bluuebunny/crossref_metadata_2025 huggingface dataset:
A Study of 43 Patients with Panayiotopoulos Syndrome, a Common and Benign Childhood Seizure Susceptibility
Authors: Lada Christina , Skiadas Konstantinos , Theodorou Virginia , Loli Nomiki , Covanis Athanasios
Published: March 2003

Summary:  Purpose: To determine prevalence, clinical, EEG features, and prognosis of Panayiotopoulos syndrome and to examine the proposition that clinical manifestations are more important than EEG findings.

Methods: We analyzed retrospectively the clinical and EEG records of 1,340 children with one or more focal seizures seen in the last 18 years, supplemented with a prospective study from 1998. Panayiotopoulos syndrome was defined by clinical criteria, mainly ictal emesis, irrespective of EEG findings.

Results: We analyzed 43 of 90 patients with Panayiotopoulos syndrome who were seizure free >2 years. Girls predominated. Mean age at first seizure was 5 years. Seizures consisted mainly of autonomic manifestations; ictal emesis was often the first symptom, culminating in vomiting in 86%. Of nonautonomic manifestations, lateral eye deviation was the most common; visual symptoms were exceptional. Impairment of consciousness ensued in all seizures, half of which ended with hemi or generalized convulsions. Nearly 46.5% of cases had at least one seizure >30 min, constituting autonomic status epilepticus. Seizures during sleep (84%) were more common than those in wakefulness. EEG showed occipital spikes in 29 patients. Of the other 14 cases, five had extraoccipital abnormalities or brief generalized discharges, and nine had normal awake and sleep EEG. Prognosis was excellent. All 43 children have been free of seizures for ≥2 years, 53% having a single seizure, and 47%, an average two to three seizures.

Conclusions: Panayiotopoulos syndrome is common and needs wider recognition. EEG shows occipital or extraoccipital abnormalities, is normal in one third of patients, and does not determine clinical manifestations or prognosis, which is excellent despite the high prevalence of lengthy seizures.
Pharmacodynamic Analysis of the Interaction between Tiagabine and Midazolam with an Allosteric Model That Incorporates Signal Transduction
Authors: Jonker Daniël M. , Vermeij Dick A. C. , Edelbroek Peter M. , Voskuyl Rob A. , Piotrovsky Vladimir K. , Danhof Meindert
Published: March 2003

Summary:  Purpose: The objective of this study was to characterize quantitatively the pharmacodynamic interaction between midazolam (MDL), an allosteric modulator of the γ‐aminobutyric acid subtype A (GABAA) receptor, and tiagabine (TGB), an inhibitor of synaptic GABA uptake.

Methods: The in vivo concentration–response relation of TGB was determined through pharmacokinetic/pharmacodynamic (PK/PD) modeling. Rats received a single intravenous dose of 10 mg/kg TGB in the absence and the presence of a steady‐state plasma concentration of MDL. The EEG response in the 11.5‐ to 30‐Hz frequency band was used as the pharmacodynamic end point.

Results: Infusion of MDL resulted in a mean steady‐state plasma concentration of 66 ± 3 ng/ml. A significant pharmacokinetic interaction with TGB was observed. MDL inhibited TGB clearance by 20 ± 7 ml/min/kg from the original value of 89 ± 6 ml/min/kg. However, no changes in plasma protein binding of both drugs were observed. The concentration–EEG relation of TGB was described by the sigmoid‐Emax model. The pharmacodynamic parameter estimates of TGB were: Emax = 327 ± 10 μV, EC50 = 392 ± 20 ng/ml, and nH = 3.1 ± 0.3. These values were not significantly different in the presence of MDL. Factors that may explain the lack of synergism were identified by a mechanism‐based interaction model that separates the receptor activation from the signal‐transduction process. High efficiency of signal transduction and the presence of a baseline response were shown to diminish the degree of synergism.

Conclusions: We conclude that the in vivo pharmacodynamic interaction between MDL and TGB is additive rather than synergistic. This strongly suggests that allosteric modulation of the antiseizure activity of a GAT‐1 inhibitor by a benzodiazepine does not offer a therapeutic advantage.
An Examination of Calcium Current Function on Heterotopic Neurons in Hippocampal Slices from Rats Exposed to Methylazoxymethanol
Authors: Calcagnotto Maria Elisa , Baraban Scott C.
Published: March 2003

Summary:  Purpose: To study voltage‐dependent calcium currents (VDCCs) on hippocampal heterotopic neurons by using whole‐cell patch‐clamp techniques in brain slices prepared from methylaxozymethanol (MAM)‐exposed rats.

Methods: Whole‐cell voltage‐clamp recordings were obtained from visually identified neurons in acute brain slices by using an infrared differential interference contrast (IR‐DIC) video microscopy system. Heterotopic neurons were compared with normotopic pyramidal cells in hippocampal slices from MAM‐exposed rats or CA1 pyramidal neurons in slices from controls.

Results: Heterotopic neurons expressed a prominent VDCC, which exhibited a peak current maximum around –30 mV (holding potential, –60 mV) and an inactivation time constant of 48.2 ± 2.4 ms (n = 91). VDCC peak current and inactivation time constants were similar for normotopic (n = 92) and CA1 pyramidal cells (n = 40). Pharmacologic analysis of VDCC, on heterotopic, normotopic, and CA1 pyramidal cells, revealed an ∼70% blockade of peak Ca2+ current with nifedipine and amiloride (L‐ and T‐type channel blockers, respectively). Inhibition of VDCC, for all three cell types, also was similar when more specific Ca2+ channel antagonists were used [e.g., ω‐conotoxin GVIA (N‐type), ω−agatoxin KT (P/Q‐type), and sFTX‐3.3 (P‐type)]. VDCC modulation by norepinephrine (NE) or adrenergic receptor–specific agonists [clonidine (α2), isoproterenol (β), and phenylephrine (α1)] was similar for heterotopic and CA1 pyramidal cells.

Conclusions: Heterotopic neurons do not appear to exhibit Ca2+ channel abnormalities that could contribute to the reported hyperexcitability associated with MAM‐exposed rats.
Exploration of a Putative Susceptibility Locus for Idiopathic Generalized Epilepsy on Chromosome 8p12
Authors: Sander Thomas , Windemuth Christine , Schulz Herbert , Saar Kathrin , Gennaro Elena , Riggio Concetta , Bianchi Amedeo , Zara Federico , Rudolf Gabrielle , Picard Fabienne , Bulteau Christine , Kaminska Anna , Cieuta Cécile , Prud'homme Jean‐François , Dulac Olivier , Bate Louise , Robinson Robert , Gardiner R. Mark , Covanis Athanasios , De Haan Gerrit‐Jan , Janssen Guus A. M. A. J. , Van Erp M. Gerard , Boezeman Eduard H. J. F. , Lindhout Dick , Heils Armin , Nürnberg Peter , Janz Diéter
Published: March 2003

Summary:  Purpose: A recent genome‐wide scan revealed a major susceptibility locus for idiopathic generalized epilepsies (IGEs) in the chromosomal region 8p12 in 32 IGE families without members with juvenile myoclonic epilepsy (JME). This study explored the presence of an IGE locus in the chromosomal region 8p12.

Methods: Our study included 176 multiplex families of probands with common IGE syndromes. Parametric and nonparametric multipoint linkage analyses were carried out between the IGE trait and six microsatellite polymorphisms encompassing the putative susceptibility locus. To explore the associated phenotype–genotype relation, two distinct subgroups of families were selected by the presence (n = 64) or absence (n = 112) of a family member with JME. To adjust the phenotypic spectrum toward adolescent‐onset IGEs, a third subgroup of 28 families without JME was chosen through an IGE proband with seizure onset at age 10–20 years.

Results: Parametric and nonparametric multipoint linkage analyses provided no evidence for linkage between IGE and markers encompassing the putative IGE locus in the chromosomal region 8p12. Furthermore, we found no hint of linkage along the candidate region in any of the three family subgroups.

Conclusions: We failed to provide evidence for a major IGE locus in the chromosomal region 8p12. On the contrary, these parametric linkage results provide strong evidence against linkage across the candidate region under a broad range of genetic models. If there is a susceptibility locus for IGE in the chromosomal region 8p12, then the size of the effect or the proportion of linked families is too small to detect linkage in the investigated family sample.
Evaluation of Opioid Peptide and Muscarinic Receptors in Human Epileptogenic Neocortex: An Autoradiography Study
Authors: Ondarza Rodolfo , Trejo‐Martínez David , Corona‐Amézcua Rodrigo , Briones Magdalena , Rocha Luisa
Published: March 2003

Summary:  Purpose: The main goal of the present study was to evaluate possible alterations in opioid peptide and muscarinic receptors in human neocortical epileptic focus and the surrounding area removed from patients with pharmacologically resistant epilepsy and epilepsy secondary to cerebral lesion by tumor or other causes.

Methods: In vitro quantitative autoradiography experiments were carried out to label μ, δ, and muscarinic receptors of neocortical epileptic focus and surrounding area obtained from patients with pharmacologically resistant primary epilepsy and epilepsy caused by tumors and angioma cavernosa, and compared with neocortex obtained from patients with dementia and tumors without epilepsy.

Results: The μ receptor levels were lower in surrounding areas (–46%). The δ receptor binding was reduced in epileptic focus obtained from patients with epilepsy secondary to cerebral lesion (–25%) and surrounding areas (–31%). In contrast, muscarinic receptor levels were higher in the focus from patients with primary epilepsy (layers I–II, 52%; layers III–IV, 44%; layers V–VI, 36%).

Conclusions: It is suggested that the increased muscarinic receptors in the epileptic focus and the decreased μ and δ receptors in the surrounding area are associated with the initiation and propagation of seizure activity in human epileptogenic neocortex.
Characterization of Reactive Astrocytes in the Chronic Phase of the Pilocarpine Model of Epilepsy
Authors: Garzillo Cibele L. , Mello Luiz E. A. M.
Published: March 2003

Summary:  Purpose: Astrogliosis is a prominent finding in human temporal lobe epilepsy. Work in animal models of temporal lobe epilepsy, however, have mostly concentrated on the acute phases of the studied models or have failed to demonstrate reactive gliosis during the chronic phases of such models.

Methods: Here we used the pilocarpine model of chronic seizures and Cajal's gold sublimate technique for the staining reactive astrocytes to study this issue.

Results: For half of the animals (nine of 17) subject to pilocarpine‐induced status epilepticus (SE), when assessed 60 days later, variable levels of reactive astrocytes were seen in many thalamic, hippocampal, amygdalar, and neocortical areas. For the remaining half of the animals, however (eight of 17), despite a similar SE induction, as well as for controls, we could not detect stained reactive astrocytes.

Conclusions: We hypothesize that these results might underlie possible differences in the frequency of recurrent spontaneous seizures.
Detecting Epileptic Spikes
Authors: Diambra L.
Published: March 2003

Summary: We present a technique for automatic detection of epileptic spikes in electroencephalogram (EEG) recordings. We used a nonlinear modeling method that enables us to detect rapidly and accurately epileptic behavior in the EEG signal. Our approach is illustrated by an application to interictal activity from a patient with focal epilepsy.
A New Approach to the Functional Systems of the Brain
Authors: Hikosaka Okihide
Published: March 2003

Summary: Action is the means by which animals survive. It consists of a complex combination of movements that are either innately endowed or acquired by learning. Innate and learned actions are controlled by different levels of neural networks: innate actions are controlled by reflex mechanisms and pattern generators in the spinal cord and brainstem, whereas learned actions are controlled by the cerebral cortex, basal ganglia, and cerebellum. However, these mechanisms are by no means independent. Recent studies have shown that multiple brain areas contribute to the implementation of learned actions. Based on a series of studies using a sequenced learning task with trial and error, we propose a hypothetical scheme in which a sequential procedure is acquired independently by two cortical systems, one using spatial coordinates, and the other using motor coordinates. They are active preferentially in the early and late stages of learning, respectively. Both of the systems are supported by loop circuits formed with the basal ganglia and the cerebellum, the former for reward‐based evaluation and the latter for processing of timing. The proposed neural architecture would operate in a flexible manner to acquire and execute multiple sequential procedures.
Myocardial Performance Index (Tei Index) Does Not Reflect Long‐Term Changes in Left Ventricular Function after Acute Myocardial Infarction
Authors: Hole Torstein , Skjærpe Terje
Published: March 2003

Aims: To evaluate whether changes in myocardial performance index (MPI or Tei index) were related to changes in other Doppler echocardiographic parameters after acute myocardial infarction, or had any independent prognostic impact in a 2‐year observational study. Methods and Results: Seventy‐one patients with acute myocardial infarction without heart failure were examined at baseline, 3 months, and 2 years. MPI was significantly related to end‐diastolic and end‐systolic volume indexes, ejection fraction, maximal velocity, and time velocity integral of early mitral filling wave at 3 months and 2 years. MPI did not contribute significantly to the prediction of any changes in the measures of diastolic or systolic function at 3 months or 2 years. Baseline MPI was significantly higher in patients who later developed heart failure

(0.55 ± 0.16)

than in other patients

(0.43 ± 0.13, P = 0.006)

, but had no independent predictive power for the development of heart failure or death relative to end‐systolic volume index and deceleration time of early mitral filling wave. Conclusion: MPI did not accurately reflect changes in Doppler and two‐dimensional echocardiographic measures of diastolic or systolic function during a 2‐year follow‐up after acute myocardial infarction, and did not have any independent prognostic impact. (ECHOCARDIOGRAPHY, Volume 20, January 2003)
Three‐Dimensional Transesophageal Echocardiographic Demonstration of Anatomical Defects in AV Septal Defect Patients Presenting for Reoperation
Authors: Miller Andrew P. , Nanda Navin C. , Aaluri Srinivasa , Mukhtar Osman , Nekkanti Rajasekhar , Thimmarayappa Mahesha V. , Pacifico Albert D.
Published: March 2003

We present two‐ and three‐dimensional transesophageal echocardiographic findings of two adult patients who presented for reoperation after previous repair of a partial atrioventricular (AV) septal defect. Both patients had a cleft in the left AV valve with severe regurgitation. One patient had an additional 10 × 5 mm defect connecting the left ventricle to the right atrium through the AV junction. Three‐dimensional echocardiography was superior to two‐dimensional echocardiography in comprehensively delineating the anatomical defects in the left AV valve and the AV junction. (ECHOCARDIOGRAPHY, Volume 20, January 2003)
Der Einfluß von Condrosulf® (Natriumchondroitinsulfat) auf die Proteoglykansynthese und Zellproliferation osteoarthrotischer humaner und juveniler boviner Gelenksknorpelzellen – eine In‐vitro‐Untersuchung
Authors: Bobacz K. , Erlacher L. , Graninger W. B.
Published: March 2003

Zusammenfassung: Grundlagen: Natriumchondroitinsulfat, Condrosulf®, kommt in der Arthrosetherapie zur Anwendung und wird zur Gruppe der „symptomatic slow‐acting drugs for osteoarthritis” gezählt. Das Ziel dieser Studie war es, den Einfluß von Natriumchondroitinsulfat auf die Proteoglykansynthese und die Zellproliferation osteoarthrotischer humaner und juveniler boviner Chondrozyten ohne arthrotische Läsionen in einem In‐vitro‐Modell zu untersuchen.

 Methodik: Die Knorpelzellen wurden als Monolayerkulturen für sieben (humaner Knorpel), bzw. 4, 8 und 12 Tage (boviner Knorpel) mit Condrosulf® unterschiedlicher Konzentrationen (100 µg/ml, 500 µg/ml, 1000 µg/ml, 2500 µg/ml und 5000 µg/ml) stimuliert. Die Proteoglykansyntheserate wurde unter Anwendung der [35S]Sulfat‐Inkorporationmethode gemessen. Zur Bestimmung der Zellproliferation wurde ein [3H]Thymidin Assay angewandt. Die Expression der Knorpelmarker Aggrecan und Collagen Typ II wurde mittels Northern Blot erhoben.

 Ergebnisse: Wir konnten zeigen, daß unter den vorherrschenden Kulturbedingungen die Stimulation mit Condrosulf® zu keiner Erhöhung der Proteoglykansyntheserate, weder in osteoarthrotischen, noch in gesundem Knorpel führte. Die Zellproliferation wurde durch Zugabe von Condrosulf® ebenfalls nicht gesteigert. Die Auswertung der Northern Blots ergab eine konzentrationsabhängige Verminderung des mRNA‐Signals, bezogen auf die Aggrecan Expression.

 Schlußfolgerungen: Diese Daten weisen darauf hin, daß Condrosulf® keinen anabolen Einfluß auf die biosynthetische Aktivität von kultivierten Knorpelzellen hat. Die bekannten Effekte der Condrosulf®‐Medikation in vivo (Linderung von Schmerzen und Rückgang von Schwellungen) könnte auf eine Interaktion mit pro‐inflammatorischen Zytokinen zurückgeführt werden.
Examination, Prevention and Treatment of Osteoporosis in Patients with Inflammatory Bowel Disease: Recommendations and Reality
Authors: Kirchgatterer A. , Wenzl H. H. , Aschl G. , Hinterreiter M. , Stadler B. , Hinterleitner T. A. , Petritsch W. , Knoflach P.
Published: March 2003

Summary: Background
: Patients with inflammatory bowel disease (IBD) are at increased risk of developing osteopenia and osteoporosis. Our aim was to evaluate the current practices of examination, prevention and treatment of osteoporosis in IBD patients in a routine clinical setting.
 
Methods
: A total of 154 consecutive patients with IBD (63 female, 91 male; 36 ulcerative colitis, 115 Crohn's disease, 3 indeterminate colitis), referred to two gastroenterological units for scheduled follow‐up examinations, were included. Patient charts were evaluated regarding bone densitometry already performed and any prophylactic or therapeutic interventions in cases of low bone mineral density.
 
Results
: Bone mineral density (BMD) measurements had been performed only in 38 patients (25 %). BMD was abnormally low in 27 of the examined patients (71 %), 20 of whom had osteopenia and seven had osteoporosis. Among the subgroup of patients on long‐term steroid therapy (77 patients), 30 had been referred to bone densitometry during the course of disease, and 21 of them were found to have low bone mineral density. Preventive measures were prescribed in 12 patients (9 % of the whole study population). In the majority of the patients with low bone mineral density, calcium and vitamin D were used as treatment.
 
Conclusions : Despite the high prevalence of osteopenia and osteoporosis in patients with IBD, only a minority of these patients were included in a structured program in accordance with modern guidelines for diagnosing and preventing this extraintestinal complication in a routine clinical setting.
Einsatz der 18F‐Fluorodeoxyglukose‐Positronenemissionstomographie in der klinischen Hirndiagnostik
Authors: Buck A. , Kamel E.
Published: March 2003

Zusammenfassung: In dieser Übersichtsarbeit wird diskutiert, bei welchen Hirnerkrankungen die Positronenemissionstomographie einen wesentlichen diagnostischen Beitrag leisten kann. Weil die Methode relativ teuer ist, müssen die Indikationen klar definiert werden. Bei der Hirntumordiagnostik steht die Unterscheidung Rezidiv/Strahlennekrose und das Grading im Vordergrund. Bei HIV‐Patienten kann mittels Fluorodeoxyglukose‐Positronenemissionstomographie zwischen Lymphom und Toxoplasmose unterschieden werden. In der Demenzabklärung ist die Positronenemissionstomographie nützlich bei der Sicherung der Alzheimerdiagnose. Ein weiteres Anwendungsgebiet betrifft die prächirurgische Abklärung von Epilepsiepatienten und Patienten mit zerebrovaskulären Erkrankungen, welche für eine Revaskularisation vorgesehen sind. Bei extrapyramidalen Syndromen kann gelegentlich die Differentialdiagnose geklärt werden.
Laser ranging and video imaging for bin picking
Authors: Boughorbel Faysal , Zhang Yan , Kang Sangkyu , Chidambaram Umayal , Abidi Besma , Koschan Andreas , Abidi Mongi
Published: March 2003

This paper describes an imaging system that was developed to aid industrial bin picking tasks. The purpose of this system was to provide accurate 3D models of parts and objects in the bin, so that precise grasping operations could be performed. The technology described here is based on two types of sensors: range mapping scanners and video cameras. The geometry of bin contents was reconstructed from range maps and modeled using superquadric representations, providing location and parts surface information that can be employed to guide the robotic arm. Texture was also provided by the video streams and applied to the recovered models. The system is expected to improve the accuracy and efficiency of bin sorting and represents a step toward full automation.
The new regionalism: trade liberalization or insurance?
Authors: Perroni Carlo , Whalley John
Published: March 2003

Several of the recently negotiated regional trade agreements contain significantly fewer concessions by the large countries to smaller countries than vice versa. In this paper, we compute post‐retaliation Nash tariffs by region under various regional trade arrangements using a calibrated numerical general equilibrium model of world trade. Regional agreements constrain strategic behaviour within each trading area, and (in the Customs Union case) enhance it outside the bloc. Results confirm the intuition that without side payments large‐small country regional agreements (such as the Canada‐U.S. agreement) would not have occurred.

Le nouveau régionalisme: libéralisation du commerce ou assurance? Dans plusieurs des accords de libre échange régionaux négociés récemment, les grands pays accordent beaucoup moins de concessions aux petits pays que les petits aux grands. Dans cet article, les auteurs mesurent, à l'aide d'un modèle numérisé d'´equilibre général du commerce mondial, les droits de douane à la Nash après ajustements réciproques. Il semble que les accords régionaux contraignent les comportements stratégiques dans chaque bloc, et (dans le cas de l'union douanière) renforcent les comportements stratégiques hors du bloc. Ces résultats confirment l'intuition qui suggère que, sans ces arrangements parallèles, les accords entre grands et petits pays (comme l'accord U.S.A.‐Canada) ne se matérialiseraient pas.
The failure of the monetary exchange rate model for the Canadian‐U.S. dollar
Authors: Cushman David O.
Published: March 2003

In this paper the validity of the monetary exchange rate model in the long run for the Canadian‐U.S. dollar exchange rate is examined. The primary test employed is the Johansen (1991) and Johansen and Juselius (1990) cointegration technique. The effects of dummy variables and lag specification on the statistical inference are considered, and Monte Carlo simulations based on the estimated parameters are employed. Despite the use of the longest data set yet for the Canadian case, no evidence is found in favour of the monetary exchange rate model using the Johansen procedures. This result is confirmed by several other cointegration procedures. JEL Classification: F31; F41

La faillite du modèle monétaire du taux de change pour les dollars canadien et américain. Ce mémoire examine le modèle monétaire du taux de change pour savoir s'il est validé par l'expérience canado‐américaine en longue période. Le test principal utilisé est la technique de cointégration de Johansen (1991) et Johansen et Juselius (1990). Les effets des variables fictives et de la spécification de la structure de délais sur l'inférence statistique sont considérés, et on utilise des simulations de Monte Carlo fondées sur les paramètres calibrés. Malgré le fait qu'on fait appel à la plus longue série chronologique utilisée dans ce type d'analyse à ce jour, on ne trouve aucun support du modèle monétaire du taux de change en utilisant les procédures de Johansen. Ce résultat est confirmé par l'utilisation de plusieurs autres procédures de cointégration.
Canadian manufacturers' relative productivity performance, 1907–1990
Authors: Keay Ian
Published: March 2003

In this paper I calculate TFP ratios for a sample of Canadian manufacturers relative to their American counterparts on an annual basis throughout most of the twentieth century. The data used to calculate these ratios are drawn from both industry‐level and firm‐level statistical sources. I find that, in contrast to the relative labour productivity evidence in the literature, when TFP is used as the measuring stick, there is virtually no evidence of consistent and substantial relative technical inefficiency on behalf of the Canadian manufacturers represented in my sample. JEL Classification: D24, N60

Dans ce mémoire, l'auteur calcule les ratios de la productivité totale des facteurs de production (PTF) des manufacturiers canadiens par rapport à celle de leurs collègues américains sur une base annuelle pour la plus grande partie du vingtième siècle. Les données utilisées sont tirées des sources statistiques tant au niveau de l'industrie que de l'entreprise. On montre que, contrairement à ce que suggère la littérature spécialisée à propos de la productivité relative du travail, quand la PTF est utilisée comme étalon de mesure, on ne trouve vraiment pas vraiment de résultats qui suggéreraient une inefficacité technique relative substantielle et persistante des manufacturiers canadiens de l'échantillon.
The effects of unions on research and development: an empirical analysis using multi‐year data
Authors: Betts Julian R. , Odgers Cameron W. , Wilson Michael K.
Published: March 2003

A link between unionization and research and development rates (research and development expenditures divided by output) is tested for in thirteen aggregate Canadian industries. A balanced panel of thirteen industries covering 1968 to 1986 reveals a negative relationship between industry unionization rates and research and development. The results hold when a number of techniques are used to control for unobserved industry heterogeneity and non‐linear responses to unionization. In an industry that moves from the 25th to the 75th percentile of unionization, research and development is predicted to fall by about 40 per cent. JEL Classification: J51

Les effets des syndicats sur l'intensité de la recherche et développement: une analyse empirique sur plusieurs années. Ce mémoire examine le lien entre le degré de syndicalisation et les taux de dépenses en recherche et développement en proportion de la production dans treize industries canadiennes. Pour ces treize secteurs industriels, entre 1968 et 1986, il semble qu'il y ait une relation négative entre les taux de syndicalisation et les taux de dépenses en recherche et développement. Ces résultats sont robustesmême quand on utilise des techniques pour tenir compte de l'hétérogéneité des secteurs et des réponses non linéaires à la syndicalisation. Pour une industrie qui voit son taux de syndicalisation passer du 25e au 75e percentile, on prévoit une chute de 40% dans la recherche et développement.
Human capital accumulation and endogenous public expenditures
Authors: Glomm Gerhard , Ravikumar B.
Published: March 2003

In this paper, we present an overlapping‐generations model, where individuals accumulate human capital through formal schooling. We model the role of the public sector in schooling as one of collecting taxes from households and providing inputs to the learning technology. Public expenditures on schools are determined endogenously. Under plausible restrictions, our model's predictions qualitatively match the observations on schooling, public expenditures on education, and student‐teacher ratios. JEL Classification: E13, E62.

Accumulation de capital humain et dépenses publiques endogènes. Dans ce mémoire, les auteurs présentent un modèle de générations qui se chevauchent où les individus accumulent du capital humain via l'éducation formelle. Le rôle du secteur public dans l'éducation est défini comme celui de collecteur d'impôts auprès des ménages et de fournisseur d'intrants dans la technologie d'apprentissage. Les dépenses publiques en éducation sont déterminées de manière endogène. A partir de restrictions plausibles, les prédictions du modèle s'arriment qualitativement aux observations sur le monde scolaire, aux dépenses publiques en éducation, et aux ratios élèves/enseignants.
Small Business Development and Nonmetropolitan Job Growth in Georgia
Authors: Winders Rebecca
Published: March 2003

To assess development potential of small business, this research examines the age and size characteristics of nonmetropolitan firms and the contribution of business ‘births,’‘deaths,’ expansions, and contractions to job growth. Analysis of data derived from the federal‐state unemployment insurance program in Georgia indicates that firms employing fewer than 100 workers account for 44.3 percent of private sector nonfarm employment in nonmetropolitan counties. Overall, the mix of small and large firms remained quite stable over the five year study period. The dynamics of job creation and loss differed dramatically by enterprise size and manufacturing/nonmanufacturing sector. Three segments of the business population contributed most to rural job growth: very small continuing firms, large manufacturing establishments, and non‐manufacturing businesses owned by large enterprises. The paper concludes with a discussion of economic development policies that may enable rural communities to capitalize on these business demographic trends.
Shift‐Share Analysis and Changes in Japanese Manufacturing Employment
Authors: Hanham Robert Q. , Banasick Shawn
Published: March 2003

Shift‐share analysis is used to examine the role of spatial structure on changes in regional manufacturing employment, in contrast to the traditional focus of shift‐share studies on the role of industrial structure. It is argued that changes in a region's space‐economy can be understood not only in terms of the economic subdivisions of the region but also in terms of the contribution of its spatial subdivisions. The latter is illustrated by means of a case study of the contribution of different types of local area to changes in regional manufacturing employment in Japan. Each region was subdivided into four types of local area based on population density. The analysis covered the period from 1981 to 1995, a time of major transformation in Japan's space‐economy. The shift‐share model was also used to estimate the impact of local area output and productivity on changes in regional employment. In general, the results show that there was a progressive underdevelopment of the core regions, associated with falling output and productivity. The country's peripheral regions were characterized by development, associated with rising output and productivity. Atthe local scale, however, the picture is far more complex. Types of local area contributed to regional employment change in very different ways, with respect to both time, region, and output/productivity. The contribution of local spatial structure to the regional space‐economy of Japan is fundamentally fragmented and uneven.
A Synthesis of Empirical Research on the Impact of Government onLong‐Run Growth
Authors: Poot Jacques
Published: March 2003

This paper provides a synthesis of the 1983–98 published literature on the empirical evidence regarding the interaction between government policies and growth. Five policy areas are considered: general government consumption, tax rates, education expenditures, defense and public infrastructure. The most conclusive results in the literature relate to the positive impact of education expenditures on growth. Public infrastructure also appears important. Regression analysis remains the most commonly adopted research methodology. A better link with current theories will be obtained when parameter calibration methods formicro‐foundations based models replace parameter estimation of regression models with ad hoc specifications. Nonetheless, there remain severe limitations on what can be learned for policy from highly aggregative models of endogenous growth. Better data are needed at the regional macro and meso levels to complement thecurrently available pooled cross‐section time‐series country data. The potential endogeneity of government fiscal variables can be resolved through the selection of appropriate instrumental variables, such as those that arise in cases of “natural experiments”.
The Role of Education in Self–Employment Success in Finland
Authors: Kangasharju Aki , Pekkala Sari
Published: March 2003

This paper analyzes the effect of self–employed persons’ education on the success of their firms during the economic downturn and upturn of the 1990's. It is found that the business cycle affects the relative closure rates of firms run by self–employed with any level of education. Exit probability is lower for the highly educated during bust, but higher in boom. This is accounted for by two facts. First, running a small firm is argued to be a less attractive choice to wage work, particularly for the highly educated, due to lower earning prospects, less stable stream of earnings, and the cultural tradition of working in large corporations. Second, the highly educated faced a higher outside demand for their labor than did the less educated during economic upturn. Finally, it was found that regardless of the state of aggregate economy, firms run by the highly educated have higher growth probabilities than those run by less educated persons.
Determining Prepositional Attachment, Prepositional Meaning, Verb Meaning, and Thematic Roles
Authors: Gomez Fernando , Segami Carlos , Hull Richard
Published: March 2003

An algorithm for semantic interpretation that integrates the determination of the meaning of verbs, the attachment and meaning of prepositions, and the determination of thematic roles is presented. The parser does not resolve structural ambiguity, which is solely the task of the semantic interpreter. Lexical semantic information about nouns and verbs is applied to the resolution of verb polysemy and modifier attachment. Semantic interpretation is centered on the representation of the meaning of the verb, called verbal concept. Verbal concepts are organized into a classification hierarchy. As long as the meaning of the verb remains unknown, parsing proceeds on a syntactic basis. Once the meaning of the verb is recognized, the semantic component makes sense of the syntactic relations built so far by the parser and of those still to be parsed. The algorithm has been implemented and tested on real–world texts.
An Informal Semantic Analysis of Motion Verbs Based on Physical Primitives
Authors: Kalita Jugal K. , Lee Joel C.
Published: March 2003

A representation scheme for verbs and prepositions specifying path and locative information is developed. The representation emphasizes the implementability of the underlying semantic primitives. The primitives pertain to mechanical characteristics such as geometric relationships among objects, force or motion characteristics implied by verbs, and their prepositional modifiers. This representation has been used to animate the performance of tasks underlying natural language imperatives.
Reasoning with Intensional Negative Adjectivals: Semantics, Pragmatics, and Context
Authors: Iwanska Lucja
Published: March 2003

Intensional negative adjectives alleged, artificial, fake, false, former, and toyare unusual adjectives that depending on context may or may not be restricting functions. A formal theory of their semantics, pragmatics, and context that uniformly accounts for their complex mathematical and computational characteristics and captures some peculiarities of individual adjectives is presented.

Such adjectives are formalized as new concept builders, negation‐like functions that operate on the values of intensional properties of the concepts denoted by their arguments and yield new concepts whose intensional properties have values consistent with the negation of the old values. Understanding these new concepts involves semantics, pragmatics and context‐dependency of natural language. It is argued that intensional negative adjectives can be viewed as a special‐purpose, weaker, conntext‐dependent negationin natural language. The theory explains and predicts many inferences licensed by expressions involving such adjectives. Implementation of sample examples demonstrates its computational feasibility. Computation of context‐dependent interpretation is discussed.

The theory allows one to enhance a knowledge representation system with similar concept building, negation‐like, context‐dependent functions, the availability of which appears to be a distinct characteristic of natural languages.
A Temporal Knowledge Representation Approach Based on Elementary Calculus
Authors: Trudel André
Published: March 2003

The standard AI method for representing temporal information in a first‐order logic is to directly associate the information with a time point or interval via a relation. We present a new paradigm for temporal knowledge representation. All point‐based temporal information is translated to real‐valued functions in the Cartesian plane. For example, information that is true/false at a point becomes a 0–1 function. Other types of information, such as velocity, are directly represented with real‐valued functions. The unique feature of the proposed approach is the use of the Riemann integral to represent interval‐based information. Our approach is based on the fact that what is true at every point in an interval completely determines what is true over the interval. We conclude with a formal presentation of a first‐order logic that is based on the proposed representation.
An Action Representation Formalism to Interpret Natural Language Instructions
Authors: Eugenio Barbara Di
Published: March 2003

The focus of this paper is on an action representation formalism that encodes bothlinguistic andplanning knowledge about actions, and that supports the interpretation of complex Natural Language instructions and, in particular, of instructions containing Purpose Clauses. The representation uses linguistically motivated primitives, derived from Jackendoff's work on Conceptual Semantics, and is embedded in the description logic based system CLASSIC. I first motivate the characteristics of the formalism as needed to understand Natural Language instructions. I then describe the formalism itself, and I argue that the integration of a linguistically motivated lexical semantics formalism and of a description logic based system is beneficial to both. Finally, I show how the formalism is exploited by the algorithm that interprets Purpose Clauses. The output of the algorithm is used in theAnimation from NL project, that has as its goal the automatic creation of animated task simulations.
Depth‐First Branch‐and‐Bound versus Depth‐Bounded IDA: New Results
Authors: Prieditis Armand E.
Published: March 2003

In a real‐time task an action must be executed given limited computation. One approach to limited computation is to search a tree of possible action sequences to a fixed depth and then execute an action with the lowest associated backed‐up cost. The standard algorithm for such a search is Depth‐First Branch‐and‐Bound (DFBB), also known in the Artificial Intelligence literature as Minimin with Alpha Pruning. This article shows that a depth‐bounded extension of a popular iterative algorithm called IDA has a surprisingly large range of search trees on which it outperforms DFBB—something previous analytical results do not predict. We prove that the extended algorithm, which we call DIDA, is correct, is guaranteed to terminate, and is asymptotically (i.e., on its last iteration) as efficient as DFBB—assuming a consistent heuristic is used. We also prove that both algorithms are guaranteed not to decrease their accuracy with a deeper search, assuming a consistent heuristic. Because accuracy is generally correlated with decision quality, the time saved by visiting fewer states translates to deeper searches which translates to better decisions. Results from random search trees show that DIDA is most efficient when the path cost + leaf node heuristic value is distributed with low variance; as branching factor increases, the range for which DIDA is more efficient also increases. Results with Eight, Fifteen, Twenty‐four, and Ninety‐nine Puzzle implementations of both algorithms—all domains with low variance of path cost + leaf node heuristic value—show that DIDA significantly outperforms DFBB.
Expressing Time Intervals and Repetition Within a Formalization of Calendars
Authors: Cukierman Diana , Delgrande James P.
Published: March 2003

We investigate a formal representation of time units, calendars, and time unit instances as restricted temporal entities for reasoning about repeated events. We generalize Allen's interval relations to a class level, and based on interval classes we define time units. We examine characteristics of time units, and provide a categorization of the hierarchical relations among them. Hence we define an abstract hierarchical unit structure (a calendar structure) that expresses specific relations and properties among the units that compose it. Specific objects in the time line are represented based on this formalism, including nonconvex intervals corresponding to repeated events. A goal of this research is to be able to represent and reason efficiently about repetition in time.
Knowledge Discovery in Complex Objects
Authors: Faïd Mourad , Missaoui Rokia , Godin Robert
Published: March 2003

Learning concepts and rules from structured (complex) objects is a quite challenging but very relevant problem in the area of machine learning and knowledge discovery. In order to take into account and exploit the semantic relationships that hold between atomic components of structured objects, we propose a knowledge discovery process, which starts from a set of complex objects to produce a set of related atomic objects (called contexts). The second step of the process makes use of the concatenation product to get a global context in which binary relations of individual contexts coexist with relations produced by the application of some operators to individual contexts. The last step permits the discovery of concepts and implication rules using the concept lattice as a framework in order to discover and interpret nontrivial concepts and rules that may relate different components of complex objects. This paper focuses on two main steps of the knowledge discovery process, namely data mining and interpretation.
Efficient Implementation of Semantic Relations in Lexical Databases
Authors: Priss Uta
Published: March 2003

In this paper we develop a formalization of semantic relations that facilitates efficient implementations of relations in lexical databases or knowledge representation systems using bases. The formalization of relations is based on a modeling of hierarchical relations in Formal Concept Analysis. Further, relations are analyzed according to Relational Concept Analysis, which allows a representation of semantic relations consisting of relational components and quantificational tags. This representation utilizes mathematical properties of semantic relations. The quantificational tags imply inheritance rules among semantic relations that can be used to check the consistency of relations and to reduce the redundancy in implementations by storing only the basis elements of semantic relations. The research presented in this paper is an example of an application of Relational Concept Analysis to lexical databases and knowledge representation systems (cf. Priss 1996) which is part of a larger framework of research on natural language analysis and formalization.
Tackling the Qualification Problem using Fluent Dependency Constraints
Authors: Kvarnström Jonas , Doherty Patrick
Published: March 2003

In the area of formal reasoning about action and change, one of the fundamental representation problems is providing concise modular and incremental specifications of action types and world models, where instantiations of action types are invoked by agents such as mobile robots. Provided the preconditions to the action are true, their invocation results in changes to the world model concomitant with the goal‐directed behavior of the agent. One particularly difficult class of related problems, collectively called the qualification problem, deals with the need to find a concise incremental and modular means of characterizing the plethora of exceptional conditions that might qualify an action, but generally do not, without having to explicitly enumerate them in the preconditions to an action. We show how fluent dependency constraints together with the use of durational fluents can be used to deal with problems associated with action qualification using a temporal logic for action and change called TAL‐Q. We demonstrate the approach using action scenarios that combine solutions to the frame, ramification, and qualification problems in the context of actions with duration, concurrent actions, nondeterministic actions, and the use of both Boolean and non‐Boolean fluents. The circumscription policy used for the combined problems is reducible to the first‐order case.
Model‐Based Visualization of Temporal Abstractions
Authors: Shahar Yuval , Cheng Cleve
Published: March 2003

We describe a new conceptual methodology and related computational architecture called Knowledge‐based Navigation of Abstractions for Visualization and Explanation (KNAVE). KNAVE is a domain‐independent framework specific to the task of interpretation, summarization, visualization, explanation, and interactive exploration, in a context‐sensitive manner, of time‐oriented raw data and the multiple levels of higher level, interval‐based concepts that can be abstracted from these data. The KNAVE domain‐independent exploration operators are based on the relations defined in the knowledge‐based temporal‐abstraction problem‐solving method, which is used to abstract the data, and thus can directly use the domain‐specific knowledge base on which that method relies. Thus, the domain‐specific semantics are driving the domain‐independent visualization and exploration processes, and the data are viewed through a filter of domain‐specific knowledge. By accessing the domain‐specific temporal‐abstraction knowledge base and the domain‐specific time‐oriented database, the KNAVE modules enable users to query for domain‐specific temporal abstractions and to change the focus of the visualization, thus reusing for a different task (visualization and exploration) the same domain model acquired for abstraction purposes. We focus here on the methodology, but also describe a preliminary evaluation of the KNAVE prototype in a medical domain. Our experiment incorporated seven users, a large medical patient record, and three complex temporal queries, typical of guideline‐based care, that the users were required to answer and/or explore. The results of the preliminary experiment have been encouraging. The new methodology has potentially broad implications for planning, monitoring, explaining, and interactive data mining of time‐oriented data.