AN ECOLOGIC STUDY OF ACCESS TO ACUTE STROKE CARE, MORTALITY AND ITS CORRELATES IN THE STROKE BELT

Importance: Stroke is leading cause of death in the United States, but quick access to treatment has been shown to result in better outcomes and improved mortality. Among the many barriers to access, geographic proximity to hospitals certified in stroke care may also play a role. Objectives: To calculate county-level measures of accessibility to certified stroke hospitals using GIS, and to examine its relationship with county stroke mortality while controlling for other county-level potential confounders. Methods: Ecologic study using county mortality rates and census data to recreate stroke death counts for use in traditional, and a geographically weighted Poisson regression model for the eleven states of the Stroke Belt (N=1033). Results: Counties farther than 60km from a stroke certified hospital displayed a 2.8% increase in stroke mortality rates while controlling for a county’s percentage of diagnosed diabetics, leisure-time physical inactivity, population aged 65 and over, black or African American population, Medicare Part D beneficiaries non-adherent to their blood pressure medication regiment, county smoking prevalence, annual PM2.5 concentrations, distressed community index score, and state’s decision to expand Medicaid. Some covariates displayed relationships with mortality that were non-stationary and varied over the study area. Conclusions: Thoughtful consideration should be made in studies of geographic access to the methods used for estimation, along with the possibility of a non-linear and nonstationary relationship with study outcomes

Eye Tracking as a Control Interface for Tele-Operation During a Visual Search Task

This study examined the utility of eye-tracking as a control method during tele-operation in a simulated task environment. Operators used a simulator to tele-operate a search robot using three different control methods: fully manual, hybrid, and eye-only. Using Endsely’s (1995a) three level SA model and a natural interface (e.g., eye-tracking) as a more user-centered approach to tele-operation, the study measured objective, electroencephalogram, and subjective (NASA-TLX) measures to reflect both workload and situation awareness during tele-operation. The results showed a significant reduction in mental workload, as reflected by EEG measures. However a significant effect was found where the operators’ perceived mental workload scores, as reflected by the TLX, significantly increased while using the natural interface. The difference in perceived mental workload was also mirrored by a post hoc analysis where frustration scores, also reflected by the TLX, supported the initial findings of the differences in perceived mental workload scores between the three conditions. The results of this study can be explained by both incomplete mental models of motor movements and differences in affordances offered by the different control conditions. Additional considerations for system designers and future research are also discussed

Engineering stochasticity in gene expression

Stochastic fluctuations (noise) in gene expression can cause members of otherwise genetically identical populations to display drastically different phenotypes. An understanding of the sources of noise and the strategies cells employ to function reliably despite noise is proving to be increasingly important in describing the behavior of natural organisms and will be essential for the engineering of synthetic biological systems. Here we describe the design of synthetic constructs, termed ribosome competing RNAs (rcRNAs), as a means to rationally perturb noise in cellular gene expression. We find that noise in gene expression increases in a manner proportional to the ability of an rcRNA to compete for the cellular ribosome pool. We then demonstrate that operons significantly buffer noise between coexpressed genes in a natural cellular background and can even reduce the level of rcRNA enhanced noise. These results demonstrate that synthetic genetic constructs can significantly affect the noise profile of a living cell and, importantly, that operons are a facile genetic strategy for buffering against noise

Technical and marketing support systems for successful small and medium-size enterprises in four countries

Studies of successful and medium-size enterprises (SMEs) and their marketing and technical support systems were undertaken for Colombia, Indonesia, Japan, and the Republic of Korea. Three to four subsectors were examined in each country. The sample worldwide amounted to 445 firms. Mechanisms to support export marketing varied across countries and subsectors. How they varied depended greatly on whether SMEs operated within well-developed private networks. When market penetration begins, transaction costs are high and collective marketing support can be important. As markets"thicken,"initiatives by foreign buyers become more important. Generally the most effective collective marketing support was of the kind that can be provided more effectively by decentralized organizations - such as industry associations or local governments and chambers of commerce (support firms'participation in trade fairs, for example) - than by central government institutions. Private mechanisms were more important than collective mechanisms for helping firms improve their technological capability. Demand for collective mechanisms tended to be greater when technological requirements of production were complex or when the endowments of private technological networks in certain countries or industries were weak. Broad-based collective technical support facilitates the emergence of an information-rich environment for firms, and may be worth pursuing in many settings. Examples of such support include: 1) sponsoring courses in specialized topics; 2) facilitating the use of expert consultants (either directly, by making a consultant available to a broad array of firms, or indirectly, by providing financial support for the use of consultants); and 3) promoting information-sharing among firms. Countries that already have strong broad-based collective support and that are moving into technologically more advanced activities might consider"high-intensity"support, but should proceed with caution.Microfinance,Small and Medium Size Enterprises,Small Scale Enterprise,Markets and Market Access,Water Conservation,Microfinance,Private Participation in Infrastructure,Small Scale Enterprise,Access to Markets,Markets and Market Access

Synaptic regulation of the hypothalamic–pituitary–adrenal axis and its modulation by glucocorticoids and stress

Dysregulation of the hypothalamic–pituitary–adrenal (HPA) axis has been implicated in a range of affective and stress-related disorders. The regulatory systems that control HPA activity are subject to modulation by environmental influences, and stressful life events or circumstances can promote subsequent HPA dysregulation. The brain is a major regulator of the HPA axis, and stress-induced plasticity of the neural circuitry involved in HPA regulation might constitute an etiological link between stress and the development of HPA dysregulation. This review focuses on the synaptic regulation of neuroendocrine corticotropin-releasing hormone (CRH) neurons of the hypothalamic paraventricular nucleus, which are the cells through which the brain predominantly exerts its influence on the HPA axis. CRH neuronal activity is largely orchestrated by three neurotransmitters: GABA, glutamate, and norepinephrine. We discuss our current understanding of the neural circuitry through which these neurotransmitters regulate CRH cell activity, as well as the plastic changes in this circuitry induced by acute and chronic stress and the resultant changes in HPA function

Optimization of the leak conductance in the squid giant axon

We report on a theoretical study showing that the leak conductance density, \GL, in the squid giant axon appears to be optimal for the action potential firing frequency. More precisely, the standard assumption that the leak current is composed of chloride ions leads to the result that the experimental value for \GL is very close to the optimal value in the Hodgkin-Huxley model which minimizes the absolute refractory period of the action potential, thereby maximizing the maximum firing frequency under stimulation by sharp, brief input current spikes to one end of the axon. The measured value of \GL also appears to be close to optimal for the frequency of repetitive firing caused by a constant current input to one end of the axon, especially when temperature variations are taken into account. If, by contrast, the leak current is assumed to be composed of separate voltage-independent sodium and potassium currents, then these optimizations are not observed.Comment: 9 pages; 9 figures; accepted for publication in Physical Review

Deoxyribozymes that recode sequence information

Allosteric nucleic acid ligases have been used previously to transform analyte-binding into the formation of oligonucleotide templates that can be amplified and detected. We have engineered binary deoxyribozyme ligases whose two components are brought together by bridging oligonucleotide effectors. The engineered ligases can ‘read’ one sequence and then ‘write’ (by ligation) a separate, distinct sequence, which can in turn be uniquely amplified. The binary deoxyribozymes show great specificity, can discriminate against a small number of mutations in the effector, and can read and recode DNA information with high fidelity even in the presence of excess obscuring genomic DNA. In addition, the binary deoxyribozymes can read non-natural nucleotides and write natural sequence information. The binary deoxyribozyme ligases could potentially be used in a variety of applications, including the detection of single nucleotide polymorphisms in genomic DNA or the identification of short nucleic acids such as microRNAs

Engineering Flow States with Localized Forcing in a Thin, Marangoni-Driven Inclined Film

Numerical simulations of lubrication models provide clues for experimentalists about the development of wave structures in thin liquid films. We analyze numerical simulations of a lubrication model for an inclined thin liquid film modified by Marangoni forces due to a thermal gradient and additional localized forcing heating the substrate. Numerical results can be explained through connections to theory for hyperbolic conservation laws predicting wave fronts from Marangoni-driven thin films without forcing. We demonstrate how a variety of forcing profiles, such as Gaussian, rectangular, and triangular, affect the formation of downstream transient structures, including an N wave not commonly discussed in the context of thin films. Simulations employing a controlled approximation of a compressive-undercompressive wave pair demonstrate possibilities for applications of localized forcing as microfluidic valve. In the simulations, localized forcing provides a control parameter that can be used to determine mass flux and film profiles