6,819 research outputs found
Cold cathode ionization gage has rigid metal housing
Cold cathode ionization gage in a stainless steel housing accurately measures high pressures. The penning effect is used with a high voltage discharge in the presence of a magnetic field for an ion current proportional to the gas pressure in the gage
Optimized maximum-confidence discrimination of N mixed quantum states and application to symmetric states
We study an optimized measurement which discriminates N mixed quantum states
occurring with given prior robabilities. The measurement yields the maximum
achievable confidence for each of the N conclusive outcomes, thereby keeping
the overall probability of inconclusive outcomes as small as possible. It
corresponds to optimum unambiguous discrimination when for each outcome the
confidence is equal to unity. Necessary and sufficient optimality conditions
are derived and general properties of the optimum measurement are obtained. The
results are applied to the optimized maximum-confidence discrimination of N
equiprobable symmetric mixed states. Analytical solutions are presented for a
number of examples, including the discrimination of N symmetric pure states
spanning a d-dimensional Hilbert space (d \leq N) and the discrimination of N
symmetric mixed qubit states.Comment: minor corrections, final versio
Linear resolutions of powers and products
The goal of this paper is to present examples of families of homogeneous
ideals in the polynomial ring over a field that satisfy the following
condition: every product of ideals of the family has a linear free resolution.
As we will see, this condition is strongly correlated to good primary
decompositions of the products and good homological and arithmetical properties
of the associated multi-Rees algebras. The following families will be discussed
in detail: polymatroidal ideals, ideals generated by linear forms and Borel
fixed ideals of maximal minors. The main tools are Gr\"obner bases and Sagbi
deformation
Diode pumped Nd:YAG laser development
A low power Nd:YAG laser was constructed which employs GaAs injection lasers as a pump source. Power outputs of 125 mW TEM CW with the rod at 250 K and the pump at 180 K were achieved for 45 W input power to the pump source. Operation of the laser, with array and laser at a common heat sink temperature of 250 K, was inhibited by difficulties in constructing long-life GaAs LOC laser arrays. Tests verified pumping with output power of 20 to 30 mW with rod and pump at 250 K. Although life tests with single LOC GaAs diodes were somewhat encouraging (with single diodes operating as long as 9000 hours without degradation), failures of single diodes in arrays continue to occur, and 50 percent power is lost in a few hundred hours at 1 percent duty factor. Because of the large recent advances in the state of the art of CW room temperature AlGaAs diodes, their demonstrated lifetimes of greater than 5,000 hours, and their inherent advantages for this task, it is recommended that these sources be used for further CW YAG injection laser pumping work
Thermoplasmonics: Quantifying plasmonic heating in single nanowires
Plasmonic absorption of light can lead to significant local heating in
metallic nanostructures, an effect that defines the sub-field of
thermoplasmonics and has been leveraged in diverse applications from biomedical
technology to optoelectronics. Quantitatively characterizing the resulting
local temperature increase can be very challenging in isolated nanostructures.
By measuring the optically-induced change in resistance of metal nanowires with
a transverse plasmon mode, we quantitatively determine the temperature increase
in single nanostructures, with the dependence on incident polarization clearly
revealing the plasmonic heating mechanism. Computational modeling explains the
resonant and nonresonant contributions to the optical heating and the dominant
pathways for thermal transport. These results, obtained by combining electronic
and optical measurements, place a bound on the role of optical heating in prior
experiments, and suggest design guidelines for engineered structures meant to
leverage such effects.Comment: 17 pages, 4 figures + 3 pages supporting materia
Lunar lander mass spectrometer Final report
Sputter ion source for lunar lander mass spectromete
THE BIOMECHANICS OF DYNAMICALLY CONTRACTING SKELETAL MUSCLE
History-dependent properties of skeletal muscle contraction have been observed for half a century. The origin of these properties has been the focus of intense scientific debate. One of these properties, the force enhancement following muscle stretching, has been associated with the development of sarcomere length non-uniformities. Here, we show that this long-held belief is likely not correct. We show this by rejecting three specific hypotheses that arise directly from the sarcomere length non-uniformity theory. We further found novel evidence that force enhancement is likely associated with the development of extra tension in a passive, molecular spring, such as titin or nebulin. This finding has a profound impact on the theory of force enhancement following muscle stretching, and has direct implications for muscle injuries occurring during active muscle stretching
Development and fabrication of bismaleimide-graphite composites
The successful fabrication of high temperature resistant composites depends mainly on the processability of the resin binder matrix. For two new bismaleimide type resins the processing of graphite fabric prepregs to composites is described. One resin coded M 751 has to be processed from N-Methylpyrrolidone, the other resin evaluated is a so-called hot melt solvent-less system. Commercial T300/3000 Graphite fabrics were used as reinforcement. The M 751 - Resin is a press grade material and laminates are therefore moulded in high pressure conditions (400 N/sq cm). The solvent-less resin system H 795 is an autoclave grade material and can be cured at 40 N/sq cm. The cure cycles for both the press grade and the autoclave grade material (Fiberite W 143 fabric prepregs) are provided and the mechanical properties of laminates at low (23 C) and high (232 C) temperatures were measured. For comparison, the neat resin flexural properties are also presented. The water absorption for the neat resins and the graphite fabric laminates after a 1000 hour period was evaluated
Distinguishing mixed quantum states: Minimum-error discrimination versus optimum unambiguous discrimination
We consider two different optimized measurement strategies for the
discrimination of nonorthogonal quantum states. The first is conclusive
discrimination with a minimum probability of inferring an erroneous result, and
the second is unambiguous, i. e. error-free, discrimination with a minimum
probability of getting an inconclusive outcome, where the measurement fails to
give a definite answer. For distinguishing between two mixed quantum states, we
investigate the relation between the minimum error probability achievable in
conclusive discrimination, and the minimum failure probability that can be
reached in unambiguous discrimination of the same two states. The latter turns
out to be at least twice as large as the former for any two given states. As an
example, we treat the case that the state of the quantum system is known to be,
with arbitrary prior probability, either a given pure state, or a uniform
statistical mixture of any number of mutually orthogonal states. For this case
we derive an analytical result for the minimum probability of error and perform
a quantitative comparison to the minimum failure probability.Comment: Replaced by final version, accepted for publication in Phys. Rev. A.
Revtex4, 6 pages, 3 figure
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