Thermodynamics of collisional models for Brownian particles: General properties and efficiency

We introduce the idea of {\it collisional models} for Brownian particles, in which a particle is sequentially placed in contact with distinct thermal environments and external forces. Thermodynamic properties are exactly obtained, irrespective the number of reservoirs involved. In the presence of external forces, entropy production presents a bilinear form in which Onsager coefficients are exactly calculated. Analysis of Brownian engines based on sequential thermal switchings is proposed and considerations about their efficiencies are investigated taking into account distinct external forces protocols. Our results shed light to a new (and alternative) route for obtaining efficient thermal engines based on finite times Brownian machines.Comment: to appear in Phys. Rev. Res. (2020). Revised version contains and extensive manuscript revision and the inclusion of an extra figur

Obtaining efficient collisional engines via velocity dependent drivings

Brownian particles interacting sequentially with distinct temperatures and driving forces at each stroke have been tackled as a reliable alternative for the construction of engine setups. However they can behave very inefficiently depending on the driving used for the worksource and/or when temperatures of each stage are very different from each other. Inspired by some models for molecular motors and recent experimental studies, a coupling between driving and velocities is introduced as an alternative ingredient for enhancing the system performance. Here, the role of this new ingredient for levering the engine performance is detailed investigated from stochastic thermodynamics. Exact expressions for quantities and distinct maximization routes have been obtained and investigated. The search of an optimal coupling provides a substantial increase of engine performance (mainly efficiency), even for large $\Delta T$. A simple and general argument for the optimal coupling can be estimated, irrespective the driving and other model details.Comment: 10 pages, 8 figures, comments are welcom

Perceptions of Successful Aging Among Diverse Elders With Late-Life Disability

Purpose: Researchers often use the term “successful aging” to mean freedom from disability, yet the perspectives of elders living with late-life disability have not been well described. The purpose of this study was to explore the meaning of successful aging among a diverse sample of community-dwelling elders with late-life disability. Design and Methods: Using qualitative grounded theory methodology, we interviewed 56 African American, White, Cantonese-speaking Chinese, and Spanish-speaking Latino disabled elders who participate in On Lok Lifeways, a Program of All-inclusive Care for the Elderly. Through semi-structured interviews with open-ended questions, we explored the elders’ perceptions of what successful aging and being old meant to them. Results: Despite experiencing late-life disability, most participants felt they had aged successfully. An overarching theme was that aging results in Living in a New Reality, with two subthemes: Acknowledging the New Reality and Rejecting the New Reality. Participants achieved successful aging by using adaptation and coping strategies to align their perception of successful aging with their experiences. Themes were common across race/ethnic groups but certain strategies were more prominent among different groups. Implications: Across race and ethnic groups, most of these participants with late-life disability felt they had aged successfully. Thus, successful aging involves subjective criteria and has a cultural context that is not captured in objective measurements. Understanding elders’ perception will help establish common ground for communication between clinicians and elders and identify the most appropriate interventions to help elders achieve and maintain the experience of successful aging

The Relation of Hypertension to Changes in ADL/IADL Limitations of Mexican American Older Adults

Hypertension, highly prevalent and often undiagnosed among older Mexican Americans, is associated with greater limitations in activities of daily living (ADLs) and instrumental activities of daily living (IADLs) that can lead to greater dependency for older adults. Using data from the Hispanic Established Populations for Epidemiologic Studies of the Elderly study, the rate of increase in ADL/IADL limitations for a 7-year period was examined for 3,046 older Mexican Americans classified either as reporting hypertension at baseline, first reporting hypertension at subsequent waves, or never reporting hypertension. Latent growth models indicated increased ADL/IADL limitations over time; individuals with hypertension evidenced greater increases than those without hypertension. Age, comorbidities, and depression were positively related to greater ADL/IADL limitations at baseline for all groups; only age was consistently related to ADL/IADL change over time. Development of hypertension may increase the risk of ADL/IADL decline, but early diagnosis and treatment may attenuate this effect. Copyright 2010, Oxford University Press.

Are Latinos Less Satisfied with Communication by Health Care Providers?

OBJECTIVE: To examine associations of patient ratings of communication by health care providers with patient language (English vs Spanish) and ethnicity (Latino vs white). METHODS: A random sample of patients receiving medical care from a physician group association concentrated on the West Coast was studied. A total of 7,093 English and Spanish language questionnaires were returned for an overall response rate of 59%. Five questions asking patients to rate communication by their health care providers were examined in this study. All five questions were administered with a 7-point response scale. MAIN RESULTS: We estimated the associations of satisfaction ratings with language (English vs Spanish) and ethnicity (white vs Latino) using ordinal logistic models, controlling for age and gender. Latinos responding in Spanish (Latino/Spanish) were significantly more dissatisfied compared with Latinos responding in English (Latino/English) and non-Latino whites responding in English (white) when asked about: (1) the medical staff listened to what they say (29% vs 17% vs 13% rated this “very poor,”“poor,” or “fair”; p < .01); (2) answers to their questions (27% vs 16% vs 12%; p < .01); (3) explanations about prescribed medications (22% vs 19% vs 14%; p < .01); (4) explanations about medical procedures and test results (36% vs 21% vs 17%; p < .01); and (5) reassurance and support from their doctors and the office staff (37% vs 23% vs 18%; p < .01). CONCLUSION: This study documents that Latino/Spanish respondents are significantly more dissatisfied with provider communication than Latino/English and white respondents. These results suggest Spanish-speaking Latinos may be at increased risk of lower quality of care and poor health outcomes. Efforts to improve the quality of communication with Spanish-speaking Latino patients in outpatient health care settings are needed