1,086 research outputs found
Semiclassical interferences and catastrophes in the ionization of Rydberg atoms by half-cycle pulses
A multi-dimensional semiclassical description of excitation of a Rydberg
electron by half-cycle pulses is developed and applied to the study of energy-
and angle-resolved ionization spectra. Characteristic novel phenomena
observable in these spectra such as interference oscillations and semiclassical
glory and rainbow scattering are discussed and related to the underlying
classical dynamics of the Rydberg electron. Modifications to the predictions of
the impulse approximation are examined that arise due to finite pulse
durations
Is tissue engineering of the TMJ disc a feasible process?
Temporomandibular joint (TMJ) disorders are common and difficult to remedy. Tissue engineering is one alternative that seeks to improve TMJ sugical treatment options. Tissue engineering aims to replace diseased or injured tissue with biologically engineered constructs. These constructs should reproduce native function and limit an immune response. To achieve tissue engineering success, it is important to first understand the tissue's cellular, biochemical and mechanical properties in order to create validation and design criteria. Reviewd herein are the known properties of the TMJ disc and initial attempts toward TMJ disc tissue engineering. Important aspects of tissue engineering are scaffold selection, cell source, biochemical factors, and mechanical stimuli
Infrared activity of hydrogen molecules trapped in Si
The rovibrational-translational states of a hydrogen molecule moving in a cage site in Si, when subjected to an electrical field arising from its surroundings, are investigated. The wave functions are expressed in terms of basis functions consisting of the eigenfunctions of the molecule confined to move in the cavity and rovibrational states of the free molecule. The energy levels, intensities of infrared and Raman transitions, effects of uniaxial stress, and a neighboring oxygen defect are found and compared with existing experimental data
Experimentally feasible measures of distance between quantum operations
We present two measures of distance between quantum processes based on the
superfidelity, introduced recently to provide an upper bound for quantum
fidelity. We show that the introduced measures partially fulfill the
requirements for distance measure between quantum processes. We also argue that
they can be especially useful as diagnostic measures to get preliminary
knowledge about imperfections in an experimental setup. In particular we
provide quantum circuit which can be used to measure the superfidelity between
quantum processes.
As the behavior of the superfidelity between quantum processes is crucial for
the properties of the introduced measures, we study its behavior for several
families of quantum channels. We calculate superfidelity between arbitrary
one-qubit channels using affine parametrization and superfidelity between
generalized Pauli channels in arbitrary dimensions. Statistical behavior of the
proposed quantities for the ensembles of quantum operations in low dimensions
indicates that the proposed measures can be indeed used to distinguish quantum
processes.Comment: 9 pages, 4 figure
Soil-landscape and climatic relationships in the middle Miocene of the Madrid Basin
The Miocene alluvial-lacustrine sequences of the Madrid Basin, Spain, formed in highly varied landscapes. The presence of various types of palaeosols allows assessment of the effects of local and external factors onsedimentation, pedogenesis and geomorphological development. In the northern, more arid, tectonicallyactive arca, soils were weakly developed in aggrading alluvial fans, dominated by mass flows. reflecting high sedimentation rates. In more distal parts of the fans and in playa lakes calcretes and dolocretes developed: the former were associated with Mg-poor fan sediments whitc: the latter formed on Mg-rich lake clays exposed during minar lake lowstands. The nonh-east part of the basin had a less arid climate. Alluvial fans in this area were dominated by stream Aood deposits, sourced by carbonate terrains. Floodplain and freshwater lakc deposits formed in distal areas. The high local supply of calcium carbonate may have contributed to the preferential developmenl on calcretes on the fans. Both the fan and floodplain palaeosols exhibit pedofacies relationships and more mature soils developed in settings more distant from the sediment sources. Palaeosols also developed on pond and lake margin carbonates, and led to the formation of palustrine limestones. The spatial distributions and stratigraphies of palaeosols in the Madrid Basin alluvial fans suggest that soil formation was controlled by local factors. These palaeosols differ from those seen in Quatemary fans. Which are characterized by climatically induced periods of stability and instability
First- principle calculations of magnetic interactions in correlated systems
We present a novel approach to calculate the effective exchange interaction
parameters based on the realistic electronic structure of correlated magnetic
crystals in local approach with the frequency dependent self energy. The analog
of ``local force theorem'' in the density functional theory is proven for
highly correlated systems. The expressions for effective exchange parameters,
Dzialoshinskii- Moriya interaction, and magnetic anisotropy are derived. The
first-principle calculations of magnetic excitation spectrum for ferromagnetic
iron, with the local correlation effects from the numerically exact QMC-scheme
is presented.Comment: 17 pages, 3 Postscript figure
Measurement of the tensor analyzing power T20 in the dd->^3Hen and dd->^3Hp at intermediate energies and at zero degree
The data on the tensor analyzing power T20 in the dd->^3Hen and dd-> ^3Hp
reactions at 140, 200 and 270 MeV of the deuteron kinetic energy and at zero
degree obtained at RIKEN Accelerator Research Facility are presented. The
observed positive sign of T20 clearly demonstrates the sensitivity to the D/S
wave ratios in the ^3He and ^3H in the energy domain of the measurements. The
T20 data for the ^3He-n and ^3H-p channels are in agreement within experimental
accuracy.Comment: 9 pages, 3 figures, submitted in Phys.Lett.
Twist-3 Distribution Amplitudes of K* and phi Mesons
We present a systematic study of twist-3 light-cone distribution amplitudes
of and mesons in QCD. The structure of SU(3)-breaking corrections
is studied in detail. Non-perturbative input parameters are estimated from QCD
sum rules. As a by-product, we update the parameters describing the twist-3
distribution amplitudes of the meson. We also review and update
predictions for the twist-2 distribution amplitudes of , and
.Comment: 27 page
A study of the centrally produced baryon-antibaryon systems in pp interactions at 450 GeV/c
A study of the centrally produced ppbar, ppbarpi, ppbarpipi and lambda lambda
channels has been performed in pp collisions using an incident beam momentum of
450 GeV/c. No significant new structures are observed in the mass spectra,
however, important new information on the production dynamics is obtained. A
systematic study of the production properties of these systems has been
performed and it is found that these systems are not produced dominantly by
double Pomeron exchange.Comment: 13 pages, Latex, 4 Figure
A study of pseudoscalar states produced centrally in pp interactions at 450 GeV/c
A study has been made of pseudoscalar mesons produced centrally in pp
interactions. The results show that the eta and etaprime appear to have a
similar production mechanism which differs from that of the pi0. The production
properties of the eta and etaprime are not consistent with what is expected
from double Pomeron exchange. In addition the production mechanism for the eta
and etaprime is such that the production cross section are greatest when the
azimuthal angle between the pT vectors of the two protons is 90 degrees.Comment: 11 pages, Latex, 3 Figure
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