1,688 research outputs found

    Exact limiting solutions for certain deterministic traffic rules

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    We analyze the steady-state flow as a function of the initial density for a class of deterministic cellular automata rules (``traffic rules'') with periodic boundary conditions [H. Fuks and N. Boccara, Int. J. Mod. Phys. C 9, 1 (1998)]. We are able to predict from simple considerations the observed, unexpected cutoff of the average flow at unity. We also present an efficient algorithm for determining the exact final flow from a given finite initial state. We analyze the behavior of this algorithm in the infinite limit to obtain for R_m,k an exact polynomial equation maximally of 2(m+k)th degree in the flow and density.Comment: 25 pages, 8 figure

    Native point defects in GaSb

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    We have applied positron annihilation spectroscopy to study native point defects in Te-doped n-type and nominally undoped p-type GaSb single crystals. The results show that the dominant vacancy defect trapping positrons in bulk GaSb is the gallium monovacancy. The temperature dependence of the average positron lifetime in both p- and n-type GaSb indicates that negative ion type defects with no associated open volume compete with the Ga vacancies. Based on comparison with theoretical predictions, these negative ions are identified as Ga antisites. The concentrations of these negatively charged defects exceed the Ga vacancy concentrations nearly by an order of magnitude. We conclude that the Ga antisite is the native defect responsible for p-type conductivity in GaSb single crystals.Peer reviewe

    Involving users in OPAC interface design: Perspective from a UK study

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    This is the post-print versoin of the Article. The official published version can be accessed from the link below - Copyright @ 2007 SpringerThe purpose of this study was to determine user suggestions for a typical OPAC (Online Public Library Catalogue) application’s functionality and features. An experiment was undertaken to find out the type of interactions features that users prefer to have in an OPAC. The study revealed that regardless of users’ Information Technology (IT) backgrounds, their functionality expectations of OPACs are the same. However, based on users’ previous experiences with OPACs, their requirements with respect to specific features may change. Users should be involved early in the OPAC development cycle process in order to ensure usable and functional interface

    Suicide and depression in former contact sports participants: population-based cohort study, systematic review, and meta-analysis

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    Background: Former participants in sports characterised by low intensity repetitive head impact appear to have elevated rates of later dementia, but links with other psychological health outcomes such as depression and suicide are uncertain. We quantified the occurrence of these endpoints in former contact sports athletes against general population controls using new data from a cohort study and a meta-analysis. Methods: The cohort study comprised 2004 retired male athletes, who had competed internationally as amateurs for Finland across a range of sports, and 1385 general population controls. All study members were linked to mortality and hospitalisation registries. In the PROSPERO-registered systematic review (CRD42022352780), we searched PubMed and Embase to October 31 2022 for cohort studies that reported standard estimates of association and precision. Study-specific estimates were aggregated in a random-effect meta-analysis. The Newcastle-Ottawa Scale was used to appraise the quality of each study. Findings: In survival analyses of the Finnish cohort data, former boxers (depression: hazard ratio 1.43 [95% CI 0.73, 2.78]; suicide: 1.75 [0.64, 4.38]), Olympic-style wrestlers (depression: 0.94 [0.44, 2.00]; suicide: 1.60 [0.64, 3.99]), and soccer players (depression: 0.62 [0.26, 1.48]; suicide: 0.50 [0.11, 2.16]) did not have statistically higher rates of major depressive disorder or suicide at follow-up relative to controls. In the systematic review, 7 cohort studies met inclusion criteria. After aggregating results with the Finnish cohort, retired soccer players appeared to have a lower risk of depression (summary risk ratio: 0.71 [0.54, 0.93]) relative to general population controls, while the rate of suicide was statistically the same across groups (0.70 [0.40, 1.23]). Past participation in American football seemed to be associated with some protection against suicide (0.58 [0.43, 0.80]) but there were insufficient studies of depression in this sport to facilitate aggregation. The aggregation of results from the soccer and American football studies showed directionally consistent relationships and there was no indication of inter-study heterogeneity (I2 = 0%). Interpretation: Based on a small cluster of studies exclusively comprising men, retired soccer players had a lower rate of later depression and former American football players had a lower risk of suicide relative to comparator groups. Whether these findings are generalisable to women requires testing. Funding: The preparation of this manuscript was unfunded

    Trends and risk factors of stillbirths and neonatal deaths in Eastern Uganda (1982-2011): a cross-sectional, population-based study.

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    : To identify mortality trends and risk factors associated with stillbirths and neonatal deaths 1982-2011. : Population-based cross-sectional study based on reported pregnancy history in Iganga-Mayuge Health and Demographic Surveillance Site (HDSS) in Uganda. A pregnancy history survey was conducted among women aged 15-49 years living in the HDSS during May-July 2011 (n = 10 540). Time trends were analysed with cubic splines and linear regression. Potential risk factors were examined with multilevel logistic regression with adjusted odds ratios (AOR) and 95% confidence intervals (CI). : 34 073 births from 1982 to 2011 were analysed. The annual rate of decrease was 0.9% for stillbirths and 1.8% for neonatal mortality. Stillbirths were associated with several risk factors: multiple births (AOR 2.57, CI 1.66-3.99), previous adverse outcome (AOR 6.16, CI 4.26-8.88) and grand multiparity among 35- to 49-year-olds (AOR 1.97, CI 1.32-2.89). Neonatal deaths were associated with multiple births (AOR 6.16, CI 4.80-7.92) and advanced maternal age linked with parity of 1-4 (AOR 2.34, CI 1.28-4.25) and grand multiparity (AOR 1.44, CI 1.09-1.90). Education, marital status and household wealth were not associated with the outcomes. : The slow decline in mortality rates and easily identifiable risk factors calls for improving quality of care at birth and a rethinking of how to address obstetric risks, potentially a revival of the risk approach in antenatal care.<br/

    Structural white matter connectometry of reading and dyslexia

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    Current views on the neural network subserving reading and its deficits in dyslexia rely largely on evidence derived from functional neuroimaging studies. However, understanding the structural organization of reading and its aberrations in dyslexia requires a hodological approach, studies of which have not provided consistent findings. Here, we adopted a whole brain hodological approach and investigated relationships between structural white matter connectivity and reading skills and phonological processing in a cross-sectional study of 44 adults using individual local connectome matrix from diffusion MRI data. Moreover, we performed quantitative anisotropy aided differential tractography to uncover structural white matter anomalies in dyslexia (23 dyslexics and 21 matched controls) and their correlation to reading-related skills. The connectometry analyses indicated that reading skills and phonological processing were both associated with corpus callosum (tapetum), forceps major and minor, as well as cerebellum bilaterally. Furthermore, the left dorsal and right thalamic pathways were associated with phonological processing. Differential tractography analyses revealed structural white matter anomalies in dyslexics in the left ventral route and bilaterally in the dorsal route compared to the controls. Connectivity deficits were also observed in the corpus callosum, forceps major, vertical occipital fasciculus and corticostriatal and thalamic pathways. Altered structural connectivity in the observed differential tractography results correlated with poor reading skills and phonological processing. Using a hodological approach, the current study provides novel evidence for the extent of the reading-related connectome and its aberrations in dyslexia. The results conform current functional neuroanatomical models of reading and developmental dyslexia but provide novel network-level and tract-level evidence on structural connectivity anomalies in dyslexia, including the vertical occipital fasciculus.Peer reviewe
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