5,285 research outputs found
A Human Information Behavior Approach to a Philosophy of Information
This paper outlines the relation between philosophy of information
(PI) and human information behavior (HIB). In this paper, we first
briefly outline the basic constructs and approaches of PI and HIB. We argue
that a strong relation exists between PI and HIB, as both are exploring
the concept of information and premise information as a fundamental
concept basic to human existence. We then exemplify that a heuristic
approach to PI integrates the HIB view of information as a cognitive human-
initiated process by presenting a specific cognitive architecture for
information initiation based on modular notion from HIB/evolutionary
psychology and the vacuum mechanism from PI.published or submitted for publicatio
The myocardial and coronary histopathology and pathogenesis of hypoplastic left heart syndrome
AbstractHypoplastic left heart syndrome has the greatest mortality rate among all CHDs and without palliation is uniformly fatal. Despite noble efforts, the aetiology of this syndrome is unknown and a cure remains elusive. The genetic and anatomic heterogeneity of hypoplastic left heart syndrome supports a rethinking of old hypotheses and warrants further investigation into the histological and vascular variations recognised with this syndrome. In an effort to elucidate the pathogenesis of hypoplastic left heart syndrome, this review will focus on its unique myocardial and coronary pathology as well as evaluate the association of hypoplastic left heart syndrome with the endocardial fibroelastosis reaction.</jats:p
Preliminary Report of Standing Crop and Rates of Harvest in Lake Fort Smith, Arkansas:1957 Through 1958
Parting: The Aftermath of Separation and Divorce / Recycling the Family: Remarriage after Divorce
Selective CVD Growth of Diamond Crystals on Tungsten
Typical field emitters consist of sharp metal tips which usually have a short life due to erosion and contamination. To improve the performance of regular field emitters, diamond can be placed on the emitter tip. This is done by selectively growing diamond on tungsten tips using chemical vapor deposition (CVD) processing. Diamond exhibits negative electron affinity, so that electrons will be emitted by properly biasing the tip.
To obtain single crystal growth right at the tip, a cantilever controlled nucleation method was developed which worked better than other methods. Surface preparation was also important to the growth process. An oxide layer was used to prevent random diamond growth and to prevent the tungsten from becoming brittle. Crystal characteristics were observed using scanning electron microscopy (SEM) and Raman spectroscopy. Size, quality and orientation of the diamond crystals varied with CVD process parameters. Higher temperatures and pressures yielded larger crystals with generally better quality, The (111) orientation was predominant at 40 Torr and higher temperatures, while the (100) orientation was favored at 60 Torr and higher temperatures. Higher amounts of methane yielded larger crystals, but the quality of the diamond was poor. Optimum conditions were determined to fabricate a diamond tip on tungsten
Electron stimulated desorption of hydronium ions from chromium oxide surfaces
The mass spectral peak observed at 19 amu in residual gas analyzers at very high (\u3c10-6 Torr) and ultrahigh vacuum (\u3c10 -9 Torr) has often been attributed to fluorine. Using Fourier Transform Mass Spectrometry, the hydronium ion, H3O+, has been fully resolved from F+ and its correlation to water vapor concentration was determined to be linear as expected for a gas phase process. The comparison of the mass 19 signals for a conventional quadrupole mass spectrometer and a Fourier transform mass spectrometer on the same vacuum chamber indicated hydronium was the source of mass 19.;The partial pressures of H2O in the very high vacuum range and higher suggest there is sufficient H2O density for the hydronium ions to form through ion-molecule interactions because hydronium formation was found to directly correlate with the H2O partial pressure. However, in a QMS at UHV, formation of H3O+ appears to occur principally by electron stimulated desorption (ESD). Introducing hydrogen into the system from 1 Langmuir exposure to saturation (1 x 10-6 Torr for 8 hours) increased the H3O + ESD yield detected by the QMS by as much as a factor of 10. The initial hydronium ESD cross section from a hydrogen saturated grid was estimated to be sigma ∼ 1 x 10-19, cm2.;TOF-SIMS sputter yields from the stainless steel grid of a quadrupole mass spectrometer also showed small signals of H3O+, as well as its constituents (H+, O+ and OH) and a small amount of fluorine as F-, but no F+ or F+ complexes (HF+, etc.). Using x-ray photoelectron spectroscopy, a small amount (0.4%) of fluorine was found in the surface of stainless steel. Electron bombardment reduces the fluorine bound in surface complexes, but not metal halides found below the surface. However, heating the sample eliminated the F 1s signal entirely, indicating that fluorine is not likely to be the source of mass 19 in residual gas analysis. Also, changes in the spectral shoulders on the O 1s and Cr 2P3/2 peaks show that hydrogen dosing stainless steel and chromium increases the amount of hydroxides at the surface, while heating and electron bombardment reduce them
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