198,027 research outputs found
Calibrating pressure switch
A pressure switch assembly comprising a body portion and a switch mechanism having a contact element operable between opposite limit positions is described. A diaphragm chamber is provided in the body portion which mounts therein a system diaphragm and a calibration diaphragm which are of generally the same configuration and having outer faces conforming to the inner and outer walls of the diaphragm chamber. The space between the inner faces of the diaphragms defines a first chamber section and the space between the outer face of one of the diaphragms and the outer wall of the diaphragm chamber defines a second chamber section. The body portion includes a system pressure port communicating with one of the chamber sections and a calibration pressure port communicating with the other chamber section. An actuator connected to one of the diaphragms and the contact element of the switch operates upon pressure change in the diaphragm sections to move said contact element between limit positions
On Asymptotic Assouad-Nagata Dimension
For a large class of metric space X including discrete groups we prove that
the asymptotic Assouad-Nagata dimension AN-asdim X of X coincides with the
covering dimension of the Higson corona of X with respect to
the sublinear coarse structure on X. Then we apply this fact to prove the
equality AN-asdim(X x R) = AN-asdim X + 1. We note that the similar equality
for Gromov's asymptotic dimension asdim generally fails to hold [Dr3].
Additionally we construct an injective map from the asymptotic cone without
the basepoint to the sublinear Higson Corona.Comment: 28 pages, 0 figure
A Census of the Carina Nebula -- II. Energy Budget and Global Properties of the Nebulosity
The first paper in this series took a direct census of energy input from the
known OB stars in the Carina Nebula, and in this paper we study the global
properties of the surrounding nebulosity. We find that the total IR luminosity
of Carina is about 1.2E7 Lsun, accounting for only about 50-60% of the known
stellar luminosity from Paper I. Similarly, the ionizing photon luminosity --
(abridged; many important details omitted). Synchronized star formation around
the periphery of Carina provides a strong case that star formation here was
indeed triggered by stellar winds and UV radiation. This second generation
appears to involve a cascade toward preferentially intermediate- and low-mass
stars, but this may soon change when eta Car and its siblings explode. If the
current reservoir of atomic and molecular gas can be tapped at that time,
massive star formation may be rejuvinated around the periphery of Carina much
as if it were a young version of Gould's Belt. Also, when these multiple SNe
occur, the triggered second generation will be pelted repeatedly with SN ejecta
bearing short-lived radioactive nuclides. Carina may therefore represent the
most observable analog to the cradle of our own Solar System.Comment: MNRAS accepted, 14 pages, fig 1 in colo
Analytic measures and Bochner measurability
Let be a -algebra over , and let denote
the Banach space of complex measures. Consider a representation for
acting on . We show that under certain, very weak
hypotheses, that if for a given and all the
map is in , then it follows that the
map is Bochner measurable. The proof is based upon the idea
of the Analytic Radon Nikod\'ym Property.
Straightforward applications yield a new and simpler proof of Forelli's main
result concerning analytic measures ({\it Analytic and quasi-invariant
measures}, Acta Math., {\bf 118} (1967), 33--59)
Satellite personal communications system
Voice channel communication between low power mobile stations dispersed over a large area is provided by a system which includes a geostationary satellite utilizing a large UHF antenna that can receive a transmission from a caller and retransmit it over any one beam of a matrix of narrow beams, so the chosen beam covers an area in which a designated called party is located. A single up-link control channel occupying a narrow frequency band, can be utilized to receive dial up signals from a caller, and another single down link control channel can be utilized to ring up the called party located anywhere within the continental United States. The satellite antenna includes a matrix of feed horns that not only direct the beams in a controlled matrix onto the area of the continental United States, but also permit detection of the region from which the caller's signal is transmitted and the region from which the called party's answer is received, to enable the interconnection of signals received from these two regions. The system is particularly useful for rural areas
Uncovering the Beast: Discovery of Embedded Massive Stellar Clusters in W49A
We present subarcsecond J, H, and Ks images (FWHM ~ 0.5") of an unbiased 5'x
5' (16pc x 16pc) survey of the densest region of the W49 giant molecular cloud.
The observations reveal 4 massive stellar clusters (with stars as massive as
\~120 Msun), the larger (Cluster 1) about 3 pc East of the well known Welch
ring of ultra-compact Hii regions. Cluster 1 is a) extincted by at least Av >
20 mag of foreground (unrelated and local) extinction, b) has more than 30 mag
of internal inhomogeneous visual extinction implying that it is still deeply
buried in its parental molecular cloud, and c) is powering a 6 pc diameter
giant Hii region seen both at the NIR and radio continuum. We also identify the
exciting sources of several UCHii regions. The census of massive stars in W49A
agrees or is slightly overabundant when compared with the number of Lyman
continuum photons derived from radio observations. We argue that although the
formation of the Welch ring could have been triggered by Cluster 1, the entire
W49A starburst region seems to have been multi-seeded instead of resulting from
a coherent trigger.Comment: ApJ Letters accepted. All figures provided as nice resolution
jpeg/gif files. Get full-res version at http://www.eso.org/~jalves/W49A.pd
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