Causation in Occupational Disease: Balancing Epidemiology, Law and Manufacturer Conduct

Drs. Lynch & Henefin examine evolution of disease causation theory and its impact on public health, as well as how these relate to the courtroom admissibility of expert opinion evidence

‘You have to find your slant, your groove:’ one physical education teacher's efforts to employ transformative pedagogy

Background: Teaching for social good and inequity has been presented as needed in sport pedagogy research. However, very little is known how transformative pedagogical practices that teach for social good are implemented and sustained at the elementary level. Purpose: This digital ethnographic study sought to describe one elementary school physical education (PE) teacher's attempt to employ transformative pedagogy (TP). Method: Cochran-Smith's [1998. “Teaching for Social Change: Toward a Grounded Theory of Teacher Education.” In The International Handbook of Educational Change, edited by A. Hargreaves, A. Lieberman, M. Fullan, and D. Hopkins, 916–952. Netherlands: Kluwer Academic Publishers, 2004. Walking the Road: Race, Diversity, and Social Justice in Teacher Education. New York: Teachers College Press] pedagogical principles for social justice education (SJE) drove our data collection and analysis. Seven qualitative methods were employed to collect data about Harry's pedagogies, organizational structures, and the content he taught. These were formal and informal interviews, conversations, short films, document collection, social media accounts, and an electronic journal. Data were analyzed using both inductive and deductive methods [Patton 2015. Qualitative Research and Evaluation Methods. 4th ed. Thousand Oaks: Sage]. Findings: Harry's TP and the factors that facilitated and limited his practice were uncovered within five main themes: (a) creating communities of learners through restorative practice principles, (b) building on what students bring to school with them for a democratic curriculum, (c) teaching skills, bridging gaps, and the affective component, (d), working with communities in-between social justice illiteracy, and (e) utilizing diverse forms of assessment. Conclusion: We confirmed that there is no best way to teach social justice through PE and that TP must be individual to the teacher. In addition, this study highlighted methods and pedagogies by which teachers could engage in TP. Finally, the study's findings implied how teacher educators might go about working with both preservice and inservice PE teachers with the goal that they focus on facilitating social justice through their pedagogical approach

Aerosol studies in mid-latitude coastal environments in Australia

The results of the evaluation of several inversion procedures that were used to select one which provides the most accurate atmospheric extinction profiles for small aerosol extinction coefficients (that often predominate in the maritime airmass) are presented. Height profiles of atmospheric extinction calculated by a two component atmospheric solution to the LIDAR equation will be compared with corresponding in-situ extinction profiles based on the size distribution profiles obtained in Western Australia. Values of the aerosol backscatter to extinction ratio obtained from multi-angle LIDAR measurements will be used in this solution

Adaptive evolution of molecular phenotypes

Molecular phenotypes link genomic information with organismic functions, fitness, and evolution. Quantitative traits are complex phenotypes that depend on multiple genomic loci. In this paper, we study the adaptive evolution of a quantitative trait under time-dependent selection, which arises from environmental changes or through fitness interactions with other co-evolving phenotypes. We analyze a model of trait evolution under mutations and genetic drift in a single-peak fitness seascape. The fitness peak performs a constrained random walk in the trait amplitude, which determines the time-dependent trait optimum in a given population. We derive analytical expressions for the distribution of the time-dependent trait divergence between populations and of the trait diversity within populations. Based on this solution, we develop a method to infer adaptive evolution of quantitative traits. Specifically, we show that the ratio of the average trait divergence and the diversity is a universal function of evolutionary time, which predicts the stabilizing strength and the driving rate of the fitness seascape. From an information-theoretic point of view, this function measures the macro-evolutionary entropy in a population ensemble, which determines the predictability of the evolutionary process. Our solution also quantifies two key characteristics of adapting populations: the cumulative fitness flux, which measures the total amount of adaptation, and the adaptive load, which is the fitness cost due to a population's lag behind the fitness peak.Comment: Figures are not optimally displayed in Firefo

The statistical mechanics of a polygenic characterunder stabilizing selection, mutation and drift

By exploiting an analogy between population genetics and statistical mechanics, we study the evolution of a polygenic trait under stabilizing selection, mutation, and genetic drift. This requires us to track only four macroscopic variables, instead of the distribution of all the allele frequencies that influence the trait. These macroscopic variables are the expectations of: the trait mean and its square, the genetic variance, and of a measure of heterozygosity, and are derived from a generating function that is in turn derived by maximizing an entropy measure. These four macroscopics are enough to accurately describe the dynamics of the trait mean and of its genetic variance (and in principle of any other quantity). Unlike previous approaches that were based on an infinite series of moments or cumulants, which had to be truncated arbitrarily, our calculations provide a well-defined approximation procedure. We apply the framework to abrupt and gradual changes in the optimum, as well as to changes in the strength of stabilizing selection. Our approximations are surprisingly accurate, even for systems with as few as 5 loci. We find that when the effects of drift are included, the expected genetic variance is hardly altered by directional selection, even though it fluctuates in any particular instance. We also find hysteresis, showing that even after averaging over the microscopic variables, the macroscopic trajectories retain a memory of the underlying genetic states.Comment: 35 pages, 8 figure

Two-Bit Messages are Sufficient to Implement Atomic Read/Write Registers in Crash-prone Systems

Atomic registers are certainly the most basic objects of computing science. Their implementation on top of an n-process asynchronous message-passing system has received a lot of attention. It has been shown that t \textless{} n/2 (where t is the maximal number of processes that may crash) is a necessary and sufficient requirement to build an atomic register on top of a crash-prone asynchronous message-passing system. Considering such a context, this paper presents an algorithm which implements a single-writer multi-reader atomic register with four message types only, and where no message needs to carry control information in addition to its type. Hence, two bits are sufficient to capture all the control information carried by all the implementation messages. Moreover, the messages of two types need to carry a data value while the messages of the two other types carry no value at all. As far as we know, this algorithm is the first with such an optimality property on the size of control information carried by messages. It is also particularly efficient from a time complexity point of view

The separate neural control of hand movements and contact forces

To manipulate an object, we must simultaneously control the contact forces exerted on the object and the movements of our hand. Two alternative views for manipulation have been proposed: one in which motions and contact forces are represented and controlled by separate neural processes, and one in which motions and forces are controlled jointly, by a single process. To evaluate these alternatives, we designed three tasks in which subjects maintained a specified contact force while their hand was moved by a robotic manipulandum. The prescribed contact force and hand motions were selected in each task to induce the subject to attain one of three goals: (1) exerting a regulated contact force, (2) tracking the motion of the manipulandum, and (3) attaining both force and motion goals concurrently. By comparing subjects' performances in these three tasks, we found that behavior was captured by the summed actions of two independent control systems: one applying the desired force, and the other guiding the hand along the predicted path of the manipulandum. Furthermore, the application of transcranial magnetic stimulation impulses to the posterior parietal cortex selectively disrupted the control of motion but did not affect the regulation of static contact force. Together, these findings are consistent with the view that manipulation of objects is performed by independent brain control of hand motions and interaction forces