6,567 research outputs found
Three-loop HTLpt thermodynamics at finite temperature and chemical potential
In this proceedings we present a state-of-the-art method of calculating
thermodynamic potential at finite temperature and finite chemical potential,
using Hard Thermal Loop perturbation theory (HTLpt) up to
next-to-next-leading-order (NNLO). The resulting thermodynamic potential
enables us to evaluate different thermodynamic quantities including pressure
and various quark number susceptibilities (QNS). Comparison between our
analytic results for those thermodynamic quantities with the available lattice
data shows a good agreement.Comment: 5 pages, 6 figures, conference proceedings of XXI DAE-BRNS HEP
Symposium, IIT Guwahati, December 2014; to appear in 'Springer Proceedings in
Physics Series
Entanglement entropy in fermionic Laughlin states
We present analytic and numerical calculations on the bipartite entanglement
entropy in fractional quantum Hall states of the fermionic Laughlin sequence.
The partitioning of the system is done both by dividing Landau level orbitals
and by grouping the fermions themselves. For the case of orbital partitioning,
our results can be related to spatial partitioning, enabling us to extract a
topological quantity (the `total quantum dimension') characterizing the
Laughlin states. For particle partitioning we prove a very close upper bound
for the entanglement entropy of a subset of the particles with the rest, and
provide an interpretation in terms of exclusion statistics.Comment: 4+ pages, 3 figures. Minor changes in v
Antibacterial and Cytotoxic Activities of Capparis zeylanica Linn Roots
Se analizaron extractos crudos y un ácido graso, ácido octadec-7-en-5-ynoic (1), de la corteza de la raÃz de Capparis
zeylanica Linn. (familia de las Capparidaceae) para observar sus actividades antibacterianas frente a la bacteria
Gram positiva y Gram negativa. Entre los extractos crudos, el extracto de cloroformo mostró una buena actividad
frente a todos los organismos de prueba. El ácido graso (1) aislado del extracto de cloroformo mostró actividades
antibacterianas frente a todos los organismos de prueba, a excepción de E. coli. Las actividades se compararon con
un antibiótico estándar: la kanamicina. Las concentraciones inhibitorias mÃnimas (CIH) de 1, determinadas mediante
la técnica de dilución en serie, fueron 64 μg/ml frente a Bacillus subtilis y Shigella dysenteriae. Las actividades
citotóxicas del extracto crudo y del ácido graso (1) se observaron mediante el bioensayo de gambas en salmuera y el valor de LC50 del compuesto fue 6,27 μg/mlCrude extracts and a fatty acid, octadec-7-en-5-ynoic acid (1), from the root bark of Capparis zeylanica Linn. (Fam.
Capparidaceae) were screened for their antibacterial activities against Gram positive and Gram negative bacteria.
Among the crude extracts, chloroform extract showed good activity against all test organisms. The fatty acid (1) isolated
from chloroform extract exhibited antibacterial activities against test organisms except E. coli. The activities were
compared to a standard antibiotic- kanamycin. The minimum inhibitory concentrations (MICs) of 1, determined by
serial dilution technique, were found to be 64 μg/ml against Bacillus subtilis and Shigella dysenteriae. The cytotoxic
activities of crude extract and fatty acid (1) were observed by brine shrimp biassay and LC50 value of the compound was found to be 6.27 μg/m
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The impact of fruit flavonoids on memory and cognition
There is intense interest in the studies related to the potential of phytochemical-rich foods to prevent age-related neurodegeneration and cognitive decline. Recent evidence has indicated that a group of plant-derived compounds known as flavonoids may exert particularly powerful actions on mammalian cognition and may reverse age-related declines in memory and learning. In particular, evidence suggests that foods rich in three specific flavonoid sub-groups, the flavanols, anthocyanins and/or flavanones, possess the greatest potential to act on the cognitive processes. This review will highlight the evidence for the actions of such flavonoids, found most commonly in fruits, such as apples, berries and citrus, on cognitive behaviour and the underlying cellular architecture. Although the precise mechanisms by which these flavonoids act within the brain remain unresolved, the present review focuses on their ability to protect vulnerable neurons and enhance the function of existing neuronal structures, two processes known to be influenced by flavonoids and also known to underpin neuro-cognitive function. Most notably, we discuss their selective interactions with protein kinase and lipid kinase signalling cascades (i.e. phosphoinositide-3 kinase/Akt and mitogen-activated protein kinase pathways), which regulate transcription factors and gene expression involved in both synaptic plasticity and cerebrovascular blood flow. Overall, the review attempts to provide an initial insight into the potential impact of regular flavonoid-rich fruit consumption on normal or abnormal deteriorations in cognitive performance
Overlap distributions for quantum quenches in the anisotropic Heisenberg chain
The dynamics after a quantum quench is determined by the weights of the
initial state in the eigenspectrum of the final Hamiltonian, i.e., by the
distribution of overlaps in the energy spectrum. We present an analysis of such
overlap distributions for quenches of the anisotropy parameter in the
one-dimensional anisotropic spin-1/2 Heisenberg model (XXZ chain). We provide
an overview of the form of the overlap distribution for quenches from various
initial anisotropies to various final ones, using numerical exact
diagonalization. We show that if the system is prepared in the
antiferromagnetic N\'eel state (infinite anisotropy) and released into a
non-interacting setup (zero anisotropy, XX point) only a small fraction of the
final eigenstates gives contributions to the post-quench dynamics, and that
these eigenstates have identical overlap magnitudes. We derive expressions for
the overlaps, and present the selection rules that determine the final
eigenstates having nonzero overlap. We use these results to derive concise
expressions for time-dependent quantities (Loschmidt echo, longitudinal and
transverse correlators) after the quench. We use perturbative analyses to
understand the overlap distribution for quenches from infinite to small nonzero
anisotropies, and for quenches from large to zero anisotropy.Comment: 23 pages, 8 figure
Entanglement entropy of a quantum unbinding transition and entropy of DNA
Two significant consequences of quantum fluctuations are entanglement and
criticality. Entangled states may not be critical but a critical state shows
signatures of universality in entanglement. A surprising result found here is
that the entanglement entropy may become arbitrarily large and negative near
the dissociation of a bound pair of quantum particles. Although apparently
counter-intuitive, it is shown to be consistent and essential for the phase
transition, by mapping to a classical problem of DNA melting. We associate the
entanglement entropy to a subextensive part of the entropy of DNA bubbles,
which is responsible for melting. The absence of any extensivity requirement in
time makes this negative entropy an inevitable consequence of quantum mechanics
in continuum. Our results encompass quantum critical points and first-order
transitions in general dimensions.Comment: v2: 6 pages, 3 figures (title modified, more details and figures
added
Conserved Density Fluctuation and Temporal Correlation Function in HTL Perturbation Theory
Considering recently developed Hard Thermal Loop perturbation theory that
takes into account the effect of the variation of the external field through
the fluctuations of a conserved quantity we calculate the temporal component of
the Euclidian correlation function in the vector channel. The results are found
to be in good agreement with the very recent results obtained within the
quenched approximation of QCD and small values of the quark mass ()
on improved lattices of size at (),
(), and (), where is
the temporal extent of the lattice. This suggests that the results from lattice
QCD and Hard Thermal Loop perturbation theory are in close proximity for a
quantity associated with the conserved density fluctuation.Comment: 16 pages, 4 figures; One para added in introduction, Fig 1 modified;
Accepted in Phys. Rev.
Victim Simulator for Victim Detection Radar
Testing of victim detection radars has traditionally used human subjects who volunteer to be buried in, or climb into a space within, a rubble pile. This is not only uncomfortable, but can be hazardous or impractical when typical disaster scenarios are considered, including fire, mud, or liquid waste. Human subjects are also inconsistent from day to day (i.e., they do not have the same radar properties), so quantitative performance testing is difficult. Finally, testing a multiple-victim scenario is difficult and expensive because of the need for multiple human subjects who must all be coordinated. The solution is an anthropomorphic dummy with dielectric properties that replicate those of a human, and that has motions comparable to human motions for breathing and heartbeat. Two airfilled bladders filled and drained by solenoid valves provide the underlying motion for vinyl bags filled with a dielectric gel with realistic properties. The entire assembly is contained within a neoprene wetsuit serving as a "skin." The solenoids are controlled by a microcontroller, which can generate a variety of heart and breathing patterns, as well as being reprogrammable for more complex activities. Previous electromagnetic simulators or RF phantoms have been oriented towards assessing RF safety, e.g., the measurement of specific absorption rate (SAR) from a cell phone signal, or to provide a calibration target for diagnostic techniques (e.g., MRI). They are optimized for precise dielectric performance, and are typically rigid and immovable. This device is movable and "positionable," and has motion that replicates the small-scale motion of humans. It is soft (much as human tissue is) and has programmable motions
Dysfunctional Light-Evoked Regulation of cAMP in Photoreceptors and Abnormal Retinal Adaptation in Mice Lacking Dopamine D4 Receptors
Dopamine is a retinal neuromodulator that has been implicated in many aspects of retinal physiology. Photoreceptor cells express dopamine D4 receptors that regulate cAMP metabolism. To assess the effects of dopamine on photoreceptor physiology, we examined the morphology, electrophysiology, and regulation of cAMP metabolism in mice with targeted disruption of the dopamine D4 receptor gene. Photoreceptor morphology and outer segment disc shedding after light onset were normal in D4 knock-out (D4KO) mice. Quinpirole, a dopamine D2/ D3/D4 receptor agonist, decreased cAMP synthesis in retinas of wild-type (WT) mice but not in retinas of D4KO mice. In WT retinas, the photoreceptors of which were functionally isolated by incubation in the presence of exogenous glutamate, light also suppressed cAMP synthesis. Despite the similar inhibition of cAMP synthesis, the effect of light is directly on the photoreceptors and independent of dopamine modulation, because it was unaffected by application of the D4 receptor antagonist L-745,870. Nevertheless, compared with WT retinas, basal cAMP formation was reduced in the photoreceptors of D4KO retinas, and light had no additional inhibitory effect. The results suggest that dopamine, via D4 receptors, normally modulates the cascade that couples light responses to adenylyl cyclase activity in photoreceptor cells, and the absence of this modulation results in dysfunction of the cascade. Dark-adapted electroretinogram (ERG) responses were normal in D4KO mice. However, ERG b-wave responses were greatly suppressed during both light adaptation and early stages of dark adaptation. Thus, the absence of D4 receptors affects adaptation, altering transmission of light responses from photoreceptors to inner retinal neurons. These findings indicate that dopamine D4 receptors normally play a major role in regulating photoreceptor cAMP metabolism and adaptive retinal responses to changing environmental illumination.Fil: Nir, Izhak. The University of Texas Health Science Center; Estados UnidosFil: Harrison, Joseph M.. The University of Texas Health Science Center; Estados UnidosFil: Haque, Rashidul. Emory University School of Medicine; Estados UnidosFil: Low, Malcolm J.. Oregon Health and Science University; Estados UnidosFil: Grandy, David K.. Oregon Health and Science University; Estados UnidosFil: Rubinstein, Marcelo. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Instituto de Investigaciones en IngenierÃa Genética y BiologÃa Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Iuvone, P. Michael. Emory University School of Medicine; Estados Unido
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