How (not) to raise money

We show that standard winner-pay auctions are inept fund-raising mechanisms because of the positive externality bidders forgo if they top another's high bid. Revenues are suppressed as a result and remain finite even when bidders value a dollar donated the same as a dollar kept. This problem does not occur in lotteries and all-pay auctions, where bidders pay irrespective of whether they win. We introduce a general class of all-pay auctions, rank their revenues, and illustrate how they dominate lotteries and winner-pay formats. The optimal fund-raising mechanism is an all-pay auction augmented with an entry fee and reserve price

Variable geographic distribution of Blastocystis subtypes and its potential implications.

Blastocystis is a common intestinal micro-eukaryote found in both humans and non-human hosts and known to be genetically very diverse. It has been divided into numerous subtypes (STs), nine of which have been identified in humans to date. Surveys of ST prevalence have started to emerge over the past few years but to date no data are available for any African country except Egypt and Tanzania. In this study, we determined the prevalence of Blastocystis STs in populations from Libya, Liberia and Nigeria, as well as expanding the dataset available for the UK. A total of 356 Blastocystis STs were identified in this study, 271 from the UK, 38 from Libya, 25 from Liberia and 22 from Nigeria. SSU rRNA gene sequences revealed the presence of eight of the nine STs known from humans but at varying frequencies between countries. ST1 was the most common ST in Libya and Nigeria whereas ST3 showed the highest frequency in the other two countries, as indeed is the case in most populations around the world. ST4 was absent in Libya and ST2 in Nigeria, while no ST5, ST6, ST8 or ST9 infections were detected in any of the three African populations. The picture emerging from this and other surveys suggests that there is significant variation in ST prevalence between populations. Some of the possible reasons for and implications of this diversity are discussed

Tractions and stress fibers control cell shape and rearrangements in collective cell migration

Key to collective cell migration is the ability of cells to rearrange their position with respect to their neighbors. Recent theory and experiments demonstrated that cellular rearrangements are facilitated by cell shape, with cells having more elongated shapes and greater perimeters more easily sliding past their neighbors within the cell layer. Though it is thought that cell perimeter is controlled primarily by cortical tension and adhesion at each cell's periphery, experimental testing of this hypothesis has produced conflicting results. Here we studied collective cell migration in an epithelial monolayer by measuring forces, cell perimeters, and motion, and found all three to decrease with either increased cell density or inhibition of cell contraction. In contrast to previous understanding, the data suggest that cell shape and rearrangements are controlled not by cortical tension or adhesion at the cell periphery but rather by the stress fibers that produce tractions at the cell-substrate interface. This finding is confirmed by an experiment showing that increasing tractions reverses the effect of density on cell shape and rearrangements. Our study therefore reduces the focus on the cell periphery by establishing cell-substrate traction as a major physical factor controlling cell shape and motion in collective cell migration.Comment: 39 pages, 6 figure

Two-dimensional electronics and optoelectronics: Present and future

Since the successful isolation of graphene a little over a decade ago, a wide variety of two-dimensional (2D) layered materials have been studied. They cover a broad spectrum of electronic properties, including metals, semimetals, semiconductors, and insulators. Many of these 2D materials have demonstrated promising potential for electronic and optoelectronic applications

Probiotics and the Prevention of Clostridioides difficile: A Review of Existing Systematic Reviews

Clostridioides difficile is the leading cause of infectious diarrhea (Vernaya et al., 2017). Probiotics have been proposed to provide a protective benefit against Clostridioides difficile infection (CDI). The objective of this literature review was to examine the research evidence pertaining to the use of probiotics for the prevention of CDI in individuals receiving antibiotic therapy. A systematic literature review of studies published between 2015 and 2019 was performed. Five databases were searched, which yielded 10 systematic reviews that met strict inclusion criteria. Overall, the majority of evidence indicated that probiotics versus no treatment, placebo, or usual care have the potential to reduce CDIs in patients on antibiotic therapy by 50% or greater. There was no increased risk of adverse events among those taking probiotics. Benefit is greater when the background risk of CDIs was over 5%. The optimal probiotic dose, duration, species, and formulation is not known, although multispecies or Lactobacillus probiotics may be more effective in addition to taking probiotics within one to two days of starting antibiotics. These findings are limited to patients that are not immune compromised, pregnant, elderly, critically ill, have not had recent surgery, and do not have prosthetic heart valves. Overall, due to the magnitude of the effect of probiotics and their favorable safety profile, providers should consider including a shared decision-making conversation with their patients taking antibiotics regarding their personal risk versus benefit option to take probiotics concurrently

A Minority Within a Minority? Identity and Sexual Health in Black and Minority Ethnic Men Who Have Sex With Men in the United Kingdom

Identity refers to the individual’s self-construal. It is characterized by multiple elements, such as sexuality, ethnicity, and religion, and not all identity elements are simultaneously salient (Jaspal & Breakwell, 2014). For instance, the same person might self-identify principally as gay at a Gay Pride March, as Muslim during Ramadan, as Pakistani during a cricket match, and as British when abroad. Social context is key to identity expression. Black and minority ethnic (BME) men who have sex with men (MSM) in the United Kingdom have multiple, often stig- matized, identity elements. Many face intersecting social stressors (e.g., racism and homophobia) that can increase the risk of poor sexual health. Many straddle the boundaries of seemingly incompatible identities, such as ethnicity and sexuality. In this commentary, we present a clinical case study, and relevant theory and research, to illustrate the practical importance of identity for effective sexual health care in this diverse population