On determinism and well-posedness in multiple time dimensions

We study the initial value problem for the wave equation and the ultrahyperbolic equation for data posed on initial surface of mixed signature (both spacelike and timelike). Under a nonlocal constraint, we show that the Cauchy problem on codimension-one hypersurfaces has global unique solutions in the Sobolev spaces $H^{m}$, thus it is well-posed. In contrast, we show that the initial value problem on higher codimension hypersurfaces is ill-posed, at least when specifying a finite number of derivatives of the data, due to the failure of uniqueness. This is in contrast to a uniqueness result which Courant and Hilbert deduce from Asgeirsson's mean value theorem, for which we give an independent derivation. The proofs use Fourier synthesis and the Holmgren-John uniqueness theorem

Unsupervised Discovery of Phonological Categories through Supervised Learning of Morphological Rules

We describe a case study in the application of {\em symbolic machine learning} techniques for the discovery of linguistic rules and categories. A supervised rule induction algorithm is used to learn to predict the correct diminutive suffix given the phonological representation of Dutch nouns. The system produces rules which are comparable to rules proposed by linguists. Furthermore, in the process of learning this morphological task, the phonemes used are grouped into phonologically relevant categories. We discuss the relevance of our method for linguistics and language technology

Treatment of Chemical Dependency May Reduce Medical Utilization and Costs

Summarizes a study of the impact of chemical dependency treatment on the costs and utilization of medical services -- hospital days, emergency department visits, and outpatient visits. Points to lack of insurance as a barrier to treatment

Multicomponent gas sorption Joule-Thomson refrigeration

The present invention relates to a cryogenic Joule-Thomson refrigeration capable of pumping multicomponent gases with a single stage sorption compressor system. Alternative methods of pumping a multicomponent gas with a single stage compressor are disclosed. In a first embodiment, the sorbent geometry is such that a void is defined near the output of the sorption compressor. When the sorbent is cooled, the sorbent primarily adsorbs the higher boiling point gas such that the lower boiling point gas passes through the sorbent to occupy the void. When the sorbent is heated, the higher boiling point gas is desorbed at high temperature and pressure and thereafter propels the lower boiling point gas out of the sorption compressor. A mixing chamber is provided to remix the constituent gases prior to expansion of the gas through a Joule-Thomson valve. Other methods of pumping a multicomponent gas are disclosed. For example, where the sorbent is porous and the low boiling point gas does not adsorb very well, the pores of the sorbent will act as a void space for the lower boiling point gas. Alternatively, a mixed sorbent may be used where a first sorbent component physically adsorbs the high boiling point gas and where the second sorbent component chemically absorbs the low boiling point gas

Flexible thermal apparatus for mounting of thermoelectric cooler

A flexible heat transfer apparatus used to flexibly connect and thermally couple a thermoelectric cooler to an object to be cooled is disclosed. The flexible heat transfer apparatus consists of a pair of flexible corrugated sheets made from high thermal conductivity materials such as copper, aluminum, gold, or silver. The ridges of the corrugated sheets are oriented perpendicular to one another and bonded sandwich-fashion between three plates to define an upper section and a lower section. The upper section provides X flexure, the lower section provides Y flexure, and both sections together provide Z flexure

CRP ENTRY COSTS ON SOUTHERN MINNESOTA FARMS

Farm Management,

MBT: A Memory-Based Part of Speech Tagger-Generator

We introduce a memory-based approach to part of speech tagging. Memory-based learning is a form of supervised learning based on similarity-based reasoning. The part of speech tag of a word in a particular context is extrapolated from the most similar cases held in memory. Supervised learning approaches are useful when a tagged corpus is available as an example of the desired output of the tagger. Based on such a corpus, the tagger-generator automatically builds a tagger which is able to tag new text the same way, diminishing development time for the construction of a tagger considerably. Memory-based tagging shares this advantage with other statistical or machine learning approaches. Additional advantages specific to a memory-based approach include (i) the relatively small tagged corpus size sufficient for training, (ii) incremental learning, (iii) explanation capabilities, (iv) flexible integration of information in case representations, (v) its non-parametric nature, (vi) reasonably good results on unknown words without morphological analysis, and (vii) fast learning and tagging. In this paper we show that a large-scale application of the memory-based approach is feasible: we obtain a tagging accuracy that is on a par with that of known statistical approaches, and with attractive space and time complexity properties when using {\em IGTree}, a tree-based formalism for indexing and searching huge case bases.} The use of IGTree has as additional advantage that optimal context size for disambiguation is dynamically computed.Comment: 14 pages, 2 Postscript figure

Rubbery acrylic polymer adhesives

This study shows how rubbery acrylic polymer adhesives can be used to adhere rubber substrates to each other. Two substrate rubber compounds were used. A styrene-butadiene copolymer and a styrene-acrylonitrile copolymer. The adhesives were homopolymers based on polybutyl acrylate and poly2-ethyl hexyl acrylate. Two reference standards were used. The first was commercial rubber based, solvent cements. The second was commercial acrylic solution polymers. All experimental work was compared to these standards. An attempt was made to optimize the adhesive components, as well as the adhesive application procedures and curing conditions. A primer coating consisting of polymer, monomer, and catalyst was applied to the rubber prior to the application of the adhesive. This primer coating had to be cured at 375°F for twenty minutes. It was also found to be advantageous to swell the rubber with the monomer to a slight degree before the application of the primer coating and the subsequent bonding of the rubber. The optimal adhesive was applied to the primed surfaces and cured at 375°F for three hours. The bonding strengths generated were 15 lbs./sq. in. for a lap shear sample and 41 oz./in. for a peel strength sample. These values were 1/3 the strength of the commercial rubber solvent cements and twice the strength of the commercial solution acrylic polymers

Ocean shrimp report 1977 season

Statewide Pacific ocean shrimp, Pandalus jordani, landings totaled 15,639,585 lb, more than triple the 1975 record catch of 4,992,233 lb. Record landings were recorded in Area A (Eureka-Crescent City), Area B-2 (Bodega Ray) with catches totaling 13,025,844 and 2,028,607 lb, respectively. Area B-1 (Fort Bragg) landings totaled 585,133 lb and no landings were reported from Area C (Avila-Morro Bay). In Area A the average catch per hour for the season for single-rig vessels was 1,241 lb and 2,228 lb for double-rig vessels. Area B-2 average catch per hour by the single-rig vessels was 2,536 lb. Two-year-old (1975 year class) shrimp dominated the catches in all areas. The outlook for the 1978 season in all areas is questionable because of the relatively weak showing of the incoming 1977 year class but it might make a significant contribution if abundant and of a marketable slze. (19pp.