¿Podem as estruturas escolares melhorar as relações entre alunos e professores? A relação entre os períodos de orientação, atenção individualizada e o desempenho acadêmico dos estudantes

In this paper, we present findings from a three-year study of students' perceptions of personalization and, specifically, advisory as a reform strategy and its relationship to students' academic progress at 14 recently converted small high schools in a large, urban school district in California. This study examined the degree to which students' sense of personalization (connections to the school and to adults at the school) interacted with students' academic achievement, as measured by standardized test scores and weighted grade-point averages. In particular, we examined the relationship between students' perceptions of formal structures to enhance personalization -- such as advisory periods -- and students' academic achievement.Este estudio se centr en las relaciones entre las percepciones de estudiantes sobre niveles de personalizacin, sus opiniones sobre los periodos de asesoramiento, y los resultados acadmicos. Durante tres aos consecutivos se administraron 10.044 encuestas a estudiantes en 14 escuelas pequeas y re-estructuradas. Las respuestas fueron vinculadas a los promedios generales de las notas de los estudiantes ponderadas durante un solo ao y a los resultados de las pruebas normalizadas en Artes del Lenguaje Ingls. Los resultados de una serie de modelos de niveles mltiples indicaron que las percepciones ms positivas sobre la personalizacin pronosticaron mejores resultados acadmicos. Las percepciones de los estudiantes sobre el perodo de asesoramiento tambin fueron relacionados con el logro acadmico, pero en direccin opuesta: sentimientos positivos acerca de los perodos de asesoramiento se asociaron con peores resultados acadmicos. Estos resultados son consistentes con un trabajo cualitativo que sugiere que niveles ms altos de personalizacin son asociados con niveles ms altos de logros acadmicos, mejoras en la cultura escolar y ms compromiso de los estudiantes. Sin embargo, estos resultados tambin sugieren que las relaciones entre perodos de asesoramiento, personalizacin y resultados acadmicos no son tan sencillas como se haba pensado anteriormente.Este estudo focalizou as relaes entre as percepes dos alunos sobre os nveis de ateno individualizada e suas opinies sobre os perodos de orientao, com resultados acadmicos. Por trs anos consecutivos foram administrados 10.044 questionrios a alunos em 14 pequenas escolas que passaram for reformas. As respostas foram relacionadas com as mdias globais das notas dos alunos durante um nico ano ponderado e os resultados de testes padronizados na disciplina Lngua Inglesa. Os resultados de uma srie de modelos multi-nvel indicaram que as percepes mais positivas sobre a ateno individualizada prognosticaram melhores resultados acadmicos. As percepes dos alunos sobre o perodo de orientao tambm foram relacionadas com os resultados acadmicos, mas na direo oposta: sentimentos positivos sobre os perodos de orientao foram associados com piores resultados acadmicos. Estes resultados coincidem com um trabalho qualitativo que sugere que nveis mais elevados de ateno individualizada esto associados com nveis mais elevados de rendimento acadmico, melhorias na cultura escolar e mais engajamento dos alunos. No entanto, esses resultados tambm sugerem que as relaes entre perodos de orientao, ateno individualizada e os resultados acadmicos no so to simples quanto se pensava anteriormente

Development of Accessory Cells in B-Cell Compartments Is Retarted in B-Cell-Depleted Fetal Sheep

Accessory-cell populations in the lymphoid tissues of fetal sheep were investigated following depletion of B cells. An intraperitoneal injection of an anti-IgM antibody early in gestation resulted in a marked depletion of IgM+ cells in lymphoid tissues. Immune and enzyme histochemical techniques were used to identify accessory-cell populations in the ileal Peyer's patch, spleen, and lymph nodes of B-cell-depleted fetal sheep. The rudimentary follicles in the ileal Peyer's patch showed strong enzyme reactivity for 5′ nucleotidase, indicating the presence of follicular dendritic cells (FDCs). Enzyme reactivities for FDCs in primary follicles of the spleen and lymph nodes were absent, as were reactivities for metallophilic macrophages in the marginal zone of the spleen. MgATPase reactivity associated with dendritic-cell populations in the gut-associated lymphoid tissues was detected. A monoclonal antibody against complement receptor-2 (CD21) reacted with FDCs in the rudimentary follicles of the ileal Peyer's patch and immature FDCs in lymph nodes. The results suggest that the development of accessory-cell populations in B-cell compartments of peripheral but not central lymphoid tissues is dependent on the presence of B cells

Potential Improvements to the Nuclear Safety and Launch Approval Process for Nuclear Reactors Utilized for Space Power and Propulsion Applications

This study examines potential improvements that could be made to the nuclear safety and launch approval process for fission reactors to reduce the associated uncertainties in cost and schedule while continuing to ensure public safety and environmental protection. It concentrates on the launch approval and mission safety of fission power and propulsion applications of nuclear energy. Improvements to the launch approval process for radioisotope power systems (RPSs) are being considered elsewhere but are acknowledged throughout the report. The study considered technical, process, and organizational improvements to the launch approval processes. The study exclusively evaluated reactors that would not be started up prior to achieving a sufficiently high orbit, per United Nations (UN) Resolution 47/68.Potential criticality accidents were considered that could occur during a launch failure or abort or during reentry. Numerous scenarios were examined that might involve one or more Earth flybys as well as potential transportation missions that could intentionally return an active, or previously active fission reactor to Earth orbit. The Study Group was guided in its deliberations according to a number of fundamental principles. These included the paramount importance of adequate and appropriate levels of public safety and environmental protection as well as the importance of the inclusion of independent scientific, engineering, and safety reviews of the applications and proposals as a critical part of the process. Also considered was the need for the development of launch approval processes that might be different, depending upon the source of the application for launch approval, whether it be derived as a governmental launch, a commercial launch, or a hybrid/combination of the two. It is clear that all launches of nuclear reactors into space should have similar safety requirements; however, the safety review effort and the details of the analysis that are required should be commensurate with the potential hazards and the actual risk, which may differ based on the reactor design and its intended purpose. Finally, the study aimed at ensuring that whatever processes and procedures are developed should maximize the sufficiency, simplicity, and transparency of the processes. The Study Group reached five Conclusions and makes thirteen Recommendations. The Conclusions and Recommendations presented here are extensions of those presented previously in other studies. This report attempts to add specificity to the actions that need to be taken in order to move forward with successful space fission reactor programs. Without action to address the perceived and real problems in the launch approval process, designers and mission managers will be reluctant to commit the resources necessary to make space fission reactors a reality

Establishment of an In Vitro System Representing the Chicken Gut-Associated Lymphoid Tissue

The bursa of Fabricius is critical for B cell development and differentiation in chick embryos. This study describes the production in vitro, from dissociated cell suspensions, of cellular agglomerates with functional similarities to the chicken bursa. Co-cultivation of epithelial and lymphoid cells obtained from embryos at the appropriate developmental stage regularly led to agglomerate formation within 48 hours. These agglomerates resembled bursal tissue in having lymphoid clusters overlaid by well organized epithelium. Whereas lymphocytes within agglomerates were predominantly Bu-1a(+), a majority of those emigrating onto the supporting membrane were Bu-1a(-) and IgM(+). Both agglomerates and emigrant cells expressed activation-induced deaminase with levels increasing after 24 hours. Emigrating cells were actively proliferating at a rate in excess of both the starting cell population and the population of cells remaining in agglomerates. The potential usefulness of this system for investigating the response of bursal tissue to avian Newcastle disease virus (strain AF2240) was examined.This study was supported by a Fundamental grant (project no. 05-13-03-040J) from the Ministry of Higher Education, Malaysia. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Galactic and Magellanic Evolution with the SKA

As we strive to understand how galaxies evolve it is crucial that we resolve physical processes and test emerging theories in nearby systems that we can observe in great detail. Our own Galaxy, the Milky Way, and the nearby Magellanic Clouds provide unique windows into the evolution of galaxies, each with its own metallicity and star formation rate. These laboratories allow us to study with more detail than anywhere else in the Universe how galaxies acquire fresh gas to fuel their continuing star formation, how they exchange gas with the surrounding intergalactic medium, and turn warm, diffuse gas into molecular clouds and ultimately stars. The $\lambda$21-cm line of atomic hydrogen (HI) is an excellent tracer of these physical processes. With the SKA we will finally have the combination of surface brightness sensitivity, point source sensitivity and angular resolution to transform our understanding of the evolution of gas in the Milky Way, all the way from the halo down to the formation of individual molecular clouds.Comment: 25 pages, from "Advancing Astrophysics with the Square Kilometre Array", to appear in Proceedings of Scienc

Physiological responses to gastrointestinal nematode infection in sheep selected for genetic difference in resistance to 'Haemonchus contortus'

The benefit of selection for resistance to gastrointestinal (GI) nematode infection is a lower worm burden. The expectation is that resistant sheep should suffer less production loss due to a reduced parasite infection. Yet, productivity of resistant sheep is comparable to or lower than that of animals carrying a large parasite burden. This research was designed to determine if divergent selection for resistance to 'H. contortus' had produced correlated changes in one or more of the following variables, voluntary feed intake and diet selection, ruminal digestion and nutrient partitioning

Predicting the effects of parasite co-infection across species boundaries

It is normal for hosts to be co-infected by parasites. Interactions among co-infecting species can have profound consequences, including changing parasite transmission dynamics, altering disease severity and confounding attempts at parasite control. Despite the importance of co-infection, there is currently no way to predict how different parasite species may interact with one another, nor the consequences of those interactions. Here, we demonstrate a method that enables such prediction by identifying two nematode parasite groups based on taxonomy and characteristics of the parasitological niche. From an understanding of the interactions between the two defined groups in one host system (wild rabbits), we predict how two different nematode species, from the same defined groups, will interact in co-infections in a different host system (sheep), and then we test this experimentally. We show that, as predicted, in co-infections, the blood-feeding nematode Haemonchus contortus suppresses aspects of the sheep immune response, thereby facilitating the establishment and/or survival of the nematode Trichostrongylus colubriformis; and that the T. colubriformis-induced immune response negatively affects H. contortus. This work is, to our knowledge, the first to use empirical data from one host system to successfully predict the specific outcome of a different co-infection in a second host species. The study therefore takes the first step in defining a practical framework for predicting interspecific parasite interactions in other animal systems

Comparing Adult Cannabis Treatment-Seekers Enrolled in a Clinical Trial with National Samples of Cannabis Users in the United States

Background—Cannabis use rates are increasing among adults in the United States (US) while the perception of harm is declining. This may result in an increased prevalence of cannabis use disorder and the need for more clinical trials to evaluate efficacious treatment strategies. Clinical trials are the gold standard for evaluating treatment, yet study samples are rarely representative of the target population. This finding has not yet been established for cannabis treatment trials. This study compared demographic and cannabis use characteristics of a cannabis cessation clinical trial sample (run through National Drug Abuse Treatment Clinical Trials Network) with three nationally representative datasets from the US; 1) National Survey on Drug Use and Health, 2) National Epidemiologic Survey on Alcohol and Related Conditions-III, and 3) Treatment Episodes Data Set – Admissions. Methods—Comparisons were made between the clinical trial sample and appropriate cannabis using sub-samples from the national datasets, and propensity scores were calculated to determine the degree of similarity between samples. Results—Results showed that the clinical trial sample was significantly different from all three national datasets, with the clinical trial sample having greater representation among older adults, African Americans, Hispanic/Latinos, adults with more education, non-tobacco users, and daily and almost daily cannabis users. Conclusions—These results are consistent with previous studies of other substance use disorder populations and extend sample representation issues to a cannabis use disorder population. This illustrates the need to ensure representative samples within cannabis treatment clinical trials to improve the generalizability of promising findings