Some Experimental Signatures to look for Time-reversal Violating superconductors

We discuss some experimental signatures associated with the topological structures of unconventional superconductor order parameters of form $d_{x^2-y^2}+ix$, where $x=s,p_x \pm p_y$, or $d_{xy}$. Specifically, we study the topological surface states on the $(110)$ and equivalent surfaces of such superconductors which are observable in Andreev tunneling experiments, as well as evaluate the magnetic flux trapped in superconducting rings of such superconductors with multiple grain-boundary Josephson junctions. Previous experiments are examined and several new experiments suggested.Comment: 11 pages, 3 figure

Development of mainshaft seals for advanced air breathing propulsion systems, phase 1 Final report, 25 Jun. 1965 - 25 Jul. 1967

Comparison of gas film mainshaft seals with rubbing contract seals for high temperature, high speed, and high pressure gas turbine application

A study of energy concentration and drain in incompressible fluids

In this paper we examine two opposite scenarios of energy behavior for solutions of the Euler equation. We show that if $u$ is a regular solution on a time interval $[0,T)$ and if $u \in L^rL^\infty$ for some $r\geq \frac{2}{N}+1$, where $N$ is the dimension of the fluid, then the energy at the time $T$ cannot concentrate on a set of Hausdorff dimension samller than $N - \frac{2}{r-1}$. The same holds for solutions of the three-dimensional Navier-Stokes equation in the range $5/3<r<7/4$. Oppositely, if the energy vanishes on a subregion of a fluid domain, it must vanish faster than (T-t)^{1-\d}, for any \d>0. The results are applied to find new exclusions of locally self-similar blow-up in cases not covered previously in the literature.Comment: an update of the previous versio

Sintered aluminium heat pipe (SAHP)

This work is the product of an ongoing PhD project in the School of the Built and Natural Environment of Northumbria University in collaboration with the University of Liverpool and Thermacore Europe Ltd. The achievements at the end of the first year are summarized. The main objective of the project is to develop an aluminum ammonia heat pipe with a sintered wick structure. Currently available ammonia heat pipes mainly use extruded axially grooved aluminum tubes as a capillary wick. There have been a few attempts of employing porous steel or nickel wicks in steel tubes with ammonia as the working fluid (Bai, Lin et al. 2009)although it is a common practice in loop heat pipes but there is no report of aluminum-ammonia heat pipes porous aluminium wick structures. The main barrier is the difficulty of sintering aluminum powders to manufacture porous wicks. So far during this project promising sintered aluminum heat pipe samples have been manufactured using the Selective Laser Melting (SLM) technique with various wick characteristics. This SLM method has proven to be capable of manufacturing very complicated wick structures with different thickness, porosity, permeability and pore sizes in different regions of a heat pipe. In addition the entire heat pipe including the end cap, outer tube wall, wick and the fill tube can be generated in a single process

Bogoliubov transformations and exact isolated solutions for simple non-adiabatic Hamiltonians

We present a new method for finding isolated exact solutions of a class of non-adiabatic Hamiltonians of relevance to quantum optics and allied areas. Central to our approach is the use of Bogoliubov transformations of the bosonic fields in the models. We demonstrate the simplicity and efficiency of this method by applying it to the Rabi Hamiltonian.Comment: LaTeX, 16 pages, 1 figure. Minor additions and journal re

Increasing prevalence of asthma diagnosis and symptoms in children is confined to mild symptoms

BACKGROUND: The prevalence of childhood asthma is increasing but few studies have investigated trends in asthma severity. We investigated trends in asthma diagnosis and symptom morbidity between an eight year time period in a paired prevalence study. METHODS: All children in one single school year aged 8-9 years in the city of Sheffield were given a parent respondent questionnaire in 1991 and 1999 based on questions from the International Survey of Asthma and Allergy in Children (ISAAC). Data were obtained regarding the prevalence of asthma and wheeze and current (12 month) prevalences of wheeze attacks, speech limiting wheeze, nocturnal cough and wheeze, and exertional symptoms. RESULTS: The response rates in 1991 and 1999 were 4580/5321 (85.3%) and 5011/6021 (83.2%), respectively. There were significant increases between the two surveys in the prevalence of asthma ever (19.9% v 29.7%, mean difference 11.9%, 95% confidence interval (CI) 10.16 to 13.57, p<0.001), current asthma (10.3% v 13.0%, mean difference 2.7%, 95% CI 1.44 to 4.03, p<0.001), wheeze ever (30.3% v 35.8%, mean difference 5.7%, 95% CI 3.76 to 7.56, p<0.001), wheeze in the previous 12 months (17.0% v 19.4%, mean difference 2.5, 95% CI 0.95 to 4.07, p<0.01), and reporting of medication use (16.9% v 20%, mean difference 3.0%, 95% CI 1.46 to 4.62, p<0.001). There were also significant increases in reported hayfever and eczema diagnoses. CONCLUSIONS: Diagnostic labelling of asthma and lifetime prevalence of wheeze has increased. The current 12 month point prevalence of wheeze has increased but this is confined to occasional symptoms. The increased medication rate may be responsible for the static prevalence of severe asthma symptoms. The significant proportion of children receiving medication but reporting no asthma symptoms identified from our 1999 survey suggests that some children are being inappropriately treated or overtreated

Tilting instability and other anomalies in the flux-lattice in some magnetic superconductors

The flux-line lattice in the compound $ErNi_2B_2C$, which has a tendency to ferromagnetic order in the a-b plane is studied with external magnetic field direction close to the c-axis. We show the existence of an instability where the direction of flux-lines spontaneously tilts away from that of the applied field near the onset of ferromagnetic order. The enhanced fluctuations in the flux lattice and the square flux lattice recently observed are explained and further experiments suggested.Comment: 12 pages, Latex file, no figur

Information and Particle Physics

Information measures for relativistic quantum spinors are constructed to satisfy various postulated properties such as normalisation invariance and positivity. Those measures are then used to motivate generalised Lagrangians meant to probe shorter distance physics within the maximum uncertainty framework. The modified evolution equations that follow are necessarily nonlinear and simultaneously violate Lorentz invariance, supporting previous heuristic arguments linking quantum nonlinearity with Lorentz violation. The nonlinear equations also break discrete symmetries. We discuss the implications of our results for physics in the neutrino sector and cosmology

Collapse of Vacuum Bubbles in a Vacuum

Motivated by the discovery of a plenitude of metastable vacua in a string landscape and the possibility of rapid tunneling between these vacua, we revisit the dynamics of a false vacuum bubble in a background de Sitter spacetime. We find that there exists a large parameter space that allows the bubble to collapse into a black hole or to form a wormhole. This may have interesting implications to inflationary physics.Comment: 8 pages including 6 figures, LaTex; references adde