Closed-shell properties of 24^{24}O with {\em ab initio} coupled-cluster theory

We present an \emph{ab initio} calculation of spectroscopic factors for neutron and proton removal from $^{24}$O using the coupled-cluster method and a state-of-the-art chiral nucleon-nucleon interaction at next-to-next-to-next-to-leading order. In order to account for the coupling to the scattering continuum we use a Berggren single-particle basis that treats bound, resonant, and continuum states on an equal footing. We report neutron removal spectroscopic factors for the $^{23}$O states $J^{\pi} = 1/2^+$, $5/2^+$, $3/2^-$ and $1/2^-$, and proton removal spectroscopic factors for the $^{23}$N states $1/2^-$ and $3/2^-$. Our calculations support the accumulated experimental evidence that $^{24}$O is a closed-shell nucleus.Comment: 5 pages, 2 figures, 1 tabl

State-of-the-art research : reflections on a concerted Nordic-Baltic nuclear energy effort

Quite a few hold the view that nuclear energy will have its renaissance in the not too distant future. Technology is, however, a necessary, but not sufficient condition. The needed prerequisites represent a complex issue. With increasing energy demand and depletion of non-renewable energy resources, nuclear will have to prove its role in an increasing energy mix, globally, regionally and often also nationally. Based on its history, experience with coordinated interplay in electricity production from a variety of energy sources, and science engagements, we argue for a future Nordic/Baltic SHOW CASE: A nuclear weapons free and proliferation safe nuclear energy supplier in the region, with a concerted role in competence building and in international ventures, and with focus on operation, safety economy and societal aspects

Effective Interaction Techniques for the Gamow Shell Model

We apply a contour deformation technique in momentum space to the newly developed Gamow shell model, and study the drip-line nuclei 5He, 6He and 7He. A major problem in Gamow shell-model studies of nuclear many-body systems is the increasing dimensionality of many-body configurations due to the large number of resonant and complex continuum states necessary to reproduce bound and resonant state energies. We address this problem using two different effective operator approaches generalized to the complex momentum plane. These are the Lee-Suzuki similarity transformation method for complex interactions and the multi-reference perturbation theory method. The combination of these two approaches results in a large truncation of the relevant configurations compared with direct diagonalization. This offers interesting perspectives for studies of weakly bound systems.Comment: 18 pages, 17 figs, Revtex

Reproducibility of fluorescent expression from engineered biological constructs in E. coli

We present results of the first large-scale interlaboratory study carried out in synthetic biology, as part of the 2014 and 2015 International Genetically Engineered Machine (iGEM) competitions. Participants at 88 institutions around the world measured fluorescence from three engineered constitutive constructs in E. coli. Few participants were able to measure absolute fluorescence, so data was analyzed in terms of ratios. Precision was strongly related to fluorescent strength, ranging from 1.54-fold standard deviation for the ratio between strong promoters to 5.75-fold for the ratio between the strongest and weakest promoter, and while host strain did not affect expression ratios, choice of instrument did. This result shows that high quantitative precision and reproducibility of results is possible, while at the same time indicating areas needing improved laboratory practices.Peer reviewe