3,316 research outputs found
Quantitative Chevalley-Weil theorem for curves
The classical Chevalley-Weil theorem asserts that for an \'etale covering of
projective varieties over a number field K, the discriminant of the field of
definition of the fiber over a K-rational point is uniformly bounded. We obtain
a fully explicit version of this theorem in dimension 1.Comment: version 4: minor inaccuracies in Lemma 3.4 and Proposition 5.2
correcte
Infrared stability of ABJ-like theories
We consider marginal deformations of the superconformal ABJM/ABJ models which
preserve N=2 supersymmetry. We determine perturbatively the spectrum of fixed
points and study their infrared stability. We find a closed line of fixed
points which is IR stable. The fixed point corresponding to the ABJM/ABJ models
is stable under marginal deformations which respect the original SU(2)xSU(2)
invariance, while deformations which break this group destabilize the theory
which then flows to a less symmetric fixed point. We discuss the addition of
flavor degrees of freedom. We prove that in general a flavor marginal
superpotential does not destabilize the system in the IR. An exception is
represented by a marginal coupling which mixes matter charged under different
gauge sectors. Finally, we consider the case of relevant deformations which
should drive the system to a strongly coupled IR fixed point recently
investigated in arXiv:0909.2036 [hep-th].Comment: 1+11 pages, 4 figures; v2: minor correction
The Conformal Manifold of Chern-Simons Matter Theories
We determine perturbatively the conformal manifold of N=2 Chern-Simons matter
theories with the aim of checking in the three dimensional case the general
prescription based on global symmetry breaking, recently introduced. We discuss
in details few remarkable cases like the N=6 ABJM theory and its less
supersymmetric generalizations with/without flavors. In all cases we find
perfect agreement with the predictions of global symmetry breaking
prescription.Comment: 1+17 pages, 1 figure, references adde
Cross-protection against European swine influenza viruses in the context of infection immunity against the 2009 pandemic H1N1 virus : studies in the pig model of influenza
Pigs are natural hosts for the same influenza virus subtypes as humans and are a valuable model for cross-protection studies with influenza. In this study, we have used the pig model to examine the extent of virological protection between a) the 2009 pandemic H1N1 (pH1N1) virus and three different European H1 swine influenza virus (SIV) lineages, and b) these H1 viruses and a European H3N2 SIV. Pigs were inoculated intranasally with representative strains of each virus lineage with 6- and 17-week intervals between H1 inoculations and between H1 and H3 inoculations, respectively. Virus titers in nasal swabs and/or tissues of the respiratory tract were determined after each inoculation. There was substantial though differing cross-protection between pH1N1 and other H1 viruses, which was directly correlated with the relatedness in the viral hemagglutinin (HA) and neuraminidase (NA) proteins. Cross-protection against H3N2 was almost complete in pigs with immunity against H1N2, but was weak in H1N1/pH1N1-immune pigs. In conclusion, infection with a live, wild type influenza virus may offer substantial cross-lineage protection against viruses of the same HA and/or NA subtype. True heterosubtypic protection, in contrast, appears to be minimal in natural influenza virus hosts. We discuss our findings in the light of the zoonotic and pandemic risks of SIVs
Roaring high and low: composition and possible functions of the Iberian stag's vocal repertoire
We provide a detailed description of the rutting vocalisations of free-ranging male Iberian deer (Cervus elaphus hispanicus, Hilzheimer 1909), a geographically isolated and morphologically differentiated subspecies of red deer Cervus elaphus. We combine spectrographic examinations, spectral analyses and automated classifications to identify different call types, and
compare the composition of the vocal repertoire with that of other red deer subspecies. Iberian stags give bouts of roars (and more rarely, short series of barks) that are typically composed of two different types of calls. Long Common Roars are mostly given at the beginning or at the end of the bout, and are characterised by a high fundamental frequency (F0) resulting in poorly defined formant frequencies but a relatively high amplitude. In contrast, Short Common Roars are typically given in the middle or at the end of the bout, and are characterised by a lower F0 resulting in relatively well defined vocal tract resonances, but low amplitude. While we did not identify entirely Harsh Roars (as described in the Scottish red
deer subspecies (Cervus elaphus scoticus), a small percentage of Long Common Roars contained segments of deterministic chaos. We suggest that the evolution of two clearly distinct types of Common Roars may reflect divergent selection pressures favouring either vocal efficiency in high pitched roars or the communication of body size in low-pitched, high spectral density roars highlighting vocal tract resonances. The clear divergence of the Iberian red deer vocal repertoire from those of other documented European red deer populations reinforces the status of this geographical variant as a distinct subspecies
Determining the neurotransmitter concentration profile at active synapses
Establishing the temporal and concentration profiles of neurotransmitters during synaptic release is an essential step towards understanding the basic properties of inter-neuronal communication in the central nervous system. A variety of ingenious attempts has been made to gain insights into this process, but the general inaccessibility of central synapses, intrinsic limitations of the techniques used, and natural variety of different synaptic environments have hindered a comprehensive description of this fundamental phenomenon. Here, we describe a number of experimental and theoretical findings that has been instrumental for advancing our knowledge of various features of neurotransmitter release, as well as newly developed tools that could overcome some limits of traditional pharmacological approaches and bring new impetus to the description of the complex mechanisms of synaptic transmission
Meta-analysis of genome-wide association studies from the CHARGE consortium identifies common variants associated with carotid intima media thickness and plaque
Carotid intima media thickness (cIMT) and plaque determined by ultrasonography are established measures of subclinical atherosclerosis that each predicts future cardiovascular disease events. We conducted a meta-analysis of genome-wide association data in 31,211 participants of European ancestry from nine large studies in the setting of the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) Consortium. We then sought additional evidence to support our findings among 11,273 individuals using data from seven additional studies. In the combined meta-analysis, we identified three genomic regions associated with common carotid intima media thickness and two different regions associated with the presence of carotid plaque (P < 5 × 10 -8). The associated SNPs mapped in or near genes related to cellular signaling, lipid metabolism and blood pressure homeostasis, and two of the regions were associated with coronary artery disease (P < 0.006) in the Coronary Artery Disease Genome-Wide Replication and Meta-Analysis (CARDIoGRAM) consortium. Our findings may provide new insight into pathways leading to subclinical atherosclerosis and subsequent cardiovascular events
Rapidly rotating second-generation progenitors for the blue hook stars of {\omega} Cen
Horizontal Branch stars belong to an advanced stage in the evolution of the
oldest stellar galactic population, occurring either as field halo stars or
grouped in globular clusters. The discovery of multiple populations in these
clusters, that were previously believed to have single populations gave rise to
the currently accepted theory that the hottest horizontal branch members (the
blue hook stars, which had late helium-core flash ignition, followed by deep
mixing) are the progeny of a helium-rich "second generation" of stars. It is
not known why such a supposedly rare event (a late flash followed by mixing) is
so common that the blue hook of {\omega} Cen contains \sim 30% of horizontal
branch stars 10 , or why the blue hook luminosity range in this massive cluster
cannot be reproduced by models. Here we report that the presence of helium core
masses up to \sim 0.04 solar masses larger than the core mass resulting from
evolution is required to solve the luminosity range problem. We model this by
taking into account the dispersion in rotation rates achieved by the
progenitors, whose premain sequence accretion disc suffered an early disruption
in the dense environment of the cluster's central regions where
second-generation stars form. Rotation may also account for frequent
late-flash-mixing events in massive globular clusters.Comment: 44 pages, 8 figures, 2 tables in Nature, online june 22, 201
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