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Although the physical properties of a structure, such as stiffness, can be determined using some statical tests, the identification of damping parameters requires a dynamic test. In general, both theoretical prediction and experimental identification of damping are quite difficult. There are many different techniques available for damping identification, and each method gives a different damping parameter. The dynamic indentation method, rheometry, atomic force microscopy, and resonant vibration tests are commonly used to identify the damping of materials, including soft materials. While the viscous damping ratio, loss factor, complex modulus, and viscosity are quite common to describe the damping of materials, there are also other parameters, such as the specific damping capacity, loss angle, half-power bandwidth, and logarithmic decrement, to describe the damping of various materials. Often, one of these parameters is measured, and the measured parameter needs to be converted into another damping parameter for comparison purposes. In this review, the theoretical derivations of different parameters for the description and quantification of damping and their relationships are presented. The expressions for both high damping and low damping are included and evaluated. This study is considered as the first comprehensive review article presenting the theoretical derivations of a large number of damping parameters and the relationships among many damping parameters, with a quantitative evaluation of accurate and approximate formulas. This paper could be a primary resource for damping research and teaching.

Byline: Rajagopal. Srinath, Uday. Yanamandra, Anurag. Singh, Nupur. Aggarwal, Praneet. Kaur, Bhavya. Aggarwal, Shivendra. Shobhit, Gaytri. Duhan, Debashish. Paul, Sai. K Bareedu, Rajesh. Sahu, Anil. Menon Background: The COVID-19 pandemic [...]

Complementary and Alternative medicine is known to have health benefits. Yoga nidra practice is an easy-to-do practice and has shown beneficial effects on stress reduction and is found to improve sleep in insomnia patients. Effect of yoga nidra practice on subjective sleep is known but its effect on sleep and cognition objectively is not documented. The aim of the study was to study the effect of yoga nidra practice on cognition and sleep using objective parameters. 41 participants were enrolled, and baseline sleep diary (SD) collected. Participants volunteered for overnight polysomnography (PSG) and cognition testing battery (CTB) comprising of Motor praxis test, emotion recognition task (ERT), digital symbol substitution task, visual object learning task (VOLT), abstract matching (AIM), line orientation task, matrix reasoning task, fractal-2-back test (NBACK), psychomotor vigilance task and balloon analog risk task. Baseline CTB and after one and two weeks of practice was compared. Power spectra density for EEG at central, frontal, and occipital locations during CTB was compared. Repeat SD and PSG after four weeks of practice were done. After yoga nidra practice, improved reaction times for all cognition tasks were seen. Post intervention compared to baseline (95%CI; p-value, effect size) showed a significant improvement in sleep efficiency of +3.62% (0.3, 5.15; p = 0.03, r = 0.42), -20min (-35.78, -5.02; p = 0.003, d = 0.84) for wake after sleep onset and +4.19 μV2 (0.5, 9.5; p = 0.04, r = 0.43) in delta during deep sleep. Accuracy increased in VOLT (95% CI: 0.08, 0.17; p = 0.002, d = 0.79), AIM (95% CI: 0.03, 0.12; p = 0.02, d = 0.61) and NBACK (95% CI: 0.02, 0.13; p = 0.04, d = 0.56); ERT accuracy increased for happy, fear and anger (95% CI: 0.07, 0.24; p = 0.004, d = 0.75) but reduced for neutral stimuli (95% CI: -0.31, -0.12; p = 0.04, r = 0.33) after yoga nidra practice. Yoga Nidra practice improved cognitive processing and night-time sleep. [ABSTRACT FROM AUTHOR]

Cerebral venous sinus thrombosis (CVT) is an uncommon subtype of stroke. In general, patients with CVT have one or more risk factors for venous thrombosis. Malignancy is an established risk factor for venous thromboembolism, and is seen in 8.9% of the patients. However, the occurrence of CVT in the case of solid organ malignancy is a rare phenomenon. Cervical cancer is a malignancy that has rarely been associated with CVT, with only one case reported in the literature, and in that also diagnosis of CVT was incidental. We present a case of a young lady with recently diagnosed locally advanced cervical cancer who presented with headache, monoparesis, and focal onset motor seizures with preserved awareness. The initial neuroimaging showed intracerebral hemorrhage. However, subsequently, she was diagnosed with CVT with hemorrhagic infarction, which was initially masqueraded as a tumor bleed. [ABSTRACT FROM AUTHOR]

Objectives: The risk of developing new-onset seizure following ascent to high-altitude areas is currently unknown. We undertook a prospective study to quantify this risk.Methods: The study was conducted at a tertiary care hospital in India between July 2015 and December 2017. It included apparently healthy males of age ≥18 years who ascended to an altitude of ≥ 2500 m and stayed there for > 30 continuous days. Individuals with a history of seizure in the past two years, those who had not undergone acclimatization protocol, and those who had a history of any chronic systemic illness were excluded.Results: The 39,213 individuals included in the study together had 39,848.6 person-years of high-altitude exposure. New-onset seizure after ascent occurred in 41 of them, indicating a seizure incidence rate of 102.9 per 100,000 person-years (95% CI = 75.8-139.7). The incidence per 100,000 person-years (95% CI) at altitudes of 2,500-3,500 m, 3,500-5,800 m, and > 5,800 m was 82.3 (53.6-126.1), 134.6 (84.9-213.6), and 210.8 (52.8-841.4), respectively. Seizure was secondary to cerebral venous thrombosis in 12 (29.3%) individuals. No etiology could be determined in the remaining 29 (70.7%) individuals.Conclusions: Our findings suggest that when subjects living at sea level are exposed to high altitudes, they will be at a higher risk for new-onset seizure in the immediate few months of exposure, and that this risk increases with increasing altitude. [ABSTRACT FROM AUTHOR]

Background Among patients hospitalized for severe pneumonia due to coronavirus disease (COVID-19), clinical stability and normal resting peripheral oxygen saturation (SpO 2 ) levels are widely used as a discharge criterion after recovery. It is unknown whether a test to assess the functional exercise capacity, like a six-minute walk test (6MWT), can add to the appropriateness of discharge criteria. Methods A cross-sectional study was conducted at a tertiary care COVID-19 hospital in India from 01 st to 31 st May 2021. All patients considered fit for discharge after recovery from "severe" COVID-19 pneumonia were subjected to 6MWT. Fitness for discharge was assessed by clinical stability and resting SpO 2 above 93% for three consecutive days. Patients were considered to have failed the 6MWT if there was ≥4% fall in SpO 2 or if they could not complete the test. Serum samples were analyzed for levels of C-reactive protein (CRP), interleukin-6 (IL-6), and lactate dehydrogenase (LDH) at the time of discharge. Results Fifty-three discharge-ready patients with a mean age of 54.54 ± 14.35 years with a male preponderance (60.38%) were analyzed. Thirty-three (62.26%) patients failed the 6MWT with a median six-minute walk distance (6MWD) of 270 m (60-360). A total of 45 (84.91%) patients had a fall in SpO 2 during the test. The median change in SpO 2 (∆SpO 2 ) was 5% ranging from -6% to 8%. Serum LDH was significantly higher among patients who failed the 6MWT with a median LDH of 334 IU/L (38.96-2339) versus 261 IU/L (49.2-494) (p = 0.02). The difference was not significant for CRP or IL-6. There was no statistically significant correlation between the inflammatory markers with either 6MWD or (∆SpO 2 ). Conclusion Two-thirds of the patients considered fit for discharge after recovery from severe COVID-19 pneumonia failed 6MWT, implying reduced functional exercise capacity and exertional hypoxia. Serum LDH levels were higher in these patients but not in other inflammatory markers. None of the inflammatory markers at discharge correlated with 6MWD or ∆SpO 2 of 6MWT., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2022, Yanamandra et al.)

Background Computed tomography (CT) scans and CT severity scores (CTSS) are widely used to assess the severity and prognosis in coronavirus disease 2019 (COVID-19). CTSS has performed well as a predictor in differentiating severe from non-severe cases. However, it is not known if CTSS performs similarly in hospitalized severe cases with hypoxia at admission. Methods We conducted a retrospective comparative study at a COVID-care center from Western India between 25th April and 31st May 2021, enrolling all consecutive severe COVID-19 patients with hypoxemia (peripheral oxygen saturation < 94%). Neutrophil-lymphocyte ratio (NLR), C-reactive protein (CRP), interleukin-6 (IL-6), lactate dehydrogenase (LDH), D-dimer, ferritin, and CT thorax were done within 24h of admission before being initiated on any anti-COVID-19 therapy. CTSS was calculated by visual assessment and categorized into three severity categories and was correlated with laboratory markers and overall survival (OS). Statistical analysis was done using John's Macintosh Project (JMP) 15.0.0 ver. 3.0.0 (Cary, North Carolina). Results The median age of the study population (n-298) was 59 years (24-95) with a male preponderance (61.41%, n=183). The 15 and 30-day survivals were 67.64% and 59.90%, respectively. CTSS did not correlate with age, gender, time from vaccination, symptoms, or comorbidities but had a significant though weak correlation with LDH (p=0.009), D-dimer (p=0.006), and NLR (p=0.019). Comparing demographic and laboratory aspects using CT severity categories, only NLR (p=0.0146) and D-dimer (p=0.0006) had significant differences. The 15d-OS of mild, moderate, and severe CT categories were 88.62%, 70.39%, and 52.62%, respectively, while 30d-OS of three categories were 59.08%, 63.96%, and 49.12%, respectively. Conclusion Among hospitalized severe COVID-19 patients with hypoxemia at admission, CT severity categories correlate well with outcomes but not inflammatory markers at admission., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2022, Yanamandra et al.)