2,824 research outputs found
The role of the outsider as an agent for change
This context statement explores and reflects on the role of the outsider as an agent for change. It argues that an outsider is often able to see things differently, to offer new insights, to detect patterns and to identify commonalities that are not apparent to an insider.
I tell the narrative story of my career spanning the media, cultural policy and education policy, and cultural funding. I examine key aspects of my professional practice: as managing director of Classic FM; as the author of independent government reviews into music education and cultural education in England; and as chief executive of Arts Council England, reflecting on a series of five published works that, together with this context statement, form the overall submission for my candidacy for the Doctorate in Professional Studies by Public Works.
Although my work has been in different fields and, on the surface at least, did not appear to me at first to have a unifying common thread, the critical reflection involved in creating this context statement helped me to identify that there was in fact a central theme running through the narrative of my professional practice. Far from it being a series of disjointed events, I argue that the development of my professional practice has, in fact, been linear in its form, allowing me to reflect on the learning from each of the experiences as new challenges were encountered.
With the benefit of reflection, I come to recognise the tacit knowledge and understanding that I have built up over thirty years of professional practice, in the process, identifying a framework for delivering change, built upon a set of common behaviours and values. I set out to illustrate how these behaviours and values have been present in my own professional practice and how they could be replicated by other outsiders who find themselves in roles where they are agents for change
Long range order in the classical kagome antiferromagnet: effective Hamiltonian approach
Following Huse and Rutenberg [Phys. Rev. B 45, 7536 (1992)], I argue the
classical Heisenberg antiferromagnet on the kagom\'e lattice has long-range
spin order of the type (modulo gradual orientation
fluctuations of the spins' plane). I start from the effective quartic
Hamiltonian for the soft (out of plane) spin fluctuation modes, and treat as a
perturbation those terms which depend on the discrete coplanar state. Soft mode
correlations, which become the coefficients of a discrete effective
Hamiltonian, are estimated analytically.Comment: 4pp, no figures. Converted to PRB format, extensive revisions/some
reorderings to improve clarity; some cut
Probing the wind-wind collision in Gamma Velorum with high-resolution Chandra X-ray spectroscopy: evidence for sudden radiative braking and non-equilibrium ionization
We present a new analysis of an archived Chandra HETGS X-ray spectrum of the
WR+O colliding wind binary Gamma Velorum. The spectrum is dominated by emission
lines from astrophysically abundant elements: Ne, Mg, Si, S and Fe. From a
combination of broad-band spectral analysis and an analysis of line flux ratios
we infer a wide range of temperatures in the X-ray emitting plasma (~4-40 MK).
As in the previously published analysis, we find the X-ray emission lines are
essentially unshifted, with a mean FWHM of 1240 +/- 30 km/s. Calculations of
line profiles based on hydrodynamical simulations of the wind-wind collision
predict lines that are blueshifted by a few hundred km/s. The lack of any
observed shift in the lines may be evidence of a large shock-cone opening
half-angle (> 85 degrees), and we suggest this may be evidence of sudden
radiative braking. From the R and G ratios measured from He-like
forbidden-intercombination-resonance triplets we find evidence that the Mg XI
emission originates from hotter gas closer to the O star than the Si XIII
emission, which suggests that non-equilibrium ionization may be present.Comment: 22 pages, 14 figures. Accepted for publication in MNRA
Properties of Resonating-Valence-Bond Spin Liquids and Critical Dimer Models
We use Monte Carlo simulations to study properties of Anderson's
resonating-valence-bond (RVB) spin-liquid state on the square lattice (i.e.,
the equal superposition of all pairing of spins into nearest-neighbor singlet
pairs) and compare with the classical dimer model (CDM). The latter system also
corresponds to the ground state of the Rokhsar-Kivelson quantum dimer model at
its critical point. We find that although spin-spin correlations decay
exponentially in the RVB, four-spin valence-bond-solid (VBS) correlations are
critical, qualitatively like the well-known dimer-dimer correlations of the
CDM, but decaying more slowly (as with , compared with
for the CDM). We also compute the distribution of monomer (defect) pair
separations, which decay by a larger exponent in the RVB than in the CDM. We
further study both models in their different winding number sectors and
evaluate the relative weights of different sectors. Like the CDM, all the
observed RVB behaviors can be understood in the framework of a mapping to a
"height" model characterized by a gradient-squared stiffness constant . Four
independent measurements consistently show a value , with the same kinds of numerical evaluations of give
results in agreement with the rigorously known value . The
background of a nonzero winding number gradient introduces spatial
anisotropies and an increase in the effective K, both of which can be
understood as a consequence of anharmonic terms in the height-model free
energy, which are of relevance to the recently proposed scenario of "Cantor
deconfinement" in extended quantum dimer models. We also study ensembles in
which fourth-neighbor (bipartite) bonds are allowed, at a density controlled by
a tunable fugacity, resulting (as expected) in a smooth reduction of K.Comment: 26 pages, 21 figures. v3: final versio
First-principles prediction of a decagonal quasicrystal containing boron
We interpret experimentally known B-Mg-Ru crystals as quasicrystal
approximants. These approximant structures imply a deterministic decoration of
tiles by atoms that can be extended quasiperiodically. Experimentally observed
structural disorder corresponds to phason (tile flip) fluctuations.
First-principles total energy calculations reveal that many distinct tilings
lie close to stability at low temperatures. Transfer matrix calculations based
on these energies suggest a phase transition from a crystalline state at low
temperatures to a high temperature state characterized by tile fluctuations. We
predict BMgRu forms a decagonal quasicrystal that is
metastable at low temperatures and may be thermodynamically stable at high
temperatures.Comment: 4 pages, 3 figures, submitted to Phys. Rev. Let
China Maritime Report No. 26: Beyond the First Battle: Overcoming a Protracted Blockade of Taiwan
If there is a war over Taiwan, an extended Chinese blockade is likely to determine the outcome. While a blockade might include intercepting ships at sea, the primary focus would be on sealing airfields and ports, particularly on the west coast of Taiwan. China could sustain that type of blockade indefinitely. Penetrating a prolonged blockade and keeping Taiwan alive would require a serious U.S. investment in systems and operational concepts that we currently do not have. Unless we make that investment, we may win the first battle, defeating an attempted landing. But we cannot win the war.https://digital-commons.usnwc.edu/cmsi-maritime-reports/1025/thumbnail.jp
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