4,117 research outputs found

    A Note on the Radiative and Collisional Branching Ratios in Polarized Radiation Transport with Coherent Scattering

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    We discuss the implementation of physically meaningful branching ratios between the CRD and PRD contributions to the emissivity of a polarized multi-term atom in the presence of both inelastic and elastic collisions. Our derivation is based on a recent theoretical formulation of partially coherent scattering, and it relies on a heuristic diagrammatic analysis of the various radiative and collisional processes to determine the proper form of the branching ratios. The expression we obtain for the emissivity is Δ=[Δ(1)−Δf.s.(2)]+Δ(2)\varepsilon=\left[\varepsilon^{\tiny (1)}-\varepsilon^{\tiny (2)}_{\rm f.s.} \right]+\varepsilon^{\tiny (2)}, where Δ(1)\varepsilon^{\tiny (1)} and Δ(2)\varepsilon^{\tiny (2)} are the emissivity terms for the redistributed and partially coherent radiation, respectively, and where "f.s." implies that the corresponding term must be evaluated assuming a flat-spectrum average of the incident radiation

    TIC: A Stokes inversion code for scattering polarization with partial frequency redistribution and arbitrary magnetic fields

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    We present the Tenerife Inversion Code (TIC), which has been developed to infer the magnetic and plasma properties of the solar chromosphere and transition region via full-Stokes inversion of polarized spectral lines. The code is based on the HanleRT forward engine, which takes into account many of the physical mechanisms that are critical for a proper modeling of the Stokes profiles of spectral lines originating in the tenuous and highly dynamic plasmas of the chromosphere and transition region: quantum level population imbalance and interference (atomic polarization), frequency coherence effects in polarized resonance scattering (partial frequency redistribution), and the impact of arbitrary magnetic fields on the atomic polarization and the radiation field. We present first results of atmospheric and magnetic inversions, and discuss future developments for the project.Comment: 17pages, 7 figures. Accepted for publication in The Astrophysical Journa

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

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    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 (ÎČ = 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

    Un modelo Poissoniano para predecir la matriculaciĂłn de vehĂ­culos en paĂ­ses europeos

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    En este artículo presentamos una modelización para la matriculación de vehículos en países de Europa mediante un proceso de Poisson Doblemente Estocåstico con media aleatoria Normal truncada. Apoyåndonos en trabajos previos acerca de este proceso, se amplía el estudio de características de éste. Asímismo, se hace una predicción de este proceso para los años 2000 y 2001

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

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    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 JaĂ©n (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 (ÎČ= ‐0.38, p= 0.001) and depressive symptoms (ÎČ= ‐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

    Subjective caregiver burden and anxiety in informal caregivers: a systematic review and meta-analysis

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    There is increasing evidence that subjective caregiver burden is an important determinant of clinically significant anxiety in family carers. This meta-analysis aims to synthesise this evidence and investigate the relationship between subjective caregiver burden and anxiety symptoms in informal caregivers. We searched PubMed, CINAHL and PsycINFO up to January 2020. Combined estimates were obtained using a random-effects model. After screening of 4,312 articles, 74 studies (with 75 independent samples) were included. There was a large, positive association between subjective caregiver burden and anxiety symptoms (r = 0.51; 95% CI = 0.47, 0.54; I2 = 0.0%). No differences were found in subgroup analyses by type of study design (cross-sectional vs. longitudinal), sampling, control of confounders or care-recipient characteristics. Subjective caregiver burden is an important risk factor for anxiety in informal caregivers. Targeting subjective caregiver burden could be beneficial in preventing clinically significant anxiety for the increasing number of family carers worldwide
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