Delay times and reflection in chaotic cavities with absorption

Absorption yields an additional exponential decay in open quantum systems which can be described by shifting the (scattering) energy E along the imaginary axis, E+i\hbar/2\tau_{a}. Using the random matrix approach, we calculate analytically the distribution of proper delay times (eigenvalues of the time-delay matrix) in chaotic systems with broken time-reversal symmetry that is valid for an arbitrary number of generally nonequivalent channels and an arbitrary absorption rate 1/\tau_{a}. The relation between the average delay time and the ``norm-leakage'' decay function is found. Fluctuations above the average at large values of delay times are strongly suppressed by absorption. The relation of the time-delay matrix to the reflection matrix S^{\dagger}S is established at arbitrary absorption that gives us the distribution of reflection eigenvalues. The particular case of single-channel scattering is explicitly considered in detail.Comment: 5 pages, 3 figures; final version to appear in PRE (relation to reflection extended, new material with Fig.3 added, experiment cond-mat/0305090 discussed

Search for patterns by combining cosmic-ray energy and arrival directions at the Pierre Auger Observatory

Energy-dependent patterns in the arrival directions of cosmic rays are searched for using data of the Pierre Auger Observatory. We investigate local regions around the highest-energy cosmic rays with E > = 6×1019 eV by analyzing cosmic rays with energies above E > = 5×1018 eV arriving within an angular separation of approximately 15°. We characterize the energy distributions inside these regions by two independent methods, one searching for angular dependence of energy-energy correlations and one searching for collimation of energy along the local system of principal axes of the energy distribution. No significant patterns are found with this analysis. The comparison of these measurements with astrophysical scenarios can therefore be used to obtain constraints on related model parameters such as strength of cosmic-ray deflection and density of point sources

Plasma signatures of Congenital Generalized Lipodystrophy patients identified by untargeted lipidomic profiling are not changed after a fat-containing breakfast meal

Background: The incapacity to store lipids in adipose tissue in Congenital Generalized Lipodystrophy (CGL) causes hypoleptinemia, increased appetite, ectopic fat deposition and lipotoxicity. CGL patients experience shortened life expectancy. The plasma lipidomic profile has not been characterized fully in CGL, nor has the extent of dietary intake in its modulation. The present work investigated the plasma lipidomic profile of CGL patients in comparison to eutrophic individuals at the fasted state and after a breakfast meal. Method: Blood samples from 11 CGL patients and 10 eutrophic controls were collected after 12 h fasting (T0) and 90 minutes after an ad libitum fat-containing breakfast (T90). The lipidomic profile of extracted plasma lipids was characterized by non-target liquid chromatography mass spectrometry. Results: Important differences between groups were observed at T0 and at T90. Several molecular species of fatty acyls, glycerolipids, sphingolipids and glycerophospholipids were altered in CGL. All the detected fatty acyl molecular species, several diacylglycerols and one triacylglycerol species were upregulated in CGL. Among sphingolipids, one sphingomyelin and one glycosphingolipid species showed downregulation in CGL. Alterations in the glycerophospholipids glycerophosphoethanolamines, glycerophosphoserines and cardiolipins were more complex. Interestingly, when comparing T90 versus T0, the lipidomic profile in CGL did not change as intensely as it did for control participants. Conclusions: The present study found profound alterations in the plasma lipidomic profile of complex lipids in CGL patients as compared to control subjects. A fat-containing breakfast meal did not appear to significantly influence the CGL profile observed in the fasted state. Our study may have implications for clinical practice, also aiding to a deeper comprehension of the role of complex lipids in CGL in view of novel therapeutic strategies

Pressão arterial entre trabalhadores de curtume Blood pressure among tannery workers

INTRODUÇÃO: O grupo das doenças cardiovasculares tem sido apontado como a principal causa de óbito no Brasil desde os anos 70, sendo a hipertensão arterial sistêmica (HAS) o fator de risco mais importante para esse grupo. Entre os trabalhadores observa-se correlação negativa entre o status ocupacional e a pressão arterial. Tais fatos ressaltam a importância do conhecimento da distribuição da pressão arterial sistêmica entre os distintos grupos profissionais. Assim, foi realizado estudo para descrever o status pressórico de uma população homogênea e estável de trabalhadores do setor secundário da economia, pouco especializados e que ganham baixos salários, estabelecendo a prevalência da HAS nesse grupo específico, relacionando-a com algumas covariáveis biológicas e socioeconômicas, e comparando-a com a prevalência de HAS em outros grupos profissionais no Brasil. MÉTODO: Foram estudados 73 trabalhadores regularmente empregados em julho de 1993 em um curtume situado no Município de Botucatu, cidade de médio porte da região Centro-Oeste do Estado de São Paulo, os quais foram submetidos a exame antropométrico, aferição de pressão arterial, anamnese e exame clínico. Os resultados foram comparados com os obtidos em estudos semelhantes, controlando-se o confundimento da idade por intermédio de diferentes técnicas. RESULTADOS: A prevalência bruta da HAS encontrada foi de 56,1%, sendo 15,8% a prevalência de hipertensão sistólica isolada. Ambas se associaram ao etilismo e ao tabagismo na população estudada. DISCUSSÃO: A prevalência da hipertensão foi consideravelmente alta e significativamente maior do que a encontrada em outros grupos de trabalhadores estudados no Brasil. Tal achado ressalta a necessidade da continuidade da investigação, objetivando o isolamento dos fatores implicados na elevação pressórica do grupo estudado.<br>INTRODUCTION: Cardiovascular diseases have been shown to be the leading cause of death in Brazil since the 1970s. High blood pressure has been the major risk factor among the above mentioned diseases. A negative correlation between occupational qualification and blood pressure has been observed among workers. The above mentioned facts bring out the importance of the knowledge of high blood pressure distribution among the different occupational groups. The aim of the present study was to describe the distribution of blood pressure in stable and homogeneous population of unskilled, low wage larning industrial workers. The Prevalence of high blood pressure was established for this specific group. This prevalence was also related to some biological and socio-economical covariates as compared with that among other occupational groups in Brazil. METHOD: The subjects were 73 active employees at a tannery in Botucatu, state of S.Paulo, Brazil, in July 1993. These subjects underwent blood pressure measurements, anamnesis and clinical examination. The results were compared with those of similar studies carried out in elsewhere Brazil. Age confounding was controlled by different techniques. RESULT: The crude prevalence of high blood pressure detected in this group of workers was of 56.1%, with 15.8% of isolated systolic hypertension. Alcohol abuse and smoking were associated with high blood pressure and isolated systolic hypertension in the population studied. DISCUSSION: Prevalence of hypertension in the group studied is significantly higher than that observed in other groups of workers studied in Brazil. Such a finding points to the need for further investigation so as to isolate those factors involved in the increased blood pressure found in this group