8,741 research outputs found
Parkes-CDSCC telemetry array: Equipment design
A unique combination of Deep Space Network (DSN) and non-DSN facilities in Australia provided enhanced data return from the Voyager spacecraft as it encountered the planet Uranus. Many of the key elements are duplicated from Voyager's encounters with Jupiter and Saturn. Some are unique extensions of that technology
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Emerging Translational Opportunities in Comparative Oncology With Companion Canine Cancers: Radiation Oncology.
It is estimated that more than 6 million pet dogs are diagnosed with cancer annually in the USA. Both primary care and specialist veterinarians are frequently called upon to provide clinical care that improves the quality and/or quantity of life for affected animals. Because these cancers develop spontaneously in animals that often share the same environment as their owners, have intact immune systems and are of similar size to humans, and because the diagnostic tests and treatments for these cancers are similar to those used for management of human cancers, canine cancer provides an opportunity for research that simultaneously helps improve both canine and human health care. This is especially true in the field of radiation oncology, for which there is a rich and continually evolving history of learning from the careful study of pet dogs undergoing various forms of radiotherapy. The purpose of this review article is to inform readers of the potential utility and limitations of using dogs in that manner; the peer-reviewed literature will be critically reviewed, and current research efforts will be discussed. The article concludes with a look toward promising future directions and applications of this pet dog "model.
New geometries for high spatial resolution hall probes
The Hall response function of symmetric and asymmetric planar Hall effect
devices is investigated by scanning a magnetized tip above a sensor surface
while simultaneously recording the topography and the Hall voltage. Hall sensor
geometries are tailored using a Focused Ion Beam, in standard symmetric and new
asymmetric geometries. With this technique we are able to reduce a single
voltage probe to a narrow constriction 20 times smaller than the other device
dimensions. We show that the response function is peaked above the
constriction, in agreement with numerical simulations. The results suggest a
new way to pattern Hall sensors for enhanced spatial resolution.Comment: 12 pages, 5 figures, submitted to Journal of Applied Physic
Interagency telemetry arraying for Voyager-Neptune encounter
The reception capability of the Deep Space Network (DSN) has been improved over the years by increasing both the size and number of antennas at each complex to meet spacecraft-support requirements. However, even more aperture was required for the final planetary encounters of the Voyager 2 spacecraft. This need was met by arraying one radio astronomy observatory with the DSN complex in the United States and another with the complex in Australia. Following a review of augmentation for the Uranus encounter, both the preparation at the National Radio Astronomy (NRAO) Very Large Array (VLA) and the Neptune encounter results for the Parkes-Canberra and VLA-Goldstone arrays are presented
A new nickel-base wrought superalloy for applications up to 1033 K (1400 F)
Alloy was melted from high purity raw materials and cast ingots extruded at 1422 K. Material was hot rolled to 0.013 m diameter bar stock. Partial solution heat-treatment followed by aging produced structure of fine gamma prime precipitate reinforcing gamma matrix containing coarser blocky gamma prime particles. Alloy can be processed by powder metallurgy
Pre- and Post-selection paradoxes and contextuality in quantum mechanics
Many seemingly paradoxical effects are known in the predictions for outcomes
of intermediate measurements made on pre- and post-selected quantum systems.
Despite appearances, these effects do not demonstrate the impossibility of a
noncontextual hidden variable theory, since an explanation in terms of
measurement-disturbance is possible. Nonetheless, we show that for every
paradoxical effect wherein all the pre- and post- selected probabilities are 0
or 1 and the pre- and post-selected states are nonorthogonal, there is an
associated proof of contextuality. This proof is obtained by considering all
the measurements involved in the paradoxical effect -- the pre-selection, the
post-selection, and the alternative possible intermediate measurements -- as
alternative possible measurements at a single time.Comment: 5 pages, 1 figure. Submitted to Phys. Rev. Lett. v2.0 revised in the
light of referee comments, results unchange
Critical Currents of Josephson-Coupled Wire Arrays
We calculate the current-voltage characteristics and critical current
I_c^{array} of an array of Josephson-coupled superconducting wires. The array
has two layers, each consisting of a set of parallel wires, arranged at right
angles, such that an overdamped resistively-shunted junction forms wherever two
wires cross. A uniform magnetic field equal to f flux quanta per plaquette is
applied perpendicular to the layers. If f = p/q, where p and q are mutually
prime integers, I_c^{array}(f) is found to have sharp peaks when q is a small
integer. To an excellent approximation, it is found in a square array of n^2
plaquettes, that I_c^{array}(f) \propto (n/q)^{1/2} for sufficiently large n.
This result is interpreted in terms of the commensurability between the array
and the assumed q \times q unit cell of the ground state vortex lattice.Comment: 4 pages, 4 figure
Optimal Entanglement Enhancement for Mixed States
We consider the actions of protocols involving local quantum operations and
classical communication (LQCC) on a single system consisting of two separated
qubits. We give a complete description of the orbits of the space of states
under LQCC and characterise the representatives with maximal entanglement of
formation. We thus obtain a LQCC entanglement concentration protocol for a
single given state (pure or mixed) of two qubits which is optimal in the sense
that the protocol produces, with non-zero probability, a state of maximal
possible entanglement of formation. This defines a new entanglement measure,
the maximum extractable entanglement.Comment: Final version: to appear in Phys. Rev. Let
New nickel-base wrought superalloy with applications up to 1253 K (1800 F)
Alloy possesses combination of high tensile strength at low and intermediate temperatures to 1033 K with good rupture strength at high temperatures to 1255 K. Alloy has promise for turbine disk application in future gas turbine engines and for wrought integrally bladed turbine wheel; thickness and weight of disk portion of wheel could be reduced
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