736 research outputs found
Very Low Energy Supernovae: Light Curves and Spectra of Shock Breakout
The brief transient emitted as a shock wave erupts through the surface of a
presupernova star carries information about the stellar radius and explosion
energy. Here the CASTRO code, which treats radiation transport using multigroup
flux-limited diffusion, is used to simulate the light curves and spectra of
shock breakout in very low-energy supernovae (VLE SNe), explosions in giant
stars with final kinetic energy much less than 10 erg. VLE SNe light
curves, computed here with the KEPLER code, are distinctively faint, red, and
long-lived, making them challenging to find with transient surveys. The
accompanying shock breakouts are brighter, though briefer, and potentially
easier to detect. Previous analytic work provides general guidance, but
numerical simulations are challenging due to the range of conditions and lack
of equilibration between color and effective temperatures. We consider previous
analytic work and extend discussions of color temperature and opacity to the
lower energy range explored by these events. Since this is the first
application of the CASTRO code to shock breakout, test simulations of normal
energy shock breakout of SN1987A are carried out and compared with the
literature. A set of breakout light curves and spectra are then calculated for
VLE SNe with final kinetic energies in the range ergs for
red supergiants with main sequence masses 15 Msun and 25 Msun. The importance
of uncertainties in stellar atmosphere model, opacity, and ambient medium is
discussed, as are observational prospects with current and forthcoming
missions.Comment: 19 pages; submitted to Astrophysical Journa
Acute effects of Hibiscus sabdariffa calyces on postprandial blood pressure, vascular function, blood lipids, biomarkers of insulin resistance and inflammation in humans
The acute impact of Hibiscus sabdariffa calyces (HSC) extract on postprandial vascular function and other cardiometabolic risk factors have not been studied previously. This study investigated the acute impact of HSC extract consumption on blood pressure (BP), vascular function and other cardiometabolic risk markers. Twenty-five men with 1% to 10% cardiovascular disease (CVD) risk (determined by QRISK 2) were randomised to consume either 250 mL of the aqueous extract of HSC or water with breakfast in a randomised, controlled, single-blinded, 2-meal cross-over study (ClinicalTrials.gov, NTC02165553) with a two weeks washout period between study days. BP was measured at baseline and hourly for 4 h. Flow mediated dilatation (FMD) of the branchial artery was measured at baseline, 2 and 4 h post intervention drink consumption. Acute consumption of aqueous extract of HSC caused a significant increase in % FMD ( < 0.001), a non-significant decrease in systolic BP (SBP) and diastolic BP (DBP); non-significant increase in urinary and plasma nitric oxide (NOx) and reduced response of serum glucose, plasma insulin, serum triacylglycerol and C-reactive protein (CRP) levels; significant ( = 0.026) improvement in the area under systemic antioxidant response curve (0 to 2 h); no significant changes in arterial stiffness following the acute consumption of the extract of HSC. Gallic acid, 4-O-methylgallic acid, 3-O-methylgallic acid and hippuric acid reached a maximum plasma concentration at 1 to 2 h post consumption of the extract of HSC. The extract of HSC improved postprandial vascular function and may be a useful dietary strategy to reduce endothelial dysfunction and CVD risk, although this requires confirmation
Mechanisms of pelvic floor muscle function and the effect on the urethra during a cough
Background: Current measurement tools have difficulty identifying the automaticphysiologic processes maintaining continence, and many questions still remainabout pelvic floor muscle (PFM) function during automatic events.Objective: To perform a feasibility study to characterise the displacement, velocity,and acceleration of the PFM and the urethra during a cough.Design, setting, and participants: A volunteer convenience sample of 23 continentwomen and 9 women with stress urinary incontinence (SUI) from the generalcommunity of San Francisco Bay Area was studied.Measurements: Methods included perineal ultrasound imaging, motion trackingof the urogenital structures, and digital vaginal examination. Statistical analysisused one-tailed unpaired student t tests, and Welch’s correction was applied whenvariances were unequal.Results and limitations: The cough reflex activated the PFM of continent women tocompress the urogenital structures towards the pubic symphysis, which wasabsent in women with SUI. The maximum accelerations that acted on the PFMduring a cough were generally more similar than the velocities and displacements.The urethras of women with SUI were exposed to uncontrolled transverse accelerationand were displaced more than twice as far ( p = 0.0002), with almost twicethe velocity ( p = 0.0015) of the urethras of continent women. Caution regardingthe generalisability of this study is warranted due to the small number of women inthe SUI group and the significant difference in parity between groups.Conclusions: During a cough, normal PFM function produces timely compressionof the pelvic floor and additional external support to the urethra, reducing displacement,velocity, and acceleration. In women with SUI, who have weakerurethral attachments, this shortening contraction does not occur; consequently,the urethras of women with SUI move further and faster for a longer duratio
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Potential health effects of Champagne wine consumption
Epidemiological studies have suggested an inverse correlation between red wine consumption and the incidence of cardiovascular and neurodegenerative disorders. Although white wines are generally low in polyphenol content as compared to red wines, champagne has been shown to contain relatively high amounts of phenolic acids that may exert protective cellular actions in vivo. In this study, we have investigated the potential cardioprotective and neuroprotective effects of champagne. Our data suggest that a daily moderate consumption of champagne may improve vascular performance via the delivery of phenolic constituents capable of improving NO bioavailability and the
modulation of metalloproteinase. Moreover, champagne intervention significantly increased spatial working memory in aged animals, whilst no improvement was observed in the presence of alcohol. Together, these data indicate that polyphenols present in champagne may induce cardioprotective and neuroprotective effects, delaying the onset of degenerative disorders
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Reformulation initiative for partial replacement of saturated with unsaturated fats in dairy foods attenuates the increase in LDL cholesterol and improves flow-mediated dilatation compared with conventional dairy: the randomized, controlled REplacement of SaturatEd fat in dairy on Total cholesterol (RESET) study
Background
Modifying dairy fat composition by increasing the MUFA content is a potential strategy to reduce dietary SFA intake for cardiovascular disease (CVD) prevention in the population.
Objectives
To determine the effects of consuming SFA-reduced, MUFA-enriched (modified) dairy products, compared with conventional dairy products (control), on the fasting cholesterol profile (primary outcome), endothelial function assessed by flow-mediated dilatation (FMD; key secondary outcome), and other cardiometabolic risk markers.
Methods
A double-blind, randomized, controlled crossover 12-wk intervention was conducted. Participants with a 1.5-fold higher (moderate) CVD risk than the population mean replaced habitual dairy products with study products (milk, cheese, and butter) to achieve a high-fat, high-dairy isoenergetic daily dietary exchange [38% of total energy intake (%TE) from fat: control (dietary target: 19%TE SFA; 11%TE MUFA) and modified (16%TE SFA; 14%TE MUFA) diet].
Results
Fifty-four participants (57.4% men; mean ± SEM age: 52 ± 3 y; BMI: 25.8 ± 0.5 kg/m2) completed the study. The modified diet attenuated the rise in fasting LDL cholesterol observed with the control diet (0.03 ± 0.06 mmol/L and 0.19 ± 0.05 mmol/L, respectively; P = 0.03). Relative to baseline, the %FMD response increased after the modified diet (0.35% ± 0.15%), whereas a decrease was observed after the control diet (−0.51% ± 0.15%; P< 0.0001). In addition, fasting plasma nitrite concentrations increased after the modified diet, yet decreased after the control diet (0.02 ± 0.01 μmol/L and −0.03 ± 0.02 μmol/L, respectively; P = 0.01).
Conclusions
In adults at moderate CVD risk, consumption of a high-fat diet containing SFA-reduced, MUFA-enriched dairy products for 12 wk showed beneficial effects on fasting LDL cholesterol and endothelial function compared with conventional dairy products. Our findings indicate that fatty acid modification of dairy products may have potential as a public health strategy aimed at CVD risk reduction. This trial was registered at clinicaltrials.gov as NCT02089035
Dietary patterns in relation to cardiovascular disease incidence and risk markers in a middle-aged British male population: data from the Caerphilly prospective study
Dietary behaviour is an important modifiable factor in cardiovascular disease (CVD) prevention. The study aimed to identify dietary patterns (DPs) and explore their association with CVD incidence and risk markers. A follow-up of 1838 middle-aged men, aged 47-67 years recruited into the Caerphilly Prospective Cohort Study at phase 2 (1984-1988) was undertaken. Principal component analysis identified three DPs at baseline, which explained 24.8% of the total variance of food intake. DP1, characterised by higher intakes of white bread, butter, lard, chips and sugar-sweetened beverages and lower intake of wholegrain bread, was associated with higher CVD (HR 1.35: 95% CI: 1.10, 1.67) and stroke (HR 1.77; 95% CI: 1.18, 2.63) incidence. DP3, characterised by higher intakes of sweet puddings and biscuits, wholegrain breakfast cereals and dairy (excluding cheese and butter) and lower alcohol intake, was associated with lower CVD (HR 0.76; 95% CI: 0.62, 0.93), coronary heart disease (HR: 0.68; 95% CI: 0.52, 0.90) and stroke (HR: 0.68; 95% CI: 0.47, 0.99) incidence and a beneficial CVD profile at baseline, while DP1 with an unfavourable profile, showed no clear associations after 12 years follow-up. Dietary pattern 2 (DP2), characterised by higher intake of pulses, fish, poultry, processed/red meat, rice, pasta and vegetables, was not associated with the aforementioned outcomes. These data may provide insight for development of public health initiatives focussing on feasible changes in dietary habits
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A nutrigenetic approach to investigate the relationship between metabolic traits and vitamin D status in an Asian Indian population
Studies in Asian Indians have examined the association of metabolic traits with vitamin D status. However, findings have been quite inconsistent. Hence, we aimed to explore the relationship between metabolic traits and 25-hydroxyvitamin D [25(OH)D] concentrations. We investigate whether this relationship was modified by lifestyle factors using a nutrigenetic approach in 545 Asian Indians randomly selected from the Chennai Urban Rural Epidemiology Study (219 normal glucose tolerant individuals, 151 with pre-diabetes and 175 individuals with type 2 diabetes). A metabolic genetic risk score (GRS) was developed using five common metabolic disease-related genetic variants. There was a significant interaction between metabolic GRS and carbohydrate intake (energy%) on 25(OH)D (Pinteraction = 0.047). Individuals consuming a low carbohydrate diet (≤62%) and those having lesser number of metabolic risk alleles (GRS ≤ 1) had significantly higher levels of 25(OH)D (p = 0.033). Conversely, individuals consuming a high carbohydrate diet despite having lesser number of risk alleles did not show a significant increase in 25(OH)D (p = 0.662). In summary, our findings show that individuals carrying a smaller number of metabolic risk alleles are likely to have higher 25(OH)D levels if they consume a low carbohydrate diet. These data support the current dietary carbohydrate recommendations of 50%–60% energy suggesting that reduced metabolic genetic risk increases 25(OH)D
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Moderate Champagne consumption promotes an acute improvement in acute endothelial-independent vascular function in healthy human volunteers
Epidemiological studies have suggested an inverse correlation between red wine consumption and the incidence of CVD. However, Champagne wine has not been fully investigated for its cardioprotective potential. In order to assess whether acute and moderate Champagne wine consumption is capable of modulating vascular function, we performed a randomised, placebo-controlled, cross-over intervention trial. We show that consumption of Champagne wine, but not a control matched for alcohol, carbohydrate and fruit-derived acid content, induced an acute change in endothelium-independent vasodilatation at 4 and 8 h post-consumption. Although both Champagne wine and the control also induced an increase in endothelium-dependent vascular reactivity at 4 h, there was no significant difference between the vascular effects induced by Champagne or the control at any time point. These effects were accompanied by an acute decrease in the concentration of matrix metalloproteinase (MMP-9), a significant decrease in plasma levels of oxidising species and an increase in urinary excretion of a number of phenolic metabolites. In particular, the mean total excretion of hippuric acid, protocatechuic acid and isoferulic acid were all significantly greater following the Champagne wine intervention compared with the control intervention. Our data suggest that a daily moderate consumption of Champagne wine may improve vascular performance via the delivery of phenolic constituents capable of improving NO bioavailability and reducing matrix metalloproteinase activity
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