Absolute calibration of the LOPES antenna system

Radio emission in extensive air showers arises from an interaction with the geomagnetic field and is subject of theoretical studies. This radio emission has advantages for the detection of high energy cosmic rays compared to secondary particle or fluorescence measurement methods. Radio antennas like the LOPES30 antenna system are suited to investigate this emission process by detecting the radio pulses. The characteristic observable parameters like electric field strength and pulse length require a calibration which was done with a reference radio source resulting in an amplification factor representing the system behavior in the environment of the KASCADE-Grande experiment. Knowing the amplification factor and the gain of the LOPES antennas LOPES30 is calibrated absolutely for systematic analyses of the radio emission.Comment: 5 pages, Proceedings of International Workshop on Acoustic and Radio EeV Neutrino detection Activities: ARENA, May 17-19, 2005, DESY Zeuthe

Secretion of flagellin by the LEE-encoded type III secretion system of enteropathogenic Escherichia coli

Background: Enteropathogenic Escherichia coli (EPEC) is an attaching and effacing (A/E) pathogen that possesses a type III secretion system (T3SS) encoded within the locus of enterocyte effacement (LEE). The LEE is essential for A/E lesion formation and directs the secretion and translocation of multiple LEE-encoded and non-LEE encoded effector proteins into the cytosol of infected cells. In this study we used proteomics to compare proteins exported to the culture supernatant by wild type EPEC E2348/69, a Delta espADB mutant and a Delta escF T3SS mutant

Simple surface functionalization strategy for immunosensing detection of aflatoxin B1

This paper describes the strategy of functionalization of gold electrodes surfaces in aim to obtain a new impedimetric immunosensor for the detection of aflatoxin B1, a common toxic food contaminant. The immunosensor elaboration is based on immobilization of anti-aflatoxin antibody on gold electrodes modified with a cross-linked film of bovine serum albumin, by a four-step protocol. The immunosensor is based on a simple design and requires small volumes of toxic aflatoxin solution. All the steps of the immunosensor elaboration and the immunochemical reaction between aflatoxin and antibody were followed using atomic force microscopy (AFM) and electrochemical impedance spectroscopy (EIS). The resistance to charge transfer (Rct) was the most sensitive parameter to changes induced to the interfacial properties of the immunosensor by the incubation with aflatoxin and varied linearly with aflatoxin concentration in the range 1-20 ng/mL. The immunosensor was applied for the detection of aflatoxin in spiked plant extracts with good recovery factors

Radioelectric Field Features of Extensive Air Showers Observed with CODALEMA

Based on a new approach to the detection of radio transients associated with extensive air showers induced by ultra high energy cosmic rays, the experimental apparatus CODALEMA is in operation, measuring about 1 event per day corresponding to an energy threshold ~ 5. 10^16 eV. Its performance makes possible for the first time the study of radio-signal features on an event-by-event basis. The sampling of the magnitude of the electric field along a 600 meters axis is analyzed. It shows that the electric field lateral spread is around 250 m (FWHM). The possibility to determine with radio both arrival directions and shower core positions is discussed.Comment: Accepted for publication in Astroparticle Physic