THE LOCATIONAL DETERMINANTS OF WESTERN NONMETRO HIGH TECH MANUFACTURERS: AN ECONOMETRIC ANALYSIS

The Tobit estimation procedure was used to determine the factors which influence the location and size of high technology manufacturers in nonmetro areas in the West. The results indicate that high tech branch plants tend to locate in populous counties adjacent to Metropolitan Statistical Areas (MSAs). Percent of local employment in manufacturing and agriculture was inversely related to branch plant employment, and the stock of human capital was not significantly related to employment. High tech unit plants also exhibited a propensity to locate in the more populous counties. Unlike branch plants, the unit concerns were more likely to develop or locate in communities with a highly educated work force and at greater distances from metro areas. The unit plants better fit the perception of high tech plants selecting high amenity locations with abundant skilled labor.Industrial Organization, Labor and Human Capital,

A kinetic study of the photolysis of tris(2,4-pentanedionato)cobalt(III) and bis(2,4-pentanedionato)cobalt(II) in chloroform

Under 254nm irradiation in chloroform, Co(acac)3 (Hacac = 2,4-pentanedione) is converted to Co(acac)2 and then to CoCl2. The metal complex is the primary photoactive species in the photoreduction of Co(acac)3, but the photosubstitution of Co(acac)2 appears to occur primarily through absorption of light by the solvent, followed by a chain reaction in which chlorine atoms displace pentanedionyl radicals. The photosubstitution rate law is complex, and the apparent quantum yield (based on total light absorbed) varies with incident light intensity and Co(acac)2 concentration, reaching values as high as 16 under the conditions of this study. Referred only to the light absorbed by CHCL3, the highest quantum yield measured was 150. An observed partial inverse dependence of the photosubstitution rate on the initial concentration of Co(acac)2 is explained in terms of a mechanism in which the pentanedione product competes with Co(acac)2 for an intermediate

Estimating the Knowledge-Capital Model of the Multinational Enterprise

What we term the firm includes three principal assumptions. First, services of knowledge-based and knowledge-generating activities, such as R&D, can be geographically separated from production and supplied to production facilities at low cost. Second, these knowledge-intensive activities are skilled-labor intensive relative to production. These characteristics give rise to vertical multinationals, which fragment production and locate activities according to factor prices and market size. Third, knowledge-based services have a (partial) joint-input characteristic that they can be supplied to additional production facilities at low cost. This characteristic gives rise to horizontal multinationals, which produce the same goods or services in multiple locations. In this paper, we note how this model predicts relationships between affiliate sales and country characteristics. We then subject these predictions to empirical tests.

Kinetics and Inhibition Studies of the L205R Mutant of cAMP-Dependent Protein Kinase Involved in Cushing’s Syndrome

Overproduction of cortisol by the hypothalamus–pituitary–adrenal hormone system results in the clinical disorder known as Cushing\u27s syndrome. Genomics studies have identified a key mutation (L205R) in the α‐isoform of the catalytic subunit of cAMP‐dependent protein kinase (PKACα) in adrenal adenomas of patients with adrenocorticotropic hormone‐independent Cushing\u27s syndrome. Here, we conducted kinetics and inhibition studies on the L205R‐PKACα mutant. We have found that the L205R mutation affects the kinetics of both Kemptide and ATP as substrates, decreasing the catalytic efficiency (kcat/KM) for each substrate by 12‐fold and 4.5‐fold, respectively. We have also determined the IC50 and Ki for the peptide substrate‐competitive inhibitor PKI(5–24) and the ATP‐competitive inhibitor H89. The L205R mutation had no effect on the potency of H89, but causes a \u3e 250‐fold loss in potency for PKI(5–24). Collectively, these data provide insights for the development of L205R‐PKACα inhibitors as potential therapeutics

Using decision-tree classifier systems to extract knowledge from databases

One difficulty in applying artificial intelligence techniques to the solution of real world problems is that the development and maintenance of many AI systems, such as those used in diagnostics, require large amounts of human resources. At the same time, databases frequently exist which contain information about the process(es) of interest. Recently, efforts to reduce development and maintenance costs of AI systems have focused on using machine learning techniques to extract knowledge from existing databases. Research is described in the area of knowledge extraction using a class of machine learning techniques called decision-tree classifier systems. Results of this research suggest ways of performing knowledge extraction which may be applied in numerous situations. In addition, a measurement called the concept strength metric (CSM) is described which can be used to determine how well the resulting decision tree can differentiate between the concepts it has learned. The CSM can be used to determine whether or not additional knowledge needs to be extracted from the database. An experiment involving real world data is presented to illustrate the concepts described

Strategies for adding adaptive learning mechanisms to rule-based diagnostic expert systems

Rule-based diagnostic expert systems can be used to perform many of the diagnostic chores necessary in today's complex space systems. These expert systems typically take a set of symptoms as input and produce diagnostic advice as output. The primary objective of such expert systems is to provide accurate and comprehensive advice which can be used to help return the space system in question to nominal operation. The development and maintenance of diagnostic expert systems is time and labor intensive since the services of both knowledge engineer(s) and domain expert(s) are required. The use of adaptive learning mechanisms to increment evaluate and refine rules promises to reduce both time and labor costs associated with such systems. This paper describes the basic adaptive learning mechanisms of strengthening, weakening, generalization, discrimination, and discovery. Next basic strategies are discussed for adding these learning mechanisms to rule-based diagnostic expert systems. These strategies support the incremental evaluation and refinement of rules in the knowledge base by comparing the set of advice given by the expert system (A) with the correct diagnosis (C). Techniques are described for selecting those rules in the in the knowledge base which should participate in adaptive learning. The strategies presented may be used with a wide variety of learning algorithms. Further, these strategies are applicable to a large number of rule-based diagnostic expert systems. They may be used to provide either immediate or deferred updating of the knowledge base

MECHANISMS OF DISEASE Acute Oxygen-Sensing Mechanisms

JOSEPH PRIESTLEY, ONE OF THE THREE SCIENTISTS CREDITED WITH THE discovery of oxygen, described the death of mice that were deprived of oxygen. However, he was also well aware of the toxicity of too much oxygen, stating, “For as a candle burns much faster in dephlogisticated [oxygen enriched] than in common air, so we might live out too fast, and the animal powers be too soon exhausted in this pure kind of air. A moralist, at least, may say, that the air which nature has provided for us is as good as we deserve.”1 In this review we examine the remarkable mechanisms by which different organs detect and respond to acute changes in oxygen tension. Specialized tissues that sense the local oxygen tension include glomus cells of the carotid body, neuroepithelial bodies in the lungs, chromaffin cells of the fetal adrenal medulla, and smooth-muscle cells of the resistance pulmonary arteries, fetoplacental arteries, systemic arteries, and the ductus arteriosus. Together, they constitute a specialized homeostatic oxygen-sensing system. Although all tissues are sensitive to severe hypoxia, these specialized tissues respond rapidly to moderate changes in oxygen tension within the physiologic range (roughly 40 to 100 mm Hg in an adult and 20 to 40 mm Hg in a fetus)Junta de Andalucí

THE DETERMINANTS OF FOOD STAMP PROGRAM PARTICIPATION

Food Security and Poverty,

AN IRRIGATION MODEL FOR MANAGEMENT OF LIMITED WATER SUPPLIES

A two-stage simulation/mathematical programming model is presented for determining the optimal intraseasonal allocation of irrigation water under conditions of limited water supply. The model is applied to a series of water shortage scenarios under both surface and center pivot irrigation. Economically efficient irrigation management is shown to involve the coordination of a number of managerial decisions, including irrigation scheduling, crop substitution, the adoption of improved irrigation labor practices, and idling land. The results indicate that significant opportunities exist for conserving water in the study area under both surface and center pivot irrigation.Crop Production/Industries, Resource /Energy Economics and Policy,