64,282 research outputs found
Density, short-range order and the quark-gluon plasma
We study the thermal part of the energy density spatial correlator in the
quark-gluon plasma. We describe its qualitative form at high temperatures. We
then calculate it out to distances approx. 1.5/T in SU(3) gauge theory lattice
simulations for the range of temperatures 0.9<= T/T_c<= 2.2. The
vacuum-subtracted correlator exhibits non-monotonic behavior, and is almost
conformal by 2T_c. Its broad maximum at r approx. 0.6/T suggests a dense medium
with only weak short-range order, similar to a non-relativistic fluid near the
liquid-gas phase transition, where eta/s is minimal.Comment: 4 pages, 4 figure
Statistical structure of convective periods derived from satellite ground based data
The documentation of characteristics of Vertical Atmospheric Soundings (VAS) through the use of statistical structure and correlation functions is presented. A measure of random error is also provided. Rawinsonde data from various periods is analyzed. Structure and correlation functions are used to compare VAS retrievals obtained using a physical algorithm with those from a regression technique. Results from both procedures are evaluated against those from a mesoscale network of rawinsonde stations. The parameters documented include temperature, mixing ratio, geopotential height, thickness, and precipitable water. Calculation are performed at several layers in the lower and upper troposphere
Rapid identification and differentiation of the vaccine strain Rac H from EHV 1 field isolates using a non-radioactive DNA probe
A method for rapid differentiation between the EHV 1 live vaccine strain Rac H and field isolates is described. Total DNA was isolated from virus-infected small scale cell cultures. DNA fragments digested with restriction endonuclease BamHI were separated, transfered and immobilized on filter membranes. A Digoxigenin-labeled probe derived from EHV 1 was used for hybridization. This probe hybridized specifically to sequences of the inverted terminal repeat region which in case of Rac H include a deletion of 0.8 kb. By comparing the different migration patterns after blot hybridization it could be shown that in 65 isolates from cases of abortion the live vaccine strain Rac H was not involve
Observation of the Cosmic Ray Electron- Positron Ratio from 100 Mev to 3 Bev in 1964
Balloon flight data on cosmic ray electron- positron ratio from 100 MeV to 3 Be
Coarse Graining of Nonbonded Inter-particle Potentials Using Automatic Simplex Optimization to Fit Structural Properties
We implemented a coarse-graining procedure to construct mesoscopic models of
complex molecules. The final aim is to obtain better results on properties
depending on slow modes of the molecules. Therefore the number of particles
considered in molecular dynamics simulations is reduced while conserving as
many properties of the original substance as possible. We address the problem
of finding nonbonded interaction parameters which reproduce structural
properties from experiment or atomistic simulations. The approach consists of
optimizing automatically nonbonded parameters using the simplex algorithm to
fit structural properties like the radial distribution function as target
functions. Moreover, any mix of structural and thermodynamic properties can be
included in the target function. Different spherically symmetric inter-particle
potentials are discussed. Besides demonstrating the method for Lennard--Jones
liquids, it is applied to several more complex molecular liquids such as
diphenyl carbonate, tetrahydrofurane, and monomers of poly(isoprene).Comment: 24 pages, 3 tables, 14 figures submitted to the Journal of Chemical
Physics (JCP
Heavy Meson Production in NN Collisions with Polarized Beam and Target -- A new facility for COSY
The study of near--threshold meson production in pp and pd collisions
involving polarized beams and polarized targets offers the rare opportunity to
gain insight into short--range features of the nucleon--nucleon interaction.
The Cooler Synchrotron COSY at FZ--J\"ulich is a unique environment to perform
such studies. Measurements of polarization observables require a cylindrically
symmetrical detector, capable to measure the momenta and the directions of
outgoing charged hadrons. The wide energy range of COSY leads to momenta of
outgoing protons to be detected in a single meson production reaction between
300 and 2500 MeV/c. Scattering angles of protons to be covered extend to about
in the laboratory system. An azimuthal angular coverage of the
device around 98% seems technically achievable. The required magnetic
spectrometer could consist of a superconducting toroid, providing fields around
3 T.Comment: 6 pages, 1 figure, submitted to Czechoslovak Journal of Physic
Extension of the spin-1/2 frustrated square lattice model: the case of layered vanadium phosphates
We study the influence of the spin lattice distortion on the properties of
frustrated magnetic systems and consider the applicability of the spin-1/2
frustrated square lattice model to materials lacking tetragonal symmetry. We
focus on the case of layered vanadium phosphates AA'VO(PO4)2 (AA' = Pb2, SrZn,
BaZn, and BaCd). To provide a proper microscopic description of these
compounds, we use extensive band structure calculations for real materials and
model structures and supplement this analysis with simulations of thermodynamic
properties, thus facilitating a direct comparison with the experimental data.
Due to the reduced symmetry, the realistic spin model of layered vanadium
phosphates AA'VO(PO4)2 includes four inequivalent exchange couplings: J1 and
J1' between nearest-neighbors and J2 and J2' between next-nearest-neighbors.
The estimates of individual exchange couplings suggest different regimes, from
J1'/J1 and J2'/J2 close to 1 in BaCdVO(PO4)2, a nearly regular frustrated
square lattice, to J1'/J1 ~ 0.7 and J2'/J2 ~ 0.4 in SrZnVO(PO4)2, a frustrated
square lattice with sizable distortion. The underlying structural differences
are analyzed, and the key factors causing the distortion of the spin lattice in
layered vanadium compounds are discussed. We propose possible routes for
finding new frustrated square lattice materials among complex vanadium oxides.
Full diagonalization simulations of thermodynamic properties indicate the
similarity of the extended model to the regular one with averaged couplings. In
case of moderate frustration and moderate distortion, valid for all the
AA'VO(PO4)2 compounds reported so far, the distorted spin lattice can be
considered as a regular square lattice with the couplings (J1+J1')/2 between
nearest-neighbors and (J2+J2')/2 between next-nearest-neighbors.Comment: 14 pages, 9 figures, 4 table
Pain management in primary care – current perspectives
According to a 1998 World Health Organization Survey of 26 000 primary care patients on five continents, 22% reported persistent
pain over the past year. Part of the problem lies with some health-care providers who have failed to keep up with the advances
in pain medicine and continue to follow the biomedical approach, which regards a specific pathway as the only source
of pain. In this model, all pain is regarded as a warning signal of tissue injury, and if conservative treatment fails, some surgical
technique will be able to correct the problem.
The modern paradigm of pain management has moved from this biomedical to the broader biopsychosocial approach,
where pain mechanisms now integrate input from sensory, emotional and cognitive systems. South African Family Practice Vol. 49 (7) 2007: pp. 20-2
Simulation of Consensus Model of Deffuant et al on a Barabasi-Albert Network
In the consensus model with bounded confidence, studied by Deffuant et al.
(2000), two randomly selected people who differ not too much in their opinion
both shift their opinions towards each other. Now we restrict this exchange of
information to people connected by a scale-free network. As a result, the
number of different final opinions (when no complete consensus is formed) is
proportional to the number of people.Comment: 7 pages including 3 figs; Int.J.MOd.Phys.C 15, issue 2; programming
error correcte
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