708 research outputs found
Food Security in the South Pacific Island Countries with Special Reference to the Fiji Islands
food security, Pacific Island countries, trade, self-reliance
Optical Response of Solid CO as a Tool for the Determination of the High Pressure Phase
We report first-principles calculations of the frequency dependent linear and
second-order optical properties of the two probable extended-solid phases of
CO--V, i.e. and . Compared to the parent
phase the linear optical susceptibility of both phases is much smaller. We find
that and differ substantially in their linear optical
response in the higher energy regime. The nonlinear optical responses of the
two possible crystal structures differ by roughly a factor of five. Since the
differences in the nonlinear optical spectra are pronounced in the low energy
regime, i.e. below the band gap of diamond, measurements with the sample inside
the diamond anvil cell are feasible. We therefore suggest optical experiments
in comparison with our calculated data as a tool for the unambiguous
identification of the high pressure phase of CO.Comment: 4 pages 2 fig
Elastic properties and zone centre frequencies of Cu2O by LCAO method
The elastic properties and the phonon frequencies at the Brillouin zone centre have been investigated for the cubic cuprous oxide. The calculations under the framework of density functional theory have been carried out by deploying the periodic linear combination of atomic orbitals method. After settling the crystal structure the elastic constants have been determined. The absolute values of elastic constants are well in agreement with the experimental reports. The vibrational frequencies at the centre of the Brillouin zone are classified as the Raman and Infrared active modes and compared with the available experimental data. The contribution of vibrational modes to the Gibbs free energy, entropy and heat capacity has also been found
Genetic overlap between diagnostic subtypes of ischemic stroke
Background and Purpose: Despite moderate heritability, the phenotypic heterogeneity of ischemic stroke has hampered gene discovery, motivating analyses of diagnostic subtypes with reduced sample sizes. We assessed evidence for a shared genetic basis among the 3 major subtypes: large artery atherosclerosis (LAA), cardioembolism, and small vessel disease (SVD), to inform potential cross-subtype analyses. Methods: Analyses used genome-wide summary data for 12 389 ischemic stroke cases (including 2167 LAA, 2405 cardioembolism, and 1854 SVD) and 62 004 controls from the Metastroke consortium. For 4561 cases and 7094 controls, individual-level genotype data were also available. Genetic correlations between subtypes were estimated using linear mixed models and polygenic profile scores. Meta-analysis of a combined LAA-SVD phenotype (4021 cases and 51 976 controls) was performed to identify shared risk alleles. Results: High genetic correlation was identified between LAA and SVD using linear mixed models (rg=0.96, SE=0.47, P=9×10-4) and profile scores (rg=0.72; 95% confid
Partonic flow and -meson production in Au+Au collisions at = 200 GeV
We present first measurements of the -meson elliptic flow
() and high statistics distributions for different
centralities from = 200 GeV Au+Au collisions at RHIC. In
minimum bias collisions the of the meson is consistent with the
trend observed for mesons. The ratio of the yields of the to those of
the as a function of transverse momentum is consistent with a model
based on the recombination of thermal quarks up to GeV/,
but disagrees at higher momenta. The nuclear modification factor () of
follows the trend observed in the mesons rather than in
baryons, supporting baryon-meson scaling. Since -mesons are
made via coalescence of seemingly thermalized quarks in central Au+Au
collisions, the observations imply hot and dense matter with partonic
collectivity has been formed at RHIC.Comment: 6 pages, 4 figures, submit to PR
Plasma Wakefield Acceleration with a Modulated Proton Bunch
The plasma wakefield amplitudes which could be achieved via the modulation of
a long proton bunch are investigated. We find that in the limit of long bunches
compared to the plasma wavelength, the strength of the accelerating fields is
directly proportional to the number of particles in the drive bunch and
inversely proportional to the square of the transverse bunch size. The scaling
laws were tested and verified in detailed simulations using parameters of
existing proton accelerators, and large electric fields were achieved, reaching
1 GV/m for LHC bunches. Energy gains for test electrons beyond 6 TeV were found
in this case.Comment: 9 pages, 7 figure
The energy dependence of angular correlations inferred from mean- fluctuation scale dependence in heavy ion collisions at the SPS and RHIC
We present the first study of the energy dependence of angular
correlations inferred from event-wise mean transverse momentum
fluctuations in heavy ion collisions. We compare our large-acceptance
measurements at CM energies $\sqrt{s_{NN}} =$ 19.6, 62.4, 130 and 200 GeV to
SPS measurements at 12.3 and 17.3 GeV. $p_t$ angular correlation structure
suggests that the principal source of $p_t$ correlations and fluctuations is
minijets (minimum-bias parton fragments). We observe a dramatic increase in
correlations and fluctuations from SPS to RHIC energies, increasing linearly
with $\ln \sqrt{s_{NN}}$ from the onset of observable jet-related
fluctuations near 10 GeV.Comment: 10 pages, 4 figure
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