931 research outputs found
Resummation Methods at Finite Temperature: The Tadpole Way
We examine several resummation methods for computing higher order corrections
to the finite temperature effective potential, in the context of a scalar
theory. We show by explicit calculation to four loops that dressing
the propagator, not the vertex, of the one-loop tadpole correctly counts
``daisy'' and ``super-daisy'' diagrams.Comment: 18 pages, LaTeX, CALT-68-1858, HUTP-93-A011, EFI-93-2
Transverse Enhancement Model and MiniBooNE Charge Current Quasi-Elastic Neutrino Scattering Data
Recently proposed Transverse Enhancement Model of nuclear effects in Charge
Current Quasi-Elastic neutrino scattering [A. Bodek, H. S. Budd, and M. E.
Christy, Eur. Phys. J. C{\bf 71} (2011) 1726] is confronted with the MiniBooNE
high statistics experimental data. It is shown that the {\it effective} large
axial mass model leads to better agreement with the data.Comment: 4 pages, 6 figure
The equation of state for two flavor QCD
We improve the calculation of the equation of state for two flavor QCD by
simulating on lattices at appropriate values of the couplings for the
deconfinement/chiral symmetry restoration crossover. For the
energy density rises rapidly to approximately 1 just after the
crossover( at this point). Comparing with our previous
result for ~\cite{eos}, we find large finite corrections as
expected from free field theory on finite lattices. We also provide formulae
for extracting the speed of sound from the measured quantities.Comment: Contribution to Lattice 95 proceedings (combines talks presented by
T. Blum and L. Karkkainen). LaTeX, 8 pages, uses espcrc2.sty, postscript
figures include
Second harmonic generation and birefringence of some ternary pnictide semiconductors
A first-principles study of the birefringence and the frequency dependent
second harmonic generation (SHG) coefficients of the ternary pnictide
semiconductors with formula ABC (A = Zn, Cd; B = Si, Ge; C = As, P) with
the chalcopyrite structures was carried out. We show that a simple empirical
observation that a smaller value of the gap is correlated with larger value of
SHG is qualitatively true. However, simple inverse power scaling laws between
gaps and SHG were not found. Instead, the real value of the nonlinear response
is a result of a very delicate balance between different intraband and
interband terms.Comment: 13 pages, 12 figure
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The Relationship Between Function and Disease Activity as Measured by the HAQ and DAS28 Varies Over Time and by Rheumatoid Factor Status in Early Inflammatory Arthritis (EIA). Results from the CATCH Cohort§
Objective: To investigate the relationship between function and disease activity in early inflammatory arthritis (EIA). Methods: Canadian Early Arthritis Cohort (CATCH) (n=1143) is a multi-site EIA cohort. Correlations between the Health Assessment Questionnaire Disability Index (HAQ) and DAS28 were done at every 3 months for the first year and then at 18 and 24 months. We also investigated the relationship between HAQ and DAS28 by age (<65 versus â„65) and RF (positive vs negative). Results: Mean HAQ and DAS28 scores were highest at the initial visit with HAQ decreasing over 24 months from a baseline of 0.94 to 0.40 and DAS28 scores decreasing from 4.54 to 2.29. All correlations between HAQ and DAS28 were significant at all time points (p<0.01). The correlations between HAQ and DAS28 were variable over time. The strongest correlation between HAQ and DAS28 occurred at initial visit (most DMARD naive) (n=1,143) and 18 months (r=0.57, n=321) and 24 months (r=0.59, n=214). The baseline correlation between HAQ and DAS28 was significantly different than correlations obtained at 3, 6, and 12 months (p=0.02, 0.01, and 0.01, respectively). Age did not change the association between HAQ and DAS28 {<65 years old (r=0.50, n=868) versus â„65 (r=0.48, n=254), p=0.49}. The correlation between HAQ and DAS28 was stronger with RF+ patients (r=0.63, n=636) vs RF negative (r=0.47, n=477), p=0.0043 Conclusion: Over 2 years in EIA, HAQ and DAS both improved; correlations at time points were different over 2 years and RF status affected the correlations
Semileptonic form factors - a model-independent approach
We demonstrate that the B->D(*) l nu form factors can be accurately predicted
given the slope parameter rho^2 of the Isgur-Wise function. Only weak
assumptions, consistent with lattice results, on the wavefunction for the light
degrees of freedom are required to establish this result. We observe that the
QCD and 1/m_Q corrections can be systematically represented by an effective
Isgur-Wise function of shifted slope. This greatly simplifies the analysis of
semileptonic B decay. We also investigate what the available semileptonic data
can tell us about lattice QCD and Heavy Quark Effective Theory. A rigorous
identity relating the form factor slope difference rho_D^2-rho_A1^2 to a
combination of form factor intercepts is found. The identity provides a means
of checking theoretically evaluated intercepts with experiment.Comment: 18 pages, Revtex, 4 postscript figures, uses epsfig.st
Second Harmonic Generation for a Dilute Suspension of Coated Particles
We derive an expression for the effective second-harmonic coefficient of a
dilute suspension of coated spherical particles. It is assumed that the coating
material, but not the core or the host, has a nonlinear susceptibility for
second-harmonic generation (SHG). The resulting compact expression shows the
various factors affecting the effective SHG coefficient. The effective SHG per
unit volume of nonlinear coating material is found to be greatly enhanced at
certain frequencies, corresponding to the surface plasmon resonance of the
coated particles. Similar expression is also derived for a dilute suspension of
coated discs. For coating materials with third-harmonic (THG) coefficient,
results for the effective THG coefficients are given for the cases of coated
particles and coated discs.Comment: 11 pages, 3 figures; accepted for publication in Phys. Rev.
Dimensional Crossover in the Effective Second Harmonic Generation of Films of Random Dielectrics
The effective nonlinear response of films of random composites consisting of
a binary composite with nonlinear particles randomly embedded in a linear host
is theoretically and numerically studied. A theoretical expression for the
effective second harmonic generation susceptibility, incorporating the
thickness of the film, is obtained by combining a modified effective-medium
approximation with the general expression for the effective second harmonic
generation susceptibility in a composite. The validity of the thoretical
results is tested against results obtained by numerical simulations on random
resistor networks. Numerical results are found to be well described by our
theory. The result implies that the effective-medium approximation provides a
convenient way for the estimation of the nonlinear response in films of random
dielectrics.Comment: 9 pages, 2 figures; accepted for publication in Phys. Rev.
INSIG1 influences obesity-related hypertriglyceridemia in humans
In our analysis of a quantitative trait locus (QTL) for plasma triglyceride (TG) levels [logarithm of odds (LOD) = 3.7] on human chromosome 7q36, we examined 29 single nucleotide polymorphisms (SNPs) across INSIG1, a biological candidate gene in the region. Insulin-induced genes (INSIGs) are feedback mediators of cholesterol and fatty acid synthesis in animals, but their role in human lipid regulation is unclear. In our cohort, the INSIG1 promoter SNP rs2721 was associated with TG levels (P = 2 Ă 10â3 in 1,560 individuals of the original linkage cohort, P = 8 Ă 10â4 in 920 unrelated individuals of the replication cohort, combined P = 9.9 Ă 10â6). Individuals homozygous for the T allele had 9% higher TG levels and 2-fold lower expression of INSIG1 in surgical liver biopsy samples when compared with individuals homozygous for the G allele. Also, the T allele showed additional binding of nuclear proteins from HepG2 liver cells in gel shift assays. Finally, the variant rs7566605 in INSIG2, the only homolog of INSIG1, enhances the effect of rs2721 (P = 0.00117). The variant rs2721 alone explains 5.4% of the observed linkage in our cohort, suggesting that additional, yet-undiscovered genes and sequence variants in the QTL interval also contribute to alterations in TG levels in humans
High-resolution magnetic resonance imaging reveals nuclei of the human amygdala: manual segmentation to automatic atlas
Available online 4 May 2017The amygdala is composed of multiple nuclei with unique functions and connections in the limbic system and to the rest of the brain. However, standard in vivo neuroimaging tools to automatically delineate the amygdala into its multiple nuclei are still rare. By scanning postmortem specimens at high resolution (100â150 ”m) at 7 T field strength (n = 10), we were able to visualize and label nine amygdala nuclei (anterior amygdaloid, cortico-amygdaloid transition area; basal, lateral, accessory basal, central, cortical medial, paralaminar nuclei). We created an atlas from these labels using a recently developed atlas building algorithm based on Bayesian inference. This atlas, which will be released as part of FreeSurfer, can be used to automatically segment nine amygdala nuclei from a standard resolution structural MR image. We applied this atlas to two publicly available datasets (ADNI and ABIDE) with standard resolution T1 data, used individual volumetric data of the amygdala nuclei as the measure and found that our atlas i) discriminates between Alzheimer's disease participants and age-matched control participants with 84% accuracy (AUC=0.915), and ii) discriminates between individuals with autism and age-, sex- and IQ-matched neurotypically developed control participants with 59.5% accuracy (AUC=0.59). For both datasets, the new ex vivo atlas significantly outperformed (all p < .05) estimations of the whole amygdala derived from the segmentation in FreeSurfer 5.1 (ADNI: 75%, ABIDE: 54% accuracy), as well as classification based on whole amygdala volume (using the sum of all amygdala nuclei volumes; ADNI: 81%, ABIDE: 55% accuracy). This new atlas and the segmentation tools that utilize it will provide neuroimaging researchers with the ability to explore the function and connectivity of the human amygdala nuclei with unprecedented detail in healthy adults as well as those with neurodevelopmental and neurodegenerative disorders.This work was supported by the PHS grant DA023427 and NICHD/
NIH grant F32HD079169 (Z.M.S); Feodor Lynen Postdoctoral Fellowship
of the Alexander von Humboldt Foundation (D.K.); R21(MH106796),
R21 (AG046657) and K01AG28521 (J.C.A.), the National Cancer
Institute (1K25CA181632-01) as well as the Genentech Foundation (M.R.); the European Union's Horizon 2020 Marie Sklodowska-Curie
grant agreement No 654911 (project âTHALAMODELâ) and ERC Starting
Grant agreement No 677697 (project âBUNGEE-TOOLSâ); and the
Spanish Ministry of Economy and Competitiveness (MINECO) reference
TEC2014-51882-P (J.E.I.); and the NVIDIA hardware award (M.R. and
J.E.I.). Further support for this research was provided in part by
the National Institute for Biomedical Imaging and Bioengineering
(P41EB015896, R01EB006758, R21EB018907, R01EB019956, R01-
EB013565), the National Institute on Aging (5R01AG008122,
R01AG016495), the National Institute of Diabetes and Digestive and
Kidney Diseases (1-R21-DK-108277-01), the National Institute for
Neurological Disorders and Stroke (R01NS0525851, R21NS072652,
R01NS070963, R01NS083534, 5U01NS086625), the Massachusetts
ADRC (P50AG005134) and was made possible by the resources provided
by Shared Instrumentation Grants 1S10RR023401, 1S10RR019307, and
1S10RR023043. Additional support was provided by the NIH Blueprint
for Neuroscience Research (5U01-MH093765), part of the multi-institutional
Human Connectome Project. In addition, BF has a financial interest
in CorticoMetrics, a company whose medical pursuits focus on brain
imaging and measurement technologies. BF's interests were reviewed and
are managed by Massachusetts General Hospital and Partners HealthCare
in accordance with their conflict of interest policies.
The collection and sharing of the ADNI MRI data used in the
evaluation was funded by the Alzheimer's Disease Neuroimaging
Initiative (ADNI) (National Institutes of Health Grant U01 AG024904)
and DOD ADNI (Department of Defense award number W81XWH-12-2-
0012). ADNI is funded by the National Institute on Aging, the National
Institute of Biomedical Imaging and Bioengineering, and through generous
contributions from the following: Alzheimer's Association;
Alzheimer's Drug Discovery Foundation; BioClinica, Inc.; Biogen Idec
Inc.; Bristol-Myers Squibb Company; Eisai Inc.; Elan Pharmaceuticals,
Inc.; Eli Lilly and Company; F. Hoffmann-La Roche Ltd and its affiliated
company Genentech, Inc.; GE Healthcare; Innogenetics, N.V.; IXICO Ltd.;
Janssen Alzheimer Immunotherapy Research & Development, LLC.;
Johnson & Johnson Pharmaceutical Research & Development LLC.;
Medpace, Inc.; Merck & Co., Inc.; Meso Scale Diagnostics, LLC.;
NeuroRx Research; Novartis Pharmaceuticals Corporation; Pfizer Inc.;
Piramal Imaging; Servier; Synarc Inc.; and Takeda Pharmaceutical
Company. The Canadian Institutes of Health Research is providing funds
to support ADNI clinical sites in Canada. Private sector contributions are
facilitated by the Foundation for the National Institutes of Health (www.
fnih.org). The grantee organization is the Northern California Institute for
Research and Education, and the study is coordinated by the Alzheimer's
Disease Cooperative Study at the University of California, San Diego.
ADNI data are disseminated by the Laboratory for Neuro Imaging at the
University of Southern California
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