118 research outputs found

    Towards an open database of assessment material for STEM subjects: requirements and recommendations from early field trials

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    If appropriately implemented, open databases of instruction material may help teaching and learning by providing content for teaching activities, scaffolding, and self-assessment. The paper presents the current results of the development and implementation of a database that is expressly built for promoting exchange of questions and exercises, together with the associated solutions among teachers for STEM subjects. Besides presenting and motivating the initiative (together with reporting its current status), the manuscript lists a series of lessons that have been learned while executing the project - including the need for proper management of authorship and version control of the uploaded material. Moreover, the manuscript describes which features any open database of instruction material should implement to aid improved usability, together with a series of nontrivial theoretical and practical problems for future scientific investigations (e.g., developing taxonomies for indexing the difficulty levels of the instruction material uploaded in the database that do not suffer from the subjective interpretability associated with the existing taxonomies)

    Large area silicon sheet by EFG

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    Progress in a program to produce high speed, thin, wide silicon sheets for fabricating 10% efficient solar cells is reported. An EFG ribbon growth system was used to perform growth rate and ribbon thickness experiments. A new, wide ribbon growth system was developed. A theoretical study of stresses in ribbons was also conducted. The EFG ribbons were observed to exhibit a characteristic defect structure which is orientation dependent in the early stages of growth

    Review: Khayelitsha 2001 - 2011: 10 years of primary care HIV and TB programmes

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    Tuberculosis (TB) and HIV care in Khayelitsha, and in South Africa as a whole, has overcome numerous obstacles in the past three decades. This article highlights what has been achieved in Khayelitsha, describes the key clinical programme and policy changes that have supported universal coverage for HIV and TB care over the last 10 years, and outlines the challenges for the next decade

    The Transcriptome of SH-SY5Y at Single-Cell Resolution: A CITE-Seq Data Analysis Workflow

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    Cellular Indexing of Transcriptomes and Epitopes by Sequencing (CITE-seq) is a recently established multimodal single cell analysis technique combining the immunophenotyping capabilities of antibody labeling and cell sorting with the resolution of single-cell RNA sequencing (scRNA-seq). By simply adding a 12-bp nucleotide barcode to antibodies (cell hashing), CITE-seq can be used to sequence antibody-bound tags alongside the cellular mRNA, thus reducing costs of scRNA-seq by performing it at the same time on multiple barcoded samples in a single run. Here, we illustrate an ideal CITE-seq data analysis workflow by characterizing the transcriptome of SH-SY5Y neuroblastoma cell line, a widely used model to study neuronal function and differentiation. We obtained transcriptomes from a total of 2879 single cells, measuring an average of 1600 genes/cell. Along with standard scRNA-seq data handling procedures, such as quality checks and cell filtering procedures, we performed exploratory analyses to identify most stable genes to be possibly used as reference housekeeping genes in qPCR experiments. We also illustrate how to use some popular R packages to investigate cell heterogeneity in scRNA-seq data, namely Seurat, Monocle, and slalom. Both the CITE-seq dataset and the code used to analyze it are freely shared and fully reusable for future research

    Comparison of Kaposi Sarcoma risk in human immunodeficiency virus-positive adults across 5 continents: A multiregional multicohort study

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    Background: We compared Kaposi sarcoma (KS) risk in adults who started antiretroviral therapy (ART) across the Asia-Pacific, South Africa, Europe, Latin, and North America. Methods: We included cohort data of human immunodeficiency virus (HIV)-positive adults who started ART after 1995 within the framework of 2 large collaborations of observational HIV cohorts. We present incidence rates and adjusted hazard ratios (aHRs). Results: We included 208 140 patients from 57 countries. Over a period of 1 066 572 person-years, 2046 KS cases were diagnosed. KS incidence rates per 100 000 person-years were 52 in the Asia-Pacific and ranged between 180 and 280 in the other regions. KS risk was 5 times higher in South African women (aHR, 4.56; 95% confidence intervals [CI], 2.73-7.62) than in their European counterparts, and 2 times higher in South African men (2.21; 1.34-3.63). In Europe, Latin, and North America KS risk was 6 times higher in men who have sex with men (aHR, 5.95; 95% CI, 5.09-6.96) than in women. Comparing patients with current CD4 cell counts 65700 cells/\u3bcL with those whose counts were <50 cells/\u3bcL, the KS risk was halved in South Africa (aHR, 0.53; 95% CI, .17-1.63) but reduced by 6595% in other regions. Conclusions. Despite important ART-related declines in KS incidence, men and women in South Africa and men who have sex with men remain at increased KS risk, likely due to high human herpesvirus 8 coinfection rates. Early ART initiation and maintenance of high CD4 cell counts are essential to further reducing KS incidence worldwide, but additional measures might be needed, especially in Southern Africa
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