293 research outputs found
Quantum chaos algorithms and dissipative decoherence with quantum trajectories
Using the methods of quantum trajectories we investigate the effects of
dissipative decoherence in a quantum computer algorithm simulating dynamics in
various regimes of quantum chaos including dynamical localization, quantum
ergodic regime and quasi-integrable motion.
As an example we use the quantum sawtooth algorithm which can be implemented
in a polynomial number of quantum gates.
It is shown that the fidelity of quantum computation decays exponentially
with time and that the decay rate is proportional to the number of qubits,
number of quantum gates and per gate dissipation rate induced by external
decoherence.
In the limit of strong dissipation the quantum algorithm generates a quantum
attractor which may have complex or simple structure.
We also compare the effects of dissipative decoherence with the effects of
static imperfections.Comment: 6 pages, 6 figs, research at http://www.quantware.ups-tlse.f
A coherent synchrotron X-ray microradiology investigation of bubble and droplet coalescence
Microradiology with coherent X-rays is shown to be very effective in revealing interfaces in multiphase systems and in particular gas bubbles. Its use has been tested in the study of bubble colescence validating the results with a simple theoretical analysis based on mass conservation
Quantum Separability of the vacuum for Scalar Fields with a Boundary
Using the Green's function approach we investigate separability of the vacuum
state of a massless scalar field with a single Dirichlet boundary. Separability
is demonstrated using the positive partial transpose criterion for effective
two-mode Gaussian states of collective operators. In contrast to the vacuum
energy, entanglement of the vacuum is not modified by the presence of the
boundary.Comment: 4 pages, 1 figure, Revtex, minor corrections. submitted to Phy. Rev.
Zero Cosmological Constant and Nonzero Dark Energy from Holographic Principle
It is shown that the first law of thermodynamics and the holographic
principle applied to an arbitrary large cosmic causal horizon naturally demand
the zero cosmological constant and non-zero dynamical dark energy in the form
of the holographic dark energy. Semiclassical analysis shows that the
holographic dark energy has a parameter and an equation of state
comparable to current observational data, if the entropy of the horizon
saturates the Bekenstein-Hawking bound. This result indicates that quantum
field theory should be modified at large scale to explain dark energy. The
relations among dark energy, quantum vacuum energy and entropic gravity are
also discussed.Comment: Revtex 7 pages 2 fig
Strong Light Confinement in Metal-Coated Si Nanopillars: Interplay of Plasmonic Effects and Geometric Resonance
Plasticity and rectangularity in survival curves
Living systems inevitably undergo a progressive deterioration of physiological function with age and an increase of vulnerability to disease and death. To maintain health and survival, living systems should optimize survival strategies with adaptive interactions among molecules, cells, organs, individuals, and environments, which arises plasticity in survival curves of living systems. In general, survival dynamics in a population is mathematically depicted by a survival rate, which monotonically changes from 1 to 0 with age. It would be then useful to find an adequate function to describe complicated survival dynamics. Here we describe a flexible survival function, derived from the stretched exponential function by adopting an age-dependent shaping exponent. We note that the exponent is associated with the fractal-like scaling in cumulative mortality rate. The survival function well depicts general features in survival curves; healthy populations exhibit plasticity and evolve towards rectangular-like survival curves, as examples in humans or laboratory animals
Identification of hypoxanthine as a urine marker for non-Hodgkin lymphoma by low-mass-ion profiling
<p>Abstract</p> <p>Background</p> <p>Non-Hodgkin lymphoma (NHL) is a hematologic malignancy for which good diagnostic markers are lacking. Despite continued improvement in our understanding of NHL, efforts to identify diagnostic markers have yielded dismal results. Here, we translated low-mass-ion information in urine samples from patients with NHL into a diagnostic marker.</p> <p>Methods</p> <p>To minimize experimental error, we tested variable parameters before MALDI-TOF analysis of low-mass ions in urine. Urine from 30 controls and 30 NHL patients was analyzed as a training set for NHL prediction. All individual peak areas were normalized to total area up to 1000 m/z. The training set analysis was repeated four times. Low-mass peaks that were not affected by changes in experimental conditions were collected using MarkerView™ software. Human Metabolome Database (HMDB) searches and ESI LC-MS/MS analyses were used to identify low-mass ions that exhibited differential patterns in control and NHL urines. Identified low-mass ions were validated in a blinded fashion in 95 controls and 66 NHL urines to determine their ability to discriminate NHL patients from controls.</p> <p>Results</p> <p>The 30 highest-ranking low-mass-ion peaks were selected from the 60-urine training set, and three low-mass-ion peaks with high intensity were selected for identification. Of these, a 137.08-m/z ion showed lower mass-peak intensity in urines of NHL patients, a result that was validated in a 161-urine blind validation set (95 controls and 66 NHL urines). The 130.08-m/z ion was identified from HMDB searches and ESI LC-MS/MS analyses as hypoxanthine (HX). The HX concentration in urines of NHL patients was significantly decreased (P < 0.001) and was correlated with the mass-peak area of the 137.08-m/z ion. At an HX concentration cutoff of 17.4 μM, sensitivity and specificity were 79.2% and 78.4%, respectively.</p> <p>Conclusions</p> <p>The present study represents a good example of low-mass-ion profiling in the setting of disease screening using urine. This technique can be a powerful non-invasive diagnostic tool with high sensitivity and specificity for NHL screening. Furthermore, HX identified in the study may be a useful single urine marker for NHL screening.</p
Kaluza-Klein Induced Gravity Inflation
A D-dimensional induced gravity theory is studied carefully in a
dimensional Friedmann-Robertson-Walker space-time. We try to extract
information of the symmetry breaking potential in search of an inflationary
solution with non-expanding internal-space. We find that the induced gravity
model imposes strong constraints on the form of symmetry breaking potential in
order to generate an acceptable inflationary universe. These constraints are
analyzed carefully in this paper.Comment: 10 pages, title changed, corrected some typos, two additional
comments adde
A Radically Configurable Six-State Compound
Most organic radicals possess short lifetimes and quickly undergo dimerization or oxidation.
Here, we report on the synthesis by radical templation of a class of air- and water-stable
organic radicals, trapped within a homo[2]catenane composed of two rigid and fixed cyclobis
(paraquat-p-phenylene) rings. The highly energetic octacationic homo[2]catenane, which is
capable of accepting up to eight electrons, can be configured reversibly, both chemically
and electrochemically, between each one of six experimentally accessible redox states
(0, 2+, 4+, 6+, 7+, and 8+) from within the total of nine states evaluated by quantum
mechanical methods. All six of the observable redox states have been identified by electrochemical
techniques, three (4+, 6+, and 7+) have been characterized by x-ray crystallography, four
(4+, 6+, 7+, and 8+) by electron paramagnetic resonance spectroscopy, one (7+) by
superconducting quantum interference device magnetometry, and one (8+) by nuclear
magnetic resonance spectroscopy
- …