Reduced Harmonics Generated and Reactive Volt-Ampere absorption of HVDC Converter Using By-Pass Switch

Control of a conventional converter station which uses a three-phase controlled bridge for converting AC to DC and vice-versa is achieved by fast-acting control of the valve firing angles. Tap-changers which are fitted on the converter transformer provide a near constant AC voltage input to the bridge to correct relatively slow changes of AC voltage. This paper describe a modification of the conventional bridge circuit, using by-pass valves connected to tapping points on the secondary winding of the transformer. This scheme permits a wide range of voltage control with a reduction in both the harmonic generation and the reactive voltampere absorption, and possibly eliminates the need for an on-load tap-changer on the converter transformer. Experimental results on a laboratory model compare well with the predicted values.</jats:p

Exploring Disparate Access to Care in Sarcoidosis Patients in Detroit, Michigan

Rationale Sarcoidosis is a multisystem granulomatous inflammatory disease with immense ongoing research. Previous studies assessed the role of social predictors on severity at presentation and found Black, older individuals, with lower income, without insurance to have more severe disease. The city of Detroit, Michigan is at greater risk of disparities with 5 times greater Black population and almost thrice in poverty compared to the nation. We aimed to explore these potential disparities to incorporate our findings into future practice at provider, patient and healthcare system level. Methods This is a retrospective chart review study of all patients seen in pulmonary clinics at Henry Ford Health between January 1st, 2020, and December 31st, 2022, with sarcoidosis patients identified as those with ICD diagnosis code D86. Data collected included date of office visit(s), age, race (Black, White, Other), sex, area deprivation index (ADI), insurance type (Medicare, Medicaid, Commercial), MyChart status, chest x-rays, pulmonary function tests (PFTs), missed clinic visits, number of hospitalizations, mortality, positive biopsy on file, communication of results after bronchoscopy and visits around the time of bronchoscopy. Categorical variables were described using frequency. Numerical variables were described using median, mean and standard deviation. Statistical analysis included Chi-square test, Two-sample T-test and Wilcoxon Rank Sum test and a p-value of \u3c0.05 was considered statistically significant. Results Sarcoidosis patients (N=788), when compared to those seen for other pulmonary problems (N=13,036) were typically slightly younger, Black, female, belonging to higher ADI (greater socioeconomic disadvantage) based on national and state ranks, more likely to use commercial insurance and Medicaid compared to Medicare, have active MyChart access, more noshows, more PFTs on file. Among sarcoidosis patients, significant findings included presence of active MyChart among younger patients, lower ADI and with commercial insurance; more X-rays and PFTs were done in Medicare patients; no-show rate was higher in higher ADI; hospitalizations were higher in those with government insurance. Sarcoidosis patients with positive biopsies on file from 2013-2023 were more likely to be male, White or other races, younger and belonged to lower national ADI ranks. Conclusions This study identified an intricate pattern of demographic and socioeconomic variables affecting access to care in sarcoidosis patients, raising concerns for healthcare barriers especially based on race and ADI, and higher bronchoscopies in those demographic groups thought less likely to have sarcoidosis. Understanding these is vital for equitable high-quality care, assisting in timely and efficient management of the patient\u27s disease. (Figure Presented)

Association of Area Deprivation Index with Adherence to Proposed Regimen in Patients with Sarcoidosis in Detroit, Michigan

BACKGROUND AND AIM: Social predictors affect severity of sarcoidosis, with Black patients, older individuals, those with lower income, and those without insurance having greater severity. This study aimed to explore potential disparities affecting access to care in sarcoidosis patients with a primary focus on metrics such as area deprivation index (ADI) and its association with adherence to the proposed regimen. METHODS: A retrospective chart review study of all patients seen in pulmonary clinics at a large urban tertiary care center over 2 years with sarcoidosis patients identified with International Classification of Diseases diagnosis code D86. Data collected included age, race, sex, ADI, insurance, online patient portal usage, chest x-rays, pulmonary function tests, missed visits, hospitalizations, positive biopsy, communication and visits around bronchoscopy. Categorical variables were described using frequency and percentage. Numerical variables were described using median, mean and standard deviation. Statistical analysis included chi-square test, two-sample T-test and Wilcoxon rank sum test. Multivariate logistic regression analysis was performed to model independent association with 12 month no-show occurrence as a metric of adherence to the proposed regimen. RESULTS: Among sarcoidosis patients (N = 788), univariate models showed the presence of active online patient portal use among younger patients (58.6 years with portal vs. 65.1 years without portal, p \u3c 0.001), those with lower ADI (73 with portal vs. 92 without portal, p \u3c 0.001) and with commercial insurance (48.5% with portal vs. 20.7% without portal, p \u3c 0.001); more x-rays (45.6% with x-rays vs. 36.6% without x-rays, p = 0.018) and hospitalizations (50.3% with hospitalizations vs. 36.2% without hospitalizations, p \u3c 0.001) in Medicare patients. Sarcoidosis patients with positive biopsies on file from 2013-2023 were more likely to be male (44.19% with positive biopsy vs. 33.91% without positive biopsy, p = 0.006), White (36.29% with positive biopsy vs. 22.9% without positive biopsy, p \u3c 0.001) or other races (3.23% with positive biopsy vs. 2.25% without positive biopsy, p \u3c 0.001), younger (55.8 years with positive biopsy vs. 61.7 years without positive biopsy, p \u3c 0.001) and belonged to lower national ADI ranks (73 with positive biopsy vs. 80 without biopsy, p = 0.041). A multivariate analysis was done with those variables found to be significant in the univariate analyses, which revealed that higher ADI national was associated with failure to adhere to the proposed regimen. CONCLUSIONS: We identified intricate patterns of sociodemographic variables affecting access to care in sarcoidosis patients, especially higher ADI national associated with failure to adhere to the proposed regimen, raising concerns for potential healthcare barriers. Understanding these barriers is vital for equitable high-quality care, assisting in timely and efficient management of the patient\u27s disease