401 research outputs found
Information compression at the turbulent-phase transition in cold atom gases
The statistical properties of physical systems in thermal equilibrium are
blatantly different from their far-from-equilibrium counterparts. In the
latter, fluctuations often dominate the dynamics and might cluster in ordered
patterns in the form of dissipative coherent structures. Here, we study the
transition of a cold atomic cloud, driven close to a sharp electronic
resonance, from a stable to a turbulent phase. From the atomic density
distribution -- measured using a spatially-resolved pump-probe technique -- we
have computed the Shannon entropy on two different basis sets. Information
compression, corresponding to a minimum in the Shannon entropy, has been
observed at criticality, where the system fluctuations organize into high-order
(low-entropy) patterns. Being independent of the representation used, this
feature is a property shared by a vast class of physical systems undergoing
phase transitions.Comment: information compression, turbulent-phase transition, cold atoms,
critical opalescence, second-order phase transitio
Prediction of a financial crisis in Latin American companies using the mixed logistic regression model
The development of statistical methods for predicting the financial crisis of a company is a real contribution to scientific research. These methods identify possible adverse financial situations of the companies, through the behavior of their financial indicators. The contribution of this work is to compare the binary classification by different prediction methods of mixed logistic models to predict a future financial crisis in new companies.
The results based on an application involving companies from the Argentina, Peru and Chile Stock Exchange showed that all prediction methods were able to predict with high accuracy the financial crisis of the next year.http://chjs.soche.cl/images/vol7n1_2016/chjs-07-01-03.pdfpublishedVersionFil: Giampaoli, Viviana. University of SĂŁo Paulo. Department of Statistics; Brasil.Fil: Tamura, Karin A. University of SĂŁo Paulo. Department of Statistics; Brasil.Fil: Caro, Norma P. Universidad Nacional de CĂłrdoba. Facultad de Ciencias EconĂłmicas; Argentina.Fil: SimĂ”es de Araujo, Luiz J. University of SĂŁo Paulo. Faculty of Economics, Administration and Accounting; Brasil.EstadĂstica y Probabilida
An international comparative study of blood pressure in populations of European vs. African descent
Background: The consistent finding of higher prevalence of hypertension in US blacks compared
to whites has led to speculation that African-origin populations are particularly susceptible to this
condition. Large surveys now provide new information on this issue.
Methods: Using a standardized analysis strategy we examined prevalence estimates for 8 white
and 3 black populations (N = 85,000 participants).
Results: The range in hypertension prevalence was from 27 to 55% for whites and 14 to 44% for
blacks.
Conclusions: These data demonstrate that not only is there a wide variation in hypertension
prevalence among both racial groups, the rates among blacks are not unusually high when viewed
internationally. These data suggest that the impact of environmental factors among both
populations may have been under-appreciated
Magnetic Resonance Imaging of the Brain in Diabetes
Diabetic patients are at increased risk for stroke, but little is known about the presence of other brain lesions. We studied the association of magnetic resonance imagingâdetected brain lesions to diabetes in 1,252 individuals aged 65â75 years who were randomly selected from eight European population registries or defined working populations. All scans were centrally read for brain abnormalities, including infarcts, white matter lesions, and atrophy. We used a three-point scale to rate periventricular white matter lesions, and the volume of subcortical lesions was calculated according to their number and size. Subjective grading of cortical atrophy by lobe and summation of the lobar grades resulted in a total cortical atrophy score. The mean of three linear measurements of the ventricular diameter relative to the intracranial cavity defined the severity of subcortical atrophy. After adjustment for possible confounders, diabetes was associated with cortical brain atrophy but not with any focal brain lesions or subcortical atrophy. There was a strong interaction of diabetes and hypertension, such that the association between diabetes and cortical atrophy existed only in hypertensive but not in normotensive participants. Cognitive and pathological data are needed to determine the clinical significance of these findings as well as to understand the mechanisms underlying these associations
Noise control in enclosures: Modeling and experiments with T-shaped acoustic resonators
Relative risks for Stroke by Age, Sex, and Population Based on Follow-up of 18 European Populations in the MORGAM Project
Noise control in enclosures: Modeling and experiments with T-shaped acoustic resonators
This paper presents a theoretical and experimental study of noise control in enclosures using a T-shaped acoustic resonator array. A general model with multiple resonators is developed to predict the acoustic performance of small resonators placed in an acoustic enclosure. Analytical solutions for the sound pressure inside the enclosure and the volume velocity source strength out of the resonator aperture are derived when a single resonator is installed, which provides insight into the physics of acoustic interaction between the enclosure and the resonator. Based on the understanding of the coupling between the individual resonators and enclosure modes, both targeted and nontargeted, a sequential design methodology is proposed for noise control in the enclosure using an array of acoustic resonators. Design examples are given to illustrate the control performance at a specific or at several resonance peaks within a frequency band of interest. Experiments are conducted to systematically validate the theory and the design method. The agreement between the theoretical and experimental results shows that, with the help of the presented theory and design methodology, either single or multiple resonance peaks of the enclosure can be successfully controlled using an optimally located acoustic resonator array. © 2007 Acoustical Society of America
Amino acid profiles in older adults with frailty. Secondary analysis from MetaboFrail and BIOSPHERE studies
An altered amino acid metabolism has been described in frail older adults which may contribute to muscle loss and functional decline associated with frailty. In the present investigation, we compared circulating amino acid profiles of older adults with physical frailty and sarcopenia (PF&S, n = 94), frail/pre-frail older adults with type 2 diabetes mellitus (F-T2DM, n = 66), and robust non-diabetic controls (n = 40). Partial least squares discriminant analysis (PLSâDA) models were built to define the amino acid signatures associated with the different frailty phenotypes. PLSâDA allowed correct classification of participants with 78.2 ± 1.9% accuracy. Older adults with F-T2DM showed an amino acid profile characterized by higher levels of 3-methylhistidine, alanine, arginine, ethanolamine, and glutamic acid. PF&S and control participants were discriminated based on serum concentrations of aminoadipic acid, aspartate, citrulline, cystine, taurine, and tryptophan. These findings suggest that different types of frailty may be characterized by distinct metabolic perturbations. Amino acid profiling may therefore serve as a valuable tool for frailty biomarker discovery
Exact expression for the diffusion propagator in a family of time-dependent anharmonic potentials
We have obtained the exact expression of the diffusion propagator in the
time-dependent anharmonic potential . The
underlying Euclidean metric of the problem allows us to obtain analytical
solutions for a whole family of the elastic parameter a(t), exploiting the
relation between the path integral representation of the short time propagator
and the modified Bessel functions. We have also analyzed the conditions for the
appearance of a non-zero flow of particles through the infinite barrier located
at the origin (b<0).Comment: RevTex, 19 pgs. Accepted in Physical Review
Combined Influence of Waist and Hip Circumference on Risk of Death in a Large Cohort of European and Australian Adults
Background - Waist circumference and hip circumference are both strongly associated with risk of death; however, their joint association has rarely been investigated.
Methods and Results - The MONICA Risk, Genetics, Archiving, and Monograph (MORGAM) Project was conducted in 30 cohorts from 11 countries; 90 487 men and women, aged 30 to 74 years, predominantly white, with no history of cardiovascular disease, were recruited in 1986 to 2010 and followed up for up to 24 years. Hazard ratios were estimated using sexâspecific Cox models, stratified by cohort, with age as the time scale. Models included baseline categorical obesity measures, age, total and highâdensity lipoprotein cholesterol, systolic blood pressure, antihypertensive drugs, smoking, and diabetes mellitus. A total of 9105 allâcause deaths were recorded during a median followâup of 10 years. Hazard ratios for allâcause death presented Jâ or Uâshaped associations with most obesity measures. With waist and hip circumference included in the same model, for all hip sizes, having a smaller waist was strongly associated with lower risk of death, except for men with the smallest hips. In addition, among those with smaller waists, hip size was strongly negatively associated with risk of death, with â20% more people identified as being at increased risk compared with waist circumference alone.
Conclusions - A more complex relationship between hip circumference, waist circumference, and risk of death is revealed when both measures are considered simultaneously. This is particularly true for individuals with smaller waists, where having larger hips was protective. Considering both waist and hip circumference in the clinical setting could help to best identify those at increased risk of death
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