292 research outputs found
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
Correlations between eigenvalues of large random matrices with independent entries
We derive the connected correlation functions for eigenvalues of large
Hermitian random matrices with independently distributed elements using both a
diagrammatic and a renormalization group (RG) inspired approach. With the
diagrammatic method we obtain a general form for the one, two and three-point
connected Green function for this class of ensembles when matrix elements are
identically distributed, and then discuss the derivation of higher order
functions by the same approach. Using the RG approach we re-derive the one and
two-point Green functions and show they are unchanged by choosing certain
ensembles with non-identically distributed elements. Throughout, we compare the
Green functions we obtain to those from the class of ensembles with unitary
invariant distributions and discuss universality in both ensemble classes.Comment: 23 pages, RevTex, hard figures available from [email protected]
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.
Effective Hadron Dynamics: From Meson Masses to the Proton Spin Puzzle
We construct a three flavor chiral Lagrangian of pseudoscalars and vectors
with special emphasis on the symmetry breaking terms. Comparing tree level two
and three point functions with experiment allows us to first, fix the
parameters of the model (including the light quark mass ratios) and second, to
predict and
. The last mentioned quantities come
out reasonably well, in contrast to an ``ordinary" treatment. For this
purpose we need ``second order" symmetry breakers involving the vector fields
analogous to those needed for the chiral perturbation theory program with only
pseudoscalars. An improved description of the system is also
given. We then use the soliton sector of this improved chiral Lagrangian to
investigate some aspects of baryon physics which are especially sensitive to
symmetry breaking. For this purpose a fairly elaborate ``cranking" techinque is
employed in connection with the collective Hamiltonian. In addition to the
``strong" baryon mass spectrum a careful investigation is made of the
non-electromagnetic part of the neutron-proton mass difference. This work is
needed to improve our previous estimates concerning the two component approach
to the ``proton spin" puzzle. We find that both the ``matter" and ``glue"
contributions are small but they do tend to cancel each other.Comment: 33 pages, LaTe
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 ‘microstage’ 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
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
Highly Asynchronous and Asymmetric Cleavage Divisions Accompany Early Transcriptional Activity in Pre-Blastula Medaka Embryos
In the initial phase of development of fish embryos, a prominent and critical event is the midblastula transition (MBT). Before MBT cell cycle is rapid, highly synchronous and zygotic gene transcription is turned off. Only during MBT the cell cycle desynchronizes and transcription is activated. Multiple mechanisms, primarily the nucleocytoplasmic ratio, are supposed to control MBT activation. Unexpectedly, we find in the small teleost fish medaka (Oryzias latipes) that at very early stages, well before midblastula, cell division becomes asynchronous and cell volumes diverge. Furthermore, zygotic transcription is extensively activated already after the 64-cell stage. Thus, at least in medaka, the transition from maternal to zygotic transcription is uncoupled from the midblastula stage and not solely controlled by the nucleocytoplasmic ratio
Moduli Effects on Neutrino Oscillations
We point out the possibility to detect the low-energy signals of moduli in
the superstring theory through the neutrino oscillation. The idea is based on
the characteristics that the couplings of moduli are different from matter to
matter. We estimate the oscillation probability both in the baseline and solar
neutrino oscillations. In both cases, when there is at least one modulus of
which mass is less than or equal to GeV, the interaction of the
modulus significantly changes the conversion probability from one neutrino
flavor to another.Comment: 17pages, Latex, 3 figures (available from the author upon request by
FAX or mail
Captivating behaviour: mouse models, experimental genetics and reductionist returns in the neurosciences
This a post-print, author-produced version of an article accepted for publication in The Sociological Review. Copyright © 2010 Wiley Blackwell. The definitive version is available at www3.interscience.wiley.comNo Abstract availabl
A review of the catfish genus Pterocryptis (Siluridae) in Vietnam, with the description of two new species
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73958/1/j.1095-8649.2001.tb02367.x.pd
- …