The Ursinus Weekly, May 26, 1958

MSGA plans tentative 1958 customs program • Junior advisory committee named • Big-little sister committee asks for applicants • Many U.C. seniors accepted at post-grad schools • Last Y commission meetings are held to plan for next Fall semester • R.G. Dunlop to speak at June 9th graduation • Ursinus\u27 Rowe gets scholarship • Editorial: Customs • Letters to the editor • Are fraternities? • Cindermen whip Mules, Dutchmen; Take three meets • Netmen finish season; Defeat Elizabethtown, 6-3 • Bears win 10th game; Lose final tilt by 8-1 • Girls\u27 tennis team beats Penn; Finish undefeated • Beta Sigma Lambda beats Sigma Rho Lambda in 9th • New Library accessionshttps://digitalcommons.ursinus.edu/weekly/1409/thumbnail.jp

Identification of competing ultrafast all-optical switching mechanisms in Si woodpile photonic crystals

We present a systematic study of ultrafast all-optical switching of Si photonic band gap woodpile crystals using broadband tunable nondegenerate pump-probe spectroscopy. At pump-probe coincidence, we investigate the behavior the differential reflectivity at the blue edge of the stopband for a wide range of pump- and probe frequencies. Both dispersive and absorptive features are observed from the probe spectra at coincidence. As the pump frequency is tuned through half the electronic bandgap of Si, the magnitude of both these features increases. For the first time we unambiguously identify this dispersive effect with the electronic Kerr effect in photonic crystals, and attribute the the absorptive features to nondegenerate two photon absorption. The dispersive and absorptive nonlinear coefficients are extracted, and are found to agree well with literature. Finally, we propose a nondegenerate figure of merit (NFOM), which defines the quality of switching for all nondegenerate optical switching processes.Comment: Accepted by JOSA

Contract cheating: a survey of Australian university students

Recent Australian media scandals suggest that university students are increasingly outsourcing their assessments to third parties – a behaviour known as ‘contract cheating’. This paper reports on findings from a large survey of students from eight Australian universities (n = 14,086) which sought to explore students’ experiences with and attitudes towards contract cheating, and the contextual factors that may influence this behaviour. A spectrum of seven outsourcing behaviours were investigated, and three significant variables were found to be associated with contract cheating: dissatisfaction with the teaching and learning environment, a perception that there are ‘lots of opportunities to cheat’, and speaking a Language Other than English (LOTE) at home. To minimise contract cheating, our evidence suggests that universities need to support the development of teaching and learning environments which nurture strong student–teacher relationships, reduce opportunities to cheat through curriculum and assessment design, and address the well-recognised language and learning needs of LOTE students.No Full Tex

Quantifiable plasma tenofovir among South African women using daily oral pre-exposure prophylaxis during the ECHO trial

Access to data from the ECHO study may be requested through submission of a research concept to ude.wu@crci. The concept must include the research question, data requested, analytic methods, and steps taken to ensure ethical use of the data. Access will be granted if the concept is evaluated to have scientific merit and if sufficient data protections are in place. As of the time of publication, data access applications are in process with the governing institutional review boards of the ECHO study to make deidentified data publicly available.BACKGROUND : HIV endpoint–driven clinical trials provide oral pre-exposure prophylaxis (PrEP) as HIV prevention standard of care. We evaluated quantifiable plasma tenofovir among South African women who used oral PrEP during the Evidence for Contraceptive Options and HIV Outcomes (ECHO) Trial. METHODS : ECHO, a randomized trial conducted in 4 African countries between 2015 and 2018, assessed HIV incidence among HIV-uninfected women, aged 16–35 years, randomized to 1 of 3 contraceptives. Oral PrEP was offered onsite as part of the HIV prevention package at the South African trial sites. We measured tenofovir in plasma samples collected at the final trial visit among women reporting ongoing PrEP use. We used bivariate and multivariate logistical regression to assess demographic and sexual risk factors associated with plasma tenofovir quantification. RESULTS : Of 260 women included, 52% were ≤24 years and 22% had Chlamydia trachomatis at enrollment. At PrEP initiation, 68% reported inconsistent/nonuse of condoms. The median duration of PrEP use was 90 days (IQR: 83–104). Tenofovir was quantified in 36% (n = 94) of samples. Women >24 years had twice the odds of having tenofovir quantified vs younger women (OR = 2.12; 95% confidence interval = 1.27 to 3.56). Women who reported inconsistent/nonuse of condoms had lower odds of tenofovir quantification (age-adjusted OR = 0.47; 95% confidence interval = 0.26 to 0.83). CONCLUSIONS : Over a third of women initiating PrEP and reporting ongoing use at the final trial visit had evidence of recent drug exposure. Clinical trials may serve as an entry point for PrEP initiation among women at substantial risk for HIV infection with referral to local facilities for ongoing access at trial end. CLINICAL TRIAL NUMBER : NCT02550067.The Bill & Melinda Gates Foundation, the American people through the United States Agency for International Development, the Swedish International Development Cooperation Agency, the South Africa Medical Research Council, and the United Nations Population Fund. Contraceptive supplies were donated by the Government of South Africa and US Agency for International Development.http://journals.lww.com/jaidshj2023Family MedicineMedical Microbiolog

High levels of pretreatment HIV-1 drug resistance mutations among South African women who acquired HIV during a prospective study

Access to data from the ECHO Study may be requested through submission of a research concept to [email protected]. The concept must include the research question, data requested, analytic methods, and steps taken to ensure ethical use of the data. Access will be granted if the concept is evaluated to have scientific merit and if sufficient data protections are in place. As of the time of publication, data access applications are in process with the governing institutional review boards of the ECHO Study to make de-identified data publicly available.BACKGROUND : Pretreatment HIV drug resistance (PDR) undermines individual treatment success and threatens the achievement of UNAIDS 95-95-95 targets. In many African countries, limited data are available on PDR as detection of recent HIV infection is uncommon and access to resistance testing is limited. We describe the prevalence of PDR among South African women with recent HIV infection from the Evidence for Contraceptive Options and HIV Outcomes (ECHO) Trial. METHODS : HIV-uninfected, sexually active women, aged 18–35 years, and seeking contraception were enrolled in the ECHO Trial at sites in South Africa, from 2015 to 2018. HIV testing was done at trial entry and repeated quarterly. We tested stored plasma samples collected at HIV diagnosis from women who seroconverted during follow-up and had a viral load >1000 copies/mL for antiretroviral resistant mutations using a validated laboratory-developed population genotyping assay, which sequences the full protease and reverse transcriptase regions. Mutation profiles were determined using the Stanford Drug Resistance Database. RESULTS : We sequenced 275 samples. The median age was 23 years, and majority (98.9%, n = 272) were infected with HIV-1 subtype C. The prevalence of surveillance drug resistance mutations (SDRMs) was 13.5% (n = 37). Nonnucleoside reverse transcriptase inhibitor (NNRTI) mutations were found in 12.4% of women (n = 34). Few women had NRTI (1.8%, n = 5) and protease inhibitor (1.1%, n = 3) mutations. Five women had multiple NRTI and NNRTI SDRMs. CONCLUSIONS : The high levels of PDR, particularly to NNRTIs, strongly support the recent change to the South African national HIV treatment guidelines to transition to a first-line drug regimen that excludes NNRTIs.The Bill & Melinda Gates Foundation, the American people through the United States Agency for International Development, the Swedish International Development Cooperation Agency, the South Africa Medical Research Council, and the United Nations Population Fund.http://journals.lww.com/jaidshj2023Family MedicineMedical Microbiolog

A Predictive Model of Intein Insertion Site for Use in the Engineering of Molecular Switches

Inteins are intervening protein domains with self-splicing ability that can be used as molecular switches to control activity of their host protein. Successfully engineering an intein into a host protein requires identifying an insertion site that permits intein insertion and splicing while allowing for proper folding of the mature protein post-splicing. By analyzing sequence and structure based properties of native intein insertion sites we have identified four features that showed significant correlation with the location of the intein insertion sites, and therefore may be useful in predicting insertion sites in other proteins that provide native-like intein function. Three of these properties, the distance to the active site and dimer interface site, the SVM score of the splice site cassette, and the sequence conservation of the site showed statistically significant correlation and strong predictive power, with area under the curve (AUC) values of 0.79, 0.76, and 0.73 respectively, while the distance to secondary structure/loop junction showed significance but with less predictive power (AUC of 0.54). In a case study of 20 insertion sites in the XynB xylanase, two features of native insertion sites showed correlation with the splice sites and demonstrated predictive value in selecting non-native splice sites. Structural modeling of intein insertions at two sites highlighted the role that the insertion site location could play on the ability of the intein to modulate activity of the host protein. These findings can be used to enrich the selection of insertion sites capable of supporting intein splicing and hosting an intein switch

A hierarchical Bayesian model for understanding the spatiotemporal dynamics of the intestinal epithelium

Our work addresses two key challenges, one biological and one methodological. First, we aim to understand how proliferation and cell migration rates in the intestinal epithelium are related under healthy, damaged (Ara-C treated) and recovering conditions, and how these relations can be used to identify mechanisms of repair and regeneration. We analyse new data, presented in more detail in a companion paper, in which BrdU/IdU cell-labelling experiments were performed under these respective conditions. Second, in considering how to more rigorously process these data and interpret them using mathematical models, we use a probabilistic, hierarchical approach. This provides a best-practice approach for systematically modelling and understanding the uncertainties that can otherwise undermine the generation of reliable conclusions-uncertainties in experimental measurement and treatment, difficult-to-compare mathematical models of underlying mechanisms, and unknown or unobserved parameters. Both spatially discrete and continuous mechanistic models are considered and related via hierarchical conditional probability assumptions. We perform model checks on both in-sample and out-of-sample datasets and use them to show how to test possible model improvements and assess the robustness of our conclusions. We conclude, for the present set of experiments, that a primarily proliferation-driven model suffices to predict labelled cell dynamics over most time-scales

Long-standing nonkin relationships of older adults in the Netherlands and the United States

The main research questions of this study were (1) How long have adults in the Netherlands and the United States known members of their nonkin networks? (2) What are the predictors of long-standing nonkin relationships? and (3) Which predictors are recognizable in both societies? The data came from the NESTOR-LSN survey (3,229 adults aged 55 to 89 years in the Netherlands) and from the Northern California Community Study (n = 1,050, with 225 respondents aged 55 to 91 years in the United States). In both countries, the duration of nonkin relationships was related to the absence of network-disturbing variables (e.g., the number of years since the last move), network-sustaining variables (e.g., distance to nonkin), and other network properties (e.g., homogeneity). Nationally based differences were also observed (e.g., having a car was related to stable relationships only in the United States, and the special integrative functions of exclusive friendships were elicited only in Europe)