5,099 research outputs found

    Enumeration in Alzheimer's disease and other late life psychiatric syndromes

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    Previous studies suggest that visual enumeration is spared in normal aging but impaired in abnormal aging (late stage Alzheimer's disease, AD), raising the task's potential as a marker of dementia. Experiment 1 compared speeded enumeration of 1–9 random dots in early stage AD, vascular dementia (VAD), depression, and age-matched controls. Previous deficits were replicated but they were not specific to AD, with the rate of counting larger numerosities similarly slowed relative to controls by both AD and VAD. Determination of subitizing span was complicated by the surprisingly slower enumeration of one than of two items, especially in AD patients. Experiment 2 showed that AD patients’ relative difficulty with one item persisted with further practice and extended to the enumeration of targets among distractors. However, it was abolished when pattern recognition was possible (enumerating dots on a die). Although an enumeration test is unlikely to help differentiate early AD from other common dementias, the unexpected pattern of patients’ performance challenges current models of enumeration and requires further investigation

    Kilometric radiation power flux dependence on area of discrete aurora

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    Kilometer wavelength radiation, measured from distant positions over the North Pole and over the Earth's equator, was compared to the area of discrete aurora imaged by several low-altitude spacecraft. Through correlative studies of auroral kilometric radiation (AKR) with about two thousand auroral images, a stereoscopic view of the average auroral acceleration region was obtained. A major result is that the total AKR power increases as the area of the discrete auroral oval increases. The implications are that the regions of parallel potentials or the auroral plasma cavities, in which AKR is generated, must possess the following attributes: (1) they are shallow in altitude and their radial position depends on wavelength, (2) they thread flux tubes of small cross section, (3) the generation mechanism in them reaches a saturation limit rapidly, and (4) their distribution over the discrete auroral oval is nearly uniform. The above statistical results are true for large samples collected over a long period of time (about six months). In the short term, AKR frequently exhibits temporal variations with scales as short as three minutes (the resolution of the averaged data used). These fluctuations are explainable by rapid quenchings as well as fast starts of the electron cyclotron maser mechanism. There were times when AKR was present at substantial power levels while optical emissions were below instrument thresholds. A recent theoretical result may account for this set of observations by predicting that suprathermal electrons, of energies as low as several hundred eV, can generate second harmonic AKR. The indirect observations of second harmonic AKR require that these electrons have mirror points high above the atmosphere so as to minimize auroral light emissions. The results provide evidence supporting the electron cyclotron maser mechanism

    J D Bernal: philosophy, politics and the science of science

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    This paper is an examination of the philosophical and political legacy of John Desmond Bernal. It addresses the evidence of an emerging consensus on Bernal based on the recent biography of Bernal by Andrew Brown and the reviews it has received. It takes issue with this view of Bernal, which tends to be admiring of his scientific contribution, bemused by his sexuality, condescending to his philosophy and hostile to his politics. This article is a critical defence of his philosophical and political position

    J D Bernal: philosophy, politics and the science of science

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    This paper is an examination of the philosophical and political legacy of John Desmond Bernal. It addresses the evidence of an emerging consensus on Bernal based on the recent biography of Bernal by Andrew Brown and the reviews it has received. It takes issue with this view of Bernal, which tends to be admiring of his scientific contribution, bemused by his sexuality, condescending to his philosophy and hostile to his politics. This article is a critical defence of his philosophical and political position

    Interaction of an expanding plasma cloud with a simple antenna: Application to anomalous voltage signals observed by Voyager 1, Voyager 2, ICE, and Vega spacecraft

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    High‐velocity impacts of interplanetary dust grains with spacecraft can give rise to transient plasma clouds from the spacecraft bodies. It is believed these plasma clouds can affect spacecraft instruments. Laboratory results are presented demonstrating the interaction of small expanding plasma clouds with a simple antenna. Results corroborate the hypothesized origin of anomalous impulsive voltage signals recorded by Voyager 1 and 2 spacecraft during flybys of Saturn, Uranus, and Neptune, the International Cometary Explorer (ICE) during its flyby of comet Giacobini‐Zinner, and Vega during its flyby of comet Halley. Results suggest that preflight calibration of antenna‐plasma interactions may extend the range of spacecraft diagnostics

    How Does Individual Recognition Evolve? Comparing Responses to Identity Information in P olistes Species with and Without Individual Recognition

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    A wide range of complex social behaviors are facilitated by the recognition of individual conspecifics. Individual recognition requires sufficient phenotypic variation to provide identity information as well as receivers that process and respond to identity information. Understanding how a complex trait such as individual recognition evolves requires that we consider how each component has evolved. Previous comparative studies have examined phenotypic variability in senders and receiver learning abilities, although little work has compared receiver responses to identity information among related species with and without individual recognition. Here, we compare responses to identity information in two Polistes paper wasps: P. fuscatus, which visually recognizes individuals, and P. metricus , which does not normally show evidence of individual recognition. Although the species differ in individual recognition, the results of this study show that receiver responses to experimentally manipulated identity information are surprisingly similar in both species. Receivers direct less aggression toward identifiable individuals than unidentifiable individuals. Therefore, the responses necessary for individual recognition may pre‐date its evolution in the P. fuscatus lineage. Additionally, our data demonstrate the apparent binary differences in a complex behavior between the two species, such as individual recognition, likely involve incremental differences along a number of axes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/102093/1/eth12191.pd

    Movement side effects of antipsychotic drugs in adults with and without intellectual disability: UK population-based cohort study

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    OBJECTIVES: To measure the incidence of movement side effects of antipsychotic drugs in adults with intellectual disability and compare rates with adults without intellectual disability. DESIGN: Cohort study using data from The Health Improvement Network. SETTING: UK primary care. PARTICIPANTS: Adults with intellectual disability prescribed antipsychotic drugs matched to a control group of adults without intellectual disability prescribed antipsychotic drugs. OUTCOME MEASURES: New records of movement side effect including acute dystonias, akathisia, parkinsonism, tardive dyskinaesia and neuroleptic malignant syndrome. RESULTS: 9013 adults with intellectual disability and a control cohort of 34 242 adults without intellectual disability together contributed 148 709 person-years data. The overall incidence of recorded movement side effects was 275 per 10 000 person-years (95% CI 256 to 296) in the intellectual disability group and 248 per 10 000 person-years (95% CI 237 to 260) in the control group. The incidence of any recorded movement side effect was significantly greater in people with intellectual disability compared with those without (incidence rate ratio 1.30, 95% CI 1.18 to 1.42, p<0.001, after adjustment for potential confounders), with parkinsonism and akathisia showing the greatest difference between the groups. Neuroleptic malignant syndrome, although occurring infrequently, was three times more common in people with intellectual disability-prescribed antipsychotic drugs (incidence rate ratio 3.03, 95% CI 1.26 to 7.30, p=0.013). Differences in rates of movement side effects between the groups were not due to differences in the proportions prescribed first and second-generation antipsychotic drugs. CONCLUSIONS: This study provides evidence to substantiate the long-held assumption that people with intellectual disability are more susceptible to movement side effects of antipsychotic drugs. Assessment for movement side effects should be integral to antipsychotic drug monitoring in people with intellectual disability. Regular medication review is essential to ensure optimal prescribing in this group

    Mental illness, challenging behaviour, and psychotropic drug prescribing in people with intellectual disability: UK population based cohort study

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    To describe the incidence of recorded mental illness and challenging behaviour in people with intellectual disability in UK primary care and to explore the prescription of psychotropic drugs in this group

    The role of planets in shaping planetary nebulae

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    In 1997 Soker laid out a framework for understanding the formation and shaping of planetary nebulae (PN). Starting from the assumption that non-spherical PN cannot be formed by single stars, he linked PN morphologies to the binary mechanisms that may have formed them, basing these connections almost entirely on observational arguments. In light of the last decade of discovery in the field of PN, we revise this framework, which, although simplistic, can still serve as a benchmark against which to test theories of PN origin and shaping. Within the framework, we revisit the role of planets in shaping PN. Soker invoked a planetary role in shaping PN because there are not enough close binaries to shape the large fraction of non-spherical PN. In this paper we adopt a model whereby only ~20% of all 1-8 solar mass stars make a PN. This reduces the need for planetary shaping. Through a propagation of percentages argument, and starting from the assumption that planets can only shape mildly elliptical PN, we conclude, like in Soker, that ~20% of all PN were shaped via planetary and other substellar interactions but we add that this corresponds to only ~5% of all 1-8 solar mass stars. This may be in line with findings of planets around main sequence stars. PN shaping by planets is made plausible by the recent discovery of planets that have survived interactions with red giant branch (RGB) stars. Finally, we conclude that of the ~80% of 1-8 solar mass stars that do not make a PN, about one quarter do not even ascend the AGB due to interactions with stellar and substellar companions, while three quarters ascend the AGB but do not make a PN. Once these stars leave the AGB they evolve normally and can be confused with post-RGB, extreme horizontal branch stars. We propose tests to identify them.Comment: 23 pages, accepted by PAS
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