2,082 research outputs found
EP-1640 Comparison of time-benefit ratio between in vivo dosimetry and pre-treatment verification in IMRT breast treatment
Hawking radiation as tunneling and the unified first law of thermodynamics at the apparent horizon in the FRW universe
Relations between the tunneling rate and the unified first law of
thermodynamics at the apparent horizon of the FRW universe are investigated.
The tunneling rate arises as a consequence of the unified first law of
thermodynamics in such a dynamical system. The analysis shows obviously how the
tunneling is intimately connected with the unified first law of thermodynamics
through the principle of conservation of energy.Comment: Latex, 9 pages, no figur
Statistical-Mechanical Measure of Stochastic Spiking Coherence in A Population of Inhibitory Subthreshold Neurons
By varying the noise intensity, we study stochastic spiking coherence (i.e.,
collective coherence between noise-induced neural spikings) in an inhibitory
population of subthreshold neurons (which cannot fire spontaneously without
noise). This stochastic spiking coherence may be well visualized in the raster
plot of neural spikes. For a coherent case, partially-occupied "stripes"
(composed of spikes and indicating collective coherence) are formed in the
raster plot. This partial occupation occurs due to "stochastic spike skipping"
which is well shown in the multi-peaked interspike interval histogram. The main
purpose of our work is to quantitatively measure the degree of stochastic
spiking coherence seen in the raster plot. We introduce a new spike-based
coherence measure by considering the occupation pattern and the pacing
pattern of spikes in the stripes. In particular, the pacing degree between
spikes is determined in a statistical-mechanical way by quantifying the average
contribution of (microscopic) individual spikes to the (macroscopic)
ensemble-averaged global potential. This "statistical-mechanical" measure
is in contrast to the conventional measures such as the "thermodynamic" order
parameter (which concerns the time-averaged fluctuations of the macroscopic
global potential), the "microscopic" correlation-based measure (based on the
cross-correlation between the microscopic individual potentials), and the
measures of precise spike timing (based on the peri-stimulus time histogram).
In terms of , we quantitatively characterize the stochastic spiking
coherence, and find that reflects the degree of collective spiking
coherence seen in the raster plot very well. Hence, the
"statistical-mechanical" spike-based measure may be used usefully to
quantify the degree of stochastic spiking coherence in a statistical-mechanical
way.Comment: 16 pages, 5 figures, to appear in the J. Comput. Neurosc
A Kato type Theorem for the inviscid limit of the Navier-Stokes equations with a moving rigid body
The issue of the inviscid limit for the incompressible Navier-Stokes
equations when a no-slip condition is prescribed on the boundary is a famous
open problem. A result by Tosio Kato says that convergence to the Euler
equations holds true in the energy space if and only if the energy dissipation
rate of the viscous flow in a boundary layer of width proportional to the
viscosity vanishes. Of course, if one considers the motion of a solid body in
an incompressible fluid, with a no-slip condition at the interface, the issue
of the inviscid limit is as least as difficult. However it is not clear if the
additional difficulties linked to the body's dynamic make this issue more
difficult or not. In this paper we consider the motion of a rigid body in an
incompressible fluid occupying the complementary set in the space and we prove
that a Kato type condition implies the convergence of the fluid velocity and of
the body velocity as well, what seems to indicate that an answer in the case of
a fixed boundary could also bring an answer to the case where there is a moving
body in the fluid
Quantitative nanoscale electrostatics of viruses
Electrostatics is one of the fundamental driving forces of the interaction between biomolecules in solution. In particular, the recognition events between viruses and host cells are dominated by both specific and non-specific interactions and the electric charge of viral particles determines the electrostatic force component of the latter. Here we probe the charge of individual viruses in liquid milieu by measuring the electrostatic force between a viral particle and the Atomic Force Microscope tip. The force spectroscopy data of co-adsorbed 29 bacteriophage proheads and mature virions, adenovirus and minute virus of mice capsids is utilized for obtaining the corresponding density of charge for each virus. The systematic differences of the density of charge between the viral particles are consistent with the theoretical predictions obtained from X-ray structural data. Our results show that the density of charge is a distinguishing characteristic of each virus, depending crucially on the nature of the viral capsid and the presence/absence of the genetic material.MINECO of Spain through project FIS2011-29493, FIS2014-59562-R, and the Spanish Interdisciplinary Network on the Biophysics of Viruses (Biofivinet, FIS2011-16090-E). CSM acknowledges funding from BFU2013- 41249-P, and Biofivinet. MGM acknowledges funding from the Spanish Government (BIO2012-37649), Comunidad de Madrid (S-505/MAT-0303), and by an institutional grant from FundaciĂłn Areces to the Centro de BiologĂa MolecularPeer Reviewe
Distorted magnetic orders and electronic structures of tetragonal FeSe from first-principles
We use the state-of-the-arts density-functional-theory method to study
various magnetic orders and their effects on the electronic structures of the
FeSe. Our calculated results show that, for the spins of the single Fe layer,
the striped antiferromagnetic orders with distortion are more favorable in
total energy than the checkerboard antiferromagnetic orders with tetragonal
symmetry, which is consistent with known experimental data, and the inter-layer
magnetic interaction is very weak. We investigate the electronic structures and
magnetic property of the distorted phases. We also present our calculated spin
coupling constants and discuss the reduction of the Fe magnetic moment by
quantum many-body effects. These results are useful to understand the
structural, magnetic, and electronic properties of FeSe, and may have some
helpful implications to other FeAs-based materials
The active living gender's gap challenge: 2013-2017 Eurobarometers physical inactivity data show constant higher prevalence in women with no progress towards global reduction goals
BACKGROUND: The World Health Organization (WHO) considers physical inactivity (PIA) as a critical noncommunicable factor for disease and mortality, affecting more women than men. In 2013, the WHO set a 10% reduction of the PIA prevalence, with the goal to be reached by 2025. Changes in the 2013-2017 period of physical inactivity prevalence in the 28 European Union (EU) countries were evaluated to track the progress in achieving WHO 2025 target. METHODS: In 2013 and 2017 EU Special Eurobarometers, the physical activity levels reported by the International Physical Activity Questionnaire of 53,607 adults were analyzed. Data were considered as a whole sample and country-by-country. A χ2 test was used to analyze the physical inactivity prevalence (%) between countries, analyzing women and men together and separately. Additionally, PIA prevalence was analyzed between years (2013-2017) for the overall EU sample and within-country using a Z-Score for two population proportions. RESULTS: The PIA prevalence increased between 2013 and 2017 for the overall EU sample (p <  0.001), and for women (p = 0.04) and men (p < 0.001) separately. Data showed a higher PIA prevalence in women versus men during both years (p <  0.001). When separately considering changes in PIA by gender, only Belgium's women and Luxembourg's men showed a reduction in PIA prevalence. Increases in PIA prevalence over time were observed in women from Austria, Croatia, Germany, Lithuania, Malta, Portugal, Romania, and Slovakia and in men from Bulgaria, Croatia, Czechia, Germany, Italy, Lithuania, Portugal, Romania, Slovakia, and Spain. CONCLUSIONS: PIA prevalence showed an overall increase across the EU and for both women and men between 2013 and 2017, with higher rates of PIA reported for women versus men during both years. PIA prevalence was reduced in only Belgium's women and Luxembourg's men. Our data indicate a limited gender-sensible approach while tacking PIA prevalence with no progress reaching global voluntary reductions of PIA for 2025
Super-diffusive Transport Processes in Porous Media
The basic assumption of models for the transport of contaminants through soil is that the movements of solute particles are characterized by the Brownian motion. However, the complexity of pore space in natural porous media makes the hypothesis of Brownian motion far too restrictive in some situations. Therefore, alternative models have been proposed. One of the models, many times encountered in hydrology, is based in fractional differential equations, which is a one-dimensional fractional advection diffusion equation where the usual second-order derivative gives place to a fractional derivative of order α, with 1 < α ≤ 2. When a fractional derivative replaces the second-order derivative in a diffusion or dispersion model, it leads to anomalous diffusion, also called super-diffusion. We derive analytical solutions for the fractional advection diffusion equation with different initial and boundary conditions. Additionally, we analyze how the fractional parameter α affects the behavior of the solutions
Next-generation mitogenomics: A comparison of approaches applied to caecilian amphibian phylogeny
Mitochondrial genome (mitogenome) sequences are being generated with increasing speed due to the advances of next-generation sequencing (NGS) technology and associated analytical tools. However, detailed comparisons to explore the utility of alternative NGS approaches applied to the same taxa have not been undertaken. We compared a 'traditional' Sanger sequencing method with two NGS approaches (shotgun sequencing and non-indexed, multiplex amplicon sequencing) on four different sequencing platforms (Illumina's HiSeq and MiSeq, Roche's 454 GS FLX, and Life Technologies' Ion Torrent) to produce seven (near-) complete mitogenomes from six species that form a small radiation of caecilian amphibians from the Seychelles. The fastest, most accurate method of obtaining mitogenome sequences that we tested was direct sequencing of genomic DNA (shotgun sequencing) using the MiSeq platform. Bayesian inference and maximum likelihood analyses using seven different partitioning strategies were unable to resolve compellingly all phylogenetic relationships among the Seychelles caecilian species, indicating the need for additional data in this case
Marker-assisted introgression of the salinity tolerance locus Saltol in temperate japonica rice
Background Rice is one of the most salt sensitive crops at seedling, early vegetative and reproductive stages. Varieties
with salinity tolerance at seedling stage promote an efficient growth at early stages in salt affected soils, leading
to healthy vegetative growth that protects crop yield. Saltol major QTL confers capacity to young rice plants growing
under salt condition by maintaining a low Na+/
K+ molar ratio in the shoots.
Results Marker-assisted backcross (MABC) procedure was adopted to transfer Saltol locus conferring salt tolerance
at seedling stage from donor indica IR64-Saltol to two temperate japonica varieties, Vialone Nano and Onice. Forward
and background selections were accomplished using polymorphic KASP markers and a final evaluation of genetic
background recovery of the selected lines was conducted using 15,580 SNP markers obtained from Genotyping by
Sequencing. Three MABC generations followed by two selfing, allowed the identification of introgression lines achieving
a recovery of the recurrent parent (RP) genome up to 100% (based on KASP markers) or 98.97% (based on GBS).
Lines with highest RP genome recovery (RPGR) were evaluated for agronomical-phenological traits in field under nonsalinized
conditions. VN1, VN4, O1 lines were selected considering the agronomic evaluations and the RPGR% results
as the most interesting for commercial exploitation. A physiological characterization was conducted by evaluating
salt tolerance under hydroponic conditions. The selected lines showed lower standard evaluation system (SES) scores:
62% of VN4, and 57% of O1 plants reaching SES 3 or SES 5 respectively, while only 40% of Vialone Nano and 25% of
Onice plants recorded scores from 3 to 5, respectively. VN1, VN4 and O1 showed a reduced electrolyte leakage values,
and limited negative effects on relative water content and shoot/root fresh weight ratio.
Conclusion The Saltol locus was successfully transferred to two elite varieties by MABC in a time frame of three years.
The application of background selection until BC3F3
allowed the selection of lines with a RPGR up to 98.97%. Physiological
evaluations for the selected lines indicate an improved salinity tolerance at seedling stage. The results supported
the effectiveness of the Saltol locus in temperate japonica and of the MABC procedure for recovering of the RP
favorable traits
- …