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Amsterdam, Netherlands

The University of Amsterdam or UvA is a public university located in Amsterdam, Netherlands. Established in 1632 by municipal authorities and later renamed for the city of Amsterdam, the University of Amsterdam is the third-oldest university in the Netherlands. It is one of the largest research universities in Europe with 29,783 students, 4,629 staff, and an endowment of €613.5 million. It is the largest university in the Netherlands by enrollment and has the second-largest university endowment in the country. The main campus is located in central Amsterdam, with a few faculties located in adjacent boroughs. The university is organised into seven faculties: Humanities, Social and Behavioural science, Economics and Business, Science, Law, Medicine, and Dentistry. The University of Amsterdam has produced six Nobel Laureates and five prime ministers of the Netherlands. In 2013, it was ranked 58th in the world, 17th in Europe, and 1st in the Netherlands by the QS World University Rankings. The university placed in the top 50 worldwide in seven fields in the 2011 QS World University Rankings in the fields of Linguistics, Sociology, Philosophy, Geography, Science, Economics & Econometrics, and Accountancy & Finance.The University of Amsterdam is a member of the League of European Research Universities , the Institutional Network of the Universities from the Capitals of Europe , European University Association , and Universitas 21. Wikipedia.


Berkhout B.,University of Amsterdam
Expert Opinion on Biological Therapy | Year: 2012

Introduction: An effective vaccine that can protect people against infection of the human immunodeficiency virus type 1 (HIV-1) remains elusive. HIV-1 vaccine research has encountered several false starts and a few causes for hope over the last 28 years, but no real success stories. Thus, it is time to think out of the box and design and test unorthodox vaccination strategies. Areas covered: Recent studies in mice and monkeys have revealed the potential of a gene therapy that provides vaccine-like protection against HIV-1 infection by producing a potent vector-encoded antibody that neutralizes the invading viruses. This novel strategy is called Vectored Immuno Prophylaxis or VIP, and it circumvents the sometimes difficult phases of regular vaccination protocols, that is, antigen design and induction of protective immune responses. Expert opinion: VIP is a prolonged form of passive immunization by means of a gene therapy. We will discuss the ins and outs of VIP and the therapeutic possibilities and challenges. © 2012 Informa UK, Ltd. Source


Slagter H.A.,University of Amsterdam | Davidson R.J.,University of Wisconsin - Madison | Lutz A.,University of Wisconsin - Madison
Frontiers in Human Neuroscience | Year: 2011

Although the adult brain was once seen as a rather static organ, it is now clear that the organization of brain circuitry is constantly changing as a function of experience or learning. Yet, research also shows that learning is often specific to the trained stimuli and task, and does not improve performance on novel tasks, even very similar ones. This perspective examines the idea that systematic mental training, as cultivated by meditation, can induce learning that is not stimulus or task specific, but process specific. Many meditation practices are explicitly designed to enhance specific, well-defined core cognitive processes. We will argue that this focus on enhancing core cognitive processes, as well as several general characteristics of meditation regimens, may specifically foster process-specific learning. To this end, we first define meditation and discuss key findings from recent neuroimaging studies of meditation. We then identify several characteristics of specific meditation training regimes that may determine process-specific learning. These characteristics include ongoing variability in stimulus input, the meta-cognitive nature of the processes trained, task difficulty, the focus on maintaining an optimal level of arousal, and the duration of training. Lastly, we discuss the methodological challenges that researchers face when attempting to control or characterize the multiple factors that may underlie meditation training effects. © 2011 Slagter, Davidson and Lutz. Source


Aalbers M.B.,University of Amsterdam
Antipode | Year: 2011

Although planned as the "City of Tomorrow", the Bijlmer district in Amsterdam quickly became the quintessential symbol of urban decline. Today, even with half of the planned renewal of the Bijlmer completed, the alleged success of this urban revitalisation programme is questionable. Parts of the black middle class did not move out and some are even returning to the Bijlmer; the combination is producing a type of "black gentrification", which forces the "undesirables" like drug users, homeless people and undocumented immigrants to leave. This revanchist renewal not only benefits the middle and lower-class population of the district, but it also serves the interests of private developers. European revanchism makes the city safe for corporate investment and aims to restore social order as well as stimulating the development of a strong middle class. This paper demonstrates how hard revanchist policies are demanded not only by private developers but also by the middle and lower classes, and they exist alongside soft "caring" policies, even for the "undesirables". © 2010 The Author Journal compilation © 2010 Editorial Board of Antipode. Source


Lapid O.,University of Amsterdam
Aesthetic Plastic Surgery | Year: 2011

A simple method for the infiltration of tumescent anesthesia is presented. An assembly is made using an infusion set, a three-way tap, and two unidirectional valves. The assembly and use of this system are straightforward and easy. The addition of unidirectional valves prevents the risk of reverse injection or aspiration of fluid from the patient. © The Author(s) 2010. Source


Levi M.,University of Amsterdam | Levy J.H.,Emory University | Andersen H.F.,Novo Nordisk AS | Truloff D.,Novo Nordisk AS
New England Journal of Medicine | Year: 2010

BACKGROUND: The use of recombinant activated factor VII (rFVIIa) on an off-label basis to treat life-threatening bleeding has been associated with a perceived increased risk of thromboembolic complications. However, data from placebo-controlled trials are needed to properly assess the thromboembolic risk. To address this issue, we evaluated the rate of thromboembolic events in all published randomized, placebo-controlled trials of rFVIIa used on an off-label basis. METHODS: We analyzed data from 35 randomized clinical trials (26 studies involving patients and 9 studies involving healthy volunteers) to determine the frequency of thromboembolic events. The data were pooled with the use of random-effects models to calculate the odds ratios and 95% confidence intervals. RESULTS: Among 4468 subjects (4119 patients and 349 healthy volunteers), 498 had thromboembolic events (11.1%). Rates of arterial thromboembolic events among all 4468 subjects were higher among those who received rFVIIa than among those who received placebo (5.5% vs. 3.2%, P = 0.003). Rates of venous thromboembolic events were similar among subjects who received rFVIIa and those who received placebo (5.3% vs. 5.7%). Among subjects who received rFVIIa, 2.9% had coronary arterial thromboembolic events, as compared with 1.1% of those who received placebo (P = 0.002). Rates of arterial thromboembolic events were higher among subjects who received rFVIIa than among subjects who received placebo, particularly among those who were 65 years of age or older (9.0% vs. 3.8%, P = 0.003); the rates were especially high among subjects 75 years of age or older (10.8% vs. 4.1%, P = 0.02). CONCLUSIONS: In a large and comprehensive cohort of persons in placebo-controlled trials of rFVIIa, treatment with high doses of rFVIIa on an off-label basis significantly increased the risk of arterial but not venous thromboembolic events, especially among the elderly. (Funded by Novo Nordisk.) Copyright © 2010 Massachusetts Medical Society. Source


Bornmann L.,Max Planck Innovation | Leydesdorff L.,University of Amsterdam
Journal of Informetrics | Year: 2013

The data of F1000 and InCites provide us with the unique opportunity to investigate the relationship between peers' ratings and bibliometric metrics on a broad and comprehensive data set with high-quality ratings. F1000 is a post-publication peer review system of the biomedical literature. The comparison of metrics with peer evaluation has been widely acknowledged as a way of validating metrics. Based on the seven indicators offered by InCites, we analyzed the validity of raw citation counts (Times Cited, 2nd Generation Citations, and 2nd Generation Citations per Citing Document), normalized indicators (Journal Actual/Expected Citations, Category Actual/Expected Citations, and Percentile in Subject Area), and a journal based indicator (Journal Impact Factor). The data set consists of 125 papers published in 2008 and belonging to the subject category cell biology or immunology. As the results show, Percentile in Subject Area achieves the highest correlation with F1000 ratings; we can assert that for further three other indicators (Times Cited, 2nd Generation Citations, and Category Actual/Expected Citations) the "true" correlation with the ratings reaches at least a medium effect size. © 2012 Elsevier Ltd. Source


Levi M.,University of Amsterdam
Seminars in Thrombosis and Hemostasis | Year: 2012

Pharmacological prohemostatic agents may be useful adjunctive treatment options in patients with severe blood loss. The efficacy of these interventions has been established in a variety of clinical situations. However, the procoagulant effect of these interventions may tip the balance toward a higher risk of thrombotic complications. Several studies have shown that some prohemostatic interventions may indeed increase the risk of arterial and venous thromboembolism, although these complications are relatively rare. When considering the use of adjunctive prohemostatic agents to prevent or treat excessive blood loss, the risk of thrombotic complications should be taken into account. Copyright © 2012 by Thieme Medical Publishers, Inc. Source


Bornmann L.,Max Planck Innovation | Leydesdorff L.,University of Amsterdam | Mutz R.,ETH Zurich
Journal of Informetrics | Year: 2013

Percentiles have been established in bibliometrics as an important alternative to mean-based indicators for obtaining a normalized citation impact of publications. Percentiles have a number of advantages over standard bibliometric indicators used frequently: for example, their calculation is not based on the arithmetic mean which should not be used for skewed bibliometric data. This study describes the opportunities and limits and the advantages and disadvantages of using percentiles in bibliometrics. We also address problems in the calculation of percentiles and percentile rank classes for which there is not (yet) a satisfactory solution. It will be hard to compare the results of different percentile-based studies with each other unless it is clear that the studies were done with the same choices for percentile calculation and rank assignment. © 2012 Elsevier Ltd. Source


Kolk A.,University of Amsterdam
Corporate Social Responsibility and Environmental Management | Year: 2012

This paper examines the case of sustainable coffee as faced by Sara Lee's International Coffee and Tea Division (SL), asking which strategic direction the company should take considering its regulatory, competitive, and societal contexts. More than a decade after sustainable coffee became a strategic issue for SL, emerging public purchasing guidelines seem to exclude the 'mainstream-market' policy of the company and instead favour the Fairtrade standard that embodies a niche approach. The case presents the strategic, organisational, and marketing dimensions, in their international supply-chain and industry dynamics. It raises the question what it means for a large, mainstream, multinational company to move to sustainability when the issues at hand are very complex, when consumer awareness is limited, and when the market for sustainable coffee is not yet mature. Several strategic options are presented, each with their pros and cons, as input for further discussion and research on the paradoxes related to sustainability and international business. © 2012 John Wiley & Sons, Ltd and ERP Environment. Source


Blessing A.,University of Amsterdam
Housing Studies | Year: 2012

While a growing number of national social housing strategies rely on the work of hybrid entities blending social and commercial tasks, the state/market dualism continues to dominate the conceptual landscape of housing research. This exploratory paper develops a conceptual approach to support research into the role of not-for-profit social entrepreneurs in the housing market. It looks for insights within their 'hybrid' status, spanning state and market, and subject to multiple sets of institutional conditions. Four frames of hybrid identity are developed, and then substantiated via a discussion of two different sectors of not-for-profit social entrepreneurs in Australia and the Netherlands. As the growth trajectory of each sector is traced and the construction of hybrid identity is explored from both public and private perspectives, institutional pressures are revealed that set the current context for development. This brings forth implications for existing conceptual tools, as well as directions for new research. © 2012 Copyright Taylor and Francis Group, LLC. Source


Boterman W.R.,University of Amsterdam
Environment and Planning A | Year: 2012

There is common understanding that gentrifiers and new middle classes more generally share an urban orientation and may share a 'metropolitan habitus'. The urban geography of Western metropolises and the formation and reproduction of specific middle-class groups are intrinsically connected. The specific urban habitus of these new middle classes, however, is challenged by events in the life course. When urban middle classes settle down and have children, many suburbanise. Using two waves of longitudinal data from a representative sample of middle-class couples expecting their first child, this study investigates the residential practices of middle classes that live in the central areas of Amsterdam when they become first-time parents. Building on prior work on urban middle classes, inspired by the theoretical concepts of Bourdieu, through a multilevel analysis, this study seeks to understand how various orientations of capital influence the decision whether to stay in the city or move to suburban areas. Controlling for a range of individual and neighbourhood variables, this study demonstrates that couples with high economic capital and relatively low cultural capital have a higher propensity to move out of the central city, whereas couples with high cultural capital and low economic capital have a smaller chance of suburbanising. Furthermore, this study confirms that the degree of social and economic connectedness through social networks and work in the city also play an important part in determining the propensity to move out of the city. © 2012 Pion and its Licensors. Source


To determine the ability of optical coherence tomography (OCT) in differentiating human renal tumours in an in-vivo setting by assessing differences in attenuation coefficient (μ(OCT); mm(-1)) as a quantitative measurement. Consecutive patients undergoing nephrectomy (partial/radical) or cryoablation for an enhancing solid renal tumour were included in our centre between October 2010 and May 2011. In vivo OCT images were obtained from renal tumour and normal parenchyma during surgery. Ex vivo OCT images of internal (subcapsular) tissue were obtained after longitudinal dissection of the extirpated specimen. Attenuation coefficients of the OCT images were determined off-line and compared between normal renal parenchyma and renal tumours (grouped per tissue type and per individual patient); and between OCT images recorded from tissue surface vs internal (subcapsular) tissue. In vivo OCT was performed in 16 cases (11 renal cell carcinoma, three benign tumours, one non-diagnostic biopsy and one not-accessible tumour). Median attenuation coefficient of normal renal parenchyma was 5.0 mm(-1) vs 8.2 mm(-1) for tumour tissue (P < 0.001) with normal parenchyma differing significantly from malignant tumour (9.2 mm(-1), P < 0.001) and non-significantly from benign tumour (7.0 mm(-1), P = 0.050). The attenuation coefficient of benign tumours did not differ significantly from that of malignant tumours (7.0 vs 9.2 mm(-1), P = 0.139). Using patients as their own control, attenuation coefficients of normal renal parenchyma differed significantly from malignant tumour (P < 0.001) and non-significantly from benign tumour (P = 0.109). Assessed in 10 patients, there was no significant difference between attenuation coefficients of tumour surface and internal tumour (8.5 vs 9.7 mm(-1) respectively, P = 0.260). In this first in vivo study on OCT for differentiation of renal tumours in humans the attenuation coefficients (as a quantitative assessment) differed significantly between normal renal parenchyma and malignant tumour. Tumour surface and internal tumour did not differ significantly, suggesting that a superficial OCT attenuation coefficient reliably assesses tissue composition inside the tumour. These results justify further research on OCT for various clinical applications in the diagnosis of renal tumours. © 2012 THE AUTHORS. BJU INTERNATIONAL © 2012 BJU INTERNATIONAL. Source


van den Berg M.,University of Amsterdam
Urban Studies | Year: 2012

Rotterdam organised the festival 'La City' as an entrepreneurial strategy to upgrade the city's class position, using femininity as a tool. 'La City' was an attempt to introduce a new economy in Rotterdam: one that is service-based and post-industrial. Rotterdam is a former industrial city and is now trying to establish a new economy and a new spatial organisation. In this article, 'La City' campaign material, texts on the character of the city and interviews in local newspapers with policy-makers are analysed in the context of the urban renewal and gentrification policies of Rotterdam. This research shows how the city uses femininity as a marketing strategy to 'cleanse' Rotterdam of its working-class mythology as well as construing a hegemonic gender identity capable of excluding lower-class groups. Rotterdam, according to its own texts, is after bourgeois, feminine inhabitants that 'lounge' in 'cocktail bars' to replace the 'rough' men who worked in the harbour. 'La City' is one of many strategies to establish genderfication: the production of space for not only more affluent users (as gentrification is often defined), but also for specific gender notions. Genderfication is also established by practices of 'mixing' urban neighbourhoods and building homes for middle-class families. © 2011 Urban Studies Journal Limited. Source


Laloy E.,University of California at Irvine | Vrugt J.A.,University of California at Irvine | Vrugt J.A.,University of Amsterdam
Water Resources Research | Year: 2012

Spatially distributed hydrologic models are increasingly being used to study and predict soil moisture flow, groundwater recharge, surface runoff, and river discharge. The usefulness and applicability of such complex models is increasingly held back by the potentially many hundreds (thousands) of parameters that require calibration against some historical record of data. The current generation of search and optimization algorithms is typically not powerful enough to deal with a very large number of variables and summarize parameter and predictive uncertainty. We have previously presented a general-purpose Markov chain Monte Carlo (MCMC) algorithm for Bayesian inference of the posterior probability density function of hydrologic model parameters. This method, entitled differential evolution adaptive Metropolis (DREAM), runs multiple different Markov chains in parallel and uses a discrete proposal distribution to evolve the sampler to the posterior distribution. The DREAM approach maintains detailed balance and shows excellent performance on complex, multimodal search problems. Here we present our latest algorithmic developments and introduce MT-DREAM (ZS), which combines the strengths of multiple-try sampling, snooker updating, and sampling from an archive of past states. This new code is especially designed to solve high-dimensional search problems and receives particularly spectacular performance improvement over other adaptive MCMC approaches when using distributed computing. Four different case studies with increasing dimensionality up to 241 parameters are used to illustrate the advantages of MT-DREAM (ZS). Copyright 2012 by the American Geophysical Union. Source


In the global debate on sustainable development, there appears to be a growing recognition of the crucial importance of worldviews vis-à-vis the urgently needed transition to an ecological economy and society. This study therefore aims to support (survey) research exploring worldviews and their complex relationships to sustainable lifestyles. I do this by analyzing and critically challenging existing measures such as the New Environmental Paradigm, and by developing a new conceptual and methodological approach. First, a review of multiple survey-approaches, stemming from different disciplinary and theoretical traditions, is conducted. This results in a meta-analysis of their strengths and weaknesses. On this basis it is concluded that a more optimal approach should be comprehensive and systematic, measure structural worldview-beliefs, and be able to account for human and cultural development. Then, the Integrative Worldview Framework (IWF) is proposed in order to support such a systematic, comprehensive, structural, and dynamic operationalization of the worldview-construct. In this way, a conceptually and methodologically innovative approach to exploring worldviews and their relationship to sustainable behaviors is developed. © 2012 Elsevier B.V. Source


Wilde A.A.M.,University of Amsterdam | Behr E.R.,St Georges, University of London
Nature Reviews Cardiology | Year: 2013

Over the past 2 decades, investigators in the field of cardiac genetics have evolved a complex understanding of the pathophysiological basis of inherited cardiac diseases, which predispose individuals to sudden cardiac death. In this Review, we describe the current status of gene discovery and the associations between phenotype and genotype in the cardiac channelopathies and cardiomyopathies. The various indications for genetic testing and its utility in the clinic are assessed in relation to diagnosis, cascade testing, guiding management, and prognosis. Some common problems exist across all phenotypes: the variable penetrance and expressivity of genetic disease, and the difficulty of assessing the functional and clinical effects of novel mutations. These issues will be of particular importance as the next-generation sequencing technologies are used by genetics laboratories to provide results from large panels of genes. The accurate interpretation of these results will be the main challenge for the future. © 2013 Macmillan Publishers Limited. All rights reserved. Source


Rep M.,University of Amsterdam | Kistler H.C.,University of Minnesota
Current Opinion in Plant Biology | Year: 2010

Comparative genomics is a powerful tool to infer the molecular basis of fungal pathogenicity and its evolution by identifying differences in gene content and genomic organization between fungi with different hosts or modes of infection. Through comparative analysis, pathogenicity-related chromosomes have been identified in Fusarium oxysporum and Fusarium solani that contain genes for host-specific virulence. Lateral transfer of pathogenicity chromosomes, inferred from genomic data, now has been experimentally confirmed. Likewise, comparative genomics reveals the evolutionary relationships among toxin gene clusters whereby the loss and gain of genes from the cluster may be understood in an evolutionary context of toxin diversification. The genomic milieu of effector genes, encoding small secreted proteins, also suggests mechanisms that promote genetic diversification for the benefit of the pathogen. © 2010. Source


Alkemade A.,University of Amsterdam
Journal of Neuroendocrinology | Year: 2010

Increasing evidence points towards a role for thyroid hormone signalling in the central nervous system with respect to the development of symptoms of thyroid disease, in addition to the well-known peripheral effects of thyroid hormone. Thyroid hormone affects target tissues directly via thyroid hormone receptors, but also indirectly through effects on the integration of the sympathetic signal in target tissues. The present review discusses these pathways and the evidence for a third pathway, that is effects of thyroid hormone on the pre-autonomic neurones in the central nervous system. The pre-autonomic neurones reside in the hypothalamus in brain nuclei such as the paraventricular nucleus of the hypothalamus where thyroid hormone receptor isoforms are expressed. Recent data from studies in transgenic mice implicate a role for thyroid hormone receptor alpha 1 in the modulation of sympathetic signalling to target tissues, thereby affecting both glucose and lipid metabolism. Focal stimulation of hypothalamic nuclei expressing thyroid hormone receptors and selective liver denervation experiments in rats have provided further evidence indicating that the metabolic changes observed during hyperthyroidism are not only a result of increased thyroid hormone signalling in the periphery, but also, at least in part, result from altered signalling in thyroid hormone sensitive neurones. © 2009 The Author. Journal Compilation © 2009 Blackwell Publishing Ltd. Source


Innate lymphoid cells (ILCs) are novel players in innate immunity. Tumanov et al. (Tumanov et al., 2011) demonstrate that crosstalk between ILCs and dendritic cells involving membrane-bound lymphotoxin in ILCs and its receptor is critical for protection against colitogenic bacteria. © 2011 Elsevier Inc. Source


Cohen M.X.,University of Amsterdam
Trends in neurosciences | Year: 2014

During human response conflict - competition between multiple conflicting actions when a mistake could be made - a specific pattern of brain electrical activity occurs over the medial frontal cortex (MFC), characterized by modulations of ongoing theta-band (∼6Hz) oscillations and synchronization with task-relevant brain regions. Despite the replicable and robust findings linking MFC theta to conflict processing, the significance of MFC theta for how neural microcircuits actually detect conflict and broadcast that signal is unknown. A neural MFC microcircuit model is proposed for processing conflict and generating theta oscillations. The model makes several novel predictions for the causes and consequences of MFC theta and conflict processing, and may be relevant for understanding the neural implementations of related cognitive processes. Copyright © 2014 Elsevier Ltd. All rights reserved. Source


Strahl H.,Newcastle University | Hamoen L.W.,Newcastle University | Hamoen L.W.,University of Amsterdam
Current Opinion in Microbiology | Year: 2012

The bacterial cell is well-organized and many proteins are confined to regions such as midcell or cell poles. These areas are not separated from each other by membranes, and therefore bacteria must rely on basic biophysical processes to localize proteins within their cytoplasmic space. The conserved protein DivIVA accumulates at cell poles and cell division sites of Gram-positive bacteria. It turns out that this protein binds specifically to concave membranes. These negatively curved membrane surfaces occur at the base of the cell division septum and the cell poles. How DivIVA recognizes this topological characteristic is yet unclear, but whole-cell Monte-Carlo simulations suggest that a few basic rules can explain why this protein accumulates at negatively curved membranes. © 2012 Elsevier Ltd. Source


Brommelstroet M.T.,University of Amsterdam
Computers, Environment and Urban Systems | Year: 2012

There is a growing body of academic literature that deals with the gap between Planning Support Systems (PSS) and daily urban planning practices. Although there are many theoretical ideas about how to improve this situation, there is only limited academic attention for testing these in real world applications. This article discusses the importance of such testing and how this can be done. Four central PSS hypothesized improvement mechanisms are translated into a grounded intervention and tested in three settings of land use and transport strategy-making in the Netherlands. I utilised workshop specific questionnaires, a general ex-post survey and participatory observation. Although small-N, the results seem to indicate a tentative pattern that the hypothesized improvement mechanisms did improve several of the bottlenecks of PSS implementation defined in other studies: it provided a better fit between the PSS characteristics and the strategy-making processes, it increased understanding of the possibilities (and limitations) of PSS and it fostered acceptance (awareness and transparency were only marginally influenced). Important mechanisms for promoting these outcomes include an open constructive critical attitude of both PSS developers and planners, a prototyping process, and placing emphasis on externalisation and internalisation of knowledge. This research example illustrates both the added value of the findings and the methodological problems of a practice oriented research approach. The paper closes with a discussion on the implications for PSS research methods, PSS development and planning and will provide directions for further research. © 2011 Elsevier Ltd. Source


Parameswaran S.A.,University of California at Berkeley | Turner A.M.,University of Amsterdam | Arovas D.P.,University of California at San Diego | Vishwanath A.,University of California at Berkeley | Vishwanath A.,Lawrence Berkeley National Laboratory
Nature Physics | Year: 2013

Band insulators appear in a crystalline system only when the filling - the number of electrons per unit cell and spin projection - is an integer. At fractional filling, an insulating phase that preserves all symmetries is a Mott insulator; that is, it is either gapless or, if gapped, exhibits fractionalized excitations and topological order. We raise the inverse question - at an integer filling is a band insulator always possible? Here we show that lattice symmetries may forbid a band insulator even at certain integer fillings, if the crystal is non-symmorphic - a property shared by most three-dimensional crystal structures. In these cases, one may infer the existence of topological order if the ground state is gapped and fully symmetric. This is demonstrated using a non-perturbative flux-threading argument, which has immediate applications to quantum spin systems and bosonic insulators in addition to electronic band structures in the absence of spin-orbit interactions. © 2013 Macmillan Publishers Limited. All rights reserved. Source


Caux J.-S.,University of Amsterdam | Konik R.M.,Brookhaven National Laboratory
Physical Review Letters | Year: 2012

Using a numerical renormalization group based on exploiting an underlying exactly solvable nonrelativistic theory, we study the out-of-equilibrium dynamics of a 1D Bose gas (as described by the Lieb-Liniger model) released from a parabolic trap. Our method allows us to track the postquench dynamics of the gas all the way to infinite time. We also exhibit a general construction, applicable to all integrable models, of the thermodynamic ensemble that has been suggested to govern this dynamics, the generalized Gibbs ensemble. We compare the predictions of equilibration from this ensemble against the long time dynamics observed using our method. © 2012 American Physical Society. Source


Heller M.P.,University of Amsterdam | Janik R.A.,Jagiellonian University | Witaszczyk P.,Jagiellonian University
Physical Review Letters | Year: 2012

We report on the approach toward the hydrodynamic regime of boost-invariant N=4 super Yang-Mills plasma at strong coupling starting from various far-from-equilibrium states at τ=0. The results are obtained through a numerical solution of Einstein's equations for the dual geometries, as described in detail in the companion article. Despite the very rich far-from-equilibrium evolution, we find surprising regularities in the form of clear correlations between initial entropy and total produced entropy, as well as between initial entropy and the temperature at thermalization, understood as the transition to a hydrodynamic description. For 29 different initial conditions that we consider, hydrodynamics turns out to be definitely applicable for proper times larger than 0.7 in units of inverse temperature at thermalization. We observe a sizable anisotropy in the energy-momentum tensor at thermalization, which is nevertheless entirely due to hydrodynamic effects. This suggests that effective thermalization in heavy-ion collisions may occur significantly earlier than true thermalization. © 2012 American Physical Society. Source


van der Groep R.,University of Amsterdam
Regional Studies | Year: 2010

'Breaking out' and 'breaking in': changing firm strategies in the Dutch audiovisual industry, Regional Studies. In this article, it is argued that privatization and deregulation processes in the Dutch broadcasting system in 1989 affected the entrepreneurial strategies of audiovisual firms in the municipality of Hilversum (that is, the broadcast town of the Netherlands) in such a way that it caused a radical break in the overall organizational structure of the broadcasting system. Two particular responses of audiovisual firms in Hilversum are reconstructed. First, there are firms with an adaptive strategy that compete on price and focus on cost reduction. However, a second and more innovative strategy is noted as well. This second strategy is found among broadcasters and television producers who started to produce audiovisual content for other media, such as internet firms and cable firms. In addition, alliances were established in this latter group with innovative (audiovisual) firms elsewhere, such as in Amsterdam, the largest audiovisual cluster of the Netherlands, in order to launch new innovative products. Eventually, it seems that Dutch audiovisual broadcasters evolve into Systems Houses, which are large disintegrated conglomerates that produce in small batches in order to realize external economies of scope. It is concluded that the establishment of these inter-cluster partnerships should be interpreted as an interactive learning process to increase their responsiveness focus, which enables Hilversum-based audiovisual firms to deal more effectively with institutional, political or technological changes. © 2010 Regional Studies Association. Source


Kloosterman R.C.,University of Amsterdam
Regional Studies | Year: 2010

Building a career: labour practices and cluster reproduction in Dutch architectural design, Regional Studies. This paper explores how firms and workers deal with the specific characteristics of the labour market in a cutting-edge cultural industry, namely, Dutch architectural design. Based on in-depth interviews with principals, workers, and key informants, the relationship between a logic of economic practice with a logic of artistic practice is investigated. The intertwining of these two practices appears to be a crucial link in the generation of spin-offs in the long run. In this way, the unintended consequences of the motivations and actions on a micro-level foster, on a higher level, the reproduction of the cluster itself. © 2010 Regional Studies Association. Source


Blaauboer M.,University of Amsterdam
Housing Studies | Year: 2010

Homeownership is influenced by resources, household context and characteristics of the family of origin. Using the Netherlands Kinship Panel Study, this paper investigates this influence and to what extent it differs between men and women in couples and between single men and women. The results for couples show that the earning potential of the male partner, indicated by the level of education, is much more important to housing tenure than the earning potential of the female partner, whereas the impact of the current income is similar for both sexes. Single women are less likely to be homeowners than single men. Moreover, the earning potential has a greater effect on homeownership for single men than for single women. Some evidence is also found for a greater effect of the father's socio-economic status on women's than on men's homeownership. © 2010 Taylor & Francis. Source


Reijnders S.,University of Amsterdam
Cultural Geographies | Year: 2010

This article considers the phenomenon of the TV detective tour, guided tours of the locations and settings of popular TV detective programs. What explains the growing popularity of these tours? The article proposes that the locations in question serve as physical points of reference to an imagined world. By visiting these locations and focusing on them, tourists are able to construct and subsequently cross a symbolic boundary between an 'imagined' and a 'real' world. To explain this process, a new concept is introduced: lieux d'imagination. This concept is supported and developed on the basis of ethnographic analysis of three popular TV detective tours: the Inspector Morse Tour in Oxford, the Baantjer Tour in Amsterdam, and the Wallander Tour in Ystad, Sweden. In all, 31 interviews were conducted with tourist office employees, tour guides, local inhabitants, and tourists; these interviews were supplemented with participatory observation. Analysis of interview transcripts and observation records shows that lieux d'imagination result from a complex process of negotiation and appropriation. © The Author(s) 2010. Source


van Gent W.P.C.,University of Amsterdam
Housing Studies | Year: 2010

The housing tenure structure has long been associated with different forms of welfare state capitalism in Western Europe. However, with the rise of owner-occupancy, this association has not been so straightforward. An alternative view is to view housing policies that promote owner-occupancy for households to acquire assets, as an attempt by the state to reform social welfare systems. The politics of welfare reform are related to the discourses of homeownership ideology. The ownership of (housing) assets agenda serves as a means to change the relationship between state, market and individual households. This view is mostly based on the British experience and this paper seeks to broaden it by examining the Netherlands and Spain. The paper shows differences, but also that housing policies play an important role in driving towards or maintaining market-dominated solutions. Housing is used to either reorient towards or maintain a welfare system where asset ownership and market dependency is deemed more appropriate than secure income and public expenditure. © 2010 Taylor & Francis. Source


Van Noorden C.J.F.,University of Amsterdam
Journal of Histochemistry and Cytochemistry | Year: 2010

For the understanding of functions of proteins in biological and pathological processes, reporter molecules such as fluorescent proteins have become indispensable tools for visualizing the location of these proteins in intact animals, tissues, and cells. For enzymes, imaging their activity also provides information on their function or functions, which does not necessarily correlate with their location. Metabolic mapping enables imaging of activity of enzymes. The enzyme under study forms a reaction product that is fluorescent or colored by conversion of either a fluorogenic or chromogenic substrate or a fluorescent substrate with different spectral characteristics. Most chromogenic staining methods were developed in the latter half of the twentieth century but still find new applications in modern cell biology and pathology. Fluorescence methods have rapidly evolved during the last decade. This review critically evaluates the methods that are available at present for metabolic mapping in living animals, unfixed cryostat sections of tissues, and living cells, and refers to protocols of the methods of choice. © 2010 Van Noorden. Source


van Gent W.P.C.,University of Amsterdam
International Journal of Housing Policy | Year: 2010

According to the Western European city thesis, European cities have a unique institutional mix which helps to explain how social patterns come about. The most important elements of this mix are the interventionist state and the housing system legacy of non-private housing. While these two are vital, overall generalisations are tricky due to regional variations in economic performance, housing markets and local state capabilities. This paper explores the generalisations that can be made about the institutional context of direct interventions in the built environment and housing, i.e. neighbourhood regeneration, in Western European cities. It examines how national policy frameworks and housing market characteristics impinge upon on the adoption of social transformation strategies. Social transformation strategies, often adopted in neighbourhood regeneration, refer to the use of physical interventions to institute social change in deprived areas. Generally, there are two types of social transformation strategies: large-scale tenure restructuring and upgrading. A comparative analysis of four cases of regeneration shows that in Western European cities the opportunities and constraints of national policy framework and regional housing market characteristics help to explain the social transformation strategies adopted locally. Furthermore, it shows the thesis' value as an explanatory and analytical framework for Western Europe. © 2010 Taylor & Francis. Source


Willems D.L.,University of Amsterdam | Verhagen A.A.,University of Groningen | van Wijlick E.,Royal Dutch Medical Association
Pediatrics | Year: 2014

BACKGROUND AND OBJECTIVES: Pediatric bioethics presumes that decisions should be taken in the child's best interest. If it's ambiguous whether a decision is in the child's interest, we defer to parents. Should parents be permitted to consider their own interests in making decisions for their child? In the Netherlands, where neonatal euthanasia is legal, such questions sometimes arise in deciding whether to hasten the death of a critically ill, suffering child. We describe the recommendations of a national Dutch committee. Our objectives were to analyze the role of competing child and family interests and to provide guidance on end-of-life decisions for doctors caring for severely ill newborns.METHODS: We undertook literature review, 7 consensus meetings in a multidisciplinary expert commission, and invited comments on draft report by specialists' associations.RESULTS: Initial treatment is mandatory for most ill newborns, to clarify the prognosis. Continuation of treatment is conditional on further diagnostic and prognostic data. Muscle relaxants can sometimes be continued after withdrawal of artificial respiration without aiming to shorten the child's life. When gasping causes suffering, or protracted dying is unbearable for the parents, muscle relaxants may be used to end a newborn's life. Whenever muscle relaxants are used, cases should be reported to the national review committee.CONCLUSIONS: New national recommendations in the Netherlands for end-of-life decisions in newborns suggest that treatment should generally be seen as conditional. If treatment fails, it should be abandoned. In those cases, palliative care should be directed at both infant and parental suffering. Sometimes, this may permit interventions that hasten death. Copyright © 2014 by the American Academy of Pediatrics. Source


Krishna R.,University of Amsterdam
Microporous and Mesoporous Materials | Year: 2014

The efficacy of nanoporous crystalline materials in separation applications is often influenced to a significant extent by diffusion of guest molecules within the pores of the structural frameworks. The Maxwell-Stefan (M-S) equations provide a fundamental and convenient description of mixture diffusion. The M-S formulation highlights two separate factors that cause mixture diffusion to be intrinsically coupled: correlation effects, and thermodynamic coupling. By careful and detailed analyses of a variety of published experimental data on (a) mixture permeation across nanoporous membranes, (b) transient uptake of mixtures within crystals, and (c) transient breakthrough characteristics of fixed bed adsorbers, we identify conditions that require the use of M-S equations including both correlation effects and thermodynamic coupling. Situations are also identified in which either of the coupling effects can be ignored. Correlation effects cause slowing-down of more-mobile-less- strongly-adsorbed molecules by tardier-more-strongly-adsorbed-partner species; such slowing-down effects are often essential for modeling mixture permeation across nanoporous membranes. Overshoots in the transient uptake of the more mobile partners in single crystals are essentially the consequence of thermodynamic coupling, originating from sizable off-diagonal elements of thermodynamic correction factors Γij. In the case of transient breakthrough of hexane isomers in a fixed bed of MFI zeolite, we show that thermodynamic coupling effects lead to a significant improvement in the separation performance. © 2013 Elsevier Inc. All rights reserved. Source


Roling R.W.,University of Amsterdam
Regional Studies | Year: 2010

The rise and growth of an international advertising industry in Amsterdam, Regional Studies. This paper presents an historical analysis of international advertising by describing four waves of advertising from early twentieth-century Western capitalism. This analysis is necessary to understand the dynamics within the organizational structure of the global advertising industry, with a tendency both of concentration in global network advertising agencies and of de-concentration, as small, flexible, and independent international advertising agencies came to the fore as innovative players. It is particularly this emerging group of smaller independent agencies that use Amsterdam in the Netherlands as a hub to create advertisements for the international market, and thereby have contributed to the increasing international importance of Amsterdam's advertising industry from the early 1990s and onwards. The difference between the different types of advertising agencies in terms of their market position is best reflected by their project networks. The global network advertising agencies turn out to be highly locally orientated, whereas the independents turn out to be much more international. © 2010 Regional Studies Association. Source


Vanderweele T.J.,Harvard University | Arah O.A.,University of California at Los Angeles | Arah O.A.,University of Amsterdam
Epidemiology | Year: 2011

Uncontrolled confounding in observational studies gives rise to biased effect estimates. Sensitivity analysis techniques can be useful in assessing the magnitude of these biases. In this paper, we use the potential outcomes framework to derive a general class of sensitivity-analysis formulas for outcomes, treatments, and measured and unmeasured confounding variables that may be categorical or continuous. We give results for additive, risk-ratio and odds-ratio scales. We show that these results encompass a number of more specific sensitivity-analysis methods in the statistics and epidemiology literature. The applicability, usefulness, and limits of the bias-adjustment formulas are discussed. We illustrate the sensitivity-analysis techniques that follow from our results by applying them to 3 different studies. The bias formulas are particularly simple and easy to use in settings in which the unmeasured confounding variable is binary with constant effect on the outcome across treatment levels. © 2010 by Lippincott Williams & Wilkins. Source


Rollman A.,University of Amsterdam
Journal of orofacial pain | Year: 2012

To determine the contribution of a wide range of factors to care-seeking behavior in orofacial pain patients, expressed as (A) decision to seek care and (B) number of health care practitioners visited. Subjects with orofacial pain complaints were recruited in seven TMD clinics and from a nonclinical population sample. They received a questionnaire including a wide range of possible predictors. To study which predictive variables were associated with the decision to seek care and with the number of health care practitioners visited, multiple regression models were built. Two hundred three persons with orofacial pain participated in the study. Of these participants, 169 (140 females) had visited at least one health care practitioner (care seekers), while the other 34 persons (25 females) did not (non-care seekers). The decision to seek care was not only associated with the pain intensity (P < .05), but, in women, also with fear of jaw movements (P < .01): Women with more fear of jaw movements were more likely to seek care. Pain intensity and disability were not associated with the number of health care practitioners visited. Instead, the main predictors were catastrophizing (P = .004) and the use of painkillers (P = .008). Pain intensity and fear of jaw movements play an important role in the decision to seek care for orofacial pain. The continuous search for help is associated with catastrophizing and the use of painkillers. Source


Kolk A.,University of Amsterdam
Sustainable Development | Year: 2013

This overview article examines the various dimensions of sustainable coffee as well as the actors involved and their perceptions of how to advance the market from niche to mainstream. The issues at hand are very complex, with different types of coffee producers, manufacturing/roasting companies and consumers, and a variety of standards, all with their own peculiarities and views on what is the best approach, and characterized by a divergent potential for 'scaling up'. Policymakers, managers and NGOs thus face difficult choices as to which path to pursue as there is no clear consensus on a concrete 'solution' to this 'wicked problem'. The article analyses the market for sustainable coffee, the different types of certified coffee available and their peculiarities considering production and supply perspectives, in relation to consumers who buy the final product. Implications are discussed as well, in the context of complexity and confusion, and the need for more complementarity. © 2011 John Wiley & Sons, Ltd and ERP Environment. Source


Fernandez-Borja M.,University of Amsterdam
Cell Research | Year: 2012

Endothelial cell adhesion to the extracellular matrix regulates migration and outgrowth of blood vessels during angiogenesis. Cell adhesion is mediated by integrins, which transduce signals from the extracellular environment into the cell and, in turn, are regulated by intracellular signaling molecules. In a paper recently published in Cell Research, Sandri et al. show that RIN2 connects three GTPases, R-Ras, Rab5 and Rac1, to promote endothelial cell adhesion through the regulation of integrin internalization and Rac1 activation. © 2012 IBCB, SIBS, CAS All rights reserved. Source


Youssef M.A.,University of Amsterdam
Cochrane database of systematic reviews (Online) | Year: 2011

For the last few decades urinary human chorionic gonadotrophin (hCG) has been used to induce final oocyte maturation triggering in in vitro fertilization (IVF) and intra-cytoplasmic sperm injection (ICSI) cycles. Recombinant technology has allowed the production of two drugs that can be used for the same purpose, to mimic the endogenous luteinizing hormone (LH) surge. This allows commercial production to be adjusted according to market requirements; the removal of all urinary contaminants; and the safe subcutaneous administration of a compound with less batch-to-batch variation. However, prior to a change in practice the effectiveness of the recombinant drugs should be known compared to the currently used urinary human chorionic gonadotrophin (uhCG). To assess the efficacy and safety of subcutaneous recombinant hCG (rhCG) and high dose recombinant LH (rLH) compared with intramuscular uhCG for inducing final oocyte maturation triggering in IVF and ICSI cycles. We searched the Cochrane Menstrual Disorders and Subfertility Group Trials Register (January 2010), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2010), MEDLINE (1966 to January 2010) and EMBASE (1980 to January 2010). Two review authors independently scanned titles and abstracts and selected those that appeared relevant for collection of the full paper. Only truly randomised controlled trials comparing rhCG and rLH with urinary hCG for final oocyte maturation triggering in IVF and ICSI cycles for treatment of infertility in normo-gonadotropic women were included. Assessment for inclusion or exclusion, quality assessment and data extraction were performed independently by two authors. Discrepancies were discussed in the presence of a third author and consensus reached. Quality assessment included method of randomisation, allocation concealment, blinding of participants and assessors, reporting of a power calculation and intention-to-treat analysis. Fourteen RCTs (n = 2306) were identified; 11 compared rhCG with uhCG and three compared rhLH with uhCG. There was no evidence of a statistically significant difference between rhCG and uhCG regarding the ongoing pregnancy or live birth rate (6 RCTs: OR 1.04, 95% CI 0.79 to 1.37; P = 0.83, I(2) = 0%). There was no significant difference in the incidence of ovarian hyperstimulation syndrome (OHSS) between rhCG and uhCG (3 RCTs: OR 1.5, 95% CI 0.37 to 4.1; P = 0.37, I(2) = 0%). There was no evidence of statistically significant difference between rhLH and uhCG regarding the ongoing pregnancy or live birth rate (OR 0.94, 95% CI 0.50 to 1.76) and incidence of OHSS (OR 0.82, 95% CI 0.39 to 1.69). These results leave open the possibility of strong differences in favour of either treatment for both ongoing pregnancy and OHSS. We conclude that there is no evidence of difference between rhCG or rhLH and uhCG in achieving final follicular maturation in IVF, with equivalent pregnancy rates and OHSS incidence. According to these findings uHCG is still the best choice for final oocyte maturation triggering in IVF and ICSI treatment cycles. Source


van Wely M.,University of Amsterdam
Cochrane database of systematic reviews (Online) | Year: 2011

Several systematic reviews compared recombinant gonadotrophin with urinary gonadotrophins (HMG, purified FSH, highly purified FSH) for ovarian hyperstimulation in IVF and ICSI cycles and these reported conflicting results. Each of these reviews used different inclusion and exclusion criteria for trials. Our aim in producing this review is to bring together all randomised studies in this field under common inclusion criteria with consistent and valid statistical methods. To compare the effectiveness of recombinant gonadotrophin (rFSH) with the three main types of urinary gonadotrophins (i.e. HMG, FSH-P and FSH-HP) for ovarian stimulation in women undergoing IVF or ICSI treatment cycles. An extended search was done according to Cochrane guidelines including the Menstrual Disorders & Subfertility Group's Specialised Register of controlled trials, The Cochrane Central Register of Controlled Trials, MEDLINE (1966 to May 2010), EMBASE (1980 to May 2010), CINAHL (1982 to May 2010), National Research Register, and Current Controlled Trials. All randomised controlled trials reporting data comparing clinical outcomes for women undergoing IVF/ICSI cycles and using recombinant FSH in comparison with HMG or highly purified HMG, purified urinary FSH (FSH-P), and highly purified urinary FSH (FSH-HP) for ovarian hyperstimulation in IVF or ICSI cycles were included. Primary outcome measure was live birth rate and OHSS per randomised woman.Binary outcomes were analysed using odds ratios and also reported in absolute terms. Grouped analyses were carried out for all outcomes to explore whether relative effects differed due to key features of the trials. We included 42 trials with a total of 9606 couples. Comparing rFSH to any of the other gonadotrophins irrespective of the down-regulation protocol used, did not result in any evidence of a statistically significant difference in live birth rate (28 trials, 7339 couples, odds ratio 0.97, 95% CI 0.87 to 1.08). This suggests that for a group with a 25% live birth rate using urinary gonadotrophins the rate would be between 22.5% and 26.5% using rFSH. There was also no evidence of a difference in the OHSS rate (32 trials, 7740 couples, OR 1.18, 95% CI 0.86 to 1.61). This means that for a group with 2% risk of OHSS using urinary gonadotrophins, the risk would be between 1.7% and 3.2% using rFSH. Clinical choice of gonadotrophin should depend on availability, convenience and costs. Further research on these comparisons is unlikely to identify substantive differences in effectiveness or safety. Source


Cruz-Cabeza A.J.,University of Amsterdam | Bernstein J.,Abu Dhabi University | Bernstein J.,Ben - Gurion University of the Negev
Chemical Reviews | Year: 2014

An unambiguous definition of conformational change and conformational polymorphism, as well as a quantitative basis for the likelihood of its appearance, is reviewed. Conformational adjustment and conformational change are different phenomena. Two polymorphs are conformational polymorphs only if their conformations are related by conformational change. Conformational change requires a change of gas-phase conformer and, hence, crossing of an energy barrier. Energy differences associated with conformational variations of small organic molecules in different polymorphs are usually small. Higher-energy conformations in crystals are rare but possible for molecules that are able to break an intramolecular interaction in favor of a strong intermolecular interaction and molecules that crystallize in special symmetry positions. Polymorphic molecules containing R-bonds that are prone to both change and adjust are likely to display a rich polymorphic landscape. Source


Calabrese P.,University of Pisa | Campostrini M.,University of Pisa | Essler F.,University of Oxford | Nienhuis B.,University of Amsterdam
Physical Review Letters | Year: 2010

We consider the Rényi α entropies for Luttinger liquids (LL). For large block lengths, these are known to grow like ln. We show that there are subleading terms that oscillate with frequency 2kF (the Fermi wave number of the LL) and exhibit a universal power-law decay with . The new critical exponent is equal to K/(2α), where K is the LL parameter. We present numerical results for the anisotropic XXZ model and the full analytic solution for the free fermion (XX) point. © 2010 The American Physical Society. Source


Marcelli T.,Polytechnic of Milan | Hiemstra H.,University of Amsterdam
Synthesis | Year: 2010

This article reviews the applications of cinchona alkaloids as asymmetric catalysts. In the last few years, characterized by the resurgence of interest in asymmetric organocatalysis, cinchona derivatives have been shown to catalyze an outstanding array of chemical reactions, often with remarkable stereoselectivity. This work presents an overview of the transformations developed in the period from 2001 through 2009, highlighting applications in the synthesis of bioactive molecules and natural products. 1 Introduction 2 Additions to Carbonyls 3 Additions to Imines 4 Conjugate Additions 5 Additions to Olefins 6 Nucleophilic Substitutions 7 Electrophilic Halogenations 8 Opening of Cyclic Anhydrides 9 Acylations 10 Cycloadditions 11 Rearrangements 12 Decarboxylations 13 Miscellaneous 14 Conclusions and Outlook List of abbreviations: Alloc, allyloxycarbonyl; Boc, tert-butyloxy?carbonyl; Bs, benzenesulfonyl; BTTP, tert-butyliminotri(pyrrolidino)phosphorane; Cbz, benzyloxycarbonyl; DABCO, 1,4-diazabicyclo[2.2.2]octane; DBAD, dibenzyl azodicarboxylate; DBU, 1,8-diazabicycloundec-7-ene; DCE, 1,2-dichloroethane; DFT, density functional theory; DIPEA, N,N-diisopropylethyl?amine; DNP, 2,4-dinitrophenyl; DMB, 3,4-dimethoxybenzoyl; DPM, diphenylmethyl; DTAD, di-tert-butyl azodicarboxylate; EVE, ethyl vinyl ether; EWG, electron-withdrawing group; FBSM, 1-fluorobis(phenylsulfonyl)methane; HFiPA, 1,1,1,3,3,3-hexafluoro-2-propyl acrylate; LAH, lithium aluminum hydride; LG, leaving group; Moc, methyloxycarbonyl; MPEG, poly(ethylene glycol) monomethyl ether; MS, molecular sieves; MVK, methyl vinyl ketone; NFSI, N-fluorobenzenesulfonimide; NMR, nuclear magnetic resonance; Ns, p-nitrophenylsulfonyl; PEG, poly(ethylene glycol); PS, proton sponge [1,8-bis(dimethylamino)naphthalene]; rds, rate-determining step; TBAF, tetrabutylammonium fluoride; TCCA, trichloroisocyanuric acid; TFAA, trifluoroacetic anhydride; THF, tetrahydrofuran; TMAF, tetramethylammonium fluoride; TMS, trimethylsilyl; Ts, p-toluenesulfonyl; UNCA, urethane-protected -amino acid N-carboxyanhydrides. © Georg Thieme Verlag Stuttgart · New York. Source


Nieuwenhuijsen K.,University of Amsterdam
Occupational medicine (Oxford, England) | Year: 2010

Knowledge on the impact of the psychosocial work environment on the occurrence of stress-related disorders (SRDs) can assist occupational physicians in the assessment of the work-relatedness of these disorders. To systematically review the contribution of work-related psychosocial risk factors to SRDs. A systematic review of the literature was carried out by searching Medline, PsycINFO and Embase for studies published up until October 2008. Studies eligible for inclusion were prospective cohort studies or patient-control studies of workers at risk for SRDs. Studies were included in the review when data on the association between exposure to psychosocial work factors and the occurrence of SRDs were presented. Where possible, meta-analysis was conducted to obtain summary odds ratios of the association. The strength of the evidence was assessed using four levels of evidence. From the 2426 studies identified, seven prospective studies were included in this review. Strong evidence was found that high job demands, low job control, low co-worker support, low supervisor support, low procedural justice, low relational justice and a high effort-reward imbalance predicted the incidence of SRDs. This systematic review points to the potential of preventing SRDs by improving the psychosocial work environment. However, more prospective studies are needed on the remaining factors, exposure assessment and the relative contributions of single factors, in order to enable consistent assessment of the work-relatedness of SRDs by occupational physicians. Source


Fan D.,University of Alberta | Creemers E.E.,University of Amsterdam | Kassiri Z.,University of Alberta
Circulation Research | Year: 2014

The extracellular matrix (ECM) is best known for its function as a structural scaffold for the tissue and more recently as a microenvironment to sequester growth factors and cytokines allowing for rapid and localized changes in their activity in the absence of new protein synthesis. In this review, we explore this and additional new aspects of ECM function in mediating cell-to-cell communications. Fibrillar and nonfibrillar components of ECM can limit and facilitate the transport of molecules through the extracellular space while also regulating interstitial hydrostatic pressure. In turn, transmembrane communications via molecules, such as ECM metalloproteinase inducer, thrombospondins, and integrins, can further mediate cell response to extracellular cues and affect ECM composition and tissue remodeling. Other means of cell-to-cell communication include extracellular microRNA transport and its contribution to gene expression in target cells and the nanotube formation between distant cells, which has recently emerged as a novel conduit for intercellular organelle sharing thereby influencing cell survival and function. The information summarized and discussed here are not limited to the cardiovascular ECM but encompass ECM in general with specific references to the cardiovascular system. © 2014 American Heart Association, Inc. Source


Leydesdorff L.,University of Amsterdam | Bornmann L.,Max Planck Society Administrative Headquarters Hofgartenstrasse 8 D 80539 Munich Germany
Journal of the American Society for Information Science and Technology | Year: 2012

A technique is developed using patent information available online (at the U.S. Patent and Trademark Office) for the generation of Google Maps. The overlays indicate both the quantity and the quality of patents at the city level. This information is relevant for research questions in technology analysis, innovation studies, and evolutionary economics, as well as economic geography. The resulting maps can also be relevant for technological innovation policies and research and development management, because the U.S. market can be considered the leading market for patenting and patent competition. In addition to the maps, the routines provide quantitative data about the patents for statistical analysis. The cities on the map are colored according to the results of significance tests. The overlays are explored for the Netherlands as a "national system of innovations" and further elaborated in two cases of emerging technologies: ribonucleic acid interference (RNAi) and nanotechnology. © 2012 ASIS&T. Source


Baptista J.M.,University of Amsterdam | Baptista J.M.,University of Lisbon
Nuclear Physics B | Year: 2011

We derive general expressions for the Kähler form of the L2-metric in terms of standard 2-forms on vortex moduli spaces. In the case of abelian vortices in gauged linear sigma-models, this allows us to compute explicitly the Kähler class of the L2-metric. As an application we compute the total volume of the moduli space of abelian semi-local vortices. In the strong coupling limit, this then leads to conjectural formulae for the volume of the space of holomorphic maps from a compact Riemann surface to projective space. Finally we show that the localization results of Samols in the abelian Higgs model extend to more general models. These include linear non-abelian vortices and vortices in gauged toric sigma-models. © 2010 Elsevier B.V. Source


Chandra Y.,University of Leeds | Leenders M.A.A.M.,University of Amsterdam
Technovation | Year: 2012

While prior studies have investigated factors, processes and pathways traversed in user innovation and user entrepreneurship within the real world, there is scant attention for user innovation and user entrepreneurship that take place within the virtual world. We report on an exploratory study of a select group of user innovators-entrepreneurs in Second Life, using virtual participant observation and in-depth interviews. Results suggest that the paths traversed by user innovators and user entrepreneurs in the virtual life broadly resemble those in the real life as reported in the literature. Interestingly, our study also suggests that Second Life as a virtual world breeds opportunities leading to entrepreneurial acts in the 'real' world as well as further opportunities in the Second Life. The virtual world itself, as a technological platform, also generates a range of opportunities. We formulate testable propositions and further link our insights to existing research on the drivers and pathways of user innovation and entrepreneurship in the 'real' world (i.e.; the role of prior knowledge and networks), Austrian economics theory of entrepreneurial discovery, and creative collective theory. © 2012 Elsevier Ltd. All rights reserved. Source


Question: Do beech and hornbeam differ in undergrowth species diversity, and could these differences be explained by mass of the organic layer, pH or soil moisture? Could species richness under beech and hornbeam be explained by differences in N dynamics? Location: Ancient forests dominated by beech and hornbeam in Luxembourg, on decalcified and lime-rich parent material. Methods: Species composition and soil characteristics, i.e. mass of the organic layer, pH, moisture content, bulk density and air-filled pore space, were determined under beech and hornbeam on decalcified marl and limestone, and analysed with cluster analysis, correspondence analysis and ANOVA, with tree species and parent material as independent factors. Net N mineralization, nitrification and N in soil and microbial biomass were determined in a laboratory incubation experiment over a pH gradient, and correlated with species richness. Results: Species richness was lower under beech than under hornbeam on both decalcified marl and on limestone. Mass of the organic layer was higher under beech in all cases, but pH and soil moisture only differed between tree species on decalcified marl. Species richness increased with soil N, microbial N and nitrification in the mineral topsoil, but was not correlated with net N mineralization, and was negatively correlated with nitrification in the organic layer and with efficiency of N mineralization per unit microbe. Conclusion: Litter quality affected species richness on both limestone and decalcified marl via the organic layer, but only on decalcified marl in terms of pH or soil moisture. Species richness did not seem to be stimulated by high overall net N mineralization or high nitrate availability in the organic layer, but only by high nitrate in the mineral topsoil. © 2009 International Association for Vegetation Science. Source


Rhebergen M.D.,University of Amsterdam
Journal of medical Internet research | Year: 2012

Many workers have questions about occupational safety and health (OSH). It is unknown whether workers are able to find correct, evidence-based answers to OSH questions when they use common information sources, such as websites, or whether they would benefit from using an easily accessible, free-of-charge online network of OSH experts providing advice. To assess the rate of correct, evidence-based answers to OSH questions in a group of workers who used an online network of OSH experts (intervention group) compared with a group of workers who used common information sources (control group). In a quasi-experimental study, workers in the intervention and control groups were randomly offered 2 questions from a pool of 16 standardized OSH questions. Both questions were sent by mail to all participants, who had 3 weeks to answer them. The intervention group was instructed to use only the online network ArboAntwoord, a network of about 80 OSH experts, to solve the questions. The control group was instructed that they could use all information sources available to them. To assess answer correctness as the main study outcome, 16 standardized correct model answers were constructed with the help of reviewers who performed literature searches. Subsequently, the answers provided by all participants in the intervention (n = 94 answers) and control groups (n = 124 answers) were blinded and compared with the correct model answers on the degree of correctness. Of the 94 answers given by participants in the intervention group, 58 were correct (62%), compared with 24 of the 124 answers (19%) in the control group, who mainly used informational websites found via Google. The difference between the 2 groups was significant (rate difference = 43%, 95% confidence interval [CI] 30%-54%). Additional analysis showed that the rate of correct main conclusions of the answers was 85 of 94 answers (90%) in the intervention group and 75 of 124 answers (61%) in the control group (rate difference = 29%, 95% CI 19%-40%). Remarkably, we could not identify differences between workers who provided correct answers and workers who did not on how they experienced the credibility, completeness, and applicability of the information found (P > .05). Workers are often unable to find correct answers to OSH questions when using common information sources, generally informational websites. Because workers frequently misjudge the quality of the information they find, other strategies are required to assist workers in finding correct answers. Expert advice provided through an online expert network can be effective for this purpose. As many people experience difficulties in finding correct answers to their health questions, expert networks may be an attractive new source of information for health fields in general. Source


Hetterscheid D.G.H.,Leiden University | Reek J.N.H.,University of Amsterdam
European Journal of Inorganic Chemistry | Year: 2014

Treatment of Ir(OH)2 with sodium periodate in aqueous solution results in formation of dioxygen following the rate law v = k obs[Ir]0.65[IO4]0.5, with k obs = 1.5 × 10-3 {Ir(OH)2 = [IrCp(Me 2NHC)(OH)2], where Me2NHC = N-dimethylimidazolin-2-ylidene and Cp* = cyclopentadienyl}. In situ ESI-MS experiments in combination with DFT calculations show that [Ir III(IO3)]+ and [IrV(=O)(IO 3)]+ species are present in the reaction mixture. On the basis of the presence of these species, a mechanistic pathway was calculated illustrating that water is not necessarily the source of the oxygen. A low-lying pathway exists wherein O2 production proceeds via two consecutive O-atom-transfer reactions from periodate to the catalyst. The resulting iodite ligand is further oxidized to close the catalytic cycle. The rate-determining step in this process is formation of the O-O bond. For this transition a 21.8 kcal/mol barrier was found. This value fits very well with the observed turnover frequency of 0.27 s-1. Although it is difficult to prove that this is the dominant pathway, these data clearly illustrate that one has to be very careful with interpretation of catalytic results in periodate-driven water oxidation reactions. Treatment of water with periodate in the presence of [IrCp(Me2NHC)(OH)2] results in formation of O2. DFT calculations and in situ mass spectrometry experiments point to a mechanism involving one or two O-atom-transfer steps, rather than electron-transfer steps only. Results must thus be interpreted cautiously when periodate is used as an oxidant in the study of catalytic water oxidation. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


There is growing interest in soluble biomarkers that could be used on the group level for screening purposes in small proof of principle studies during early drug development. We investigated early changes in serum levels of several candidate biomarkers involved in cartilage and bone metabolism following the initiation of adalimumab as a prototypic active treatment in psoriatic arthritis (PsA) compared to placebo. Twenty-four PsA patients were randomized to receive either adalimumab 40 mg s.c. every other week or placebo for 4 weeks, followed by an open label extension phase. Serum samples were obtained at baseline and after 4 and 12 weeks of treatment and analyzed for levels of CPII and PINP (synthesis of type II and type I procollagen), melanoma inhibitory activity (MIA) (chondrocyte anabolism), matrix metalloproteinase (MMP)-3, C2C and cartilage oligomeric matrix protein (COMP) (type II collagen degradation), osteocalcin (OC) (bone formation), NTX-I and ICTP (both type I collagen degradation). After 4 weeks, there was a significant decrease in serum MMP-3 levels in adalimumab-treated patients (P<0.005), while no change was observed in the placebo group. A significant increase in serum MIA was noted after adalimumab therapy (P<0.005) but not after placebo treatment. After 12 weeks, there was a marked reduction in serum MMP-3 in both groups (P<0.005), whereas other markers did not show significant changes compared to baseline. MMP-3 and MIA could serve as soluble biomarkers associated with inflammation as well as joint remodelling and destruction and may, together with clinical evaluation and in combination with other biomarkers, assist in distinguishing between effective and ineffective therapy in small, proof-of-principle studies of short duration in PsA. Current Controlled Trials ISRCTN23328456. Source


Krishna R.,University of Amsterdam | Long J.R.,University of California at Berkeley | Long J.R.,Lawrence Berkeley National Laboratory
Journal of Physical Chemistry C | Year: 2011

Metal-organic frameworks (MOFs) offer considerable potential for separating a variety of mixtures that are important in applications such as CO2 capture and H2 purification. In view of the vast number of MOFs that have been synthesized, there is a need for a reliable procedure for comparing screening and ranking MOFs with regard to their anticipated performance in pressure swing adsorption (PSA) units. For this purpose, the most commonly used metrics are the adsorption selectivity and the working capacity. Here, we suggest an additional metric for comparing MOFs that is based on the analysis of the transient response of an adsorber to a step input of a gaseous mixture. For a chosen purity of the gaseous mixture exiting from the adsorber, a dimensionless breakthrough time τbreak can be defined and determined; this metric determines the frequency of required regeneration and influences the productivity of a PSA unit. The values of τbreak are dictated both by selectivity and by capacity metrics.By performing transient adsorber calculations for separation of CO2/H2, CO 2/CH4, CH4/H2, and CO 2/CH4/H2 mixtures, we compare the values of τbreak to highlight some important advantages of MOFs over conventionally used adsorbents such as zeolite NaX. For a given separation duty, such comparisons provide a more realistic ranking of MOFs than afforded by either selectivity or capacity metrics alone. We conclude that breakthrough calculations can provide an essential tool for screening MOFs. © 2011 American Chemical Society. Source


De Bruin N.M.W.J.,Fraunhofer Institute for Molecular Biology and Applied Ecology | Kruse C.G.,University of Amsterdam
Current Pharmaceutical Design | Year: 2015

5-hydroxytryptamine6 receptor (5-HT6R) antagonists have shown efficacy in animal models for cognitive impairment in multiple cognitive domains relevant for schizophrenia. Improvements were found with 5-HT6R antagonists in preclinical tests for episodic memory, social cognition, executive function, working memory and several other tests for both learning and memory. In contrast, there is little evidence for efficacy on attention. It will be interesting to further investigate 5-HT6R antagonists in neurodevelopmental animal models which are based on prenatal exposure to specific environmental insults, and are characterized by a high level of face, construct and predictive validity for cognitive impairments associated with schizophrenia. It is also important to do more add-on preclinical studies of 5-HT6 antagonists with antipsychotics. Possible mechanisms of action to improve cognition have been described. 5- HT6R antagonists decrease GABA release and GABAergic interneuron excitability, which subsequently disinhibits glutamate and/or acetylcholine release and results in enhancement of synaptic plasticity. Furthermore, cognition could be improved by 5-HT6R antagonists, because these compounds increase the number of NCAM PSA-immunoreactive neurons in the dendate gyrus, inhibit mTOR and Fyntyrosine kinase and interact with DARPP-32. Interestingly, there is increasing preclinical evidence that could support additional benefits of 5-HT6R ligandson comorbid conditions in schizophrenia such as drug abuse, depression, anxiety, obesity andantipsychotic-induced EPS. Finally, we briefly give an overview of the 5-HT6R compounds that are currently in clinical development for the treatment of cognitive impairment in both schizophrenia and Alzheimer’s disease. © 2015, Bentham Science Publishers. Source


The first purification of bovine NADH:ubiquinone oxidoreductase (Complex I) was reported nearly half a century ago (Hatefi et al. J Biol Chem 237:1676-1680, 1962). The pathway of electron-transfer through the enzyme is still under debate. A major obstacle is the assignment of EPR signals to the individual iron-sulfur clusters in the subunits. The preceding paper described a working model based on the kinetics with NADPH. This model is at variance with current views in the field. The present paper provides a critical overview on the possible causes for the discrepancies. It is concluded that the stability of all purified preparations described thus far, including Hatefi's Complex I, is compromised due to removal of the enzyme from the protective membrane environment. In addition, most preparations described during the last two decades are purified by methods involving synthetic detergents and column chromatography. This results in delipidation, loss of endogenous quinones and loss of reactions with (artificial) quinones in a rotenone-sensitive way. The Fe:FMN ratio's indicate that FMN-a is absent, but that all Fe-S clusters may be present. In contrast to the situation in bovine SMP and Hatefi's Complex I, three of the six expected [4Fe-4S] clusters are not detected in EPR spectra. Qualitatively, the overall EPR lineshape of the remaining three cubane signals may seem similar to that of Hatefi's Complex I, but quantitatively it is not. It is further proposed that point mutations in any of the TYKY, PSST, 49-kDa or 30-kDa subunits, considered to make up the delicate structural heart of Complex I, may have unpredictable effects on any of the other subunits of this quartet. The fact that most point mutations led to inactive enzymes makes a correct interpretation of such mutations even more ambiguous. In none of the Complex-I-containing membrane preparations from non-bovine origin, the pH dependencies of the NAD(P)H→O2 reactions and the pH-dependent reduction kinetics of the Fe-S clusters with NADPH have been determined. This excludes a proper discussion on the absence or presence of FMN-a in native Complex I from other organisms. © 2010 The Author(s). Source


Rollman A.,University of Amsterdam
Journal of orofacial pain | Year: 2013

To identify potential predictors of self-reported sleep bruxism (SB) within children's family and school environments. A Aims: To assess possible differences between care seekers and non-care seekers with temporomandibular disorder (TMD) pain complaints, by using semi-structured interviews. Semi-structured interviews were held with 16 subjects who had TMD- pain complaints: 8 care seekers and 8 non-care seekers, matched for age, sex, pain intensity, and fear of movement. Subjects were selected from a previously held survey study, with their consent. The interviews were audiotaped, transcribed verbatim, and analyzed according to qualitative content analysis. From the analysis, seven themes differentiating care seekers from non-care seekers were identified: catastrophizing, pain management, assertiveness, critical attitude towards health care, confidence in medical care, recognition, and adequate referral. Aspects upon which care seekers differed from non-care seekers were mainly person-related characteristics. Next to these characteristics, it appeared that inadequate referrals may play a role in care seeking. The use of semi-structured interviews may further improve insights into processes that determine care seeking among people with TMD pain complaints. Source


Sorokin D.Y.,Technical University of Delft | Banciu H.L.,Babes - Bolyai University | Muyzer G.,University of Amsterdam
Current Opinion in Microbiology | Year: 2015

Soda lakes represent unique permanently haloalkaline system. Despite the harsh conditions, they are inhabited by abundant, mostly prokaryotic, microbial communities. This review summarizes results of studies of main functional groups of the soda lake prokaryotes responsible for carbon, nitrogen and sulfur cycling, including oxygenic and anoxygenic phototrophs, aerobic chemolithotrophs, fermenting and respiring anaerobes. The main conclusion from this work is that the soda lakes are very different from other high-salt systems in respect to microbial richness and activity. The reason for this difference is determined by the major physico-chemical features of two dominant salts - NaCl in neutral saline systems and sodium carbonates in soda lakes, that are influencing the amount of energy required for osmotic adaptation. © 2015 Elsevier Ltd. Source


Huson M.A.,University of Amsterdam
Clinical infectious diseases : an official publication of the Infectious Diseases Society of America | Year: 2014

Information on community-acquired bacterial bloodstream infections (BSIs) in individuals infected with human immunodeficiency virus (HIV) is limited. We conducted a systematic literature review. The case fraction of community-acquired bacterial BSIs in hospitalized patients is 20% and 30% in adults and children, respectively, compared to 9% in HIV-negative adults and children. Worldwide, the main pathogens of community-acquired BSI are nontyphoid salmonellae (NTS), Streptococcus pneumoniae, Escherichia coli, and Staphylococcus aureus, but regional differences are apparent, especially for S. pneumoniae. Compared to HIV-negative populations, HIV patients are particularly at risk to develop NTS bacteremia. Bacteremia incidence is related to immunosuppression, and antiretroviral therapy reduces the incidence of BSI in HIV patients (rate ratios, 0.63-0.02). Mortality rates varied between 7% and 46%. These results suggest that bacterial BSI is more likely to be found in HIV-positive than in HIV-negative patients upon hospitalization, and that causative pathogens vary by region. Source


Blutner R.,University of Amsterdam
Cognitive Systems Research | Year: 2010

We propose a formalization of C.G. Jung's theory of personality using a four-dimensional Hilbert-space for the representation of two qubits. The first qubit relates to Jung's four psychological functions: Thinking, Feeling, Sensing and i. Ntuition, which are represented by two groups of projection operators, {. T, F} and {. S, N}. The operators in each group are commuting but operators of different groups are not. The second qubit represents Jung's two perspectives of extraversion and introversion. It is shown that this system gives a natural explanation of the 16 psychological types that are defined in the Jungian tradition. Further, the system accounts for the restriction posed by Jung concerning the possible combination of psychological functions and perspectives. The empirical consequences of the present theory are discussed, and the results of a pilot study are reported with the aim to check some basic predictions of the theory. In addition, it is shown why the present praxis of personality diagnostics based on classical statistics is insufficient. © 2009 Elsevier B.V. Source


Youssef M.A.,University of Amsterdam
Cochrane database of systematic reviews (Online) | Year: 2010

Gonadotropin-releasing hormone (GnRH) antagonist protocols for pituitary down regulation in in vitro fertilisation (IVF) and intracytoplasmic sperm injection (ICSI) allow the use of GnRH agonists for triggering final oocyte maturation. Currently, human chorionic gonadotropin (HCG) is still the standard medication for this purpose. The effectiveness of triggering with a GnRH agonist compared to HCG measured as pregnancy and ovarian hyperstimulation(OHSS) rates are unknown. To compare the effectiveness of a GnRH agonist with HCG for triggering final oocyte maturation in IVF and ICSI patients undergoing controlled ovarian hyperstimulation in a GnRH antagonist protocol followed by embryo transfer.  We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE , EMBASE, the National Research Register, the Medical Research Council's Clinical Trials Register, and the NHS Centre for Reviews and Dissemination database. We also examined the reference lists of all known primary studies and review articles, citation lists of relevant publications and abstracts of major scientific meetings. All randomised controlled studies (RCTs) reporting data comparing clinical outcomes for women undergoing IVF and ICSI cycles and using a GnRH agonist in comparison with HCG for final oocyte maturation triggering. Two review authors independently assessed trial quality and extracted data. We identified 11 RCTs (n = 1055). Eight studies assessed fresh autologous cycles and three studies assessed donor-recipient cycles. In fresh-autologous cycles, GnRH agonist was less effective than HCG in terms of the live birth rate per randomised woman (OR 0.44, 95% CI 0.29 to 0.68; 4 RCTs) and ongoing pregnancy rate per randomised woman (OR 0.45, 95% CI 0.31 to 0.65; 8 RCTs). For a group with a 30% live birth or ongoing pregnancy rate using HCG, the rate would be between 12% and 22% using an GnRH agonist. Moderate to severe ovarian hyperstimulation syndrome (OHSS) incidence per randomised woman was significantly lower in the GnRH agonist group compared to the HCG group (OR 0.10, 95% CI 0.01 to 0.82; 5 RCTs). For a group with a 3% OHSS rate using HCG the rate would be between 0% and 2.6% using GnRH agonist. In donor recipient cycles, there was no evidence of a statistical difference in the live birth rate per randomised woman (OR 0.92, 95% CI 0.53 to 1.61; 1 RCT). We do not recommend that GnRH agonists be routinely used as a final oocyte maturation trigger in fresh autologous cycles because of lowered live birth rates and ongoing pregnancy rates. An exception could be made for women with high risk of OHSS, after appropriate counselling. Source


van Montfort T.,University of Amsterdam
Expert review of vaccines | Year: 2012

Evaluation of: Böckl K, Wild J, Bredl S et al. Altering an artificial Gagpolnef polyprotein and mode of Env co-administration affects the immunogenicity of a clade C HIV-1 DNA vaccine. PLoS ONE 7(4), e34723 (2012). SIV vaccination studies in monkeys have revealed that Env-directed antibodies are critical for protection against virus acquisition, whereas CD8(+) T-cell responses against the Gag and Pol proteins contribute to control of viremia postinfection. However, designing a vaccine that strongly activates both arms of the immune system, is challenging for a variety of reasons, one being interference of Gag and Env responses. Böckl et al. have studied how to optimize CD8 T-cell responses against Gag, Pol and Nef in the presence of Env co-vaccination. Although Env coadministration suppressed anti-Gag CD8(+) responses, this effect could be counteracted by adjusting the molar ratio of the vaccines and by spatial or temporal separation of the Gag and Env antigens. These results demonstrate that optimal induction of antiviral CD8(+) responses requires careful optimization of vaccine design, composition and administration. Source


Van der Sleen M.I.,University of Amsterdam
International journal of dental hygiene | Year: 2010

The objective of this review was to summarize the available evidence regarding the effects of mechanical tongue cleaning compared with no mechanical tongue cleaning on breath odour and tongue coating (TC). PubMed-MEDLINE, EMBASE and Cochrane-CENTRAL were searched to identify potentially relevant studies. The inclusion criteria included the following: randomized controlled clinical trials (RCTs) or controlled clinical trials (CCTs) conducted in humans in good general health (no systemic disorders) and a patient age of ≥17 years. For the intervention, we considered tongue cleaning [the use of a tongue scraper (TS) or tongue brush (TB)] and for the control, brushing only (B) groups. Clinical parameters such as volatile sulphur compound concentration, organoleptic scores and TC were the outcome variables of interest. Study selection, quality assessment and data extraction were carried out by two independent reviewers. After screening of the titles and abstracts and subsequent full text reading of the potential papers, we identified five publications that met the eligibility criteria and provided seven experiments. The five studies consisted of three RCTs and two CCTs. All experiments show a positive effect of mechanical tongue cleaning in addition to toothbrushing on various parameters of oral malodour. This review demonstrated that mechanical approaches, such as tongue brushing or tongue scraping to clean the dorsum of the tongue, have the potential to successfully reduce breath odour and TC. However, data concerning the effect of mechanical tongue cleaning on chronic oral malodour (halitosis) are insufficient. © 2010 John Wiley & Sons A/S. Source


Levi M.,University of Amsterdam
Hamostaseologie | Year: 2010

Critically ill patients often have systemic activation of both inflammation and coagulation. Increasing evidence points to an extensive cross-talk between these two systems, whereby inflammation not only leads to activation of coagulation, but coagulation also considerably affects inflammatory activity. The intricate relationship between inflammation and coagulation may have major consequences for the pathogenesis of microvascular failure and subsequent multiple organ failure, as a result of severe infection and the associated systemic inflammatory response. Molecular pathways that contribute to inflammation-induced activation of coagulation have been precisely identified. Activation of the coagulation system and ensuing thrombin generation is dependent on an interleukin-6-induced expression of tissue factor on activated mononuclear cells and endothelial cells and is insufficiently counteracted by tissue factor pathway inhibitor. Simultaneously, endothelial-bound anticoagulant mechanisms, in particular the protein C system and the antithrombin system, are shut-off by pro-inflammatory cytokines. Modulation of inflammatory activity by activation of coagulation also occurs by various mechanisms. Activated coagulation proteases, such as the tissue factor-factor VIIa complex, factor Xa and thrombin can bind to protease-activated receptors on various cells and the ensuing intracellular signaling leads to increased production of pro-inflammatory cytokines and chemo kines. Physiological anticoagulants can modulate inflammatory activity as well. Increasing knowledge on the various mechanisms underlying activation of inflammation and coagulation may lead to better (adjunctive) management strategies in critically ill patients. © Schattauer 2010. Source


Rogers R.,University of Amsterdam
Journal of Information Technology and Politics | Year: 2010

Digital studies on culture may be distinguished from cultural studies of the digital, at least in terms of method. This lecture takes up the question of the distinctiveness of "digital methods" for researching Internet cultures. It asks, initially, should the methods of study change, however slightly or wholesale, given the specificity of the new medium? The larger digital methods project thereby engages with "virtual methods," the current, dominant "e-science" approach to the study of the Internet, and the consequences for research of importing standard methods from the social sciences in particular. What kinds of contributions are made to digital media studies, and the Internet in particular, when traditional methods are imported from the social sciences and the humanities onto the medium? Which research opportunities are foreclosed? Second, I ask, what kinds of new approaches are worthwhile, given an emphasis on the "natively digital" as opposed to digitization? The goal is also to change the focus of humanities and humanities computing away from the opportunities afforded by transforming ink into bits. The effort is to develop the study of natively digital objects (the link, the tag, etc.) and devices (engines and other recommendation machines) that make use of them. After critically reviewing existing approaches to the study of the digital, which largely import method onto the medium, I subsequently propose research strategies that follow the medium. How can one learn from methods in the medium, and repurpose them for social and cultural research? The lecture launches a novel strand of study: digital methods. © Taylor & Francis Group, LLC. Source


Leydesdorff L.,University of Amsterdam | Opthof T.,Experimental Cardiology Group
Journal of the American Society for Information Science and Technology | Year: 2010

Impact factors (and similar measures such as the Scimago Journal Rankings) suffer from two problems: (a) citation behavior varies among fields of science and, therefore, leads to systematic differences, and (b) there are no statistics to inform us whether differences are significant. The recently introduced "source normalized impact per paper" indicator of Scopus tries to remedy the first of these two problems, but a number of normalization decisions are involved, which makes it impossible to test for significance. Using fractional counting of citation-based on the assumption that impact is proportionate to the number of references in the citing document-citations can be contextualized at the paper level and aggregated impacts of sets can be tested for their significance. It can be shown that the weighted impact of Annals of Mathematics (0.247) is not so much lower than that of Molecular Cell (0.386) despite a five-f old difference between their impact factors (2.793 and 13.156, respectively). © 2010 ASIS&T. Source


Leydesdorff L.,University of Amsterdam
Journal of the American Society for Information Science and Technology | Year: 2010

The communication of meaning as distinct from (Shannon-type) information is central to Luhmann's social systems theory and Giddens' structuration theory of action. These theories share an emphasis on reflexivity, but focus on meaning along a divide between interhuman communication and intentful action as two different systems of reference. Recombining these two theories into a theory about the structuration of expectations, interactions, organization, and self-organization of intentional communications can be simulated based on algorithms from the computation of anticipatory systems. The self-organizing and organizing layers remain rooted in the double contingency of the human encounter, which provides the variation. Organization and selforganization of communication are reflexive upon and therefore reconstructive of each other. Using mutual information in three dimensions, the imprint of meaning processing in the modeling system on the historical organization of uncertainty in the modeled system can be measured. This is shown empirically in the case of intellectual organization as "structurating" structure in the textual domain of scientific articles. © 2010 ASIS&T. Source


BACKGROUND: Artemisinin combination therapy (ACT) is recommended as first-line treatment for uncomplicated Plasmodium falciparum malaria, whereas chloroquine is still commonly used for the treatment of non-falciparum species (Plasmodium vivax, Plasmodium ovale and Plasmodium malariae). A more simplified, more uniform treatment approach across all malaria species is worthwhile to be considered both in endemic areas and for malaria as an imported condition alike.METHODS: A PROSPERO-registered systematic review to determine the efficacy and safety of ACT for the treatment of non-falciparum malaria was conducted, following PRISMA guidelines. Without language restrictions, Medline/PubMed, Embase, Cochrane Central Register of Controlled Trials, Web of Science, LILACS, Biosis Previews and the African Index Medicus were searched for studies published up to November 2014.RESULTS: The literature search identified 986 reports; 40 publications were found eligible for inclusion, all of them on non-falciparum malaria in endemic areas. Most evidence was available for P. vivax (n = 35). Five clinical trials in total were identified evaluating ACT for P. ovale, P. malariae and Plasmodium knowlesi. Most ACT presentations have high efficacy against P. vivax parasites; artemisinin-based combinations have shorter parasite and fever clearance times compared to chloroquine. ACT is as effective as chloroquine in preventing recurrent parasitaemia before day 28. Artemisinin-based combinations with long half-lives show significantly fewer recurrent parasitaemia up to day 63. The limited evidence available supports both the use of chloroquine and an ACT for P. ovale and P. malariae. ACT seems to be preferable for optimal treatment of P. knowlesi.CONCLUSION: ACT is at least equivalent to chloroquine in effectively treating non-falciparum malaria. These findings may facilitate development of simplified protocols for treating all forms of malaria with ACT, including returning travellers. Obtaining comprehensive efficacy and safety data on ACT use for non-falciparum species particularly for P. ovale, P. malariae and P. knowlesi should be a research priority.TRIAL REGISTRATION: CRD42014009103. Source


Dermauw W.,Ghent University | Van Leeuwen T.,Ghent University | Van Leeuwen T.,University of Amsterdam
Insect Biochemistry and Molecular Biology | Year: 2014

About a 100 years ago, the Drosophila white mutant marked the birth of Drosophila genetics. The white gene turned out to encode the first well studied ABC transporter in arthropods. The ABC gene family is now recognized as one of the largest transporter families in all kingdoms of life. The majority of ABC proteins function as primary-active transporters that bind and hydrolyze ATP while transporting a large diversity of substrates across lipid membranes. Although extremely well studied in vertebrates for their role in drug resistance, less is known about the role of this family in the transport of endogenous and exogenous substances in arthropods. The ABC families of five insect species, a crustacean and a chelicerate have been annotated in some detail. We conducted a thorough phylogenetic analysis of the seven arthropod and human ABC protein subfamilies, to infer orthologous relationships that might suggest conserved function. Most orthologous relationships were found in the ABCB half transporter, ABCD, ABCE and ABCF subfamilies, but specific expansions within species and lineages are frequently observed and discussed. We next surveyed the role of ABC transporters in the transport of xenobiotics/plant allelochemicals and their involvement in insecticide resistance. The involvement of ABC transporters in xenobiotic resistance in arthropods is historically not well documented, but an increasing number of studies using unbiased differential gene expression analysis now points to their importance. We give an overview of methods that can be used to link ABC transporters to resistance. ABC proteins have also recently been implicated in the mode of action and resistance to Bt toxins in Lepidoptera. Given the enormous interest in Bt toxicology in transgenic crops, such findings will provide an impetus to further reveal the role of ABC transporters in arthropods. © 2014 The Authors. Source


Voorveld H.A.M.,University of Amsterdam
Computers in Human Behavior | Year: 2011

Research on the effectiveness of cross-media campaigns has shown that combining online advertising with advertising in offline media can result in more positive consumer responses than using only one medium. However, when using computers, people increasingly engage in more than one media activity at a time (i.e. media multitasking), which might influence how consumers respond to advertisements they encounter in these media. Therefore, this paper investigates advertising effects during media multitasking. More specifically, the paper gives insight into the effectiveness of simultaneous exposure to online and radio advertising, because simultaneously surfing the internet and listening to the radio is a common media multitasking combination. Results of an experimental study with 111 participants showed that combining online and radio advertising resulted in more positive affective and behavioral responses than using only one medium. However, media multitasking seemed to have a negative influence on the recall and recognition of auditory information as combining media did not result in superior cognitive responses compared to using online ads alone. © 2011 Elsevier Ltd. All rights reserved. Source


Davin J.-C.,University of Amsterdam | Coppo R.,University of Turin
Nature Reviews Nephrology | Year: 2014

Henoch-Schönlein purpura (HSP) is the most common vasculitis in children, in whom prognosis is mostly dependent upon the severity of renal involvement. Nephritis is observed in about 30% of children with HSP. Renal damage eventually leads to chronic kidney disease in up to 20% of children with HSP nephritis in tertiary care centres, but in less than 5% of unselected patients with HSP, by 20 years after diagnosis. HSP nephritis and IgA nephropathy are related diseases resulting from glomerular deposition of aberrantly glycosylated IgA1. Although both nephritides present with similar histological findings and IgA abnormalities, they display pathophysiological differences with important therapeutic implications. HSP nephritis is mainly characterized by acute episodes of glomerular inflammation with endocapillary and mesangial proliferation, fibrin deposits and epithelial crescents that can heal spontaneously or lead to chronic lesions. By contrast, IgA nephropathy normally presents with slowly progressive mesangial lesions resulting from continuous low-grade deposition of macromolecular IgA1. This Review highlights the variable evolution of similar clinical and histological presentations among paediatric patients with HSP nephritis, which constitutes a challenge for their management, and discusses the treatment of these patients in light of current guidelines based on clinical evidence from adults with IgA nephropathy. © 2014 Macmillan Publishers Limited. All rights reserved. Source


Estimating the risk for recidivism is important for many areas of the criminal justice system. In the present study, the Youth Actuarial Risk Assessment Tool (Y-ARAT) was developed for juvenile offenders based solely on police records, with the aim to estimate the risk of general recidivism among large groups of juvenile offenders by police officers without clinical expertise. On the basis of the Y-ARAT, juvenile offenders are classified into five risk groups based on (combinations of) 10 variables including different types of incidents in which the juvenile was a suspect, total number of incidents in which the juvenile was a suspect, total number of other incidents, total number of incidents in which co-occupants at the youth's address were suspects, gender, and age at first incident. The Y-ARAT was developed on a sample of 2,501 juvenile offenders and validated on another sample of 2,499 juvenile offenders, showing moderate predictive accuracy (area under the receiver-operating-characteristic curve =.73), with little variation between the construction and validation sample. The predictive accuracy of the Y-ARAT was considered sufficient to justify its use as a screening instrument for the police. © The Author(s) 2013. Source


Bovine NADH:ubiquinone oxidoreductase (Complex I) is the first complex in the mitochondrial respiratory chain. It has long been assumed that it contained only one FMN group. However, as demonstrated in 2003, the intact enzyme contains two FMN groups. The second FMN was proposed to be located in a conserved flavodoxin fold predicted to be present in the PSST subunit. The long-known reaction of Complex I with NADPH differs in many aspects from that with NADH. It was proposed that the second flavin group was specifically involved in the reaction with NADPH. The X-ray structure of the hydrophilic domain of Complex I from Thermus thermophilus (Sazanov and Hinchliffe 2006, Science 311, 1430-1436) disclosed the positions of all redox groups of that enzyme and of the subunits holding them. The PSST subunit indeed contains the predicted flavodoxin fold although it did not contain FMN. Inspired by this structure, the present paper describes a re-evaluation of the enigmatic reactions of the bovine enzyme with NADPH. Published data, as well as new freeze-quench kinetic data presented here, are incompatible with the general opinion that NADPH and NADH react at the same site. Instead, it is proposed that these pyridine nucleotides react at opposite ends of the 90Å long chain of prosthetic groups in Complex I. Ubiquinone is proposed to react with the Fe-S clusters in the TYKY subunit deep inside the hydrophilic domain. A new model for electron transfer in Complex I is proposed. In the accompanying paper this model is compared with the one advocated in current literature. © 2010 The Author(s). Source


Forceville C.,University of Amsterdam
Journal of Pragmatics | Year: 2011

Speed lines, movement lines and emotion-enhancing flourishes (" pictorial runes" ) may contribute, marginally or substantially, to the potential meanings to be inferred from a comic's panel. It seems plausible that pictorial runes convey their meanings in patterned ways, but hitherto little systematic research appears to have been done to investigate them. The primary aim of this paper is to present the first version of a model to research pictorial runes by inventorying and categorizing all specimens occurring in a single Tintin album and to generalize tentatively about their meaning. In this manner, the model can be further tested, refined, elaborated, or refuted, in further research. Such research will aid both comics scholarship and cognition studies based on visual stimuli. © 2010 Elsevier B.V. Source


Post I.C.,University of Amsterdam
Annals of biomedical engineering | Year: 2012

Intra-organ flow is the most critical parameter in machine-perfused organ preservation systems (MPS). Ultrasonic flow sensors (UFS) are commonly employed in MPS. However, UFS are sensitive to changes in fluid composition and temperature and require recalibration. Novel Coriolis-type mass flow sensors (CFS) may be more suitable for MPS because the measurement technique is not amenable to these factors. The effect of viscosity, colloids, temperature, pressure, and preservation solution on flow measurement accuracy of UFS and CFS was therefore investigated. A CFS-based MPS was built and validated for setpoint stability using porcine kidneys and the ability to reproduce different pressure and flow waveforms. The UFS exhibited a temperature- and preservation solution-dependent overestimation of flow rate compared to the CFS. The CFS deviated minimally from the actual flow rate and did not require recalibration. The CFS-based MPS conformed to the preprogrammed temperature, flow, pressure, and vascular resistance settings during 6-h kidney preservation. The system was also able to accurately reproduce different pressure and flow waveforms. Conclusively, CFS-based MPS are more suitable for organ preservation than UFS-based MPS. Our CFS-based MPS provides a versatile yet robust experimental platform for testing and validating different types of clinical and experimental MPS. Source


Liebrand T.W.H.,Wageningen University | Liebrand T.W.H.,Center for Biosystems Genomics | van den Burg H.A.,University of Amsterdam | Joosten M.H.A.J.,Wageningen University | Joosten M.H.A.J.,Center for Biosystems Genomics
Trends in Plant Science | Year: 2014

Leucine-rich repeat-receptor-like proteins (LRR-RLPs) are ubiquitous cell surface receptors lacking a cytoplasmic signalling domain. For most of these LRR-RLPs, it remained enigmatic how they activate cellular responses upon ligand perception. Recently, the LRR-receptor-like kinase (LRR-RLK) SUPPRESSOR OF BIR1-1 (SOBIR1) was shown to be essential for triggering defence responses by certain LRR-RLPs that act as immune receptors. In addition to SOBIR1, the regulatory LRR-RLK BRI1-ASSOCIATED KINASE-1 (BAK1) is also required for LRR-RLP function. Here, we compare the roles of SOBIR1 and BAK1 as regulatory LRR-RLKs in immunity and development. BAK1 has a general regulatory role in plasma membrane-associated receptor complexes comprising LRR-RLPs and/or LRR-RLKs. By contrast, SOBIR1 appears to be specifically required for the function of receptor complexes containing LRR-RLPs. © 2013 Elsevier Ltd. Source


Hol E.M.,University Utrecht | Hol E.M.,An institute of the Royal Netherlands Academy of Arts and science | Hol E.M.,University of Amsterdam | Pekny M.,Gothenburg University | And 2 more authors.
Current Opinion in Cell Biology | Year: 2015

Glial fibrillary acidic protein (GFAP) is the hallmark intermediate filament (IF; also known as nanofilament) protein in astrocytes, a main type of glial cells in the central nervous system (CNS). Astrocytes have a range of control and homeostatic functions in health and disease. Astrocytes assume a reactive phenotype in acute CNS trauma, ischemia, and in neurodegenerative diseases. This coincides with an upregulation and rearrangement of the IFs, which form a highly complex system composed of GFAP (10 isoforms), vimentin, synemin, and nestin. We begin to unravel the function of the IF system of astrocytes and in this review we discuss its role as an important crisis-command center coordinating cell responses in situations connected to cellular stress, which is a central component of many neurological diseases. © 2015 Elsevier Ltd. Source


Michel M.C.,University of Amsterdam
Neurourology and urodynamics | Year: 2011

While complex symptom scales are important research tools, simpler, preferably single item scales may be more useful for routine clinical practise in the evaluation of patients with overactive bladder syndrome (OAB). This study aimed to compare multiple single-item scales at baseline and after treatment with patient-reported overall rating of treatment efficacy. In a pre-planned secondary analysis of a previously reported observational study, 4,450 patients were evaluated at baseline and after 12 weeks open-label treatment with solifenacin. Apart from episode counting for classical OAB symptoms, the following single-item rating scales were applied: Indevus Urgency Severity Scale, Urgency Perception Scale, a Visual Analog Scale (VAS), quality of life question of the IPSS, and general health and bladder problem questions of the King's Health Questionnaire (KHQ). At baseline OAB symptoms correlated at best moderately with each (r=0.285-0.508) other or with any of the rating scales (r=0.060-0.399). Pair-wise correlations between treatment-associated symptom or scale improvements tended to be tighter (r=0.225-0.588). When compared to patient-reported efficacy, the VAS (r=0.487) and the bladder problem question of the KHQ (r=0.452) showed the tightest correlation, whereas all symptom and rating scale improvements exhibited poor correlation with patient-reported tolerability (r≤0.283). The VAS and the bladder problem question of the KHQ show the greatest promise as single-item scales to assess problem intensity in OAB patients. Copyright © 2011 Wiley-Liss, Inc. Source


Hek G.,University of Amsterdam
Journal of Mathematical Biology | Year: 2010

Geometric singular perturbation theory is a useful tool in the analysis of problems with a clear separation in time scales. It uses invariant manifolds in phase space in order to understand the global structure of the phase space or to construct orbits with desired properties. This paper explains and explores geometric singular perturbation theory and its use in (biological) practice. The three main theorems due to Fenichel are the fundamental tools in the analysis, so the strategy is to state these theorems and explain their significance and applications. The theory is illustrated by many examples. © The Author(s) 2009. Source


Kontopodis M.,University of Amsterdam
Sport, Education and Society | Year: 2013

This study moves in the space between two fields: science and technology studies (STS) and childhood studies; it thus belongs to the broader STS literature that investigates everyday practices outside the laboratory. The interpretation of ethnographic and bibliographic data on contemporary cardiovascular and obesity prevention in German kindergartens makes evident that when knowledge travels from biomedical laboratories to the preschool, then psychology comes into play! Bodies of knowledge such as behavioural or cognitive theories shape prevention and intervention practices, which could be seen as originally resulting from biomedical findings and trends. Accompanying this development is a change in the primary sciences that deal with childhood: these are no longer pedagogy or developmental and educational psychology (at least in their traditional forms), but 'developmental science'. All this shapes contemporary childhood in quite normative ways. It thus remains an open question what non- or less normative institutional practices and bodies of knowledge could look like. © 2013 Copyright Taylor and Francis Group, LLC. Source


Mutual information among three or more dimensions (μ* = -Q) has been considered as interaction information. However, Krippendorff [1,2] has shown that this measure cannot be interpreted as a unique property of the interactions and has proposed an alternative measure of interaction information based on iterative approximation of maximum entropies. Q can then be considered as a measure of the difference between interaction information and redundancy generated in a model entertained by an observer. I argue that this provides us with a measure of the imprint of a second-order observing system-a model entertained by the system itself-on the underlying information processing. The second-order system communicates meaning hyper-incursively; an observation instantiates this meaning-processing within the information processing. The net results may add to or reduce the prevailing uncertainty. The model is tested empirically for the case where textual organization can be expected to contain intellectual organization in terms of distributions of title words, author names, and cited references. © 2010 by the authors; licensee Molecular Diversity Preservation International, Basel, Switzerland. Source


Wijnands R.,University of Amsterdam | Degenaar N.,University of Michigan
Monthly Notices of the Royal Astronomical Society | Year: 2013

We report on a series of Swift/X-ray telescope observations, performed between 2012 February and 22 March, during the quiescent state of the neutron-star X-ray binary SAX J1750.8-2900. In these observations, the source was either just detected or undetected, depending on the exposure length (which ranged from ~0.3 to ~3.8 ks). The upper limits for the non-detections were consistent with the detected luminosities (when fitting a thermal model to the spectrum) of ~1034 erg s-1 (0.5-10 keV). This level is consistent with what has been measured previously for this source in quiescence. However, on March 17 the source was found to have an order of magnitude larger count rate. When fitting the flare spectrum with an absorbed power-law model, we obtained a flare luminosity of (3-4) × 1034 erg s-1 (0.5-10 keV). Follow-up Swift observations showed that this flare lasted <16 d. This event was very likely due to a brief episode of low-level accretion on to the neutron star and provides further evidence that the quiescent state of neutron-star X-ray transients might not be as quiet as is generally assumed. The detection of this low-level accretion flare raises the question whether the quiescent emission of the source (outside the flare) could also be due to residual accretion, albeit continuous instead of episodic. However, we provide arguments which would suggest that the lowest intensity level might instead represent the cooling of the accretion-heated neutron star. ©2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Source


Decowski M.P.,University of Amsterdam
Nuclear Physics B | Year: 2016

The KamLAND experiment started operation in the Spring of 2002 and is operational to this day. The experiment observes signals from electron antineutrinos from distant nuclear reactors. The program, spanning more than a decade, allowed the determination of LMA-MSW as the solution to the solar neutrino transformation results (under the assumption of CPT invariance) and the measurement of various neutrino oscillation parameters. In particular, the solar mass-splitting δm212 was determined to high precision. Besides the study of neutrino oscillation, KamLAND started the investigation of geologically produced antineutrinos (geo-ν[U+203E]e). The collaboration also reported on a variety of other topics related to particle and astroparticle physics. © 2016. Source


Kalmijn M.,University of Amsterdam
Journals of Gerontology - Series B Psychological Sciences and Social Sciences | Year: 2013

Objectives. Using a within-family perspective, we examine how mothers allocate support among their adult children, and we test alternative theories about support exchange.Method. We use a large-scale multiactor survey from the Netherlands in which mothers and children were interviewed independently. We analyze sibling pairs (aged 36 on average) who were connected to 604 mothers (aged 63 on average). Fixed effects regression models and instrumental variable models are used to examine effects of child characteristics on received support.Results. Mothers give more support to the child who lives without a partner, has children, has health problems, and is lower educated than to the child who does not have these characteristics. Children who more strongly support filial norms also receive more support. Support given to one child has a small positive effect on the support that the mother gives to the other child.Discussion. The analyses provide new and supportive evidence for the notion that parents are altruistically motivated. At the same time, older parents are motivated by exchange because they invest more in children who are more likely to reciprocate. Some evidence exists for the norm of equality. © 2012 The Author. Source


Eftimov F.,University of Amsterdam
The Cochrane database of systematic reviews | Year: 2013

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) causes progressive or relapsing weakness and numbness of the limbs, developing over at least two months. Uncontrolled studies suggest that intravenous immunoglobulin (IVIg) helps. This review was first published in 2002 and has since been updated, most recently in 2013. To review systematically the evidence from randomised controlled trials (RCTs) concerning the efficacy and safety of IVIg in CIDP. On 4 December 2012, we searched the Cochrane Neuromuscular Disease Group Specialized Register, CENTRAL (2012, issue 11 in the Cochrane Library), MEDLINE and EMBASE to December 2012 and ISI from January 1985 to May 2008. We searched for ongoing trials through two metaRegistries (World Health Organization International Clinical Trials Registry Platform Search Portal and Current Controlled Trials). We selected RCTs testing any dose of IVIg versus placebo, plasma exchange or corticosteroids in definite or probable CIDP. Two authors reviewed literature searches to identify potentially relevant RCTs, scored their quality and extracted data independently. We contacted authors for additional information. We considered eight RCTs, including 332 participants, to be eligible for inclusion in the review. These trials were homogeneous and the overall risk of bias low. Five studies, in a total of 235 participants compared IVIg against placebo. One trial with 20 participants compared IVIg with plasma exchange, one trial compared IVIg with prednisolone in 32 participants, and one trial, newly included at this update, compared IVIg with intravenous methylprednisolone in 46 participants.A significantly higher proportion of participants improved in disability within one month after IVIg treatment as compared with placebo (risk ratio (RR) 2.40, 95% confidence interval (CI) 1.72 to 3.36; number needed to treat for an additional beneficial outcome 3.03 (95% CI 2.33 to 4.55), high quality evidence). Whether all these improvements are equally clinically relevant cannot be deduced from this analysis because each trial used different disability scales and definitions of significant improvement. In three trials, including 84 participants, the disability score could be transformed to the modified Rankin score, on which improvement of one point after IVIg treatment compared to placebo was barely significant (RR 2.40, 95% CI 0.98 to 5.83) (moderate quality evidence). Only one placebo-controlled study included in this review had a long-term follow-up. The results of this study suggest that IVIg improves disability more than placebo over 24 and 48 weeks.The mean disability score revealed no significant difference between IVIg and plasma exchange at six weeks (moderate quality evidence). There was no significant difference in improvement in disability on prednisolone compared with IVIg after two or six weeks, or on methylprednisolone compared to IVIg after two weeks or six months (moderate quality evidence).There were no statistically significant differences in frequencies of side effects between the three types of treatment for which data were available (IVg versus placebo or steroids). (moderate or high quality evidence) Mild and transient adverse events were found in 49% of participants treated with IVIg, while serious adverse events were found in six per cent. The evidence from RCTs shows that IVIg improves disability for at least two to six weeks compared with placebo, with an NNTB of three. During this period it has similar efficacy to plasma exchange, oral prednisolone and intravenous methylprednisolone. In one large trial, the benefit of IVIg persisted for 24 and possibly 48 weeks. Further research is needed to compare the long-term benefits as well as side effects of IVIg with other treatments. Source


Wiersinga W.M.,University of Amsterdam
Best Practice and Research: Clinical Endocrinology and Metabolism | Year: 2012

General health-related quality-of-life (QoL) questionnaires (MOS SF-24 and SF-36) and the more sensitive disease-specific QoL questionnaire (GO-QoL) both indicate substantial impairment of quality of life in patients with Graves' ophthalmopathy (GO). The GO-QoL contains 8 questions on visual functioning and 8 questions on appearance; answers on each subscale are transformed to scores ranging from 0 (worst) to 100 (best). The minimal clinically important difference in scores is ≥10 points for invasive therapies, but a change of 6 points on one of both subscales is already perceived by patients as beneficial and associated with an important change in daily functioning. The GO-QoL is well validated, widely used, and available in eight languages. The GO-QoL is recommended as an independent primary outcome measure in randomized clinical trials. Incorporating the GO-QoL in the routine assessment of GO in daily clinical practice is also recommended: although unproven, it is likely to improve the quality of care by identifying patients who are in need for psychological support in order to address poor psychosocial functioning and low self-esteem. © 2011 Elsevier Ltd. All rights reserved. Source


Bus S.A.,University of Amsterdam
Diabetes/Metabolism Research and Reviews | Year: 2012

Biomechanical factors play an important role in diabetic foot disease. Reducing high foot pressures (i.e. offloading) is one of the main goals in healing and preventing foot ulceration. Evidence-based guidelines show the strong association between the efficacy to offload the foot and clinical outcome. However, several aspects related to offloading are underexposed. First, in the management of foot complications, offloading is mostly studied as a single entity, whereas it should be analysed in a broader perspective of contributing factors to better predict clinical outcome. This includes assessment of patient behavioural factors such as type and intensity of daily physical activity and adherence to prescribed treatment. Second, a large gap exists between evidence-based recommendations and clinical practice in the use of offloading for ulcer treatment, and this gap needs to be bridged. Possible ways to achieve this are discussed in this article. Third, our knowledge about the efficacy and role of offloading in treating complicated and non-plantar neuropathic foot ulcers needs to be expanded because these ulcers currently dominate presentation in multidisciplinary foot practice. Finally, foot ulcer prevention is underexposed when compared with ulcer treatment. Prevention requires a larger focus, in particular regarding the efficacy of therapeutic footwear and its relative role in comparison with other preventative strategies. These priorities need the attention of clinicians, scientists and professional societies to improve our understanding of offloading and to improve clinical outcome in the management of the diabetic foot. © 2012 John Wiley & Sons, Ltd. Source


Hoogendijk M.G.,University of Amsterdam
Frontiers in Physiology | Year: 2012

Arrhythmogenic right ventricular cardiomyopathy (ARVC) and Brugada syndrome are distinct clinical entities which diagnostic criteria exclude their coexistence in individual patients. ARVC is a myocardial disorder characterized by fibro-fatty replacement of the myocardium and ventricular arrhythmias. In contrast, the Brugada syndrome has long been considered a functional cardiac disorder: no gross structural abnormalities can be identified in the majority of patients and its electrocardiographic hallmark of coved-type ST-segment elevation in right precordial leads is dynamic. Nonetheless, a remarkable overlap in clinical features has been demonstrated between these conditions. This review focuses on this overlap and discusses its potential causes and consequences. © 2012 Hoogendijk. Source


Prins P.J.,University of Amsterdam
Cyberpsychology, behavior and social networking | Year: 2011

This study examined the benefits of adding game elements to standard computerized working memory (WM) training. Specifically, it examined whether game elements would enhance motivation and training performance of children with ADHD, and whether it would improve training efficacy. A total of 51 children with ADHD aged between 7 and 12 years were randomly assigned to WM training in a gaming format or to regular WM training that was not in a gaming format. Both groups completed three weekly sessions of WM training. Children using the game version of the WM training showed greater motivation (i.e., more time training), better training performance (i.e., more sequences reproduced and fewer errors), and better WM (i.e., higher scores on a WM task) at post-training than children using the regular WM training. Results are discussed in terms of executive functions and reinforcement models of ADHD. It is concluded that WM training with game elements significantly improves the motivation, training performance, and working memory of children with ADHD. The findings of this study are encouraging and may have wide-reaching practical implications in terms of the role of game elements in the design and implementation of new intervention efforts for children with ADHD. Source


De Groote M.L.,University of Groningen | Verschure P.J.,University of Amsterdam | Rots M.G.,University of Groningen
Nucleic Acids Research | Year: 2012

Despite significant advances made in epigenetic research in recent decades, many questions remain unresolved, especially concerning cause and consequence of epigenetic marks with respect to gene expression modulation (GEM). Technologies allowing the targeting of epigenetic enzymes to predetermined DNA sequences are uniquely suited to answer such questions and could provide potent (bio)medical tools. Toward the goal of gene-specific GEM by overwriting epigenetic marks (Epigenetic Editing, EGE), instructive epigenetic marks need to be identified and their writers/erasers should then be fused to gene-specific DNA binding domains. The appropriate epigenetic mark(s) to change in order to efficiently modulate gene expression might have to be validated for any given chromatin context and should be (mitotically) stable. Various insights in such issues have been obtained by sequence-specific targeting of epigenetic enzymes, as is presented in this review. Features of such studies provide critical aspects for further improving EGE. An example of this is the direct effect of the edited mark versus the indirect effect of recruited secondary proteins by targeting epigenetic enzymes (or their domains). Proof-of-concept of expression modulation of an endogenous target gene is emerging from the few EGE studies reported. Apart from its promise in correcting disease-associated epi-mutations, EGE represents a powerful tool to address fundamental epigenetic questions. © 2012 The Author(s). Source


Cryopreservation of oocytes or embryos preceded by controlled ovarian stimulation (COS) can increase the chance of future pregnancy in women with breast cancer who risk therapy-induced ovarian failure. In women with estrogen-receptor (ER) positive breast cancer, alternative COS protocols with tamoxifen or letrozole are being used to theoretically inhibit breast cancer growth during COS. To assess the effects of tamoxifen or letrozole, in addition to standard COS protocols, on the breast cancer-free interval in premenopausal women with ER positive breast cancer who undergo COS for embryo or oocyte cryopreservation. We searched the Ovid Cochrane Central Register of Controlled Trials (CENTRAL), Ovid MEDLINE, Ovid EMBASE, Ovid PsycINFO, and EBSCOhost CINAHL. We applied no limitations in year of publication or language. In addition, we searched trial registers for ongoing and registered trials, conference abstracts, and sources of grey literature. The search was conducted in January 2013. Randomised trials comparing different COS protocols in women with breast cancer were eligible for inclusion. Two review authors independently scanned the titles, abstracts, or both sections according to Cochrane guidelines. If data to include were provided, data extraction would have been independently performed by two review authors by using forms designed according to Cochrane guidelines. No randomised controlled trials were found that met the inclusion criteria. COS schedules with the additional use of tamoxifen or letrozole are commonly chosen as an alternative regimen in young women with ER positive breast cancer who undergo COS for oocyte or embryo cryopreservation. No randomised controlled trials support the idea that these alternative COS schedules are superior to standard COS. Source


Ubbink D.T.,University of Amsterdam
Cochrane database of systematic reviews (Online) | Year: 2013

Patients suffering from inoperable chronic critical leg ischaemia (NR-CCLI) face amputation of the leg. Spinal cord stimulation (SCS) has been proposed as a helpful treatment in addition to standard conservative treatment. To find evidence for an improvement on limb salvage, pain relief, and the clinical situation using SCS compared to conservative treatment alone. For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched January 2013) and CENTRAL (2012, Issue 12). Controlled studies comparing the addition of SCS with any form of conservative treatment to conservative treatment alone in patients with NR-CCLI. Both authors independently assessed the quality of the studies and extracted data. Six studies comprising nearly 450 patients were included. In general the quality of the studies was good. No study was blinded due to the type of intervention.Limb salvage after 12 months was significantly higher in the SCS group (risk ratio (RR) 0.71, 95% confidence interval (CI) 0.56 to 0.90; risk difference (RD) -0.11, 95% CI -0.20 to -0.02). Significant pain relief occurred in both treatment groups, but was more prominent in the SCS group where the patients required significantly less analgesics. In the SCS group, significantly more patients reached Fontaine stage II than in the conservative group (RR 4.9, 95% CI 2.0 to 11.9; RD 0.33, 95% CI 0.19 to 0.47). Overall, no significantly different effect on ulcer healing was observed with the two treatments.Complications of SCS treatment consisted of implantation problems (9%, 95% CI 4 to 15%) and changes in stimulation requiring re-intervention (15%, 95% CI 10 to 20%). Infections of the lead or pulse generator pocket occurred less frequently (3%, 95% CI 0 to 6%). Overall risk of complications with additional SCS treatment was 17% (95% CI 12 to 22%), indicating a number needed to harm of 6 (95% CI 5 to 8).Average overall costs (one study) at two years were EUR 36,500 (SCS group) and EUR 28,600 (conservative group). The difference (EUR 7900) was significant (P < 0.009). There is evidence to favour SCS over standard conservative treatment alone to improve limb salvage and clinical situations in patients with NR-CCLI. The benefits of SCS must be considered against the possible harm of relatively mild complications and the costs. Source


Spronk R.,University of Amsterdam
Culture, Health and Sexuality | Year: 2014

In this paper, I reflect on the notion of 'African men' as it is employed in global health scholarship and disentangle the way the idea is used as a generative concept. I explore how this notion circulates and gets modified, adapted and reproduced by scholars, on the one hand, and by various groups of men in Africa, on the other. I argue that the use of the idea of African men as an a priori category in scholarly imagination and practice presents us with stereotypes that impede much research. I then briefly connect with what has been analysed as the hegemonic discourse on Africa as the paradigm of difference, and the history of local modes of self-presentation as Africans. In Kenya, among both men and women, the use of the phrase African men as a natural category of sexual agents has been used to explain or justify men's multiple sexual relations. Yet if we look more closely at men's experiences, it becomes clear how men are caught up in conflicting discourses of masculinity. I conclude that we need to analyse gender as a performative quality that is both constructed and meaningful. © 2014 © 2014 Taylor & Francis. Source


Tytgat G.N.J.,University of Amsterdam
Digestive Diseases | Year: 2011

Ulceration corresponds to tissue loss, breaching the muscularis mucosae. When ulcers develop in the acid-peptic environment of the gastroduodenum, they are traditionally called peptic ulcer (PUD). Ulcers never develop spontaneously in a healthy gastroduodenal mucosa. Ulceration is the ultimate consequence of a disequilibrium between aggressive injurious factors and defensive mucosa-protective factors. The dominant aggressors are strong acid and high proteolytic (pepsin) activity in gastric secretions. The dominant defensors are the phospholipid surfactant layer, covering the mucus bicarbonate gel, the mucus bicarbonate layer covering the epithelium, the tight junctional structures between the epithelial cells, restricting proton permeability, and the epithelial trefoil peptides, contributing to healing after injury. Initially, acid-peptic aggression was considered the overwhelming cause of PUD, supported by the pioneering work of Schwartz, launching the dictum 'no acid, no ulcer'. This led to the universal therapy directed against intragastric acidity, also interfering with peptic activity when the pH was >4. The therapeutic sequence went from large doses of antacids to H 2-receptor antagonists and finally to proton pump inhibitors (PPIs). The longer the intragastric pH was >3, the quicker ulcer healing was seen. Unfortunately, ulcers often recurred after stopping therapy, demanding maintenance therapy to keep the ulcers healed and to prevent the need for surgery (vagotomy, partial gastric resection). Later on, the emphasis gradually shifted to weakening/failing of the defensive factors, raising the vulnerability of the gastroduodenal mucosa to luminal secretions. Leading injurious mechanisms jeopardizing the mucosal integrity are numerous: infections, especially Helicobacter pylori, drug-induced injury, particularly acetylsalicylic acid (ASA) and non-steroidal anti-inflammatory drugs (NSAIDs), physicochemical and caustic injury, vascular disorders, interfering with perfusion, etc. Currently the leading cause of PUD is H. pylori infection. Standard triple eradication therapy is losing interest in favor of quadruple therapy (PPI, bismuth, tetracycline, metronidazole). H. pylori-induced PPI is rapidly disappearing in the Western world, in contrast to drug-induced ulcer disease and what is called idiopathic PUD. Partial prophylaxis of ASA/NSAID-induced ulceration is possible with PPI maintenance therapy, but novel ways to strengthen the mucosal defense are urgently awaited. Copyright © 2011 S. Karger AG, Basel. Source


Strahl H.,Newcastle University | Burmann F.,Max Planck Institute of Biochemistry | Hamoen L.W.,Newcastle University | Hamoen L.W.,University of Amsterdam
Nature Communications | Year: 2014

The eukaryotic cortical actin cytoskeleton creates specific lipid domains, including lipid rafts, which determine the distribution of many membrane proteins. Here we show that the bacterial actin homologue MreB displays a comparable activity. MreB forms membrane-associated filaments that coordinate bacterial cell wall synthesis. We noticed that the MreB cytoskeleton influences fluorescent staining of the cytoplasmic membrane. Detailed analyses combining an array of mutants, using specific lipid staining techniques and spectroscopic methods, revealed that MreB filaments create specific membrane regions with increased fluidity (RIFs). Interference with these fluid lipid domains (RIFs) perturbs overall lipid homeostasis and affects membrane protein localization. The influence of MreB on membrane organization and fluidity may explain why the active movement of MreB stimulates membrane protein diffusion. These novel MreB activities add additional complexity to bacterial cell membrane organization and have implications for many membrane-associated processes. © 2014 Macmillan Publishers Limited. All rights reserved. Source


Van Veelen M.,University of Amsterdam
Journal of Theoretical Biology | Year: 2011

This is a reply to "Queller's rule ok: Comment on van Veelen 'when inclusive fitness is right and when it can be wrong' "by James Marshall in the Journal of Theoretical Biology, in this issue.In order to circumvent the disagreement about the Price equation and focus on the issue of the predictive power of inclusive fitness for group selection models, I derive Queller's and Marshall's rule without the Price equation. Both rules however need a translation step in order to be able to link them to the group selection model in van Veelen (2009). Queller's rule applies to games with 2 players and 2 strategies, and is general. Marshall's rule on the other hand applies only to a small subset of 3-player games. His rule is correct, but for other, similarly small subsets we would get other rules. This implies that if we want a rule that applies to all symmetric games with 3 players and 2 strategies, it will have to use a vector of dimension 2 that represents population structure. More in general: for group selection models with groups of size n, a correct and general prediction will need to use a vector of dimension n-1 that represents population structure. © 2010 Elsevier Ltd. Source


Mathus-Vliegen E.M.H.,University of Amsterdam
Best Practice and Research: Clinical Gastroenterology | Year: 2014

The results of lifestyle interventions and pharmacotherapy are disappointing in severe obesity which is characterised by premature death and many obesity-associated co-morbidities. Only surgery may achieve significant and durable weight losses associated with increased life expectancy and improvement of comorbidities. Bariatric surgery involves the gastrointestinal tract and may therefore increase gastrointestinal complaints. Bariatric surgery may also result in complications which in many cases can be solved by endoscopic interventions. This requires a close cooperation between surgeons and endoscopists. This chapter will concentrate on the most commonly performed operations such as the Roux-en-Y gastric bypass, the adjustable gastric banding and the sleeve gastrectomy, in the majority of cases performed by laparoscopy. Operations such as the vertical banded gastroplasty and the biliopancreatic diversion with or without duodenal switch will not be discussed at length as patients with these operations will not be encountered frequently and their management can be found under the headings of the other operations. © 2014 Elsevier Ltd. All rights reserved. Source


Leydesdorff L.,University of Amsterdam | Ivanova I.A.,Far Eastern Federal University
Journal of the American Society for Information Science and Technology | Year: 2014

The study of interhuman communication requires a more complex framework than Claude E. Shannon's (1948) mathematical theory of communication because "information" is defined in the latter case as meaningless uncertainty. Assuming that meaning cannot be communicated, we extend Shannon's theory by defining mutual redundancy as a positional counterpart of the relational communication of information. Mutual redundancy indicates the surplusof meanings that canbeprovidedtothe exchangesin reflexive communications. The information is redundant because it is based on "pure sets" (i.e., without subtraction of mutual information in the overlaps). We show that in the three-dimensional case (e.g., of a triple helix of university-industry- government relations), mutual redundancy is equal to mutual information (R xyz = Txyz); but when the dimensionality is even, the sign is different. We generalize to the measurement in N dimensions and proceed to the interpretation. Using Niklas Luhmann's (1984-1995) social systems theory and/or Anthony Giddens's (1979, 1984) structuration theory, mutual redundancy can beprovided withan interpretation in the sociological case: Different meaningprocessing structures code and decode with other algorithms. A surplus of ("absent") options can then be generated that add to the redundancy. Luhmann's "functional (sub)systems" of expectations or Giddens's "ruleresource sets" are positioned mutually, but coupled operationally in events or "instantiated" in actions. Shannon-type information is generated by the mediation, but the "structures" are (re-)positioned toward one another as sets of (potentially counterfactual) expectations. The structural differences among the coding and decoding algorithms provide a source of additional options in reflexive and anticipatory communications. © 2013 ASIS&T. Source


Watts A.L.,University of Amsterdam
Annual Review of Astronomy and Astrophysics | Year: 2012

Burst oscillations, a phenomenon observed in a significant fraction of Type I (thermonuclear) X-ray bursts, involve the development of highly asymmetric brightness patches in the burning surface layers of accreting neutron stars. Intrinsically interesting as nuclear phenomena, they are also important as probes of dense matter physics and the strong gravity, high magnetic field environment of the neutron star surface. Burst oscillation frequency is also used to measure stellar spin, and doubles the sample of rapidly rotating (above 10 Hz) accreting neutron stars with known spins. Although the mechanism remains mysterious, burst oscillation models must take into account thermonuclear flame spread, nuclear processes, rapid rotation, and the dynamical role of the magnetic field. This review provides a comprehensive summary of the observational properties of burst oscillations, an assessment of the status of the theoretical models that are being developed to explain them, and an overview of how they can be used to constrain neutron star properties such as spin, mass, and radius. Copyright © 2012 by Annual Reviews. Source


Arina C.,University of Amsterdam | Mohapatra R.N.,University of Maryland University College | Sahu N.,Indian Institute of Technology Hyderabad
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2013

We discuss aspects of a scenario for co-genesis of matter and dark matter which extends the standard model by adding a fourth generation vector-like lepton doublet and show that if the fourth neutrino is a massive pseudo-Dirac fermion with mass in the few hundred GeV range and mass splitting of about 100 keV, its lighter component can be a viable inelastic dark matter candidate. Its relic abundance is produced by the CP violating out-of-equilibrium decay of the type-II seesaw scalar triplet, which also gives rise to the required baryon asymmetry of the Universe via type-II leptogenesis, thus providing a simultaneous explanation of dark matter and baryon abundance observed today. Moreover, the induced vacuum expectation value of the same scalar triplet is responsible for the sub-eV Majorana masses to the three active neutrinos. A stable fourth generation of neutrinos is elusive at collider, however might be detected by current dark matter direct search experiments. © 2013 Elsevier B.V. Source


Pinto Y.,University of Amsterdam
Journal of vision | Year: 2013

What is the relationship between top-down and bottom-up attention? Are both types of attention tightly interconnected, or are they independent? We investigated this by testing a large representative sample of the Dutch population on two attentional tasks: a visual search task gauging the efficiency of top-down attention and a singleton capture task gauging bottom-up attention. On both tasks we found typical performance--i.e., participants displayed a significant search slope on the search task and significant slowing caused by the unique, but irrelevant, object on the capture task. Moreover, the high levels of significance we observed indicate that the current set-up provided very high signal to noise ratios, and thus enough power to accurately unveil existing effects. Importantly, in this robust investigation we did not observe any correlation in performance between tasks. The use of Bayesian statistics strongly confirmed that performance on both tasks was uncorrelated. We argue that the current results suggest that there are two attentional systems that operate independently. We hypothesize that this may have implications beyond our understanding of attention. For instance, it may be that attention and consciousness are intertwined differently for top-down attention than for bottom-up attention. Source


Kringos D.S.,University of Amsterdam | Boerma W.,Netherlands Institute for Health Services Research | Van Der Zee J.,Maastricht University | Groenewegen P.,Netherlands Institute for Health Services Research
Health Affairs | Year: 2013

Strong primary care systems are often viewed as the bedrock of health care systems that provide high-quality care, but the evidence supporting this view is somewhat limited. We analyzed comparative primary care data collected in 2009-10 as part of a European Union-funded project, the Primary Health Care Activity Monitor for Europe. Our analysis showed that strong primary care was associated with better population health; lower rates of unnecessary hospitalizations; and relatively lower socioeconomic inequality, as measured by an indicator linking education levels to self-rated health. Overall health expenditures were higher in countries with stronger primary care structures, perhaps because maintaining strong primary care structures is costly and promotes developments such as decentralization of services delivery. Comprehensive primary care was also associated with slower growth in health care spending. More research is needed to explore these associations further, even as the evidence grows that strong primary care in Europe is conducive to reaching important health system goals. © 2013 Project HOPE-The People-to-People Health Foundation, Inc. Source


Ekstrand J.,Linkoping University | Van Dijk C.N.,University of Amsterdam
British Journal of Sports Medicine | Year: 2013

Background There is little information about Metatarsal Five (MT-5) fractures for specific sports. Objective To study the occurrence, the imaging characteristics, the lay-off times and healing problems of MT-5 fractures among male footballers. Methods Sixty-four European elite teams were monitored from 2001 to 2012. x-Rays were collected and classified by the Torg criteria. Results Of 13 754 injuries, 0.5% (67) proved to be MT-5 fractures. Their incidence was 0.04 injuries/1000 h of exposure. A team of 25 players might thus expect an MT-5 fracture every fifth season. Of these fractures, 67% (38) were primary and 33% were refractures. One of the 38 primary fractures was an avulsion of the tuberosity; all the others (97%) located towards the base. In total, 32% of the players with MT-5 fracture were younger than 21 years, 40% of the fractures occurred during the preseason and 45% of the players had prodromal symptoms. In total, 54% of the initial xrays were classified as Torg type II (stress fractures), and 46% were classified as Torg type I (acute type). After surgical treatment the fractures healed faster, compared with conservative treatment (75% vs 33%, p<0.05). There was no significant difference in lay-off days between players that had been operated, and those that had not (80 vs 74 days, p=0.67). Conclusions The majority of MT-5 fractures are stress fractures, and mainly occur among young players. There are frequent healing problems, which might be explained by the stress nature of the injury. After surgery there are less healing problems, compared with those in conservative treatment. Source


Vink J.,University of Amsterdam
Astronomy and Astrophysics Review | Year: 2012

Supernova remnants are beautiful astronomical objects that are also of high scientific interest, because they provide insights into supernova explosion mechanisms, and because they are the likely sources of Galactic cosmic rays. X-ray observations are an important means to study these objects. And in particular the advances made in X-ray imaging spectroscopy over the last two decades has greatly increased our knowledge about supernova remnants. It has made it possible to map the products of fresh nucleosynthesis, and resulted in the identification of regions near shock fronts that emit X-ray synchrotron radiation. Since X-ray synchrotron radiation requires 10-100 TeV electrons, which lose their energies rapidly, the study of X-ray synchrotron radiation has revealed those regions where active and rapid particle acceleration is taking place. In this text all the relevant aspects of X-ray emission from supernova remnants are reviewed and put into the context of supernova explosion properties and the physics and evolution of supernova remnants. The first half of this review has a more tutorial style and discusses the basics of supernova remnant physics and X-ray spectroscopy of the hot plasmas they contain. This includes hydrodynamics, shock heating, thermal conduction, radiation processes, non-equilibrium ionization, He-like ion triplet lines, and cosmic ray acceleration. The second half offers a review of the advances made in field of X-ray spectroscopy of supernova remnants during the last 15 year. This period coincides with the availability of X-ray imaging spectrometers. In addition, I discuss the results of high resolution X-ray spectroscopy with the Chandra and XMM-Newton gratings. Although these instruments are not ideal for studying extended sources, they nevertheless provided interesting results for a limited number of remnants. These results provide a glimpse of what may be achieved with future microcalorimeters that will be available on board future X-ray observatories. In discussing the results of the last 15 years I have chosen to discuss a few topics that are of particular interest. These include the properties of Type Ia supernova remnants, which appear to be regularly shaped and have stratified ejecta, in contrast to core collapse supernova remnants, which have patchy ejecta distributions. For core collapse supernova remnants I discuss the spatial distribution of fresh nucleosynthesis products, but also their properties in connection to the neutron stars they contain. For the mature supernova remnants I focus on the prototypal supernova remnants Vela and the Cygnus Loop. And I discuss the interesting class of mixed-morphology remnants. Many of these mature supernova remnants contain still plasma with enhanced ejecta abundances. Over the last five years it has also become clear that many mixed-morphology remnants contain plasma that is overionized. This is in contrast to most other supernova remnants, which contain underionized plasmas. This text ends with a review of X-ray synchrotron radiation from shock regions, which has made it clear that some form of magnetic-field amplification is operating near shocks, and is an indication of efficient cosmic-ray acceleration. © The Author(s) 2011. Source


De Jong J.T.V.M.,University of Amsterdam
Transcultural Psychiatry | Year: 2014

This article addresses four major challenges for efforts to create synergy between the global mental health movement and cultural psychiatry. First, although they appear to share domains of mutual interest, the worlds of global mental health and cultural psychiatry have distinct lineages. Expanding their horizons by learning from adjacent disciplines would be mutually beneficial. A second challenge concerns the conceptualization of a new classification system for mental health problems. Adopting a classification system that integrates new insights from socio-neurobiology and from a networks perspective could bring cultural psychiatry and global mental health closer and change the way each field addresses the mental health gap, which constitutes the third challenge. I summarize attempts to achieve comprehensive mental health coverage around the globe and question whether the strategies employed to achieve these goals have been successful, both in high- (HIC) and low- and middle-income countries (LMIC). In LMIC, the dominant strategy needs to be complemented by mobilization of other community resources including local practitioners. A fourth challenge is the lack of mathematical models to guide action and research and solve major preoccupations such as access to care or multi-level analyses in complex ecological or health systems. © The Author(s) 2014. Source


Caux J.-S.,University of Amsterdam | Essler F.H.L.,University of Oxford
Physical Review Letters | Year: 2013

We consider quantum quenches in integrable models. We argue that the behavior of local observables at late times after the quench is given by their expectation values with respect to a single representative Hamiltonian eigenstate. This can be viewed as a generalization of the eigenstate thermalization hypothesis to quantum integrable models. We present a method for constructing this representative state by means of a generalized thermodynamic Bethe ansatz (GTBA). Going further, we introduce a framework for calculating the time dependence of local observables as they evolve towards their stationary values. As an explicit example we consider quantum quenches in the transverse-field Ising chain and show that previously derived results are recovered efficiently within our framework. © 2013 American Physical Society. Source


Linn A.J.,University of Amsterdam
Journal of medical Internet research | Year: 2011

Since medication nonadherence is considered to be an important health risk, numerous interventions to improve adherence have been developed. During the past decade, the use of Internet-based interventions to improve medication adherence has increased rapidly. Internet interventions have the potential advantage of tailoring the interventions to the needs and situation of the patient. The main aim of this systematic review was to investigate which tailored Internet interventions are effective in improving medication adherence. We undertook comprehensive literature searches in PubMed, PsycINFO, EMBASE, CINAHL, and Communication Abstracts, following the guidelines of the Cochrane Collaboration. The methodological quality of the randomized controlled trials and clinical controlled trials and methods for measuring adherence were independently reviewed by two researchers. A total of 13 studies met the inclusion criteria. All included Internet interventions clearly used moderately or highly sophisticated computer-tailored methods. Data synthesis revealed that there is evidence for the effectiveness of Internet interventions in improving medication adherence: 5 studies (3 high-quality studies and 2 low-quality studies) showed a significant effect on adherence; 6 other studies (4 high-quality studies and 2 low-quality studies) reported a moderate effect on adherence; and 2 studies (1 high-quality study and 1 low-quality study) showed no effect on patients' adherence. However, most studies used self-reported measurements to assess adherence, which is generally perceived as a low-quality measurement. In addition, we did not find a clear relationship between the quality of the studies or the level of sophistication of message tailoring and the effectiveness of the intervention. This might be explained by the great difference in study designs and the way of measuring adherence, which makes results difficult to compare. There was also large variation in the measured interval between baseline and follow-up measurements. This review shows promising results on the effectiveness of Internet interventions to enhance patients' adherence to prescribed long-term medications. Although there is evidence according to the data synthesis, the results must be interpreted with caution due to low-quality adherence measurements. Future studies using high-quality measurements to assess medication adherence are recommended to establish more robust evidence for the effectiveness of eHealth interventions on medication adherence. Source


Stolk C.,University of Amsterdam
Journal of Computational Physics | Year: 2013

A new domain decomposition method is introduced for the heterogeneous 2-D and 3-D Helmholtz equations. Transmission conditions based on the perfectly matched layer (PML) are derived that avoid artificial reflections and match incoming and outgoing waves at the subdomain interfaces. We focus on a subdivision of the rectangular domain into many thin subdomains along one of the axes, in combination with a certain ordering for solving the subdomain problems and a GMRES outer iteration. When combined with multifrontal methods, the solver has near-linear cost in examples, due to very small iteration numbers that are essentially independent of problem size and number of subdomains. It is to our knowledge only the second method with this property next to the moving PML sweeping method. © 2013 Elsevier Inc. Source


Pols J.,University of Amsterdam
Science Technology and Human Values | Year: 2011

How do technologies such as webcams influence health care and what concepts may describe this? This article explores the literature and analyses what people looking through webcams do within a particular health care practice in the Netherlands, that is, within the rehabilitation of people suffering from severe chronic obstructive pulmonary disease (COPD) or asthma. Several ways to describe the activities webcams support and perform are identified. The webcam is (1) concentrating the activities of its users, by making them focus on the task at hand and (2) magnifies the characteristics of the already existing relationships between webcam users by imposing a relational distance that fits best with intimate contacts. (3) Although webcams shift notions of space and distance, their working appears to be related, to a great extent, to their location. © The Author(s) 2011. Source


Morina N.,University of Amsterdam
Journal of Nervous and Mental Disease | Year: 2011

This study examined independent contributions of rumination and experiential avoidance in predicting symptoms of psychological distress among female widowed survivors of war. A decade after the war in Kosovo, 100 widowed survivors of war completed measures of rumination, experiential avoidance, depression, posttraumatic stress, and prolonged grief. Results showed that both rumination and experiential avoidance significantly predicted the symptom severity of prolonged grief, depression, and posttraumatic stress. Furthermore, rumination accounted for additional variance above and beyond experiential avoidance and vice versa. Finally, the interaction of rumination and experiential avoidance did not provide significant explanatory power over and above the individual main effects. These findings suggest that rumination and experiential avoidance may be significant factors in understanding and treating psychological distress following exposure to potentially traumatic events and loss due to violence. Copyright © 2011 by Lippincott Williams &Wilkins. Source


Persson L.,Umea University | De Roos A.M.,University of Amsterdam
Journal of Animal Ecology | Year: 2012

Life-history omnivory or size-induced mixed competition-predation systems have under many conditions theoretically been shown to be fragile, whereas at the same time existing empirical data suggest such systems to be common in nature. In a whole lake experiment covering 17years, we analysed the effects of the introduction of the intraguild prey roach (Rutilus rutilus) on the population size and individual performance of the intraguild predator perch (Perca fluviatilis) and on resource levels in two low productivity systems. A strong long-term effect of roach on the zooplankton resource but not on the macroinvertebrate resource was present. Competitive effects of roach on perch were observed in one of the lakes the first years after the introduction, but at the end of the study no competitive effect of roach on either size class of perch was observed in any of the two lakes. In contrast, a positive predatory effect reflected in improved growth rates of older perch was present. The lack of a support for a competitive effect of roach on small perch raises the question of the importance of mixed competition-predation interactions in life-history omnivorous systems and the problem of comparing descriptive data on feeding relationships with theoretical predictions based on interaction modules. © 2011 The Authors. Journal of Animal Ecology © 2011 British Ecological Society. Source


Aronica E.,University of Amsterdam | Crino P.B.,University of Pennsylvania
Epilepsia | Year: 2011

Over the past decade, an increasing number of observations indicate that activation of inflammatory processes occurs in variety of focal epilepsies. Understanding the feature and consequences of neuroinflammation, including the contribution to development and perpetuation of seizures, as well as to mood or cognitive dysfunction, is a major requisite for delineating its role in epilepsy. The present article discusses the most recent observations supporting the involvement of the inflammatory response in human focal epilepsy. It also evaluates emerging evidence concerning the possibility to identify epilepsy-associated inflammatory biomarkers in cerebrospinal fluid and serum, as well as the potential application of neuroimaging approaches to study the inflammatory reactions in chronic epilepsy patients in vivo, aiming to improve the recognition of appropriate patient populations who might benefit from antiinflammatory or immunomodulatory therapies. © 2011 International League Against Epilepsy. Source


Levi M.,University of Amsterdam
Current Opinion in Anaesthesiology | Year: 2012

Purpose of review: Hemorrhage is the second most important cause of death in patients with trauma, contributing to approximately 30% of trauma-related mortality. Pharmacological prohemostatic agents may be useful adjunctive treatment options in patients with severe blood loss. Recent findings: Tranexamic acid was evaluated in a large international randomized controlled study in patients with trauma and severe blood loss. The drug was shown to reduce death due to bleeding, provided the treatment was given within 3 h after injury. Tranexamic acid treatment did not result in serious adverse events nor thrombotic complications. Summary: In view of this efficacy and safety of this relatively cheap and simple drug, it may be recommended to put tranexamic acid in the first (maybe even prehospital) line of management of patients with severe traumatic hemorrhage. © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins. Source


van Stralen K.J.,University of Amsterdam
Clinical Journal of the American Society of Nephrology | Year: 2014

Background and objectives Growth and final height are of major concern in children with ESRD. This study sought to describe the distribution of adult height of patients who started renal replacement therapy (RRT) during childhood and to identify determinants of final height in a large cohort of RRT children. Design, setting, participants, & measurements A total of 1612 patients from 20 European countries who started RRT before 19 years of age and reached final height between 1990 and 2011 were included. Linear regression analyses were performed to calculate adjusted mean final height SD score (SDS) and to investigate its potential determinants. Results The median final height SDS was -1.65 (median of 168 cm in boys and 155 cm in girls). Fifty-five percent of patients attained an adult height within the normal range. Adjusted for age at start of RRT and primary renal diseases, final height increased significantly over time from -2.06 SDS in children who reached adulthood in 1990-1995 to -1.33 SDS among those reaching adulthood in 2006-2011. Older age at start of RRT, more recent period of start of RRT, cumulative percentage time on a functioning graft, and greater height SDS at initiation of RRT were independently associated with a higher final height SDS. Patients with congenital anomalies of the kidney and urinary tract and metabolic disorders had a lower final height than those with other primary renal diseases. Conclusions Although final height remains suboptimal in children with ESRD, it has consistently improved over time. © 2014 by the American Society of Nephrology. Source


van den Brink W.,University of Amsterdam
Current Drug Abuse Reviews | Year: 2012

This review summarizes our current knowledge of the pharmacological treatment of substance use disorders and pathological gambling using data mainly from randomized controlled trials and meta-analyses regarding these randomized controlled trials. The review is restricted to the selection of first and second line pharmacological treatments for smoking, alcohol dependence, opioid dependence, cocaine dependence, cannabis dependence and pathological gambling. It is concluded that great progress has been made in the last three decades and that currently evidence-based pharmacological treatments are available for smoking cessation, alcohol and opioid dependence and pathological gambling. At the same time a series of existing and new pharmacological compounds are being tested in cocaine and cannabis dependence. The review concludes with a summary of additional strategies to increase the effect size of already available pharmacological interventions, including polypharmacy, combining pharmacotherapy with psychotherapy and psychosocial support, and improved patient-treatment matching. © 2012 Bentham Science Publishers. Source


Papadodimas K.,University of Amsterdam
Journal of High Energy Physics | Year: 2010

We present some new exact results for general four-dimensional superconformal field theories. We derive differential equations governing the coupling constant dependence of chiral primary correlators. For N = 2 theories we show that the Zamolodchikov metric on the moduli space and the operator mixing of chiral primaries are quasi-topological quantities and constrained by holomorphy. The equations that we find are the four-dimensional analogue of the tt* equations in two-dimensions, discovered by the method of "topological anti-topological fusion" by Cecotti and Vafa. Our analysis relies on conformal perturbation theory and the superconformal Ward identities and does not use a topological twist. © 2010 SISSA. Source


Pozsgay B.,University of Amsterdam
Journal of High Energy Physics | Year: 2010

We investigate the sub-leading contributions to the free energy of Bethe Ansatz solvable (continuum) models with different boundary conditions. We show that the Thermodynamic Bethe Ansatz approach is capable of providing the 0(1) pieces if both the density of states in rapidity space and the quadratic fluctuations around the saddle point solution to the TBA are properly taken into account. In relativistic boundary QFT the 0(1) contributions are directly related to the exact g-function. In this paper we provide an all-orders proof of the previous results of P. Dorey et al. on the g-function in both massive and massless models. In addition, we derive a new result for the g-function which applies to massless theories with arbitrary diagonal scattering in the bulk. © 2010 SISSA. Source


Baharoglu M.I.,University of Amsterdam
The Cochrane database of systematic reviews | Year: 2013

Rebleeding is an important cause of death and disability in people with aneurysmal subarachnoid haemorrhage. Rebleeding is probably related to dissolution of the blood clot at the site of aneurysm rupture by natural fibrinolytic activity. This review is an update of a previously published Cochrane review. To assess the effects of antifibrinolytic treatment in people with aneurysmal subarachnoid haemorrhage. We searched the Cochrane Stroke Group Trials Register (February 2013), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 1), MEDLINE (1948 to December 2012), and EMBASE (1947 to December 2012). In an effort to identify further published, unpublished, and ongoing studies we searched reference lists and trial registers, performed forward tracking of relevant references and contacted drug companies. Randomised trials comparing oral or intravenous antifibrinolytic drugs (tranexamic acid, epsilon amino-caproic acid, or an equivalent) with control in people with subarachnoid haemorrhage of suspected or proven aneurysmal cause. Two review authors independently selected trials for inclusion and extracted the data. Three review authors assessed trial quality. For the primary outcome we converted the outcome scales between good and poor outcome for the analysis. We scored death from any cause and rates of rebleeding, cerebral ischaemia, and hydrocephalus per treatment group. We expressed effects as risk ratios (RR) with 95% confidence intervals (CI). We used random-effects models for all analyses. We included 10 trials involving 1904 participants. The risk of bias was low in six studies. Four studies were open label and were rated as high risk of performance bias. One of these studies was also rated as high risk for attrition bias. Four trials reported on poor outcome (death, vegetative state, or severe disability) with a pooled risk ratio (RR) of 1.02 (95% confidence interval (CI) 0.91 to 1.15). All trials reported on death from all causes with a pooled RR of 1.00 (95% CI 0.85 to 1.18). In a trial that combined short-term antifibrinolytic treatment (< 72 hours) with preventative measures for cerebral ischaemia the RR for poor outcome was 0.85 (95% CI 0.64 to 1.14). Antifibrinolytic treatment reduced the risk of re-bleeding reported at the end of follow-up (RR 0.65, 95% CI 0.44 to 0.97; 78 per 1000 participants), but there was heterogeneity (I2 = 62%) between the trials. The pooled RR for reported cerebral ischaemia was 1.41 (95% CI 1.04 to 1.91, 83 per 1000 participants), again with heterogeneity between the trials (I2 = 52%). Antifibrinolytic treatment showed no effect on the reported rate of hydrocephalus in five trials (RR 1.11, 95% CI 0.90 to 1.36). The current evidence does not support the use of antifibrinolytic drugs in the treatment of people with aneurysmal subarachnoid haemorrhage, even in those who have concomitant treatment strategies to prevent cerebral ischaemia. Results on short-term treatment are promising, but not conclusive. Further randomised trials evaluating short-term antifibrinolytic treatment are needed to evaluate its effectiveness. Source


Park H.W.,Yeungnam University | Leydesdorff L.,University of Amsterdam
Journal of Informetrics | Year: 2013

This paper examines the structural patterns of networks of internationally co-authored SCI papers in the domain of research driven by big data and provides an empirical analysis of semantic patterns of paper titles. The results based on data collected from the DVD version of the 2011 SCI database identify the U.S. as the most central country, followed by the U.K., Germany, France, Italy, Australia, the Netherlands, Canada, and Spain, in that order. However, some countries (e.g., Portugal) with low degree centrality occupied relatively central positions in terms of betweenness centrality. The results of the semantic network analysis suggest that internationally co-authored papers tend to focus on primary technologies, particularly in terms of programming and related database issues. The results show that a combination of words and locations can provide a richer representation of an emerging field of science than the sum of the two separate representations. © 2013 Elsevier Ltd. Source


Shelton R.D.,WTEC Inc | Leydesdorff L.,University of Amsterdam
Journal of the American Society for Information Science and Technology | Year: 2012

Multivariate linear regression models suggest a trade-off in allocations of national research and development (R&D). Government funding and spending in the higher education sector encourage publications as a long-term research benefit. Conversely, other components such as industrial funding and spending in the business sector encourage patenting. Our results help explain why the United States trails the European Union in publications: The focus in the United States is on industrial funding-some 70% of its total R&D investment. Likewise, our results also help explain why the European Union trails the United States in patenting, since its focus on government funding is less effective than industrial funding in predicting triadic patenting. Government funding contributes negatively to patenting in a multiple regression, and this relationship is significant in the case of triadic patenting. We provide new forecasts about the relationships of the United States, the European Union, and China for publishing; these results suggest much later dates for changes than previous forecasts because Chinese growth has been slowing down since 2003. Models for individual countries might be more successful than regression models whose parameters are averaged over a set of countries because nations can be expected to differ historically in terms of the institutional arrangements and funding schemes. © 2011 ASIS&T. Source


Kulaxizi M.,University of Amsterdam | Parnachev A.,State University of New York at Stony Brook
Physical Review Letters | Year: 2011

We show that in most conformal field theories the condition of the energy flux positivity, proposed by Hofman and Maldacena, is equivalent to the absence of ghosts. At finite temperature and large energy and momenta, the two-point functions of the stress energy tensor develop lightlike poles. The residues of the poles can be computed, as long as the only spin-two conserved current, which appears in the stress energy tensor operator-product expansion and acquires a nonvanishing expectation value at finite temperature, is the stress energy tensor. The condition for the residues to stay positive and the theory to remain ghost-free is equivalent to the condition of positivity of energy flux. © 2011 The American Physical Society. Source


Park H.W.,Yeungnam University | Leydesdorff L.,University of Amsterdam
Research Policy | Year: 2010

This study examines the longitudinal trend of systemness in networked research relations in South Korea using a triple helix (TH) indicator of university-industry-government (UIG) relations. The data were harvested from the Science Citation Index (SCI) and its counterparts in the social sciences (SSCI) and the arts and humanities (A&HCI). The total number of Korean SCI publications has grown rapidly since 1965. However, the TH indicator shows that the network dynamics have varied considerably according to the research policies of the national government. The collaboration patterns, as measured by co-authorship relations in the SCI noticeably increased, with some variation, from the mid-1970s to the mid-1990s. However, inter-institutional collaboration in the first decade of the 21st century was negatively influenced by the new national science and technology (S&T) research policies that evaluated domestic scientists and research groups based on their international publication numbers rather than on the level of cooperation among academic, private, and public domains. The results reveal that Korea has failed to boost its national research capacity by neglecting the network effects in science, technology, and industry. © 2010 Elsevier B.V. All rights reserved. Source


Aleiner I.L.,Columbia University | Altshuler B.L.,Columbia University | Shlyapnikov G.V.,University Paris - Sud | Shlyapnikov G.V.,University of Amsterdam
Nature Physics | Year: 2010

It is commonly accepted that there are no phase transitions in one-dimensional systems at a finite temperature, because long-range correlations are destroyed by thermal fluctuations. Here we show theoretically that the one-dimensional gas of short-range interacting bosons in the presence of disorder can undergo a finite-temperature phase transition between two distinct states: fluid and insulator. Neither of these states has long-range spatial correlations, but this is a true, albeit non-conventional, phase transition, because transport properties are singular at the transition point. In the fluid phase, mass transport is possible, whereas in the insulator phase it is completely blocked even at finite temperatures. This study thus provides insight into how the interaction between disordered bosons influences their Anderson localization. This question, first raised for electrons in solids, is now crucial for the studies of atomic bosons, where recent experiments have demonstrated Anderson localization in expanding dilute quasi-one-dimensional clouds. © 2010 Macmillan Publishers Limited. All rights reserved. Source


Journal impact factors (IFs) can be considered historically as the first attempt to normalize citation distributions by using averages over 2 years. However, it has been recognized that citation distributions vary among fields of science and that one needs to normalize for this. Furthermore, the mean-or any central-tendency statistics-is not a good representation of the citation distribution because these distributions are skewed. Important steps have been taken to solve these two problems during the last few years. First, one can normalize at the article level using the citing audience as the reference set. Second, one can use non-parametric statistics for testing the significance of differences among ratings. A proportion of most-highly cited papers (the top-10% or top-quartile) on the basis of fractional counting of the citations may provide an alternative to the current IF. This indicator is intuitively simple, allows for statistical testing, and accords with the state of the art. © 2012 The Author(s). Source


Subramani K.,University of Amsterdam
The International journal of oral & maxillofacial implants | Year: 2012

To review the literature on decontamination of titanium implant surfaces following peri-implantitis and the effect of various cleaning methods on re-osseointegration. An electronic search of the literature at PubMed was conducted on the studies published between 1966 and October 2010. In vitro, animal, and clinical studies were included. Of 597 studies retrieved, 74 manuscripts were selected for the review. Various implant surface decontamination methods using various chemical and mechanical agents have been suggested for treatment and re-osseointegration following periimplantitis. It has been shown that re-osseointegration of contaminated implant surfaces is possible; this largely depends upon the surface of the implant and the types of decontamination techniques and bone regenerative materials used. Complete re-osseointegration cannot be achieved by surface decontamination alone. Titanium implants with titanium plasma-sprayed or sandblasted and acid-etched surfaces may be effectively decontaminated by applying chlorhexidine and saline-soaked gauze or by repeated rinsing with these solutions. Both mechanical and chemical decontamination techniques should be applied alongside regenerative surgical procedures to obtain optimum re-osseointegration and successfully treat peri-implantitis. In recent years, lasers and photodynamic therapy have shown minor beneficial results, which need to be confirmed by long-term clinical studies with comparable groups. Source


Takken F.L.W.,University of Amsterdam | Takken F.L.W.,Center for Biosystems Genomics | Goverse A.,Wageningen University | Goverse A.,Center for Biosystems Genomics
Current Opinion in Plant Biology | Year: 2012

Many plant disease resistance (R) proteins belong to the family of nucleotide-binding-leucine rich repeat (NB-LRR) proteins. NB-LRRs mediate recognition of pathogen-derived effector molecules and subsequently activate host defence. Their multi-domain structure allows these pathogen detectors to simultaneously act as sensor, switch and response factor. Structure-function analyses and the recent elucidation of the 3D structures of subdomains have provided new insight in how these different functions are combined and what the contribution is of the individual subdomains. Besides interdomain contacts, interactions with chaperones, the proteasome and effector baits are required to keep NB-LRRs in a signalling-competent, yet auto-inhibited state. In this review we explore operational models of NB-LRR functioning based on recent advances in understanding their structure. © 2012 Elsevier Ltd. Source


Rieder B.,University of Amsterdam
First Monday | Year: 2012

In this paper, we outline a study of the Twitter microblogging platform through a sample of French users. We discuss sampling methodology and compare three "issues" taken from the collected set of tweets. Based on the empirical findings we make a case for extending the notion of "information diffusion" to take into account questions of meaning, values, and ideology. We propose the concept of "refraction" to take a step toward this end. Source


De Dreu C.K.W.,University of Amsterdam
Hormones and Behavior | Year: 2012

The author reviews evidence that hypothalamic release (or infusion) of the neuropeptide oxytocin modulates the regulation of cooperation and conflict among humans because of three reasons. First, oxytocin enables social categorization of others into in-group versus out-group. Second, oxytocin dampens amygdala activity and enables the development of trust. Third, and finally, oxytocin up-regulates neural circuitries (e.g., inferior frontal gyrus, ventromedial prefrontal cortex, caudate nucleus) involved in empathy and other-concern. Consistent with an evolutionary perspective on the functionality of cooperation, it is concluded that oxytocin-motivated cooperation is mostly parochial-it motivates (i) in-group favoritism, (ii) cooperation towards in-group but not out-group members, and (iii) defense-motivated non-cooperation towards threatening outsiders. Thus, in addition to its well-known role in reproduction and pair-bond formation, oxytocin's primary functions include in-group "tend-and-defend." This review concludes with avenues for new research on oxytocin's functions in within-group cooperation and between-group competition. This article is part of a Special Issue entitled Oxytocin, Vasopressin, and Social Behavior. © 2011 Elsevier Inc. Source


van Egmond M.,VU University Amsterdam | Vidarsson G.,University of Amsterdam | Bakema J.E.,VU University Amsterdam
Immunological Reviews | Year: 2015

The individual role of pathogen-binding Toll-like receptors (TLRs) and antibody-binding Fc receptors (FcRs) during pathogenic infections has been studied extensively. However, combined activation of these different receptor classes has received little attention, even though they are triggered simultaneously when immune cells bind antibody-opsonized pathogens. In the last few years, it has become evident that joined activation of TLRs and FcRs substantially tailors inflammatory immune responses, which is an efficient and controlled mechanism of the host to act upon invading pathogens. In this review, we discuss the mechanisms of cross-talk between different TLRs and FcRs and the resulting inflammatory immune responses. Furthermore, we propose how chronic activation via this cross-talk might be detrimental in inflammatory (auto) immune diseases. We conclude with the potential exploitation of the interplay between TLRs and FcRs for monoclonal antibody therapy to target tumors. Future interests in this field of research include establishing a more detailed and mechanistic understanding of the mode of action of TLR and FcR cross-talk and exploration of its physiological importance in health and disease. This may furthermore open up novel therapeutic options for intervention in inflammatory diseases or cancer. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd. Source


Belzen J.A.,University of Amsterdam
Mental Health, Religion and Culture | Year: 2010

After a brief introduction, this paper tries to establish what type of psychology the psychology of religion is. Having introduced cultural psychology in general, some theories applicable in research on religion are presented, and some examples of cultural psychological research of religious phenomena are discussed. © 2010 Taylor & Francis. Source


Richard E.,University of Amsterdam
JAMA neurology | Year: 2013

To evaluate the association of late-life depression with mild cognitive impairment (MCI) and dementia in a multiethnic community cohort. A cohort study was conducted in Northern Manhattan, New York, New York. A total of 2160 community-dwelling Medicare recipients aged 65 years or older were included in the study. Depression was assessed using the 10-item version of the Center for Epidemiological Studies Depression scale (CES-D) and defined by a CES-D score of 4 or more. We used logistic regression for cross-sectional association analyses and proportional hazards regression for longitudinal analyses. Mild cognitive impairment dementia, and progression from MCI to dementia were the main outcome measures. We also used subcategories of MCI (amnestic and nonamnestic), and dementia (probable Alzheimer disease and vascular dementia, including possible Alzheimer disease with stroke). Baseline depression was associated with prevalent MCI (odds ratio, 1.4; 95% CI, 1.1-1.9) and dementia (2.2; 1.6-3.1). Baseline depression was associated with an increased risk of incident dementia (hazard ratio [HR], 1.7; 95% CI, 1.2-2.3) but not with incident MCI (0.9; 0.7-1.2). Persons with MCI and coexisting depression at baseline had a higher risk of progression to dementia (HR, 2.0; 95% CI, 1.2-3.4), especially vascular dementia (4.3; 1.1-17.0), but not Alzheimer disease (1.9; 1.0-3.6). The association of depression with prevalent MCI and with progression from MCI to dementia, but not with incident MCI, suggests that depression accompanies cognitive impairment but does not precede it. Source


Leydesdorff L.,University of Amsterdam | Rafols I.,University of Sussex
Journal of Informetrics | Year: 2011

A citation-based indicator for interdisciplinarity has been missing hitherto among the set of available journal indicators. In this study, we investigate network indicators (betweenness centrality), unevenness indicators (Shannon entropy, the Gini coefficient), and more recently proposed Rao-Stirling measures for " interdisciplinarity." The latter index combines the statistics of both citation distributions of journals (vector-based) and distances in citation networks among journals (matrix-based). The effects of various normalizations are specified and measured using the matrix of 8207 journals contained in the Journal Citation Reports of the (Social) Science Citation Index 2008. Betweenness centrality in symmetrical (1-mode) cosine-normalized networks provides an indicator outperforming betweenness in the asymmetrical (2-mode) citation network. Among the vector-based indicators, Shannon entropy performs better than the Gini coefficient, but is sensitive to size. Science and Nature, for example, are indicated at the top of the list. The new diversity measure provides reasonable results when (1-cosine) is assumed as a measure for the distance, but results using Euclidean distances were difficult to interpret. © 2010 Elsevier Ltd. Source


Van Bergen J.,Leiden University | Mulder C.J.,University of Amsterdam | Mearin M.L.,Leiden University | Koning F.,Leiden University
Gastroenterology | Year: 2015

In patients with celiac disease, gluten consumption causes inflammation of the duodenum, and, to a lesser extent, the proximal jejunum. Immune-dominant gluten peptides are modified by the enzyme TG2, leading to their high-affinity binding to HLA-DQ2 or HLA-DQ8 molecules, present in people with a predisposition to celiac disease. Gluten peptide-loaded HLA-DQ2 or HLA-DQ8 molecules are recognized by highly conserved receptors on CD4+ T cells in the lamina propria. B cells specific for TG2 and modified gluten peptides are also abundant in the lamina propria of patients with celiac disease. In the epithelium, interleukin-15 activates intraepithelial lymphocytes that promote destruction of epithelial cells. However, it is not clear how the immune responses in the lamina propria and the epithelium, separated by a basement membrane, are linked. We review the immune processes that occur in the lamina propria and their potential effects on epithelial pathology in celiac disease. © 2015 AGA Institute. Source


Speijer D.,University of Amsterdam | Lukes J.,University of South Bohemia | Lukes J.,Canadian Institute for Advanced Research | Elias M.,University of Ostrava
Proceedings of the National Academy of Sciences of the United States of America | Year: 2015

Sexual reproduction and clonality in eukaryotes are mostly seen as exclusive, the latter being rather exceptional. This view might be biased by focusing almost exclusively on metazoans. We analyze and discuss reproduction in the context of extant eukaryotic diversity, paying special attention to protists. We present results of phylogenetically extended searches for homologs of two proteins functioning in cell and nuclear fusion, respectively (HAP2 and GEX1), providing indirect evidence for these processes in several eukaryotic lineages where sex has not been observed yet. We argue that (i) the debate on the relative significance of sex and clonality in eukaryotes is confounded by not appropriately distinguishing multicellular and unicellular organisms; (ii) eukaryotic sex is extremely widespread and already present in the last eukaryotic common ancestor; and (iii) the general mode of existence of eukaryotes is best described by clonally propagating cell lines with episodic sex triggered by external or internal clues. However, important questions concern the relative longevity of true clonal species (i.e., species not able to return to sexual procreation anymore). Long-lived clonal species seem strikingly rare. We analyze their properties in the light of meiotic sex development from existing prokaryotic repair mechanisms. Based on these considerations, we speculate that eukaryotic sex likely developed as a cellular survival strategy, possibly in the context of internal reactive oxygen species stress generated by a (proto) mitochondrion. Thus, in the context of the symbiogenic model of eukaryotic origin, sex might directly result from the very evolutionary mode by which eukaryotic cells arose. © 2015. National Academy of Sciences. All rights reserved. Source


Krishna R.,University of Amsterdam
Microporous and Mesoporous Materials | Year: 2012

The major objective of this communication is to compare the performance of three metal-organic frameworks (MOFs): CuBTC, MIL-101, and Zn(bdc)dabco, with that of NaX zeolite for selective adsorption of CO 2 from mixtures containing CH 4 and CO in a pressure swing adsorption (PSA) unit operating at pressures ranging to 60 bar. Data on the pure component adsorption isotherms in the published literature are available in terms of excess loadings. For purposes of isotherm fitting with fundamental Langmuir-type models, these data need to be converted to absolute loadings. Calculations using the Ideal Adsorbed Solution Theory (IAST), using the fitted isotherm data on absolute loadings, show that the CO 2/CH 4 and CO 2/CO selectivities are significantly higher with NaX than for the three MOFs. The working capacity for CO 2 adsorption, on the other hand, is significantly higher for MOFs than for NaX zeolite as the pressures are increased significantly above 2 bar. For a realistic comparison of the separation characteristics in a fixed bed adsorber unit, transient breakthrough calculations were performed for an equilibrium packed bed adsorber. For a specified purity of CO 2 exiting the packed bed adsorber, the best CO 2 removal performance is obtained with CuBTC. Our studies highlight the relative importance of adsorption selectivities and capacities in the performance of fixed bed adsorbers, and underline the significant advantage of MOFs over traditionally used zeolites. © 2012 Elsevier Inc. All rights reserved. Source


Andreux P.A.,Ecole Polytechnique Federale de Lausanne | Houtkooper R.H.,University of Amsterdam | Auwerx J.,Ecole Polytechnique Federale de Lausanne
Nature Reviews Drug Discovery | Year: 2013

Mitochondrial dysfunction is not only a hallmark of rare inherited mitochondrial disorders but also implicated in age-related diseases, including those that affect the metabolic and nervous system, such as type 2 diabetes and Parkinson's disease. Numerous pathways maintain and/or restore proper mitochondrial function, including mitochondrial biogenesis, mitochondrial dynamics, mitophagy and the mitochondrial unfolded protein response. New and powerful phenotypic assays in cell-based models as well as multicellular organisms have been developed to explore these different aspects of mitochondrial function. Modulating mitochondrial function has therefore emerged as an attractive therapeutic strategy for several diseases, which has spurred active drug discovery efforts in this area. Source


den Blaauwen T.,University of Amsterdam
Current Opinion in Microbiology | Year: 2013

Gram-negative rod-shaped bacteria have different approaches to position the cell division initiating Z-ring at the correct moment in their cell division cycle. The subsequent maturation into a functional division machine occurs in vastly different species in two steps with appreciable time in between these. The function of this time delay is unclear, but may partly be explained by competition for Lipid-II between proteins involved in length growth that interact directly with the Z-ring early in the maturation phase and the proteins involved in septum synthesis. A second possible activity of the early Z-ring might be the monitoring of or the active involvement in DNA segregation through proteins such as ZapA and ZapB/MatP and their homologues. © 2013 Elsevier Ltd. Source


Kruikemeier S.,University of Amsterdam
Computers in Human Behavior | Year: 2014

This study investigates the content characteristics of Twitter during an election campaign, and the relationship between candidates' style of online campaigning (i.e., politically personalized and interactive communication) and electoral support for those candidates. Thereby, it provides a better understanding of the linkage between the use of Twitter by candidates and effects on preferential votes. Two data sources are used to examine this relationship: first, a quantitative computer-assisted as well as a manual content analysis of tweets posted by political candidates during the Dutch national elections of 2010 (N = 40,957) and second, a dataset containing the number of votes for electable political candidates during that period. The findings show that using Twitter has positive consequences for political candidates. Candidates who used Twitter during the course of the campaign received more votes than those who did not, and using Twitter in an interactive way had a positive impact as well. © 2014 Elsevier Ltd. All rights reserved. Source


Diphoorn T.,University of Amsterdam
Medical Anthropology: Cross Cultural Studies in Health and Illness | Year: 2015

In this article, I analyze the role of bodily capital in the daily policing practices of armed response officers, a specific type of private security officers, in Durban, South Africa. Based on 20 months of ethnographic fieldwork, I argue that the masculinized bodily capital of armed response officers is a key source of their sovereign power; it plays a central role in how they acquire and exert authority. Furthermore, I argue that an analysis of bodily capital should not solely analyze the actual flesh of the body, but must include particular equipment (such as bulletproof vests and firearms) that is experienced as a part of the body. Copyright © 2015 Taylor & Francis Group, LLC. Source


Leydesdorff L.,University of Amsterdam | Bornmann L.,Max Planck Society
Journal of the American Society for Information Science and Technology | Year: 2011

In bibliometrics, the association of "impact" with central-tendency statistics is mistaken. Impacts add up, and citation curves therefore should be integrated instead of averaged. For example, the journals MIS Quarterly and Journal of the American Society for Information Science and Technology differ by a factor of 2 in terms of their respective impact factors (IF), but the journal with the lower IF has the higher impact. Using percentile ranks (e.g., top-1%, top-10%, etc.), an Integrated Impact Indicator (I3) can be based on integration of the citation curves, but after normalization of the citation curves to the same scale. The results across document sets can be compared as percentages of the total impact of a reference set. Total number of citations, however, should not be used instead because the shape of the citation curves is then not appreciated. I3 can be applied to any document set and any citation window. The results of the integration (summation) are fully decomposable in terms of journals or institutional units such as nations, universities, and so on because percentile ranks are determined at the paper level. In this study, we first compare I3 with IFs for the journals in two Institute for Scientific Information subject categories ("Information Science & Library Science" and "Multidisciplinary Sciences"). The library and information science set is additionally decomposed in terms of nations. Policy implications of this possible paradigm shift in citation impact analysis are specified. © 2011 ASIS&T. Source


Leydesdorff L.,University of Amsterdam | Bornmann L.,Foresight
Journal of the American Society for Information Science and Technology | Year: 2011

The Impact Factors (IFs) of the Institute for Scientific Information suffer from a number of drawbacks, among them the statisticsâWhy should one use the mean and not the median?âand the incomparability among fields of science because of systematic differences in citation behavior among fields. Can these drawbacks be counteracted by fractionally counting citation weights instead of using whole numbers in the numerators? (a) Fractional citation counts are normalized in terms of the citing sources and thus would take into account differences in citation behavior among fields of science. (b) Differences in the resulting distributions can be tested statistically for their significance at different levels of aggregation. (c) Fractional counting can be generalized to any document set including journals or groups of journals, and thus the significance of differences among both small and large sets can be tested. A list of fractionally counted IFs for 2008 is available online at The between-group variance among the 13 fields of science identified in the U.S. Science and Engineering Indicators is no longer statistically significant after this normalization. Although citation behavior differs largely between disciplines, the reflection of these differences in fractionally counted citation distributions can not be used as a reliable instrument for the classification. © 2010 ASIS&T. Source


Munnik T.,University of Amsterdam | Nielsen E.,University of Michigan
Current Opinion in Plant Biology | Year: 2011

Plant genomes lack homologues of the inositol 1,4,5-trisphosphate receptor and protein kinase C, which are important components of the canonical phospholipase C signalling system in animals. Instead, plants seem to utilize alternative downstream signalling molecules, that is, InsP6 and phosphatidic acid. Inositol lipids may also function as second messengers themselves. By reversible phosphorylation of the inositol headgroup, five biologically active plant polyphosphoinositides can be detected. Protein targets interact with specific polyphosphoinositide isomers via selective lipid-binding domains, thereby altering their intracellular localization and/or enzymatic activity. Such lipid-binding domains have also been used to create GFP based-lipid biosensors to visualize PPIs dynamics in vivo. Here, we highlight some recent advances and ideas on PPIs' role in plant signalling. © 2011 Elsevier Ltd. Source


Schmidt S.M.,University of Amsterdam | Panstruga R.,Max Planck Institute for Plant Breeding Research
Current Opinion in Plant Biology | Year: 2011

Members of the kingdom fungi comprise numerous plant pathogens, including the causal agents of many agriculturally relevant plant diseases such as rust, powdery mildew, rice blast and cereal head blight. Data from recent sequencing projects provide deep insight into the genomes of a range of fungi that infect different organs of monocotyledonous or dicotyledonous hosts and that have diverse pathogenic lifestyles. These studies have revealed that, similar to sequenced phytopathogenic oomycetes, these plant parasites possess very plastic and dynamic genomes, which typically encode several hundred candidate secreted effector proteins that can be highly divergent even among related species. A new insight is the presence of lineage-specific genes on mobile and partly dispensable chromosomes that are transferred intraspecifically and possibly interspecifically, thereby constituting pathogenicity and host range determinants. Convergent lifestyle-specific adaptations have shaped the parasite genomes to maximize pathogenic success according to the different infection strategies employed. © 2011 Elsevier Ltd. Source


Turolla R.,University of Padua | Turolla R.,University College London | Zane S.,University College London | Watts A.L.,University of Amsterdam
Reports on Progress in Physics | Year: 2015

Magnetars are the strongest magnets in the present universe and the combination of extreme magnetic field, gravity and density makes them unique laboratories to probe current physical theories (from quantum electrodynamics to general relativity) in the strong field limit. Magnetars are observed as peculiar, burst-active x-ray pulsars, the anomalous x-ray pulsars (AXPs) and the soft gamma repeaters (SGRs); the latter emitted also three 'giant flares', extremely powerful events during which luminosities can reach up to 1047erg s-1 for about one second. The last five years have witnessed an explosion in magnetar research which has led, among other things, to the discovery of transient, or 'outbursting', and 'low-field' magnetars. Substantial progress has been made also on the theoretical side. Quite detailed models for explaining the magnetars' persistent x-ray emission, the properties of the bursts, the flux evolution in transient sources have been developed and confronted with observations. New insight on neutron star asteroseismology has been gained through improved models of magnetar oscillations. The long-debated issue of magnetic field decay in neutron stars has been addressed, and its importance recognized in relation to the evolution of magnetars and to the links among magnetars and other families of isolated neutron stars. The aim of this paper is to present a comprehensive overview in which the observational results are discussed in the light of the most up-to-date theoretical models and their implications. This addresses not only the particular case of magnetar sources, but the more fundamental issue of how physics in strong magnetic fields can be constrained by the observations of these unique sources. © 2015 IOP Publishing Ltd. Source


The phosphoinositide 3-kinases (PI3Ks) are critical components of the B-cell receptor (BCR) pathway and have an important role in the pathobiology of chronic lymphocytic leukemia (CLL). Inhibitors of PI3Kδ block BCR-mediated cross-talk between CLL cells and the lymph node microenvironment and provide significant clinical benefit to CLL patients. However, the PI3Kδ inhibitors applied thus far have limited direct impact on leukemia cell survival and thus are unlikely to eradicate the disease. The use of inhibitors of multiple isoforms of PI3K might lead to deeper remissions. Here we demonstrate that the pan-PI3K/mammalian target of rapamycin inhibitor SAR245409 (voxtalisib/XL765) was more pro-apoptotic to CLL cells—irrespective of their ATM/p53 status—than PI3Kα or PI3Kδ isoform selective inhibitors. Furthermore, SAR245409 blocked CLL survival, adhesion and proliferation. Moreover, SAR245409 was a more potent inhibitor of T-cell-mediated production of cytokines, which support CLL survival. Taken together, our in vitro data provide a rationale for the evaluation of a pan-PI3K inhibitor in CLL patients.Leukemia advance online publication, 10 November 2015; doi:10.1038/leu.2015.241. © 2015 Macmillan Publishers Limited Source


Lapid O.,University of Amsterdam
Aesthetic Plastic Surgery | Year: 2013

Background Gestational gigantomastia (GGM) is a rare complication of pregnancy. Management usually is initiated with bromocriptine. If this is unsuccessful, surgery may be required. The surgical management may be by breast reduction or by mastectomy and delayed reconstruction. Case A 24-year-old woman (G1P0) presented at 24 weeks gestation with massive hypertrophy of her breasts. A decision to operate was made by a multidisciplinary team. At 30 weeks gestation, bilateral mastectomies were performed, with removal of more than 8 kg per side. Reconstruction was started 10 months after delivery using tissue expanders followed by definitive implants. Conclusion GGM can be successfully reconstructed. Knowledge of the treatment process and the expected outcomes can help clinicians inform their patients.Level of Evidence V This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266. © Springer Science+Business Media New York and International Society of Aesthetic Plastic Surgery 2013. Source


Bellini C.,University of Genoa | Hennekam R.C.,University of Amsterdam
American Journal of Medical Genetics, Part A | Year: 2012

Hydrops fetalis is an excessive accumulation of fetal fluid. Hydrops is traditionally classified into either immune or non-immune hydrops (NIHF), but in practice, nowadays in the Western world >90% of hydrops is of non-immune origin. The basis of the disorder is an imbalance in the regulation of fetal fluid movement between the vascular and interstitial space. We previously suggested a diagnostic flow-chart for NIHF. In this short review we describe the main mechanisms leading to NIHF. © 2012 Wiley Periodicals, Inc. Source


Corboz P.,ETH Zurich | Corboz P.,University of Amsterdam | Rice T.M.,ETH Zurich | Troyer M.,ETH Zurich
Physical Review Letters | Year: 2014

Variational studies of the t-J model on the square lattice based on infinite projected-entangled pair states confirm an extremely close competition between a uniform d-wave superconducting state and different stripe states. The site-centered stripe with an in-phase d-wave order has an equal or only slightly lower energy than the stripe with antiphase d-wave order. The optimal stripe filling is not constant but increases with J/t. A nematic anisotropy reduces the pairing amplitude and the energies of stripe phases are lowered relative to the uniform state with increasing nematicity. © 2014 American Physical Society. Source


Heller M.P.,University of Amsterdam | Janik R.A.,Jagiellonian University | Witaszczyk P.,Jagiellonian University
Physical Review Letters | Year: 2013

We utilize the fluid-gravity duality to investigate the large order behavior of hydrodynamic gradient expansion of the dynamics of a gauge theory plasma system. This corresponds to the inclusion of dissipative terms and transport coefficients of very high order. Using the dual gravity description, we calculate numerically the form of the stress tensor for a boost-invariant flow in a hydrodynamic expansion up to terms with 240 derivatives. We observe a factorial growth of gradient contributions at large orders, which indicates a zero radius of convergence of the hydrodynamic series. Furthermore, we identify the leading singularity in the Borel transform of the hydrodynamic energy density with the lowest nonhydrodynamic excitation corresponding to a 'nonhydrodynamic' quasinormal mode on the gravity side. © 2013 American Physical Society. Source


Blutner R.,University of Amsterdam
Journal of Logic, Language and Information | Year: 2012

Taking the lead from orthodox quantum theory, I will introduce a handy generalization of the Boolean approach to propositions and questions: the orthoalgebraic framework. I will demonstrate that this formalism relates to a formal theory of questions (or 'observables' in the physicist's jargon). This theory allows formulating attitude questions, which normally are non-commuting, i. e., the ordering of the questions affects the answer behavior of attitude questions. Further, it allows the expression of conditional questions such as "If Mary reads the book, will she recommend it to Peter?", and thus gives the framework the semantic power of raising issues and being informative at the same time. In the case of commuting observables, there are close similarities between the orthoalgebraic approach to questions and the Jäger/Hulstijn approach to question semantics. However, there are also differences between the two approaches even in case of commuting observables. The main difference is that the Jäger/Hulstijn approach relates to a partition theory of questions whereas the orthoalgebraic approach relates to a 'decorated' partition theory (i. e. the elements of the partition are decorated by certain semantic values). Surprisingly, the orthoalgebraic approach is able to overcome most of the difficulties of the Jäger/Hulstijn approach. Furthermore, the general approach is suitable to describe the different types of (non-commutative) attitude questions as investigated in modern survey research. Concluding, I will suggest that an active dialogue between the traditional model-theoretic approaches to semantics and the orthoalgebraic paradigm is mandatory. © 2012 The Author(s). Source


The new interface of the Web of Science (Thomson Reuters) enables users to retrieve sets larger than 100,000 documents in a single search. This makes it possible to compare publication trends for China, the USA, EU-27, and smaller countries with the data in the Scopus (Elsevier) database. China no longer grew exponentially during the 2000s, but linearly. Contrary to previous predictions on the basis of exponential growth, the cross-over of the lines for China and the USA is postponed to the next decade (after 2020) according to this data. These long extrapolations, however, should be used only as indicators and not as predictions. Uncertainty in trends can be specified using the coefficient of determination of the regression (R2) and confidence intervals. Along with the dynamics in the publication trends, one also has to take into account the dynamics of the databases used for the measurement. Source


Chowdhury B.D.,University of Amsterdam | Puhm A.,CEA Saclay Nuclear Research Center
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

Recently, Almheiri, Marolf, Polchinski, and Sully have suggested a Gedankenexperiment to test black hole complementarity. They claim that the postulates of black hole complementarity are mutually inconsistent and choose to give up the "absence of drama" for an infalling observer. According to them, the black hole is shielded by a firewall no later than Page time. This has generated some controversy. We find that an interesting picture emerges when we take into account objections from the advocates of fuzzballs. We reformulate Almheiri, Marolf, Polchinski, and Sully's Gedankenexperiment in the decoherence picture of quantum mechanics and find that low energy wave packets interact with the radiation quanta rather violently while high energy wave packets do not. This is consistent with Mathur's recent proposal of fuzzball complementarity for high energy quanta falling into fuzzballs. © 2013 American Physical Society. Source


Ho W.C.G.,University of Southampton | Andersson N.,University of Southampton | Haskell B.,University of Amsterdam
Physical Review Letters | Year: 2011

We consider the astrophysical constraints on the gravitational-wave-driven r-mode instability in accreting neutron stars in low-mass x-ray binaries. We use recent results on superfluid and superconducting properties to infer the core temperature in these neutron stars and show the diversity of the observed population. Simple theoretical models indicate that many of these systems reside inside the r-mode instability region. However, this is in clear disagreement with expectations, especially for the systems containing the most rapidly rotating neutron stars. The inconsistency highlights the need to reevaluate our understanding of the many areas of physics relevant to the r-mode instability. We summarize the current status of our understanding, and we discuss directions for future research which could resolve this dilemma. © 2011 American Physical Society. Source


Hatlo M.M.,University Utrecht | Panja D.,University of Amsterdam | Van Roij R.,University Utrecht
Physical Review Letters | Year: 2011

Recent experiments of translocation of double-stranded DNA through nanopores reveal that the DNA capture rate can be significantly influenced by a salt gradient across the pore. We show that osmotic flow combined with electrophoretic effects can quantitatively explain the experimental data on the salt-gradient dependence of the capture rate. © 2011 American Physical Society. Source


Holsheimer K.,University of Amsterdam
Journal of High Energy Physics | Year: 2014

We study holographic renormalization and RG flow in a strongly-coupled Lifshitz-type theory in 2+1 dimensions with dynamical exponent z = 2. The bottomup gravity dual we use is 3+1 dimensional Einstein gravity coupled to a massive vector field. This model contains a marginally relevant operator around the Lifshitz fixed point. We show how holographic renormalization works in the presence of this marginally relevant operator without the need to introduce explicitly cutoff-dependent counterterms. A simple closed-form expression is found for the renormalized on-shell action. We also discuss how asymptotically Lifshitz geometries flow to AdS in the interior due to the marginally relevant operator. We study the behavior of the renormalized entanglement entropy and confirm that it decreases monotonically along the Lifshitz-to-AdS RG flow. Open Access, © 2014 The Authors. Source


Galanopoulou A.S.,Yeshiva University | Gorter J.A.,University of Amsterdam | Cepeda C.,University of California at Los Angeles
Epilepsia | Year: 2012

The mammalian target of rapamycin (mTOR) signaling pathway regulates cell growth, differentiation, proliferation, and metabolism. Loss-of-function mutations in upstream regulators of mTOR have been highly associated with dysplasias, epilepsy, and neurodevelopmental disorders. These include tuberous sclerosis, which is due to mutations in TSC1 or TSC2 genes; mutations in phosphatase and tensin homolog (PTEN) as in Cowden syndrome, polyhydramnios, megalencephaly, symptomatic epilepsy syndrome (PMSE) due to mutations in the STE20-related kinase adaptor alpha (STRADalpha); and neurofibromatosis type 1 attributed to neurofibromin 1 mutations. Inhibition of the mTOR pathway with rapamycin may prevent epilepsy and improve the underlying pathology in mouse models with disrupted mTOR signaling, due to PTEN or TSC mutations. However the timing and duration of its administration appear critical in defining the seizure and pathology-related outcomes. Rapamycin application in human cortical slices from patients with cortical dysplasias reduces the 4-aminopyridine- induced oscillations. In the multiple-hit model of infantile spasms, pulse high-dose rapamycin administration can reduce the cortical overactivation of the mTOR pathway, suppresses spasms, and has disease-modifying effects by partially improving cognitive deficits. In post-status epilepticus models of temporal lobe epilepsy, rapamycin may ameliorate the development of epilepsy-related pathology and reduce the expression of spontaneous seizures, but its effects depend on the timing and duration of administration, and possibly the model used. The observed recurrence of seizures and epilepsy-related pathology after rapamycin discontinuation suggests the need for continuous administration to maintain the benefit. However, the use of pulse administration protocols may be useful in certain age-specific epilepsy syndromes, like infantile spasms, whereas repetitive-pulse rapamycin protocols may suffice to sustain a long-term benefit in genetic disorders of the mTOR pathway. In summary, mTOR dysregulation has been implicated in several genetic and acquired forms of epileptogenesis. The use of mTOR inhibitors can reverse some of these epileptogenic processes, although their effects depend upon the timing and dose of administration as well as the model used. © Wiley Periodicals, Inc. © 2012 International League Against Epilepsy. Source


Reijnders L.,University of Amsterdam
Biomass and Bioenergy | Year: 2010

In the near future, the lignocellulosic C4 crops Miscanthus and switchgrass (Panicum virgatum) are unlikely to outcompete sugarcane (Saccharum officinarum) in net energetic yearly yield of transport biofuel ha-1. This holds both for the thermochemical conversion into liquid hydrocarbons and the enzymatic conversion into ethanol. Currently, Miscanthus and switchgrass would also not seem able to outcompete corn (Zea mays) in net energetic yearly yield of liquid transport biofuel ha-1, but further development of these lignocellulosic crops may gradually lead to a different outcome. © 2009 Elsevier Ltd. All rights reserved. Source


Bovenkerk F.,University of Amsterdam
Crime, Law and Social Change | Year: 2011

Terrorist organizations, groups, cells or just 'bunches of guys' are systematically compared with other types of criminal or deviant organizations: organized crime such as the mafia, street gangs and religious sects. Of course there are many differences between them, especially where motivation is concerned, but they share the common factor that it is almost impossible or very difficult for individual members to step out. However, de-radicalization may follow analogous paths: aging out, accepting exit programs in prison or disengaging ideologically. The article discusses the obstacles that a government strategy that encourages desistance from terrorism by stepping out may encounter. It may be sufficient and more realistic to discourage radicals from using violence than to try to de-radicalize them by using counternarrative techniques. © 2011 Springer Science+Business Media B.V. Source


Karger J.,University of Leipzig | Binder T.,University of Leipzig | Chmelik C.,University of Leipzig | Hibbe F.,University of Leipzig | And 3 more authors.
Nature Materials | Year: 2014

The intense interactions of guest molecules with the pore walls of nanoporous materials is the subject of continued fundamental research. Stimulated by their thermal energy, the guest molecules in these materials are subject to a continuous, irregular motion, referred to as diffusion. Diffusion, which is omnipresent in nature, influences the efficacy of nanoporous materials in reaction and separation processes. The recently introduced techniques of microimaging by interference and infrared microscopy provide us with a wealth of information on diffusion, hitherto inaccessible from commonly used techniques. Examples include the determination of surface barriers and the sticking coefficient's analogue, namely the probability that, on colliding with the particle surface, a molecule may continue its diffusion path into the interior. Microimaging is further seen to open new vistas in multicomponent guest diffusion (including the detection of a reversal in the preferred diffusion pathways), in guest-induced phase transitions in nanoporous materials and in matching the results of diffusion studies under equilibrium and non-equilibrium conditions. © 2014 Macmillan Publishers Limited. All rights reserved. Source


Verhagen T.,VU University Amsterdam | Van Dolen W.,University of Amsterdam
Information and Management | Year: 2011

Our study provides insight into the relationships between online store beliefs and consumer online impulse buying behavior. Drawing upon cognitive emotion theory, we developed a model and showed how beliefs about functional convenience (online store merchandise attractiveness and ease of use) and about representational delight (enjoyment and website communication style) related to online impulse buying. The model was tested using survey data from 532 customers of a Dutch online store. Our results showed significant effects of merchandise attractiveness, enjoyment, and online store communication style, mediated by consumers' emotions. The study should enhance our understanding of online impulse buying and, by assessing the impact of the online store, of beliefs in non-rational decision-making settings. © 2011 Elsevier B.V. Source


Van Der Vlugt J.I.,University of Amsterdam
Chemical Society Reviews | Year: 2010

Recent developments toward selective N-H cleavage and the use of ammonia as a substrate in homogeneous catalysis are discussed in this critical review (134 references). © The Royal Society of Chemistry 2010. Source


Priolo F.,University of Catania | Priolo F.,CNR Institute for Microelectronics and Microsystems | Gregorkiewicz T.,University of Amsterdam | Galli M.,University of Pavia | Krauss T.F.,University of York
Nature Nanotechnology | Year: 2014

Silicon has long been established as the material of choice for the microelectronics industry. This is not yet true in photonics, where the limited degrees of freedom in material design combined with the indirect bandgap are a major constraint. Recent developments, especially those enabled by nanoscale engineering of the electronic and photonic properties, are starting to change the picture, and some silicon nanostructures now approach or even exceed the performance of equivalent direct-bandgap materials. Focusing on two application areas, namely communications and photovoltaics, we review recent progress in silicon nanocrystals, nanowires and photonic crystals as key examples of functional nanostructures. We assess the state of the art in each field and highlight the challenges that need to be overcome to make silicon a truly high-performing photonic material. © 2014 Macmillan Publishers Limited. Source


McIntyre P.B.,University of Sydney | O'Brien K.L.,International Vaccine Access Center | Greenwood B.,London School of Hygiene and Tropical Medicine | Van De Beek D.,University of Amsterdam
The Lancet | Year: 2012

Three bacteria-Haemophilus infl uenzae, Streptococcus pneumoniae, and Neisseria meningitidis-account for most acute bacterial meningitis. Measurement of the eff ect of protein-polysaccharide conjugate vaccines is most reliable for H infl uenzae meningitis because one serotype and one age group account for more than 90% of cases and the incidence has been best measured in high-income countries where these vaccines have been used longest. Pneumococcal and meningococcal meningitis are caused by diverse serotypes and have a wide age distribution; measurement of their incidence is complicated by epidemics and scarcity of surveillance, especially in low-income countries. Near elimination of H infl uenzae meningitis has been documented after vaccine introduction. Despite greater than 90% reductions in disease attributable to vaccine serotypes, all-age pneumococcal meningitis has decreased by around 25%, with little data from low-income settings. Near elimination of serogroup C meningococcal meningitis has been documented in several high-income countries, boding well for the eff ect of a new serogroup A meningococcal conjugate vaccine in the African meningitis belt. Source


Walton N.S.,University of Amsterdam
Queueing Systems | Year: 2011

We describe a queuing model where service is allocated as a function of queue sizes. We consider allocations policies that are insensitive to service requirements and have a maximal stability region. We take a limit where the queuing model becomes congested. We study how service is allocated under this limit. We demonstrate that the only possible limit allocation is one that maximizes a proportionally fair optimization problem. © 2011 The Author(s). Source


Davies J.M.,University of Queensland | Platts-Mills T.A.,University of Virginia | Aalberse R.C.,University of Amsterdam
Journal of Allergy and Clinical Immunology | Year: 2013

Our understanding of the origin and fate of the IgE-switched B cell has been markedly improved by studies in mouse models. The immediate precursor of the IgE-switched B cell is either a relatively naive nonswitched B cell or a mature IgG-switched B cell. These 2 routes are referred to as the direct and indirect pathways, respectively. IgE responses derived from each pathway differ significantly, largely reflecting the difference in time spent in a germinal center and thus time for clonal expansion, somatic hypermutation, affinity maturation, and acquisition of a memory phenotype. The clinical and therapeutic implications for IgE responses in human subjects are still a matter of debate, largely because the immunization procedures used in the animal models are significantly different from classical atopic sensitization to allergens from pollen and mites. On the basis of the limited information available, it seems likely that these atopic IgE responses are characterized by a relatively low IgG/IgE ratio, low B-cell memory, and modest affinity maturation, which fits well with the direct switching pathway. It is still unresolved how the IgE response evolves to cover a wide epitope repertoire involving many epitopes per allergen, as well as many different allergens from a single allergen source. © 2013 American Academy of Allergy, Asthma & Immunology. Source


Levi M.,University of Amsterdam
Critical Care | Year: 2015

The diagnosis of disseminated intravascular coagulation (DIC) based on composite scoring systems using routinely available coagulation tests has been greatly facilitated. Such scoring instruments not only adequately assess the presence of DIC but also have strong prognostic power for morbidity and mortality. In this issue of Critical Care, Gando and colleagues report on the prospective validation of the Japanese Association of Acute Medicine score for DIC in patients with severe sepsis. © 2013 BioMed Central Ltd. Source


Verschueren K.,Catholic University of Leuven | Koomen H.M.Y.,University of Amsterdam
Attachment and Human Development | Year: 2012

This special issue aims to prompt reflection on the mutual contribution of attachment theory, on the one hand, and teacher-child relationship research, on the other, by bringing together conceptual and empirical contributions taking an attachment perspective on teacher-child relationships. In this introductory article, we contend that the teacher can be regarded as an ad hoc attachment figure with a safe haven and secure base function, although for most children the relationship with the teacher is probably not an attachment bond. Furthermore, we explain how attachment theory and research: (1) shape the way in which "high quality" teacher-child relationships are conceptualized and operationalized; (2) highlight the importance of teacher sensitivity to children's needs, as a central proximal determinant of relationship quality; (3) guide research hypotheses regarding the consequences of teacher-child relationship quality and the intervening mechanisms; and (4) inspire the development of interventions to improve teacher-child relationships. © 2012 Copyright Taylor and Francis Group, LLC. Source


Zeerleder S.,Sanquin Research | Zeerleder S.,University of Amsterdam
Seminars in Thrombosis and Hemostasis | Year: 2011

C1-inhibitor (C1-inh) is a crucial regulator of the activation of plasmatic cascade systems involved in inflammation contributing to the homeostasis in the generation of proinflammatory mediators. The importance of C1-inh is illustrated by patients with hereditary angioedema where decreased levels of C1-inh lead to an uncontrolled generation of vasoactive peptides resulting in potential life-threatening subcutaneous edema. Recent publications, however, suggest that the anti-inflammatory properties of C1-inh do not strictly depend on its capacity to regulate the complement and contact phase system. This review summarizes the biochemical characteristics of C1-inh and its role in the regulation of plasmatic cascade systems as well as the role of the nonserpin domain. Copyright © 2011 by Thieme Medical Publishers, Inc. Source


Panja D.,University of Amsterdam
Journal of Physics Condensed Matter | Year: 2011

It has been recently shown that the phase space trajectories for the anomalous dynamics of a tagged monomer of a polymer - for single polymeric systems and phenomena such as phantom Rouse, self-avoiding Rouse, and Zimm ones, reptation, and translocation through a narrow pore in a membrane, as well as for many polymeric systems such as polymer melts in the entangled regime - are robustly described by the generalized Langevin equation. Here I show that the probability distribution of phase space trajectories for all of these classical anomalous dynamics for single polymers is that of a fractional Brownian motion (fBm), while the dynamics for polymer melts between the entangled regime and the eventual diffusive regime exhibits small but systematic deviations from that of a fBm. © 2011 IOP Publishing Ltd. Source


Pe'er A.,Harvard - Smithsonian Center for Astrophysics | Markoff S.,University of Amsterdam
Astrophysical Journal | Year: 2012

While the non-thermal radio through at least near-infrared emission in the hard state in X-ray binaries (XRBs) is known to originate in jets, the source of the non-thermal X-ray component is still uncertain. We introduce a new model for this emission, which takes into account the transient nature of outflows, and show that it can explain the observed properties of the X-ray spectrum. Rapid radiative cooling of the electrons naturally accounts for the break often seen below around 10keV, and for the canonical spectral slope F νν-1/2 observed below the break. We derive the constraints set by the data for both synchrotron- and Compton-dominated models. We show that for the synchrotron-dominated case, the jet should be launched at radii comparable to the inner radius of the disk (few 100 rs for the 2000 outburst of XTE J1118+480), with typical magnetic field B ≳ 10 6 G. We discuss the consequences of our results for the possible connection between the inflow and outflow in the hard state of XRBs. © 2012. The American Astronomical Society. All rights reserved.. Source


Zhou N.,University of California at Irvine | Berge D.,University of Amsterdam | Whiteson D.,University of California at Irvine
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

Searches for dark matter production at particle colliders are complementary to direct-detection and indirect-detection experiments and especially powerful for small masses, mχ<100 GeV. An important collider dark matter signature is due to the production of a pair of these invisible particles with the initial-state radiation of a standard model particle. Currently, collider searches use individual and nearly orthogonal final states to search for initial-state jets, photons or massive gauge bosons. We combine these results across final states and across experiments to give the strongest current collider-based limits in the context of effective field theories and map these to limits on dark matter interactions with nuclei and to dark matter self-annhiliation. © 2013 American Physical Society. Source


Vitanyi P.M.B.,National Research Center for Mathematics and Computer Science | Vitanyi P.M.B.,University of Amsterdam
IEEE Transactions on Information Theory | Year: 2011

Information distance is a parameter-free similarity measure based on compression, used in pattern recognition, data mining, phylogeny, clustering and classification. The notion of information distance is extended from pairs to multiples (finite lists). We study maximal overlap, metricity, universality, minimal overlap, additivity and normalized information distance in multiples. We use the theoretical notion of Kolmogorov complexity which for practical purposes is approximated by the length of the compressed version of the file involved, using a real-world compression program. © 2011 IEEE. Source


Acute coagulopathic peripartum calamities are relatively rare but contribute importantly to maternal morbidity and mortality in the Western world. Abruptio placenta, amniotic fluid embolism, and retained fetal or placental material may lead to fulminant intravascular activation of coagulation which results in thromboembolic complications and consumption coagulopathy causing severe hemorrhage. The central underlying pathophysiological pathway in the coagulopathy associated with these syndromes is the occurrence of tissue factor, released from the placenta and amniotic fluid, in the circulation, in combination with low levels of physiological anticoagulant factors during pregnancy. The diagnosis of DIC may be made trough conventional composite scoring systems employing routine coagulation tests, whereas for the diagnosis of amniotic fluid embolism measurement of insulin like growth factor binding protein-1 seems promising. Therapy is aimed at removing the precipitating factor combined with supportive adjunctive treatment options. © 2013 Elsevier Ltd. All rights reserved. Source


Hagenaars M.A.,Radboud University Nijmegen | Oitzl M.,University of Amsterdam | Roelofs K.,Radboud University Nijmegen
Neuroscience and Biobehavioral Reviews | Year: 2014

Freezing is widely used as the main outcome measure for fear in animal studies. Freezing is also getting attention more frequently in human stress research, as it is considered to play an important role in the development of psychopathology. Human models on defense behavior are largely based on animal models. Unfortunately, direct translations between animal and human studies are hampered by differences in definitions and methods. The present review therefore aims to clarify the conceptualization of freezing. Neurophysiological and neuroanatomical correlates are discussed and a translational model is proposed. We review the upcoming research on freezing in humans that aims to match animal studies by using physiological indicators of freezing (bradycardia and objective reduction in movement). Finally, we set the agenda for future research in order to optimize mutual animal-human translations and stimulate consistency and systematization in future empirical research on the freezing phenomenon. © 2014 Elsevier Ltd. Source


van der Poll T.,University of Amsterdam | Herwald H.,Lund University
Thrombosis and Haemostasis | Year: 2014

Blood coagulation has a Janus-faced role in infectious diseases. When systemically activated, it can cause serious complications associated with high morbidity and mortality. However, coagulation is also part of the innate immune system and its local activation has been found to play an important role in the early host response to infection. Though the latter aspect has been less investigated, phylogenetic studies have shown that many factors involved in coagulation have ancestral origins which are often combined with anti-microbial features. This review gives a general overview about the most recent advances in this area of research also referred to as immunothrombosis. © Schattauer 2014. Source


Artis D.,Cornell University | Spits H.,University of Amsterdam
Nature | Year: 2015

The innate immune system is composed of a diverse array of evolutionarily ancient haematopoietic cell types, including dendritic cells, monocytes, macrophages and granulocytes. These cell populations collaborate with each other, with the adaptive immune system and with non-haematopoietic cells to promote immunity, inflammation and tissue repair. Innate lymphoid cells are the most recently identified constituents of the innate immune system and have been the focus of intense investigation over the past five years. We summarize the studies that formally identified innate lymphoid cells and highlight their emerging roles in controlling tissue homeostasis in the context of infection, chronic inflammation, metabolic disease and cancer. © 2015 Macmillan Publishers Limited. All rights reserved. Source


Dewald J.F.,University of Amsterdam
Behavioral sleep medicine | Year: 2014

This prospective quasi-experiment (N = 175; mean age = 15.14 years) investigates changes in adolescents' sleep from low-stress (regular school week) to high-stress times (exam week), and examines the (moderating) role of chronic sleep reduction, baseline stress, and gender. Sleep was monitored over three consecutive weeks using actigraphy. Adolescents' sleep was more fragmented during the high-stress time than during the low-stress time, meaning that individuals slept more restless during stressful times. However, sleep efficiency, total sleep time, and sleep onset latency remained stable throughout the three consecutive weeks. High chronic sleep reduction was related to later bedtimes, later sleep start times, later sleep end times, later getting up times, and more time spent in bed. Furthermore, low chronic sleep reduction and high baseline stress levels were related to more fragmented sleep during stressful times. This study shows that stressful times can have negative effects on adolescents' sleep fragmentation, especially for adolescents with low chronic sleep reduction or high baseline stress levels. Source


Savonije G.J.,University of Amsterdam
Astronomy and Astrophysics | Year: 2013

Context. Space missions like CoRoT and Kepler have provided numerous new observations of stellar oscillations in a multitude of stars by high precision photometry. The identification of the photometrically observed oscillations is, however, difficult and requires detailed model calculations of pulsating stars. Aims. This work compares the observed rich oscillation spectrum of the rapidly rotating B3 IV star HD 43317 with the first results obtained by a new method to calculate unstable oscillation modes in rapidly rotating stars in order to see whether some of the observed modes can be identified. Methods. The new numerical method consists of two parts. We first search for modes resonant with a prescribed forcing symmetry by moving through relevant regions of complex frequency space and monitoring any increase of the stellar response to the applied forcing and zooming in onto the resonance. These resonant non-adiabatic 2D-solutions are then fed into a 2D relaxation code with the same equations but without forcing terms. The complex oscillation frequency used in the forcing is now no longer prescribed, but added as an extra unknown. The corresponding free oscillation mode is usually obtained after a few (<10) iterations with only minor adjustment of the complex oscillation frequency. To compare with the observed light variations we calculate the "visibility" of the found unstable oscillation modes, taking into account the cancellation of the various parts of the radiating oscillating stellar surface as seen by the observer. Results. The frequencies of unstable axisymmetric g-modes, which have the highest visibility, appear to nearly coincide with the observed largest amplitude photometric variations of HD 43317, making an identification of the latter oscillations as m = 0 modes plausible. The identification of m = 1 g-modes is less straightforward, while many of the unstable even m = 2 g-modes may correspond to observed weaker photometric variations. Only one unstable r-mode has non-negligible visibility. The observationally inferred almost equidistant period spacings of ten, respectively seven, oscillation frequencies for HD 43317 cannot be reproduced. © 2013 ESO. Source


As free-living organisms, alpha-proteobacteria produce reactive oxygen species (ROS) that diffuse into the surroundings; once constrained inside the archaeal ancestor of eukaryotes, however, ROS production presented evolutionary pressures - especially because the alpha-proteobacterial symbiont made more ROS, from a variety of substrates. I previously proposed that ratios of electrons coming from FADH2 and NADH (F/N ratios) correlate with ROS production levels during respiration, glucose breakdown having a much lower F/N ratio than longer fatty acid (FA) breakdown. Evidently, higher endogenous ROS formation did not hinder eukaryotic evolution, so how were its disadvantages mitigated? I propose that the resulting selection pressures favoured the evolution of a variety of eukaryotic 'innovations': peroxisomes for FA breakdown, carnitine shuttles, the linkage of beta-oxidation to antioxidant properties, uncoupling proteins (UCPs) and using mitochondrial uncoupling during beta-oxidation to reduce ROS. Recently observed relationships between peroxisomes and mitochondria further support the model. © 2014 WILEY Periodicals, Inc. Source


Bringmann T.,University of Oslo | Vollmann M.,University of Hamburg | Weniger C.,University of Amsterdam
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

The apparent gamma-ray excess in the Galactic center region and inner Galaxy has attracted considerable interest, notably because both its spectrum and its radial distribution are consistent with an interpretation in terms of annihilating dark matter particles with a mass of about 10-40 GeV. We confront such an interpretation with an updated compilation of various indirect dark matter detection bounds, which we adapt to the specific form required by the observed signal. We find that cosmic-ray positron data strongly rule out dark matter annihilating to light leptons, or "democratically" to all leptons, as an explanation of the signal. Cosmic-ray antiprotons, for which we present independent and significantly improved limits with respect to previous estimates, are already in considerable tension with dark matter (DM) annihilation to any combination of quark final states; the first set of AMS-02 data will thus be able to rule out or confirm the DM hypothesis with high confidence. For reasonable assumptions about the magnetic field in the Galactic center region, radio observations independently put very severe constraints on a DM interpretation of the excess, in particular for all leptonic annihilation channels. © 2014 American Physical Society. Source


Levi M.,University of Amsterdam
Thrombosis Research | Year: 2014

The association between cancer and thrombosis is known for years. Besides the well-recognized connection between venous thromboembolism and malignancies, there are, however, also other manifestations of cancer-related activation of coagulation and (micro)vascular dysfunction. In fact, coagulation derangements and vascular disturbances in patients with cancer cover a wide spectrum of diseases and various clinical manifestations. In this review we will highlight the mechanisms that play a role in the systemic activation of coagulation in cancer patients, in its most severe form manifested as disseminated intravascular coagulation. Clinically, disseminated intravascular coagulation (DIC) in cancer has in general a less fulminant presentation than the types of DIC complicating sepsis and trauma. A more gradual, but also more chronic, systemic activation of coagulation can proceed subclinically. The relationship between venous thromboembolism and cancer as a consequence of the hypercoagulability will be discussed as well. Furthermore, the role of perturbed endothelium in the pathogenesis of microvascular dysfunction and microangiopathy in particular in the setting of cancer and chemo- or radiotherapy will be reviewed. © 2014 Elsevier Ltd. All rights reserved. © 2014 Elsevier Ltd. Source


Rader D.J.,University of Pennsylvania | Hovingh G.K.,University of Amsterdam
The Lancet | Year: 2014

The cholesterol contained within HDL is inversely associated with risk of coronary heart disease and is a key component of predicting cardiovascular risk. However, despite its properties consistent with atheroprotection, the causal relation between HDL and atherosclerosis is uncertain. Human genetics and failed clinical trials have created scepticism about the HDL hypothesis. Nevertheless, drugs that raise HDL-C concentrations, cholesteryl ester transfer protein inhibitors, are in late-stage clinical development, and other approaches that promote HDL function, including reverse cholesterol transport, are in early-stage clinical development. The final chapters regarding the effect of HDL-targeted therapeutic interventions on coronary heart disease events remain to be written. © 2014 Elsevier Ltd. Source


Mathus-Vliegen E.M.H.,University of Amsterdam
Best Practice and Research: Clinical Gastroenterology | Year: 2014

The obesity epidemic asks for an active involvement of gastroenterologists: many of the co-morbidities associated with obesity involve the gastrointestinal tract; a small proportion of obese patients will need bariatric surgery and may suffer from surgical complications that may be solved by minimally invasive endoscopic techniques; and finally, the majority will not be eligible for bariatric surgery and will need some other form of treatment. The first approach should consist of an energy-restricted diet, physical exercise and behaviour modification, followed by pharmacotherapy. For patients who do not respond to medical therapy but are not or not yet surgical candidates, an endoscopic treatment might look attractive. So, endoscopic bariatric therapy has a role to play either as an alternative or adjunct to medical treatment. The different endoscopic modalities may vary in mechanisms of action: by gastric distension and space occupation, delayed gastric emptying, gastric restriction and decreased distensibility, impaired gastric accommodation, stimulation of antroduodenal receptors, or by duodenal exclusion and malabsorption. These treatments will be discussed into detail. © 2014 Elsevier Ltd. All rights reserved. Source


Benschop L.,University of Amsterdam
Cochrane database of systematic reviews (Online) | Year: 2010

Endometriomata are cysts of endometriosis in the ovaries. As artificial reproductive technology (ART) cycles involve oocyte pickup from the ovaries, endometriomata may interfere with the outcome of ART. To determine the effectiveness and safety of surgery, medical treatment, combination therapy or no treatment for improving reproductive outcomes among women with endometriomata, prior to undergoing ART cycles. The review authors searched: Cochrane Menstrual Disorders and Subfertility Group Specialised Register of trials, CENTRAL (The Cochrane Library), EMBASE, MEDLINE, PubMed, PsycINFO, CINAHL, DARE, trial registers for ongoing and registered trials, citation indexes, conference abstracts on the ISI Web of Knowledge, Clinical Study Results, OpenSIGLE (July 2010) and handsearched Fertility and Sterility (2008 to 2010). Randomised controlled trials of any medical, surgical or combination therapy or expectant management for endometriomata prior to ART. The trials were independently identified and assessed for risk of bias by two authors. The authors of the trials that were potentially eligible for inclusion were contacted for additional information. Outcomes were expressed as Peto odds ratios and mean differences (MD). Eleven trials were identified of which seven were excluded and four with 312 participants were included.No trial reported live birth outcomes. One trial compared gonadotropin-releasing hormone (GnRH) agonist with GnRH antagonist. There was no evidence of a difference for clinical pregnancy rate (CPR), however the number of mature oocytes retrieved (NMOR) was greater with GnRH agonists (MD -1.60, 95% CI -2.44 to -0.76) and the ovarian response was increased (estradiol (E2) levels on day of human chorionic gonadotropin (hCG) injection) (MD -456.30, 95% CI -896.06 to -16.54).Surgery (aspiration or cystectomy) versus expectant management (EM) showed no evidence of a benefit for clinical pregnancy with either technique. Aspiration was associated with greater NMOR (MD 0.50, 95% CI 0.02 to 0.98) and increased ovarian response (E2 levels on day of hCG injection) (MD 685.3, 95% CI 464.50 to 906.10) compared to EM.Cystectomy was associated with a decreased ovarian response to controlled ovarian hyperstimulation (COH) (MD -510.00, 95% CI -676.62 to -343.38); no evidence of an effect on the NMOR compared to EM. Aspiration versus cystectomy showed no evidence of a difference in CPR or the NMOR. There was no evidence of an effect on reproductive outcomes in any of the four included trials. Further RCTs of management of endometrioma in women undergoing ART are required. Source


McKenzie A.,University of Cambridge | Spits H.,University of Amsterdam | Eberl G.,Institute Pasteur Paris
Immunity | Year: 2014

Innate lymphoid cells (ILCs) were first described as playing important roles in the development of lymphoid tissues and more recently in the initiation of inflammation at barrier surfaces in response to infection or tissue damage. It has now become apparent that ILCs play more complex roles throughout the duration of immune responses, participating in the transition from innate to adaptive immunity and contributing to chronic inflammation. The proximity of ILCs to epithelial surfaces and their constitutive strategic positioning in other tissues throughout the body ensures that, in spite of their rarity, ILCs are able to regulate immune homeostasis effectively. Dysregulation of ILC function might result in chronic pathologies such as allergies, autoimmunity, and inflammation. A new role for ILCs in the maintenance of metabolic homeostasis has started to emerge, underlining their importance in fundamental physiological processes beyond infection and immunity. Innate lymphoid cells (ILCs) can respond rapidly to changes in the tissue microenvironment with immunoregulatory cytokine production. McKenzie and colleagues review the role of ILCs in inflammation and immunity and highlight the essential role these cells play in maintaining immune homeostasis. © 2014 Elsevier Inc. Source


Romijn J.A.,University of Amsterdam
Nature Reviews Endocrinology | Year: 2016

Ultimately, almost all patients who are appropriately treated for pituitary tumours enter a chronic phase with control or cure of hormonal excess, adequate treatment of pituitary insufficiency and relief of mass effects. This phase is associated with improvement of initial signs and symptoms, but also with the persistent consequences of the initial disease and associated treatments. Pituitary insufficiency is a common denominator in many of these patients, and is associated with a reduction in quality of life, despite adequate endocrine substitution. Hypothalamic dysfunction can be present in patients previously treated for visual impairments caused by large suprasellar adenomas, or craniopharyngiomas. In addition to hypopituitarism, these patients can have multisystem morbidities caused by altered hypothalamic function, including weight gain and disturbed regulation of sleep–wake cycles. Mortality can also be affected. Patients cured of Cushing disease or acromegaly have chronic multisystem morbidities (in the case of Cushing disease, also affecting mortality) caused by irreversible effects of the previous excesses of cortisol in Cushing disease and growth hormone and insulin-like growth factor 1 in acromegaly. In addition to early diagnosis and treatment of pituitary tumours, research should focus on the amenability of these chronic post-treatment syndromes to therapeutic intervention, to improve quality of life and clinical outcomes. © 2016 Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved. Source


Morozov A.,National Research Nuclear University MEPhI | Popolitov A.,University of Amsterdam
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2015

Wilson-loop averages in Chern-Simons theory (HOMFLY polynomials) can be evaluated in different ways - the most difficult, but most interesting of them is the hypercube calculus, the only one applicable to virtual knots and used also for categorification (higher-dimensional extension) of the theory. We continue the study of quantum dimensions, associated with hypercube vertices, in the drastically simplified version of this approach to knot polynomials. At q=. 1 the problem is reformulated in terms of fat (ribbon) graphs, where Seifert cycles play the role of vertices. Ward identities in associated matrix model provide a set of recursions between classical dimensions. For q≠. 1 most of these relations are broken (i.e. deformed in a still uncontrollable way), and only few are protected by Reidemeister invariance of Chern-Simons theory. Still they are helpful for systematic evaluation of entire series of quantum dimensions, including negative ones, which are relevant for virtual link diagrams. To illustrate the effectiveness of developed formalism we derive explicit expressions for the 2-cabled HOMFLY of virtual trefoil and virtual 3.2 knot, which involve respectively 12 and 14 intersections - far beyond any dreams with alternative methods. As a more conceptual application, we describe a relation between the genus of fat graph and Turaev genus of original link diagram, which is currently the most effective tool for the search of thin knots. © 2015 The Authors. Source


Wiersinga W.M.,University of Amsterdam
Endocrine Development | Year: 2014

Autoimmune thyroid disease (AITD) is a multifactorial disease in which autoimmunity against thyroid antigens develops against a particular genetic background facilitated by exposure to environmental factors. Immunogenicity of the major thyroid antigens thyroid peroxidase, thyroglobulin (TG) and thyrotropin receptor (TSHR) is increased by genetic polymorphisms, a high number of antigenic peptides available for binding to human leukocyte antigen (HLA), and a high degree of glycosylation. Antigens bound to HLA are presented by antigen-presenting cells to T cell receptors. Further interaction between both cells is required via binding of CD40 ligand to CD40 and of B7-1/2 to CD28 for activation of T cells. Complex regulatory mechanisms serve to prevent an immune response directed against 'self'-antigens in the thymus (central tolerance) and in peripheral tissues (peripheral tolerance) with the help of regulatory T cells. Breakdown of tolerance to thyroid antigens can result in thyroid autoimmunity, which may happen in subjects who have the wrong genes and who are exposed to the wrong environment. Polymorphisms in thyroid genes (TG, TSHR) and immunoregulatory genes (HLA, CTLA4, PTPN22, CD40, FCRL3, IL2RA, FOXP3) would contribute for about 70% to AITD, and environmental exposures (like iodine, smoking, infections, parity) for the remaining 30%. Thyroidinfiltrating activated T cells may lead to cell-mediated immunity, thyroid injury and eventually hypothyroidism, whereas humoral immunity via TSHR-stimulating antibodies may give rise to hyperthyroidism. Pediatric Hashimoto's and Graves' disease are less prevalent than in adults, and the female preponderance is also less marked in children. The discrepancy is probably due to relatively less involvement of environmental insults in children, whereas the prevalence of risk alleles in AITD children is higher than in AITD adults. © 2014 S. Karger AG, Basel. Source


van Zanten H.,University of Amsterdam
Mathematical Biosciences | Year: 2013

In this paper we review recently developed methods for nonparametric Bayesian inference for one-dimensional diffusion models. We discuss different possible prior distributions, computational issues, and asymptotic results. © 2013 Elsevier Inc. Source


Rhodes R.E.,University of Victoria | De Bruijn G.-J.,University of Amsterdam
British Journal of Health Psychology | Year: 2013

Objectives The physical activity (PA) intention-behaviour gap is a topic of considerable contemporary research, given that most of our models used to understand physical activity suggest that intention is the proximal antecedent of behavioural enactment. The purpose of this study was to quantify the intention-PA gap at public health guidelines with a meta-analysis of the action control framework. Design Systematic review and meta-analysis. Methods Literature searches were conducted in July 2012 among five key search engines. This search yielded a total of 2,865 potentially relevant records; of these, 10 studies fulfilled the full eligibility criteria (N = 3,899). Results Random-effects meta-analysis procedures with correction for sampling bias were employed in the analysis for estimates of non-intenders who subsequently did not engage in physical activity (21%), non-intenders who subsequently performed physical activity (2%), intenders who were not successful at following through with their PA (36%), and successful intenders (42%). The overall intention-PA gap was 46%. Conclusion These results emphasize the weakness in early intention models for understanding PA and suggest this would be a problem during intervention. Contemporary research that is validating and exploring additional constructs (e.g., self-regulation, automaticity) that augment intention or improving the measurement of motivation seems warranted. Statement of contribution What is already known on this subject? Intention is considered the proximal antecedent of behaviour in many popular models. Intention is also an established correlate of physical activity behaviour, yet discordance is considerable in experimental research. What does this study add? This meta-analysis of studies that have assessed concordance/discordance of physical activity intention and behaviour at public health guidelines shows the intention-behaviour gap at 48% and the discordance is from intenders who do not act. The results demonstrate that discordance is not just from extreme levels of intention or behaviour (e.g., intend to exercise six times but only exercise five), but from levels that are relevant to health promotion. © 2013 The British Psychological Society. Source


Environmental education scholars have hailed the emergence of the discourse of education for sustainable development (ESD) as a progressive transition in the field. The author argues that there are some salient aspects present in sustainability discourse that present ethical paradoxes as well as empirical dilemmas. Discourse on sustainable development singles out economic development, which might have created the current ecological problems in the first place, as part of the solution. It is empirically questionable whether the industrial production necessary to expand the 'economic pie' to include the most dispossessed, is possible without further degrading the environment. In an educational context, ESD replaces a problem orientation associated with environmental education and shifts the focus to the inclusion of social issues and economic development. ESD masks its anthropocentric agenda and may in fact be counterproductive to the efficacy of environmental education in fostering a citizenry that is prepared to address the anthropogenic causes of environmental problems. © 2011 John Wiley & Sons, Ltd and ERP Environment. Source


van der Sijpt E.,University of Amsterdam
Culture, Health and Sexuality | Year: 2012

In the East Province of Cameroon, respectable womanhood has long been intrinsically related to ethics of production and reproduction: women attain social standing through productive work in the fields and through the reproduction of children - preferably within a marital setting. Yet, in the face of current alternative 'horizons of honour' such as schooling, employment or relationships with rich urban men, women's intentions with regard to marriage and motherhood acquire different meanings. On their pathways to urban forms of honour, formal engagements and childbearing are often postponed, while premarital sexual encounters proliferate. This paper explores the meanings of pregnancy within the context of these fragile relationships and women's urban aspirations; fertility will be shown to be a 'bet' that may either disrupt or stabilize urban affairs and ambitions. As such, pregnancies can be strategically anticipated and deliberately disclosed or unexpectedly encountered and secretly disrupted. This paper sheds light on women's strategies of concealment and disclosure of pregnancies and shows that these practices are often inspired by a notion of the 'right timing' of particular reproductive conjunctures - a notion that is of increasing relevance in current frames of female honour in Cameroon. © 2012 Copyright Erica van der Sijpt. Source


Moyer E.,University of Amsterdam
Culture, Health and Sexuality | Year: 2012

Most HIV treatment guidelines advise people who test positive to disclose their status to improve adherence and garner psychosocial care and support. Similarly, advocacy groups for people living with HIV encourage disclosure as a key component of fighting self- and community-based stigma. Although there is arguably much to be gained by disclosing, there is also much at stake, including issues of individual and family honour and the possibility of living a 'normal' life. Starting with the question, Faidha gani? or 'What's the point?' this paper attempts to shed light on motives for disclosure and non-disclosure. The arguments draw from a qualitative study among young HIV-positive adults in eastern Africa and, most specifically, an in-depth case study of one couple in Zanzibar. © 2012 Copyright Eileen Moyer. Source


Afink G.B.,University of Amsterdam
Thyroid : official journal of the American Thyroid Association | Year: 2010

BACKGROUND: Thyroid hormone is prerequisite for proper fetal and postnatal neurodevelopment, growth, and metabolism. Although much progress has been made in the characterization of genes implicated in thyroid development and function, the majority of genes involved in this process are still unknown. We have previously applied serial analysis of gene expression (SAGE) to identify novel genes preferentially expressed in the thyroid, and this has resulted in the characterization of DUOX2 and IYD (also known as DEHAL1), two genes encoding essential enzymes in the production of thyroid hormone. In the current study we characterize the gene C16orf89, which is linked to another thyroid-specific SAGE tag CCAGCTGCCT. METHODS: We establish tissue-specific expression of C16orf89 using novel tissue-specific SAGE libraries and quantitative polymerase chain reaction. In addition, we characterize the C16orf89 gene and protein, and analyze its mRNA expression in response to thyrotropin and during mouse development. RESULTS: C16orf89 is predominantly expressed in human thyroid tissue with a specificity intermediate between thyroid transcription factors and proteins involved in thyroid hormone synthesis. C16orf89 shows the same expression pattern as Nkx2-1 (thyroid transcription factor 1) from embryonic day (E) 17.5 onward in the developing mouse thyroid and lung. The developmental timing of C16orf89 mRNA expression is similar to that of the iodide transporter Slc5a5 (also known as Nis). Both transcripts are detected from E17.5 in the developing thyroid. This is clearly later than the onset of Tg mRNA expression (from E14.5), while Nkx2-1 and Iyd mRNA can already be detected in the E12.5 thyroid. In in vitro cell culture C16orf89 expression is stimulated by thyrotropin. The major splice variant encodes a 361 amino acid protein that is well conserved between mammals, contains an N-terminal signal peptide, is secreted in a glycosylated form, and does not contain any known functional domain. CONCLUSIONS: We present a novel gene highly expressed in thyroid that encodes a currently enigmatic protein. Source


We report on experimental high-resolution spectroscopic studies in combination with advanced theoretical calculations that focus on the excited-state dynamics of various forms of the chromophore of the Photoactive Yellow Protein (PYP), and the dependence of these dynamics on conformational and isosteric structure, as well as the biological environment. Three-colour nanosecond multiphoton ionization pump-probe studies confirm and extend previous conclusions that the dominant decay channel of the lowest excited pipi* state (the so-called V' state) of methyl-4-hydroxycinnamate is picosecond internal conversion to the adiabatically lower nPi* state, and enable us to resolve apparent contradictions with picosecond pump-probe studies. Comparison of multiphoton ionization and laser induced fluorescence excitation spectra leads to the assignment of the hitherto elusive excitation spectrum of the V(pipi*) state. Complexation of methyl-4-hydroxycinnamate with water radically changes the excited-state dynamics; internal conversion to the npi* state is absent, and bond isomerization channels instead play a prominent role. Excited states of the thio-ester compound, the form in which the chromophore is present in PYP, have till the present study remained out of reach of gas-phase studies. The excitation spectra obtained here show a broad, almost structureless band system, giving evidence for enhanced nonradiative decay channels. The gas-phase results will be discussed in the context of results from ultrafast studies on these two chromophores in solution. Source


Kissling W.D.,University of Amsterdam | Schleuning M.,Biodiversity And Climate Research Center Bik d Senckenberg Gesellschaft For Naturforschung
Ecography | Year: 2015

Trophic interactions among multiple species are ubiquitous in nature and their importance for structuring ecological communities has been extensively demonstrated at local spatial scales. However, how local species interactions scale-up to large spatial scales and how they contribute to shape species distributions and diversity patterns at macroecological extents remains less clear. Here, we provide an overview of recent and potential future developments in macroecology that explore the role of antagonistic and mutualistic interactions among multiple species across trophic levels. Recent studies broadly represent two analytical methods (analyses of species richness and ecological networks) and provide evidence that plant-animal interactions (e.g. pollination, frugivory) and predator-prey interactions influence large-scale richness patterns and that ecological network structure varies systematically at macroscales. Current methodological problems and challenges are related to defining the functional links in cross-trophic richness analyses, understanding trait effects in multispecies interactions, and addressing sampling effects when analyzing multiple ecological networks across large spatial extents. Key topics for future research are 1) testing paleoclimatic imprints on interaction diversity, 2) understanding macroevolution and the phylogenetic structure of multispecies interactions, 3) quantifying contemporary spatial and temporal variability in complex ecological networks, and 4) predicting novel interactions under global change. Moreover, we see great potential for a deeper bidirectional integration of macroecology and network research, e.g. by analyses of trait complementarity and functional diversity of interacting groups and by employing species distribution modeling to predict changes in functional network structure. Addressing these key topics and achieving a better integration between these two research fields will significantly advance our understanding of the ecological and evolutionary drivers of multispecies interactions. This could also help to develop more realistic forecasts of changes in biodiversity under climate and land use change. © 2014 The Authors. Source


Cohen M.X.,University of Amsterdam | Cohen M.X.,University of Arizona
Current Biology | Year: 2011

The hippocampus and prefrontal cortex interact to support working memory (WM) and long-term memory [1-3]. Neurophysiologically, WM is thought to be subserved by reverberatory activity of distributed networks within the prefrontal cortex (PFC) [2, 4-8], which become synchronized with reverberatory activity in the hippocampus [1, 4]. This electrophysiological synchronization is difficult to study in humans because noninvasive electroencephalography (EEG) cannot measure hippocampus activity. Here, using a novel integration of EEG and diffusion-weighted imaging, it is shown that individuals with relatively stronger anatomical connectivity linking the hippocampus to the right ventrolateral PFC (ventral Brodmann area 46) exhibited slower frequency neuronal oscillations during a WM task. Furthermore, subjects with stronger hippocampus-PFC connectivity were better able to encode the complex pictures used in the WM task into long-term memory. These findings are consistent with models suggesting that electrophysiological oscillations provide a mechanism of long-range interactions [9] and link hippocampus-PFC structural connectivity to PFC rhythmic electrical dynamics and memory performance. More generally, these results highlight the importance of incorporating individual differences when linking structure and function to cognition. © 2011 Elsevier Ltd. Source


Dorner T.,Charite University Hospital Berlin and Deutsches Rheumaforschungszentrum | Kinnman N.,Merck Serono SA Geneva | Tak P.P.,University of Amsterdam
Pharmacology and Therapeutics | Year: 2010

B cell-depletion therapy, particularly using anti-CD20 treatment, has provided proof of concept that targeting B cells and the humoral response may result in clinical improvements in immune-mediated inflammatory disease. In this review, the mechanisms of action of B cell-targeting drugs are investigated, and potential biomarkers associated with response to treatment in patients with autoimmune diseases are identified. Most available data relate to B cell depletion using anti-CD20 therapy (rituximab) in patients with rheumatoid arthritis (RA). Treatment leads to significant clinical benefit, but apparently fails to deplete long-lived plasma cells, and discontinuation is associated with relapse. Biomarkers commonly used in studies of B cell-targeted therapies include rheumatoid factor, anti-citrullinated peptide antibodies, and immunoglobulin (Ig) levels. More recently, there has been interest in markers such as B cell phenotype analysis, and B lymphocyte stimulator (BLyS)/a proliferation-inducing ligand (APRIL), the latter particularly in studies of the IgG Fc-transmembrane activator and CAML interactor (TACI) fusion protein (atacicept) and anti-BLyS therapy (belimumab). Data from clinical trials of B cell-depleting agents in RA suggest that specific autoantibodies, BLyS, APRIL, and circulating and synovial B lineage cell levels may have potential as biomarkers predictive of response to treatment. Further trials validating these markers against clinical outcomes in RA are required. In patients with systemic lupus erythematosus, Fc receptors and levels of circulating immune cells (including B cells and natural killer cells) may be relevant markers. © 2010 Elsevier Inc. All rights reserved. Source


Rieder B.,University of Amsterdam
Proceedings of the 3rd Annual ACM Web Science Conference, WebSci 2013 | Year: 2013

This paper describes Netvizz, a data collection and extraction application that allows researchers to export data in standard file formats from different sections of the Facebook social networking service. Friendship networks, groups, and pages can thus be analyzed quantitatively and qualitatively with regards to demographical, post-demographical, and relational characteristics. The paper provides an overview over analytical directions opened up by the data made available, discusses platform specific aspects of data extraction via the official Application Programming Interface, and briefly engages the difficult ethical considerations attached to this type of research. Copyright 2013 ACM. Source


Verlinde E.,University of Amsterdam
Journal of High Energy Physics | Year: 2011

Starting from first principles and general assumptions we present a heuristic argument that shows that Newton's law of gravitation naturally arises in a theory in which space emerges through a holographic scenario. Gravity is identified with an entropic force caused by changes in the information associated with the positions of material bodies. A relativistic generalization of the presented arguments directly leads to the Einstein equations. When space is emergent even Newton's law of inertia needs to be explained. The equivalence principle auggests that it is actually the law of inertia whose origin is entropic. © SISSA 2011. Source


Cohen M.X.,University of Amsterdam
International Journal of Psychophysiology | Year: 2015

The purpose of this paper is to compare the effects of different spatial transformations applied to the same scalp-recorded EEG data. The spatial transformations applied are two referencing schemes (average and linked earlobes), the surface Laplacian, and beamforming (a distributed source localization procedure). EEG data were collected during a speeded reaction time task that provided a comparison of activity between error vs. correct responses. Analyses focused on time-frequency power, frequency band-specific inter-electrode connectivity, and within-subject cross-trial correlations between EEG activity and reaction time. Time-frequency power analyses showed similar patterns of midfrontal delta-theta power for errors compared to correct responses across all spatial transformations. Beamforming additionally revealed error-related anterior and lateral prefrontal beta-band activity. Within-subject brain-behavior correlations showed similar patterns of results across the spatial transformations, with the correlations being the weakest after beamforming. The most striking difference among the spatial transformations was seen in connectivity analyses: linked earlobe reference produced weak inter-site connectivity that was attributable to volume conduction (zero phase lag), while the average reference and Laplacian produced more interpretable connectivity results. Beamforming did not reveal any significant condition modulations of connectivity. Overall, these analyses show that some findings are robust to spatial transformations, while other findings, particularly those involving cross-trial analyses or connectivity, are more sensitive and may depend on the use of appropriate spatial transformations. © 2014 Elsevier B.V. Source


An important theoretical challenge for theorizing about power dynamics in societal transitions is the transformation of power itself. In this respect, it is especially puzzling how agency at the level of novel practices can extend beyond the habitual, how it can draw on structures and destructure at the same time and in doing so, how it might emerge both as a creative and a destructive force. This article addresses this puzzle by scrutinizing and refining multi-level conceptions of power in the field of transitions studies. In the first part, it explores one specific multi-level framework by Grin and Van Tatenhove in a longitudinal case study of wind energy projects in Denmark and establishes that it has four conceptual short-comings-relating to (1) temporality; (2) relationality; (3) materiality; and (4) creativity-that this article claims to overcome in the second part. In order to so, it draws on several practice theories for an extended framework that enables the unpacking of the interplay between creativity and transition processes. © 2013 Springer Science+Business Media New York. Source


Brommelstroet M.T.,University of Amsterdam
Computers, Environment and Urban Systems | Year: 2013

Planning Support Systems (PSSs) are a family of computer based instruments specifically designed to support actors in their complex tasks in the field of planning. There is a gap between the high expectations that PSS developers have about the usefulness of their instruments and the instruments' application in daily planning practice. PSS academics have proposed several ways to close this so-called implementation gap through a range of software, hardware and orgware approaches. Several of these approaches have been applied in practical planning settings. There is however a lack of consistent and structured reporting on the effectiveness of these approaches in improving PSS performance. Therefore, it is hard to distinguish between successful and less successful strategies, and it is difficult to draw overall lessons. This paper (1) proposes a comprehensive multidimensional framework that operationalizes PSS performance, and (2) analyses how recent PSS implementation studies have reported on this performance. The developed framework, based on literature from Group Model Building and group psychology, is sensitive to a wide variety of performance dimensions and therefore forms a useful guideline for assessing PSS implementation strategies. Studying these in a common framework supports the potential transfer of lessons to other PSS implementations. Most of the analyzed studies only posed hypotheses about which dimensions are improved through a specific strategy, but did not report on measuring impacts. By structurally measuring the effectiveness of a range of strategies to improve PSS implementation, lessons can be exchanged and a consistent body of knowledge can be built. © 2012 Elsevier Ltd. Source


Davidson M.D.,University of Amsterdam
Ecological Economics | Year: 2013

Various attempts have been made to amalgamate the concepts of intrinsic value and ecosystem services, often with a stop-over at the economic concept of existence value. These attempts are based on a confusion of concepts, however. In this article, two types of non-use values are distinguished: warm glow value, related to the satisfaction people may derive from altruism towards nature, and existence value, related to the satisfaction people may derive from the mere knowledge that nature exists and originating in the human need for self-transcendence. As benefits to humans, warm glow and existence values can be considered ecosystem services. Neither warm glow value nor existence value represents benefits to nature itself, however. Intrinsic value lies outside the scope of the wide palette of ecosystem services.Although the concept of ecosystem services does not cover benefits to nature and the intrinsic value of such benefits, intrinsic value is not necessarily incompatible with economic valuation. Although a deontological ethics does not allow economic valuation of nature as an end in itself, consequentialism does. In consequentialism, however, intrinsic value is not attributed to nature itself, but to benefits to nature. These benefits can be economically valued on the basis of benefit transfer. © 2013 Elsevier B.V. Source


Background. The clinical impact of trial-based quality of life (QL) outcomes is frequently underestimated due, in part, to prejudice and lack of knowledge by the medical community. The objectives of this paper are to show that QL assessments build upon an empirically based and stringent approach to measurement and QL outcomes should not be viewed nor handled differently than any other parameter in medical research. Material and methods. Literature overview. Results. The objectives are substantiated with empirical evidence showing that: (1) existing QL measures are as reliable as most other clinical outcomes; (2) available guidelines improve the quality of trial-based QL data; (3) QL data have strong prognostic value for survival; (4) clinical significance of QL data can be established; and (5) accounting for response-shift effects in QL data over time is feasible. Finally, the investigation of the genetic disposition of QL is described as an emerging area of research. Discussion. It is a waste of effort and money and also unethical when collected trial-based QL data are not used to their full power. QL and other patient-reported outcomes deserve to be included in more trials, with full disclosure of all results, and standardized interpretation. Only the combined use of patient-reported and clinical outcomes will enable the examination of the extent to which cancer patients live a qualitatively good life as long as possible. Source


Krishna R.,University of Amsterdam
Physical Chemistry Chemical Physics | Year: 2015

This work investigates the transient equilibration process when partially miscible ternary liquid mixtures of two different compositions are brought into contact with each other. Diffusional coupling effects are shown to become increasingly significant as the mixture compositions approach the meta-stable regions of the phase equilibrium diagrams. The proper modelling of coupled diffusion phenomena requires the use of a Fick diffusivity matrix [D], with inclusion of non-zero off-diagonal elements. The primary objective of this article is to develop a simple, robust, procedure for the estimation of the matrix [D], using the Maxwell-Stefan (M-S) formulation as a convenient starting point. In the developed simplified approach, the Fick diffusivity matrix [D] is expressed as the product of a scalar diffusivity and the matrix of thermodynamic correction factors [Γ]. By detailed examination of experimental data for the matrix [D] in a wide variety of ternary mixtures, it is deduced that the major contribution of diffusional coupling arises from the contributions of non-ideal solution thermodynamics, quantified by the matrix of thermodynamic correction factors [Γ]. An important consequence of strong thermodynamic coupling is that equilibration trajectories are serpentine in shape and may exhibit incursions into meta-stable zones opening up the possibility of spontaneous emulsification and the Ouzo effect. If diffusional coupling effects are ignored, the equilibration trajectory is linear in composition space. For a wide variety of partially miscible ternary mixtures, it is demonstrated that the corresponding linear equilibration trajectories do not anticipate the possibility of emulsification. © 2015 the Owner Societies. Source


Schultze U.,Southern Methodist University | Avital M.,University of Amsterdam
Information and Organization | Year: 2011

Information Systems (IS) publications that use interviews for data generation tend to provide very little insight into the research process and very few rely on a carefully chosen and well-articulated interviewing method. Given the wide variety of interviewing approaches available to qualitative researchers, it seems that the IS discipline is lagging behind and can easily enhance its methodological sophistication. In this paper, we address this opportunity by (i) highlighting the potential of interviewing as a means of generating data that provides insight into people's experiential life; (ii) discussing the various epistemological stances that can be taken to interviewing; (iii) introducing and illustrating three interviewing methods (i.e., appreciative, laddering and photo-diary interviewing); and (iv) juxtaposing these methods to identify the conditions under which they are most effective. © 2010 Elsevier Ltd. Source


Hofman D.M.,University of Amsterdam | Rollier B.,University of Groningen
Nuclear Physics B | Year: 2015

Two dimensional Warped Conformal Field Theories (WCFTs) may represent the simplest examples of field theories without Lorentz invariance that can be described holographically. As such they constitute a natural window into holography in non-. AdS space-times, including the near horizon geometry of generic extremal black holes. It is shown in this paper that WCFTs posses a type of boost symmetry. Using this insight, we discuss how to couple these theories to background geometry. This geometry is not Riemannian. We call it Warped Geometry and it turns out to be a variant of a Newton-Cartan structure with additional scaling symmetries. With this formalism the equivalent of Weyl invariance in these theories is presented and we write two explicit examples of WCFTs. These are free fermionic theories. Lastly we present a systematic description of the holographic duals of WCFTs. It is argued that the minimal setup is not Einstein gravity but an SL (2,R)×U(1) Chern-Simons Theory, which we call Lower Spin Gravity. This point of view makes manifest the definition of boundary for these non-AdS geometries. This case represents the first step towards understanding a fully invariant formalism for WN field theories and their holographic duals. © 2015 The Authors. Source


In contested wind farm developments, the dominant issue concerns scenic impact and the landscape at the proposed site. The number of large wind power schemes that have failed is growing. The case analysed here is a near-shore wind farm in the Dutch part of the Wadden Sea, in 2001 the largest wind project (278 MW) ever proposed in the Netherlands. The government refused to negotiate with civil society organizations representing various landscape values, primarily with the WaddenVereniging and its allies. The often suggested idea that siting wind farms offshore could solve the problems encountered onshore is naïve and far too simple. Siting issues offshore are just as relevant as onshore, as this case study illustrates. As most current offshore developments, the case concerns a near-shore development. It would have been highly visible in an iconic landscape. In such cases, the main dialogue is similar to onshore schemes, which is about impact on the landscape, or 'seascape', as perceived by the public. The paper provides description of the historical development of the area, highlighting significant scenic and ecological values, as well as cultural heritage and its importance for tourism and the rural economy. The acceptability and the assessment of different qualities in relation to wind farm siting are analysed with a survey among members of the WaddenVereniging, the national environmental organization for the protection of the Wadden region. The analysis reveals that these environmentalists with their strong identification with the landscape, believe that there are suitable sites for wind turbines in this sensitive area. However, the spatial layout that was chosen by the developers was based on a landscape assessment of the governmental architect. This was a highly technocratic, top-down decision that did not take account of the landscape preferences of the public. This decision evoked its opposition, and eventually, the WaddenVereniging succeeded in generating sufficient national political support to scupper this project. © 2009 Elsevier Ltd. All rights reserved. Source


De Vries G.K.D.,University of Amsterdam
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2013

In this paper we introduce an approximation of the Weisfeiler-Lehman graph kernel algorithm aimed at improving the computation time of the kernel when applied to Resource Description Framework (RDF) data. Typically, applying graph kernels to RDF is done by extracting subgraphs from a large RDF graph and computing the kernel on this set of subgraphs. In contrast, our algorithm computes the Weisfeiler-Lehman kernel directly on the large RDF graph, but still retains the subgraph information. We show that this algorithm is faster than the regular Weisfeiler-Lehman kernel for RDF data and has at least the same performance. Furthermore, we show that our method has similar or better performance, and is faster, than other recently introduced graph kernels for RDF. © 2013 Springer-Verlag. Source


Sluys R.,Naturalis Biodiversity Center | Sluys R.,University of Amsterdam
Biodiversity and Conservation | Year: 2013

Several ways have been suggested to improve the poor status of taxonomy as well as to overcome the taxonomic impediment and thus to speed up species discovery and documentation, such as: DNA barcoding, creation of databases of taxa and identification tools, online quantum contributions, standardization of morphological features, training of a new generation of taxonomists. The paper comments on the desirability and effectiveness of these presumed remedies. It is argued that the analytical, hypothesis-testing nature of taxonomic research is not well understood or appreciated and forms a major constraint on the rate of taxonomic descriptions. The various components of the taxonomic method, such as exploration, data, analysis, and results, interact in a complex manner that resembles the erratic, bouncing behaviour of a pinball machine. Species hypotheses probably are the most tested hypotheses in the natural sciences. The introduction of cybertaxonomy instrumentation and infrastructure will not alleviate the time-consuming, intrinsically analytical and hypothesis-testing process underlying the description and/or identification of each taxon. Long-term survival of the discipline of taxonomy, thus guaranteeing the future cumulative taxonomic output of amateurs and professionals, is endangered by a diminishing workforce of adequately trained professional systematists. The only way to increase the pace of a well-documented and scientifically useful taxic inventory of the world's biodiversity is to increase the number of professional taxonomists. © 2013 Springer Science+Business Media Dordrecht. Source


De Deken J.,University of Amsterdam
Journal of European Social Policy | Year: 2013

Privatization entails a number of quite different aspects that overlap only to some extent: (1) responsibility in provision; (2) possibilities of exit from statutory plans; (3) the transfer of the administration and management of schemes from public bodies acting in a unitary non-competitive administrative environment to private sector actors acting in a more fragmented competitive market based environment; (4) the transfer of the risks of retirement from the collective to the individual; and (5) the 'recommodification' and 'financialization' of retirement risks. The paper develops a compound index of private pension provision based on a number of quantifiable variables (theoretical replacement rates of public plans, assets of funded pension schemes, private pension expenditure and coverage by private pension plans) that tries to tap into these different aspects. It can be used to empirically categorize the extent to which Organisation for Economic Co-operation and Development (OECD) countries have privatized their pension provision. © The Author(s) 2013. Source


de Boeck P.,University of Amsterdam | Partchev I.,Catholic University of Leuven
Journal of Statistical Software | Year: 2012

A category of item response models is presented with two defining features: they all (i) have a tree representation, and (ii) are members of the family of generalized linear mixed models (GLMM). Because the models are based on trees, they are denoted as IRTree models. The GLMM nature of the models implies that they can all be estimated with the glmer function of the lme4 package in R. The aim of the article is to present four subcategories of models, the first two of which are based on a tree representation for response categories: 1. linear response tree models (e.g., missing response models), 2. nested response tree models (e.g., models for parallel observations regarding item responses such as agreement and certainty), while the last two are based on a tree representation for latent variables: 3. linear latent-variable tree models (e.g., models for change processes), and 4. nested latent-variable tree models (e.g., bi-factor models). The use of the glmer function is illustrated for all four subcategories. Simulated example data sets and two service functions useful in preparing the data for IRTree modeling with glmer are provided in the form of an R package, irtrees. For all four subcategories also a real data application is discussed. Source


Alkemade A.,University of Amsterdam
Frontiers in Neuroanatomy | Year: 2015

Thyroid hormone (TH) plays an essential role in normal brain development and function. Both TH excess and insufficiency during development lead to structural brain abnormalities. Proper TH signaling is dependent on active transport of the prohormone thyroxine (T4) across the blood-brain-barrier and into brain cells. In the brain T4 undergoes local deiodination into the more active 3,3',5-triiodothyronine (T3), which binds to nuclear TH receptors (TRs). TRs are already expressed during the first trimester of pregnancy, even before the fetal thyroid becomes functional. Throughout pregnancy, the fetus is largely dependent on the maternal TH supply. Recent studies in mice have shown that normal hypothalamic development requires intact TH signaling. In addition, the development of the human lateral hypothalamic zone coincides with a strong increase in T3 and TR mRNA concentrations in the brain. During this time the fetal hypothalamus already shows evidence forTH signaling. Expression of components crucial for central TH signaling show a specific developmental timing in the human hypothalamus. A coordinated expression of deiodinases in combination with TH transporters suggests that TH concentrations are regulated to prevent untimely maturation of brain cells. Even though the fetus depends on the maternal TH supply, there is evidence suggesting a role for the fetal hypothalamus in the regulation of TH serum concentrations. A decrease in expression of proteins involved in TH signaling towards the end of pregnancy may indicate a lower fetal TH demand. This may be relevant for the thyrotropin (TSH) surge that is usually observed after birth, and supports a role for the hypothalamus in the regulation of TH concentrations during the fetal period anticipating birth. © 2015 Alkemade. Source


Houtkooper R.H.,Ecole Polytechnique Federale de Lausanne | Houtkooper R.H.,University of Amsterdam | Pirinen E.,Ecole Polytechnique Federale de Lausanne | Pirinen E.,University of Eastern Finland | Auwerx J.,Ecole Polytechnique Federale de Lausanne
Nature Reviews Molecular Cell Biology | Year: 2012

Since the beginning of the century, the mammalian sirtuin protein family (comprising SIRT1-SIRT7) has received much attention for its regulatory role, mainly in metabolism and ageing. Sirtuins act in different cellular compartments: they deacetylate histones and several transcriptional regulators in the nucleus, but also specific proteins in other cellular compartments, such as in the cytoplasm and in mitochondria. As a consequence, sirtuins regulate fat and glucose metabolism in response to physiological changes in energy levels, thereby acting as crucial regulators of the network that controls energy homeostasis and as such determines healthspan. © 2012 Macmillan Publishers Limited. All rights reserved. Source


Nieuwenhuizen T.M.,University of Amsterdam
Journal of Physics: Conference Series | Year: 2014

The outcome of a single quantum experiment is unpredictable, except in a pure-state limit. The definite process that takes place in the apparatus may either be intrinsically random or be explainable from a deeper theory. While the first scenario is the standard lore, the latter implies that quantum mechanics is emergent. In that case, it is likely that one has to reconsider radiation by accelerated charges as a physical effect, which thus must be compensated by an energy input. Stochastic electrodynamics, for example, asserts that the vacuum energy arises from classical fluctuations with energy 1/2ω per mode. In such theories the stability of the hydrogen ground state will arise from energy input from fluctuations and output by radiation, hence due to an energy throughput. That flux of energy constitutes an arrow of time, which we call the "subquantum arrow of time". It is related to the stability of matter and it is more fundamental than, e.g., the thermodynamic and cosmological arrows. © Published under licence by IOP Publishing Ltd. Source


Schall P.,University of Amsterdam | Van Hecke M.,Leiden University
Annual Review of Fluid Mechanics | Year: 2010

Shear bands, localized regions where shear flows concentrate, form in many complex fluids under a wide range of circumstances. In this review, we outline the main mechanisms that cause shear banding in complex fluids with granularity: foams, emulsions, colloidal suspensions, and granular matter. Apart from shear bands caused by continuum-scale mechanisms such as stress inhomogeneities and flow instabilities, we discuss a range of shear-banding phenomena for which the particle scale plays a crucial role. Copyright © 2010 by Annual Reviews. All rights reserved. Source


van Wijngaarden G.J.,University of Amsterdam
Quaternary International | Year: 2012

To understand the human perception of landscapes in the past, archaeologists would require knowledge of the immaterial landscape elements: the stories that are connected to physical landscape features. One way of acquiring access to such stories is through written literature (poetry, prose), which has survived centuries and is connected to specific landscapes. In this article, a particular powerful example is examined: Homer's Odyssey. It will be argued that the epic myth has strong interconnections to the landscape of the Ionian Islands in Greece. Whether the Homeric Geography is reflected in the current landscape remains open for debate. However, the text itself has played an important role in the formation of the archaeological record, in the way classical scholarship in the region has developed and in public perceptions of archaeology and history. Because of the extremely long narrative history, Homer's Odyssey has played a structuring role with regard to the cultural landscape. © 2011 Elsevier Ltd and INQUA. Source


Communication among stakeholders is commonly held to improve agreement on facts and management goals. Results from statistical network analyses of six natural resource management systems indicate that the effects of communication depend on context. If communication affects stakeholder knowledge and values, it fosters agreement between stakeholder groups but it results in more disagreement within stakeholder groups. In addition, more centralized communication networks have more disagreement, especially within stakeholder groups, while co-management systems have more disagreement between stakeholder groups. The results may reflect communication effects but also selection effects: the propensity of stakeholders or management systems to establish communication ties between participants with dissimilar knowledge and values. In addition, the results may be linked to different phases in the management process. The conclusion includes a reflection on the need for further research to address these possibilities. © 2013 by the author(s). Source


Neo-liberalism and decentralisation are eroding the capacity of central governments to implement their national spatial objectives. National government, with fewer financial and political resources at its disposal, has little power to intervene in strategic urban development, because cities have sufficient autonomy to define their own land use plans. This paper challenges this understanding of the contemporary condition of national spatial planning. It demonstrates that, although national governments have a weaker grip on local spatial dynamics, they play an active role in governing complex spatial development. Two urban development projects in the Dutch Randstad will be discussed in order to demonstrate empirically four different logics of involvement: endorsement, monetary impulse, propulsion and effectuation. It is concluded that there is great potential for national planning in a 'lighter' profile, with instruments used to strengthen the interconnectivity of networks-a condition for generating strategic capacity and ensuring the governability of spatial policies. © 2012 Urban Studies Journal Limited. Source


Kopnina H.,University of Amsterdam
Journal of Environmental Education | Year: 2013

This critical essay based on empirical study draws upon research on the differences in attitudes toward consumption among Dutch upper-elementary school children with different socioeconomic backgrounds. This article examines two strands of theory: critical literature on the conceptualization and practice of sustainable consumption, and the theory of postmaterialist values. By synthesizing these strands of theory the author outlines a number of paradoxes and challenges in theory and practice of consumption and lays a foundation for teaching sustainable consumption at the upper-elementary school level. The Cradle-to-Cradle framework is proposed as a form of strategically significant environmental education that can be used for teaching consumption. © 2013 Copyright Taylor and Francis Group, LLC. Source