Playing the Game: The Impact of No Pass/No Play Sanctions on High School Athletes, A Youth Development Approach

In the original “No Pass/No Play” legislation (enacted by Texas State Legislature in 1985), students had to pass all classes with at least a 70% average to participate in sports or extracurricular activities. Since then, no pass/no play regulations have been enacted across the nation with little evidence regarding their effectiveness. Questions necessarily arise: What effects do sanctions have on athletes’ social, emotional, and physical development? Specifically, how do imposed no pass/no play sanctions affect the youth development of high school athletes? Using the framework of youth development, this study aimed to describe the impacts of no pass/no play on sanctioned youths. It was grounded in Giesela Konopka’s (1973) authoritative theories of the essential characteristics of positive and negative youth development, including her nine tenets describing requirements for healthy adolescent youth development. This study used a qualitative, interview-based, grounded theory methodology. Data from 15 cases were categorized into factors that facilitated or impeded youth development. Within these two groups, participant responses were categorized by Konopka’s tenets as reported most often (High), in the midrange (Moderate), and rarely (Minimal). Analysis yielded a combined 387 comments (157 that facilitate and 230 that impede). The results indicated how sanctions impacted the participants in terms of their youth development as athletes. Those comments indicating that positive youth development had been facilitated were outnumbered by those indicating it had been impeded by nearly 30%. Since the “highly impedes” and “moderately impedes” categories represented the majority of all the data, these findings suggest that no pass/no play sanctions may negatively impact the youth development of athletes more often than not. Less commonly, participants identified how the sanctions may have facilitated their youth development. This study concluded that stakeholders implementing no pass/no play policies should develop sanctions that focus particularly on activities that propel youths toward citizenship, self-reflection, and accountability. Further research may alter the course of sanction implementation or, minimally, provide better tools to facilitate, rather than hinder, athletes’ positive youth development

Fluctuations of fitness distributions and the rate of Muller's ratchet

The accumulation of deleterious mutations is driven by rare fluctuations which lead to the loss of all mutation free individuals, a process known as Muller's ratchet. Even though Muller's ratchet is a paradigmatic process in population genetics, a quantitative understanding of its rate is still lacking. The difficulty lies in the nontrivial nature of fluctuations in the fitness distribution which control the rate of extinction of the fittest genotype. We address this problem using the simple but classic model of mutation selection balance with deleterious mutations all having the same effect on fitness. We show analytically how fluctuations among the fittest individuals propagate to individuals of lower fitness and have a dramatically amplified effects on the bulk of the population at a later time. If a reduction in the size of the fittest class reduces the mean fitness only after a delay, selection opposing this reduction is also delayed. This delayed restoring force speeds up Muller's ratchet. We show how the delayed response can be accounted for using a path integral formulation of the stochastic dynamics and provide an expression for the rate of the ratchet that is accurate across a broad range of parameters.Comment: Genetics 201

Colorectal cancer: advances in prevention and early detection

Colorectal cancer (CRC) is currently the fourth leading cause of cancer death worldwide. While mortality rates are in decline in most westernised countries, global estimates predict that CRC incidence rates and the overall number of CRC-related deaths are set to rise by 77% and 80%, respectively, by 2030. The development of CRC is multifactorial, and risk factors include various lifestyle, genetic, and environmental factors. It has been estimated that at least half of CRC cases could be prevented by a reduction in known modifiable lifestyle-related risk factors. Further reductions in CRC incidence and mortality can be achieved through screening, but the uptake of screening varies across different sectors of the population. This special issue comprises articles highlighting issues in the prevention, early diagnosis, and treatment of CRC

Evolution of the chemical composition of Sn thin films heated during x-ray photoelectron spectroscopy

High-vacuum XPS have been used to analyse the surface modification of a 3 nm-thick Sn thin film on Si (100) before and after annealing up to 450 °C. Increasing the XPS stage temperature led to a reduction in the amount of surface Sn and increasing amounts of O and Si. High-resolution XPS scans revealed the presence of mostly pure Sn and SnO2 for the as-deposited Sn thin film. Increasing the XPS stage temperature to > 232 °C led to the conversion of SnO2 to SnO and an enhancing pure Sn signal. The Si2p and SiO2 peaks become prominent at temperatures > 350 °C, which in combination with scanning electron microscope images, signals the dewetting of the Sn film and subsequent exposure of the underlying Si (100) substrate. XPS depth profiles revealed the presence of a pure Sn metallic core encapsulated by a Sn-oxide shell. Electron microscope images shows a densely packed particulate surface features for the as-deposited Sn thin film. However, these particulate regions increase in size and are more isolated at XPS stage temperatures > 350 °C.National Metrology Institute of South Africa and the National Research Foundation (GUN: 93212, 92520, 103621)

Temporal trends in mode, site and stage of presentation with the introduction of colorectal cancer screening: a decade of experience from the West of Scotland

background:  Population colorectal cancer screening programmes have been introduced to reduce cancer-specific mortality through the detection of early-stage disease. The present study aimed to examine the impact of screening introduction in the West of Scotland. methods:  Data on all patients with a diagnosis of colorectal cancer between January 2003 and December 2012 were extracted from a prospectively maintained regional audit database. Changes in mode, site and stage of presentation before, during and after screening introduction were examined. results:  In a population of 2.4 million, over a 10-year period, 14 487 incident cases of colorectal cancer were noted. Of these, 7827 (54%) were males and 7727 (53%) were socioeconomically deprived. In the postscreening era, 18% were diagnosed via the screening programme. There was a reduction in both emergency presentation (20% prescreening vs 13% postscreening, P0.001) and the proportion of rectal cancers (34% prescreening vs 31% pos-screening, P0.001) over the timeframe. Within non-metastatic disease, an increase in the proportion of stage I tumours at diagnosis was noted (17% prescreening vs 28% postscreening, P0.001). conclusions:  Within non-metastatic disease, a shift towards earlier stage at diagnosis has accompanied the introduction of a national screening programme. Such a change should lead to improved outcomes in patients with colorectal cancer

The potential for climate-driven bathymetric range shifts: sustained temperature and pressure exposures on a marine ectotherm, Palaemonetes varians

Range shifts are of great importance as a response for species facing climate change. In the light of current ocean-surface warming, many studies have focused on the capacity of marine ectotherms to shift their ranges latitudinally. Bathymetric range shifts offer an important alternative, and may be the sole option for species already at high latitudes or those within enclosed seas; yet relevant data are scant. Hydrostatic pressure (HP) and temperature have wide ranging effects on physiology, importantly acting in synergy thermodynamically, and therefore represent key environmental constraints to bathymetric migration. We present data on transcriptional regulation in a shallow-water marine crustacean (Palaemonetes varians) at atmospheric and high HP following 168-h exposures at three temperatures across the organisms' thermal scope, to establish the potential physiological limit to bathymetric migration by neritic fauna. We observe changes in gene expression indicative of cellular macromolecular damage, disturbances in metabolic pathways and a lack of acclimation after prolonged exposure to high HP. Importantly, these effects are ameliorated (less deleterious) at higher temperatures, and exacerbated at lower temperatures. These data, alongside previously published behavioural and heat-shock analyses, have important implications for our understanding of the potential for climate-driven bathymetric range shift

In-depth analysis of the Naming Game dynamics: the homogeneous mixing case

Language emergence and evolution has recently gained growing attention through multi-agent models and mathematical frameworks to study their behavior. Here we investigate further the Naming Game, a model able to account for the emergence of a shared vocabulary of form-meaning associations through social/cultural learning. Due to the simplicity of both the structure of the agents and their interaction rules, the dynamics of this model can be analyzed in great detail using numerical simulations and analytical arguments. This paper first reviews some existing results and then presents a new overall understanding.Comment: 30 pages, 19 figures (few in reduced definition). In press in IJMP

Calibration of optimal execution of financial transactions in the presence of transient market impact

Trading large volumes of a financial asset in order driven markets requires the use of algorithmic execution dividing the volume in many transactions in order to minimize costs due to market impact. A proper design of an optimal execution strategy strongly depends on a careful modeling of market impact, i.e. how the price reacts to trades. In this paper we consider a recently introduced market impact model (Bouchaud et al., 2004), which has the property of describing both the volume and the temporal dependence of price change due to trading. We show how this model can be used to describe price impact also in aggregated trade time or in real time. We then solve analytically and calibrate with real data the optimal execution problem both for risk neutral and for risk averse investors and we derive an efficient frontier of optimal execution. When we include spread costs the problem must be solved numerically and we show that the introduction of such costs regularizes the solution.Comment: 31 pages, 8 figure