8,080 research outputs found
The Proper Motion of PSR J0205+6449 in 3C 58
We report on sensitive phase-referenced and gated 1.4-GHz VLBI radio
observations of the pulsar PSR J0205+6449 in the young pulsar-wind nebula 3C
58, made in 2007 and 2010. We employed a novel technique where the ~105-m Green
Bank telescope is used simultaneously to obtain single-dish data used to
determine the pulsar's period as well as to obtain the VLBI data, allowing the
VLBI correlation to be gated synchronously with the pulse to increase the
signal-to-noise. The high timing noise of this young pulsar precludes the
determination of the proper motion from the pulsar timing. We derive the
position of the pulsar accurate at the milliarcsecond level, which is
consistent with a re-determined position from the Chandra X-ray observations.
We reject the original tentative optical identification of the pulsar by
Shearer and Neustroev (2008), but rather identify a different optical
counterpart on their images, with R-band magnitude ~24. We also determine an
accurate proper motion for PSR J0205+6449 of (2.3 +- 0.3) mas/yr, corresponding
to a projected velocity of only (35 +- 6) km/s for a distance of 3.2 kpc, at
p.a. -38 deg. This projected velocity is quite low compared to the velocity
dispersion of known pulsars of ~200 km/s. Our measured proper motion does not
suggest any particular kinematic age for the pulsar.Comment: 10 pages, 7 figures; accepted for publication in MNRA
Measurement of the longitudinal and transverse cross-section in e^+e^- annihilation at sqrt(s)=35-44 GeV
An investigation of the polar angle distribution of charged hadrons is
presented using data taken by the JADE experiment at the PETRA e^+e^- collider
at centre-of-mass energies of 35 and 44 GeV. From fits to the polar angle
distribution the longitudinal, sigma_L, and transverse, sigma_T, cross-section
relative to the total hadronic are determined at an average energy scale of
36.6 GeV. The results are sigma_L/sigma_tot = 0.067 +/- 0.013,
sigma_T/sigma_tot = 0.933 -/+ 0.013 where total errors are given and the
results are exactly anti-correlated. Using the next-to-leading order QCD
prediction for the longitudinal cross-section, the value alpha_S(36.6 GeV) =
0.150 +/- 0.025 of the strong coupling constant is obtained in agreement with
the world average value of alpha_S evolved to an energy scale of 36.6 GeV.Comment: 12 pages, LaTeX2e, 5 .eps-files included, pennames.sty included,
submitted to Phys. Lett.
Opportunities for farming in alpine countries – pathways to truly grassland-based beef and milk production in Austria and Switzerland
Farming in the alpine countries of Austria and Switzerland fulfils important economic, socio-cultural and ecological functions for society. However, even though both Austria and Switzerland have increasingly focused their agricultural policy towards ecology, in both countries negative environmental impacts of agriculture still have to be reduced massively
Multi-excitonic complexes in single InGaN quantum dots
Cathodoluminescence spectra employing a shadow mask technique of InGaN layers
grown by metal organic chemical vapor deposition on Si(111) substrates are
reported. Sharp lines originating from InGaN quantum dots are observed.
Temperature dependent measurements reveal thermally induced carrier
redistribution between the quantum dots. Spectral diffusion is observed and was
used as a tool to correlate up to three lines that originate from the same
quantum dot. Variation of excitation density leads to identification of exciton
and biexciton. Binding and anti-binding complexes are discovered.Comment: 3 pages, 4 figure
Sustainability assessment of organic dairy farms in mountainous areas of Austria
Dairy farming plays a major role in mountainous regions of Austria, mostly due to high proportion of grasslands. In general, Austria’s dairy farming faces challenges regarding sustainability, e.g. environmental impacts, but specifically for alpine areas low productivity and dependency on direct payments are lowering sustainability. Organic farming is considered as a strategy to overcome these challenges.
Considering this general background, we analysed the sustainability performance and its main drivers of organic dairy farms in mountainous regions of Austria
miRGator v2.0 : an integrated system for functional investigation of microRNAs
miRGator is an integrated database of microRNA (miRNA)-associated gene expression, target prediction, disease association and genomic annotation, which aims to facilitate functional investigation of miRNAs. The recent version of miRGator v2.0 contains information about (i) human miRNA expression profiles under various experimental conditions, (ii) paired expression profiles of both mRNAs and miRNAs, (iii) gene expression profiles under miRNA-perturbation (e.g. miRNA knockout and overexpression), (iv) known/predicted miRNA targets and (v) miRNA-disease associations. In total, >8000 miRNA expression profiles, ∼300 miRNA-perturbed gene expression profiles and ∼2000 mRNA expression profiles are compiled with manually curated annotations on disease, tissue type and perturbation. By integrating these data sets, a series of novel associations (miRNA–miRNA, miRNA–disease and miRNA–target) is extracted via shared features. For example, differentially expressed genes (DEGs) after miRNA knockout were systematically compared against miRNA targets. Likewise, differentially expressed miRNAs (DEmiRs) were compared with disease-associated miRNAs. Additionally, miRNA expression and disease-phenotype profiles revealed miRNA pairs whose expression was regulated in parallel in various experimental and disease conditions. Complex associations are readily accessible using an interactive network visualization interface. The miRGator v2.0 serves as a reference database to investigate miRNA expression and function (http://miRGator.kobic.re.kr)
A light-front description of electromagnetic form factors for hadrons
A review of the hadron electromagnetic form factors obtained in a light-front
constituent quark model, based on the eigenfunctions of a mass operator, is
presented. The relevance of different components in the q-q interaction for the
description of hadron experimental form factors is analysed.Comment: 6 pages, Latex, 3 Postscript figures included. Proceedings of
"Nucleon 99", Frascati, June 1999. To appear in Nucl. Phys.
A low-cost vision based navigation system for small size unmanned aerial vehicle applications
Not availabl
On QCD analysis of stucture function in alternative approach
The alternative approach to QCD analysis of the photon structure function
is presented. It differs from the conventional one by the
presence of the terms which in conventional approach appear in higher orders.
We show that this difference concerns also the photonic parton distribution
functions. In the alternative approach, the complete LO analysis of
can be performed as all required quantities are known. At the
NLO, however, one of the coefficient function is so far not available and thus
only the photonic parton distribution function can be computed and compared to
those of standard approach. We discuss the numerical difference of these
approaches at the LO and the NLO approximation and show that in case of
this difference is non-negligible and may play an important role
in the analysis on photon data of the future experiments.Comment: 25 page
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