Background: The triple-alpha reaction is the key to our understanding about the nucleosynthesis and the observed abundance of 12 C in stars. The theory of this process is well established at high temperatures but rather ambiguous in the low temperature regime where measurements are impossible. Purpose: Develop a new three-body method, which tackles properly the scattering boundary condition for three charged particles and takes into account both the resonant and the non-resonant reaction mechanisms on the same footing, to compute the triple-alpha reaction rate at low temperatures. Methods: We combine the R-matrix expansion, the R-matrix propagation method, and the screening technique in the hyperspherical harmonics basis. Results: Both the 2 + 1 bound state and the 0 + 2 resonant state in 12 C are well reproduced. We also study the cluster structure of these states. We calculate the triple-alpha reaction rate for T = 0.01 − 0.1 GK. Conclusions: We obtain the same rate as NACRE for temperatures above 0.07 GK, but the new rate is largely enhanced at lower temperatures (≈ 10 12 at 0.02 GK). The differences are caused by the direct capture contribution to the reaction when three alpha particles can not reach the resonant energies.

With the increasing interest in using (d,p) transfer reactions to extract structure and astrophysical information, it is important to evaluate the accuracy of common approximations in reaction theory. Starting from the zero-range adiabatic wave model, which takes into account deuteron breakup in the transfer process, we evaluate the importance of the finite range of the n − p interaction in calculating the adiabatic deuteron wave (as in Johnson and Tandy) as well as in evaluating the transfer amplitude. Our study covers a wide variety of targets as well as a large range of beam energies. Whereas at low beam energies finite range effects are small (below 10%), we find these effects to become important at intermediate energies (20 MeV/u) calling for an exact treatment of finite range in the analysis of (d,p) reactions measured at fragmentation facilities.

BackgroundHospital nurses are exposed to various work-related factors that may be associated with increased risk of developing different mental disorders. Empirical evidence on the prevalence and correlates of individual mental health problems such as stress, anxiety and depression is widely reported, while a combined pattern of these conditions is unknown. This study aims to examine the co-occurrence of stress, anxiety and depression among clinical nurses, and to explore socio-demographic characteristics of, and working conditions experienced by, nurses that may be associated with these three mental health conditions.MethodsA cross-sectional study was implemented in one tertiary hospital in Hanoi city, Vietnam, from May to September 2015. A self-reported questionnaire including a short version of the Depression, Anxiety and Stress scale 21 items and questions on demographic and work-related characteristics was delivered to 787 registered nurses. 600 completed questionnaires was used in the final analysis (76.2% response rate). The two-step clustering analysis was performed to identify sub groups. Chi square test and post hoc ANOVA analysis with Bonferroni correction were used to examine differences in psychological status, demographic characteristics and working conditions among the clusters (two-tailed p < 0.05).ResultsThe prevalence of self-reported stress, anxiety and depression were 18.5%, 39.8% and 13.2%, respectively. 45.3% participants reported symptoms of at least one mental disorder, 7.3% had all three. Nurses in the first cluster (high prevalence of mental disorders), had high task demand and conflict at work with low job control and reward. The second cluster nurses (moderate percentage of mental strain) were significantly older and in marital relationship, high task demand and job control, and presence of chronic diseases. The lowest proportion of self-perceived mental disorders were observed in the cluster three who were younger and had fewer years of services, moderate task demand and low job control and better physical health in comparison with those in the other two clusters (p < 0.05).ConclusionsStress, anxiety and depression were prevalent among clinical nurses. Heterogeneity in demographic characteristics and working conditions were observed across clusters with different patterns of mental disorders. Institutional effort should be emphasized to support nurses in their career development to reduce psychological strains.Electronic supplementary materialThe online version of this article (10.1186/s13033-018-0257-4) contains supplementary material, which is available to authorized users.

The14 C(n, γ) 15 C reaction plays an important role in inhomogeneous big bang models. In [N. K. Timofeyuk et al., Phys. Rev. Lett. 96, 162501 (2006)] it was shown that the 14 C(n, γ) 15 C radiative capture at astrophysically relevant energies is peripheral reaction, i.e. the overall normalization of its cross section is determined by the asymptotic normalization coefficient (ANC) for 15 C → 14 C+n. Here we present new measurements of the 14 C(d, p) 15 C differential cross sections at deuteron incident energy of 17.06 MeV and the analysis to determine the ANCs for neutron removal from the ground and first excited states of 15 C. The results are compared with the previous estimations.

Aging, often considered a result of random cellular damage, can be accurately estimated using DNA methylation profiles, the foundation of pan-tissue epigenetic clocks. Here, we demonstrate the development of universal pan-mammalian clocks, using 11,754 methylation arrays from our Mammalian Methylation Consortium, which encompass 59 tissue types across 185 mammalian species. These predictive models estimate mammalian tissue age with high accuracy (r > 0.96). Age deviations correlate with human mortality risk, mouse somatotropic axis mutations and caloric restriction. We identified specific cytosines with methylation levels that change with age across numerous species. These sites, highly enriched in polycomb repressive complex 2-binding locations, are near genes implicated in mammalian development, cancer, obesity and longevity. Our findings offer new evidence suggesting that aging is evolutionarily conserved and intertwined with developmental processes across all mammals.

A new three-body method is used to compute the rate of the triple-alpha capture reaction, which is the primary source of 12C in stars. In this Letter, we combine the Faddeev hyperspherical harmonics and the R-matrix method to obtain a full solution to the three-body α+α+α continuum. Particular attention is paid to the long-range effects caused by the pairwise Coulomb interactions. The new rate agrees with the Nuclear Astrophysics Compilation of Reaction rates for temperatures greater than 0.07 GK, but a large enhancement at lower temperature is found (≈10(12) at 0.02 GK). Our results are compared to previous calculations where additional approximations were made. We show that the new rate does not significantly change the evolution of stars around one solar mass. In particular, such stars still undergo a red-giant phase consistent with observations, and no significant differences are found in the final white dwarfs.

The dispersive optical-model is applied to transfer reactions. A systematic study of (d, p) reactions on closed-shell nuclei using the finite-range adiabatic reaction model is performed at several beam energies and results are compared to data as well as to predictions using a standard global optical-potential. Overall, we find that the dispersive optical-model is able to describe the angular distributions as well as or better than the global parameterization. In addition, it also constrains the overlap function. Spectroscopic factors extracted using the dispersive optical-model are generally lower than those using standard parameters, exhibit a reduced dependence on beam energy, and are more in line with results obtained from (e, e ′ p) measurements.

The PMTs of the CMS Hadron Forward calorimeter were found to generate a large size signal when their windows were traversed by energetic charged particles. This signal, which is due toCerenkov light production at the PMT window, could interfere with the calorimeter signal and mislead the measurements. In order to find a viable solution to this problem, the response of four different types of PMTs to muons traversing their windows at different orientations is measured at the H2 beam-line at CERN. Certain kinds of PMTs with thinner windows show significantly lower response to direct muon incidence. For the four anode PMT, a simple and powerful algorithm to identify such events and recover the PMT signal using the signals of the quadrants without window hits is also presented. For the measurement of PMT responses toCerenkov light, the Hadron Forward calorimeter signal was mimicked by two different setups in electron beams and the PMT performances were compared with each other. Superior performance of particular PMTs was observed.