10,846 research outputs found
Low-Energy Properties of a One-dimensional System of Interacting bosons with Boundaries
The ground state properties and low-lying excitations of a (quasi)
one-dimensional system of longitudinally confined interacting bosons are
studied. This is achieved by extending Haldane's harmonic-fluid description to
open boundary conditions. The boson density, one-particle density matrix, and
momentum distribution are obtained accounting for finite-size and boundary
effects. Friedel oscillations are found in the density. Finite-size scaling of
the momentum distribution at zero momentum is proposed as a method to obtain
from the experiment the exponent that governs phase correlations. The strong
correlations between bosons induced by reduced dimensionality and interactions
are displayed by a Bijl-Jastrow wave function for the ground state, which is
also derived.Comment: Final published version. Minor changes with respect to the previous
versio
Spinodal nanodecomposition in magnetically doped semiconductors
This review presents the recent progress in computational materials design,
experimental realization, and control methods of spinodal nanodecomposition
under three- and two-dimensional crystal-growth conditions in spintronic
materials, such as magnetically doped semiconductors. The computational
description of nanodecomposition, performed by combining first-principles
calculations with kinetic Monte Carlo simulations, is discussed together with
extensive electron microscopy, synchrotron radiation, scanning probe, and ion
beam methods that have been employed to visualize binodal and spinodal
nanodecomposition (chemical phase separation) as well as nanoprecipitation
(crystallographic phase separation) in a range of semiconductor compounds with
a concentration of transition metal (TM) impurities beyond the solubility
limit. The role of growth conditions, co-doping by shallow impurities, kinetic
barriers, and surface reactions in controlling the aggregation of magnetic
cations is highlighted. According to theoretical simulations and experimental
results the TM-rich regions appear either in the form of nanodots (the {\em
dairiseki} phase) or nanocolumns (the {\em konbu} phase) buried in the host
semiconductor. Particular attention is paid to Mn-doped group III arsenides and
antimonides, TM-doped group III nitrides, Mn- and Fe-doped Ge, and Cr-doped
group II chalcogenides, in which ferromagnetic features persisting up to above
room temperature correlate with the presence of nanodecomposition and account
for the application-relevant magneto-optical and magnetotransport properties of
these compounds. Finally, it is pointed out that spinodal nanodecomposition can
be viewed as a new class of bottom-up approach to nanofabrication.Comment: 72 pages, 79 figure
Gamow-Teller strength distributions for double-beta-decaying nuclei within continuum-QRPA
A version of the pn-continuum-QRPA is outlined and applied to describe the
Gamow-Teller strength distributions for -decaying open-shell
nuclei. The calculation results obtained for the pairs of nuclei Cd-Sn
and Te-Xe are compared with available experimental data.Comment: 8 pages, 3 figures, To appear in the proceedings of "Nucleus-2007:
Fundamental problems of nuclear physics, atomic power engineering and nuclear
technologies" Voronezh, Russia, June 25-29, 200
Material microstructure effects in micro-endmilling of Cu99.9E
This article presents an investigation of the machining response of metallurgically and mechanically modified materials at the micro-scale. Tests were conducted that involved micro-milling slots in coarse-grained Cu99.9E with an average grain size of 30 µm and ultrafine-grained Cu99.9E with an average grain size of 200 nm, produced by equal channel angular pressing. A new method based on atomic force microscope measurements is proposed for assessing the effects of material homogeneity changes on the minimum chip thickness required for a robust micro-cutting process with a minimum surface roughness. The investigation has shown that by refining the material microstructure the minimum chip thickness can be reduced and a high surface finish can be obtained. Also, it was concluded that material homogeneity improvements lead to a reduction in surface roughness and surface defects in micro-cutting
A Multi-Objective Optimization for Supply Chain Network Using the Bees Algorithm
A supply chain is a complex network which involves the products, services and information flows between suppliers and customers. A typical supply chain is composed of different levels, hence, there is a need to optimize the supply chain by finding the optimum configuration of the network in order to get a good compromise between the multi-objectives such as cost minimization and lead-time minimization. There are several multi-objective optimization methods which have been applied to find the optimum solutions set based on the Pareto front line. In this study, a swarm-based optimization method, namely, the bees algorithm is proposed in dealing with the multi-objective supply chain model to find the optimum configuration of a given supply chain problem which minimizes the total cost and the total lead-time. The supply chain problem utilized in this study is taken from literature and several experiments have been conducted in order to show the performance of the proposed model; in addition, the results have been compared to those achieved by the ant colony optimization method. The results show that the proposed bees algorithm is able to achieve better Pareto solutions for the supply chain problem
The Distribution of Dengue Virus Serotype in Quang Nam Province (Vietnam) during the Outbreak in 2018
Objectives: Quang Nam province in the Centre of Vietnam has faced an outbreak of dengue hemorrhagic fever (DHF) in 2018. Although DHF is a recurrent disease in this area, no epidemiological and microbiological reports on dengue virus serotypes have been conducted mainly due to lack of facilities for such a kind of advanced surveillance. The aim of this study was to detect different dengue virus serotypes in patients’ blood samples. Design and Methods: Suspected cases living in Quang Nam province (Vietnam) and presenting clinical and hematological signs of dengue hemorrhagic fever were included in the study. The screening was performed, and the results were compared by using two methodologies: RT real-time PCR (RT-rPCR) and the Dengue NS1 rapid test. Results: From December 2018 to February 2019, looking both at RT-rPCR [+] and NS1 [+] methodologies, a total of 488 patients were screened and 336 were positive for dengue virus detection (74 children and 262 adults); 273 of these patients (81.3%) underwent viral serotype identification as follows: 12.82% (35/273) D1 serotype, 17.95% (49/273) D2, 0.37% (1/273) D3, 68.50 (187/283) D4, and 0.37% (1/273) D2+D4 serotypes. The RT-rPCR outcomes showed higher sensitivity during the first three days of infection compared to NS1 (92.3% vs. 89.7%). The NS1 increased sensitivity after the first 3 days whilst the RT-rPCR decreased. Conclusions: Advanced surveillance with dengue virus serotypes identification, if performed routinely, may help to predict and prevent further DHF epidemics based on the exposure of the different serotypes during different periods that lead to the intensification of disease severity as a consequence of antibody-dependent enhancement (ADE)
Honesty of a Dynamic Female Aggressive Status Signal: Baseline Testosterone Relates to Bill Color in Female American Goldfinches
Status signals are linked to fighting ability and enable competitors to gain access to resources without risking injury in aggressive combat. The relationship between testosterone (T), a hormone that mediates aggression, and signals of status is well studied in males, but little is known about the relationship between T and female signals of status. Female and male American goldfinches Spinus tristis express a dynamic carotenoid-based orange bill color during the breeding season and previous work has demonstrated that females use orange bill color to communicate competitive ability during intrasexual competition. We test the hypothesis that female bill color reflects baseline T, which would allow receivers to directly assess a competitor\u27s aggressive potential. We found a positive relationship between T and bill coloration in females, indicating that bill color has the ability to signal female competitive status. This finding is consistent with the hypothesis that female bill color is a reliable signal of fighting ability, and indicates that females, like males, may use coloration to signal their hormonally mediated aggressive potential
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