Testing Asymmetric-Information Asset Pricing Models

Theoretical asset pricing models routinely assume that investors have heterogeneous information. We provide direct evidence of the importance of information asymmetry for asset prices and investor demands using plausibly exogenous variation in the supply of information caused by the closure of 43 brokerage firms' research operations in the U.S. Consistent with predictions derived from a Grossman and Stiglitz-type model, share prices and uninformed investors' demands fall as information asymmetry increases. Cross-sectional tests support the comparative statics: Prices and uninformed demand experience larger declines, the more investors are uninformed, the larger and more variable is stock turnover, the more uncertain is the asset's payoff, and the noisier is the better-informed investors' signal. We show that at least part of the fall in prices is due to expected returns becoming more sensitive to liquidity risk. Our results imply that information asymmetry has a substantial effect on asset prices and that a primary channel linking asymmetry to prices is liquidity

Detection limits of organic compounds achievable with intense, short-pulse lasers

Many organic molecules have strong absorption bands which can be accessed by ultraviolet short pulse lasers to produce efficient ionization. This resonant multiphoton ionization scheme has already been exploited as an ionization source in time-of-flight mass spectrometers used for environmental trace analysis. In the present work we quantify the ultimate potential of this technique by measuring absolute ion yields produced from the interaction of 267 nm femtosecond laser pulses with the organic molecules indole and toluene, and gases Xe, N2 and O2. Using multiphoton ionization cross sections extracted from these results, we show that the laser pulse parameters required for real-time detection of aromatic molecules at concentrations of one part per trillion in air and a limit of detection of a few attomoles are achievable with presently available commercial laser systems. The potential applications for the analysis of human breath, blood and tissue samples are discussed

Raw and Count Data Comparability of Hip-Worn ActiGraph GT3X+ and Link Accelerometers

To enable inter- and intrastudy comparisons it is important to ascertain comparability among accelerometer models. Purpose: The purpose of this study was to compare raw and count data between hip-worn ActiGraph GT3X+ and GT9X Link accelerometers. Methods: Adults (n = 26 (n = 15 women); age, 49.1 T 20.0 yr) wore GT3X+ and Link accelerometers over the right hip for an 80-min protocol involving 12–21 sedentary, household, and ambulatory/exercise activities lasting 2–15 min each. For each accelerometer, mean and variance of the raw (60 Hz) data for each axis and vector magnitude (VM) were extracted in 30-s epochs. A machine learning model (Montoye 2015) was used to predict energy expenditure in METs from the raw data. Raw data were also processed into activity counts in 30-s epochs for each axis and VM, with Freedson 1998 and 2011 count-based regression models used to predictMETs. Time spent in sedentary, light, moderate, and vigorous intensities was derived from predicted METs from each model. Correlations were calculated to compare raw and count data between accelerometers, and percent agreement was used to compare epoch-by-epoch activity intensity. Results: For raw data, correlations for mean acceleration were 0.96 T 0.05, 0.89 T 0.16, 0.71 T 0.33, and 0.80 T 0.28, and those for variance were 0.98 T 0.02, 0.98 T 0.03, 0.91 T 0.06, and 1.00 T 0.00 in the X, Y, and Z axes and VM, respectively. For count data, corresponding correlations were 1.00 T 0.01, 0.98 T 0.02, 0.96 T 0.04, and 1.00 T 0.00, respectively. Freedson 1998 and 2011 count-based models had significantly higher percent agreement for activity intensity (95.1% T 5.6% and 95.5% T 4.0%) compared with theMontoye 2015 raw data model (61.5% T 27.6%; P G 0.001). Conclusions: Count data were more highly comparable than raw data between accelerometers. Data filtering and/or more robust raw data models are needed to improve raw data comparability between ActiGraph GT3X+ and Link accelerometers

Defining “elite” status in sport: from chaos to clarity

The past two decades have seen a rapid rise in attention towards talent identification, athlete development and skill acquisition. However, there are important limitations to the evidentiary foundations of this field of research. For instance, variability in describing the performance levels of individuals has made it challenging to draw inferences about inter- and intrapopulation differences. More specifically, recent reviews on high performers in sport have noted considerable variation in how terms such as “elite” are used. This may be particularly concerning for researchers in high-performance disciplines, since they regularly struggle with small sample sizes and rely on research synthesis approaches (i.e. meta-analyses and systematic reviews) to inform evidence-based decisions. In this discussion piece, we (a) highlight issues with the application of current terminology, (b) discuss challenges in conceptualizing an improved framework and (c) provide several recommendations for researchers and practitioners working in this area

Interventions to improve water quality for preventing diarrhoea

Background Diarrhoea is a major cause of death and disease, especially among young children in low-income countries. In these settings, many infectious agents associated with diarrhoea are spread through water contaminated with faeces. In remote and low-income settings, source-based water quality improvement includes providing protected groundwater (springs, wells, and bore holes), or harvested rainwater as an alternative to surface sources (rivers and lakes). Point-of-use water quality improvement interventions include boiling, chlorination, flocculation, filtration, or solar disinfection, mainly conducted at home. Objectives To assess the effectiveness of interventions to improve water quality for preventing diarrhoea. Search methods We searched the Cochrane Infectious Diseases Group Specialized Register (11 November 2014), CENTRAL (the Cochrane Library, 7 November 2014), MEDLINE (1966 to 10 November 2014), EMBASE (1974 to 10 November 2014), and LILACS (1982 to 7 November 2014). We also handsearched relevant conference proceedings, contacted researchers and organizations working in the field, and checked references from identified studies through 11 November 2014. Selection criteria Randomized controlled trials (RCTs), quasi-RCTs, and controlled before-and-after studies (CBA) comparing interventions aimed at improving the microbiological quality of drinking water with no intervention in children and adults. Data collection and analysis Two review authors independently assessed trial quality and extracted data. We used meta-analyses to estimate pooled measures of effect, where appropriate, and investigated potential sources of heterogeneity using subgroup analyses. We assessed the quality of evidence using the GRADE approach. Main results Forty-five cluster-RCTs, two quasi-RCTs, and eight CBA studies, including over 84,000 participants, met the inclusion criteria. Most included studies were conducted in low- or middle-income countries (LMICs) (50 studies) with unimproved water sources (30 studies) and unimproved or unclear sanitation (34 studies). The primary outcome in most studies was self-reported diarrhoea, which is at high risk of bias due to the lack of blinding in over 80% of the included studies. Source-based water quality improvements There is currently insufficient evidence to know if source-based improvements such as protected wells, communal tap stands, or chlorination/filtration of community sources consistently reduce diarrhoea (one cluster-RCT, five CBA studies, very low quality evidence). We found no studies evaluating reliable piped-in water supplies delivered to households. Point-of-use water quality interventions On average, distributing water disinfection products for use at the household level may reduce diarrhoea by around one quarter (Home chlorination products: RR 0.77, 95% CI 0.65 to 0.91; 14 trials, 30,746 participants, low quality evidence; flocculation and disinfection sachets: RR 0.69, 95% CI 0.58 to 0.82, four trials, 11,788 participants, moderate quality evidence). However, there was substantial heterogeneity in the size of the effect estimates between individual studies. Point-of-use filtration systems probably reduce diarrhoea by around a half (RR 0.48, 95% CI 0.38 to 0.59, 18 trials, 15,582 participants, moderate quality evidence). Important reductions in diarrhoea episodes were shown with ceramic filters, biosand systems and LifeStraw® filters; (Ceramic: RR 0.39, 95% CI 0.28 to 0.53; eight trials, 5763 participants, moderate quality evidence; Biosand: RR 0.47, 95% CI 0.39 to 0.57; four trials, 5504 participants, moderate quality evidence; LifeStraw®: RR 0.69, 95% CI 0.51 to 0.93; three trials, 3259 participants, low quality evidence). Plumbed in filters have only been evaluated in high-income settings (RR 0.81, 95% CI 0.71 to 0.94, three trials, 1056 participants, fixed effects model). In low-income settings, solar water disinfection (SODIS) by distribution of plastic bottles with instructions to leave filled bottles in direct sunlight for at least six hours before drinking probably reduces diarrhoea by around a third (RR 0.62, 95% CI 0.42 to 0.94; four trials, 3460 participants, moderate quality evidence). In subgroup analyses, larger effects were seen in trials with higher adherence, and trials that provided a safe storage container. In most cases, the reduction in diarrhoea shown in the studies was evident in settings with improved and unimproved water sources and sanitation. Authors' conclusions Interventions that address the microbial contamination of water at the point-of-use may be important interim measures to improve drinking water quality until homes can be reached with safe, reliable, piped-in water connections. The average estimates of effect for each individual point-of-use intervention generally show important effects. Comparisons between these estimates do not provide evidence of superiority of one intervention over another, as such comparisons are confounded by the study setting, design, and population. Further studies assessing the effects of household connections and chlorination at the point of delivery will help improve our knowledge base. As evidence suggests effectiveness improves with adherence, studies assessing programmatic approaches to optimising coverage and long-term utilization of these interventions among vulnerable populations could also help strategies to improve health outcomes

Comparing use and acceptability of menstrual cups and sanitary pads by schoolgirls in rural Western Kenya

Background: Girls in low and middle-income countries (LMIC) lack access to hygienic and affordable menstrual products. We explore Kenyan schoolgirls’ use and views of the cup compared to girls provided with disposable sanitary pads for a feasibility study.Methods: Schoolgirls aged 14-16 years, received a menstrual cup in 10 schools or 16 pads/month in another10 schools. All were trained by nurses on puberty, hand washing, and product use. They self-completed a net book survey at baseline and twice a term during a year follow-up. We examined their reported ease of insertion and removal, also comfort, soreness, and pain with product use. An aggregate ‘acceptability’ score was compiled for each product and girls’ socio-demographic and menstrual characteristics were compared.Results: 195 participants received cups and 255 pads. Mean age was 14.6 years, menarchial age was 13.6 years, with an average 3.8 days menses per month. Cup use was 39% in month 1, rising to 80% by month 12 (linear trend p<0.001). Pad use rose from 85% to 92% (linear trend p=0.15). Measures of cup acceptability demonstrated girls had initial problems using the cup but reported difficulties with insertion, removal and comfort reduced over time. Girls using pads reported fewer acceptability issues. At baseline, approximately a quarter of girls in the pad arm reported inserting pads intravaginally although this was significantly lower among girls with prior experience of pad use (aRR 0.62; 0.45-0.87).Conclusions: While a smaller proportion of girls provided with cups used them in the first months compared to girls given pads, reported use was similar by study-end, and early acceptability issues reduced over time. Girls in LMIC may successfully and comfortably use cups, but require instruction, support and some persistence

Language games and blurry terminology: Can clarity enhance athlete development?

This perspective focuses on the need for researchers and practitioners to carefully consider the clarity and consistency of their language in the context of athlete development. Evidence supporting a lack of congruency in the way certain terms and expressions are defined, understood, and operationalized continues to accumulate, highlighting the importance of this area for sport stakeholders and the potential looming crises. In systems that regularly rely on precision and accuracy, it will be critical that all involved in the co-creation of knowledge generation and application carefully consider terms that may further complicate athlete development practices. We highlight some potentially blurry terms and draw attention to potential avenues for future research

Language games and blurry terminology: Can clarity enhance athlete development?

This perspective focuses on the need for researchers and practitioners to carefully consider the clarity and consistency of their language in the context of athlete development. Evidence supporting a lack of congruency in the way certain terms and expressions are defined, understood, and operationalized continues to accumulate, highlighting the importance of this area for sport stakeholders and the potential looming crises. In systems that regularly rely on precision and accuracy, it will be critical that all involved in the co-creation of knowledge generation and application carefully consider terms that may further complicate athlete development practices. We highlight some potentially blurry terms and draw attention to potential avenues for future research