Isomeric Excitation Energy for ^{99}In^{m} from Mass Spectrometry Reveals Constant Trend Next to Doubly Magic ^{100}Sn

The excitation energy of the 1/2^{-} isomer in ^{99}In at N=50 is measured to be 671(37) keV and the mass uncertainty of the 9/2^{+} ground state is significantly reduced using the ISOLTRAP mass spectrometer at ISOLDE/CERN. The measurements exploit a major improvement in the resolution of the multireflection time-of-flight mass spectrometer. The results reveal an intriguing constancy of the 1/2^{-} isomer excitation energies in neutron-deficient indium that persists down to the N=50 shell closure, even when all neutrons are removed from the valence shell. This trend is used to test large-scale shell model, ab initio, and density functional theory calculations. The models have difficulties describing both the isomer excitation energies and ground-state electromagnetic moments along the indium chain.

Nuclear Equation of State for Arbitrary Proton Fraction and Temperature Based on Chiral Effective Field Theory and a Gaussian Process Emulator

We calculate the equation of state of asymmetric nuclear matter at finite temperature based on chiral effective field theory interactions to next-to-next-to-next-to-leading order. Our results assess the theoretical uncertainties from the many-body calculation and the chiral expansion. Using a Gaussian process emulator for the free energy, we derive the thermodynamic properties of matter through consistent derivatives and use the Gaussian process to access arbitrary proton fraction and temperature. This enables a first nonparametric calculation of the equation of state in beta equilibrium, and of the speed of sound and the symmetry energy at finite temperature. Moreover, our results show that the thermal part of the pressure decreases with increasing densities.

Nuclear Charge Radii of the Nickel Isotopes ^{58-68,70}Ni

Collinear laser spectroscopy is performed on the nickel isotopes ^{58-68,70}Ni, using a time-resolved photon counting system. From the measured isotope shifts, nuclear charge radii R_{c} are extracted and compared to theoretical results. Three ab initio approaches all employ, among others, the chiral interaction NNLO_{sat}, which allows an assessment of their accuracy. We find agreement with experiment in differential radii δ⟨r_{c}^{2}⟩ for all employed ab initio methods and interactions, while the absolute radii are consistent with data only for NNLO_{sat}. Within nuclear density functional theory, the Skyrme functional SV-min matches experiment more closely than the Fayans functional Fy(Δr,HFB).

Role of Chiral Two-Body Currents in ^{6}Li Magnetic Properties in Light of a New Precision Measurement with the Relative Self-Absorption Technique

A direct measurement of the decay width of the excited 0_{1}^{+} state of ^{6}Li using the relative self-absorption technique is reported. Our value of Γ_{γ,0_{1}^{+}→1_{1}^{+}}=8.17(14)_{stat.}(11)_{syst.}  eV provides sufficiently low experimental uncertainties to test modern theories of nuclear forces. The corresponding transition rate is compared to the results of ab initio calculations based on chiral effective field theory that take into account contributions to the magnetic dipole operator beyond leading order. This enables a precision test of the impact of two-body currents that enter at next-to-leading order.

Ab Initio Limits of Atomic Nuclei

We predict the limits of existence of atomic nuclei, the proton and neutron drip lines, from the light through medium-mass regions. Starting from a chiral two- and three-nucleon interaction with good saturation properties, we use the valence-space in-medium similarity renormalization group to calculate ground-state and separation energies from helium to iron, nearly 700 isotopes in total. We use the available experimental data to quantify the theoretical uncertainties for our ab initio calculations towards the drip lines. Where the drip lines are known experimentally, our predictions are consistent within the estimated uncertainty. For the neutron-rich sodium to chromium isotopes, we provide predictions to be tested at rare-isotope beam facilities.

Symmetric Nuclear Matter from the Strong Interaction

We study the equation of state of symmetric nuclear matter at zero temperature over a wide range of densities using two complementary theoretical approaches. At low densities, up to twice nuclear saturation density, we compute the energy per particle based on modern nucleon-nucleon and three-nucleon interactions derived within chiral effective field theory. For higher densities, we derive for the first time constraints in a Fierz-complete setting directly based on quantum chromodynamics using functional renormalization group techniques. We find remarkable consistency of the results obtained from both approaches as they come together in density and the natural emergence of a maximum in the speed of sound c_{S} at supranuclear densities. The presence of this maximum appears tightly connected to the formation of a diquark gap. Notably, this maximum is observed to exceed the asymptotic value c_{S}^{2}=1/3 while its exact position in terms of the density cannot yet be determined conclusively.

Polypharmacy and potential drug-drug interactions for people with HIV in the UK from the Climate-HIV database

Objectives

People with HIV (PWHIV) are likely to need therapies for comorbidities as they age. We assessed risk of drug–drug interactions (DDIs) in PWHIV.

Methods

The Climate‐HIV electronic recording system was used to cross‐sectionally analyse records from PWHIV aged ≥ 18 years attending four UK HIV units with a current antiretroviral (ARV) prescription in February 2018. Antiretroviral and non‐ARV medications were categorized by clinical significance of DDIs (University of Liverpool DDI tool). Potential DDIs were predicted using treatment guidelines for commonly recorded comorbidities.

Results

Among 4630 PWHIV (44% female), 41% were ≥ 50 years old. The average number of non‐ARV comedications increased from < 1 for patients aged ≤ 24 years to > 5 for patients aged ≥ 75 years; 65% were taking one or more non‐ARV comedications. The median (interquartile range) number of non‐ARVs was 1 (0–2) and 2 (1–5) for those aged < 50 and ≥ 50 years, respectively. Common comorbidities/concurrent health conditions occurred more frequently in patients aged ≥ 50 years vs. < 50 (53% vs. 34%). Boosted protease inhibitors were associated with the highest proportion of contraindicated comedications; dolutegravir and raltegravir had the fewest. For non‐ARVs, sildenafil and quetiapine were most likely to result in DDIs. Guideline‐recommended treatments for hepatitis C, hepatitis B, and tuberculosis had the highest proportions of contraindications when combined with ARV regimens, while treatments for hepatitis C, malignancy, and mental health conditions had the highest proportion of combinations potentially causing DDIs requiring dose monitoring or adjustment.

Conclusions

Non‐ARV use by PWHIV is high and increases with age. Treatment decisions for ageing PWHIV should consider guideline recommendations for comorbidities.

Charge Radius of the Short-Lived ^{68}Ni and Correlation with the Dipole Polarizability

We present the first laser spectroscopic measurement of the neutron-rich nucleus ^{68}Ni at the N=40 subshell closure and extract its nuclear charge radius. Since this is the only short-lived isotope for which the dipole polarizability α_{D} has been measured, the combination of these observables provides a benchmark for nuclear structure theory. We compare them to novel coupled-cluster calculations based on different chiral two- and three-nucleon interactions, for which a strong correlation between the charge radius and dipole polarizability is observed, similar to the stable nucleus ^{48}Ca. Three-particle-three-hole correlations in coupled-cluster theory substantially improve the description of the experimental data, which allows to constrain the neutron radius and neutron skin of ^{68}Ni.

First Glimpse of the N=82 Shell Closure below Z=50 from Masses of Neutron-Rich Cadmium Isotopes and Isomers

We probe the N=82 nuclear shell closure by mass measurements of neutron-rich cadmium isotopes with the ISOLTRAP spectrometer at ISOLDE-CERN. The new mass of ^{132}Cd offers the first value of the N=82, two-neutron shell gap below Z=50 and confirms the phenomenon of mutually enhanced magicity at ^{132}Sn. Using the recently implemented phase-imaging ion-cyclotron-resonance method, the ordering of the low-lying isomers in ^{129}Cd and their energies are determined. The new experimental findings are used to test large-scale shell-model, mean-field, and beyond-mean-field calculations, as well as the ab initio valence-space in-medium similarity renormalization group.

Equation of State Effects in Core-Collapse Supernovae

We investigate the impact of different properties of the nuclear equation of state in core-collapse supernovae, with a focus on the proto-neutron-star contraction and its impact on the shock evolution. To this end, we introduce a range of equations of state that vary the nucleon effective mass, incompressibility, symmetry energy, and nuclear saturation point. This allows us to point to the different effects in changing these properties from the Lattimer and Swesty to the Shen et al. equations of state, the two most commonly used equations of state in simulations. In particular, we trace the contraction behavior to the effective mass, which determines the thermal nucleonic contributions to the equation of state. Larger effective masses lead to lower pressures at nuclear densities and a lower thermal index. This results in a more rapid contraction of the proto-neutron star and consequently higher neutrino energies, which aids the shock evolution to a faster explosion.

First Results on the Scalar WIMP-Pion Coupling, Using the XENON1T Experiment

We present first results on the scalar coupling of weakly interacting massive particles (WIMPs) to pions from 1  t yr of exposure with the XENON1T experiment. This interaction is generated when the WIMP couples to a virtual pion exchanged between the nucleons in a nucleus. In contrast to most nonrelativistic operators, these pion-exchange currents can be coherently enhanced by the total number of nucleons and therefore may dominate in scenarios where spin-independent WIMP-nucleon interactions are suppressed. Moreover, for natural values of the couplings, they dominate over the spin-dependent channel due to their coherence in the nucleus. Using the signal model of this new WIMP-pion channel, no significant excess is found, leading to an upper limit cross section of 6.4×10^{-46}  cm^{2} (90% confidence level) at 30  GeV/c^{2} WIMP mass.

How Robust is the N=34 Subshell Closure? First Spectroscopy of ^{52}Ar

The first γ-ray spectroscopy of ^{52}Ar, with the neutron number N=34, was measured using the ^{53}K(p,2p) one-proton removal reaction at ∼210  MeV/u at the RIBF facility. The 2_{1}^{+} excitation energy is found at 1656(18) keV, the highest among the Ar isotopes with N>20. This result is the first experimental signature of the persistence of the N=34 subshell closure beyond ^{54}Ca, i.e., below the magic proton number Z=20. Shell-model calculations with phenomenological and chiral-effective-field-theory interactions both reproduce the measured 2_{1}^{+} systematics of neutron-rich Ar isotopes, and support a N=34 subshell closure in ^{52}Ar.

Chiral Interactions up to Next-to-Next-to-Next-to-Leading Order and Nuclear Saturation

We present an efficient Monte Carlo framework for perturbative calculations of infinite nuclear matter based on chiral two-, three-, and four-nucleon interactions. The method enables the incorporation of all many-body contributions in a straightforward and transparent way, and makes it possible to extract systematic uncertainty estimates by performing order-by-order calculations in the chiral expansion as well as the many-body expansion. The versatility of this new framework is demonstrated by applying it to chiral low-momentum interactions, exhibiting a very good many-body convergence up to fourth order. Following these benchmarks, we explore new chiral interactions up to next-to-next-to-next-to-leading order (N^{3}LO). Remarkably, simultaneous fits to the triton and to saturation properties can be achieved, while all three-nucleon low-energy couplings remain natural. The theoretical uncertainties of nuclear matter are significantly reduced when going from next-to-next-to-leading order to N^{3}LO.

Precision Mass Measurements of ^{58-63}Cr: Nuclear Collectivity Towards the N=40 Island of Inversion

The neutron-rich isotopes ^{58-63}Cr were produced for the first time at the ISOLDE facility and their masses were measured with the ISOLTRAP spectrometer. The new values are up to 300 times more precise than those in the literature and indicate significantly different nuclear structure from the new mass-surface trend. A gradual onset of deformation is found in this proton and neutron midshell region, which is a gateway to the second island of inversion around N=40. In addition to comparisons with density-functional theory and large-scale shell-model calculations, we present predictions from the valence-space formulation of the ab initio in-medium similarity renormalization group, the first such results for open-shell chromium isotopes.

Structure of the Lightest Tin Isotopes

We link the structure of nuclei around ^{100}Sn, the heaviest doubly magic nucleus with equal neutron and proton numbers (N=Z=50), to nucleon-nucleon (NN) and three-nucleon (NNN) forces constrained by data of few-nucleon systems. Our results indicate that ^{100}Sn is doubly magic, and we predict its quadrupole collectivity. We present precise computations of ^{101}Sn based on three-particle-two-hole excitations of ^{100}Sn, and we find that one interaction accurately reproduces the small splitting between the lowest J^{π}=7/2^{+} and 5/2^{+} states.

Properties of Nuclei up to A=16 using Local Chiral Interactions

We report accurate quantum Monte Carlo calculations of nuclei up to A=16 based on local chiral two- and three-nucleon interactions up to next-to-next-to-leading order. We examine the theoretical uncertainties associated with the chiral expansion and the cutoff in the theory, as well as the associated operator choices in the three-nucleon interactions. While in light nuclei the cutoff variation and systematic uncertainties are rather small, in ^{16}O these can be significant for large coordinate-space cutoffs. Overall, we show that chiral interactions constructed to reproduce properties of very light systems and nucleon-nucleon scattering give an excellent description of binding energies, charge radii, and form factors for all these nuclei, including open-shell systems in A=6 and 12.

Dawning of the N=32 Shell Closure Seen through Precision Mass Measurements of Neutron-Rich Titanium Isotopes

A precision mass investigation of the neutron-rich titanium isotopes ^{51-55}Ti was performed at TRIUMF's Ion Trap for Atomic and Nuclear science (TITAN). The range of the measurements covers the N=32 shell closure, and the overall uncertainties of the ^{52-55}Ti mass values were significantly reduced. Our results conclusively establish the existence of the weak shell effect at N=32, narrowing down the abrupt onset of this shell closure. Our data were compared with state-of-the-art ab initio shell model calculations which, despite very successfully describing where the N=32 shell gap is strong, overpredict its strength and extent in titanium and heavier isotones. These measurements also represent the first scientific results of TITAN using the newly commissioned multiple-reflection time-of-flight mass spectrometer, substantiated by independent measurements from TITAN's Penning trap mass spectrometer.

Electric Dipole Polarizability of ^{48}Ca and Implications for the Neutron Skin

The electric dipole strength distribution in ^{48}Ca between 5 and 25 MeV has been determined at RCNP, Osaka from proton inelastic scattering experiments at forward angles. Combined with photoabsorption data at higher excitation energy, this enables the first extraction of the electric dipole polarizability α_{D}(^{48}Ca)=2.07(22)  fm^{3}. Remarkably, the dipole response of ^{48}Ca is found to be very similar to that of ^{40}Ca, consistent with a small neutron skin in ^{48}Ca. The experimental results are in good agreement with ab initio calculations based on chiral effective field theory interactions and with state-of-the-art density-functional calculations, implying a neutron skin in ^{48}Ca of 0.14-0.20 fm.

Nucleus-Dependent Valence-Space Approach to Nuclear Structure

We present a nucleus-dependent valence-space approach for calculating ground and excited states of nuclei, which generalizes the shell-model in-medium similarity renormalization group to an ensemble reference with fractionally filled orbitals. Because the ensemble is used only as a reference, and not to represent physical states, no symmetry restoration is required. This allows us to capture three-nucleon (3N) forces among valence nucleons with a valence-space Hamiltonian specifically targeted to each nucleus of interest. Predicted ground-state energies from carbon through nickel agree with results of other large-space ab initio methods, generally to the 1% level. In addition, we show that this new approach is required in order to obtain convergence for nuclei in the upper p and sd shells. Finally, we address the 1^{+}/3^{+} inversion problem in ^{22}Na and ^{46}V. This approach extends the reach of ab initio nuclear structure calculations to essentially all light- and medium-mass nuclei.

Chiral Three-Nucleon Interactions in Light Nuclei, Neutron-α Scattering, and Neutron Matter

We present quantum Monte Carlo calculations of light nuclei, neutron-α scattering, and neutron matter using local two- and three-nucleon (3N) interactions derived from chiral effective field theory up to next-to-next-to-leading order (N(2)LO). The two undetermined 3N low-energy couplings are fit to the (4)He binding energy and, for the first time, to the spin-orbit splitting in the neutron-α P-wave phase shifts. Furthermore, we investigate different choices of local 3N-operator structures and find that chiral interactions at N(2)LO are able to simultaneously reproduce the properties of A=3,4,5 systems and of neutron matter, in contrast to commonly used phenomenological 3N interactions.

Quantum Monte Carlo calculations of light nuclei using chiral potentials

We present the first Green's function Monte Carlo calculations of light nuclei with nuclear interactions derived from chiral effective field theory up to next-to-next-to-leading order. Up to this order, the interactions can be constructed in a local form and are therefore amenable to quantum Monte Carlo calculations. We demonstrate a systematic improvement with each order for the binding energies of A=3 and A=4 systems. We also carry out the first few-body tests to study perturbative expansions of chiral potentials at different orders, finding that higher-order corrections are more perturbative for softer interactions. Our results confirm the necessity of a three-body force for correct reproduction of experimental binding energies and radii, and pave the way for studying few- and many-nucleon systems using quantum Monte Carlo methods with chiral interactions.

Nonperturbative shell-model interactions from the in-medium similarity renormalization group

We present the first ab initio construction of valence-space Hamiltonians for medium-mass nuclei based on chiral two- and three-nucleon interactions using the in-medium similarity renormalization group. When applied to the oxygen isotopes, we find experimental ground-state energies are well reproduced, including the flat trend beyond the drip line at (24)O. Similarly, natural-parity spectra in (21,22,23,24)O are in agreement with experiment, and we present predictions for excited states in (25,26)O. The results exhibit a weak dependence on the harmonic-oscillator basis parameter and reproduce spectroscopy within the standard sd valence space.

Breakdown of the isobaric multiplet mass equation for the A = 20 and 21 multiplets

Using the Penning trap mass spectrometer TITAN, we performed the first direct mass measurements of (20,21)Mg, isotopes that are the most proton-rich members of the A = 20 and A = 21 isospin multiplets. These measurements were possible through the use of a unique ion-guide laser ion source, a development that suppressed isobaric contamination by 6 orders of magnitude. Compared to the latest atomic mass evaluation, we find that the mass of (21)Mg is in good agreement but that the mass of (20)Mg deviates by 3 σ. These measurements reduce the uncertainties in the masses of (20,21)Mg by 15 and 22 times, respectively, resulting in a significant departure from the expected behavior of the isobaric multiplet mass equation in both the A = 20 and A = 21 multiplets. This presents a challenge to shell model calculations using either the isospin nonconserving universal sd USDA and USDB Hamiltonians or isospin nonconserving interactions based on chiral two- and three-nucleon forces.

Supernova matter at subnuclear densities as a resonant Fermi gas: enhancement of neutrino rates

At low energies nucleon-nucleon interactions are resonant and therefore supernova matter at subnuclear densities has many similarities to atomic gases with interactions dominated by a Feshbach resonance. We calculate the rates of neutrino processes involving nucleon-nucleon collisions and show that these are enhanced in mixtures of neutrons and protons at subnuclear densities due to the large scattering lengths. As a result, the rate for neutrino pair bremsstrahlung and absorption is significantly larger below 10(13) g cm(-3) compared to rates used in supernova simulations.

Precision Measurements of Magnetic Moments of Nuclei with weak NMR Signals

Two NMR spectrometers were combined and a special probe assembly was constructed in order to enable a simultaneous measurement of the signals of 2H and any nucleus, the gyromagnetic ratio of which is <1.4·107T-1sec-1. The Larmor frequencies of 39K, 73Ge, and 109Ag in well defined samples were referred very accurately to the resonance of 2H in D2O. It was possible now, to refer the Lamor frequencies of the nuclei 41K, 57Fe, 87Sr, 107Ag, 183W, 187Os, which were previously referred to the resonance of one of the nuclei mentioned above, to the Larmor frequencies of the deuteron and the proton in D2O or H2O.

The magnetic moments of all these nuclei are given.

109Ag Nuclear Magnetic Resonance Studies of Organic and Inorganic Silver Complexes

The NMR lines of 109Ag have been investigated in solutions of several silver salts in acetonitrile, propionitrile, pyridine, and ethylenediamine, and also in aqueous solutions of Na2S2O3 and ethyl-amine. In these solvents the Ag+ -ions form one or several complexes. In any case a single NMR line was to be detected, i. e. a rapid chemical exchange between different complexes in a sample may be assumed. The concentration dependence of the chemical shifts was determined with high accuracy for these solutions. From these results the chemical shift data of some defined complexes were derived. The chemical shifts of mixtures of AgCl and AgBr and also of AgCl and Agl dissolved in 70% aqueous solution of ethylamine are linear functions of the anions mole fraction. In two samples of AgNO3 dissolved in organic solvents, the ratio υ(109Ag)/υ(107Ag) = 1.149 640 (1) was measured in good agreement with the value from silver salts in aqueous solutions; i. e. no primary isotopic effect was to be detected within these limits of error (0.9 ppm).

Fourier-Kernresonanzuntersuchungen an 10 B und 11 B in wäßriger Lösung / Fourier Transform NMR Studies of 10 B and 11 B in Aqueous Solutions

The ratios of the Larmor frequencies of 10 B and 2 H and of 11 B and 10 B have been measured with the NMR method and a magnetic moment has been calculated for 10 B in the B (OH)4 - -ion. For this, an investigation of the dependence of the NMR signals of 10 B and 2 H on the concentration of some boron salts in solutions of H2O and D2O was necessary. Using hyperfine interaction constants from literature, the hyperfine structure anomaly 10 ∆ 11 of boron in the 2 P1/2 atomic ground state has been calculated. A difference in the magnetic shielding between the isotopes 10 B and 11 B in different compounds could not be detected.

39K, 40K and 41K Nuclear Magnetic Resonance Studies

The NMR lines of 39K and 41K have been investigated in solutions of many potassium salts in H2O, D2O, methanol and ethylenediamine and also in solid potassium halides. The NMR signal of the rare isotope 40K was detected for the first time. The ratio of the Larmor frequencies of 39K and 41K has been measured in various samples: υ(30K)/υ(41K) =1.821873 1 (9). No primary isotopic effect was to be detected within these limits of error (0.5 ppm). The concentration dependence of the chemical shift of the 39K resonance frequencies was determined. Using this dependence, the ratios of the Larmor frequencies of the nuclei 39K, 40K, and 41K for infinite dilution relative to the resonance frequency of 2H in D2O are given. The magnetic moments of the 39K+, 40K+, and 41K+ ions purely surrounded by water molecules are μ(39K+) =0.390 952 9 (24)μN, μ(40K+) = -1.296 262(9)μN , μ(41K+) =0.214 588 4 (13) μN without diamagnetic corrections. Comparison of these values with the results of atomic beam magnetic resonance experiments yields the hyperfine structure anomalies of all pairs of potassium isotopes and also the shielding of potassium nuclei by water molecules around the ions; the shielding constant is σ* (K+ in H2O vs. K atom) = - 0.000 105 2(8). For the liquid samples the relaxation times T2 and for the solid ones the relaxation times T2 and the line widths are given.

109Ag NMR-Studies of the Selective Solvation of the Ag+ -Ion in Water-Ethylamine-Mixtures and of the Coordination of Halide-Anions to the Silver-Ethylamine Solvate Complexes

109Ag chemical shift measurements of 0.02 up to 3 molar solutions of AgNO3, AgCl, and AgBr in solvent mixtures of H2O (W) and ethylamine (ea) were performed. The extremely long relaxation times T1 and T2 were determined with new techniques.

The Ag+ -ion in solvent mixtures of W and ea shows a strongly selective solvation by ea. The 109Ag chemical shift of the solvate complex [Ag ea2]+ surrounded solely by W is δ2 = (335 ± 2) ppm (referred to the Ag+-ion in W). A further solvation in addition to the inner solvation sphere was determined; this solvation is not or only weakly selective. There is a rapid chemical exchange; the lifetime of the inner solvation sphere is long compared with the Larmor period, whereas the solvation outside this sphere is changed in times shorter than the Larmor period.

In contrast to the NO3- -anion, the halide anions Cl- and Br- are partly coordinated to the [Ag ea2]+ complex. The equilibrium constants for this coordination were determined as well as the chemical shifts of the [Ag ea2 · Cl] and the [Ag ea2 · Br] complexes. The bromine ion is coordinated for shorter times than the Larmor period, whereas the time of the coordination of the chlorine ion may be comparable to the Larmor period or shorter.

Fourier Transform Nuclear Magnetic Resonance Studies of 25Mg and 43Ca

The ratios of the Larmor frequencies of 25Mg and 37Cl and of 43Ca and 37Cl have been measured in aqueous solutions and nuclear magnetic moments are given for these nuclei in the hydrated ions.

25Mg and 43Ca chemical shifts have been investigated at natural abundance of these isotopes in solutions of the chlorides, bromides, nitrates, Perchlorates in H2O and D2O. The signal intensities are large enough to study within reasonable time these nuclei at natural abundance down to low concentrated solutions, e.g. 8 millimolal for 25Mg. For 25Mg very small chemical shifts have been observed whereas for 43Ca remarkable shifts to higher frequencies are found for halide solutions and to lower frequencies for the oxyanion solutions. Linewidths of only some Hz have been observed for both isotopes

Search for a Primary Isotopic Effect on the Magnetic Shielding of the Rubidium and Cadmium Isotopes

The ratios of the gI-factors of 85Rb and 87Rb and of 111Cd and 113Cd have been measured in aqueous solutions of salts by the NMR method with high accuracy. A comparison with the same ratios measured by optical pumping techniques in free atoms shows agreement within the limits of error of 2.3 · 10-6 in the case of rubidium and of 3 · 10-7 in the case of cadmium: No difference in the magnetic shielding between the isotopes is observable.

Nuclear Magnetic Resonance Studies of 43Ca

The ratio of the Larmor frequencies of 43Ca and 37Cl has been measured and a magnetic moment for 43Ca of μ(43Ca2+ in D2O) = -1.315645 (7) μN; has been calculated. 43Ca chemical shifts have been determined in aqueous calcium salt solutions with 43Ca in natural abundance, also at low concentrations. The latter result is interesting for 43Ca studies in biological systems.

Notizen: 67Zn NMR Anomalous Solvent Isotope Effect in Aqueous Solutions

For 67Zn NMR lines of solutions of ZnCl2, ZnBr2, and ZnI2 in H2O and D2O an anomalous solvent isotope effect is reported. In D2O solutions the lines are shifted to higher frequencies. The difference between the shieldings in H2O and D2O is e.g. σ(H2O) - σ(D2O) = (13.1 ±0.7) ppm for a concentration of 0.02 moles zinc bromide per mole solvent.

Fourier Transform Nuclear Magnetic Resonance Studies of 67Zn

67Zn nuclear magnetic resonance studies of various solutions of diverse zinc salts in H2O and D2O are reported. In the solutions of ZnI2, ZnBr2 and ZnCl2 a remarkable chemical shift to higher frequency is observable, whilst for Zn(ClO4)2, Zn(NO3)2 and ZnSO4 no shift is detectable. The 67Zn shifts in zinc halide solutions depend on the isotopic composition of the solvent. The substitution of hydrogen by deuterium in the solvent yields for the 67Zn line an anomalous solvent isotope effect to higher frequency. Moreover for increasing temperature a linear increase of the shift and a nonlinear decrease of the linewidth for the zinc halide solutions were observed.

The ratio of the Larmor frequencies of 67Zn and 37Cl has been measured in an aqueous zinc perchlorate solution, and a magnetic moment has been calculated for 67Zn. The shielding constant for the hydrated zinc ion has been evaluated:

σ*(hydrated 67Zn++ versus 67Zn atom) = − (6.9 ± 0.1) · 10−4.

Starting treatment according to guidelines evaluation: a multicentre audit of HIV patients in the UK

The aim of this audit was to assess whether HIV patients are being started on antiretroviral therapy (ART) according to British and European guidelines. Data were collected from the Survey of Prevalent HIV Infections Diagnosed (SOPHID) return for 2010 at five major HIV management centres in the UK. Data from this 3873 patient cohort revealed 52 patients who should have been receiving ART according to the guidelines but were not. Of these, 23 patients elected not to start ART despite clinical advice to the contrary. Information required to assist in the decision for earlier ART initiation (CD4 count 350–500 cells/mL) was missing for some patients. Clinicians must pay attention to the regular assessment of patients with a CD4 count of 351–500 cells/mL so that all those who may benefit from earlier treatment are identified. Future research should investigate patient barriers to initiating therapy following recommendation by a clinician.

Quantum Monte Carlo calculations with chiral effective field theory interactions

We present the first quantum Monte Carlo (QMC) calculations with chiral effective field theory (EFT) interactions. To achieve this, we remove all sources of nonlocality, which hamper the inclusion in QMC calculations, in nuclear forces to next-to-next-to-leading order. We perform auxiliary-field diffusion Monte Carlo (AFDMC) calculations for the neutron matter energy up to saturation density based on local leading-order, next-to-leading order, and next-to-next-to-leading order nucleon-nucleon interactions. Our results exhibit a systematic order-by-order convergence in chiral EFT and provide nonperturbative benchmarks with theoretical uncertainties. For the softer interactions, perturbative calculations are in excellent agreement with the AFDMC results. This work paves the way for QMC calculations with systematic chiral EFT interactions for nuclei and nuclear matter, for testing the perturbativeness of different orders, and allows for matching to lattice QCD results by varying the pion mass.

Neutron matter at next-to-next-to-next-to-leading order in chiral effective field theory

Neutron matter presents a unique system for chiral effective field theory because all many-body forces among neutrons are predicted to next-to-next-to-next-to-leading order (N(3)LO). We present the first complete N(3)LO calculation of the neutron matter energy. This includes the subleading three-nucleon forces for the first time and all leading four-nucleon forces. We find relatively large contributions from N(3)LO three-nucleon forces. Our results provide constraints for neutron-rich matter in astrophysics with controlled theoretical uncertainties.

Three-body forces and proton-rich nuclei

We present the first study of three-nucleon (3N) forces for proton-rich nuclei along the N=8 and N=20 isotones. Our results for the ground-state energies and proton separation energies are in very good agreement with experiment where available, and with the empirical isobaric multiplet mass equation. We predict the spectra for all N=8 and N=20 isotones to the proton dripline, which agree well with experiment for 18Ne, 19Na, 20Mg and 42Ti. In all other cases, we provide first predictions based on nuclear forces. Our results are also very promising for studying isospin symmetry breaking in medium-mass nuclei based on chiral effective field theory.

Evaluation of nutritional counselling in HIV-associated malnutrition

In HIV-infected patients, the outcome of counselling as the first step of a nutritional intervention programme was evaluated, in order to identify clinical and nutritional predictors for its efficacy. 75 HIV-infected patients were investigated, most with advanced disease. Nutritional status was determined by body weight, bioelectrical impedance and 7-day food intake record. Prior mean weight loss was 10% (range = +4% to -31%). Counselling facilitated weight gain in 40 75 patients (1-4 months later, overall mean difference +1.4 +/- 6.2%) and in 14 34 patients (8-11 months later, overall mean difference -1.4 +/- 9.0%). Weight changes correlated with changes in body cell mass (r(2) = .69, p < .001) and in body fat (r(2) = .29, p < 0.05), but not extracellular mass. Underlying conditions such as AIDS definition, fever, and diarrhoea correlated to prior weight loss (p < .001) but not to the outcome of counselling. Low energy intake (before counselling, < 31.5 kcal/kg) did not correlate to prior weight loss but it predicted further weight loss (p < 0.05 towards normal intake). High energy intake (> 38.5 kcal/kg) correlated (p < 0.05) with more prior weight loss but not with further weight changes. Nutritional counselling may be an effective first-line intervention for malnourished HIV infected patients. More than half of patients gain weight without other nutritional treatment. Whereas the severity of malnutrition is influenced by the underlying disease, fever, and diarrhoea, the course of weight change after nutritional intervention is not. Counselling may reduce the nutritional impact of these risk factors. In patients with low spontaneous intake, efficacy of counselling alone is limited, but it may help to identify those who require more invasive nutritional treatment.

New precision mass measurements of neutron-rich calcium and potassium isotopes and three-nucleon forces

We present precision Penning trap mass measurements of neutron-rich calcium and potassium isotopes in the vicinity of neutron number N=32. Using the TITAN system, the mass of 51K was measured for the first time, and the precision of the (51,52)Ca mass values were improved significantly. The new mass values show a dramatic increase of the binding energy compared to those reported in the atomic mass evaluation. In particular, 52Ca is more bound by 1.74 MeV, and the behavior with neutron number deviates substantially from the tabulated values. An increased binding was predicted recently based on calculations that include three-nucleon (3N) forces. We present a comparison to improved calculations, which agree remarkably with the evolution of masses with neutron number, making neutron-rich calcium isotopes an exciting region to probe 3N forces.

First direct mass measurement of the two-neutron halo nucleus 6He and improved mass for the four-neutron halo 8He

The first direct mass measurement of {6}He has been performed with the TITAN Penning trap mass spectrometer at the ISAC facility. In addition, the mass of {8}He was determined with improved precision over our previous measurement. The obtained masses are m({6}He)=6.018 885 883(57)  u and m({8}He)=8.033 934 44(11)  u. The {6}He value shows a deviation from the literature of 4σ. With these new mass values and the previously measured atomic isotope shifts we obtain charge radii of 2.060(8) and 1.959(16) fm for {6}He and {8}He, respectively. We present a detailed comparison to nuclear theory for {6}He, including new hyperspherical harmonics results. A correlation plot of the point-proton radius with the two-neutron separation energy demonstrates clearly the importance of three-nucleon forces.

Chiral two-body currents in nuclei: Gamow-Teller transitions and neutrinoless double-beta decay

We show that chiral effective field theory (EFT) two-body currents provide important contributions to the quenching of low-momentum-transfer Gamow-Teller transitions, and use chiral EFT to predict the momentum-transfer dependence that is probed in neutrinoless double-beta (0νββ) decay. We then calculate for the first time the 0νββ decay operator based on chiral EFT currents and study the nuclear matrix elements at successive orders. The contributions from chiral two-body currents are significant and should be included in all calculations.

In-medium similarity renormalization group for nuclei

We present a new ab initio method that uses similarity renormalization group (SRG) techniques to continuously diagonalize nuclear many-body Hamiltonians. In contrast with applications of the SRG to two- and three-nucleon interactions in free space, we perform the SRG evolution "in medium" directly in the A-body system of interest. The in-medium approach has the advantage that one can approximately evolve 3,…,A-body operators using only two-body machinery based on normal-ordering techniques. The method is nonperturbative and can be tailored to problems ranging from the diagonalization of closed-shell nuclei to the construction of effective valence-shell Hamiltonians and operators. We present first results for the energies of 4He, 16O, and 40Ca, which have accuracies comparable to coupled-cluster calculations.

Constraints on neutron star radii based on chiral effective field theory interactions

We show that microscopic calculations based on chiral effective field theory interactions constrain the properties of neutron-rich matter below nuclear densities to a much higher degree than is reflected in commonly used equations of state. Combined with observed neutron star masses, our results lead to a radius R=9.7-13.9  km for a 1.4M⊙ star, where the theoretical range is due, in about equal amounts, to uncertainties in many-body forces and to the extrapolation to high densities.

The prevalence of hepatitis C virus (HCV) infection in HIV-positive individuals in the UK - trends in HCV testing and the impact of HCV on HIV treatment outcomes

We examined the prevalence of hepatitis C virus (HCV) infection among HIV-positive individuals in the UK, trends in HCV testing and the impact of HCV on HIV treatment outcomes. Trends over time in HCV prevalence were calculated using each patient's most recent HCV status at the end of each calendar year. Logistic regression was used to identify factors associated with having a HCV antibody test, and Cox regression was used to determine whether HCV status was associated with the time to experiencing an immunological response to highly active antiretroviral treatment (HAART), time to virological response and viral rebound. Of the 31,765 HIV-positive individuals seen for care between January 1996 and September 2007, 20,365 (64.1%) individuals were tested for HCV, and 1807 (8.9%) had detectable HCV antibody. The proportion of patients in follow-up ever tested for HCV increased over time, from 782/8505 (9.2%) in 1996 to 14,280/17,872 (79.9%) in 2007. Nine thousand six hundred and sixty-nine individuals started HAART for the first time in or after January 2000, of whom, 396 (4.1%) were HCV positive. Presence of HCV infection did not affect initial virological response, virological rebound or immunological response. The cumulative prevalence of HCV in the UK CHIC Study is 8.9%. Despite UK guidelines, over 20% of HIV-positive individuals have not had their HCV status determined by 2007. HCV infection had no impact on HIV virological outcomes or immunological response to HIV treatment. The long-term impact on morbidity and mortality remain to be determined.

Discordant responses on starting highly active antiretroviral therapy: suboptimal CD4 increases despite early viral suppression in the UK Collaborative HIV Cohort (UK CHIC) Study

OBJECTIVES

Patients starting highly active antiretroviral therapy (HAART) may have a suboptimal CD4 increase despite rapid virological suppression. The frequency and the significance for patient care of this discordant response are uncertain. This study was designed to determine the incidence of a discordant response at two time-points, soon after 6 months and at 12 months, and to determine the relationship with clinical outcomes.

METHODS

Data obtained in the UK Collaborative HIV Cohort Study were analysed. A total of 2584 treatment-naïve patients starting HAART with HIV viral load (VL) > 1000 HIV-1 RNA copies/mL at baseline and < 50 copies/mL within 6 months were included in the analysis. Patients were classified at either 6-10 (midpoint 8) months or 10-14 (midpoint 12) months as having a discordant (CD4 count increase < 100 cells/microL from baseline) or concordant response (CD4 count increase >or= 100 cells/microL).

RESULTS

Discordant responses occurred in 32.1% of patients at 8 months and in 24.2% at 12 months; 35% of those discordant at 8 months were concordant at 12 months. A discordant response was associated with older age, lower baseline VL, and (at 12 months) higher baseline CD4 cell count. In a multivariate analysis it was associated with an increased risk of death, more strongly at 12 months [incidence rate ratio (IRR) 3.35, 95% confidence interval (CI) 1.73-6.47, P < 0.001] than at 8 months (IRR 2.08, 95% CI 1.19-3.64, P = 0.010), but not with new AIDS events.

CONCLUSIONS

Discordant responders have a worse outcome, but assessment at 12 months may be preferred, given the number of 'slow' responders. Management strategies to improve outcomes for discordant responders need to be investigated.

The associations between age and the development of laboratory abnormalities and treatment discontinuation for reasons other than virological failure in the first year of highly active antiretroviral therapy

OBJECTIVE

The aim of this study was to describe the relationship between age and the time to treatment discontinuation in the absence of virological failure as well as the development of specific laboratory abnormalities, in patients starting highly active antiretroviral therapy (HAART) for the first time.

METHODS

Analyses included 8708 antiretroviral-naïve patients from the UK Collaborative HIV Cohort (CHIC) study who started HAART from 1998 onwards. We considered time to the first discontinuation of any drug in the initial HAART regimen for reasons other than virological failure; the association between this and age at the start of HAART was determined using proportional hazards regression after adjustment for potential confounders. The incidence of specific laboratory abnormalities in the first year after starting HAART was compared in those of different ages using multiple logistic regression.

RESULTS

A total of 2650 patients discontinued at least one drug in their HAART regimen in the first year for reasons other than virological failure; after controlling for confounders, those aged < 30 years at the time of starting HAART were more likely to discontinue than those aged 30-39 years [relative hazard (RH) 1.12; 95% confidence interval (CI) 1.01, 1.24] as were those aged > or = 50 years (RH 1.14; 95% CI 1.00, 1.31). There were strong associations between greater age and raised total cholesterol, decreased haemoglobin and raised triglycerides over the first year, although the latter disappeared after adjustment for pre-HAART levels, suggesting that this finding reflected higher pre-HAART triglyceride levels in older individuals.

CONCLUSIONS

Continued attempts to improve the tolerability of HAART regimens may help to sustain the good outcomes in all age groups over the longer term.