2,909 research outputs found
Managing the accountability-autonomy tensions in university research commercialisation
This article investigates organisational responses to emerging concerns about how accountability–autonomy tensions can be managed within the context of university research commercialisation. The findings suggest that changed expectations of university research practices, which result from the introduction of a commercialisation logic, can be managed via the homogenisation of research goals and strategies. The successful management of accountability–autonomy tensions also depends on utilising the various structures and cultural contexts that can be facilitated by decoupling and bridging strategies. Further, while adopting symbolic systems may enhance legitimacy, failure to implement material practices and provide the appropriate cultural context to manage conflicting relationships may put university commercialisation ambitions at risk
General Relativistic Magnetohydrodynamic Simulations of Magnetically Choked Accretion Flows around Black Holes
Black hole (BH) accretion flows and jets are qualitatively affected by the
presence of ordered magnetic fields. We study fully three-dimensional global
general relativistic magnetohydrodynamic (MHD) simulations of radially extended
and thick (height to cylindrical radius ratio of )
accretion flows around BHs with various dimensionless spins (, with BH
mass ) and with initially toroidally-dominated (-directed) and
poloidally-dominated ( directed) magnetic fields. Firstly, for toroidal
field models and BHs with high enough , coherent large-scale (i.e. ) dipolar poloidal magnetic flux patches emerge, thread the BH, and generate
transient relativistic jets. Secondly, for poloidal field models, poloidal
magnetic flux readily accretes through the disk from large radii and builds-up
to a natural saturation point near the BH. For sufficiently high or low
the polar magnetic field compresses the inflow into a geometrically
thin highly non-axisymmetric "magnetically choked accretion flow" (MCAF) within
which the standard linear magneto-rotational instability is suppressed. The
condition of a highly-magnetized state over most of the horizon is optimal for
the Blandford-Znajek mechanism that generates persistent relativistic jets with
% efficiency for . A magnetic Rayleigh-Taylor
and Kelvin-Helmholtz unstable magnetospheric interface forms between the
compressed inflow and bulging jet magnetosphere, which drives a new jet-disk
quasi-periodic oscillation (JD-QPO) mechanism. The high-frequency QPO has
spherical harmonic mode period of for
with coherence quality factors . [abridged]Comment: 32 pages + acks/appendix/references, 22 figures, 10 tables. MNRAS in
press. High-Res Version: http://www.slac.stanford.edu/~jmckinne/mcaf.pdf .
Fiducial Movie: http://youtu.be/V2WoJOkIin
Constraints on the shapes of galaxy dark matter haloes from weak gravitational lensing
We study the shapes of galaxy dark matter haloes by measuring the anisotropy
of the weak gravitational lensing signal around galaxies in the second
Red-sequence Cluster Survey (RCS2). We determine the average shear anisotropy
within the virial radius for three lens samples: all galaxies with
19<m_r'<21.5, and the `red' and `blue' samples, whose lensing signals are
dominated by massive low-redshift early-type and late-type galaxies,
respectively. To study the environmental dependence of the lensing signal, we
separate each lens sample into an isolated and clustered part and analyse them
separately. We also measure the azimuthal dependence of the distribution of
physically associated galaxies around the lens samples. We find that these
satellites preferentially reside near the major axis of the lenses, and
constrain the angle between the major axis of the lens and the average location
of the satellites to =43.7 deg +/- 0.3 deg for the `all' lenses,
=41.7 deg +/- 0.5 deg for the `red' lenses and =42.0 deg +/- 1.4
deg for the `blue' lenses. For the `all' sample, we find that the anisotropy of
the galaxy-mass cross-correlation function =0.23 +/- 0.12, providing
weak support for the view that the average galaxy is embedded in, and
preferentially aligned with, a triaxial dark matter halo. Assuming an
elliptical Navarro-Frenk-White (NFW) profile, we find that the ratio of the
dark matter halo ellipticity and the galaxy ellipticity
f_h=e_h/e_g=1.50+1.03-1.01, which for a mean lens ellipticity of 0.25
corresponds to a projected halo ellipticity of e_h=0.38+0.26-0.25 if the halo
and the lens are perfectly aligned. For isolated galaxies of the `all' sample,
the average shear anisotropy increases to =0.51+0.26-0.25 and
f_h=4.73+2.17-2.05, whilst for clustered galaxies the signal is consistent with
zero. (abridged)Comment: 28 pages, 23 figues, accepted for publication in A&
Gravitational Lensing
Gravitational lensing has developed into one of the most powerful tools for
the analysis of the dark universe. This review summarises the theory of
gravitational lensing, its main current applications and representative results
achieved so far. It has two parts. In the first, starting from the equation of
geodesic deviation, the equations of thin and extended gravitational lensing
are derived. In the second, gravitational lensing by stars and planets,
galaxies, galaxy clusters and large-scale structures is discussed and
summarised.Comment: Invited review article to appear in Classical and Quantum Gravity, 85
pages, 15 figure
Competing Sound Sources Reveal Spatial Effects in Cortical Processing
Neurons in the avian auditory forebrain show strong sensitivity to the spatial configuration of two competing sources, even though there is only weak spatial dependence for any single source
Theory of disk accretion onto supermassive black holes
Accretion onto supermassive black holes produces both the dramatic phenomena
associated with active galactic nuclei and the underwhelming displays seen in
the Galactic Center and most other nearby galaxies. I review selected aspects
of the current theoretical understanding of black hole accretion, emphasizing
the role of magnetohydrodynamic turbulence and gravitational instabilities in
driving the actual accretion and the importance of the efficacy of cooling in
determining the structure and observational appearance of the accretion flow.
Ongoing investigations into the dynamics of the plunging region, the origin of
variability in the accretion process, and the evolution of warped, twisted, or
eccentric disks are summarized.Comment: Mostly introductory review, to appear in "Supermassive black holes in
the distant Universe", ed. A.J. Barger, Kluwer Academic Publishers, in pres
The Interstellar Environment of our Galaxy
We review the current knowledge and understanding of the interstellar medium
of our galaxy. We first present each of the three basic constituents - ordinary
matter, cosmic rays, and magnetic fields - of the interstellar medium, laying
emphasis on their physical and chemical properties inferred from a broad range
of observations. We then position the different interstellar constituents, both
with respect to each other and with respect to stars, within the general
galactic ecosystem.Comment: 39 pages, 12 figures (including 3 figures in 2 parts
Theory and Applications of Non-Relativistic and Relativistic Turbulent Reconnection
Realistic astrophysical environments are turbulent due to the extremely high
Reynolds numbers. Therefore, the theories of reconnection intended for
describing astrophysical reconnection should not ignore the effects of
turbulence on magnetic reconnection. Turbulence is known to change the nature
of many physical processes dramatically and in this review we claim that
magnetic reconnection is not an exception. We stress that not only
astrophysical turbulence is ubiquitous, but also magnetic reconnection itself
induces turbulence. Thus turbulence must be accounted for in any realistic
astrophysical reconnection setup. We argue that due to the similarities of MHD
turbulence in relativistic and non-relativistic cases the theory of magnetic
reconnection developed for the non-relativistic case can be extended to the
relativistic case and we provide numerical simulations that support this
conjecture. We also provide quantitative comparisons of the theoretical
predictions and results of numerical experiments, including the situations when
turbulent reconnection is self-driven, i.e. the turbulence in the system is
generated by the reconnection process itself. We show how turbulent
reconnection entails the violation of magnetic flux freezing, the conclusion
that has really far reaching consequences for many realistically turbulent
astrophysical environments. In addition, we consider observational testing of
turbulent reconnection as well as numerous implications of the theory. The
former includes the Sun and solar wind reconnection, while the latter include
the process of reconnection diffusion induced by turbulent reconnection, the
acceleration of energetic particles, bursts of turbulent reconnection related
to black hole sources as well as gamma ray bursts. Finally, we explain why
turbulent reconnection cannot be explained by turbulent resistivity or derived
through the mean field approach.Comment: 66 pages, 24 figures, a chapter of the book "Magnetic Reconnection -
Concepts and Applications", editors W. Gonzalez, E. N. Parke
Recommended from our members
Using a community-based definition of poverty for targeting poor households for premium subsidies in the context of a community health insurance in Burkina Faso
Background: One of the biggest challenges in subsidizing premiums of poor households for community health insurance is the identification and selection of these households. Generally, poverty assessments in developing countries are based on monetary terms. The household is regarded as poor if its income or consumption is lower than a predefined poverty cut-off. These measures fail to recognize the multi-dimensional character of poverty, ignoring community members? perception and understanding of poverty, leaving them voiceless and powerless in the identification process. Realizing this, the steering committee of Nouna's health insurance devised a method to involve community members to better define `perceived? poverty, using this as a key element for the poor selection. The community-identified poor were then used to effectively target premium subsidies for the insurance scheme.
Methods: The study was conducted in the Nouna's Health District located in northwest Burkina Faso. Participants in each village were selected to take part in focus-group discussions (FGD) organized in 41 villages and 7 sectors of Nouna's town to discuss criteria and perceptions of poverty. The discussions were audio recorded, transcribed and analyzed in French using the software NVivo 9.
Results: From the FGD on poverty and the subjective definitions and perceptions of the community members, we found that poverty was mainly seen as scarcity of basic needs, vulnerability, deprivation of capacities, powerlessness, voicelessness, indecent living conditions, and absence of social capital and community networks for support in times of need. Criteria and poverty groups as described by community members can be used to identify poor who can then be targeted for subsidies.
Conclusion: Policies targeting the poorest require the establishment of effective selection strategies. These policies are well-conditioned by proper identification of the poor people. Community perceptions and criteria of poverty are grounded in reality, to better appreciate the issue. It is crucial to take these perceptions into account in undertaking community development actions which target the poor. For most community-based health insurance schemes with limited financial resources, using a community-based definition of poverty in the targeting of the poorest might be a less costly alternative
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