The presence of White students and the emergence of Black-White within-school inequalities: two interaction-based mechanisms

This article investigates mechanism-based explanations for a well-known empirical pattern in sociology of education, namely, that Black-White unequal access to school resources -- defined as advanced coursework -- is the highest in racially diverse and majority-White schools. Through an empirically calibrated and validated agent-based model, this study explores the dynamics of two qualitatively informed mechanisms, showing (1) that we have reason to believe that the presence of White students in school can influence the emergence of Black-White advanced enrollment disparities and (2) that such influence can represent another possible explanation for the macro-level pattern of interest. Results contribute to current scholarly accounts of within-school inequalities, shedding light into policy strategies to improve the educational experiences of Black students in racially integrated settings

Adjusting for academic preparedness when estimating enrollment disparities in advanced high school coursework

Whether racial disparities in enrollment in advanced high school coursework can be attributed to differences in prior academic preparation is a central empirical question in sociological research, with important implications for education policy. However, the regression-based approaches to this question that are predominant in the literature suffer significant methodological limitations by implicitly assuming that students are similarly prepared if and only if they have similar values on a selected set of academic background measures. Here, we provide a general technique to estimate enrollment disparities in advanced coursework between similarly-prepared students of different races that is less vulnerable to these limitations. We introduce a novel measure of academic preparedness, a student's ex-ante probability of "success" in the course, directly adjust for this single measure in a regression model of enrollment on race, and assess the robustness of estimated disparities to potential unmeasured confounding. We illustrate this approach by analyzing Black-White disparities in AP mathematics enrollment in a large, urban, public school system in the United States. We find that preexisting differences in academic preparation do not fully explain the under-representation of Black students relative to White students in AP mathematics, and contrast our results with those from traditional approaches

Avaliação do potencial produtivo de cultivares de mandioca industrial desenvolvidas no sistema de produção orgânica em Campo Grande, MS.

Publicado também na: RAT: Revista Raízes e Amidos Tropicais, v. 3, 2007. (SEP 037)

Theory for phonon pumping by magnonic spin currents

In recent years several experimental observations and theoretical predictions of unique phenomena involving the interplay between spin currents and the coupled magnetization-elastic dynamics have invigorated the field of spintronics. One important experiment reported several years ago showed that elastic waves can produce spin pumping, that is, generation of spin currents in a metallic film in contact with a ferromagnetic material. Very recently the Onsager reciprocal of this effect has been observed in samples made of a film of the insulating ferrimagnet yttrium iron garnet in contact with a platinum strip with nanoscopic silver particles that is known to exhibit a giant spin Hall effect. By passing an electric current through the metallic strip, the spin current generated by the spin Hall effect produces a large magnonic spin current that excites phonons with microwave frequency, observed by Brillouin light scattering. Here we show that these experiments are explained by a theory based on a process in which one magnon in the spin current creates one phonon and another magnon, with conservation of energy and momentum. The theoretical value of the critical charge current in the metallic strip necessary to drive phonons and the values of the phonon frequencies are in good agreement with the values measured experimentally

Scopolamine induces deficits in spontaneous object-location recognition and fear-learning in marmoset monkeys

The non-selective muscarinic receptor antagonist scopolamine (SCP) induces memory deficits in both animals and humans. However, few studies have assessed the effects of amnesic agents on memory functions of marmosets – a small-bodied neotropical primate that is becoming increasingly used as a translational model for several neuropathologies. Here we assessed the effects of an acute SCP administration (0.03 mg/kg, sc) on the behavior of adult marmoset monkeys in two tasks. In the spontaneous object-location (SOL) recognition task, two identical neutral stimuli were explored on the sample trial, after which preferential exploration of the displaced versus the stationary object was analyzed on the test trial. In the fear-motivated behavior (FMB) procedure, the same subjects were submitted to an initial baseline trial, followed by an exposure period to a snake model and lastly a post-exposure trial. All trials and inter-trial intervals lasted 10 min for both tests. Results showed that on the SOL test trial, the saline group explored the displaced object significantly longer than its identical stationary counterpart, whereas SCP-treated marmosets explored both objects equivalently. In the FMB test, the saline group – but not the SCP-treated animals – spent significantly less time where the stimulus had been specifically encountered and more time being vigilant of their surroundings, compared to pre-exposure levels. Drug-related effects on general activity, overall exploration (SOL task) and behavioral response to the aversive stimulus (FMB task) were not observed. SCP thus impaired the marmosets’ short-term ability to detect changes associated with the spatial location of ethologically irrelevant (SOL task) and relevant stimuli (FMB task). Similar results have been reported in other animal species. Marmosets may thus help reduce the translational gap between pre-clinical studies and memory-associated human pathologies

Interannual variability of ground surface thermal regimes in Livingston and Deception islands, Antarctica (2007–2021)

The absence of vegetation in most ice-free areas of Antarctica makes the soil surface very sensitive to atmosphere dynamics, especially in the western sector of the Antarctic Peninsula, an area within the limits of the permafrost zone. To evaluate the possible effects of regional warming on frozen soils, we conducted an analysis of ground surface temperatures (GSTs) from 2007 to 2021 from different monitoring sites in Livingston and Deception islands (South Shetlands archipelago, Antarctica). The analysis of the interannual evolution of the GST and their daily regimes and the freezing and thawing indexes reveals that climate change is showing impacts on seasonal and perennially frozen soils. Freezing Degree Days (FDD) have decreased while Thawing Degree Day (TDD) have increased during the study period, resulting in a balance that is already positive at the sites at lower elevations. Daily freeze–thaw cycles have been rare and absent since 2014. Meanwhile, the most common thermal regimes are purely frozen – F1 (daily temperatures < = 0.5C), isothermal – IS (ranging between 0.5C to +0.5C), and purely thawed – T1 (> = +0.5C). A decrease in F1 days has been observed, while the IS and T1 days increased by about 60 days between 2007 and 2021. The annual number of days with snow cover increased between 2009 and 2014 and decreased since then. The GST and the daily thermal regimes evolution point to general heating, which may be indicative of the degradation of the frozen soils in the study area.Ministry of Economy of the Government of Spain; PERMAMODEL, Grant/Award Number: POL2006-01918; PERMAPLANET, Grant/Award Number: CTM2009-10165; PERMASNOW, Grant/Award Number: CTM2014-52021-R; PARANTAR, Grant/Award Number: PID2020-115269GBI00; ANTARPERMA, Grant/Award Number: CTM2011-15565-Einfo:eu-repo/semantics/publishedVersio

Unveiling time in dose-response models to infer host susceptibility to pathogens

The biological effects of interventions to control infectious diseases typically depend on the intensity of pathogen challenge. As much as the levels of natural pathogen circulation vary over time and geographical location, the development of invariant efficacy measures is of major importance, even if only indirectly inferrable. Here a method is introduced to assess host susceptibility to pathogens, and applied to a detailed dataset generated by challenging groups of insect hosts (Drosophila melanogaster) with a range of pathogen (Drosophila C Virus) doses and recording survival over time. The experiment was replicated for flies carrying the Wolbachia symbiont, which is known to reduce host susceptibility to viral infections. The entire dataset is fitted by a novel quantitative framework that significantly extends classical methods for microbial risk assessment and provides accurate distributions of symbiont-induced protection. More generally, our data-driven modeling procedure provides novel insights for study design and analyses to assess interventions

Individual variation in susceptibility or exposure to SARS-CoV-2 lowers the herd immunity threshold

Funding Information: We thank Jorge Carneiro, Ben Cooper, José Ferreira Machado, Kate Langwig, Robert MacKay, Paul McKeigue, Antonio Montalbán, Joe Schoneman, Laurette Tuckerman and Simon Wood for valuable discussions throughout this study. At the University of Strathclyde, Matthew Burns, Zhichun Jiang, Naithan McNeil, Lauren Schofield and Aidan West conducted their final year BSc projects on Communicating Mathematics and Statistics, supervised by M.G.M.G., on topics related to this study while this paper was being written. This has contributed clarity to our presentation. The models presented here were first submitted to medRxiv on 27 April 2020 and posted soon after. Applications to the COVID-19 pandemic and subsequent updates followed. We are grateful to the preprint server for making our work available to interested readers in real time. M.U.F. received funding from Conselho Nacional de Desenvolvimento Científico e Tecnológico, Brazil. Funding Information: We thank Jorge Carneiro, Ben Cooper, Jos? Ferreira Machado, Kate Langwig, Robert MacKay, Paul McKeigue, Antonio Montalb?n, Joe Schoneman, Laurette Tuckerman and Simon Wood for valuable discussions throughout this study. At the University of Strathclyde, Matthew Burns, Zhichun Jiang, Naithan McNeil, Lauren Schofield and Aidan West conducted their final year BSc projects on Communicating Mathematics and Statistics, supervised by M.G.M.G. on topics related to this study while this paper was being written. This has contributed clarity to our presentation. The models presented here were first submitted to medRxiv on 27 April 2020 and posted soon after. Applications to the COVID-19 pandemic and subsequent updates followed. We are grateful to the preprint server for making our work available to interested readers in real time. M.U.F. received funding from Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico, Brazil. Publisher Copyright: © 2022 Elsevier LtdIndividual variation in susceptibility and exposure is subject to selection by natural infection, accelerating the acquisition of immunity, and reducing herd immunity thresholds and epidemic final sizes. This is a manifestation of a wider population phenomenon known as “frailty variation”. Despite theoretical understanding, public health policies continue to be guided by mathematical models that leave out considerable variation and as a result inflate projected disease burdens and overestimate the impact of interventions. Here we focus on trajectories of the coronavirus disease (COVID-19) pandemic in England and Scotland until November 2021. We fit models to series of daily deaths and infer relevant epidemiological parameters, including coefficients of variation and effects of non-pharmaceutical interventions which we find in agreement with independent empirical estimates based on contact surveys. Our estimates are robust to whether the analysed data series encompass one or two pandemic waves and enable projections compatible with subsequent dynamics. We conclude that vaccination programmes may have contributed modestly to the acquisition of herd immunity in populations with high levels of pre-existing naturally acquired immunity, while being crucial to protect vulnerable individuals from severe outcomes as the virus becomes endemic.publishersversionpublishe

Geotecnologia na construção de mapas participativos: estratégia para planejamento de propriedades na Amazônia Oriental.

A relação do agricultor com o ambiente que o cerca pode direcioná-lo a uma superexploração dos recursos naturais, refletindo ao longo dos anos no aumento de áreas improdutivas. Desse modo, surge a necessidade de planejar a paisagem com o objetivo de identificar os espaços mais adequados ao desenvolvimento das atividades econômicas. Assim, o uso de tecnologia de geoprocessamento tem sido apontado como uma ferramenta na construção de uma gestão sustentável. O estudo foi realizado nos municípios de Bragança, Capitão Poço e Garrafão do Norte, nos quais foram entrevistadas 12 famílias de agricultores. Como resultado, foram obtidos os perfis das famílias e a construção de mapas participativos que, segundo os agricultores são importante instrumento para gestão da propriedade