Chaos in Anisotropic Pre-Inflationary Universes

We study the dynamics of anisotropic Bianchi type-IX models with matter and cosmological constant. The models can be thought as describing the role of anisotropy in the early stages of inflation. The concurrence of the cosmological constant and anisotropy are sufficient to produce a chaotic dynamics in the gravitational degrees of freedom, connected to the presence of a critical point of saddle-center type in the phase space of the system. The invariant character of chaos is guaranteed by the topology of the cylinders emanating from unstable periodic orbits in the neighborhood of the saddle-center. We discuss a possible mechanism for amplification of specific wavelengths of inhomogeneous fluctuations in the models. A geometrical interpretation is given for Wald's inequality in terms of invariant tori and their destruction by increasing values of the cosmological constant.Comment: 14 pages, figures available under request. submitted to Physical Review

Homoclinic chaos in the dynamics of a general Bianchi IX model

The dynamics of a general Bianchi IX model with three scale factors is examined. The matter content of the model is assumed to be comoving dust plus a positive cosmological constant. The model presents a critical point of saddle-center-center type in the finite region of phase space. This critical point engenders in the phase space dynamics the topology of stable and unstable four dimensional tubes $R \times S^3$, where $R$ is a saddle direction and $S^3$ is the manifold of unstable periodic orbits in the center-center sector. A general characteristic of the dynamical flow is an oscillatory mode about orbits of an invariant plane of the dynamics which contains the critical point and a Friedmann-Robertson-Walker (FRW) singularity. We show that a pair of tubes (one stable, one unstable) emerging from the neighborhood of the critical point towards the FRW singularity have homoclinic transversal crossings. The homoclinic intersection manifold has topology $R \times S^2$ and is constituted of homoclinic orbits which are bi-asymptotic to the $S^3$ center-center manifold. This is an invariant signature of chaos in the model, and produces chaotic sets in phase space. The model also presents an asymptotic DeSitter attractor at infinity and initial conditions sets are shown to have fractal basin boundaries connected to the escape into the DeSitter configuration (escape into inflation), characterizing the critical point as a chaotic scatterer.Comment: 11 pages, 6 ps figures. Accepted for publication in Phys. Rev.

Dynamical System Analysis for Inflation with Dissipation

We examine the solutions of the equations of motion for an expanding Universe, taking into account the radiation of the inflaton field energy. We then analyze the question of the generality of inflationary solutions in this more general setting of a dissipative system. We find a surprisingly rich behavior for the solutions of the dynamical system of equations in the presence of dissipational effects. We also determine that a value of dissipation as small as $\sim 10^{-7} H$ can lead to a smooth exit from inflation to radiation.Comment: Plain LaTex, 21 pages, 8 eps figs (uses epsf), to be published in Phys. Rev.

Aedes (Stegomyia) aegypti L. e a culicideofauna associada em área urbana da região sul, Brasil

Foram mostrados alguns aspectos sobre a ecologia de 11 espécies de Culicidae que procriam em recipientes, em uma área urbana do Sul do Brasil. Os mais variados tipos de recipientes foram listados como eficientes criadouros para larvas de culicídeos. Aedes aegypti apareceu como espécie recém-introduzida e limitada somente a duas áreas da cidade. As espécies predominantes foram: Culex quinquefasciatus, Culex coronator, Aedes aegypti, Aedes fluviatilis e Limatus durhamii.Some aspects of the ecology of eleven species of Culicidae that were found breeding in recipients in an urban area of Southern Brazil are presented. A great variety of recipients were listed as efficient breeding sites. Apparently Aedes aegypti has been recently introduced into the region and was limited to two areas of the city. Culex quinquefasciatus, Cx. coronator, Ae. aegypti, Ae. fluviatilis e Limatus durhamii were the predominant species

Can we rely on iFR for avoiding FFR? Conclusions of a 5-year experience

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017Background: Recently, the instantaneous wave free ratio (iFR), has been proposed an alternative or complementary method to fractional flow reserve (FFR). This new method does not require the use of adenosine and may expedite the speed of functional assessment. The iFR “hybrid strategy” relies on values 0,93 as definitive results which would not require the use of FFR. However, this strategy is much less consensual than FFR alone. Purpose: We aimed to assess the concordance of FFR and iFR results using the principle of the “hybrid strategy”, based on the 5-year experience of a single center. We also aimed to analyse the effect of iFR in the operator's decision to proceed to FFR, and its impact on procedure duration and radiation time/dosage. Methods: Single-center registry of all patients undergoing functional coronary lesion assessment during 5 years. FFR was used as a gold standard (with a cut-off point for intervention ≤0,80) for assessing the diagnostic accuracy of iFR in every patient who underwent measurements with both techniques. For analysis purposes, an iFR value 0,93 was considered negative (i.e. defer intervention). Values in between were deemed inconclusive. For statistical analysis we used the T student and Chi-Square tests. Results: Functional testing was undertaken in 326 patients (67±11 years, 65,6% male), encompassing 402 lesions. 154 lesions underwent assessment with both techniques, 222 by FFR only and 26 cases iFR only. The average iFR was 0,9±0,1. 60 lesions had an iFR >0,93 and 21 an iFR <0,86. An iFR value between 0,86 and 0,93 was strongly associated with the decision to proceed to FFR (χ2=30,1; p0,93 (71,4% vs 68%; p=0,792). In these cases, there was a statistically significant concordance of 87% between the iFR and FFR results (χ2=22,43; p<0,001). Notwithstanding, there were 4 out of 13 cases (30,7%) of positive iFR with negative FFR and 3 out of 42 (7,1%) cases of negative iFR and positive FFR. This difference was statistically significant (p=0,026). Regarding procedural time, radiation time and radiation dose, there were no statistically significant differences between patients who only underwent iFR, FFR only, or both techniques. Conclusions: The iFR results were inconclusive (i.e. between 0,86 and 0,93) in most cases. There was a high degree of concordance between the iFR and FFR values. However, a significant proportion of patients, particularly in cases of positive iFR (<0,86), were classified as negative by FFR. The use of iFR had no impact on procedural time, radiation time and radiation dose.info:eu-repo/semantics/publishedVersio

A Structural Equations Modeling Approach

COVID-19 vaccine hesitancy (VH) has caused concerns due to the possible fluctuations that may occur directly impacting the control of the pandemic. In this study, we aimed to estimate the prevalence and factors associated with COVID-19 VH in Portuguese-speaking countries. We developed a web survey (N:6,843) using an online, structured, and validated questionnaire. We used Measurement Models, Exploratory Factor Analysis, Exploratory Structural Equation Models, and Confirmatory Factor Analysis for the data analysis. The overall prevalence of COVID-19 VH in Portuguese-speaking countries was 21.1%. showed a statistically significant direct effect for VH: vaccine-related conspiracy beliefs (VB) (β = 0.886), perceived stress (PS) (β = 0.313), COVID-19 Misinformation (MIS) (β = 0.259) and individual responses to COVID-19 (CIR) (β = −0.122). The effect of MIS and CIR for VH was greater among men and of PS and VB among women; the effect of PS was greater among the youngest and of VB and CIR among the oldest. No discrepant differences were identified in the analyzed education strata. In conclusion, we found that conspiracy beliefs related to the vaccine strongly influence the decision to hesitate (not to take or to delay the vaccine). Specific characteristics related to gender, age group, social and cognitive vulnerabilities, added to the knowledge acquired, poorly substantiated and/or misrepresented about the COVID-19 vaccine, need to be considered in the planning of vaccination campaigns. It is necessary to respond in a timely, fast, and accurate manner to the challenges posed by vaccine hesitancy.publishersversionpublishe

The Brazilian Tunable Filter Imager for the SOAR telescope

This paper presents a new Tunable Filter Instrument for the SOAR telescope. The Brazilian Tunable Filter Imager (BTFI) is a versatile, new technology, tunable optical imager to be used in seeing-limited mode and at higher spatial fidelity using the SAM Ground-Layer Adaptive Optics facility at the SOAR telescope. The instrument opens important new science capabilities for the SOAR community, from studies of the centers of nearby galaxies and the insterstellar medium to statistical cosmological investigations. The BTFI takes advantage of three new technologies. The imaging Bragg Tunable Filter concept utilizes Volume Phase Holographic Gratings in a double-pass configuration, as a tunable filter, while a new Fabry-Perot (FP) concept involves technologies which allow a single FP etalon to act over a large range of interference orders and spectral resolutions. Both technologies will be in the same instrument. Spectral resolutions spanning the range between 25 and 30,000 can be achieved through the use of iBTF at low resolution and scanning FPs beyond R ~2,000. The third new technologies in BTFI is the use of EMCCDs for rapid and cyclically wavelength scanning thus mitigating the damaging effect of atmospheric variability through data acquisition. An additional important feature of the instrument is that it has two optical channels which allow for the simultaneous recording of the narrow-band, filtered image with the remaining (complementary) broad-band light. This avoids the uncertainties inherent in tunable filter imaging using a single detector. The system was designed to supply tunable filter imaging with a field-of-view of 3 arcmin on a side, sampled at 0.12" for direct Nasmyth seeing-limited area spectroscopy and for SAM's visitor instrument port for GLAO-fed area spectroscopy. The instrument has seen first light, as a SOAR visitor instrument. It is now in comissioning phase.Comment: accepted in PAS

The consequences of growth hormone-releasing hormone receptor haploinsufficiency for bone quality and insulin resistance

Objective Growth hormone (GH)/insulin-like growth factor (IGF) axis and insulin are key determinants of bone remodelling. Homozygous mutations in the GH-releasing hormone receptor (GHRHR) gene (GHRHR) are a frequent cause of genetic isolated GH deficiency (IGHD). Heterozygosity for GHRHR mutation causes changes in body composition and possibly an increase in insulin sensitivity, but its effects on bone quality are still unknown. The objective of this study was to assess the bone quality and metabolism and its correlation with insulin sensitivity in subjects heterozygous for a null mutation in the GHRHR. Patients and methods A cross-sectional study was performed on 76 normal subjects (68.4% females) (N/N) and 64 individuals (64.1% females) heterozygous for a mutation in the GHRHR (MUT/N). Anthropometric features, quantitative ultrasound (QUS) of the heel, bone markers [osteocalcin (OC) and CrossLaps], IGF-I, glucose and insulin were measured, and homeostasis model assessment of insulin resistance (HOMAIR) was calculated. Results There were no differences in age or height between the two groups, but weight (P = 0.007) and BMI (P = 0.001) were lower in MUT/N. There were no differences in serum levels of IGF-I, glucose, T-score or absolute values of stiffness and OC, but insulin (P = 0.01), HOMAIR (P = 0.01) and CrossLaps (P = 0.01) were lower in MUT/N. There was no correlation between OC and glucose, OC and HOMAIR in the 140 individuals as a whole or in the separate MUT/N or N/N groups. Conclusions This study suggests that one allele mutation in the GHRHR gene has a greater impact on energy metabolism than on bone quality.NIH, National Institutes of Health USA [1 R01 DK065718]FAPITEC/SE, BrazilCAPESFAEP