913 research outputs found
Hospitalized Infection as a Trigger for Acute Ischemic Stroke
Acute triggers for ischemic stroke, which may include infection, are understudied, as is whether background cardiovascular disease (CVD) risk modifies such triggering. We hypothesized that infection increases acute stroke risk, especially among those with low CVD risk
Model simulations on the long-term dispersal of 137Cs released into the Pacific Ocean off Fukushima
A sequence of global ocean circulation models, with horizontal mesh sizes of 0.5°, 0.25° and 0.1°, are used to estimate the long-term dispersion by ocean currents and mesoscale eddies of a slowly decaying tracer (half-life of 30 years, comparable to that of 137Cs) from the local waters off the Fukushima Dai-ichi Nuclear Power Plants. The tracer was continuously injected into the coastal waters over some weeks; its subsequent spreading and dilution in the Pacific Ocean was then simulated for 10 years. The simulations do not include any data assimilation, and thus, do not account for the actual state of the local ocean currents during the release of highly contaminated water from the damaged plants in March–April 2011. An ensemble differing in initial current distributions illustrates their importance for the tracer patterns evolving during the first months, but suggests a minor relevance for the large-scale tracer distributions after 2–3 years. By then the tracer cloud has penetrated to depths of more than 400 m, spanning the western and central North Pacific between 25°N and 55°N, leading to a rapid dilution of concentrations. The rate of dilution declines in the following years, while the main tracer patch propagates eastward across the Pacific Ocean, reaching the coastal waters of North America after about 5–6 years. Tentatively assuming a value of 10 PBq for the net 137Cs input during the first weeks after the Fukushima incident, the simulation suggests a rapid dilution of peak radioactivity values to about 10 Bq m−3 during the first two years, followed by a gradual decline to 1–2 Bq m−3 over the next 4–7 years. The total peak radioactivity levels would then still be about twice the pre-Fukushima values
Characteristics of Repetitive Thought Associated with Borderline Personality Features: A Multimodal Investigation of Ruminative Content and Style
Increased ruminative style of thought has been well documented in borderline personality disorder (BPD); however, less is known about how the content of rumination relates to domains of BPD features. Relationships between forms of rumination and BPD features were examined in an undergraduate sample with a wide range of BPD features. Participants completed self-report measures of rumination and a free-writing task about their repetitive thought. Rumination on specific themes, including anger rumination, depressive brooding, rumination on interpersonal situations, anxious rumination, and stress-reactive rumination were significantly associated with most BPD features after controlling for general rumination. Coded writing samples suggested that BPD features are associated with repetitive thought that is negative in valence, difficult to control, prolonged, unhelpful, and unresolved. Although rumination is often described as a form of self-focused attention, BPD relationship difficulties were correlated with greater other-focus in the writing samples, which may reflect more interpersonal themes. Across both self-reports and the writing task, the BPD feature of self-destructive behavior was associated specifically with anger and hostility, suggesting this content may play a particularly important role in fueling impulsive behavior. These findings suggest that both the style and the content of repetitive thought may play a role in BPD features
Hecke-type double sums, Appell-Lerch sums, and mock theta functions (I)
By developing a connection between partial theta functions and Appell-Lerch
sums, we find and prove a formula which expresses Hecke-type double sums in
terms of Appell-Lerch sums and theta functions. Not only does our formula prove
classical Hecke-type double sum identities such as those found in work Kac and
Peterson on affine Lie Algebras and Hecke modular forms, but once we have the
Hecke-type forms for Ramanujan's mock theta functions our formula gives
straightforward proofs of many of the classical mock theta function identities.
In particular, we obtain a new proof of the mock theta conjectures. Our formula
also applies to positive-level string functions associated with admissable
representations of the affine Lie Algebra as introduced by Kac and
Wakimoto
Associations of psychosocial factors with heart rate and its short-term variability: multi-ethnic study of atherosclerosis
OBJECTIVE: To examine the association of psychosocial factors with heart rate (HR) and its variability across multiple ethnic groups and by gender. Increased HR and reduced HR variability are markers of increased cardiovascular risk.
METHODS: Between 2000 and 2002, 6814 men and women (2624 Whites, 1895 African-Americans, 1492 Hispanics, and 803 Chinese) aged 45 to 84 years took part in the first examination of the Multi-Ethnic Study of Atherosclerosis. Associations of psychosocial variables with mean values of HR and its short-term variability were tested, using multivariate regression models.
RESULTS: In age, gender, race/ethnicity, and risk factor-adjusted analyses, a depressive symptom score was positively associated with HR and inversely associated with HR variability (standard deviation of normal-to-normal (N-N) interbeat intervals (SDNN) and the root mean square of successive differences in N-N intervals (RMSSD)). The adjusted mean differences per 1-SD (8 points) increment of depression score for HR, RMSSD, and SDNN were 0.5 (95% confidence interval (CI), 0.2-0.7), -0.8 (95% CI, -1.5 to -0.2), and -0.7 (95% CI, -1.1 to -0.2). The social support score was inversely associated with HR, but nonsignificantly associated with RMSSD and SDNN. There was no association of trait anger or trait anxiety with HR, RMSSD, or SDNN. Associations were generally consistent in men and women.
CONCLUSIONS: These findings generally support the hypothesis that depression may be associated with increased HR and reduced HR variability, which increase the risk of cardiovascular diseases.http://deepblue.lib.umich.edu/bitstream/2027.42/78571/1/OhiraDiezRoux2008_PsychosomMed.pd
Carotid Artery Wall Thickness and Risk of Stroke Subtypes: The Atherosclerosis Risk in Communities Study
Understanding associations of carotid atherosclerosis with stroke subtypes may contribute to more effective prevention of stroke
Common carotid artery intima-media thickness is as good as carotid intima-media thickness of all carotid artery segments in improving prediction of coronary heart disease risk in the Atherosclerosis Risk in Communities (ARIC) study
Carotid intima–media thickness (CIMT) and plaque information can improve coronary heart disease (CHD) risk prediction when added to traditional risk factors (TRF). However, obtaining adequate images of all carotid artery segments (A-CIMT) may be difficult. Of A-CIMT, the common carotid artery intima–media thickness (CCA-IMT) is relatively more reliable and easier to measure. We evaluated whether CCA-IMT is comparable to A-CIMT when added to TRF and plaque information in improving CHD risk prediction in the Atherosclerosis Risk in Communities (ARIC) study
Ages for exoplanet host stars
Age is an important characteristic of a planetary system, but also one that
is difficult to determine. Assuming that the host star and the planets are
formed at the same time, the challenge is to determine the stellar age.
Asteroseismology provides precise age determination, but in many cases the
required detailed pulsation observations are not available. Here we concentrate
on other techniques, which may have broader applicability but also serious
limitations. Further development of this area requires improvements in our
understanding of the evolution of stars and their age-dependent
characteristics, combined with observations that allow reliable calibration of
the various techniques.Comment: To appear in "Handbook of Exoplanets", eds. Deeg, H.J. & Belmonte,
J.A, Springer (2018
Common carotid intima media thickness and ankle-brachial pressure index correlate with local but not global atheroma burden:a cross sectional study using whole body magnetic resonance angiography
Common carotid intima media thickness (CIMT) and ankle brachial pressure index (ABPI) are used as surrogate marker of atherosclerosis, and have been shown to correlate with arterial stiffness, however their correlation with global atherosclerotic burden has not been previously assessed. We compare CIMT and ABPI with atheroma burden as measured by whole body magnetic resonance angiography (WB-MRA).50 patients with symptomatic peripheral arterial disease were recruited. CIMT was measured using ultrasound while rest and exercise ABPI were performed. WB-MRA was performed in a 1.5T MRI scanner using 4 volume acquisitions with a divided dose of intravenous gadolinium gadoterate meglumine (Dotarem, Guerbet, FR). The WB-MRA data was divided into 31 anatomical arterial segments with each scored according to degree of luminal narrowing: 0 = normal, 1 = <50%, 2 = 50-70%, 3 = 70-99%, 4 = vessel occlusion. The segment scores were summed and from this a standardized atheroma score was calculated.The atherosclerotic burden was high with a standardised atheroma score of 39.5±11. Common CIMT showed a positive correlation with the whole body atheroma score (β 0.32, p = 0.045), however this was due to its strong correlation with the neck and thoracic segments (β 0.42 p = 0.01) with no correlation with the rest of the body. ABPI correlated with the whole body atheroma score (β -0.39, p = 0.012), which was due to a strong correlation with the ilio-femoral vessels with no correlation with the thoracic or neck vessels. On multiple linear regression, no correlation between CIMT and global atheroma burden was present (β 0.13 p = 0.45), while the correlation between ABPI and atheroma burden persisted (β -0.45 p = 0.005).ABPI but not CIMT correlates with global atheroma burden as measured by whole body contrast enhanced magnetic resonance angiography in a population with symptomatic peripheral arterial disease. However this is primarily due to a strong correlation with ilio-femoral atheroma burden
Discovery of a weak magnetic field in the photosphere of the single giant Pollux
Aims: We observe the nearby, weakly-active single giant, Pollux, in order to
directly study and infer the nature of its magnetic field. Methods: We used the
new generation spectropolarimeters ESPaDOnS and NARVAL to observe and detect
circular polarization within the photospheric absorption lines of Pollux. Our
observations span 18 months from 2007-2009. We treated the spectropolarimetric
data using the Least-Squares Deconvolution method to create high
signal-to-noise ratio mean Stokes V profiles. We also measured the classical
activity indicator S-index for the Ca H&K lines, and the stellar radial
velocity (RV). Results: We have unambiguously detected a weak Stokes V signal
in the spectral lines of Pollux, and measured the related surface-averaged
longitudinal magnetic field Bl. The longitudinal field averaged over the span
of the observations is below one gauss. Our data suggest variations of the
longitudinal magnetic field, but no significant variation of the S-index. We
observe variations of RV which are qualitatively consistent with the published
ephemeris for a proposed exoplanet orbiting Pollux. The observed variations of
Bl appear to mimic those of RV, but additional data for this relationship to be
established. Using evolutionary models including the effects of rotation, we
derive the mass of Pollux and we discuss its evolutionary status and the origin
of its magnetic field. Conclusions: This work presents the first direct
detection of the magnetic field of Pollux, and demonstrates that ESPaDOnS and
NARVAL are capable of obtaining sub-G measurements of the surface-averaged
longitudinal magnetic field of giant stars, and of directly studying the
relationships between magnetic activity, stellar evolution and planet hosting
of these stars.Comment: 8 pages, 6 figures, accepted for publication in Astronomy and
Astrophysic
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