384 research outputs found
Effects of aircraft noise on human activities
The effects of aircrft noise on human activities was investigated by developing a battery of tasks (1) representative of a range of human activities and (2) sensitive to the disruptive effects of noise. The noise used were recordings of jet aircraft and helicopter sounds at three lvels of loudness--60, 70, and 80 dB(A). Experiment 1 investigated 12 different cognitive tasks, along with two intelligibility tasks included to validate that the noises were being effective. Interference with intelligibility was essentially the same as found in the research literature, but only inconsistent effects were found on either accuracy or latency of performance on the cognitive tasks. When the tasks were grouped into four categories (Intelligibility, Matching, Verbal, and Arithmetic), reliable differences in rated annoyingness of the noises were related to the task category and to the type of noise (jet or helicopter)
Fractionation of distance in simulated space
Fractionation of distance in space environment simulatio
Magnitude estimation of perceived distance over various distance ranges
Magnitude estimation judgments of perceived distance for stationary space vehicle under conditions simulating outer spac
Verbal estimation of distance in a simulated space environment
Human performance in estimating distances in simulated space environmen
p-Type doping of II-VI heterostructures from surface states: application to ferromagnetic CdMnTe quantum wells
We present a study of p-type doping of CdTe and CdMnTe quantum
wells from surface states. We show that this method is as efficient as usual
modulation doping with nitrogen acceptors, and leads to hole densities
exceeding cm. Surface doping was successfully applied
to obtain carrier-induced ferromagnetism in a CdMnTe quantum well.
The observed temperature dependence of photoluminescence spectra, and the
critical temperature, correspond well to those previously reported for
ferromagnetic quantum wells doped with nitrogen.Comment: 4 figure
Distance discrimination in a simulated space environment
Successive comparisons method used for distance discrimination tests in simulated space environmen
Light and electric field control of ferromagnetism in magnetic quantum structures
A strong influence of illumination and electric bias on the Curie temperature
and saturation value of the magnetization is demonstrated for semiconductor
structures containing a modulation-doped p-type Cd0.96Mn0.04Te quantum well
placed in various built-in electric fields. It is shown that both light beam
and bias voltage generate an isothermal and reversible cross-over between the
paramagnetic and ferromagnetic phases, in the way that is predetermined by the
structure design. The observed behavior is in quantitative agreement with the
expectations for systems, in which ferromagnetic interactions are mediated by
the weakly disordered two-dimensional hole liquid.Comment: 4 pages and 3 figure
Optical frequency measurement of the 1S-3S two-photon transition in hydrogen
This article reports the first optical frequency measurement of the
transition in hydrogen. The excitation of this
transition occurs at a wavelength of 205 nm which is obtained with two
frequency doubling stages of a titanium sapphire laser at 820 nm. Its frequency
is measured with an optical frequency comb. The second-order Doppler effect is
evaluated from the observation of the motional Stark effect due to a transverse
magnetic field perpendicular to the atomic beam. The measured value of the
frequency splitting is with a relative uncertainty of
. After the measurement of the
frequency, this result is the most precise of the optical frequencies in
hydrogen
Unconventional MBE Strategies from Computer Simulations for Optimized Growth Conditions
We investigate the influence of step edge diffusion (SED) and desorption on
Molecular Beam Epitaxy (MBE) using kinetic Monte-Carlo simulations of the
solid-on-solid (SOS) model. Based on these investigations we propose two
strategies to optimize MBE growth. The strategies are applicable in different
growth regimes: During layer-by-layer growth one can exploit the presence of
desorption in order to achieve smooth surfaces. By additional short high flux
pulses of particles one can increase the growth rate and assist layer-by-layer
growth. If, however, mounds are formed (non-layer-by-layer growth) the SED can
be used to control size and shape of the three-dimensional structures. By
controlled reduction of the flux with time we achieve a fast coarsening
together with smooth step edges.Comment: 19 pages, 7 figures, submitted to Phys. Rev.
Block of death-receptor apoptosis protects mouse cytomegalovirus from macrophages and is a determinant of virulence in immunodeficient hosts.
The inhibition of death-receptor apoptosis is a conserved viral function. The murine cytomegalovirus (MCMV) gene M36 is a sequence and functional homologue of the human cytomegalovirus gene UL36, and it encodes an inhibitor of apoptosis that binds to caspase-8, blocks downstream signaling and thus contributes to viral fitness in macrophages and in vivo. Here we show a direct link between the inability of mutants lacking the M36 gene (ΔM36) to inhibit apoptosis, poor viral growth in macrophage cell cultures and viral in vivo fitness and virulence. ΔM36 grew poorly in RAG1 knockout mice and in RAG/IL-2-receptor common gamma chain double knockout mice (RAGγC(-/-)), but the depletion of macrophages in either mouse strain rescued the growth of ΔM36 to almost wild-type levels. This was consistent with the observation that activated macrophages were sufficient to impair ΔM36 growth in vitro. Namely, spiking fibroblast cell cultures with activated macrophages had a suppressive effect on ΔM36 growth, which could be reverted by z-VAD-fmk, a chemical apoptosis inhibitor. TNFα from activated macrophages synergized with IFNγ in target cells to inhibit ΔM36 growth. Hence, our data show that poor ΔM36 growth in macrophages does not reflect a defect in tropism, but rather a defect in the suppression of antiviral mediators secreted by macrophages. To the best of our knowledge, this shows for the first time an immune evasion mechanism that protects MCMV selectively from the antiviral activity of macrophages, and thus critically contributes to viral pathogenicity in the immunocompromised host devoid of the adaptive immune system
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