527 research outputs found

    On the Validity and Applicability of Models of Negative Capacitance and Implications for MOS Applications

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    The observation of room temperature sub-60 mV/dec subthreshold slope (SS) in MOSFETs with ferroelectric (FE) layers in the gate stacks or in series with the gate has attracted much attention. Recently, we modeled this effect in the framework of a FE polarization switching model. However, there is a large amount of literature attributing this effect to a stabilization of quasi-static (QS) negative capacitance (NC) in the FE. The technological implications of a stabilized non-switching (NS) QSNC model vs a FE switching model are vastly different; the latter precluding applications to sub-60 mV/dec SS scaled CMOS due to speed limitations and power dissipated in switching. In this letter, we provide a thorough analysis assessing the foundations of models of QSNC, identifying which specific assumptions (ansatz) may be unlikely or unphysical, and analyzing their applicability. We show that it is not reasonable to expect QSNC for two separate capacitors connected in series (with a metal plate between dielectric (DE) and FE layers). We propose a model clarifying under which conditions a QS "apparent NC" for a FE layer in a FE-DE bi-layer stack may be observed, quantifying the requirements of strong interface polarization coupling in addition to capacitance matching. In this regime, our model suggests the FE layer does not behave as a NC layer, simply, the coupling leads to both the DE and FE behaving as high-k DE with similar permittivities. This may be useful for scaled EOT devices but does not lead to sub-60 mV/dec SS.Comment: Version published in Appl. Phys. Let

    Viewing the efficiency of chaos control

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    This paper aims to cast some new light on controlling chaos using the OGY- and the Zero-Spectral-Radius methods. In deriving those methods we use a generalized procedure differing from the usual ones. This procedure allows us to conveniently treat maps to be controlled bringing the orbit to both various saddles and to sources with both real and complex eigenvalues. We demonstrate the procedure and the subsequent control on a variety of maps. We evaluate the control by examining the basins of attraction of the relevant controlled systems graphically and in some cases analytically

    Polyphenol Content and Antioxidant Activity of Sour Cherries From Serbia

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    The aim of this study was to evaluate the content of phenolics: the total phenols (TP), flavonoids (TF), anthocyanins (TA), as well as the total antioxidant\ud capacity (TAC) in three sour cherry cultivars (Prunus cerasus L.) introduced to the southeast Serbia climate conditions. Among the investigated sour cherries,\ud „Oblačinska“ cultivar contained the highest amounts of all groups of phenolics, followed by „Cigančica“ > „Marela“. A significant difference were observed in the phenolic content among different cultivars and growing seasons (p  0.05), and the phenolic compounds were significantly higher in the growing season 2009. The examined cultivars possess a high antioxidant capacity, and all phenolics of highy correlation with TAC. The following compounds were identified and quantified using HPLC-DAD: 4 anthocyanins, the most abundant of which was cyanidin-3-glucoside in “Marela” and “Oblačinska”, and cyanidin-3-glucosylrutinoside in „Cigančica“, and 4 hydroxycinnamic acids, the most abundant of which was neochlorogenic acid in all sour cherry cultivars. The growing and ripening process on the tree of sour cherry cv. „Oblačinska“ was evaluated also. The results showed significant increases in total phenols during the ripening, the total anthocyanins and total antioxidant capacity and 4 quantified anthocyanins, however the neochlorogenic acid decreased during the ripening. The study indicated that the growing and climate conditions in southeast Serbia are convenient for introducing sour cherry cultivars.\u

    Modeling Single Electron Transfer in Si:P Double Quantum Dots

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    Solid-state systems such as P donors in Si have considerable potential for realization of scalable quantum computation. Recent experimental work in this area has focused on implanted Si:P double quantum dots (DQDs) that represent a preliminary step towards the realization of single donor charge-based qubits. This paper focuses on the techniques involved in analyzing the charge transfer within such DQD devices and understanding the impact of fabrication parameters on this process. We show that misalignment between the buried dots and surface gates affects the charge transfer behavior and identify some of the challenges posed by reducing the size of the metallic dot to the few donor regime.Comment: 11 pages, 7 figures, submitted to Nanotechnolog

    Characterization of the “frequent exacerbator phenotype” in bronchiectasis

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    Rationale: Exacerbations are key events in the natural history of bronchiectasis, but clinical predictors and outcomes of patients with frequently exacerbating disease are not well described. Objectives: To establish if there is a \u201cfrequent exacerbator phenotype\u201d in bronchiectasis and the impact of exacerbations on long-term clinical outcomes. Methods: We studied patients with bronchiectasis enrolled from 10 clinical centers in Europe and Israel, with up to 5 years of follow-up. Patients were categorized by baseline exacerbation frequency (zero, one, two, or three or more per year). The repeatability of exacerbation status was assessed, as well as the independent impact of exacerbation history on hospitalizations, quality of life, and mortality. Measurements and Main Results: A total of 2,572 patients were included. Frequent exacerbations were the strongest predictor of future exacerbation frequency, suggesting a consistent phenotype.The incident rate ratios for future exacerbations were 1.73 (95% confidence interval [CI], 1.47-2.02; P, 0.0001) for one exacerbation per year, 3.14 (95% CI, 2.70-3.66; P, 0.0001) for two exacerbations, and 5.97 (95% CI, 5.27-6.78; P, 0.0001) for patients with three or more exacerbations per year at baseline. Additional independent predictors of future exacerbation frequency were Haemophilus influenzae and Pseudomonas aeruginosa infection, FEV1, radiological severity of disease, and coexisting chronic obstructive pulmonary disease. Patients with frequently exacerbating disease had worse quality of life and were more likely to be hospitalized during followup. Mortality over up to 5 years of follow-up increased with increasing exacerbation frequency. Conclusions: The frequent exacerbator phenotype in bronchiectasis is consistent over time and shows high disease severity, poor quality of life, and increased mortality during follow-up

    Particle motion in weak relativistic gravitational fields

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    We derive the geodesic equation of motion in the presence of weak gravitational fields produced by relativistic sources such as cosmic strings, decomposed into scalar, vector and tensor parts. We find that the vector (gravito-magnetic) force is an important contributor, and for non-relativistic particles we recover the well-known result for the impulse from a moving straight string. Our results can be straightforwardly incorporated into N-body simulations to allow for the presence of cosmic defects or other sources of weak gravitational fields.Comment: 9 pages, 5 figure

    The independent contribution of <i>Pseudomonas aeruginosa</i> infection to long-term clinical outcomes in bronchiectasis

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    Pseudomonas aeruginosa is responsible for chronic infection in many bronchiectasis patients but it is not known whether it is associated with worse clinical outcomes independent of the underlying severity of disease. This study analysed data from 2596 bronchiectasis patients included from 10 different bronchiectasis clinical centres across Europe and Israel, with a 5-year follow-up period. Prevalence of P. aeruginosa chronic infection and its independent impact on exacerbations, hospitalisations, quality of life and mortality was assessed. The prevalence of P. aeruginosa chronic infection was 15.0% (n=389). P. aeruginosa was associated with a higher mortality in a univariate analysis (hazard ratio (HR) 2.02; 95% (confidence interval) CI 1.53-2.66; p&lt;0.0001) but an independent impact on mortality was not found in a multivariate analysis (HR 0.98; 95% CI 0.70-1.36; p=0.89). P. aeruginosa was independently associated with increased mortality only in patients with frequent exacerbations (two or more per year) (HR 2.03; 95% CI 1.36-3.03; p=0.001). An independent association with worse quality of life of 7.46 points (95% CI 2.93-12.00; p=0.001) was found in a multivariable linear regression. P. aeruginosa was therefore found to be independently associated with exacerbation frequency, hospital admissions and worse quality of life. Mortality was increased in patients with P. aeruginosa particularly in the presence of frequent exacerbations

    Cross-sectional study of the rates of military sexual trauma (MST) and associations with adverse mental health outcomes among UK female ex-service personnel:a study protocol

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    Introduction: This study investigates the rates of military sexual trauma (MST) and its associations with adverse mental health among a sample of UK female ex-service personnel who served during the Iraq/Afghanistan eras. Methods and analysis: Female ex-service personnel, who participated in the fourth phase (Phase 4) of the King’s Centre for Military Health Research (KCMHR) Health and Well-being Cohort Study (2022–2023) and consented to be recontacted for follow-up studies (n=295), are being invited to participate in an online questionnaire between July 2024 and February 2025. The questionnaire contains surveys and questions related to experiences of sexual harassment and sexual assault during and outside of military service, disordered eating and broader female health issues. While the questionnaire relates to several female health topics, this study focuses on the surveys related to experiences of sexual trauma and eating disorders. Sociodemographic variables and some health variables, including post-traumatic stress disorder (PTSD), complex PTSD, common mental disorders, alcohol misuse, physical somatisation and social support, will be extracted from participants’ pre-existing data collected in Phase 4 of the KCMHR Cohort Study. Analyses will assess rates of MST, and hierarchical multiple logistic regressions will investigate associated health impacts. Rates and ORs, employing 95% CIs, will be reported. Ethics and dissemination: This study has been granted full ethical approval by the King’s College London Research Ethics Committee (Ref: HR/DP-23/24–39040). Participants provide informed consent before participating and have access to a signposting booklet containing contact details for a range of support services. A risk protocol is in place, which outlines the procedure to be undertaken if a participant contacts the research team in distress. Findings will form part of a PhD thesis and will be further disseminated through peer-reviewed publication and dissemination with veteran mental health services and charities, and relevant government departments

    Mental health outcomes associated with military sexual trauma in serving and ex-servicewomen:A systematic review

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    Military sexual trauma (MST) (sexual harassment or sexual assault experienced during military service) is associated with adverse mental health outcomes. This systematic review assessed international, published, peer-reviewed academic literature and aimed to (1) identify the mental health outcomes of MST for serving and ex-servicewomen, (2) understand whether sexual harassment and sexual assault impact mental health differently, and (3) identify individual differences that may influence mental health outcomes. Included sources were peer reviewed, primary research, which investigated MST as a predictor of mental health outcome(s) in women. Database searches (June 2023, May 2024, and March 2025) yielded 63 studies, most of which (n = 58) were conducted in the United States and used quantitative methods (n = 60). A narrative synthesis approach facilitated data synthesis. Quantitative studies identified associations between MST and adverse mental health outcomes, with qualitative studies providing further context to these associations. Military sexual assault appeared to have a stronger relationship with adverse mental health than other MST experiences. Posttraumatic stress disorder and depression symptoms were associated with further outcomes, such as suicidality, disordered eating, and substance use. Some additional trauma exposures exacerbated the impacts of MST on mental health, whilst social support mitigated negative mental health outcomes. This review identifies significant mental health impacts of MST and highlights the importance of formal and informal support for serving and ex-servicewomen with MST experiences.</p
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