719 research outputs found
Special symplectic Lie groups and hypersymplectic Lie groups
A special symplectic Lie group is a triple such that
is a finite-dimensional real Lie group and is a left invariant
symplectic form on which is parallel with respect to a left invariant
affine structure . In this paper starting from a special symplectic Lie
group we show how to ``deform" the standard Lie group structure on the
(co)tangent bundle through the left invariant affine structure such
that the resulting Lie group admits families of left invariant hypersymplectic
structures and thus becomes a hypersymplectic Lie group. We consider the affine
cotangent extension problem and then introduce notions of post-affine structure
and post-left-symmetric algebra which is the underlying algebraic structure of
a special symplectic Lie algebra. Furthermore, we give a kind of double
extensions of special symplectic Lie groups in terms of post-left-symmetric
algebras.Comment: 32 page
Lyapunov exponents for products of complex Gaussian random matrices
The exact value of the Lyapunov exponents for the random matrix product with each , where
is a fixed positive definite matrix and a complex Gaussian matrix with entries standard complex normals, are
calculated. Also obtained is an exact expression for the sum of the Lyapunov
exponents in both the complex and real cases, and the Lyapunov exponents for
diffusing complex matrices.Comment: 15 page
Identification and functional characterization of an N-terminal oligomerization domain for polycystin-2*
Autosomal dominant polycystic kidney disease (ADPKD), the most common inherited cause of kidney failure, is caused by mutations in either PKD1 (85%) or PKD2 (15%). The PKD2 protein, polycystin-2 (PC2 or TRPP2), is a member of the transient receptor potential (TRP) superfamily and functions as a non-selective calcium channel. PC2 has been found to form oligomers in native tissues suggesting that it may form functional homo- or heterotetramers with other subunits, similar to other TRP channels. Our experiments unexpectedly revealed that PC2 mutant proteins lacking the known C-terminal dimerization domain were still able to form oligomers and co-immunoprecipitate full-length PC2, implying the possible existence of a proximal dimerization domain. Using yeast two-hybrid and biochemical assays, we have mapped an alternative dimerization domain to the N terminus of PC2 (NT2-1-223, L224X). Functional characterization of this domain demonstrated that it was sufficient to induce cyst formation in zebrafish embryos and inhibit PC2 surface currents in mIMCD3 cells probably by a dominant-negative mechanism. In summary, we propose a model for PC2 assembly as a functional tetramer which depends on both C- and N-terminal dimerization domains. These results have significant implications for our understanding of PC2 function and disease pathogenesis in ADPKD and provide a new strategy for studying PC2 function
Beam Dynamics of Qi Storage Rings
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
Measure representation and multifractal analysis of complete genomes
This paper introduces the notion of measure representation of DNA sequences.
Spectral analysis and multifractal analysis are then performed on the measure
representations of a large number of complete genomes. The main aim of this
paper is to discuss the multifractal property of the measure representation and
the classification of bacteria. From the measure representations and the values
of the spectra and related curves, it is concluded that these
complete genomes are not random sequences. In fact, spectral analyses performed
indicate that these measure representations considered as time series, exhibit
strong long-range correlation. For substrings with length K=8, the
spectra of all organisms studied are multifractal-like and sufficiently smooth
for the curves to be meaningful. The curves of all bacteria
resemble a classical phase transition at a critical point. But the 'analogous'
phase transitions of chromosomes of non-bacteria organisms are different. Apart
from Chromosome 1 of {\it C. elegans}, they exhibit the shape of double-peaked
specific heat function.Comment: 12 pages with 9 figures and 1 tabl
Electronic Structure of a Hydrogenic Acceptor Impurity in Semiconductor Nano-structures
The electronic structure and binding energy of a hydrogenic acceptor impurity in 2, 1, and 0-dimensional semiconductor nano-structures (i.e. quantum well (QW), quantum well wire (QWW), and quantum dot (QD)) are studied in the framework of effective-mass envelope-function theory. The results show that (1) the energy levels monotonically decrease as the quantum confinement sizes increase; (2) the impurity energy levels decrease more slowly for QWWs and QDs as their sizes increase than for QWs; (3) the changes of the acceptor binding energies are very complex as the quantum confinement size increases; (4) the binding energies monotonically decrease as the acceptor moves away from the nano-structures’ center; (5) as the symmetry decreases, the degeneracy is lifted, and the first binding energy level in the QD splits into two branches. Our calculated results are useful for the application of semiconductor nano-structures in electronic and photoelectric devices
Calibration of the Gamma-RAy Polarimeter Experiment (GRAPE) at a Polarized Hard X-Ray Beam
The Gamma-RAy Polarimeter Experiment (GRAPE) is a concept for an astronomical
hard X-ray Compton polarimeter operating in the 50 - 500 keV energy band. The
instrument has been optimized for wide-field polarization measurements of
transient outbursts from energetic astrophysical objects such as gamma-ray
bursts and solar flares. The GRAPE instrument is composed of identical modules,
each of which consists of an array of scintillator elements read out by a
multi-anode photomultiplier tube (MAPMT). Incident photons Compton scatter in
plastic scintillator elements and are subsequently absorbed in inorganic
scintillator elements; a net polarization signal is revealed by a
characteristic asymmetry in the azimuthal scattering angles. We have
constructed a prototype GRAPE module containing a single CsI(Na) calorimeter
element, at the center of the MAPMT, surrounded by 60 plastic elements. The
prototype has been combined with custom readout electronics and software to
create a complete "engineering model" of the GRAPE instrument. This engineering
model has been calibrated using a nearly 100% polarized hard X-ray beam at the
Advanced Photon Source at Argonne National Laboratory. We find modulation
factors of 0.46 +/- 0.06 and 0.48 +/- 0.03 at 69.5 keV and 129.5 keV,
respectively, in good agreement with Monte Carlo simulations. In this paper we
present details of the beam test, data analysis, and simulations, and discuss
the implications of our results for the further development of the GRAPE
concept.Comment: 35 pages, 14 figures, accepted for publication in NIM-
Electroexcitation of the at low momentum transfer
We report on new p measurements at the
resonance at the low momentum transfer region. The mesonic
cloud dynamics is predicted to be dominant and rapidly changing in this
kinematic region offering a test bed for chiral effective field theory
calculations. The new data explore the low dependence of the resonant
quadrupole amplitudes while extending the measurements of the Coulomb
quadrupole amplitude to the lowest momentum transfer ever reached. The results
disagree with predictions of constituent quark models and are in reasonable
agreement with dynamical calculations that include pion cloud effects, chiral
effective field theory and lattice calculations. The reported measurements
suggest that improvement is required to the theoretical calculations and
provide valuable input that will allow their refinements
Partial Wave Analysis of
BES data on are presented. The
contribution peaks strongly near threshold. It is fitted with a
broad resonance with mass MeV, width MeV. A broad resonance peaking at 2020 MeV is also required
with width MeV. There is further evidence for a component
peaking at 2.55 GeV. The non- contribution is close to phase
space; it peaks at 2.6 GeV and is very different from .Comment: 15 pages, 6 figures, 1 table, Submitted to PL
Fine mapping of the tomato yellow leaf curl virus resistance gene Ty-2 on chromosome 11 of tomato
Resistances to begomoviruses, including bipartite tomato mottle virus and monopartite tomato yellow leaf curl virus (TYLCV), have been introgressed to cultivated tomato (Solanumlycopersicum) fromwild tomato accessions. A major gene, Ty-2 from S. habrochaites f. glabratum accession ‘‘B6013,’’ that confers resistance to TYLCV was previously mapped to a 19-cMregion on the long arm of chromosome 11. In the present study, approximately 11,000 plants were screened and nearly 157 recombination events were identified between the flankingmarkersC2_At1g07960 (82.5 cM, physical distance 51.387 Mb) and T0302 (89 cM, 51.878 Mb). Molecular marker analysis of recombinants and TYLCV evaluation of progeny from these recombinants localized Ty-2 to an approximately 300,000-bp interval between markers UP8 (51.344 Mb) and M1 (51.645 Mb). No recombinants were identified between TG36 and C2_At3g52090, a region of at least 115 kb, indicating severe recombination suppression in this region. Due to the small interval, fluorescence in situ hybridization analysis failed to clarify whether recombination suppression is caused by chromosomal rearrangements. Candidate genes predicted based on tomato genome annotation were analyzed by RT-PCR and virus-induced gene silencing. Results indicate that the NBS gene family present in the Ty-2 region is likely not responsible for the Ty-2-conferred resistance and that two candidate genes might play a role in the Ty-2-conferred resistance. Severalmarkers very tightly linked to the Ty-2 locus are presented and useful for marker-assisted selection in breeding programs to introgress Ty-2 for begomovirus resistance
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