43,705 research outputs found
Different cation-protonation patterns in mol-ecular salts of unsymmetrical dimethyhydrazine : C2H9N2·Br and C2H9N2·H2PO3
Acknowledgements We thank the EPSRC National Crystallography Service (University of Southampton) for the data collections.Peer reviewedPublisher PD
Orbital ordering in LaSrMnO studied by model Hartree-Fock calculation
We have investigated orbital ordering in the half-doped manganite
LaSrMnO, which displays spin, charge and orbital ordering,
by means of unrestricted Hartree-Fock calculations on the multiband -
model. From recent experiment, it has become clear that
LaSrMnO exhibits a cross-type orbital
ordering rather than the widely believed rod-type orbital
ordering. The calculation reveals that cross-type orbital
ordering results from an effect of in-plane distortion as well as from the
relatively long out-of-plane Mn-O distance. For the "Mn" site, it is
shown that the elongation along the c-axis of the MnO octahedra leads to an
anisotropic charge distribution rather than the isotropic one.Comment: 4 pages, 5 figure
An unexpected oxidation : NaK5Cl2(S2O6)2 revisited
Acknowledgements We thank the EPSRC National Crystallography Service (University of Southampton) for the X-ray data collection.Peer reviewedPublisher PD
Thermal storage experience at the MSSTF and plans for the future
The background of thermal storage development at the Midtemperature Solar Systems Test Facility is reviewed. The problems which were encountered are discussed and a course of action for resolving the problems is outlined. Scaling effects of going from laboratory models to full-size applications were determined and applied to thermal storage needs in near-term solar projects
The development of a power spectral density processor for C and L band airborne radar scatterometer sensor systems
A real-time signal processor was developed for the NASA/JSC L-and C-band airborne radar scatterometer sensor systems. The purpose of the effort was to reduce ground data processing costs. Conversion of two quadrature channels of data (like and cross polarized) was made to obtain Power Spectral Density (PSD) values. A chirp-z transform (CZT) approach was used to filter the Doppler return signal and improved high frequency and angular resolution was realized. The processors have been tested with record signals and excellent results were obtained. CZT filtering can be readily applied to scatterometers operating at other wavelengths by altering the sample frequency. The design of the hardware and software and the results of the performance tests are described in detail
Use of the painDETECT tool in rheumatoid arthritis suggests neuropathic and sensitization components in pain reporting.
Rheumatoid arthritis (RA) is an inflammatory autoimmune condition typified by systemic inflammation targeted toward synovial joints. Inhibition of proinflammatory networks by disease-modifying antirheumatic drugs, eg, methotrexate and biologic therapies, including tumor necrosis factor-α inhibitors, often leads to suppression of disease activity observed at the clinical level. However, despite the era of widespread use of disease-modifying treatments, there remain significant groups of patients who continue to experience pain. Our study formulated a pain assessment tool in the arthritis clinic to assess feasibility of measurements including the visual analog scale (VAS) and painDETECT to assess multimodal features of pain in people with established RA (n=100). Clinical measures of disease activity (Disease Activity Score in 28 Joints [DAS28]) were also recorded. Our data showed that despite the majority of subjects on at least one disease-modifying agent, the majority of patients reported severe pain (54%) by VAS, despite well-controlled clinical disease, with mean DAS28 2.07±0.9. Using the painDETECT questionnaire, 67% of patients had unlikely neuropathic pain. A significant proportion of subjects (28%) had possible neuropathic pain and 5% had features of likely neuropathic pain by painDETECT scoring. We found a positive correlation between VAS and painDETECT (R (2)=0.757). Of note, the group who had likely or probable neuropathic pain also showed significantly increased pain reporting by VAS (P30) also had statistically higher proportions of pain reporting (VAS 89.0±0.7 mm) compared with subjects who had a normal body mass index (VAS 45.2±21.8 mm), P<0.05. Our findings suggest that multimodal features of pain perception exist in RA, including neuropathic and sensitization elements, perhaps explaining why a subgroup of people with RA continue to experience ongoing pain, despite their apparent suppression of inflammation
S=1/2 Kagome antiferromagnets CsCu_{12}$ with M=Zr and Hf
Magnetization and specific heat measurements have been carried out on
CsCuZrF and CsCuHfF single crystals, in which
Cu ions with spin-1/2 form a regular Kagom\'{e} lattice. The
antiferromagnetic exchange interaction between neighboring Cu spins is
K and 540 K for CsCuZrF and
CsCuHfF, respectively. Structural phase transitions were
observed at K and 175 K for CsCuZrF and
CsCuHfF, respectively. The specific heat shows a small bend
anomaly indicative of magnetic ordering at K and 24.5 K in
CsCuZrF and CsCuHfF, respectively. Weak
ferromagnetic behavior was observed below . This weak
ferromagnetism should be ascribed to the antisymmetric interaction of the
Dzyaloshinsky-Moriya type that are generally allowed in the Kagom\'{e} lattice.Comment: 6 pages, 4 figure. Conference proceeding of Highly Frustrated
Magnetism 200
Some remarks on one-dimensional force-free Vlasov-Maxwell equilibria
The conditions for the existence of force-free non-relativistic
translationally invariant one-dimensional (1D) Vlasov-Maxwell (VM) equilibria
are investigated using general properties of the 1D VM equilibrium problem. As
has been shown before, the 1D VM equilibrium equations are equivalent to the
motion of a pseudo-particle in a conservative pseudo-potential, with the
pseudo-potential being proportional to one of the diagonal components of the
plasma pressure tensor. The basic equations are here derived in a different way
to previous work. Based on this theoretical framework, a necessary condition on
the pseudo-potential (plasma pressure) to allow for force-free 1D VM equilibria
is formulated. It is shown that linear force-free 1D VM solutions, which so far
are the only force-free 1D VM solutions known, correspond to the case where the
pseudo-potential is an attractive central potential. A general class of
distribution functions leading to central pseudo-potentials is discussed.Comment: Physics of Plasmas, accepte
Absence of Hybridization Gap in Heavy Electron Systems and Analysis of YbAl3 in terms of Nearly Free Electron Conduction Band
In the analysis of the heavy electron systems, theoretical models with c-f
hybridization gap are often used. We point out that such a gap does not exist
and the simple picture with the hybridization gap is misleading in the metallic
systems, and present a correct picture by explicitly constructing an effective
band model of YbAl_3. Hamiltonian consists of a nearly free electron model for
conduction bands which hybridize with localized f-electrons, and includes only
a few parameters. Density of states, Sommerfeld coefficient, f-electron number
and optical conductivity are calculated and compared with the band calculations
and the experiments.Comment: 9 pages, 9 figures, submitted to J. Phys. Soc. Jp
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