A Method for Individual Source Brightness Estimation in Single- and Multi-band Data

We present a method of reliably extracting the flux of individual sources from sky maps in the presence of noise and a source population in which number counts are a steeply falling function of flux. The method is an extension of a standard Bayesian procedure in the millimeter/submillimeter literature. As in the standard method, the prior applied to source flux measurements is derived from an estimate of the source counts as a function of flux, dN/dS. The key feature of the new method is that it enables reliable extraction of properties of individual sources, which previous methods in the literature do not. We first present the method for extracting individual source fluxes from data in a single observing band, then we extend the method to multiple bands, including prior information about the spectral behavior of the source population(s). The multi-band estimation technique is particularly relevant for classifying individual sources into populations according to their spectral behavior. We find that proper treatment of the correlated prior information between observing bands is key to avoiding significant biases in estimations of multi-band fluxes and spectral behavior, biases which lead to significant numbers of misclassified sources. We test the single- and multi-band versions of the method using simulated observations with observing parameters similar to that of the South Pole Telescope data used in Vieira, et al. (2010).Comment: 11 emulateapj pages, 3 figures, revised to match published versio

Self-Similarity of Friction Laws

The change of the friction law from a mesoscopic level to a macroscopic level is studied in the spring-block models introduced by Burridge-Knopoff. We find that the Coulomb law is always scale invariant. Other proposed scaling laws are only invariant under certain conditions.}Comment: Plain TEX. Figures not include

Behavior and Design of Axially Compressed Sheathed Wall Studs

The objective of this paper is to summarize efforts in a multi year project dedicated to developing a reliable design method for cold - formed steel wall studs that rely on sheathing for bracing. Testing on single columns with sheathing, and full - scale walls with sheathin g, are summarized. Particular emphasis is placed on the observed limit states given the different sheathing conditions. The sheathing supplies beneficial restraint to the wall studs and the stiffness of this sheathing - based restraint is characterized exper imentally and analytically. A unique application of the Direct Strength Method of design is explored where the sheathing - based restraint is used explicitly in determination of the elastic buckling loads of the wall studs, and then these elastic buckling lo ads are utilized to determine the strength. The test results are compared with the newly proposed design method as well as with previous design methods adopted by the AISI Specification. Good agreement is demonstrated for the new approach both in terms of strength an d limit states prediction

Tracking persistence of Helicobacter pylori in potable water biofilms using novel 16S rRNA peptide nucleic acid probes

A two stage chemostat system was used to study the pathogenic bacteria H. pylori association to drinking water biofilms. After allowing one week old biofilms to be grown on stainless steel coupons the system was inoculated with the pathogen that was detected using the recently established technique of 16S rRNA peptide nucleic acid (PNA) fluorescence in situ hybridization (FISH). Results show that H. pylori can successfully incorporate within biofilms and its presence was detected for up to five days, either in the basal layer or inside typical biofilm structures such as stacks or fronds. The PNA FISH protocol appears to be a promising new technique for the in situ visualization of microorganisms in biofilms, especially because the hydrophobic nature of the PNA molecule allows a better diffusion through the constituents of the biofilm matrix allowing an improved discrimination of microorganisms inside these naturally occurring structures. A setback in the application of this methodology was the presence of autofluorescent microorganisms. This problem can be minimized by comparing the morphologic characteristics of these suspected false positives with typical H. pylori morphology. If questions subsist, the visualization of the biofilm under different filter blocks can also improve the degree of certainty in the identification, since the reporter probe has usually a very distinctive pattern of fluorescence when compared to the autofluorescent microorganisms

Chaos and Rotating Black Holes with Halos

The occurrence of chaos for test particles moving around a slowly rotating black hole with a dipolar halo is studied using Poincar\'e sections. We find a novel effect, particles with angular momentum opposite to the black hole rotation have larger chaotic regions in phase space than particles initially moving in the same direction.Comment: 9 pages, 4 Postscript figures. Phys. Rev. D, in pres

Development of an optimized technique for the recovery of H. pylori from water and drinking water biofilms

At present, the route of transmission is perhaps one of the most controversialareas of Helicobacter pylori research. Drinking water and associated biofilms have been suggested as possible environmental reservoirs for the bacterium, however, successful and consistent detection of the bacterium in real systems has not yet been accomplished. A new protocol that offers improved recovery ratings of H. pylori from water and associated-biofilms has been developed and evaluated. This protocol includes optimized incubation atmospheres and a new recovery culture medium, as well as an assessmentof existing techniques for the detachment of H. pylori from surfaces. Even though obvious advantages in terms of cell counts are obtained using this method, certain problems, such as contamination by faster-growing species of the culture medium in heavily contaminated waters may still hinder a successful recovery of the pathogen.Future research will involve further improvement of the protocol and monitoring of real drinking water distribution systems.Unit of Helicobacter/Campylobacter of the Center of Bacteriology of INSA para a Ciência e a Tecnologia (FCT) ; European Commission Research Project SAFER

Beam loading in the nonlinear regime of plasma-based acceleration

A theory that describes how to load negative charge into a nonlinear, three-dimensional plasma wakefield is presented. In this regime, a laser or an electron beam blows out the plasma electrons and creates a nearly spherical ion channel, which is modified by the presence of the beam load. Analytical solutions for the fields and the shape of the ion channel are derived. It is shown that very high beam-loading efficiency can be achieved, while the energy spread of the bunch is conserved. The theoretical results are verified with the Particle-In-Cell code OSIRIS.Comment: 5 pages, 2 figures, to appear in Physical Review Letter

The chiral Anomalous Hall effect in re-entrant AuFe alloys

The Hall effect has been studied in a series of AuFe samples in the re-entrant concentration range, as well as in part of the spin glass range. An anomalous Hall contribution linked to the tilting of the local spins can be identified, confirming theoretical predictions of a novel topological Hall term induced when chirality is present. This effect can be understood in terms of Aharonov-Bohm-like intrinsic current loops arising from successive scatterings by canted local spins. The experimental measurements indicate that the chiral signal persists, meaning scattering within the nanoscopic loops remains coherent, up to temperatures of the order of 150 K.Comment: 7 pages, 11 eps figures Published version. Minor change