Shadows of charged rotating black holes: Kerr-Newman versus Kerr-Sen

Celebrating the centennial of its first experimental test, the theory of General Relativity (GR) has successfully and consistently passed all subsequent tests with flying colours. It is expected, however, that at certain scales new physics, in particular in the form of quantum corrections, will emerge, changing some of the predictions of GR, which is a classical theory. In this respect, black holes (BHs) are natural configurations to explore the quantum effects on strong gravitational fields. BH solutions in the low-energy effective field theory description of the heterotic string theory, which is one of the leading candidates to describe quantum gravity, have been the focus of many studies in the last three decades. The recent interest in strong gravitational lensing by BHs, in the wake of the Event Horizon Telescope observations, suggests comparing the BH lensing in both GR and heterotic string theory, in order to assess the phenomenological differences between these models. In this work, we investigate the differences in the shadows of two charged BH solutions with rotation: one arising in the context of GR, namely the Kerr-Newman solution, and the other within the context of low-energy heterotic string theory, the Kerr-Sen solution. We show and interpret, in particular, that the stringy BH always has a larger shadow, for the same physical parameters and observation conditions.Comment: 11 pages, 11 figures, Contribution to Selected Papers of the Fifth Amazonian Symposium on Physics, v2: references added, typos corrected, matches published versio

A novel behavioral fish model of nociception for testing analgesics

Pain is a major symptom in many medical conditions, and often interferes significantly with a person's quality of life. Although a priority topic in medical research for many years, there are still few analgesic drugs approved for clinical use. One reason is the lack of appropriate animal models that faithfully represent relevant hallmarks associated with human pain. Here we propose zebrafish (Danio rerio) as a novel short-term behavioral model of nociception, and analyse its sensitivity and robustness. Firstly, we injected two different doses of acetic acid as the noxious stimulus. We studied individual locomotor responses of fish to a threshold level of nociception using two recording systems: a video tracking system and an electric biosensor (the MOBS system). We showed that an injection dose of 10% acetic acid resulted in a change in behavior that could be used to study nociception. Secondly, we validated our behavioral model by investigating the effect of the analgesic morphine. In time-course studies, first we looked at the dose-response relationship of morphine and then tested whether the effect of morphine could be modulated by naloxone, an opioid antagonist. Our results suggest that a change in behavioral responses of zebrafish to acetic acid is a reasonable model to test analgesics. The response scales with stimulus intensity, is attenuated by morphine, and the analgesic effect of morphine is blocked with naloxone. The change in behavior of zebrafish associated with the noxious stimulus can be monitored with an electric biosensor that measures changes in water impedance. © 2011 by the authors; licensee MDPI, Basel, Switzerland

A SOLIDARIEDADE EM AÇÕES PEDAGÓGICAS NA MODALIDADE EAD

O presente artigo versa sobre o tema conhecimento-solidariedade em EAD. O objetivo principal do estudo é contribuir para a implementação de ações pedagógicas em EAD na perspectiva do conhecimento-solidariedade. A partir, principalmente, dos referenciais de Boaventura Santos, Jean Piaget e Yves deLa Taille procura-se compreender o que vem a ser o conhecimento solidariedade, bem como os valores e saberes que favorecem a ocorrência de ações pedagógicas de professores e alunos em EAD nessa perspectiva

Dissecção da Axila no Tratamento do Câncer de Mama

A dissecção da axila no tratamento do câncer da mama tem sido questionada quanto aos seus objetivos. No passado próximo a intenção era curativa: presentemente tem sido indicada principalmente para oferecer informação de extensão da doença (comprometimento de linfonodos por tumor) e tratamentos complementares, principalmente a quimioterapia adjuvante. Apenas alguns subgrupos de mulheres têm-se beneficiado realmente da quimioterapia adjuvante: as pré-meno-pausadas com linfonodos axilares comprometidos com tumor. Uma vez decidida a dissecção axilar, ainda resta a questão de saber se deve ser radical, ou limitada a níveis I e II (até músculo peitoral menor). Muitos centros importantes de câncer indicam a dissecção limitada da axila, que em média retira cerca de 10 linfonodos, alegando que desta forma não há risco de edema importante do braço e conseguem boa informação prognóstica e bom controle tumoral da axila. Aqueles que indicam a dissecção radical alegam que esta é a única forma de se obter informação real da situação axilar. Algumas pacientes podem ter linfonodos livres de tumor na parte baixa da axila, mas com tumor no ápice axilar ("skip metastasis") e a única forma de descobri-lo seria através da dissecção radical. Como a dissecção radical da axila pode causar edema do braço, é importante questionara real indicação da mesma. Pacientes em pós-menopausa e com axila clinicamente negativa talvez pudessem ter a alternativa de não dissecara axila de forma radical (e com isso não correr o risco de edema do braço), sem aumentara chance de falha de tratamento. O presente artigo discute o problema da dissecção da axila no tratamento do câncer da mama e mostra dados de 148 pacientes que fizeram tratamento conservador no Centro de Oncologia Campinas, metade das quais sem dissecção da axila

TESS asteroseismology of the known red-giant host stars HD 212771 and HD 203949

International audienc

Associations between changes in habitual sleep duration and lower self-rated health among COVID-19 survivors: findings from a survey across 16 countries/regions

Background: Self-rated health (SRH) is widely recognized as a clinically significant predictor of subsequent mortality risk. Although COVID-19 may impair SRH, this relationship has not been extensively examined. The present study aimed to examine the correlation between habitual sleep duration, changes in sleep duration after infection, and SRH in subjects who have experienced SARS-CoV-2 infection. Methods: Participants from 16 countries participated in the International COVID Sleep Study-II (ICOSS-II) online survey in 2021. A total of 10,794 of these participants were included in the analysis, including 1,509 COVID-19 individuals (who reported that they had tested positive for COVID-19). SRH was evaluated using a 0-100 linear visual analog scale. Habitual sleep durations of 9 h were defined as short and long habitual sleep duration, respectively. Changes in habitual sleep duration after infection of ≤ -2 h and ≥ 1 h were defined as decreased or increased, respectively. Results: Participants with COVID-19 had lower SRH scores than non-infected participants, and those with more severe COVID-19 had a tendency towards even lower SRH scores. In a multivariate regression analysis of participants who had experienced COVID-19, both decreased and increased habitual sleep duration after infection were significantly associated with lower SRH after controlling for sleep quality (β = −0.056 and −0.058, respectively, both p < 0.05); however, associations between current short or long habitual sleep duration and SRH were negligible. Multinomial logistic regression analysis showed that decreased habitual sleep duration was significantly related to increased fatigue (odds ratio [OR] = 1.824, p < 0.01), shortness of breath (OR = 1.725, p < 0.05), diarrhea/nausea/vomiting (OR = 2.636, p < 0.01), and hallucinations (OR = 5.091, p < 0.05), while increased habitual sleep duration was significantly related to increased fatigue (OR = 1.900, p < 0.01). Conclusions: Changes in habitual sleep duration following SARS-CoV-2 infection were associated with lower SRH. Decreased or increased habitual sleep duration might have a bidirectional relation with post-COVID-19 symptoms. Further research is needed to better understand the mechanisms underlying these relationships for in order to improve SRH in individuals with COVID-19.info:eu-repo/semantics/publishedVersio

Genome of the Avirulent Human-Infective Trypanosome—Trypanosoma rangeli

Background: Trypanosoma rangeli is a hemoflagellate protozoan parasite infecting humans and other wild and domestic mammals across Central and South America. It does not cause human disease, but it can be mistaken for the etiologic agent of Chagas disease, Trypanosoma cruzi. We have sequenced the T. rangeli genome to provide new tools for elucidating the distinct and intriguing biology of this species and the key pathways related to interaction with its arthropod and mammalian hosts.  Methodology/Principal Findings: The T. rangeli haploid genome is ,24 Mb in length, and is the smallest and least repetitive trypanosomatid genome sequenced thus far. This parasite genome has shorter subtelomeric sequences compared to those of T. cruzi and T. brucei; displays intraspecific karyotype variability and lacks minichromosomes. Of the predicted 7,613 protein coding sequences, functional annotations could be determined for 2,415, while 5,043 are hypothetical proteins, some with evidence of protein expression. 7,101 genes (93%) are shared with other trypanosomatids that infect humans. An ortholog of the dcl2 gene involved in the T. brucei RNAi pathway was found in T. rangeli, but the RNAi machinery is non-functional since the other genes in this pathway are pseudogenized. T. rangeli is highly susceptible to oxidative stress, a phenotype that may be explained by a smaller number of anti-oxidant defense enzymes and heatshock proteins.  Conclusions/Significance: Phylogenetic comparison of nuclear and mitochondrial genes indicates that T. rangeli and T. cruzi are equidistant from T. brucei. In addition to revealing new aspects of trypanosome co-evolution within the vertebrate and invertebrate hosts, comparative genomic analysis with pathogenic trypanosomatids provides valuable new information that can be further explored with the aim of developing better diagnostic tools and/or therapeutic targets