A mixed effects changepoint quantile regression model for longitudinal data with application on COVID-19 data

Introduction: Longitudinal individual response profiles could exhibit a mixture of two or more phases of increase or decrease in trend throughout the follow-up period, with one or more unknown transition points (changepoints). The detection and estimation of these changepoints is crucial. Most of the proposed statistical methods for detecting and estimating changepoints in literature rely on distributional assumptions that may not hold. In this case, a good alternative is to use a robust approach;the quantile regression model. There are methods in the literature to deal with quantile regression models with a changepoint. These methods ignore the within-subject dependence of longitudinal data. Methods: We propose a mixed effects quantile regression model with changepoints to account for dependence structure in the longitudinal data. Fixed effects parameters, in addition to the location of the changepoint, are estimated using the profile estimation method. The stochastic approximation EM algorithm is proposed to estimate the fixed effects parameters exploiting the link between an asymmetric Laplace distribution and the quantile regression. In addition, the location of the changepoint is estimated using the usual optimization methods. Results and discussion: A simulation study shows that the proposed estimation and inferential procedures perform reasonably well in finite samples. The practical use of the proposed model is illustrated using COVID-19 data. The data focus on the effect of global economic and health factors on the monthly death rate due to COVID-19 from 1 April 2020 to 30th April 2021. the results show a positive effect on the monthly number of patients with COVID-19 in intensive care units (ICUs) for both 0.5th and 0.8th quantiles of new monthly deaths per million. The stringency index, hospital beds, and diabetes prevalence have no significant effect on both 0.5th and 0.8th quantiles of new monthly deaths per million. Copyright © 2023 Ibrahim, Gad and Abd-Rabou.

Racial and socioeconomic status differences in stress, posttraumatic growth, and mental health in an older adult cohort during the COVID-19 pandemic.

Background: The COVID-19 pandemic has disproportionately impacted the most vulnerable and widened the health disparity gap in both physical and mental well-being. Consequentially, it is vital to understand how to best support elderly individuals, particularly Black Americans and people of low socioeconomic status, in navigating stressful situations during the COVID-19 pandemic and beyond. The aim of this study was to investigate perceived levels of stress, posttraumatic growth, coping strategies, socioeconomic status, and mental health between Black and non-Hispanic, White older adults, the majority over the age of 70. Additionally, we investigated which variables, if any, were associated with posttraumatic growth in these populations. Methods: One hundred seventy-six community dwelling older adults (mean age = 76.30 ±8.94), part of two observational studies (The Harvard Aging Brain Study and Instrumental Activities of Daily Living Study) in Massachusetts, US, were included in this cross-sectional study. The survey, conducted from March 23, 2021 to May 13, 2021, measured perceived stress, behavioral coping strategies, posttraumatic growth, and mental health during the COVID-19 pandemic. We investigated associations with post-traumatic growth in a multiple linear regression model and examined their differences by race with t-tests, Wilcoxon rank-sum tests, and Fisher's exact tests. A second multiple linear regression model was used to examine which coping strategies were associated with posttraumatic growth. Findings: Our results indicated no significant difference between the groups in terms of mental health or stress. However, Black participants showed significantly greater posttraumatic growth compared to non-Hispanic, White participants. Additionally, the coping strategies of religion and positive reframing were found to be significantly associated with posttraumatic growth. Furthermore, even with the effects of stress and coping strategies controlled for, race remained significantly associated with posttraumatic growth. Interpretation: The COVID-19 pandemic has differentially impacted Black and non-Hispanic White older adults. These results may help encourage further analysis on geriatric psychiatry as well as understanding how cultural values and adaptations impact posttraumatic growth and mental health in diverse populations. Funding: The Harvard Aging Brain Study (HABS) has been funded by NIH-NIA P01 AG036694 (PI: Reisa Sperling). The IADL study is funded by the National Institute on Aging (R01 AG053184, PI: Gad A. Marshall).

Chest imaging features of Coronavirus disease 2019 pneumonia: a systematic review and meta-analysis

INTRODUCTION: This study aimed to systematically review the evidence reporting the key imaging findings in confirmed COVID-19 pneumonia. EVIDENCE ACQUISITION: A systematic search for articles reporting the prevalence of imaging findings in patients with COVID-19 pneumonia was conducted in seven databases up to April 10, 2020. The study protocol was registered in PROSPERO (CRD42020172528). EVIDENCE SYNTHESIS: A total of 25 imaging features were identified in 29 studies. The most characteristic radiographic features of COVID-19 pneumonia include peripheral distribution (92.4%, 95% CI: 86.8-95.8), bilateral involvement (82.8%, 95% CI: 76.0-87.9), and ground-glass opacities (GGO) (76.0%, 95% CI: 59.5-87.3). Right lower lobe (RLL) was the most frequently involved lobe (89.0%, 95% CI: 79.6-94.4), followed by left lower lobe (LLL) in 86.5% (95% CI: 74.8-93.2) of patients. The atypical imaging features included bronchial wall thickening, lymphadenopathy, and pleural effusion, which were observed more commonly in severe and critical COVID-19 pneumonia compared to mild and moderate condition. CONCLUSIONS: Chest imaging can help to diagnose COVID-19 pneumonia, especially in regions where the availability of RT-PCR testing kits is limited. Recognition of key radiographic features of COVID-19 pneumonia is essential to identify patients at early stages, monitor disease progression, and optimize their management plan.

The impact of COVID-19 pandemic on wheat yield in El Sharkia Governorate, Egypt & nbsp;

The Corona pandemic limits human activities at a time when the world is facing challenges in food safety. Wheat is foremost cereal crop grown healthy in Egypt, especially in El Sharkia Governorate. The target of this work is to monitor wheat cultivation in El Sharkia Governorate during COVID-19 pandemic. The Normalized Difference Vegetation Index (NDVI) estimates were made by band 4 and band 5 of Landsat-8 images of 2018, 2019 and 2020. At the start of May 2020 a field visit was made to 50 sites cultivated with wheat to find out their yield and collecting soil samples. The Yield with NDVI was shown to have a strong relationship (R-2 = 0.84). The NDVI maps of 2018, 2019 and 2020 were produced using ENVI 5.3 software. The changes in wheat cultivation during 2018-2020 were analyzed and discussed in detail. Decrement in wheat yield was noticed in 2020 due to the lack of production requirements owing to the pandemic. (C) 2022 National Authority of Remote Sensing & Space Science. Published by Elsevier B.V.& nbsp;& nbsp;

Greater psychological resilience during the COVID-19 pandemic is associated with lower tau burden in cognitively unimpaired individuals

Background The outbreak of the 2019 novel coronavirus SARS-CoV-2, causing the COVID-19 pandemic, along with the global measures used to control the spread of the disease, have been particularly stressful for older individuals. Robust evidence suggests that stress-related physiological processes may play a significant role in the onset of age-related cognitive decline and dementia, such as Alzheimer?s disease (AD). For example, previous animal and human research have shown that stress exacerbates tau pathology and subsequent cognitive impairment. One important factor determining a person?s level of stress is psychological resilience, which refers to a person?s ability to return to equilibrium when difficulties occur. As such, resilience may buffer and protect individuals against the deleterious effects of stress. The objectives of this study were to examine the relationship between psychological resilience and tau burden in cognitively unimpaired individuals, and to evaluate whether amyloid (Aß) pathology modifies this relationship. Method A total of 114 older adults (mean age=74.5;66 females (57.9%)) enrolled in the Harvard Aging Brain Study or the Instrumental Activities of Daily Living study completed an electronic survey online including measures of psychological resilience (Connor-Davidson Resilience Scale-10, where a higher score indicates greater resilience) during the COVID-19 pandemic period (May 2020). We used previously collected (mean time from survey=1.75 year) PET imaging data to assess Aß and tau burden. Results Overall, participants demonstrated high levels of resilience (mean=29.5,range=9-40). Multiple regression analyses (correcting for age, gender and time difference between survey and PET) demonstrated an interaction between resilience and amyloid on tau pathology (ß=-0.01,p=0.015, Figure1). Specifically, in Aß+ individuals (SUVR>1.324), those with higher psychological resilience also had lower tau pathology. No relationship was seen in Aß- individuals. Conclusion Our findings suggest that greater resilience during the pandemic is associated with lower tau burden in individuals at higher risk of cognitive decline (i.e. preclinical AD). Future studies are needed to determine the impact of stress and psychological resilience on prospective pathological brain changes and subsequent cognitive decline. Furthermore, resilience may be an important target for interventions to support older adults navigating stressful situations and to lessen the influence of stressors on AD pathological processes.

Resilience and perceived stress in cognitively normal older adults during the COVID-19 pandemic

Background Psychological resilience, a construct representing a person?s ability to return to their baseline when difficulties occur, can play an important role in determining outcomes in the face of stressors. Resilience is a crucial component to consider during times of prolonged stress, such as experienced during the coronavirus disease (COVID-19) pandemic, given that chronic stress has been associated with cognitive decline and dementia. Here, we investigated whether psychological resilience modified levels of perceived stress (assessed over 7 months), as well as examined the influence of demographic variables and Alzheimer?s disease biomarkers on this relationship. Method In May-November 2020 of the COVID-19 pandemic, 39 cognitively normal participants (mean age=78.38;53.85% female) in the Harvard Aging Brain Study (HABS) completed questionnaires assessing stress (Perceived Stress Scale, PSS) and resilience (only at baseline;Connor-Davidson Resilience Scale), higher scores on each measure indicating greater stress and increased resilience, respectively. We used previously collected data to better characterize the cohort, with the Preclinical Alzheimer Cognitive Composite (PACC;mean=0.46, SD=0.79) to assess cognition, and PET imaging data to assess Aß burden. A hierarchical regression model was used to assess whether resilience could predict baseline perceived stress. A separate linear mixed effect model (LME) was used to explore how resilience, time, and their interaction may affect stress. Both models also included age, sex, education, cognition, and Aß status (SUVR>1.324). Result Perceived stress levels were generally low (mean=13.54, SD=8.65, range=0-35), and did not significantly vary over the study period (p>0.5;mean number of timepoints=3.13). Both models demonstrated a main effect of resilience, such that higher resilience was associated with lower stress levels (p<0.001;Figure 1). Perceived stress was not influenced by demographic factors, cognition or Aß status. No significant interaction was found between resilience and time in predicting stress levels longitudinally. Conclusion Our findings confirm that resilience is critical for coping with stress during the COVID-19 pandemic, suggesting that resilience could be an important target for potential interventions in the future. Efforts at increasing resilience could not only help support older adults navigating stressful situations, but may also mitigate negative effects of stress on neurocognitive and mental health.

Stress, resilience, and coping strategies in a sample of community-dwelling older adults during COVID-19.

Assessing the impact of the COVID-19 pandemic on perceived stress in older adults is critical to understanding how to best support elderly individuals navigating stressful situations, with the aim to lessen the impact of stressors on their brain health. Here, we collected measures on perceived stress, resilience, and behavioral coping strategies, in the context of the COVID-19 pandemic, in a cross-sectional sample of 141 community dwelling older adults (mean age = 74.4 ± 8.4, 59% females) who were part of two longitudinal observational studies in Massachusetts, U.S. Our results indicate that participants demonstrated moderate levels of stress related to COVID-19 and showed relatively high levels of resilience. Higher resilience was associated with greater use of adaptive coping behaviors and less use of maladaptive coping behaviors. The use of maladaptive coping strategies was associated with more stress. Moreover, hierarchical regression analyses revealed that resilience was the strongest unique predictor of stress, thus, largely accounting for the observed coping-outcome associations. Individual differences in resilience levels moderated the effects of two coping strategies (planning and self-blame) on stress. Specifically, planning was associated with increased levels of stress for people with low resilience. In contrast, high personal resilience attenuated the negative effect of self-blame on their stress levels. Taken together, our findings suggest that resilience is critical for coping with stress during the COVID-19 pandemic. Future approaches for augmenting resilience could prove to be important potential interventions to help support older adults navigating stressful situations as well as lessen adverse effects on neurocognitive and mental health in the future.

Perceptions of participants on Online Learning in the Outbreak of COVID-19: Case Study (preprint)

Corona pandemic wreaked havoc across the world, perilously hitting the education system. This comparative case study with tertiary students reveals their perceptions of on-line learning during the outbreak of the COVID-19. Tertiary institutes closed their doors, shifting students and staff to the on-line process without advanced notice or prior training. In-depth individual interviews were conducted via video conferencing, and thematic analysis was done using NVivo-12 software. However, it was explored 87% of Sri Lankan students struggled in the new learning space while it is 34% in New Zealand; Only 10% New Zealand students believed that online learning provided them with the ability to self-reliant learning in their own time and not be restricted by a classroom lesson, which they could miss. However, 5% Sri Lankan students had perception that online learning is benefited for self-reliant learn at the site may be highly adopted tuition culture of the secondary education, but they have struggled to overcome challenges in new learning space. This gap is seen across social norms and cultural values. It was revealed that in both countries, students faced cybersecurity and bullying and gender discrimination issues. It was also revealed that both countries have similar issues in on-line learning and teaching, such as lack of reliable internet access and technology issues. It is recommended that the teachers should be more competent since our learners are native digital speakers, while teachers are digital immigrants.

Vision-based Approach for Automated Social Distance Violators Detection

Social distancing is a necessary precaution measure taken in order to have more control over the outbreak of infectious diseases such as COVID-19. Most of Social distancing monitoring approaches are based on Bluetooth and mobile phones that require an app to be downloaded on all phones. This paper proposes a different approach to monitor social distancing, using cameras, and combining different computer vision algorithms. The approach utilizes the concept of inverse perspective mapping (IPM) together with the camera's intrinsic information to produce a bird's eye view with real-world coordinates of the frame being processed from a video source. The process starts with image enhancement, foreground detection using Gaussian Mixture Model (GMM) background subtraction, tracking using Kalman filter, computing real-world distance measurements between individuals, and detecting those who have been in less than 2 meters apart as they are considered to be in contact. This tool could assist the efforts of the governments to contain the virus. It can be implemented in closed areas or institutions, monitor the extent of people's commitment, and provide analysis and a faster approach to detect possibly corona suspicion cases. The approach is tested on the task decomposition data set, which included frames of closed areas and the camera's intrinsic parameters. Another data set was created with different scenarios to increase the confidence level of our algorithm. The results showed the success of our approach in detecting the violation in social distancing with accurate measures of the real-world coordinates. © 2020 IEEE.