Space,Time, and Local Employment Growth: An Application of Spatial Regression Analysis

ABSTRACT Local and regional employment growth is generally studied either by searching for local qualitative explanatory factors such as governance, synergy between firms, and milieu effects, or by searching for general growth factors using statistical techniques. The body of work that relies on this approach has tended, in keeping with economics’ nomothetic tradition, to assume that local and regional growth factors are constant over space. The focus of this paper is on exploring the spatial stationarity of employment growth factors in Canada, but it also seeks to clarify some of the broad principles behind spatial regression techniques in order to provide a point of entry and a conceptual framework for empirical researchers. To do so, we apply a recently developed technique, Geographically Weighted Regression (GWR), and we explore the method's advantages and limits for answering our research question. We find evidence that growth factors differ across Canada, but we also conclude that the GWR technique, given the number and shape of regions available for our analysis and given certain limitations that are currently inherent to the method, can only provide tentative and exploratory results.     

Cardiovascular complications of chronic catheterization of the jugular vein in the dog

Cardiovascular changes associated with indwelling catheters were evaluated in 51 adult beagle dogs catheterized for 4 to 9 weeks. Pathologic changes consistent with traumatic injury were in the vena cava and endocardium of the right atrium of 88% of cannulated dogs. Lesions were characterized by surface denudation and diffuse intimal thickening due to myointimal hyperplasia and deposition of extracellular matrix. Affected intima was lined by hyperplastic, poorly differentiated endothelial cells and contained round to oval cells with characteristics of smooth muscle cells. After 9 weeks, thickened intima was vascularized and composed of spindle-shaped cells and fibrillar stroma. Intimal sclerosis and localized proliferative papillary projections in the vena cava cranial to areas of myointimal hyperplasia occurred infrequently. Traumatic lesions, regardless of location or severity, did not extend below the internal elastic membrane. Inflammatory cellular responses, when present, were minimal. The location, distribution, and morphogenesis of catheter-related cardiovascular lesions distinguishes them from those induced by chemical toxicity or pharmacotoxicity.     

Pathogenesis of experimental Leptospira interrogans serotype icterohaemorrhagiae infection in the guinea pigs: possible role of endotoxin of intestinal bacteria in the development of lesions.

Germ-free guinea pigs were infected with a virulent strain of Leptospira interrogans serotype icterohaemorrhagiae to evaluate the possible role of endotoxin of intestinal bacteria in the development of hemorrhages and hepatic and renal failure. Clinical manifestations, necropsy findings and histological lesions were similar to those seen in control animals. In the second part of the experiment, endotoxin was not detected by the Limulus test in the blood of ten guinea pigs during the five day course of leptospirosis.     

Immunization of mice against Streptococcus suis serotype 2 infections using a live avirulent strain.

In this study, the IgG response of mice injected with two virulent strains and one avirulent Streptococcus suis capsular type 2 strain was compared by Western blotting. The serum from mice immunized against the avirulent strain could recognize most proteins of the various strains tested and similar results were obtained with serum from mice injected with virulent strains. The live avirulent strain was injected twice (days 0 and 10) to groups of five mice, and four virulent strains from different geographical origins were used to challenge the animals. All mice, except one in one group, survived the challenge. These results suggest that a live avirulent strain could be used for immunization of swine, the natural host.     

Fibrocartilaginous emboli as the cause of ischemic myelopathy in a dog.

Acute hemiplegia and Horner's syndrome developed in a 6-year-old female black Labrador Retriever 24 hours after a day of exercise. Radiographic, cerebrospinal fluid, and electromyographic studies did not detect the site or nature of the suspected cervical lesion. The dog showed no improvement after evaluation for 5 days on corticosteroid and antibiotic therapy. Gross and microscopic examination revealed the presence of an ischemic infarct in the C6 segment of the cervical spinal cord and associated fibrocartilaginous emboli. The nature of the clinical signs and the pathologic findings in this case are similar to previous reports of human and canine cases.     

Bacterial and fungal flora in healthy eyes of birds of prey.

Birds of prey are often affected with external ocular injuries that are routinely treated with antimicrobial agents used for small animals. The resident ocular bacterial and fungal flora is still unknown in birds of prey and this knowledge would be very useful in assessing the accuracy of treatments. In a study involving 65 raptors with healthy eyes, swabs were taken from both eyes to identify the resident bacterial and fungal flora. Fifty-five birds had a positive culture in one or both eyes. Both gram-positive and gram-negative organisms were isolated, with a predominance of Staphylococcus spp., which were found in 52.3% of cultures. Only two fungal species, Aspergillus spp. and Cladosporium spp. were found. The overall results of this study are similar to previous studies carried out in humans and other animals.     

Inflammation: a clinical perspective. The Ciba-Geigy Prize for Research in Animal Health

The cardinal signs of acute inflammation have been recognised for almost 2000 years, but it is only in the last hundred years that significant progress has been made in understanding the underlying cellular response. Our knowledge of the chemical messengers which regulate and in some cases lead to persistence of the inflammatory process is, as yet, incomplete, but it is hoped that further research at this level will lead to the development of more effective therapeutic agents.     

Immunoperoxidase labeling of canine distemper virus replication cycle in Vero cells

An indirect immunocytochemical labeling technique, using horseradish peroxidase-conjugated antibody was used to detect the intracellular and surface membrane localization of canine distemper virus (R252-CDV) antigens during productive virus replication in infected Vero cells. Specific labeling of intracellular viral antigens was restricted to rough nucleocapsid aggregates. Surface membrane labeling correlated directly with the appearances both of virus-specific membrane spikes and buds and of mature virions. Syncytial cell formation was associated with labeled cytoplasmic nucleocapsid, but there was no evidence of productive CDV formation on surface membranes. The immunoperoxidase technique provided precise ultrastructural antigenic localization with concomitant preservation of excellent ultrastructural detail within single virus-infected cells during CDV replication cycle in vitro.