362 research outputs found
Measurement Of Transverse Instability Thresholds In Low And high Emittance optics At The Photon Factory Storage Ring
Universal Behavior of Correlations between Eigenvalues of Random Matrices
The universal connected correlations proposed recently between eigenvalues of
unitary random matrices is examined numerically. We perform an ensemble average
by the Monte Carlo sampling. Although density of eigenvalues and a bare
correlation of the eigenvalues are not universal, the connected correlation
shows a universal behavior after smoothing.Comment: ISSP-September-199
Correlation functions of eigenvalues of multi-matrix models, and the limit of a time dependent matrix
We consider the correlation functions of eigenvalues of a unidimensional
chain of large random hermitian matrices. An asymptotic expression of the
orthogonal polynomials allows to find new results for the correlations of
eigenvalues of different matrices of the chain. Eventually, we consider the
limit of the infinite chain of matrices, which can be interpreted as a time
dependent one-matrix model, and give the correlation functions of eigenvalues
at different times.Comment: Tex-Harvmac, 27 pages, submitted to Journ. Phys.
New measurement on photon yields from air and the application to the energy estimation of primary cosmic rays
The air fluorescence technique is used to detect ultra-high energy cosmic
rays (UHECR), and to estimate their energy. Of fundamental importance is the
photon yield due to excitation by electrons, in air of various densities and
temperatures. After our previous report, the experiment has been continued
using a Sr90 source to study the pressure dependence of photon yields
for radiation in nitrogen and dry air. The photon yields in 15 wave bands
between 300 nm and 430 nm have been determined. The total photon yield between
300 nm and 406 nm (used in most experiments) in air excited by a 0.85 MeV
electron is 3.81+-0.13 (+-13 % systematics) photons per meter at 1013 hPa and
20 C. The air density and temperature dependencies of 15 wave bands
are given for application to UHECR observations.Comment: 23 pages, 8 figures, LaTeX with elsart.cls, accepted by Astroparticle
Physic
Indigenous evolution of Plasmodium falciparum pyrimethamine resistance multiple times in Africa
A study on the sharp knee and fine structures of cosmic ray spectra
The paper investigates the overall and detailed features of cosmic ray (CR)
spectra in the knee region using the scenario of nuclei-photon interactions
around the acceleration sources. Young supernova remnants can be the physical
realities of such kind of CR acceleration sites. The results show that the
model can well explain the following problems simultaneously with one set of
source parameters: the knee of CR spectra and the sharpness of the knee, the
detailed irregular structures of CR spectra, the so-called "component B" of
Galactic CRs, and the electron/positron excesses reported by recent
observations. The coherent explanation serves as evidence that at least a
portion of CRs might be accelerated at the sources similar to young supernova
remnants, and one set of source parameters indicates that this portion mainly
comes from standard sources or from a single source.Comment: 13 pages, 4 figures, accepted for publication in SCIENCE CHINA
Physics, Mechanics & Astronomy
High Resolution Intravital Imaging of Subcellular Structures of Mouse Abdominal Organs Using a Microstage Device
Intravital imaging of brain and bone marrow cells in the skull with subcellular resolution has revolutionized neurobiology, immunology and hematology. However, the application of this powerful technology in studies of abdominal organs has long been impeded by organ motion caused by breathing and heartbeat. Here we describe for the first time a simple device designated âmicrostageâ that effectively reduces organ motions without causing tissue lesions. Combining this microstage device with an upright intravital laser scanning microscope equipped with a unique stick-type objective lens, the system enables subcellular-level imaging of abdominal organs in live mice. We demonstrate that this technique allows for the quantitative analysis of subcellular structures and gene expressions in cells, the tracking of intracellular processes in real-time as well as three-dimensional image construction in the pancreas and liver of the live mouse. As the aforementioned analyses based on subcellular imaging could be extended to other intraperitoneal organs, the technique should offer great potential for investigation of physiological and disease-specific events of abdominal organs. The microstage approach adds an exciting new technique to the in vivo imaging toolbox
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