Neuron splitting in compute-bound parallel network simulations enables runtime scaling with twice as many processors

Neuron tree topology equations can be split into two subtrees and solved on different processors with no change in accuracy, stability, or computational effort; communication costs involve only sending and receiving two double precision values by each subtree at each time step. Splitting cells is useful in attaining load balance in neural network simulations, especially when there is a wide range of cell sizes and the number of cells is about the same as the number of processors. For compute-bound simulations load balance results in almost ideal runtime scaling. Application of the cell splitting method to two published network models exhibits good runtime scaling on twice as many processors as could be effectively used with whole-cell balancing

Entanglement Sharing and Decoherence in the Spin-Bath

The monogamous nature of entanglement has been illustrated by the derivation of entanglement sharing inequalities - bounds on the amount of entanglement that can be shared amongst the various parts of a multipartite system. Motivated by recent studies of decoherence, we demonstrate an interesting manifestation of this phenomena that arises in system-environment models where there exists interactions between the modes or subsystems of the environment. We investigate this phenomena in the spin-bath environment, constructing an entanglement sharing inequality bounding the entanglement between a central spin and the environment in terms of the pairwise entanglement between individual bath spins. The relation of this result to decoherence will be illustrated using simplified system-bath models of decoherence.Comment: 5 pages, 1 figure v2: 6 pages 2 figures, additional example and reference

Unobscured Type 2 Active Galactic Nuclei

Type 2 active galactic nuclei (AGNs) with intrinsically weak broad emission lines (BELs) would be exceptions to the unified model. After examining a number of proposed candidates critically, we find that the sample is contaminated significantly by objects with BELs of strengths indicating that they actually contain intermediate-type AGNs, plus a few Compton-thick sources as revealed by extremely low ratios of X-ray to nuclear IR luminosities. We develop quantitative metrics that show two (NGC 3147 and NGC 4594) of the remaining candidates to have BELs 2-3 orders of magnitude weaker than those of typical type 1 AGNs. Several more galaxies remain as candidates to have anomalously weak BELs, but this status cannot be confirmed with the existing information. Although the parent sample is poorly defined, the two confirmed objects are well under 1% of its total number of members, showing that the absence of a BEL is possible, but very uncommon in AGN. We evaluate these two objects in detail using multi-wavelength measurements including new IR data obtained with Spitzer and ground-based optical spectropolarimeteric observations. They have little X-ray extinction with N_H < ~10^(21) cm^(–2). Their IR spectra show strong silicate emission (NGC 4594) or weak aromatic features on a generally power-law continuum with a suggestion of silicates in emission (NGC 3147). No polarized BEL is detected in NGC 3147. These results indicate that the two unobscured type 2 objects have circumnuclear tori that are approximately face-on. Combined with their X-ray and optical/UV properties, this behavior implies that we have an unobscured view of the nuclei and thus that they have intrinsically weak BELs. We compare their properties with those of the other less-extreme candidates. We then compare the distributions of bolometric luminosities and accretion rates of these objects with theoretical models that predict weak BELs

Dust in the wind: Crystalline silicates, corundum and periclase in PG 2112+059

We have determined the mineralogical composition of dust in the Broad Absorption Line (BAL) quasar PG 2112+059 using mid-infrared spectroscopy obtained with the Spitzer Space Telescope. From spectral fitting of the solid state features, we find evidence for Mg-rich amorphous silicates with olivine stoichiometry, as well as the first detection of corundum (Al_2O_3) and periclase (MgO) in quasars. This mixed composition provides the first direct evidence for a clumpy density structure of the grain forming region. The silicates in total encompass 56.5% of the identified dust mass, while corundum takes up 38 wt.%. Depending on the choice of continuum, a range of mass fractions is observed for periclase ranging from 2.7% in the most conservative case to 9% in a less constrained continuum. In addition, we identify a feature at 11.2 micron as the crystalline silicate forsterite, with only a minor contribution from polycyclic aromatic hydrocarbons. The 5% crystalline silicate fraction requires high temperatures such as those found in the immediate quasar environment in order to counteract rapid destruction from cosmic rays.Comment: 2 figure

Effects of alternative soy sources on growth performance in early-weaned pigs

A total of 144 pigs (initial body wt of 10.4 lb) was used in a 56-d growth assay to determine the effects of different soybean preparations on growth performance and cost of gain in nursery pigs. Experimental diets were fed in three phases from d 0 to 35 postweaning (Le., d 0 to 7, 7 to 21, and 21 to 35). Treatments were a soybean meal-based regimen; a dry-extruded whole soybeans (mill-run) regimen; and a specially processed soy products regimen (Le., soy isolate in Phase I, soy concentrate in Phase 11, and extruded soy flour in Phase Ill). All diets were formulated to 1. 55, 1. 25, and 1.15% lysine for Phases I, 11, and III, respectively. Fat additions to the soybean meal and specialty soy product treatments were 2, 2, and 3%, for Phases I, 11, and III, respectively. The diets with extruded soybeans had more total fat (2.5, 3.8, and 4.8% greater percentage ether extract in Phases I, 11, and III, respectively) than the soybean meal-based control. On d 35 postweaning, the pigs were switched to the same soybean meal-based grower diet (.9% lysine) for a period of 3 wk. During Phase I (d 0 to 7 postweaning), pigs fed soybean meal gained 25% less and were 22% less efficient than those fed extruded soybeans and the specially processed soy products. Average daily feed intake was not affected by dietary treatment; however, pigs fed the specially processed soy product had the greatest ADG of any treatment, and numerically, the best efficiencies of gain. No statistical differences were found for ADG, ADFI, or F/G among treatments from d 7 to 21, 21 to 35, or 35 to 56 of the experiment. Thus, overall (from d 0 to 56 postweaning), pigs fed the various soybean protein sources had similar growth performance. However, overall costs per pound of gain were $.33,$.34, and $.42 for pigs fed extruded soybeans, soybean meal, and the specialty soy products, respectively. In conclusion, although the specially processed soy products regimen (Le., soy isolate) supported the greatest growth performance immediately after weaning (d 0 to 7), the best cost of gain was achieved by feeding extruded soybeans. However, the additional fat provided by extruded soybeans did not influence pig performance in this experiment.; Swine Day, Manhattan, KS, November 17, 199