Magnetoresistance and electronic structure of asymmetric GaAs/AlGaAs double quantum wells in the in-plane/tilted magnetic field

Bilayer two-dimensional electron systems formed by a thin barrier in the GaAs buffer of a standard heterostructure were investigated by magnetotransport measurements. In magnetic fields oriented parallel to the electron layers, the magnetoresistance exhibits an oscillation associated with the depopulation of the higher occupied subband and the field-induced transition into a decoupled bilayer. Shubnikov-de Haas oscillations in slightly tilted magnetic fields allow to reconstruct the evolution of the electron concentration in the individual subbands as a function of the in-plane magnetic field. The characteristics of the system derived experimentally are in quantitative agreement with numerical self-consistent-field calculations of the electronic structure.Comment: 6 pages, 5 figure

Physiological quality, content and activity of antioxidants in soybean seeds artificially aged.

ABSTRACT - The objective of this study was to evaluate physiological quality, content, and activity of antioxidants, in soybean seeds subjected to accelerated aging during different periods. Seeds of cultivars BRS 258, BRS 262 and BRS 268, subjected to accelerated aging during 12, 24, 36 and 48 hours and non-aged seeds were used. After each aging period, the seed were evaluated by tests of: germination; first count and tetrazolium. The total of phenolic compounds, total flavonoides, total of isoflavones, and activity for eliminating ABTS°+ radicals were quantified. There were differences among cultivars according to vigor and viability only after seeds were aged. Cultivars BRS 158 and BRS 268 have shown better seed physiological quality in each aging period; however, not presenting higher amounts of isoflavones and efficiency in removing free radicals. For all cultivars, the values for total of phenolic compounds, as well as total of flavonoids have shown quadratic positive behavior; the values for isoflavones remained constant and the vigor and viability showed contrary trend to activity of antioxidant agents. RESUMO: Qualidade fisiológica, conteúdo e atividade de antioxidantes presentes em sementes de soja envelhecidas artificialmente. O objetivo deste trabalho foi avaliar a qualidade fisiológica, o conteúdo e a atividade de agentes antioxidantes presentes em sementes de soja envelhecidas durante diferentes períodos. Foram utilizadas sementes das cultivares BRS 258, BRS 262 e BRS 268, envelhecidas durante 12, 24, 36 e 48 h e sementes não envelhecidas. Após cada período de envelhecimento, as sementes foram avaliadas pelo testes de: germinação; primeira contagem e tetrazólio. Foram quantificados: compostos fenólicos totais; flavonóides totais; total de isoflavonas e atividade eliminadora do radical ABTS°+. Houve diferença entre as cultivares em relação ao vigor e viabilidade somente quando foram envelhecidas. BRS 158 e BRS 268 apresentaram melhor qualidade fisiológica de sementes em cada período de envelhecimento, porém, não apresentaram maior quantidade de isoflavonas e eficiência no sequestro dos radicais livres. Para todas as cultivares, os valores de compostos fenólicos totais, assim como os flavonóides totais, apresentaram comportamento quadrático positivo; os valores das isoflavonas permaneceram constantes e o vigor e a viabilidade apresentaram tendência contrária à atividade dos agentes antioxidantes

Can You Hear us Now? Voices from the Margin: Using Indigenous Methodologies in Geographic Research

Indigenous methodologies are an alternative way of thinking about research processes. Although these methodologies vary according to the ways in which different Indigenous communities express their own unique knowledge systems, they do have common traits. This article argues that research on Indigenous issues should be carried out in a manner which is respectful and ethically sound from an Indigenous perspective. This naturally challenges Western research paradigms, yet it also affords opportunities to contribute to the body of knowledge about Indigenous peoples. It is further argued that providing a mechanism for Indigenous peoples to participate in and direct these research agendas ensures that their communal needs are met, and that geographers then learn how to build ethical research relationships with them. Indigenous methodologies do not privilege Indigenous researchers because of their Indigeneity, since there are many ‘insider’ views, and these are thus suitable for both Indigenous and non-Indigenous researchers. However, there is a difference between research done within an Indigenous context using Western methodologies and research done using Indig- enous methodologies which integrates Indigenous voices. This paper will discuss those differences while presenting a historical context of research on Indigenous peoples, providing further insights into what Indigenous methodologies entail, and proposing ways in which the academy can create space for this discourse

Biology, Fishery, Conservation and Management of Indian Ocean Tuna Fisheries

The focus of the study is to explore the recent trend of the world tuna fishery with special reference to the Indian Ocean tuna fisheries and its conservation and sustainable management. In the Indian Ocean, tuna catches have increased rapidly from about 179959 t in 1980 to about 832246 t in 1995. They have continued to increase up to 2005; the catch that year was 1201465 t, forming about 26% of the world catch. Since 2006 onwards there has been a decline in the volume of catches and in 2008 the catch was only 913625 t. The Principal species caught in the Indian Ocean are skipjack and yellowfin. Western Indian Ocean contributed 78.2% and eastern Indian Ocean 21.8% of the total tuna production from the Indian Ocean. The Indian Ocean stock is currently overfished and IOTC has made some recommendations for management regulations aimed at sustaining the tuna stock. Fishing operations can cause ecological impacts of different types: by catches, damage of the habitat, mortalities caused by lost or discarded gear, pollution, generation of marine debris, etc. Periodic reassessment of the tuna potential is also required with adequate inputs from exploratory surveys as well as commercial landings and this may prevent any unsustainable trends in the development of the tuna fishing industry in the Indian Ocean

Genetic loci regulate Sarbecovirus pathogenesis: A comparison across mice and humans

Coronavirus (CoV) cause considerable morbidity and mortality in humans and other mammals, as evidenced by the emergence of Severe Acute Respiratory CoV (SARS-CoV) in 2003, Middle East Respiratory CoV (MERS-CoV) in 2012, and SARS-CoV-2 in 2019. Although poorly characterized, natural genetic variation in human and other mammals modulate virus pathogenesis, as reflected by the spectrum of clinical outcomes ranging from asymptomatic infections to lethal disease. Using multiple human epidemic and zoonotic Sarbecoviruses, coupled with murine Collaborative Cross genetic reference populations, we identify several dozen quantitative trait loci that regulate SARS-like group-2B CoV pathogenesis and replication. Under a Chr4 QTL, we deleted a candidate interferon stimulated gene, Trim14 which resulted in enhanced SARS-CoV titers and clinical disease, suggesting an antiviral role during infection. Importantly, about 60 % of the murine QTL encode susceptibility genes identified as priority candidates from human genome-wide association studies (GWAS) studies after SARS-CoV-2 infection, suggesting that similar selective forces have targeted analogous genes and pathways to regulate Sarbecovirus disease across diverse mammalian hosts. These studies provide an experimental platform in rodents to investigate the molecular-genetic mechanisms by which potential cross mammalian susceptibility loci and genes regulate type-specific and cross-SARS-like group 2B CoV replication, immunity, and pathogenesis in rodent models. Our study also provides a paradigm for identifying susceptibility loci for other highly heterogeneous and virulent viruses that sporadically emerge from zoonotic reservoirs to plague human and animal populations

Functional Annotation of ESR1 Gene Fusions in Estrogen Receptor-Positive Breast Cancer

RNA sequencing (RNA-seq) detects estrogen receptor alpha gene (ESR1) fusion transcripts in estrogen receptor-positive (ER+) breast cancer, but their role in disease pathogenesis remains unclear. We examined multiple ESR1 fusions and found that two, both identified in advanced endocrine treatment-resistant disease, encoded stable and functional fusion proteins. In both examples, ESR1-e6>YAP1 and ESR1-e6>PCDH11X, ESR1 exons 1–6 were fused in frame to C-terminal sequences from the partner gene. Functional properties include estrogen-independent growth, constitutive expression of ER target genes, and anti-estrogen resistance. Both fusions activate a metastasis-associated transcriptional program, induce cellular motility, and promote the development of lung metastasis. ESR1-e6>YAP1- and ESR1-e6>PCDH11X-induced growth remained sensitive to a CDK4/6 inhibitor, and a patient-derived xenograft (PDX) naturally expressing the ESR1-e6>YAP1 fusion was also responsive. Transcriptionally active ESR1 fusions therefore trigger both endocrine therapy resistance and metastatic progression, explaining the association with fatal disease progression, although CDK4/6 inhibitor treatment is predicted to be effective. Lei et al. show that transcriptionally active estrogen receptor gene (ESR1) fusions identified from late-stage, treatment-refractory estrogen receptor-positive (ER+) breast cancer drive pan-endocrine therapy resistance and metastatic progression. Growth of breast tumors driven by ESR1 fusions at primary and metastatic sties can be suppressed with a CDK4/6 inhibitor