Fock space relativistic coupled-Cluster calculations of Two-Valence Atoms

We have developed an all particle Fock-space relativistic coupled-cluster method for two-valence atomic systems. We then describe a scheme to employ the coupled-cluster wave function to calculate atomic properties. Based on these developments we calculate the excitation energies, magnetic hyperfine constants and electric dipole matrix elements of Sr, Ba and Yb. Further more, we calculate the electric quadrupole HFS constants and the electric dipole matrix elements of Sr$^+$, Ba$^+$ and Yb$^+$. For these we use the one-valence coupled-cluster wave functions obtained as an intermediate in the two-valence calculations. We also calculate the magnetic dipole hyperfine constants of Yb$^+$.Comment: 23 pages, 12 figures, 10 tables typos are corrected and some minor modifications in some of the section

Predictable Disruption Tolerant Networks and Delivery Guarantees

This article studies disruption tolerant networks (DTNs) where each node knows the probabilistic distribution of contacts with other nodes. It proposes a framework that allows one to formalize the behaviour of such a network. It generalizes extreme cases that have been studied before where (a) either nodes only know their contact frequency with each other or (b) they have a perfect knowledge of who meets who and when. This paper then gives an example of how this framework can be used; it shows how one can find a packet forwarding algorithm optimized to meet the 'delay/bandwidth consumption' trade-off: packets are duplicated so as to (statistically) guarantee a given delay or delivery probability, but not too much so as to reduce the bandwidth, energy, and memory consumption.Comment: 9 page

A european equivalence scale for public in-kind transfers

This paper introduces a theory-based equivalence scale for public in-kind transfers, which justifies comparison of distributions of extended income (cash income plus the value of public services) between European countries. We demonstrate the usefulness of the proposed equivalence scale in an empirical analysis of the effects of public health care, long-term care, education and childcare expenditure on estimates of income inequality and poverty for 24 European countries. The empirical results show significant effects of public in-kind transfers on the level of income inequality and poverty for all countries. Over the period 2006–2018, inequality and poverty estimates display rather different trends across European countries.This work has been supported by the second Network for the analysis of EU-SILC (Net-SILC2) coordinated by CEPS/INSTEAD (Luxembourg). Financial support from Eurostat, the Norwegian Ministry of Finance, and the Norwegian Research Council (grant number 261985) is gratefully acknowledged

Relativistic many-body calculation of low-energy dielectronic resonances in Be-like carbon

We apply relativistic configuration-interaction method coupled with many-body perturbation theory (CI+MBPT) to describe low-energy dielectronic recombination. We combine the CI+MBPT approach with the complex rotation method (CRM) and compute the dielectronic recombination spectrum for Li-like carbon recombining into Be-like carbon. We demonstrate the utility and evaluate the accuracy of this newly-developed CI+MBPT+CRM approach by comparing our results with the results of the previous high-precision study of the CIII system [Mannervik et al., Phys. Rev. Lett. 81, 313 (1998)].Comment: 6 pages, 1 figure; v2,v3: fixed reference

Computing singularities of perturbation series

Many properties of current \emph{ab initio} approaches to the quantum many-body problem, both perturbational or otherwise, are related to the singularity structure of Rayleigh--Schr\"odinger perturbation theory. A numerical procedure is presented that in principle computes the complete set of singularities, including the dominant singularity which limits the radius of convergence. The method approximates the singularities as eigenvalues of a certain generalized eigenvalue equation which is solved using iterative techniques. It relies on computation of the action of the perturbed Hamiltonian on a vector, and does not rely on the terms in the perturbation series. Some illustrative model problems are studied, including a Helium-like model with $\delta$-function interactions for which M{\o}ller--Plesset perturbation theory is considered and the radius of convergence found.Comment: 11 figures, submitte

What News Outlets do People Have in Mind When They Answer Survey Questions about Trust in "Media?"

While ample research on audience trust in the news media uses survey questions that ask respondents about their trust in a generic "news media,"only scant research has investigated what types of news outlets respondents have in mind when answering such questions. These previous investigations originated mostly in the US and resulted in inconsistent findings. To further investigate this question, we use data from a large-scale survey (N=2,337), collected in Sweden, including both general media trust measures and specific measures about trust in 20 mainstream and nonmainstream news outlets. The results demonstrate that our respondents seemingly averaged across all mainstream sources when they formed their general evaluations of the news media's trustworthiness

State-insensitive trapping of Rb atoms: linearly versus circularly polarized lights

We study the cancellation of differential ac Stark shifts in the 5s and 5p states of rubidium atom using the linearly and circularly polarized lights by calculating their dynamic polarizabilities. Matrix elements were calculated using a relativistic coupled-cluster method at the single, double and important valence triple excitations approximation including all possible non-linear correlation terms. Some of the important matrix elements were further optimized using the experimental results available for the lifetimes and static polarizabilities of atomic states. "Magic wavelengths" are determined from the differential Stark shifts and results for the linearly polarized light are compared with the previously available results. Possible scope of facilitating state-insensitive optical trapping schemes using the magic wavelengths for circularly polarized light are discussed. Using the optimized matrix elements, the lifetimes of the 4d and 6s states of this atom are ameliorated.Comment: 13 pages, 13 tables and 4 figure

Effect of thermal aging on microstructure and carbides of SA508/Alloy 52 dissimilar metal weld

A narrow-gap SA508/Alloy 52 dissimilar metal weld (DMW) mock-up, fully representative of an actual nuclear component, was investigated in this work. The microstructure and carbides formed in the low alloy steel fusion boundary (FB) and heat affected zone (HAZ) can act as brittle fracture initiators and could influence the brittle fracture behavior. However, the amount of information available in the open literature on the microstructural changes and carbide formation in DMW occurring upon post-weld heat treatment and long-term thermal aging is very limited. The microstructure and carbide type, morphology and size in the carbide precipitation zone (CPZ, up to 1.5 μm from FB), carbon depletion zone (CDZ, up to 40–50 μm from FB) and HAZ (up to 2 mm from FB) of the plant-relevant DMW in post-weld heat-treated and thermally-aged (400 \ub0C for 15,000 h, corresponding to 90 years of operation) conditions were analyzed with analytical electron microscopy, wide-angle X-ray scattering and atom probe tomography. Long-term thermal aging increases the microhardness peak close to the FB, triples the width of the CPZ and coarsens the carbide size in the HAZ (up to a magnitude). There is no evidence of a significant phosphorus segregation to grain boundaries due to thermal aging

An Improved Technique for Determining the Equation of State of Concrete and Geological Materials

Concrete is an extremely versatile building material. It is being used extensively as a building material for defense and civilian structures and infrastructure. In defense applications, concrete is often used as the primary structural component in facilities that are hardened against enemy attack, especially projectiles that can impact the structure with a high rate of speed and a large explosive force. The high strain and strain rate of such an event make it imperative to know the mechanical behavior of concrete at these elevated loads in order to properly design the appropriate weapons that can penetrate such structures, or, conversely for defensive purposes, design the structure to withstand and survive such an event. Similar conditions can occur in the civilian sector. Depending on the geographical location of these structures, they can be exposed to similar conditions as some of the defense facilities. For example, an earthquake is typically composed of several different types of shock waves [1]. The exact nature of the shock waves is dependent on the nature of the earthquake source

No country for old men? Increasing the retirement age in the Armed Forces

An ageing workforce due to low fertility rates and higher life expectancies challenges modern industrialized economies. To secure economic welfare and the balance of public budgets, governments worldwide implement reforms to increase the retirement age. This trend towards higher retirement age confronts a defense sector that for centuries has been in search of an age structure characterized by ‘youth and vigor’. We study the economic gains to society from increasing the special retirement age for military personnel in the Norwegian Armed Forces. By combining the literatures on pension, personnel, and military economics, we identify mechanisms crucial to the outcome of a special retirement age reform. Monte Carlo simulation is applied to illustrate the potential impact on the economic net gains of uncertain variables. We find that an increase in the retirement age provides substantial net benefits to society, even under fairly negative assumptions about the consequences for retention, motivation and efforts, and the value of elderly personnel in the Armed Forces