Boundary versus bulk behavior of time-dependent correlation functions in one-dimensional quantum systems

We study the influence of reflective boundaries on time-dependent responses of one-dimensional quantum fluids at zero temperature beyond the low-energy approximation. Our analysis is based on an extension of effective mobile impurity models for nonlinear Luttinger liquids to the case of open boundary conditions. For integrable models, we show that boundary autocorrelations oscillate as a function of time with the same frequency as the corresponding bulk autocorrelations. This frequency can be identified as the band edge of elementary excitations. The amplitude of the oscillations decays as a power law with distinct exponents at the boundary and in the bulk, but boundary and bulk exponents are determined by the same coupling constant in the mobile impurity model. For nonintegrable models, we argue that the power-law decay of the oscillations is generic for autocorrelations in the bulk, but turns into an exponential decay at the boundary. Moreover, there is in general a nonuniversal shift of the boundary frequency in comparison with the band edge of bulk excitations. The predictions of our effective field theory are compared with numerical results obtained by time-dependent density matrix renormalization group (tDMRG) for both integrable and nonintegrable critical spin-$S$ chains with $S=1/2$, $1$ and $3/2$.Comment: 20 pages, 12 figure

Prospects and status of quark mass renormalization in three-flavour QCD

We present the current status of a revised strategy to compute the running of renormalized quark masses in QCD with three flavours of massless O(a) improved Wilson quarks. The strategy employed uses the standard finite-size scaling method in the Schr\"odinger functional and accommodates for the non-perturbative scheme-switch which becomes necessary at intermediate renormalized couplings as discussed in [arXiv:1411.7648].Comment: 7 pages, 3 figures, 1 table; Proceedings of the 33rd International Symposium on Lattice Field Theory, 14-18 July 2015, Kobe, Japa

Open charm meson in nuclear matter at finite temperature beyond the zero range approximation

The properties of open charm mesons, $D$, $\bar D$, $D_s$ and $\bar D_s$ in nuclear matter at finite temperature are studied within a self-consistent coupled-channel approach. The interaction of the low lying pseudoscalar mesons with the ground state baryons in the charm sector is derived from a $t$-channel vector-exchange model. The in-medium scattering amplitudes are obtained by solving the Lippmann-Schwinger equation at finite temperature including Pauli blocking effects, as well as $D$, $\bar D$, $D_s$ and $\bar D_s$ self-energies taking their mutual influence into account. We find that the in-medium properties of the $D$ meson are affected by the $D_s$-meson self-energy through the intermediate $D_s Y$ loops coupled to $DN$ states. Similarly, dressing the $\bar{D}$ meson in the $\bar{D}Y$ loops has an influence over the properties of the $\bar{D}_s$ meson.Comment: 23 pages, 9 figures, 2 table

Working conditions, health and retirement intentions: a case study of truck drivers

Purpose. Being a professional truck driver implies prolonged exposure to physical and psychosocial risks, which can affect health and work ability in the short and long term. The purpose of this paper is to examine the role of working conditions in truck drivers’ perceived health and retirement intentions in a Portuguese transportation company. Design/methodology/approach. Using ergonomic work analysis (EWA), this study incorporates document analysis, observation and 16 interviews. Content analysis is applied to interviews’ transcripts. Findings. In line with previous research, drivers acknowledged their activity as physically demanding (e.g. static postures, repetitive movements, heavy lifting) and psychologically demanding (e.g. high time pressure, lack of control, lack of work–family balance). Despite that, drivers report themselves to be in good health, with only some complaints related to back and knee pain. However, hard working conditions associated with ageing can contribute to gradual health deterioration, leading them to desire to retire before the legal retirement age. Practical implications. The company can promote drivers’ health by creating a unit to provide psychosocial support and career orientation, improving the mentoring programme, and investing in training on occupational risk prevention. Originality/value. This study is the first to use EWA to examine the impact of the complex relationship between truck drivers’ work and health in their retirement intentions, adopting a temporal perspective.info:eu-repo/semantics/acceptedVersio

Bulge RR Lyrae stars in the VVV tile b201\textit{b201}

The VISTA Variables in the V\'ia L\'actea (VVV) Survey is one of the six ESO public surveys currently ongoing at the VISTA telescope on Cerro Paranal, Chile. VVV uses near-IR ($ZYJHK_{\rm s}$) filters that at present provide photometry to a depth of $K_{\rm s} \sim 17.0$ mag in up to 36 epochs spanning over four years, and aim at discovering more than 10$^6$ variable sources as well as trace the structure of the Galactic bulge and part of the southern disk. A variability search was performed to find RR Lyrae variable stars. The low stellar density of the VVV tile $\textit{b201}$, which is centered at ($\ell, b$) $\sim$ ($-9^\circ, -9^\circ$), makes it suitable to search for variable stars. Previous studies have identified some RR Lyrae stars using optical bands that served to test our search procedure. The main goal is to measure the reddening, interstellar extinction, and distances of the RR Lyrae stars and to study their distribution on the Milky Way bulge. A total of 1.5 sq deg were analyzed, and we found 39 RR Lyrae stars, 27 of which belong to the ab-type and 12 to the c-type. Our analysis recovers all the previously identified RR Lyrae variables in the field and discovers 29 new RR Lyrae stars. The reddening and extinction toward all the RRab stars in this tile were derived, and distance estimations were obtained through the period--luminosity relation. Despite the limited amount of RR Lyrae stars studied, our results are consistent with a spheroidal or central distribution around $\sim 8.1$ and $\sim 8.5$ kpc. for either the Cardelli or Nishiyama extinction law.Comment: 10 pages, 8 figures, accepted for publication in Astronomy and Astrophysic

Dynamically generated open charmed baryons beyond the zero range approximation

The interaction of the low lying pseudo-scalar mesons with the ground state baryons in the charm sector is studied within a coupled channel approach using a t-channel vector-exchange driving force. The amplitudes describing the scattering of the pseudo-scalar mesons off the ground-state baryons are obtained by solving the Lippmann--Schwinger equation. We analyze in detail the effects of going beyond the $t=0$ approximation. Our model predicts the dynamical generation of several open charmed baryon resonances in different isospin and strangeness channels, some of which can be clearly identified with recently observed states.Comment: 7 figures, 8 table

The redshift and broad band spectral energy distribution of NRAO 150

Context. NRAO 150 is one of the brightest radio and mm AGN sources on the northern sky. It has been revealed as an interesting source where to study extreme relativistic jet phenomena. However, its cosmological distance has not been reported so far, because of its optical faintness produced by strong Galactic extinction. Aims. Aiming at measuring the redshift of NRAO 150, and hence to start making possible quantitative studies from the source. Methods. We have conducted spectroscopic and photometric observations of the source in the near-IR, as well as in the optical. Results. All such observations have been successful in detecting the source. The near-IR spectroscopic observations reveal strong H$\alpha$ and H$\beta$ emission lines from which the cosmological redshift of NRAO 150 ($z=1.517\pm0.002$) has been determined for the first time. We classify the source as a flat-spectrum radio-loud quasar, for which we estimate a large super-massive black-hole mass $\sim5\times 10^{9} \mathrm{M_\odot}$. After extinction correction, the new near-IR and optical data have revealed a high-luminosity continuum-emission excess in the optical (peaking at $\sim2000$\,\AA, rest frame) that we attribute to thermal emission from the accretion disk for which we estimate a high accretion rate, $\sim30$\,% of the Eddington limit. Conclusions. Comparison of these source properties, and its broad-band spectral-energy distribution, with those of Fermi blazars allow us to predict that NRAO 150 is among the most powerful blazars, and hence a high luminosity -although not detected yet- $\gamma$-ray emitter.Comment: 8 pages, 4 figure

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

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