Nuclear forces and their impact on neutron-rich nuclei and neutron-rich matter

We review the impact of nuclear forces on matter at neutron-rich extremes. Recent results have shown that neutron-rich nuclei become increasingly sensitive to three-nucleon forces, which are at the forefront of theoretical developments based on effective field theories of quantum chromodynamics. This includes the formation of shell structure, the spectroscopy of exotic nuclei, and the location of the neutron dripline. Nuclear forces also constrain the properties of neutron-rich matter, including the neutron skin, the symmetry energy, and the structure of neutron stars. We first review our understanding of three-nucleon forces and show how chiral effective field theory makes unique predictions for many-body forces. Then, we survey results with three-nucleon forces in neutron-rich oxygen and calcium isotopes and neutron-rich matter, which have been explored with a range of many-body methods. Three-nucleon forces therefore provide an exciting link between theoretical, experimental and observational nuclear physics frontiers.Comment: 28 pages, 13 figures, 1 tabl

Three-nucleon forces and spectroscopy of neutron-rich calcium isotopes

We study excited-state properties of neutron-rich calcium isotopes based on chiral two- and three-nucleon interactions. We first discuss the details of our many-body framework, investigate convergence properties, and for two-nucleon interactions benchmark against coupled-cluster calculations. We then focus on the spectroscopy of 47-56Ca, finding that with both 3N forces and an extended pfg9/2 valence space, we obtain a good level of agreement with experiment. We also study electromagnetic transitions and find that experimental data are well described by our calculations. In addition, we provide predictions for unexplored properties of neutron-rich calcium isotopes.Comment: 15 pages, 22 figures, published versio

Exploring sd-shell nuclei from two- and three-nucleon interactions with realistic saturation properties

We study ground- and excited-state properties of all sd-shell nuclei with neutron and proton numbers 8 <= N,Z <= 20, based on a set of low-resolution two- and three-nucleon interactions that predict realistic saturation properties of nuclear matter. We focus on estimating the theoretical uncertainties due to variation of the resolution scale, the low-energy couplings, as well as from the many-body method. The experimental two-neutron and two-proton separation energies are reasonably well reproduced, with an uncertainty range of about 5 MeV. The first excited 2+ energies also show overall agreement, with a more narrow uncertainty range of about 500 keV. In most cases, this range is dominated by the uncertainties in the Hamiltonian.Comment: 6 pages, 4 figure

Hashing Fuzzing: Introducing Input Diversity to Improve Crash Detection

The utility of a test set of program inputs is strongly influenced by its diversity and its size. Syntax coverage has become a standard proxy for diversity. Although more sophisticated measures exist, such as proximity of a sample to a uniform distribution, methods to use them tend to be type dependent. We use r-wise hash functions to create a novel, semantics preserving, testability transformation for C programs that we call HashFuzz. Use of HashFuzz improves the diversity of test sets produced by instrumentation-based fuzzers. We evaluate the effect of the HashFuzz transformation on eight programs from the Google Fuzzer Test Suite using four state-of-the-art fuzzers that have been widely used in previous research. We demonstrate pronounced improvements in the performance of the test sets for the transformed programs across all the fuzzers that we used. These include strong improvements in diversity in every case, maintenance or small improvement in branch coverage -- up to 4.8% improvement in the best case, and significant improvement in unique crash detection numbers -- between 28% to 97% increases compared to test sets for untransformed programs

Rural Roads: The Challenge of Decentralized Implementation

This paper will review the key elements required for effective decentralized implementation of rural roads programs. It will review the range of options available and the evidence for successful implementation where it exists. Section 2 makes the case for the importance of rural roads and sets out the evidence for the socio-economic benefits. Section 3 addresses the responsibilities for implementation and critical importance of having clarity over network ownership. Section 4 highlights the difficulties of finance, particularly for longer term maintenance, and sets out options for improving allocations and the reliability of receipt for those allocations. Section 5 sets out the project cycle from planning, design, implementation, maintenance and subsequent evaluation. Section 6 summarizes the key issues and highlights the main policy considerations

Viral asthma: implications for clinical practice

The natural history of asthma appears to be driven primarily by the timing and duration of viral respiratory infections. From the very high rate of infections in childhood, to the more sporadic pattern seen in adults, the cycle of acute injury followed by an inefficient repair process helps explain the clinical patterns of asthma severity currently recognized by asthma guidelines. Why the asthmatic host responds to viral injury in a particular way is largely a mystery and the subject of intense investigation. The role of viruses in asthma extends not just to intermittent but to persistent disease, and to both the atopic as well as nonatopic phenotypes. Future therapeutic strategies should include primary prevention via the development of antiviral innate immunity-enhancing vaccines, as well as secondary prevention via the use of antiviral agents, or immunomodulators designed to boost the antiviral response or interrupt the proinflammatory cascade

Inelastic light scattering and the excited states of many-electron quantum dots

A consistent calculation of resonant inelastic (Raman) scattering amplitudes for relatively large quantum dots, which takes account of valence-band mixing, discrete character of the spectrum in intermediate and final states, and interference effects, is presented. Raman peaks in charge and spin channels are compared with multipole strengths and with the density of energy levels in final states. A qualitative comparison with the available experimental results is given.Comment: 5 pages, accepted in J. Phys.: Condens. Matte

How Barred is the NIR Nearby Universe? An analysis using 2MASS

We determine a firm lower limit to the bar fraction of 0.58 in the nearby universe using J+H+Ks-band images for 134 spirals from 2MASS. With a mean deprojected semi-major axis of 5.1 kpc, and a mean deprojected ellipticity of 0.45 this local bar sample lays the ground work for studies on bar formation and evolution at high redshift.Comment: In the proceedings "Penetrating Bars through Masks of Cosmic Dust: The Hubble Tuning Fork strikes a New Note

Spin-dependent WIMP scattering off nuclei

Chiral effective field theory (EFT) provides a systematic expansion for the coupling of WIMPs to nucleons at the momentum transfers relevant to direct cold dark matter detection. We derive the currents for spin-dependent WIMP scattering off nuclei at the one-body level and include the leading long-range two-body currents, which are predicted in chiral EFT. As an application, we calculate the structure factor for spin-dependent WIMP scattering off 129,131Xe nuclei, using nuclear interactions that have been developed to study nuclear structure and double-beta decays in this region. We provide theoretical error bands due to the nuclear uncertainties of WIMP currents in nuclei.Comment: 6 pages, 3 figures, published versio