On the Origin of the Early Solar System Radioactivities. Problems with the AGB and Massive Star Scenarios

Recent improvements in stellar models for intermediate-mass and massive stars are recalled, together with their expectations for the synthesis of radioactive nuclei of lifetime $\tau \lesssim 25$ Myr, in order to re-examine the origins of now extinct radioactivities, which were alive in the solar nebula. The Galactic inheritance broadly explains most of them, especially if $r$-process nuclei are produced by neutron star merging according to recent models. Instead, $^{26}$Al, $^{41}$Ca, $^{135}$Cs and possibly $^{60}$Fe require nucleosynthesis events close to the solar formation. We outline the persisting difficulties to account for these nuclei by Intermediate Mass Stars (2 $\lesssim$ M/M$_\odot \lesssim 7 - 8$). Models of their final stages now predict the ubiquitous formation of a $^{13}$C reservoir as a neutron capture source; hence, even in presence of $^{26}$Al production from Deep Mixing or Hot Bottom Burning, the ratio $^{26}$Al/$^{107}$Pd remains incompatible with measured data, with a large excess in $^{107}$Pd. This is shown for two recent approaches to Deep Mixing. Even a late contamination by a Massive Star meets problems. In fact, inhomogeneous addition of Supernova debris predicts non-measured excesses on stable isotopes. Revisions invoking specific low-mass supernovae and/or the sequential contamination of the pre-solar molecular cloud might be affected by similar problems, although our conclusions here are weakened by our schematic approach to the addition of SN ejecta. The limited parameter space remaining to be explored for solving this puzzle is discussed.Comment: Accepted for publication on Ap

Charge Fluctuations in the Edge States of N-S hybrid Nano-Structures

In this work we show how to calculate the equilibrium and non-equilibrium charge fluctuations in a gated normal mesoscopic conductor which is attached to one normal lead and one superconducting lead. We then consider an example where the structure is placed in a high magnetic field, such that the transport is dominated by edge states. We calculate the equilibrium and non-equilibrium charge fluctuations in the gate, for a single edge state, comparing our results to those for the same system, but with two normal leads. We then consider the specific example of a quantum point contact and calculate the charge fluctuations in the gate for more than one edge state.Comment: 4 pages with 1 figure. In published version the high magnetic field dynamics of the holes is treated incorrectly. An erratum is in preparatio

Effect of Level of Barley in Finishing Diets of Swine Performance and Carcass Characteristics

Barley continues to be a feed ingredient available to swine producers in South Dakota, that can be used as a substitute for corn. In experiments reported in the 1984 South Dakota Swine Day Proceedings we reported that pigs fed barley diets gained slower during the grower period (60 to 125 lbs) but not during the finisher period (125 to 220 lb). This experiment was designed to evaluate various levels of barley, 0 to 100% of the grain, in diets fed to pigs from an average of 80 to 220 lb market weight

Comparison of Required Energy Intake of Gilts and Sows to Obtain Recommended Gestation Gains

Three trials utilizing 104 crossbred sows and gilts were conducted to evaluate energy needs to provide_ predetermined gestation gains for gilts and sows. In trial l» gilts required similar energy levels (6918 kcal ME) to gain .9 lb/day as bred sows required (7008 kcal ME) to gain .5 lb/day during gestation. Open sows and gilts consumed much more energy but were unable to gain at the predetermined levels. In trial 2, 8 month old gilts required more energy than mature sows (5898 vs 5028 kcal ME) and 11 month old gilts consumed more than either other group to gain at an intermediate level. In trial 3, a daily difference in energy consumption of approximately 800 kcal of ME existed between gilts and sows fed to predetermined gestation gains. If the results of the last two trials are averaged, a difference in energy consumption of 840 kcal of ME/day is found between gilts fed to gain .9 lb/day and sows fed to gain .5 lb/day. This difference is approximately .6 lb of additional gestation feed needed per day for the bred gilt if gestation gain is used as a criteria of evaluation

Influence of Gestation Energy on Large White x Landrace Sow Productivity

Production remains extremely important in our swine industry today. In the past 5-10 years, there has been an increase in the usage of white breeds in swine herds. The white or mother breeds are noted for their increased productivity; however, a question has stirred as to the feeding regime of these productive females. This question is important as feed costs are the major portion of operating expenses for the hog producers. Little controlled research has been conducted in the United States to establish the caloric intake requirement of the white sows during gestation. The National Research Council (NRC, 1979) lists the energy requirement of the bred sow and gilt as 6.1 Meal of. digestible energy (DE) or 5.8 Meal of metabolizable energy (ME) daily. This recommendation is largely based on research with traditional 3-way crossbred sows. Great Britain swine researchers in the 1960\u27s and United States researchers Frobish and workers (1966) were the last to evaluate the effect of gestation energy on strictly white sows. To help answer the current concerns of white sow nutrition, this research project was designed to study the influence of gestation energy on Large White x Landrace sow productivity

Comparison of Sow and Gilt Performance as Affected by Gestation Energy Intake

Gestation energy needs of sows include maintenance as well as tissue growth associated with pregnancy and fetal development. Gilts have the additional demands of body tissue growth but less maintenance needs because of smaller body size. Differences in total daily energy needs between sows and gilts have not been resolved. Results of three trials conducted to compare energy needs for specific gestation gains for sows and gilts were reported last year (Swine 84-10). These results suggested the need for approximately 870 Kcal of additional metabolizable energy (ME) (.6 lb of feed) for gilts with the desired gains of .5 lb/day for sows and .9 lb/day for gilts. The trial reported herein was designed to evaluate comparative performance of sows and gilts fed a wide range of ME levels

Importance truncation for the in-medium similarity renormalization group

Ab initio nuclear many-body frameworks require extensive computational resources, especially when targeting heavier nuclei. Importance-truncation (IT) techniques allow to significantly reduce the dimensionality of the problem by neglecting unimportant contributions to the solution of the many-body problem. In this work, we apply IT methods to the nonperturbative in-medium similarity renormalization group (IMSRG) approach and investigate the induced errors for ground-state energies in different mass regimes based on different nuclear Hamiltonians. We study various importance measures, which define the IT selection, and identify two measures that perform best, resulting in only small errors to the full IMSRG(2) calculations even for sizable compression ratios. The neglected contributions are accounted for in a perturbative way and serve as an estimate of the IT-induced error. Overall we find that the IT-IMSRG(2) performs well across all systems considered, while the largest compression ratios for a given error can be achieved when using soft Hamiltonians and for large single-particle bases

In-medium similarity renormalization group with three-body operators

Over the last decade the in-medium similarity renormalization group (IMSRG) approach has proven to be one of the most powerful and versatile ab initio many-body methods for studying medium-mass nuclei. So far, the IMSRG was limited to the approximation in which only up to two-body operators are incorporated in the renormalization group flow, referred to as the IMSRG(2). In this work, we extend the IMSRG(2) approach to fully include three-body operators yielding the IMSRG(3) approximation. We use a perturbative scaling analysis to estimate the importance of individual terms in this approximation and introduce truncations that aim to approximate the IMSRG(3) at a lower computational cost. The IMSRG(3) is systematically benchmarked for different nuclear Hamiltonians for ${}^{4}\text{He}$ and ${}^{16}\text{O}$ in small model spaces. The IMSRG(3) systematically improves over the IMSRG(2) relative to exact results. Approximate IMSRG(3) truncations constructed based on computational cost are able to reproduce much of the systematic improvement offered by the full IMSRG(3). We also find that the approximate IMSRG(3) truncations behave consistently with expectations from our perturbative analysis, indicating that this strategy may also be used to systematically approximate the IMSRG(3).Comment: 22 pages, 10 figures, updated versio

Natural orbitals for many-body expansion methods

The nuclear many-body problem for medium-mass systems is commonly addressed using wave-function expansion methods that build upon a second-quantized representation of many-body operators with respect to a chosen computational basis. While various options for the computational basis are available, perturbatively constructed natural orbitals recently have been shown to lead to significant improvement in many-body applications yielding faster model-space convergence and lower sensitivity to basis set parameters in large-scale no-core shell model diagonalizations. This work provides a detailed comparison of single-particle basis sets and a systematic benchmark of natural orbitals in nonperturbative many-body calculations using the in-medium similarity renormalization group approach. As a key outcome we find that the construction of natural orbitals in a large single-particle basis enables for performing the many-body calculation in a reduced space of much lower dimension, thus offering significant computational savings in practice that help extend the reach of ab initio methods towards heavier masses and higher accuracy.Comment: 15 pages, 9 figures, published versio