6,350 research outputs found
Improving the initial guess for the Newton-Raphson protocol in time-dependent simulations
A general linearisation procedure for the consistent tangent of a
small-strain visco-plastic material model is presented in this note. The
procedure is based on multi-variable linearisation around a so-called
'reference state'. In particular, the linerarisation of the time integration
scheme is found to yield an extra term compared to classical expressions, which
only appears because the material response is time-dependent. It has the effect
of yielding a very accurate initial guess for the Newton-Raphson protocol based
on the ongoing viscous flow. It is shown, using a modern variational FFT-based
solver, that the extra term reduces both the CPU time and the number of
Newton-Raphson iterations by around a factor two.Comment: Journal of Computational Physics, 202
14N and 15N coupling constants of the oxidized primary donor P-860 of bacterial photosynthesis obtained by electron spin echo envelope modulation spectroscopy
An electron spin echo modulation frequency analysis of P+-860 is performed in 14N chromatophores of Rhodospirillum rubrum, and in 15N substituted reaction centers from Rhodopseudomonas sphaeroides 2.4.1. For the 14N material two sets of nuclear quadrupole parameters are obtained. From the frequencies found for 15N reaction centers the perpendicular, parallel and isotropic hyperfine previous termcouplingnext term constants of three of the four bacteriochlorophyll nitrogen nuclei are inferred
Targeting DNA Repair, Cell Cycle, and Tumor Microenvironment in B Cell Lymphoma
The DNA double-strand break (DSB) is the most cytotoxic lesion and compromises genome stability. In an attempt to efficiently repair DSBs, cells activate ATM kinase, which orchestrates the DNA damage response (DDR) by activating cell cycle checkpoints and initiating DSB repair pathways. In physiological B cell development, however, programmed DSBs are generated as intermediates for effective immune responses and the maintenance of genomic integrity. Disturbances of these pathways are at the heart of B cell lymphomagenesis. Here, we review the role of DNA repair and cell cycle control on B cell development and lymphomagenesis. In addition, we highlight the intricate relationship between the DDR and the tumor microenvironment (TME). Lastly, we provide a clinical perspective by highlighting treatment possibilities of defective DDR signaling and the TME in mantle cell lymphoma, which serves as a blueprint for B cell lymphomas
Thiazide diuretics and the rate of disease progression in autosomal dominant polycystic kidney disease:an observational study
BACKGROUND: In autosomal dominant polycystic kidney disease (ADPKD), hypertension is prevalent and cardiovascular events are the main cause of death. Thiazide diuretics are often prescribed as second-line antihypertensives, on top of renin-angiotensin-aldosterone system (RAAS) blockade. There is a concern, however, that diuretics may increase vasopressin concentration and RAAS activity, thereby worsening disease progression in ADPKD. We aimed to investigate the validity of these suggestions. METHODS: We analysed an observational cohort of 533 ADPKD patients. Plasma copeptin (surrogate for vasopressin), aldosterone and renin were measured by enzyme-linked immunosorbent assay and radioimmunoassay, respectively. Linear mixed models were used to assess the association of thiazide use with estimated glomerular filtration rate (eGFR) decline and Cox proportional hazards models for the association with the composite kidney endpoint of incident end-stage kidney disease, 40% eGFR decline or death. RESULTS: A total of 23% of participants (n = 125) used thiazide diuretics at baseline. Compared with non-users, thiazide users were older, a larger proportion was male, they had lower eGFRs and similar blood pressure under more antihypertensives. Plasma copeptin was higher, but this difference disappeared after adjustment for age and sex. Both renin and aldosterone were higher in thiazide users. There was no difference between thiazide users and non-users in the rate of eGFR decline {difference -0.35 mL/min/1.73 m2 per year [95% confidence interval (CI) -0.83 to -0.14], P = 0.2} during 3.9 years of follow-up (interquartile range 2.5-4.9). This did not change after adjustment for potential confounders [difference final model: 0.08 mL/min/1.73 m2 per year [95% CI -0.46 to -0.62], P = 0.8). In the crude model, thiazide use was associated with a higher incidence of the composite kidney endpoint [hazard ratio (HR) 1.53 (95% CI 1.05-2.23), P = 0.03]. However, this association lost significance after adjustment for age and sex and remained unassociated after adjustment for additional confounders [final model: HR 0.80 (95% CI 0.50-1.29), P = 0.4]. CONCLUSIONS: These data do not show that thiazide diuretics have a detrimental effect on the rate of disease progression in ADPKD and suggest that these drugs can be prescribed as second-line antihypertensives
Galactic contamination in the QMAP experiment
We quantify the level of foreground contamination in the QMAP Cosmic
Microwave Background (CMB) data with two objectives: (a) measuring the level to
which the QMAP power spectrum measurements need to be corrected for foregrounds
and (b) using this data set to further refine current foreground models. We
cross-correlate the QMAP data with a variety of foreground templates. The 30
GHz Ka-band data is found to be significantly correlated with the Haslam 408
MHz and Reich and Reich 1420 MHz synchrotron maps, but not with the Diffuse
Infrared Background Experiment (DIRBE) 240, 140 and 100 micron maps or the
Wisconsin H-Alpha Mapper (WHAM) survey. The 40 GHz Q-band has no significant
template correlations. We discuss the constraints that this places on
synchrotron, free-free and dust emission. We also reanalyze the
foreground-cleaned Ka-band data and find that the two band power measurements
are lowered by 2.3% and 1.3%, respectively.Comment: 4 ApJL pages, including 4 figs. Color figures and data at
http://www.hep.upenn.edu/~angelica/foreground.html#qmap or from
[email protected]
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