115,614 research outputs found
A simple extended-cavity diode laser
Operating a laser diode in an extended cavity which provides frequency-selective feedback is a very effective method of reducing the laser's linewidth and improving its tunability. We have developed an extremely simple laser of this type, built from inexpensive commercial components with only a few minor modifications, A 780 nm laser built to this design has an output power of 80 mW, a Linewidth of 350 kHz, and it has been continuously locked to a Doppler-free rubidium transition for several days
Differentiated effects of the multimodal antidepressant vortioxetine on sleep architecture: Part 1, a pharmacokinetic/pharmacodynamic comparison with paroxetine in healthy men
We compared the effect of vortioxetine, paroxetine and placebo after three days of dosing on sleep architecture. This was a randomised, double-blind, four-way crossover, placebo-controlled, multiple-dose study in 24 healthy young men. Subjects received 20mg vortioxetine, 40mg vortioxetine, 20mg paroxetine or placebo for three consecutive days in four different periods with at least three weeks between them. Polysomnography and blood sampling for pharmacokinetic analysis were performed on the pre-dose night and nights 1 and 3 of dosing in each period. Plasma concentrations of vortioxetine and paroxetine during the polysomnography measurement were used to estimate SERT occupancies using published relationships in healthy subjects. All three active treatments significantly increased REM onset latency and decreased time spent in REM sleep. In the pharmacokinetic/pharmacodynamics analysis significant relationships were found between REM onset latency and time spent in REM sleep and vortioxetine/paroxetine exposure. The relation between REM suppression parameters and SERT occupancy was significantly different between vortioxetine and paroxetine, despite the same SERT occupancy. This indicates that vortioxetine has a different clinical pharmacological profile from paroxetine, which may explain the differences in adverse effect profile of the two drugs, for instance the lower incidence of nausea, weight gain and sexual dysfunction with vortioxetine
How large is the spreading width of a superdeformed band?
Recent models of the decay out of superdeformed bands can broadly be divided
into two categories. One approach is based on the similarity between the
tunneling process involved in the decay and that involved in the fusion of
heavy ions, and builds on the formalism of nuclear reaction theory. The other
arises from an analogy between the superdeformed decay and transport between
coupled quantum dots. These models suggest conflicting values for the spreading
width of the decaying superdeformed states. In this paper, the decay of
superdeformed bands in the five even-even nuclei in which the SD excitation
energies have been determined experimentally is considered in the framework of
both approaches, and the significance of the difference in the resulting
spreading widths is considered. The results of the two models are also compared
to tunneling widths estimated from previous barrier height predictions and a
parabolic approximation to the barrier shape
The structure of lightning flashes HF-UHF: 12 September 1975, Atlanta, Georgia
Simultaneous measurement of sferics at 3, 30, 139, and 295 MHz were made during thunderstorms. Wideband electronics and an analogue tape recorder continuously recorded the radiation from lightning with about 300 kHz of bandwidth. The data were obtained during the passage of a cold front. Flashing rate, burst rate and the structure of individual flashes were recorded. The record of a typical flash begins with a sudden burst of closely spaced pulses whose temporal structure is typical of the stepped leader, and ends in a large pulse suggestive of a first return stroke. The remainder of the flash consists of a sequence of pulses of varying amplitude separated by quiet periods of the order of milliseconds. The shape of these pulses and the temporal structure suggest that the first few large pulses are return strokes. Other discharges begin with widely spaced discrete pulses and resemble the preceding discharge less the leader and return stroke phase. The radiation exhibits a similar structure, at each of the frequencies monitored
Entanglement of mixed macroscopic superpositions: an entangling-power study
We investigate entanglement properties of a recently introduced class of
macroscopic quantum superpositions in two-mode mixed states. One of the tools
we use in order to infer the entanglement in this non-Gaussian class of states
is the power to entangle a qubit system. Our study reveals features which are
hidden in a standard approach to entanglement investigation based on the
uncertainty principle of the quadrature variables. We briefly describe the
experimental setup corresponding to our theoretical scenario and a suitable
modification of the protocol which makes our proposal realizable within the
current experimental capabilities.Comment: 9 pages, 7 figures, RevTeX
Generation of graph-state streams
We propose a protocol to generate a stream of mobile qubits in a graph state
through a single stationary parent qubit and discuss two types of its physical
implementation, namely, the generation of photonic graph states through an
atom-like qubit and those of flying atoms through a cavity-mode photonic qubit.
The generated graph states fall into an important class that can hugely reduce
the resource requirement of fault-tolerant linear optics quantum computation,
which was previously known to be far from realistic. In regard to the flying
atoms, we also propose a heralded generation scheme, which allows for
high-fidelity graph states even under the photon loss.Comment: Accepted for publication at PRA Rapid Communication
A site selection model to identify optimal locations for microalgae biofuel production facilities in sicily (Italy)
The lack of sustainability and negative environmental impacts of using fossil fuel resources for energy production and their consequent increase in prices during last decades have led to an increasing interest in the development of renewable biofuels. Among possible biomass fuel sources, microalgae represent one of the most promising solutions. The present work is based on the implementation of a model that facilitates identification of optimal geographic locations for large-scale open ponds for microalgae cultivation for biofuels production. The combination of a biomass production model with specific site location parameters such as irradiance, geographical constraints, land use, topography, temperatures and CO2 for biofuels plants were identified in Sicily (Italy). A simulation of CO2 saved by using the theoretical biofuel produced in place of traditional fuel was implemented. Results indicate that the territory of Sicily offers a good prospective for these technologies and the results identify ideal locations for locating biomass fuel production facilities. Moreover, the research provides a robust method that can be tailored to the specific requirements and data availability of other territories. © Research India Publications
The Radio Emission from the Ultra-Luminous Far-Infrared Galaxy NGC 6240
We present new radio observations of the ``prototypical'' ultra-luminous far-
infrared galaxy NGC~6240, obtained using the VLA at 20~cm in `B' configuration
and at 3.6~cm in `A' configuration. These data, along with those from four
previous VLA observations, are used to perform a comprehensive study of the
radio emission from NGC~6240. Approximately 70\% (~3 x 10 W~Hz)
of the total radio power at 20 cm originates from the nuclear region ( <~ 1.5
kpc), of which half is emitted by two unresolved (\alphaS_{\nu} \propto \nu^{-\alpha}). The
supernova rate required to power the diffuse component is consistent with that
predicted by the stellar evolution models of Rieke \etal (1985). If the radio
emission from the two compact cores is powered by supernova remnants, then
either the remnants overlap and form hot bubbles in the cores, or they are very
young ( <~ 100 yr). Nearly all of the other 30\% of the total radio power comes
from an ``arm-like'' region extending westward from the nuclear region. The
western arm emission has a steep spectrum (\alpha^{-14}$ erg/s/cm2 in the 2-10 keV band. No significant radio
emission is detected from or near the possible ultra-massive ``dark core''
hypothesized by Bland-Hawthorn, Wilson \& Tully (1991).Comment: 36 pages (text and tables) as an uuencoded compressed postscript file
(figures available upon request), accepted for the ApJ (20 Nov issue), STScI
preprint no. ?? -- May 199
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