1,132 research outputs found
Modelling the electronic structure and magnetic properties of LiFeAs and FeSe using hybrid-exchange density functional theory
The electronic structure and magnetic properties of LiFeAs and FeSe have been
studied using hybrid exchange density functional theory. The total energies for
a unit cell in LiFeAs and FeSe with different spin states including
non-magnetic and spin-2 are calculated. The spin-2 configuration has the lower
energy for both LiFeAs and FeSe. The computed anti-ferromagnetic exchange
interactions between spins on the nearest (next nearest) neighbouring Fe atoms
in LiFeAs and FeSe are approximately 14 (17) meV and 6 (13) meV respectively.
The total energies of the checkerboard and stripe-type anti-ferromagnetic
ordering for LiFeAs and FeSe are compared, yielding that for LiFeAs the
checkerboard is lower whereas for FeSe the stripe-type is lower. However, owing
to the fact that the exchange interaction of the next nearest neighbour is
larger than that of the nearest one, which means that the collinear ordering
might be the ground state. These results are in agreement with previous
theoretical calculations and experiments. Especially the calculations for
LiFeAs indicate a co-existence of conducting d-bands at the Fermi surface and
d-orbital magnetism far below the Fermi surface. The theoretical results
presented here might be useful for the experimentalists working on the
electronic structure and magnetism of iron-based superconductors.Comment: 7 pages, 4 figures, 1 table, accepted by Solid State Communication
2015 ACVIM Small Animal Consensus Statement on Seizure Management in Dogs
This report represents a scientific and working clinical consensus statement on seizure management in dogs based on current literature and clinical expertise. The goal was to establish guidelines for a predetermined, concise, and logical sequential approach to chronic seizure management starting with seizure identification and diagnosis (not included in this report), reviewing decisionâmaking, treatment strategies, focusing on issues related to chronic antiepileptic drug treatment response and monitoring, and guidelines to enhance patient response and quality of life. Ultimately, we hope to provide a foundation for ongoing and future clinical epilepsy research in veterinary medicine
Spatial Epidemiology: Current Approaches and Future Challenges
Spatial epidemiology is the description and analysis of geographic variations in disease with respect to demographic, environmental, behavioral, socioeconomic, genetic, and infectious risk factors. We focus on small-area analyses, encompassing disease mapping, geographic correlation studies, disease clusters, and clustering. Advances in geographic information systems, statistical methodology, and availability of high-resolution, geographically referenced health and environmental quality data have created unprecedented new opportunities to investigate environmental and other factors in explaining local geographic variations in disease. They also present new challenges. Problems include the large random component that may predominate disease rates across small areas. Though this can be dealt with appropriately using Bayesian statistics to provide smooth estimates of disease risks, sensitivity to detect areas at high risk is limited when expected numbers of cases are small. Potential biases and confounding, particularly due to socioeconomic factors, and a detailed understanding of data quality are important. Data errors can result in large apparent disease excess in a locality. Disease cluster reports often arise nonsystematically because of media, physician, or public concern. One ready means of investigating such concerns is the replication of analyses in different areas based on routine data, as is done in the United Kingdom through the Small Area Health Statistics Unit (and increasingly in other European countries, e.g., through the European Health and Environment Information System collaboration). In the future, developments in exposure modeling and mapping, enhanced study designs, and new methods of surveillance of large health databases promise to improve our ability to understand the complex relationships of environment to health
Internal construct validity of the Warwick-Edinburgh Mental Well-being Scale (WEMWBS): a Rasch analysis using data from the Scottish Health Education Population Survey
Background: The Warwick-Edinburgh Mental Well-Being Scale (WEMWBS) was developed to meet demand for instruments
to measure mental well-being. It comprises 14 positively phrased Likert-style items and fulfils classic criteria for scale development. We report here the internal construct validity of WEMWBS from the perspective of the Rasch measurement model.
Methods: The model was applied to data collected from 779 respondents in Wave 12 (Autumn 2006) of the Scottish Health
Education Population Survey. Respondents were aged 16â74 (average 41.9) yrs.
Results: Initial fit to model expectations was poor. The items 'I've been feeling good about myself', 'I've been interested in new things' and 'I've been feeling cheerful' all showed significant misfit to model expectations, and were deleted. This led to a marginal improvement in fit to the model. After further analysis, more items were deleted and a strict unidimensional seven item scale (the Short Warwick Edinburgh Mental Well-Being Scale (SWEMWBS)) was resolved. Many items deleted because of misfit with
model expectations showed considerable bias for gender. Two retained items also demonstrated bias for gender but, at the
scale level, cancelled out. One further retained item 'I've been feeling optimistic about the future' showed bias for age. The correlation between the 14 item and 7 item versions was 0.954. Given fit to the Rasch model, and strict unidimensionality, SWEMWBS provides an interval scale estimate of mental well-being.
Conclusion: A short 7 item version of WEMWBS was found to satisfy the strict unidimensionality expectations of the Rasch model, and be largely free of bias. This scale, SWEMWBS, provides a raw score-interval scale transformation for use in parametric procedures. In terms of face validity, SWEMWBS presents a more restricted view of mental well-being than the 14 item WEMWBS, with most items representing aspects of psychological and eudemonic well-being, and few covering hedonic well-being or affect. However, robust measurement properties combined with brevity make SWEMWBS preferable to WEMWBS at present for monitoring mental well-being in populations. Where face validity is an issue there remain arguments for continuing to collect data on the full 14 item WEMWBS
International Veterinary Epilepsy Task Force consensus proposal: Medical treatment of canine epilepsy in Europe
In Europe, the number of antiepileptic drugs (AEDs) licensed for dogs has grown considerably over the last years. Nevertheless, the same questions remain, which include, 1) when to start treatment, 2) which drug is best used initially, 3) which adjunctive AED can be advised if treatment with the initial drug is unsatisfactory, and 4) when treatment changes should be considered. In this consensus proposal, an overview is given on the aim of AED treatment, when to start long-term treatment in canine epilepsy and which veterinary AEDs are currently in use for dogs. The consensus proposal for drug treatment protocols, 1) is based on current published evidence-based literature, 2) considers the current legal framework of the cascade regulation for the prescription of veterinary drugs in Europe, and 3) reflects the authorsâ experience. With this paper it is aimed to provide a consensus for the management of canine idiopathic epilepsy. Furthermore, for the management of structural epilepsy AEDs are inevitable in addition to treating the underlying cause, if possible
Bottom mixed layer oxygen dynamics in the Celtic Sea
The seasonally stratified continental shelf seas are highly productive, economically important environments which are under considerable pressure from human activity. Global dissolved oxygen concentrations have shown rapid reductions in response to anthropogenic forcing since at least the middle of the twentieth century. Oxygen consumption is at the same time linked to the cycling of atmospheric carbon, with oxygen being a proxy for carbon remineralisation and the release of CO2. In the seasonally stratified seas the bottom mixed layer (BML) is partially isolated from the atmosphere and is thus controlled by interplay between oxygen consumption processes, vertical and horizontal advection. Oxygen consumption rates can be both spatially and temporally dynamic, but these dynamics are often missed with incubation based techniques. Here we adopt a Bayesian approach to determining total BML oxygen consumption rates from a high resolution oxygen time-series. This incorporates both our knowledge and our uncertainty of the various processes which control the oxygen inventory. Total BML rates integrate both processes in the water column and at the sediment interface. These observations span the stratified period of the Celtic Sea and across both sandy and muddy sediment types. We show how horizontal advection, tidal forcing and vertical mixing together control the bottom mixed layer oxygen concentrations at various times over the stratified period. Our muddy-sand site shows cyclic spring-neap mediated changes in oxygen consumption driven by the frequent resuspension or ventilation of the seabed. We see evidence for prolonged periods of increased vertical mixing which provide the ventilation necessary to support the high rates of consumption observed
CRISPR-Cas9 screens in human cells and primary neurons identify modifiers of C9ORF72 dipeptide-repeat-protein toxicity.
Hexanucleotide-repeat expansions in the C9ORF72 gene are the most common cause of amyotrophic lateral sclerosis and frontotemporal dementia (c9ALS/FTD). The nucleotide-repeat expansions are translated into dipeptide-repeat (DPR) proteins, which are aggregation prone and may contribute to neurodegeneration. We used the CRISPR-Cas9 system to perform genome-wide gene-knockout screens for suppressors and enhancers of C9ORF72 DPR toxicity in human cells. We validated hits by performing secondary CRISPR-Cas9 screens in primary mouse neurons. We uncovered potent modifiers of DPR toxicity whose gene products function in nucleocytoplasmic transport, the endoplasmic reticulum (ER), proteasome, RNA-processing pathways, and chromatin modification. One modifier, TMX2, modulated the ER-stress signature elicited by C9ORF72 DPRs in neurons and improved survival of human induced motor neurons from patients with C9ORF72 ALS. Together, our results demonstrate the promise of CRISPR-Cas9 screens in defining mechanisms of neurodegenerative diseases
Indigenous peoples, the city and inclusive urban development policies in Latin America: Lessons from Bolivia and Ecuador
The historical construction of indigeneity as essentially rural policy category represents a key cause for the ongoing exclusion of urban indigenous peoples and blocks progress in delivering Agenda 2030 in Latin American cities. Even in Bolivia and Ecuador where urban indigeneity is recognised through constitutional reforms there are obstacles to the delivery of policies shaped to urban indigenous interests. By reviewing experiences from these countries, this article highlights that policy delivery problems are a result of multiple factors, including (1) rural constructions of indigeneity, (2) conflicting development priorities, and (3) difficulties in promoting universal rights while simultaneously guaranteeing indigenous rights. The article concludes with policy recommendations for more inclusive urban development approaches which leave no indigenous person behind
Tâcell epitope content comparison (EpiCC) of swine H1 influenza A virus hemagglutinin
Background: Predicting vaccine efficacy against emerging pathogen strains is a significant problem in human and animal vaccine design. Tâcell epitope crossâconservation may play an important role in crossâstrain vaccine efficacy. While influenza A virus (IAV) hemagglutination inhibition (HI) antibody titers are widely used to predict protective efficacy of 1 IAV vaccine against new strains, no similar correlate of protection has been identified for Tâcell epitopes.
Objective: We developed a computational method (EpiCC) that facilitates pairwise comparison of protein sequences based on an immunological propertyâTâcell epitope contentârather than sequence identity, and evaluated its ability to classify swine IAV strain relatedness to estimate crossâprotective potential of a vaccine strain for circulating viruses.
Methods: Tâcell epitope relatedness scores were assessed for 23 IAV HA sequences representing the major H1 swine IAV phyloâclusters circulating in North American swine and HA sequences in a commercial inactivated vaccine (FluSure XPÂź). Scores were compared to experimental data from previous efficacy studies.
Results: Higher EpiCC scores were associated with greater protection by the vaccine against strains for 23 field IAV strain vaccine comparisons. A threshold for EpiCC relatedness associated with full or partial protection in the absence of crossâreactive HI antibodies was identified. EpiCC scores for field strains for which FluSure protective efficacy is not yet available were also calculated.
Conclusion: EpiCC thresholds can be evaluated for predictive accuracy of protection in future efficacy studies. EpiCC may also complement HI crossâreactivity and phylogeny for selection of influenza strains in vaccine development
The crustal domains of the Alboran Basin (Western Mediterranean)
The Alboran Basin in the westernmost Mediterranean hosts the orogenic boundary between the Iberian and African plates. Although numerous geophysical studies of crustal structure onshore Iberia have been carried out during the last decade, the crustal structure of the Alboran Basin has comparatively been poorly studied. We analyze crustalâscale images of a grid of new and reprocessed multichannel seismic profiles showing the tectonic structure and variations in the reflective character of the crust of the basin. The nature of the distinct domains has been groundâtruthed using available basement samples from drilling and dredging. Our results reveal four different crustal types âdomainsâ of the Alboran Basin: a) a thin continental crust underneath the West Alboran and Malaga basins, which transitions to b) a magmatic arc crust in the central part of the Alboran Sea and the East Alboran Basin, c) the NorthâAfrican continental crust containing the Pytheas and Habibas subâbasins, and d) the oceanic crust in the transition towards the AlgeroâBalearic Basin. The Alboran Basin crust is configured in a foreâarc basin (West Alboran and Malaga basins), a magmatic arc (central and East Alboran), and a backâarc system in the easternmost part of the East Alboran Basin and mainly AlgeroâBalearic Basin. The NorthâAfrican continental crust is influenced by arcârelated magmatism along its edge, and was probably affected by strikeâslip tectonics during westward migration of the Miocene subduction system. The distribution of active tectonic structures in the current compressional setting generally corresponds to boundaries between domains, possibly representing inherited lithosphericâscale weak structures
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