516,661 research outputs found
Studying Membrane Biogenesis with a Luciferase-Based Reporter Gene Assay
To study the coordination of different lipid synthesis pathways during membrane biogenesis it is useful to work with an experimental system where membrane biogenesis occurs rapidly and in an inducible manner. We have found that phagocytosis of latex beads is practical for these purposes as cells rapidly synthesize membrane lipids to replenish membrane pools lost as wrapping material during particle engulfment. Here, we describe procedures for studying changes in phagocytosis-induced gene expression with a luciferase-based reporter gene approach using the Dual-Glo Luciferase Assay System from Promega
Auxiliary-field quantum Monte Carlo calculations of molecular systems with a Gaussian basis
We extend the recently introduced phaseless auxiliary-field quantum Monte
Carlo (QMC) approach to any single-particle basis, and apply it to molecular
systems with Gaussian basis sets. QMC methods in general scale favorably with
system size, as a low power. A QMC approach with auxiliary fields in principle
allows an exact solution of the Schrodinger equation in the chosen basis.
However, the well-known sign/phase problem causes the statistical noise to
increase exponentially. The phaseless method controls this problem by
constraining the paths in the auxiliary-field path integrals with an
approximate phase condition that depends on a trial wave function. In the
present calculations, the trial wave function is a single Slater determinant
from a Hartree-Fock calculation. The calculated all-electron total energies
show typical systematic errors of no more than a few milli-Hartrees compared to
exact results. At equilibrium geometries in the molecules we studied, this
accuracy is roughly comparable to that of coupled-cluster with single and
double excitations and with non-iterative triples, CCSD(T). For stretched bonds
in HO, our method exhibits better overall accuracy and a more uniform
behavior than CCSD(T).Comment: 11 pages, 5 figures. submitted to JC
An optimal synchronous bandwidth allocation scheme for guaranteeing synchronous message deadlines with the timed-token MAC protocol
This paper investigates the inherent timing properties of the timed-token medium access control (MAC) protocol necessary to guarantee synchronous message deadlines in a timed token ring network such as, fiber distributed data interface (FDDI), where the timed-token MAC protocol is employed. As a result, an exact upper bound, tighter than previously published, on the elapse time between any number of successive token arrivals at a particular node has been derived. Based on the exact protocol timing property, an optimal synchronous bandwidth allocation (SBA) scheme named enhanced MCA (EMCA) for guaranteeing synchronous messages with deadlines equal to periods in length is proposed. Thm scheme is an enhancement on the previously publiibed MCA scheme
Fermi motion and nuclear modification factor
It has been argued recently that the so-called nuclear modification factor
() is an observable useful for identifying the quark-gluon plasma. We
discuss the effect of Fermi motion in nuclei on at CERN SPS and BNL
RHIC energies. Contrary to the simple intuition, rather large effects are found
for CERN SPS. The Fermi motion in nuclei contributes significantly to the
Cronin effect. The effect found is qualitatively similar to the one observed
experimentally at CERN energies and similar to the one obtained in the models
of multiple scattering of initial partons. We predict different size of the
effect for different types of hadrons, especially at low energies.Comment: 16 pages + 6 figures, some calculations have been corrected, text has
been modified accordingly, 1 figure has been added, in print Modern Physics
Letters A19 (2004)
Intramolecular dynamics. II. Artificial intelligence search evaluation function and treatment of resonance centers for large systems
The role of resonance centers in obtaining large size matrices via an artificial intelligence (AI) search is discussed. The results are used to develop for an AI search an evaluation function which takes cognizance of isolated internal resonances in these many-state systems. The effect of later-accepted states on resonance centers is included. This evaluation function and one without a resonance factor are used in Part III of this series. A search is made there to select zeroth-order vibrational states of benzene that are used in a diagonalization treatment of CH overtone spectra. When there are many overlapping resonances, as in that case, a comparison of results obtained with those two types of evaluation function is of particular interest
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