388 research outputs found

    Reconfigurable quadruple quantum dots in a silicon nanowire transistor

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    We present a novel reconfigurable metal-oxide-semiconductor multi-gate transistor that can host a quadruple quantum dot in silicon. The device consist of an industrial quadruple-gate silicon nanowire field-effect transistor. Exploiting the corner effect, we study the versatility of the structure in the single quantum dot and the serial double quantum dot regimes and extract the relevant capacitance parameters. We address the fabrication variability of the quadruple-gate approach which, paired with improved silicon fabrication techniques, makes the corner state quantum dot approach a promising candidate for a scalable quantum information architecture

    Psychometric validation of the Persian Bergen Social Media Addiction Scale using classic test theory and Rasch models

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    Background and aims: The Bergen Social Media Addiction Scale (BSMAS), a six-item self-report scale that is a brief and effective psychometric instrument for assessing at-risk social media addiction on the Internet. However, its psychometric properties in Persian have never been examined and no studies have applied Rasch analysis for the psychometric testing. This study aimed to verify the construct validity of the Persian BSMAS using confirmatory factor analysis (CFA) and Rasch models among 2,676 Iranian adolescents. Methods: In addition to construct validity, measurement invariance in CFA and differential item functioning (DIF) in Rasch analysis across gender were tested for in the Persian BSMAS. Results: Both CFA [comparative fit index (CFI) = 0.993; Tucker–Lewis index (TLI) = 0.989; root mean square error of approximation (RMSEA) = 0.057; standardized root mean square residual (SRMR) = 0.039] and Rasch (infit MnSq = 0.88–1.28; outfit MnSq = 0.86–1.22) confirmed the unidimensionality of the BSMAS. Moreover, measurement invariance was supported in multigroup CFA including metric invariance (ΔCFI = −0.001; ΔSRMR = 0.003; ΔRMSEA = −0.005) and scalar invariance (ΔCFI = −0.002; ΔSRMR = 0.005; ΔRMSEA = 0.001) across gender. No item displayed DIF (DIF contrast = −0.48 to 0.24) in Rasch across gender. Conclusions: Given the Persian BSMAS was unidimensional, it is concluded that the instrument can be used to assess how an adolescent is addicted to social media on the Internet. Moreover, users of the instrument may comfortably compare the sum scores of the BSMAS across gender

    Temporal associations between morningness/eveningness, problematic social media use, psychological distress and daytime sleepiness: mediated roles of sleep quality and insomnia among young adults

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    The extant literature has suggested relationships between an individual's chronotype (in relation to morningness/eveningness) and several outcomes, including addictive disorders, psychological distress and daytime sleepiness. Moreover, sleep quality has been proposed to be a mediator in the aforementioned relationships. Consequently, the aim of the present study was to investigate the complex relationship between morningness/eveningness, problematic social media use, psychological distress and daytime sleepiness, with the potential mediators of sleep quality and insomnia. All participants (N = 1,791 [30.1% males]; mean age = 27.2 years, SD = 10.1) completed a battery of psychometric scales, including a reduced version of the Morningness‐Eveningness Questionnaire (at baseline), the Pittsburgh Sleep Quality Index and Insomnia Severity Index (1 month after baseline assessment), the Bergen Social Media Addiction Scale, the Hospital Anxiety and Depression Scale, and the Epworth Sleepiness Scale (2 months after baseline assessment). The impacts of morningness‐eveningness on problematic social media use, anxiety, depression and daytime sleepiness were found in the mediation models. Furthermore, the mediated effects of insomnia and sleep quality were observed. The present study's results emphasize the importance of promoting healthy sleep habits and sleep hygiene behaviours, and that of early detection of sleep problems among individuals who have the eveningness chronotype, because this would significantly improve their health outcomes

    Forcing mechanisms behind variations in TOC concentration of lake waters Forcing mechanisms behind variations in total organic carbon (TOC) concentration of lake waters during the past eight centuries – palaeolimnological evidence from southern Sweden Forcing mechanisms behind variations in TOC concentration of lake waters

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    International audienceDecadal-scale variations in total organic carbon (TOC) concentration in lake water since AD 1200 in two small lakes in southern Sweden were reconstructed based on visible-near infrared spectroscopy (VNIRS) of their recent sediment successions. In order to assess the impacts of local land-use changes and regional variations in 5 sulphur deposition and climate on the inferred changes in TOC concentration, the same sediment records were subjected to multi-proxy palaeolimnological analyses. Changes in lake-water pH were inferred from diatom analysis, whereas pollen-based land-use reconstructions (Landscape Reconstruction Algorithm) together with geo-chemical records provided information on catchment-scale environmental changes, 10 and comparisons were made with available records of climate and population density. Our long-term reconstructions reveal that TOC concentrations were generally high prior to AD 1900, with second-order variations coupled mainly to changes in agricultural land-use intensity. The last century showed significant changes, and unusually low TOC concentrations were recorded in 1930–1990, followed by a recent increase. Vari-15 ations in sulphur emissions, with an increase in the early 1900s to a peak around AD 1980 and a subsequent decrease, were most likely the main driver of these dynamics, although processes related to the introduction of modern forestry and recent increases in precipitation and temperature may have contributed. The increase in lake-water TOC concentration from around AD 1980 may therefore reflect a recovery process. Given 20 that the effects of sulphate deposition now subside, other forcing mechanisms related to land management and climate change will possibly become the main drivers of TOC concentration changes in boreal lake waters in the future

    Usefulness of high resolution coastal models for operational oil spill forecast: the "Full City" accident

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    Oil spill modeling is considered to be an important part of a decision support system (DeSS) for oil spill combatment and is useful for remedial action in case of accidents, as well as for designing the environmental monitoring system that is frequently set up after major accidents. Many accidents take place in coastal areas, implying that low resolution basin scale ocean models are of limited use for predicting the trajectories of an oil spill. In this study, we target the oil spill in connection with the "Full City" accident on the Norwegian south coast and compare operational simulations from three different oil spill models for the area. The result of the analysis is that all models do a satisfactory job. The "standard" operational model for the area is shown to have severe flaws, but by applying ocean forcing data of higher resolution (1.5 km resolution), the model system shows results that compare well with observations. The study also shows that an ensemble of results from the three different models is useful when predicting/analyzing oil spill in coastal areas

    Historical TOC concentration minima during peak sulfur deposition in two Swedish lakes

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    International audienceDecadal-scale variations in total organic carbon (TOC) concentration in lake water since AD 1200 in two small lakes in southern Sweden were reconstructed based on visible–near-infrared spectroscopy (VNIRS) of their recent sediment successions. In order to assess the impacts of local land-use changes, regional variations in sulfur, and nitrogen deposition and climate variations on the inferred changes in TOC concentration, the same sediment records were subjected to multi-proxy palaeolimnological analyses. Changes in lake-water pH were inferred from diatom analysis , whereas pollen-based land-use reconstructions (Landscape Reconstruction Algorithm) together with geochemical records provided information on catchment-scale environmental changes, and comparisons were made with available records of climate and population density. Our long-term reconstructions reveal that inferred lake-water TOC concentrations were generally high prior to AD 1900, with additional variability coupled mainly to changes in forest cover and agricultural land-use intensity. The last century showed significant changes, and unusually low TOC concentrations were inferred at AD 1930–1990, followed by a recent increase , largely consistent with monitoring data. Variations in sulfur emissions, with an increase in the early 1900s to a peak around AD 1980 and a subsequent decrease, were identified as an important driver of these dynamics at both sites, while processes related to the introduction of modern forestry and recent increases in precipitation and temperature may have contributed, but the effects differed between the sites. The increase in lake-water TOC concentration from around AD 1980 may therefore reflect a recovery process. Given that the effects of sulfur deposition now subside and that the recovery of lake-water TOC concentrations has reached pre-industrial levels, other forcing mechanisms related to land management and climate change may become the main drivers of TOC concentration changes in boreal lake waters in the future

    A cluster randomized controlled trial of a theory-based sleep hygiene intervention for adolescents

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    Study Objectives To use theory to design and evaluate an intervention to promote sleep hygiene and health among adolescents. Methods The Theory of Planned Behavior (TPB) and the Health Action Process Approach (HAPA) were used to develop an intervention, which was then evaluated in a cluster randomized trial. Participants were high school students (N = 2,841, M age = 15.12, SD = 1.50). Adolescents in the intervention group received four face-to-face sessions providing behavior change techniques targeting the theoretical determinants of sleep hygiene. Adolescents in the control group only received educational material at the end of the study. The primary outcome was sleep hygiene measured at 1 and 6 months postintervention. A number of secondary outcomes were also measured, including beliefs about sleep, self-regulatory processes, and outcomes related to health and wellbeing. Results Sleep hygiene was improved in the intervention group when compared with the control group at both follow-up points (coefficients = 0.16 and 0.19, 95% CIs = 0.12–0.20 and 0.15–0.23 at 1 and 6 months, respectively, for scores on the Adolescent Sleep Hygiene Scale), as were psychosocial and general aspects of health. Mediation analyses suggested that beliefs about sleep hygiene as specified by the TPB, along with self-regulatory processes from HAPA, both mediated the effect of the intervention on outcomes. In turn, the effects of the intervention on sleep hygiene mediated its impact on general health. Conclusions Healthcare practitioners might consider intervention programs based on the TPB and the HAPA to improve sleep among adolescents
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