8,238 research outputs found
Measurements and Simulation Studies of Piezoceramics for Acoustic Particle Detection
Calibration sources are an indispensable tool for all detectors. In acoustic
particle detection the goal of a calibration source is to mimic neutrino
signatures as expected from hadronic cascades. A simple and promising method
for the emulation of neutrino signals are piezo ceramics. We will present
results of measruements and simulations on these piezo ceramics.Comment: 5 pages, 5 figure
Reconstruction methods for acoustic particle detection in the deep sea using clusters of hydrophones
This article focuses on techniques for acoustic noise reduction, signal
filters and source reconstruction. For noise reduction, bandpass filters and
cross correlations are found to be efficient and fast ways to improve the
signal to noise ratio and identify a possible neutrino-induced acoustic signal.
The reconstruction of the position of an acoustic point source in the sea is
performed by using small-volume clusters of hydrophones (about 1 cubic meter)
for direction reconstruction by a beamforming algorithm. The directional
information from a number of such clusters allows for position reconstruction.
The algorithms for data filtering, direction and position reconstruction are
explained and demonstrated using simulated data.Comment: 7 pages, 13 figure
Development of High Granulated Straw Chambers of Large Sizes
We have developed the baseline design for the straw drift tube tracking
detectors for high rate environment application. The low-mass inner straw
elements and the technology of the multianode straws assembly was devised and
checked. The prototype chamber was constructed and studied the granularity of
similar chambers can be reduced to one cm2.
Submitted to Physics of Elementary Particles and Atomic Nuclei, LettersComment: 6 pages, 10 figure
Contribution of the nucleon-hyperon reaction channels to K production in proton-nucleus collisions
The cross sections for producing K mesons in nucleon-hyperon elementary
processes are estimated assuming one-pion exchange and using the experimentally
known pion-hyperon cross sections. The results are implemented in a transport
model which is applied to calculation of proton-nucleus collisions. In
significant difference to earlier estimates for heavy-ion collisions the
inclusion of the nucleon-hyperon cross section roughly doubles the K
production in near-threshold proton-nucleus collisions
Bim and Bmf synergize to induce apoptosis in Neisseria gonorrhoeae infection
Abstract: Bcl-2 family proteins including the pro-apoptotic BH3-only proteins are central regulators of apoptotic cell death. Here we show by a focused siRNA miniscreen that the synergistic action of the BH3-only proteins Bim and Bmf is required for apoptosis induced by infection with Neisseria gonorrhoeae (Ngo). While Bim and Bmf were associated with the cytoskeleton of healthy cells, they both were released upon Ngo infection. Loss of Bim and Bmf from the cytoskeleton fraction required the activation of Jun-N-terminal kinase-1 (JNK-1), which in turn depended on Rac-1. Depletion and inhibition of Rac-1, JNK-1, Bim, or Bmf prevented the activation of Bak and Bax and the subsequent activation of caspases. Apoptosis could be reconstituted in Bim-depleted and Bmf-depleted cells by additional silencing of antiapoptotic Mcl-1 and Bcl-XL, respectively. Our data indicate a synergistic role for both cytoskeletal-associated BH3-only proteins, Bim, and Bmf, in an apoptotic pathway leading to the clearance of Ngo-infected cells. Author Summary: A variety of physiological death signals, as well as pathological insults, trigger apoptosis, a genetically programmed form of cell death. Pathogens often induce host cell apoptosis to establish a successful infection. Neisseria gonorrhoeae (Ngo), the etiological agent of the sexually transmitted disease gonorrhoea, is a highly adapted obligate human-specific pathogen and has been shown to induce apoptosis in infected cells. Here we unveil the molecular mechanisms leading to apoptosis of infected cells. We show that Ngo-mediated apoptosis requires a special subset of proapoptotic proteins from the group of BH3-only proteins. BH3-only proteins act as stress sensors to translate toxic environmental signals to the initiation of apoptosis. In a siRNA-based miniscreen, we found Bim and Bmf, BH3-only proteins associated with the cytoskeleton, necessary to induce host cell apoptosis upon infection. Bim and Bmf inactivated different inhibitors of apoptosis and thereby induced cell death in response to infection. Our data unveil a novel pathway of infection-induced apoptosis that enhances our understanding of the mechanism by which BH3-only proteins control apoptotic cell death
Integration of Acoustic Neutrino Detection Methods into ANTARES
The ANTARES Neutrino Telescope is a water Cherenkov detector currently under
construction in the Mediterranean Sea. It is also designed to serve as a
platform for investigations of the deep-sea environment. In this context, the
ANTARES group at the University of Erlangen will integrate acoustic sensors
within the infrastructure of the experiment. With this dedicated setup, tests
of acoustic particle detection methods and deep-sea acoustic background studies
shall be performed. The aim of this project is to evaluate the feasibility of a
future acoustic neutrino telescope in the deep sea operating in the ultra-high
energy regime. In these proceedings, the implementation of the project is
described in the context of the premises and challenges set by the physics of
acoustic particle detection and the integration into an existing
infrastructure.Comment: 6 pages, 5 figures, to appear in the proceedings of the International
ARENA Workshop, May 28-30th, 2006, University of Northumbri
Integration of Acoustic Detection Equipment into ANTARES
The ANTARES group at the University of Erlangen is working towards the
integration of a set of acoustic sensors into the ANTARES Neutrino Telescope.
With this setup, tests of acoustic particle detection methods and background
studies shall be performed. The ANTARES Neutrino Telescope, which is currently
being constructed in the Mediterranean Sea, will be equipped with the
infrastructure to accommodate a 3-dimensional array of photomultipliers for the
detection of Cherenkov light. Within this infrastructure, the required
resources for acoustic sensors are available: Bandwidth for the transmission of
the acoustic data to the shore, electrical power for the off-shore electronics
and physical space to install the acoustic sensors and to route the connecting
cables (transmitting signals and power) into the electronics containers. It
will be explained how the integration will be performed with minimal
modifications of the existing ANTARES design and which setup is foreseen for
the acquisition of the acoustic data.Comment: 5 pages, 1 figure, to appear in the proceedings of the 1st
International ARENA Workshop, May 17-19th, 2005, DESY Zeuthen (Germany
Testing Thermo-acoustic Sound Generation in Water with Proton and Laser Beams
Experiments were performed at a proton accelerator and an infrared laser
acility to investigate the sound generation caused by the energy deposition of
pulsed particle and laser beams in water. The beams with an energy range of 1
PeV to 400 PeV per proton beam spill and up to 10 EeV for the laser pulse were
dumped into a water volume and the resulting acoustic signals were recorded
with pressure sensitive sensors. Measurements were performed at varying pulse
energies, sensor positions, beam diameters and temperatures. The data is well
described by simulations based on the thermo-acoustic model. This implies that
the primary mechanism for sound generation by the energy deposition of
particles propagating in water is the local heating of the media giving rise to
an expansion or contraction of the medium resulting in a pressure pulse with
bipolar shape. A possible application of this effect would be the acoustical
detection of neutrinos with energies greater than 1 EeV.Comment: 5 pages, 2 figures, to appear in the proceedings of the 1st
International ARENA Workshop, May 17-19th, 2005, DESY Zeuthe
Development of Acoustic Sensors for the ANTARES Experiment
In order to study the possibility of acoustic detection of ultra-high energy
neutrinos in water, our group is planning to deploy and operate an array of
acoustic sensors using the ANTARES Neutrino telescope in the Mediterranean Sea.
Therefore, acoustic sensor hardware has to be developed which is both capable
of operation under the hostile conditions of the deep sea and at the same time
provides the high sensitivity necessary to detect the weak pressure signals
resulting from the neutrino's interaction in water. In this paper, two
different approaches to building such sensors, as well as performance studies
in the laboratory and in situ, are presented.Comment: 5 pages, 3 figures. Proceedings of the ARENA 2005 Worksho
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