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In this paper, we study a stock-rationing queue with two demand classes by means of the sensitivity-based optimization, and develop a complete algebraic solution to the optimal dynamic rationing policy. We show that the optimal dynamic rationing policy must be of transformational threshold type. Based on this finding, we can refine three sufficient conditions under each of which the optimal dynamic rationing policy is of threshold type (i.e., critical rationing level). To do this, we use the performance difference equation to characterize the monotonicity and optimality of the long-run average profit of this system, and thus establish some new structural properties of the optimal dynamic rationing policy by observing any given reference policy. Finally, we use numerical experiments to demonstrate our theoretical results of the optimal dynamic rationing policy. We believe that the methodology and results developed in this paper can shed light on the study of stock-rationing queue and open a series of potentially promising research.
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This study aims to investigate the association between waist circumference and the development of hypertension based on a nationwide cohort Chinese population. A total of 5330 individuals free of hypertension at baseline were collected from the China Health and Retirement Longitudinal Study. The association between waist circumference and the development of hypertension was analyzed by an adjusted cox regression model and visualized by restricted cubic splines. Further, we applied the supervised machine learning methods to evaluate the importance of multiple variates for new-onset hypertension. Additionally, the robustness of the association was assessed by a subgroup analysis. A total of 1490 individuals (28.0%) developed hypertension during a mean follow-up of 3.32 years. The new-onset hypertension was more observed in those with increased waist circumference (P for trend < .001). In the fully adjusted Cox regression, each 10 cm increase of waist circumference would result in an 18% elevated risk of hypertension. The random forest method and the Extreme Gradient Boosting method revealed waist circumference as an important feature to predict the development of hypertension. The sensitivity analysis indicated a consistent trend between waist circumference and new-onset hypertension in all BMI categories. This study suggested high waist circumference as an independent risk factor for new-onset hypertension based on a nationwide cohort of Chinese adults aged ≥45 years old. Our results supported that waist circumference should be routinely measured.
Assuntos
Hipertensão , Adulto , Índice de Massa Corporal , China/epidemiologia , Humanos , Hipertensão/diagnóstico , Hipertensão/epidemiologia , Hipertensão/etiologia , Estudos Longitudinais , Pessoa de Meia-Idade , Aposentadoria , Fatores de Risco , Circunferência da CinturaRESUMO
Aim: This study investigates the trend in general obesity and abdominal obesity in US adults from 2001 to 2018. Methods: We included 44,184 adults from the nine cycles of the continuous NHANES (2001-2002, 2003-2004, 2005-2006, 2007-2008, 2009-2010, 2011-2012, 2013-2014, 2015-2016, and 2017-2018). The age-adjusted mean body mass index and waist circumference were calculated, and the sex-specific annual change was estimated by the survey cycle. We used the weighted sex-specific logistic regression models to analyze the prevalence of general obesity and abdominal obesity from 2001 to 2018. The weighted adjusted odds ratio (OR) with a 95% confidence interval (CI) was calculated. Results: Our study showed that general obesity and abdominal obesity account for about 35.48 and 53.13% of the US population. From 2001-2002 to 2017-2018, the age-adjusted prevalence of general obesity increased from 33.09 to 41.36% in females and from 26.88 to 42.43% in males. During 2001-2018, the age-adjusted prevalence of abdominal obesity increased from 57.58 to 67.33% in females and from 39.07 to 49.73% in males. A significant time-dependent increase was observed in the prevalence of general obesity (adjusted OR, 1.007; 95% CI 1.005-1.009, P < 0.001) and abdominal obesity (adjusted OR, 1.006; 95% CI, 1.004-1.008; P < 0.001). Conclusion: General obesity and abdominal obesity are a heavy health burden among US adults, and the increasing trend remains in both males and females from 2001 to 2018.
Assuntos
Obesidade Abdominal , Obesidade , Masculino , Feminino , Humanos , Obesidade Abdominal/epidemiologia , Inquéritos Nutricionais , Obesidade/epidemiologia , Circunferência da Cintura , Índice de Massa CorporalRESUMO
Background: Hypertension is a significant risk factor of cardiovascular diseases, posing a serious threat to global health. Calcium plays an important role in regulating body homeostasis. The association of calcium with hypertension remains uncertain in the general population. Methods and Results: Cross-sectional data from the 2007-2018 National Health and Nutrition Examination Survey (NHANES) were analyzed. Adjusted multivariable logistic regression analysis and restricted cubic spline were used to investigate the association of serum calcium with the prevalence of hypertension. A total of 26,778 participants were included. The increase in calcium levels showed a positive association with the prevalence of hypertension in all three models with ORs of 1.347 (1.249-1.454), 1.522 (1.401-1.654), and 1.438 (1.306-1.583). The further subgroup analysis demonstrated a robust trend across all categories by sex, age, race, BMI, and eGFR. The restricted cubic spline plot exhibited an S-curve relationship between calcium and hypertension. Conclusion: Our cross-sectional study demonstrated a positive association between higher serum calcium level and the prevalence of hypertension. Our findings highlighted serum calcium level in hypertensive patients.
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BACKGROUND: Talaromycosis caused by Talaromyces marneffei infection is a fatal systemic mycosis in immunosuppressed individuals, such as patients with AIDS. Cytokines and immunocytes play a central role against fungus infection. However, how the host immune system responds to infection and treatment has not been reported to date. METHODS: Forty-one Talaromyces marneffei coinfected AIDS patients were followed up, their immunocytes and cytokine profiles were obtained at different antifungal treatment stages, and data on clinical features and laboratory examinations were collected. Correlation analysis was used to identify factors associated with host immunity against Talaromyces marneffei infection in AIDS patients. RESULTS: Common diseases and conditions of these 41 patients were lymphadenopathy, hepatomegaly, and splenomegaly. CD4+ T cells were extremely low in all of them. Moreover, significant increases of proinflammatory cytokines (IL-12, IL-17A, TNF-α, IFN-γ, IL-18, and IL-1ß), anti-inflammatory cytokines (IL-10), and chemokines (IP-10) were observed in talaromycosis before treatment (P < .05), comparing to both AIDS patients and healthy controls. The cytokines IL-6, IL-8, TNF-α, IL-18, IL-17A, IL-7, IP-10, and IL-1ß reached peak levels 3 days after initial antifungal therapy, and then gradually decreased. The symptoms of the patients gradually decreased. Furthermore, patients who died showed the highest levels of IL-6, TNF-α, IL-8, IL-1ß, and IP-10, which were 1.4- to 164-fold higher than in surviving patients. CONCLUSIONS: Our findings indicate that innate immune-cell-derived cytokines are critical for host defense against AIDS-associated Talaromyces marneffei infection; furthermore, excessive inflammatory cytokines are associated with poor outcomes.