5,939 research outputs found
Can VMD improve the estimate of the muon g-2 ?
We show that a VMD based theoretical input allows for a significantly
improved accuracy for the hadronic vacuum polarization of the photon which
contributes to the theoretical estimate of the muon g-2. We also show that the
only experimental piece of information in the decay which cannot be
accounted for is the accepted value for {\rm Br}(\tau \ra \pi \pi \nu_\tau),
while the spectum lineshape is in agreement with expectations from
annihilations.Comment: 6 pages, 1 figure Proceedings of the PhiPsi09, Oct. 13-16, 2009,
Beijing, Chin
Social distancing strategies against disease spreading
The recurrent infectious diseases and their increasing impact on the society
has promoted the study of strategies to slow down the epidemic spreading. In
this review we outline the applications of percolation theory to describe
strategies against epidemic spreading on complex networks. We give a general
outlook of the relation between link percolation and the
susceptible-infected-recovered model, and introduce the node void percolation
process to describe the dilution of the network composed by healthy individual,
, the network that sustain the functionality of a society. Then, we survey
two strategies: the quenched disorder strategy where an heterogeneous
distribution of contact intensities is induced in society, and the intermittent
social distancing strategy where health individuals are persuaded to avoid
contact with their neighbors for intermittent periods of time. Using
percolation tools, we show that both strategies may halt the epidemic
spreading. Finally, we discuss the role of the transmissibility, , the
effective probability to transmit a disease, on the performance of the
strategies to slow down the epidemic spreading.Comment: to be published in "Perspectives and Challenges in Statistical
Physics and Complex Systems for the Next Decade", Word Scientific Pres
On the zero set of G-equivariant maps
Let be a finite group acting on vector spaces and and consider a
smooth -equivariant mapping . This paper addresses the question of
the zero set near a zero of with isotropy subgroup . It is known
from results of Bierstone and Field on -transversality theory that the zero
set in a neighborhood of is a stratified set. The purpose of this paper is
to partially determine the structure of the stratified set near using only
information from the representations and . We define an index
for isotropy subgroups of which is the difference of
the dimension of the fixed point subspace of in and . Our main
result states that if contains a subspace -isomorphic to , then for
every maximal isotropy subgroup satisfying , the zero
set of near contains a smooth manifold of zeros with isotropy subgroup
of dimension . We also present a systematic method to study
the zero sets for group representations and which do not satisfy the
conditions of our main theorem. The paper contains many examples and raises
several questions concerning the computation of zero sets of equivariant maps.
These results have application to the bifurcation theory of -reversible
equivariant vector fields
The mtDNA 15497 G/A polymorphism in cytochrome b in severe obese subjects from Southern Italy.
Background and aim: A large number of mitochondrial DNA (mtDNA)
mutations have been implicated in degenerative diseases and aging. The aim of this
study was to evaluate whether the 15497 G/A mtDNA polymorphism (G251S) in the
cytochrome b subunit of respiratory complex III, which has been associated with
obesity-related variables and lipid metabolism in a Japanese population, is
associated with severe obesity also in adult Caucasians from southern Italy.
Methods and results: Unrelated severely obese patients (n Z 317; BMI > 40 kg/m2)
and controls (n Z 217; BMI < 25 kg/m2) from Southern Italy were genotyped by
allelic discrimination TaqMan assay for the 15497 G/A mtDNA polymorphism. In
obese patients fasting serum total cholesterol, triglycerides, HDL-cholesterol and
glucose were measured enzymatically and sitting blood pressure and heart rate
were also collected. Mean levels of total cholesterol, triglycerides and glucose were
below the upper reference limit for healthy subjects. Female obese subjects
showed lower levels of blood pressure and heart rate and higher levels of
HDL cholesterol than male obese patients (P < 0.001). All the control subjects and 315/317 severely obese patients were homozygous for the G allele (wild type),
whereas only 2/317, were females homozygous for the A allele.
Conclusions: The mtDNA 15497 G/A polymorphism in cytochrome b was present in
0.6% obese subjects, two females whose lipid parameters and BMI were similar to
those of the overall group. Therefore, this mutation may appear to contribute in
rare instances to severe obesity but does not explain the majority of cases in our
population. A more extensive genetic haplogroup characterization is required to
identify associations to obesity in Caucasians
Slow epidemic extinction in populations with heterogeneous infection rates
We explore how heterogeneity in the intensity of interactions between people
affects epidemic spreading. For that, we study the
susceptible-infected-susceptible model on a complex network, where a link
connecting individuals and is endowed with an infection rate
proportional to the intensity of their contact
, with a distribution taken from face-to-face experiments
analyzed in Cattuto (PLoS ONE 5, e11596, 2010). We find an extremely
slow decay of the fraction of infected individuals, for a wide range of the
control parameter . Using a distribution of width we identify two
large regions in the space with anomalous behaviors, which are
reminiscent of rare region effects (Griffiths phases) found in models with
quenched disorder. We show that the slow approach to extinction is caused by
isolated small groups of highly interacting individuals, which keep epidemic
alive for very long times. A mean-field approximation and a percolation
approach capture with very good accuracy the absorbing-active transition line
for weak (small ) and strong (large ) disorder, respectively
Effect of degree correlations above the first shell on the percolation transition
The use of degree-degree correlations to model realistic networks which are
characterized by their Pearson's coefficient, has become widespread. However
the effect on how different correlation algorithms produce different results on
processes on top of them, has not yet been discussed. In this letter, using
different correlation algorithms to generate assortative networks, we show that
for very assortative networks the behavior of the main observables in
percolation processes depends on the algorithm used to build the network. The
different alghoritms used here introduce different inner structures that are
missed in Pearson's coefficient. We explain the different behaviors through a
generalization of Pearson's coefficient that allows to study the correlations
at chemical distances l from a root node. We apply our findings to real
networks.Comment: In press EP
The good, the bad and the blend: The strategic role of the âmiddle leadershipâ in work-family/life dynamics during remote working
The ongoing epidemiological crisis has suddenly steered us towards a new futuristic work scenario in which most service sector employees work remotely, which could be a permanent reality for most service sector employees. This paper focuses on the strategic role that leadership could play in the radical change process that is taking place in work environments. Particular attention was paid to the role of âmiddle managersâ who perform an important function as a link between the strategic vision of top management and the workforce. In addition, special attention was paid to gender differences in work-life dynamics, which are particularly relevant in countries with traditional cultural identities. As this is a conceptual contribution, the most recent studies on this specific role of middle managers have been taken into account and embedded in the current scenario. Therefore, the main contribution in terms of originality was that the current review aimed to leverage such a legacy of knowledge and create a system of evidence-based practical implications for effectively supporting change in organizational culture through the identification of the most appropriate middle management leadership models for remote working that could prevent and/or limit any psychosocial risks (e.g., workaholism and technostress) and longer-term outcomes such as sustainable work-life interface
Poor Outcome in a Mitochondrial Neurogastrointestinal Encephalomyopathy Patient with a Novel TYMP Mutation: The Need for Early Diagnosis.
Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a devastating autosomal recessive disorder due to mutations in TYMP, which cause loss of function of thymidine phosphorylase (TP), nucleoside accumulation in plasma and tissues and mitochondrial dysfunction. The clinical picture includes progressive gastrointestinal dysmotility, cachexia, ptosis and ophthalmoparesis, peripheral neuropathy and diffuse leukoencephalopathy, which usually lead to death in early adulthood. Therapeutic options are currently available in clinical practice (allogeneic hematopoietic stem cell transplantation and carrier erythrocyte entrapped TP therapy) and newer, promising therapies are expected in the near future. However, successful treatment is strictly related to early diagnosis. We report on an incomplete MNGIE phenotype in a young man harboring the novel heterozygote c.199 C>T (Q67X) mutation in exon 2, and the previously reported c.866 A>C (E289A) mutation in exon 7 in TYMP. The correct diagnosis was achieved many years after the onset of symptoms and unfortunately, the patient died soon after diagnosis because of multiorgan failure due to severe malnutrition and cachexia before any therapeutic option could be tried. To date, early diagnosis is essential to ensure that patients have the opportunity to be treated. MNGIE should be suspected in all patients who present with both gastrointestinal and nervous system involvement, even if the classical complete phenotype is lacking
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