6,521 research outputs found
On finite-size effects in computer simulations using the Ewald potential
We discuss the origin and relevance for computer simulations of a strong
finite-size effect that appears when using the Ewald summation formula. It can
be understood as arising from a volume-dependent shift of the potential in a
finite, periodic box relative to the infinite volume limit. This shift is due
to the fact that the ``zero of energy'' for a periodic system cannot be defined
by letting the interacting particles be separated by an infinite distance; the
correct definition corresponds to setting its \bbox k=\bbox 0 Fourier mode to
zero. The implications of this effect for computer simulations are discussed.Comment: Submitted to Journal of Chemical Physic
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
Evaluating the Effects of Nature in the City on 5th grade Studentsâ Environmental Literacy in the Syracuse City School District
Baltimore Woods Nature Centerâs Nature in the City school programs provides K-6 students in the Syracuse City School District with hands-on learning experiences that connect them with their environment. To improve the quality of Baltimore Woods Nature Centerâs Nature in the City (NITC) program, as well as assess changes in 5th grade studentsâ environmental literacy, assessments were conducted in all participating schools. Assessments were given before and after NITC programs in each 5th grade classroom. Pre- and post-assessments scores were calculated for each student, and these scores were used to compute statistics for individual schools and the overall district. Paired t-tests were run at a 95% level of confidence (α = 0.05). Following data analysis it was found that the overall participating students showed a significant increase from pre- to post-scores (percent change of 46.3%). Ten out the 12 schools in this report showed an individual significant increase. Results from Delaware and Porter suggest there is room for improvement in the program. When asked, âwill you change your habits to save energy in your daily life,â and âdo you your actions impact the environment,â the initial response was positive with \u3e40% answering âyes,â or âI already do.â This positive response increased by a small margin of 1 and 3% from pre- to post-scores. The overall findings of this report show that the Nature in the City program is effective at increasing participantsâ environmental literacy. This positive change in opinions about the environment, and the significant increase of scientific knowledge, will equip students who participated in the NITC program with the tools they will need to make environmentally conscious decisions and act in its favor. This not only benefits the global environment, but also helps Baltimore Woods Nature Center meet their goal of increasing studentsâ knowledge and engaging them in hands-on activities
Experimental pre-assessing entanglement in Gaussian states mixing
We suggest and demonstrate a method to assess entanglement generation schemes
based on mixing of Gaussian states at a beam splitter (BS). Our method is based
on the fidelity criterion and represents a tool to analyze the effect of losses
and noise before the BS in both symmetric and asymmetric channels with and
without thermal effects. More generally, our scheme allows one to pre-assess
entanglement resources and to optimize the design of BS-based schemes for the
generation of continuous variable entanglement.Comment: 10 pages, 15 figure
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
Microwave satellite remote sensing for a sustainable sea
The oceans cover roughly 2/3 of the Earthâs surface and are a fundamental ecosystem regulating climate, weather and representing a huge reservoir of biodiversity and natural resources. The preservation of the oceans is therefore not only relevant on an environmental perspective but also on an economical one. A sustainable approach is requested that cannot be simply achieved by improving technologies but calls for a shared new vision of common goods.Within such a complex and holistic problem, the role of satellite microwave remote sensing to observe marine ecosystem and to assist a sustainable development of human activities must be considered. In such a view the paper is meant. Accordingly, the key microwave sensor technologies are reviewed paying particular emphasis on those applications that can provide effective support to pursue some of the UN Sustainable Development Goals. Three meaningful sectors are showcased:oil and gas, where microwave sensors can provide continuous fine-resolution monitoring of critical infrastructures; renewable energy, where microwave satellite remote sensing allows supporting the management of offshore wind farms during both feasibility and operational stages; plastic pollution, where microwave technologies that exploit signals of opportunity offer large-scale monitoring capability to provide marine litter maps of the oceans
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
From Natural Language to Ontology Population in the Cultural Heritage Domain. A Computational Linguistics-based approach.
Using the Digital Millennium Copyright Act to Limit Potential Copyright Liability Online
Any online service provider ( OSP ), including a website operator, that accepts user postings or includes content from other parties on its website or online service is at risk that it will be held liable if such third-party content infringes the copyright of another party. Liability for copyright infringement is an expensive proposition and can run into the millions of dollars. Thus, an OSP must be vigilant in limiting its potential liability in connection with such third-party content
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