The X-ray View of Galaxies in Compact Groups and the Coma Cluster Infall Region

In this thesis, we have explored what information may be gleaned from X-ray observations of galaxies in dense environments. We use X-ray observations from XMM- Newton and the Chandra X-ray Observatory, and multi-wavelength ancillary data, to investigate the X-ray emission of galaxies. First, we study the distribution and properties of the intragroup diffuse X-ray emission in compact groups (CGs) of galaxies. From a sample of 19 CGs, we find the morphology of hot gas in low-mass groups is varied, and most systems have hot gas (if any) associated with only individual members. The galaxy-linked hot gas is coupled with high star formation rates (SFRs), while only CGs with high baryonic masses have substantial hot gas linked to the group environment. It is high-mass CGs that also agree well with the observed scaling relations between diffuse X-ray luminosity (LX), gas temperature, and velocity dispersion predicted and observed in galaxy clusters, indicating that the hot gas in only massive CGs is virialized. We also investigate the relations between LX, SFR, and stellar mass from individual members of CGs and the infall region of the nearby Coma galaxy cluster, which is the only environment that has a mid-infrared galaxy color distribution similar to CGs. The Coma galaxies agree with the scaling relations between LX, SFR, and stellar mass from the literature within uncertainties, while the CG members often show an X-ray excess. We also used our multi-wavelength observations to identify active galaxies in the Coma infall sample and find that the fraction of active galaxies is similar to the CG environment. From our observations of the diffuse X-ray emission in CGs, we find it unlikely that the intragroup hot gas is responsible for the rapid transformation of galaxies from star-forming to quiescent. While the fraction of nuclear activity in Coma infall and CG galaxies is similar, which may reflect the influence of multi-galaxy gravitational interactions, the X-ray emission from individual galaxies in the two environments is also markedly different

Service Induced Byproducts for Localized Drug Delivery in Orthopaedic Implants

A composite material including ultra-high molecular weight polyethylene in conjunction with a biologically active agent is described. The biologically active agent can be, for example, an anti-osteolytic agent such as a bisphosphonate. The composite material can be utilized in forming implants such as total joint replacement implants. The biologically active agent can be released from the composite material either from the bulk or from wear particles released from the surface of the implant component during use. Upon release, the biologically active agent can carry out the intended function of the agent

Hexabromocyclododecane and hexachlorocyclohexane: How lessons learnt have led to improved regulation

This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2014 Taylor & Francis.The use of chemicals by society has many benefits but contamination of the environment is an unintended consequence. One example is the organochlorine compound hexachlorocyclohexane (HCH). During the 1980s, when HCH was banned in many countries, the brominated flame retardant, hexabromocyclododecane (HBCD), found increasing use. The persistent, bioaccumulative, and toxic characteristics of HBCD are, 30 years later, likely to warrant global action on production and use under the Stockholm Convention on persistent organic pollutants. Historical lessons have taught us that we need to control the use of chemicals and programs are in place worldwide in an attempt to do so.Tertiary Education Trust Fund, Nigeri

Surface induced magnetization reversal of MnP nanoclusters embedded in GaP

We investigate the quasi-static magnetic behavior of ensembles of non-interacting ferromagnetic nanoparticles consisting of MnP nanoclusters embedded in GaP(001) epilayers grown at 600, 650 and 700{\deg}C. We use a phenomenological model, in which surface effects are included, to reproduce the experimental hysteresis curves measured as a function of temperature (120-260 K) and direction of the applied field. The slope of the hysteresis curve during magnetization reversal is determined by the MnP nanoclusters size distribution, which is a function of the growth temperature. Our results show that the coercive field is very sensitive to the strength of the surface anisotropy, which reduces the energy barrier between the two states of opposite magnetization. Notably, this reduction in the energy barrier increases by a factor of 3 as the sample temperature is lowered from 260 to 120 K.Comment: 7 pages, 5 figure

Exploring X-ray Binary Populations in Compact Group Galaxies with ChandraChandra

We obtain total galaxy X-ray luminosities, $L_X$, originating from individually detected point sources in a sample of 47 galaxies in 15 compact groups of galaxies (CGs). For the great majority of our galaxies, we find that the detected point sources most likely are local to their associated galaxy, and are thus extragalactic X-ray binaries (XRBs) or nuclear active galactic nuclei (AGNs). For spiral and irregular galaxies, we find that, after accounting for AGNs and nuclear sources, most CG galaxies are either within the $\pm1\sigma$ scatter of the Mineo et al. (2012) $L_X$ - star formation rate (SFR) correlation or have higher $L_X$ than predicted by this correlation for their SFR. We discuss how these "excesses" may be due to low metallicities and high interaction levels. For elliptical and S0 galaxies, after accounting for AGNs and nuclear sources, most CG galaxies are consistent with the Boroson et al. (2011) $L_X$ - stellar mass correlation for low-mass XRBs, with larger scatter, likely due to residual effects such as AGN activity or hot gas. Assuming non-nuclear sources are low- or high-mass XRBs, we use appropriate XRB luminosity functions to estimate the probability that stochastic effects can lead to such extreme $L_X$ values. We find that, although stochastic effects do not in general appear to be important, for some galaxies there is a significant probability that high $L_X$ values can be observed due to strong XRB variability.Comment: Accepted by Ap

A Kato type Theorem for the inviscid limit of the Navier-Stokes equations with a moving rigid body

The issue of the inviscid limit for the incompressible Navier-Stokes equations when a no-slip condition is prescribed on the boundary is a famous open problem. A result by Tosio Kato says that convergence to the Euler equations holds true in the energy space if and only if the energy dissipation rate of the viscous flow in a boundary layer of width proportional to the viscosity vanishes. Of course, if one considers the motion of a solid body in an incompressible fluid, with a no-slip condition at the interface, the issue of the inviscid limit is as least as difficult. However it is not clear if the additional difficulties linked to the body's dynamic make this issue more difficult or not. In this paper we consider the motion of a rigid body in an incompressible fluid occupying the complementary set in the space and we prove that a Kato type condition implies the convergence of the fluid velocity and of the body velocity as well, what seems to indicate that an answer in the case of a fixed boundary could also bring an answer to the case where there is a moving body in the fluid

Existence of global strong solutions to a beam-fluid interaction system

We study an unsteady non linear fluid-structure interaction problem which is a simplified model to describe blood flow through viscoleastic arteries. We consider a Newtonian incompressible two-dimensional flow described by the Navier-Stokes equations set in an unknown domain depending on the displacement of a structure, which itself satisfies a linear viscoelastic beam equation. The fluid and the structure are fully coupled via interface conditions prescribing the continuity of the velocities at the fluid-structure interface and the action-reaction principle. We prove that strong solutions to this problem are global-in-time. We obtain in particular that contact between the viscoleastic wall and the bottom of the fluid cavity does not occur in finite time. To our knowledge, this is the first occurrence of a no-contact result, but also of existence of strong solutions globally in time, in the frame of interactions between a viscous fluid and a deformable structure