4,882 research outputs found
Eigenvector Approximation Leading to Exponential Speedup of Quantum Eigenvalue Calculation
We present an efficient method for preparing the initial state required by
the eigenvalue approximation quantum algorithm of Abrams and Lloyd. Our method
can be applied when solving continuous Hermitian eigenproblems, e.g., the
Schroedinger equation, on a discrete grid. We start with a classically obtained
eigenvector for a problem discretized on a coarse grid, and we efficiently
construct, quantum mechanically, an approximation of the same eigenvector on a
fine grid. We use this approximation as the initial state for the eigenvalue
estimation algorithm, and show the relationship between its success probability
and the size of the coarse grid.Comment: 4 page
Time--Evolving Statistics of Chaotic Orbits of Conservative Maps in the Context of the Central Limit Theorem
We study chaotic orbits of conservative low--dimensional maps and present
numerical results showing that the probability density functions (pdfs) of the
sum of iterates in the large limit exhibit very interesting
time-evolving statistics. In some cases where the chaotic layers are thin and
the (positive) maximal Lyapunov exponent is small, long--lasting
quasi--stationary states (QSS) are found, whose pdfs appear to converge to
--Gaussians associated with nonextensive statistical mechanics. More
generally, however, as increases, the pdfs describe a sequence of QSS that
pass from a --Gaussian to an exponential shape and ultimately tend to a true
Gaussian, as orbits diffuse to larger chaotic domains and the phase space
dynamics becomes more uniformly ergodic.Comment: 15 pages, 14 figures, accepted for publication as a Regular Paper in
the International Journal of Bifurcation and Chaos, on Jun 21, 201
Inhibition of human glutathione transferases by pesticides: Development of a simple analytical assay for the quantification of pesticides in water
Glutathione transferases (GSTs; EC 2.5.1.18) form a group of multifunctional enzymes that are involved in phase II cellular detoxification mechanism. Here, screening of the inhibition potency of a wide range of pesticides toward selected human GST isoenzymes (hGSTA1-1, hGSTP1-1, hGSTT2-2 and hGSTO1-1) was carried out. hGSTA1-1 was found more susceptible to inhibition by pesticides than other isoenzymes. The insecticides dieldrin and spiromesifen were identified as potent reversible inhibitors toward hGSTA1- 1 with IC50 values equal to 17.9 ± 1.7 M and 12.1 ± 3.4 M, respectively. Based on in silico docking analysis and kinetic inhibition studies it was concluded that dieldrin and spiromesifen bind specifically to the enzyme presumably at a distinct position that partially overlaps with both the G- and H-site. The ability of dieldrin and spiromesifen to inhibit hGSTA1-1 activity was exploited for the development of analytical quantification assays for these two pesticides. Linear calibration curves were obtained for dieldrin and spiromesifen, with useful concentration in the range of 0–10 M. The reproducibility of the assay response, expressed by relative standard deviation, was in the order of 4.1% (N = 28). The method was successfully applied to the determination of these pesticides in real water samples without sample preparation steps
Fabrication of integrated planar gunn diode and micro-cooler on GaAs substrate
We demonstrate fabrication of an integrated
micro cooler with the planar Gunn diode and characterise
its performance. First experimental results have shown a
small cooling at the surface of the micro cooler. This is first
demonstration of an integrated micro-cooler with a planar
Gunn diode
Planar gunn diode characterisation and resonators elements to realise oscillator circuits
The paper describes the planar Gunn diode, which is well suited to providing milli-metric and tera hertz sources using microwave monolithic integrated circuit (MMIC) technologies. Different planar Gunn electrode geometries are described along with DC, RF and thermal characterisation. To realize the planar high frequency sources there is requirement for high frequency planar resonators, the paper will describe both the radial and new diamond shaped geometries
Construction of Integrals of Higher-Order Mappings
We find that certain higher-order mappings arise as reductions of the
integrable discrete A-type KP (AKP) and B-type KP (BKP) equations. We find
conservation laws for the AKP and BKP equations, then we use these conservation
laws to derive integrals of the associated reduced maps.Comment: appear to Journal of the Physical Society of Japa
Acoustic radiation controls friction: Evidence from a spring-block experiment
Brittle failures of materials and earthquakes generate acoustic/seismic waves
which lead to radiation damping feedbacks that should be introduced in the
dynamical equations of crack motion. We present direct experimental evidence of
the importance of this feedback on the acoustic noise spectrum of
well-controlled spring-block sliding experiments performed on a variety of
smooth surfaces. The full noise spectrum is quantitatively explained by a
simple noisy harmonic oscillator equation with a radiation damping force
proportional to the derivative of the acceleration, added to a standard viscous
term.Comment: 4 pages including 3 figures. Replaced with version accepted in PR
High-Spatial-Resolution Monitoring of Strong Magnetic Field using Rb vapor Nanometric-Thin Cell
We have implemented the so-called -Zeeman technique (LZT) to
investigate individual hyperfine transitions between Zeeman sublevels of the Rb
atoms in a strong external magnetic field in the range of G
(recently it was established that LZT is very convenient for the range of G). Atoms are confined in a nanometric thin cell (NTC) with the thickness
, where is the resonant wavelength 794 nm for Rb
line. Narrow velocity selective optical pumping (VSOP) resonances in the
transmission spectrum of the NTC are split into several components in a
magnetic field with the frequency positions and transition probabilities
depending on the -field. Possible applications are described, such as
magnetometers with nanometric local spatial resolution and tunable atomic
frequency references.Comment: 12 page
The development of planar Gunn diodes for the realisation of MMIC oscillators
This review presents the development of planar Gunn diodes over the last few years for the implementation of millimetre-wave sources. The fabrication procedure incorporates electron beam lithography and the oscillation frequency is determined by the anode-to-cathode distance. The evolution of the material design for the maximisation of the maximum frequency of oscillation and the enhancement of the generated power is presented in this paper. The recent implementation of a planar Gunn diode with a high-electron mobility transistor on the same substrate is also described in this work
- …