58,486 research outputs found
Acoustic vibration test detects intermittent electrical discontinuities
Nondestructive test method detects faulty electrical connections in inaccessible or hidden portions of electronic harness assemblies and connectors. Method employs readily available commercial equipment
An Algebraic Duality Theory for Multiplicative Unitaries
Multiplicative Unitaries are described in terms of a pair of commuting shifts
of relative depth two. They can be generated from ambidextrous Hilbert spaces
in a tensor C*-category. The algebraic analogue of the Takesaki-Tatsuuma
Duality Theorem characterizes abstractly C*-algebras acted on by unital
endomorphisms that are intrinsically related to the regular representation of a
multiplicative unitary. The relevant C*-algebras turn out to be simple and
indeed separable if the corresponding multiplicative unitaries act on a
separable Hilbert space. A categorical analogue provides internal
characterizations of minimal representation categories of a multiplicative
unitary. Endomorphisms of the Cuntz algebra related algebraically to the
grading are discussed as is the notion of braided symmetry in a tensor
C*-category.Comment: one reference adde
The dependence on morphology of the gas content in galactic disks
The classification S0 was introduced by Hubble to serve as a description of galaxies whose morphological characteristics seemed to lie between the disk-dominated spirals and the spheroidal elliptical systems. Since then there has been extensive discussion as to whether this classification sequence is also an evolutionary sequence. Many studies have focussed on a particular feature such as the luminosity profile, the bulge-to-disk ratio, or the nature of the interstellar matter, but the question of the evolution remains contentious. Equally contentious is the question of the classification itself. For systems with well-developed disks there usually is no problem. Many spheroidal systems also are unambiguously classified as ellipticals in most catalogs. However, there are a number of early systems which have been reclassified following review using improved optical material. For example, Eder et al. (AJ, 102, 572, 1991) found that many of the S0 galaxies which are rich in neutral hydrogen have faint spiral features. The confusion about classification propagates into the discussion of the properties of early-type systems. Attempts to put the classification system on a quantitative basis have in general been unsuccessful. Recently Sandage (private communication) has reviewed the classification of early systems and has defined a set of sub-classes for these objects. The S0 galaxies are divided into three groups, depending on the prominence of the disk. There are six subdivisions of Sa galaxies, depending upon the relative prominence of knots and other arm-like characteristics. We have explored the total gas content in these objects to see if there is a dependence on the galaxy morphology, as denoted by these new subclasses
The in-vacuo torque performance of dry-lubricated ball bearings at cryogenic temperatures
The performance of dry-lubricated, angular contact ball bearings in vacuum at a temperature of 20 degrees K has been investigated, and is compared with the in-vacuo performance at room temperatures. Bearings were lubricated using dry-lubricant techniques which have been previously established for space applications involving operations at or near room temperature. Comparative tests were undertaken using three lubricants: molybdenum disulphide, lead, and PTFE. Results obtained using the three lubricants are presented
A Remark on Quantum Group Actions and Nuclearity
Let H be a compact quantum group with faithful Haar measure and bounded
counit. If H acts on a C*-algebra A, we show that A is nuclear if and only if
its fixed-point subalgebra is nuclear. As a consequence H is a nuclear
C*-algebra.Comment: 12 pages, LateX 2
Evaluation of Two Systems Used to Extract Alfalfa Weevil Larvae (Coleoptera: Curculionidae) from Alfalfa Samples
A modified Berlese funnel system was developed to extract alfalfa weevil larvae (Hypera postica) from quadrats 30.5 cm on a side. Data from this system were comp.wed with simultaneous data from a hand sorting extraction system. In most instances, the modified Berlese system was as efficient as the hand sorting method and the number of man hours required to process samples by hand was far greater than that required by the Berlese system
A Laboratory Infection of Alfalfa Weevil, \u3ci\u3eHypera Postica\u3c/i\u3e (Coleoptera: Curculionidae), Larvae With the Fungal Pathogen \u3ci\u3eZoophthora Phytonomi\u3c/i\u3e (Zygomycetes: Entomophthoraceae)
Larvae of the alfalfa weevil, Hypera postica, were infected by an in vitro colony of Zoophthora phytonomi. Two spore types (infective conidia, and resting spores) were produced from infection trials. The spore type produced may be influenced by the physiological state of the larvae. Trials using field collected larvae which would produce diapausing adults formed both conidia and resting spores. Trials using larvae from a nondiapausing colony, however, formed only resting spores
- …