363 research outputs found
Behavior of Poly electrolyte Gels in Concentrated Solutions of Highly Soluble Salts
Ionic hydrogels are an abundant class of materials with applications ranging from drug delivery devices to high performance concrete to baby diapers. A more thorough understanding of interactions between poly electrolyte networks and ionic solutes is critical as these materials are further tailored for performance applications in highly targeted ionic environments. In this work, we seek to develop structure-property relationships between polyelectrolyte gels and environments containing high concentrations of multivalent ions. Specifically, this work seeks to elucidate the causes behind differences in hydrogel response to divalent ions of main group metals versus transition metals. PANa-co-PAM hydrogels containing low and high fractions of ionic groups are investigated in solutions of DI water, NaCl, CaCl2, and CuSO4 at concentrations ranging from 5 to 100 mM in order to understand 1) the transient or permanent nature of crosslinks produced in these networks by divalent counter-ions, 2) the role of polymer ionic content in these interactions, and 3) how these interactions scale with salt concentration. Gravimetric swelling and mechanical compression testing are employed to characterize water and salt-swollen hydrogels in order to develop guiding principles to control and manipulate material properties through polymer-counter-ion interactions. The work presented here confirms the formation of permanent crosslinks by transition metal ions, offers explanation for the behavioral discrepancy observed between ionic hydrogels and main group versus transition metal ions, and illustrates how such hydrogel properties scale with counter-ion concentration
Stress appraisal, coping, and work engagement among police recruits: an exploratory study.
This study investigated the influence of stress appraisal and coping on work engagement levels (Absorption, Vigour, and Dedication) of police recruits. Participants were 387 men, ages 20 to 33 yr. (M = 24.1, SD = 2.4), in their last month of academy training before becoming police officers. Partially in support of predictions, work engagement was associated with Stressor control perceived, but not Stress intensity experienced over a self-selected stressor. Although the three dimensions of work engagement were explained by Stressor control and coping, Absorption was the dimension better explained by these variables. Police recruits reporting higher Absorption, Vigour, and Dedication reported using more Active coping and less Behavioural disengagement. Results showed that stress appraisal and coping are important variables influencing work engagement among police recruits. Findings suggested that future applied interventions fostering work engagement among police recruits should reinforce perceptions of control over a stressor as well as Active coping strategies
An interpretative phenomenological analysis of men’s and women’s coping strategy selection during early IVF treatment
Objectives: To describe the coping strategies that men and women adopted during the early stages of in vitro fertilisation treatment, and explore why and how they selected those strategies. Background: Previous research has identified coping strategies used during fertility treatment and the impact of those strategies on adjustment, but not how and why individuals choose the strategies they did, which is important for understanding coping strategy use as a self-regulatory process. Methods: Three heterosexual couples took part in two or three individual semi-structured interviews over six months, producing fourteen accounts, which were analysed using interpretative phenomenological analysis. Results: The emergent themes were: not dwelling on emotional issues; getting on with treatment; and keeping busy with other things. Participants selected coping strategies in a conscious, deliberate way, by making comparisons with other patients and by drawing on their broader, customary ways of coping. The strategies participants adopted made sense in the context of their long-term goals as well as their short-term treatment objectives. Conclusion: This research shows that for these participants, shorter-term behavioural strategies were informed by longer-term goals, which is consistent with a self-regulatory approach to understanding how people cope with the stress of treatment for infertility.N/
Cumulative Load of Depressive Symptoms Is Associated With Cortisol Awakening Response in Very Old Age.
This study examined links of cumulative and present depressive symptoms with present cortisol diurnal profiles in oldest-old adults. Five waves of data from 50 older adults (M age = 89.05 years; 64% women) who participated in the Australian Longitudinal Study of Ageing were used to combine 15 years of longitudinal data with seven cortisol samples per day over a one-week period. Findings revealed that individuals with more past depressive symptoms showed a lower cortisol awakening response (CAR). Interestingly, present depressive symptoms were not associated with the CAR. These findings inform our understanding of distal health factors in very old age
Posttraumatic growth as positive personality change: evidence, controversies and future directions
This target article focuses on the construct of post-traumatic growth—positive psychological change experienced as a result of the struggle with highly challenging life circumstances. Prominent theories of post-traumatic growth define it in terms of personality change, and as a result, this area of research should be of great interest to personality psychologists. Despite this fact, most of the research on this topic has not been sufficiently informed by relevant research in personality psychology, and much of the extant research suffers from significant methodological limitations. We review the literature on post-traumatic growth, with a particular focus on how researchers have conceptualized it and the specific methodological issues associated with these conceptualizations. We outline some ways in which personality science can both be enriched by the study of this phenomenon and inform rigorous research on post-traumatic growth and provide a series of guidelines for future research of post-traumatic growth as positive personality change
Predictive ability of a semi-mechanistic model for neutropenia in the development of novel anti-cancer agents: two case studies
Abstract
In cancer chemotherapy neutropenia is a common dose-limiting toxicity. An ability to predict the neutropenic effects of cytotoxic agents based on proposed trial designs and models conditioned on previous studies would be valuable. The aim of this study was to evaluate the ability of a semi-mechanistic pharmacokinetic/pharmacodynamic (PK/PD) model for myelosuppression to predict the neutropenia observed in Phase I clinical studies, based on parameter estimates obtained from prior trials. Pharmacokinetic and neutropenia data from 5 clinical trials for diflomotecan and from 4 clinical trials for indisulam were used. Data were analyzed and simulations were performed using the population approach with NONMEM VI. Parameter sets were estimated under the following scenarios: (a) data from each trial independently, (b) pooled data from all clinical trials and (c) pooled data from trials performed before the tested trial. Model performance in each of the scenarios was evaluated by means of predictive (visual and numerical) checks. The semi-mechanistic PK/PD model for neutropenia showed adequate predictive ability for both anti-cancer agents. For diflomotecan, similar predictions were obtained for the three scenarios. For indisulam predictions were better when based on data from the specific study, however when the model parameters were conditioned on data from trials performed prior to a specific study, similar predictions of the drug related-neutropenia profiles and descriptors were obtained as when all data were used. This work provides further indication that modeling and simulation tools can be applied in the early stages of drug development to optimize future trials
Evaluation of Phase Feeding and Complete Diet Blending at Different Standardized Ileal Digestible Lysine Levels on Growing-Finishing Pigs’ Growth Performance, Carcass Characteristics, and Diet Economics
A total of 2,160 mixed-gender pigs (PIC 337 × 1050; initially 54.8 ± 9.4 lb) were used in the 120-d study to compare feeding strategies (phase feeding vs. complete diet blending) at different SID Lys levels (90 vs. 100% of requirement estimates) on finishing pig growth performance, carcass characteristics, and economics. Pens of pigs were randomly assigned to 1 of 4 treatments following a completely randomized block design with barn and initial body weight as blocking factors. The treatments included two feeding programs, a 5-phase feeding strategy at either 90% (Phase-90) or 100% of SID Lys requirement estimates (Phase-100); or two programs with complete diet blending, with pre-defined mixing proportions of a low and high SID Lys diet to meet 90 (Blend-90) or 100% (Blend-100) of the SID Lys curve requirement estimates for 50- to 280-lb pigs. Pigs in the phase-feeding strategies were fed on a feed budget with 47, 144, 147, 138, and 136 lb of feed per pig for phases 1 to 5, respectively. Body weights at any period of the trial and overall ADG (d 0 to 120) were not affected by the feeding strategy nor by diet SID Lys levels. In contrast, the overall ADFI of pigs fed by diet blending was lower than the ADFI of those fed by phase feeding (P = 0.002), resulting in improved F/G (P \u3c 0.001). The SID Lys levels did not influence overall ADFI or F/G. Hot carcass weight, carcass yield, lean percentage, fat depth, and loin depth were not affected by the feeding program. Despite the lower overall ADFI of pigs fed by diet blending, the feeding strategy resulted in no significant differences in economic criteria except for feed cost per lb of gain at the high price scenario (P = 0.049). With low diet cost, the 90% SID Lys level resulted in lower feed cost per pig and feed cost per lb of gain than 100% SID Lys, but this was not reflected in income over feed cost (IOFC). In conclusion, diet blending at either 90 or 100% of the SID Lys requirement estimate improved F/G by reducing ADFI without impacting ADG or carcass characteristics. At current prices used in this study, feeding strategies at either 90 or 100% SID Lys did not significantly affect IOFC, but feeding 90% of the SID Lys recommendation reduced the feed cost
Chronic psychosocial and financial burden accelerates 5-year telomere shortening: findings from the Coronary Artery Risk Development in Young Adults Study.
Leukocyte telomere length, a marker of immune system function, is sensitive to exposures such as psychosocial stressors and health-maintaining behaviors. Past research has determined that stress experienced in adulthood is associated with shorter telomere length, but is limited to mostly cross-sectional reports. We test whether repeated reports of chronic psychosocial and financial burden is associated with telomere length change over a 5-year period (years 15 and 20) from 969 participants in the Coronary Artery Risk Development in Young Adults (CARDIA) Study, a longitudinal, population-based cohort, ages 18-30 at time of recruitment in 1985. We further examine whether multisystem resiliency, comprised of social connections, health-maintaining behaviors, and psychological resources, mitigates the effects of repeated burden on telomere attrition over 5 years. Our results indicate that adults with high chronic burden do not show decreased telomere length over the 5-year period. However, these effects do vary by level of resiliency, as regression results revealed a significant interaction between chronic burden and multisystem resiliency. For individuals with high repeated chronic burden and low multisystem resiliency (1 SD below the mean), there was a significant 5-year shortening in telomere length, whereas no significant relationships between chronic burden and attrition were evident for those at moderate and higher levels of resiliency. These effects apply similarly across the three components of resiliency. Results imply that interventions should focus on establishing strong social connections, psychological resources, and health-maintaining behaviors when attempting to ameliorate stress-related decline in telomere length among at-risk individuals
Caring for a child with a learning disability born into the family unit: Women's recollections over time
This is the authors' print-print version of an article published in Scandianavian journal of disability research which is available online at: http://www.tandfonline.com/doi/abs/10.1080/15017419.2010.540827Caring over time for a child/young adult with a learning disability requires that the family, and in particular the mother, negotiate their needs with services and professionals, and these negotiations are complicated further by significant behavioural issues in the children. This study reports on a series of interviews undertaken with mothers of children and young adults with learning disabilities and a history of challenging behaviours. The interviews were supplemented by documentary data from clinical and other notes in order to provide a more detailed view of the issues arising from caring over time. Detailed thematic analysis revealed five key themes demonstrating the cumulative effect of caring for someone with such complex needs, the centrality of that individual’s needs to the lives of those interviewed and the ongoing negotiation between family and professionals required in order for the former to work out how to continue caring both effectively and on their own terms. All the names of mothers and children are psuedonyms
Understanding older women's decision making and coping in the context of breast cancer treatment
Background: Primary endocrine therapy (PET) is a recognised alternative to surgery followed by endocrine therapy for a subset of older, frailer women with breast cancer. Choice of treatment is preference-sensitive and may require decision support. Older patients are often conceptualised as passive decision-makers. The present study used the Coping in Deliberation (CODE) framework to gain insight into decision making and coping processes in a group of older women who have faced breast cancer treatment decisions, and to inform the development of a decision support intervention (DSI).
Methods: Semi-structured interviews were carried out with older women who had been offered a choice of PET or surgery from five UK hospital clinics. Women's information and support needs, their breast cancer diagnosis and treatment decisions were explored. A secondary analysis of these interviews was conducted using the CODE framework to examine women's appraisals of health threat and coping throughout the deliberation process.
Results: Interviews with 35 women aged 75-98 years were analysed. Appraisals of breast cancer and treatment options were sometimes only partial, with most women forming a preference for treatment relatively quickly. However, a number of considerations which women made throughout the deliberation process were identified, including: past experiences of cancer and its treatment; scope for choice; risks, benefits and consequences of treatment; instincts about treatment choice; and healthcare professionals' recommendations. Women also described various strategies to cope with breast cancer and their treatment decisions. These included seeking information, obtaining practical and emotional support from healthcare professionals, friends and relatives, and relying on personal faith. Based on these findings, key questions were identified that women may ask during deliberation.
Conclusions: Many older women with breast cancer may be considered involved rather than passive decision-makers, and may benefit from DSIs designed to support decision making and coping within and beyond the clinic setting
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