76 research outputs found
A Catalog of Very Isolated Galaxies from the SDSS Data Release 1
We present a new catalog of isolated galaxies obtained through an automated
systematic search. These 2980 isolated galaxies were found in approximately
2099 sq deg of sky in the Sloan Digital Sky Survey Data Release 1 (SDSS DR1)
photometry. The selection algorithm, implementing a variation on the criteria
developed by Karachentseva in 1973, proved to be very efficient and fast. This
catalog will be useful for studies of the general galaxy characteristics. Here
we report on our results.Comment: 67 pages, which includes 14 figures. Accepted for publication by A
Photometric study of the FUor star V 1735 Cyg (Elias 1-12)
Results from optical photometric observations of the PMS star V 1735 Cyg are reported. On the basis of observed outburst and spectral properties, V 1735 Cyg was classified as a FUor object. We present data from IRVB CCD photometric observations of the star collected from Introduction V 1735 Cyg (Elias 1-12) was discovered by IRVB light curves of V 1735 Cyg in the period . The arrows mark the upper limits from photographic observations made with Palomar, Tonantzintla and Rozhen Schmidt telescopes Results and Discussion Using the collected data from photographic and CCD observations we try to construct the historical light curve of V 1735 Cyg and to study the photometric behavior of the star around the optical outburst and in the time of set in brightness. The analysis of the available photometric data for V 1735 Cyg leads to some important conclusions. The time of rise in brightness and the star magnitude in the maximum light are still under discussion. The data from photographic observations made with the 50/70-cm Schmidt telescope from 1986 to 1992 show a strong light variability (∆V = 1 m .2). Taking into account the magnitudes from We find the photometric studies of FUor and FUor-like objects as very important for their exact classification. The problems with duration and possible recurrence of FUor stage can by solved by collecting photometric data from the photographic plate archives and with photometric monitoring in the present time. Another disputed point that can be solved by photometric monitoring of star forming regions is the percentage of PMS stars passing through a FUor outburst. Acknowledgements
Study of plasma polymer structures to induce composite layers
This study is designed to investigate the ability of plasma polymer films (PPHMDS), grown from the hexamethyldisiloxane
(HMDS) monomer on stainless steel (SS) and silica glass (SG) substrates, to induce the deposition of composite layers
from a mixture of saturated simulated body fluid (SBF) and detonation nanodiamond (DND) by a biomimetic process.
Results from FTIR and XPS studies showed that the structure of the PPHDMS layers depends on the nature of the
substrate, as well as on the deposition conditions and the influence of the subsequent deposition of the composite layers.
The PPHDMS structure appears to be covalently bonded to SG, compared to those on SS. After their immersion in the
mixture of SBF and DND, the layers grown on the SG_PPHDMS structure shows the existence of phosphate and carbonate
groups. On the SS_PPHMDS, it shows a predominantly carbon enrich deposit, which indicates that the lack of functional
polar groups of the SS_PPHMDS surfaces, and limits the process of precipitation of the SBF ions. The results emphasize
the potential for tailoring a plasma polymer structure PPHMDS, by varying the deposition conditions and substrate, in order
to use them as biocompatible materials
The Impact of Different Timing Schedules on Prostate HDR-Mono-Brachytherapy. A TCP Modeling Investigation
Background: Mechanistic TCP (tumor control probability) models exist that account for possible re-sensitization of an initially hypoxic tumor during treatment. This phenomenon potentially explains the better outcome of a 28-day vs 14-day treatment schedule of HDR (high dose rate) brachytherapy of low- to intermediate-risk prostate cancer as recently reported. Methods: A TCP model accounting for tumor re-sensitization developed earlier is used to analyze the reported clinical data. In order to analyze clinical data using individual TCP model, TCP distributions are constructed assuming inter-individual spread in radio-sensitivity. Results: Population radio-sensitivity parameter values are found that result in TCP population values which are close to the reported ones. Using the estimated population parameters, two hypothetical regimens are investigated that are shorter than the ones used clinically. The impact of the re-sensitization rate on the calculated treatment outcome is also investigated as is the anti-hypothesis that there is no re-sensitization during treatment. Conclusions: The carried out investigation shows that the observed clinical data cannot be described without assuming an initially hypoxic state of the tumor followed by re-oxygenation and, hence, re-sensitization. This phenomenon explains the better outcome of the prolonged treatment schedule compared to shorter regimens based on the fact that prostate cancer is a slowly repopulating tumor
The impact of different timing schedules on prostate HDR-mono-brachytherapy. A TCP modeling investigation
Background: Mechanistic TCP (tumor control probability) models exist that account for possible re-sensitization of an initially hypoxic tumor during treatment. This phenomenon poten-tially explains the better outcome of a 28-day vs 14-day treatment schedule of HDR (high dose rate) brachytherapy of low-to intermediate-risk prostate cancer as recently reported. Methods: A TCP model accounting for tumor re-sensitization developed earlier is used to analyze the reported clinical data. In order to analyze clinical data using individual TCP model, TCP distributions are con-structed assuming inter-individual spread in radio-sensitivity. Results: Population radio-sensitivity parameter values are found that result in TCP population values which are close to the reported ones. Using the estimated population parameters, two hypothetical regimens are investigated that are shorter than the ones used clinically. The impact of the re-sensitization rate on the calculated treatment outcome is also investigated as is the anti-hypothesis that there is no re-sensitization during treatment. Conclusions: The carried out investigation shows that the observed clinical data can-not be described without assuming an initially hypoxic state of the tumor followed by re-oxygena-tion and, hence, re-sensitization. This phenomenon explains the better outcome of the prolonged treatment schedule compared to shorter regimens based on the fact that prostate cancer is a slowly repopulating tumor
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