Search for surviving companions in type Ia supernova remnants

The nature of the progenitor systems of type~Ia supernovae is still unclear. One way to distinguish between the single-degenerate scenario and double-degenerate scenario for their progenitors is to search for the surviving companions. Using a technique that couples the results from multi-dimensional hydrodynamics simulations with calculations of the structure and evolution of main-sequence- and helium-rich surviving companions, the color and magnitude of main-sequence- and helium-rich surviving companions are predicted as functions of time. The surviving companion candidates in Galactic type~Ia supernova remnants and nearby extragalactic type~Ia supernova remnants are discussed. We find that the maximum detectable distance of main-sequence surviving companions (helium-rich surviving companions) is $0.6-4$~Mpc ($0.4-16$~Mpc), if the apparent magnitude limit is 27 in the absence of extinction, suggesting that the Large and Small Magellanic Clouds and the Andromeda Galaxy are excellent environments in which to search for surviving companions. However, only five Ia~SNRs have been searched for surviving companions, showing little support for the standard channels in the singe-degenerate scenario. To better understand the progenitors of type Ia supernovae, we encourage the search for surviving companions in other nearby type Ia supernova remnants.Comment: 25 pages, 5 figures, and 2 tables. Accepted for publication in Ap

Simulations of the symbiotic recurrent nova V407 Cyg. I. Accretion and shock evolutions

The shock interaction and evolution of nova ejecta with a wind from a red giant star in a symbiotic binary system are investigated via three-dimensional hydrodynamics simulations. We specifically model the March 2010 outburst of the symbiotic recurrent nova V407~Cygni from the quiescent phase to its eruption phase. The circumstellar density enhancement due to wind-white dwarf interaction is studied in detail. It is found that the density-enhancement efficiency depends on the ratio of the orbital speed to the red giant wind speed. Unlike another recurrent nova, RS~Ophiuchi, we do not observe a strong disk-like density enhancement, but instead observe an aspherical density distribution with $\sim 20\%$ higher density in the equatorial plane than at the poles. To model the 2010 outburst, we consider several physical parameters, including the red giant mass loss rate, nova eruption energy, and ejecta mass. A detailed study of the shock interaction and evolution reveals that the interaction of shocks with the red giant wind generates strong Rayleigh-Taylor instabilities. In addition, the presence of the companion and circumstellar density enhancement greatly alter the shock evolution during the nova phase. The ejecta speed after sweeping out most of the circumstellar medium decreases to $\sim 100-300$ km-s$^{-1}$, depending on model, which is consistent with the observed extended redward emission in [N~II] lines in April 2011.Comment: ApJ, In Press. Simulation Animation: https://youtu.be/g5Nu7vDfCO

Improved facial feature fitting for model based coding and animation

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

The Forgotten Children

The “forgotten children” of pediatric cancer are the siblings. There is a dearth of literature published on the effects of cancer on the siblings’ psychosocial state. Despite significant improvements made in the survival of pediatric cancer patients, the psychosocial health of the siblings remains the same. The siblings’ need for support and understanding continue to go unnoticed. The aim of this chapter is to shed light on the roles siblings play in the pediatric cancer trajectory, as well as to recognize the emotional and psychological toll they endure through the experience of diagnosis, treatment, survival, and bereavement as the “forgotten children.

A water quality study of the eastern branch of the Lynnhaven Bay, Virginia

To alleviate the flooding in the drainage basin of the Lynnhaven River at Virginia Beach, Virginia, the U. S. Army Corps of Engineers has proposed to improve the waterways along the headwater of the river (House Document, 1976). The improvements include the widening and deepening of the existing canal, and the dredging of a new canal. As a result of the proposed project and the present rate of increase in area development, the freshwater runoff from the drainage basin and the tidal prism in the system are expected to increase. Since nonpoint sources are the only source of pollutants to the Eastern Branch of the Bay, the increase in freshwater runoff will have accompanying increase in pollutant loads of the same relative magnitude. The primary objective of this study is to assess the changes in water quality conditions as the results of the increases in freshwater discharge and in the tidal prism. This study consists of two parts. The field survey includes two slack water runs and a dye release experiment. The model study consists of model validation and projection of water quality changes

Identification of osteopontin-dependent signaling pathways in a mouse model of human breast cancer

<p>Abstract</p> <p>Background</p> <p>Osteopontin (OPN) is a secreted phosphoprotein which functions as a cell attachment protein and cytokine that signals through two cell adhesion molecules, α_vβ₃-integrin and CD44, to regulate cancer growth and metastasis. However, the signaling pathways associated with OPN have not been extensively characterized. In an in vivo xenograft model of MDA-MB-231 human breast cancer, we have previously demonstrated that ablation of circulating OPN with an RNA aptamer blocks interaction with its cell surface receptors to significantly inhibit adhesion, migration and invasion in vitro and local progression and distant metastases.</p> <p>Findings</p> <p>In this study, we performed microarray analysis to compare the transcriptomes of primary tumor in the presence and absence of aptamer ablation of OPN. The results were corroborated with RT-PCR and Western blot analysis. Our results demonstrate that ablation of OPN cell surface receptor binding is associated with significant alteration in gene and protein expression critical in apoptosis, vascular endothelial growth factor (VEGF), platelet derived growth factor (PDGF), interleukin-10 (IL-10), granulocyte-macrophage colony stimulating factor (GM-CSF) and proliferation signaling pathways. Many of these proteins have not been previously associated with OPN.</p> <p>Conclusion</p> <p>We conclude that secreted OPN regulates multiple signaling pathways critical for local tumor progression.</p