Improved Polyakov-loop potential for effective models from functional calculations

We investigate the quark backreaction on the Polyakov loop and its impact on the thermodynamics of quantum chromodynamics. The dynamics of the gluons generating the Polyakov-loop potential is altered by the presence of dynamical quarks. However, this backreaction of the quarks has not yet been taken into account in Polyakov-loop extended model studies. In the present work, we show within a 2+1 flavour Polyakov-quark-meson model that a quark-improved Polyakov-loop potential leads to a smoother transition between the low-temperature hadronic phase and the high-temperature quark-gluon plasma phase. In particular, we discuss the dependence of our results on the remaining uncertainties that are the critical temperature and the parametrisation of the Polyakov-loop potential as well as the mass of the sigma-meson.Comment: 19 pages, 25 figures; version published in Phys. Rev.

Structural relaxation of nanocrystalline PdAu alloy: Probing the spectrum of potential barriers

A commonality between nanocrystalline metals and metallic glasses is their dependence of structure and properties upon preparation history and postprocessing. Depending on preparation conditions, stored excess enthalpy and volume—relative to the crystalline ground state—can vary significantly. Annealing of material states of elevated enthalpy or volume induces structural relaxation and concomitant depletion of excess energy and volume. We analyzed the kinetics of volume relaxation in nanocrystalline PdAu alloys by partitioning the overall process into a set of independent and parallel reactions for arbitrary time-temperature protocols. The obtained spectra of kinetic parameters imply a complex relaxation behavior that violates time-temperature superposition and time aging-time superposition. The analysis will enable to reconstruct the effective energy landscape underlying the relaxation dynamics

Structural relaxation of nanocrystalline PdAu alloy: Mapping pathways through the potential energy landscape

Preparation history and processing have a crucial influence on which configurational state material systems assume. Glasses and nanocrystalline materials usually reside in nonequilibrium states at room temperature, and as a consequence, their thermodynamic, dynamical, and physical properties change with time—even years after manufacture. Such changes, entitled aging or structural relaxation, are all manifestations of paths taken in the underlying potential energy landscape. Since it is highly multidimensional, there is a need to reduce complexity. Here, we demonstrate how to construct a one-dimensional pathway across the energy landscape using strain/volume as an order parameter. On its way to equilibrium, we map the system’s release of energy by calorimetry and the spectrum of barrier heights by dilatometry. The potential energy of the system is reduced by approximately B during relaxation, whereas the crossing of saddle points requires activation energies in the order of 1eV/atom relative to the energy minima. As a consequence, the system behaves as a bad global minimum finder. We also discovered that aging is accompanied by a decrease in the non-ergodicity parameter, suggesting a decline in density fluctuations during aging

The 3-phase-model of dyadic adaptation to dementia: why it might sometimes be better to be worse

In the next years and decades, the number of old spousal dyads having to deal with the onset and progression of dementia in one partner will increase significantly. Existing research indicates that caregiving for an ill spouse is related to decreased caregiver well-being and high levels of caregiver stress. In this theoretical paper, we argue that three aspects deserve additional theoretical and empirical attention: (a) Some spousal caregivers seem to exhibit stable pattern of individual well-being, (b) dyads may be able to adapt their ways of supporting each other to maintain a maximum of dyadic autonomy, and (c) the progression of the dementia increasingly compromising the individual autonomy is likely to require different behaviors and skills of the dyad to achieve high levels of dyadic well-being. We suggest a 3-phase-model of dyadic adaptation to dementia-related losses of patients' individual autonomy and discuss adaptive processes in three phases of dementia that may allow stable levels of well-being in caregivers over time. Thereby, our model can integrate existing findings and theories and allows deriving areas of future researc

A new method for the estimation of cooling and denudation rates using paramagnetic centers in quartz: a case study on the Eldzhurtinskiy Granite, Caucasus

We present a new method for the assessment of the most recent cooling and denudation rates using paramagnetic centers in quartz measured by electron spin resonance (ESR) spectroscopy. These centers have a relatively low thermal stability. For cooling rates of 40° and 1000°C Myr−1, effective closure temperatures vary between 55° and 82°C (Ti center) and 49° and 64°C (Al center), respectively. Samples were collected from two cores that were drilled into the Eldzhurtinskiy Granite, which has an emplacement age of ∼2 Ma as measured by U/Pb analyses of zircons. One 1500 m core was taken from a drill hole into the dome of the granite, a second core of 4000 m from a drill hole at the base of the Baksan Valley. Our results yield cooling rates of between 160 and 250°C Myr−1 for the upper core and between 570° and 600°C Myr−1 for the lower core; the corresponding denudation rates are ∼2.5 (upper core) and 5.5mm a−1 (lower core). The shape of the temperature profile of the lower core indicates recent erosion. When fitting the temperature data with a two-dimensional heat-transfer model, we obtain a net denudation rate of ∼10 mm a−1 and cooling rates in the range of 500°C Myr−1, thus confirming the cooling rates estimated by ESR. However, the ESR denudation rates underestimate the erosion rate of the Baksan Valley because the geothermal gradient is not equilibrated between the surface and the depth of the annihilation temperatures, 950 and 1800 m for the Al and Ti centers, respectively. We conclude that ESR measurements of paramagnetic centers in quartz will allow the reconstruction of landscape dynamics for the past 10–1000 kyr and that in conjunction with U/Pb, fission track, and Ar/Ar analyses it will be possible to develop dynamic models for Quaternary tectonic movements

Dementia caregiving in spousal relationships: a dyadic perspective

Objectives: The number of couples facing a dementia diagnosis for one partner of the spousal dyad increases. Spousal caregiving can be a highly stressful experience associated with negative caregiver outcomes such as depression and poorer immune function. However, surprisingly little is known about how the illness and the required care effects patient’s well-being and relational changes experienced by afflicted couples. The aim of this study was to provide a literature review on how the dyadic perspective is taken into account and on how dementia effects both parts of the dyad. Methods: In order to outline findings about individual and dyadic well-being of affected couples, we conducted a literature search to review the three types of studies. First, studies focusing on one partner’s perspective, usually the perspective of the caregiver; second, studies including the caregiver’s and partially the care receiver’s view; third, studies directly referring to both partners’ perspectives. Results: The majority of studies neglect the individual with dementia by exclusively assessing caregiver variables or only indirectly including patients’ characteristics. Very few studies embrace dyadic and relational variables to execute how both partners experience the illness, spousal caregiving, and changes in the relationship. Despite the arguable validity of self reports of individuals with dementia, some studies demonstrated the usefulness of including both partners’ perspectives. Discussion: Results indicate the urgent need of integrating the perspective of the individual with dementia to improve the understanding of the effects of dementia caregiving

Light-cone distribution amplitudes of the baryon octet

We present results of the first ab initio lattice QCD calculation of the normalization constants and first moments of the leading twist distribution amplitudes of the full baryon octet, corresponding to the small transverse distance limit of the associated S-wave light-cone wave functions. The P-wave (higher twist) normalization constants are evaluated as well. The calculation is done using $N_f=2+1$ flavors of dynamical (clover) fermions on lattices of different volumes and pion masses down to 222 MeV. Significant SU(3) flavor symmetry violation effects in the shape of the distribution amplitudes are observed.Comment: Update to the version published in JHE

Revealing Grain Boundary Sliding from Textures of a Deformed Nanocrystalline Pd–Au Alloy

Employing a recent modeling scheme for grain boundary sliding [Zhao et al. Adv. Eng. Mater. 2017, doi:10.1002/adem.201700212], crystallographic textures were simulated for nanocrystalline fcc metals deformed in shear compression. It is shown that, as grain boundary sliding increases, the texture strength decreases while the signature of the texture type remains the same. Grain boundary sliding affects the texture components differently with respect to intensity and angular position. A comparison of a simulation and an experiment on a Pd–10 atom % Au alloy with a 15 nm grain size reveals that, at room temperature, the predominant deformation mode is grain boundary sliding contributing to strain by about 60%