Are dentists enough aware of infectious risk associated with dental unit waterlines?

Environmental conditions in DU encourage biofilm development. This biofilm may represent a risk for patients and dental staff exposed to water and aerosols generated during dental cares, particularly for immunocompromised persons. A survey was conducted on the 175 dental surgeons of the department of Vienne (France) to investigate the motivations of dental practitioners to renew their DU, their awareness levels with respect to infectious risks related to water circulating within DU, and methods used for the maintenance of DU waterlines. These dentists were only partially aware of the need for maintaining DU waterlines. For this maintaining, chemical treatments and purges of pipes were carried out by 88% and 91.5% of dentists respectively ; chemical treatments were usually on a continous mode and dentists seemed to have complete confidence in their DU supplier regarding the choice and the use of chemical treatments. Flushes were performed only once per day in most cases (63%). This survey also highlighted that dentists were not enough aware of water related infectous risk, even though 68% estimated that the development of a biofilm within DU waterlines was an actual risk. Finally, very positively, dentists strongly indicated their wish to be more informed regarding all these risks. Although these results are based on a relatively small sample, corresponding to dentists of a French department, they clearly suggest that awareness of dental surgeons is still insufficient and must be performed to permit an effective prevention of infectious risk related to DU waterlines

Particle Physics Explanations for Ultra High Energy Cosmic Ray Events

The origin of cosmic ray events with E \gsim 10^{11} GeV remains mysterious. In this talk I briefly summarize several proposed particle physics explanations: a breakdown of Lorentz invariance, the ``$Z-$burst'' scenario, new hadrons with masses of several GeV as primaries, and magnetic monopoles with mass below $10^{10}$ GeV as primaries. I then describe in a little more detail the idea that these events are due to the decays of very massive, long--lived exotic particles.Comment: Invited plenary talk at PASCOS03, Mumbai, India, January 2003; 13 pages, 1 figur

Probing mSUGRA via the Extreme Universe Space Observatory

An analysis is carried out within mSUGRA of the estimated number of events originating from upward moving ultra-high energy neutralinos that could be detected by the Extreme Universe Space Observatory (EUSO). The analysis exploits a recently proposed technique that differentiates ultra-high energy neutralinos from ultra-high energy neutrinos using their different absorption lengths in the Earth's crust. It is shown that for a significant part of the parameter space, where the neutralino is mostly a Bino and with squark mass $\sim 1$ TeV, EUSO could see ultra-high energy neutralino events with essentially no background. In the energy range 10^9 GeV < E < 10^11 GeV, the unprecedented aperture of EUSO makes the telescope sensitive to neutralino fluxes as low as 1.1 \times 10^{-6} (E/GeV)^{-1.3} GeV^{-1} cm^{-2} yr^{-1} sr^{-1}, at the 95% CL. Such a hard spectrum is characteristic of supermassive particles' $N$-body hadronic decay. The case in which the flux of ultra-high energy neutralinos is produced via decay of metastable heavy particles with uniform distribution throughout the universe is analyzed in detail. The normalization of the ratio of the relics' density to their lifetime has been fixed so that the baryon flux produced in the supermassive particle decays contributes to about 1/3 of the events reported by the AGASA Collaboration below 10^{11} GeV, and hence the associated GeV gamma-ray flux is in complete agreement with EGRET data. For this particular case, EUSO will collect between 4 and 5 neutralino events (with 0.3 of background) in ~ 3 yr of running. NASA's planned mission, the Orbiting Wide-angle Light-collectors (OWL), is also briefly discussed in this context.Comment: Some discussion added, final version to be published in Physical Review

Integrating hydraulic modelling and GIS for wastewater systems management: a case study

The increasing costs related to operation and maintenance of urban wastewater systems has led to a special attention of utilities in promoting studies to address the key problem of water infiltration, inflow and improper connections entering the separate drainage networks. This is a common and hard to predict operational situation that needs to be identified and minimized as it negatively affects the managerial conditions of the network and the downstream wastewater treatment plant (WWTP) efficiency. Management difficulties in separate drainage networks seldom occur when unexpected groundwater inflow, stormwater infiltration, and flows from improper connections enter into the dedicated sanitary sewer systems. Although the consequences that improper flows may have on wastewater systems are known, the problem is difficult to locate and quantify. The use of modelling tools is of special relevance to the planning, management and rehabilitation of these types of systems, which can be very useful for: (i) evaluating the capacity of existing systems in real time; (ii) testing alternative solutions to solve problems detected; or testing different procedures to operate the systems in extreme events scenarios. The implementation of mathematical models for determining the hydrodynamics behaviour of dry-weather and wet-weather flows in sewers was applied in a small urban wastewater network of the city of Braga in Portugal (Figure 1). The free user program US EPA SWMM was applied with the integration of GIS InterAqua information related to the wastewater collection system

Integrating hydraulic modelling and GIS for wastewater systems management: a case study

The increasing costs related to operation and maintenance of urban wastewater systems has led to a special attention of utilities in promoting studies to address the key problem of water infiltration, inflow and improper connections entering the separate drainage networks. This is a common and hard to predict operational situation that needs to be identified and minimized as it negatively affects the managerial conditions of the network and the downstream wastewater treatment plant efficiency. The implementation of mathematical models for determining the hydrodynamics behaviour of dry weather and wet weather flows in sewers appears to be a sound methodology to identify the causes for those adverse management conditions. This methodology was applied in a small urban wastewater network of the city of Braga (Portugal). The free user program USEPA SWMM was applied with the integration of GIS information related to the wastewater collection system

Electroweak jet cascading in the decay of superheavy particles

We study decays of superheavy particles $X$ into leptons. We show that they initiate cascades similar to QCD parton jets, if m_X\gsim 10^6 GeV. Electroweak cascading is studied and the energy spectra of the produced leptons are calculated in the framework of a broken SU(2) model of weak interactions. As application, important for the Z-burst model for ultrahigh energy cosmic rays, we consider decays of superheavy particles coupled on tree-level only to neutrinos and derive stringent limit for these decays from the observed diffuse extragalactic $\gamma$-ray flux.Comment: 4 pages, 1 eps figur

Minimal surfaces and particles in 3-manifolds

We use minimal (or CMC) surfaces to describe 3-dimensional hyperbolic, anti-de Sitter, de Sitter or Minkowski manifolds. We consider whether these manifolds admit ``nice'' foliations and explicit metrics, and whether the space of these metrics has a simple description in terms of Teichm\"uller theory. In the hyperbolic settings both questions have positive answers for a certain subset of the quasi-Fuchsian manifolds: those containing a closed surface with principal curvatures at most 1. We show that this subset is parameterized by an open domain of the cotangent bundle of Teichm\"uller space. These results are extended to ``quasi-Fuchsian'' manifolds with conical singularities along infinite lines, known in the physics literature as ``massive, spin-less particles''. Things work better for globally hyperbolic anti-de Sitter manifolds: the parameterization by the cotangent of Teichm\"uller space works for all manifolds. There is another description of this moduli space as the product two copies of Teichm\"uller space due to Mess. Using the maximal surface description, we propose a new parameterization by two copies of Teichm\"uller space, alternative to that of Mess, and extend all the results to manifolds with conical singularities along time-like lines. Similar results are obtained for de Sitter or Minkowski manifolds. Finally, for all four settings, we show that the symplectic form on the moduli space of 3-manifolds that comes from parameterization by the cotangent bundle of Teichm\"uller space is the same as the 3-dimensional gravity one.Comment: 53 pages, no figure. v2: typos corrected and refs adde

Lorentz invariance violation in top-down scenarios of ultrahigh energy cosmic ray creation

The violation of Lorentz invariance (LI) has been invoked in a number of ways to explain issues dealing with ultrahigh energy cosmic ray (UHECR) production and propagation. These treatments, however, have mostly been limited to examples in the proton-neutron system and photon-electron system. In this paper we show how a broader violation of Lorentz invariance would allow for a series of previously forbidden decays to occur, and how that could lead to UHECR primaries being heavy baryonic states or Higgs bosons.Comment: Replaced with heavily revised (see new Abstract) version accepted by Phys. Rev. D. 6 page

Notes on a paper of Mess

These notes are a companion to the article "Lorentz spacetimes of constant curvature" by Geoffrey Mess, which was first written in 1990 but never published. Mess' paper will appear together with these notes in a forthcoming issue of Geometriae Dedicata.Comment: 26 page

Ultra-High Energy Neutrino Fluxes: New Constraints and Implications

We apply new upper limits on neutrino fluxes and the diffuse extragalactic component of the GeV gamma-ray flux to various scenarios for ultra high energy cosmic rays and neutrinos. As a result we find that extra-galactic top-down sources can not contribute significantly to the observed flux of highest energy cosmic rays. The Z-burst mechanism where ultra-high energy neutrinos produce cosmic rays via interactions with relic neutrinos is practically ruled out if cosmological limits on neutrino mass and clustering apply.Comment: 10 revtex pages, 9 postscript figure