805 research outputs found
Insecticide Sensitivity of Native Chloride and Sodium Channels in a Mosquito Cell Line
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
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Finding the Magnetic Center of a Quadrupole to High Resolution
In a companion pro, collposal it is proposed to align quadrupoles of a transport line to within transverse tolerances of 5 to 10 micrometers. Such a proposal is meaningful only if the effective magnetic center of such lenses can in fact be repeatably located with respect to some external mechanical tooling to comparable accuracy. It is the purpose of this note to describe some new methods and procedures that will accomplish this aim. It will be shown that these methods are capable of yielding greater sensitivity than the more traditional methods used in the past. The notion of the ''nodal'' point is exploited
One in four die from acute infectious illness in an emergency department in Eastern Cape Province, South Africa
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 30Â 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
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
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
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
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
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
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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