105 research outputs found
Guam Initial Technical Assessment Report
Under an interagency agreement, funded by the Department of Interior's (DOI) Office of Insular Affairs (OIA), the National Renewable Energy Laboratory (NREL) was tasked to deliver technical assistance to the island of Guam by conducting an island initial technical assessment that would lay out energy consumption and production data and establish a baseline. This assessment will be used to conduct future analysis and studies by NREL that will estimate energy efficiency and renewable energy potential for the island of Guam
X-ray spectra from magnetar candidates. II Resonant cross sections for electron-photon scattering in the relativistic regime
Recent models of spectral formation in magnetars called renewed attention on
electron-photon scattering in the presence of ultra-strong magnetic fields.
Investigations presented so far mainly focussed on mildly relativistic
particles and magnetic scattering was treated in the non-relativistic (Thomson)
limit. This allows for consistent spectral calculations up to a few tens of
keVs, but becomes inadequate in modelling the hard tails (<200 keV) detected by
INTEGRAL from magnetar sources. In this paper, the second in a series devoted
to model the X-/soft gamma-ray persistent spectrum of magnetar candidates, we
present explicit, relatively simple expressions for the magnetic Compton
cross-section at resonance which account for Landau-Raman scattering up to the
second Landau level. No assumption is made on the magnetic field strength. We
find that sensible departures from the Thomson regime can bealready present at
B ~5E12 G. The form of the magnetic cross section we derived can be easily
implemented in Monte Carlo transfer codes and a direct application to magnetar
spectral calculations will be presented in a forthcoming study.Comment: 14 pages, 5 figures, accepted for publication in MNRA
Recommended from our members
Small Wind Turbine Testing and Applications Development
Small wind turbines offer a promising alternative for many remote electrical uses where there is a good wind resource. The National Wind Technology Center (NWTC) of the National Renewable Energy Laboratory helps further the role that small turbines can play in supplying remote power needs. The NWTC tests and develops new applications for small turbines. The NWTC also develops components used in conjunction with wind turbines for various applications. This paper describes wind energy research at the NWTC for applications including battery charging stations, water desalination/purification, and health clinics. Development of data acquisition systems and tests on small turbines are also described
Gamma-Ray Burst Energy Spectra: Theoretical Models, Old and New
The modelling of gamma-ray burst (GRB) spectra has considerable potential for
increasing the understanding of these enigmatic sources. A diversity of ideas
and analyses has been generated over the last two decades to explain line
features and continuum shapes, encompassing both older galactic neutron star
and ``new age'' cosmological source models. This paper reviews some of the
highlights of these studies, discussing the merits and limitations of various
ideas, and in particular their compatibility with the observational data. The
first focus will be on continuum models for GRBs, which include optically thin
synchrotron emission and resonant Compton upscattering near galactic neutron
stars, while the synchrotron and non-magnetic inverse Compton scattering
mechanisms are prominent in the less well-developed cosmological scenarios.
Line formation scenarios will then be discussed, in particular the scattering
model for producing cyclotron features, which remains the only viable
explanation for the Ginga observations of double lines. Absorption-like line
production in cosmological burst models is generally difficult, though
interesting notions such as femtolensing interference patterns have been
proffered.Comment: 8 pages with no figures, as a compressed, uuencoded, Postscript file.
Invited review, to appear in Astrophysics and Space Science as part of the
proceedings of the 29th ESLAB Symposium ``Towards the Source of Gamma-Ray
Bursts'' held in Noordwijk, 199
QCD Corrections to QED Vacuum Polarization
We compute QCD corrections to QED calculations for vacuum polarization in
background magnetic fields. Formally, the diagram for virtual loops
is identical to the one for virtual loops. However due to
confinement, or to the growth of as decreases, a direct
calculation of the diagram is not allowed. At large we consider the
virtual diagram, in the intermediate region we discuss the role of
the contribution of quark condensates \left and at the
low-energy limit we consider the , as well as charged pion
loops. Although these effects seem to be out of the measurement accuracy of
photon-photon laboratory experiments they may be relevant for -ray
burst propagation. In particular, for emissions from the center of the galaxy
(8.5 kpc), we show that the mixing between the neutral pseudo-scalar pion
and photons renders a deviation from the power-law spectrum in the
range. As for scalar quark condensates \left and
virtual loops are relevant only for very high radiation density
and very strong magnetic fields of order .Comment: 15 pages, 4 figures; Final versio
Wolves in the Wolds: Late Capitalism, the English Eerie, and the Wyrd Case of âOld Stinkerâ the Hull Werewolf
In this article, I depart from the earlier opinions of Emily Gerard, Sabine Baring-Gould, and others, who explained the disappearance of the werewolf in folklore as following the extinction of the wolf. I argue instead that British literature is distinctive in representing a history of werewolf sightings in places in Britain where there were once wolves. I draw on the idea of absence, manifestations of the English eerie, and the turbulence of England in the era of late capitalism to illuminate my analysis of the representation of contemporary werewolf sightingsPeer reviewe
A Calanais myth and an alignment of the east stone-row with both the rising of the Pleiades and crossovers of Venus at sunrise on the summer solstices
Acknowledgements My thanks to Stefan Sagrott of Historic Environment Scotland for his help in obtaining Patrick Ashmoreâs data and to David Forrest, School of Geographical and Earth Sciences, University of Glasgow, for providing a copy of David Taitâs map of Calanais.Peer reviewedPublisher PD
- âŠ