445 research outputs found
Resolvent Analysis: With or Without Eddy Viscosity?
International audienceIn this study, estimations of the spatio-temporal power cross-spectral density based on the resolvent operator are compared to those obtained by direct numerical simulation (DNS) in the turbulent plane channel flow at Re τ = 1007 by analysing separately the contribution of each temporal frequency ω. The comparison is performed for spatial scales characteristic of buffer-layer and large-scale motions. Good agreement between the resolvent-based estimates and the statistics obtained by DNS is found when the resolvent operator is based on a linear model which includes the effect of an eddy-viscosity modelling the effect of turbulent Reynolds stresses. The agreement is further improved when a colored noise matching the measures is used instead of white noise in the forcing modelling. Such a good agreement is not observed when the eddy-viscosity terms are not included in the linear model. In this case, the estimation based on the resolvent is unable to select the right peak frequency and wall-normal location of buffer-layer motions
B Cells in the CNS at Postmortem Are Associated With Worse Outcome and Cell Types in Multiple Sclerosis
BACKGROUND AND OBJECTIVES: To define the clinical and pathologic correlations of compartmentalized perivascular B cells in postmortem progressive multiple sclerosis (MS) brains. METHODS: Brain slices were acquired from 11 people with secondary progressive (SP) MS, 5 people with primary progressive (PP) MS, and 4 controls. Brain slices were immunostained for B lymphocytes (CD20), T lymphocytes (CD3), cytotoxic T lymphocytes (CD8), neuronal neurofilaments (NF200), myelin (SMI94), macrophages/microglia (CD68 and IBA1), astrocytes (glial fibrillary acidic protein [GFAP]), and mitochondria (voltage-dependent anion channel and cytochrome c oxidase subunit 4). Differences in CD20 immunostaining intensity between disease groups and associations between CD20 immunostaining intensity and both clinical variables and other immunostaining intensities were explored with linear mixed regression models and Cox regression models, as appropriate. RESULTS: CD20 immunostaining intensity was higher in PPMS (Coeff = 0.410; 95% confidence interval [CI] = 0.046, 0.774; p = 0.027) and SPMS (Coeff = 0.302; 95% CI = 0.020, 0.585; p = 0.036) compared with controls. CD20 immunostaining intensity was higher in cerebellar, spinal cord, and pyramidal onset (Coeff = 0.274; 95% CI = 0.039, 0.510; p = 0.022) compared with optic neuritis and sensory onset. Higher CD20 immunostaining intensity was associated with younger age at onset (hazard ratio [HR] = 1.033; 95% CI = 1.013, 1.053; p = 0.001), SP conversion (HR = 1.056; 95% CI = 1.022, 1.091; p = 0.001), wheelchair dependence (HR = 1.472; 95% CI = 1.108, 1.954; p = 0.008), and death (HR = 1.684; 95% CI = 1.238, 2.291; p = 0.001). Higher immunostaining intensity for CD20 was associated with higher immunostaining intensity for CD3 (Coeff = 0.114; 95% CI = 0.005, 0.224; p = 0.040), CD8 (Coeff = 0.275; 95% CI = 0.200, 0.350; p < 0.001), CD68 (Coeff = 0.084; 95% CI = 0.023, 0.144; p = 0.006), GFAP (Coeff = 0.002; 95% CI = 0.001, 0.004; p = 0.030), and damaged mitochondria (Coeff = 3.902; 95% CI = 0.891, 6.914; p = 0.011). DISCUSSION: Perivascular B cells were associated with worse clinical outcomes and CNS-compartmentalized inflammation. Our findings further support the concept of targeting compartmentalized B-cell inflammation in progressive MS
Haldane-gap excitations in the low-H_c 1-dimensional quantum antiferromagnet NDMAP
Inelastic neutron scattering on deuterated single-crystal samples is used to
study Haldane-gap excitations in the new S=1 one-dimensional quantum
antiferromagnet NDMAP, that was recently recognized as an ideal model system
for high-field studies. The Haldane gap energies meV,
meV and meV, for excitations polarized along
the a, b, and c crystallographic axes, respectively, are directly measured. The
dispersion perpendicular to the chain axis c is studied, and extremely weak
inter-chain coupling constants meV and meV, along the a and b axes, respectively, are determined. The results
are discussed in the context of future experiments in high magnetic fields.Comment: 5 pages, 4 figures, submitted to Phys. Rev.
The Framingham cardiovascular risk score in multiple sclerosis
Background and purpose: Cardiovascular risk factors can increase the risk of multiple sclerosis (MS) and modify its course. However, such factors possibly interact, determining a global cardiovascular risk. Our aim was to compare the global cardiovascular risk of subjects with and without MS with the simplified 10-year Framingham General Cardiovascular Disease Risk Score (FR) and to evaluate its importance on MS-related outcomes. Methods: Age, gender, smoking status, body mass index, systolic blood pressure, type II diabetes and use of antihypertensive medications were recorded in subjects with and without MS to estimate the FR, an individualized percentage risk score estimating the 10-year likelihood of cardiovascular events. Results: In total, 265 MS subjects were identified with 530 matched controls. A t test showed similar FR in cases and controls (P = 0.212). Secondary progressive MS presented significantly higher FR compared to relapsing-remitting MS (P < 0.001). Linear regression analysis showed a direct relationship between FR and Expanded Disability Status Scale (P < 0.001) and MS Severity Scale (P < 0.001). Conclusion: The FR, evaluating the global cardiovascular health by the interaction amongst different risk factors, relates to MS disability, severity and course
An experimental measurement of the staggered magnetization curve for a Haldane spin chain
Long-range magnetic ordering in R_2 Ba Ni O_5 (R=magnetic rare earth)
quasi-1-dimensional mixed-spin antiferromagnets is described by a simple
mean-field model that is based on the intrinsic staggered magnetization
function of isolated Haldane spin chains for the Ni-subsystem, and single-ion
magnetization functions for the rare earth ions. The model is applied to new
experimental results obtained in powder diffraction experiments on Nd_2 Ba Ni
O_5 and Nd Y Ba Ni O_5, and to previously published diffraction data for Er_2
Ba Ni O_5. From this analysis we extract the bare staggered magnetization curve
for Haldane spin chains in these compounds.Comment: some revisions in text and figures 5 pages, 2 figures, PRL accepted
for publicatio
emission rates in absorptions at rest on Li, Li, Be, C and O
An experimental study of the reaction
on Li, Li, Be, C and O -shell nuclei is
presented. The data were collected by the FINUDA spectrometer operating at the
DANE -factory (LNF-INFN, Italy). Emission rates for the reaction in
the mentioned nuclei are measured and compared with the few existing data. The
spectra of several observables are discussed; indications of Quasi-Free
absorptions by a pair embedded in the nucleus can be obtained from
the study of the missing mass distributions.Comment: Version accepted by PR
- …