1,916 research outputs found
Black Branes in a Box: Hydrodynamics, Stability, and Criticality
We study the effective hydrodynamics of neutral black branes enclosed in a
finite cylindrical cavity with Dirichlet boundary conditions. We focus on how
the Gregory-Laflamme instability changes as we vary the cavity radius R. Fixing
the metric at the cavity wall increases the rigidity of the black brane by
hindering gradients of the redshift on the wall. In the effective fluid, this
is reflected in the growth of the squared speed of sound. As a consequence,
when the cavity is smaller than a critical radius the black brane becomes
dynamically stable. The correlation with the change in thermodynamic stability
is transparent in our approach. We compute the bulk and shear viscosities of
the black brane and find that they do not run with R. We find mean-field theory
critical exponents near the critical point.Comment: 23 pages, 3 figures. v2: added comments on first-order phase
transitio
Folate catabolites in spot urine as non-invasive biomarkers of folate status during habitual intake and folic acid supplementation.
Folate status, as reflected by red blood cell (RCF) and plasma folates (PF), is related to health and disease risk. Folate degradation products para-aminobenzoylglutamate (pABG) and para-acetamidobenzoylglutamate (apABG) in 24 hour urine have recently been shown to correlate with blood folate.
Since blood sampling and collection of 24 hour urine are cumbersome, we investigated whether the determination of urinary folate catabolites in fasted spot urine is a suitable non-invasive biomarker for folate status in subjects before and during folic acid supplementation.
Immediate effects of oral folic acid bolus intake on urinary folate catabolites were assessed in a short-term pre-study. In the main study we included 53 healthy men. Of these, 29 were selected for a 12 week folic acid supplementation (400 µg). Blood, 24 hour and spot urine were collected at baseline and after 6 and 12 weeks and PF, RCF, urinary apABG and pABG were determined.
Intake of a 400 µg folic acid bolus resulted in immediate increase of urinary catabolites. In the main study pABG and apABG concentrations in spot urine correlated well with their excretion in 24 hour urine. In healthy men consuming habitual diet, pABG showed closer correlation with PF (rs = 0.676) and RCF (rs = 0.649) than apABG (rs = 0.264, ns and 0.543). Supplementation led to significantly increased folate in plasma and red cells as well as elevated urinary folate catabolites, while only pABG correlated significantly with PF (rs = 0.574) after 12 weeks.
Quantification of folate catabolites in fasted spot urine seems suitable as a non-invasive alternative to blood or 24 hour urine analysis for evaluation of folate status in populations consuming habitual diet. In non-steady-state conditions (folic acid supplementation) correlations between folate marker (RCF, PF, urinary catabolites) decrease due to differing kinetics
Autonomic Effects of Controlled Fine Particulate Exposure in Young Healthy Adults: Effect Modification by Ozone
Background: Human controlled-exposure studies have assessed the impact of ambient fine particulate matter on cardiac autonomic function measured by heart rate variability (HRV), but whether these effects are modified by concomitant ozone exposure remains unknown. Objective: In this study we assessed the impact of O and particulate matter exposure on HRV in humans. Methods: In a crossover design, 50 subjects (19–48 years of age) were randomized to 2-hr controlled exposures to filtered air (FA), concentrated ambient particles (CAPs), O, or combined CAPs and ozone (CAPs + O). The primary end point was change in HRV between the start and end of exposure. Secondary analyses included blood pressure (BP) responses, and effect modification by asthmatic status. Results: Achieved mean CAPs and O exposure concentrations were 121.6 ± 48.0 μg/m and 113.9 ± 6.6 ppb, respectively. In a categorical analysis, exposure had no consistent effect on HRV indices. However, the dose–response relationship between CAPs mass concentration and HRV indices seemed to vary depending on the presence of O. This heterogeneity was statistically significant for the low-frequency component of HRV (p = 0.02) and approached significance for the high-frequency component and time-domain measures of HRV. Exposure to CAPs + O increased diastolic BP by 2.0 mmHg (SE, 1.2; p = 0.02). No other statistically significant changes in BP were observed. Asthmatic status did not modify these effects. Conclusion: The potentiation by O of CAPs effects on diastolic BP and possibly HRV is of small magnitude in young adults. Further studies are needed to assess potential effects in more vulnerable populations
[89Zr]Oxinate4 for long-term in vivo cell tracking by positron emission tomography
Purpose 111In (typically as [111In]oxinate3) is a gold standard
radiolabel for cell tracking in humans by scintigraphy. A long
half-life positron-emitting radiolabel to serve the same purpose
using positron emission tomography (PET) has long
been sought. We aimed to develop an 89Zr PET tracer for cell
labelling and compare it with [111In]oxinate3 single photon
emission computed tomography (SPECT).
Methods [89Zr]Oxinate4 was synthesised and its uptake and
efflux were measured in vitro in three cell lines and in human
leukocytes. The in vivo biodistribution of eGFP-5T33 murine
myeloma cells labelled using [89Zr]oxinate4 or [111In]oxinate3
was monitored for up to 14 days. 89Zr retention by living
radiolabelled eGFP-positive cells in vivo was monitored by
FACS sorting of liver, spleen and bone marrow cells followed
by gamma counting.
Results Zr labelling was effective in all cell types with yields
comparable with 111In labelling. Retention of 89Zr in cells
in vitro after 24 h was significantly better (range 71 to
>90 %) than 111In (43–52 %). eGFP-5T33 cells in vivo
showed the same early biodistribution whether labelled with
111In or 89Zr (initial pulmonary accumulation followed by
migration to liver, spleen and bone marrow), but later translocation
of radioactivity to kidneys was much greater for 111In.
In liver, spleen and bone marrow at least 92 % of 89Zr
remained associated with eGFP-positive cells after 7 days
in vivo.
Conclusion [89Zr]Oxinate4 offers a potential solution to the
emerging need for a long half-life PET tracer for cell tracking
in vivo and deserves further evaluation of its effects on survival
and behaviour of different cell types
Towards the glueball spectrum from unquenched lattice QCD
We use a variational technique to study heavy glueballs on gauge
configurations generated with 2+1 flavours of ASQTAD improved staggered
fermions. The variational technique includes glueball scattering states. The
measurements were made using 2150 configurations at 0.092 fm with a pion mass
of 360 MeV. We report masses for 10 glueball states. We discuss the prospects
for unquenched lattice QCD calculations of the oddballs.Comment: 19 pages, 4 tables and 8 figures. One figure added. Now matches the
published versio
Peripheral arterial disease: A high risk – but neglected – disease population
Peripheral arterial disease (PAD) is a common, progressive manifestation of atherothrombotic vascular disease, which should be managed no different to cardiac disease. Indeed, there is growing evidence that PAD patients are a high risk group, although still relatively under-detected and under treated. This is despite the fact that PAD patients are an increased mortality rate comparable to those with pre-existing or established cardiovascular disease [myocardial infarction, stroke]. With a holistic approach to atherothrombotic vascular disease, our management of PAD can only get better
{\eta} and {\eta}' mesons from Nf=2+1+1 twisted mass lattice QCD
We determine mass and mixing angles of eta and eta' states using Nf=2+1+1
Wilson twisted mass lattice QCD. We describe how those flavour singlet states
need to be treated in this lattice formulation. Results are presented for three
values of the lattice spacing, a=0.061 fm, a=0.078 fm and a=0.086 fm, with
light quark masses corresponding to values of the charged pion mass in a range
of 230 to 500 MeV and fixed bare strange and charm quark mass values. We obtain
557(15)(45) MeV for the eta mass (first error statistical, second systematic)
and 44(5) degrees for the mixing angle in the quark flavour basis,
corresponding to -10(5) degrees in the octet-singlet basis.Comment: 28 pages, 9 figures, version to appear in JHEP, extended discussion
of autocorrelation times and comparison to results available in the
literature, added a comment for FS-effects and clarified the description of
our blocking procedur
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