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.     

Biomechanical Analysis of the Three-Dimensional Motion Pattern of the Canine Cervical Spine Segment C4–C5

Objective— To study the kinematics of cervical spine segment C₄–C₅ and its association with disc dimensions and the coupled motion (CM) in relation to primary motion (PM).
Study Design— Cadaveric biomechanical study.
Animals— Cadavers of large breed dogs (>20 kg; n=11).
Methods— Spines were freed from muscles. Radiographs were taken orthogonal to the C₄–C₅ disc space and disc thickness, endplate width, and height were measured. Spines were mounted on a simulator for 3-dimensional motion analysis. Data were recorded with an optoelectronic motion analysis system. Range of motion (ROM) and neutral zone (NZ) were determined in the direction of flexion/extension, left/right lateral bending, and left/right axial rotation, as well as the ROM of CM.
Results— ROM in flexion and extension was similar; there was no CM in flexion/extension. Left/right axial rotation and left/right lateral bending were coupled to the same side. CM was 1.72 and 3.56 times the ROM of the PM in lateral bending and axial rotation, respectively. Disc dimensions were positively correlated with body weight. Flexion/extension magnitude was significantly reduced for larger endplates, but axial rotation was not influenced. Lateral bending had no correlation with weight or disc dimensions.
Conclusion— Left/right lateral bending and left/right axial rotation are coupled differently in the C₄–C₅ segment in dogs compared with humans.
Clinical Relevance— The canine C₄–C₅ spinal segment has unique motion coupling patterns that should be considered for dynamic implant designs.     

Field Efficacy of a Mechanical Pump Spray Formulation Containing 0.25% Fipronil in the Treatment and Control of Flea Infestation and Associated Dermatological Signs in Dogs and Cats

Abstract— Fipronil is a new insecticide and acaricide belonging to the phenylpyrazole family. Experimental studies have demonstrated the efficacy of a 0.25% fipronil mechanical pump spray formulation against fleas and ticks in both dogs and cats. Two multicentric clinical trials were set up to confirm the efficacy of this product under field conditions. The dog study was a positive control study. Flea infestation was qualitatively assessed at the initial visit (treatment date) and at the final visit (when reinfestation was observed or at the latest by 2 months after treatment). Sixty-one per cent and 21.5 per cent of dogs were free of fleas (“zero-flea stage”) at the end of the second month post-treatment in the experimental and reference groups, respectively. The incidence of pruritus and dermatological lesions was reduced in the two groups but with significantly better results in the fipronil group. Sixty-one per cent of the cats treated with fipronil were also free of fleas at the end of the second month post-treatment. Pruritus was also significantly reduced. Résumé— Le fipronil est un nouvel insecticide appartenant à la famille des phénylpyrazolés. Des études expérimentales ont démontré l'efficacité d'une solution à 0,25% de fipronil en pulvérisation manuelle contre les puces et les tiques chez le chien et le chat. Deux études cliniques multicentriques ont été conduites pour confirmer l'efficacité de ce produit sur le terrain. L'étude chez le chien est une étude contrôlée positive. L'infestation par les puces a été déterminée qualitativement lors de la visite initiale (date du traitement), et lors de la visite finale (quand une réinfestation a été observée ou au moins 2 mois après le traitement). 61% et 21,5% des chiens étaient indemnes de puces (stade 0 puce) à la fin du second mois consécutif au traitement respectivement dans le groupe traité et dans le groupe de référence. Le prurit et les lésions dermatologiques étaient réduits dans les deux groupes, mais avec des résultats meilleurs dans le groupe fipronil. 61% des chats traités avec le fipronil étaient aussi indemnes de puces 2 mois après le traitement. Le prurit était également significativement réduit. [Postal, J.-M. R., Jeannin, P. C, Consalui, P.-J. Field efficiency of a mechanical pump spray formulation containing 0.25% fipronil in the treatment and control of flea infestation and associated dermatological signs in cats and dogs (Efficacité d'une solution à 0,25% de fipronil en pulvérisation manuelle dans le traitement et le contrôle d'une pullicose et des symptômes dermatologiques associés chez les chiens et les chats). Resumen— El fipronil es un nuevo insecticida y acaricida de la familia de los fenilpirazoles. Estudios expérimentales han demostrado la efectividad de une fórmula de fipronil al 0,25% en un pulverizador con sistema mecànico de bombeo contra pulgas y piojos en el perro y en el gato. Se diseñaron dos pruebas clinicas multicéntricas para confirmar la afectividad de este producto en condiciones de campo. El estudio en el perro fue la prueba control. Se realizó un examen cualtitativo sobre el grado de infestación por pulgas en la primera visita (fecha de tratamiento) y en la última visita (en caso de reinfestación o como máximo dos meses después del tratamiento). El sesenta y uno por ciento y el 21,5% de los perros estaba libre de pulgas (“estadio pulga-cero”) al final del segundo mes después del tratamiento en los grupos experimental y de referencia, respectivamente. La incidencia de prurito y de lesiones dermatológicas se vieron reducidos en los dos grupos pero con resultados significativamente mejores en el grupo del fipronil. El sesenta y uno por ciento de los gatos tratados con fipronil estaban también fibres de pulgas al final del segundo mes después del tratamiento. El prurito se vió también significativamente disminuido. [Postal, J.-M. R., Jeannin, P. C, Consalui, P.-J. Field efficiency of a mechanical pump spray formulation containing 0.25% fipronil in the treatment and control of flea infestation and associated dermatological signs in cats and dogs (Efectividad en un estudio de campo de una fórmula para pulverizador con sistema mecànico de bombeo con un 0,25% de fipronil en el tratamiento y control de infestaciones por pulgas y problemas dermatológicos asociados en el perro y el gato).     

Rapid flow cytometry method for ploidy determination in salmonid eggs

Abstract. A rapid and simple method for ploidy determination by Row cytometry was developed for rainbow trout, Oncorhynchus mykiss Walbaum, and brown trout, Salmo trutta L., using commercially available reagents, and protocols previously implemented for plant tissues. The whole egg was directly chopped up in buffer, to release nuclei in an intact state. After filtration, the nuclei suspension was stained with a specific DNA fluorochrome and analysed by flow cytometry, using a compact, one-parameter cytometer. Within minutes, histograms of high quality were obtained, with a very good reproducibility, allowing unambiguous discrimination of diploids and triploids. Preliminary results indicate that the same methodology could be used for non-destructive analysis of young fish, using small samples of fin or muscle.     

Pharmacokinetic interaction of isopropylaminophenazone and phenylbutazone in the horse

The pharmacokinetics of the two active anti-inflammatory compounds, isopropylaminophenazone and phenylbutazone, were investigated in the horse. Therapeutic intravenous doses of 12 mg/kg body weight and 6 mg/kg body weight, respectively, were given separately and as a combination to five horses. Blood concentrations were described by two-compartment kinetics. Significantly lower total clearances, unchanged volumes of distribution, and hence significantly higher elimination half-lives were found for both substances when administered as a combination. It is possible that the hydroxylated metabolites of the substances are responsible for the presumed metabolic interference.     

Effects of the seed weight and burial depth on the seed behavior of common ragweed (Ambrosia artemisiifolia)

Common ragweed (Ambrosia artemisiifolia L.) is one of the annual plants that were described recently as invasive weeds in Europe. This species is described as an invasive plant that produces seeds that are highly variable. Its production of variably sized seeds is regarded as promoting its spread in different environments. Experiments were carried out to determine the influence of the seed weight and temperature on germination and the influence of the seed weight and burial depth on seedling emergence. The seeds were divided into a number of classes of weight and the seed weight effect on germination was evaluated by Petri dish assays. In another experiment, the seeds were buried at different depths in a clay soil/sand mix to estimate the burial effect on germination and seedling emergence. The germination level of A. artemisiifolia was high overall, between 76.8% and 94.2%. The seed germination was modified by temperature but it was not influenced by the seed weight. The amounts of germination and seedling emergence were greater for the seeds on the soil surface and decreased with an increasing burial depth, from 2 to 8 cm. No germination or emergence was observed for the seeds that were buried at 10 and 12 cm. The lightest seeds were more sensitive to burial. A greater level of seedling emergence for those seeds that were placed near the soil surface could explain the success of this species in open habitats, where the probability of deeper burial is low. After high seed production, the management of A. artemisiifolia in fields could be partly achieved through soil tillage, burying seeds below 10 cm, and not carrying out deep soil tillage the following year.     

Biomechanical Analysis of Torsion and Shear Forces in Lumbar and Lumbosacral Spine Segments of Nonchondrodystrophic Dogs

Objective— To determine stiffness and load–displacement curves as a biomechanical response to applied torsion and shear forces in cadaveric canine lumbar and lumbosacral specimens.
Study Design— Biomechanical study.
Animals— Caudal lumbar and lumbosacral functional spine units (FSU) of nonchondrodystrophic large-breed dogs (n=31) with radiographically normal spines.
Methods— FSU from dogs without musculoskeletal disease were tested in torsion in a custom-built spine loading simulator with 6 degrees of freedom, which uses orthogonally mounted electric motors to apply pure axial rotation. For shear tests, specimens were mounted to a custom-made shear-testing device, driven by a servo hydraulic testing machine. Load–displacement curves were recorded for torsion and shear.
Results— Left and right torsion stiffness was not different within each FSU level; however, torsional stiffness of L7-S1 was significantly smaller compared with lumbar FSU (L4-5–L6-7).
Ventral/dorsal stiffness was significantly different from lateral stiffness within an individual FSU level for L5-6, L6-7, and L7-S1 but not for L4-5. When the data from 4 tested shear directions from the same specimen were pooled, level L5-6 was significantly stiffer than L7-S1.
Conclusions— Increased range of motion of the lumbosacral joint is reflected by an overall decreased shear and rotational stiffness at the lumbosacral FSU.
Clinical Relevance— Data from dogs with disc degeneration have to be collected, analyzed, and compared with results from our chondrodystrophic large-breed dogs with radiographically normal spines.     

Understanding what controls the spawning distribution of North Sea whiting (Merlangius merlangus) using a multi‐model approach

The processes that control the spatial distribution of North Sea whiting (Merlangius merlangus) spawning adults are investigated using a statistical multi‐model approach. Models of external and internal controls on the population, such as environmental conditions, spatial constraints, present or past spatial distribution, and demographic state of the population, are evaluated, compared and ranked to select those that are the best able to predict the observed distribution of spawning adults. Model selection is greatly influenced by the selection method, either based on data fitting or prediction, as well as by the threshold value used to stop the selection. Model selection based on prediction tends to select simpler models than selection based on data fitting. The hypotheses underlying the selected models are inferred to play a significant role in controlling North Sea whiting spatial distribution. The multi‐model inference approach developed in this study enables comparison of several theoretical concepts and hypotheses and the results provide important clues on the processes involved in the control of the spatial distribution of whiting. We conclude that whiting has a high spatial fidelity to spawning site which can be linked to either geographical attachment or year‐to‐year persistence of the spatial distribution of the population. Environmental factors – temperature and salinity – appear to influence the geographical extent of spawning whiting distribution, whereas local abundance levels are primarily controlled by internal factors, i.e., population size and spatial segregation between ages.