Symplectic Map Tracking for the LHC

Tracking simulation is the essential tool to evaluate how multipolar imperfections of the magnets limit the regime of stable particle motion in phase space. In the LHC, for instance, particles have to remain at injection energy, where the multipolar errors are at their maximum, for more than 10 million turns. Systematic tracking studies have to be limited to a small fraction of this total time even on modern computer systems. A considerable speed-up is expected when a symplectified one-turn map can be used instead of the element-by-element tracking. In this report we have applied this method for various map orders to the realistic case of the LHC lattice version 6 with special emphasis on precision and gain in speed

Fast symplectic map tracking for the CERN Large Hadron Collider

Tracking simulations remain the essential tool for evaluating how multipolar imperfections in ring magnets restrict the domain of stable phase-space motion. In the Large Hadron Collider (LHC) at CERN, particles circulate at the injection energy, when multipole errors are most significant, for more than 10^{7} turns, but systematic tracking studies are limited to a small fraction of this total time—even on modern computers. A considerable speedup is expected by replacing element-by-element tracking with the use of a symplectified one-turn map. We have applied this method to the realistic LHC lattice, version 6, and report here our results for various map orders, with special emphasis on precision and speed

The AMIGA sample of isolated galaxies. V. Quantification of the isolation

The AMIGA project aims to build a well defined and statistically significant reference sample of isolated galaxies in order to estimate the environmental effects on the formation and evolution of galaxies. The goal of this paper is to provide a measure of the environment of the isolated galaxies in the AMIGA sample, quantifying the influence of the candidate neighbours identified in our previous work and their potential effects on the evolution of the primary galaxies. Here we provide a quantification of the isolation degree of the galaxies in this sample. Our starting sample is the Catalogue of Isolated Galaxies (CIG). We used two parameters to estimate the influence exerted by the neighbour galaxies on the CIG galaxy: the local number density of neighbour galaxies and the tidal strength affecting the CIG galaxy. We show that both parameters together provide a comprehensive picture of the environment. For comparison, those parameters have also been derived for galaxies in denser environments such as triplets, groups and clusters. The CIG galaxies show a continuous spectrum of isolation, as quantified by the two parameters, from very isolated to interacting. The fraction of CIG galaxies whose properties are expected to be influenced by the environment is however low (159 out of 950 galaxies). The isolated parameters derived for the comparsion samples gave higher values than for the CIG and we found clear differences for the average values of the 4 samples considered, proving the sensitivity of these parameters. The environment of the galaxies in the CIG has been characterised, using two complementary parameters quantifying the isolation degree, the local number density of the neighbour galaxies and the tidal forces affecting the isolated galaxies. (Abridged)Comment: 10 pages, 12 figures, proposed for acceptance A&

Evaluation of mechanical and thermal nociception as objective tools to measure painful and nonpainful lameness phases in multiparous sows

The objective of this study was to quantify pain sensitivity differences using mechanical nociception threshold (MNT) and thermal nociception threshold (TNT) tests when sows were in painful and nonpainful transient lameness phases. A total of 24 mixed parity crossbred sows (220.15 ± 21.23 kg) were utilized for the MNT test, and a total of 12 sows (211.41 ± 20.21 kg) were utilized for the TNT test. On induction day (D0), all sows were anesthetized and injected with Amphotericin B (10mg/mL) in the distal interphalangeal joint space in both claws of one randomly selected hind limb to induce transient lameness. Three days were compared: (1) D-1 (sound phase, defined as 1 d before induction), (2) D+1 (most lame phase, defined as 1 d after induction), and (3) D+6 (resolution phase, defined as 6 d after induction). After completion of the first round, sows were given a 7-d rest period and then the procedures were repeated with lameness induced in the contralateral hind limb. During the MNT test, pressure was applied perpendicularly to 3 landmarks in a randomized sequence for each sow: 1) middle of cannon on the hind limb (cannon), 2) 1 cm above the coronary band on the medial hind claw (medial claw), and 3) 1 cm above the coronary band on the lateral hind claw (lateral claw). During the TNT test, a radiant heat stimulus was directed 1 cm above the coronary band. The data were analyzed using the MIXED procedure in SAS with sow as the experimental unit. Differences were analyzed between sound and lame limbs on each day. For the MNT test, pressure tolerated by the lame limb decreased for every landmark (P \u3c 0.05) when comparing D-1 and D+1. The sound limb tolerated more pressure on D+1 and D+6 than on baseline D-1 (P \u3c 0.05). Thermal stimulation tolerated by the sound limb did not change over the 3 d (P \u3e 0.05). However, the sows tolerated less heat stimulation on their lame limb on D+1 compared to D-1 levels (P \u3c 0.05). Both MNT and TNT tests indicated greater pain sensitivity thresholds when sows were acutely lame

Radio galaxies and magnetic fields in A514

A514 contains six extended and polarized radio sources located at various projected distances from the cluster center. Here we present a detailed study of these six radio sources in total intensity and polarization using the Very Large Array at 3.6 and 6 cm. Since the radio sources sample different lines of sight across the cluster, an analysis of the Faraday Rotation Measures (RMs) provides information on the strength and the structure of the cluster magnetic field. These sources show a decreasing Faraday Rotation Measure with increasing distance from the cluster center. We estimate the strength of the magnetic field to be ~3-7 uG in the cluster center. From the RM structure across the stronger and more extended sources we estimate the coherence length of the magnetic field to be about 9 kpc at the cluster center.Comment: 16 pages, 18 ps figures accepted by A&

Development of an Objective Feet and Leg Conformation Evaluation Method Using Digital Imagery in Swine

Background:The objectives of this study were to create an objective measurement method of joint angles for knee, hock, front and rear pasterns and a rear stance position in swine using digital imaging technology and to assess the repeatability of the objective measurement process. Methods and Findings: Forty-five multiparous sows (average parity 6.7 ± 2.5; parity range 5 to 14) from two commercial farms (n=21 farm 1 and n=24 farm 2) were used. Sows were moved to a pen where digital images of the profile and rear stance were captured. On average, 5.2 (± 2.6) profile and 2.6 (± 1.0) rear stance high quality images were used per sow. A joint angle measuring system was devised to collect angle measurements on the four feet and leg joints previously mentioned and the rear stance. Joint measurements were analyzed using repeated measure mixed model methods, including farm and parity (as 5, 6, and 7+) as fixed effects. Intraclass correlation coefficients were calculated to evaluate process repeatability. Joint angle measurement repeatability ranged from 0.63 to 0.82. Lowest and highest repeatabilities were observed for the front pastern and hock angle measurements, respectively. No significant farm or parity differences were observed for joint angles measured except for the knee angle between farms (P\u3c0.05) and the hock angle between sows’ parities 5 and 6 and parity 7+ (P\u3c0.05). Conclusions: Feet and leg conformation evaluation using digital images could be successfully used as an objective tool to aide in selection of replacement gilts. This could have a beneficial impact on sow longevity and farm productivity and profitability

Structural characterization of InAlAsSb/InGaAs/InP heterostructures for solar cells

In this work, we have characterized by transmission electron microscopy techniques the structural properties of InAlAsSb/InGaAs/InP heterostructures, with target applications in high efficiency solar cells. Previous photoluminescence (PL)1 analysis suggested the existence of compositional fluctuations in the active layer of these heterostructures. 220 bright field (BF)2 diffraction contrast micrographs have revealed strong strain contrast in the InGaAs buffer layer, related to the existence of these compositional fluctuations. The effect of a decomposed buffer on the growth of the InAlAsSb layer has been analyzed through the simulation of the strain fields in the heterostructure using the finite elements method (FEM).3 These simulations have shown that the strain in the buffer layer due to the compositional fluctuations only affects the first few nm of the InAlAsSb layer. The analysis by aberration corrected high angle annular dark field scanning transmission electron microscopy (HAADF-STEM)4and electron energy loss spectroscopy (EELS)5of the composition of the InAlAsSb layer reveals that any compositional fluctuation is only observed as an average effect, rather than in the form of clustering or atomically sharp transitions. The limitations of these techniques for the detection of small 3D compositional fluctuations are discussed

Modeling of Covalent Bonding in Solids by Inversion of Cohesive Energy Curves

We provide a systematic test of empirical theories of covalent bonding in solids using an exact procedure to invert ab initio cohesive energy curves. By considering multiple structures of the same material, it is possible for the first time to test competing angular functions, expose inconsistencies in the basic assumption of a cluster expansion, and extract general features of covalent bonding. We test our methods on silicon, and provide the direct evidence that the Tersoff-type bond order formalism correctly describes coordination dependence. For bond-bending forces, we obtain skewed angular functions that favor small angles, unlike existing models. As a proof-of-principle demonstration, we derive a Si interatomic potential which exhibits comparable accuracy to existing models.Comment: 4 pages revtex (twocolumn, psfig), 3 figures. Title and some wording (but no content) changed since original submission on 24 April 199