Characterization of bulk MgB2 synthesized by infiltration and growth

Superconducting MgB2 has been synthesized successfully by a modified infiltration and growth (IG) technique. The ambient pressure technique is relatively simple and scalable to complex shaped bulks. The extent of MgB 2 phase formation has been found to be influenced strongly by the IG process time and/or temperature, and this is found to reflect in the X-ray diffraction patterns, magnetization measurements, and microhardness. Scanning electron microscopy images show a bimodal particle size distribution with 20-50 nm sized fine precipitates in the inter particle region. A critical current density of 400 kA cm-2 was measured at 5 K.KACST-Cambridge Research Centre, Cambridge, U.K

The Venus ionosphere in the northern polar region

PLASLIFE is a computer simulation which assists in the interpretation of high latitude ionospheric observations and, in this study, is applied to the polar regions of Venus. The Venus Express spacecraft samples the high latitude ionosphere in the northern hemisphere of the planet. On 4 August 2008 it was inserted into a new orbit with pericentre located below 200 km close to 86° N. The ASPERA-4 instrument on the spacecraft records the first extended in situ data set of the plasma environment in this sector. The observed ionospheric ion and electron populations exhibit significant variation between orbits and, by compensating for the effects of solar zenith angle and altitude, the relative contributions of photoionisation and plasma transport can be investigated. These variations are discussed with respect to parameters including local time and solar flux. Comparisons are drawn with the terrestrial ionosphere

A Search for Pulsars in Quiescent Soft X-Ray Transients. I

We have carried out a deep search at 1.4 GHz for radio pulsed emission from six soft X-ray transient sources observed during their X-ray quiescent phase. The commonly accepted model for the formation of the millisecond radio pulsars predicts the presence of a rapidly rotating, weakly magnetized neutron star in the core of these systems. The sudden drop in accretion rate associated with the end of an X-ray outburst causes the Alfv\`en surface to move outside the light cylinder, allowing the pulsar emission process to operate. No pulsed signal was detected from the sources in our sample. We discuss several mechanisms that could hamper the detection and suggest that free-free absorption from material ejected from the system by the pulsar radiation pressure could explain our null result.Comment: accepted by Ap

Radio pulsar populations

The goal of this article is to summarize the current state of play in the field of radio pulsar statistics. Simply put, from the observed sample of objects from a variety of surveys with different telescopes, we wish to infer the properties of the underlying sample and to connect these with other astrophysical populations (for example supernova remnants or X-ray binaries). The main problem we need to tackle is the fact that, like many areas of science, the observed populations are often heavily biased by a variety of selection effects. After a review of the main effects relevant to radio pulsars, I discuss techniques to correct for them and summarize some of the most recent results. Perhaps the main point I would like to make in this article is that current models to describe the population are far from complete and often suffer from strong covariances between input parameters. That said, there are a number of very interesting conclusions that can be made concerning the evolution of neutron stars based on current data. While the focus of this review will be on the population of isolated Galactic pulsars, I will also briefly comment on millisecond and binary pulsars as well as the pulsar content of globular clusters and the Magellanic Clouds.Comment: 16 pages, 6 figures, to appear in Proceedings of ICREA Workshop on The High-Energy Emission from Pulsars and their Systems, Sant Cugat, Spain, 2010 April 12-16 (Springer

Smooth signal extraction from instantaneous mixtures

Published versio

A C.elegans inspired robotic model for pothole detection

Animals navigate complex and variable environments, but often use only limited sensory information. Here we present a simulated robot system using a C. elegans inspired sensory model and navigation strategy and demonstrate its ability to successfully identify specific, discretely located cues. We show a range of conditions under which this approach has performance benefits over other search strategies

Long-term benefit from immune modulation and anti-inflammatory treatment in metastatic mesothelioma.

A 64 year old male heating engineer was investigated for a persistent cough and found to have epithelioid mesothelioma with pleural effusion, lung nodules and increased thoracic lymph nodes. He declined standard of care treatment following his own research and he was enrolled in a named patient programme of IMM-101. He was advised to correct his low vitamin D3 level and to start using anti-inflammatories such as aspirin, bromelain and low dose Naltrexone. At review one year later a CT scan showed no change and he continued on the regimen. Four years after the diagnosis a CT scan showed that there was a modest but definite progression of the left malignant pleural thickening, and a new right-sided effusion, enlargement of several intrathoracic nodes which had been noted on the early scans. The chest wall lump eventually broke down and required local radiotherapy. He then developed abdominal pain and found to have peritoneal disease. Last year he obtained the cannabinoids CBD and THC which slowed down the disease and a CT scan after he had been on this for six months, showed that his disease was fairly stable with marginal progression

The cementation technique for coating carbon fibres

The cementation technique is used in a modified form where glacial acetic acid is added to the salt solution as an activating agent so that the displaced metal can wet the carbon fiber better. The feasibility of the technique is demonstrated on three types of carbon fibers. Copper, nickel and cobalt are deposited onto the carbon fiber from the corresponding salt solutions using four displacing agents, Zn, Mg, Al and Fe. To obtain uniform, continuous and adherent coatings, the following parameters are investigated and optimized: the metal ion solution concentration, the activation treatment of the fibers, temperature of the solution, time of deposition, effect of the reducing agent, and particle size of the reducing agent. The characterization of the coating is made on the basis of metallographic examination and tensile properties of the coated fibers. It is shown that by controlling the size of the reducing agent, acid concentration, solution concentration and temperature, uniform and adherent coatings can be obtained. The coating fibers are introduced into an aluminum matrix by an infiltration technique and are uniformly distributed in the composit