9,963 research outputs found
Development of a novel metastable composite material
The development of a new family of mouldable metastable composite materials has been demonstrated. Their special quality is derived from the ability to maintain the matrix as a supercooled liquid or gel whose solidification can be triggered mechanically, as desired, by a user. This article describes some aspects of the development work. In particular, the following are explained: the choice of matrix material; the use of additives to enhance the properties of the matrix; and the selection of reinforcement fibre. As part of the work, some mechanical testing was performed on several variations of a matrix-fibre pair and, to demonstrate the potential of such materials, some comparisons were made with a possible competitor material, a glass-reinforced urethane. It was shown that the metastable material could be formulated to provide mechanical properties that would make it suitable for applications such as orthopaedic casting, splinting and body armour, and in items of sports equipment, these being areas where its mouldability could be particularly desirable
Morell Mackenzieâs contribution to the description of spasmodic dysphonia
Objectives: Since the middle of the 20th century most discussions of Spasmodic Dysphonia reference a paper by Ludwig Traube published in1871 as the first historical citation, crediting him with priority for this clinical syndrome. However, our recent research has determined that the original observation by Traube was published in 1864 and does not in fact describe what is currently recognized as SD. It appears that many clinics throughout Europe and North America were investigating and publishing observations on a range of voice disorders..
Methods: The wider context of work on laryngeal disorders in the 1860s-1870s is considered. One of Traubeâs contemporaries, Morell Mackenzie made significant contributions to the understanding of laryngeal movement disorder and its consequences for the voice. These will be examined to gain a clearer focus on the characterization of this disorder.
Results: The clinical descriptions published by Morrell Mackenzie in the 1860s provide details which conform quite closely to our current day understanding of SD.
Conclusions: The citation of Traubeâs âhystericalâ patient links to mid-20th century views of the functional nature of SD and the utility of psychiatric treatment. The description presented by Mackenzie is consistent with current views of SD as a movement disorder
Problems With Complex Actions
We consider Euclidean functional integrals involving actions which are not
exclusively real. This situation arises, for example, when there are -odd
terms in the the Minkowski action. Writing the action in terms of only real
fields (which is always possible), such terms appear as explicitly imaginary
terms in the Euclidean action. The usual quanization procedure which involves
finding the critical points of the action and then quantizing the spectrum of
fluctuations about these critical points fails. In the case of complex actions,
there do not exist, in general, any critical points of the action on the space
of real fields, the critical points are in general complex. The proper
definition of the function integral then requires the analytic continuation of
the functional integration into the space of complex fields so as to pass
through the complex critical points according to the method of steepest
descent. We show a simple example where this procedure can be carried out
explicitly. The procedure of finding the critical points of the real part of
the action and quantizing the corresponding fluctuations, treating the
(exponential of the) complex part of the action as a bounded integrable
function is shown to fail in our explicit example, at least perturbatively.Comment: 6+epsilon pages, no figures, presented at Theory CANADA
Equivariant cohomology over Lie groupoids and Lie-Rinehart algebras
Using the language and terminology of relative homological algebra, in
particular that of derived functors, we introduce equivariant cohomology over a
general Lie-Rinehart algebra and equivariant de Rham cohomology over a locally
trivial Lie groupoid in terms of suitably defined monads (also known as
triples) and the associated standard constructions. This extends a
characterization of equivariant de Rham cohomology in terms of derived functors
developed earlier for the special case where the Lie groupoid is an ordinary
Lie group, viewed as a Lie groupoid with a single object; in that theory over a
Lie group, the ordinary Bott-Dupont-Shulman-Stasheff complex arises as an a
posteriori object. We prove that, given a locally trivial Lie groupoid G and a
smooth G-manifold f over the space B of objects of G, the resulting
G-equivariant de Rham theory of f boils down to the ordinary equivariant de
Rham theory of a vertex manifold relative to the corresponding vertex group,
for any vertex in the space B of objects of G; this implies that the
equivariant de Rham cohomology introduced here coincides with the stack de Rham
cohomology of the associated transformation groupoid whence this stack de Rham
cohomology can be characterized as a relative derived functor. We introduce a
notion of cone on a Lie-Rinehart algebra and in particular that of cone on a
Lie algebroid. This cone is an indispensable tool for the description of the
requisite monads.Comment: 47 page
Orthopedic management of the extremities in patients with Morquio A syndrome.
BackgroundMusculoskeletal involvement in Morquio A syndrome (mucopolysaccharidosis IVA; MPS IVA) contributes significantly to morbidity and mortality. While the spinal manifestations of the disorder have received considerable attention in the literature, there have been few reported studies to date to guide the management of the orthopedic problems associated with the lower and upper extremities.PurposeThe objective was to develop recommendations for the management of the extremities in patients with Morquio A syndrome.MethodsA group of specialists in orthopedics, pediatrics and genetics with experience in the management of Morquio A patients convened to review and discuss current clinical practices and to develop preliminary recommendations. Evidence from the literature was retrieved. Recommendations were further refined until consensus was reached.Results and conclusionsThis present article provides a detailed review and discussion of the lower and upper extremity deformities in Morquio A syndrome and presents recommendations for the assessment and treatment of these complications. Key issues, including the importance of early diagnosis and the implications of medical therapy, are also addressed. The recommendations herein represent an attempt to develop a uniform and practical approach to managing patients with Morquio A syndrome and improving their outcomes
f_K/f_pi in Full QCD with Domain Wall Valence Quarks
We compute the ratio of pseudoscalar decay constants f_K/f_pi using
domain-wall valence quarks and rooted improved Kogut-Susskind sea quarks. By
employing continuum chiral perturbation theory, we extract the Gasser-Leutwyler
low-energy constant L_5, and extrapolate f_K/f_pi to the physical point. We
find: f_K/f_pi = 1.218 (+- 0.002) (+0.011 -0.024) where the first error is
statistical and the second error is an estimate of the systematic due to chiral
extrapolation and fitting procedures. This value agrees within the
uncertainties with the determination by the MILC collaboration, calculated
using Kogut-Susskind valence quarks, indicating that systematic errors arising
from the choice of lattice valence quark are small.Comment: 14 pages, 9 figure
Probing the AGN Unification Model at redshift z 3 with MUSE observations of giant Ly nebulae
A prediction of the classic active galactic nuclei (AGN) unification model is
the presence of ionisation cones with different orientations depending on the
AGN type. Confirmations of this model exist for present times, but it is less
clear in the early Universe. Here, we use the morphology of giant Ly
nebulae around AGNs at redshift z3 to probe AGN emission and therefore
the validity of the AGN unification model at this redshift. We compare the
spatial morphology of 19 nebulae previously found around type I AGNs with a new
sample of 4 Ly nebulae detected around type II AGNs. Using two
independent techniques, we find that nebulae around type II AGNs are more
asymmetric than around type I, at least at radial distances ~physical kpc
(pkpc) from the ionizing source. We conclude that the type I and type II AGNs
in our sample show evidence of different surrounding ionising geometries. This
suggests that the classical AGN unification model is also valid for
high-redshift sources. Finally, we discuss how the lack of asymmetry in the
inner parts (r30 pkpc) and the associated high values of the HeII to
Ly ratios in these regions could indicate additional sources of (hard)
ionizing radiation originating within or in proximity of the AGN host galaxies.
This work demonstrates that the morphologies of giant Ly nebulae can be
used to understand and study the geometry of high redshift AGNs on
circum-nuclear scales and it lays the foundation for future studies using much
larger statistical samples.Comment: 15 pages, 13 figures, accepted for publication in MNRA
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