2,210 research outputs found
Statistical Physics of Structural Glasses
This paper gives an introduction and brief overview of some of our recent
work on the equilibrium thermodynamics of glasses. We have focused onto first
principle computations in simple fragile glasses, starting from the two body
interatomic potential. A replica formulation translates this problem into that
of a gas of interacting molecules, each molecule being built of atoms, and
having a gyration radius (related to the cage size) which vanishes at zero
temperature. We use a small cage expansion, valid at low temperatures, which
allows to compute the cage size, the specific heat (which follows the Dulong
and Petit law), and the configurational entropy. The no-replica interpretation
of the computations is also briefly described. The results, particularly those
concerning the Kauzmann tempaerature and the configurational entropy, are
compared to recent numerical simulations.Comment: 21 pages, 6 figures, to appear in the proceedings of the Trieste
workshop on "Unifying Concepts in Glass Physics
Asteroseismology of the Hyades red giant and planet host epsilon Tauri
Asteroseismic analysis of solar-like stars allows us to determine physical
parameters such as stellar mass, with a higher precision compared to most other
methods. Even in a well-studied cluster such as the Hyades, the masses of the
red giant stars are not well known, and previous mass estimates are based on
model calculations (isochrones). The four known red giants in the Hyades are
assumed to be clump (core-helium-burning) stars based on their positions in
colour-magnitude diagrams, however asteroseismology offers an opportunity to
test this assumption. Using asteroseismic techniques combined with other
methods, we aim to derive physical parameters and the evolutionary stage for
the planet hosting star epsilon Tau, which is one of the four red giants
located in the Hyades. We analysed time-series data from both ground and space
to perform the asteroseismic analysis. By combining high signal-to-noise (S/N)
radial-velocity data from the ground-based SONG network with continuous
space-based data from the revised Kepler mission K2, we derive and characterize
27 individual oscillation modes for epsilon Tau, along with global oscillation
parameters such as the large frequency separation and the ratio between the
amplitude of the oscillations measured in radial velocity and intensity as a
function of frequency. The latter has been measured previously for only two
stars, the Sun and Procyon. Combining the seismic analysis with interferometric
and spectroscopic measurements, we derive physical parameters for epsilon Tau,
and discuss its evolutionary status.Comment: 13 pages, 13 figures, 4 tables, accepted for publication in Astronomy
& Astrophysic
A tentative Replica Study of the Glass Transition
We propose a method to study quantitatively the glass transition in a system
of interacting particles. In spite of the absence of any quenched disorder, we
introduce a replicated version of the hypernetted chain equations. The solution
of these equations, for hard or soft spheres, signals a transition to the glass
phase. However the predicted value of the energy and specific heat in the glass
phase are wrong, calling for an improvement of this method.Comment: 9 pages, four postcript figures attache
Earth system modeling with endogenous and dynamic human societies: the copan:CORE open World-Earth modeling framework
Analysis of Earth system dynamics in the Anthropocene requires to explicitly
take into account the increasing magnitude of processes operating in human
societies, their cultures, economies and technosphere and their growing
feedback entanglement with those in the physical, chemical and biological
systems of the planet. However, current state-of-the-art Earth System Models do
not represent dynamic human societies and their feedback interactions with the
biogeophysical Earth system and macroeconomic Integrated Assessment Models
typically do so only with limited scope. This paper (i) proposes design
principles for constructing World-Earth Models (WEM) for Earth system analysis
of the Anthropocene, i.e., models of social (World) - ecological (Earth)
co-evolution on up to planetary scales, and (ii) presents the copan:CORE open
simulation modeling framework for developing, composing and analyzing such WEMs
based on the proposed principles. The framework provides a modular structure to
flexibly construct and study WEMs. These can contain biophysical (e.g. carbon
cycle dynamics), socio-metabolic/economic (e.g. economic growth) and
socio-cultural processes (e.g. voting on climate policies or changing social
norms) and their feedback interactions, and are based on elementary entity
types, e.g., grid cells and social systems. Thereby, copan:CORE enables the
epistemic flexibility needed for contributions towards Earth system analysis of
the Anthropocene given the large diversity of competing theories and
methodologies used for describing socio-metabolic/economic and socio-cultural
processes in the Earth system by various fields and schools of thought. To
illustrate the capabilities of the framework, we present an exemplary and
highly stylized WEM implemented in copan:CORE that illustrates how endogenizing
socio-cultural processes and feedbacks could fundamentally change macroscopic
model outcomes
Process mapping strategies to prevent subcutaneous implantable cardioverter-defibrillator infections
Background:
Infection remains a major complication of cardiac implantable electronic devices and can lead to significant morbidity and mortality. Implantable devices that avoid transvenous leads, such as the subcutaneous implantable cardioverter-defibrillator (S-ICD), can reduce the risk of serious infection-related complications, such as bloodstream infection and infective endocarditis. While the 2017 AHA/ACC/HRS guidelines include recommendations for S-ICD use for patients at high risk of infection, currently, there are no clinical trial data that address best practices for the prevention of S-ICD infections. Therefore, an expert panel was convened to develop a consensus on these topics.
Methods:
An expert process mapping methodology was used to achieve consensus on the appropriate steps to minimize or prevent S-ICD infections. Two face-to-face meetings of high-volume S-ICD implanters and an infectious diseases specialist, with expertise in cardiovascular implantable electronic device infections, were conducted to develop consensus on useful strategies pre-, peri-, and postimplant to reduce S-ICD infection risk.
Results:
Expert panel consensus on recommended steps for patient preparation, S-ICD implantation, and postoperative management was developed to provide guidance in individual patient management.
Conclusion:
Achieving expert panel consensus by process mapping methodology for S-ICD infection prevention was attainable, and the results should be helpful to clinicians in adopting interventions to minimize risks of S-ICD infection
Increased appendicularian zooplankton alter carbon cycling under warmer more acidified ocean conditions
Anthropogenic atmospheric loading of CO2 raises concerns about combined effects of increasing ocean temperature and acidification, on biological processes. In particular, the response of appendicularian zooplankton to climate change may have significant ecosystem implications as they can alter biogeochemical cycling compared to classical copepod dominated food webs. However, the response of appendicularians to multiple climate drivers and effect on carbon cycling are still not well understood. Here, we investigated how gelatinous zooplankton (appendicularians) affect carbon cycling of marine food webs under conditions predicted by future climate scenarios. Appendicularians performed well in warmer conditions and benefited from low pH levels, which in turn altered the direction of carbon flow. Increased appendicularians removed particles from the water column that might otherwise nourish copepods by increasing carbon transport to depth from continuous discarding of filtration houses and fecal pellets. This helps to remove CO2 from the atmosphere, and may also have fisheries implications
Light whole genome sequence for SNP discovery across domestic cat breeds
<p>Abstract</p> <p>Background</p> <p>The domestic cat has offered enormous genomic potential in the veterinary description of over 250 hereditary disease models as well as the occurrence of several deadly feline viruses (feline leukemia virus -- FeLV, feline coronavirus -- FECV, feline immunodeficiency virus - FIV) that are homologues to human scourges (cancer, SARS, and AIDS respectively). However, to realize this bio-medical potential, a high density single nucleotide polymorphism (SNP) map is required in order to accomplish disease and phenotype association discovery.</p> <p>Description</p> <p>To remedy this, we generated 3,178,297 paired fosmid-end Sanger sequence reads from seven cats, and combined these data with the publicly available 2X cat whole genome sequence. All sequence reads were assembled together to form a 3X whole genome assembly allowing the discovery of over three million SNPs. To reduce potential false positive SNPs due to the low coverage assembly, a low upper-limit was placed on sequence coverage and a high lower-limit on the quality of the discrepant bases at a potential variant site. In all domestic cats of different breeds: female Abyssinian, female American shorthair, male Cornish Rex, female European Burmese, female Persian, female Siamese, a male Ragdoll and a female African wildcat were sequenced lightly. We report a total of 964 k common SNPs suitable for a domestic cat SNP genotyping array and an additional 900 k SNPs detected between African wildcat and domestic cats breeds. An empirical sampling of 94 discovered SNPs were tested in the sequenced cats resulting in a SNP validation rate of 99%.</p> <p>Conclusions</p> <p>These data provide a large collection of mapped feline SNPs across the cat genome that will allow for the development of SNP genotyping platforms for mapping feline diseases.</p
Selectivity, efficacy and toxicity studies of UCCB01-144, a dimeric neuroprotective PSD-95 inhibitor
Inhibition of postsynaptic density protein-95 (PSD-95) decouples N-methyl-d-aspartate (NMDA) receptor downstream signaling and results in neuroprotection after focal cerebral ischemia. We have previously developed UCCB01-144, a dimeric PSD-95 inhibitor, which binds PSD-95 with high affinity and is neuroprotective in experimental stroke. Here, we investigate the selectivity, efficacy and toxicity of UCCB01-144 and compare with the monomeric drug candidate Tat-NR2B9c. Fluorescence polarization using purified proteins and pull-downs of mouse brain lysates showed that UCCB01-144 potently binds all four PSD-95-like membrane-associated guanylate kinases (MAGUKs). In addition, UCCB01-144 affected NMDA receptor signaling pathways in ischemic brain tissue. UCCB01-144 reduced infarct size in young and aged male mice at various doses when administered 30 min after permanent middle cerebral artery occlusion, but UCCB01-144 was not effective in young male mice when administered 1 h post-ischemia or in female mice. Furthermore, UCCB01-144 was neuroprotective in a transient stroke model in rats, and in contrast to Tat-NR2B9c, high dose of UCCB01-144 did not lead to significant changes in mean arterial blood pressure or heart rate. Overall, UCCB01-144 is a potent MAGUK inhibitor that reduces neurotoxic PSD-95-mediated signaling and improves neuronal survival following focal brain ischemia in rodents under various conditions and without causing cardiovascular side effects, which encourages further studies towards clinical stroke trials
Population-level impact and herd effects following the introduction of human papillomavirus vaccination programmes: updated systematic review and meta-analysis
Background More than 10 years have elapsed since human papillomavirus (HPV) vaccination was implemented. We did a systematic review and meta-analysis of the population-level impact of vaccinating girls and women against human papillomavirus on HPV infections, anogenital wart diagnoses, and cervical intraepithelial neoplasia grade 2+ (CIN2+)to summarise the most recent evidence about the effectiveness of HPV vaccines in real-world settings and to quantify the impact of multiple age-cohort vaccination.Methods In this updated systematic review and meta-analysis, we used the same search strategy as in our previous paper. We searched MEDLINE and Embase for studies published between Feb 1, 2014, and Oct 11, 2018. Studies were eligible if they compared the frequency (prevalence or incidence) of at least one HPV-related endpoint (genital HPV infections, anogenital wart diagnoses, or histologically confirmed CIN2+) between pre-vaccination and post-vaccination periods among the general population and if they used the same population sources and recruitment methods before and after vaccination. Our primary assessment was the relative risk (RR) comparing the frequency (prevalence or incidence) of HPV-related endpoints between the pre-vaccination and post-vaccination periods. We stratified all analyses by sex, age, and years since introduction of HPV vaccination. We used random-effects models to estimate pooled relative risks.Findings We identified 1702 potentially eligible articles for this systematic review and meta-analysis, and included 65 articles in 14 high-income countries: 23 for HPV infection, 29 for anogenital warts, and 13 for CIN2+.After 5\u20138 years of vaccination, the prevalence of HPV 16 and 18 decreased significantly by 83% (RR 0\ub717, 95% CI 0\ub711\u20130\ub725) among girls aged 13\u201319 years, and decreased significantly by 66% (RR 0\ub734, 95% CI 0\ub723\u20130\ub749) among women aged 20\u201324 years. The prevalence of HPV 31, 33, and 45 decreased significantly by 54% (RR 0\ub746, 95% CI 0\ub733\u20130\ub766) among girls aged 13\u201319 years. Anogenital wart diagnoses decreased significantly by 67% (RR 0\ub733, 95% CI 0\ub724\u20130\ub746) among girls aged 15\u201319 years, decreased significantly by 54% (RR 0\ub746, 95% CI 0.36\u20130.60) among women aged 20\u201324 years, and decreased significantly by 31% (RR 0\ub769, 95% CI 0\ub753\u20130\ub789) among women aged 25\u201329 years. Among boys aged 15\u201319 years anogenital wart diagnoses decreased significantly by 48% (RR 0\ub752, 95% CI 0\ub737\u20130\ub775) and among men aged 20\u201324 years they decreased significantly by 32% (RR 0\ub768, 95% CI 0\ub747\u20130\ub798). After 5\u20139 years of vaccination, CIN2+ decreased significantly by 51% (RR 0\ub749, 95% CI 0\ub742\u20130\ub758) among screened girls aged 15\u201319 years and decreased significantly by 31% (RR 0\ub769, 95% CI 0\ub757\u20130\ub784) among women aged 20\u201324 years.Interpretation This updated systematic review and meta-analysis includes data from 60 million individuals and up to 8 years of post-vaccination follow-up. Our results show compelling evidence of the substantial impact of HPV vaccination programmes on HPV infections and CIN2+ among girls and women, and on anogenital warts diagnoses among girls, women, boys, and men. Additionally, programmes with multi-cohort vaccination and high vaccination coverage had a greater direct impact and herd effects
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