15,688 research outputs found
X-ray and radio prompt emission from a hypernova SN 2002ap
Here we report on combined X-ray and radio observations of SN 2002ap with
XMM-Newton ToO observation and GMRT observations aided with VLA published
results. In deriving the X-ray flux of SN 2002ap we account for the
contribution of a nearby source, found to be present in the pre-SN explosion
images obtained with Chandra observatory. We also derive upper limits on mass
loss rate from X-ray and radio data. We suggest that the prompt X-ray emission
is non-thermal in nature and its is due to the repeated compton boosting of
optical photons. We also compare SN's early radiospheric properties with two
other SNe at the same epoch.Comment: 4 pages, 5 figures. Uses espcrc2.sty. To appear in proceedings of
symposium on X-ray astronomy "The Restless High-Energy Universe", May 2003,
Amsterdam, The Netherlands, eds. E.P.J. van den Heuvel, J.J.M. in 't Zand,
and R.A.M.J. Wijer
Mode-matching without root-finding: Application to a dissipative silencer
This article presents an analytic mode-matching approach suitable for modelling the propagation of sound in a two-dimensional, three-part, ducting system. The approach avoids the need to the find roots of the characteristic equation for the middle section of the duct (the component) and is readily applicable to a broad class of problems. It is demonstrated that the system of equations, derived via analytic mode-matching, exhibits certain features which ensure that they can be re-cast into a form that is independent of the roots of the characteristic equation for the component. The precise details of the component are irrelevant to the procedure; it is required only that there exists an orthogonality relation, or similar, for the eigenmodes corresponding to the propagating wave-forms in this region. The method is applied here to a simple problem involving acoustic transmission through a dissipative silencer of the type commonly found in heating ventilation and air-conditioning (HVAC) ducts. With reference to this example, the silencer transmission loss is computed, and the power balance for the silencer is investigated and is shown to be an identity that is necessarily satisfied by the system of equations, regardless of the level of truncation
High aspect reactor vessel and method of use
An improved bio-reactor vessel and system useful for carrying out mammalian cell growth in suspension in a culture media are presented. The main goal of the invention is to grow and maintain cells under a homogeneous distribution under acceptable biochemical environment of gas partial pressures and nutrient levels without introducing direct agitation mechanisms or associated disruptive mechanical forces. The culture chamber rotates to maintain an even distribution of cells in suspension and minimizes the length of a gas diffusion path. The culture chamber design is presented and discussed
Possible existence of wormholes in the galactic halo region
Two observational results, the density profile from simulations performed in
the CDM scenario and the observed flat galactic rotation curves, are
taken as input with the aim of showing that the galactic halo possesses some of
the characteristics needed to support traversable wormholes. This result should
be sufficient to provide an incentive for scientists to seek observational
evidence for wormholes in the galactic halo region.Comment: 11 pages, 3 figures, 1 table, Eur. Phys. J. C (2014) 74:2750, DOI
10.1140/epjc/s10052-014-2750-
Classical T Tauri-like Outflow Activity in the Brown Dwarf Mass Regime
Over the last number of years spectroscopic studies have strongly supported
the assertion that protostellar accretion and outflow activity persists to the
lowest masses. In this paper we present the results of our latest investigation
of brown dwarf (BD) outflow activity and report on the discovery of two new
outflows. Here ISO-Oph 32 is shown to drive a blue-shifted outflow with a
radial velocity of 10-20 km/s and spectro-astrometric analysis constrains the
position angle of this outflow to 240 +/- 7 degrees. The BD candidate ISO-Cha1
217 is found to have a bipolar outflow bright in several key forbidden lines
(radial velocity = -20 km/s, +40 km/s) and with a PA of 190-210 degrees. A
striking feature of the ISO-Cha1 217 outflow is the strong asymmetry between
the red and blue-shifted lobes. This asymmetry is revealed in the relative
brightness of the two lobes (red-shifted lobe is brighter), the factor of two
difference in radial velocity (the red-shifted lobe is faster) and the
difference in the electron density (again higher in the red lobe). Such
asymmetries are common in jets from low mass protostars and the observation of
a marked asymmetry at such a low mass supports the idea that BD outflow
activity is scaled down from low mass protostellar activity.
In addition to presenting these new results, a comprehensive comparison is
made between BD outflow activity and jets launched by CTTSs. In particular, the
application of current methods for investigating the excitation conditions and
mass loss rates in CTT jets to BD spectra is explored.Comment: Accepted by Astrophysical Journa
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