30,567 research outputs found
Thin Films of 3He -- Implications on the Identification of 3 He -A
Recently the identification of 3He-A with the axial state has been
questioned. It is suggested that the A-phase can actually be in the axiplanar
state. We point out in the present paper that experiments in a film geometry
may be useful to distinguish the above two possibilities. In particular a
second order phase transition between an axial and an axiplanar state would
occur as a function of thickness or temperature.Comment: 3 pages, no figures latex- revtex aps accepted by J. of Low
Temperature Physic
Research Reports: 1983 NASA/ASEE Summer Faculty Fellowship Program
Thirty-five technical reports contain results of investigations in information and electronic systems; materials and processing; systems dynamics; structures and propulsion; and space sciences. Ecology at KSC, satellite de-spin, and the X-ray source monitor were also studied
Research reports: 1985 NASA/ASEE Summer Faculty Fellowship Program
A compilation of 40 technical reports on research conducted by participants in the 1985 NASA/ASEE Summer Faculty Fellowship Program at Marshall Space Flight Center (MSFC) is given. Weibull density functions, reliability analysis, directional solidification, space stations, jet stream, fracture mechanics, composite materials, orbital maneuvering vehicles, stellar winds and gamma ray bursts are among the topics discussed
Research Reports: 1984 NASA/ASEE Summer Faculty Fellowship Program
A NASA/ASEE Summer Faulty Fellowship Program was conducted at the Marshall Space Flight Center (MSFC). The basic objectives of the programs are: (1) to further the professional knowledge of qualified engineering and science faculty members; (2) to stimulate an exchange of ideas between participants and NASA; (3) to enrich and refresh the research and teaching activities of the participants' institutions; and (4) to contribute to the research objectives of the NASA Centers. The Faculty Fellows spent ten weeks at MSFC engaged in a research project compatible with their interests and background and worked in collaboration with a NASA/MSFC colleague. This document is a compilation of Fellows' reports on their research during the summer of 1984. Topics covered include: (1) data base management; (2) computational fluid dynamics; (3) space debris; (4) X-ray gratings; (5) atomic oxygen exposure; (6) protective coatings for SSME; (7) cryogenics; (8) thermal analysis measurements; (9) solar wind modelling; and (10) binary systems
Project for the analysis of technology transfer Quarterly report, 1 Oct. - 31 Dec. 1969
Analysis of Tech Brief-Technical Support Package progra
Principles of Control for Decoherence-Free Subsystems
Decoherence-Free Subsystems (DFS) are a powerful means of protecting quantum
information against noise with known symmetry properties. Although Hamiltonians
theoretically exist that can implement a universal set of logic gates on DFS
encoded qubits without ever leaving the protected subsystem, the natural
Hamiltonians that are available in specific implementations do not necessarily
have this property. Here we describe some of the principles that can be used in
such cases to operate on encoded qubits without losing the protection offered
by the DFS. In particular, we show how dynamical decoupling can be used to
control decoherence during the unavoidable excursions outside of the DFS. By
means of cumulant expansions, we show how the fidelity of quantum gates
implemented by this method on a simple two-physical-qubit DFS depends on the
correlation time of the noise responsible for decoherence. We further show by
means of numerical simulations how our previously introduced "strongly
modulating pulses" for NMR quantum information processing can permit
high-fidelity operations on multiple DFS encoded qubits in practice, provided
that the rate at which the system can be modulated is fast compared to the
correlation time of the noise. The principles thereby illustrated are expected
to be broadly applicable to many implementations of quantum information
processors based on DFS encoded qubits.Comment: 12 pages, 7 figure
Recommended from our members
The role of right and left parietal lobes in the conceptual processing of numbers
Neuropsychological and functional imaging studies have associated the conceptual processing of numbers with bilateral parietal regions (including intraparietal sulcus). However, the processes driving these effects remain unclear because both left and right posterior parietal regions are activated by many other conceptual, perceptual, attention, and response-selection processes. To dissociate parietal activation that is number-selective from parietal activation related to other stimulus or response-selection processes, we used fMRI to compare numbers and object names during exactly the same conceptual and perceptual tasks while factoring out activations correlating with response times. We found that right parietal activation was higher for conceptual decisions on numbers relative to the same tasks on object names, even when response time effects were fully factored out. In contrast, left parietal activation for numbers was equally involved in conceptual processing of object names. We suggest that left parietal activation for numbers reflects a range of processes, including the retrieval of learnt facts that are also involved in conceptual decisions on object names. In contrast, number selectivity in right parietal cortex reflects processes that are more involved in conceptual decisions on numbers than object names. Our results generate a new set of hypotheses that have implications for the design of future behavioral and functional imaging studies of patients with left and right parietal damage
The Planetary Nebula System and Dynamics in the Outer Halo of NGC 5128
The halos of elliptical galaxies are faint and difficult to explore, but they
contain vital clues to both structure and formation. We present the results of
an imaging and spectroscopic survey for planetary nebulae (PNe) in the nearby
elliptical NGC 5128. We extend the work of Hui et al.(1995) well into the halo
of the galaxy--out to distances of 100 and 50 kpc along the major and minor
axes. We now know of 1141 PNe in NGC 5128, 780 of which are confirmed. Of these
780 PNe, 349 are new from this survey, and 148 are at radii beyond 20 kpc. PNe
exist at distances up to 80 kpc (~15 r_e), showing that the stellar halo
extends to the limit of our data. This study represents by far the largest
kinematic study of an elliptical galaxy to date, both in the number of velocity
tracers and in radial extent. We confirm the large rotation of the PNe along
the major axis, and show that it extends in a disk-like feature into the halo.
The rotation curve of the stars flattens at ~100 km/s with V/sigma between 1
and 1.5, and with the velocity dispersion of the PNe falling gradually at
larger radii. The two-dimensional velocity field exhibits a zero-velocity
contour with a pronounced twist, showing that the galaxy potential is likely
triaxial in shape, tending toward prolate. The total dynamical mass of the
galaxy within 80 kpc is ~5 x 10^{11} M_sun, with M/L_B ~ 13. This mass-to-light
ratio is much lower than what is typically expected for elliptical galaxies.Comment: 21 pages, 13 figures (figures 3-8 best viewed in color), accepted for
publication in the Astrophysical Journa
The importance of acknowledgement of emotions in routine patient psychological assessment:The example of the dental setting
This work was funded by the Chief Scientist Office, Scotland under their Clinical Academic Fellowship Scheme (grant number: CAF/07/02).Objective: To investigate, by means of a conceptual model, the effect of dental staff engaging with their patients who share their level of dental anxiety in a short screening questionnaire. Methods : Three consecutive studies based in the UK primary dental care services were conducted. Each study adopted a randomised group design to focus on the possible influence on patient state anxiety of the dentist becoming aware of their patients' dental anxiety from the self-reports of the Modified Dental Anxiety Scale (MDAS). Results : A consistent finding in the first two studies was that the presentation of MDAS score sheet to the dentist was effective in reducing patient state anxiety when leaving the surgery. The third study provided supportive evidence that a more permanent anxiolytic effect of the presentation of the MDAS to the dentist was associated with the dentist responding openly to their patient about the fears expressed. Conclusion: The active engagement of dental staff in the formal presentation of dental anxiety screening confers a reliable benefit to dentally anxious patients. Clinical implications: Anxiety assessments in clinical service may give patients significant relief when staff acknowledge and engage patients when presented with their self-reported ratings.PostprintPeer reviewe
Magnetic groundstate and Fermi surface of bcc Eu
Using spin-spiral technique within the full potential linearized
augmented-plane-waves (LAPW) electronic structure method we investigate the
magnon spectrum and N\'eel temperature of bcc Eu. Ground state corresponding to
an incommensurate spin-spiral is obtained in agreement with experiment and
previous calculations. We demonstrate that the magnetic coupling is primarily
through the intra-atomic and exchange and
Ruderman-Kittel-Kasuya-Yosida mechanism. We show that the existence of this
spin-spiral is closely connected to a nesting feature of the Fermi surface
which was not noticed before.Comment: 6 pages 8 figure
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