879 research outputs found
Public perception of cross-infection control in dentistry
The document attached has been archived with permission from the Australian Dental Association. An external link to the publisherâs copy is included.Since the advent of HIV/AIDS at the beginning of the 1980s, concern has generated considerable impetus for change in cross-infection control procedures in dentistry. This process has been hastened partly by media coverage which, in tending to favour sensation over rational discourse, has played a not inconsiderable role in shaping public uderstanding and expectations. This study aimed to investigate public perceptions of cross-infection control in dentistry in Australia using a postal follow-up to the 1995 National Dental Telephone rate was 85.2 per cent. Concerns about the procedures used by their dentist to sterilize instruments were reported by 13.3 per cent of respondents overall, and this was greater among non-health-card-holders, individuals who mainly spoke a language other than English in the home, and those who reported a non-routine dental visiting pattern. Avoidance or delaying of dental visits due to the perceived cross-infection risk was reported by an overall 3.6 per cent of people, and this was higher among females and those who expressed concern about cross-infection control. The profession has a responsibility to ensure that information on the measures which have been taken to reduce the risk of cross-infection in dentisry is disseminated as widely and as clearly as possible so that undue public concern and avoidance of dental care are minimized.W. Murray Thomson, Judith F. Stewart, Knute D. Carter and A. John Spence
Charged Dilatonic AdS Black Branes in Arbitrary Dimensions
We study electromagnetically charged dilatonic black brane solutions in
arbitrary dimensions with flat transverse spaces, that are asymptotically AdS.
This class of solutions includes spacetimes which possess a bulk region where
the metric is approximately invariant under Lifshitz scalings. Given fixed
asymptotic boundary conditions, we analyze how the behavior of the bulk up to
the horizon varies with the charges and derive the extremality conditions for
these spacetimes.Comment: References update
Populating the swampland: the case of U(1)^496 and E_8 x U(1)^248
For d=10 N=1 SUGRA coupled to d=10 N=1 SYM, anomaly cancellation places
severe constraints on the allowed gauge groups. Besides the ones known to
appear in string theory, only U(1)^496 and E_8 x U(1)^248 are allowed. There
are no known theories of quantum gravity that reduce in some limit to these two
last supergravity theories, and in this note I present some evidence that those
quantum theories might not exist. The first observation is that, upon
compactification, requring that the quantum theory possesses a moduli space
with finite volume typically implies the existence of singularities where the
4d gauge group is enhanced, but for these two theories that gauge enhancement
is problematic from the 10d point of view. I also point out that while these
four supergravity theories present repulson-type singularities, the known
mechanism that repairs those singularities for the first two - the non-Abelian
enhancon - is not available for the last two theories. In short, these two
supergravity theories might be too Abelian for their own good.Comment: 12 page
Technical challenges to surgical clipping of aneurysmal regrowth with coil herniation following endovascular treatment â a case report
In recent years, technical developments have made endovascular procedures attractive therapeutic options and enabled the endovascular surgeon to redefine the management of cerebral aneurysms. However, as the number of aneurysms undergoing endovascular therapy has grown, so has the number of patients with incompletely treated aneurysms who are presenting for further management. In cases of failure of endovascular treatment caused by either incomplete occlusion or regrowth of the aneurysm, a complementary treatment is often necessary. Surgical treatment of these patients is challenging. We present a case of a ruptured posterior cerebral artery aneurysm treated initially with endovascular coiling that left behind significant residual aneurysmal sac. Regrowth of the aneurysm documented on follow-up was treated surgically. At surgery, the coil was found to have herniated through the aneurysmal sac into the subarachnoid space, and the aneurysm was successfully clipped without removing the coils. We review the regrowth of aneurysms following endovascular therapy and potential problems and challenges of surgically managing these lesions
Land of Addicts? An Empirical Investigation of Habit-Based Asset Pricing Models
A popular explanation of aggregate stock market behavior suggests that assets are priced as if there were a representative investor whose utility is a power function of the difference between aggregate consumption and a âhabitâ level, where the habit is some function of lagged and (possibly) contemporaneous consumption. But theory does not provide precise guidelines about the parametric functional relationship between the habit and aggregate consumption. This makes for- mal estimation and testing challenging; at the same time, it raises an empirical question about the functional form of the habit that best explains asset pricing data. This paper studies the ability of a general class of habit-based asset pricing models to match the conditional moment restrictions implied by asset pricing theory. Our approach is to treat the functional form of the habit as unknown, and to estimate it along with the rest of the modelâs finite dimensional parameters. This semiparametric approach allows us to empirically evaluate a number of interesting hypotheses about the specification of habit-based asset pricing models. Using stationary quarterly data on consumption growth, assets returns and instruments, our empirical results indicate that the estimated habit function is nonlinear, the habit formation is internal, and the estimated time-preference parameter and the power utility parameter are sensible. In addition, our estimated habit function generates a positive stochastic discount factor (SDF) proxy and performs well in explaining cross-sectional stock return data. We find that an internal habit SDF proxy can explain a cross-section of size and book-market sorted portfolio equity returns better than (i) the Fama and French (1993) three-factor model, (ii) the Lettau and Ludvigson (2001b) scaled consumption CAPM model, (iii) an external habit SDF proxy, (iv) the classic CAPM, and (v) the classic consumption CAPM
black hole at N=2 supergravity
In this paper, we consider the charged non-extremal black hole at five
dimensional N = 2 supergravity. We study thermodynamics of AdS_{5} black hole
with three equal charges (q_{1} = q_{2} = q_{3} = q). We obtain Schrodinger
like equation and discuss the effective potential. Then, we consider the case
of the perturbed dilaton field background and find presence of odd coefficients
of the wave function. Also we find that the higher derivative corrections have
no effect on the first and second even coefficients of the wave function.Comment: 17 pages, 4 figures. Published versio
A holographic model for the fractional quantum Hall effect
Experimental data for fractional quantum Hall systems can to a large extent
be explained by assuming the existence of a modular symmetry group commuting
with the renormalization group flow and hence mapping different phases of
two-dimensional electron gases into each other. Based on this insight, we
construct a phenomenological holographic model which captures many features of
the fractional quantum Hall effect. Using an SL(2,Z)-invariant
Einstein-Maxwell-axio-dilaton theory capturing the important modular
transformation properties of quantum Hall physics, we find dyonic diatonic
black hole solutions which are gapped and have a Hall conductivity equal to the
filling fraction, as expected for quantum Hall states. We also provide several
technical results on the general behavior of the gauge field fluctuations
around these dyonic dilatonic black hole solutions: We specify a sufficient
criterion for IR normalizability of the fluctuations, demonstrate the
preservation of the gap under the SL(2,Z) action, and prove that the
singularity of the fluctuation problem in the presence of a magnetic field is
an accessory singularity. We finish with a preliminary investigation of the
possible IR scaling solutions of our model and some speculations on how they
could be important for the observed universality of quantum Hall transitions.Comment: 86 pages, 16 figures; v.2 references added, typos fixed, improved
discussion of ref. [39]; v.3 more references added and typos fixed, several
statements clarified, v.4 version accepted for publication in JHE
Coulomb-blockade transport in single-crystal organic thin-film transistors
Coulomb-blockade transportâwhereby the Coulomb interaction between electrons can prohibit their transport around a circuitâoccurs in systems in which both the tunnel resistance, RT, between neighbouring sites is large (»h/e2) and the charging energy, EC (EC = e2/2C, where C is the capacitance of the site), of an excess electron on a site is large compared to kT. (Here e is the charge of an electron, k is Boltzmann's constant, and h is Planck's constant.) The nature of the individual sitesâmetallic, superconducting, semiconducting or quantum dotâis to first order irrelevant for this phenomenon to be observed. Coulomb blockade has also been observed in two-dimensional arrays of normal-metal tunnel junctions, but the relatively large capacitances of these micrometre-sized metal islands results in a small charging energy, and so the effect can be seen only at extremely low temperatures. Here we demonstrate that organic thin-film transistors based on highly ordered molecular materials can, to first order, also be considered as an array of sites separated by tunnel resistances. And as a result of the sub-nanometre sizes of the sites (the individual molecules), and hence their small capacitances, the charging energy dominates at room temperature. Conductivity measurements as a function of both gate bias and temperature reveal the presence of thermally activated transport, consistent with the conventional model of Coulomb blockade.
Light States in Chern-Simons Theory Coupled to Fundamental Matter
Motivated by developments in vectorlike holography, we study SU(N)
Chern-Simons theory coupled to matter fields in the fundamental representation
on various spatial manifolds. On the spatial torus T^2, we find light states at
small `t Hooft coupling \lambda=N/k, where k is the Chern-Simons level, taken
to be large. In the free scalar theory the gaps are of order \sqrt {\lambda}/N
and in the critical scalar theory and the free fermion theory they are of order
\lambda/N. The entropy of these states grows like N Log(k). We briefly consider
spatial surfaces of higher genus. Based on results from pure Chern-Simons
theory, it appears that there are light states with entropy that grows even
faster, like N^2 Log(k). This is consistent with the log of the partition
function on the three sphere S^3, which also behaves like N^2 Log(k). These
light states require bulk dynamics beyond standard Vasiliev higher spin gravity
to explain them.Comment: 58 pages, LaTeX, no figures, Minor error corrected, references added,
The main results of the paper have not change
Holographic Conductivity in Disordered Systems
The main purpose of this paper is to holographically study the behavior of
conductivity in 2+1 dimensional disordered systems. We analyze probe D-brane
systems in AdS/CFT with random closed string and open string background fields.
We give a prescription of calculating the DC conductivity holographically in
disordered systems. In particular, we find an analytical formula of the
conductivity in the presence of codimension one randomness. We also
systematically study the AC conductivity in various probe brane setups without
disorder and find analogues of Mott insulators.Comment: 43 pages, 28 figures, latex, references added, minor correction
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