1,369 research outputs found

    Strapdown calibration and alignment study. Volume 1 - Development document Final report

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    Calibration and alignment techniques for inertial sensing uni

    Distance domination in partitioned graphs

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    Blunted Cystine–Glutamate Antiporter Function in the Nucleus Accumbens Promotes Cocaine-induced Drug Seeking

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    Repeated cocaine alters glutamate neurotransmission, in part, by reducing cystine–glutamate exchange via system xc−, which maintains glutamate levels and receptor stimulation in the extrasynaptic compartment. In the present study, we undertook two approaches to determine the significance of plasticity involving system xc−. First, we examined whether the cysteine prodrug N-acetylcysteine attenuates cocaine-primed reinstatement by targeting system xc−. Rats were trained to self-administer cocaine (1 mg/kg/200 μl, i.v.) under extended access conditions (6 h/day). After extinction training, cocaine (10 mg/kg, i.p.) primed reinstatement was assessed in rats pretreated with N-acetylcysteine (0–60 mg/kg, i.p.) in the presence or absence of the system xc− inhibitor (S)-4-carboxyphenylglycine (CPG; 0.5 μM; infused into the nucleus accumbens). N-acetylcysteine attenuated cocaine-primed reinstatement, and this effect was reversed by co-administration of CPG. Secondly, we examined whether reduced system xc− activity is necessary for cocaine-primed reinstatement. To do this, we administered N-acetylcysteine (0 or 90 mg/kg, i.p.) prior to 12 daily self-administration sessions (1 mg/kg/200 μl, i.v.; 6 h/day) since this procedure has previously been shown to prevent reduced activity of system xc−. On the reinstatement test day, we then acutely impaired system xc− in some of the rats by infusing CPG (0.5 μM) into the nucleus accumbens. Rats that had received N-acetylcysteine prior to daily self-administration sessions exhibited diminished cocaine-primed reinstatement; this effect was reversed by infusing the cystine–glutamate exchange inhibitor CPG into the nucleus accumbens. Collectively these data establish system xc− in the nucleus accumbens as a key mechanism contributing to cocaine-primed reinstatement

    Repeated \u3cem\u3eN\u3c/em\u3e-Acetylcysteine Administration Alters Plasticity-Dependent Effects of Cocaine

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    Cocaine produces a persistent reduction in cystine–glutamate exchange via system xc− in the nucleus accumbens that may contribute to pathological glutamate signaling linked to addiction. System xc− influences glutamate neurotransmission by maintaining basal, extracellular glutamate in the nucleus accumbens, which, in turn, shapes synaptic activity by stimulating group II metabotropic glutamate autoreceptors. In the present study, we tested the hypothesis that a long-term reduction in system xc− activity is part of the plasticity produced by repeated cocaine that results in the establishment of compulsive drug seeking. To test this, the cysteine prodrug N-acetylcysteine was administered before daily cocaine to determine the impact of increased cystine–glutamate exchange on the development of plasticity-dependent cocaine seeking. Although N-acetylcysteine administered before cocaine did not alter the acute effects of cocaine on self-administration or locomotor activity, it prevented behaviors produced by repeated cocaine including escalation of drug intake, behavioral sensitization, and cocaine-primed reinstatement. Because sensitization or reinstatement was not evident even 2–3 weeks after the last injection of N-acetylcysteine, we examined whether N-acetylcysteine administered before daily cocaine also prevented the persistent reduction in system xc− activity produced by repeated cocaine. Interestingly, N-acetylcysteine pretreatment prevented cocaine-induced changes in [35S]cystine transport via system xc−, basal glutamate, and cocaine-evoked glutamate in the nucleus accumbens when assessed at least 3 weeks after the last N-acetylcysteine pretreatment. These findings indicate that N-acetylcysteine selectively alters plasticity-dependent behaviors and that normal system xc− activity prevents pathological changes in extracellular glutamate that may be necessary for compulsive drug seeking

    Displacement experiments provide evidence for path integration in Drosophila

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    Like many other animals, insects are capable of returning to previously visited locations using path integration, which is a memory of travelled direction and distance. Recent studies suggest that Drosophila can also use path integration to return to a food reward. However, the existing experimental evidence for path integration in Drosophila has a potential confound: pheromones deposited at the site of reward might enable flies to find previously rewarding locations even without memory. Here, we show that pheromones can indeed cause naïve flies to accumulate where previous flies had been rewarded in a navigation task. Therefore, we designed an experiment to determine if flies can use path integration memory despite potential pheromonal cues by displacing the flies shortly after an optogenetic reward. We found that rewarded flies returned to the location predicted by a memory-based model. Several analyses are consistent with path integration as the mechanism by which flies returned to the reward. We conclude that although pheromones are often important in fly navigation and must be carefully controlled for in future experiments, Drosophila may indeed be capable of performing path integration

    Work ethics climate in relation to nurses’ commitment in a South African hospital

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    Orientation: Commitment, well-being and employer loyalty affect nurse retention. Literature shows that nurses are leaving the workforce at an alarming rate and that various factors are causing them to leave their employers. Research purpose: The main aim of this study was to investigate the influence of the ethical work climate in the organisation on nurses’ commitment. Motivation for the study: The health sector is essential in promoting mental, physical and emotional health but faces a shortage of skilled workers. The work ethics climate (WEC) can play a crucial role in retaining skills. Research approach/design and method: A quantitative research approach was adopted in a non-probability convenience sample of 208 permanent nurses from a South African public hospital. Participants completed self-assessments on an ethical climate questionnaire and an organisational commitment scale (OCS), and regression analysis was used to analyse the data. Main findings: Work ethics climate correlated with nurses’ affective, continuance and normative commitment. In addition, the results indicated that WEC predicted nurses’ commitment. Practical/managerial implications: Public hospitals in South Africa should create policies, laws and procedures that encourage ethical behaviour characterised by honesty, justice and dignity to boost nurse commitment. Thus, the South African hospital should foster an ethical workplace and implement an ethical code. Contribution/value add: This study contributes to the theory of ethical work climate and ethical behaviour by suggesting that nurses who positively perceive policies, rules and hospitals that have clear regulations are more likely to engage

    Correction to "Influence of Dust and Black Carbon on the Snow Albedo in the NASA Goddard Earth Observing System Version 5 Land Surface Model"

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    The website information describing the forcing meteorological data used for the land surface model (LSM) simulation, which were observed at an Automated Meteorological Station CAWS) at the Sapporo District Meteorological Observatory maintained by the Japan Meteorological Agency (JMA), was missing from the text. The 1-hourly data were obtained from the website of Kisyoutoukeijouhou (Information for available JMA-observed meteorological data in the past) on the website of JMA (in Japanese) (available at: http://www.jma.go.jpijmaimenulreport.html). The measurement height information of 59.5 m for the anemometer at the Sapporo Observatory was also obtained from the website of JMA (in Japanese) (available at: http://www.jma.go.jp/jma/menu/report.html). In addition, the converted 10-m wind speed, based on the AWS/JMA data, was further converted to a 2-m wind speed prior to its use with the land model as a usual treatment of off-line Catchment simulation. Please ignore the ice absorption data on the website mentioned in paragraph [15] which was not used for our calculations (but the data on the website was mostly the same as the estimated ice absorption coefficients by the following method because they partially used the same data by Warren [1984]). We calculated the ice absorption coefficients with the method mentioned in the same paragraph, for which some of the refractive index data by Warren [1984] were used and then interpolated between wavelengths, and also mentioned in paragraph [20] for the visible (VIS) and near-infrared (NIR) ranges. The optical data we used were interpolated between wavelengths as necessary

    The influence of using digital diagnostic information on orthodontic treatment planning - a pilot study

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    The purpose of this pilot study was to assess whether orthodontic treatment planning is reproducible when carried out using digital records compared with clinical examinations or using standard records. The study also assessed patients' opinion of face-to-face consultations and potential use of teleorthodontics. The study was designed as a prospective observational cross-sectional pilot study and carried out in a UK dental teaching hospital involving 27 subjects. Four consultant Orthodontists carried out treatment planning, firstly following a clinical examination, then using standard records, and then using digital records. Each subject completed a questionnaire. Cohen's kappa coefficient and Fleiss' kappa coefficient were used to assess intra-observer reproducibility and inter-observer reproducibility of treatment planning decisions, respectively. A change in the diagnostic information format affected treatment planning reproducibility for half of the observers. Inter-observer reproducibility was greater when using hard copy records in comparison to digital records. No subjects were unsatisfied with their face-to-face consultation

    Managerial Work in a Practice-Embodying Institution - The role of calling, the virtue of constancy

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    What can be learned from a small scale study of managerial work in a highly marginal and under-researched working community? This paper uses the ‘goods-virtues-practices-institutions’ framework to examine the managerial work of owner-directors of traditional circuses. Inspired by MacIntyre’s arguments for the necessity of a narrative understanding of the virtues, interviews explored how British and Irish circus directors accounted for their working lives. A purposive sample was used to select subjects who had owned and managed traditional touring circuses for at least 15 years, a period in which the economic and reputational fortunes of traditional circuses have suffered badly. This sample enabled the research to examine the self-understanding of people who had, at least on the face of it, exhibited the virtue of constancy. The research contributes to our understanding of the role of the virtues in organizations by presenting evidence of an intimate relationship between the virtue of constancy and a ‘calling’ work orientation. This enhances our understanding of the virtues that are required if management is exercised as a domain-related practice
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