1,178 research outputs found

    Using Physical Chemistry To Differentiate Nicotinic from Cholinergic Agonists at the Nicotinic Acetylcholine Receptor

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    The binding of three distinct agonists - acetylcholine (ACh), nicotine, and epibatidine - to the nicotinic acetylcholine receptor has been probed using unnatural amino acid mutagenesis. ACh makes a cation−π interaction with Trp α149, while nicotine employs a hydrogen bond to a backbone carbonyl in the same region of the agonist binding site. The nicotine analogue epibatidine achieves its high potency by taking advantage of both the cation−π interaction and the backbone hydrogen bond. A simple structural model that considers only possible interactions with Trp α149 suggests that a novel aromatic C - H···O=C hydrogen bond further augments the binding of epibatidine. These studies illustrate the subtleties and complexities of the interactions between drugs and membrane receptors and establish a paradigm for obtaining detailed structural information

    Dihydrolevoglucosenone (Cyreneâ„¢) as a bio-renewable solvent for Cu(0)wire-mediated reversible deactivation radical polymerization (RDRP) without external deoxygenation

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    Biorenewable dihydrolevoglucosenone (Cyreneâ„¢) is used as an effective dipolar aprotic solvent for Cu(0) wire-mediated RDRP of various monomers without external deoxygenation being applied

    Assessing Commitment and Reporting Fidelity to a Text Message-Based Participatory Surveillance in Rural Western Uganda.

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    Syndromic surveillance, the collection of symptom data from individuals prior to or in the absence of diagnosis, is used throughout the developed world to provide rapid indications of outbreaks and unusual patterns of disease. However, the low cost of syndromic surveillance also makes it highly attractive for the developing world. We present a case study of electronic participatory syndromic surveillance, using participant-mobile phones in a rural region of Western Uganda, which has a high infectious disease burden, and frequent local and regional outbreaks. Our platform uses text messages to encode a suite of symptoms, their associated durations, and household disease burden, and we explore the ability of participants to correctly encode their symptoms, with an average of 75.2% of symptom reports correctly formatted between the second and 11th reporting timeslots. Concomitantly we identify divisions between participants able to rapidly adjust to this unusually participatory style of data collection, and those few for whom the study proved more challenging. We then perform analyses of the resulting syndromic time series, examining the clustering of symptoms by time and household to identify patterns such as a tendency towards the within-household sharing of respiratory illness.National Institute of Health (Grant ID: TW009237)This is the final version of the article. It first appeared from the Public Library of Science via http://dx.doi.org/10.1371/journal.pone.015597

    WTEC panel report on European nuclear instrumentation and controls

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    Control and instrumentation systems might be called the 'brain' and 'senses' of a nuclear power plant. As such they become the key elements in the integrated operation of these plants. Recent developments in digital equipment have allowed a dramatic change in the design of these instrument and control (I&C) systems. New designs are evolving with cathode ray tube (CRT)-based control rooms, more automation, and better logical information for the human operators. As these new advanced systems are developed, various decisions must be made about the degree of automation and the human-to-machine interface. Different stages of the development of control automation and of advanced digital systems can be found in various countries. The purpose of this technology assessment is to make a comparative evaluation of the control and instrumentation systems that are being used for commercial nuclear power plants in Europe and the United States. This study is limited to pressurized water reactors (PWR's). Part of the evaluation includes comparisons with a previous similar study assessing Japanese technology

    Explicitly correlated trial wave functions in Quantum Monte Carlo calculations of excited states of Be and Be-

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    We present a new form of explicitly correlated wave function whose parameters are mainly linear, to circumvent the problem of the optimization of a large number of non-linear parameters usually encountered with basis sets of explicitly correlated wave functions. With this trial wave function we succeeded in minimizing the energy instead of the variance of the local energy, as is more common in quantum Monte Carlo methods. We applied this wave function to the calculation of the energies of Be 3P (1s22p2) and Be- 4So (1s22p3) by variational and diffusion Monte Carlo methods. The results compare favorably with those obtained by different types of explicitly correlated trial wave functions already described in the literature. The energies obtained are improved with respect to the best variational ones found in literature, and within one standard deviation from the estimated non-relativistic limitsComment: 19 pages, no figures, submitted to J. Phys.

    Proceedings, Pot Chrysanthemum School, 1971

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    Space management / Robert W. Langhans -- Soils / D. C. Kiplinger -- Nutrition / George L. Staby -- Temperature and photoperiod / Joseph W. Love -- Automated short day control -- R. A. Aldrich -- Growth regulators / James B. Shanks -- Programming for insect-free pot mums / Richard K. Lindquist -- Programming for disease-free pot mums / Lester P. Nichols and Paul E. Nelson -- Where you go wrong / Harry K. Tayam

    Multi-instrument observations of the effects of a solar wind pressure pulse on the high latitude ionosphere : a detailed case study of a geomagnetic sudden impulse

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    Funding: ARF was supported by an STFC studentship, Science Foundation Ireland Grant 18/FRL/6199, and an Irish Research Council Government of Ireland Postdoctoral Fellowship GOIPD/2022/782. ML, TKY, and SEM acknowledge support from the Science and Technology Facilities Council, UKRI, grant no. ST/W00089X/1. JAC is supported by Royal Society grant DHF\R1\211068. HKS was supported by an STFC studentship. TE was supported by a Leverhulme Trust Early Career Fellowship (ECF-2019-155), the University of Leicester and the University of Glasgow. SJW was supported by NERC studentship NE/L002493/1. MKJ was supported by STFC Grant ST/W00089X/1. JML was supported by the Irish Research Council. LJP was supported by AFOSR MURI Award 26-0201-51-62.The effects of a solar wind pressure pulse on the terrestrial magnetosphere have been observed in detail across multiple datasets. The communication of these effects into the magnetosphere is known as a positive geomagnetic sudden impulse (+SI), and are observed across latitudes and different phenomena to characterise the propagation of +SI effects through the magnetosphere. A superposition of Alfvén and compressional propagation modes are observed in magnetometer signatures, with the dominance of these signatures varying with latitude. For the first time, collocated lobe reconnection convection vortices and region 0 field aligned currents are observed preceding the +SI onset, and an enhancement of these signatures is observed as a result of +SI effects. Finally, cusp auroral emission is observed collocated with the convection and current signatures. For the first time, simultaneous observations across multiple phenomena are presented to confirm models of +SI propagation presented previously.Publisher PDFPeer reviewe

    An Analysis of Private School Closings

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    We add to the small literature on private school supply by exploring exits of K-12 private schools. We find that the closure of private schools is not an infrequent event, and use national survey data from the National Center for Education Statistics to study closures of private schools. We assume that the probability of an exit is a function of excess supply of private schools over the demand, as well as the school's characteristics such as age, size, and religious affiliation. Our empirical results generally support the implications of the model. Working Paper 07-0
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