304 research outputs found
Ferrohydrodynamics: testing a new magnetization equation
A new magnetization equation recently derived from irreversible
thermodynamics is employed to the calculation of an increase of ferrofluid
viscosity in a magnetic field. Results of the calculations are compared with
those obtained on the basis of two well-known magnetization equations. One of
the two was obtained phenomenologically, another one was derived
microscopically from the Fokker-Planck equation. It is shown that the new
magnetization equation yields a quite satisfactory description of
magnetiviscosity in the entire region of magnetic field strength and the flow
vorticity. This equation turns out to be valid -- like the microscopically
derived equation but unlike the former phenomenological equation -- even far
from equilibrium, and so it should be recommended for further applications.Comment: 4 pages, 3 figures, Submitted to Phys. Rev.
Comment on "Magnetoviscosity and relaxation in ferrofluids"
It is shown and discussed how the conventional system of hydrodynamic
equations for ferrofluids was derived. The set consists of the equation of
fluid motion, the Maxwell equations, and the magnetization equation. The latter
was recently revised by Felderhof [Phys. Rev. E, v.62, p.3848 (2000)]. His
phenomenological magnetization equation looks rather like corresponding
Shliomis' equation, but leads to wrong consequences for the dependence of
ferrofluid viscosity and magnetization relaxation time on magnetic field.Comment: 6 pages, 1 figure, Submitted to Phys. Rev.
Variational Monte Carlo study of the ground state properties and vacancy formation energy of solid para-H2 using a shadow wave function
A Shadow Wave Function (SWF) is employed along with Variational Monte Carlo
techniques to describe the ground state properties of solid molecular
para-hydrogen. The study has been extended to densities below the equilibrium
value, to obtain a parameterization of the SWF useful for the description of
inhomogeneous phases. We also present an estimate of the vacancy formation
energy as a function of the density, and discuss the importance of relaxation
effects near the vacant site
Universality of Sypersymmetric Attractors
The macroscopic entropy-area formula for supersymmetric black holes in
N=2,4,8 theories is found to be universal: in d=4 it is always given by the
square of the largest of the central charges extremized in the moduli space.
The proof of universality is based on the fact that the doubling of unbroken
supersymmetry near the black hole horizon requires that all central charges
other than Z=M vanish at the attractor point for N=4,8. The ADM mass at the
extremum can be computed in terms of duality symmetric quartic invariants which
are moduli independent. The extension of these results for d=5, N=1,2,4 is also
reported. A duality symmetric expression for the energy of the ground state
with spontaneous breaking of supersymmetry is provided by the power 1/2 (2/3)
of the black hole area of the horizon in d=4 (d=5). It is suggested that the
universal duality symmetric formula for the energy of the ground state in
supersymmetric gravity is given by the modulus of the maximal central charge at
the attractor point in any supersymmetric theory in any dimension.Comment: few misprints removed, version to appear in Phys. Rev. 20 pages, 1
figur
Insulin-Like Growth Factor-1 but Not Insulin Predicts Cognitive Decline in Huntington's Disease
BACKGROUND: Huntington\u27s disease (HD) is one of several neurodegenerative disorders that have been associated with metabolic alterations. Changes in Insulin Growth Factor 1 (IGF-1) and/or insulin input to the brain may underlie or contribute to the progress of neurodegenerative processes. Here, we investigated the association over time between changes in plasma levels of IGF-1 and insulin and the cognitive decline in HD patients.
METHODS: We conducted a multicentric cohort study in 156 patients with genetically documented HD aged from 22 to 80 years. Among them, 146 patients were assessed at least twice with a follow-up of 3.5 ± 1.8 years. We assessed their cognitive decline using the Unified Huntington\u27s Disease Rating Scale, and their IGF-1 and insulin plasmatic levels, at baseline and once a year during the follow-up. Associations were evaluated using a mixed-effect linear model.
RESULTS: In the cross-sectional analysis at baseline, higher levels of IGF-1 and insulin were associated with lower cognitive scores and thus with a higher degree of cognitive impairment. In the longitudinal analysis, the decrease of all cognitive scores, except the Stroop interference, was associated with the IGF-1 level over time but not of insulin.
CONCLUSIONS: IGF-1 levels, unlike insulin, predict the decline of cognitive function in HD
Unconventional MBE Strategies from Computer Simulations for Optimized Growth Conditions
We investigate the influence of step edge diffusion (SED) and desorption on
Molecular Beam Epitaxy (MBE) using kinetic Monte-Carlo simulations of the
solid-on-solid (SOS) model. Based on these investigations we propose two
strategies to optimize MBE growth. The strategies are applicable in different
growth regimes: During layer-by-layer growth one can exploit the presence of
desorption in order to achieve smooth surfaces. By additional short high flux
pulses of particles one can increase the growth rate and assist layer-by-layer
growth. If, however, mounds are formed (non-layer-by-layer growth) the SED can
be used to control size and shape of the three-dimensional structures. By
controlled reduction of the flux with time we achieve a fast coarsening
together with smooth step edges.Comment: 19 pages, 7 figures, submitted to Phys. Rev.
Microbial Translocation Is Associated with Extensive Immune Activation in Dengue Virus Infected Patients with Severe Disease
Background:Severe dengue virus (DENV) disease is associated with extensive immune activation, characterized by a cytokine storm. Previously, elevated lipopolysaccharide (LPS) levels in dengue were found to correlate with clinical disease severity. In the present cross-sectional study we identified markers of microbial translocation and immune activation, which are associated with severe manifestations of DENV infection.Methods:Serum samples from DENV-infected patients were collected during the outbreak in 2010 in the State of São Paulo, Brazil. Levels of LPS, lipopolysaccharide binding protein (LBP), soluble CD14 (sCD14) and IgM and IgG endotoxin core antibodies were determined by ELISA. Thirty cytokines were quantified using a multiplex luminex system. Patients were classified according to the 2009 WHO classification and the occurrence of plasma leakage/shock and hemorrhage. Moreover, a (non-supervised) cluster analysis based on the expression of the quantified cytokines was applied to identify groups of patients with similar cytokine profiles. Markers of microbial translocation were linked to groups with similar clinical disease severity and clusters with similar cytokine profiles.Results:Cluster analysis indicated that LPS levels were significantly increased in patients with a profound pro-inflammatory cytokine profile. LBP and sCD14 showed significantly increased levels in patients with severe disease in the clinical classification and in patients with severe inflammation in the cluster analysis. With both the clinical classification and the cluster analysis, levels of IL-6, IL-8, sIL-2R, MCP-1, RANTES, HGF, G-CSF and EGF were associated with severe disease.Conclusions:The present study provides evidence that both microbial translocation and extensive immune activation occur during severe DENV infection and may play an important role in the pathogenesis
Guidelines for clinical pharmacological practices in Huntington's disease
OBJECTIVE: Evidence-based medicine is a difficult goal to achieve in rare diseases where randomized controlled trials are lacking. This report provides guidelines that capitalize on both the literature and expertise of the French National Huntington Disease Reference Centre to optimalize pharmacological therapeutic interventions for Huntington\u27s disease (HD).
MATERIAL AND METHODS: HD experts conducted a systematic analysis of the literature from 1965 to 2013, using a scoring procedure established by the French National Authority for Health. These experts offered their views when evidence was missing to set up provisional guidelines for care in HD. These guidelines were then scored and amended through two subsequent online questionnaires (using SurveyMonkey scoring), and one face-to-face meeting with an external multidisciplinary working group as a step towards validation.
RESULTS: Except for the beneficial effects of tetrabenazine in chorea, none of the published recommendations were grounded on established scientific evidence. Second-generation antipsychotics are nevertheless the first choice for patients with psychiatric manifestations (low level of evidence). All other guidelines are based on low-level evidence and little professional agreement.
CONCLUSION: Patients\u27 care has greatly improved over the last few years despite the lack of high-level evidence standards. Guidelines are based on the expertise of trained specialists from the French National Plan for Rare Diseases. This strategy should now be extended internationally to promote future studies and to harmonize worldwide care of HD
Measurement of the B0-anti-B0-Oscillation Frequency with Inclusive Dilepton Events
The - oscillation frequency has been measured with a sample of
23 million \B\bar B pairs collected with the BABAR detector at the PEP-II
asymmetric B Factory at SLAC. In this sample, we select events in which both B
mesons decay semileptonically and use the charge of the leptons to identify the
flavor of each B meson. A simultaneous fit to the decay time difference
distributions for opposite- and same-sign dilepton events gives ps.Comment: 7 pages, 1 figure, submitted to Physical Review Letter
- …