrastructure, its legal implications, construction logistics, user service, cost analysis and planning. In addition the project makes the necessary preparations in the domain of risk management and quality control. The project is planned to take three years. A Policy and Science Board, populated by the representatives of fourteen potentially interested partner countries and eight cooperating scientific networks, oversees the progress of the preparations. The individual members of the Board act as the liaison with their political domains and the research communities, respectively.


Samaj L.,University Paris - Sud | Samaj L.,Slovak Academy of Sciences | Trizac E.,University Paris - Sud
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2011

We present a new analytical approach to the strong electrostatic coupling regime (SC) that can be achieved equivalently at low temperatures, high charges, low dielectric permittivity, etc. Two geometries are analyzed in detail: one charged wall first, and then two parallel walls at small distances that can be likely or oppositely charged. In all cases, only one type of mobile counterions is present, and ensures electroneutrality (salt-free case). The method is based on a systematic expansion around the ground state formed by the two-dimensional Wigner crystal(s) of counterions at the plate(s). The leading SC order stems from a single-particle theory, and coincides with the virial SC approach that has been much studied in the last 10 years. The first correction has the functional form of the virial SC prediction, but the prefactor is different. The present theory is free of divergences and the obtained results, both for symmetrically and asymmetrically charged plates, are in excellent agreement with available data of Monte Carlo simulations under strong and intermediate Coulombic couplings. All results obtained represent relevant improvements over the virial SC estimates. The present SC theory starting from the Wigner crystal and therefore coined Wigner SC, sheds light on anomalous phenomena like the counterion mediated like-charge attraction, and the opposite-charge repulsion. © 2011 American Physical Society.


Nanjo Y.,Japan National Agriculture and Food Research Organization | Skultety L.,Slovak Academy of Sciences | Uvackova L.,Slovak Academy of Sciences | Klubicova K.,Slovak Academy of Sciences | And 2 more authors.
Journal of Proteome Research | Year: 2012

Flooding injury is a major problem in soybean cultivation. A proteomics approach was used to clarify the occurrence of changes in protein expression level and phosphorylation in soybeans under flooding stress. Two-day-old seedlings were flooded for 1 day, proteins were extracted from root tips of the seedlings and digested with trypsin, and their expression levels and phosphorylation states were compared to those of untreated controls using mass spectrometry-based proteomics techniques. Phosphoproteins were enriched using a phosphoprotein purification column prior to digestion and mass spectrometry. The expression of proteins involved in energy production increased as a result of flooding, while expression of proteins involved in protein folding and cell structure maintenance decreased. Flooding induced changes of phosphorylation status of proteins involved in energy generation, protein synthesis and cell structure maintenance. The response to flooding stress may be regulated by both modulation of protein expression and phosphorylation state. Energy-demanding and production-related metabolic pathways may be particularly subject to regulation by changes in protein phosphorylation during flooding. © 2011 American Chemical Society.


Schauer S.,AIT Austrian Institute of Technology | Huber M.,University of Vienna | Hiesmayr B.C.,Slovak Academy of Sciences | Hiesmayr B.C.,University of Vienna
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2010

In this article we present a general security strategy for quantum secret sharing (QSS) protocols based on the scheme presented by Hillery, Büek, and Berthiaume (HBB) [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.59.1829 59, 1829 (1999)]. We focus on a generalization of the HBB protocol to n communication parties thus including n-partite Greenberger-Horne-Zeilinger states. We show that the multipartite version of the HBB scheme is insecure in certain settings and impractical when going to large n. To provide security for such QSS schemes in general we use the framework presented by some of the authors to detect certain genuine n-partite entanglement between the communication parties. In particular, we present a simple inequality which tests the security. © 2010 The American Physical Society.


Raith M.,University of Regensburg | Stano P.,Slovak Academy of Sciences | Baruffa F.,University of Regensburg | Baruffa F.,Jülich Research Center | Fabian J.,University of Regensburg
Physical Review Letters | Year: 2012

A global quantitative picture of the phonon-induced two-electron spin relaxation in GaAs double quantum dots is presented using highly accurate numerics. Wide regimes of interdot coupling, magnetic field magnitude and orientation, and detuning are explored in the presence of a nuclear bath. Most important, the giant magnetic anisotropy of the singlet-triplet relaxation can be controlled by detuning switching the principal anisotropy axes: a protected state becomes unprotected upon detuning and vice versa. It is also established that nuclear spins can dominate spin relaxation for unpolarized triplets even at high magnetic fields, contrary to common belief. © 2012 American Physical Society.


Grant
Agency: European Commission | Branch: FP7 | Program: CP | Phase: ENERGY.2009.7.3.1 | Award Amount: 4.64M | Year: 2010

The project aims at developing a unique device for electricity networks: A superconducting fault current limiter (SFCL) based on coated conductor YBCO tape (cc-tape) or 2nd Generation HTS tape. The general trend in Europe to a higher meshing of distribution networks and the rapid growing integration of renewable energy sources leads to an increase of the fault current level by every new installation. As substations ratings are coming to their limits network operators have to either decline additional installations to their grids or to upgrade if not rebuild complete substations. The SFCL provides a solution to deal with the increasing incidence and level of fault currents and will contribute to improving the performance, stability and efficiency of electricity grids. It can be applied as a new tool for grid operation and will enhance the flexibility for further grid planning. SFCL are considered to be the most attractive superconducting devices as they offer unparalleled features compared to conventional techniques such as automatic ultrafast and effective current limitation, no external trigger (fail safe), rapid self recovery and negligible impedance during operation. In contrast to conventional solutions resistive type SFCL are also suitable for higher voltage levels. So far developed SFCL prototypes based on BSCCO material are exhibiting significant AC-losses at higher currents which oppose their commercial introduction. Today, the availability of cc-tape in longer lengths at reasonable cost makes a commercial breakthrough of FCL possible with unique features such as compactness, short recovery-time, low AC-losses. Leading industrial and academic institutions from Europe have teamed up to design, build, and test the first full 3-phase cc-tape FCL worldwide. The device will be long term tested or even permanently installed in the medium voltage grid. The strong demand for this device is emphasized by the large number of electric utilities participating as partner


Grant
Agency: European Commission | Branch: FP7 | Program: CP | Phase: ENV.2012.6.2-1 | Award Amount: 11.49M | Year: 2012

Despite improved understanding of the links between ecosystem health, provision of ecosystem services and human well-being, further conceptual and empirical work is needed to make the ideas of ecosystem services (ESS) and natural capital (NC) operational. OpenNESS will therefore develop innovative and practical ways of applying them in land, water and urban management: it will identify how, where and when the concepts can most effectively be applied to solve problems. To do this, it will work with public and private decision makers and stakeholders to better understand the range of policy and management problems faced in different case study contexts (ranging across locales, sectors, scales and time). OpenNESS will consolidate, refine and develop a range of spatially-explicit methods to identify, quantify and value ecosystem services, and will develop hybrid assessment methods. It will also explore the effectiveness of financial and governance mechanisms, such as payments for ecosystem services, habitat banking, biodiversity offsetting and land and ecosystem accounting. These types of interventions have potential for sustaining ESS and NC, and for the design of new economic and social investment opportunities. Finally, OpenNESS will assess how current regulatory frameworks and other institutional factors at EU and national levels enable or constrain consideration of ESS and NC, and identify the implications for issues related to well-being, governance and competitiveness. OpenNESS will analyse the knowledge that is needed to define ESS and NC in the legal, administrative and political contexts that are relevant to the EU. The work will deliver a menu of multi-scale solutions to be used in real life situations by stakeholders, practitioners, and decision makers in public and business organizations, by providing new frameworks, data-sets, methods and tools that are fit-for-purpose and sensitive to the plurality of decision-making contexts.


Holic R.,Japan National Institute of Advanced Industrial Science and Technology | Holic R.,Slovak Academy of Sciences | Yazawa H.,Japan National Institute of Advanced Industrial Science and Technology | Kumagai H.,Asahi Glass Co. | Uemura H.,Japan National Institute of Advanced Industrial Science and Technology
Applied Microbiology and Biotechnology | Year: 2012

In an effort to produce ricinoleic acid (12-hydroxy-octadeca-cis-9-enoic acid: C18:1-OH) as a petrochemical replacement in a variety of industrial processes, we introduced Claviceps purpurea oleate Δ12-hydroxylase gene (CpFAH12) to Schizosaccharomyces pombe, putting it under the control of inducible nmt1 promoter. Since Fah12p is able to convert oleic acid to ricinoleic acid, we thought that S. pombe, in which around 75% of total fatty acid (FA) is oleic acid, would accordingly be an ideal microorganism for high production of ricinoleic acid. Unfortunately, at the normal growth temperature of 30°C, S. pombe cells harboring CpFAH12 grew poorly when the CpFAH12 gene expression was induced, perhaps implicating ricinoleic acid as toxic in S. pombe. However, in line with a likely thermoinstability of Fah12p, there was almost no growth inhibition at 37°C or, by contrast with 30°C and lower temperatures, ricinoleic acid accumulation. Accordingly, various optimization steps led to a regime with preliminary growth at 37°C followed by a 5-day incubation at 20°C, and the level of ricinoleic acid reached 137.4 μg/ml of culture that corresponded to 52.6% of total FA. © 2012 Springer-Verlag.


Di Nola A.,University of Salerno | Dvurecenskij A.,Slovak Academy of Sciences | Lettieri A.,University of Naples Federico II
International Journal of Approximate Reasoning | Year: 2010

In [4,5] the authors introduced the variety SMV of MV-algebras with an internal operator, state MV-algebras. In [2,3] the authors gave a stronger version of state MV-algebras, called state-morphism MV-algebras. In this paper we continue the studies presented in [2,3] just looking at several proper subvarieties of SMV, obtained by imposing suitable conditions on the behavior of the internal operator. © 2010 Elsevier Inc. All rights reserved.


Sepelak V.,Karlsruhe Institute of Technology | Sepelak V.,Slovak Academy of Sciences | Begin-Colin S.,CNRS Institute of Genetics and of Molecular and Cellular Biology | Le Caer G.,Rennes Institute of Physics
Dalton Transactions | Year: 2012

This paper, by no means exhaustive, focuses on high-energy ball-milling of oxides, on their mechanically induced changes and on the consequences of such changes on their physical and chemical properties. High-energy ball-milling offers a fortunate combination of technical simplicity and of complexity both of physical mechanisms which act during milling and of mechanosynthesized materials. Its basic interest, which stems from the large diversity of routes it offers to prepare oxides either directly or indirectly, is illustrated with various families of oxides. The direct path is to be favoured when as-milled oxides are of interest per se because of their nanocrystalline characteristics, their defects or their modified structures which result from mechanically driven phase transformations. The indirect path consists of a sequence of steps starting with mechanically activated oxides which may be subsequently just annealed or submitted to a combination of thermal treatments, with the possible occurrence of various chemical reactions, to prepare the sought-after materials with potential gains in processing temperatures and times. High energy ball-milling of oxides is more and more currently used to activate powders and to prepare nano-oxides at moderate temperatures. The interest of an activation step is well illustrated by the broad development of doped titania powders, synthesized by heat treatment of pre-ground reactants, for photocatalytic applications or to develop antibacterial materials. Another important class of applications of high-energy ball-milling is the formation of composites. It is exemplified here with the case of oxide-dispersed strengthened alloys whose properties are considerably improved by a dispersion of ultra-stable nanosized oxides whose formation mechanisms were recently described. The basic understanding of the mechanisms by which oxides or oxide mixtures evolve by high-energy ball-milling appears to be less advanced than it is for metallic materials essentially because of the overall complexity of the oxide structures, of their surfaces, of their defects and of their mechanical behavior. © 2012 The Royal Society of Chemistry.


Budaj J.,Slovak Academy of Sciences | Hubeny I.,Slovak Academy of Sciences | Hubeny I.,University of Arizona | Burrows A.,Princeton
Astronomy and Astrophysics | Year: 2012

Context. The internal heat loss, or cooling, of a planet determines its structure and evolution. Aims. We study the effects of irradiation, metallicity of the atmosphere, heat redistribution, stratospheres, and the depth where the heat redistribution takes place on the atmospheric structure, the core entropy, and subsequently on the cooling of the interior of the planet. Methods. We address in a consistent fashion the coupling between the day and the night sides of a planet by means of model atmosphere calculations with heat redistribution. We assume that strong convection leads to the same entropy on the day and night sides and that gravity is the same on both hemispheres. Results. We argue that the core cooling rates from the two hemispheres of a strongly irradiated planet may not be the same and that the difference depends on several important parameters. If the day-night heat redistribution is very efficient or if it takes place at the large optical depth, then the day-side and the night-side cooling may be comparable. However, if the day-night heat transport is not efficient or if it takes place at a shallow optical depth then there can be a large difference between the day-and the night-side cooling and the night side will cool more efficiently. If stellar irradiation becomes stronger, e.g. owing to stellar evolution or migration, cooling from both the day and the night sides is reduced. Enhanced metallicity of the atmosphere would act as an added "blanket" and reduces both the day-and the night-side cooling. However, a stratosphere on the planetary day side can enhance day-side cooling since its opacity acts as a "sunshade" that screens the stellar irradiation. These effects may also influence the well-known gravity darkening and bolometric albedo effects in interacting binaries, especially for strongly irradiated cold components. © 2012 ESO.


Schouwink P.,University of Geneva | Ley M.B.,University of Aarhus | Jensen T.R.,University of Aarhus | Smrcok L.,Slovak Academy of Sciences | Cerny R.,University of Geneva
Dalton Transactions | Year: 2014

The five novel compounds ALiM(BH4)4 (A = K or Rb; M = Mg or Mn) and K3Li2Mg2(BH4) 9 crystallizing in the space groups Aba2 and P2/c, respectively, represent the first two-dimensional topologies amongst homoleptic borohydrides. The crystal structures have been solved, refined and characterized by synchrotron X-ray powder diffraction, neutron powder diffraction and solid-state DFT calculations. Minimal energies of ordered models corroborate crystal symmetries retrieved from diffraction data. The layered Li-Mg substructure forms negatively charged uninodal 4-connected networks. It is shown that this connectivity cannot generate the long sought-after, bimetallic Li-Mg borohydrides without countercations when assuming preferred coordination polyhedra as found in Mg(BH4)2 and LiBH4. The general properties of the trimetallic compound series are analogous with the anhydrous aluminosilicates. Additionally, a relationship with zeolites is suggested, which are built from three-dimensional Al-Si-O networks with a negative charge on them. The ternary metal borohydride systems are of interest due to their potential as novel hydridic frameworks and will allow exploration of the structural chemistry of light-metal systems otherwise subject to eutectic melting. This journal is © the Partner Organisations 2014.


Feranec J.,Slovak Academy of Sciences | Jaffrain G.,IGN France International | Soukup T.,R.Ø.S.A. | Hazeu G.,Wageningen University
Applied Geography | Year: 2010

The CORINE land cover (CLC) data derived from satellite images for the period of the 1990s and 2000 (± one year) provide information about land cover changes for a substantial part of Europe. Availability of these data can contribute to new approaches to the assessment of the European landscape, for instance in the context of environmental and economic accounting, diversity, modelling of its properties, etc. These possibilities are given by the fact that land cover reflects the biophysical state of the real landscape. The paper contains information about frequency and areas of CLC and their changes in the period 1990-2000, but above all in the processes - flows (LCF) that take place in the European landscape. Results of statistical analysis and maps demonstrate the frequency and rate (by two values: one above and another below the mean LCF rates) of the following processes: urbanisation (LCF1), intensification of agriculture (LCF2), extensification of agriculture (LCF3), afforestation (LCF4), deforestation (LCF5) and construction of water bodies (LCF6). LCF1 was most conspicuous in the Netherlands (2.1% of total country's area), LCF2 in Ireland (3.3%), LCF3 in the Czech Republic (over 3.5%), LCF4 in Portugal (over 4%), LCF5 in Portugal (over 3.5%) and LCF6 in the Netherlands and Slovakia (over 0.1%). The overall area of identified land cover changes in 24 European countries in the period 1990-2000 was around 88,000 km2 which equals 2.5% of their total area. Details presented concerning the LCF frequency and rate will certainly contribute to the overall awareness and anticipation of possible developments in the European landscape. © 2009 Elsevier Ltd. All rights reserved.


Mikula Jr. I.,University of Veterinary Medicine in Kosice | Mikula Jr. I.,Slovak Academy of Sciences | Mikula Sr. I.,Slovak Academy of Sciences
Developmental and Comparative Immunology | Year: 2011

One of the major roles of innate immunity system is the recognition and the determination of the nature of the antigen. This ability is encompassed by specific receptors as Toll-like receptors (TLRs). TLR9 recognizes bacterial and viral CpG motifs, while their potent immunostimulation effect seems to be promising for lentiviral therapies. Recent studies, however, show the presence of a big polymorphism within the TLR genes and the linkage between substitutions and susceptibility to various infections. Moreover, different recognition ability seems to be utilized by different species and possibly breeds. In this study, we characterized the protein coding region of ovine TLR9 gene. By using comparative analysis of two closely related species and humans, we suggest, which characteristics of protein could be responsible for altered recognition. Furthermore, analyzing the presence of the substitutions, we show the intraspecies polymorphism and its possible implications, while attempting to define the association of discovered substitutions with the maedi visna infection. © 2010 Elsevier Ltd.


Serova L.I.,New York Medical College | Laukova M.,New York Medical College | Laukova M.,Slovak Academy of Sciences | Alaluf L.G.,New York Medical College | And 2 more authors.
European Neuropsychopharmacology | Year: 2014

PTSD is a debilitating neuropsychiatric disorder and many patients do not respond sufficiently to current treatments. Neuropeptide Y (NPY) is suggested to provide resilience to the development of PTSD and co-morbid depression. Injections of NPY to the rodent brain are anxiolytic. Recently we showed that intranasal delivery of NPY to rats before or immediately after exposure to single prolonged stress (SPS) animal model of PTSD prevented development of many biochemical and behavioral symptoms of PTSD, indicating its prophylactic potential. Here, we investigated whether intranasal NPY might provide benefits once symptoms have already developed. One week after exposure to SPS stressors, animals were given intranasal NPY or vehicle and tested on elevated plus maze 2. h or 2 days later. The NPY treated rats had lower anxiety-like behavior than vehicle treated rats as indicated by more entries into open arms and fewer into closed arms, lower anxiety index, higher risk assessment and unprotected head dips and reduced grooming time. Their anxiety index was similar to that of unstressed controls. On most of these variables there was no effect of time interval and rats displayed similar overall changes 2. h or 2 days after the infusion. Moreover, intranasal NPY led to reduced depressive-like behavior, assessed by forced swim test. Thus, intranasal NPY reversed several behavioral impairments triggered by the traumatic stress of SPS and has potential for non-invasive PTSD therapeutic intervention. © 2013 Elsevier B.V. and ECNP.


Pey A.L.,University of Granada | Majtan T.,Aurora University | Majtan T.,Slovak Academy of Sciences | Sanchez-Ruiz J.M.,University of Granada | Kraus J.P.,Aurora University
Biochemical Journal | Year: 2013

CBS (cystathionine β-synthase) is a multidomain tetrameric enzyme essential in the regulation of homocysteine metabolism, whose activity is enhanced by the allosteric regulator SAM (S-adenosylmethionine). Missense mutations in CBS are the major cause of inherited HCU (homocystinuria). In the present study we apply a novel approach based on a combination of calorimetric methods, functional assays and kinetic modelling to provide structural and energetic insight into the effects of SAM on the stability and activity of WT (wild-type) CBS and seven HCU-causing mutants. We found two sets of SAM-binding sites in the C-terminal regulatory domain with different structural and energetic features: a high affinity set of two sites, probably involved in kinetic stabilization of the regulatory domain, and a low affinity set of four sites, which are involved in the enzyme activation. We show that the regulatory domain displays a low kinetic stability in WT CBS, which is further decreased in many HCU-causing mutants. We propose that the SAM-induced stabilization may play a key role in modulating steady-state levels of WT and mutant CBS in vivo. Our strategy may be valuable for understanding ligand effects on proteins with a complex architecture and their role in human genetic diseases and for the development of novel pharmacological strategies. © The Authors Journal compilation © 2013 Biochemical Society.


Bergendiova K.,R.Ø.S.A. | Tibenska E.,Medirex a.s. | Majtan J.,Slovak Academy of Sciences | Majtan J.,Slovak Medical University
European Journal of Applied Physiology | Year: 2011

Prolonged and exhausting physical activity causes numerous changes in immunity and sometimes transient increases the risk of upper respiratory tract infections (URTIs). Nutritional supplements as countermeasures to exercise-induced changes have increasingly been studied in the last decade. One of the most promising nutritional supplements is β-glucan, a well-known immunomodulator with positive effects on the function of immunocompetent cells. In this double blind, placebo-controlled study, we investigated the effect of pleuran, an insoluble β-(1,3/1,6) glucan from mushroom Pleurotus ostreatus, on selected cellular immune responses and incidence of URTI symptoms in athletes. Fifty athletes were randomized to pleuran or placebo group, taking pleuran (commercial name Imunoglukan ®) or placebo supplements during 3 months. Venous whole blood was collected before and after 3 months of supplementation and additionally 3 months after supplementation period was completed. Incidence of URTI symptoms together with characterization of changes in phagocytosis and natural killer (NK) cell count was monitored during the study. We found that pleuran significantly reduced the incidence of URTI symptoms and increased the number of circulating NK cells. In addition, the phagocytosis process remained stable in pleuran group during the study in contrast to placebo group where significant reduction of phagocytosis was observed. These findings indicate that pleuran may serve as an effective nutritional supplement for athletes under heavy physical training. Additional research is needed to determine the mechanisms of pleuran function. © Springer-Verlag 2011.


Feranec J.,Slovak Academy of Sciences | Soukup T.,R.Ø.S.A.
Central European Journal of Geosciences | Year: 2013

The landscapes of the world are constantly changing under the influence of human activities leading to the growth of artificial surfaces. The covering of soil by artificial surfaces is referred to as soil sealing. Aerial and satellite images or data derived from them (for instance CORINE land cover - CLC data used here) provide important information that makes it possible to assess the occurrence, area and rate of soil sealing. As the term sealed soil cannot be wholly identified with the content of the appropriate CLC classes, the term land cover flow urbanization (LCFU) will be used here. The essence of this study is the demonstration and documentation of the trends of the LCFU in Europe for the periods 1990-2000 and 2000-2006 on a single map. This may contribute to a better spatial awareness of the ongoing transformation of landscape under the effects of human activities in an pan-European context. Changes in the LCFU can be seen on a map, compiled from 3 × 3 km squares at an all-European scale, using colours and their hues, to fulfil the role both of identification and classification. The colour method employed makes it possible to perceive three groups of LCFU changes on two time horizons, that is, whether the rate of LCFU in 2000-2006 increased or remained the same (hues of red); or dropped compared to the 1990-2000 period (hues of light to dark blue). The third group represents the LCFU with rates higher or lower than the average (countries with changes recorded in only one time horizon are presented in dark and light magenta colours). © 2013 Versita Warsaw and Springer-Verlag Wien.


Monosik R.,Slovak University of Technology in Bratislava | Magdolen P.,Slovak Academy of Sciences | Stredansky M.,R.Ø.S.A. | Sturdik E.,Slovak University of Technology in Bratislava
Food Chemistry | Year: 2013

The aim of the present study was to analyze sugar levels (namely maltose, maltotriose, glucose and fructose) and alcohols (ethanol and glycerol) during the fermentation process in wort samples by amperometric enzymatic biosensors developed by our research group for industrial application, HPLC and spectrophotometry, and to compare the suitability of the presented methods for determination of individual analytes. We can conclude that for the specific monitoring of maltose or maltotriose only the HPLC method was suitable. On the other hand, biosensors and spectrophotometry reflected a decrease in total sugar concentration better and were able to detect both glucose and fructose in the later stages of fermentation, while HPLC was not. This can be attributed to the low detection limits and good sensitivity of the proposed methods. For the ethanol and glycerol analysis all methods proved to be suitable. However, concerning the cost expenses and time analysis, biosensors represented the best option. © 2012 Elsevier Ltd. All rights reserved.


Mandakova T.,Masaryk University | Kovarik A.,Academy of Sciences of the Czech Republic | Zozomova-Lihova J.,Slovak Academy of Sciences | Shimizu-Inatsugi R.,University of Zürich | And 5 more authors.
Plant Cell | Year: 2013

This article describes the use of cytogenomic and molecular approaches to explore the origin and evolution of Cardamine schulzii, a textbook example of a recent allopolyploid, in its ~110-year history of human-induced hybridization and allopolyploidy in the Swiss Alps. Triploids are typically viewed as bridges between diploids and tetraploids but rarely as parental genomes of high-level hybrids and polyploids. The genome of the triploid semifertile hybrid Cardamine × insueta (2n = 24, RRA) was shown to combine the parental genomes of two diploid (2n = 2x = 16) species, Cardamine amara (AA) and Cardamine rivularis (RR). These parental genomes have remained structurally stable within the triploid genome over the >100 years since its origin. Furthermore, we provide compelling evidence that the alleged recent polyploid C. schulzii is not an autohexaploid derivative of C. × insueta. Instead, at least two hybridization events involving C. × insueta and the hypotetraploid Cardamine pratensis (PPPP, 2n = 4x-2 = 30) have resulted in the origin of the trigenomic hypopentaploid (2n = 5x-2 = 38, PPRRA) and hypohexaploid (2n = 6x-2 = 46, PPPPRA). These data show that the semifertile triploid hybrid can promote a merger of three different genomes and demonstrate how important it is to reexamine the routinely repeated textbook examples using modern techniques. © 2013 American Society of Plant Biologists. All rights reserved.


Aube M.,Cegep de Sherbrooke | Kocifaj M.,Slovak Academy of Sciences
Monthly Notices of the Royal Astronomical Society | Year: 2012

Astronomical observations are increasingly limited by light pollution, which is a product of the over-illumination of the night sky. To predict both the angular distribution of scattered light and the ground-reaching radiative fluxes, a set of models has been introduced in recent decades. Two distinct numerical tools, MSNsR Au and ILLUMINA, are compared in this paper, with the aim of identifying their strengths and weaknesses. The numerical experiment comprises the simulation of spectral radiances in the region of the Canary Islands. In particular, the light fields near the Roque de los Muchachos and Teide observatories are computed under various turbidity conditions. It is shown that ILLUMINA has enhanced accuracy at low elevation angles. However, ILLUMINA is time-consuming because of the two scattering orders incorporated into the calculation scheme. Under low-turbidity conditions and for zenith angles smaller than 70° the two models agree well, and thus can be successfully applied to typical cloudless situations at the majority of observatories. MSNsR Au is well optimized for large-scale simulations. In particular, the grid size is adapted dynamically depending on the distance between a light source and a hypothetical observer. This enables rapid numerical modelling for large territories. MSNsR Au is also well suited for the mass modelling of night-sky radiances after ground-based light sources are hypothetically changed. This enables an optimum design of public lighting systems and a time-efficient evaluation of the optical effects related to different lamp spectra or different lamp distributions. ILLUMINA provides two diagnostic geographical maps to help local authorities concerned about light-pollution control. The first map allows the identification of the relative contribution of each ground element to the observed sky radiance at a given viewing angle, while the second map gives the sensitivity, basically saying how each ground element contributes per lumen installed. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.


Aube M.,Cegep de Sherbrooke | Roby J.,Cegep de Sherbrooke | Kocifaj M.,Slovak Academy of Sciences
PLoS ONE | Year: 2013

Artificial light at night can be harmful to the environment, and interferes with fauna and flora, star visibility, and human health. To estimate the relative impact of a lighting device, its radiant power, angular photometry and detailed spectral power distribution have to be considered. In this paper we focus on the spectral power distribution. While specific spectral characteristics can be considered harmful during the night, they can be considered advantageous during the day. As an example, while blue-rich Metal Halide lamps can be problematic for human health, star visibility and vegetation photosynthesis during the night, they can be highly appropriate during the day for plant growth and light therapy. In this paper we propose three new indices to characterize lamp spectra. These indices have been designed to allow a quick estimation of the potential impact of a lamp spectrum on melatonin suppression, photosynthesis, and star visibility. We used these new indices to compare various lighting technologies objectively. We also considered the transformation of such indices according to the propagation of light into the atmosphere as a function of distance to the observer. Among other results, we found that low pressure sodium, phosphor-converted amber light emitting diodes (LED) and LED 2700 K lamps filtered with the new Ledtech's Equilib filter showed a lower or equivalent potential impact on melatonin suppression and star visibility in comparison to high pressure sodium lamps. Low pressure sodium, LED 5000 K-filtered and LED 2700 K-filtered lamps had a lower impact on photosynthesis than did high pressure sodium lamps. Finally, we propose these indices as new standards for the lighting industry to be used in characterizing their lighting technologies. We hope that their use will favor the design of new environmentally and health-friendly lighting technologies. © 2013 Aubé et al.


Heinosaari T.,University of Turku | Miyadera T.,Kyoto University | Ziman M.,Slovak Academy of Sciences
Journal of Physics A: Mathematical and Theoretical | Year: 2016

In the context of a physical theory, two devices, A and B, described by the theory are called incompatible if the theory does not allow the existence of a third device C that would have both A and B as its components. Incompatibility is a fascinating aspect of physical theories, especially in the case of quantum theory. The concept of incompatibility gives a common ground for several famous impossibility statements within quantum theory, such as 'no-cloning' and 'no information without disturbance'; these can be all seen as statements about incompatibility of certain devices. The purpose of this paper is to give a concise overview of some of the central aspects of incompatibility. © 2016 IOP Publishing Ltd.


Hurnikova Z.,Slovak Academy of Sciences | Hurnikova Z.,University of Veterinary Medicine in Kosice | Miterpakova M.,Slovak Academy of Sciences | Mandelik R.,University of Veterinary Medicine in Kosice
Parasitology Research | Year: 2013

Angiostrongylus vasorum is a metastrongyloid nematode that may cause cardiopulmonary disease, neurological signs and coagulopathies in dogs. The parasite has an indirect life cycle with molluscs as intermediate hosts, in which the infective third larval stage develops. Recently, A. vasorum has been repeatedly reported in dogs outside the endemic areas, indicating that this parasite is widely distributed over Europe. This is the first record of an autochthonous infection in a dog from Slovakia that was casually diagnosed during routine preventive parasitological examination. A. vasorum first-stage larvae were recovered using the Baermann technique and identified by length and characteristic tail morphology. The animal originated from Slovakia and had not travelled abroad. The dog had been regularly walked on grass fields with a concentrated presence of common species of Gastropoda and frogs. The owner reported that the dog had been licking and eating grass and it had shown curiosity for molluscs and frogs. The first finding of A. vasorum-infected dog in Slovakia has confirmed that the parasite is spreading beyond the traditional hyperendemic foci, which accentuates the need for monitoring and increasing of disease awareness in primary care clinical practice. © 2013 Springer-Verlag Berlin Heidelberg.


Le Bail A.,University of Maine, France | Smrcok L.,Slovak Academy of Sciences
Powder Diffraction | Year: 2011

The structure of 3,4-diaminopyridin-1-ium dihydrogen phosphate, [C5H3(NH)(NH2)2]+ (H2PO4)-, is solved from conventional X-ray powder diffraction data in direct space (monoclinic unit cell with a = 16.0725(9) Å, b = 7.7301(3) Å, c = 14.6189(9) Å, β = 96.869(1)°, V = 1803.2(2) Å3, Z = 8, and space group I2/c), and optimized by energy minimization in the solid state. In the crystal structure of the title compound, dihydrogenphosphate tetrahedra are linked by strong hydrogen O-H...O bonds forming chains running parallel to the b-axis. Antiparallelly π-π stacked DAP cations form molecular columns in the spaces between the chains. Although the dominant interaction of the molecules with their surroundings is electrostatic, their bonding are further enhanced by N-H...O and C-H...O hydrogen bonds. © 2011 International Centre for Diffraction Data.


Heinosaari T.,University of Turku | Kiukas J.,Aberystwyth University | Reitzner D.,Slovak Academy of Sciences
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2015

The existence of incompatible measurements is a fundamental phenomenon having no explanation in classical physics. Intuitively, one considers given measurements to be incompatible within a framework of a physical theory, if their simultaneous implementation on a single physical device is prohibited by the theory itself. In the mathematical language of quantum theory, measurements are described by POVMs (positive operator valued measures), and given POVMs are by definition incompatible if they cannot be obtained via coarse-graining from a single common POVM; this notion generalizes noncommutativity of projective measurements. In quantum theory, incompatibility can be regarded as a resource necessary for manifesting phenomena such as Clauser-Horne-Shimony-Holt (CHSH) Bell inequality violations or Einstein-Podolsky-Rosen (EPR) steering which do not have classical explanation. We define operational ways of quantifying this resource via the amount of added classical noise needed to render the measurements compatible, i.e., useless as a resource. In analogy to entanglement measures, we generalize this idea by introducing the concept of incompatibility measure, which is monotone in local operations. In this paper, we restrict our consideration to binary measurements, which are already sufficient to explicitly demonstrate nontrivial features of the theory. In particular, we construct a family of incompatibility monotones operationally quantifying violations of certain scaled versions of the CHSH Bell inequality, prove that they can be computed via a semidefinite program, and show how the noise-based quantities arise as special cases. We also determine maximal violations of the new inequalities, demonstrating how Tsirelson's bound appears as a special case. The resource aspect is further motivated by simple quantum protocols where our incompatibility monotones appear as relevant figures of merit. © 2015 American Physical Society. ©2015 American Physical Society.


Schouwink P.,University of Geneva | Ley M.B.,University of Aarhus | Tissot A.,University of Geneva | Hagemann H.,University of Geneva | And 3 more authors.
Nature Communications | Year: 2014

Perovskite materials host an incredible variety of functionalities. Although the lightest element, hydrogen, is rarely encountered in oxide perovskite lattices, it was recently observed as the hydride anion H-, substituting for the oxide anion in BaTiO 3. Here we present a series of 30 new complex hydride perovskite-type materials, based on the non-spherical tetrahydroborate anion BH4 - and new synthesis protocols involving rare-earth elements. Photophysical, electronic and hydrogen storage properties are discussed, along with counterintuitive trends in structural behaviour. The electronic structure is investigated theoretically with density functional theory solid-state calculations. BH 4 -specific anion dynamics are introduced to perovskites, mediating mechanisms that freeze lattice instabilities and generate supercells of up to 16 × the unit cell volume in AB(BH 4) 3. In this view, homopolar hydridic di-hydrogen contacts arise as a potential tool with which to tailor crystal symmetries, thus merging concepts of molecular chemistry with ceramic-like host lattices. Furthermore, anion mixing BH4- → X-(X- =Cl-, Br-, I-) provides a link to the known ABX 3 halides. ©2014 Macmillan Publishers Limited. All rights reserved.


Pardo E.,Slovak Academy of Sciences | Grilli F.,Karlsruhe Institute of Technology
Superconductor Science and Technology | Year: 2012

The AC losses in ReBCO coated conductors are large in situations when the conductors are subjected to a considerable magnetic field, as in rotating machines, transformers and high-field magnets. Roebel cables can reduce the AC losses in these cases. However, computer simulations are needed to interpret the experiments, understand the loss mechanisms, reduce the AC losses by optimizing the Roebel cable and design the cryogenic system. In this paper, we simulate and discuss the AC losses due to an applied magnetic field with an arbitrary angle with respect to the cable and taking into account a realistic anisotropic field dependence of the critical current density. We study the AC losses in the superconductor parts for the limits of very high coupling currents and completely uncoupled strands. The simulations for the uncoupled case also describe a double pancake coil with no transport current. For the simulations, we use two different numerical methods with complementary strengths. This serves as a mutual check of the correctness of the simulation results, which agree with each other. As opposed to what was expected, we found that the AC losses do not only depend on the perpendicular component of the applied magnetic field. We also found that the AC losses for applied fields with an orientation below 7° with the strand surface are reduced by more than one order of magnitude as compared with an untransposed cable. Therefore, we recommend to use Roebel cables for windings with important parallel components, such as transformers and high-field magnets.


Grilli F.,Karlsruhe Institute of Technology | Pardo E.,Vienna University of Technology | Pardo E.,Slovak Academy of Sciences
Superconductor Science and Technology | Year: 2010

Roebel cables are a promising concept for high-current coated conductor cables with low ac loss. In order to optimize their design, simulations are necessary. In this paper we compute the field and current distribution and the ac loss due to either a transport current or an applied magnetic field. We distinguish between the coupled and uncoupled situations. These situations correspond to the limits of low and high resistance between strands in one transposition length, respectively. We perform the simulations with two different methods. One method assumes the critical-state model for the superconductor and calculates the current distribution by minimizing the magnetic energy variation; the other describes the superconductor with a power-law resistivity and uses the finite-element technique for solving the problem. We found that the results from both models agree with each other. Moreover, the coupling strongly influences the current distribution for all cases, as well as the magnetization loss. However, the effect on the transport loss is small. In conclusion, simulations are necessary in order to predict the loss reduction caused by the strand transposition in a Roebel cable. Our simulation methods are useful for these predictions. © 2010 IOP Publishing Ltd.


Nagyova V.,Public Health Authority of the Slovak Republic | Nagy A.,R.Ø.S.A. | Timko J.,Slovak Academy of Sciences
Parasitology Research | Year: 2010

Acanthamoeba keratitis (AK) is a relatively rare disease worldwide. Over the past 10 years, five cases of AK were reported in Slovakia. Four preserved Slovak strains and one strain from the Czech Republic isolated from corneal scrapes of patients with AK are characterised in this study. Genotype identification of isolates is based on sequences of the PCR amplimer GTSA.B1 amplified from 18S ribosomal DNA. A strain isolated from the first patient in 1999 was classified as a rare sequence type T15. This is just the second report in which genotype T15 has been associated with AK. The other three Slovak strains were identified as belonging to the most common genotype T4. The only strain originating from the Czech Republic was classified as sporadically appearing sequence type T3. All isolates were also studied for their temperature tolerance and growth characteristics. The cythopatic effect was tested in vitro on Vero cell cultures. © Springer-Verlag 2010.


Nostramo R.,New York Medical College | Tillinger A.,Slovak Academy of Sciences | Serova L.,New York Medical College | Kvetnansky R.,Slovak Academy of Sciences | Sabban E.L.,New York Medical College
Endocrinology | Year: 2013

Bradykinin, acting via the bradykinin B2 receptor (B2R), is a potent stimulator of adrenomedullary catecholamine biosynthesis and release and likely plays an important role in the adrenomedullary stress response. However, the effects of stress on the expression of this receptor in the adrenal medulla are currently unclear. Here, we examined the changes in adrenomedullary B2R gene expression in male rats in response to single (1 time) and repeated (6 times) exposure to 2 hours immobilization stress (IMO). Immediately after 1 or 6 times IMO, B2R mRNA levels were increased by 9-fold and 7-fold, respectively, and returned to unstressed control levels 3 hours later. This large, but transient, increase in mRNA elicited a doubling of protein levels 3 hours after the stress exposure. Next, the role of the hypothalamic-pituitary-adrenocortical axis in the stress-induced upregulation of B2R gene expression was examined. Treatment with endogenous (corticosterone) and synthetic (dexamethasone) glucocorticoids dose-dependently increased B2R mRNA levels in adrenomedullary-derived PC12 cells. Furthermore, cortisol supplementation at levels mimicking stress exposure elevated B2R mRNA levels in the adrenal medulla of hypophysectomized rats. In response to 1 exposure to IMO, the stress-triggered rise in plasma corticosterone and adrenomedullary B2R mRNA levels was attenuated in CRH-knockout mice and absent in pharmacologically adrenalectomized rats, indicating a requirement for glucocorticoids in the upregulation of B2R gene expression with stress. Overall, the increase in B2R gene expression in response to the stress-triggered rise in glucocorticoids likely enhances catecholamine biosynthesis and release and may serve as an adaptive response of the adrenomedullary catecholaminergic system to stress. Copyright © 2013 by The Endocrine Society.


Grant
Agency: European Commission | Branch: H2020 | Program: IA | Phase: NMBP-18-2016 | Award Amount: 9.03M | Year: 2017

Sustainability of energy systems goes through high penetration of renewable energy with huge volumes of electricity to transmit over long distances. The most advanced solution is the HVDC Supergrid. But fault currents remain an issue even if DC circuit breakers have emerged. These are not satisfying, whereas Superconducting Fault Current Limiters (SCFCLs) using REBCO tapes bring an attractive solution. SCFCLs have already proved their outstanding performances in MVAC systems, with a few commercial devices in service. However, present REBCO conductors cannot be readily used at very high voltages: the electrical field under current limitation is too low and leads to too long tapes and high cost. FASTGRID aims to improve and modify the REBCO conductor, in particular its shunt, in order to significantly enhance (2 to 3 times) the electric field and so the economical SCFCL attractiveness. A commercial tape will be upgraded to reach a higher critical current and enhanced homogeneity as compared to todays standards. For safer and better operation, the tapes normal zone propagation velocity will be increased by at least a factor of 10 using the patented current flow diverter concept. The shunt surface will also be functionalized to boost the thermal exchanges with coolant. This advanced conductor will be used in a smart DC SCFCL module (1 kA 50 kV). This one will include new functionalities and will be designed as sub-element of a real HVDC device. In parallel to this main line of work, developments will be carried out on a promising breakthrough path: ultra high electric field tapes based on sapphire substrates. FASTGRID will bring this to the next levels of technology readiness. In conclusion, FASTGRID project aims at improving significantly existing REBCO conductor architecture to make SCFCLs economically attractive for HVDC Supergrids. However, availability of such an advanced conductor will have an impact on virtually all other applications of HTS tapes.


Sadovsky Z.,Slovak Academy of Sciences | Guedes Soares C.,University of Lisbon
Reliability Engineering and System Safety | Year: 2011

Probabilistic assessment of post-buckling strength of thin plate is a difficult problem because of computational effort needed to evaluate single collapse load. The difficulties arise from the nonlinear behaviour of an in-plane loaded plate showing up multiple equilibrium states with possible bifurcations, snap-through or smooth transitions of states. The plate strength depends heavily on the shape of geometrical imperfection of the plate mid-surface. In this paper, an artificial neural network (ANN) is employed to approximate the collapse strength of plates as a function of the geometrical imperfections. For the training set, mainly theoretical imperfections with the corresponding collapse loads of plate calculated by FEM are considered. The ANN validation is based on the measured imperfections of ship plating and FEM strength. © 2011 Elsevier Ltd. All rights reserved.


Grant
Agency: European Commission | Branch: FP7 | Program: CP-FP | Phase: SSH-2007-6.1-01 | Award Amount: 1.92M | Year: 2008

Our overall aim is to help find better ways of using indicators in all aspects of policy, but with a thematic focus on the role of indicators in fostering and supporting change in areas of policy making towards Sustainable Development. The research area of indicators in the presumed service of sustainability will provide a rich ground for addressing the actual use, influence and impacts of indicators, reflecting dynamic interactions between forces for policy continuation and versus policy change. . The objectives of the project are to: Design a coherent framework of analysis and generate hypotheses on the use and influence of indicators, by pulling together the disparate strands of research and practical experience of indicator use and influence, focusing broadly on European policies, but with a special emphasis on fostering change towards sustainability Test the analytical framework and the hypotheses on specific cases of sector integration and sustainability indicators, as well as composite indicators (indices) in order to identify the ways in which indicators influence policy, including the unintended types of influence and situations of non-use; and Identify factors that condition the way in which indicators influence policies, including the process and the outcome of designing and producing indicators, the type of indicators, expectations of stakeholders involved, the role of the organisations preparing and disseminating the indicators, as well as general socio-cultural and political background factors. Recommend ways to enhance the role of indicators in supporting policies


Grant
Agency: European Commission | Branch: FP7 | Program: CP-IP | Phase: NMP.2011.2.2-1 | Award Amount: 20.10M | Year: 2012

High current coated conductors (CCs) have high potential for developing electrical power applications and very high field magnets. The key issues for market success are low cost robust processes, high performance and a reliable manufacturing methodology of long length conductors. In recent years EU researchers and companies have made substantial progress towards these goals, based on vacuum (PLD) and chemical deposition (CSD) methods, towards nanostructuring of films. This provides a unique opportunity for Europe to integrate these advances in high performance conductors. The EUROTAPES project will address two broad objectives: 1/ the integration of the latest developments into simple conductor architectures for low and medium cost applications and to deliver \500m tapes. Defining of quality control tools and protocols to enhance the processing throughput and yield to achieve a pre-commercial cost target of 100 /kAm. 2/ Use of advanced methodologies to enhance performance (larger thickness and Ic, enhanced pinning for high fields, reduction of ac losses, increased mechanical strength). Demonstration of high critical currents (Ic>400A/cm-w, at 77K and self-field and Ic>1000A/cm-w at 5K and 15T) and pinning forces (Fp>100GN/m3 at 60 K). The CSD and PLD technologies will be combined to achieve optimized tape architectures, nanostructures and processes to address a variety of HTS applications at self-field, high and ultrahigh magnetic fields. Up to month 36, 3 types of conductors will be developed (RABiT, ABAD and round wire); at Mid Term 2 will be chosen for demonstration during the final 18 months. The consortium consists of 20 partners from 8 member states 6 universities (Cambridge, UK; Antwerp, B, U.A. Barcelona, ES, TU Cluj, RO, U. Ghent, BE and TU Wien, A), 5 institutes (CSIC-ICMAB, E, ENEA, I, IEE, SK, Inst. Neel-CNRS, F, and IFW, D), 1 technological center (LEITAT, ES) and 8 industrial companies (Bruker, D, Evico, D, Theva, D, Nexans GmbH, D, Percotech, D, Nexans SA, F, Lafarga Lacambra, ES and Oxolutia, ES).


Grant
Agency: European Commission | Branch: FP7 | Program: CP | Phase: ENERGY.2012.2.3.1 | Award Amount: 5.24M | Year: 2012

SUPRAPOWER is a research project focused on a major innovation in offshore wind turbine technology by developing a new compact superconductor-based generator. The project aims to provide an important breakthrough in offshore wind industrial solutions by designing an innovative, lightweight, robust and reliable 10 MW class offshore wind turbine based on a superconducting (SC) generator, taking into account all the essential aspects of electric conversion, integration and manufacturability. Todays geared as well as direct-drive permanent magnet generators are difficult to scale up further. Their huge size and weight drives up the cost of both fixed and floating foundations as well as O&M cost. New solutions to provide better power scalability, weight reduction and reliability are needed. Superconductivity may be the only technology able to combine such features and allow scaling to 10 MW and beyond by radical reduction of the head mass. SUPRAPOWER will pursue the following general objectives: To reduce turbine head mass, size and cost of offshore wind turbines by means of a compact superconducting generator. To reduce O&M and transportation costs and increase life cycle using an innovative direct drive system. To increase the reliability and efficiency of high power wind turbines by means of drive-train specific integration in the nacelle. Starting from an already patent-applied concept, the coordinator has assembled a top-class European consortium from 7 countries. Industrial partners are a wind turbine manufacturer, an energy company, an SME superconducting wire developer, a cryogenic systems supplier, and an offshore engineering company. In addition to the coordinator, research partners are a large laboratory with deep experience in superconductivity, a university and a national institute. The main outcome of the project will be a proof of concept for a key European technology to scale wind turbines up to power levels of 10MW and beyond


Hurai V.,Slovak Academy of Sciences | Paquette J.-L.,University Blaise Pascal | Huraiova M.,Comenius University | Konecny P.,Geological Survey
Journal of Volcanology and Geothermal Research | Year: 2010

Phreatomagmatic eruptions in the Lučenec Basin in Slovakia ejected fragments of igneous rocks of unknown age and ranging in composition from gabbro to syenite and orthopyroxene granodiorite - pincinite. Two kinds of syenites with different Fe3+ contents composed of anorthoclase and interstitial metaluminous trachyte-to-alkali rhyolite glass represent the final products of alkali basalt differentiation at depths of 10 and 15-18km. Pincinite composed of plagioclase, quartz, orthopyroxene, ilmenite and interstitial peraluminous dacite glass is a quenched supersolidus anatectic melt formed at the depth of 17-20km by high-temperature dehydration melting of biotite-bearing gneissic protolith. Zircon from pincinite and syenite, and monazite from syenite were dated using excimer laser ablation ICP-MS. The obtained ages cluster at 5.8 ± 0.1 and 5.4 ± 0.1. Ma, thus corroborating the genetic link between the two rock-types and constraining the residence time of at least 300 ± 100. ka of the parental basalt in the deep crustal magma storage zones. The inferred ages overlap the Upper Miocene-Pliocene boundary, and are considerably younger than spatially associated basaltic lava flows dated using the K/Ar method. Consequently, the fluviolacustrine Poltár Formation overlying the maar structure must have sedimented during the Pliocene and not during the Upper Miocene (Pontian) as previously assumed. © 2010 Elsevier B.V.


Lihova J.,Slovak Academy of Sciences | Kudoh H.,Kyoto University | Marhold K.,Charles University
American Journal of Botany | Year: 2010

Premise of the study: Studies on genetic structure of plant populations help us understand the history of local flora and vegetation. In this study, we focus on the temperate-boreal herb Cardamine scutata from northeast Asia, an area with scarce phylogeographic studies. We explore patterns of genetic variation within this species, with an aim to infer its (post-) glacial history with reference to colonization routes and migrations via land bridges. Methods: We analyzed 46 populations sampled in Japan, Kamchatka, and Korea using AFLP and cpDNA sequence data. Key results: Two intraspecific genetic groups were resolved, distributed in the northeastern and southwestern part of the study area, most likely reflecting lineages isolated from each other during (at least) the last glaciation. A zone of secondary contacts was found in central/northern Honshu, and a few cases of long-distance dispersal were observed. We detected efficient gene flow across the marine straits, supporting the role of land bridges created by sea level decline during the last glacial period. The cpDNA data indicated extensive recent expansion and diversification within both lineages. We inferred recent colonization of Kamchatka from Hokkaido, associated with genetic impoverishment. Conclusions: The pattern of north-south genetic differentiation found in C. scutata is rather common among several other plant species studied in Japan, despite their distinct biological features. We assume that different processes and factors may have brought about this similarity. Overall, this study contributes to better understanding of the biogeography of northeast Asia. © 2010 Botanical Society of America.


Mihalkovic M.,Cornell University | Mihalkovic M.,Slovak Academy of Sciences | Henley C.L.,Cornell University
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

By fitting to a database of ab initio forces and energies, we can extract pair potentials for alloys with a simple six-parameter analytic form including Friedel oscillations, which give a remarkably faithful account of many complex intermetallic compounds. Furthermore, such potentials are combined with a method of discovering complex zero-temperature structures with hundreds of atoms per cell, given only the composition and the constraint of known lattice parameters, using molecular-dynamics quenches. We apply this approach to structure prediction in the Al-Cu-Sc quasicrystal-related system. © 2012 American Physical Society.


Kruger D.H.,Institute of Medical Virology | Figueiredo L.T.M.,University of Sao Paulo | Song J.-W.,Korea University | Klempa B.,Institute of Medical Virology | Klempa B.,Slovak Academy of Sciences
Journal of Clinical Virology | Year: 2015

Hantaviruses are emerging zoonotic viruses which cause human disease in Africa, America, Asia, and Europe. This review summarizes the progress in hantavirus epidemiology and diagnostics during the previous decade. Moreover, we discuss the influence of ecological factors on the worldwide virus distribution and give an outlook on research perspectives for the next years. © 2014 Elsevier B.V.


Mandakova T.,Masaryk University | Marhold K.,Slovak Academy of Sciences | Marhold K.,Charles University | Lysak M.A.,Masaryk University
New Phytologist | Year: 2014

The origin of Cardamine flexuosa (Wavy Bittercress) has been a conundrum for more than six decades. Here we identify its parental species, analyse its genome structure in comparison to parental genomes and describe intergenomic structural variations in C. flexuosa. Genomic in situ hybridization (GISH) and comparative chromosome painting (CCP) uncovered the parental genomes and the chromosome composition of C. flexuosa and its presumed diploid progenitors. Cardamine flexuosa is an allotetraploid (2n = 4x = 32), originating from two diploid species, Cardamine amara and Cardamine hirsuta (2n = 2x = 16). The two parental species display almost perfectly conserved chromosomal collinearity for seven out of the eight chromosomes. A 13 Mb pericentric inversion distinguishes chromosome CA1 from CH1. A comparative cytomolecular map was established for C. flexuosa by CCP/GISH. Whereas conserved chromosome collinearity between the C. amara and C. hirsuta subgenomes might have promoted intergenomic rearrangements through homeologous recombination, only one reciprocal translocation between two homeologues has occurred since the origin of C. flexuosa. The genome of C. flexuosa demonstrates that allopolyploids can maintain remarkably stable subgenomes over 104-105 yr throughout a wide distribution range. By contrast, the rRNA genes underwent genome-specific elimination towards a diploid-like number of loci. © 2013 New Phytologist Trust.


Orvosova M.,Slovak Museum of Nature Protection and Speleology | Deininger M.,University of Heidelberg | Milovsky R.,Slovak Academy of Sciences
Boreas | Year: 2014

Coarse crystalline cryogenic cave carbonate (CCC) forms during the slow freezing of standing water pools and represents indirect proof of freezing temperature in the past. The dating by U-series of CCC deposits from nine caves in the Western Carpathians Mountains of Slovakia suggests that freezing conditions, and possible permafrost conditions, occurred during the Last Permafrost Maximum (LPM, c.20-18 ka BP). The CCC deposits occur in caves at elevations of between 800 and 1800ma.s.l. They point to widespread alpine permafrost, the lower limit of discontinuous/sporadic permafrost being approximately 800ma.s.l. The thickness of permafrost probably varied between 30 and 180m. In the Vysoké Tatry Mountains at altitudes of ~1800ma.s.l., one occurrence of CCC suggests that subzero temperatures may have penetrated to a depth of over 285m. © 2013 The Boreas Collegium.


Wang J.,Guizhou University | Zhou Y.,Xiangtan University | Feckan M.,Comenius University | Feckan M.,Slovak Academy of Sciences
Nonlinear Dynamics | Year: 2013

In this paper, a generalized Darbo's fixedpoint theorem associated with Hausdorff measure of noncompactness is established. Then we apply this new variant fixed-point theorem to study some fractional differential equations in Banach spaces via the technique of measure of noncompactness. Many novel existence and uniqueness results for solutions are obtained under the more general conditions. © Springer Science+Business Media B.V. 2012.


Karmazinova M.,Slovak Academy of Sciences | Baumgart J.P.,Cornell University | Perez-Reyes E.,University of Virginia | Lacinova L.,Slovak Academy of Sciences
Pflugers Archiv European Journal of Physiology | Year: 2011

Low-voltage-activated Ca V3 Ca 2+ channels have an activation threshold around -60 mV, which is lower than the activation threshold of other voltage-dependent calcium channels (VDCCs). The kinetics of their activation at membrane voltages just above the activation threshold is much slower than the activation kinetics of other VDCCs. It was demonstrated recently that the intracellular loop connecting repeats I and II of all three Ca V3 channels contains a so-called gating brake. Disruption of this brake yields channels that activate at even more hyperpolarized potentials with significantly accelerated kinetics. We have compared gating of a wild-type Ca V3.3 channel and a mutated ID12 channel, in which the putative gating brake at the proximal part of the I-II loop was removed. Voltage dependence of the gating current activation was shifted by 34.6 mV towards more hyperpolarized potentials in ID12 channel. ON-charge movement was significantly faster in the ID12 channel, while the kinetics of the off-charge was not altered by the mutation. We conclude that the putative gating brake in I-II loop hinders not only the opening of the conducting pore but also the activating movement of voltage-sensing S4 segments, stabilizing the channel in its closed state. © 2011 Springer-Verlag.


Lukan M.,University of Zilina | Lukan M.,Slovak Academy of Sciences | Bullova E.,Slovak Academy of Sciences | Petko B.,Slovak Academy of Sciences | Petko B.,Catholic University in Ruzomberok
Emerging Infectious Diseases | Year: 2010

Increased tick-borne encephalitis (TBE) cases have been reported in central Europe. To investigate temporal trends in the altitude at which TBE cases occur in Slovakia, we analyzed the number of TBE cases during 1961-2004. Since 1980, TBE cases moved from lowlands to submountainous areas, most likely because of rising temperature.


Mihalkovic M.,Slovak Academy of Sciences | Henley C.L.,Cornell University
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

Using pair potentials fitted to an ab initio database, combined with replica-exchange simulated annealing, we show that the complex, quasicrystal-related Al11Ir4 compound contains a nonstandard version of the "pseudo-Mackay" icosahedral cluster, with nonicosahedral inner Al10Ir and/or Al9Ir clusters that exist in various orientations and account for partial occupancies in the reported structure. We found two different compositions with different orientationally ordered grounds, each doubling the (cubic) unit cell and each reached by a first-order thermal transition. One of these is metallic and the other is insulating. © 2013 American Physical Society.


Chowdhury P.,University of Calcutta | Kudela K.,Slovak Academy of Sciences | Dwivedi B.N.,Banaras Hindu University
Solar Physics | Year: 2013

Galactic cosmic rays (GCRs) encounter an outward-moving solar wind with cyclic magnetic-field fluctuation and turbulence. This causes convection and diffusion in the heliosphere. The GCR counts from the ground-based neutron monitor stations show intensity changes that are anti-correlated with the sunspot numbers with a lag of a few months. GCRs experience various types of modulation from different solar activity features and influence space weather and the terrestrial climate. In this work, we investigate certain aspects of the GCR modulation at low cut-off rigidity (Rc≈1 GV) in relation to some solar and geomagnetic indices for the entire solar cycle 23 (1996 - 2008). We separately study the GCR modulation during the ascending phase of cycle 23 including its maximum (1996 - 2002) and the descending phase including its minimum (2003 - 2008). We find that during the descending phase, the GCR recoveries are much faster than those of the solar parameters with negative time-lag. The results are discussed in light of modulation models, including drift effects and previous results. © 2013 Springer Science+Business Media Dordrecht.


Musatov A.,University of Texas Health Science Center at San Antonio | Musatov A.,Slovak Academy of Sciences
Journal of Biological Inorganic Chemistry | Year: 2013

The effect of heparin on peroxidation of cardiolipin (CL) initiated by ferrous iron was studied in vitro using detergent-solubilized CL, liposomal CL, or CL bound to isolated cytochrome c oxidase (CcO). Heparin increased both the rate and the extent of CL peroxidation for detergent-solubilized CL and for CcO-bound CL. The effect of heparin was time- and concentration-dependent as monitored by the formation of conjugated dienes or thiobarbituric acid reactive substances. The results showed great similarity between the effect of heparin and the effect of certain iron chelators, such as ADP, on phospholipid peroxidation. Heparin increased the peroxidation of CcO-bound CL only when tertiary butyl hydroperoxide was also present. The enzyme activity of the resulting CcO complex decreased 25 %, in part due to peroxidation of functionally important CL. In contrast to peroxidation of detergent-solubilized CL, peroxidation of liposomal CL was inhibited by heparin, suggesting that the effect of heparin and ferrous iron depends on their proximity to the acyl chains of CL. © 2013 SBIC.


Bartanusz V.,University of Texas Health Science Center at San Antonio | Jezova D.,Slovak Academy of Sciences | Alajajian B.,University of Texas Health Science Center at San Antonio | Digicaylioglu M.,University of Texas Health Science Center at San Antonio
Annals of Neurology | Year: 2011

The blood-spinal cord barrier (BSCB) is the functional equivalent of the blood-brain barrier (BBB) in the sense of providing a specialized microenvironment for the cellular constituents of the spinal cord. Even if intuitively the BSCB could be considered as the morphological extension of the BBB into the spinal cord, evidence suggests that this is not so. The BSCB shares the same principal building blocks with the BBB; nevertheless, it seems that morphological and functional differences may exist between them. Dysfunction of the BSCB plays a fundamental role in the etiology or progression of several pathological conditions of the spinal cord, such as spinal cord injury, amyotrophic lateral sclerosis, and radiation-induced myelopathy. This review summarizes current knowledge of the morphology of the BSCB, the methodology of studying the BSCB, and the potential role of BSCB dysfunction in selected disorders of the spinal cord, and finally summarizes therapeutic approaches to the BSCB. © 2011 American Neurological Association.


Kaplan Z.,Academy of Sciences of the Czech Republic | Marhold K.,Slovak Academy of Sciences | Marhold K.,Charles University
Botanical Journal of the Linnean Society | Year: 2012

The Potamogeton compressus group is a complex of three to five closely related species with a circumpolar distribution in the Northern Hemisphere. Multivariate morphometric analyses (principal component analysis, cluster analysis, canonical and classificatory discriminant analyses) were used to elucidate the patterns of variation within this group and to test the morphological differentiation of the species recognized in the current literature. From the entire distribution range, 156 specimens of the group were included in the numerical methods. Results from morphological comparison are discussed in relation to molecular data, reproductive behaviour and geographical distribution. Morphometric analyses provided evidence that this complex can be clearly divided into three groups, one of which was subdivided mainly on the basis of allopatric occurrence and genetic differentiation. These groups correspond to four species accepted here: P.acutifolius (temperate regions of Europe), P.compressus (boreal and temperate regions of Europe and Asia), P.manchuriensis (northeastern China and Russian Far East) and P.zosteriformis (boreal and temperate regions of North America). Two species, P.acutifolius and P.compressus, are partly sympatric, but clearly differentiated morphologically and genetically, and effectively isolated reproductively. Endemic P.manchuriensis is characterized by a unique combination of characters and an occurrence in a limited geographical area. Allopatric P.zosteriformis is weakly differentiated morphologically from P.compressus, but differs markedly in molecular markers correlated with geographical differentiation. It may represent a cryptic species. In contrast, a recently suggested concept of southern Siberian P.henningii was not supported by our analyses. Plants so named are considered here as slender phenotypes of the widespread and variable P.compressus. © 2012 The Linnean Society of London.


Ermilov S.G.,Nizhniy Novgorod Referral Center | Kaluz S.,Slovak Academy of Sciences
Systematic and Applied Acarology | Year: 2012

Two new oribatid mite species, Hermannobates bifurcatus sp. nov. (Hermanniellidae) and Xenillus brevisetosus sp. nov. (Liacaridae), are described from Ecuador. Hermannobates bifurcatus sp. nov. is similar to Hermannobates monstruosus Hammer in having the combination of a tuberculate prodorsum, foveolate notogaster, and long setiform prodorsal and exuvial notogastral setae and sensilli. However it clearly differs from the latter by having some bifurcate epimeral setae, the surface of the prodorsum, and the lengths of some notogastral setae. Xenillus brevisetosus sp. nov. is similar to Xenillus davisorum J. & P. Balogh in having the combination of the same body surface sculpture and the morphology of the lamellar complex, sensilli, and prodorsal and notogastral setae. However it clearly differs from the latter by the length of the lamellar cusps, interlamellar setae and notogastral setae h1, and number of genital setae. An identification key to Ecuadorian species of Xenillus is presented. © 2012 Systematic & Applied Acarology Society.


Pazda A.D.,University of Rochester | Prokop P.,University of Trnava | Prokop P.,Slovak Academy of Sciences | Elliot A.J.,University of Rochester
Personality and Social Psychology Bulletin | Year: 2014

Research has shown that men perceive women wearing red, relative to other colors, as more attractive and more sexually receptive; women’s perceptions of other women wearing red have scarcely been investigated. We hypothesized that women would also interpret female red as a sexual receptivity cue, and that this perception would be accompanied by rival derogation and intentions to mate-guard. Experiment 1 demonstrated that women perceive another woman in a red, relative to white, dress as sexually receptive. Experiment 2 demonstrated that women are more likely to derogate the sexual fidelity of a woman in red, relative to white. Experiment 3 revealed that women are more likely to intend to guard their romantic partner from a woman wearing a red, relative to a green, shirt. These results suggest that some color signals are interpreted similarly across sex, albeit with associated reactions that are sex-specific. © 2014 by the Society for Personality and Social Psychology, Inc.


Ermilov S.G.,Nizhniy Novgorod Referral Center | Kaluz S.,Slovak Academy of Sciences
International Journal of Acarology | Year: 2012

Two new oribatid mite species of Oppiidae, Gittella ecuadoriensis sp. nov. and Lasiobelba (Antennoppia) chistyakovi sp. nov., are described from Ecuador. Gittella and Lasiobelba are recorded for the first time from Ecuador. Gittella ecuadoriensis sp. nov. differs from all species of the genus by the selective characters (long, setiform and smooth notogastral setae, granulate body surface, sensilli with long cilia, absence of muscle sigilla in interbothridial and epimeral regions). Lasiobelba (Antennoppia) chistyakovi sp. nov. differs from all species of the subgenus by the setiform sensilli with long cilia and localization of lamellar setae nearer to interlamellar setae, than rostral setae. An identification key to all known species of Gittella is presented. © 2012 Taylor & Francis.


Ermilov S.G.,Nizhniy Novgorod Referral Center | Kaluz S.,Slovak Academy of Sciences
Annales Zoologici | Year: 2012

A new oribatid mite subgenus, Perscheloribates (Ecuadoribates) subgen. nov., and three new species, Perscheloribates (Ecuadoribates) pentasacculus sp. nov., Fissurobates neotropicus sp. nov. and Mucrobates microsetosus sp. nov., of the family Scheloribatidae are described from Ecuador. The new subgenus differs from Perscheloribates (Perscheloribates) by the number of notogastral sacculi and number of genital setae. Fissurobates and Mucrobates are recorded for the first time in Ecuador. The morphology of gnathosoma and legs are presented for the first time for any member of Fissurobates and Mucrobates. © Fundacja Natura optima dux.


Mihalkovic M.,Slovak Academy of Sciences | Henley C.L.,Cornell University
Philosophical Magazine | Year: 2011

In i-ScZn, like other quasicrystals of the i-CaCd class, the innermost shell of the icosahedral cluster is a Zn4 tetrahedron, which thus breaks the symmetry of the outer cluster shells. We investigate theoretically the dynamics of individual tetrahedra, using interatomic pair potentials, fitted from an ab initio database, and molecular dynamics (MD). This includes the formulation of an effective Hamiltonian written in terms of a rigid-body rotation representing the state of each tetrahedron. We characterize the minimum-energy orientations of a tetrahedron, as well as the paths of the transitions between minima (reorientations). The velocity autocorrelations were evaluated for the tetrahedral atoms in the MD dynamics; the corresponding spectral density S(ω) is fairly well fitted by a simplified model in which each atom hops in a double well. © 2011 Taylor & Francis.


Simko F.,Comenius University | Simko F.,Slovak Academy of Sciences | Reiter R.J.,University of Texas Health Science Center at San Antonio | Pechanova O.,Slovak Academy of Sciences | And 2 more authors.
Frontiers in Bioscience | Year: 2013

Melatonin secreted by the pineal gland plays an important role in the regulation of blood pressure (BP) and its administration reduces hypertension both in animals and humans. There are two experimental models of melatonindeficient hypertension: one induced by pinealectomy and another by continuous 24 hour exposure to light. Both models cause melatonin deficiency and prevent darknessmediated nocturnal melatonin secretion and are associated with increased BP and myocardial, vascular and renal dysfunction. These models also lead to neurohumoral activation of the renin-angiotensin system, sympathetic nervous system, adrenocorticotrophin-glucocorticoid axis and cause insulin resistance. Together, these alterations contribute to rise in blood pressure by vasoconstrictive or circulatory fluid volume overload. The light induced hypertension model mimics the melatonin deficiency in patients with insufficient nocturnal BP decline, in those who have night shift or who are exposed to environmental light pollution. For this reason, this model is useful in development of anti-hypertensive drugs.


Wang J.,Guizhou University | Zhou Y.,Xiangtan University | Feckan M.,Comenius University | Feckan M.,Slovak Academy of Sciences
Computers and Mathematics with Applications | Year: 2012

In this paper, the first purpose is treating Cauchy problems and boundary value problems for nonlinear impulsive differential equations with Caputo fractional derivative. We introduce the concept of piecewise continuous solutions for impulsive Cauchy problems and impulsive boundary value problems respectively. By using a new fixed point theorem, we obtain many new existence, uniqueness and data dependence results of solutions via some generalized singular Gronwall inequalities. The second purpose is discussing Ulam stability for impulsive fractional differential equations. Some new concepts in stability of impulsive fractional differential equations are offered from different perspectives. Some applications of our results are also provided. © 2011 Elsevier Ltd. All rights reserved.


Wang J.,Guizhou University | Zhou Y.,Xiangtan University | Feckan M.,Comenius University | Feckan M.,Slovak Academy of Sciences
Computers and Mathematics with Applications | Year: 2012

This paper is motivated from some recent papers treating the boundary value problems for impulsive fractional differential equations. We first make a counterexample to show that the formula of solutions in cited papers are incorrect. Second, we establish a general framework to find the solutions for impulsive fractional boundary value problems, which will provide an effective way to deal with such problems. Third, some sufficient conditions for the existence of the solutions are established by applying fixed point methods. Meanwhile, data dependence is obtained by using a new generalized singular Gronwall inequality. Finally, three examples are given to illustrate the results. © 2011 Elsevier Ltd. All rights reserved.


Hajek M.,Masaryk University | Horsak M.,Masaryk University | Tichy L.,Masaryk University | Hajkova P.,Masaryk University | And 2 more authors.
Journal of Biogeography | Year: 2011

Aim The term relict refers to a formerly widespread species currently occurring in refugia that provide a persistent combination of specific ecological conditions. In peatlands, direct palaeoecological evidence of relict status exists for some plant species and, in the case of calcareous sediments, for some snail species. We tested whether some species are significantly linked to old calcareous fens at the millennial scale independent of the effect of recent fen area. We focused on three organism groups - vascular plants, bryophytes and land snails - that differ in the degree of preservation of their remains in calcareous fen sediments and in their dispersal ability. Location Western Carpathians (Slovakia and the Czech Republic). Methods The sample sites comprised 47 well-preserved calcareous fens, from which we compiled complete recent species lists, measured the area and analysed radiocarbon-dated samples from the deepest sediment and from the beginning of complete deforestation, as indicated by plant and snail fossils. Using the species co-occurrences in large data sets, we identified calcareous fen specialists and compared their recent distribution patterns against a null model that controlled for the effect of fen area. Results Two land snail species, eleven vascular plant species and no bryophyte species have statistically significant affinities with old fens, independent of the effect of recent fen area. For one bryophyte and one snail, the effects of age and area are not distinguishable. Main conclusions The results for land snails, being abundantly preserved and easily determinable in calcareous fen deposits, are in full accordance with the direct macrofossil evidence. This suggests that our approach indirectly revealed a relict distribution of the species. Identification of species that are significantly linked to ancient localities at the millennial scale has great potential in palaeoecology for the detection of stands with old sediments, and in nature conservation as a tool for the identification of long-term-persisting rare species that infrequently colonize young sites and thus deserve priority in the protection of their habitats. From a theoretical perspective, limited dispersal from old to new localities of the same habitat can contribute to spatial effects in biotic assemblages, even at relatively fine scales. © 2010 Blackwell Publishing Ltd.


Bravyi S.,IBM | Caha L.,Masaryk University | Movassagh R.,Massachusetts Institute of Technology | Nagaj D.,Slovak Academy of Sciences | Shor P.W.,Massachusetts Institute of Technology
Physical Review Letters | Year: 2012

Frustration-free (FF) spin chains have a property that their ground state minimizes all individual terms in the chain Hamiltonian. We ask how entangled the ground state of a FF quantum spin-s chain with nearest-neighbor interactions can be for small values of s. While FF spin-1/2 chains are known to have unentangled ground states, the case s=1 remains less explored. We propose the first example of a FF translation-invariant spin-1 chain that has a unique highly entangled ground state and exhibits some signatures of a critical behavior. The ground state can be viewed as the uniform superposition of balanced strings of left and right brackets separated by empty spaces. Entanglement entropy of one half of the chain scales as 12logn+O(1), where n is the number of spins. We prove that the energy gap above the ground state is polynomial in 1/n. The proof relies on a new result concerning statistics of Dyck paths which might be of independent interest. © 2012 American Physical Society.


Kruzliak P.,St Annes University Hospital Brno | Kruzliak P.,Slovak Academy of Sciences | Novak J.,St Annes University Hospital Brno | Novak J.,Masaryk University | Novak M.,St Annes University Hospital Brno
American Journal of Hypertension | Year: 2014

Hypertension is the most common adverse effect of the inhibitors of vascular endothelial growth factor (VEGF) pathway-based therapy (VEGF pathway inhibitors therapy, VPI therapy) in cancer patients. VPI includes monoclonal antibodies against VEGF, tyrosine kinase inhibitors, VEGF Traps, and so-called aptamers that may become clinically relevant in the future. All of these substances inhibit the VEGF pathway, which in turn causes a decrease in nitric oxide (NO) and an increase in blood pressure, with the consequent development of hypertension and its final events (e.g., myocardial infarction or stroke). To our knowledge, there is no current study on how to provide an optimal therapy for patients on VPI therapy with hypertension. This review summarizes the roles of VEGF and NO in vessel biology, provides an overview of VPI agents, and suggests a potential treatment procedure for patients with VPI-induced hypertension. © American Journal of Hypertension, Ltd 2013.


Filippov S.N.,Slovak Academy of Sciences | Filippov S.N.,Moscow Institute of Physics and Technology | Ziman M.,Slovak Academy of Sciences | Ziman M.,Masaryk University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2013

We fully characterize bipartite entanglement-annihilating (EA) channels that destroy entanglement of any state shared by subsystems and, thus, should be avoided in any entanglement-enabled experiment. Our approach relies on extending the problem to EA positive maps, the cone of which remains invariant under concatenation with partially positive maps. Due to this invariancy, positive EA maps adopt a well characterization and their intersection with completely positive trace-preserving maps results in the set of EA channels. In addition to a general description, we also provide sufficient operational criteria revealing EA channels. They have a clear physical meaning since the processes involved contain stages of classical information transfer for subsystems. We demonstrate the applicability of derived criteria for local and global depolarizing noises, and specify corresponding noise levels beyond which any initial state becomes disentangled after passing the channel. The robustness of some entangled states is discussed. © 2013 American Physical Society.


Kruzliak P.,Slovak Academy of Sciences | Kruzliak P.,Masaryk University | Kovacova G.,University Hospital | Pechanova O.,Slovak Academy of Sciences
Angiogenesis | Year: 2013

Angiogenesis is critical to tumor growth as well as to metastases. This process is tightly regulated by pro- and anti-angiogenic growth factors and their receptors. Some of these factors are highly specific for the endothelium - e.g., vascular endothelial growth factor (VEGF). A variety of drugs that target VEGF or its receptors have been developed for the treatment of different tumor types and a number of new agents is expected to be introduced within the coming years. However, clinical experience has revealed that inhibition of VEGF induces several side effects including hypertension and renal and cardiac toxicity. Angiogenesis-inhibitor-induced hypertension represents "crux medicorum" as it is often pharmacoresistant to antihypertensive therapy. We consider two most important pathomechanisms in the development of hypertension induced by angiogenesis inhibitors. The first represents direct inhibition of NO production leading to reduced vasodilatation and the second consists in increased proliferation of vascular medial cells mediated by NO deficiency and is resulting in fixation of hypertension. Based on the results of experimental and clinical studies as well as on our clinical experience, we assume that NO donors could be successfully used not only for the treatment of developed angiogenesis-inhibitor-induced hypertension but also for preventive effects. We thoroughly documented three clinical cases of cancer patients with resistant hypertension who on receiving NO donor treatment achieved target blood pressure level and a good clinical status. © 2012 The Author(s).


Palecek E.,Academy of Sciences of the Czech Republic | Tkac J.,Slovak Academy of Sciences | Bartosik M.,Masaryk Memorial Cancer Institute | Bertok T.,Slovak Academy of Sciences | And 2 more authors.
Chemical Reviews | Year: 2015

Significant progress has been done in the electrochemical (EC) analysis of practically all proteins, based on the electroactivity of amino acid (aa) residues in proteins. From a transducer point of view, it can be anticipated that many different ways of how nanomaterials can be integrated into the EC detection platform of detection will be developed. This can be done by direct modification of electroactive surfaces by nanomaterials or by advanced patterning protocol and by using nanomaterials as amplification tags, helping to produce lectin biosensors/biochips working in an ultrasensitive and selective way. Further, it can be anticipated that EC-based biosensors will compete in a future with instrumental techniques or lectin microarrays only if such devices are integrated into a biochip format offering multiplexed glycan measurements. Moreover, it has been shown that some glucosamine-containing poly- and oligosaccharides are electroactive under conditions close to physiological and that most polysaccharides and glycans can be transformed into electrochemically active substances by a simple chemical modification. Usually 4-10 biomarkers have to be detected to obtain good specificity and selectivity of detection. EC detection appears particularly advantageous for the preparation of low-density chips with this number of biomarkers.


Moravcikov L.,Slovak Academy of Sciences | Ziman M.,Slovak Academy of Sciences | Ziman M.,Masaryk University
Journal of Physics A: Mathematical and Theoretical | Year: 2010

We introduce and investigate a family of entanglement-annihilating channels. These channels are capable of destroying any quantum entanglement within the system they act on. We show that they are not necessarily entanglement breaking. In order to achieve this result we analyze the subset of locally entanglement-annihilating channels. In this case, the same local noise applied on each subsystem individually is less entanglement annihilating (with respect to multi-partite entanglement) as the number of subsystems is increasing. Therefore, the bipartite case provides restrictions on the set of local entanglement-annihilating channels for the multipartite case. The introduced concepts are illustrated on the family of single-qubit depolarizing channels. © 2010 IOP Publishing Ltd.


Plescha M.,Slovak Academy of Sciences | Pivoluska M.,Masaryk University
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2014

Expansion and amplification of weak randomness with untrusted quantum devices has recently become a very fruitful topic of research. Here we contribute with a procedure for amplifying a single weak random source using tri-partite GHZ-type entangled states. If the quality of the source reaches a fixed threshold R = log2 (10), perfect random bits can be produced. This technique can be used to extract randomness from sources that can't be extracted neither classically, nor by existing procedures developed for Santha-Vazirani sources. Our protocol works with a single fault-free device decomposable into three non-communicating parts, that is repeatedly reused throughout the amplification process. © 2014 Elsevier B.V. All rights reserved.


Tvaroska I.,Slovak Academy of Sciences | Tvaroska I.,Masaryk University | Kozmon S.,Masaryk University | Wimmerova M.,Masaryk University | Koca J.,Masaryk University
Journal of the American Chemical Society | Year: 2012

In higher eukaryotes, a variety of proteins are post-translationally modified by adding O-linked N-acetylglucosamine (GlcNAc) residue to serine or threonine residues. Misregulation of O-GlcNAcylation is linked to a wide variety of diseases, such as diabetes, cancer, and neurodegenerative diseases, including Alzheimers disease. GlcNAc transfer is catalyzed by an inverting glycosyltransferase O-GlcNAc transferase (uridine diphospho-N-acetylglucosamine: polypeptide β-N-acetylaminyltransferase, OGT) that belongs to the GT-B superfamily. The catalytic mechanism of this metal-independent glycosyltransferase is of primary importance and is investigated here using QM(DFT)/MM methods. The structural model of the reaction site used in this paper is based on the crystal structures of OGT. The entire enzyme-substrate system was partitioned into two different subsystems: the QM subsystem containing 198 atoms, and the MM region containing 11 326 atoms. The catalytic mechanism was monitored by means of three two-dimensional potential energy maps calculated as a function of three predefined reaction coordinates at different levels of theory. These potential energy surfaces revealed the existence of a concerted SN2-like mechanism, in which a nucleophilic attack by O Ser, facilitated by proton transfer to the catalytic base, and the dissociation of the leaving group occur almost simultaneously. The transition state for the proposed reaction mechanism at the MPW1K level was located at C1-OSer = 1.92 Å and C1-O1 = 3.11 Å. The activation energy for this passage was estimated to be ∼20 kcal mol-1. These calculations also identified, for the first time for glycosyltransferases, the substrate-assisted mechanism in which the N-acetamino group of the donor participates in the catalytic mechanism. © 2012 American Chemical Society.


Betakova T.,Slovak Academy of Sciences | Betakova T.,Max Delbrück Center for Molecular Medicine | Svancarova P.,Slovak Academy of Sciences
Acta Virologica | Year: 2013

RNA interference (RNAi) is a naturally occurring endogenous biological post-transcriptional cellular mechanism that regulates RNA expression. Small interfering RNAs (siRNAs), mediators of RNAi, are short (19-26nt), double-stranded RNA duplexes that inhibit gene expression by inducing sequence-specific degradation of homologous messenger RNA (mRNA). Influenza virus infection is a major public health problem, causing hundreds of thousands of deaths worldwide each year. RNAi have provided a means to performing genome-wide screens to determine and validate host cell genes that may be required for influenza replication and treatment with siRNA specific to regions of the influenza genes which can inhibit influenza virus replication. Moreover, influenza virus is using small RNA in the regulation of virus replication and in modulation of the innate immune signalling system of the host.


Jiraskova G.,Slovak Academy of Sciences | Klima O.,Masaryk University
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

A biautomaton is a finite automaton which arbitrarily alternates between reading the input word from the left and from the right. Some compatibility assumptions in the formal definition of a biautomaton ensure that the acceptance of an input does not depend on the way how the input is read. The paper studies the constructions of biautomata from the descriptional point of view. It proves that the tight bounds on the size of a biautomaton recognizing a regular language represented by a deterministic or nondeterministic automaton of n states, or by a syntactic monoid of size n, are n•2 n - 2(n - 1), 2 2n - 2(2 n - 1), and n 2, respectively. © 2012 Springer-Verlag Berlin Heidelberg.


Sedlak M.,Palacky University | Sedlak M.,Slovak Academy of Sciences | Ziman M.,Slovak Academy of Sciences | Ziman M.,Masaryk University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2014

We study discrimination of m quantum measurements in the scenario when the unknown measurement with n outcomes can be used only once. We show that ancilla-assisted discrimination procedures provide a nontrivial advantage over simple (ancilla-free) schemes for perfect distinguishability and we prove that inevitably m≤n. We derive necessary and sufficient conditions of perfect distinguishability of general binary measurements. We show that the optimization of the discrimination of projective qubit measurements and their mixtures with white noise is equivalent to the discrimination of specific quantum states. In particular, the optimal protocol for discrimination of projective qubit measurements with fixed failure rate (exploiting maximally entangled test state) is described. While minimum-error discrimination of two projective qubit measurements can be realized without any need of entanglement, we show that discrimination of three projective qubit measurements requires a bipartite probe state. Moreover, when the measurements are not projective, the non-maximally entangled test states can outperform the maximally entangled ones. Finally, we rephrase the unambiguous discrimination of measurements as quantum key distribution protocol. © 2014 American Physical Society.


Huber M.,University of Vienna | Plesch M.,Masaryk University | Plesch M.,Slovak Academy of Sciences
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

In tasks where multipartite entanglement plays a central role, state purification is, due to inevitable noise, a crucial part of the procedure. We consider a scenario exploiting the multipartite entanglement in a straightforward multipartite purification algorithm and compare it to bipartite purification procedures combined with state teleportation. While complete purification requires an infinite amount of input states in both cases, we show that for an imperfect output fidelity the multipartite procedure exhibits a major advantage in terms of input states used. © 2011 American Physical Society.


Farinon S.,National Institute of Nuclear Physics, Italy | Fabbricatore P.,National Institute of Nuclear Physics, Italy | Gomory F.,Slovak Academy of Sciences
Superconductor Science and Technology | Year: 2010

The commercially available finite element code ANSYS has been adapted to solve the critical state of single strips and multifilamentary tapes. We studied a special algorithm which approaches the critical state by an iterative adjustment of the material resistivity. Then, we proved its validity by comparing the results obtained for a thin strip to the Brand theory for the transport current and magnetization cases. Also, the challenging calculation of the magnetization loss of a real multifilamentary BSCCO tape showed the usefulness of our method. Finally, we developed several methods to enhance the speed of convergence, making the proposed process quite competitive in the existing survey of ac losses simulations. © 2010 IOP Publishing Ltd.


Filippov S.N.,Moscow Institute of Physics and Technology | Ziman M.,Slovak Academy of Sciences | Ziman M.,Masaryk University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2014

We analyze general laws of continuous-variable entanglement dynamics during the deterministic attenuation and amplification of the physical signal carrying the entanglement. These processes are inevitably accompanied by noises, so we find fundamental limitations on noise intensities that destroy entanglement of Gaussian and non-Gaussian input states. The phase-insensitive amplification Φ1 - Φ2 - ΦN with the power gain κi≥2 (≈3 dB, i=1,..,N) is shown to destroy entanglement of any N-mode Gaussian state even in the case of quantum-limited performance. In contrast, we demonstrate non-Gaussian states with the energy of a few photons such that their entanglement survives within a wide range of noises beyond quantum-limited performance for any degree of attenuation or gain. We detect entanglement preservation properties of the channel Φ1 - Φ2, where each mode is deterministically attenuated or amplified. Gaussian states of high energy are shown to be robust to very asymmetric attenuations, whereas non-Gaussian states are at an advantage in the case of symmetric attenuation and general amplification. If Φ1=Φ2, the total noise should not exceed 12κ2+1 to guarantee entanglement preservation. © 2014 American Physical Society.


Kocifaj M.,Slovak Academy of Sciences | Klacka J.,Comenius University | Kelling T.,University of Duisburg - Essen | Wurm G.,University of Duisburg - Essen
Icarus | Year: 2011

Temperature gradients in dust beds embedded in a low pressure gaseous environment induce a lift of particles under certain conditions. This effect can erode planetesimals and enables entrainment of dust into the martian atmosphere. Here, we consider a numerical model to calculate the temperature profile in a dust bed which is subject to illumination. We consider the situation when the illumination is switched on and heats the dust bed's surface and when it is switched off again after a certain time. The calculations focus on the heat transfer by infrared radiation within the dust layer. We find that radiative transfer within the dust bed modifies the absolute temperatures and temperature gradients significantly. This is important for effects which are sensitive to absolute temperatures, i.e. ice sublimation or melting of solids. For low thermal conductivity dust beds of 0.001Wm -1K -1 it determines the temperature structure of the dust. For higher thermal conductivities the modifications are moderate with respect to dust eruptions as the order of magnitude of temperature gradients stays the same. © 2010 Elsevier Inc.


Paulis L.,Comenius University | Paulis L.,Charité - Medical University of Berlin | Simko F.,Slovak Academy of Sciences | Laudon M.,Discovery at Neurim Pharmaceuticals Ltd
Expert Opinion on Investigational Drugs | Year: 2012

Introduction: Melatonin synchronizes circadian rhythms with light/dark period and it was demonstrated to correct chronodisruption. Several melatonin receptor agonists with improved pharmacokinetics or increased receptor affinity are being developed, three of them are already in clinical use. However, the actions of melatonin extend beyond chronobiology to cardiovascular and metabolic systems as well. Given the high prevalence of cardiovascular disease and their common occurrence with chronodisruption, it is of utmost importance to classify the cardiometabolic effects of the newly approved and putative melatoninergic drugs. Areas covered: In the present review, the available (although very sparse) data on such effects, in particular by the approved (circadin, ramelteon, agomelatine) or clinically advanced (tasimelteon, piromelatine Neu-P11, TIK-301) compounds are summarized. The authors have searched for an association with blood pressure, vascular reactivity, ischemia, myocardial and vascular remodeling and metabolic syndrome. Expert opinion: The data suggest that cardiovascular effects of melatonin are at least partly mediated via MT1/MT2 receptors and associated with its chronobiotic action. Therefore, despite the sparse direct evidence, it is believed that these effects will be shared by melatonin analogs as well. With the expected approval of novel melatoninergic compounds, it is suggested that the investigation of their cardiovascular effects should no longer be neglected. © Informa UK, Ltd.


Kruzliak P.,Slovak Academy of Sciences | Kruzliak P.,Masaryk University | Pechanova O.,Slovak Academy of Sciences | Kara T.,Masaryk University | Kara T.,Rochester College
Heart Failure Reviews | Year: 2014

Nitric oxide (NO) is often used to treat heart failure accompanied with pulmonary edema. According to present knowledge, however, NO donors are contraindicated when systolic blood pressure is less than 90 mmHg. Based on recent findings and our own clinical experience, we formulated a hypothesis about the new breakthrough complex lifesaving effects of NO donors in patients with cardiac arrest and cardiopulmonary resuscitation therapy. It includes a direct hemodynamic effect of NO donors mediated through vasodilation of coronary arteries in cooperation with improvement of cardiac function and cardiac output through reversible inhibition of mitochondrial complex I and mitochondrial NO synthase, followed by reduction in reactive oxygen species and correction of myocardial stunning. Simultaneously, an increase in vascular sensitivity to sympathetic stimulation could lead to an increase in diastolic blood pressure. Confirmation of this hypothesis in clinical practice would mean a milestone in the treatment for cardiac arrest and cardiopulmonary resuscitation. © 2013 The Author(s).


Hillery M.,City College of New York | Reitzner D.,Slovak Academy of Sciences | Buzek V.,Slovak Academy of Sciences
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2010

We show how a quantum walk can be used to find a marked edge or a marked complete subgraph of a complete graph. We employ a version of a quantum walk, the scattering walk, which lends itself to experimental implementation. The edges are marked by adding elements to them that impart a specific phase shift to the particle as it enters or leaves the edge. If the complete graph has N vertices and the subgraph has K vertices, the particle becomes localized on the subgraph in O(N/K) steps. This leads to a quantum search that is quadratically faster than a corresponding classical search. We show how to implement the quantum walk using a quantum circuit and a quantum oracle, which allows us to specify the resources needed for a quantitative comparison of the efficiency of classical and quantum searches-the number of oracle calls. © 2010 The American Physical Society.


Tenzer R.,University of Otago | Gladkikh V.,University of Otago | Novak P.,University of West Bohemia | Vajda P.,Slovak Academy of Sciences
Surveys in Geophysics | Year: 2012

We analyse spatial and spectral characteristics of various refined gravity data used for modelling and gravimetric interpretation of the crust-mantle interface and the mantle-lithosphere structure. Depending on the purpose of the study, refined gravity data have either a strong or weak correlation with the Moho depths (Moho geometry). The compilation of the refined gravity data is purely based on available information on the crustal density structure obtained from seismic surveys without adopting any isostatic hypothesis. We demonstrate that the crust-stripped relative-to-mantle gravity data have a weak correlation with the CRUST2. 0 Moho depths of about 0. 02. Since gravitational signals due to the crustal density structure and the Moho geometry are subtracted from gravity field, these refined gravity data comprise mainly the information on the mantle lithosphere and sub-lithospheric mantle. On the other hand, the consolidated crust-stripped gravity data, obtained from the gravity field after applying the crust density contrast stripping corrections, comprise mainly the gravitational signal of the Moho geometry, although they also contain the gravitational signal due to anomalous mass density structures within the mantle. In the absence of global models of the mantle structure, the best possible option of computing refined gravity data, suitable for the recovery/refinement of the Moho interface, is to subtract the complete crust-corrected gravity data from the consolidated crust-stripped gravity data. These refined gravity data, that is, the homogenous crust gravity data, have a strong absolute correlation of about 0. 99 with the CRUST2. 0 Moho depths due to removing a gravitational signal of inhomogeneous density structures within the crust and mantle. Results of the spectral signal decomposition and the subsequent correlation analysis reveal that the correlation of the homogenous crust gravity data with the Moho depths is larger than 0. 9 over the investigated harmonic spectrum up to harmonic degree 90. The crust-stripped relative-to-mantle gravity data correlate substantially with the Moho depths above harmonic degree 50 where the correlation exceeds 0. 5. © 2012 Springer Science+Business Media B.V.


Stano P.,Slovak Academy of Sciences | Stano P.,University of Basel | Jacquod P.,University of Arizona | Jacquod P.,University of Geneva
Nature Photonics | Year: 2013

Understanding random lasing is a formidable theoretical challenge. Unlike conventional lasers, random lasers have no resonator to trap light, they are highly multimode with potentially strong modal interactions, and they are based on disordered gain media, where photons undergo random multiple scattering. Interference effects notoriously modify the propagation of waves in such random media, but their fate in the presence of nonlinearity and interactions is poorly understood. Here, we present a semiclassical theory for multimode random lasing in the strongly scattering regime. We show that Anderson localization, a wave interference effect, is not affected by the presence of nonlinearities. To the contrary, its presence suppresses interactions between simultaneously lasing modes. Consequently, each lasing mode in a strongly scattering random laser is given by a single long-lived, Anderson localized mode of the passive cavity, the frequency and wave profile of which do not vary with pumping, even in the multimode regime when modes spatially overlap. © 2013 Macmillan Publishers Limited.


Gosset D.,University of Waterloo | Nagaj D.,Slovak Academy of Sciences
SIAM Journal on Computing | Year: 2016

Quantum satisfiability is a constraint satisfaction problem that generalizes classical boolean satisfiability. In the quantum k-SAT problem, each constraint is specified by a k-local projector and is satisfied by any state in its nullspace. Bravyi showed that quantum 2-SAT can be solved efficiently on a classical computer and that quantum k-SAT with k ≥ 4 is QMA1-complete [S. Bravyi, Efficient Algorithm for a Quantum Analogue of 2-SAT, eprint arXiv:quant-ph/0602108, 2006]. Quantum 3-SAT was known to be contained in QMA1 [Bravyi, 2006], but its computational hardness was unknown until now. We prove that quantum 3-SAT is QMA1-hard, and therefore complete for this complexity class. © 2016 Society for Industrial and Applied Mathematics.


Pincak R.,Slovak Academy of Sciences | Pincak R.,Joint Institute for Nuclear Research | Bartos E.,Slovak Academy of Sciences
Physica A: Statistical Mechanics and its Applications | Year: 2015

Overwhelming majority of econometric models applied on a long term basis in the financial forex market do not work sufficiently well. The reason is that transaction costs and arbitrage opportunity are not included, as this does not simulate the real financial markets. Analyses are not conducted on the non equidistant date but rather on the aggregate date, which is also not a real financial case. In this paper, we would like to show a new way how to analyze and, moreover, forecast financial market. We utilize the projections of the real exchange rate dynamics onto the string-like topology in the OANDA market. The latter approach allows us to build the stable prediction models in trading in the financial forex market. The real application of the multi-string structures is provided to demonstrate our ideas for the solution of the problem of the robust portfolio selection. The comparison with the trend following strategies was performed, the stability of the algorithm on the transaction costs for long trade periods was confirmed.


Majtan T.,University of Colorado at Denver | Majtan T.,Slovak Academy of Sciences | Liu L.,University of Colorado at Denver | Carpenter J.F.,University of Colorado at Denver | Kraus J.P.,University of Colorado at Denver
Journal of Biological Chemistry | Year: 2010

Missense mutations represent the most common cause of many genetic diseases including cystathionine β-synthase (CBS) deficiency. Many of these mutations result in misfolded proteins, which lack biological function. The presence of chemical chaperones can sometimes alleviate or even restore protein folding and activity of mutant proteins. We present the purification and characterization of eight CBS mutants expressed in the presence of chemical chaperones such as ethanol, dimethyl sulfoxide, or trimethylamine-N-oxide. Preliminary screening in Escherichia coli crude extracts showed that their presence during protein expression had a significant impact on the amount of recovered CBS protein, formation of tetramers, and catalytic activity. Subsequently, we purified eight CBS mutants to homogeneity (P49L, P78R, A114V, R125Q, E176K, P422L, I435T, and S466L). The tetrameric mutant enzymes fully saturated with heme had the same or higher specific activities than wild type CBS. Thermal stability measurements demonstrated that the purified mutants are equally or more thermostable than wild type CBS. The response to S-adenosyl-L-methionine stimulation or thermal activation varied. The lack of response of R125Q and E176K to both stimuli indicated that their specific conformations were unable to reach the activated state. Increased levels of molecular chaperones in crude extracts, particularly DnaJ, indicated a rather indirect effect of the chemical chaperones on folding of CBS mutants. In conclusion, the chemical chaperones present in the expression medium were able to fully restore the activity of eight CBS mutants by improving their protein folding. This finding could have direct implications for the development of a therapeutical approach to pyridoxine unresponsive homocystinuria. © 2010 by The American Society for Biochemistry and Molecular Biology, Inc.


Betak E.,Slovak Academy of Sciences | Betak E.,Silesian University in Opava
Nuclear Data Sheets | Year: 2014

We address the angular momentum effects within the state density approach to the Iwamoto-Harada-(Bisplinghoff) model of the pre-equilibrium cluster emission. Using this way, the cluster emission is independent of the cluster formation probability, which - using a rough approximation - contains also all angular momenta couplings related to the creation of a cluster in nuclear reaction. Consequently, the angular-momentum part of the cluster emission rate is formally the same as it is in the nucleon emission case (but energy parts are substantially different). The 197Au(p,α) reaction at 62 MeV serves as an illustration of the suggested model. Inclusion of spin variables causes the enhancement of the α channel (and a weakening of the sum of nucleon channels due to particle emission competition) compared to the spin-independent case. © 2014.


Hoi H.,Austrian Academy of Sciences | Kristin A.,Slovak Academy of Sciences | Valera F.,CSIC - Estación Experimental De Zonas Áridas | Hoi C.,Austrian Academy of Sciences
Oecologia | Year: 2012

In order to understand habitat selection, it is important to consider the way individual animals assess the suitability of a future reproductive site. One way of investigating mechanisms (such as those involved in nest site selection) is to examine breeding success and habitat characteristics in terms of animals returning to a place where they have already reproduced and using the same location over successive years or searching for new alternatives. This approach seems especially suitable for testing recent hypotheses suggesting that nest site selection is an integrative process that includes the use of social information (e. g. past breeding success of conspecifics). Determining the factors that elicit conservative or innovative behaviour regarding nest-site selection could be important for improving our understanding of habitat selection decisions in animals. More than half of the nests of the long-distance migratory lesser grey shrike Lanius minor, are built in the same or neighbouring trees. We found no evidence that habitat characteristics influence nest-site tradition. On the contrary, social information in terms of the presence of conspecifics and past reproductive success in terms of complete nest failures due to nest predation (but not detailed information such as variation in fledgling number) influenced nest-site tradition. Hence, social information and past reproductive success may play a role in nest-site choice in this species. Our results further demonstrate that previous experience with a nest site does not appear to be beneficial. © 2011 Springer-Verlag.


Thorson M.K.,University of Utah | Majtan T.,Slovak Academy of Sciences | Kraus J.P.,University of Colorado at Denver | Barrios A.M.,University of Utah
Angewandte Chemie - International Edition | Year: 2013

Buzzing with activity: A hydrogen sulfide selective fluorogenic probe, 7-azido-4-methylcoumarin (AzMC), serves as a highly sensitive assay for cystathionine β-synthase activity, and is suitable for the high-throughput discovery of novel enzyme inhibitors. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Lukac B.,Slovak Central Observatory | Rybansky M.,Slovak Academy of Sciences
Solar Physics | Year: 2010

The original coronal index of the solar activity (CI) has been constructed on the basis of ground-based measurements of the intensities of the coronal line of 530. 3 nm (Rybanský in Bull. Astron. Inst. Czechoslov., 28, 367, 1975; Rybanský et al. in J. Geophys. Res., 110, A08106, 2005). In this paper, CI is compared with the EUV measurements on the CELIAS/SEM equipment based on the same idea as the original idea of the coronal index. The correlation is very good for the period 1996 - 2005 (r=0. 94 for daily values). The principal result of this paper is the introduction of the modified coronal index (MCI) which in all uses and contexts can replace the existing CI index. Daily MCI values extend over a time period of six solar activity cycles. Future MCI measurements will be derived from more reliable measurements made by space-based observatories that are not influenced by the weather. MCI measurements are and will continue to be archived at the web site of the Slovak Central Observatory in Hurbanovo (http://www.suh.sk/obs/vysl/MCI.htm). © Springer Science+Business Media B.V. 2010.


Hapala I.,Slovak Academy of Sciences | Marza E.,University of Bordeaux Segalen | Ferreira T.,Slovak Academy of Sciences | Ferreira T.,University of Poitiers
Biology of the Cell | Year: 2011

LDs (lipid droplets) have long been considered as inert particles used by the cells to store fatty acids and sterols as esterified non-toxic lipid species (i.e. triacylglycerols and steryl esters). However, accumulating evidence suggests that LDs behave as a dynamic compartment, which is involved in the regulation of several aspects of the homoeostasis of their originating organelle, namely the ER (endoplasmic reticulum). The ER is particularly sensitive to physiological/pathological stimuli, which can ultimately induce ER stress. In the present review, after considering the basic mechanisms of LD formation and the signal cascades leading to ER stress, we focus on the connections between these two pathways. Taking into consideration recent data from the literature, we will try to draw possible mechanisms for the role of LDs in the regulation of ER homoeostasis and in ER-stress-related diseases. © The Authors Journal compilation. © 2011 Portland Press Limited.


Raith M.,University of Regensburg | Stano P.,Slovak Academy of Sciences | Stano P.,University of Basel | Fabian J.,University of Regensburg
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

Highly accurate numerical results of phonon-induced two-electron spin relaxation in silicon double quantum dots are presented. The relaxation, enabled by spin-orbit coupling and the nuclei of 29Si (natural or purified abundance), is investigated for experimentally relevant parameters, the interdot coupling, the magnetic field magnitude and orientation, and the detuning. We calculate relaxation rates for zero and finite temperatures (100 mK), concluding that our findings for zero temperature remain qualitatively valid also for 100 mK. We confirm the same anisotropic switch of the axis of prolonged spin lifetime with varying detuning as recently predicted in GaAs. Conditions for possibly hyperfine-dominated relaxation are much more stringent in Si than in GaAs. For experimentally relevant regimes, the spin-orbit coupling, although weak, is the dominant contribution, yielding anisotropic relaxation rates of at least two orders of magnitude lower than in GaAs. © 2012 American Physical Society.


Baruffa F.,University of Regensburg | Stano P.,Slovak Academy of Sciences | Stano P.,University of Arizona | Fabian J.,University of Regensburg
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

The influence of the spin-orbit interactions on the energy spectrum of two-electron laterally coupled quantum dots is investigated. The effective Hamiltonian for a spin qubit pair proposed in Baruffa [Phys. Rev. Lett. 104, 126401 (2010)]10.1103/PhysRevLett.104.126401 is confronted with exact numerical results in single and double quantum dots in zero and finite magnetic field. The anisotropic exchange Hamiltonian is found quantitatively reliable in double dots in general. There are two findings of particular practical importance: (i) the model stays valid even for maximal possible interdot coupling (a single dot), due to the absence of a coupling to the nearest excited level, a fact following from the dot symmetry. (ii) In a weak-coupling regime, the Heitler-London approximation gives quantitatively correct anisotropic exchange parameters even in a finite magnetic field, although this method is known to fail for the isotropic exchange. The small discrepancy between the analytical model (which employs the linear Dresselhaus and Bychkov-Rashba spin-orbit terms) and the numerical data for GaAs quantum dots is found to be mostly due to the cubic Dresselhaus term. © 2010 The American Physical Society.


Saniga M.,Slovak Academy of Sciences | Levay P.,Budapest University of Technology and Economics
EPL | Year: 2012

Mermin's pentagram, a specific set of ten three-qubit observables arranged in quadruples of pairwise commuting ones into five edges of a pentagram and used to provide a very simple proof of the Kochen-Specker theorem, is shown to be isomorphic to an ovoid (elliptic quadric) of the three-dimensional projective space of order two, PG(3, 2). This demonstration employs properties of the real three-qubit Pauli group embodied in the geometry of the symplectic polar space W(5, 2) and rests on the facts that: 1) the four observables/operators on any of the five edges of the pentagram can be viewed as points of an affine plane of order two, 2) all the ten observables lie on a hyperbolic quadric of the five-dimensional projective space of order two, PG(5, 2), and 3) that the points of this quadric are in a well-known bijective correspondence with the lines of PG(3, 2). Copyright © EPLA, 2012.


Filippov S.N.,Moscow Institute of Physics and Technology | Rybar T.,Slovak Academy of Sciences | Ziman M.,Slovak Academy of Sciences | Ziman M.,ETH Zurich
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

We address the problem of the robustness of entanglement of bipartite systems (qubits) interacting with dynamically independent environments. In particular, we focus on the characterization of so-called local entanglement-annihilating (EA) two-qubit channels, which set the maximum permissible noise level allowing us to perform entanglement-enabled experiments. The differences, but also the subtle relations, between entanglement-breaking and local EA channels are emphasized. A detailed characterization of the latter ones is provided for a variety of channels including depolarizing, unital, (generalized) amplitude-damping, and extremal channels. We also consider the convexity structure of local EA qubit channels and introduce a concept of EA duality. © 2012 American Physical Society.


Dubnicka S.,Slovak Academy of Sciences | Dubnickova A.Z.,Comenius University | Ivanov M.A.,Joint Institute for Nuclear Research | Korner J.G.,Johannes Gutenberg University Mainz
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2010

We explore the consequences of treating the X(3872) meson as a tetraquark bound state. As dynamical framework we employ a relativistic constituent quark model which includes infrared confinement in an effective way. We calculate the decay widths of the observed channels X→J/ψ+2π(3π) and X→D̄0+D0+π0 via the intermediate off-shell states X→J/ψ+ρ(ω) and X→D̄+D*. For reasonable values of the size parameter ΛX of the X(3872) we find consistency with the available experimental data. We also discuss the possible impact of the X(3872) in a s-channel dominance description of the J/ψ dissociation cross section. © 2010 The American Physical Society.


Baruffa F.,University of Regensburg | Stano P.,Slovak Academy of Sciences | Stano P.,University of Arizona | Fabian J.,University of Regensburg
Physical Review Letters | Year: 2010

The effects of spin-orbit coupling on the two-electron spectra in lateral coupled quantum dots are investigated analytically and numerically. It is demonstrated that in the absence of magnetic field, the exchange interaction is practically unaffected by spin-orbit coupling, for any interdot coupling, boosting prospects for spin-based quantum computing. The anisotropic exchange appears at finite magnetic fields. A numerically accurate effective spin Hamiltonian for modeling spin-orbit-induced two-electron spin dynamics in the presence of magnetic field is proposed. © 2010 The American Physical Society.


Dubnicka S.,Slovak Academy of Sciences | Dubnickova A.Z.,Comenius University | Ivanov M.A.,Joint Institute for Nuclear Research | Liptaj A.,Slovak Academy of Sciences
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

The covariant quark model represents an appropriate theoretical framework to describe the recent results on Bs→J/ψ+η and B s→J/ψ+η′ decays from the Belle and LHCb collaborations. In this article, we present the main features of the covariant quark model together with details on some of its aspects and methods, which we consider to be important. Further, we apply the model specifically to the studied decay processes and give numerical results on decay widths as they follow from the model. We conclude that the model, with most of its parameters previously fixed from different processes, is able to incorporate the new experimental measurements. In particular, we found that the ratio of the branching fractions of the decays Bs into J/ψ+η ′ and J/ψ+η is equal to R≈0.86, in agreement with the data reported by the Belle and LHCb collaborations. © 2013 American Physical Society.


Kodera P.,Comenius University | Heinrich C.A.,ETH Zurich | Walle M.,ETH Zurich | Lexa J.,Slovak Academy of Sciences
Geology | Year: 2014

The recently discovered Biely Vrch deposit in the Western Carpathian magmatic arc is the most extreme example of a porphyry gold deposit, being practically free of copper, molybdenum or any other sulfi de minerals. Microanalytical data on fl uid inclusions in quartz veinlets, including a characteristic type of banded veinlets, show that this deposit formed from nearly anhydrous Fe-K-Na-Cl salt melts containing ~10ppm Au, coexisting with hydrous vapor of very low density. This exceptional fl uid evolution required an Fe-rich dioritic source magma that was emplaced at shallow subvolcanic depth (<3.5km), directly exsolving a hypersaline liquid and magmatic vapor at high temperature (~850 oC). During ascent to the level of the porphyry intrusion (0.5-1km), fl uid expansion at high temperature but low pressure led to halite precipitation and further water loss to the vapor, generating an increasingly Fe-K-rich salt melt that transported high concentrations of Au but negligible Cu into the fractured porphyry stock. The low sulfur fugacity resulting from fl uid expansion suppressed precipitation of sulfi de, explaining the goldonly enrichment in this globally recurring but rare type of gold ore.


Cavallero S.,University of Rome La Sapienza | Snabel V.,Slovak Academy of Sciences | Pacella F.,University of Rome La Sapienza | Perrone V.,Az. USL Rome B | D'Amelio S.,University of Rome La Sapienza
PLoS Neglected Tropical Diseases | Year: 2013

Background: The taxonomic distinctiveness of Ascaris lumbricoides and A. suum, two of the world's most significant nematodes, still represents a much-debated scientific issue. Previous studies have described two different scenarios in transmission patterns, explained by two hypotheses: (1) separated host-specific transmission cycles in highly endemic regions, (2) a single pool of infection shared by humans and pigs in non-endemic regions. Recently, A. suum has been suggested as an important cause of human ascariasis in endemic areas such as China, where cross-infections and hybridization have also been reported. The main aims of the present study were to investigate the molecular epidemiology of human and pig Ascaris from non-endemic regions and, with reference to existing data, to infer the phylogenetic and phylogeographic relationships among the samples. Methodology: 151 Ascaris worms from pigs and humans were characterized using PCR-RFLP on nuclear ITS rDNA. Representative geographical sub-samples were also analysed by sequencing a portion of the mitochondrial cox1 gene, to infer the extent of variability at population level. Sequence data were compared to GenBank sequences from endemic and non-endemic regions. Principal Findings: No fixed differences between human and pig Ascaris were evident, with the exception of the Slovak population, which displays significant genetic differentiation. The RFLP analysis confirmed pig as a source of human infection in non-endemic regions and as a corridor for the promulgation of hybrid genotypes. Epidemiology and host-affiliation seem not to be relevant in shaping molecular variance. Phylogenetic and phylogeographical analyses described a complex scenario, involving multiple hosts, sporadic contact between forms and an ancestral taxon referable to A. suum. Conclusions/Significance: These results suggest the existence of homogenizing gene flow between the two taxa, which appear to be variants of a single polytypic species. This conclusion has implications on the systematics, transmission and control programs relating to ascariasis. © 2013 Cavallero et al.


Vaclav R.,Slovak Academy of Sciences | Valera F.,CSIC - Estación Experimental De Zonas Áridas | Martinez T.,CSIC - Estación Experimental De Zonas Áridas
Oecologia | Year: 2011

Recent work increasingly reveals the importance of social information in individual dispersal decisions, population dynamics and conservation. Much of the knowledge gained to date comes from studies on short-lived and/or densely breeding species. In contrast, our understanding of the processes involved in nest-site selection for long-lived, solitary breeding species is insufficient. We increased nest-site availability by nest-box supplementation over a 5-year period in a population of a long-lived, solitary, secondary-cavity nesting bird, the European roller Coracias garrulus, breeding in natural cavities and human constructions. We tested the nest limitation and the inadvertent conspecific social information hypothesis in order to study the dynamics and mechanisms of abandonment of previously used nests and the colonisation of new ones. Our data lend support to the nest-limitation hypothesis both in terms of quantity-population and the size of breeding clusters increased, and suitability-the majority of pairs used and re-occupied nest-boxes. Nevertheless, the use of natural cavities did not decrease after 5 years. At the between-patch scale, rollers were revealed to colonise nest-boxes based on conspecific social attraction, namely distance to the nearest neighbour in the same season. Despite the unpredictability of patch productivity, at the within-patch scale, the selection of previously unoccupied cavities was consistent with the performance-based conspecific attraction hypothesis. Philopatry could account for the repeated use of cavities, because nests that were used for two successive years were more likely to also be reused in the subsequent season. © 2010 Springer-Verlag.


Gomory F.,Slovak Academy of Sciences | Inanir F.,Recep Tayyip Erdoğan University
IEEE Transactions on Applied Superconductivity | Year: 2012

Numerical simulations have been performed in order to predict the behavior of a round wire covered by thin superconducting layer when exposed to AC magnetic field or transporting AC current, as well as for a solenoid coil made from such wire. It was found that the AC loss of a single coated round wire is in good agreement with the predictions based on the existing analytical results for a hollow superconducting cylinder. AC loss in the coil shows two regimes. At low currents it is lower than in the case of the coil made from a full round wire with the same critical current and outer radius. In the range of currents comparable to the critical current the loss superseded the values expected for the reference coil from full wire. These results indicate, that the use of coated round wires instead of full ones does not offer a significant advantage from the point of view of AC loss in a coil winding. © 2011 IEEE.


Pincak R.,Slovak Academy of Sciences | Pincak R.,Joint Institute for Nuclear Research
Physica A: Statistical Mechanics and its Applications | Year: 2013

In this paper we apply a new approach of string theory to the real financial market. The models are constructed with an idea of prediction models based on the string invariants (PMBSI). The performance of PMBSI is compared to support vector machines (SVM) and artificial neural networks (ANN) on an artificial and a financial time series. A brief overview of the results and analysis is given. The first model is based on the correlation function as invariant and the second one is an application based on the deviations from the closed string/pattern form (PMBCS). We found the difference between these two approaches. The first model cannot predict the behavior of the forex market with good efficiency in comparison with the second one which is, in addition, able to make relevant profit per year. The presented string models could be useful for portfolio creation and financial risk management in the banking sector as well as for a nonlinear statistical approach to data optimization. © 2013 Elsevier B.V. All rights reserved.


Vinogradov E.,National Research Council Canada | Frimmelova M.,Slovak Academy of Sciences | Toman R.,Slovak Academy of Sciences
Carbohydrate Research | Year: 2013

Elucidation of the carbohydrate backbone structure of the lipopolysaccharide (LPS) from Piscirickettsia salmonis, the etiological agent of the salmonid rickettsial septicemia, is described. Structural information was established by a combination of monosaccharide and methylation analyses of LPS, and by NMR and mass spectrometries of oligosaccharides obtained through the use of various chemical degradations of the native polymer. The following structure of the backbone sugars was determined on the basis of the combined data from these experiments: (Equation presented) The presence of two consecutive residues of diacetylated pseudaminic acid (Pse5,7Ac, 5,7-diacetamido-3,5,7,9-tetradeoxy- L-glycero-L-manno-non-2-ulosonic acid) in the LPS appears to be unique among polysaccharides containing this acidic sugar. Similarly, the presence of 4-aminoarabinose (Ara4N, 4-amino-4-deoxy-L-arabinopyranose) on O-4 of the α-GlcN1P of the lipid A moiety is a unique feature of this LPS. © 2013 Elsevier Ltd.


Calero-Torralbo M.A.,CSIC - Estación Experimental De Zonas Áridas | Vaclav R.,Slovak Academy of Sciences | Valera F.,CSIC - Estación Experimental De Zonas Áridas
Oikos | Year: 2013

The role of environmental and host-associated factors in synchronization of host-parasite life-cycles is an important question of evolutionary ecology. Yet, only handsome of studies examined this question at the intraspecific level. Here we explore how host-associated traits, such as breeding phenology and host breeding habitat, can influence parasite phenology and co-occurrence at different spatial scales. We studied the system comprised of a generalist ectoparasitic fly Carnus hemapterus and one of its avian hosts, the European roller Coracias garrulus. Inter-annual variation in phenology was larger for parasites than hosts. Host predictability in terms of occurrence and phenological regularity was moderate, suggesting that this resource can be difficult to be tracked by the parasite. A large proportion of flies consistently emerged before the appearance of suitable host resources at both the nest and population level. Consequently, we revealed low and highly variable inter-annual host-parasite synchronization rates. Nevertheless, we found that parasites from nests of early and progressively earlier breeding European rollers were more synchronized with their hosts than parasites from nests of late and progressively later breeding hosts, respectively. Temporal trends in host suitability and parasite emergence at the population scale suggest that other mechanisms, such as dispersal or exploitation of other host species, ensure parasites access to resources and counteract asynchrony with the host at the nest scale. © 2013 The Authors. Oikos © 2013 Nordic Society Oikos.


Lorenc M.,Slovak Central Observatory | Rybansky M.,Slovak Academy of Sciences | Dorotovic I.,Slovak Central Observatory
Solar Physics | Year: 2012

We have studied the rotation of the solar corona using the images taken at a 9. 4 nm wavelength by the AIA 094 instrument on board the Solar Dynamics Observatory (SDO) satellite. Our analysis implies that the solar corona rotates differentially. It appears that ω, the angular rotation velocity of the solar corona, does not only depend on heliographic latitude but is also a function of time, while the nature of the latter dependence remains unclear. Besides measurement errors, deviations Δω from the mean rotational speed are also caused by proper motion of the observed point source (the tracer) with respect to its surroundings. The spread in ω values at a particular heliographic latitude is a real effect, not caused by measurement errors. Most of the observations carry relative error less than 1 % in ω. © 2012 Springer Science+Business Media B.V.


Grant
Agency: European Commission | Branch: FP7 | Program: MC-ITN | Phase: FP7-PEOPLE-2012-ITN | Award Amount: 3.47M | Year: 2013

A network combining 9 academic research groups and 4 collaborating industrial companies is proposed to train the next generation of PhD students and post-doctoral researchers, in developing and applying novel experimental and theoretical methods in the NMR spectroscopy of systems containing paramagnetic metals. The assembled team, with researchers distributed throughout the EU, will investigate a variety of important problems in chemistry and biology including catalysts, battery materials, metalloproteins and large protein-protein assemblies. The researchers will be trained to attack key problems that prevent the widespread usage of NMR spectroscopy as applied to paramagnetic materials, and to develop new methods to improve significantly the structural and electronic information that can be obtained from these systems. Three experimental and theoretical work programs are proposed, which build on, but also move significantly beyond the recent advances in pNMR, many of which have originated from members of this network: i) developing experimental approaches for obtaining NMR spectra from challenging paramagnetic molecules and materials, ii) extending the fundamental theoretical understanding of pNMR parameters, and facilitating their quantum-chemical implementations in first-principles software; iii) attacking relevant chemical and biological problems, with novel techniques to determine structure (e.g., of insoluble proteins and disordered battery electrode materials), dynamics and reactivity around metal centres, and exploring interactions between, e.g., biomolecules, catalytic centres and supports. Integral to the research-based training programme is the series of workshops, practical training courses, international conferences, and outreach actions, located at the different sites. These will i) train the young researchers of the network in the basics of pNMR and ii) disseminate the results of the network to the larger NMR community and to the general public.


Raith M.,University of Regensburg | Stano P.,University of Arizona | Stano P.,Slovak Academy of Sciences | Fabian J.,University of Regensburg
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

We investigate the spin relaxation induced by acoustic phonons in the presence of spin-orbit interactions in single electron Si/SiGe lateral coupled quantum dots. The relaxation rates are computed numerically in single and double quantum dots, in in-plane and perpendicular magnetic fields. The deformation potential of acoustic phonons is taken into account for both transverse and longitudinal polarizations, and their contributions to the total relaxation rate are discussed with respect to the dilatation and shear potential constants. We find that in single dots the spin relaxation rate scales approximately with the seventh power of the magnetic field, in line with a recent experiment. In double dots the relaxation rate is much more sensitive to the dot spectrum structure, as it is often dominated by a spin hot spot. The anisotropy of the spin-orbit interactions gives rise to easy passages, special directions of the magnetic field for which the relaxation is strongly suppressed. Quantitatively, the spin relaxation rates in Si are typically two orders of magnitude smaller than in GaAs due to the absence of the piezoelectric phonon potential and generally weaker spin-orbit interactions. © 2011 American Physical Society.


Surovtsev Yu.S.,Joint Institute for Nuclear Research | Bydzovsky P.,Nuclear Physics Institute of Czech Republic | Kaminski R.,Polish Academy of Sciences | Nagy M.,Slovak Academy of Sciences
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2010

The status and parameters of the scalar, vector, and tensor mesonic resonances are obtained in the multichannel analysis of processes ππ→ππ, KK̄, ηη, and ηη′ and compared with other results. For example, we obtained the f0(600) meson with mass 774±15MeV and width 988±36MeV (the pole position on sheet II is 596-i494MeV) and the first ρ-like meson with mass 1275±32MeV and total width 304±24MeV, which differ significantly from the mean value 1459±11MeV cited in the Particle Data Group tables. Spectroscopic implications from results of these analyses and possible classification of the resonance states in terms of the SU(3) multiplets are also discussed. © 2010 The American Physical Society.


Foulis D.J.,University of Massachusetts Amherst | Pulmannova S.,Slovak Academy of Sciences
Reports on Mathematical Physics | Year: 2011

Elements of the exocenter of a generalized effect algebra (GEA) correspond to decompositions of the GEA as a direct sum and thus the exocenter is a generalization to GEAs of the center of an effect algebra. The exocenter of a GEA is shown to be a boolean algebra, and the notion of a hull mapping for an effect algebra is generalized to a hull system for a GEA. We study Dedekind orthocompleteness of GEAs and extend to GEAs the notion of a centrally orthocomplete effect algebra. © 2011 Polish Scientific Publishers.


Zamocky M.,University of Natural Resources and Life Sciences, Vienna | Zamocky M.,Slovak Academy of Sciences | Furtmuller P.G.,University of Natural Resources and Life Sciences, Vienna | Obinger C.,University of Natural Resources and Life Sciences, Vienna
Archives of Biochemistry and Biophysics | Year: 2010

The phylogenetics of Class I of the heme peroxidase-catalase superfamily currently representing over 940 known sequences in all available genomes of prokaryotes and eukaryotes has been analysed. The robust reconstructed tree for 193 Class I peroxidases with 6 selected Class II representatives reveals all main trends of molecular evolution. It suggests how the ancestral peroxidase gene might have been transferred from prokaryotic into eukaryotic genomes. Besides well known families of catalase-peroxidases, cytochrome c peroxidases and ascorbate peroxidases, the phylogenetic analysis shows for the first time the presence of two new well separated clades of hybrid-type peroxidases that might represent evolutionary bridges between catalase-peroxidases and cytochrome c peroxidases (type A) as well as between ascorbate peroxidases and Class II peroxidases (type B). Established structure-function relationships are summarized. Presented data give useful hints on the origin and evolution of catalytic promiscuity and specificity and will be a valuable basis for future functional analysis of Class I enzymes as well as for de novo design. © 2010 Elsevier Inc.


Kona J.,Slovak Academy of Sciences | Fabian W.M.F.,University of Graz
Journal of Chemical Theory and Computation | Year: 2011

The first reaction step of the redox cycle of bovine erythrocyte glutathione peroxidase from class 1 (GPX1) was investigated using hybrid quantum mechanics/molecular mechanics (QM/MM) calculations using the ONIOM methodology. The reduction of hydrogen peroxide by the active-site selenocysteine in selenolate form assisted by the Arg177 residue was modeled based on a proposal from previous molecular dynamics simulations and pK a calculations (J. Chem. TheoryComput. 2010, 6, 1670-1681). The redox reaction is predicted as a concerted S N2 nucleophilic substitution with a concomitant proton transfer from Arg177 onto leaving hydroxide ion upon reduction of hydrogen peroxide. The height of the reaction barrier was predicted in range of 6-11 kcal mol -1, consistent with an experimental rate constant of ca. 10 7 M -1 s -1. The proposed GPX1-Se --Arg177H + mechanism for GPX1 is compared with the GPX3-SeH-Gln83 one proposed for human glutathione peroxidase from class 3 (GPX3) and with the solvent-assisted proton exchange mechanism proposed for GPX-like organic selenols. The structural and energetic parameters predicted by various density functional theory methods (B3LYP, MPW1PW91, MPW1K, BB1K, M05-2X, M06-2X, and M06) are also discussed. © 2011 American Chemical Society.


Roessl U.,University of Graz | Nahalka J.,Slovak Academy of Sciences | Nidetzky B.,University of Graz
Biotechnology Letters | Year: 2010

Methods for the preparation of carrier-free insoluble enzymes are reviewed. The technology of cross-linked enzyme aggregates has now been applied to a range of synthetically useful activities. Fusion proteins are also gaining momentum because they allow a relatively selective aggregation or even a specific self-assembly of the desired enzyme activity into insoluble particles in the absence of potentially denaturing chemicals required for precipitation and cross-linking. Recycling of insoluble protein particles for multiple rounds of batchwise reaction has been demonstrated in selected biotransformations. However, for application in a fully continuous biocatalytic process, low resistance to mechanical stress and high compressibility are issues for consideration on carrier-free enzyme particles. © Springer Science+Business Media B.V. 2009.


Ligon S.C.,Vienna University of Technology | Husar B.,Vienna University of Technology | Husar B.,Slovak Academy of Sciences | Wutzel H.,Vienna University of Technology | And 2 more authors.
Chemical Reviews | Year: 2014

Photoinduced polymerization will continue to find broad application in industry due to the reductions in energy, solvent, and process time that it can offer. Oxygen inhibition can be completely avoided by performing polymerization in the total absence of oxygen, but this solution is practical only in very limited applications. Chemical additives are likely to continue to play a major role in reducing oxygen inhibition, with increasing emphasis on the shelf life stability of the formulation. Effective strategies should try either to avoid the formation of peroxyl radicals or to reinitiate the polymerization from them. Alternative photocuring monomers, photocationic systems, and hybrid technology are of great interest, but these will become industrially useful only where products are able to provide the desired application qualities and service life properties at a commercially viable price.


Harra L.K.,UCL Mullard Space Science Laboratory | Sterling A.C.,NASA | Sterling A.C.,Japan Aerospace Exploration Agency | Gomory P.,Slovak Academy of Sciences | Veronig A.,University of Graz
Astrophysical Journal Letters | Year: 2011

We observed a coronal wave (EIT wave) on 2011 February 16, using EUV imaging data from the Solar Dynamics Observatory/Atmospheric Imaging Assembly (AIA) and EUV spectral data from the Hinode/EUV Imaging Spectrometer (EIS). The wave accompanied an M1.6 flare that produced a surge and a coronal mass ejection (CME). EIS data of the wave show a prominent redshifted signature indicating line-of-sight velocities of 20kms-1 or greater. Following the main redshifted wave front, there is a low-velocity period (and perhaps slightly blueshifted), followed by a second redshift somewhat weaker than the first; this progression may be due to oscillations of the EUV atmosphere set in motion by the initial wave front, although alternative explanations may be possible. Along the direction of the EIS slit the wave front's velocity was 500kms -1, consistent with its apparent propagation velocity projected against the solar disk as measured in the AIA images, and the second redshifted feature had propagation velocities between 200 and 500kms-1. These findings are consistent with the observed wave being generated by the outgoing CME, as in the scenario for the classic Moreton wave. This type of detailed spectral study of coronal waves has hitherto been a challenge, but is now possible due to the availability of concurrent AIA and EIS data. © 2011. The American Astronomical Society. All rights reserved..


Kuzmik J.,Slovak Academy of Sciences | Kuzmik J.,Vienna University of Technology
ASDAM 2012 - Conference Proceedings: The 9th International Conference on Advanced Semiconductor Devices and Microsystems | Year: 2012

Motivation for replacing the AlGaN barrier layer of the conventional AlGaN/GaN HEMTs with lattice-matched InAlN is explained. State-of-the-art InAlN/GaN HEMTs are reviewed; emphasize is given to the analysis of the normally-off InAlN/GaN HEMTs using either a gate recessing or a concept of polarization engineering. Reliability issues of InAlN/GaN HEMTs are studied for different stress conditions and results discussed in respect to AlGaN/GaN HEMTs. Concept of InAlN/GaN/AlGaN double-heterostructure QW HEMT is shown to be more effective in blocking the hot electron injection in to the buffer. Novel InN-channel based devices are suggested with a relaxed InAlN buffer. The InN/InAlN-based HEMTs should be the choice for reaching a THz frequency range. © 2012 IEEE.


Strecka J.,University of P.J. Šafarik | Cencarikova H.,Slovak Academy of Sciences | Lyra M.L.,Federal University of Alagoas
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2015

Phase diagrams and thermodynamic properties of a correlated spin-electron system considering localized Ising spins on nodal sites and mobile electrons on decorating sites of doubly decorated planar lattices are rigorously examined with the help of generalized decoration-iteration transformation. The investigated model defined on loose-packed (honeycomb and square) lattices exhibits the phase diagram including a spontaneous ferromagnetic and antiferromagnetic order in a vicinity of quarter and half-filling, respectively, while the same model on close-packed (triangular and kagome) lattices only shows a spontaneous ferromagnetic order due to a kinetically-driven spin frustration at high electron concentrations. The lower critical concentration, at which the ferromagnetic order appears, is remarkably close to a bond percolation threshold in spite of the annealed character of the developed procedure. The specific heat exhibits at the critical temperature either a logarithmic divergence for integer-valued electron concentrations or it shows a finite-cusp for any non-integer electron concentration due to the annealed bond disorder. © 2015 Elsevier B.V.


Prokop P.,Slovak Academy of Sciences | Fancovicova J.,University of Trnava
Acta Ethologica | Year: 2010

Evolutionary explanations of disgust propensity propose that disgust is an adaptation which helps us to decrease the likelihood of being infected by pathogens. To test this hypothesis, we examined human fear, disgust and self-perceived danger as a response on colourful pictures of disease-relevant and disease-irrelevant invertebrates. Furthermore, we also examined a possible link between these variables and human anti-parasite behaviour. We found that participants clearly distinguished between disease-relevant and disease-irrelevant group of animals, and that females always scored higher than males. Moreover, there were associations between ratings of fear, disgust and danger and human anti-parasite behaviour. Our results support the hypothesis that human emotions and behaviours are shaped by natural selection. © 2010 Springer-Verlag and ISPA.


Foulis D.J.,University of Massachusetts Amherst | Pulmannova S.,Slovak Academy of Sciences
Foundations of Physics | Year: 2013

A synaptic algebra is a generalization of the self-adjoint part of a von Neumann algebra. In this article we extend to synaptic algebras the type-I/II/III decomposition of von Neumann algebras, AW*-algebras, and JW-algebras. © 2013 Springer Science+Business Media New York.


Trnka A.,University of Trnava | Prokop P.,University of Trnava | Prokop P.,Slovak Academy of Sciences | Grim T.,Palacky University
PLoS ONE | Year: 2012

Background: Co-evolutionary struggles between dangerous enemies (e.g., brood parasites) and their victims (hosts) lead to the emergence of sophisticated adaptations and counter-adaptations. Salient host tricks to reduce parasitism costs include, as front line defence, adult enemy discrimination. In contrast to the well studied egg stage, investigations addressing the specific cues for adult enemy recognition are rare. Previous studies have suggested barred underparts and yellow eyes may provide cues for the recognition of cuckoos Cuculus canorus by their hosts; however, no study to date has examined the role of the two cues simultaneously under a consistent experimental paradigm. Methodology/Principal Findings: We modify and extend previous work using a novel experimental approach - custom-made dummies with various combinations of hypothesized recognition cues. The salient recognition cue turned out to be the yellow eye. Barred underparts, the only trait examined previously, had a statistically significant but small effect on host aggression highlighting the importance of effect size vs. statistical significance. Conclusion: Relative importance of eye vs. underpart phenotypes may reflect ecological context of host-parasite interaction: yellow eyes are conspicuous from the typical direction of host arrival (from above), whereas barred underparts are poorly visible (being visually blocked by the upper part of the cuckoo's body). This visual constraint may reduce usefulness of barred underparts as a reliable recognition cue under a typical situation near host nests. We propose a novel hypothesis that recognition cues for enemy detection can vary in a context-dependent manner (e.g., depending on whether the enemy is approached from below or from above). Further we suggest a particular cue can trigger fear reactions (escape) in some hosts/populations whereas the same cue can trigger aggression (attack) in other hosts/populations depending on presence/absence of dangerous enemies that are phenotypically similar to brood parasites and costs and benefits associated with particular host responses. © 2012 Trnka et al.


Lapin J.,Slovak Academy of Sciences | Frkanova K.,University of Trnava
Kovove Materialy | Year: 2011

The effect of two processing routes on chemical composition, microstructure and mechanical properties of plasma melted intermetallic ingots with nominal composition Ti-46Al-8Ta (at.%) was studied. The semi-products for plasma melting were prepared by: (i) cold single action compaction of initial pure materials and (ii) induction melting of binary master alloy with nominal composition Al-14Ta (at.%), its casting in a copper mould and mixing with Ti sponge. The applied processing routes and selected parameters of plasma melting result in a full dissolution of initial materials and homogeneous distribution of alloying elements in the plasma melted Ti-Al-Ta ingots. The ingots prepared from the cold compacted materials show high burnout of Al up to 3.7 at.% and contamination by O up to 1.31 at.%. Content of Al is well adjusted in the plasma melted ingots prepared from the master alloy mixed with Ti sponge and content of O is reduced to 0.69 at.%. The morphology of dendrites within columnar and equiaxed grains indicates solidification via β (Ti-based solid solution with cubic crystal structure) primary solidification phase. The microstructure of the grains is lamellar and consists of α2(Ti3Al) and γ(TiAl) phases. Vickers hardness and compression yield strength of the plasma melted ingots is higher than those measured in a benchmark Ti-46Al-8Ta (at.%) alloy with convoluted γ + α2 type of microstructure. The compression strength of the ingot prepared from the cold compacted semi-products is by 20 % higher than that of the ingot prepared from the master Al-Ta alloy mixed with the Ti sponge.


Krajci P.,Slovak Academy of Sciences | Holko L.,Slovak Academy of Sciences | Perdigao R.A.P.,Vienna University of Technology | Parajka J.,Vienna University of Technology
Journal of Hydrology | Year: 2014

We present a method for estimation of regional snowline elevation (RSLE) from satellite data for seasonally snow covered mountain basins. The methodology is based on finding an elevation for which the sum of snow covered pixels below and land pixels above the RSLE is minimized for each day. The methodology is tested with MODIS daily snow cover product in the period 2000-2013 in the upper Váh basin (Slovakia). The accuracy is evaluated by daily snow depth measurements at seven climate stations and additional snow course measurements at 16 profiles in the period 2000-2013. The results show that RSLE allows accurate estimation of snowline elevation. For the RSLE estimation, two thresholds need to be considered. The thresholds of maximum cloud coverage and minimum number of snow pixels considerably affect the number of days (images) available for estimation. The sensitivity evaluation indicates that the cloud threshold has less effect on the accuracy than the minimum snow threshold. Setting cloud and minimum snow thresholds to 70% and 5% respectively, results in an average RSLE estimation accuracy of 86% at climate stations. The accuracy in the forest is 92% in the winter months and drops to 70% in April. The main factors that control the accuracy and scatter around the snowline are vegetation cover and shading of terrain. The results show that spatial patterns of misclassification correspond well with forest cover and potential insolation duration in winter. The developed RSLE method is more accurate than the previously used methods of snowline elevation estimation, it decreases the scatter around the snowline and can be potentially applied in an improved cloud reduction in MODIS products as well. © 2014 Elsevier B.V.


Zamocky M.,University of Natural Resources and Life Sciences, Vienna | Zamocky M.,Slovak Academy of Sciences | Gasselhuber B.,University of Natural Resources and Life Sciences, Vienna | Furtmuller P.G.,University of Natural Resources and Life Sciences, Vienna | Obinger C.,University of Natural Resources and Life Sciences, Vienna
Cellular and Molecular Life Sciences | Year: 2014

Heme peroxidases and catalases are key enzymes of hydrogen peroxide metabolism and signaling. Here, the reconstruction of the molecular evolution of the peroxidase-catalase superfamily (annotated in pfam as PF00141) based on experimentally verified as well as numerous newly available genomic sequences is presented. The robust phylogenetic tree of this large enzyme superfamily was obtained from 490 full-length protein sequences. Besides already well-known families of heme b peroxidases arranged in three main structural classes, completely new (hybrid type) peroxidase families are described being located at the border of these classes as well as forming (so far missing) links between them. Hybrid-type A peroxidases represent a minor eukaryotic subfamily from Excavates, Stramenopiles and Rhizaria sharing enzymatic and structural features of ascorbate and cytochrome c peroxidases. Hybrid-type B peroxidases are shown to be spread exclusively among various fungi and evolved in parallel with peroxidases in land plants. In some ascomycetous hybrid-type B peroxidases, the peroxidase domain is fused to a carbohydrate binding (WSC) domain. Both here described hybrid-type peroxidase families represent important turning points in the complex evolution of the whole peroxidase-catalase superfamily. We present and discuss their phylogeny, sequence signatures and putative biological function. © 2014 The Author(s).


Trnka A.,University of Trnava | Prokop P.,University of Trnava | Prokop P.,Slovak Academy of Sciences
Animal Behaviour | Year: 2012

The close resemblance between the common cuckoo, Cuculus canorus, and the Eurasian sparrowhawk, Accipiter nisus, is often viewed as Batesian mimicry evolved by the cuckoo in response to the aggression of its host. However, the effectiveness of such mimicry is poorly known. We examined cuckoo-hawk discrimination ability in the great reed warbler, Acrocephalus arundinaceus, a well-known and aggressive cuckoo host. We measured the responses of birds to three combinations of simultaneously presented taxidermic mounts of the cuckoo, sparrowhawk and turtle dove, as a harmless control, placed near their nests. Great reed warblers clearly discriminated the two enemies from the innocuous species. They always attacked cuckoos and sparrowhawks more often than turtle doves suggesting they considered both a danger to their broods. However, when we confronted the tested birds with the simultaneously presented mounts of these species, the parents attacked the cuckoo more frequently than the sparrowhawk. The results revealed that although great reed warblers attacked both cuckoo and sparrowhawk mounts near their nest, they were able to discriminate between them. This may suggest that if cuckoos had evolved the visual mimicry of a sparrowhawk to avoid host attacks, this mimicry may be unsuccessful not only because it is imperfect and hosts can learn to discriminate but also because of the generalized nest defence of more aggressive hosts. © 2011 The Association for the Study of Animal Behaviour.


Prokop P.,University of Trnava | Prokop P.,Slovak Academy of Sciences | Tunnicliffe S.D.,University of London
Anthrozoos | Year: 2010

Having pets at home provides various social, health, and educational benefits to children. The question of how keeping pets at home affects the attitudes of children toward wild animals still has not been answered, due to various methodological issues, such as ignorance of some attitude dimensions and/or questionnaires that include items focused on very different animals. We conducted three independent research surveys (using three independent samples) of Slovakian primary school children aged 10 to 15 years (n = 1297). These surveys focused on the effects of keeping pets on the attitudes of children towards, and knowledge of, three unpopular animals in Slovakia. These animals were pests (potato beetle) (Study 1), predators (wolf) (Study 2), and those that pose a threat of disease to hu-mans (mouse) (Study 3). Each survey also included a popular animal (ladybird beetle, rabbit, and squirrel, respectively), which served as a "control"; these were compared by pair-wise statistics. Results consistently showed that children had better knowledge of, but less favorable attitudes towards, unpopular animals compared with popularnes. Having pets at home was associated with more positive attitudes to, and better knowledge of, both popular and unpopular animals. Girls were less favorably inclined than boys to animals that may pose a threat, danger, or disease to them. Implications for humane education are discussed, especially in terms of keeping pets, the link between knowledge and attitudes, and children's understanding of ecological adaptations. © ISAZ 2010.


Janecek S.,Slovak Academy of Sciences | Janecek S.,University of Trnava | Kuchtova A.,Slovak Academy of Sciences | Kuchtova A.,University of Trnava
FEBS Letters | Year: 2012

The glycoside hydrolase family 119 (GH119) contains the α-amylase from Bacillus circulans and five other hypothetical proteins. Until now, nothing has been reported on the catalytic residues and catalytic-domain fold of GH119. Based on a detailed in silico analysis involving sequence comparison in combination with BLAST searches and structural modelling, an unambiguous relationship was revealed between the families GH119 and GH57. This includes sharing the catalytic residues, i.e. Glu231 and Asp373 as catalytic nucleophile and proton donor, respectively, in the predicted catalytic (β/α) 7-barrel domain of GH119 B. circulans α-amylase. The GH57 and GH119 families may thus define a new CAZy clan. © 2012 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.


Klinovaja J.,University of Basel | Klinovaja J.,Harvard University | Stano P.,University of Basel | Stano P.,Slovak Academy of Sciences | And 2 more authors.
Physical Review Letters | Year: 2013

We consider quasi-one-dimensional Ruderman-Kittel-Kasuya-Yosida (RKKY) systems in proximity to an s-wave superconductor. We show that a 2kF peak in the spin susceptibility of the superconductor in the one-dimensional limit supports helical order of localized magnetic moments via RKKY interaction, where kF is the Fermi wave vector. The magnetic helix is equivalent to a uniform magnetic field and very strong spin-orbit interaction (SOI) with an effective SOI length 1/2kF. We find the conditions to establish such a magnetic state in atomic chains and semiconducting nanowires with magnetic atoms or nuclear spins. Generically, these systems are in a topological phase with Majorana fermions. The inherent self-tuning of the helix to 2kF eliminates the need to tune the chemical potential. © 2013 American Physical Society.


Kopeliovich B.Z.,Federico Santa María Technical University | Nemchik J.,Czech Technical University | Nemchik J.,Slovak Academy of Sciences | Potashnikova I.K.,Federico Santa María Technical University | Schmidt I.,Federico Santa María Technical University
Physical Review C - Nuclear Physics | Year: 2012

High-p T hadrons produced in hard collisions and detected inclusively bear peculiar features: (i) they originate from jets whose initial virtuality and energy are of the same order and (ii) such jets are rare and have a very biased energy sharing among the particles, namely the detected hadron carries the main fraction of the jet energy. The former feature leads to an extremely intensive gluon radiation and energy dissipation at the early stage of hadronization, either in vacuum or in a medium. As a result, a leading hadron must be produced on a short length scale. Evaluation within a model of perturbative fragmentation confirms the shortness of the production length. This result is at variance with the unjustified assumption of long production length, made within the popular energy-loss scenario. Thus, we conclude that the main reason of suppression of high-p T hadrons in heavy-ion collisions is the controlled-by-color-transparency attenuation of a high-p T dipole propagating through the hot medium. Adjusting a single parameter, the transport coefficient, we describe quite well the data from the Large Hadron Collider and the Relativistic Heavy Ion Collider for the suppression factor R AA as function of p T, collision energy, and centrality. We observe that the complementary effect of the initial-state interaction causes a flattening and even fall of R AA at large p T. The azimuthal anisotropy of hadron production, calculated with no further adjustment, also agrees well with data at different energies and centralities. © 2012 American Physical Society.


Parajka J.,Vienna University of Technology | Holko L.,Slovak Academy of Sciences | Kostka Z.,Slovak Academy of Sciences | Bloschl G.,Vienna University of Technology
Hydrology and Earth System Sciences | Year: 2012

Numerous global and regional validation studies have examined MODIS snow mapping accuracy by using measurements at climate stations, which are mainly at open sites. MODIS accuracy in alpine and forested regions is, however, still not well understood. The main objective of this study is to evaluate MODIS (MOD10A1 and MYD10A1) snow cover products in a small experimental catchment by using extensive snow course measurements at open and forest sites. The MODIS accuracy is tested in the Jalovecky creek catchment (northern Slovakia) in the period 2000-2011. The results show that the combined Terra and Aqua images enable snow mapping at an overall accuracy of 91.5%. The accuracies at forested, open and mixed land uses at the Aervenec sites are 92.7%, 98.3% and 81.8%, respectively. The use of a 2-day temporal filter enables a significant reduction in the number of days with cloud coverage and an increase in overall snow mapping accuracy. In total, the 2-day temporal filter decreases the number of cloudy days from 61% to 26% and increases the snow mapping accuracy to 94%. The results indicate three possible factors leading to misclassification of snow as land: patchy snow cover, limited MODIS geolocation accuracy and mapping algorithm errors. Out of a total of 27 misclassification cases, patchy snow cover, geolocation issues and mapping errors occur in 12, 12 and 3 cases, respectively. © 2012 Author(s). CC Attribution 3.0 License.


Boca M.,Slovak Academy of Sciences | Boca M.,Vienna University of Technology | Jameson R.F.,University of Dundee | Linert W.,Vienna University of Technology
Coordination Chemistry Reviews | Year: 2011

A review of papers up to 2008 dealing with all branches of chemistry of the compounds containing 2,2'-pyridine-2,6-diylbis(1H-benzimidazole) and 2,2'-pyridine-2,6-diylbis(1,3-benzothiazole) is presented. The review summarizes the preparation procedures and properties of free organic compounds, as well as their different protonated and/or deprotonated forms. A summary of complex compounds of the considered ligands is presented together with the review of the most important properties such as spectroscopic properties, structures, magnetic properties or biological and electrochemical activity. From this review the blind spots can be identified which might suggest more points of potential interest. Also missing is a promising investigation of, at present unknown, analogues. © 2010 Elsevier B.V.


Lapin J.,Slovak Academy of Sciences | Pelachova T.,Slovak Academy of Sciences | Domankova M.,University of Trnava
Intermetallics | Year: 2011

Creep behaviour of a new cast air-hardenable intermetallic Ti-46Al-8Ta (at.%) alloy was investigated. Constant load tensile creep tests were performed at initial applied stresses ranging from 200 to 400 MPa in the temperature range from 973 to 1073 K. The minimum creep rate is found to depend strongly on the applied stress and temperature. The power law stress exponent of the minimum creep rate is n = 5.8 and the apparent activation energy for creep is calculated to be Qa = (382.9 ± 14.5) kJ/mol. The kinetics of creep deformation of the specimens tested to a minimum creep rate (creep deformation about 2%) is suggested to be controlled by non-conservative motion of dislocations in the γ(TiAl) matrix. Besides dislocation mechanisms, deformation twinning contributes significantly to overall measured strains in the specimens tested to fracture. The initial γ(TiAl) + α2(Ti3Al) microstructure of the creep specimens is unstable and transforms to the γ + α2 + τ type during creep. The particles of the τ phase are preferentially formed along the grain and lamellar colony boundaries. © 2010 Elsevier Ltd. All rights reserved.


Husar B.,Vienna University of Technology | Husar B.,Slovak Academy of Sciences | Liska R.,Vienna University of Technology
Chemical Society Reviews | Year: 2012

Although acrylates and methacrylates are the state-of-the-art monomers for protective and decorative coatings, skin and inhalation irritancy and potential cytotoxicity of monomers present serious health hazards. Monomers like vinyl carbonates or vinyl carbamates can overcome these problems with their generally lower cytotoxicity and yet similar photoreactivity to (meth)acrylates. The reviewed classes of monomers have not attracted industry's attention until now due to expensive synthetic methods though recently developed affordable routes offer prospect for their increasing use. © The Royal Society of Chemistry 2012.


Zamocky M.,University of Natural Resources and Life Sciences, Vienna | Zamocky M.,Slovak Academy of Sciences | Gasselhuber B.,University of Natural Resources and Life Sciences, Vienna | Furtmuller P.G.,University of Natural Resources and Life Sciences, Vienna | Obinger C.,University of Natural Resources and Life Sciences, Vienna
Archives of Biochemistry and Biophysics | Year: 2012

For efficient removal of intra- and/or extracellular hydrogen peroxide by dismutation to harmless dioxygen and water (2H 2O 2 → O 2 + 2H 2O), nature designed three metalloenzyme families that differ in oligomeric organization, monomer architecture as well as active site geometry and catalytic residues. Here we report on the updated reconstruction of the molecular phylogeny of these three gene families. Ubiquitous typical (monofunctional) heme catalases are found in all domains of life showing a high structural conservation. Their evolution was directed from large subunit towards small subunit proteins and further to fused proteins where the catalase fold was retained but lost its original functionality. Bifunctional catalase-peroxidases were at the origin of one of the two main heme peroxidase superfamilies (i.e. peroxidase-catalase superfamily) and constitute a protein family predominantly present among eubacteria and archaea, but two evolutionary branches are also found in the eukaryotic world. Non-heme manganese catalases are a relatively small protein family with very old roots only present among bacteria and archaea. Phylogenetic analyses of the three protein families reveal features typical (i) for the evolution of whole genomes as well as (ii) for specific evolutionary events including horizontal gene transfer, paralog formation and gene fusion. As catalases have reached a striking diversity among prokaryotic and eukaryotic pathogens, understanding their phylogenetic and molecular relationship and function will contribute to drug design for prevention of diseases of humans, animals and plants. © 2012 Elsevier Inc. All rights reserved.


Cipak L.,University of Vienna | Cipak L.,Slovak Academy of Sciences | Hyppa R.W.,Fred Hutchinson Cancer Research Center | Smith G.R.,Fred Hutchinson Cancer Research Center | Gregan J.,University of Vienna
Cell Cycle | Year: 2012

To study meiosis, synchronous cultures are often indispensable, especially for physical analyses of DNA and proteins. A temperature-sensitive allele of the Pat1 protein kinase (pat1-114) has been widely used to induce synchronous meiosis in the fission yeast Schizosaccharomyces pombe, but pat1-114-induced meiosis differs from wild-type meiosis, and some of these abnormalities might be due to higher temperature needed to inactivate the Pat1 kinase. Here, we report an ATP analog-sensitive allele of Pat1 [Pat1(L95A), designated pat1-as2] that can be used to generate synchronous meiotic cultures at physiological temperature. In pat1-as2 meiosis, chromosomes segregate with higher fidelity and spore viability is higher than in pat1-114 meiosis, although recombination is lower by a factor of 2-3 in these mutants than in starvation-induced pat1+ meiosis. Addition of the mat-Pc gene improved chromosome segregation and spore viability to nearly the level of starvation-induced meiosis. We conclude that pat1-as2 mat-Pc cells offer synchronous meiosis with most tested properties similar to those of wild-type meiosis. © 2012 Landes Bioscience.


Spanova M.,University of Graz | Czabany T.,University of Graz | Zellnig G.N.,University of Graz | Leitner E.,University of Graz | And 2 more authors.
Journal of Biological Chemistry | Year: 2010

Squalene belongs to the group of isoprenoids and is a precursor for the synthesis of sterols, steroids, and ubiquinons. In the yeast Saccharomyces cerevisiae, the amount of squalene can be increased by variation of growth conditions or by genetic manipulation. In this report, we show that a hem1Δ mutant accumulated a large amount of squalene, which was stored almost exclusively in cytoplasmic lipid particles/droplets. Interestingly, a strain bearing a hem1Δ deletion in a dga1Δlro1Δare1Δ are2Δ quadruple mutant background (QMhem1Δ), which is devoid of the classical storage lipids, triacylglycerols and steryl esters, and lacks lipid particles, accumulated squalene at similar amounts as the hem1Δ mutant in a wild type background. In QMhem1Δ, however, increased amounts of squalene were found in cellular membranes, especially in microsomes. The fact thatQMhem1Δ did not form lipid particles indicated that accumulation of squalene solely was not sufficient to initiate proliferation of lipid particles. Most importantly, these results also demonstrated that (i) squalene was not lipotoxic under the conditions tested, and (ii) organelle membranes in yeast can accommodate relatively large quantities of this non-polar lipid without compromising cellular functions. In summary, localization of squalene as described here can be regarded as an unconventional example of non-polar lipid storage in cellular membranes. © 2010 by The American Society for Biochemistry and Molecular Biology, Inc.


Trnka A.,University of Trnava | Prokop P.,University of Trnava | Prokop P.,Slovak Academy of Sciences
Ethology | Year: 2010

In birds with biparental care, males and females often conflict over how much care to provide to their offspring and it may be substantially influenced by increased level of polygamy. In accordance with sexual conflict theory, males of socially polygynous bird species provide much less care to their nestlings than do males of most socially monogamous species. Most of previous studies, however, have used feeding behaviour as an index for variations in male parental care only. However, this may be skewed if polygynous males compensate for lower feeding assistance through the provision of other parental care such as protection of nests from predators. In this paper, we examine nest defence behaviour in the facultatively polygynous great reed warbler with respect to sex and type of social mating system. We recorded latency to the first arrival, distance from the predator and defensive reaction of each parent towards a human intruder. Socially polygynous males with two simultaneously active nests defended primary females' nests less vigorously than socially monogamous males, whereas no differences were found between monogamous and primary females. Generally, however, they took a bigger role in nest defence than males in all cases. Our results support an idea that sexual conflict is driven by polygamy and that type of social mating system can influence nest defence behaviour of facultatively polygynous birds. This finding should be taken into consideration when studying nest defence parental care in polygynous mating systems. © 2010 Blackwell Verlag GmbH.


Trnka A.,University of Trnava | Prokop P.,University of Trnava | Prokop P.,Slovak Academy of Sciences
Journal of Avian Biology | Year: 2011

There is increasing evidence that hosts within a population may not be parasitized by common cuckoos Cuculus canorus with equal probability. Such non-randomness has been documented, for example, for host nest sites and host quality. In this study we demonstrate association between successful cuckoo parasitism and host social mating system. We found that nests of socially polygynous great reed warblers Acrocephalus arundinaceus were more often successfully parasitized than the nests of their monogamous counterparts. We hypothesize that lack of parental assistance provided by polygynous males to their mates during egg laying period and higher nest activity in their territories could contribute to this discrepancy. These data imply that social mating system should be taken into account in future studies of brood parasitism. © 2011 The Authors. J. Avian Biol. © 2011 J. Avian Biol.


Foulis D.J.,University of Massachusetts Amherst | Pulmannova S.,Slovak Academy of Sciences
Foundations of Physics | Year: 2010

Effect algebras (EAs), play a significant role in quantum logic, are featured in the theory of partially ordered Abelian groups, and generalize orthoalgebras, MV-algebras, orthomodular posets, orthomodular lattices, modular ortholattices, and boolean algebras. We study centrally orthocomplete effect algebras (COEAs), i. e., EAs satisfying the condition that every family of elements that is dominated by an orthogonal family of central elements has a supremum. For COEAs, we introduce a general notion of decomposition into types; prove that a COEA factors uniquely as a direct sum of types I, II, and III; and obtain a generalization for COEAs of Ramsay's fourfold decomposition of a complete orthomodular lattice. © 2009 Springer Science+Business Media, LLC.


Pincak R.,Slovak Academy of Sciences | Smotlacha J.,Czech Technical University
European Physical Journal B | Year: 2013

The electronic properties of the wormhole and the perturbed nanocylinder were investigated using two different methods: the continuum gauge field-theory model that deals with the continuum approximation of the surface and the Haydock recursion method that transforms the surface into a simplier structure and deals with the nearest-neighbor interactions. Furthermore, the changes of the electronic properties were investigated for the case of enclosing the appropriate structure, and possible substitutes for the encloser were derived. Finally, the character of the electron flux through the perturbed wormhole was predicted from the model based on the multiwalled nanotubes. The effect of the "graphene blackhole" is introduced. © 2013 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.


Janak M.,Slovak Academy of Sciences | Ravna E.J.K.,University of Tromsø | Kullerud K.,University of Tromsø
Journal of Metamorphic Geology | Year: 2012

Kyanite- and phengite-bearing eclogites have better potential to constrain the peak metamorphic P-T conditions from phase equilibria between garnet+omphacite+kyanite+phengite+quartz/coesite than common, mostly bimineralic (garnet+omphacite) eclogites, as exemplified by this study. Textural relationships, conventional geothermobarometry and thermodynamic modelling have been used to constrain the metamorphic evolution of the Tromsdalstind eclogite from the Tromsø Nappe, one of the biggest exposures of eclogite in the Scandinavian Caledonides. The phase relationships demonstrate that the rock progressively dehydrated, resulting in breakdown of amphibole and zoisite at increasing pressure. The peak-pressure mineral assemblage was garnet+omphacite+kyanite+phengite+coesite, inferred from polycrystalline quartz included in radially fractured omphacite. This omphacite, with up to 37mol.% of jadeite and 3% of the Ca-Eskola component, contains oriented rods of silica composition. Garnet shows higher grossular (X Grs=0.25-0.29), but lower pyrope-content (X Prp=0. 37-0.39) in the core than the rim, while phengite contains up to 3.5Si pfu. The compositional isopleths for garnet core, phengite and omphacite constrain the P-T conditions to 3.2-3.5GPa and 720-800°C, in good agreement with the results obtained from conventional geothermobarometry (3.2-3.5GPa & 730-780°C). Peak-pressure assemblage is variably overprinted by symplectites of diopside+plagioclase after omphacite, biotite and plagioclase after phengite, and sapphirine+spinel+corundum+plagioclase after kyanite. Exhumation from ultrahigh-pressure (UHP) conditions to 1.3-1.5GPa at 740-770°C is constrained by the garnet rim (X Ca Grt=0.18-0.21) and symplectite clinopyroxene (X Na Cpx=0.13-0.21), and to 0.5-0.7GPa at 700-800°C by sapphirine (X Mg=0.86-0.87) and spinel (X Mg=0.60-0.62) compositional isopleths. UHP metamorphism in the Tromsø Nappe is more widespread than previously known. Available data suggest that UHP eclogites were uplifted to lower crustal levels rapidly, within a short time interval (452-449Ma) prior to the Scandian collision between Laurentia and Baltica. The Tromsø Nappe as the highest tectonic unit of the North Norwegian Caledonides is considered to be of Laurentian origin and UHP metamorphism could have resulted from subduction along the Laurentian continental margin. An alternative is that the Tromsø Nappe belonged to a continental margin of Baltica, which had already been subducted before the terminal Scandian collision, and was emplaced as an out-of-sequence thrust during the Scandian lateral transport of nappes. © 2012 Blackwell Publishing Ltd.


Poletti C.,Vienna University of Technology | Balog M.,Slovak Academy of Sciences | Simancik F.,Slovak Academy of Sciences | Degischer H.P.,Vienna University of Technology
Acta Materialia | Year: 2010

Aluminium powders with a mean particle size of around 1 μm were compacted by cold isostatic pressing (CIP) and additional forging. The specimens are characterized by hot compression tests, dilatometry and metallography. A 3D interconnected structure of alumina films <5 nm in thickness is observed by transmission electron microscopy and field emission gun scanning electron microscopy; it is associated with the natural oxide skin which covers every aluminium powder and occupies around 3 vol.%. The compression tests are carried out in the range of 350-520 °C at strain rates of 0.003-3 s-1. The compressive strength was 100-150 and 130-180 MPa for the CIPed and forged samples, respectively. The low strain rate sensitivity m (<0.08) suggests that the alumina network forms a barrier, which suppresses any restoration mechanism across the grain boundaries as well as grain boundary sliding during hot deformation. The high strength of such compacted sub-micron Al powder is attributed to the conservation of a 3D alumina closed cell network filled with elastoplastic aluminium. © 2010 Acta Materialia Inc.


Orfanus T.,Slovak Academy of Sciences | Eitzinger J.,University of Natural Resources and Life Sciences, Vienna
Ecohydrology | Year: 2010

Across a wide range of spatial and temporal scales, the soil water content (SWC) can be perceived as an integral component of the hydrological cycle. The concept of field capacity is insufficient to characterize the limits of ideal moisture conditions for plants and the concept of SWC of limited plant availability (θla) has been introduced to characterize the available SWC threshold value, below which the relative transpiration drops under 1 θla is not a stable property of soil but also depends on the actual evapotranspiration demand of the atmosphere (potential evapotranspiration, Ep). To avoid water stress and ensure high biomass production, water should be supplied to vegetation in order to maintain the optimal range of SWC above θla during important ontogenetic phases. The influence of two factors, one of which is pedological (soil texture) and another is biological (8-m high hedgerow) on field-scale fluctuations of θla, was studied in western Slovakia near Moravskỳ Svätỳ Ján (MSJ) village and in north-eastern Austria near the village Rutzendorf, respectively. In the MSJ-field θla values reflected the textural heterogeneity of soil. The intrapopulation range Δθla was 0.15 m3 m-3 in a clay loam Mollic Gleysol, but only 0.08 m3 m-3 in a loamy sand Arenic Regosol. The interpopulation differences in mean θla between two textural classes were 0.06-0.09 m3 m-3. The maximum Δθla caused by changes in textural composition over the 4.5 ha field was 0.18 m3 m-3. It was found during two SWC measurement campaigns with different boundary conditions [Ep and ground water (GW) table] that the loamy sand soil is much more susceptible to the occurrence of water stress than the clay loam. The actual SWC falls below the θla threshold more frequently in loamy sand because of its small water retention capacity, rapid drainage and poorer hydraulic connection with GW. The seasonal variability of θla in 2002 reached 0.06-0.09 m3 m-3, depending on textural class. The hedgerow at Field-Rutzendorf had a small effect on the spatial variation in θla during days with low Ep rates Δθla was less then 0.01 m3 m-3 when potential evapotranspiration was less then 1 mm day-1. However, during days with great atmospheric demand for evapotranspiration (6 mm day-1) Δθla reached 0.19 m3 m-3 during the 2004 growing season. The results illustrate that both evapotranspiration intensity and soil texture influence the occurrence of soil water stress. Copyright © 2010 John Wiley & Sons, Ltd.


Benedek R.,Argonne National Laboratory | Thackeray M.M.,Argonne National Laboratory | Low J.,Argonne National Laboratory | Bucko T.,Comenius University | And 2 more authors.
Journal of Physical Chemistry C | Year: 2012

Constrained density functional theory at the GGA+U level, within the Blue Moon ensemble, as implemented in the VASP code, is applied to simulate aqueous dissolution of lithium manganate spinel, a candidate cathode material for lithium ion batteries. Ions are dissolved from stoichiometric slabs of composition LiMn 2O 4, with orientations (001) and (110), embedded in a cell with 20 Å water channels between periodically repeated slabs. Analysis of the Blue Moon ensemble forces for dissolution of Li, Mn, and O ions from lithium manganate indicate that bond breaking occurs sequentially, ordered from weak to strong bonds, where bond breaking occurs when a bond length is stretched about 50% relative to its equilibrium value. Substrate ions are displaced to maintain bond lengths close to equilibrium for bonds other than that the one being broken. The predicted free energies required to break the chemical bonds with the LiMn 2O 4 substrate are Mn 3+, 1.4; O 2-, 1.0; Mn 2+, 0.8; and Li +, 0.35, in eV; an existing experimental measurement (Lu, C. H.; Lin, S. W. J. Mater. Res.2002, 17, 1476) had yielded an effective dissolution activation energy of 0.7 eV. A mechanism for the role of acid in promoting lithium manganate dissolution is discussed. © 2012 American Chemical Society.


Krajci M.,Slovak Academy of Sciences | Hafner J.,University of Vienna
Journal of Catalysis | Year: 2014

The activity and selectivity of the polar threefold surfaces of the B20-type intermetallic compound GaPd for the semi-hydrogenation of acetylene to ethylene has been investigated using ab initio density functional theory (DFT). Because of the lack of inversion symmetry, the threefold {1 1 1} surfaces of the B20 structure have polar character, in both nonequivalent [1 1 1] and [1̄1̄1̄] directions several surface terminations differing in structure and chemical composition are possible. The structural and energetic properties and the chemical reactivities of ten conceivable terminations have recently been investigated using DFT (Krajčí and Hafner, 2013) - here detailed atomistic scenarios for the selective semi-hydrogenation of acetylene to ethylene on these surfaces have been developed. Threefold surfaces with only Ga-atoms in the outermost layer are energetically favorable at the Ga-rich end of the interval of the admissible chemical potentials, but they are catalytically inactive because molecular hydrogen cannot be dissociated and hence the hydrogenation of adsorbed hydrocarbon molecules is impossible. Highly corrugated surfaces with Pd atoms in the top atomic plane can hydrogenate adsorbed acetylene molecules easily. But simultaneously their high reactivity with respect to both molecular and atomic hydrogen complicates dissociation and diffusion processes. The selectivity of such surfaces is also insufficient as ethylene molecules adsorbed on-top of highly protruding Pd atoms can be easily attacked by co-adsorbed hydrogen atoms from the bottom. We have found that one of the possible threefold surface terminations with isolated Pd3 triplets and Ga atoms in one-half of the hollows between the Pd3 triplets exhibits both superior catalytic activity and selectivity. However, this surface is energetically competitive only in a very narrow range of chemical potentials. An important factor for achieving a high selectivity is the transition from di-σ bonded adsorption configuration for acetylene to a π-bonded adsorption of ethylene. This transition has also been found in our earlier investigation of the (2 1 0) surface of GaPd as a catalyst for semi-hydrogenation (Krajčí and Hafner, 2012). The large distances between the isolated active sites is also important to avoid undesired side-reactions such as oligomerization. Our results are well compatible with the available experimental observations. We have demonstrated that the observed activity and selectivity of GaPd catalyst originate form contributions from different surfaces terminations differing in activity and selectivity. An optimal selectivity of the catalyst can be achieved only if the formation of surfaces with low selectivity is avoided and terminations with enhanced selectivity are formed. © 2014 Elsevier Inc. All rights reserved.


Bucko T.,Comenius University | Bucko T.,Slovak Academy of Sciences | Hafner J.,University of Vienna | Lebegue S.,University of Lorraine | Angyan J.G.,University of Lorraine
Physical Chemistry Chemical Physics | Year: 2012

Periodic dispersion corrected DFT calculations have been performed to study the spin-crossover transition of Fe(phen)2(NCS)2 in the molecular and in the crystalline state. We show that London dispersion interactions play a crucial role in the cohesion of the crystals. Based on calculations of vibrational eigenstates of the isolated molecule and of the crystalline phase in both the low- and high-spin states, the transition entropies and enthalpies have been calculated. We demonstrate that, due to the stabilization of the low-spin state by intermolecular dispersion forces, the transition enthalpy at the transition temperature is larger for the crystalline phase in comparison with an isolated molecule. The effective coordination number of the nitrogen atoms of the ligands around the iron atom has been identified as the order parameter driving the quasi-reversible low-spin to high-spin transition in the crystal. Finally, using constrained geometry relaxations at fixed values of the coordination number, we computed the energy barrier of the LS to HS transition and found it to be in a reasonable agreement with the experimental value. © the Owner Societies 2012.


Puliova P.,Park University | Puliova P.,Academy of Sciences of the Czech Republic | Kovac J.,Slovak Academy of Sciences | Voigt A.,Otto Von Guericke University of Magdeburg | Raschman P.,Park University
Journal of Magnetism and Magnetic Materials | Year: 2013

Nano-particles of CoFe2O4, NiFe2O 4 and Co0.5Ni0.5Fe2O4 were synthesized by a two step microemulsion precipitation where inverse micelles of water in hexanol were stabilized using cetyltrimethylammonium bromide. Powder X-ray diffraction analysis and Transmission electron microscopy measurements provided data to clarify the crystal structure and size of the produced nano-particles. Different measurements of magnetic properties at low temperatures of 2 K revealed that nano-particles of NiFe2O4 represent magnetically soft ferrite with a coercivity -40 kA!m, whereas nano-particles of CoFe 2O4 and Coo.5Nio5Fe2O4 were magnetically harder with a coercivity of 815 and 947 kA!m, respectively. Additionally zero field cooling and field cooling measurements provided data for estimating the blocking temperature of the materials produced. For NiFe 2O4 this temperature is lower, 23 K. The blocking temperature of CoFe2O4 of 238 K and Co0.5Ni0.5Fe 2O4 of 268 K are higher in comparison with NiFe 2O4. © 2013 Elsevier B.V. All rights reserved.


Bucko T.,Comenius University | Bucko T.,Slovak Academy of Sciences | Hafner J.,University of Vienna
Journal of Catalysis | Year: 2015

The competing influences of enthalpy and entropy on the adsorption and transformation of hydrocarbon molecules in zeolites have been investigated using dispersion-corrected density-functional theory in combination with advanced statistical-mechanical techniques. At the example of propane in protonated mordenite, it is demonstrated that while enthalpy favors adsorption in the narrower side pockets (SP) due to the stronger interaction with the framework, the loss of entropy is smaller for molecules in the wider main channel (MC). At ambient and elevated temperatures, the free energy favors adsorption in the MC (in agreement with experiment) and diffusion to the SP is an activated process. On the other hand, the free energy of activation for monomolecular cracking is lower for Brønsted acid (BA) sites in the SP, if the reactant is already located there. Cracking at a BA in the MC is a simple one-step reaction but as the SP is accessible to molecules only via the MC, cracking at a BA site in the SP is possible only after overcoming the barrier for diffusion from the MC to the SP. Thus, the difference in the free energies of adsorption in the MC and the SP increases the effective free-energy of activation for the reaction in SP and the reaction in the MC is favored. This result contradicts the interpretation of recent experiments on hydrocarbon transformations catalyzed by mordenite-containing BA sites and Na+ counterions in varying proportions. This experimental interpretation is based on the assumption that Na+ counterions preferentially replace BA sites located in the SP. This assumption has been critically examined using ab-initio calculations and found to be inconsistent with our theoretical predictions. It is demonstrated that the experimentally observed decrease of the reaction rate with increasing Na+/H+ ratio arises from the strongly attractive nature of the Na+ counterions, which makes the approach of the reactant to the BA site more difficult and reduces the reaction rate. We suggest that our results on the competing influence of enthalpy and entropy arising from the confinement of the reactant in cavities of different diameters have general validity for the adsorption and acid-catalyzed reactions of hydrocarbon molecules in zeolites with a complex framework structure. © 2015 Elsevier Inc. All rights reserved.


Bauer J.,Slovak Academy of Sciences | Ondrovicova G.,Slovak Academy of Sciences | Najmanova L.,Academy of Sciences of the Czech Republic | Pevala V.,Slovak Academy of Sciences | And 5 more authors.
Acta Crystallographica Section D: Biological Crystallography | Year: 2014

The S-adenosyl-l-methionine (SAM)-dependent methyltransferase CcbJ from Streptomyces caelestis catalyzes one of the final steps in the biosynthesis of the antibiotic celesticetin, methylation of the N atom of its proline moiety, which greatly enhances the activity of the antibiotic. Since several celesticetin variants exist, this enzyme may be able to act on a variety of substrates. The structures of CcbJ determined by MAD phasing at 3.0 Å resolution, its native form at 2.7 Å resolution and its complex with S-adenosyl-l-homocysteine (SAH) at 2.9 Å resolution are reported here. Based on these structures, three point mutants, Y9F, Y17F and F117G, were prepared in order to study its behaviour as well as docking simulations of both CcbJ-SAM-substrate and CcbJ-SAH-product complexes. The structures show that CcbJ is a class I SAM-dependent methyltransferase with a wide active site, thereby suggesting that it may accommodate a number of different substrates. The mutation results show that the Y9F and F117G mutants are almost non-functional, while the Y17F mutant has almost half of the wild-type activity. In combination with the docking studies, these results suggest that Tyr9 and Phe117 are likely to help to position the substrate for the methyl-transfer reaction and that Tyr9 may also facilitate the reaction by removing an H+ ion. Tyr17, on the other hand, seems to operate by helping to stabilize the SAM cofactor. © 2014 International Union of Crystallography.


Ferrari C.,Science 37 | Buffagni E.,Science 37 | Bonnini E.,Science 37 | Bonnini E.,University of Parma | Korytar D.,Slovak Academy of Sciences
Journal of Applied Crystallography | Year: 2013

Diffraction profiles of curved Si and GaAs crystals obtained by a controlled damage process on one side of planar crystals have been investigated at X-ray energies E = 17, 59 and 120keV. At E = 17 and 59keV in the condition of slight curvature, that is when the diffracting plane bending over the extinction length is lower than the Darwin width, the Laue diffraction profiles with lattice planes parallel or inclined with respect to the curvature radius R show an enhancement of integrated intensity proportional to 1/R, much larger than in the corresponding perfect bent crystals. At E = 120keV, in the condition of strong curvature, the crystals behave as bent perfect crystals with integrated intensity corresponding to that of a mosaic crystal. These crystals are proposed as optical elements for focusing hard X-ray beams. © 2013 International Union of Crystallography Printed in Singapore - all rights reserved.


Hafner J.,University of Vienna | Krajci M.,Slovak Academy of Sciences
Accounts of Chemical Research | Year: 2014

Complex intermetallic compounds are a class of ordered alloys consisting of quasicrystals and other ordered compounds with large unit cells; many of them are approximant phases to quasicrystals. Quasicrystals are the limiting case where the unit cell becomes infinitely large; approximants are series of periodic structures converging to the quasicrystal. While the unique properties of quasicrystals have inspired many investigations of their surfaces, relatively little attention has been devoted to the surface properties of the approximants.In general, complex intermetallic compounds display rather irregular, often strongly corrugated surfaces, making the determination of their atomic structure a very complex and challenging task. During recent years, scanning tunneling microscopy (STM) has been used to study the surfaces of several complex intermetallic compounds. If atomic resolution can be achieved, STM permits visualization of the local atomistic surface structure. However, the interpretation of the STM images is often ambiguous and sometimes even impossible without a realistic model of the structure of the surface and the distribution of the electronic density above the surface.Here we demonstrate that ab initio density functional theory (DFT) can be used to determine the energetics and the geometric and electronic structures of the stable surfaces of complex intermetallic compounds. Calculations for surfaces with different chemical compositions can be performed in the grand canonical ensemble. Simulated cleavage experiments permit us to determine the formation of the cleavage planes requiring the lowest energy. The investigation of the adsorption of molecular species permits a comparison with temperature-programmed thermal desorption experiments. Calculated surface electronic densities of state can be compared with the results of photoelectron spectroscopy. Simulations of detailed STM images can be directly confronted with the experimental results.Detailed results are presented for two intermetallic compounds that have recently attracted much attention as active and highly selective catalysts for the semihydrogenation of alkynes to alkenes, but the identification of the catalytically active surfaces was found to be very difficult. The crystal structure of B20-type GaPd can be interpreted as the lowest order approximant of icosahedral Al-Pd-Mn quasicrystals. Among the low-index surfaces, the {100} surface shows 2-fold symmetry and the {210} surface pseudo-5-fold symmetry; for both the surface stoichiometry is identical to that of the bulk. Because the structure lacks inversion symmetry, the {111} surfaces have polar character and permit terminations of widely different chemical composition. Results for all three surfaces are presented and compared with the available experiments. The crystal structure of orthorhombic Al13Co4 is built by pentagonal clusters similar to those found in decagonal Al-Co and Al-Ni-Co quasicrystals. A simulated cleavage experiment shows that the constituent clusters remain intact upon cleavage, resulting in the formation of a highly corrugated (100) surface. The calculated STM images are found to be in very good agreement with experiment and permit in addition identification of possible surface modifications by the desorption of individual atoms. Pentagonal motifs on the {210} surface of GaPd and on the (100) surface of Al13Co4 consisting of simple- and transition-metal atoms have been identified as the catalytically active centers for the semihydrogenation of acetylene to ethylene. © 2014 American Chemical Society.


Krajci M.,Slovak Academy of Sciences | Hafner J.,University of Vienna
Journal of Physical Chemistry C | Year: 2014

Ab-initio density-functional calculations have been used to investigate the structure and stability of the (010) surfaces of the intermetallic compound GaPd2 and their activity and selectivity for the catalytic semihydrogenation of acetylene to ethylene. The calculations of the surface energies show that Ga-enrichment of the surface is energetically favored under Ga-rich preparation conditions. The bulk-terminated stoichiometric GaPd 2(010) surface is catalytically active but does not exhibit the desired selectivity. The high Pd concentration in the surface leads to the formation of Pd3 triplets favoring a strong binding of ethylene and its further hydrogenation to ethyl. In contrast Ga-enriched GaPd 2(010) surfaces provide an excellent selectivity for the formation of ethylene. Selectivity increases with increasing number of Ga atoms in the vicinity of the active Pd atoms. The atomistic scenarios for the dissociative adsorption of hydrogen, the diffusion of atomic hydrogen, and the hydrogenation reactions of acetylene to vinyl and further to ethylene demonstrate that on the selective surfaces the catalytically active centers are triangular configurations of one Pd and two Ga atoms binding acetylene through di-σ bonds in Ga-Ga bridge sites. Ethylene, on the other hand is only weakly π-bonded on top of the Pd atom such that desorption is easier than further hydrogenation to ethyl. It is remarkable that the atomic structure of one of the Ga-enriched GaPd2(010) surfaces is very similar to that of the (001) surface of the Ga3Pd5 compound and to the structure of the (210) surface of GaPd. The structural similarity of the surfaces results in comparable catalytic properties. The comparison with the results for the semihydrogenation of acetylene to ethylene on the (210) surfaces of GaPd and AlPd and on the (100) surface of Al13Co4 suggests that the concept of catalytically active centers consisting of transition-metal-sp- bonded-metal complexes has general validity. © 2014 American Chemical Society.


Stefek M.,Slovak Academy of Sciences | Karasu C.,Gazi University
Rejuvenation Research | Year: 2011

Old age is accompanied by a number of pathological eye conditions. Cataract is the most common age-related eye complication. Because the lens becomes naturally more opaque over time, aging is the most important risk factor for developing cataract, which is a major cause of blindness in the world. Cataractogenesis is also one of the earliest secondary complications of diabetes mellitus. The lens is a closed system with limited capability to repair or regenerate itself. Current evidence supports the view that cataractogenesis is a multifactorial process. Oxidative stress and its sequelae are clearly involved in the etiology of senile cataract, whereas mechanisms related to glucose toxicity, namely oxidative stress, processes of nonenzymatic glycation, and enhanced polyol pathway contribute significantly to the development of the eye complications under conditions of diabetes. There is an urgent need for inexpensive, nonsurgical approaches to the treatment of cataract. Recently, considerable attention has been devoted to the search for phytochemical therapeutics. Several pharmacological actions of natural flavonoids may operate in preventing cataract because flavonoids are capable of affecting multiple mechanisms or etiological factors responsible for the development of sight-threatening ocular diseases. The flavonol quercetin is the most widely consumed flavonoid in the human diet. In this article, quercetin is reviewed as an agent that could reduce the risk of cataract formation via affecting multiple pathways pertinent to eye lens opacification, including oxidative stress, nonenzymatic glycation, the polyol pathway, lens calpain proteases, and epithelial cell signaling. In addition, the bioavailability of quercetin to the lens is considered. © 2011 Mary Ann Liebert, Inc.


Bucko T.,Comenius University | Bucko T.,Slovak Academy of Sciences | Lebegue S.,CNRS Laboratory of Crystallography, Nuclear Magnetic Resonance and Modelling | Hafner J.,University of Vienna | Angyan J.G.,CNRS Laboratory of Crystallography, Nuclear Magnetic Resonance and Modelling
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

The method proposed by Tkatchenko and Scheffler to correct density functional calculations for the missing van der Waals interactions is implemented in the Vienna ab initio simulation package (vasp) code and tested on a wide range of solids, including noble-gas crystals, molecular crystals (α-N2, sulfur dioxide, benzene, naphthalene, cytosine), layered solids (graphite, hexagonal boron nitride, vanadium pentoxide, MoS2, NbSe2), chain-like structures (selenium, tellurium, cellulose I), ionic crystals (NaCl, KI), and metals (nickel, zinc, cadmium). In addition to the original formulation expressing the van der Waals (vdW) corrections as pairwise potentials whose strength is derived from the rescaled polarizabilities of the neutral free atoms, the self-consistently screened (TS+SCS) variant of the method involving electrodynamic response effects has been examined. Analytical expressions for the forces acting on the atoms and for the components of the stress tensor needed for the relaxation of the volume and shape of the unit cell using the TS+SCS method are derived. While the calculated structures are reasonably close to experiment, the van der Waals corrections to the binding energies are often found to be overestimated in comparison with experimental data. The TS+SCS approach leads to significantly better results in some problematic cases, such as the binding energy of graphite. However, there is room for further improvements, in particular for strongly ionic systems. © 2013 American Physical Society.


Bucko T.,Comenius University | Bucko T.,Slovak Academy of Sciences | Bucko T.,University of Vienna | Lebegue S.,CNRS Laboratory of Crystallography, Nuclear Magnetic Resonance and Modelling | And 2 more authors.
Journal of Chemical Theory and Computation | Year: 2013

The Tkatchenko-Scheffler method for calculating dispersion correction to standard density-functional theory, which uses fixed neutral atoms as a reference to estimate the effective volumes of atoms-in-molecule and to calibrate their polarizabilities and dispersion coefficients, fails to describe the structure and the energetics of ionic solids. Here, we propose a more appropriate partitioning, based on the iterative Hirshfeld scheme, where the fractionally charged atomic reference state is determined self-consistently. We show that our new method extends the applicability of the original method in particular to study ionic systems and adsorption phenomena on surfaces of ionic solids. © 2013 American Chemical Society.


Krajci M.,Slovak Academy of Sciences | Hafner J.,University of Vienna
Journal of Physical Chemistry C | Year: 2012

Recently, it has been demonstrated that intermetallic compounds composed of Pd and Ga or Co and Al provide excellent selectivity for the hydrogenation of acetylene to ethylene. Motivated by experimental works on GaPd catalysts, we have performed a detailed ab initio study of acetylene hydrogenation by the pseudo 5-fold (120) surface of the isostructural and isoelectronic AlPd compound crystallizing in the B20-type structure. The structure of the surface can be described by a triangle-rectangle tiling, and we demonstrate that the most active sites for hydrogenation are triangular arrangements of two Al and one Pd atom. Acetylene is bound to bridge sites between two Al atoms. The most favorable adsorption site for ethylene is on top of the most strongly protruding Pd atom. Activation energies for all steps of the reaction have been calculated. We demonstrate that the activation energies for the rate-controlling steps are comparable to those on reference catalysts (Pd, Pd-Ag, and Al 13Co 4) and that a desorption energy for ethylene that is lower than the activation energy of ethylene to ethyl provides thus good selectivity. We show that the decisive factors for the activity and selectivity of the catalyst are the same on both intermetallic compounds AlPd and Al 13Co 4. © 2012 American Chemical Society.


Krajci M.,Slovak Academy of Sciences | Krajci M.,University of Vienna | Hafner J.,University of Vienna
Philosophical Magazine | Year: 2011

While the surfaces of ordinary crystals provide only a few inequivalent adsorption sites, the complex landscape of the surfaces of quasicrystals and their approximants provides a rich variety of different adsorption sites. Recently, Armbruster et al. reported that Al13Co4, whose structure is closely related to decagonal Al-Ni-Co quasicrystals, is an efficient and selective hydrogenation catalyst for alkynes. In the present work, the hydrogenation of acetylene to ethylene on the (100) surface of Al 13Co4 has been studied using ab initio density-functional simulations. Surprisingly, the stable cleavage surface of Al13Co 4 is strongly corrugated. The surface is covered by zig-zag chains of edge-sharing Al pentagons, each centered on a Co atom and separated from neighboring chains by wide troughs. The binding energies for adsorption and co-adsorption of H2 and C2H2 molecules at various surface sites have been calculated. Surprisingly, in the energetically most favorable configuration, acetylene is bound in a di-δ configuration to two Al atoms, not to the Co atom. We have searched for the optimal reaction pathway for the dissociatible adsorption of hydrogen and for the hydrogenation of acetylene to vinyl, ethylene by a Langmuir-Hinshelwood mechanism. The energetic barriers for all reaction steps were calculated by the nudged-elastic-band method. It was found that the energetic barrier of any reaction step does not exceed 0.65 eV (63 kJ/mol). This value is lower than the activation energies for acetylene to ethylene hydrogenation over a Pd catalyst where barriers of 78 kJ/mol and 85 kJ/mol were reported for the rate-determining steps. © 2011 Taylor & Francis.


Benco L.,University of Vienna | Benco L.,Slovak Academy of Sciences
Journal of Catalysis | Year: 2013

The compensation effect is investigated using DFT calculations of the activation of the N2O molecule over mononuclear cations (Fe 2+, Co2+) and cationic oxo-particles (RuO2+, RuO+), identified as perspective active sites. Constrained MD simulations are used to calculate Helmholtz free energies of activation at 300 K, 420 K, and 700 K. Reaction rates calculated according to the transition state theory are used to construct Arrhenius plots (AP). Activation energies, derived from the AP, are 60.9 kJ/mol, 77.2 kJ/mol, 99.4 kJ/mol, and 105.1 kJ/mol for RuO+, Fe2+, Co2+, and RuO2+, respectively. A linear dependence between enthalpy of activation ΔH ‡ and entropy of activation ΔS‡ is observed only when the reaction exhibits the isokinetic behavior. The change of entropy of activation is approximately three orders smaller than the change of enthalpy. For the activation of N2O, a rare case of the anticompensation is observed. The reaction rates computed for the temperature range between 300 K and 700 K increase in order: RuO+ > Fe 2+ > Co2+ > RuO2+. © 2012 Elsevier Inc. All rights reserved.


Krajci M.,Slovak Academy of Sciences | Hafner J.,University of Vienna
Journal of Chemical Physics | Year: 2013

The polar threefold surfaces of the GaPd compound crystallizing in the B20 (FeSi-type) structure (space group P213) have been investigated using density-functional methods. Because of the lack of inversion symmetry the B20 structure exists in two enantiomorphic forms denoted as A and B. The threefold {111} surfaces have polar character. In both nonequivalent (111) and (111) directions several surface terminations differing in structure and chemical composition are possible. The formation of the threefold surfaces has been studied by simulated cleavage experiments and by calculations of the surface energies. Because of the polar character of the threefold surfaces calculations for stoichiometric slabs permit only the determination of the average energy of the surfaces exposed on both sides of the slab. Calculations for nonstoichiometric slabs performed in the grand canonical ensemble yield differences of the surface energies for the possible terminations as a function of the chemical potential in the reactive atmosphere above the surface and predict a transition between Ga- and Pd-terminated surfaces as a function of the chemical potential. The {100} surfaces are stoichiometric and uniquely defined. The calculated surface energies are identical to the average energies of the {100} surfaces of the pure metals. The {210} surfaces are also stoichiometric, with an energy very close to that of the {100} surfaces. Assuming that for the {111} surfaces the energies of different possible terminations are in a proportion equal to that of the concentration-weighted energies of the {111} surfaces of the pure metals, surface energies for all possible {111} terminations may be calculated. The preferable termination perpendicular to the A111 direction consists of a bilayer with three Ga atoms in the upper and three Pd atoms in the lower part. The surface energy of this termination further decreases if the Pd triplet is covered by additional Ga atom. Perpendicular to the A111 direction the lowest energy has been found for a bilayer with three Ga atoms per surface cell in the upper layer and one Ga and one Pd in the lower part. The calculated surface energies are in agreement with a simulated cleavage experiment. However, cleavage does not result in the formation of the lowest-energy surfaces, because all possible {111} cleavage planes expose a low-energy surface on one, and a high-energy surface on the other side. The prediction of Ga-terminated surfaces has been tested against the available experimental information. The calculated surface electronic density of states is in very good agreement with photo-emission spectroscopy. Calculated STM images of the most stable surfaces agree with all details of the available experimental images. The chemical reactivity of the most stable surfaces has been studied by the adsorption of CO molecules. The adsorption energies and maximum coverages calculated for the Ga-terminated surfaces permit a reasonable interpretation of the observed thermal desorption spectra, whereas for the Pd-terminated surfaces the calculated adsorption energies are far too high. © 2013 American Institute of Physics.


Krajci M.,Slovak Academy of Sciences | Hafner J.,University of Vienna
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

The low-index surfaces of the AlPd compound crystallizing in the B20 (FeSi-type) structure have been investigated using ab initio density functional methods. The space group of the B20 structure is P213, with four threefold rotational axes along the 111 directions and three twofold screw axes along the 100 directions, but no inversion symmetry. The B20 structure exists in two enantiomorphic forms related by inversion. The termination of the structure perpendicular to the twofold screw axes is uniquely defined: The corrugated {100} surfaces are formed by the characteristic zigzag Al-Pd chains separated by shallow troughs. Perpendicular to the 210a directions the structure consists of slightly puckered planes containing Al and Pd in equal numbers. The {210} surfaces shows pseudo-fivefold symmetry. Their structure is shown to be closely related to that of the {110} surfaces of the B2 structure. Both the {100} and {210} surfaces undergo some structural relaxation, but no reconstruction changing their (1×1) periodicity. While perpendicular to the 100 and 210 directions only one surface termination is possible, perpendicular to the threefold 111 directions there are several possible surface terminations differing in structure and chemical composition. Because of the lack of inversion symmetry the threefold {111} surfaces have polar character. The (111) and (1̄1̄1̄) surfaces are not equivalent; the (111) surfaces of one enantiomorph are identical to the (1̄1̄1̄) surfaces of the other form (and vice versa). In both the (111) and (1̄1̄1̄) directions several surface terminations are possible. The formation of threefold surfaces has been studied by simulated cleavage experiments and by calculations of the surface energies of all possible terminations. Perpendicular to the 111 direction the lowest energy has been found for a bilayer with three Al atoms per surface cell in the upper layer and one Al and one Pd in the lower part. The preferable termination perpendicular to the 1̄1̄1 direction is more symmetric; it consists again of a bilayer with three Al atoms in the upper and three Pd atoms in the lower part. The surface energy of this termination further decreases if the Pd triplet is covered by additional Al atom. The calculated surface energies permit us to perform a Wulff construction of the equilibrium shape of AlPd crystallites. {100} and {210} facets together occupy 77% of the surface area in about equal proportion. The high anisotropy of the energy of the {111} surfaces results in the substantial difference of the surface areas of the opposite threefold facets. © 2013 American Physical Society.


Krajci M.,University of Vienna | Krajci M.,Slovak Academy of Sciences | Hafner J.,University of Vienna
Journal of Catalysis | Year: 2011

Recently, a novel concept for the design of selective and stable catalysts for the hydrogenation of alkynes has been announced - the isolation of the active sites on the surface of a complex intermetallic compound. The basic idea is that isolated active sites enable only a reduced number of possible adsorption geometries for the reactants, leading to a narrower range of possible reaction products. However, so far an atomistic scenario for the complex multi-step hydrogenation process catalyzed by complex intermetallic compounds has not yet been developed. Here, we present detailed ab initio density-functional simulations of the surface structure and of the selective hydrogenation of acetylene to ethylene on the (1 0 0) surface of the compound Al13Co4. In agreement with recent STM investigations, our calculations show that the surface is highly corrugated with well-separated Co surface atoms in the center of CoAl5 pentagons. The activation energies for the rate-controlling steps are found to be comparable or even lower than those calculated for conventional Pd or Pd-Ag catalysts, and the desorption energy of ethylene is lower than the barrier to further hydrogenation to ethyl. This confirms that Al13Co4 is an efficient as well as highly selective catalyst. Our results demonstrate that the active sites are not the Co atoms alone, but pentagonal CoAl5 clusters forming zig-zag chains on the surface separated by wide troughs. The high activity of the Al atoms in these clusters is promoted by the strong, partially covalent bonding between Al and Co atoms, as well as by their low coordination in a surface with a very complex topology. © 2010 Elsevier Inc. All rights reserved.


Chattopadhyay D.,IISER Kolkata | Zuschin M.,University of Vienna | Tomasovych A.,Slovak Academy of Sciences
Paleobiology | Year: 2014

Edge-drilling is an unusual predation pattern in which a predatory gastropod drills a hole on the commissure between the valves of a bivalve. Although it is faster than wall drilling, it involves the potential risk of amputating the drilling organ. We therefore hypothesize that this risky strategy is advantageous only in environments where predators face high competition or predation pressure while feeding. The high frequency of edge-drilling (EDF, relative to the total number of drilled valves) in a diverse Recent bivalve assemblage from the Red Sea enables us to test this hypothesis, predicting (1) a low EDF in infaunal groups, (2) a high EDF in bivalves with elongated shape, (3) high incidence of edge-drilling in groups showing a high wall-drilling frequency, and (4) high EDF in shallow habitats. We evaluate these predictions based on >15,000 bivalve specimens. Among ecological attributes, we found substrate affinity and predation intensity of a species to be good predictors of edge-drilling incidence. Infaunal taxa with high length/width ratio have a low EDF, in accordance with our predictions. Predation intensity is also a significant predictor of edge-drilling; groups with high predation intensity show higher incidence of edge-drilling, confirming our prediction. Although water depth fails to show any significant effect on EDF, this analysis generally supports the high-risk hypothesis of edge-drilling incidence because shallow depths have considerable microhabitat variability. Classically the drill hole site selection has often been linked to predatory behavior. Our study indicates that prey attributes are also crucial in dictating the behavioral traits of a driller such as site selection. This calls for considering such details of the prey to fully understand predation in modern and fossil habitats. Moreover, this perspective is important for tackling the longstanding riddle of the limited temporal and spatial distribution of edge-drilling. © 2014 The Paleontological Society. All rights reserved.


Stateva I.,Bulgarian Academy of Science | Iliev I.K.,Bulgarian Academy of Science | Budaj J.,Slovak Academy of Sciences
Monthly Notices of the Royal Astronomical Society | Year: 2012

We continue here the systematic abundance analysis of a sample of Am binaries in order to search for possible abundance anomalies driven by tidal interaction in these binary systems. New CCD observations of HD116657, HD138213, HD155375, HD159560, HD196544 and HD204188 were obtained in two spectral regions (6400-6500 and 6660-6760Å). A synthetic spectrum analysis was carried out and the basic stellar properties, effective temperatures, gravities, projected rotational velocities, masses, ages and abundances of several elements were determined. We conclude that all six stars are Am stars. These stars were put into the context of other Am binaries with 10 < P orb < 200d, and their abundance anomalies discussed in the context of possible tidal effects. There is a clear anticorrelation of the Am peculiarities with vsini. However, there seems also to be a correlation with the eccentricity and perhaps with the orbital period. The dependence on temperature, age, mass and microturbulence was studied as well. The projected rotational velocities obtained by us were compared with those of Royer et al. and Abt & Morrell. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS.


Morimae T.,Gunma University | Nagaj D.,Slovak Academy of Sciences | Schuch N.,RWTH Aachen
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2016

Quantum Merlin Arthur (QMA) is the class of problems which, though potentially hard to solve, have a quantum solution that can be verified efficiently using a quantum computer. It thus forms a natural quantum version of the classical complexity class NP (and its probabilistic variant MA, Merlin-Arthur games), where the verifier has only classical computational resources. In this paper, we study what happens when we restrict the quantum resources of the verifier to the bare minimum: individual measurements on single qubits received as they come, one by one. We find that despite this grave restriction, it is still possible to soundly verify any problem in QMA for the verifier with the minimum quantum resources possible, without using any quantum memory or multiqubit operations. We provide two independent proofs of this fact, based on measurement-based quantum computation and the local Hamiltonian problem. The former construction also applies to QMA1, i.e., QMA with one-sided error. © 2016 American Physical Society.


Krajci M.,Slovak Academy of Sciences | Hafner J.,University of Vienna
Journal of Catalysis | Year: 2012

Recently, it has been demonstrated that intermetallic compounds composed of transition (Pd and Co) and simple (Ga and Al) metals used as catalysts provide excellent efficiency and selectivity for the hydrogenation of acetylene to ethylene. Motivated by experimental work on GaPd catalysts, we have performed a detailed density-functional study of the hydrogenation of acetylene catalyzed by the B20-type GaPd compound. We have identified the pseudo-fivefold (2 1 0) surface of the B20 structure as a possible catalytically active surface termination. The atomic structure of the (2 1 0) surface can be described by a triangle-rectangle tiling. An atomistic scenario has been constructed for the hydrogenation process catalyzed by this surface. We demonstrate that the active sites for the hydrogenation of acetylene to vinyl and further to ethylene are triangular arrangements of two Ga and one Pd atom atoms. Acetylene is bound to bridge sites formed by two Ga atoms. Vinyl formed in a first hydrogenation step is strongly attached to a Ga atom through its CH group, while the CH 2 group shifts toward a neighboring Pd atom. In contrast, ethylene is bound only on top of the Pd atom most strongly protruding from the surface. The activation energies for all steps of the reaction (dissociative adsorption and diffusion of hydrogen, adsorption of all hydrocarbon species, hydrogenation of acetylene to vinyl, of vinyl to ethylene, and of ethylene to ethyl, desorption of ethylene) have been calculated. The activation energies for the rate-controlling steps of 60-70 kJ/mol are comparable to those on other catalytically active compounds AlPd and Al 13Co 4 investigated in previous studies and also comparable or even lower than for a pure Pd catalyst. The desorption energy for ethylene of 45 kJ/mol is at least by 14 kJ/mol lower than the activation energy of ethylene to ethyl and provides thus excellent selectivity of GaPd. We show that the decisive factors for the activity and selectivity of the catalyst (corrugated surface with slightly protruding transition-metal atoms forming together with two neighboring Al/Ga atoms a triangular arrangement) are essentially the same on all investigated intermetallic compounds GaPd, AlPd, and Al 13Co 4. © 2012 Elsevier Inc. All rights reserved.


Krajci M.,Slovak Academy of Sciences | Hafner J.,University of Vienna
ChemCatChem | Year: 2016

During the last decade, it has been demonstrated that the use of intermetallic compounds composed of simple and transition metals as catalysts leads to improved activity and selectivity for a number of industrially important processes. Herein, we discuss the insight gained from density functional theory (DFT) calculations for the example of the semihydrogenation of acetylene to ethylene catalyzed by compounds of Pd with Ga or Al and of Co or Fe with Al. Investigations of the potentially active surfaces demonstrate that the chemical composition of nonstoichiometric surfaces depends strongly on the preparation conditions. Ga- or Al-terminated surfaces are catalytically inactive because they cannot dissociate hydrogen, but Pd-terminated surfaces are also unfavorable because the activation energy for the rate-controlling step is higher than the desorption energy of acetylene. Active sites promoting a selective semihydrogenation are triangular groups consisting of two simple-metal (Al, Ga) atoms and one transition-metal (Pd, Co) atom. Acetylene is strongly bound to simple-metal atoms in a di-σ configuration, whereas ethylene is weakly π bonded on top of a transition-metal atom. The change from strong to weak bonding is of great importance for the selectivity of the process. The novel point elucidated by the DFT calculations is the strong reactivity of the non-transition-metal atoms arising from the strong metallocovalent bonding in the compounds, which also contributes to their stability. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.


Perez S.,CNRS Molecular Pharmacochemistry Department | Tvaroska I.,Slovak Academy of Sciences | Tvaroska I.,Constantine the Philosopher University
Advances in Carbohydrate Chemistry and Biochemistry | Year: 2014

The article reviews the significant contributions to, and the present status of, applications of computational methods for the characterization and prediction of protein-carbohydrate interactions. After a presentation of the specific features of carbohydrate modeling, along with a brief description of the experimental data and general features of carbohydrate-protein interactions, the survey provides a thorough coverage of the available computational methods and tools. At the quantum-mechanical level, the use of both molecular orbitals and density-functional theory is critically assessed. These are followed by a presentation and critical evaluation of the applications of semiempirical and empirical methods: QM/MM, molecular dynamics, free-energy calculations, metadynamics, molecular robotics, and others. The usefulness of molecular docking in structural glycobiology is evaluated by considering recent docking- validation studies on a range of protein targets. The range of applications of these theoretical methods provides insights into the structural, energetic, and mechanistic facets that occur in the course of the recognition processes. Selected examples are provided to exemplify the usefulness and the present limitations of these computational methods in their ability to assist in elucidation of the structural basis underlying the diverse function and biological roles of carbohydrates in their dialogue with proteins. These test cases cover the field of both carbohydrate biosynthesis and glycosyltransferases, as well as glycoside hydrolases. The phenomenon of (macro)molecular recognition is illustrated for the interactions of carbohydrates with such proteins as lectins, monoclonal antibodies, GAG-binding proteins, porins, and viruses. © 2014 Elsevier Inc.


Capek P.,Slovak Academy of Sciences | Matulova M.,Slovak Academy of Sciences | Navarini L.,Illycaffe s.p.a. | Suggi-Liverani F.,Illycaffe s.p.a.
Carbohydrate Polymers | Year: 2010

An arabinogalactan-protein (AGP) composed of d-galactose and l-arabinose in 9:1 mol proportion containing about 1.6% of protein has been isolated from the instant coffee powder of roasted Coffea arabica beans by water extraction followed by barium hydroxide and ethanol precipitations. AGP was recovered in 3.2% yield of instant coffee powder and its average molecular mass was significantly decreased due to severe manufacturing conditions to 5400. Chemical and spectroscopic studies on the instant coffee AGP revealed a β-(1,3)-linked Galp backbone branched at C6 by side 6-linked Galp residues terminated by Araf and/or Galp and confirming thus an α-arabino-3,6-β-galactan in the instant coffee powder composite. It has been found that about 74% of branched 3,6-linked Galp residues have their origin in the backbone while 26% is located in side chains (6-linked Gal units substituted at C3 by Araf or terminal Galp units). Moreover, about 11% of Galp residues involved in linear 1,6-linkages of AGP side chains survived a severe industrial process. © 2009 Elsevier Ltd. All rights reserved.


Krajci M.,Slovak Academy of Sciences | Hafner J.,University of Vienna
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

The formation and the structural and electronic properties of the (100) surface of the complex intermetallic compound Al13Co4 have been investigated using ab initio density functional methods. While the layered crystal structure of the compound suggests that the (100) surface is formed by cleaving the crystal between adjacent flat (F) and puckered (P) layers, a simulated cleavage experiment shows that the P layer splits into two complementary parts to preserve the integrity of very stable clusters forming pentagonal bipyramids (PB's). The stable surface is terminated by an incomplete P layer consisting of the tips of the PB clusters and exposing in the interstices that part of the underlying F layer forming the connection between the PB's. The stability of this strongly corrugated surface is further confirmed by the calculation of the surface energies and of the formation energies of surface vacancies, as well as by a simulated high-temperature annealing. The analysis of the electronic structure shows that the stability of the PB clusters arises primarily from strong, partially covalent vertical Co-Al-Co bonds between the tips of the clusters. Simulated scanning tunneling microscopy (STM) images are provided to permit a comparison with the STM experiments of Addou. Measured and simulated STM images are in good agreement, possible reasons for the remaining differences in the Al/Co contrast are discussed in detail. © 2011 American Physical Society.


Benco L.,University of Vienna | Benco L.,Slovak Academy of Sciences | Bucko T.,Comenius University | Hafner J.,University of Vienna
Journal of Catalysis | Year: 2011

The dehydrogenation of propane over Zn 2+-exchanged mordenite has been studied theoretically using ab initio density-functional calculations at different levels of theory. We compare (i) total-energy calculations based on semilocal exchange-correlation functionals with those adding semi-empirical corrections for dispersion forces, (ii) calculations based on a large periodic model of the zeolite with calculations based on small and large finite cluster models, and (iii) calculations of the free energies of activation and of the reaction rates based on harmonic transition state theory (hTST) with those based on thermodynamic integration over free-energy gradients determined by constrained ab initio molecular dynamics. Dehydrogenation proceeds in four steps: (i) adsorption of propane on the Zn 2+ cation, (ii) dissociation of a hydrogen atom leading to the formation of a Zn-propyl complex and a Brønsted acid site, (iii) reaction of the acid proton and a β-H atom of propyl, resulting in the elimination of a hydrogen molecule, and (iv) desorption of propene from the Zn 2+ cation. The periodic calculations demonstrate that the dispersion corrections increase the adsorption/desorption energies from 70 to 107 kJ/mol for propane and from 177 to 233 kJ/mol for propene and decrease the activation energy for H-dissociation from 73 to 61 kJ/mol, while the activation energy for the heterolytic dehydrogenation is almost unaffected with 132 kJ/mol. Hence, dispersion corrections are of foremost importance for lowering the activation energy for H-dissociation below the desorption energy of propane. While according to the periodic calculations the highest activation energies are predicted for the heterolytic dehydrogenation and the desorption of propene, cluster calculations predict a higher activation energy for H-dissociation than for H 2 elimination. Both hTST and thermodynamic integrations show that both activation processes lead to a loss of entropy because the transition state configurations admit for a lower degree of disorder than the initial and intermediate states. hTST consistently underestimates the loss of entropy, the anharmonic corrections are most important for the H-dissociation step. © 2010 Elsevier Inc.


Jackson F.,Moredun Research Institute | Varady M.,Slovak Academy of Sciences | Bartley D.J.,Moredun Research Institute
Small Ruminant Research | Year: 2012

Disease caused by gastrointestinal (GI) nematodes is arguably one of the most important health constraints affecting productivity in small ruminants. This is of particular importance for many tropical and subtropical countries where goats play a vital role in the agricultural economies. Anthelmintic resistance is an important component of the losses attributable to parasitoses, unfortunately there is ample evidence that it is more common in goats than in other farmed ruminants. The increased prevalence of anthelmintic resistance in goats can largely be explained by unique aspects of their pharmacology, immunology and behaviour, all of which we need to understand and make allowance for if we are to effectively and sustainably manage anthelmintic resistance in goats. © 2011 Elsevier B.V.


Pripfl J.,University of Vienna | Tomova L.,University of Vienna | Riecansky I.,University of Vienna | Riecansky I.,Slovak Academy of Sciences | Lamm C.,University of Vienna
Brain Stimulation | Year: 2014

Background TMS has high potential as smoking cessation treatment. However, the neural mechanisms underlying TMS induced reduction of tobacco craving remain unclear. Electroencephalographic (EEG) delta frequency has been associated with the activity of the dopaminergic brain reward system, which is crucial for nicotine induced effects, and decreases after nicotine admission in smokers. Objective The aim of this study was to investigate EEG delta power changes induced by hf rTMS of the left dorsolateral prefrontal cortex (DLPFC) in nicotine deprived smokers and it's relation to cue-induced nicotine craving. Methods Fourteen healthy smokers meeting ICD-10 criteria for tobacco addiction participated in this within-subject sham controlled study. Participants had to abstain from smoking 6 h before the experiment. Effects of high-frequency repetitive TMS (hf rTMS) (10 Hz) for verum (left DLPFC) and sham (vertex) stimulations on cue-induced nicotine craving and resting state EEG delta power were assessed before and three times within 40 min after rTMS. Results Both craving (P = 0.046) and EEG delta power (P = 0.048) were significantly lower after verum stimulation compared to sham stimulation across the whole post stimulation time period assessed. However, changes of craving ratings and delta power did not correlate. Conclusion Hf rTMS applied to the left DLPFC reduces nicotine craving in short-term abstinent smokers. Changes in delta activity support the idea that stimulation induced effects are mediated by the dopaminergic brain reward system, which presumably plays a prominent, but probably not exclusive, role in this stimulation induced behavioral modulation, making this method a promising smoking cessation treatment candidate. © 2014 Elsevier Inc.


News Article | December 18, 2015
Site: boingboing.net

These are the "walking palm trees" of Ecuador. Each year, they could walk as much as 20 meters. Slower than the Ents from Lord of the Rings but, well, real. “As the soil erodes, the tree grows new, long roots that find new and more solid ground, sometimes up to 20m,” Peter Vrsansky, a palaeobiologist from the Earth Science Institute of the Slovak Academy of Sciences Bratislava, tells the BBC. “Then, slowly, as the roots settle in the new soil and the tree bends patiently toward the new roots, the old roots slowly lift into the air. The whole process for the tree to relocate to a new place with better sunlight and more solid ground can take a couple of years.” Tragically, the incredible Sumaco Biosphere Reserve where they live is being chopped down. “This [cutting] is a shame, as Ecuador is one of the world countries with the highest partition of protected areas," Vransky says, But the trees can’t walk fast enough to escape the chainsaw and the machetes backed by current legislation."


Chiang C.-F.,University of Central Florida | Nagaj D.,Slovak Academy of Sciences | Wocjan P.,University of Central Florida
Quantum Information and Computation | Year: 2010

We present an efficient general method for realizing a quantum walk operator corresponding to an arbitrary sparse classical random walk. Our approach is based on Grover and Rudolph's method for preparing coherent versions of efficiently integrable probability distributions [1]. This method is intended for use in quantum walk algorithms with polynomial speedups, whose complexity is usually measured in terms of how many times we have to apply a step of a quantum walk [2], compared to the number of necessary classical Markov chain steps. We consider a finer notion of complexity including the number of elementary gates it takes to implement each step of the quantum walk with some desired accuracy. The difference in complexity for various implementation approaches is that our method scales linearly in the sparsity parameter and poly-logarithmically with the inverse of the desired precision. The best previously known general methods either scale quadratically in the sparsity parameter, or polynomially in the inverse precision. Our approach is especially relevant for implementing quantum walks corresponding to classical random walks like those used in the classical algorithms for approximating permanents [3, 4] and sampling from binary contingency tables [5]. In those algorithms, the sparsity parameter grows with the problem size, while maintaining high precision is required. © Rinton Press.


Janecek S.,Slovak Academy of Sciences | Svensson B.,Technical University of Denmark | MacGregor E.A.,2 Nicklaus Green
Enzyme and Microbial Technology | Year: 2011

Starch-binding domains (SBDs) comprise distinct protein modules that bind starch, glycogen or related carbohydrates and have been classified into different families of carbohydrate-binding modules (CBMs). The present review focuses on SBDs of CBM20 and CBM48 found in amylolytic enzymes from several glycoside hydrolase (GH) families GH13, GH14, GH15, GH31, GH57 and GH77, as well as in a number of regulatory enzymes, e.g., phosphoglucan, water dikinase-3, genethonin-1, laforin, starch-excess protein-4, the β-subunit of AMP-activated protein kinase and its homologues from sucrose non-fermenting-1 protein kinase SNF1 complex, and an adaptor-regulator related to the SNF1/AMPK family, AKINβγ. CBM20s and CBM48s of amylolytic enzymes occur predominantly in the microbial world, whereas the non-amylolytic proteins containing these modules are mostly of plant and animal origin. Comparison of amino acid sequences and tertiary structures of CBM20 and CBM48 reveals the close relatedness of these SBDs and, in some cases, glycogen-binding domains (GBDs). The families CBM20 and CBM48 share both an ancestral form and the mode of starch/glycogen binding at one or two binding sites. Phylogenetic analyses demonstrate that they exhibit independent behaviour, i.e. each family forms its own part in an evolutionary tree, with enzyme specificity (protein function) being well represented within each family. The distinction between CBM20 and CBM48 families is not sharp since there are representatives in both CBM families that possess an intermediate character. These are, for example, CBM20s from hypothetical GH57 amylopullulanase (probably lacking the starch-binding site 2) and CBM48s from the GH13 pullulanase subfamily (probably lacking the starch/glycogen-binding site 1). The knowledge gained concerning the occurrence of these SBDs and GBDs through the range of taxonomy will support future experimental research. © 2011 Elsevier Inc.


Veselsky M.,Slovak Academy of Sciences | Ma Y.G.,CAS Shanghai Institute of Applied Physics
Physical Review C - Nuclear Physics | Year: 2013

The extension of the Boltzmann-Uehling-Uhlenbeck model of nucleus-nucleus collision is presented. The isospin-dependent nucleon-nucleon cross sections are estimated using the proper volume extracted from the equation of state of the nuclear matter transformed into the form of the Van der Waals equation of state. The results of such simulations demonstrate the dependence on symmetry energy, which typically varies strongly from the results obtained using only the isospin-dependent mean field. The evolution of the n/p multiplicity ratio with angle and kinetic energy, in combination with the elliptic flow of neutrons and protons, provides a suitable set of observables for determination of the density dependence of the symmetry energy. The model thus provides an environment for testing of equations of state that are used for various applications in nuclear physics and astrophysics. © 2013 American Physical Society.


Hajduch M.,Slovak Academy of Sciences | Matusova R.,Slovak Academy of Sciences | Houston N.L.,University of Missouri | Thelen J.J.,University of Missouri
Proteomics | Year: 2011

Proteomics is increasingly being used to understand enzyme expression and regulatory mechanisms involved in the accumulation of storage reserves in crops with sequenced genomes. During the past six years, considerable progress has been made to characterize proteomes of both mature and developing seeds, particularly oilseeds - plants which accumulate principally oil and protein as storage reserves. This review summarizes the emerging proteomics data, with emphasis on seed filling in soy, rapeseed, castor and Arabidopsis as each of these oilseeds were analyzed using very similar proteomic strategies. These parallel studies provide a comprehensive view of source-sink relationships, specifically sucrose assimilation into organic acid intermediates for de novo amino acid and fatty acid synthesis. We map these biochemical processes for seed maturation and illustrate the differences and similarities among the four oilseeds. For example, while the four oilseeds appear capable of producing cytosolic phosphoenolpyruvate as the principal carbon intermediate, soybean and castor also express malic enzymes and malate dehydrogenase, together capable of producing malate that has been previously proposed to be the major intermediate for fatty acid synthesis in castor. We discuss these and other differences in the context of intermediary metabolism for developing oilseeds. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Miernyk J.A.,University of Missouri | Hajduch M.,Slovak Academy of Sciences
Journal of Proteomics | Year: 2011

Seeds comprise a protective covering, a small embryonic plant, and a nutrient-storage organ. Seeds are protein-rich, and have been the subject of many mass spectrometry-based analyses. Seed storage proteins (SSP), which are transient depots for reduced nitrogen, have been studied for decades by cell biologists, and many of the complicated aspects of their processing, assembly, and compartmentation are now well understood. Unfortunately, the abundance and complexity of the SSP requires that they be avoided or removed prior to gel-based analysis of non-SSP. While much of the extant data from MS-based proteomic analysis of seeds is descriptive, it has nevertheless provided a preliminary metabolic picture explaining much of their biology. Contemporary studies are moving more toward analysis of protein interactions and posttranslational modifications, and functions of metabolic networks. Many aspects of the biology of seeds make then an attractive platform for heterologous protein expression. Herein we present a broad review of the results from the proteomic studies of seeds, and speculate on a potential future research directions. © 2010 Elsevier B.V.


Borko L.,Slovak Academy of Sciences | Bauerova-Hlinkova V.,Slovak Academy of Sciences | Hostinova E.,Slovak Academy of Sciences | Gasperik J.,Slovak Academy of Sciences | And 4 more authors.
Acta Crystallographica Section D: Biological Crystallography | Year: 2014

Human ryanodine receptor 2 (hRyR2) mediates calcium release from the sarcoplasmic reticulum, enabling cardiomyocyte contraction. The N-terminal region of hRyR2 (amino acids 1-606) is the target of >30 arrhythmogenic mutations and contains a binding site for phosphoprotein phosphatase 1. Here, the solution and crystal structures determined under near-physiological conditions, as well as a homology model of the hRyR2 N-terminal region, are presented. The N-terminus is held together by a unique network of interactions among its three domains, A, B and C, in which the central helix (amino acids 410-437) plays a prominent stabilizing role. Importantly, the anion-binding site reported for the mouse RyR2 N-terminal region is notably absent from the human RyR2. The structure concurs with the differential stability of arrhythmogenic mutations in the central helix (R420W, I419F and I419F/R420W) which are owing to disparities in the propensity of mutated residues to form energetically favourable or unfavourable contacts. In solution, the N-terminus adopts a globular shape with a prominent tail that is likely to involve residues 545-606, which are unresolved in the crystal structure. Docking the N-terminal domains into cryo-electron microscopy maps of the closed and open RyR1 conformations reveals Cα atom movements of up to 8 Å upon channel gating, and predicts the location of the leucine-isoleucine zipper segment and the interaction site for spinophilin and phosphoprotein phosphatase 1 on the RyR surface.


Tomasovych A.,Slovak Academy of Sciences | Kidwell S.M.,University of Chicago | Barber R.F.,University of Chicago | Kaufman D.S.,Northern Arizona University
Geology | Year: 2014

Shells in modern seabeds can be thousands of years old, far older than would be extrapolated from the rapid rates of shell loss detected in short-term experiments. An extensive shelldating program on the Southern California (USA) shelf permits rigorous modeling of the dynamics of shell loss in the mixed layer, discriminating the key rates of carbonate disintegration and sequestration for the first time. We find that bivalve shells experience an initially high disintegration rate λ1 (~ decadal half-lives) but shift abruptly, within the first ~500 yr postmortem, to a 100-fold lower disintegration rate λ2 (~ millennial half-lives) at sequestration rate τ (burial and/or diagenetic stabilization). This drop permits accrual of a long tail of very old shells even when sequestration is very slow, and allows only a minority (<1%) of all shells to survive the first phase. These high rates of disintegration and low rates of sequestration are consistent with independent measures of high carbonate loss and slow sedimentation on this shelf. Our two-phase model thus reveals significant spatial and temporal partitioning of carbonate loss rates within the mixed layer, and shows how shell age-frequency distributions can yield rigorous and realistic estimates of carbonate recycling on geological time scales. © 2014 Geological Society of America.


Bezak P.,Slovak Academy of Sciences | Mitchley J.,University of Reading
Regional Environmental Change | Year: 2014

The transformations in Slovak agriculture from the 1950s to the present day, considering both the generic (National and EU) and site-specific (local) drivers of landscape change, were analysed in five mountain study areas in the country. An interdisciplinary approach included analysis of population trends, evaluation of land use and landscape change combined with exploration of the perceptions of local stakeholders and results of previous biodiversity studies. The generic processes active from the 1950s to 1970s were critical for all study areas with impacts lasting right up until the present day. Agricultural collectivisation, agricultural intensification and land abandonment had negative effects in all study areas. However, the precise impacts on the landscape were different in the different study areas due to site-specific attributes (e.g. population trends, geographic localisation and local attitudes and opportunities), and these played a decisive role in determining the trajectory of change. Regional contrasts in rural development between these territories have increased in the last two decades, also due to the im