176 research outputs found
Organisational studies in an era of educational reform
One social science base for educational administration proposed in the Baron and Taylor collection was organisation theory. In the event this expectation turned out to be over-optimistic. Organisation theory was much too contested and insufficiently pragmatic for the British taste. Major developments in this field occurred mainly in the USA. Nevertheless, the more general approach of organisational studies continues to enhance our understanding of schools where a ‘both-and’ perspective is adopted towards organisational dualities, particularly in the face of what we have provocatively termed ‘transformania’. The article explores the unintended consequences of relentless transformania through three examples of duality: organisation–institution, bureaucracy–professionality, and the culture of teaching–the culture of managerialism. Finally, it is suggested that a revival of an interest in the somewhat dormant theory of ambiguity would be timely
Does External Pressure Explain Recent Results for Molecular Clouds?
The recent paper by Heyer et al (2009) indicates that observations of size,
linewidth and column density of interstellar clouds do not agree with simple
virial equilibrium (VE) as a balance between gravitational and kinetic energies
in the sense that the clouds either have too much kinetic energy or too little
mass to be bound. This may be explained by violation of VE as suggested by
Dobbs et al 2011, by observational underestimation of the masses as suggested
by Heyer et al 2009, or by an external pressure acting as an additional
confining force as suggested earlier by Heyer et al 2004. The data of Heyer et
al. 2009 cannot be explained with a single value for the external pressure, but
if different clouds in the sample have different external pressures in the
range of Pe/k = E4 to E7 cm-3 K, then most of the clouds could be in pressure
virial equilibrium (PVE). In this paper we discuss two consequences of the
external pressure. First, we show that the observational data are consistent
with the hypothesis (Chie\'ze 1987) that most clouds are at a critical mass for
dynamical stability determined solely by the pressure. Above this mass a cloud
is unstable to gravitational collapse or fragmentation. Second, we show that
the external pressure modifies the well-known size-linewidth relationship first
proposed by Larson (1981) so that the proportionality is no longer constant but
depends on the external pressure.Comment: Accepted for publication in MNRA
New Experimental Limits on Macroscopic Forces Below 100 Microns
Results of an experimental search for new macroscopic forces with Yukawa
range between 5 and 500 microns are presented. The experiment uses 1 kHz
mechanical oscillators as test masses with a stiff conducting shield between
them to suppress backgrounds. No signal is observed above the instrumental
thermal noise after 22 hours of integration time. These results provide the
strongest limits to date between 10 and 100 microns, improve on previous limits
by as much as three orders of magnitude, and rule out half of the remaining
parameter space for predictions of string-inspired models with low-energy
supersymmetry breaking. New forces of four times gravitational strength or
greater are excluded at the 95% confidence level for interaction ranges between
200 and 500 microns.Comment: 25 Pages, 7 Figures: Minor Correction
On the Population of Wind-Accreting Neutron Stars in the Galaxy
We explore the possibility that neutron stars accreting from the winds of
main-sequence stellar companions account for a significant fraction of
low-luminosity, hard X-ray sources (L_X <~ 10^35 ergs/s; 1-10 keV) in the
Galaxy. This work was motivated by recent Chandra observations of the Galactic
center by Wang et al. (2002). Our calculations indicate that many of the
discrete X-ray sources detected in this survey may be wind-accreting neutron
stars, and that many more may be discovered with deeper X-ray observations. We
propose that an infrared observing campaign be undertaken to search for the
stellar counterparts of these X-ray sources.Comment: submitted to ApJ Letter
Sensation seeking and its relationship with psychopathic traits, impulsivity and aggression: a validation of the Dutch Brief Sensation Seeking Scale (BSSS)
Sensation seeking is a personality trait that manifests as a preference for change, variety and novelty. Sensation seeking has been positively associated with different externalising behaviours. However, its associations with psychopathic traits, impulsivity and aggression are unclear. These associations were examined via the psychometric properties of the Dutch version of the Brief Sensation Seeking Scale (BSSS) using individuals from the general population and forensic patients. The results show that the BSSS has good psychometric properties, including test-retest reliability and a four-factor structure. Additionally, the results support associations between sensation seeking and psychopathic traits, impulsivity and total scores of aggression but revealed no specific associations with different types of aggression (e.g. proactive and reactive). The Dutch BSSS is a valuable tool for assessing sensation seeking in both the general population and forensic patients. Future research should further examine its utility and explore the role of sensation seeking in antisocial conduct
Book reviews
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43582/1/11159_2005_Article_BF01450280.pd
Magnetic flaring in the pre-main sequence Sun and implications for the early solar system
To address the role of energetic processes in the solar nebula, we provide a
detailed characterization of magnetic flaring in stellar analogs of the
pre-main sequence Sun based on 23 hours observations of 43 analogs of the young
Sun in the Orion Nebula Cluster obtained with the Chandra X-ray Observatory. We
find the X-ray luminosities are strongly elevated over main sequence levels
with average = 30.3 erg/s and = -3.9 (0.5-8 keV), and
dozens of flares are present. Analogs of the <= 1 My old pre-main sequence Sun
exhibit X-ray flares 10^{1.5} times more powerful and 10^{2.5} times more
frequent than the most powerful flares seen on the contemporary Sun.
Extrapolating the solar relationship between X-ray luminosity and proton
fluence, we infer that the young Sun exhibited a 10^5-fold enhancement in
energetic protons compared to contemporary levels. Unless the flare geometries
are unfavorable, this inferred proton flux on the disk is sufficient to produce
the observed meteoritic abundances of several important short-lived radioactive
isotopes. Our study thus strengthens the astronomical foundation for local
proton spallation models of isotopic anomalies in carbonaceous chondritic
meteorites. The radiation, particles and shocks produced by the magnetic
reconnection flares seen with Chandra may also have flash melted meteoritic
chondrules and produced excess 21-Ne seen in meteoritic grains.Comment: 36 pages, 3 figures. Accepted for publication in the Astrophysical
Journa
Bondi-Hoyle-Lyttleton Accretion Model for Low-luminosity X-ray Sources in Globular Clusters
We present a new model for low-luminosity X-ray sources in globular clusters,
with L_x < 10^34 erg/s. The model we propose is that of a single neutron star
accreting from cluster gas that has accumulated as a natural product of stellar
evolution. An analytic luminosity function is derived under the assumption that
the speed distribution of neutron stars in the central region of a cluster is
described by a Maxwellian, and that the density and temperature of the gas are
uniform. Predictions of the model and implications for the gas content of
globular clusters are discussed.Comment: Accepted by ApJ. Minor changes and expanded conclusions sectio
- …