Duality in Nondifferentiable Vector Programming

AbstractIn this paper we study the saddle point optimality conditions and Lagrange duality in multiobjective optimization for generalized subconvex-like functions. We obtain results which will allow us to characterize the solutions for multiobjective programming problems from the saddle point conditions and allow us to relate them to the dual problem solutions which will be adequately defined. We also define a new dual problem for the multiobjective programming problem with the special property of being a scalar programming problem

Generalized Convexity in Multiobjective Programming

AbstractFor the scalar programming problem, some characterizations for optimal solutions are known. In these characterizations convexity properties play a very important role. In this work, we study characterizations for multiobjective programming problem solutions when functions belonging to the problem are differentiable. These characterizations need some conditions of convexity. In differentiable scalar programming problems the concept of invexity is very important. We prove that it is also necessary for the multiobjective programming problem and give some characterizations of multiobjective programming problem solutions under weaker conditions. We define analogous concepts to those of stationary points and to the conditions of Kuhn–Tucker and Fritz–John for the multiobjective programming problem

The relationship between perceived social support and psychological distress in carers of older relatives: A longitudinal cross-lagged analysis

BACKGROUND AND OBJECTIVES: Although a large body of research has examined the relationship between social support and psychological health of family carers of frail older people, the exact nature and direction of this relationship is not well understood with most research to date being cross-sectional. This longitudinal study explored the relationship between perceived social support and psychological distress in carers of older relatives. METHODS: We used data from two longitudinal cohorts which included a total of 332 family carers of frail older people. We used cross-lagged panel analysis to investigate the longitudinal association between perceived social support and carer psychological distress controlling for a number of covariates over time. RESULTS: Fully-adjusted Generalised Estimating Equations (GEE) and cross-lagged models indicated that higher social support was significantly associated with lower carer psychological distress over time (regression coefficient [B] = -0.178, standard error [SE] = 0.028), with levels of perceived social support exerting an effect on psychological distress rather than vice versa (β = 0.03, p = 0.32). LIMITATIONS: All observations were based on self-report data, and there may be other variables that may explain the results that we did not account for. DISCUSSION AND IMPLICATIONS: Our study finds that the directionality of the relationship appears to be from perceived social support to carer psychological distress suggesting that social support directly affects carer psychological health but not vice versa. This finding has important implications for the provision of social support interventions for carers of frail older people at risk of experiencing psychological distress

Effect of alloying on mechanical properties of as cast ferritic nodular cast irons

The development of low temperature applications for ferritic nodular cast irons calls for improved materials in the as cast state, e.g. for off-shore windmills components. Within this line of work, a series of 68 castings were prepared with the same casting procedure and slight changes in composition. The tensile properties at room temperature, as well as the impact energy for rupture at room temperature, 220 °C and 240 °C, were measured. Outputs from multivariate analysis performed on the data are then discussed and compared to literature results, putting emphasis on the properties of the ferritic matrix

La aplicación local de la norma RDA y su convivencia con MARC

Depto. de Biblioteconomía y DocumentaciónFac. de Ciencias de la DocumentaciónTRUEpu

The mediating role of sense of coherence on mental health outcomes in carers of older dependent relatives: a longitudinal study

Background: Sense of coherence (SOC) is an important protective factor for carer well‐being but research to date remains cross‐sectional, focusing primarily on the direct effects of SOC on carers’ mental health. The study's aim was to investigate the mediating role of SOC in the longitudinal relationship between caregiver strain and carers’ psychological health, and its stability over time. / Methods: Prospective longitudinal study conducted in Jaén (Spain) with a probabilistic sample of 132 carers of older people, with data collected at baseline and at one‐year follow‐up. We measured SOC, caregiver strain, anxiety and depressive symptoms, and several care recipient characteristics and intensity of care provided. We used multiple linear regression modelling and the Sobel test to analyse mediation effects. / Results: SOC was significantly negatively longitudinally associated with both anxiety (β= ‐0.38, p= 0.001) and depressive symptoms (β= ‐0.28, p= 0.023), after controlling for several confounders. SOC mediated both the relationship between caregiver strain and anxiety and caregiver strain and depressive symptoms (Sobel test; p< 0.001 for anxiety and p< 0.001 for depressive symptoms). Differences between baseline and one‐year follow‐up SOC scores were not statistically significant (p= 0.617). / Conclusions: SOC appears to buffer the impact of caregiver strain on symptoms of depression and anxiety in informal carers of older people. Our data showed that SOC is an important psychological resource for carers that remained relatively stable under non‐experimental conditions over a period of one year in this sample. Findings suggest that interventions aimed at strengthening SOC may protect carer psychological well‐being