75 research outputs found

    The infinite-dimensional Pontryagin maximum principle for optimal control problems of fractional evolution equations with endpoint state constraints

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    In this paper, we study the infinite-dimensional endpoint state-constrained optimal control problem for fractional evolution equations. The state equation is modeled by the X \mathsf{X} -valued left Caputo fractional evolution equation with the analytic semigroup, where X \mathsf{X} is a Banach space. The objective functional is formulated by the Bolza form, expressed in terms of the left Riemann-Liouville (RL) fractional integral running and initial/terminal costs. The endpoint state constraint is described by initial and terminal state values within convex subsets of X \mathsf{X} . Under this setting, we prove the Pontryagin maximum principle. Unlike the existing literature, we do not assume the strict convexity of X∗ \mathsf{X}^* , the dual space of X \mathsf{X} . This assumption is particularly important, as it guarantees the differentiability of the distance function of the endpoint state constraint. In the proof, we relax this assumption via a separation argument and constructing a family of spike variations for the Ekeland variational principle. Subsequently, we prove the maximum principle, including nontriviality, adjoint equation, transversality, and Hamiltonian maximization conditions, by establishing variational and duality analysis under the finite codimensionality of initial- and end-point variational sets. Our variational and duality analysis requires new representation results on left Caputo and right RL linear fractional evolution equations in terms of (left and right RL) fractional state transition operators. Indeed, due to the inherent complex nature of the problem of this paper, our maximum principle and its proof technique are new in the optimal control context. As an illustrative example, we consider the state-constrained fractional diffusion PDE control problem, for which the optimality condition is derived by the maximum principle of this paper

    Commentaries on Computer-based Language Assessment

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    The rapid change and use of computer technology has had a profound influence in the field of language teaching and assessment, and the changes that computer and technology has brought to language assessment in particular are not only in the delivery method, but also in the scoring systems (Chapelle & Douglas, 2006). For instance, a wide variety of tasks be given as a test online worldwide, and scores can be available immediately to the test takers. However, along with such advances come potential problems and concerns

    Synergic hypocholesterolaemic effect of n

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    Risk of all-cause and cause-specific mortality associated with immune-mediated inflammatory diseases in Korea

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    ObjectiveImmune-mediated inflammatory disease (IMID) is associated with an increased risk of mortality. It is unclear whether the higher mortality is attributable to the IMIDs themselves or to the higher prevalence of comorbidities in IMIDs. We aimed to investigate whether IMIDs per se confer a higher risk of mortality.MethodsFrom the Korean National Health Insurance Service-National Sample Cohort database, this population-based cohort study included 25,736 patients newly diagnosed with IMIDs between January 2007 and December 2017, and 128,680 individuals without IMIDs who were matched for age, sex, income, hypertension, type 2 diabetes, dyslipidemia, and the Charlson comorbidity index. All individuals were retrospectively observed through December 31, 2019. The outcomes included all-cause and cause-specific mortalities. Adjustments for age, sex, and comorbidities were performed using multivariable Cox proportional hazard regression analyses, and adjusted hazard ratios (aHRs) with 95% confidence intervals (CIs) for the outcomes were estimated.ResultsThe adjusted risk of all-cause mortality was significantly lower in patients with IMIDs than that in those without (aHR, 0.890; 95% CI, 0.841–0.942). Regarding cause-specific mortality, cancer-specific (aHR, 0.788; 95% CI, 0.712–0.872) and cardiovascular disease-specific (aHR, 0.798; 95% CI, 0.701–0.908) mortalities were the two causes of death that showed significantly lower risks in patients with IMIDs. A similar trend was observed when organ based IMIDs were analyzed separately (i.e., gut, joint, and skin IMIDs).ConclusionAfter adjusting for comorbidities, IMIDs were associated with a lower risk of all-cause mortality compared to those without IMIDs. This was attributable to the lower risks of cancer-and cardiovascular disease-specific mortalities

    Association of immune-mediated inflammatory diseases with depression and anxiety in patients with type 2 diabetes: A nationwide population-based study

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    ObjectivePatients with type 2 diabetes (T2DM) are at a high risk of developing depression and anxiety. To better stratify the risk, we aimed to assess whether the presence of immune-mediated inflammatory diseases (IMIDs) confers a higher risk of depression and anxiety in these patients.MethodsPatients with T2DM without prior depression or anxiety who underwent national health examination between 2009 and 2012 (n = 1,612,705) were enrolled from the nationwide health check-up data from Korean National Health Insurance Service. The outcome events were incident depression and anxiety, defined as International Classification of Diseases, 10th Revision codes F32–F33 and F40–F41, respectively. Multivariable Cox proportional hazard regression analyses were conducted to estimate the adjusted hazard ratio (aHR) and 95% confidence interval (CI) according to the existence of IMIDs.ResultsOver an average follow-up time of 6.4 years, existence of gut IMIDs was associated with a higher risk of depression (aHR: 1.28 [95% CI: 1.08–1.53]) and anxiety (1.22 [1.06–1.42]). Existence of joint IMIDs was associated with a higher risk of depression (1.34 [1.31–1.37]) and anxiety (1.31 [1.29–1.34]). Existence of skin IMID was associated with a higher risk of depression (1.18 [1.14–1.23]) and anxiety (1.13 [1.09–1.16]). The effect sizes of IMIDs on depression and anxiety were larger in those with ≥ 2 IMIDs (1.42 [1.19–1.69] and 1.49 [1.29–1.72], respectively) than in those with one IMID (1.30 [1.27–1.32] and 1.26 [1.24–1.28], respectively).ConclusionIn patients with T2DM, presence of IMIDs was associated with a higher risk of depression and anxiety. More stringent attention and screening for anxiety and depression should be encouraged in patients with T2DM and comorbid IMIDs due to clinical implications of psychological distress on patient-reported outcomes and prognosis

    Systemic chemotherapy with doxorubicin, cisplatin and capecitabine for metastatic hepatocellular carcinoma

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    BACKGROUND: Although numerous chemotherapeutic agents have been tested, the role of systemic chemotherapy for hepatocellular carcinoma (HCC) has not been clarified. New therapeutic strategies are thus needed to improve outcomes, and we designed this study with new effective drug combination. METHODS: Twenty-nine patients with histologically-confirmed, metastatic HCC received a combination chemotherapy with doxorubicin 60 mg/m(2 )and cisplatin 60 mg/m(2 )on day 1, plus capecitabine 2000 mg/m(2)/day as an intermittent regimen of 2 weeks of treatment followed by a 1-week rest. RESULTS: The median age was 49 years (range, 32–64) and 19 patients were hepatitis B virus seropositive. Child-Pugh class was A in all patients and 4 had Zubrod performance status of 2. The objective response rate was 24% (95% CI 9–40) with 6 stable diseases. The chemotherapy was generally well tolerated despite one treatment-related death. CONCLUSION: Combination chemotherapy with doxorubicin, cisplatin and capecitabine produced modest antitumor activity with tolerable adverse effects in patients with metastatic HCC

    Recent Progress in Electrospun Nanofibres: Reinforcement Effect and Mechanical Performance

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    Composite materials are becoming increasingly important as structural materials for aeronautical and space engineering, naval, automotive, and civil engineering, sporting goods, and other consumer products. Fiber-based reinforcement represents one of the most effective manufacturing strategies for enhancing the mechanical strength and other properties of composite materials. Electrospinning has gained widespread interest in the last two decades because of its ability to fabricate continuous ultrafine nanofibers with unique characteristics. The impact of electrospinning on fiber synthesis and processing, characterization, and applications in drug delivery, nanofiltration, tissue scaffolding, and electronics has been extensively studied in the past. In this article, the authors have focused on a comprehensive review of the mechanical performance and properties of electrospun nanofibers as potential reinforcements as well as their advanced nanocomposites
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