3,056 research outputs found
Arterial stiffness and Vitamin D levels: the Baltimore Longitudinal Study of Aging
CONTEXT:
The importance of vitamin D for bone health has long been acknowledged. Recent evidence suggests that vitamin D can also play a role in reducing the risk of several other diseases, including cardiovascular disease.
OBJECTIVE:
The aim of this study is to test the hypothesis that 25-hydroxyvitamin D (25-OH D) is an independent cross-sectional correlate of central arterial stiffness in a normative aging study population.
DESIGN AND SETTINGS:
We conducted a cross-sectional analysis.
SUBJECTS:
We studied 1228 healthy volunteers (50% males; age, 70\ub112 yr) of the Baltimore Longitudinal Study of Aging.
MAIN OUTCOME MEASURES:
We measured carotid-femoral pulse wave velocity (PWV) and 25-OH D levels.
RESULTS:
We found a significant inverse association between PWV and 25-OH D levels (adjusted r2=0.27; \u3b2=-0.43; P=0.001). After adjusting for age, gender, ethnicity, season of blood draw, estimated glomerular filtration rate, physical activity level, cardiovascular risk factors score (smoking, visceral obesity, hypercholesterolemia, hypertension, and diabetes), calcium/vitamin D supplementation, serum calcium, and PTH levels, the association between PWV and 25-OH D levels was only slightly reduced and remained statistically significant (adjusted r2=0.34; \u3b2=-0.34; P=0.04).
CONCLUSIONS:
Vitamin D levels are inversely associated with increased arterial stiffness in a normative aging population, irrespective of traditional risk factor burden. Further research is needed to understand the mechanism of this association and to test the hypothesis that vitamin D supplementation can reduce arterial stiffness
Chronic Oedema and the older person: The effects of ageing upon treatment outcomes
Chronic oedema (CO) and lymphoedema (LO) are long-term conditions that can become more complicated or are more likely to develop with age. The ageing process can involve alterations in the structures that support the normal function of the lymphatic system or put it at greater risk of damage. The main three components (skin care, exercise and compression therapy) within the management of CO/LO can become more difficult to apply with age. This is because of reduced healing rates, decreased cardiovascular capacity and deterioration in vascular and arterial structures. The impact of ageing and how this can affect patients and treatment outcomes requires careful consideration
Photoconductivity of biased graphene
Graphene is a promising candidate for optoelectronic applications such as
photodetectors, terahertz imagers, and plasmonic devices. The origin of
photoresponse in graphene junctions has been studied extensively and is
attributed to either thermoelectric or photovoltaic effects. In addition, hot
carrier transport and carrier multiplication are thought to play an important
role. Here we report the intrinsic photoresponse in biased but otherwise
homogeneous graphene. In this classic photoconductivity experiment, the
thermoelectric effects are insignificant. Instead, the photovoltaic and a
photo-induced bolometric effect dominate the photoresponse due to hot
photocarrier generation and subsequent lattice heating through electron-phonon
cooling channels respectively. The measured photocurrent displays polarity
reversal as it alternates between these two mechanisms in a backgate voltage
sweep. Our analysis yields elevated electron and phonon temperatures, with the
former an order higher than the latter, confirming that hot electrons drive the
photovoltaic response of homogeneous graphene near the Dirac point
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Characterization of off-axis fishbones
Repetitive bursting instabilities with strong frequency chirping occur in high-beta, beam-heated plasmas with safety factor q > 1 in the DIII-D tokamak. Although the mode structures differ, in many ways, the off-axis fishbones are similar to the q = 1 fishbones first observed on the Poloidal Divertor Experiment (PDX). The modes are driven by energetic trapped ions at the fast-ion precession frequency. During a burst, the frequency changes most rapidly as the mode reaches its maximum amplitude. Larger amplitude bursts have larger growth rates and frequency chirps. Unlike PDX fishbones, the decay phase is highly variable and is usually shorter than the growth phase. Also, the waveform is highly distorted by higher harmonics during the latter portion of a burst. The radial mode structure alters its shape during the burst. Like PDX fishbones, the modes expel trapped ions in a 'beacon' with a definite phase relationship relative to the mode. Seven types of loss detectors measure the beacon. The losses scale linearly with mode amplitude. The neutron rate changes most rapidly at maximum mode amplitude but, depending on the loss diagnostic, the losses often peak a few cycles later. The non-ambipolar fast-ion losses cause a sudden change in toroidal rotation frequency across the entire plasma. In addition to an overall drop, the neutron signal oscillates in response to the wave. Unlike the beacon of lost particles, which maintains a fixed phase relative to the mode, the phase of the neutron oscillations steadily increases throughout the burst, with the greatest phase slippage occurring in the highly nonlinear phase near maximum mode amplitude. © 2011 IOP Publishing Ltd
Hospital Variability in Use of Anticoagulant Strategies During Acute Myocardial Infarction Treated With an Early Invasive Strategy
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/139118/1/jah31000.pd
Interim Design Report
The International Design Study for the Neutrino Factory (the IDS-NF) was
established by the community at the ninth "International Workshop on Neutrino
Factories, super-beams, and beta- beams" which was held in Okayama in August
2007. The IDS-NF mandate is to deliver the Reference Design Report (RDR) for
the facility on the timescale of 2012/13. In addition, the mandate for the
study [3] requires an Interim Design Report to be delivered midway through the
project as a step on the way to the RDR. This document, the IDR, has two
functions: it marks the point in the IDS-NF at which the emphasis turns to the
engineering studies required to deliver the RDR and it documents baseline
concepts for the accelerator complex, the neutrino detectors, and the
instrumentation systems. The IDS-NF is, in essence, a site-independent study.
Example sites, CERN, FNAL, and RAL, have been identified to allow site-specific
issues to be addressed in the cost analysis that will be presented in the RDR.
The choice of example sites should not be interpreted as implying a preferred
choice of site for the facility
Indication for the disappearance of reactor electron antineutrinos in the Double Chooz experiment
The Double Chooz Experiment presents an indication of reactor electron
antineutrino disappearance consistent with neutrino oscillations. A ratio of
0.944 0.016 (stat) 0.040 (syst) observed to predicted events was
obtained in 101 days of running at the Chooz Nuclear Power Plant in France,
with two 4.25 GW reactors. The results were obtained from a single 10
m fiducial volume detector located 1050 m from the two reactor cores. The
reactor antineutrino flux prediction used the Bugey4 measurement as an anchor
point. The deficit can be interpreted as an indication of a non-zero value of
the still unmeasured neutrino mixing parameter \sang. Analyzing both the rate
of the prompt positrons and their energy spectrum we find \sang = 0.086
0.041 (stat) 0.030 (syst), or, at 90% CL, 0.015 \sang 0.16.Comment: 7 pages, 4 figures, (new version after PRL referee's comments
Altered collecting duct adenylyl cyclase content in collecting duct endothelin-1 knockout mice
<p>Abstract</p> <p>Background</p> <p>Endothelin-1 (ET-1) inhibition of vasopressin (AVP)-stimulated water reabsorption by the inner medullary collecting duct (IMCD) is associated with reduced cAMP accumulation. To determine the effect of ET-1 deficiency, AVP-stimulated cAMP responsiveness was assessed in IMCD from mice with collecting duct-specific deletion of ET-1 (CD ET-1 KO) and from control animals.</p> <p>Methods</p> <p>Cyclic AMP production, adenylyl cyclase (AC) mRNA, and AC protein were measured in acutely isolated IMCD.</p> <p>Results</p> <p>CD ET-1 KO IMCD had enhanced AVP-stimulated cAMP accumulation. Inhibition of calcium-stimulated AC using BAPTA did not prevent enhanced AVP responsiveness in CD ET-1 KO IMCD. Factors known to be modified by ET-1, including nitric oxide, cyclooxygenase metabolites, and superoxide did not affect the increased AVP responsiveness of CD ET-1 KO IMCD. Differential V2 receptor or G-protein activity was not involved since CD ET-1 KO IMCD had increased cAMP accumulation in response to forskolin and/or cholera toxin. CD ET-1 KO did not affect mRNA or protein levels of AC3, one of the major known collecting duct AC isoforms. However, the other known major collecting duct AC isoform (AC5/6) did have increased protein levels in CD ET-1 KO IMCD, although AC5 (weak signal) and 6 mRNA levels were unchanged.</p> <p>Conclusion</p> <p>ET-1 deficiency increases IMCD AC5/6 content, an effect that may synergize with acute ET-1 inhibition of AVP-stimulated cAMP accumulation.</p
Inclusive jet cross section in collisions at TeV
The inclusive jet differential cross section has been measured for jet
transverse energies, , from 15 to 440 GeV, in the pseudorapidity region
0.10.7. The results are based on 19.5 pb of data
collected by the CDF collaboration at the Fermilab Tevatron collider. The data
are compared with QCD predictions for various sets of parton distribution
functions. The cross section for jets with GeV is significantly
higher than current predictions based on O() perturbative QCD
calculations. Various possible explanations for the high- excess are
discussed.Comment: 8 pages with 2 eps uu-encoded figures Submitted to Physical Review
Letter
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