4,285 research outputs found

    Spatial but not verbal cognitive deficits at age 3 years in persistently antisocial individuals

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    Previous studies have repeatedly shown verbal intelligence deficits in adolescent antisocial individuals, but it is not known whether these deficits are in place prior to kindergarten or, alternatively, whether they are acquired throughout childhood. This study assesses whether cognitive deficits occur as early as age 3 years and whether they are specific to persistently antisocial individuals. Verbal and spatial abilities were assessed at ages 3 and 11 years in 330 male and female children, while antisocial behavior was assessed at ages 8 and 17 years. Persistently antisocial individuals (N = 47) had spatial deficits in the absence of verbal deficits at age 3 years compared to comparisons (N = 133), and also spatial and verbal deficits at age 11 years. Age 3 spatial deficits were independent of social adversity, early hyperactivity, poor test motivation, poor test comprehension, and social discomfort during testing, and they were found in females as well as males. Findings suggest that early spatial deficits contribute to persistent antisocial behavior whereas verbal deficits are developmentally acquired. An early-starter model is proposed whereby early spatial impairments interfere with early bonding and attachment, reflect disrupted right hemisphere affect regulation and expression, and predispose to later persistent antisocial behavior

    Ultrasound by emergency physicians to detect abdominal aortic aneurysms: a UK case series

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    Early identification of abdominal aortic aneurysms in some patients can be difficult and the diagnosis is missed in up to 30% of patients. Ultrasound cannot be used to identify a leak, but the presence of an aneurysm in an unstable patient is conclusive. With minimal training emergency physicians can easily identify the aorta and thus in the early phase of resuscitation an aneurysm can be confidently excluded. The purpose of the examination is not to delineate the extent of the aneurysm, but to identify those patients that will need emergency surgery. A series of patients presented to the department in an unstable condition with equivocal abdominal signs. An ultrasound scan in the resuscitation room by members of the emergency department revealed an aneurysm, which was enough to convince the vascular surgeons to take the patient straight to theatre with good results. In patients who are stable, computed tomography will continue to be used to evaluate the extent of the aneurysm and identify a leak

    Algal culture studies related to a Closed Ecological Life Support System (CELSS)

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    Studies with algal cultures which relate to closed ecological life support systems (CELSS) are discussed. A description of a constant cell density apparatus for continuous culture of algae is included. Excretion of algal by-products, and nitrogen utilization and excretion are discussed

    Distributional fixed point equations for island nucleation in one dimension: a retrospective approach for capture zone scaling

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    The distributions of inter-island gaps and captures zones for islands nucleated on a one-dimensional substrate during submonolayer deposition are considered using a novel retrospective view. This provides an alternative perspective on why scaling occurs in this continuously evolving system. Distributional fixed point equations for the gaps are derived both with and without a mean field approximation for nearest neighbour gap size correlation. Solutions to the equations show that correct consideration of fragmentation bias justifies the mean field approach which can be extended to provide closed-from equations for the capture zones. Our results compare favourably to Monte Carlo data for both point and extended islands using a range of critical island size i=0,1,2,3i=0,1,2,3. We also find satisfactory agreement with theoretical models based on more traditional fragmentation theory approaches.Comment: 9 pages, 7 figures and 1 tabl

    Island size distributions in submonolayer growth: successful prediction by mean field theory with coverage dependent capture numbers

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    We show that mean-field rate equations for submonolayer growth can successfully predict island size distributions in the pre-coalescence regime if the full dependence of capture numbers on both the island size and the coverage is taken into account. This is demonstrated by extensive Kinetic Monte Carlo simulations for a growth kinetics with hit and stick aggregation. A detailed analysis of the capture numbers reveals a nonlinear dependence on the island size for small islands. This nonlinearity turns out to be crucial for the successful prediction of the island size distribution and renders an analytical treatment based on a continuum limit of the mean-field rate equations difficult.Comment: 4 pages, 4 figue

    Evolution of unoccupied resonance during the synthesis of a silver dimer on Ag(111)

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    Silver dimers were fabricated on Ag(111) by single-atom manipulation using the tip of a cryogenic scanning tunnelling microscope. An unoccupied electronic resonance was observed to shift toward the Fermi level with decreasing atom-atom distance as monitored by spatially resolved scanning tunnelling spectroscopy. Density functional calculations were used to analyse the experimental observations and revealed that the coupling between the adsorbed atoms is predominantly direct rather than indirect via the Ag(111) substrate.Comment: 9 pages, 3 figure

    Crossover in the scaling of island size and capture zone distributions

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    Simulations of irreversible growth of extended (fractal and square) islands with critical island sizes i=1 and 2 are performed in broad ranges of coverage \theta and diffusion-to-deposition ratios R in order to investigate scaling of island size and capture zone area distributions (ISD, CZD). Large \theta and small R lead to a crossover from the CZD predicted by the theory of Pimpinelli and Einstein (PE), with Gaussian right tail, to CZD with simple exponential decays. The corresponding ISD also cross over from Gaussian or faster decays to simple exponential ones. For fractal islands, these features are explained by changes in the island growth kinetics, from a competition for capture of diffusing adatoms (PE scaling) to aggregation of adatoms with effectively irrelevant diffusion, which is characteristic of random sequential adsorption (RSA) without surface diffusion. This interpretation is confirmed by studying the crossover with similar CZ areas (of order 100 sites) in a model with freezing of diffusing adatoms that corresponds to i=0. For square islands, deviations from PE predictions appear for coverages near \theta=0.2 and are mainly related to island coalescence. Our results show that the range of applicability of the PE theory is narrow, thus observing the predicted Gaussian tail of CZD may be difficult in real systems.Comment: 9 pages, 7 figure

    How members of the public account for the England Riots of summer 2011

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    The purpose of this study is to gain knowledge of how the general public viewed the England riots of 2011 in order to gain a fuller understanding of the riots and their impact on society. The study involved the thematic analysis of four semi-structured focus groups that were conducted with a total of eighteen participants from differing backgrounds. The analysis identified five themes: how participants draw on traditional theories of the crowd; the Police were deemed to be ‘damned if they do and damned if they don’t’; opportunism was used to account for looting; the media were viewed as aiding the spread of the riots but also as informative and as aiding the cleanup after the riots ended; and the riots were presented as being understandable, but in no way acceptable. This demonstrates how public understanding of the riots differs from the psychological literature. Practical recommendations are suggested including the need to give a platform to crowd psychologists

    Capture-zone scaling in island nucleation: phenomenological theory of an example of universal fluctuation behavior

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    In studies of island nucleation and growth, the distribution of capture zones, essentially proximity cells, can give more insight than island-size distributions. In contrast to the complicated expressions, ad hoc or derived from rate equations, usually used, we find the capture-zone distribution can be described by a simple expression generalizing the Wigner surmise from random matrix theory that accounts for the distribution of spacings in a host of fluctuation phenomena. Furthermore, its single adjustable parameter can be simply related to the critical nucleus of growth models and the substrate dimensionality. We compare with extensive published kinetic Monte Carlo data and limited experimental data. A phenomenological theory sheds light on the result.Comment: 5 pages, 4 figures, originally submitted to Phys. Rev. Lett. on Dec. 15, 2006; revised version v2 tightens and focuses the presentation, emphasizes the importance of universal features of fluctuations, corrects an error for d=1, replaces 2 of the figure

    Algal culture studies related to a Closed Ecological Life Support System (CELSS)

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    In many respects, algae would be the ideal plant component for a biologically based controlled life support system, since they are eminently suited to the closely coupled functions of atmosphere regeneration and food production. Scenedesmus obliquus and Spirulina platensis were grown in three continuous culture apparatuses. Culture vessels their operation and relative merits are described. Both light and nitrogen utilization efficiency are examined. Long term culture issues are detailed and a discussion of a plasmid search in Spirulina is included
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