bluuebunny/crossref_metadata_2025_split huggingface dataset:
Short‐Term Plasticity of Hippocampal Neuropeptides and Neuronal Circuitry in Experimental Status Epilepticus
Authors: Wasterlain Claude G. , Mazarati Andrey M. , Naylor David , Niquet Jerome , Liu Hantao , Suchomelova Lucie , Baldwin Roger , Katsumori Hiroshi , Shirasaka Yukiyoshi , Shin Don , Sankar Raman 
Published: March 2003

Summary:  Purpose: We used a model of self‐staining status epilepticus (SSSE), induced by brief intermittent stimulation of the perforant path in unanesthetized rats, to study the mechanism of initiation and of maintenance of SSSE and the role of neuropeptides in those processes.Methods: The perforant path was stimulated intermittently for 7 min (ineffective stimulation) or 30 min (generating SSSE). Peptides and their agonists and antagonists were delivered either intraperitoneally, or directly into the hippocampus through a implanted cannula. Behavior and electroencephalogram (EEG) were recorded through a videotape‐telemetry system with automatic spike and seizures detection programs, which were supplemented by manual review of the records to confirm the diagnosis. Immunocytochemistry and enzyme‐linked immunosorbent assay followed published methods.Results: Initiation of SSSE was blocked by many agonists of inhibitory neurotransmitters or neuromodulators, and by many antagonists of excitatory synapses, and was facilitated by agents with the opposite action, suggesting the activation of a complex circuit with multiple potential entry points. Once SSSE was established, however, only N‐methyl‐d‐aspartate (NMDA)‐receptor ligands and a few neuropeptides had major effects on its maintenance. Galanin and dynorphin had powerful anticonvulsant roles in the maintenance phase of SSSE, whereas somatostatin and neuropeptide Y suppressed seizures only transiently. SSSE seemed to induce maladaptive changes in neuropeptides: it depleted the hippocampus of the galanin‐ and dynorphin‐immunoreactive (IR) fibers, which normally function as endogenous anticonvulsants; whereas it induced overexpression of the proconvulsant neuropeptides substance P and neurokinin B; however, late in the course of SSSE, galanin‐IR interneurons appeared in the dentate hilus.Conclusions: Initiation of SSSE seems to involve a circuit with many points of entry, and blockage of any point along this circuit inhibits the development of SSSE. Far fewer agents alter the maintenance phase of SSSE. Galanin, dynorphin, somatostatin, and neuropeptide Y have anticonvulsant roles, matching the previous described convulsant role of substance P and neurokinin B. Galanin and dynorphin seem to undergo maladaptive changes, which appear to play an important role of the maintenance phase of SSSE. Later, the de novo expression of inhibitory neuropeptides in novel cells in hippocampus coincides with the waning of seizures and may play a role in their termination.
Veratridine, But Not Elevated K+, Inhibits Excitatory Amino Acid Transporter Activity in Rat Hippocampal Slices
Authors: Claudio O. I. , Berríos N. , García M. , Casasnovas R. , Ortiz J. G. 
Published: March 2003

Summary: Purpose:Excitatory amino acid transporter (EAAT) activity prevents Glu from reaching toxic levels, but their contribution to epileptogenesis remains controversial. We examined how the convulsant veratridine causes inhibition of EAAT activity and how it differs from the effects of another convulsant, high (50 mM) K+, that also increases Na+conductance.Methods:Transverse rat hippocampal slices were incubated for 1 h with 100 μMveratridine in oxygenated artificial cerebrospinal fluid (aCSF) with or without extracellular Ca2+. The medium was replaced by 50 μM[3H]glutamate in aCSF, and the slices incubated for 10 min at 37°C. The slices were washed 3 times with cold aCSF after removal of the extracellular medium, and the radioactivity was quantified after solubilization of the slices.Results:Veratridine caused a time‐ and dose‐dependent decrease, whereas high K+had no effect on EAAT activity. The effects of veratridine on EAAT activity were not prevented by tetrodotoxin (TTX; 10 μM). Coincubation of ouabain with veratridine resulted in further decreases of EAAT activity. Removal of extracellular Ca2+potentiated the inhibitory effects of veratridine (and other convulsants) on EAAT activity. Chelation of intracellular Ca2+with BAPTA also increased the inhibitory effects of veratridine on EAAT activity.Conclusions:Veratridine caused changes Ca2+dynamics that led to inhibition of EAAT activity. Such changes in EAAT activity can contribute to the sustained epileptiform activity caused by veratridine.
Host plant choice and location by larvae of the wheat bulb fly (Delia coarctata)
Authors: Marriott C. , Evans K. A. 
Published: March 2003

AbstractWheat bulb fly (Delia coarctata Fallen, Diptera: Anthomyiidae) is an important pest of winter wheat in the eastern half of the UK, and in northern and eastern Europe. The larvae must find a host plant and invade a tiller soon after hatching in late January. Chemical controls are costly and weather conditions may reduce their efficacy or prevent their application. Post‐emergence control relies on organophosphate insecticides, which may soon be withdrawn due to concerns about their negative health and environmental effects. Winter wheat (Triticum aestivum L.) is the preferred cereal host, but other winter cereals and related grasses may also be attacked, while oats (Avena spp.) are shunned. In choice test bioassays, neonate larvae chose couch grass (Elytrigia repens (L.) Nevski syn. Elymus repens (L.) Gould, Agropyearon repens (L.) Beauv.) seedlings and exudates over wheat seedlings and exudates, and exhibited geotaxis and negative phototaxis. Analysis of larval trails in choice test bioassays of seedling exudates showed that couch exudates are more attractive than wheat exudates, and that wheat exudates are more arrestant than couch exudates. This suggests that infochemicals isolated from couch, wheat, and oats could be used in wheat bulb fly control; possible delivery mechanisms are discussed. These findings, previous research, and a comparison of the phenologies and geographical distributions of D. coarctata and its hosts suggest that E. repens is the natural host of D. coarctata.
Effect of neonicotinoid synergists on entomopathogenic nematode fitness
Authors: Koppenhöfer Albrecht M. , Cowles Richard S. , Cowles Elizabeth A. , Fuzy Eugene M. , Kaya Harry K. 
Published: March 2003

AbstractIn previous greenhouse and field studies, the neonicotinoid insecticide imidacloprid interacted synergistically with five entomopathogenic nematode species against five scarab species. Two other neonicotinoids, thiamethoxam and acetamiprid, showed a weaker interaction with nematodes in scarab larvae. Entomopathogenic nematodes have the potential to recycle in hosts after inundative applications, thereby increasing the persistence of nematodes and insect control. Thus we investigated the effect of neonicotinoids on nematode fitness after tank mixing and after combined applications. Tank mixing only had a negative effect on nematode survival and infectivity in a few nematode–insecticide combinations and only if both insecticide concentration and exposure time were several times higher than typical for field applications. Combined application of nematodes with imidacloprid generally had no negative effect on the percentage of scarab cadavers producing progeny or the number of nematode progeny emerging per cadaver. In experiments with a synergistic increase in scarab mortality, the total number of progeny in combination treatments was up to four times higher than in nematodes only treatments. Similarly, nematode populations in soil from combination treatments were 13.2 times greater than for nematodes only treatments at 28 days after treatment. Combined imidacloprid–nematode applications did not affect the pathogenicity or infectivity of the nematode progeny. Combining thiamethoxam with nematodes had no negative effects on nematode reproduction in the majority of treatments. However, due to the weaker interaction of thiamethoxam and nematodes on scarab mortality, the total number of nematode progeny per treatment generally did not increase compared with nematodes only treatments. The demonstrated tank mix compatibility of imidacloprid and nematodes improves the feasibility of combining these agents for curative white grub control. The positive effect of imidacloprid on nematode reproduction after combined application may increase the likelihood of infection of white grubs by subsequent generations of nematodes, thereby improving their field persistence and biological control potential.
Effects of mowing frequency on densities of natural enemies in three Pacific Northwest pear orchards
Authors: Horton David R. , Broers Debra A. , Lewis Richard R. , Granatstein David , Zack Richard S. , Unruh Thomas R. , Moldenke Andrew R. , Brown John J. 
Published: March 2003

AbstractEffects of mowing frequency on ground cover composition and on numbers of predators, parasitoids, and select phytophagous arthropods in the ground cover of three reduced‐insecticide pear orchards were determined. Concurrent samples taken in the tree canopy (with beating trays) and in the herbicide strips on the orchard floor (with pitfall traps) tested whether counts of natural enemies in these two habitats were also affected by mowing regime. A reduction in frequency of mowing from two to three times per month (= control) to once per month or once per growing season led to increased cover of grasses, broadleaf plants, and broadleaf plants in flower. Sweep net samples of natural enemies in the ground cover were dominated numerically by spiders (Araneae), parasitic Hymenoptera, and predatory Heteroptera, with lesser numbers of other taxa (Syrphidae, Neuroptera, Coccinellidae). Predators and parasitoids showed substantial increases in numbers associated with decreased mowing frequency. Sweep net counts of aphids, Lygus spp. (Heteroptera: Miridae), and leafhoppers/planthoppers, all potential prey of predators, also increased significantly with decreased mowing frequency. In the pitfall samples, only the European earwig (Forficula auricularia L.) (Dermaptera: Forficulidae) exhibited a change in counts associated with mowing treatment; numbers of earwigs in pitfall traps declined as mowing frequency decreased. For the beat tray samples, mean tray counts for most natural enemy taxa were higher in the less frequently mowed plots, but significantly (P < 0.05) so only for two taxa: spiders and a predatory mirid, Deraeocoris brevis (Uhler) (Heteroptera: Miridae). It remains to be determined whether biological control of pests in the tree canopy can be enhanced by manipulating mowing frequency. Questions raised by this study include whether there is extensive movement by natural enemies between the ground cover and tree canopy, and whether plot size affects the likelihood of showing that mowing frequency influences predator densities in the tree canopy.
Free trade agreements without delocation
Authors: Baldwin Richard E. , Robert‐Nicoud Frederic 
Published: March 2003

Small nations fear that FTAs with larger, richer nations will erode their industrial bases. These concerns are recognized in FTA and multilateral talks: small nations may explicitly or implicitly maintain higher trade barriers. Using a model where symmetric liberalization de‐industrializes small, poor nations, we characterize the path of protection‐asymmetries that allow liberalization without delocation. In welfare terms, the large nation prefers this no‐delocation liberalization scheme only when barriers are sufficiently high; the small nation's ranking is reversed. An anti‐delocation scheme involving international income transfers is also evaluated and found infeasible. Accords de libre‐échange quand il y a délocalisation. Les petits pays craignent que les accords de libre‐échange avec des pays plus grands et plus riches n'entament leur base industrielle. Ces malaises sont reconnus dans les négociations bilatérales et multilatérales: on permet aux petits pays de maintenir explicitement ou implicitement des barrières commerciales plus élevées. A l'aide d'un modéle où la libéralisation des échanges engendre une désindustrialisation des petits pays pauvres, les auteurs identifient les niveaux d'asymétrie dans le niveau de protection qui permettent d'engendrer une désindustrialisation sans délocalisation. En termes de niveau de bien‐être, le grand pays préfère cet arrangement sans délocalisation seulement quand les barrières commerciales sont suffisamment élevées; la préférence des petits pays est à l'inverse. On évalue un arrangement sans délocalisation impliquant des transferts internationaux de revenus, et on montre qu'il est impraticable.
TRIMs, environmental taxes, and foreign investment
Authors: Chao Chi‐Chur , Yu Eden S.H. 
Published: March 2003

Various second‐best policy mixes of investment measures and environmental taxes for a polluted, small open economy with foreign capital and immovable trade restrictions are examined. The optimal policy mix depends on the types of trade restrictions. When tariffs are in place, strict policies of pollution taxes and export requirements are optimal for alleviating tariff‐induced consumption and production distortions. When involuntary quotas are used in lieu of tariffs, however, the optimal policy mix is a zero export requirement and Pigouvian taxes on pollution. For the case of VERs, however, the optimal policy demands export requirements and a less stringent pollution tax. TRIMs, impôts environnementaux et investissement étranger. Ce mémoire examine certains ensembles de politiques de second‐ordre portant sur l'investissement et les impôts environnementaux dans une petite économie ouverte polluée où il y a capital étranger et restrictions au commerce international. Quand on a des droits de douane en place, des politiques de fiscalité environnementale et d'exportations requises sont optimales pour corriger les distorsions aux patterns de production et de consommation engendrées par les droits de douane. Cependant quand des contingentements involontaires sont en place plutôt que des droits de douane, le mélange optimal de politiques est de ne pas requérir d'exportation mais d'imposer des taxes à la Pigou sur la pollution. Pour ce qui est des restrictions volontaires à l'exportation, le mélange optimal de politiques réclame une taxe moins forte sur la pollution accompagnée par un certain niveau d'exportation requis.
Did tax flattening affect RRSP contributions?
Authors: Veall Michael R. 
Published: March 2003

In 1988 marginal personal income tax rates changed in Canada, for some individuals by reasonably substantial amounts. In this note a large sample of tax‐filer data is examined and the conclusion is drawn that, when attention is paid to the possible confounding of marginal tax rate and non‐linear income effects, there is no convincing evidence that the tax rate changes affected contributions to Registered Retirement Saving Plans (RRSPs). Est‐ce que l'aplatissement des taux d'imposition influence les contributions au REER? En 1988, les taux marginaux d'imposition du revenu personnel ont changé au Canada, et, pour certaines personnes, ces changements ont été substantiels. Cette note examine un grand échantillon de rapports d'impôts et en arrive à la conclusion que, quand on prend en compte le mélange possible des effets du taux marginal d'imposition et des effets de revenu non‐linéaires, il n'y a pas de résultats qui montrent de façon probante que les changements dans les taux d'imposition ont influencé les contributions au REER.
Education, earnings, and the ‘Canadian G.I. Bill’
Authors: Lemieux Thomas , Card David 
Published: March 2003

Canadian Second World War veterans benefited from an extensive educational program similar to the U.S. G.I. Bill. Because of differences in military enlistment rates, however, a much lower fraction of Quebec men were eligible for these benefits than men from other provinces. Building on this fact, we analyse inter‐cohort patterns of education and earnings for English‐speaking men from Ontario, using French‐speaking men from Quebec as a control group. We find that the instrumental variables estimates of the return to schooling are typically as big or bigger than the corresponding OLS estimates. JEL Classification: J24, I21 Education, revenus, et le ‘G.I. Bill canadien.’ Les anciens combattants canadiens de la deuxième guerre mondiale ont bénéficié d'un programme d'aide aux études similaire au G.I. Bill américain. Relativement peu de Québécois ont cependant pu bénéficier de ce programme en raison de la faible proportion de ces derniers qui ont fait leur service militaire durant cette période. Sur la base de cette observation, nous analysons les différences intergénérationelles dans la scolarisation et les revenus des Ontariens anglophones en se servant des Québécois francophones comme groupe témoin. Nos résultats indiquent que les estimés du taux de rendements de l'éducation obtenus à l'aide de la méthode des variables instrumentales sont comparables sinon plus élévés que ceux obtenus par moindres carrés ordinaires.
An empirical analysis of intergovernmental tax interaction: the case of business income taxes in Canada
Authors: Hayashi Masayoshi , Boadway Robin 
Published: March 2003

Both federal and provincial governments in Canada levy corporate taxes on businesses in their jurisdictions, which potentially gives rise to horizontal and vertical tax externalities within the federation. Using a simple model of interdependent tax choices, we estimate tax‐setting functions for the federal government, Ontario, Quebec, and an aggregate of the remaining eight provinces. We find evidence of significant vertical and horizontal tax interactions. Provincial tax rates respond negatively to the federal tax rate, while at least some provinces increase their tax rates in response to increases in the tax rates of other provinces. JEL Classification: H25, H7 Une analyse empirique de l'interaction fiscale entre gouvernements: le cas des impôts sur les revenus d'affaires au Canada. Au Canada, les gouvernements fédéral et provinciaux collectent des impôts sur le revenu de sociétés sous leur jurisdiction. Voilà qui peut donner lieu à des effets externes horizontaux et verticaux à l'intérieur de la fédération. A l'aide d'un modèle de choix fiscaux interdépendants, les auteurs calibrent les fonctions d'imposition du gouvernement fédéral, des gouvernements du Québec et de l'Ontario, et d'une entité composée des huit autres provinces. On montre que les effets verticaux et horizontaux d'interaction fiscale sont significatifs. Les taux d'imposition des provinces réagissent négativement au taux d'imposition fédéral, mais certaines provinces accroissent leur taux d'imposition en réponse à des accroissements dans les taux d'imposition d'autres provinces.
Bootstrap inference in econometrics
Authors: MacKinnon James G. 
Published: March 2003

The astonishing increase in computer performance over the past two decades has made it possible for economists to base many statistical inferences on simulated, or bootstrap, distributions rather than on distributions obtained from asymptotic theory. In this paper, I review some of the basic ideas of bootstrap inference. I discuss Monte Carlo tests, several types of bootstrap test, and bootstrap confidence intervals. Although bootstrapping often works well, it does not do so in every case. Inférence par la méthode d’auto–amorçage (bootstrap) en économétrie. L’incroyable accroissement dans la puissance des ordinateurs au cours des deux dernières décennies a permis aux économistes de fonder plusieurs inférences sur des distributions simulées, ou obtenues par auto–amorçage, plutôt que sur des distributions obtenues par la théorie aymptotique. Dans ce texte, l’auteur passe en revue quelques–unes des idées de base de l’inférence par la méthode d’auto–amorçage. Le texte discute aussi des tests de Monte Carlo, de divers types de tests et des intervalles de confiance obtenus par la méthode d’auto–amorçage. Même si le processus d’auto–amorçage fonctionne souvent bien, cela n’est pas toujours le cas.
The Struggle for Tamil Eelam in Sri Lanka
Authors: Stokke Kristian , Ryntveit Anne Kirsti 
Published: March 2003

Regionalism has commonly been expected to dissolve as a consequence of the administrative regional penetration of the centralized modern state and the homogenizing forces associated with modernization. This mode of reasoning has reappeared recently among authors who see globalization as a universal force that will eradicate regional economic inequalities, local identities and regional political mobilization. Contrary to these expectations, regional autonomy movements continue to play a central political role within many states. Consequently, it remains an important analytical challenge to understand the construction and politicization of regional interests.Against this background, the article presents a critical interpretation and contextual analysis of Tamil separatism in Sri Lanka. It is argued that studies of nationalist movements should seek inspiration in the contemporary dialog between three main perspectives on social movements (theories of new social movements, resource mobilization theories, and theories of collective identity) and a corresponding three‐dimensional understanding of place (location, locale, and sense of place). The paper shows how nationalist mobilization cannot be reduced to essentialist notions of primordial nations, territorial nation‐states, or internal colonialism, but instead should be understood as the outcome of cultural and political practices by a multitude of actors, operating in time‐ and place‐specific contexts.