Determination of fragmentation functions and their uncertainties from e+ + e- -> h + X data

Fragmentation functions are determined for pions, kaons, and nucleons by a global analysis of charged-hadron production data in electron-positron annihilation. The optimum functions are obtained in both leading order (LO) and next-to-leading order (NLO) of alpha_s. It is important that uncertainties of the fragmentation functions are estimated in this work by the Hessian method. We found that the uncertainties are large at small Q^2 and that they are generally reduced in the NLO in comparison with the LO ones. We supply a code for calculating the fragmentation functions and their uncertainties for the pions, kaons, and nucleons at given z and Q^2.Comment: 4 pages, LaTeX, 5 eps files, to be published in AIP proceedings of the 17th International Spin Physics Symposium (SPIN2006), Oct. 2-7, 2006, Kyoto, Japa

Effects of Galaxy Formation on Thermodynamics of the Intracluster Medium

We present detailed comparisons of the intracluster medium (ICM) in cosmological Eulerian cluster simulations with deep Chandra observations of nearby relaxed clusters. To assess the impact of galaxy formation, we compare two sets of simulations, one performed in the non-radiative regime and another with radiative cooling and several physical processes critical to various aspects of galaxy formation: star formation, metal enrichment and stellar feedback. We show that the observed ICM properties outside cluster cores are well-reproduced in the simulations that include cooling and star formation, while the non-radiative simulations predict an overall shape of the ICM profiles inconsistent with observations. In particular, we find that the ICM entropy in our runs with cooling is enhanced to the observed levels at radii as large as half of the virial radius. We also find that outside cluster cores entropy scaling with the mean ICM temperature in both simulations and Chandra observations is consistent with being self-similar within current error bars. We find that the pressure profiles of simulated clusters are also close to self-similar and exhibit little cluster-to-cluster scatter. The X-ray observable-total mass relations for our simulated sample agree with the Chandra measurements to \~10%-20% in normalization. We show that this systematic difference could be caused by the subsonic gas motions, unaccounted for in X-ray hydrostatic mass estimates. The much improved agreement of simulations and observations in the ICM profiles and scaling relations is encouraging and the existence of tight relations of X-ray observables, such as Yx, and total cluster mass and the simple redshift evolution of these relations hold promise for the use of clusters as cosmological probes.Comment: 14 pages, 6 figures. Matches version accepted to Ap

Non-resonant direct p- and d-wave neutron capture by 12C

Discrete gamma-rays from the neutron capture state of 13C to its low-lying bound states have been measured using pulsed neutrons at En = 550 keV. The partial capture cross sections have been determined to be 1.7+/-0.5, 24.2+/-1.0, 2.0+/-0.4 and 1.0+/-0.4 microb for the ground (1/2-), first (1/2+), second (3/2-) and third (5/2+) excited states, respectively. From a comparison with theoretical predictions based on the non-resonant direct radiative capture mechanism, we could determine the spectroscopic factor for the 1/2+ state to be 0.80 +/- 0.04, free from neutron-nucleus interaction ambiguities in the continuum. In addition we have detected the contribution of the non-resonant d-wave capture component in the partial cross sections for transitions leading to the 1/2- and 3/2- states. While the s-wave capture dominates at En < 100 keV, the d-wave component turns out to be very important at higher energies. From the present investigation the 12C(n,gamma)13C reaction rate is obtained for temperatures in the range 10E+7 - 10E+10 K.Comment: Accepted for publication in Phys. Rev. C. - 16 pages + 8 figure

Capturing characteristics of the conceptual ideation process of master crafts persons to inform design education: a comparative study of rural craft practitioners in Indonesia and in the UK

At the very early stage of idea generation, allegedly, a master craftsperson encounters cognitive dissonance to maintain beliefs/mindsets from various conceptual stimuli. We aim to capture the underlying form of cognition by examining the structure of thoughts collected from the subjective conceptualisation. A think-aloud protocol was employed to obtain verbalised thoughts of both Indonesian and UK master craftsmen. The keywords of verbalised thoughts were evaluated and extracted using a list of typical mindsets. The evaluated keywords were then analysed by means of a conceptual network to reproduce a model of the individual's mental state. This study discovered that Indonesian master craftsmen's conceptualisation is greatly influenced by the strong typical mindsets of object-attribute that emphasise rationale and mastery, which stimulates a pragmatic viewpoint. Furthermore, UK master craftsmen's conceptualisation greatly considers strong typical mindsets of object-attribute that emphasise wisdom and passionate, which indicates a rigorous mind. This paper reveals that both pragmatic and rigorous mindsets can create potential or barriers for creative cognitive resources

Limb-Brightened Jet of 3C 84 Revealed by the 43-GHz Very-Long-Baseline-Array Observation

We present a study of sub-pc scale radio structure of the radio galaxy 3C 84/NGC 1275 based on the Very Long Baseline Array (VLBA) data at 43 GHz. We discover a limb-brightening in the "restarted" jet associated with the 2005 radio outburst. In the 1990s, the jet structure was ridge-brightening rather than limb-brightening, despite the observations being done with similar angular resolution. This indicates that the transverse jet structure has changed recently. This change in the morphology shows an interesting agreement with the $\gamma$-ray flux increase, i.e., the $\gamma$-ray flux in 1990s was at least seven times lower than the current one. One plausible explanation for the limb-brightening is the velocity structure of the jet in the context of the stratified jet, which is a successful scenario to explain the $\gamma$-ray emission in some active galactic nuclei (AGNs). If this is the case, the change in apparent transverse structure might be caused by the change in the transverse velocity structure. We argue the possibility that the transition from ridge-brightening to limb-brightening is related to the $\gamma$-ray time variability on the timescale of decades. We also discuss the collimation profile of the jet.Comment: 22 pages, 4 figures, Accepted for Publication in Ap

Liveness-Driven Random Program Generation

Randomly generated programs are popular for testing compilers and program analysis tools, with hundreds of bugs in real-world C compilers found by random testing. However, existing random program generators may generate large amounts of dead code (computations whose result is never used). This leaves relatively little code to exercise a target compiler's more complex optimizations. To address this shortcoming, we introduce liveness-driven random program generation. In this approach the random program is constructed bottom-up, guided by a simultaneous structural data-flow analysis to ensure that the generator never generates dead code. The algorithm is implemented as a plugin for the Frama-C framework. We evaluate it in comparison to Csmith, the standard random C program generator. Our tool generates programs that compile to more machine code with a more complex instruction mix.Comment: Pre-proceedings paper presented at the 27th International Symposium on Logic-Based Program Synthesis and Transformation (LOPSTR 2017), Namur, Belgium, 10-12 October 2017 (arXiv:1708.07854

Modeling the iron oxides and oxyhydroxides for the prediction of environmentally sensitive phase transformations

Iron oxides and oxyhydroxides are challenging to model computationally as competing phases may differ in formation energies by only several kJ/mol, they undergo magnetization transitions with temperature, their structures may contain partially occupied sites or long-range ordering of vacancies, and some loose structures require proper description of weak interactions such as hydrogen bonding and dispersive forces. If structures and transformations are to be reliably predicted under different chemical conditions, each of these challenges must be overcome simultaneously, while preserving a high level of numerical accuracy and physical sophistication. Here we present comparative studies of structure, magnetization, and elasticity properties of iron oxides and oxyhydroxides using density functional theory calculations with plane-wave and locally-confined-atomic-orbital basis sets, which are implemented in VASP and SIESTA packages, respectively. We have selected hematite, maghemite, goethite, lepidocrocite, and magnetite as model systems from a total of 13 known iron oxides and oxyhydroxides; and use same convergence criteria and almost equivalent settings in order to make consistent comparisons. Our results show both basis sets can reproduce the energetic stability and magnetic ordering, and are in agreement with experimental observations. There are advantages to choosing one basis set over the other, depending on the intended focus. In our case, we find the method using PW basis set most appropriate, and combine our results to construct the first phase diagram of iron oxides and oxyhydroxides in the space of competing chemical potentials, generated entirely from first principlesComment: 46 pages - Accepted for publication in PRB (19 journal pages), January 201