The Role of Fermions in Bubble Nucleation

We present a study of the role of fermions in the decay of metastable states of a scalar field via bubble nucleation. We analyze both one and three-dimensional systems by using a gradient expansion for the calculation of the fermionic determinant. The results of the one-dimensional case are compared to the exact results of previous work.Comment: 15 pages, revtex, 9 figure

Developing a site-conditions map for seismic hazard Assessment in Portugal

The evaluation of site effects on a broad scale is a critical issue for seismic hazard and risk assessment, land use planning and emergency planning. As characterization of site conditions based on the shear-wave velocity has become increasingly important, several methods have been proposed in the literature to estimate its average over the first thirty meters (Vs30) from more extensively available data. These methods include correlations with geologic-geographic defined units and topographic slope. In this paper we present the first steps towards the development of a site–conditions map for Portugal, based on a regional database of shear-wave velocity data, together with geological, geographic, and lithological information. We computed Vs30 for each database site and classified it according to the corresponding geological-lithological information using maps at the smallest scale available (usually 1:50000). We evaluated the consistency of Vs30 values within generalized-geological classes, and assessed the performance of expedient methodologies proposed in the literature

Is age just a number? The impact of age-diversity practices and workers' age on health and well-being

Workforces across the world are ageing. Research has been focusing on how Human Resources Management (HRM) can develop and promote sustainable careers for workers of all ages (e.g. Kooij et al., 2013; Schalk et al., 2010; Truxillo, Cadiz, & Hammer, 2015). This study tests two moderation hypotheses: age moderates the effect of perceived age-diversity practices (1) on perceived health and (2) on well-being. Human Resources (HR) practices that consider the needs, goals and preferences of workers of all ages – age-diversity practices – can be a strategy to ensure workers’ well-being and health. Perceived age-diversity practices refer to the degree to which individuals perceive that workers of all ages receive non-discriminatory treatment in terms of organisational practices, policies and procedures (Boehm, Kunze, & Bruch, 2014; Kunze, Boehm, & Bruch, 2013). Organisations can implement these practices to support workers’ health and well-being over time, by adjusting the physical work environment (e.g., ergonomic aspects) and fostering knowledge and skills. Age can have an important role in the impact of perceived age-diversity practices on health and well-being. The assumption is that these practices are especially important for older workers as they are more likely to experience health limitations due to the ageing process (Hansson, DeKoekkoek, Neece, & Patterson, 1997), and they are frequently the target of age discrimination in the workplace (e.g., Finkelstein, Burke, & Raju, 1995; Posthuma & Campion, 2009). A sample of 410 participants aged between 19 and 67 years old (M = 37.74, SD = 12.93) answered to a questionnaire with an on-line and a paper version. The moderation hypotheses were tested by Multiple Linear Regression using PROCESS macro for SPSS (Hayes, 2012). Findings supported the first hypothesis, suggesting that as increases age, also increases the effect of perceived age-diversity practices on perceived health, which means that as age increased, this relationship became more important. The second hypothesis was not supported, because the moderator effect of age was not significant. However, perceived age-diversity practices had a significant main effect on well-being, emphasising the importance of these practices to retain all workers, regardless of their age. These findings suggest that organisations should develop age-diversity practices to improve the well-being of workers of all ages, and that they could be particularly relevant for older workers’ health.info:eu-repo/semantics/acceptedVersio

‘What could make me stay at work’: Retirement transition profiles

Aging populations pose a persistent challenge to the sustainability of public pension systems. To tackle these financial pressures, many countries strengthen the incentives to work by increasing the statutory retirement age and reducing early retirement benefits. These policy reforms make retirement a topic of utmost importance for individuals, organizations, and societies. Although retirement predictors are already a widely studied topic in the literature, there is still much to investigate about why people decide to retire when they do. In particular, the role of work-related variables in the retirement decision-making process is still not fully understood. Thus, the aim of this study was to examine how individual and work factors influence retirement timing (early, on-time, and later retirement). Forty-one interviews were conducted, and data were subjected to content analysis. The inter-relationship between the multiple categories was analyzed by a Multiple Correspondence Analysis (MCA) combined with Cluster Analysis. Results revealed three distinct profiles, which allowed us to group the participants into three clusters. The stay factors profile (e.g., high positive experiences at work, having no dependents, the spouse/partner not being retired) was associated with later retirement. These results can be important for organizations that want and need to retain the best senior talents, by acknowledging that positive experiences at work are associated with older workers’ desire of postponing retirement.info:eu-repo/semantics/acceptedVersio

Age-diversity practices and retirement preferences among older workers: a moderated mediation model of work engagement and work ability

To meet the demographic changes, organizations are challenged to develop practices that retain older workers and encourage them to postpone retirement. The purpose of this paper is to examine the role of human resources (HR) practices in retirement preferences of older workers. Drawing on theories on lifespan development and social exchange, we suggest that organizations can facilitate longer working lives by implementing bundles of HR practices that are sensitive to age-related changes in workers’ skills, preferences, and goals – i.e., age-diversity practices. We posit that age-diversity practices are positively related to work engagement that, in turn, relates to the preference for retiring later. We further suggest that work ability moderates the relationship between age-diversity practices and work engagement. Finally, we propose a moderated mediation model in which the mediated relationship is moderated by work ability. A sample of 232 older Portuguese workers completed a questionnaire. Hypotheses were tested by using structural equation modeling (SEM). Findings show that work engagement completely mediates the relationship between age-diversity practices and the preference for early or late retirement. Moreover, this mediating relationship is more important for those workers who experience low work ability. Results further demonstrate that the effect of age-diversity practices on the preference for retiring later via work engagement is stronger for lower levels of work ability. This study highlights the organizational role in promoting longer and healthier working lives through the implementation of age-supportive HR practices.info:eu-repo/semantics/publishedVersio

Retaining an age-diverse workforce through HRM: the mediation of work engagement and affective commitment

An aging population and an increasingly age-diverse workforce exemplify the complex challenge that age represents for most managers today. For that reason, research has shown the importance of designing and implementing human resources (HR) practices that meet age-related differences in workers’ motives and needs. Drawing on signaling and social exchange theories, the current study investigated a first stage moderated parallel multiple mediation model. We examined the mediating roles of work engagement and affective commitment in the relationship between age-diversity practices and turnover intention, as well as the moderating role of work centrality in these mediated relationships. Using a sample of 802 Portuguese workers, the study supported the parallel multiple mediation hypotheses. Further, the findings revealed that work centrality moderated the relationship between age-diversity practices and turnover intention via work engagement, but not via affective commitment. Age-diversity practices may motivate those workers who place less importance on work to be more engaged, which, in turn, reduces their intentions to leave the organization. Moreover, all workers, regardless of the importance that work plays in their life, are more emotionally attached to the organization and more willing to stay when there are age-diversity practices. Thus, to retain a healthy and productive age-diverse workforce, organizations should implement age-diversity practices. Empirical and practical implications are discussed.info:eu-repo/semantics/acceptedVersio

Development of Ag/TiO2NM-treated leathers with antibacterial activity for footwear industry

This work aims to contribute to the industrial development of safer and advanced leathers using nanomaterials (NMs) that are based in titanium oxide doped with silver (Ag-TiO2NMs). These NMs present an ecological alternative to volatile organic biocides and organic solvents, frequently used nowadays. Safe application of these NMs brings added value to footwear and leather products and reduces the bulk chemical wide pollution. These newly developed materials are expected to be useful for footwear manufacturing (for common or professional use) with advanced protection against bacteria and fungus, which are the most common cause of feet infections, for either common or professional use. Hence, the main aim of this work is the improvement of leather footwear in order to overcome the feet infections and ensure minimum risk of human skin penetration. In order to accomplish the main aim, the cytotoxicity, antimicrobial and self-cleaning properties of leather surface, treated with Ag-TiO2NMs by sputtering deposition were assessed. The Ag-TiO2 coatings were deposited onto leather substrates by DC-pulsed reactive magnetron sputtering using two targets, Ti and Ag, in an Ar + O2 atmosphere. Compositional analysis was achieved by X-ray energy dispersive spectrometry (EDX). Contact angle of the coatings was measured and the results show that with the introduction of silver in TiO2 microstructure promotea an increase in hydrophobicity. The antibacterial activity of the samples was assessed by agar diffusion method and the results point out to a silver antibacterial activity

Influence of albumin on the tribological behavior of Ag-Ti (C, N) thin films for orthopedic implants

With the increase of elderly population and the health problems arising nowadays, such as cancer, knee and hip joint prostheses are widely used worldwide. It is estimated that 20% of hip replacement surgeries simply fail after 5 years, due to wear loosening, instability and infection. In this paper it is reported the study of advanced materials with the ability to overcome some of these drawbacks. The development of ceramic coatings, based on carbonitrides of transition metals, such as TiCN, doped with silver, Ag, may represent an effective solution. Thin films of Ag-TiCN were produced by dc reactive magnetron sputtering with silver contents ranging from 4 to 8 at. %. The physical, chemical, structural, morphological/topographical, mechanical and tribological properties were evaluated. The tribological tests were performed in a unidirectional wear simulator, pin on disc, being the antagonists of a ceramic Al2O3 ball, and using simulate body fluids as lubricant. Hank’s Balanced Salt Solution (HBSS) and bovine serum albumin (BSA) in HBSS were chosen, in order to evaluate the lubrication ability of the solution containing the protein, albumin. The results revealed that the coatings with Ag content ranging from 4 to 8 at. %, were the most promising, as the tribological properties were superior to the results reported by other authors, which also developed Ag-TiCN coatings containing similar Ag contents and using similar test conditions. The presence of albumin lead to a lower wear in all the test conditions, and this enhancement was higher in the hydrophobic surfaces.This research is sponsored by FEDER funds through the program COMPETE - Programa Operacional Factores de Competitividade and by National funds through FCT - Fundacao para a Ciencia e a Tecnologia, in the framework of the Strategic Projects PEST-C/FIS/UI607/2011, and PEst-C/EME/UI0285/2011 and under the project, PTDC/CTM/102853/2008

Estudos filogenéticos e de diversidade em Capsicum e sua aplicação na conservação e uso de recursos genéticos das espécies C. frutescens E C. chinense.

No presente trabalho, estudou-se a variabilidade genética de um banco de germoplasma com 115 acessos de C. frutescense 480 de C. chinense visando subsidar ações de conservação e uso dos recursos genéticos.Resumo CBRG 269