1,116 research outputs found
The complex radio and X-ray structure in the nuclear regions of the active galaxy NGC1365
We present a multiwavelength analysis of the prominent active galaxy NGC1365,
in particular looking at the radio and X-ray properties of the central regions
of the galaxy.
We analyse ROSAT observations of NGC1365, and discuss recent ASCA results. In
addition to a number of point sources in the vicinity of NGC1365, we find a
region of X-ray emission extending along the central bar of the galaxy,
combined with an emission peak near the centre of the galaxy. This X-ray
emission is centred on the optical/radio nucleus, but is spatially extended.
The X-ray spectrum can be well fitted by a thermal plasma model, with
kT=0.6-0.8keV and a low local absorbing column. The thermal spectrum is
suggestive of starburst emission rather than emission from a central
black-hole.
The ATCA radio observations show a number of hotspots, located in a ring
around a weak radio nucleus. Synchrotron emission from electrons accelerated by
supernovae and supernova remnants (SNRs) is the likely origin of these
hotspots. The radio nucleus has a steep spectrum, indicative perhaps of an AGN
or SNRs. The evidence for a jet emanating from the nucleus is at best marginal.
The extent of the radio ring is comparable to the extended central X-ray
source.Comment: 13 pages, 5 figures, to be published in MNRA
A preliminary examination of differential decomposition patterns in mass graves
This study represents a preliminary, quantitative approach to the examination of differential decomposition patterns in mass graves. Five pairs of mass graves, each containing the carcasses of 21 rabbits, were used to examine decomposition rates at four fixed positions within the burial. A pair of graves was exhumed at approximately 100 accumulated degree day (ADD) intervals. At exhumation the total body score (TBS) and internal carcass temperature of each rabbit were recorded. Although there was no significant difference between decomposition rates for core and deep-positioned carcasses (p = 0.13), all other position differences were significant (p < 0.001). Decomposition occurred fastest in shallow carcasses, followed by mid-outer carcasses; both deep and core carcasses exhibited a slower rate. Internal carcass temperature was significantly influenced by carcass location
within the mass grave; there was a mean internal temperature difference of ca. 1 oC between deep and
shallow carcasses (30 cm apart). Adipocere formation was minimal and confined, with the exception of a single individual in the mid- periphery, to the deepest level. Decomposition rate may be as affected by the compactness of a mass as by interment depth and/or peripheral substrate contact, and further investigation into the role of oxygenation and pH are required
Stock market integration for the transition economies: Time-varying conditional correlation approach
This is the accepted version of the following article: WANG, P. and MOORE, T. (2008), Stock market integration for the transition economies: Time-varying conditional correlation approach. The Manchester School, 76: 116–133. doi: 10.1111/j.1467-9957.2008.01083.x, which has
been published in final form at http://onlinelibrary.wiley.com/doi/10.1111/j.1467-
9957.2008.01083.x/abstract.In this paper, we investigate the extent to which the three emerging Central Eastern European stock markets have become integrated with the aggregate eurozone market over the sample period from 1994 to 2006 by utilizing the dynamic conditional correlation. We find a higher level of the stock market correlation during the period after the Asian and Russian crises and also during the post-entry period to the European Union. It is found that financial market integration seems to be a largely self-fuelling process, depending on existing levels of financial sector development for the Czech Republic and Hungary
Novel sampling method for assessing human-pathogen interactions in the natural environment using boot socks and citizen scientists, with application to Campylobacter seasonality
This paper introduces a novel method for sampling pathogens in natural environments. It uses fabric boot socks worn over walkers' shoes to allow the collection of composite samples over large areas. Wide-area sampling is better suited to studies focusing on human exposure to pathogens (e.g., recreational walking). This sampling method is implemented using a citizen science approach: groups of three walkers wearing boot socks undertook one of six routes, 40 times over 16 months in the North West (NW) and East Anglian (EA) regions of England. To validate this methodology, we report the successful implementation of this citizen science approach, the observation that Campylobacter bacteria were detected on 47% of boot socks, and the observation that multiple boot socks from individual walks produced consistent results. The findings indicate higher Campylobacter levels in the livestock-dominated NW than in EA (55.8% versus 38.6%). Seasonal differences in the presence of Campylobacter bacteria were found between the regions, with indications of winter peaks in both regions but a spring peak in the NW. The presence of Campylobacter bacteria on boot socks was negatively associated with ambient temperature (P = 0.011) and positively associated with precipitation (P < 0.001), results consistent with our understanding of Campylobacter survival and the probability of material adhering to boot socks. Campylobacter jejuni was the predominant species found; Campylobacter coli was largely restricted to the livestock-dominated NW. Source attribution analysis indicated that the potential source of C. jejuni was predominantly sheep in the NW and wild birds in EA but did not differ between peak and nonpeak periods of human incidence
RESPOND – A patient-centred program to prevent secondary falls in older people presenting to the emergency department with a fall: Protocol for a multi-centre randomised controlled trial
Introduction: Participation in falls prevention activities by older people following presentation to the Emergency Department (ED) with a fall is suboptimal. This randomised controlled trial (RCT) will test the RESPOND program which is designed to improve older persons’ participation in falls prevention activities through delivery of patient-centred education and behaviour change strategies. Design and setting: An RCT at two tertiary referral EDs in Melbourne and Perth, Australia. Participants: Five-hundred and twenty eight community-dwelling people aged 60-90 years presenting to the ED with a fall and discharged home will be recruited. People who: require an interpreter or hands-on assistance to walk; live in residential aged care or >50 kilometres from the trial hospital; have terminal illness, cognitive impairment, documented aggressive behaviour or history of psychosis; are receiving palliative care; or are unable to use a telephone will be excluded. Methods: Participants will be randomly allocated to the RESPOND intervention or standard care control group. RESPOND incorporates: (1) home-based risk factor assessment; (2) education, coaching, goal setting, and follow-up telephone support for management of one or more of four risk factors with evidence of effective intervention; and (3) healthcare provider communication and community linkage delivered over six months. Primary outcomes are falls and fall injuries per-person-year. Discussion: RESPOND builds on prior falls prevention learnings and aims to help individuals make guided decisions about how they will manage their falls risk. Patient-centred models have been successfully trialled in chronic and cardiovascular disease however evidence to support this approach in falls prevention is limited. Trial registration. The protocol for this study is registered with the Australian New Zealand Clinical Trials Registry (ACTRN12614000336684)
Coronary CT Angiography and 5-Year Risk of Myocardial Infarction.
BACKGROUND: Although coronary computed tomographic angiography (CTA) improves diagnostic certainty in the assessment of patients with stable chest pain, its effect on 5-year clinical outcomes is unknown. METHODS: In an open-label, multicenter, parallel-group trial, we randomly assigned 4146 patients with stable chest pain who had been referred to a cardiology clinic for evaluation to standard care plus CTA (2073 patients) or to standard care alone (2073 patients). Investigations, treatments, and clinical outcomes were assessed over 3 to 7 years of follow-up. The primary end point was death from coronary heart disease or nonfatal myocardial infarction at 5 years. RESULTS: The median duration of follow-up was 4.8 years, which yielded 20,254 patient-years of follow-up. The 5-year rate of the primary end point was lower in the CTA group than in the standard-care group (2.3% [48 patients] vs. 3.9% [81 patients]; hazard ratio, 0.59; 95% confidence interval [CI], 0.41 to 0.84; P=0.004). Although the rates of invasive coronary angiography and coronary revascularization were higher in the CTA group than in the standard-care group in the first few months of follow-up, overall rates were similar at 5 years: invasive coronary angiography was performed in 491 patients in the CTA group and in 502 patients in the standard-care group (hazard ratio, 1.00; 95% CI, 0.88 to 1.13), and coronary revascularization was performed in 279 patients in the CTA group and in 267 in the standard-care group (hazard ratio, 1.07; 95% CI, 0.91 to 1.27). However, more preventive therapies were initiated in patients in the CTA group (odds ratio, 1.40; 95% CI, 1.19 to 1.65), as were more antianginal therapies (odds ratio, 1.27; 95% CI, 1.05 to 1.54). There were no significant between-group differences in the rates of cardiovascular or noncardiovascular deaths or deaths from any cause. CONCLUSIONS: In this trial, the use of CTA in addition to standard care in patients with stable chest pain resulted in a significantly lower rate of death from coronary heart disease or nonfatal myocardial infarction at 5 years than standard care alone, without resulting in a significantly higher rate of coronary angiography or coronary revascularization. (Funded by the Scottish Government Chief Scientist Office and others; SCOT-HEART ClinicalTrials.gov number, NCT01149590 .)
The photometric evolution of dissolving star clusters I: First predictions
We calculated the broad-band photometric evolution of unresolved star
clusters, including the preferential loss of low-mass stars due to mass
segregation. The stellar mass function of a cluster evolves due to three
effects: (a) the evolution of massive stars; (b) early tidal effects reduce the
mass function independently of the stellar mass; (c) after mass segregation has
completed, tidal effects preferentially remove the lowest-mass stars from the
cluster. Results: (1) During the first ~40% of the lifetime of a cluster the
cluster simply gets fainter due to the loss of stars by tidal effects. (2)
Between ~40 and ~80% of its lifetime the cluster gets bluer due to the loss of
low-mass stars. This will result in an underestimate of the age of clusters if
standard cluster evolution models are used (0.15 -- 0.5 dex). (3) After ~80% of
the total lifetime of a cluster it will rapidly get redder. This is because
stars at the low-mass end of the main sequence, which are preferentially lost,
are bluer than the AGB stars that dominate the light at long wavelengths,
resulting in an age overestimate. (4) Clusters with mass segregation and the
preferential loss of low-mass stars evolve along almost the same tracks in
colour-colour diagrams as clusters without mass segregation. Therefore it will
be difficult to distinguish this effect from that due to the cluster age for
unresolved clusters, unless the total lifetime of the clusters can be
estimated. (5) The changes in the colour evolution of unresolved clusters due
to the preferential loss of low-mass stars will affect the determination of the
SFHs. (6) The preferential loss of low-mass stars might explain the presence of
old (~13 Gyr) clusters in NGC 4365 which are photometrically disguised as
intermediate-age clusters (2 - 5 Gyr). [Abridged]Comment: accepted for publication in A&
Extranuclear Halpha-emitting complexes in low-z (U)LIRGs: Precursors of tidal dwarf galaxies?
(Abridged)This paper characterizes the physical and kinematic properties of
external massive star-forming regions in a sample of (U)LIRGs. We use high
angular resolution ACS images from the HST B and I bands, as well as
Halpha-line emission maps obtained with IFS. We find 31 external
Halpha-emitting (young star-forming) complexes in 11 (U)LIRGs. These complexes
have in general similar sizes, luminosities, and metallicities to extragalactic
giant HII regions and TDG candidates found in less luminous mergers and compact
groups of galaxies. We assess the mass content and the likelihood of survival
as TDGs of the 22 complexes with simple structures in the HST images based on
their photometric, structural, and kinematic properties. The dynamical tracers
used (radius-sigma and luminosity-sigma diagrams) indicate that most of the
complexes might be self-gravitating entities. The resistance to forces from the
parent galaxy is studied by considering the tidal mass of the candidate and its
relative velocity with respect to the parent galaxy. After combining the
results of previous studies of TDG searches in ULIRGs a total of 9 complexes
satisfy most of the applied criteria and thus show a high-medium or high
likelihood of survival, their total mass likely being compatible with that of
dwarf galaxies. They are defined as TDG candidates. We propose that they
probably formed more often during the early phases of the interaction.
Combining all data for complexes with IFS data where a significant fraction of
the system is covered, we infer a TDG production rate of 0.3 candidates with
the highest probabilities of survival per system for the (U)LIRGs class. This
rate, though, might decrease to 0.1 after the systems in (U)LIRGs have evolved
for 10 Gyr, for long-lived TDGs, which would imply that no more than 5-10 % of
the overall dwarf population could be of tidal origin.Comment: Accepted for publication in A&A, 21 pages, 8 figures. Typo corrected
(article 1111.0468
Extreme infrared variables from UKIDSS-I. A concentration in star-forming regions
We present initial results of the first panoramic search for high-amplitude near-infrared variability in theGalactic plane.We analyse the widely separated two-epoch K-band photometry in the fifth and seventh data releases of the UKIDSS Galactic plane survey.We find 45 stars with δK > 1 mag, including two previously known OH/IR stars and a Nova. Even though the midplane is not yet included in the data set, we find the majority (66 per cent) of our sample to be within known star-forming regions (SFRs), with two large concentrations in the Serpens OB2 association (11 stars) and the Cygnus-X complex (12 stars). Sources in SFRs show spectral energy distributions that support classification as young stellar objects (YSOs). This indicates that YSOs dominate the Galactic population of high-amplitude infrared variable stars at low luminosities and therefore likely dominate the total high-amplitude population. Spectroscopic follow up of the DR5 sample shows at least four stars with clear characteristics of eruptive premain- sequence variables, two of which are deeply embedded. Our results support the recent concept of eruptive variability comprising a continuum of outburst events with different timescales and luminosities, but triggered by a similar physical mechanism involving unsteady accretion. Also, we find what appears to be one of the most variable classical Be stars. © 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society
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