High zenith angle observations of PKS 2155-304 with the MAGIC telescope

The high frequency peaked BL Lac PKS 2155-304 with a redshift z=0.116 was discovered 1997 in the VHE range by the University of Durham Mark 6 gamma-ray telescope in Australia with a flux corresponding to approx. 0.2 times the Crab Nebula flux. It was later observed and detected with high significance by the Southern observatories CANGAROO and H.E.S.S. establishing this source as the best studied Southern TeV blazar. Detection from the Northern hemisphere was very difficult due to challenging observation conditions under large zenith angles. In July 2006, the H.E.S.S. collaboration reported an extraordinary outburst of VHE gamma-emission. During the outburst, the VHE gamma-ray emission was found to be variable on the time scales of minutes and at a mean flux of approx. 7 times the flux observed from the Crab Nebula. The MAGIC collaboration operates a 17m imaging air Cherenkov Telescope at La Palma (Northern Hemisphere). Follow up observations of the extraordinary outburst have been triggered in a Target of Opportunity program by an alert from the H.E.S.S. collaboration. The measured spectrum and light curve are presented.Comment: Contribution to the 31st ICRC, Lodz, Poland, July 200

The drive system of the Major Atmospheric Gamma-ray Imaging Cherenkov Telescope

The MAGIC telescope is an imaging atmospheric Cherenkov telescope, designed to observe very high energy gamma-rays while achieving a low energy threshold. One of the key science goals is fast follow-up of the enigmatic and short lived gamma-ray bursts. The drive system for the telescope has to meet two basic demands: (1) During normal observations, the 72-ton telescope has to be positioned accurately, and has to track a given sky position with high precision at a typical rotational speed in the order of one revolution per day. (2) For successfully observing GRB prompt emission and afterglows, it has to be powerful enough to position to an arbitrary point on the sky within a few ten seconds and commence normal tracking immediately thereafter. To meet these requirements, the implementation and realization of the drive system relies strongly on standard industry components to ensure robustness and reliability. In this paper, we describe the mechanical setup, the drive control and the calibration of the pointing, as well as present measurements of the accuracy of the system. We show that the drive system is mechanically able to operate the motors with an accuracy even better than the feedback values from the axes. In the context of future projects, envisaging telescope arrays comprising about 100 individual instruments, the robustness and scalability of the concept is emphasized.Comment: 15 pages, 12 (10) figures, submitted to Astroparticle Physics, a high resolution version of the paper (particularly fig. 1) is available at http://publications.mppmu.mpg.de/2008/MPP-2008-101/FullText.pd

Experimental oak wilt control in Missouri

A joint report by the Central States Forest Experiment Station, Forest Service, U.S. Department of Agriculture and the Missouri Agricultural Experiment Station.Digitized 2007 AES.Includes bibliographical references (page [12])

EQUILIBRIUM OF CHILDREN PRACTISING JUDO

INTRODUCTION Human body equilibrium is the index of one's health, physical development, fitness and athletic mastery level. Coordinational abilities of children aged 4-5 in maintaining statodynamic stability have been studied when solving equilibrium motor tasks ( P. Perrin, 1989; V. N. Boloban, 1990; K. Bretz, R. J. Kaske, 1994; A.U. Kholtobina, 1994, et al.) . METHODOLOGY Measurements have been made by means of ADAMtype equipment complex (Software: lngchicurbüro - Dr. K.Bretz, 1992). Different methods of solving equilibrium motor tasks by children have been determined. Their stabilograms consist of such individual parameters as: amplitude, frequency of vibration, duration of test task performance, special location in time function (on isoline, above or below it ) , and in “stabilograph-subject” coordinate system. RESULTS Spectral Fourier-analysis of stabilograms demonstrates that body stability is generally determined by vibrations having the frequencies 0.5-1.5 Hz. In the frequencies above 2-3 Hz, children subjects do not yet possess voluntary motions to regulate body postures. Coordination indices of children's body orthograde position demonstrate necessity of special training to provide body equilibrium. Developed didactical means, methods and control elements provide efficient formation of statodynamic stability skill. Stabilogram indices allow to determine coordinational abilities in children and forecast development of their voluntary motions in the structure of professional orientation

Avalanche statistics of sand heaps

Large scale computer simulations are presented to investigate the avalanche statistics of sand piles using molecular dynamics. We could show that different methods of measurement lead to contradicting conclusions, presumably due to avalanches not reaching the end of the experimental table.Comment: 6 pages, 4 figure