1,764 research outputs found
Arrow ribbon graphs
We introduce an additional structure on ribbon graphs, arrow structure. We
extend the Bollob\'as-Riordan polynomial to ribbon graph with this structure.
The extended polynomial satisfies the contraction-deletion relations and
naturally behaves with respect to the partial duality of ribbon graphs. We
construct an arrow ribbon graph from a virtual link whose extended
Bollob\'as-Riordan polynomial specializes to the arrow polynomial of the
virtual link recently introduced by H.Dye and L.Kauffman. This result
generalizes the classical Thistlethwaite theorem to the arrow polynomial of
virtual links.Comment: to appear in Journal of Knot Theory and Its Ramification
Recommended from our members
On the Average Genus of a Graph
Not all rational numbers are possibilities for the average genus of an individual graph. The smallest such numbers are determined, and varied examples are constructed to demonstrate that a single value of average genus can be shared by arbitrarily many different graphs. It is proved that the number one is a limit point of the set of possible values for average genus and that the complete graph K4 is the only 3-connected graph whose average genus is less than one. Several problems for future study are suggested
A Rigorous Derivation of the Gross-Pitaevskii Energy Functional for a Two-Dimensional Bose Gas
We consider the ground state properties of an inhomogeneous two-dimensional
Bose gas with a repulsive, short range pair interaction and an external
confining potential. In the limit when the particle number is large but
is small, where is the average particle density and
the scattering length, the ground state energy and density are rigorously
shown to be given to leading order by a Gross-Pitaevskii (GP) energy functional
with a coupling constant . In contrast to the 3D
case the coupling constant depends on through the mean density. The GP
energy per particle depends only on . In 2D this parameter is typically so
large that the gradient term in the GP energy functional is negligible and the
simpler description by a Thomas-Fermi type functional is adequate.Comment: 14 pages, no figures, latex 2e. References, some clarifications and
an appendix added. To appear in Commun. Math. Phy
Native Electrospray and Electron-Capture Dissociation in FTICR Mass Spectrometry Provide Top-Down Sequencing of a Protein Component in an Intact Protein Assembly
The intact yeast alcohol dehydrogenase (ADH) tetramer of 147 kDa was introduced into a FTICR mass spectrometer by native electrospray. Electron capture dissociation of the entire 23+ to 27+ charge state distribution produced the expected charge-reduced ions and, more unexpectedly, 39 c-type peptide fragments that identified N-terminus acetylation and the first 55 amino acids. The results are in accord with the crystal structure of yeast ADH, which shows that the C-terminus is buried at the assembly interface, whereas the N-terminus is exposed, allowing ECD to occur. This remarkable observation shows promise that a top-down approach for intact protein assemblies will be effective for characterizing their components, inferring their interfaces, and obtaining both proteomics and structural biology information in one experiment
Levels of self-consistency in the GW approximation
We perform calculations on atoms and diatomic molecules at different
levels of self-consistency and investigate the effects of self-consistency on
total energies, ionization potentials and on particle number conservation. We
further propose a partially self-consistent scheme in which we keep the
correlation part of the self-energy fixed within the self-consistency cycle.
This approximation is compared to the fully self-consistent results and to
the and the approximations. Total energies, ionization
potentials and two-electron removal energies obtained with our partially
self-consistent approximation are in excellent agreement with fully
self-consistent results while requiring only a fraction of the
computational effort. We also find that self-consistent and partially
self-consistent schemes provide ionization energies of similar quality as the
values but yield better total energies and energy differences.Comment: 11 pages, 3 figures, 3 table
Precursor Lesions of High-Grade Serous Ovarian Carcinoma: Morphological and Molecular Characteristics
The lack of proven screening tools for early detection and the high mortality of ovarian serous carcinoma (OSC), particularly high grade, have focused attention on identifying putative precursor lesions with distinct morphological and molecular characteristics. The finding of occult invasive and intraepithelial fallopian tube carcinomas in prophylactically removed specimens from asymptomatic high-risk BRCA 1/2-mutation carriers supports the notion of an origin for OSC in the fallopian tube. The intraepithelial carcinomas have been referred to as serous intraepithelial carcinomas (STICs) but our own findings (unpublished data) and recent reports have drawn attention to a spectrum of changes that fall short of STICs that we have designated serous tubal intraepithelial lesions (STILs)
Tetrahydroaminoacridine (THA) reduces voltage-dependent calcium currents in rat sensory neurons
Tetrahydroaminoacridine (THA) is a centrally active anticholinesterase that also interacts with neuronal K+ and Na+ channels and cardiac Ca2+ channels. The effects of THA on neuronal voltage-dependent Ca2+ channels are not known. We tested the effects of THA (25 nM-250 [mu]M) on the Ca2+ current components of acutely dissociated rat nodose ganglion and dorsal root ganglion (DRG) neurons using the whole cell patch clamp recording technique. THA reduced the low-threshold (T) and high-threshold (N/L) Ca2+ current components in a concentration-dependent manner (IC50 [congruent with] 125 [mu]M for T; [congruent with] 80 [mu]M for (N/L). Minimal current reduction was seen below ~ 10 [mu]M. Our results show that THA reduces voltage-dependent Ca2+ currents in rodent sensory neurons suggesting another means by which THA may affect Ca2+-dependent physiologic processes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29032/1/0000064.pd
Classical quasi-particle dynamics in trapped Bose condensates
The dynamics of quasi-particles in repulsive Bose condensates in a harmonic
trap is studied in the classical limit. In isotropic traps the classical motion
is integrable and separable in spherical coordinates. In anisotropic traps the
classical dynamics is found, in general, to be nonintegrable. For
quasi-particle energies E much smaller than thechemical potential, besides the
conserved quasi-particle energy, we identify two additional nearly conserved
phase-space functions. These render the dynamics inside the condensate
(collective dynamics) integrable asymptotically for E/chemical potential very
small. However, there coexists at the same energy a dynamics confined to the
surface of the condensate, which is governed by a classical Hartree-Fock
Hamiltonian. We find that also this dynamics becomes integrable for E/chemical
potential very small, because of the appearance of an adiabatic invariant. For
E/chemical potential of order 1 a large portion of the phase-space supports
chaotic motion, both, for the Bogoliubov Hamiltonian and its Hartree-Fock
approximant. To exemplify this we exhibit Poincar\'e surface of sections for
harmonic traps with the cylindrical symmetry and anisotropy found in TOP traps.
For E/chemical potential very large the dynamics is again governed by the
Hartree-Fock Hamiltonian. In the case with cylindrical symmetry it becomes
quasi-integrable because the remaining small chaotic components in phase space
are tightly confined by tori.Comment: 13 pages Latex, 6 eps.gz-figure
Commissioning and Calibrating the CMS Silicon Strip Tracker
The data acquisition system for the CMS Silicon Strip Tracker (SST) is based around a custom analogue front-end ASIC, an analogue optical link system and an off-detector VME board that performs digitization, zero-suppression and data formatting. A complex procedure is required to optimally configure, calibrate and synchronize the 107 channels of the SST readout system. We present an overview of this procedure, which will be used to commission and calibrate the SST during the integration, Start-Up and operational phases of the experiment. Recent experiences from the CMS Magnet Test Cosmic Challenge and system tests at the Tracker Integration Facility are also reported
- …