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We have used LOFAR to perform targeted millisecond pulsar surveys of Fermi γ-ray sources. Operating at a center frequency of 135 MHz, the surveys use a novel semi-coherent dedispersion approach where coherently dedispersed trials at coarsely separated dispersion measures are incoherently dedispersed at finer steps. Three millisecond pulsars have been discovered as part of these surveys. We describe the LOFAR surveys and the properties of the newly discovered pulsars.
Multi-decade observing campaigns of the globular clusters 47 Tucanae and M15 have led to an outstanding number of discoveries. Here, we report on the latest results of the long-term observations of the pulsars in these two clusters. For most of the pulsars in 47 Tucanae we have measured, among other things, their higher-order spin period derivatives, which have in turn provided stringent constraints on the physical parameters of the cluster, such as its distance and gravitational potential. For M15, we have studied the relativistic spin precession effect in PSR B2127+11C. We have used full-Stokes observations to model the precession effect, and to constrain the system geometry. We find that the visible beam of the pulsar is swiftly moving away from our line of sight and may very soon become undetectable. On the other hand, we expect to see the opposite emission beam sometime between 2041 and 2053.
PSR B1828–11 is a young pulsar once thought to be undergoing free precession and recently found instead to be switching magnetospheric states in tandem with spin-down changes. Here we show the two extreme states of the mode-changing found for this pulsar and comment briefly on its interpretation.
We report on a project to determine the proper motions of a sample of 13 young pulsars. Sky positions are measured with phase referencing using two elements of the MERLIN array, giving a baseline of 198km. This technique involves the concurrent observation of each pulsar with one or more extra-galactic reference sources located in the same primary beam. At an observing wavelength of 21 cm, this allows the measurement of pulsar positions to an accuracy greater than 1 mas.
The Parkes multibeam pulsar survey uses a 13-element receiver operating at a wavelength of 20 cm to survey the inner Galactic plane with remarkable sensitivity. To date we have collected and analyzed data from 45% of the survey region (|b| < 5°; 260° < l < 50°), and have discovered 440 pulsars, in addition to re-detecting 190 previously known ones. Most of the newly discovered pulsars are at great distances, as inferred from a median dispersion measure (DM) of 400 cm−3 pc.
The incidence of psychotic disorders varies between geographical areas and it has been hypothesized that neighbourhood-level factors may influence this variation. It is also plausible that the duration of untreated psychosis (DUP) is associated with neighbourhood characteristics. The aims of this study were to determine whether the incidence of first-episode psychosis (FEP) and the DUP are associated with the level of social deprivation, fragmentation, social capital and population density.
All individuals with a FEP from a geographical defined catchment area over a 5-year period were included. Age-standardized incidence rates were calculated for each neighbourhood factor.
A total of 292 cases of FEP were included in the study and 45% had a diagnosis of a schizophrenia-spectrum disorder. The age standardized incidence rate of FEP in the most deprived area was 72.4 [95% confidence interval (CI) 26.4–162.7] per 100 000 person-years compared with 21.5 (95% CI 17.6–26.0) per 100 000 person-years in the most affluent areas. This represents a 3.4-fold increase in FEP incidence in the most deprived areas. The incidence of FEP was also increased in neighbourhoods that were more socially fragmented [incidence rate ratio (IRR) = 2.40, 95% CI 1.05–5.51, p = 0.04] and there was a trend for the incidence to be increased in neighbourhoods with lower social capital (IRR = 1.43, 95% CI 0.99–2.06, p = 0.05). The median DUP was 4 months and was higher in more socially fragmented neighbourhoods.
The incidence of psychotic disorders is related to neighbourhood factors and it may be useful to consider neighbourhood factors when allocating resources for early intervention services.
Study of illness characteristics and symptoms in a young population with psychosis can assist for understanding of their needs, and can inform service planning strategies. The aims of the current study were to describe illness characteristics and symptoms of a first episode psychosis (FEP) sample aged 25 years and under, and compare with a sample aged over 25 years.
Interviews were conducted for 437 individuals aged 16–65 years presenting with suspected psychosis between 2005 and 2012 in a defined catchment area (population of 390 000) using the Structured Clinical Interview for DSM IV to determine the presence of a psychosis diagnosis. Individuals with confirmed psychosis were assessed using standardised instruments to determine illness characteristics at first presentation.
Among the 25 years, and under FEP sample, 23.9% had their first onset of symptoms (prodromal or psychotic) before 18 years of age. After controlling for confounders, the sample aged 25 years and under had a significantly shorter log transformed duration of untreated psychosis (p=0.002), more negative symptoms (p=0.045) and greater frequency of comorbid cannabis abuse diagnosis (p=0.027).
Symptom onset in a youth FEP sample frequently occurs before age 18 years. Certain illness characteristics differed across the age categories, such as greater negative symptoms and cannabis abuse in the youth sample. Overall, the findings support the provision of adequate strategies for management of negative symptom deficits and substance abuse across all ages in FEP.
To examine the use of vitamin D supplements during infancy among the participants in an international infant feeding trial.
Information about vitamin D supplementation was collected through a validated FFQ at the age of 2 weeks and monthly between the ages of 1 month and 6 months.
Infants (n 2159) with a biological family member affected by type 1 diabetes and with increased human leucocyte antigen-conferred susceptibility to type 1 diabetes from twelve European countries, the USA, Canada and Australia.
Daily use of vitamin D supplements was common during the first 6 months of life in Northern and Central Europe (>80 % of the infants), with somewhat lower rates observed in Southern Europe (>60 %). In Canada, vitamin D supplementation was more common among exclusively breast-fed than other infants (e.g. 71 % v. 44 % at 6 months of age). Less than 2 % of infants in the USA and Australia received any vitamin D supplementation. Higher gestational age, older maternal age and longer maternal education were study-wide associated with greater use of vitamin D supplements.
Most of the infants received vitamin D supplements during the first 6 months of life in the European countries, whereas in Canada only half and in the USA and Australia very few were given supplementation.
To compare the efficacy of computed tomographic angiography (CTA) to that of digital subtraction angiography (DSA) in the detection of secondary causes of intracerebral hemorrhage (ICH).
Between January 2001 and February 2007 there were 286 patients that had both CTA and DSA for intracranial hemorrhage of all types. Those with primarily subarachnoid hemorrhage or recent trauma were excluded. Fifty-five patients formed the study cohort. Three reviewers independently analyzed the CTAs in a blinded protocol and classified them based on presence or absence of a secondary etiology. Results were compared with the reference standard DSA and kappa values determined for interobserver variability.
The overall sensitivity, specificity, positive predictive value, negative predictive value and accuracy of CTA were 89%, 92%, 91%, 91% and 91%, respectively. Kappa value for interobserver agreement ranged from 0.78 to 0.89. Two of four dural arteriovenous fistulas (dAVF) were missed on CTA by all three reviewers.
CTA is nearly as effective as DSA at determining the cause of secondary intracerebral hemorrhage, but with a lower sensitivity for dAVFs. This supports the use of CTA as the first screening test in patients presenting with spontaneous ICH.
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