124 research outputs found
Magneto-x-ray effects in transition-metal alloys
We present a theory that combines the relativistic spin-polarized version of the Koringa-Kohn-Rostoker coherent-potential approximation theory and the macroscopic theory of magneto-optical effects enabling us to calculate magneto-x-ray effects from first principles. The theory is illustrated by calculation of Faraday and Kerr rotations and ellipticities for transition-metal alloys
Signal-to-noise per unit time optimization for in vivo single-voxel proton magnetic resonance spectroscopy of the brain: Theoretical formulation and experimental verification at two field strengths
Signal-to-noise ratio optimization, regarding repetition time selection, was
explored mathematically and experimentally for single-voxel proton magnetic
resonance spectroscopy. Theoretical findings were benchmarked against phantom
measurements at 1.5 Tesla and localized in vivo proton brain spectra acquired
at both 1.5 Tesla/3.0 Tesla. A detailed mathematical description of
signal-to-noise ratio per unit time was derived, yielding an optimal repetition
time of 1.256 times the metabolite longitudinal relaxation time. While
long-repetition-time acquisitions minimize longitudinal relaxation time
contributions, a repetition time of ~1.5s results in maximum signal-to-noise
ratio per unit time, which can in turn be invested into smaller voxel sizes.
The latter is of utmost importance in brain oncology, allowing accurate
spectroscopic characterization of small lesions.Comment: 26 pages, 4 figures, submitted to Spectroscopy Letter
Electronic structure and x-ray magnetic dichroism in random substitutional alloys of f-electron elements
The Koringa-Kohn-Rostoker —coherent-potential-approximation method combines multiple-scattering theory and the coherent-potential approximation to calculate the electronic structure of random substitutional alloys of transition metals. In this paper we describe the generalization of this theory to describe f-electron alloys. The theory is illustrated with a calculation of the electronic structure and magnetic dichroism curves for a random substitutional alloy containing rare-earth or actinide elements from first principles
Skeletal muscle mass and body fat in relation to successful ageing of older adults: The multi-national MEDIS study
BACKGROUND: The determinants that promote successful ageing still remain unknown. The aim of the present work was to evaluate the role of skeletal muscle mass and body fat percentage (BF%), in the level of successful ageing. METHODS: during 2005-2011, 2663 older (aged 65-100 years) from 21 Mediterranean islands and the rural Mani region (Peloponnesus) of Greece were voluntarily enrolled in the study. Appendicular skeletal muscle mass (ASM), skeletal muscle mass index (SMI) and BF% were calculated using population formulas. Dietary habits, energy intake, expenditure and energy balance were derived throughout standard procedures. A successful ageing index ranging from 0 to 10 was used. RESULTS: The mean ASM mass was 24±6.0kg, the SMI was 0.84±0.21 and the BF% was 44%. Females had lower SMI and higher BF% in comparison with males, respectively [(SMI: 0.66±0.09 vs. 1.03±0.11; BF%: 51% vs. 34%, (p<0.001)]. High successful agers had better rates in ASM (p=0.01), SMI (p<0.001) and BF% (p<0.001), compared with the medium and low successful ones. Changes in SMI [b-coefficient (95% CI):2.14 (1.57 to 2.71)] were positively associated with successful ageing, while changes in BF% [b-coefficient (95% CI): -0.04 (-0.05 to -0.03)] were inversely associated with successful ageing. Results from sensitivity analysis showed that the effects of variations on body composition were consistent, less pronounced in the positive energy balance group and more pronounced among the oldest old. CONCLUSIONS: Body composition changes seem to be associated with lower quality of life in the older adults, as measured through successful ageing
Is Parental Longevity Associated With the Cardiovascular Risk and the Successful Aging of Their Offspring? Results From the Multinational MEDIS Study
The aim of the present study was to evaluate the role of parental longevity and parental cardiovascular disease (CVD) history in CVD risk and successful aging of a random sample of older adults living in the Mediterranean basin and who participated in the MEDiterranean Islands (MEDIS) study. During 2005 to 2011, 2663 elders were voluntarily enrolled. A multidimensional successful aging index consisting of 10 components was used. Paternal and maternal longevity was defined as those older participants of whom both parents lived above the age of 90. The burden of CVD-related factors (CVD-RFs) was calculated as the total score of 4 major CVD-RFs (range 0-4). After adjustment, parental longevity was inversely associated with the burden of CVD-RFs (P= .04). Moreover, parental longevity was positively associated with the older adults' successful aging score (β-coefficient [95% confidence interval]: .38 [0.06-0.71]). Parent's long living was revealed as an important factor for successful aging and for reduced CVD risk, suggesting that further research is needed in the genetic predisposition of longevity
Agency, stewardship and the universal-family firm : a qualitative historical analysis
This paper introduces the idea of a non-kinship-based Universal-family firm, an organizational form we developed based on interpreting historical writings in their socio-economic context. We analyzed Luke’s gospel with an eye toward drawing implications for the stewardship-agency debate in the contemporary family business literature. Our paper makes contributions at two important levels. In addition to introducing and developing theory about the Universal-family firms, we also contribute to the methodological toolkit of family business scholars by providing a template for using historical documents to challenge, enhance and develop theory
Association between siesta (daytime sleep), dietary patterns and the presence of metabolic syndrome in elderly living in Mediterranean area (MEDIS study):The moderating effect of gender
Objectives: Several lifestyle parameters including diet, physical activity and sleep were associated in isolation with the presence of Metabolic Syndrome (MetS) in adults, to date there is a paucity of studies which evaluated their combined role aging populations and especially with respect to gender. Therefore, the aim of the present study was to provide a global consideration of the lifestyle factors associated with MetS among elderly individuals. Design: Cross-sectional observational study. Setting: 21 Mediterranean islands and the rural Mani region (Peloponnesus) of Greece. Participants: during 2005-2015, 2749 older (aged 65-100 years) from were voluntarily enrolled in the study. Measurements: Dietary habits, energy intake, physical activity status, sociodemographic characteristics, lifestyle parameters (sleeping and smoking habits) and clinical profile aspects were derived through standard procedures. The presence of MetS was defined using the definition provided by NCEP ATP III (revised) and cluster analysis was used to identify overall dietary habit patterns. Results: The overall prevalence of MetS in the study sample was 36.2%, but occurred more frequently in females (40.0% vs. 31.8%, respectively, p=0.03). Individuals with MetS were more likely to sleep during the day (89.4% vs. 76.8% respectively, p=0.039) and frequent ‘siesta’ was positively linked to the odds of MetS presence in females (Odds Ratio (OR) =3.43, 95% Confidence Intervals (CI): 1.08-10.9), but not for men (p=0.999). The lower carbohydrate (i.e., 45.2% of total daily energy, 120±16gr/day) dietary cluster was inversely associated with the odds for MetS presence, but only for men (OR=0.094, 95%CI: 0.010-0.883). Conclusions: Lifestyle parameters including sleep and diet quality are strongly associated with the presence of MetS in elderly cohort, but different their level of influence appears to be different, depending on gender. Further research is needed to better consider the role of lifestyle characteristics in the management of MetS in clinical practice
Anti-Inflammatory Nutrition and Successful Ageing in Elderly Individuals: The Multinational MEDIS Study
BACKGROUND: The role of diet and inflammation in successful ageing is not transparent, and as such, is still being investigated. The aim of the present work was to evaluate the inflammatory potential of dietary habits in the successful ageing of a random sample of older adults living in the Mediterranean basin and who participated in the MEDIS (MEDiterranean ISlands) study. METHODS: During 2005-2016, 3,128 older adults (aged 65-100 years) from 24 Mediterranean islands and the rural Mani region (Peloponnesus) of Greece were enrolled in the study. A multidimensional successful ageing index consisting of 10 components was employed. A validated and reproducible Food Frequency Questionnaire (FFQ) was used to evaluate the dietary habits of the older adults. A nutrition anti-inflammatory (NAI) score based on the participants' specific dietary habits was assessed. RESULTS: Participants with high NAI scores (proinflammatory nutrition) had a higher prevalence of hypercholesterolemia and lower levels of successful ageing. After adjusting for several confounders, the NAI score was associated with successful ageing (-0.03, 95% CI -0.5 to -0.006). Stratified analysis by gender and advanced age revealed heterogeneity in the NAI score, predicting successful ageing. CONCLUSIONS: The inflammatory potential of nutrition was reported as an important factor for successful ageing, suggesting that further research is needed on the role of anti- and proinflammatory dietary habits in healthy and successful ageing
Modeling of synthesis and flow properties of propylene-diene copolymers
Copolymerization with nonconjugated dienes offers an attractive route for introducing long-chain branching in polypropylene. From a simplified set of rate equations for such copolymerization with a metallocene catalyst, we derive the probabilities of branch formation at different stages of the reaction in a semibatch reactor. Using these probabilities, we generate an ensemble of molecules via a Monte Carlo sampling. The knowledge of the branching topology and segment lengths allows us to compute the flow properties of the resins from computational rheology. We compare our model predictions with existing experimental data, namely the molar mass distribution and small amplitude oscillatory shear response, for a set of resins with varying diene content. The rheology data suggest that the entanglement time Ï.,e depends sensitively and in a well-defined fashion on the diene content
Favouritism: exploring the 'uncontrolled' spaces of the leadership experience
In this paper, we argue that a focus on favouritism magnifies a central ethical ambiguity in leadership, both conceptually and in practice. The social process of favouritism can even go unnoticed, or misrecognised if it does not manifest in a form in which it can be either included or excluded from what is (collectively interpreted as) leadership. The leadership literature presents a tension between what is an embodied and relational account of the ethical, on the one hand, and a more dispassionate organisational ‘justice’ emphasis, on the other hand. We conducted 23 semi-structured interviews in eight consultancy companies, four multinationals and four internationals. There were ethical issues at play in the way interviewees thought about favouritism in leadership episodes. This emerged in the fact that they were concerned with visibility and conduct before engaging in favouritism. Our findings illustrate a bricolage of ethical justifications for favouritism, namely utilitarian, justice, and relational. Such findings suggest the ethical ambiguity that lies at the heart of leadership as a concept and a practice
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