160 research outputs found
Comprehensive chromosome screening with synchronous blastocyst transfer: time for a paradigm shift☆
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Dietary fiber intake and mortality among survivors of myocardial infarction: prospective cohort study
Objective: To evaluate the associations of dietary fiber after myocardial infarction (MI) and changes in dietary fiber intake from before to after MI with all cause and cardiovascular mortality. Design: Prospective cohort study. Setting: Two large prospective cohort studies of US women and men with repeated dietary measurements: the Nurses’ Health Study and the Health Professionals Follow-Up Study. Participants: 2258 women and 1840 men who were free of cardiovascular disease, stroke, or cancer at enrollment, survived a first MI during follow-up, were free of stroke at the time of initial onset of MI, and provided food frequency questionnaires pre-MI and at least one post-MI. Main outcome measures Associations of dietary fiber post-MI and changes from before to after MI with all cause and cardiovascular mortality using Cox proportional hazards models, adjusting for drug use, medical history, and lifestyle factors. Results: Higher post-MI fiber intake was significantly associated with lower all cause mortality (comparing extreme fifths, pooled hazard ratio 0.75, 95% confidence interval 0.58 to 0.97). Greater intake of cereal fiber was more strongly associated with all cause mortality (pooled hazard ratio 0.73, 0.58 to 0.91) than were other sources of dietary fiber. Increased fiber intake from before to after MI was significantly associated with lower all cause mortality (pooled hazard ratio 0.69, 0.55 to 0.87). Conclusions: In this prospective study of patients who survived MI, a greater intake of dietary fiber after MI, especially cereal fiber, was inversely associated with all cause mortality. In addition, increasing consumption of fiber from before to after MI was significantly associated with lower all cause and cardiovascular mortality
ROMA (Rank-Ordered Multifractal Analysis) for intermittent fluctuations with global crossover behavior
Rank-Ordered Multifractal Analysis (ROMA), a recently developed technique
that combines the ideas of parametric rank ordering and one parameter scaling
of monofractals, has the capabilities of deciphering the multifractal
characteristics of intermittent fluctuations. The method allows one to
understand the multifractal properties through rank-ordered scaling or
non-scaling parametric variables. The idea of the ROMA technique is applied to
analyze the multifractal characteristics of the auroral zone electric field
fluctuations observed by SIERRA. The observed fluctuations span across
contiguous multiple regimes of scales with different multifractal
characteristics. We extend the ROMA technique such that it can take into
account the crossover behavior -- with the possibility of collapsing
probability distributions functions (PDFs) -- over these contiguous regimes.Comment: 24 pages, 18 figure
Generality of shear thickening in suspensions
Suspensions are of wide interest and form the basis for many smart fluids.
For most suspensions, the viscosity decreases with increasing shear rate, i.e.
they shear thin. Few are reported to do the opposite, i.e. shear thicken,
despite the longstanding expectation that shear thickening is a generic type of
suspension behavior. Here we resolve this apparent contradiction. We
demonstrate that shear thickening can be masked by a yield stress and can be
recovered when the yield stress is decreased below a threshold. We show the
generality of this argument and quantify the threshold in rheology experiments
where we control yield stresses arising from a variety of sources, such as
attractions from particle surface interactions, induced dipoles from applied
electric and magnetic fields, as well as confinement of hard particles at high
packing fractions. These findings open up possibilities for the design of smart
suspensions that combine shear thickening with electro- or magnetorheological
response.Comment: 11 pages, 9 figures, accepted for publication in Nature Material
Delivery of a chromosomally normal child from an oocyte with reciprocal aneuploid polar bodies
An integrated multi-study analysis of intra-subject variability in cerebrospinal fluid amyloid-β concentrations collected by lumbar puncture and indwelling lumbar catheter
INTRODUCTION:
Amyloid-β (Aβ) has been investigated as a diagnostic biomarker and therapeutic drug target. Recent studies found that cerebrospinal fluid (CSF) Aβ fluctuates over time, including as a diurnal pattern, and increases in absolute concentration with serial collection. It is currently unknown what effect differences in CSF collection methodology have on Aβ variability. In this study, we sought to determine the effect of different collection methodologies on the stability of CSF Aβ concentrations over time.
METHODS:
Grouped analysis of CSF Aβ levels from multiple industry and academic groups collected by either lumbar puncture (n=83) or indwelling lumbar catheter (n=178). Participants were either placebo or untreated subjects from clinical drug trials or observational studies. Participants had CSF collected by lumbar puncture or lumbar catheter for quantitation of Aβ concentration by enzyme linked immunosorbent assay. Data from all sponsors was converted to percent of the mean for Aβ40 and Aβ42 for comparison. Repeated measures analysis of variance was performed to assess for factors affecting the linear rise of Aβ concentrations over time.
RESULTS:
Analysis of studies collecting CSF via lumbar catheter revealed tremendous inter-subject variability of Aβ40 and Aβ42 as well as an Aβ diurnal pattern in all of the sponsors' studies. In contrast, Aβ concentrations from CSF samples collected at two time points by lumbar puncture showed no significant differences. Repeated measures analysis of variance found that only time and draw frequency were significantly associated with the slope of linear rise in Aβ40 and Aβ42 concentrations during the first 6 hours of collection.
CONCLUSIONS:
Based on our findings, we recommend minimizing the frequency of CSF draws in studies measuring Aβ levels and keeping the frequency standardized between experimental groups. The Aβ diurnal pattern was noted in all sponsors' studies and was not an artifact of study design. Averaging Aβ concentrations at each time point is recommended to minimize the effect of individual variability. Indwelling lumbar catheters are an invaluable research tool for following changes in CSF Aβ over 24-48 hours, but factors affecting Aβ concentration such as linear rise and diurnal variation need to be accounted for in planning study designs
‘What are you going to do, confiscate their passports?’ Professional perspectives on cross-border reproductive travel
Objective: This article reports findings from a UK-based study which explored the phenomenon of overseas travel for fertility treatment. The first phase of this project aimed to explore how infertility clinicians and others professionally involved in fertility treatment understand the nature and consequences of cross-border reproductive travel. Background: There are indications that, for a variety of reasons, people from the UK are increasingly travelling across national borders to access assisted reproductive technologies. While research with patients is growing, little is known about how ‘fertility tourism’ is perceived by health professionals and others with a close association with infertility patients. Methods: Using an interpretivist approach, this exploratory research included focussed discussions with 20 people professionally knowledgeable about patients who had either been abroad or were considering having treatment outside the UK. Semi-structured interviews were recorded, transcribed verbatim and subjected to a thematic analysis. Results: Three conceptual categories are developed from the data: ‘the autonomous patient’; ‘cross-border travel as risk’, and ‘professional responsibilities in harm minimisation’. Professionals construct nuanced, complex and sometimes contradictory narratives of the ‘fertility traveller’, as vulnerable and knowledgeable; as engaged in risky behaviour and in its active minimisation. Conclusions: There is little support for the suggestion that states should seek to prevent cross-border treatment. Rather, an argument is made for less direct strategies to safeguard patient interests. Further research is required to assess the impact of professional views and actions on patient choices and patient experiences of treatment, before, during and after travelling abroad
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Low Carbohydrate Diet From Plant or Animal Sources and Mortality Among Myocardial Infarction Survivors
Background: The healthiest dietary pattern for myocardial infarction (MI) survivors is not known. Specific long‐term benefits of a low‐carbohydrate diet (LCD) are unknown, whether from animal or vegetable sources. There is a need to examine the associations between post‐MI adherence to an LCD and all‐cause and cardiovascular mortality. Methods and Results: We included 2258 women from the Nurses' Health Study and 1840 men from the Health Professional Follow‐Up Study who had survived a first MI during follow‐up and provided a pre‐MI and at least 1 post‐MI food frequency questionnaire. Adherence to an LCD high in animal sources of protein and fat was associated with higher all‐cause and cardiovascular mortality (hazard ratios of 1.33 [95% CI: 1.06 to 1.65] for all‐cause mortality and 1.51 [95% CI: 1.09 to 2.07] for cardiovascular mortality comparing extreme quintiles). An increase in adherence to an animal‐based LCD prospectively assessed from the pre‐ to post‐MI period was associated with higher all‐cause mortality and cardiovascular mortality (hazard ratios of 1.30 [95% CI: 1.03 to 1.65] for all‐cause mortality and 1.53 [95% CI: 1.10 to 2.13] for cardiovascular mortality comparing extreme quintiles). An increase in adherence to a plant‐based LCD was not associated with lower all‐cause or cardiovascular mortality. Conclusions: Greater adherence to an LCD high in animal sources of fat and protein was associated with higher all‐cause and cardiovascular mortality post‐MI. We did not find a health benefit from greater adherence to an LCD overall after MI
Low-Mass X-ray Binaries and Globular Clusters in Centaurus A
We present results of Hubble Space Telescope and Chandra X-ray Observatory
observations of globular clusters (GCs) and low-mass X-ray binaries (LMXBs) in
the central regions of Centaurus A. Out of 440 GC candidates we find that 41
host X-ray point sources that are most likely LMXBs. We fit King models to our
GC candidates in order to measure their structural parameters. We find that GCs
that host LMXBs are denser and more compact, and have higher encounter rates
and concentrations than the GC population as a whole. We show that the higher
concentrations and masses are a consequence of the dependence of LMXB incidence
on central density and size plus the general trend for denser GCs to have
higher masses and concentrations. We conclude that neither concentration nor
mass are fundamental variables in determining the presence of LMXBs in GCs, and
that the more fundamental parameters relate to central density and size.Comment: 4 pages, 2 figures. Accepted for publication in ApJ Letter
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