Evolution of magnetic fields through cosmological perturbation theory

The origin of galactic and extra-galactic magnetic fields is an unsolved problem in modern cosmology. A possible scenario comes from the idea of these fields emerged from a small field, a seed, which was produced in the early universe (phase transitions, inflation, ...) and it evolves in time. Cosmological perturbation theory offers a natural way to study the evolution of primordial magnetic fields. The dynamics for this field in the cosmological context is described by a cosmic dynamo like equation, through the dynamo term. In this paper we get the perturbed Maxwell's equations and compute the energy momentum tensor to second order in perturbation theory in terms of gauge invariant quantities. Two possible scenarios are discussed, first we consider a FLRW background without magnetic field and we study the perturbation theory introducing the magnetic field as a perturbation. The second scenario, we consider a magnetized FLRW and build up the perturbation theory from this background. We compare the cosmological dynamo like equation in both scenarios

Evaluation of the postharvest quality of Cagaita fruits (Eugenia dysenterica DC.) coated with chitosan and associated with refrigeration

Cagaita fruits are subject to seasonality and perishability. This work aims to use scanning electron microscopy (SEM) to evaluate the physicochemical characteristics, texture, color and physical structure of cagaita fruits coated with different chitosan concentrations. The fruits were divided as follows: T0 (uncoated fruits), T1 (fruits coated with 1% (v/v) chitosan), T2 (fruits coated with 2% (v/v) chitosan) and T3 (fruits coated with 3% (v/v) chitosan). They were analyzed at 0, 10, 20 and 30 days of storage. Titratable acidity and soluble solids content showed no conservation of fruit characteristics; they showed better results for uncoated fruits, as well as weight loss, vitamin C and peak strain. The color of cagaita fruits confirmed ripening during storage regardless of treatment. Scanning electron microscopy showed that the film solution did not adhere, as desired, to the cell wall of fruits. As the results of fruits coated with 3% pectin were close to control, further studies should be carried out with higher coating percentages so that the fruit quality is maintained during storage.Keywords: Physical structure, film solution, quality, shelf life

Strained graphene structures: from valleytronics to pressure sensing

Due to its strong bonds graphene can stretch up to 25% of its original size without breaking. Furthermore, mechanical deformations lead to the generation of pseudo-magnetic fields (PMF) that can exceed 300 T. The generated PMF has opposite direction for electrons originating from different valleys. We show that valley-polarized currents can be generated by local straining of multi-terminal graphene devices. The pseudo-magnetic field created by a Gaussian-like deformation allows electrons from only one valley to transmit and a current of electrons from a single valley is generated at the opposite side of the locally strained region. Furthermore, applying a pressure difference between the two sides of a graphene membrane causes it to bend/bulge resulting in a resistance change. We find that the resistance changes linearly with pressure for bubbles of small radius while the response becomes non-linear for bubbles that stretch almost to the edges of the sample. This is explained as due to the strong interference of propagating electronic modes inside the bubble. Our calculations show that high gauge factors can be obtained in this way which makes graphene a good candidate for pressure sensing.Comment: to appear in proceedings of the NATO Advanced Research Worksho

CLINICAL CHARACTERISTICS, OUTCOMES AND RISK FACTORS FOR DEATH AMONG CRITICALLY ILL PATIENTS WITH HIV-RELATED ACUTE KIDNEY INJURY

SUMMARY Background: The aim of this study is to describe clinical characteristics, outcomes and risk factors for death among patients with HIV-related acute kidney injury (AKI) admitted to an intensive care unit (ICU). Methods: A retrospective study was conducted with HIV-infected AKI patients admitted to the ICU of an infectious diseases hospital in Fortaleza, Brazil. All the patients with confirmed diagnosis of HIV and AKI admitted from January 2004 to December 2011 were included. A comparison between survivors and non-survivors was performed. Risk factors for death were investigated. Results: Among 256 AKI patients admitted to the ICU in the study period, 73 were identified as HIV-infected, with a predominance of male patients (83.6%), and the mean age was 41.2 ± 10.4 years. Non-survivor patients presented higher APACHE II scores (61.4 ± 19 vs. 38.6 ± 18, p = 0.004), used more vasoconstrictors (70.9 vs. 37.5%, p = 0.02) and needed more mechanical ventilation - MV (81.1 vs. 35.3%, p = 0.001). There were 55 deaths (75.3%), most of them (53.4%) due to septic shock. Independent risk factors for mortality were septic shock (OR = 14.2, 95% CI = 2.0-96.9, p = 0.007) and respiratory insufficiency with need of MV (OR = 27.6, 95% CI = 5.0-153.0, p < 0.001). Conclusion: Non-survivor HIV-infected patients with AKI admitted to the ICU presented higher severity APACHE II scores, more respiratory damage and hemodynamic impairment than survivors. Septic shock and respiratory insufficiency were independently associated to death

Water exercises and quality of life during pregnancy

<p>Abstract</p> <p>Background</p> <p>In Brazil, concern with the quality of life of pregnant women is one of the points emphasized in the Program for the Humanization of Prenatal Care and Childbirth launched in 2000. However, there are few references in the literature on the role of either land or water-based physical exercise on women's quality of life during pregnancy. The purpose of this study was to evaluate the effects of a physical exercise program of water aerobics on the quality of life (QOL) of sedentary pregnant women.</p> <p>Methods</p> <p>A comparative observational study involving sedentary low-risk pregnant women bearing a single fetus with gestational age less than 20 weeks at the time of admission to the study, who were receiving antenatal care at a public health service. One group of 35 women was given routine antenatal care, while another group of 31 women, in addition to receiving the same routine care as the first group, also participated in three classes of water aerobics per week. QOL was evaluated by applying the WHOQOL-BREF questionnaire in both groups at the 20^th, 28^thand 36^thweeks of pregnancy. In the same occasions, women also answered another questionnaire about their experience with pregnancy and antenatal care.</p> <p>Results</p> <p>The great majority of the participants considered that the practice of water aerobics had benefitted them in some way. QOL scores were found to be high in both groups during follow-up. There was no association between the practice of water aerobics and QOL.</p> <p>Conclusions</p> <p>Further studies involving larger sample sizes should be conducted in different sociocultural contexts and/or using other instruments to adequately evaluate the QOL of women during pregnancy.</p

HOXA1 is overexpressed in oral squamous cell carcinomas and its expression is correlated with poor prognosis

<p>Abstract</p> <p>Background</p> <p>HOX genes encode homeodomain-containing transcription factors involved in the regulation of cellular proliferation and differentiation during embryogenesis. However, members of this family demonstrated oncogenic properties in some malignancies. The present study investigated whether genes of the HOXA cluster play a role in oral cancer.</p> <p>Methods</p> <p>In order to identify differentially expressed HOXA genes, duplex RT-PCR in oral samples from healthy mucosa and squamous cell carcinoma was used. The effects of HOXA1 on proliferation, apoptosis, adhesion, invasion, epithelial-mesenchymal transition (EMT) and anchorage-independent growth were assessed in cells with up- and down-regulation of HOXA1. Immunohistochemical analysis using a tissue microarray (TMA) containing 127 oral squamous cell carcinomas (OSCC) was performed to determine the prognostic role of HOXA1 expression.</p> <p>Results</p> <p>We showed that transcripts of HOXA genes are more abundant in OSCC than in healthy oral mucosa. In particular, HOXA1, which has been described as one of the HOX members that plays an important role in tumorigenesis, was significantly more expressed in OSCCs compared to healthy oral mucosas. Further analysis demonstrated that overexpression of HOXA1 in HaCAT human epithelial cells promotes proliferation, whereas downregulation of HOXA1 in human OSCC cells (SCC9 cells) decreases it. Enforced HOXA1 expression in HaCAT cells was not capable of modulating other events related to tumorigenesis, including apoptosis, adhesion, invasion, EMT and anchorage-independent growth. A high number of HOXA1-positive cells was significantly associated with T stage, N stage, tumor differentiation and proliferative potential of the tumors, and was predictive of poor survival. In multivariate analysis, HOXA1 was an independent prognostic factor for OSCC patients (HR: 2.68; 95% CI: 1.59-2.97; p = 0.026).</p> <p>Conclusion</p> <p>Our findings indicate that HOXA1 may contribute to oral carcinogenesis by increasing tumor cell proliferation, and suggest that HOXA1 expression might be helpful as a prognostic marker for patients with OSCC.</p