452 research outputs found
Development of Combined Opto-Acoustical Sensor Modules
The faint fluxes of cosmic neutrinos expected at very high energies require
large instrumented detector volumes. The necessary volumes in combination with
a sufficient shielding against background constitute forbidding and complex
environments (e.g. the deep sea) as sites for neutrino telescopes. To withstand
these environments and to assure the data quality, the sensors have to be
reliable and their operation has to be as simple as possible. A compact sensor
module design including all necessary components for data acquisition and
module calibration would simplify the detector mechanics and ensures the long
term operability of the detector. The compact design discussed here combines
optical and acoustical sensors inside one module, therefore reducing
electronics and additional external instruments for calibration purposes. In
this design the acoustical sensor is primary used for acoustic positioning of
the module. The module may also be used for acoustic particle detection and
marine science if an appropriate acoustical sensor is chosen.
First tests of this design are promising concerning the task of calibration.
To expand the field of application also towards acoustic particle detection
further improvements concerning electromagnetic shielding and adaptation of the
single components are necessary.Comment: 4 pages, 2 figures, ARENA2010 proceeding
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
Position reconstruction of acoustic sources with the AMADEUS Detector
This article focuses on techniques for position reconstruction of acoustic
point sources with the AMADEUS setup consisting of 36 acoustic sensors in the
Mediterranean Sea. The direction reconstruction of an acoustic point source
utilizes the information of the 6 small-volume hydrophone clusters of AMADEUS
individually. Source position reconstruction is then done by combining the
directional information of each cluster. The algorithms for direction and
position reconstruction are explained and demonstrated using data taken in the
deep sea.Comment: 4 pages, 7 figures, to appear in the proceedings of the 3rd
International Workshop on the Acoustic and Radio EeV Neutrino detection
Activities, Rome, Ital
Involvement of formyl peptide receptors in the stimulatory effect of crotoxin on macrophages co-cultivated with tumour cells
Crotoxin (CTX) is the main neurotoxic component of Crotalus durissus terrificus snake venom. It inhibits tumour growth and modulates the function of macrophages, which are essential cells in the tumour microenvironment. the present study investigated the effect of CTX on the secretory activity of monocultured macrophages and macrophages co-cultivated with LLC-WRC 256 cells. the effect of the macrophage secretory activities on tumour cell proliferation was also evaluated. Macrophages pre-treated with CTX (0.3 mu g/mL) for 2 h were co-cultivated with LLC-WRC 256 cells, and the secretory activity of the macrophages was determined after 12, 24 and 48 h. the co-cultivation of CTX-treated macrophages with the tumour cells caused a 20% reduction in tumour cell proliferation. the production of both H2O2 and NO was increased by 41% and 29% after 24 or 48 h of co-cultivation, respectively, compared to the values for the co-cultures of macrophages of control. the level of secreted IL-1 beta increased by 3.7- and 3.2-fold after 12 h and 24 h of co-cultivation, respectively. Moreover, an increased level of LXA(4) (25%) was observed after 24 h of co-cultivation, and a 2.3- and 2.1-fold increased level of 15-epi-LXA(4) was observed after 24 h and 48 h, respectively. Boc-2, a selective antagonist of formyl peptide receptors, blocked both the stimulatory effect of CTX on the macrophage secretory activity and the inhibitory effect of these cells on tumour cell proliferation. Taken together, these results indicate that CTX enhanced the secretory activity of macrophages, which may contribute to the antitumour activity of these cells, and that activation of formyl peptide receptors appears to play a major role in this effect. (C) 2013 Elsevier B.V. All rights reserved.Fundação de Amparo Ă Pesquisa do Estado de SĂŁo Paulo (FAPESP)Conselho Nacional de Desenvolvimento CientĂfico e TecnolĂłgico (CNPq)PAPInstituto Nacional de Ciencia e Tecnologia em ToxinasButantan Inst, Lab Pathophysiol, BR-05503900 SĂŁo Paulo, BrazilUniversidade Federal de SĂŁo Paulo, Lab Inflammat & Vasc Pharmacol, BR-09913030 Diadema, SP, BrazilUniv SĂŁo Paulo, Fac Med, BR-01246000 SĂŁo Paulo, BrazilUniv SĂŁo Paulo, Inst Biomed Sci, Dept Anat, BR-05508900 SĂŁo Paulo, BrazilUniv SĂŁo Paulo, Inst Biomed Sci, Dept Physiol & Biophys, BR-05508900 SĂŁo Paulo, BrazilButantan Inst, Special Lab Pain & Signaling, BR-05503900 SĂŁo Paulo, BrazilUniversidade Federal de SĂŁo Paulo, Lab Inflammat & Vasc Pharmacol, BR-09913030 Diadema, SP, BrazilFAPESP: 09/52330-9Instituto Nacional de Ciencia e Tecnologia em Toxinas: INCTTOX 2008/57898-0Web of Scienc
Science verification of the new FlashCam-based camera in the 28m telescope of H.E.S.S
In October 2019 the central 28m telescope of the H.E.S.S. experiment has beenupgraded with a new camera. The camera is based on the FlashCam design whichhas been developed in view of a possible future implementation in themedium-sized telescopes of the Cherenkov Telescope Array (CTA). We report hereon the results of the science verification program that has been performedafter commissioning of the new camera, to show that the camera and softwarepipelines are working up to expectations.<br
The Glial Regenerative Response to Central Nervous System Injury Is Enabled by Pros-Notch and Pros-NFÎşB Feedback
Organisms are structurally robust, as cells accommodate changes preserving structural integrity and function. The molecular mechanisms underlying structural robustness and plasticity are poorly understood, but can be investigated by probing how cells respond to injury. Injury to the CNS induces proliferation of enwrapping glia, leading to axonal re-enwrapment and partial functional recovery. This glial regenerative response is found across species, and may reflect a common underlying genetic mechanism. Here, we show that injury to the Drosophila larval CNS induces glial proliferation, and we uncover a gene network controlling this response. It consists of the mutual maintenance between the cell cycle inhibitor Prospero (Pros) and the cell cycle activators Notch and NFÎşB. Together they maintain glia in the brink of dividing, they enable glial proliferation following injury, and subsequently they exert negative feedback on cell division restoring cell cycle arrest. Pros also promotes glial differentiation, resolving vacuolization, enabling debris clearance and axonal enwrapment. Disruption of this gene network prevents repair and induces tumourigenesis. Using wound area measurements across genotypes and time-lapse recordings we show that when glial proliferation and glial differentiation are abolished, both the size of the glial wound and neuropile vacuolization increase. When glial proliferation and differentiation are enabled, glial wound size decreases and injury-induced apoptosis and vacuolization are prevented. The uncovered gene network promotes regeneration of the glial lesion and neuropile repair. In the unharmed animal, it is most likely a homeostatic mechanism for structural robustness. This gene network may be of relevance to mammalian glia to promote repair upon CNS injury or disease
Performance of the First ANTARES Detector Line
In this paper we report on the data recorded with the first Antares detector
line. The line was deployed on the 14th of February 2006 and was connected to
the readout two weeks later. Environmental data for one and a half years of
running are shown. Measurements of atmospheric muons from data taken from
selected runs during the first six months of operation are presented.
Performance figures in terms of time residuals and angular resolution are
given. Finally the angular distribution of atmospheric muons is presented and
from this the depth profile of the muon intensity is derived.Comment: 14 pages, 9 figure
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