9,326 research outputs found
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
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
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
Diagnostics of stellar flares from X-ray observations: from the decay to the rise phase
The diagnostics of stellar flaring coronal loops have been so far largely
based on the analysis of the decay phase. We derive new diagnostics from the
analysis of the rise and peak phase of stellar flares. We release the
assumption of full equilibrium of the flaring loop at the flare peak, according
to the frequently observed delay between the temperature and the density
maximum. From scaling laws and hydrodynamic simulations we derive diagnostic
formulas as a function of observable quantities and times. We obtain a
diagnostic toolset related to the rise phase, including the loop length,
density and aspect ratio. We discuss the limitations of this approach and find
that the assumption of loop equilibrium in the analysis of the decay leads to a
moderate overestimate of the loop length. A few relevant applications to
previously analyzed stellar flares are shown. The analysis of the flare rise
and peak phase complements and completes the analysis of the decay phase.Comment: 10 pages, 7 figures, accepted on refereed journa
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