805 research outputs found

    Insecticide Sensitivity of Native Chloride and Sodium Channels in a Mosquito Cell Line

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    The aim of this study was to investigate the utility of cultured Anopheles gambiae Sua1B cells for insecticide screening applications without genetic engineering or other treatments. Sua1B cells were exposed to the known insecticidal compounds lindane and DIDS, which inhibited cell growth at micromolar concentrations. In patch clamp studies, DIDS produced partial inhibition (69%) of chloride current amplitudes, and an IC50 of 5.1 ÎĽM was determined for Sua1B cells. A sub-set of chloride currents showed no response to DIDS; however, inhibition (64%) of these currents was achieved using a low chloride saline solution, confirming their identity as chloride channels. In contrast, lindane increased chloride current amplitude (EC50 = 116 nM), which was reversed when cells were bathed in calcium-free extracellular solution. Voltage-sensitive chloride channels were also inhibited by the presence of fenvalerate, a type 2 pyrethroid, but not significantly blocked by type 1 allethrin, an effect not previously shown in insects. Although no evidence of fast inward currents typical of sodium channels was observed, studies with fenvalerate in combination with veratridine, a sodium channel activator, revealed complete inhibition of cell growth that was best fit by a two-site binding model. The high potency effect was completely inhibited in the presence of tetrodotoxin, a specific sodium channel blocker, suggesting the presence of some type of sodium channel. Thus, Sua1B cells express native insect ion channels with potential utility for insecticide screening

    One in four die from acute infectious illness in an emergency department in Eastern Cape Province, South Africa

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    Background. Despite the breadth of data supporting evidence-based practice for sepsis care in high-resource settings, there are relatively few data to guide the management of sepsis in low-resource settings, particularly in areas where HIV and tuberculosis (TB) are prevalent. Furthermore, few studies had broadened sepsis parameters to include all patients with acute infectious illness or followed patients up after hospital discharge. Understanding the epidemiology and outcomes of acute infections in a local context is the critical first step to developing locally informed targeted management strategies.Objectives. To quantify and describe the incidence of and risk factors for mortality in a cohort of patients with undifferentiated acute infectious illnesses who presented to an emergency department (ED) in the Eastern Cape region of South Africa (SA).Methods. In this prospective cohort study, patients with suspected acute infectious illness were enrolled at a district casualty ward in Mthatha, SA, between 1 July and 1 September 2017. Demographic data, interventions, diagnostic studies and disposition were prospectively collected during the initial encounter and during the hospital stay. Follow-up was conducted both in hospital and via phone interviews 30 days after the index visit.Results. A total of 301 patients presented to the ED with acute infectious illness during the study period, of whom 54.8% had complete 30-day follow-up. Of the study population, only 5.7% had a complete set of vital signs (heart rate, respiratory rate, blood pressure and temperature) documented. Of the cohort, 51.8% had HIV and 32.9% active or treated TB; 25.2% of patients died within 30 days. Accounting for medical history, diagnosis and ED interventions, risk of mortality was independently associated with age (odds ratio (OR) 1.03; 95% confidence interval (CI) 1.00 - 1.06), HIV-positive status (OR 4.10; 95% CI 1.44 - 11.67) and Quick Sequential (Sepsis-Related) Organ Failure Assessment (qSOFA) score (OR 1.90; 95% CI 1.14 - 3.19) in an adjusted model. No ED interventions were protective for mortality, with intravenous fluid administration associated with increased 30-day mortality in this cohort (OR 3.65; 95% CI 1.38 - 9.62).Conclusions. Among adults with suspected acute infectious illness in Mthatha, SA, 30-day mortality was concerningly high. Mortality was highest in patients with concomitant HIV infection. In particular, vital sign assessment to identify possible sepsis in this cohort is crucial, as it affects mortality to a meaningful extent, yet is often unavailable. Future research is needed on the management of sepsis in low-resource settings, particularly in HIV-positive individuals

    Optimal topological simplification of discrete functions on surfaces

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    We solve the problem of minimizing the number of critical points among all functions on a surface within a prescribed distance {\delta} from a given input function. The result is achieved by establishing a connection between discrete Morse theory and persistent homology. Our method completely removes homological noise with persistence less than 2{\delta}, constructively proving the tightness of a lower bound on the number of critical points given by the stability theorem of persistent homology in dimension two for any input function. We also show that an optimal solution can be computed in linear time after persistence pairs have been computed.Comment: 27 pages, 8 figure

    Scalar Field Quantum Inequalities in Static Spacetimes

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    We discuss quantum inequalities for minimally coupled scalar fields in static spacetimes. These are inequalities which place limits on the magnitude and duration of negative energy densities. We derive a general expression for the quantum inequality for a static observer in terms of a Euclidean two-point function. In a short sampling time limit, the quantum inequality can be written as the flat space form plus subdominant correction terms dependent upon the geometric properties of the spacetime. This supports the use of flat space quantum inequalities to constrain negative energy effects in curved spacetime. Using the exact Euclidean two-point function method, we develop the quantum inequalities for perfectly reflecting planar mirrors in flat spacetime. We then look at the quantum inequalities in static de~Sitter spacetime, Rindler spacetime and two- and four-dimensional black holes. In the case of a four-dimensional Schwarzschild black hole, explicit forms of the inequality are found for static observers near the horizon and at large distances. It is show that there is a quantum averaged weak energy condition (QAWEC), which states that the energy density averaged over the entire worldline of a static observer is bounded below by the vacuum energy of the spacetime. In particular, for an observer at a fixed radial distance away from a black hole, the QAWEC says that the averaged energy density can never be less than the Boulware vacuum energy density.Comment: 27 pages, 2 Encapsulated Postscript figures, uses epsf.tex, typeset in RevTe

    B806: Performance Evaluations of Potato Clones and Varieties in the Northeastern States 1984

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    Cooperative potato clone and variety trials were conducted at 32 locations to determine field performance of selected clones and varieties grown under soil, climatic, and cultural management common to the potato growing areas of 12 cooperating states and the Province of New Brunswick, Canada. A few locations also evaluated storage and processing behavior of selected clones and varieties. These tests are contributions to Regional Project NE107 entitled, Breeding and Evaluation of New Potato Clones for the Northeast. The primary objective of this project is to determine clone performance and stability over a wide range of soil, climate, and cultural conditions.https://digitalcommons.library.umaine.edu/aes_bulletin/1117/thumbnail.jp

    Stochastic Gravity: A Primer with Applications

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    Stochastic semiclassical gravity of the 90's is a theory naturally evolved from semiclassical gravity of the 70's and 80's. It improves on the semiclassical Einstein equation with source given by the expectation value of the stress-energy tensor of quantum matter fields in curved spacetimes by incorporating an additional source due to their fluctuations. In stochastic semiclassical gravity the main object of interest is the noise kernel, the vacuum expectation value of the (operator-valued) stress-energy bi-tensor, and the centerpiece is the (stochastic) Einstein-Langevin equation. We describe this new theory via two approaches: the axiomatic and the functional. The axiomatic approach is useful to see the structure of the theory from the framework of semiclassical gravity. The functional approach uses the Feynman-Vernon influence functional and the Schwinger-Keldysh close-time-path effective action methods which are convenient for computations. It also brings out the open systems concepts and the statistical and stochastic contents of the theory such as dissipation, fluctuations, noise and decoherence. We then describe the application of stochastic gravity to the backreaction problems in cosmology and black hole physics. Intended as a first introduction to this subject, this article places more emphasis on pedagogy than completeness.Comment: 46 pages Latex. Intended as a review in {\it Classical and Quantum Gravity

    School-Based Programs to Reduce Bullying and Victimization

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    School bullying has serious short-term and long-term effects on children’s physical and mental health. Various anti-bullying programs have been implemented world wide and, more rarely, evaluated. Previous narrative reviews, summarizing the work done on bullying prevention, as well as previous meta-analyses of anti-bullying programs, are limited. The definition of school bullying includes several key elements: physical, verbal, or psychological attack or intimidation that is intended to cause fear, distress, or harm to the victim; an imbalance of power (psychological or physical), with a more powerful child (or children) oppressing less powerful ones; and repeated incidents between the same children over a prolonged period. School bullying can occur in school or on the way to or from school. It is not bullying when two persons of the same strength (physical, psychological, or verbal) victimize each other. This report presents a systematic review and meta-analysis of the effectiveness of programs designed to reduce school bullying perpetration and victimization (i.e. being bullied). The authors indicate the pitfalls of previous reviews and explain in detail how the present systematic review and meta-analysis addresses the gaps in the existing literature on bullying prevention

    Using the Mystery Motivator to Improve Child Bedtime Compliance

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    Child bedtime problems are commonly reported by parents. A number of behavioral techniques, including extinction of tantrum behaviors, reinforcement of compliant bedtime, and implementation of consistent bedtime routines have been successful in improving bedtime compliance. The present study examined the effects of the Mystery Motivator (MM), a behavioral contract designed to remediate bedtime problems by delivering random reinforcement. Emphasis was placed on the optimal use of clinical intervention by enlisting parents as primary change agents in the home setting. Three adults and their four children, aged 3-5 years, participated. Three of the four children showed substantial changes in both time out of bed and bedtime noncompliance between baseline and treatment phases. A fourth child showed less improvement. Parent participants demonstrated understanding of the materials and successfully implemented the home program. Both parent and child participants rated the Mystery Motivator reinforcement system as an acceptable intervention
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