114 research outputs found
A formula for the Bloch vector of some Lindblad quantum systems
Using the Bloch representation of an N-dimensional quantum system and
immediate results from quantum stochastic calculus, we establish a closed
formula for the Bloch vector, hence also for the density operator, of a quantum
system following a Lindblad evolution with selfadjoint Lindblad operators.Comment: Accepted in Phys. Lett. A (shorter version than original
An Immunocompetent Mouse Model of HPV16(+) Head and Neck Squamous Cell Carcinoma
The incidence of human papilloma virus (HPV)-associated head and neck squamous cell carcinoma (HNSCC) is increasing and implicated in more than 60% of all oropharyngeal carcinomas (OPSCCs). Although whole-genome, transcriptome, and proteome analyses have identified altered signaling pathways in HPV-induced HNSCCs, additional tools are needed to investigate the unique pathobiology of OPSCC. Herein, bioinformatics analyses of human HPV(+) HNSCCs revealed that all tumors express full-length E6 and identified molecular subtypes based on relative E6 and E7 expression levels. To recapitulate the levels, stoichiometric ratios, and anatomic location of E6/E7 expression, we generated a genetically engineered mouse model whereby balanced expression of E6/E7 is directed to the oropharyngeal epithelium. The addition of a mutant PIK3CAE545K allele leads to the rapid development of pre-malignant lesions marked by immune cell accumulation, and a subset of these lesions progress to OPSCC. This mouse provides a faithful immunocompetent model for testing treatments and investigating mechanisms of immunosuppression
Rotational Surfaces in and Solutions in the Nonlinear Sigma Model
The Gauss map of non-degenerate surfaces in the three-dimensional Minkowski
space are viewed as dynamical fields of the two-dimensional O(2,1) Nonlinear
Sigma Model. In this setting, the moduli space of solutions with rotational
symmetry is completely determined. Essentially, the solutions are warped
products of orbits of the 1-dimensional groups of isometries and elastic curves
in either a de Sitter plane, a hyperbolic plane or an anti de Sitter plane. The
main tools are the equivalence of the two-dimensional O(2,1) Nonlinear Sigma
Model and the Willmore problem, and the description of the surfaces with
rotational symmetry. A complete classification of such surfaces is obtained in
this paper. Indeed, a huge new family of Lorentzian rotational surfaces with a
space-like axis is presented. The description of this new class of surfaces is
based on a technique of surgery and a gluing process, which is illustrated by
an algorithm.Comment: PACS: 11.10.Lm; 11.10.Ef; 11.15.-q; 11.30.-j; 02.30.-f; 02.40.-k. 45
pages, 11 figure
Quantum Computing in the Presence of Detected Spontaneous Emission
A new method for quantum computation in the presence of detected spontaneous
emission is proposed. The method combines strong and fast (dynamical
decoupling) pulses and a quantum error correcting code that encodes logical
qubits into only physical qubits. Universal fault-tolerant quantum
computation is shown to be possible in this scheme using Hamiltonians relevant
to a range of promising proposals for the physical implementation of quantum
computers.Comment: 7 pages, no figures. This version corrects an error in the
description of spontaneous emission in the quantum jumps picture. As a
consequence the error correcting code and some aspects of the preparation,
computation, and recovery operations have been modified. The main conclusions
of the published paper remain intact. An erratum will be published shortly in
Phys. Rev. A, detailing all the corrections required in the published paper.
The present version includes all these corrections in the body of the pape
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Self-referencing Mach-Zehnder interferometer as a laser system diagnostic: Active and adaptive optical systems
We are incorporating a novel self-referencing Mach-Zehnder interferometer into a large scale laser system as a real time, interactive diagnostic tool for wavefront measurement. The instrument is capable of absolute wavefront measurements accurate to better than {lambda}/10 pv over a wavelength range > 300 nm without readjustment of the optical components. This performance is achieved through the design of both refractive optics and catadioptric collimator to achromatize the Mach-Zehnder reference arm. Other features include polarization insensitivity through the use of low angles of incidence on all beamsplitters as well as an equal path length configuration that allows measurement of either broad-band or closely spaced laser-line sources. Instrument accuracy is periodically monitored in place by means of a thermally and mechanically stable wavefront reference source that is calibrated off-line with a phase conjugate interferometer. Video interferograms are analyzed using Fourier transform techniques on a computer that includes dedicated array processor. Computer and video networks maintain distributed interferometers under the control of a single analysis computer with multiple user access. 7 refs., 11 figs
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