3,215 research outputs found
Software tools for big data resources in family names dictionaries
This paper describes the design and development of specific software tools used during the creation of Family Names in Britain and Ireland (FaNBI) research project, started by the University of the West of England in 2010 and finished successfully in 2016. First, the overview of the project and methodology is provided. Next section contains the description of dictionary management tools and software tools to combine input data resources
Bistatic LIDAR experiment proposed for the shuttle/tethered satellite system missions
A new experiment concept has been proposed for the shuttle/tethered satellite system missions, which can provide high resolution, global density mappings of certain ionospheric species. The technique utilizes bistatic LIDAR to take advantage of the unique dual platform configuration offered by these missions. A tuned, shuttle-based laser is used to excite a column of the atmosphere adjacent to the tethered satellite, while triangulating photometic detectors on the satellite are employed to measure the fluorescence from sections of the column. The fluorescent intensity at the detectors is increased about six decades over both ground-based and monostatic shuttle-based LIDAR sounding of the same region. In addition, the orbital motion of the Shuttle provides for quasi-global mapping unattainable with ground-based observations. Since this technique provides such vastly improved resolution on a synoptic scale, many important middle atmospheric studies, heretofore untenable, may soon be addressed
Dispersion-shifted all-solid high index-contrast microstructured optical fiber for nonlinear applications at 1.55µm
We report the fabrication of an all-solid highly nonlinear microstructured optical fiber. The structured preform was made by glass extrusion using two types of commercial lead silicate glasses that provide high index-contrast. Effectively single-moded guidance was observed in the fiber at 1.55µm. The effective nonlinearity and the propagation loss at this wavelength were measured to be 120W/km respectively at 1.55µm. These predictions are consistent with the experimentally determined dispersion of +12.5ps/nm/km at 1.55µm. Tunable and efficient four-wave-mixing based wavelength conversion was demonstrated at wavelengths around 1.55µm using a 1.5m length of the fiber
Multichannel wavelength conversion of 40 Gbit/s NRZ DPSK signals in a highly nonlinear dispersion flattened lead silicate fibre
We experimentally demonstrate the wavelength conversion of three wavelength multiplexed 40 Gbit/s Differential Phase Shift Keyed (DPSK) signals in a 2.2m length of highly nonlinear, dispersion tailored W-type lead-silicate optical fibre
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Cleanup of a Department of Energy Nonreactor Nuclear Facility: Experience at the Los Alamos National Laboratory High Pressure Tritium Laboratory
On October 25, 1990, Los Alamos National Laboratory (LANL) ceased programmatic operations at the High Pressure Tritium Laboratory (HPTL). Since that time, LANL has been preparing the facility for transfer into the Department of Energy`s (DOE`s) Decontamination and Decommissioning Program. LANL staff now has considerable operational experience with the cleanup of a 40-year-old facility used exclusively to conduct experiments in the use of tritium, the radioactive isotope of hydrogen. Tritium and its compounds have permeated the HPTL structure and equipment, have affected operations and procedures, and now dominate efforts at cleanup and disposal. At the time of shutdown, the HPTL still had a tritium inventory of over 100 grams in a variety of forms and containers
Preparation and optical properties of GA(x)IN(1-x)P alloys
The solution crystallization method was used to obtain Ga(z)In(1-x)P alloys for all values of x desired between zero and 1. The method of preparation makes it possible to crystallize the solid at a constant temperature. The points obtained by cathodoluminescence are nearly in straight lines. The optical absorption thresholds are confirmed in the results and make it possible to define the nature of the transitions except when x is in the neighborhood of 0.65. These determinations agree with those of Hilsum and Porteus (1968), but are not in agreement with those obtained by Lorenz et al, (1968)
Control of posture with FES systems
One of the major obstacles in restoration of functional FES supported standing in paraplegia is the lack of knowledge of a suitable control strategy. The main issue is how to integrate the purposeful actions of the non-paralysed upper body when interacting with the environment while standing, and the actions of the artificial FES control system supporting the paralyzed lower extremities. In this paper we provide a review of our approach to solving this question, which focuses on three inter-related areas: investigations of the basic mechanisms of functional postural responses in neurologically intact subjects; re-training of the residual sensory-motor activities of the upper body in paralyzed individuals; and development of closed-loop FES control systems for support of the paralyzed joints
Cavity cooling of a single atom
All conventional methods to laser-cool atoms rely on repeated cycles of
optical pumping and spontaneous emission of a photon by the atom. Spontaneous
emission in a random direction is the dissipative mechanism required to remove
entropy from the atom. However, alternative cooling methods have been proposed
for a single atom strongly coupled to a high-finesse cavity; the role of
spontaneous emission is replaced by the escape of a photon from the cavity.
Application of such cooling schemes would improve the performance of atom
cavity systems for quantum information processing. Furthermore, as cavity
cooling does not rely on spontaneous emission, it can be applied to systems
that cannot be laser-cooled by conventional methods; these include molecules
(which do not have a closed transition) and collective excitations of Bose
condensates, which are destroyed by randomly directed recoil kicks. Here we
demonstrate cavity cooling of single rubidium atoms stored in an intracavity
dipole trap. The cooling mechanism results in extended storage times and
improved localization of atoms. We estimate that the observed cooling rate is
at least five times larger than that produced by free-space cooling methods,
for comparable excitation of the atom
Resonator-Enhanced Optical Dipole Trap for Fermionic Lithium Atoms
We demonstrate a novel optical dipole trap which is based on the enhancement
of the optical power density of a Nd:YAG laser beam in a resonator. The trap is
particularly suited for experiments with ultracold gases, as it combines a
potential depth of order 1 mK with storage times of several tens of seconds. We
study the interactions in a gas of fermionic lithium atoms in our trap and
observe the influence of spin-changing collisions and off-resonant photon
scattering. A key element in reaching long storage times is an ultra-low noise
laser. The dependence of the storage time on laser noise is investigated.Comment: 4 pages 3 figures Revised 17.07.2001; Corrected calibration of noise
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Optical decay from a Fabry-Perot cavity faster than the decay time
The dynamical response of an optical Fabry-Perot cavity is investigated
experimentally. We observe oscillations in the transmitted and reflected light
intensity if the frequency of the incoupled light field is rapidly changed. In
addition, the decay of a cavity-stored light field is accelerated if the phase
and intensity of the incoupled light are switched in an appropriate way. The
theoretical model by M. J. Lawrence em et al, JOSA B 16, 523 (1999) agrees with
our observations.Comment: submitted to Josa
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