498 research outputs found
Generation of vortices and observation of Quantum Turbulence in an oscillating Bose-Einstein Condensate
We report on the experimental observation of vortex formation and production
of tangled vortex distribution in an atomic BEC of Rb-87 atoms submitted to an
external oscillatory perturbation. The oscillatory perturbations start by
exciting quadrupolar and scissors modes of the condensate. Then regular
vortices are observed finally evolving to a vortex tangle configuration. The
vortex tangle is a signature of the presence of a turbulent regime in the
cloud. We also show that this turbulent cloud has suppression of the aspect
ratio inversion typically observed in quantum degenerate bosonic gases during
free expansion.Comment: to appear in JLTP - QFS 200
Integrating the Water Planetary Boundary With Water Management From Local to Global Scales
The planetary boundaries framework defines the "safe operating space for humanity" represented by nine global processes that can destabilize the Earth System if perturbed. The water planetary boundary attempts to provide a global limit to anthropogenic water cycle modifications, but it has been challenging to translate and apply it to the regional and local scales at which water problems and management typically occur. We develop a cross-scale approach by which the water planetary boundary could guide sustainable water management and governance at subglobal contexts defined by physical features (e.g., watershed or aquifer), political borders (e.g., city, nation, or group of nations), or commercial entities (e.g., corporation, trade group, or financial institution). The application of the water planetary boundary at these subglobal contexts occurs via two approaches: (i) calculating fair shares, in which local water cycle modifications are compared to that context's allocation of the global safe operating space, taking into account biophysical, socioeconomic, and ethical considerations; and (ii) defining a local safe operating space, in which interactions between water stores and Earth System components are used to define local boundaries required for sustaining the local water system in stable conditions, which we demonstrate with a case study of the Cienaga Grande de Santa Marta wetlands in Colombia. By harmonizing these two approaches, the water planetary boundary can ensure that water cycle modifications remain within both local and global boundaries and complement existing water management and governance approaches
Risk factors for raised left ventricular filling pressure by cardiovascular magnetic resonance: prognostic insights
Background
Cardiovascular magnetic resonance (CMR) imaging shows promise in estimating pulmonary capillary wedge pressure (PCWP) non-invasively. At the population level, the prognostic role of CMR-modelled PCWP remains unknown. Furthermore, the relationship between CMR-modelled PCWP and established risk factors for cardiovascular disease has not been well characterized.
Objective
The main aim of this study was to investigate the prognostic value of CMR-modelled PCWP at the population level.
Methods
Employing data from the imaging substudy of the UK Biobank, a very large prospective population-based cohort study, CMR-modelled PCWP was calculated using a model incorporating left atrial volume, left ventricular mass and sex. Logistic regression explored the relationships between typical cardiovascular risk factors and raised CMR-modelled PCWP (â„15 mmHg). Cox regression was used to examine the impact of typical risk factors and CMR-modelled PCWP on heart failure (HF) and major adverse cardiovascular events (MACE).
Results
Data from 39 163 participants were included in the study. Median age of all participants was 64 years (inter-quartile range: 58 to 70), and 47% were males. Clinical characteristics independently associated with raised CMR-modelled PCWP included hypertension [odds ratio (OR) 1.57, 95% confidence interval (CI) 1.44â1.70, P < 0.001], body mass index (BMI) [OR 1.57, 95% CI 1.52â1.62, per standard deviation (SD) increment, P < 0.001], male sex (OR 1.37, 95% CI 1.26â1.47, P < 0.001), age (OR 1.33, 95% CI 1.27â1.41, per decade increment, P < 0.001) and regular alcohol consumption (OR 1.10, 95% CI 1.02â1.19, P = 0.012). After adjusting for potential confounders, CMR-modelled PCWP was independently associated with incident HF [hazard ratio (HR) 2.91, 95% CI 2.07â4.07, P < 0.001] and MACE (HR 1.48, 95% CI 1.16â1.89, P = 0.002).
Conclusions
Raised CMR-modelled PCWP is an independent risk factor for incident HF and MACE. CMR-modelled PCWP should be incorporated into routine CMR reports to guide HF diagnosis and further management
Tune in to your emotions: a robust personalized affective music player
The emotional power of music is exploited in a personalized affective music player (AMP) that selects music for mood enhancement. A biosignal approach is used to measure listenersâ personal emotional reactions to their own music as input for affective user models. Regression and kernel density estimation are applied to model the physiological changes the music elicits. Using these models, personalized music selections based on an affective goal state can be made. The AMP was validated in real-world trials over the course of several weeks. Results show that our models can cope with noisy situations and handle large inter-individual differences in the music domain. The AMP augments music listening where its techniques enable automated affect guidance. Our approach provides valuable insights for affective computing and user modeling, for which the AMP is a suitable carrier application
Asteroseismology of Eclipsing Binary Stars in the Kepler Era
Eclipsing binary stars have long served as benchmark systems to measure
fundamental stellar properties. In the past few decades, asteroseismology - the
study of stellar pulsations - has emerged as a new powerful tool to study the
structure and evolution of stars across the HR diagram. Pulsating stars in
eclipsing binary systems are particularly valuable since fundamental properties
(such as radii and masses) can determined using two independent techniques.
Furthermore, independently measured properties from binary orbits can be used
to improve asteroseismic modeling for pulsating stars in which mode
identifications are not straightforward. This contribution provides a review of
asteroseismic detections in eclipsing binary stars, with a focus on space-based
missions such as CoRoT and Kepler, and empirical tests of asteroseismic scaling
relations for stochastic ("solar-like") oscillations.Comment: 28 pages, 12 figures, 2 tables; Proceedings of the AAS topical
conference "Giants of Eclipse" (AASTCS-3), July 28 - August 2 2013, Monterey,
C
Overriding water table control on managed peatland greenhouse gas emissions
Global peatlands store more carbon than is naturally present in the atmosphere1,2. However, many peatlands are under pressure from drainage-based agriculture, plantation development and fire, with the equivalent of around 3% of all anthropogenic greenhouse gases emitted from drained peatland3â5. Efforts to curb such emissions are intensifying through the conservation of undrained peatlands and rewetting of drained systems6. Here we report CO2 eddy covariance data from 16 locations and CH4 data from 41 locations in the British Isles, and combine them with published data from sites across all major peatland biomes. We find that the mean annual effective water-table depth (WTDe; that is, the average depth of the aerated peat layer) overrides all other ecosystem- and management-related controls on greenhouse gas fluxes. We estimate that every 10 cm of reduction in WTDe could reduce the net warming impact of CO2 and CH4 emissions (100-year Global Warming Potentials) by at least 3 t CO2e ha-1 yr-1, until WTDe is < 30 cm. Raising water levels further would continue to have a net cooling effect until WTDe is < 10 cm. Our results suggest that greenhouse gas emissions from peatlands drained for agriculture could be greatly reduced without necessarily halting their productive use. Halving WTDe in all drained agricultural peatlands, for example, could reduce emissions by the equivalent of over 1% of global anthropogenic emissions
Modeling the cumulative genetic risk for multiple sclerosis from genome-wide association data
BACKGROUND:
Multiple sclerosis (MS) is the most common cause of chronic neurologic disability beginning in early to middle adult life. Results from recent genome-wide association studies (GWAS) have substantially lengthened the list of disease loci and provide convincing evidence supporting a multifactorial and polygenic model of inheritance. Nevertheless, the knowledge of MS genetics remains incomplete, with many risk alleles still to be revealed.
METHODS:
We used a discovery GWAS dataset (8,844 samples, 2,124 cases and 6,720 controls) and a multi-step logistic regression protocol to identify novel genetic associations. The emerging genetic profile included 350 independent markers and was used to calculate and estimate the cumulative genetic risk in an independent validation dataset (3,606 samples). Analysis of covariance (ANCOVA) was implemented to compare clinical characteristics of individuals with various degrees of genetic risk. Gene ontology and pathway enrichment analysis was done using the DAVID functional annotation tool, the GO Tree Machine, and the Pathway-Express profiling tool.
RESULTS:
In the discovery dataset, the median cumulative genetic risk (P-Hat) was 0.903 and 0.007 in the case and control groups, respectively, together with 79.9% classification sensitivity and 95.8% specificity. The identified profile shows a significant enrichment of genes involved in the immune response, cell adhesion, cell communication/signaling, nervous system development, and neuronal signaling, including ionotropic glutamate receptors, which have been implicated in the pathological mechanism driving neurodegeneration. In the validation dataset, the median cumulative genetic risk was 0.59 and 0.32 in the case and control groups, respectively, with classification sensitivity 62.3% and specificity 75.9%. No differences in disease progression or T2-lesion volumes were observed among four levels of predicted genetic risk groups (high, medium, low, misclassified). On the other hand, a significant difference (F = 2.75, P = 0.04) was detected for age of disease onset between the affected misclassified as controls (mean = 36 years) and the other three groups (high, 33.5 years; medium, 33.4 years; low, 33.1 years).
CONCLUSIONS:
The results are consistent with the polygenic model of inheritance. The cumulative genetic risk established using currently available genome-wide association data provides important insights into disease heterogeneity and completeness of current knowledge in MS genetics
Young and Intermediate-age Distance Indicators
Distance measurements beyond geometrical and semi-geometrical methods, rely
mainly on standard candles. As the name suggests, these objects have known
luminosities by virtue of their intrinsic proprieties and play a major role in
our understanding of modern cosmology. The main caveats associated with
standard candles are their absolute calibration, contamination of the sample
from other sources and systematic uncertainties. The absolute calibration
mainly depends on their chemical composition and age. To understand the impact
of these effects on the distance scale, it is essential to develop methods
based on different sample of standard candles. Here we review the fundamental
properties of young and intermediate-age distance indicators such as Cepheids,
Mira variables and Red Clump stars and the recent developments in their
application as distance indicators.Comment: Review article, 63 pages (28 figures), Accepted for publication in
Space Science Reviews (Chapter 3 of a special collection resulting from the
May 2016 ISSI-BJ workshop on Astronomical Distance Determination in the Space
Age
Complex relationships among personality traits, job characteristics, and work behaviors
The aim of the study was to investigate the additive, mediating, and moderating effects of personality traits and job characteristics on work behaviors. Job applicants (N = 161) completed personality questionnaires measuring extraversion, neuroticism, achievement motivation, and experience seeking. One and a half years later, supervisors rated the applicants' job performance, and the job incumbents completed questionnaires about skill variety, autonomy, and feedback, work stress, job satisfaction, work self-efficacy, and propensity to leave. LISREL was used to test 15 hypotheses. Perceived feedback mediated the relationship between achievement motivation and job performance. Extraversion predicted work self-efficacy and job satisfaction. Work stress mediated the relationship between neuroticism and job satisfaction. Job satisfaction and experience seeking were related to propensity to leave. Autonomy, skill variety, and feedback were related to job satisfaction
Enhanced glycemic control with combination therapy for type 2 diabetes in primary care
Type 2 diabetes mellitus is an increasingly common medical problem for primary care clinicians to address. Treatment of diabetes has evolved from simple replacement of insulin (directly or through insulin secretagogs) through capture of mechanisms such as insulin sensitizers, alpha-glucosidase inhibitors, and incretins. Only very recently has recognition of the critical role of the gastrointestinal system as a major culprit in glucose dysregulation been established. Since glycated hemoglobin A1c reductions provide meaningful risk reduction as well as improved quality of life, it is worthwhile to explore evolving paths for more efficient use of the currently available pharmacotherapies. Because diabetes is a progressive disease, even transiently successful treatment will likely require augmentation as the disorder progresses. Pharmacotherapies with complementary mechanisms of action will be necessary to achieve glycemic goals. Hence, clinicians need to be well informed about the various noninsulin alternatives that have been shown to be successful in glycemic goal attainment. This article reviews the benefits of glucose control, the current status of diabetes control, pertinent pathophysiology, available pharmacological classes for combination, limitations of current therapies, and suggestions for appropriate combination therapies, including specific suggestions for thresholds at which different strategies might be most effectively utilized by primary care clinicians
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