Seyffart’s Directory of Drug Dosage in Kidney Disease By Günte Seyffart Dustri-Verlag Dr. Karl Feistle, 2011 870 pp, hardcover, US$135.00 ISBN 9783871854002

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The In-Medium Similarity Renormalization Group: A Novel Ab Initio Method for Nuclei

We present a comprehensive review of the In-Medium Similarity Renormalization Group (IM-SRG), a novel ab inito method for nuclei. The IM-SRG employs a continuous unitary transformation of the many-body Hamiltonian to decouple the ground state from all excitations, thereby solving the many-body problem. Starting from a pedagogical introduction of the underlying concepts, the IM-SRG flow equations are developed for systems with and without explicit spherical symmetry. We study different IM-SRG generators that achieve the desired decoupling, and how they affect the details of the IM-SRG flow. Based on calculations of closed-shell nuclei, we assess possible truncations for closing the system of flow equations in practical applications, as well as choices of the reference state. We discuss the issue of center-of-mass factorization and demonstrate that the IM-SRG ground-state wave function exhibits an approximate decoupling of intrinsic and center-of-mass degrees of freedom, similar to Coupled Cluster (CC) wave functions. To put the IM-SRG in context with other many-body methods, in particular many-body perturbation theory and non-perturbative approaches like CC, a detailed perturbative analysis of the IM-SRG flow equations is carried out. We conclude with a discussion of ongoing developments, including IM-SRG calculations with three-nucleon forces, the multi-reference IM-SRG for open-shell nuclei, first non-perturbative derivations of shell- model interactions, and the consistent evolution of operators in the IM-SRG. We dedicate this review to the memory of Gerry Brown, one of the pioneers of many-body calculations of nuclei.Comment: 92 pages, 33 figures, to appear in Physics Report

Is a Trineutron Resonance Lower in Energy than a Tetraneutron Resonance?

We present quantum Monte Carlo calculations of few-neutron systems confined in external potentials based on local chiral interactions at next-to-next-to-leading order in chiral effective field theory. The energy and radial densities for these systems are calculated in different external Woods-Saxon potentials. We assume that their extrapolation to zero external-potential depth provides a quantitative estimate of three- and four-neutron resonances. The validity of this assumption is demonstrated by benchmarking with an exact diagonalization in the two-body case. We find that the extrapolated trineutron resonance, as well as the energy for shallow well depths, is lower than the tetraneutron resonance energy. This suggests that a three-neutron resonance exists below a four-neutron resonance in nature and is potentially measurable. To confirm that the relative ordering of three- and four-neutron resonances is not an artifact of the external confinement, we test that the odd-even staggering in the helium isotopic chain is reproduced within this approach. Finally, we discuss similarities between our results and ultracold Fermi gases.Comment: 6 pages, 5 figures, version compatible with published lette

Signatures of few-body resonances in finite volume

We study systems of bosons and fermions in finite periodic boxes and show how the existence and properties of few-body resonances can be extracted from studying the volume dependence of the calculated energy spectra. Using a plane-wave-based discrete variable representation to conveniently implement periodic boundary conditions, we establish that avoided level crossings occur in the spectra of up to four particles and can be linked to the existence of multi-body resonances. To benchmark our method we use two-body calculations, where resonance properties can be determined with other methods, as well as a three-boson model interaction known to generate a three-boson resonance state. Finding good agreement for these cases, we then predict three-body and four-body resonances for models using a shifted Gaussian potential. Our results establish few-body finite-volume calculations as a new tool to study few-body resonances. In particular, the approach can be used to study few-neutron systems, where such states have been conjectured to exist.Comment: 13 pages, 10 figures, 2 tables, published versio

Effective Nucleon-Nucleon Interaction and Fermi Liquid Theory

We present two novel relations between the quasiparticle interaction in nuclear matter and the unique low momentum nucleon-nucleon interaction in vacuum. These relations provide two independent constraints on the Fermi liquid parameters of nuclear matter. Moreover, the new constraints define two combinations of Fermi liquid parameters, which are invariant under the renormalization group flow in the particle-hole channels. Using empirical values for the spin-independent Fermi liquid parameters, we are able to compute the major spin-dependent ones by imposing the new constraints as well as the Pauli principle sum rules.Comment: 4 pages, 5 figures, in Proc. 11th International Conference on Recent Progress in Many-Body Theories, Manchester, UK, July 9-13, 200

Magnetic Properties of the low dimensional spin system (VO)2_2P2_2O7_{7}: ESR and susceptibility

Experimental results on magnetic resonance (ESR) and magnetic susceptibility are given for single crystalline (VO)$_2$P$_2$O$_{7}$. The crystal growth procedure is briefly discussed. The susceptibility is interpreted numerically using a model with alternating spin chains. We determine $J$=51 K and $\delta$=0.2. Furthermore we find a spin gap of $\approx 6$meV from our ESR measurements. Using elastic constants no indication of a phase transition forcing the dimerization is seen below 300 K.Comment: 7 pages, REVTEX, 7 figure

Influence of light nuclei on neutrino-driven supernova outflows

We study the composition of the outer layers of a protoneutron star and show that light nuclei are present in substantial amounts. The composition is dominated by nucleons, deuterons, tritons and alpha particles; 3He is present in smaller amounts. This composition can be studied in laboratory experiments with new neutron-rich radioactive beams that can reproduce similar densities and temperatures. After including the corresponding neutrino interactions, we demonstrate that light nuclei have a small impact on the average energy of the emitted electron neutrinos, but are significant for the average energy of antineutrinos. During the early post-explosion phase, the average energy of electron antineutrinos is slightly increased, while at later times during the protoneutron star cooling it is reduced by about 1 MeV. The consequences of these changes for nucleosynthesis in neutrino-driven supernova outflows are discussed

Comparing the cumulative pain patients experience waiting for knee arthroplasty to their postoperative pain

Introduction: Reduction of pain is a major goal of anesthesiologists treating patients undergoing knee arthroplasty. This has been achieved traditionally through the use of regional analgesia. Although these techniques decrease postoperative pain, they inherently do not affect the longstanding pain patients experience as they wait for surgery. Our objectives were to quantify: 1) the decrease in pain achieved by surgical joint replacement; and 2) the decrease in postoperative pain achievable through femoral nerve blocks versus opioids. From a systems-based perspective, we wanted to determine how much reduction in waiting time before surgery would be necessary to achieve an equal cumulative pain decrease (i.e, pain x duration of pain) as that afforded by regional techniques in the immediate postoperative period. Materials and methods: A systematic review using PubMed was performed to obtain: 1) articles reporting preoperative pain scores for patients awaiting joint arthroplasty; 2) articles with knee arthroplasty patients who received femoral nerve blocks; and 3) articles providing duration on joint arthroplasty waiting lists. Cumulative pain was assessed by the area under the response curve of pain scores vs. time, a methodology that is simple and valid. This was calculated by multiplying mean pain scores by the duration of pain. Results: The decrease in knee pain subsequent to arthroplasty (6.4/10 vs. 2.9/10) is similar to the decrease in pain afforded by femoral nerve blocks for knee arthroplasty (4.7/10 vs. 2.0/10). Waiting times in many countries exceed 3 months. A decrease in waiting time by about 2 days results in a decrease in the area under the curve of Conclusion: Reducing waiting time for knee arthroplasty decreases total pain experienced by patients and is one systems-based approach that anesthesiologists could take to relieve pain. Further studies are needed to evaluate how best to accomplish this goal