52,540 research outputs found
The First Scientific Results from the Pierre Auger Observatory
The southern site of the Pierre Auger Observatory is under the construction
near Malargue in Argentina and now more than 60% of the detectors are
completed. The observatory has been collecting data for over 1 year and the
cumulative exposure is already similar to that of the largest forerunner
experiments. The hybrid technique provides model-independent energy
measurements from the Fluorescence Detector to calibrate the Surface Detector.
Based on this technique, the first estimation of the energy spectrum above 3
EeV has been presented and is discussed in this paper.Comment: 4 pages, 1 figure, Proceedings of the PANIC 2005 conferenc
Resonance Production at STAR
We present the first measurement of mid-rapidity vector meson
production in collisions at RHIC ( GeV) from the
STAR detector. For the 11% most central collisions, the slope parameter from an
exponential fit to the transverse mass distribution is ~37951(stat)
45(syst)~MeV, the yield 0.37(stat) 0.57(syst) per
event and the ratio is found to be
0.0210.001(stat) 0.03(syst). We currently place the value of the
ratio between 0.10 and 0.16. The measured ratios
and , as well as for the meson
at mid-rapidity do not change for the selected centrality bins.Comment: 8 pages, 7 figures (in eps) talk given at XXXI International
Symposium on Multiparticle Dynamics, Sep. 1-7, 2001, Datong China at
http://ismd31.ccnu.edu.cn
Intrinsic double-peak structure of the specific heat in low-dimensional quantum ferrimagnets
Motivated by recent magnetic measurements on A3Cu3(PO4)4 (A=Ca,Sr) and
Cu(3-Clpy)2(N3)2 (3-Clpy=3-Chloropyridine), both of which behave like
one-dimensional ferrimagnets, we extensively investigate the ferrimagnetic
specific heat with particular emphasis on its double-peak structure. Developing
a modified spin-wave theory, we reveal that ferromagnetic and antiferromagnetic
dual features of ferrimagnets may potentially induce an extra low-temperature
peak as well as a Schottky-type peak at mid temperatures in the specific heat.Comment: 5 pages, 6 figures embedded, Phys. Rev. B 65, 214418 (2002
Effect of tangential traction and roughness on crack initiation/propagation during rolling contact
Rolling fatigue tests of 0.45 percent carbon steel rollers were carried out using a four roller type rolling contact fatigue tester. Tangential traction and surface roughness of the harder mating rollers were varied and their effect was studied. The results indicate that the fatigue life decreases when fraction is applied in the same direction as that of rolling. When the direction of fraction is reversed, the life increases over that obtained with zero traction. The roughness of harder mating roller also has a marked influence on life. The smoother the mating roller, the longer the life. Microscopic observation of specimens revealed that the initiation of cracks during the early stages of life is more strongly influenced by the surface roughness, while the propagation of these cracks in the latter stages is affected mainly by the tangential traction
SKILL EVALUATION OF MOVEMENT BASED ON HUMAN LIMB ELECTRICAL IMPEDANCE
The purpose of this work is to propose a skill evaluation of tennis movement based on forearm electrical impedance and its measurement method. We try to evaluate the pattern of movement using the pattern of impedance waveform and the stability of movement using the reproducibility of impedance waveform. It can be intuitively evaluated reproducibility and mobility of serve movement using waveform of forearm electrical impedance (Z). Consequently 4 parameters which show reproducibility and mobility using waveform of Z was defined. We made a trial about principal component analysis of Z during serve and got a scatter diagram of first second principal component about 9 subjects including skilful and beginner players. Then the principal component analysis devided subjects into skilful and beginner players. The measurement method of Z used the four electrodes technique based on constant current(50 k Hz,500 uA). Z changes with the changes of cross sectional area of muscle and blood volume caused by the change of joint angle and acceleration. Hence Z has information of movement. The results of this experiment was as follows. In waveforms of Z during serve with a ball and without a ball, each waveform of a skillful player was very similar to each other, but each waveform of a beginner player was not. Z of a skillful player varied more than that Z of a beginner player, because the movement of a skillful player is larger than that of a beginner player. The advantages of this method are as follows. There is no spatial and temporal limitation for measurement. The subject is scarcely restricted in movement. Although we must select appropriate locations of electrodes in each type of movement, this method can be expected to have applications for various sports
- …