28,484 research outputs found
Exploring the potential X-ray counterpart of the puzzling TeV gamma-ray source HESS J1507-622 with new Suzaku observations
The unidentified VHE (E>100 GeV) gamma-ray source HESS J1507-622 seems to not
fit into standard models for sources related to young supernova remnants,
pulsar wind nebulae, or young stellar populations in general. This is due to
its intrinsically extended, but yet compact morphology, coupled with a relative
large offset (~3.5 deg) from the Galactic plane. Therefore, it has been
suggested that this object may be the first representative of a new distinct
class of extended off-plane gamma-ray sources. The distance to HESS J1507-622
is the key parameter to constrain the source's most important properties, such
as age and energetics of the relativistic particle population.
In this article we report on results of follow-up observations of the
potential X-ray counterpart with Suzaku. We present detailed measurements of
its spectral parameters and find a high absorbing hydrogen column density,
compatible with the total amount of Galactic gas in this direction. In
comparisons to measurements and models of the Galactic three-dimensional gas
distribution we show that the potential X-ray counterpart of HESS J1507-622 may
be located at the far end of the Galaxy. If the gamma-ray source is indeed
physically connected to this extended X-ray source, this in turn would place
the object outside of the usual distribution of Galactic VHE gamma-ray
emitters.Comment: 12 pages, 7 figures, accepted for publication by MNRA
Design, development and delivery of one /1/ breadboard and three /3/ production units of a 75 VA integrated static inverter Monthly progress report no. 11, Mar. 1966
Breadboard model development of integrated static inverte
Design, development and delivery of one /1/ breadboard and three /3/ production units of a 75 VA integrated static inverter Monthly report no. 15
Flip-flop arrays, power transistors, epitaxial stress, and other technological developments in integrated static inverter progra
Electrodynamics of a Magnet Moving through a Conducting Pipe
The popular demonstration involving a permanent magnet falling through a
conducting pipe is treated as an axially symmetric boundary value problem.
Specifically, Maxwell's equations are solved for an axially symmetric magnet
moving coaxially inside an infinitely long, conducting cylindrical shell of
arbitrary thickness at nonrelativistic speeds. Analytic solutions for the
fields are developed and used to derive the resulting drag force acting on the
magnet in integral form. This treatment represents a significant improvement
over existing models which idealize the problem as a point dipole moving slowly
inside a pipe of negligible thickness. It also provides a rigorous study of
eddy currents under a broad range of conditions, and can be used for precision
magnetic braking applications. The case of a uniformly magnetized cylindrical
magnet is considered in detail, and a comprehensive analytical and numerical
study of the properties of the drag force is presented for this geometry.
Various limiting cases of interest involving the shape and speed of the magnet
and the full range of conductivity and magnetic behavior of the pipe material
are investigated and corresponding asymptotic formulas are developed.Comment: 20 pages, 3 figures; computer program posted to
http://www.csus.edu/indiv/p/partovimh/magpipedrag.nb Submitted to the
Canadian Journal of Physic
StemNet: An Evolving Service for Knowledge Networking in the Life Sciences
Up until now, crucial life science information resources, whether bibliographic or factual databases, are isolated from each other. Moreover, semantic metadata intended to structure their contents is supplied in a manual form only. In the StemNet project we aim at developing a framework for semantic interoperability for these resources. This will facilitate the extraction of relevant information from textual sources and the generation of semantic metadata in a fully automatic manner. In this way, (from a computational perspective) unstructured life science documents are linked to structured biological fact databases, in particular to the identifiers of genes, proteins, etc. Thus, life scientists will be able to seamlessly access information from a homogeneous platform, despite the fact that the original information was unlinked and scattered over the whole variety of heterogeneous life science information resources and, therefore, almost inaccessible for integrated systematic search by academic, clinical, or industrial users
Extending Hybrid CSP with Probability and Stochasticity
Probabilistic and stochastic behavior are omnipresent in computer controlled
systems, in particular, so-called safety-critical hybrid systems, because of
fundamental properties of nature, uncertain environments, or simplifications to
overcome complexity. Tightly intertwining discrete, continuous and stochastic
dynamics complicates modelling, analysis and verification of stochastic hybrid
systems (SHSs). In the literature, this issue has been extensively
investigated, but unfortunately it still remains challenging as no promising
general solutions are available yet. In this paper, we give our effort by
proposing a general compositional approach for modelling and verification of
SHSs. First, we extend Hybrid CSP (HCSP), a very expressive and process
algebra-like formal modeling language for hybrid systems, by introducing
probability and stochasticity to model SHSs, which is called stochastic HCSP
(SHCSP). To this end, ordinary differential equations (ODEs) are generalized by
stochastic differential equations (SDEs) and non-deterministic choice is
replaced by probabilistic choice. Then, we extend Hybrid Hoare Logic (HHL) to
specify and reason about SHCSP processes. We demonstrate our approach by an
example from real-world.Comment: The conference version of this paper is accepted by SETTA 201
Determination of Strong-Interaction Widths and Shifts of Pionic X-Rays with a Crystal Spectrometer
Pionic 3d-2p atomic transitions in F, Na, and Mg have been studied using a bent crystal spectrometer. The pionic atoms were formed in the production target placed in the external proton beam of the Space Radiation Effects Laboratory synchrocyclotron. The observed energies and widths of the transitions are E=41679(3) eV and Γ=21(8) eV, E=62434(18) eV and Γ=22(80) eV, E=74389(9) eV and Γ=67(35) eV, in F, Na, and Mg, respectively. The results are compared with calculations based on a pion-nucleus optical potential
Vancomycin therapeutic drug monitoring and population pharmacokinetic models in special patient subpopulations
Vancomycin is a fundamental antibiotic in the management of severe Gram-positive infections. Inappropriate vancomycin dosing is associated with therapeutic failure, bacterial resistance and toxicity. Therapeutic drug monitoring (TDM) is acknowledged as an important part of the vancomycin therapy management, at least in specific patient subpopulations, but implementation in clinical practice has been difficult because there are no consensus and agglutinator documents. The aims of the present work are to present an overview of the current knowledge on vancomycin TDM and population pharmacokinetic (PPK) models relevant to specific patient subpopulations. Based on three published international guidelines (American, Japanese and Chinese) on vancomycin TDM and a bibliographic review on available PPK models for vancomycin in distinct subpopulations, an analysis of evidence was carried out and the current knowledge on this topic was summarized. The results of this work can be useful to redirect research efforts to address the detected knowledge gaps. Currently, TDM of vancomycin presents a moderate level of evidence and practical recommendations with great robustness in neonates, pediatric and patients with renal impairment. However, it is important to investigate in other subpopulations known to present altered vancomycin pharmacokinetics (eg neurosurgical, oncological and cystic fibrosis patients), where evidence is still unsufficient
Permeability measurements of two low-density phenolic-nylon chars Final report
Permeability measurements of low-density phenolic-nylon chars in gaseous nitrogen and heliu
Squeeze film dampers with oil hole feed
To improve the damping capability of squeeze film dampers, oil hole feed rather than circumferential groove feed is a practical proposition. However, circular orbit response can no longer be assumed, significantly complicating the design analysis. This paper details a feasible transient solution procedure for such dampers, with particular emphasis on the additional difficulties due to the introduction of oil holes. It is shown how a cosine power series solution may be utilized to evaluate the oil hole pressure contributions, enabling appropriate tabular data to be compiled. The solution procedure is shown to be applicable even in the presence of flow restrictors, albeit at the expense of introducing an iteration at each time step. Though not of primary interest, the procedure is also applicable to dynamically loaded journal bearings with oil hole feed
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