617 research outputs found
A Binary Millisecond Pulsar in Globular Cluster NGC6544
We report the detection of a new 3.06 ms binary pulsar in the globular
cluster NGC6544 using a Fourier-domain ``acceleration'' search. With an implied
companion mass of ~0.01 solar masses and an orbital period of only P_b~1.7
hours, it displays very similar orbital properties to many pulsars which are
eclipsed by their companion winds. The orbital period is the second shortest of
known binary pulsars after 47 Tuc R. The measured flux density of 1.3 +/- 0.4
mJy at 1332 MHz indicates that the pulsar is almost certainly the known
steep-spectrum point source near the core of NGC6544.Comment: Accepted by ApJ Letters on 11 October 2000, 5 page
The Timing of Nine Globular Cluster Pulsars
We have used the Robert C. Byrd Green Bank Telescope to time nine previously
known pulsars without published timing solutions in the globular clusters M62,
NGC 6544, and NGC 6624. We have full timing solutions that measure the spin,
astrometric, and (where applicable) binary parameters for six of these pulsars.
The remaining three pulsars (reported here for the first time) were not
detected enough to establish solutions. We also report our timing solutions for
five pulsars with previously published solutions, and find good agreement with
past authors, except for PSR J1701-3006B in M62. Gas in this system is probably
responsible for the discrepancy in orbital parameters, and we have been able to
measure a change in the orbital period over the course of our observations.
Among the pulsars with new solutions we find several binary pulsars with very
low mass companions (members of the so-called "black widow" class) and we are
able to place constraints on the mass-to-light ratio in two clusters. We
confirm that one of the pulsars in NGC 6624 is indeed a member of the rare
class of non-recycled pulsars found in globular clusters. We also have measured
the orbital precession and Shapiro delay for a relativistic binary in NGC 6544.
If we assume that the orbital precession can be described entirely by general
relativity, which is likely, we are able to measure the total system mass
(2.57190(73) M_sun) and companion mass (1.2064(20) M_sun), from which we derive
the orbital inclination [sin(i) = 0.9956(14)] and the pulsar mass (1.3655(21)
M_sun), the most precise such measurement ever obtained for a millisecond
pulsar. The companion is the most massive known around a fully recycled pulsar.Comment: Published in ApJ; 33 pages, 5 figures, 7 table
Observations of the Cosmic Microwave Background and Implications for Cosmology and Large Scale Structure
Observations of the Cosmic Microwave Background (CMB) are discussed, with
particular emphasis on current ground-based experiments and on future
satellite, balloon and interferometer experiments. Observational techniques and
the effects of contaminating foregrounds are highlighted. Recent CMB data is
used with large scale structure (LSS) data to constrain cosmological parameters
and the complementary nature of CMB, LSS and supernova distance data is
emphasized.Comment: 23 pages, 10 figures. Phil. Trans. R. Soc. Lond. A., 1998, in pres
An observational test for correlations between cosmic rays and magnetic fields
We derive the magnitude of fluctuations in total synchrotron intensity in the
Milky Way and M33, from both observations and theory under various assumption
about the relation between cosmic rays and interstellar magnetic fields. Given
the relative magnitude of the fluctuations in the Galactic magnetic field (the
ratio of the rms fluctuations to the mean magnetic field strength) suggested by
Faraday rotation and synchrotron polarization, the observations are
inconsistent with local energy equipartition between cosmic rays and magnetic
fields. Our analysis of relative synchrotron intensity fluctuations indicates
that the distribution of cosmic rays is nearly uniform at the scales of the
order of and exceeding 100\p, in contrast to strong fluctuations in the
interstellar magnetic field at those scales. A conservative upper limit on the
ratio of the the fluctuation magnitude in the cosmic ray number density to its
mean value is 0.2--0.4 at scales of order 100\,pc. Our results are consistent
with a mild anticorrelation between cosmic-ray and magnetic energy densities at
these scales, in both the Milky Way and M33. Energy equipartition between
cosmic rays and magnetic fields may still hold, but at scales exceeding 1\,kpc.
Therefore, we suggest that equipartition estimates be applied to the observed
synchrotron intensity smoothed to a linear scale of kiloparsec order (in spiral
galaxies) to obtain the cosmic ray distribution and a large-scale magnetic
field. Then the resulting cosmic ray distribution can be used to derive the
fluctuating magnetic field strength from the data at the original resolution.
The resulting random magnetic field is likely to be significantly stronger than
existing estimates.Comment: submitted to MNRA
Interrelationships between negative mood and clinical constructs: a motivational systems approach
A series of three experiments was designed to test predictions from a motivational systems approach to understanding the role of clinical constructs in anxiety-based problems. Negative mood, inflated responsibility, and intolerance of uncertainty (IU) were separately manipulated within analog samples to examine their effect on the other two factors. In the first experiment (n = 59) the negative mood group scored significantly higher in terms of inflated responsibility than the positive mood group. In the second experiment (n = 63) the high responsibility group scored significantly higher in terms of both negative mood and IU than the low responsibility group. In the third experiment (n = 61) the high IU group scored significantly higher in terms of negative mood than the low IU group. Tests of indirect effects revealed an indirect effect of IU on inflated responsibility through negative mood and an indirect effect of negative mood on IU through inflated responsibility, suggesting all three constructs are causally interrelated. The findings are consistent with contemporary transdiagnostic views of clinical constructs, and support a view of anxiety that is underpinned by a coordinated and interdependent motivational system evolved to manage threat
Having a lot of a good thing: multiple important group memberships as a source of self-esteem.
Copyright: © 2015 Jetten et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are creditedMembership in important social groups can promote a positive identity. We propose and test an identity resource model in which personal self-esteem is boosted by membership in additional important social groups. Belonging to multiple important group memberships predicts personal self-esteem in children (Study 1a), older adults (Study 1b), and former residents of a homeless shelter (Study 1c). Study 2 shows that the effects of multiple important group memberships on personal self-esteem are not reducible to number of interpersonal ties. Studies 3a and 3b provide longitudinal evidence that multiple important group memberships predict personal self-esteem over time. Studies 4 and 5 show that collective self-esteem mediates this effect, suggesting that membership in multiple important groups boosts personal self-esteem because people take pride in, and derive meaning from, important group memberships. Discussion focuses on when and why important group memberships act as a social resource that fuels personal self-esteem.This study was supported by 1. Australian Research Council Future Fellowship (FT110100238) awarded to Jolanda Jetten (see http://www.arc.gov.au) 2. Australian Research Council Linkage Grant (LP110200437) to Jolanda Jetten and Genevieve Dingle (see http://www.arc.gov.au) 3. support from the Canadian Institute for Advanced Research Social Interactions, Identity and Well-Being Program to Nyla Branscombe, S. Alexander Haslam, and Catherine Haslam (see http://www.cifar.ca)
Maternal control of child-feeding during breast and formula feeding in the first 6 months post-partum
Towards a free-free template for CMB foregrounds
A full-sky template map of the Galactic free-free foreground emission
component is increasingly important for high sensitivity CMB experiments. We
use the recently published \ha data of both the northern and southern skies as
the basis for such a template.
The first step is to correct the \ha maps for dust absorption using the 100
m dust maps of Schlegel, Finkbeiner & Davis (1998). We show that for a
range of longitudes, the Galactic latitude distribution of absorption suggests
that it is 33 per cent of the full extragalactic absorption. A reliable
absorption-corrected \ha map can be produced for per cent of the sky;
the area for which a template cannot be recovered is the Galactic plane area
, and some isolated
dense dust clouds at intermediate latitudes.
The second step is to convert the dust-corrected \ha data into a predicted
radio surface brightness. The free-free emission formula is revised to give an
accurate expression (1 per cent) for the radio emission covering the frequency
range 100 MHz to 100 GHz and the electron temperature range 3000 to 20000 K.
The main uncertainty when applying this expression is the variation of electron
temperature across the sky. The emission formula is verified in several
extended H{\sc ii} regions using data in the range 408 to 2326 MHz.
A full-sky free-free template map is presented at 30 GHz; the scaling to
other frequencies is given. The Haslam et al. all-sky 408 MHz map of the sky
can be corrected for this free-free component, which amounts to a
per cent correction at intermediate and high latitudes....Comment: 18 pages, 11 figures, accepted for publication in M.N.R.A.S.
High-resolution versions of figs 2,7 (in colour), 9 and 11 can be obtained
from ftp://ftp.jb.man.ac.uk/pub/cdickins/ff_paper/FINAL_FIGURES
Appointing Women to Boards: Is There a Cultural Bias?
Companies that are serious about corporate governance and business ethics are turning their attention to gender diversity at the most senior levels of business (Institute of Business Ethics, Business Ethics Briefing 21:1, 2011). Board gender diversity has been the subject of several studies carried out by international organizations such as Catalyst (Increasing gender diversity on boards: Current index of formal approaches, 2012), the World Economic Forum (Hausmann et al., The global gender gap report, 2010), and the European Board Diversity Analysis (Is it getting easier to find women on European boards? 2010). They all lead to reports confirming the overall relatively low proportion of women on boards and the slow pace at which more women are being appointed. Furthermore, the proportion of women on corporate boards varies much across countries. Based on institutional theory, this study hypothesizes and tests whether this variation can be attributed to differences in cultural settings across countries. Our analysis of the representation of women on boards for 32 countries during 2010 reveals that two cultural characteristics are indeed associated with the observed differences. We use the cultural dimensions proposed by Hofstede (Culture’s consequences: International differences in work-related values, 1980) to measure this construct. Results show that countries which have the greatest tolerance for inequalities in the distribution of power and those that tend to value the role of men generally exhibit lower representations of women on boards
Development of a Series of Kynurenine 3-Monooxygenase Inhibitors Leading to a Clinical Candidate for the Treatment of Acute Pancreatitis
Recently, we reported a novel role for KMO in the pathogenesis of acute pancreatitis (AP). A number of inhibitors of kynurenine 3-monooxygenase (KMO) have previously been described as potential treatments for neurodegenerative conditions and particularly for Huntington's disease. However, the inhibitors reported to date have insufficient aqueous solubility relative to their cellular potency to be compatible with the intravenous (iv) dosing route required in AP. We have identified and optimized a novel series of high affinity KMO inhibitors with favorable physicochemical properties. The leading example is exquisitely selective, has low clearance in two species, prevents lung and kidney damage in a rat model of acute pancreatitis, and is progressing into preclinical development.</p
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