247,314 research outputs found
Evidence of a saturated gravity-wave spectrum throughout the atmosphere
The view adapted here is that the dominant mesoscale motions are due to internal gravity waves and show that previous and new vertical wave number spectra of horizontal winds are consistent with the notion of a saturation limit on wave amplitudes. It is also proposed that, at any height, only those vertical wave numbers m less than m sub asterisk are at saturation amplitudes, where m sub asterisk is the vertical wave number of the dominant energy-containing scale. Wave numbers m less than m sub asterisk are unsaturated, but experience growth with height due to the decrease of atmospheric density. The result is a saturated spectrum of gravity waves with both m sub asterisk decreasing and wave energy increasing with height. This saturation theory is consistent with a variety of atmospheric spectral observations and provides a basis for the notion of a universal spectrum of atmospheric gravity waves
Charge and spin state readout of a double quantum dot coupled to a resonator
State readout is a key requirement for a quantum computer. For
semiconductor-based qubit devices it is usually accomplished using a separate
mesoscopic electrometer. Here we demonstrate a simple detection scheme in which
a radio-frequency resonant circuit coupled to a semiconductor double quantum
dot is used to probe its charge and spin states. These results demonstrate a
new non-invasive technique for measuring charge and spin states in quantum dot
systems without requiring a separate mesoscopic detector
Adjustable high emittance gap filler
A flexible, adjustable refractory filler is disclosed for filling gaps between ceramic tiles forming the heat shield of a space shuttle vehicle, to protect its aluminum skin during atmospheric reentry. The easily installed and replaced filler consists essentially of a strip of ceramic cloth coated, at least along both its longitudinal edges with a room temperature vulcanizable silicone rubber compound with a high emittance colored pigment. The filler may have one or more layers as the gap width requires. Preferred materials are basket weave aluminoborosilicate cloth, and a rubber compounded with silicon tetraboride as the emittance agent and finely divided borosilicate glass containing about 7.5% B2O3 as high temperature binder. The filler cloth strip or tape is cut to proper width and length, inserted into the gap, and fastened with previously applied drops of silicone rubber adhesive
Observation of Entanglement-Dependent Two-Particle Holonomic Phase
Holonomic phases---geometric and topological---have long been an intriguing
aspect of physics. They are ubiquitous, ranging from observations in particle
physics to applications in fault tolerant quantum computing. However, their
exploration in particles sharing genuine quantum correlations lack in
observations. Here we experimentally demonstrate the holonomic phase of two
entangled-photons evolving locally, which nevertheless gives rise to an
entanglement-dependent phase. We observe its transition from geometric to
topological as the entanglement between the particles is tuned from zero to
maximal, and find this phase to behave more resilient to evolution changes with
increasing entanglement. Furthermore, we theoretically show that holonomic
phases can directly quantify the amount of quantum correlations between the two
particles. Our results open up a new avenue for observations of holonomic
phenomena in multi-particle entangled quantum systems.Comment: 8 pages, 6 figure
A comparison of operationally determined atmospheric densities from satellite orbit solutions and the exospheric temperature from the Jacchia-Roberts model
Operational orbit determination by the Flight Dynamics Division at the Goddard Space Flight Center has yielded a data base of orbit solutions covering the onset of solar cycle 22. Solutions for nine satellites include an estimated drag adjustment parameter (rho sub 1) determined by the Goddard Trajectory Determination System (GTDS). The rho sub 1 is used to evaluate correlations between density variations and changes in the following: 10.7-centimeter wavelength solar flux (F sub 10.7), the geomagnetic index A sub p, and two exospheric temperatures (T sub c and T sub infinity) adapted from the Jacchia-Roberts atmospheric density model in GTDS. T sub c depends on the daily and 81-day centered mean F sub 10.7; T sub infinity depends on T sub c and the geomagnetic index K sub p values. The highest correlations are between density and T sub infinity. Correlations with T sub c and F sub 10.7 are lower by 9 and 10 percent, respectively. For most cases, correlations with A sub p are considerably lower; however, significant correlations with A sub p were found for some high-inclination, moderate-altitude orbits. Results from this analysis enhance the understanding of the drag model and the accommodation of atmospheric density variations in the operational orbit determination support. The degree of correlation demonstrates the sensitivity of the orbit determination process to drag variations and to the input parameters that characterize aspects of the atmospheric density model. To this extent, the degree of correlation provides a measure of performance for methods of selecting or modeling the thermospheric densities using the solar F sub 10.7 and geomagnetic data as input to the process
HST NICMOS Images of the HH 7/11 Outflow in NGC1333
We present near infrared images in H2 at 2.12um of the HH 7/11 outflow and
its driving source SVS 13 taken with HST NICMOS 2 camera, as well as archival
Ha and [SII] optical images obtained with the WFPC2 camera. The NICMOS high
angular resolution observations confirm the nature of a small scale jet arising
from SVS 13, and resolve a structure in the HH 7 working surface that could
correspond to Mach disk H2 emission. The H2 jet has a length of 430 AU (at a
distance of 350 pc), an aspect ratio of 2.2 and morphologically resembles the
well known DG Tau optical micro-jet. The kinematical age of the jet (approx. 10
yr) coincides with the time since the last outburst from SVS 13. If we
interpret the observed H2 flux density with molecular shock models of 20-30
km/s, then the jet has a density as high as 1.e+5 cc. The presence of this
small jet warns that contamination by H2 emission from an outflow in studies
searching for H2 in circumstellar disks is possible. At the working surface,
the smooth H2 morphology of the HH 7 bowshock indicates that the magnetic field
is strong, playing a major role in stabilizing this structure. The H2 flux
density of the Mach disk, when compared with that of the bowshock, suggests
that its emission is produced by molecular shocks of less than 20 km/s. The
WFPC2 optical images display several of the global features already inferred
from groundbased observations, like the filamentary structure in HH 8 and HH
10, which suggests a strong interaction of the outflow with its cavity. The H2
jet is not detected in {SII] or Ha, however, there is a small clump at approx.
5'' NE of SVS 13 that could be depicting the presence either of a different
outburst event or the north edge of the outflow cavity.Comment: 13 pages, 5 figures (JPEGs
What and how: doing good research with young people, digital intimacies, and relationships and sex education
© 2020, © 2020 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. As part of a project funded by the Wellcome Trust, we held a one-day symposium, bringing together researchers, practitioners, and policymakers, to discuss priorities for research on relationships and sex education (RSE) in a world where young people increasingly live, experience, and augment their relationships (whether sexual or not) within digital spaces. The introduction of statutory RSE in schools in England highlights the need to focus on improving understandings of young people and digital intimacies for its own sake, and to inform the development of learning resources. We call for more research that puts young people at its centre; foregrounds inclusivity; and allows a nuanced discussion of pleasures, harms, risks, and rewards, which can be used by those working with young people and those developing policy. Generating such research is likely to be facilitated by participation, collaboration, and communication with beneficiaries, between disciplines and across sectors. Taking such an approach, academic researchers, practitioners, and policymakers agree that we need a better understanding of RSE’s place in lifelong learning, which seeks to understand the needs of particular groups, is concerned with non-sexual relationships, and does not see digital intimacies as disconnected from offline everyday ‘reality’
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