Timing of pulsars found in a deep Parkes multibeam survey

We have carried out a sensitive radio pulsar survey along the northern Galactic plane ($50^{\circ} < l < 60^{\circ}$ and |b| \lapp 2^{\circ}) using the Parkes 20-cm multibeam system. We observed each position for 70-min on two separate epochs. Our analyses to date have so far resulted in the detection of 32 pulsars, of which 17 were previously unknown. Here we summarize the observations and analysis and present the timing observations of 11 pulsars and discovery parameters for a further 6 pulsars. We also present a timing solution for the 166-ms bursting pulsar, PSR~J1938+2213, previously discovered during an Arecibo drift-scan survey. Our survey data for this pulsar show that the emission can be described by a steady pulse component with bursting emission, which lasts for typically 20--25 pulse periods, superposed. Other new discoveries are the young 80.1-ms pulsar PSR~J1935+2025 which exhibits a significant amount of unmodeled low-frequency noise in its timing residuals, and the 4.2-ms pulsar PSR~J1935+1726 which is in a low-mass binary system with a 90.7-day circular orbit.Comment: 6 pages, 2 figures, accepted for publication in MNRA

Social perception and executive function following stroke

Components of social perception include the ability to recognise and interpret both verbal and non-verbal emotional cues, such as vocal tone and facial expression. Functional brain imaging studies have shown that the frontal cortex of the brain is more active during tasks involving social and emotional perception (Baron-Cohen et ah, 1994). Individuals with frontal lobe lesions have been shown to have acquired difficulties in emotional and social functioning similar to those in which social functioning deficits are frequently observed, such as people with autism (Baron-Cohen, 1985). Difficulties in emotional perception has also been found in individuals who have sustained a brain injury (Cicone et ah, 1980). Additionally, acquired social perception deficits have been observed in stroke patients (Happe et ah, 1999). Executive functioning is also seen as being mediated by the frontal cortex (Dela Salla et ah, 1998). The aim of this present study was to investigate executive function and social perception in post-stroke individuals.The hypotheses were that stroke patients would show a reduced ability in social perception compared to matched controls and that executive functioning would be positively associated with social perception. Twenty-two individuals who had experienced a stroke were assessed on tasks of executive function and compared to a control group on tasks of emotional perception and social awareness.The results were analysed within and between groups and are discussed with reference to theories linking executive function and social perception with the frontal cortex. The findings of this present study indicated no significant differences in the recognition of emotion between individuals who have sustained lesions to the brain following stroke and age-matched controls. Also, no significant differences were found on tasks of social perception relative to controls. However, there is some evidence to suggest that the control group may have performed at an unexpectedly low level. Significant and positive associations were observed between executive function and both emotion recognition tasks and tasks of social perception. Methodological issues and conclusions are discussed

Glioblastoma in the elderly - how do we choose who to treat?

Objective: Glioblastoma (GBM) is the commonest primary malignant brain tumour amongst the adult population. Incidence peaks in the 7th and 8th decades of life and as our global population ages, rates are increasing. GBM is an almost universally fatal disease with life expectancy in the range of 3–5 months amongst the elderly. Materials and Methods: The assessment of elderly GBM patients prior to treatment decisions is poorly researched and unstandardised. In order to begin tackling this issue we performed a cross-sectional survey across all UK based consultant neuro-oncologists to review their current practice in assessing elderly GBM patients. Results: There were 56 respondents from a total of 93 recipients (60% response rate). All respondents confirmed that at least some patients aged 70 or over were referred to their clinics from the local multidisciplinary team meeting (MDT). Only 18% of consultants routinely performed a cognitive or frailty screening test at initial consultation. Of those who performed a screening test, the majority reported that the results of the test changed their treatment decision in approximately 50% of cases. Participants ranked performance status as the most important factor in determining treatment decisions. Conclusions: Considering the heterogeneity of this patient population, we argue that performance status is a crude measure of vulnerability within this cohort. Elderly GBM patients represent a unique clinical scenario because of the complexity of distinguishing neuro-oncology related symptoms from general frailty. There is a need for specific geriatric assessment models tailored to the elderly neuro-oncology population in order to facilitate treatment decisions

A Search for Sub-millisecond Pulsations in Unidentified FIRST and NVSS Radio Sources

We have searched 92 unidentified sources from the FIRST and NVSS 1400 MHz radio survey catalogs for radio pulsations at 610 MHz. The selected radio sources are bright, have no identification with extragalactic objects, are point-like and are more than 5% linearly polarized. Our search was sensitive to sub-millisecond pulsations from pulsars with dispersion measures (DMs) less than 500 pc cm-3 in the absence of scattering. We have detected no pulsations from these sources and consider possible effects which might prevent detection. We conclude that as a population, these sources are unlikely to be pulsars.Comment: 8 pages, including 2 tables and 1 figure. Accepted for publication in A

Heartbeat of the Mouse: a young radio pulsar associated with the axisymmetric nebula G359.23-0.82

We report the discovery of PSR J1747-2958, a radio pulsar with period P = 98 ms and dispersion measure DM = 101 pc/cc, in a deep observation with the Parkes telescope of the axially-symmetric "Mouse" radio nebula (G359.23-0.82). Timing measurements of the newly discovered pulsar reveal a characteristic age Pdt/2dP = 25 kyr and spin-down luminosity dE/dt = 2.5e36 erg/s. The pulsar (timing) position is consistent with that of the Mouse's "head". The distance derived from the DM, ~2 kpc, is consistent with the Mouse's distance limit from HI absorption, < 5.5 kpc. Also, the X-ray energetics of the Mouse are compatible with being powered by the pulsar. Therefore we argue that PSR J1747-2958, moving at supersonic speed through the local interstellar medium, powers this unusual non-thermal nebula. The pulsar is a weak radio source, with period-averaged flux density at 1374 MHz of 0.25 mJy and luminosity ~1 mJy kpc^2.Comment: 6 pages, 2 figures, accepted for publication in ApJ Letter

Implementation of barycentric resampling for continuous wave searches in gravitational wave data

We describe an efficient implementation of a coherent statistic for continuous gravitational wave searches from neutron stars. The algorithm works by transforming the data taken by a gravitational wave detector from a moving Earth bound frame to one that sits at the Solar System barycenter. Many practical difficulties arise in the implementation of this algorithm, some of which have not been discussed previously. These difficulties include constraints of small computer memory, discreteness of the data, losses due to interpolation and gaps in real data. This implementation is considerably more efficient than previous implementations of these kinds of searches on Laser Interferometer Gravitational Wave (LIGO) detector data.Comment: 10 pages, 3 figure

Observations of 20 millisecond pulsars in 47 Tucanae at 20 cm

We have used a new observing system on the Parkes radio telescope to carry out a series of pulsar observations of the globular cluster 47 Tucanae at 20-cm wavelength. We detected all 11 previously known pulsars, and have discovered nine others, all of which are millisecond pulsars in binary systems. We have searched the data for relatively short orbital period systems, and found one pulsar with an orbital period of 96 min, the shortest of any known radio pulsar. The increased rate of detections with the new system resulted in improved estimates of the flux density of the previously known pulsars, determination of the orbital parameters of one of them, and a coherent timing solution for another one. Five of the pulsars now known in 47 Tucanae have orbital periods of a few hours and implied companion masses of only ~ 0.03 Msun. Two of these are eclipsed at some orbital phases, while three are seen at all phases at 20 cm but not always at lower frequencies. Four and possibly six of the other binary systems have longer orbital periods and companion masses ~ 0.2 Msun, with at least two of them having relatively large orbital eccentricities. All 20 pulsars have rotation periods in the range 2-8 ms.Comment: 15 pages, 6 embedded EPS figures, to be published in The Astrophysical Journa

A bright millisecond radio burst of extragalactic origin

Pulsar surveys offer one of the few opportunities to monitor even a small fraction (~0.00001) of the radio sky for impulsive burst-like events with millisecond durations. In analysis of archival survey data, we have discovered a 30-Jy dispersed burst of duration <5 ms located three degrees from the Small Magellanic Cloud. The burst properties argue against a physical association with our Galaxy or the Small Magellanic Cloud. Current models for the free electron content in the Universe imply a distance to the burst of <1 Gpc No further bursts are seen in 90-hr of additional observations, implying that it was a singular event such as a supernova or coalescence of relativistic objects. Hundreds of similar events could occur every day and act as insightful cosmological probes.Comment: 18 pages, 4 figures. Accepted by Science. Published electronically via Science Express on September 27, 200

Estimating the sensitivity of wide-parameter-space searches for gravitational-wave pulsars

This paper presents an in-depth study of how to estimate the sensitivity of searches for gravitational-wave pulsars -- rapidly-rotating neutron stars which emit quasi-sinusoidal gravitational waves. It is particularly concerned with searches over a wide range of possible source parameters, such as searches over the entire sky and broad frequency bands. Traditional approaches to estimating the sensitivity of such searches use either computationally-expensive Monte Carlo simulations, or analytic methods which sacrifice accuracy by making an unphysical assumption about the population of sources being searched for. This paper develops a new, analytic method of estimating search sensitivity which does not rely upon this unphysical assumption. Unlike previous analytic methods, the new method accurately predicts the sensitivity obtained using Monte Carlo simulations, while avoiding their computational expense. The change in estimated sensitivity due to properties of the search template bank, and the geographic configuration of the gravitational wave detector network, are also investigated.Comment: 16 figures, 2 tables, REVTeX 4.1; minor typos corrected from v2, updated reference