437 research outputs found

    The world-sheet description of A and B branes revisited

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    We give a manifest supersymmetric description of A and B branes on Kahler manifolds using a completely local N=2 superspace formulation of the world-sheet nonlinear sigma-model in the presence of a boundary. In particular, we show that an N=2 superspace description of type A boundaries is possible, at least when the background is Kahler. This leads to an elegant and concrete setting for studying coisotropic A branes. Here, apgesan important role is played by the boundary potential, whose precise physical meaning remains to be fully understood. Duality transformations relating A and B branes in the presence of isometries are studied as well.Comment: LaTeX, 32 page

    Reconstructed Intentions in Collaborative Problem Solving Dialogues

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    We provide evidence that speech act recognition, is 1) difficult for humans to do and 2) likely to misidentify proposals involving reconstructed intentions. We examine the reliability of coding for speech acts in collaborative dialogues and we present an approach for recognizing reconstructed proposals using domain context and other more easily recognized features. 1 Introduction Speech act recognition plays a prominent role in dialogue understanding, in traditional approaches that infer a plan using plan construction operators [PA80], [LA90], [LC91, LC92], and in more recent techniques relying on statistical correlations or finite state machines [RM95, QDL + 97]. Both approaches recognize surface speech acts, using surface form and information provided by the discourse context and the discourse operators, or by a finite state approximation of the planning information. These approaches assume that it is (relatively) simple to recognize speech acts, and that speech acts are a requi..

    A synopsis of the Joint Environment and Human Health Programme in the UK

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    The Joint Environment and Human Health (E&HH) Programme has explored how both man-made and natural changes to the environment can influence human health. Scientists have tackled the complicated mix of environmental, social and economic factors that influence health, particularly focusing on naturally occurring toxins, man-made pollutants, nanoparticles and pathogens to see

    Archaeogenetic evidence of ancient Nubian barley evolution from six to two-row indicates local adaptation

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    Background Archaeobotanical samples of barley (Hordeum vulgare L.) found at Qasr Ibrim display a two-row phenotype that is unique to the region of archaeological sites upriver of the first cataract of the Nile, characterised by the development of distinctive lateral bracts. The phenotype occurs throughout all strata at Qasr Ibrim, which range in age from 3000 to a few hundred years. Methodology and Findings We extracted ancient DNA from barley samples from the entire range of occupancy of the site, and studied the Vrs1 gene responsible for row number in extant barley. Surprisingly, we found a discord between the genotype and phenotype in all samples; all the barley had a genotype consistent with the six-row condition. These results indicate a six-row ancestry for the Qasr Ibrim barley, followed by a reassertion of the two-row condition. Modelling demonstrates that this sequence of evolutionary events requires a strong selection pressure. Conclusions The two-row phenotype at Qasr Ibrim is caused by a different mechanism to that in extant barley. The strength of selection required for this mechanism to prevail indicates that the barley became locally adapted in the region in response to a local selection pressure. The consistency of the genotype/phenotype discord over time supports a scenario of adoption of this barley type by successive cultures, rather than the importation of new barley varieties associated with individual cultures

    Implementing a Pressure Ulcer Bundle

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    Background: A quality improvement DNP project in a rural southern hospital was implemented to improve hospital-acquired pressure ulcers by implementing an evidence-based pressure ulcer prevention policy and education. Framework: The Evidence-Based Practice framework utilized in the project\u27s development, implementation, and evaluation was the John Hopkins Evidence-based Practice Model. Local Problem: The hospital had no pressure ulcer bundle in place. Design: Quality improvement project utilizing the plan-do-study-act cycle. Methods: An educational presentation on pressure ulcers and the steps to implement a bundle. A pre-and post-test using Pieper\u27s Pressure Ulcer Knowledge Test, modified from Agency for Healthcare Research and Quality (AHRQ) website. Data Analysis: A pre-and post-test analysis, percentage of nurses on the medical surgical floor that attended the training, the number of Hospital Acquired Pressure Ulcers (HAPU) pre-and post-implementation, and the number of times the bundle was implemented post-educational sessions. Results: There was a 100% completion of the educational sessions by the wound care nurse before implementing the HAPU bundle. Participants scored higher during the post-test (M=87.524, SD= 6.534), a statistically significant mean increase of 4.891, 95% CI [1.621, 8.160], t(17) = 3.156, p= .006. The wound care nurse observed every chart. Information gathered from the review demonstrated 77.05% compliance with the implementation of the HAPU bundle. Conclusion: There was high compliance with the nurses attending the educational sessions and implementing the HAPU bundle. Implementation of preventative measures included in this bundle is considered best practice in the fight against HAPUs. The HAPU bundle have become part of hospital policy

    Environmental Exposure and Health Effects Associated with Malathion Toxicity

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    Malathion (O,O-dimethyl-S-1,2-bis ethoxy carbonyl ethyl phosphorodithionate) is a non-systemic, wide-spectrum pesticide. It is widely used throughout the world for agricultural, residential, and public health purposes, mainly to enhance food production and to provide protection from disease vectors. Malathion preference over other organophosphate pesticides relates to its low persistence in the environment as it is highly susceptible to hydrolysis, photolysis, and biodegradation. However, numerous malathion poisoning incidents including acute and chronic cases have been reported among pesticide workers and small children through accidental exposure. Malathion toxicity is compounded by its reactive metabolites and also depends upon the product purity, route of exposure, nutritional status, and gender of exposed individuals. Its metabolic oxidation in mammals, insects, and plants leads to the formation of malaoxon which appears to be several times more acutely toxic and represents the primary cause of malathion’s toxicity. Depending on the level of exposure, several signs and symptoms of toxicity including numbness, tingling sensation, headache, dizziness, difficulty breathing, weakness, irritation of skin, exacerbation of asthma, abdominal cramps, and death have been reported. Similar to other organophosphate pesticides, malathion exerts it toxic action by binding to acetylcholinesterase enzyme and inhibiting its activity, leading to accumulation of acetylcholine in synaptic junctions, which in turn results in overstimulation of cholinergic, muscarinic, and nicotinic receptors, and subsequent induction of adverse biologic effects. This chapter provides an update and analysis of the production and use, environmental occurrence, molecular mechanisms of toxicity, genotoxicity and carcinogenicity, and adverse human health effects associated with malathion exposure

    Long-Term Mortality Outcomes According to the Frequency of Right Ventricular Pacing in Veterans

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    Background. Right ventricular pacing (RVP) has been associated with adverse outcomes, including heart failure and death. Minimizing RVP has been proposed as a therapeutic goal for a variety of pacing devices and indications. Objective. Quantify survival according to frequency of RVP in veterans with pacemakers. Methods. We analyzed electrograms from transtelephonic monitoring of veterans implanted with pacemakers between 1995 and 2005 followed by the Eastern Pacemaker Surveillance Center. We compared all cause mortality and time to death between patients with less than 20% and more than 80% RVP. Results. Analysis was limited to the 7198 patients with at least six trans-telephonic monitoring records (mean = 21). Average follow-up was 5.3 years. Average age at pacemaker implant was significantly lower among veterans with <20% RVP (67 years versus 72 years; P < .0001). An equal proportion of deaths during follow-up were noted for each group: 126/565 patients (22%) with <20% RVP and 1113/4968 patients (22%) with >80% RVP. However, average post-implant survival was 4.3 years with <20% RVP versus 4.7 years with >80% RVP (P < .0001). Conclusions. Greater frequency (>80%) of RVP was not associated with higher mortality in this population of veterans. Those veterans utilizing <20% RVP had a shortened adjusted survival rate (P = .0016)

    Perceptions of Support Among Older African American Cancer Survivors

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    To explore the perceived social support needs among older adult African American cancer survivors

    Decaying Dark Matter can explain the electron/positron excesses

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    PAMELA and ATIC recently reported excesses in e+ e- cosmic rays. Since the interpretation in terms of DM annihilations was found to be not easily compatible with constraints from photon observations, we consider the DM decay hypothesis and find that it can explain the e+ e- excesses compatibly with all constraints, and can be tested by dedicated HESS observations of the Galactic Ridge. ATIC data indicate a DM mass of about 2 TeV: this mass naturally implies the observed DM abundance relative to ordinary matter if DM is a quasi-stable composite particle with a baryon-like matter asymmetry. Technicolor naturally yields these type of candidates.Comment: 20 pages, 7 figure
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