Advisor and Student Experiences of Summer Support for College-intending, Low-income high school graduates

Summer melt occurs when students who have been accepted to college and intend to enroll fail to matriculate in college in the fall semester after high school. A high rate of summer melt contributes to the lower postsecondary attainment rates of low-income students, in particular. This article presents qualitative findings from two interventions intended to reduce summer melt among low-income, urban high school graduates who had been accepted to college and indicated their intention to enroll. Results from student and counselor surveys, interviews, and focus groups point to a web of personal and contextual factors that collectively influence students' college preparation behaviors and provide insight into the areas of summer supports from which students like these can benefit. The data fit an ecological perspective, in which personal, institutional, societal, and temporal factors interact to affect students' behaviors and outcomes. A model of summer intervention shows that obstacles in completing college financing and informational tasks can lead college-intending students to re-open the question of where or whether to attend college in the fall after high school graduation. Given the pressure of concerns about how to actualize their offer of admission, students rarely engage in the anticipatory socialization activities that might help them make optimal transitions into college

Intrinsic noise profoundly alters the dynamics and steady state of morphogen-controlled bistable genetic switches

During tissue development, patterns of gene expression determine the spatial arrangement of cell types. In many cases, gradients of secreted signaling molecules - morphogens - guide this process. The continuous positional information provided by the gradient is converted into discrete cell types by the downstream transcriptional network that responds to the morphogen. A mechanism commonly used to implement a sharp transition between two adjacent cell fates is the genetic toggle switch, composed of cross-repressing transcriptional determinants. Previous analyses emphasize the steady state output of these mechanisms. Here, we explore the dynamics of the toggle switch and use exact numerical simulations of the kinetic reactions, the Chemical Langevin Equation, and Minimum Action Path theory to establish a framework for studying the effect of gene expression noise on patterning time and boundary position. This provides insight into the time scale, gene expression trajectories and directionality of stochastic switching events between cell states. Taking gene expression noise into account predicts that the final boundary position of a morphogen-induced toggle switch, although robust to changes in the details of the noise, is distinct from that of the deterministic system. Moreover, stochastic switching introduces differences in patterning time along the morphogen gradient that result in a patterning wave propagating away from the morphogen source. The velocity of this wave is influenced by noise; the wave sharpens and slows as it advances and may never reach steady state in a biologically relevant time. This could explain experimentally observed dynamics of pattern formation. Together the analysis reveals the importance of dynamical transients for understanding morphogen-driven transcriptional networks and indicates that gene expression noise can qualitatively alter developmental patterning

Reframing Systems Disasters With Three Perspectives of organizational Culture

This paper presents the major literature on systems disasters and how organizational culture is portrayed in this literature. The paper then outlines the three cultural perspectives used by Martin 2002 to describe organizational cultures: integration, differentiation, and fragmentation. The paper explores show these perspectives influence interpretations about the disasters described. The paper concludes that the effect of an organization’s culture on safety, reliability, and disasters can be fully understood only when all three perspectives are applied

Entrepreneur- Investor Negotiations: Investigating The Power Gap

Federal Securities Laws are designed to ensure that investors are provided with sufficient information to make an informed investment. These Laws presume that investors are relatively naive and powerless compared to the relatively sophisticated and powerful sellers of securities. In the new venture arena, however, it is often the case that sellers, the entrepreneurs, are relatively naive and powerless compared to the investors, who tend to be expert in venture finance. This paper explores these heretofore unexamined power imbalances and presents attributes of the entrepreneurs and their resources that may affect entrepreneurs\u27 ability to negotiate with venture capitalists

Cooperative success in epithelial public goods games

Cancer cells obtain mutations which rely on the production of diffusible growth factors to confer a fitness benefit. These mutations can be considered cooperative, and studied as public goods games within the framework of evolutionary game theory. The population structure, benefit function and update rule all influence the evolutionary success of cooperators. We model the evolution of cooperation in epithelial cells using the Voronoi tessellation model. Unlike traditional evolutionary graph theory, this allows us to implement global updating, for which birth and death events are spatially decoupled. We compare, for a sigmoid benefit function, the conditions for cooperation to be favoured and/or beneficial for well mixed and structured populations. We find that when population structure is combined with global updating, cooperation is more successful than if there were local updating or the population were well-mixed. Interestingly, the qualitative behaviour for the well-mixed population and the Voronoi tessellation model is remarkably similar, but the latter case requires significantly lower incentives to ensure cooperation.Comment: 29 Pages, 13 Figure

The role of evolutionary game theory in spatial and non-spatial models of the survival of cooperation in cancer: a review

Evolutionary game theory (EGT) is a branch of mathematics which considers populations of individuals interacting with each other to receive pay-offs. An individual’s pay-off is dependent on the strategy of its opponent(s) as well as on its own, and the higher its pay-off, the higher its reproductive fitness. Its offspring generally inherit its interaction strategy, subject to random mutation. Over time, the composition of the population shifts as different strategies spread or are driven extinct. In the last 25 years there has been a flood of interest in applying EGT to cancer modelling, with the aim of explaining how cancerous mutations spread through healthy tissue and how intercellular cooperation persists in tumour-cell populations. This review traces this body of work from theoretical analyses of well-mixed infinite populations through to more realistic spatial models of the development of cooperation between epithelial cells. We also consider work in which EGT has been used to make experimental predictions about the evolution of cancer, and discuss work that remains to be done before EGT can make large-scale contributions to clinical treatment and patient outcomes

Aid, growth, and real exchange rate dynamics

Devarajan, Go, Page, Robinson, and Thierfelder argued that if aid is about the future and recipients are able to plan consumption and investment decisions optimally over time, then the potential problem of an aid-induced appreciation of the real exchange rate (Dutch disease) does not occur. In their paper,"Aid, Growth and Real Exchange Rate Dynamics,"this key result is derived without requiring extreme assumptions or additional productivity story. The economic framework is a standard neoclassical growth model, based on the familiar Salter-Swan characterization of an open economy, with full dynamic savings and investment decisions. It does require that the model is fully dynamic in both savings and investment decisions. An important assumption is that aid should be predictable for intertemporal smoothing to take place. If aid volatility forces recipients to be constrained and myopic, Dutch disease problems become an issue.Economic Theory&Research,Debt Markets,Currencies and Exchange Rates,Emerging Markets,

Minimum Action Path theory reveals the details of stochastic biochemical transitions out of oscillatory cellular states

Cell state determination is the outcome of intrinsically stochastic biochemical reactions. Tran- sitions between such states are studied as noise-driven escape problems in the chemical species space. Escape can occur via multiple possible multidimensional paths, with probabilities depending non-locally on the noise. Here we characterize the escape from an oscillatory biochemical state by minimizing the Freidlin-Wentzell action, deriving from it the stochastic spiral exit path from the limit cycle. We also use the minimized action to infer the escape time probability density function