204 research outputs found

    Toward a holistic understanding of conduct disorder across the lifespan

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    Conduct Disorder is a developmental disorder characterized by clinically significant and culturally unexpected aggressive and antisocial behaviors. While much work has focused on the numerous predisposing genetic, neurobiological, psychological, and environmental risk factors for Conduct Disorder, its causal mechanisms, several developmental trajectories, and interacting risks have still yet to be properly elucidated within the context of these factors. With the aim of integrating the literature’s current understanding of Conduct Disorder, we searched APA PsycNet and Google Scholar using a scoping review to select peer-reviewed articles relating to age of onset, presentation, trajectory, persistence, and outcomes of Conduct Disorder. Of the 29 papers found, abstract screening and full text review identified 21 relevant peer-reviewed articles. When taken together and critically examined from a developmentally informed perspective, this holistic review of the literature highlights age of onset and persistence as important influences of disorder trajectory and outcome. The vast heterogeneity of Conduct Disorder should be given greater weight in future research, diagnosis, and early intervention efforts

    Monolithically Integrated Electrically Pumped Continuous-Wave III-V Quantum Dot Light Sources on Silicon

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    In this paper, we report monolithically integrated IIIV quantum dot (QD) light-emitting sources on silicon substrates for silicon photonics. We describe the first practical InAs/GaAs QD lasers monolithically grown on an offcut silicon (001) substrate due to the realization of high quality III-V epilayers on silicon with low defect density, indicating that the large material dissimilarity between III-Vs and silicon is no longer a fundamental barrier limiting monolithic growth of III-V lasers on Si substrates. Although the use of offcut silicon substrates overcomes the antiphase boundary (APB) problem, it has the disadvantage of not being readily compatible with standard microelectronics fabrication, where wafers with on-axis silicon (001) substrates are used. We therefore report, to the best of our knowledge, the first electrically pumped continuous-wave (c.w.) InAs/GaAs QD lasers fabricated on on-axis GaAs/Si (001) substrates without any intermediate buffer layers. Based on the achievements described above, we move on to report the first study of post-fabrication and prototyping of various Si-based light emitting sources by utilizing the focused ion beam (FIB) technique, with the intention of expediting the progress toward large-scale and low-cost photonic integrated circuits monolithically integrated on a silicon platform. We compare two Si-based QD lasers with as-cleaved and FIB-made facets, and prove that FIB is a powerful tool to fabricate integrated lasers on silicon substrates. Using angled facet structures, which effectively reduce facet reflectivity, we demonstrate Si-based InAs/GaAs QD superluminescent light emitting diodes (SLDs) operating under c.w. conditions at room temperature for the first time. The work described represents significant advances towards the realization of a comprehensive silicon photonics technology

    Monolithically Integrated Electrically Pumped Continuous-Wave III-V Quantum Dot Light Sources on Silicon

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    In this paper, we report monolithically integrated IIIV quantum dot (QD) light-emitting sources on silicon substrates for silicon photonics. We describe the first practical InAs/GaAs QD lasers monolithically grown on an offcut silicon (001) substrate due to the realization of high quality III-V epilayers on silicon with low defect density, indicating that the large material dissimilarity between III-Vs and silicon is no longer a fundamental barrier limiting monolithic growth of III-V lasers on Si substrates. Although the use of offcut silicon substrates overcomes the antiphase boundary (APB) problem, it has the disadvantage of not being readily compatible with standard microelectronics fabrication, where wafers with on-axis silicon (001) substrates are used. We therefore report, to the best of our knowledge, the first electrically pumped continuous-wave (c.w.) InAs/GaAs QD lasers fabricated on on-axis GaAs/Si (001) substrates without any intermediate buffer layers. Based on the achievements described above, we move on to report the first study of post-fabrication and prototyping of various Si-based light emitting sources by utilizing the focused ion beam (FIB) technique, with the intention of expediting the progress toward large-scale and low-cost photonic integrated circuits monolithically integrated on a silicon platform. We compare two Si-based QD lasers with as-cleaved and FIB-made facets, and prove that FIB is a powerful tool to fabricate integrated lasers on silicon substrates. Using angled facet structures, which effectively reduce facet reflectivity, we demonstrate Si-based InAs/GaAs QD superluminescent light emitting diodes (SLDs) operating under c.w. conditions at room temperature for the first time. The work described represents significant advances towards the realization of a comprehensive silicon photonics technology

    Prevalence and factors associated with convulsive status epilepticus in Africans with epilepsy

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    Objective: We conducted a community survey to estimate the prevalence and describe the features, risk factors, and consequences of convulsive status epilepticus (CSE) among people with active convulsive epilepsy (ACE) identified in a multisite survey in Africa. Methods: We obtained clinical histories of CSE and neurologic examination data among 1,196 people with ACE identified from a population of 379,166 people in 3 sites: Agincourt, South Africa; Iganga-Mayuge, Uganda; and Kilifi, Kenya. We performed serologic assessment for the presence of antibodies to parasitic infections and HIV and determined adherence to antiepileptic drugs. Consequences of CSE were assessed using a questionnaire. Logistic regression was used to identify risk factors. Results: The adjusted prevalence of CSE in ACE among the general population across the 3 sites was 2.3 per 1,000, and differed with site (p \u3c 0.0001). Over half (55%) of CSE occurred in febrile illnesses and focal seizures were present in 61%. Risk factors for CSE in ACE were neurologic impairments, acute encephalopathy, previous hospitalization, and presence of antibody titers to falciparum malaria and HIV; these differed across sites. Burns (15%), lack of education (49%), being single (77%), and unemployment (78%) were common in CSE; these differed across the 3 sites. Nine percent with and 10% without CSE died. Conclusions: CSE is common in people with ACE in Africa; most occurs with febrile illnesses, is untreated, and has focal features suggesting preventable risk factors. Effective prevention and the management of infections and neurologic impairments may reduce the burden of CSE in ACE

    Integrating III-V quantum dot lasers on silicon substrates for silicon photonics

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    The realization of efficient III-V lasers directly grown on Si substrates is highly desirable for large-scale and low-cost silicon based optoelectronic integrated circuits. However, it has been hindered by the high threading dislocation (TD) density generated at the interface between III-V compounds and Si substrates. Introducing dislocation filter layers (DFLs) to suppress the TD propagation into the active region becomes a key factor for realising lasers with advanced performance. In this paper, optimization of InGaAs/GaAs DFLs in III-V quantum dot (QD) lasers on Si is demonstrated. Based on these optimized DFLs and other strategies, we have achieved a high performance electrically pumped QD laser on a Si substrate with threshold current density of 62.5 A cm-2, over 105 mW output power, maximum operation temperature of 120 °C and over 100,158 h of extrapolated lifetime

    Magnitude and factors associated with nonadherence to antiepileptic drug treatment in Africa: A cross-sectional multisite study

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    Objectives: The epilepsy treatment gap is large in low- and middle-income countries, but the reasons behind nonadherence to treatment with antiepileptic drugs (AEDs) across African countries remain unclear. We investigated the extent to which AEDs are not taken and associated factors in people with active convulsive epilepsy (ACE) identified in cross-sectional studies conducted in five African countries. Methods: We approached 2,192 people with a confirmed diagnosis of ACE for consent to give blood voluntarily. Participants were asked if they were taking AEDs, and plasma drug concentrations were measured using a fluorescence polarization immunoassay analyzer. Information about possible risk factors was collected using questionnaire-based clinical interviews. We determined factors associated with nonadherence to AED treatment in children and adults, as measured by detectable and optimal levels, using multilevel logistic regression. Results: In 1,303 samples assayed (43.7% were children), AEDs were detected in 482, but only 287 had optimal levels. Of the 1,303 samples, 532 (40.8%) were from people who had reported they were on AEDs. The overall prevalence of nonadherence to treatment was 63.1% (95% confidence interval [CI] 60.5–65.6%) as measured by detectable AED levels and 79.1% (95% CI 73.3–84.3%) as measured by optimal AED levels; self-reported nonadherence was 65.1% (95% CI 45.0–79.5%). Nonadherence was significantly (p < 0.001) more common among the children than among adults for optimal and detectable levels of AEDs, as was the self-reported nonadherence. In children, lack of previous hospitalization and learning difficulties were independently associated with nonadherence to treatment. In adults, history of delivery at home, absence of burn marks, and not seeking traditional medicine were independently associated with the nonadherence to AED treatment. Significance: Only about 20% of people with epilepsy benefit fully from antiepileptic drugs in sub-Saharan Africa, according to optimum AEDs levels. Children taking AEDs should be supervised to promote compliance

    Electrically Pumped Continuous-Wave III-V Quantum Dot Lasers Monolithically Grown On Silicon

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    We demonstrate electrically pumped continuous-wave InAs/GaAs quantum dot lasers monolithically grown on silicon substrates with a low threshold current density of 62.5 Acm -2 , a room temperature output exceeding 105 mW, operation up to 120 °C, and long extrapolated lifetime exceeding 100,000 h

    An Outcome-based Approach for the Creation of Fetal Growth Standards: Do Singletons and Twins Need Separate Standards?

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    Contemporary fetal growth standards are created by using theoretical properties (percentiles) of birth weight (for gestational age) distributions. The authors used a clinically relevant, outcome-based methodology to determine if separate fetal growth standards are required for singletons and twins. All singleton and twin livebirths between 36 and 42 weeks’ gestation in the United States (1995–2002) were included, after exclusions for missing information and other factors (n = 17,811,922). A birth weight range was identified, at each gestational age, over which serious neonatal morbidity and neonatal mortality rates were lowest. Among singleton males at 40 weeks, serious neonatal morbidity/mortality rates were lowest between 3,012 g (95% confidence interval (CI): 3,008, 3,018) and 3,978 g (95% CI: 3,976, 3,980). The low end of this optimal birth weight range for females was 37 g (95% CI: 21, 53) less. The low optimal birth weight was 152 g (95% CI: 121, 183) less for twins compared with singletons. No differences were observed in low optimal birth weight by period (1999–2002 vs. 1995–1998), but small differences were observed for maternal education, race, parity, age, and smoking status. Patterns of birth weight-specific serious neonatal morbidity/neonatal mortality support the need for plurality-specific fetal growth standards
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