9,140 research outputs found
Everyone Makes Mistakes - Including Feynman
This talk is dedicated to Alberto Sirlin in celebration of his seventieth
birthday. I wish to convey my deep appreciation of his many important
contributions to particle physics over 40 years and look forward to many more
years of productive research.Comment: 16 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLN
Asymptotic flatness at null infinity in arbitrary dimensions
We define the asymptotic flatness and discuss asymptotic symmetry at null
infinity in arbitrary dimensions using the Bondi coordinates. To define the
asymptotic flatness, we solve the Einstein equations and look at the asymptotic
behavior of gravitational fields. Then we show the asymptotic symmetry and the
Bondi mass loss law with the well-defined definition.Comment: 12 pages, published version in PR
RAVEN: a GUI and an Artificial Intelligence Engine in a Dynamic PRA Framework
Increases in computational power and pressure for
more accurate simulations and estimations of accident scenario consequences are driving the need for Dynamic
Probabilistic Risk Assessment (PRA) [1] of very complex models. While more sophisticated algorithms and
computational power address the back end of this challenge, the front end is still handled by engineers that
need to extract meaningful information from the large amount of data and build these complex models.
Compounding this problem is the difficulty in knowledge transfer and retention, and the increasing speed of
software development. The above-described issues would have negatively
impacted deployment of the new high fidelity plant simulator RELAP-7 (Reactor Excursion and Leak
Analysis Program) at Idaho National Laboratory. Therefore, RAVEN that was initially focused to be the
plant controller for RELAP-7 will help mitigate future
RELAP-7 software engineering risks. In order to accomplish such a task Reactor Analysis
and V
Effects of applied pressure on hot-pressing of Beta-SiC
The effects of applied pressure on the densification during hot pressing of beta-SiC compacts were investigated. Beta-SiC powder is Starck made and has the average particle size of about 0.7 micrometer. Hot pressing experiments were carried out in graphite dies at temperatures of 1700 deg to 2300 deg C and at the pressures up to 1000 kg/sq cm. The compacts containing 1 weight percent B4C were examined. Sintered compacts were examined for microstructure and the Rockwell A-scale hardness was measured. The B4C addition was very effective to mitigate the hot pressing conditions. It is found that densification goes with the strengthening of the bonding and does not occur in particle deformation due to concentrated stress
On the Hadronic Contribution to Light-by-light Scattering in
We comment on the theoretical uncertainties involved in estimating the
hadronic effects on the light-by-light scattering contribution to the anomalous
magnetic moment of the muon, especially based on the analysis and results of T.
Kinoshita, B. Ni\v zi\'c, and Y. Okamoto, Phys.\ Rev.\ D31, 2108 (1985). From
the point of view of an effective field theory and chiral perturbation theory,
we suggest that the charged pion contribution may be better determined than has
been appreciated. However, the neutral pion contribution needs greater
theoretical insight before its magnitude can be reliably estimated.Comment: 9 pages, no figures, U. Michigan UM-TH-93-18. (Input phyzzm to
compile.) Revised version has minor changes in text. To be published in Phys.
Rev. D, Comments sectio
Proton Polarization Shifts in Electronic and Muonic Hydrogen
The contribution of virtual excitations to the energy levels of electronic
and muonic hydrogen is investigated combining a model-independent approach for
the main part with quark model predictions for the remaining corrections.
Precise values for the polarization shifts are obtained in the long-wavelength
dipole approximation by numerically integrating over measured total
photoabsorption cross sections. These unretarded results are considerably
reduced by including retardation effects in an approximate way since the
average momentum transfer (together with the mean excitation energy) turns out
to be larger than usually assumed. Transverse and seagull contributions are
estimated in a simple harmonic oscillator quark model and found to be
non-negligible. Possible uncertainties and improvements of the final results
are discussed.Comment: 8 pages, LATEX, no figures, discussion improved and references
updated, final version accepted for publication in Phys. Lett.
On recognizing Japanese katakana words: Explaining the reduced priming with hiragana and mixed-kana identity primes
The Japanese kana syllabary has 2 allographic forms, hiragana and katakana. As with other allographic variants like the uppercase and lowercase letters of the Roman alphabet, they show robust formindependent priming effects in the allograph match task (e.g., Kinoshita. Schubert. & Verdonschot, 2019). suggesting that they share abstract character-level representations. In direct contradiction, Perea. Nakayama, and Lupker (2017) argued that hiragana and katakana do not share character-level representations. based on their finding of reduced priming with identity prime containing a mix of hiragana and katakana (the mixed-kana prime) relative to the all-katakana identity prime in a lexical-decision task with loanword targets written in katakana. Here we sought to reconcile these seemingly contradictory claims, using mixed-kana. hiragana, and katakana primes in lexical decision. The mixed-kana prime and hiragana prime produced priming effects that are indistinguishable, and both were reduced in size relative to the priming effect produced by the katakana identity prime. Furthermore, this pattern was unchanged when the target was presented in hiragana. The findings are interpreted in terms of the assumption that the katakana format is specified in the orthographic representation of loanwords in Japanese readers. Implications of the account for the universality across writing systems is discussed
Mora or more? The phonological unit of Japanese word production in the Stroop color naming task
In English, Dutch, and other European languages, it is well established that the fundamental phonological unit in word production is the phoneme; in contrast, recent studies have shown that in Chinese it is the (atonal) syllable and in Japanese the mora. The present study investigated whether this cross-language variation in the size of the unit of word production is due to the type of script used in the language (i.e., alphabetic, morphosyllabic, or moraic). Capitalizing on the multiscriptal nature of Japanese, and using the Stroop color naming task, we show that the overlap in the initial mora between the color name and the written distractor facilitates color naming independent of script type. These results confirm the mora as the phonological unit of word production in Japanese, and establish the Stroop color naming task as a useful task for investigating the fundamental (or "proximate") phonological unit used in speech production
Phonological encoding is free from orthographic influence: evidence from a picture variant of the phonological Stroop task
The phonological Stroop task, in which the participant names the color of written distractors, is being used increasingly to study the phonological encoding process in speech production. A brief review of experimental paradigms used to study the phonological encoding process indicated that currently it is not known whether the onset overlap benefit (faster color naming when the distractor shares the onset segment with the color name) in a phonological Stroop task is due to phonology or orthography. The present paper investigated this question using a picture variant of the phonological Stroop task. Participants named a small set of line drawings of animals (e.g., camel) with a pseudoword distractor printed on it. Picture naming was facilitated when the distractor shared the onset segment with the picture name regardless of orthographic overlap (CUST–camel = KUST–camel < NUST–camel). We conclude that the picture variant of the phonological Stroop task is a useful tool to study the phonological encoding process, free of orthographic influence
Angular momentum at null infinity in higher dimensions
We define the angular momentum at null infinity in higher dimensions. The
asymptotic symmetry at null infinity becomes the Poincare group in higher
dimensions. This fact implies that the angular momentum can be defined without
any ambiguities such as supertranslation in four dimensions. Indeed we can show
that the angular momentum in our definition is transformed covariantly with
respect to the Poincare group.Comment: 13 page
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