Special treatment reduces helium permeation of glass in vacuum systems

Internal surfaces of the glass component of a vacuum system are exposed to cesium in gaseous form to reduce helium permeation. The cesium gas is derived from decomposition of cesium nitrate through heating. Several minutes of exposure of the internal surfaces of the glass vessel are sufficient to complete the treatment

Extreme vacuum technology including cryosorption, diffusion pump and pressure calibration studies Summary technical report, 1 Feb. 1965 - 1 Mar. 1966

Cryosorption, diffusion pump, and pressure calibration studies in extreme vacuum science and technology application progra

Extreme vacuum technology including cryosorption, diffusion pump and pressure calibration studies Quarterly status report no. 8, 1 May - 1 Aug. 1965

Cryosorption, diffusion pump, and low pressure calibration studies on Penning gauge and cold cathode magnetro

Study of low pressure application of the orbitron

Evaluation of low pressure performance of orbitron ionization gaug

Optical/Infrared Observations of the Anomalous X-ray Pulsar 1E 1048.1-5937 During Its 2007 X-Ray Flare

We report on optical and infrared observations of the anomalous X-ray pulsar (AXP) 1E 1048.1-5937, made during its ongoing X-ray flare which started in 2007 March. We detected the source in the optical I and near-infrared Ks bands in two ground-based observations and obtained deep flux upper limits from four observations, including one with the Spitzer Space Telescope at 4.5 and 8.0 microns. The detections indicate that the source was approximately 1.3--1.6 magnitudes brighter than in 2003--2006, when it was at the tail of a previous similar X-ray flare. Similar related flux variations have been seen in two other AXPs during their X-ray outbursts, suggesting common behavior for large X-ray flux variation events in AXPs. The Spitzer flux 1E 1048.1-5937 limits are sufficiently deep that we can exclude mid-infrared emission similar to that from the AXP 4U 0142+61, which has been interpreted as arising from a dust disk around the AXP. The optical/near-infrared emission from probably has a magnetospheric origin. The similarity in the flux spectra of 4U 0142+61 and 1E 1048.1-5937 challenges the dust disk model proposed for the latter.Comment: 5 pages, 1 figure, accepted by Ap

Extreme vacuum technology developments

Ultrahigh vacuum environments technology development

Calibrated Sub-Bundles in Non-Compact Manifolds of Special Holonomy

This paper is a continuation of math.DG/0408005. We first construct special Lagrangian submanifolds of the Ricci-flat Stenzel metric (of holonomy SU(n)) on the cotangent bundle of S^n by looking at the conormal bundle of appropriate submanifolds of S^n. We find that the condition for the conormal bundle to be special Lagrangian is the same as that discovered by Harvey-Lawson for submanifolds in R^n in their pioneering paper. We also construct calibrated submanifolds in complete metrics with special holonomy G_2 and Spin(7) discovered by Bryant and Salamon on the total spaces of appropriate bundles over self-dual Einstein four manifolds. The submanifolds are constructed as certain subbundles over immersed surfaces. We show that this construction requires the surface to be minimal in the associative and Cayley cases, and to be (properly oriented) real isotropic in the coassociative case. We also make some remarks about using these constructions as a possible local model for the intersection of compact calibrated submanifolds in a compact manifold with special holonomy.Comment: 20 pages; for Revised Version: Minor cosmetic changes, some paragraphs rewritten for improved clarit

The importance of regional variation in the analysis of urbanization-agriculture interactions

La recherche géographique sur l'agriculture dans les régions métropolitaines a été orientée vers l'étude des changements agricoles influencés par l'urbanisation. D'autres processus d'évolution et les facteurs liés aux variations de l'environnement régional ont été négligés. Certaines recherches récentes faisant apparaître l'importance de l'environnement régional à des échelles géographiques différentes sont décrites. Premièrement, une typologie de régions basées sur les régions métropolitaines de recensement du Canada est présentée. Certains groupes de la typologie ont connu des changements agricoles importants qui ne s'expliquent pas par les pressions du développement métropolitain. Des différences régionales dans l'environnement agricole apportent des explications partielles. Deuxièmement, pour la région de Montréal des variables agricoles (de 1961 à 1971) sont analysées avec une analyse factorielle. Les résultats sont interprétés en termes a) de l'urbanisation et b) des variations dans l'environnement à l'intérieur de la région. En dernier lieu, pour une municipalité située près de Toronto, une analyse est faite de la répartition géographique du morcellement des parcelles cadastrales. Une fois encore, des liens sont apparents avec certaines caractéristiques de l'environnement. La conclusion est que les changements agricoles ne sont pas homogènes, soit entre régions, soit à l'intérieur d'une même région, et que l'explication devrait être formulée aussi bien en termes de la variation de l'environnement régional qu'en termes des influences métropolitaines.Research into agriculture in metropolitan regions has concentrated on urban-induced agricultural land use changes. Other processes of change and factors related to variations in the regional environment have been neglected. Some recent research is reported here which points to the importance of the regional environment at a variety of scale levels. First, a typology of regions based on Census Metropolitan Areas in Canada is developed. Some groups of regions experienced significant agricultural changes quite unrelated to metropolitan development pressures. Regional differences in the agricultural environment are suggested as partial explanations. Second, for the Montréal region, a series of agricultural variables (1961 to 1971) are analysed using factor analysis. Results are interpreted in the light of a) urbanisation forces and b) internal variation in the regional environment. Finally, for a township near Toronto, an investigation is made of the distribution of severances. Once more, relationships appear with certain physical characteristics. The paper concludes that agricultural change is not uniform either between regions or within regions, and that part of the variation is related to differences in the "regional" environment and part to metropolitan forces

Automatic extraction of learner errors in ESL sentences using linguistically enhanced alignments

We propose a new method of automatically extracting learner errors from parallel English as a Second Language (ESL) sentences in an effort to regularise annotation formats and reduce inconsistencies. Specifically, given an original and corrected sentence, our method first uses a linguistically enhanced alignment algorithm to determine the most likely mappings between tokens, and secondly employs a rule-based function to decide which alignments should be merged. Our method beats all previous approaches on the tested datasets, achieving state-of-the-art results for automatic error extraction.This is the author accepted manuscript. It is currently under an indefinite embargo pending publication by the Association for Computational Linguistics