Payload Positioning System for Gravity Gradient Satellite

Many current satellites rely on active control systems to maintain attitude. Passively controlled gravity gradient satellites cost less and are more reliable, but have difficulty accommodating independently moving payloads such as pointable telescopes. To eliminate these difficulties, use of a counter rotating inertia is proposed to negate payload induced transient instabilities. Counter rotating inertias have been used before with limited success due to residual torque/momentum. In gravity gradient satellites, this is absorbed by the gravity gradient restoring torques. A single axis (of a three axis) demonstration gimbal using a bifilar pendulum with PC controlled servo feedback loop and simulated pointable payload was designed and tested. Results without momentum compensation resulted in large excursions and pointing stability problems. Measured displacements using the counter rotating inertia momentum compensation system were within specified and predicted values

Carotid Artery Calcification Detected on Panoramic Radiography Is Significantly Related to Cerebrovascular Accident, Coronary Artery Disease, and Poor Oral Health: A Retrospective Cross-Sectional Study

Panoramic radiography imaging modality is widely used by dentists for diagnosing dental and jaw conditions. It can also detect carotid artery calcification (CAC), indicative of calcified atherosclerotic plaques in the carotid arteries. This cross-sectional retrospective study at the University of Tennessee Health Science Center investigated the link between CAC identified on panoramic radiograph (PR) and cerebrovascular accident (CVA), coronary artery disease (CAD), and poor oral health. Data from 314 CAC patients collected from 2014 to 2023 included age at diagnosis, gender, and clinical histories of hypertension, hyperlipidemia, diabetes mellitus, CVA, CAD, and the decay, missing, and filled permanent teeth (DMFT) index. These patients were age- and gender-matched with non-CAC patients for analysis. The findings revealed high prevalences of hypertension (86.2%), hyperlipidemia (57.6%), diabetes mellitus (30.7%), CVA (15.5%), and CAD (28.7%) amongst CAC patients and the average DMFT index was 26.6. A comparative analysis of 276 matched controls demonstrated significant differences in hypertension (85.9% vs. 57.6%), hyperlipidemia (58.3% vs. 33.7%), diabetes (32.6% vs. 22.1%), CVA history (14.9% vs. 5.1%), CAD (26.1% vs. 9.8%), and DMFT scores (26.3 vs. 23.7), all indicating strong associations between CAC and these health conditions. The adjusted analysis showed that hypertension (aOR: 3.20 [95% CI: 2.06–5.07]), hyperlipidemia (aOR: 1.70 [95% CI: 1.14–2.50]), CVA (aOR: 2.20 [95% CI: 1.13–4.30]), and CAD (aOR: 2.10 [95% CI: 1.28–3.60]) were significantly associated with CAC. Notably, only 41.7% of the patients received a medical consultation after CAC detection on PR. It is crucial for dentists to refer patients for further evaluation

No Correlation between Giant Cell Arteritis and Chlamydia pneumoniae Infection: Investigation of 189 Patients by Standard and Improved PCR Methods▿

A total of 189 temporal artery biopsy samples from giant cell arteritis (GCA) patients were investigated using sensitive PCR targeting Chlamydia pneumoniae. Chlamydial DNA was detected in 17 samples, 11 of which were positive for chlamydial antigens. Our data did not reveal strong evidence that C. pneumoniae plays an important role in the pathogenesis of GCA