SynopsisGas-liquid chromatography (GLC) has been applied to the study of thermodynamic interactions in poly(viny1 chloride) (PVC) plasticized by di-n-octyl phthalate (DnOP). A number of vapor-phase "probes" were used to evaluate the Flory-Huggins thermodynamic parameter for the PVC-DnOP interaction in stationary phase mixtures of the components which covered the entire composition range. Experiments were carried out in the temperature span of 10O-13O0C. The interaction parameter was strongly negative, indicating high PVC-DnOP compatibility, up to 0.25 volume fraction of plasticizer. It then became less negative and finally positive a t 0.55 volume fraction of DnOP, suggesting a lower compatibility limit. The composition dependence of the interaction parameter and its apparent variation with the chemical nature of the vaporphase probe may reflect a nonrandom solution of the probe in the stationary phase and/or nonrandom mixing of PVC-DnOP, particularly a t DnOP contents in the limited compatibility range. Evaluations of the influence of DnOP on zero-shear melt viscosity and Tg of compounds indicate that both thermodynamic interactions and volume-of-dilution effects must be taken into account in assessing the effectiveness of the plasticizer.

Summary Recurrent event data are commonly encountered in observational studies where each subject may experience a particular event repeatedly over time. In this article, we aim to compare cumulative rate functions (CRFs) of two groups when treatment assignment may depend on the unbalanced distribution of confounders. Several estimators based on pseudo-observations are proposed to adjust for the confounding effects, namely inverse probability of treatment weighting estimator, regression model-based estimators, and doubly robust estimators. The proposed marginal regression estimator and doubly robust estimators based on pseudo-observations are shown to be consistent and asymptotically normal. A bootstrap approach is proposed for the variance estimation of the proposed estimators. Model diagnostic plots of residuals are presented to assess the goodness-of-fit for the proposed regression models. A family of adjusted two-sample pseudo-score tests is proposed to compare two CRFs. Simulation studies are conducted to assess finite sample performance of the proposed method. The proposed technique is demonstrated through an application to a hospital readmission data set.

Introduction: Social-distancing due to COVID-19 has led to social isolation, stress, and mental health issues in older adults, while overwhelming healthcare systems worldwide. Telehealth involving phone calls by trained volunteers is understudied and may be a low-cost, scalable, and valuable preventive tool for mental health. In this context, from patient participatory volunteer initiatives, we have adapted and developed an innovative volunteer-based telehealth intervention program for older adults (TIP-OA).Methods and analysis: To evaluate TIP-OA, we are conducting a mixed-methods longitudinal observational study.Participants: TIP-OA clients are older adults (age ≥ 60) recruited in Montreal, Quebec.Intervention: TIP-OA volunteers make weekly friendly phone calls to seniors to check in, form connections, provide information about COVID-19, and connect clients to community resources as needed.Measurements: Perceived stress, fear surrounding COVID-19, depression, and anxiety will be assessed at baseline, and at 4- and 8-weeks. Semi-structured interviews and focus groups will be conducted to assess the experiences of clients, volunteers, and stakeholders.Results: As of October 15th, 2020, 150 volunteers have been trained to provide TIP-OA to 305 older clients. We will consecutively select 200 clients receiving TIP-OA for quantitative data collection, plus 16 volunteers and 8 clinicians for focus groups, and 15 volunteers, 10 stakeholders, and 25 clients for semi-structured interviews.Discussion: During COVID-19, healthcare professionals' decreased availability and increased needs related to geriatric mental health are expected. If successful and scalable, volunteer-based TIP-OA may help prevent and improve mental health concerns, improve community participation, and decrease healthcare utilization.Clinical Trial Registration: ClinicalTrials.gov NCT04523610; https://clinicaltrials.gov/ct2/show/NCT04523610?term=NCT04523610&draw=2&rank=1

Objectives Late‐onset bipolar disorder (LOBD) represents a significant subgroup of bipolar disorder (BD). However, knowledge for this group is mostly extrapolated from small studies in subjects with early/mixed age of illness onset. In this global sample of older adults with BD (OABD: ≥50 years old) we aim to characterize the sociodemographic and clinical presentation of LOBD (≥40 years at BD onset) compared to early‐onset BD (EOBD: <40 years at BD onset). Methods The Global Aging and Geriatric Experiments in Bipolar Disorder consortium provided international data on 437 older age bipolar disorder participants. We compared LOBD versus EOBD on depression, mania, functionality, and physical comorbidities. Exploratory analyses were performed on participants with BD onset ≥50 years old. Results LOBD (n = 105) did not differ from EOBD (n = 332) on depression, mania, global functioning, nor employment status (p > 0.05). Late‐onset bipolar disorder was associated with higher endocrine comorbidities (odds ratio = 1.48, [95%CI = 1.0,12.1], p = 0.03). This difference did not remain significant when subjects with BD onset ≥50 years old were analyzed. Limitations This study is limited by the retrospective nature of the variable age of onset and the differences in evaluation methods across studies (partially overcame by harmonization processes). Conclusion The present analysis is in favor of the hypothesis that LOBD might represent a similar clinical phenotype as classic EOBD with respect to core BD symptomatology, functionality, and comorbid physical conditions. Large‐scale global collaboration to improve our understanding of BD across the lifespan is needed.