Spatial distribution of psychotic disorders in an urban area of France: an ecological study

Previous analyses of neighbourhood variations of non-affective psychotic disorders (NAPD) have focused mainly on incidence. However, prevalence studies provide important insights on factors associated with disease evolution as well as for healthcare resource allocation. This study aimed to investigate the distribution of prevalent NAPD cases in an urban area in France. The number of cases in each neighbourhood was modelled as a function of potential confounders and ecological variables, namely: migrant density, economic deprivation and social fragmentation. This was modelled using statistical models of increasing complexity: frequentist models (using Poisson and negative binomial regressions), and several Bayesian models. For each model, assumptions validity were checked and compared as to how this fitted to the data, in order to test for possible spatial variation in prevalence. Data showed significant overdispersion (invalidating the Poisson regression model) and residual autocorrelation (suggesting the need to use Bayesian models). The best Bayesian model was Leroux's model (i.e. a model with both strong correlation between neighbouring areas and weaker correlation between areas further apart), with economic deprivation as an explanatory variable (OR = 1.13, 95% CI [1.02-1.25]). In comparison with frequentist methods, the Bayesian model showed a better fit. The number of cases showed non-random spatial distribution and was linked to economic deprivation

Electron detachment from negative ions in bichromatic laser field

Negative ion detachment in two-colour laser field is considered within the recent modification of Keldysh model which makes it quantitatively reliable. The general approach is illustrated by calculation of angular differential detachment rates, partial rates for particular ATD (Above Threshold Detachment) channels and total detachment rates for H$^-$ ion in bichromatic field with 1:2 frequency ratio. Both perturbative and strong field regimes are examined. Polar asymmetry and phase effects are quantitatively characterized with some new features revealed. Phase effects are found to result in a huge anisotropy factor $\sim 10^3$ in the electron angular distribution in the perturbative regime.Comment: 13 pages, 8 figures in separate files which are not incorporated in the latex file of the pape

Space-time evolution of electron cascades in diamond

Here we describe model calculations to follow the spatio-temporal evolution of secondary electron cascades in diamond. The band structure of the insulator has been explicitly incorporated into the calculations as it affects ionizations from the valence band. A Monte-Carlo model was constructed to describe the path of electrons following the impact of a single electron of energy E 250 eV. The results show the evolution of the secondary electron cascades in terms of the number of electrons liberated, the spatial distribution of these electrons, and the energy distribution among the electrons as a function of time. The predicted ionization rates (5-13 electrons in 100 fs) lie within the limits given by experiments and phenomenological models. Calculation of the local electron density and the corresponding Debye length shows that the latter is systematically larger than the radius of the electron cloud. This means that the electron gas generated does not represent a plasma in a single impact cascade triggered by an electron of E 250 eV energy. This is important as it justifies the independent-electron approximation used in the model. At 1 fs, the (average) spatial distribution of secondary electrons is anisotropic with the electron cloud elongated in the direction of the primary impact. The maximal radius of the cascade is about 50 A at this time. As the system cools, energy is distributed more equally, and the spatial distribution of the electron cloud becomes isotropic. At 90 fs maximal radius is about 150 A. The Monte-Carlo model described here could be adopted for the investigation of radiation damage in other insulators and has implications for planned experiments with intense femtosecond X-ray sources.Comment: 26 pages, latex, 13 figure

Calibrated Sub-Bundles in Non-Compact Manifolds of Special Holonomy

This paper is a continuation of math.DG/0408005. We first construct special Lagrangian submanifolds of the Ricci-flat Stenzel metric (of holonomy SU(n)) on the cotangent bundle of S^n by looking at the conormal bundle of appropriate submanifolds of S^n. We find that the condition for the conormal bundle to be special Lagrangian is the same as that discovered by Harvey-Lawson for submanifolds in R^n in their pioneering paper. We also construct calibrated submanifolds in complete metrics with special holonomy G_2 and Spin(7) discovered by Bryant and Salamon on the total spaces of appropriate bundles over self-dual Einstein four manifolds. The submanifolds are constructed as certain subbundles over immersed surfaces. We show that this construction requires the surface to be minimal in the associative and Cayley cases, and to be (properly oriented) real isotropic in the coassociative case. We also make some remarks about using these constructions as a possible local model for the intersection of compact calibrated submanifolds in a compact manifold with special holonomy.Comment: 20 pages; for Revised Version: Minor cosmetic changes, some paragraphs rewritten for improved clarit

Differential Photoelectron Holography: A New Approach for Three-Dimensional Atomic Imaging

We propose differential holography as a method to overcome the long-standing forward-scattering problem in photoelectron holography and related techniques for the three-dimensional imaging of atoms. Atomic images reconstructed from experimental and theoretical Cu 3p holograms from Cu(001) demonstrate that this method suppresses strong forward-scattering effects so as to yield more accurate three-dimensional images of side- and back-scattering atoms.Comment: revtex, 4 pages, 2 figure

Adiabatic Theory of Electron Detachment from Negative Ions in Two-Color Laser Field

Negative ion detachment in bichromatic laser field is considered within the adiabatic theory. The latter represents a recent modification of the famous Keldysh model for multiphoton ionization which makes it quantitatively reliable. We calculate angular differential detachment rates, partial rates for particular ATD (Above Threshold Detachment) channels and total detachment rates for the Hydrogen ion in a bichromatic field with 1:3 frequency ratio and various phase differences. Reliability of the present, extremely simple approach is testified by comparison with much more elaborate earlier calculations.Comment: 22 pages, 6 Postscript figure

LEED Holography applied to a complex superstructure: a direct view of the adatom cluster on SiC(111)-(3x3)

For the example of the SiC(111)-(3x3) reconstruction we show that a holographic interpretation of discrete Low Energy Electron Diffraction (LEED) spot intensities arising from ordered, large unit cell superstructures can give direct access to the local geometry of a cluster around an elevated atom, provided there is only one such prominent atom per surface unit cell. By comparing the holographic images obtained from experimental and calculated data we illuminate validity, current limits and possible shortcomings of the method. In particular, we show that periodic vacancies such as cornerholes may inhibit the correct detection of the atomic positions. By contrast, the extra diffraction intensity due to slight substrate reconstructions, as for example buckling, seems to have negligible influence on the images. Due to the spatial information depth of the method the stacking of the cluster can be imaged down to the fourth layer. Finally, it is demonstrated how this structural knowledge of the adcluster geometry can be used to guide the dynamical intensity analysis subsequent to the holographic reconstruction and necessary to retrieve the full unit cell structure.Comment: 11 pages RevTex, 6 figures, Phys. Rev. B in pres

Oral health promotion: the economic benefits to the NHS of increased use of sugarfree gum in the UK.

INTRODUCTION: The effect of sugarfree gum (SFG) on the prevention of dental caries has been established for some time. With increased constraints placed on healthcare budgets, the importance of economic considerations in decision-making about oral health interventions has increased. The aim of this study was to demonstrate the potential cost savings in dental care associated with increased levels of SFG usage. METHODS: The analysis examined the amount of money which would hypothetically be saved if the UK 12-year-old population chewed more SFG. The number of sticks chewed per year and the caries risk reduction were modelled to create a dose response curve. The costs of tooth restoration, tooth extraction in primary care settings and under general anaesthetic were considered, and the effects of caries reduction on these costs calculated. RESULTS: If all members of the UK 12-year-old population chewed SFG frequently (twice a day), the potential cost savings for the cohort over the course of one year were estimated to range from £1.2 to £3.3 million and if they chewed three times a day, £8.2 million could be saved each year. Sensitivity analyses of the key parameters demonstrated that cost savings would still be likely to be observed even in scenarios with less significant increases in SFG use. CONCLUSION: This study shows that if levels of SFG usage in the teenage population in the UK could be increased, substantial cost savings might be achieved

The diagnosis and management of patients with idiopathic osteolysis

Idiopathic osteolysis or disappearing bone disease is a condition characterized by the spontaneous onset of rapid destruction and resorption of a single bone or multiple bones. Disappearing bone disorder is a disease of several diagnostic types. We are presenting three patients with osteolysis who have different underlying pathological features. Detailed phenotypic assessment, radiologic and CT scanning, and histological and genetic testing were the baseline diagnostic tools utilized for diagnosis of each osteolysis syndrome. The first patient was found to have Gorham-Stout syndrome (non-heritable). The complete destruction of pelvic bones associated with aggressive upward extension to adjacent bones (vertebral column and skull base) was notable and skeletal angiomatosis was detected. The second patient showed severe and aggressive non-hereditary multicentric osteolysis with bilateral destruction of the hip bones and the tarsal bones as well as a congenital unilateral solitary kidney and nephropathy. The third patient was phenotypically and genotypically compatible with Winchester syndrome resulting in multicentric osteolysis (autosomal recessive). Proven mutation of the (MMP2-Gen) was detected in this third patient that was associated with 3MCC deficiency (3-Methylcrontonyl CoA Carboxylase deficiency). The correct diagnoses in our 3 patients required the exclusion of malignant osteoclastic tumours, inflammatory disorders of bone, vascular disease, and neurogenic arthropathies using history, physical exam, and appropriate testing and imaging. This review demonstrates how to evaluate and treat these complex and difficult patients. Lastly, we described the various management procedures and treatments utilized for these patients