University of Gdask
University of Gdask
Brzychczy S.,AGH University of Science and Technology |
Leszczyski H.,University of Gdask |
Journal of Integrative Neuroscience | Year: 2012
Application of comparison theorem is used to examine the validitiy of the "lumped parameter assumption" in describing the behavior of solutions of the continuous cable equation Ut = DUxx+f(U) with the discrete cable equation dVn/dt = d*(Vn+1 - 2V n + Vn-1) + f(Vn), where f is a nonlinear functional describing the internal diffusion of electrical potential in single neurons. While the discrete cable equation looks like a finite difference approximation of the continuous cable equation, solutions of the two reveal significantly different behavior which imply that the compartmental models (spiking neurons) are poor quantifiers of neurons, contrary to what is commonly accepted in computational neuroscience. © 2012 Imperial College Press.
Linde B.B.J.,University of Gdask |
Rosenfeld E.,Merseburg University of Applied Sciences
Journal of the Acoustical Society of America | Year: 2011
Similarities and differences in vibrational behavior of two guitars having a symmetric Torres bracing pattern and an asymmetric pattern forming a lattice on a soundboard are investigated by means of the modal analysis technique and laser Doppler vibrometry (LDV) measurements. Instruments are investigated before and after a bridge and strings assembling (i.e., they are incomplete or complete). The bracing pattern and the absence/presence of the bridge and strings have some effect on modal frequencies and mode shapes. The bracing pattern does not affect the sequence of at least first three low frequency mode shapes of incomplete/complete instruments but affects their modal frequencies. Depending on frequency, the bridge behaves either as a rigid or a flexible structure. © 2011 Acoustical Society of America.
Jozefowicz M.,University of Gdask
Optics and Spectroscopy (English translation of Optika i Spektroskopiya) | Year: 2011
Spectral changes of ethyl 5-(4-aminophenyl)-3-amino-2,4-dicyanobenzoate (EAADCy), observed as a function of solute concentration, external quenching by aniline (one of the fragments of the investigated molecule), and temperature, were interpreted in terms of the selective quenching of different EAADCy conformers. It was shown that molecules with the donor and acceptor moieties oriented orthogo nally are considerable more self and external quenched than the coplanar conformers. On the other hand, results of performed studies indicate that in the studied system static (mainly) and dynamic processes of quenching take place. © Pleiades Publishing, Ltd., 2011.
Grinberg M.,University of Gdask
Journal of Luminescence | Year: 2011
Emission related to rare earth ions in solids takes place usually due to 4fn→4fn and 4fn-15d1→ 4fn internal transitions. In the case of band to band excitation the effective energy transfer from the host to optically active impurity is required. Among other processes one of the possibilities is capturing of the electron at the excited state and the hole at the ground state of impurity. The latest results on high pressure investigations of luminescence related to Pr3+ and Eu2 in different lattices are briefly reviewed. The influence of pressure on anomalous luminescence and 4fn-15d 1→4fn luminescence in BaSrF2:Eu 2 and LiBaF3:Eu2 systems and Pr3+ 4fn→4fn emission quenching is presented and discussed. A theoretical model describing the impurity-trapped exciton as a system where a hole is localized at the impurity and an electron is captured by Coulomb potential at Rydberg-like states is developed. The results show the importance of local lattice relaxation for the creation of stable impurity-trapped exciton states. The ligands shifts create a potential barrier that controls the effect of mixing between the Rydberg-like electron and localized electron wave functions. © 2010 Elsevier B.V. All rights reserved.
Sieradzan I.,University of Gdask |
Anusiewicz I.,University of Gdask
Journal of Chemical Physics | Year: 2013
The properties of AA-Y- anions (where AA = cysteine, aspartic acid, lysine; Y=BF3, PF5) were investigated at the ab initio Outer Valence Greens Function (OVGF)/6-311++G(3df,3pd)//MP2/6-311++G(d,p) level of theory. It is shown that introducing a superhalogen-like substituent to an amino acid (i.e., Cys, Asp, and Lys) results in obtaining molecules that bind an excess electron relatively strongly. The electronic stabilities of such resulting daughter anions are predicted to be substantial (5.3-6.9 eV). © 2013 American Institute of Physics.
Stempniewicz L.,University of Gdask |
Iliszko L.,University of Gdask
Arctic | Year: 2010
Observations were made of glaucous gulls (Larus hyperboreus) stealing little auks (Alle alle) stored in a den by arctic foxes (Vulpes lagopus) in Magdalenefjorden, northwest Spitsbergen. Before stealing the spoil, the gulls observed and followed foxes transporting little auks hunted in a nearby colony. Skill in detecting and successfully taking over the food cached by arctic foxes may help glaucous gulls to survive critical periods of lowered prey availability and enhanced energy demands, such as the little auk incubation period, when the auks are well hidden in the nests and inaccessible for gulls feeding their own large nestlings. These observations are the first documented instances of the glaucous gulls kleptoparasiting arctic foxes and provide additional evidence of the complex nature of interactions occurring between these two opportunistic Arctic predators. © The Arctic Institute of North America.
Alicki R.,University of Gdask |
Alicki R.,Weizmann Institute of Science
Open Systems and Information Dynamics | Year: 2012
It is argued using a Gedankenexperiment that a scalable quantum memory could be used as a perpetuum mobile of the second kind and hence cannot be realized in nature. The reasoning is based on the assumption that the Landauer's principle for measurements is a consequence of the second law of thermodynamics and not an independent postulate. This implies a modification of the Landauer's principle when applied for discrimination of equilibrium (metastable) states. While identification of the metastable state can be done at infinitesimally low cost, any change of such state involves dissipation of energy proportional to its stability factor. © 2012 World Scientific Publishing Company.
Czarnota P.,University of Rzeszow |
Czarnota P.,Scientific Laboratory of the Gorce National Park |
Guzow-Krzeminska B.,University of Gdask
Lichenologist | Year: 2010
The phylogeny of the Micarea prasina group was investigated using mitochondrial small subunit ribosomal DNA sequences from 14 taxa representing this group, four other members of the genus Micarea, and Psilolechia lucida as an outgroup. A total of 31 new mtSSU rDNA sequences were generated, including 10 from the M. micrococca complex. Bayesian, maximum parsimony (MP) and maximum likelihood (ML) methods were used to analyse the data. The results show that M. micrococca is not monophyletic and forms three strongly supported lineages: 1) M. micrococca s. str., 2) M. byssacea (Th. Fr.) Czarnota, Guzow-Krzemiska & Coppins comb. nov., and 3) a putative taxon that requires further studies. Micarea viridileprosa is a sister species to M. micrococca s. str. and the recently described M. nowakii is a sister species to M. prasina s. str. The placement of M. tomentosa within the M. prasina group is confirmed. Micarea hedlundii appears to be more closely related to the M. micrococca complex than M. prasina s. str. Descriptions, illustrations, taxonomic remarks, distribution and habitat data for M. micrococca s. str. and M. byssacea are provided. A lectotype for Biatora byssacea Hampe non Zwackh and a neotype for Catillaria prasina [var.] byssacea are selected. © 2009 British Lichen Society.
Mahlik S.,University of Gdask |
Lazarowska A.,University of Gdask |
Grobelna B.,University of Gdask |
Grinberg M.,University of Gdask
Journal of Physics Condensed Matter | Year: 2012
This paper presents a spectroscopic characterization of Gd 2(WO 4) 3:Ln 3+ (Ln=Eu, Pr, Tb and Dy). The luminescence and luminescence kinetics were measured under pressures up to 250kbar. It was found that pressure quenches the luminescence of Pr 3+ and Tb 3+, whereas the emission of Eu 3+ and Dy 3+ was stable up to 250kbar. This effect was related to a decrease in the ionization energy of Pr 3+ and Tb 3+ caused by pressure induced increase in energies of the Ln 2+ and Ln 3+ ions with respect to the band edges. Analysis of emission and excitation spectra allowed us to estimate the energies of the ground states of Ln 3+ and Ln 2+ with respect to the valence and conduction band edges of the Gd 2 (WO 4) 3 host. Differences between energies of the ground states of Ln 2+ and Ln 3+ have also been calculated. © 2012 IOP Publishing Ltd.
Alicki R.,University of Gdask |
Miklaszewski W.,University of Gdask
Journal of Chemical Physics | Year: 2012
The Wigner-Weisskopf-type model developed by Alicki and Giraldi [J. Phys. B 44, 154020 (2011)]10.1088/0953-4075/44/15/154020 is applied to the biological process of energy transfer from a large peripheral light harvesting antenna to the reaction center. This process is mediated by the Fenna-Matthews-Olson (FMO) photosynthetic complex with a remarkably high efficiency. The proposed model provides a simple resonance mechanism of this phenomenon employing exciton coherent motion and is described by analytical formulas. A coupling to the vibrational environment is a necessary component of this mechanism as well as a fine-tuning of the FMO complex Hamiltonian. The role of the relatively strong coupling to the energy sink in achieving the resonance condition and the absence of heating of the vibrational environment are emphasized. © 2012 American Institute of Physics.