4,105 research outputs found
INTEGRAL observations of TeV plerions
Amongst the sources seen in very high gamma-rays several are associated with
Pulsar Wind Nebulae (``TeV plerions''). The study of hard X-ray/soft gamma-ray
emission is providing an important insight into the energetic particle
population present in these objects. The unpulsed emission from pulsar/pulsar
wind nebula systems in the energy range accessible to the INTEGRAL satellite is
mainly synchrotron emission from energetic and fast cooling electrons close to
their acceleration site. Our analyses of public INTEGRAL data of known TeV
plerions detected by ground based Cherenkov telescopes indicate a deeper link
between these TeV plerions and INTEGRAL detected pulsar wind nebulae. The newly
discovered TeV plerion in the northern wing of the Kookaburra region
(G313.3+0.6 powered by the middle aged PSR J1420-6048) is found to have a
previously unknown INTEGRAL counterpart which is besides the Vela pulsar the
only middle aged pulsar detected with INTEGRAL. We do not find an INTEGRAL
counterpart of the TeV plerion associated with the X-ray PWN ``Rabbit''
G313.3+0.1 which is possibly powered by a young pulsar.Comment: 4 pages, 6 figures, proceedings of conference "The Multi-Messenger
Approach to High-Energy Gamma-ray Sources" Barcelona/Spain (2006
Charge Symmetry Violation Effects in Pion Scattering off the Deuteron
We discuss the theoretical and experimental situations for charge symmetry
violation (CSV) effects in the elastic scattering of pi+ and pi- on deuterium
(D) and 3He/3H. Accurate comparison of data for both types of targets provides
evidence for the presence of CSV effects. While there are indications of a CSV
effect in deuterium, it is much more pronounced in the case of 3He/3H. We
provide a description of the CSV effect on the deuteron in terms of single- and
double- scattering amplitudes. The Delta-mass splitting is taken into account.
Theoretical predictions are compared with existing experimental data for pi-d
scattering; a future article will speak to the pi-three nucleon case.Comment: 16 pages of RevTeX, 7 postscript figure
Using self-definition to predict the influence of procedural justice on organizational, interpersonal, and job/task-oriented citizenship behaviors
An integrative self-definition model is proposed to improve our understanding of how procedural justice affects different outcome modalities in organizational behavior. Specifically, it is examined whether the strength of different levels of self-definition (collective, relational, and individual) each uniquely interact with procedural justice to predict organizational, interpersonal, and job/task-oriented citizenship behaviors, respectively. Results from experimental and (both single and multisource) field data consistently revealed stronger procedural justice effects (1) on organizational-oriented citizenship behavior among those who define themselves strongly in terms of organizational characteristics, (2) on interpersonal-oriented citizenship behavior among those who define themselves strongly in terms of their interpersonal relationships, and (3) on job/task-oriented citizenship behavior among those who define themselves weakly in terms of their distinctiveness or uniqueness. We discuss the relevance of these results with respect to how employees can be motivated most effectively in organizational settings
Lexicality and frequency in specific language impairment: accuracy and error data from two nonword repetition tests
Purpose: Deficits in phonological working memory and deficits in phonological processing have both been considered potential explanatory factors in Specific Language Impairment (SLI). Manipulations of the lexicality and phonotactic frequency of nonwords enable contrasting predictions to be derived from these hypotheses. Method: 18 typically developing (TD) children and 18 children with SLI completed an assessment battery that included tests of language ability, non-verbal intelligence, and two nonword repetition tests that varied in lexicality and frequency. Results: Repetition accuracy showed that children with SLI were unimpaired for short and simple high lexicality nonwords, whereas clear impairments were shown for all low lexicality nonwords. For low lexicality nonwords, greater repetition accuracy was seen for nonwords constructed from high over low frequency phoneme sequences. Children with SLI made the same proportion of errors that substituted a nonsense syllable for a lexical item as TD children, and this was stable across nonword length. Conclusions: The data show support for a phonological processing deficit in children with SLI, where long-term lexical and sub-lexical phonological knowledge mediate the interpretation of nonwords. However, the data also suggest that while phonological processing may provide a key explanation of SLI, a full account is likely to be multi-faceted
Tev Observations of the Variability and Spectrum of Markarian 421
Markarian 421 was the first extragalactic source to be detected with high
statistical certainty at TeV energies. The Whipple Observatory gamma-ray
telescope has been used to observe the Active Galactic Nucleus, Markarian 421
in 1996 and 1997. The rapid variability observed in TeV gamma rays in previous
years is confirmed. Doubling times as short as 15 minutes are reported with
flux levels reaching 15 photons per minute. The TeV energy spectrum is derived
using two independent methods. The implications for the intergalactic infra-red
medium of an observed unbroken power law spectrum up to energies of 5 TeV is
discussed.Comment: 4 pages, 4 figures, to appear in proceedings of 25 ICRC (Durban
TeV Observations of the Variability and Spectrum of Markarian 501
Markarian 501 is only the second extragalactic source to be detected with
high statistical certainty at TeV energies; it is similar in many ways to
Markarian 421. The Whipple Observatory gamma-ray telescope has been used to
observe the AGN Markarian 501 in 1996 and 1997, the years subsequent to its
initial detection. The apparent variability on the one-day time-scale observed
in TeV gamma rays in 1995 is confirmed and compared with the variability in
Markarian 421. Observations at X-ray and optical wavelengths from 1997 are also
presented.Comment: 4 pages, 2 figures, to appear in proceedings of 25th ICRC (Durban
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