John Ogbu has studied minority education from a comparative perspective for over 30 years. The study reported in this book--jointly sponsored by the community and the school district in Shaker ...Heights, Ohio--focuses on the academic performance of Black American students. Not only do these students perform less well than White students at every social class level, but also less well than immigrant minority students, including Black immigrant students. Furthermore, both middle-class Black students in suburban school districts, as well as poor Black students in inner-city schools are not doing well. Ogbu's analysis draws on data from observations, formal and informal interviews, and statistical and other data. He offers strong empirical evidence to support the cross-class existence of the problem.
The book is organized in four parts:
*Part I provides a description of the twin problems the study addresses--the gap between Black and White students in school performance and the low academic engagement of Black students; a review of conventional explanations; an alternative perspective; and the framework for the study.
*Part II is an analysis of societal and school factors contributing to the problem, including race relations, Pygmalion or internalized White beliefs and expectations, levelling or tracking, the roles of teachers, counselors, and discipline.
* Community factors --the focus of this study--are discussed in Part III. These include the educational impact of opportunity structure, collective identity, cultural and language or dialect frame of reference in schooling, peer pressures, and the role of the family. This research focus does not mean exonerating the system and blaming minorities, nor does it mean neglecting school and society factors. Rather, Ogbu argues, the role of community forces should be incorporated into the discussion of the academic achievement gap by researchers, theoreticians, policymakers, educators, and minorities themselves who genuinely want to improve the academic achievement of African American children and other minorities.
*In Part IV, Ogbu presents a summary of the study's findings on community forces and offers recommendations--some of which are for the school system and some for the Black community.
Black American Students in an Affluent Suburb: A Study of Academic Disengagement is an important book for a wide range of researchers, professionals, and students, particularly in the areas of Black education, minority education, comparative and international education, sociology of education, educational anthropology, educational policy, teacher education, and applied anthropology.
Ternary alloyed CdZnTe quantum dots were prepared in aqueous medium using 3-Mercapto propionic acid as the capping agent. The structural and morphological characteristics of the alloyed CdZnTe were ...investigated through X-ray powder diffraction, Fourier transform infrared spectroscopy, Transmission electron microscopy and UV–visible absorption measurements. The diffraction patterns reveal the cubic zinc blende structure and the transmission electron microscopy measurement shows flower-like type microstructures. The UV–visible measurements showed blue shifted absorption peak with Zn alloying and the optical bandgap were determined with Tauc plot method. The nonlinear properties of the prepared CdZnTe were investigated using Z-scan technique with a continuous wave DPSS 532 nm laser source. The variations associated with the nonlinear absorption coefficients (
β
) and the third order nonlinear refractive indices (
n
2
) were determined employing open aperture and closed aperture Z-scan setup for different zinc content. The nonlinear refractive indices were negatively signed and showed a self-defocusing phenomena for all compositions, whereas the magnitude of nonlinear refractive indices and absorption coefficients varies with the zinc content due to the quantum confinement and thermal effects. The nonlinear susceptibilities (
χ
3
) of the alloyed quantum dots were also calculated. The alloyed CdZnTe nanostructures have good composition tuneable nonlinear characteristics and can considered as potential candidates for nonlinear optical devices and applications, such as optical limiters, optical switching, data storage, optical communications etc.
AIM: We develop a framework for quantifying invasions based on lagged trends in invasions (‘invasion debt’) with the aim of identifying appropriate metrics to quantify delayed responses at different ...invasion stages – from introduction to when environmental impacts occur. LOCATION: World‐wide; detailed case study in South Africa. METHODS: We define four components of invasion debt: the number of species not yet introduced but likely to be introduced in the future given current levels of introduction/propagule pressure; the establishment of introduced species; the potential increase in area invaded by established species (including invasive species); and the potential increase in impacts. We demonstrate the approach in terms of number of species for 21 known invasive Australian Acacia species globally and estimate three components of invasion debt for 58 Acacia species already introduced to South Africa by quantifying key invasion factors (environmental suitability, species invasion status, residence time, propagule pressure, spread rate and impacts). RESULTS: Current global patterns of invasive species richness reflect historical trends of introduction – most acacia species that will become invasive in southern Africa have already invaded, but there is a substantial establishment debt in South and North America. In South Africa, the likely consequence of invasion debt over the next 20 years was estimated at: four additional species becoming invasive with an average increase of 1075 km² invaded area per invasive species. We estimate that this would require over US$ 500 million to clear. MAIN CONCLUSIONS: Our results indicate that invasion debt is a valuable metric for reporting on the threats attributable to biological invasions, that invasion debt must be factored into strategic plans for managing global change, and, as with other studies, they highlight the value of proactive management. Given the uncertainty associated with biological invasions, further work is required to quantify the different components of invasion debt.
A Report of the American College of Cardiology Foundation Appropriate Use Criteria Task Force, American Heart Association, American Society of Echocardiography, American Society of Nuclear ...Cardiology, Heart Failure Society of America, Heart Rhythm Society, Society for Cardiovascular Angiography and Interventions, Society of Cardiovascular Computed Tomography, Society for Cardiovascular Magnetic Resonance, and Society of Thoracic Surgeons ACCF Multimodality Appropriate Use Criteria for the Detection and Risk Assessment of Ischemic Heart Disease Writing Group, Technical Panel, Task Force, and Indication Reviewers...Relationships With Industry and Other Entities (Relevant)... .403 Abstract The American College of Cardiology Foundation along with key specialty and subspecialty societies, conducted an appropriate use review of common clinical presentations for stable ischemic heart disease (SIHD) to consider use of stress testing and anatomic diagnostic procedures. The use of some modalities of testing in the initial evaluation of patients with symptoms representing ischemic equivalents, newly diagnosed heart failure, arrhythmias, and syncope was generally found to be Appropriate or May Be Appropriate, except in cases where low pre-test probability or low risk limited the benefit of most testing except exercise electrocardiogram (ECG).
There has been a dramatic growth in research on biological invasions over the past 20 years, but a mature understanding of the field has been hampered because invasion biologists concerned with ...different taxa and different environments have largely adopted different model frameworks for the invasion process, resulting in a confusing range of concepts, terms and definitions. In this review, we propose a unified framework for biological invasions that reconciles and integrates the key features of the most commonly used invasion frameworks into a single conceptual model that can be applied to all human-mediated invasions. The unified framework combines previous stage-based and barrier models, and provides a terminology and categorisation for populations at different points in the invasion process.
Using standardized methodology, the clinical scenarios (indications) in this document were developed by a diverse writing group to represent patient presentations encountered in everyday practice and ...were evaluated and rated by a separate, independent rating panel. Because there is significant clinical overlap between valvular and structural heart disease, separating the indications in the 2 AUC documents is somewhat arbitrary. (e.g., tests that expose the patient to ionizing radiation should not necessarily receive a lower score than those that do not). ...a given modality should be weighed specifically in the context of the clinical scenario with the potential harm considered relative to the potential benefit gained. Because a given modality may address diverse disease states, indications previously compiled in a single document may be spread over several AUC documents. First-degree family history of a bicuspid aortic valve A (8) R (1) R (1) R (1) R (1) 6.
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•A comprehensive overview of through-silicon-via technology (TSV) is presented.•TSV technology enables Moore’s Law to scale vertically.•We explore the challenges associated with ...running high volume TSV manufacturing.•We explore the unit process issues in creating TSVs.•We explore the design and yield challenges associated with TSV use.
The idea of using through-silicon-via (TSV) technology has been around for many years. However, this technology has only recently been introduced into high volume manufacturing. This paper gives a comprehensive summary of the TSV fabrication steps, including etch, insulation, and metallization. Along with the backside processing, assembly, metrology, design, packaging, reliability, testing and yield challenges that arise with the use of TSVs. Benefits and drawbacks for using each approach to manufacture TSVs are discussed including via-first, via-middle, and the via-last process. Several applications for TSVs are discussed including memory arrays and image sensors.
Evolutionary transitions in bacterial symbiosis Sachs, Joel L; Skophammer, Ryan G; Regus, John U
Proceedings of the National Academy of Sciences - PNAS,
06/2011, Letnik:
108, Številka:
Supplement 2
Journal Article
Recenzirano
Odprti dostop
Diverse bacterial lineages form beneficial infections with eukaryotic hosts. The origins, evolution, and breakdown of these mutualisms represent important evolutionary transitions. To examine these ...key events, we synthesize data from diverse interactions between bacteria and eukaryote hosts. Five evolutionary transitions are investigated, including the origins of bacterial associations with eukaryotes, the origins and subsequent stable maintenance of bacterial mutualism with hosts, the capture of beneficial symbionts via the evolution of strict vertical transmission within host lineages, and the evolutionary breakdown of bacterial mutualism. Each of these transitions has occurred many times in the history of bacterial-eukaryote symbiosis. We investigate these evolutionary events across the bacterial domain and also among a focal set of well studied bacterial mutualist lineages. Subsequently, we generate a framework for examining evolutionary transitions in bacterial symbiosis and test hypotheses about the selective, ecological, and genomic forces that shape these events.
Careful attention should be given to comorbidities that could worsen bleeding and subsequent outcome.Because of their dependence on renal function for clearance, all of the DOACs have higher blood ...levels and longer half lives in patients with renal dysfunction.If idarucizumab is unavailable, then either PCC or activated prothrombin complex concentrate (aPCC) at 50 U/kg (max dose 4,000 U) may be used; these measurements are based on some limited animal, ex vivo, and human studies showing variable efficacy of either agent in improving hemostatic parameters in vitro (65-71).Since dabigatran is mostly not bound to proteins in the serum (>85%), hemodialysis has been suggested if the drug level is very high, especially in patients with impaired renal function (72,73).The timing of anticoagulation reinitiation has not been systematically studied and is highly variable, although a prospective study in which anticoagulation was restarted at the time of discharge in patients with a median length of stay of 5 days (including patients in whom no source of bleeding was found) demonstrated fewer TEs at 90 days with no increase in bleeding events; in AF patients, restarting warfarin >7 days after a bleed was associated with improved survival and decreased thromboembolism without an increased risk of recurrent GI bleeding (97,98)....in most cases of GI bleeding, the writing committee favors reinitiation of anticoagulation in patients with an indication for OAC once bleeding has been controlled (including patients in whom no discrete source of bleeding was identified).Approximately 20% of spontaneous intracranial hemorrhage is related to anticoagulation therapy....a cautious, individualized approach to restarting OAC after intracranial hemorrhage is warranted.
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