Catalytic surface effects on contaminated space shuttle tile in a dissociated nitrogen stream

Visual inspection revealed contamination on the surface of tiles removed from the lower section of the space shuttle orbiter after the second flight of Columbia (STS-2). Possible sources of this contamination and the effect on surface catalycity are presented

Performance of an ablator for Space Shuttle inorbit repair in an arc-plasma airstream

An ablator patch material performed well in an arc plasma environment simulating nominal Earth entry conditions for the Space Shuttle. Ablation tests using vacuum molded cones provided data to optimize the formulation of a two part polymer system for application under space conditions. The blunt cones were made using a Teflon mold and a state of the art caulking gun. Char stability of formulations with various amounts of catalyst and diluent were investigated. The char was found to be unstable in formulations with low amounts of catalyst and high amounts of diluent. The best polymer system determined by these tests was evaluated using a half tile patch in a multiple High Temperature Reusable surface Insulation tile model. It was demonstrated that this ablator could be applied in a space environment using a state of the art caulking gun, would maintain the outer mold line of the thermal protection system during entry, and would keep the bond line temperature at the aluminum tile interface below the design limit

Observer and Particle Transformations and Newton's Laws

A frequently confused point in studies of symmetry violation is the distinction between observer and particle transformations. In this work, we consider a model in which a coefficient in the Standard-Model Extension leads to violations of rotation invariance in Newton's second law. The model highlights the distinction between observer and particle transformations.Comment: Presented at the Sixth Meeting on CPT and Lorentz Symmetry, Bloomington, Indiana, June 17-21, 201

Cooling of Hybrid Neutron Stars and Hypothetical Self-bound Objects with Superconducting Quark Cores

We study the consequences of superconducting quark cores (with color-flavor-locked phase as representative example) for evolution of temperature profiles and the cooling curves in quark-hadron hybrid stars and in hypothetical self-bounded objects having no a hadron shell (quark core neutron stars). The quark gaps are varied from 0 to $\Delta_q =50$ MeV. For hybrid stars we find time scales of $1\div5$, $5\div10$ and $50\div100$ years for the formation of a quasistationary temperature distribution in the cases $\Delta_q =0$, 0.1 MeV and \gsim 1 MeV, respectively. These time scales are governed by the heat transport within quark cores for large diquark gaps (\Delta \gsim 1 MeV) and within the hadron shell for small diquark gaps (\Delta \lsim 0.1 MeV). For quark core neutron stars we find a time scale $\simeq 300$ years for the formation of a quasistationary temperature distribution in the case \Delta \gsim 10 MeV and a very short one for \Delta \lsim 1 MeV. If hot young compact objects will be observed they can be interpreted as manifestation of large gap color superconductivity. Depending on the size of the pairing gaps, the compact star takes different paths in the ${lg}T_s$ vs. ${lg} t$ diagram where $T_s$ is the surface temperature. Compared to the corresponding hadronic model which well fits existing data the model for the hybrid neutron star (with a large diquark gap) shows too fast cooling. The same conclusion can be drawn for the corresponding self-bound objects.Comment: 8 pages, 4 figures, uses aa-package (included), accepted for A&

Nuclear symmetry energy and the r-mode instability of neutron stars

We analyze the role of the symmetry energy slope parameter $L$ on the {\it r}-mode instability of neutron stars. Our study is performed using both microscopic and phenomenological approaches of the nuclear equation of state. The microscopic ones include the Brueckner--Hartree--Fock approximation, the well known variational equation of state of Akmal, Pandharipande and Ravenhall, and a parametrization of recent Auxiliary Field Diffusion Monte Carlo calculations. For the phenomenological approaches, we use several Skyrme forces and relativisic mean field models. Our results show that the {\it r}-mode instability region is smaller for those models which give larger values of $L$. The reason is that both bulk ($\xi$) and shear ($\eta$) viscosities increase with $L$ and, therefore, the damping of the mode is more efficient for the models with larger $L$. We show also that the dependence of both viscosities on $L$ can be described at each density by simple power-laws of the type $\xi=A_{\xi}L^{B_\xi}$ and $\eta=A_{\eta}L^{B_\eta}$. Using the measured spin frequency and the estimated core temperature of the pulsar in the low-mass X-ray binary 4U 1608-52, we conclude that observational data seem to favor values of $L$ larger than $\sim 50$ MeV if this object is assumed to be outside the instability region, its radius is in the range $11.5-12$($11.5-13$) km, and its mass $1.4M_\odot$($2M_\odot$). Outside this range it is not possible to draw any conclusion on $L$ from this pulsar.Comment: 10 pages, 6 figures. Version published in Physical Review

Experiences of diagnosis, stigma, culpability, and disclosure in male patients with hepatitis C virus: an interpretative phenomenological analysis

The current study aimed to explore the lived experience of patients with hepatitis C virus infection. Semi-structured interviews were conducted with seven male participants living with hepatitis C virus and were analysed using interpretative phenomenological analysis. Two master themes were identified: (1) diagnosis and the search for meaning and (2) impact of stigma on disclosure. Participants reported fears of contaminating others, feelings of stigma and concerns of disclosing the condition to others. Response to diagnosis, stigma and disclosure among the participants appeared to be interrelated and directly related to locus of blame for virus contraction. More specifically, hepatitis C virus transmission via medical routes led to an externalisation of culpability and an openness to disclosure. Transmission of hepatitis C virus as a direct result of intravenous drug use led to internalised blame and a fear of disclosure. The inter- and intra-personal consequences of hepatitis C virus explored in the current study have potential implications for tailoring future psychological therapy and psychoeducation to the specific needs of the hepatitis C virus population

Nucleon Superfluidity vs Observations of Cooling Neutron Stars

Cooling simulations of neutron stars (NSs) are performed assuming that stellar cores consist of neutrons, protons and electrons and using realistic density profiles of superfluid critical temperatures $T_{cn}(\rho)$ and $T_{cp}(\rho)$ of neutrons and protons. Taking a suitable profile of $T_{cp}(\rho)$ with maximum $\sim 5 \times 10^9$ K one can obtain smooth transition from slow to rapid cooling with increasing stellar mass. Adopting the same profile one can explain the majority of observations of thermal emission from isolated middle--aged NSs by cooling of NSs with different masses either with no neutron superfluidity in the cores or with a weak superfluidity, $T_{cn} < 10^8$ K. The required masses range from $\sim 1.2 M_\odot$ for (young and hot) RX J0822-43 and (old and warm) PSR 1055-52 and RX J1856-3754 to $\approx 1.45 M_\odot$ for the (colder) Geminga and Vela pulsars. Observations constrain the $T_{cn}(\rho)$ and $T_{cp}(\rho)$ profiles with respect to the threshold density of direct Urca process and maximum central density of NSs.Comment: 4 pages, 2 figures, AA Letters, accepte

Pairing and alpha-like quartet condensation in N=Z nuclei

We discuss the treatment of isovector pairing by an alpha-like quartet condensate which conserves exactly the particle number, the spin and the isospin. The results show that the quartet condensate describes accurately the isovector pairing correlations in the ground state of systems with an equal number of protons and neutronsComment: 4 pages, to appear in Journal of Physics: Conference Serie

Antimicrobial resistance: a biopsychosocial problem requiring innovative interdisciplinary and imaginative interventions

To date, antimicrobials have been understood through largely biomedical perspectives. There has been a tendency to focus upon the effectiveness of pharmaceuticals within individual bodies. However, the growing threat of antimicrobial resistance demands we reconsider how we think about antimicrobials and their effects. Rather than understanding them primarily within bodies, it is increasingly important to consider their effects between bodies, between species and across environments. We need to reduce the drivers of antimicrobial resistance (AMR) at a global level, focusing on the connections between prescribing in one country and resistance mechanisms in another. We need to engage with the ways antimicrobials within the food chain will impact upon human healthcare. Moreover, we need to realise what happens within the ward will impact upon the environment (through waste water). In the future, imaginative interventions will be required that must make the most of biomedicine but draw equally across a wider range of disciplines (e.g. engineering, ecologists) and include an ever-increasing set of professionals (e.g. nurses, veterinarians and farmers). Such collective action demands a shift to working in new interdisciplinary, inter-professional ways. Mutual respect and understanding is required to enable each perspective to be combined to yield synergistic effects