4,578 research outputs found
Data Reduction and Analysis of Photometric Data for 48 Evolved Stars from the All Sky Automated Survey and Valparaiso University Observatory
We are carrying out research to determine the pulsation period of a specific stage in evolved, low-mass stars’ life cycles called Proto-Planetary Nebulae. Our datasets come from The Valparaiso University Observatory (VUO), as well as The All Sky Automated Survey – All Sky Catalogue (ASAS-ASC), and The All Sky Automated Survey for Supernova (ASAS-SN). These datasets complement each other to ensure that we get high-quality data for our very faint objects over long intervals of time in both hemispheres. The VUO has been observing on this project for over 20 years. The ASAS-ASC and ASAS-SN data recently became open to the public and we are using them in our analysis. We are using these three datasets to search for periodic photometric variability in 48 evolved stars. We do this by using a sophisticated period search program called Period04. Our research has found 18 objects that have one or more significant periods ranging from 37 to 208 days
Data Reduction and Analysis of Photometric Data for 48 Evolved Stars from the All Sky Automated Survey and Valparaiso University Observatory
We are carrying out research to determine the pulsation period of a specific stage in evolved, low-mass stars’ life cycles called Proto-Planetary Nebulae. Our datasets come from The Valparaiso University Observatory (VUO), as well as The All Sky Automated Survey – All Sky Catalogue (ASAS-ASC), and The All Sky Automated Survey for Supernova (ASAS-SN). These datasets complement each other to ensure that we get high-quality data for our very faint objects over long intervals of time in both hemispheres. The VUO has been observing on this project for over 20 years. The ASAS-ASC and ASAS-SN data recently became open to the public and we are using them in our analysis. We are using these three datasets to search for periodic photometric variability in 48 evolved stars. We do this by using a sophisticated period search program called Period04. Our research has found 18 objects that have one or more significant periods ranging from 37 to 208 days
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Arterial-portal fistula treated with hepatic arterial embolization and portal venous aneurysm stent-graft exclusion complicated by type 2 endoleak.
Intrahepatic arterioportal fistulas may be complicated by portal hypertension. An associated portal venous aneurysm (PVA) may impinge upon adjacent structures or rupture. We present a 65-year-old man with an intrahepatic Intrahepatic arterioportal fistula and 6.4 × 5.8 cm right portal vein aneurysm extending within 0.4 cm of the hepatic margin, associated with pain concerning for impending rupture. The PVA was refractory to transarterial embolization due to recruitment of arterial collaterals. Therefore, it was additionally excluded from the portal vein with a 12 mm × 9.5 cm venous stent graft. Although endovascular therapy thrombosed the aneurysm and improved symptoms, it was complicated by a type 2 endoleak into the PVA
A Parkes half-Jansky sample of GPS galaxies
This paper describes the selection of a new southern/equatorial sample of
Gigahertz Peaked Spectrum (GPS) radio galaxies, and subsequent optical CCD
imaging and spectroscopic observations using the ESO 3.6m telescope. The sample
consists of 49 sources with -4020 degrees, and
S(2.7GHz)>0.5 Jy, selected from the Parkes PKSCAT90 survey. About 80% of the
sources are optically identified, and about half of the identifications have
available redshifts. The R-band Hubble diagram and evolution of the host
galaxies of GPS sources are reviewed.Comment: Latex, 12 pages, 8 figures, accepted for publication in MNRA
Slowing Down and Scattering of Ions in Solids
The interaction of particle beams with solids yields three parts, i.e. reflected particles, penetrating particles and trapped particles. At very low energies particle reflection is dominant, at very high energies penetration is the most important effect. Trapped particles are the result of energy loss processes, which on the other hand cause radiation damage in the solid. In the energy range discussed here, i.e. above energies where quantum effects, diffraction etc. are important and below energies where nuclear reactions, relativistic effects etc. may occur, the particle trajectories are classical. The energy loss process can be treated separately as nuclear and electronic stopping power. The collisions of the projectiles with target atoms are hence binary collisions involving a properly chosen screened Coulomb-potential. In single crystals the structural properties enable channeling, which is a very useful tool in sol id state analysis. The electronic stopping includes contributions from single collision processes and collective excitations. Both effects can be described by a dielectric response function. The range of applications covers analytical methods, means to modify solid state properties and also the production of thin films
Hodge Duality on the Brane
It has been claimed that whereas scalars can be bound to a Randall-Sundrum
brane, higher p-form potentials cannot, in contradiction with the Hodge duality
between 0-form and 3-form potentials in the five-dimensional bulk. Here we show
that a 3-form in the bulk correctly yields a 2-form on the brane, in complete
agreement with both bulk and brane duality. We also emphasize that the
phenomenon of photon screening in the Randall-Sundrum geometry is ruled out by
the bulk Einstein equation.Comment: 6 pages, Latex. We emphasize that the phenomenon of photon screening
in the Randall-Sundrum geometry is ruled out by the bulk Einstein equatio
Dynamic PRA: an Overview of New Algorithms to Generate, Analyze and Visualize Data
State of the art PRA methods, i.e. Dynamic PRA
(DPRA) methodologies, largely employ system
simulator codes to accurately model system dynamics.
Typically, these system simulator codes (e.g., RELAP5 )
are coupled with other codes (e.g., ADAPT,
RAVEN that monitor and control the simulation. The
latter codes, in particular, introduce both deterministic
(e.g., system control logic, operating procedures) and
stochastic (e.g., component failures, variable uncertainties)
elements into the simulation. A typical DPRA analysis is
performed by:
1. Sampling values of a set of parameters from the
uncertainty space of interest
2. Simulating the system behavior for that specific set of
parameter values
3. Analyzing the set of simulation runs
4. Visualizing the correlations between parameter values
and simulation outcome
Step 1 is typically performed by randomly sampling
from a given distribution (i.e., Monte-Carlo) or selecting
such parameter values as inputs from the user (i.e.,
Dynamic Event Tre
Massive galaxies with very young AGN
Gigahertz Peaked Spectrum (GPS) radio galaxies are generally thought to be
the young counterparts of classical extended radio sources and live in massive
ellipticals. GPS sources are vital for studying the early evolution of
radio-loud AGN, the trigger of their nuclear activity, and the importance of
feedback in galaxy evolution. We study the Parkes half-Jansky sample of GPS
radio galaxies of which now all host galaxies have been identified and 80% has
their redshifts determined (0.122 < z < 1.539). Analysis of the absolute
magnitudes of the GPS host galaxies show that at z > 1 they are on average a
magnitude fainter than classical 3C radio galaxies. This suggests that the AGN
in young radio galaxies have not yet much influenced the overall properties of
the host galaxy. However their restframe UV luminosities indicate that there is
a low level of excess as compared to passive evolution models.Comment: To appear in the proceedings of "Formation and Evolution of Galaxy
Bulges", IAUS 245; M. Bureau, E. Athanassoula & B. Barbuy, ed
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