The effects of a chemosterilant (Mestranol) on population and behavior in the Richardson's ground squirrel (Spermophilus richardsonii) in Alberta

A chemosterilant, mestranol, was administered to three populations of Richardson's ground squirrel in southeastern Alberta. Mestranol was given to all squirrels in one plot, to only 50 percent in another plot, while a third plot remained as control. In all plots social behavior and population dynamics were followed over two seasons by live trapping and visual observations. Mestranol sterilized all females who received the drug shortly before or in early pregnancy; accordingly the birth rates were reduced. Levels of total aggression were also reduced but increased survival and immigration rates nullified the effects of the treatment during the first season. During the second season, low birth rates due to repeated treatment in one plot and to adult emigration and unknown causes in the other, were not compensated for by immigration. As a result of the repeated mestranol treatment and in one case also of adult emigration, the numbers of squirrels were reduced in the vicinity, thus limiting potential immigration in the treated plots. As a consequence, both treated populations crashed, demonstrating the effectiveness of mestranol

Expansions des innovations par retrait : éléments de caractérisation et de réflexion

L'étude sociologique des innovations propose des modèles génériques d'analyse rendant compte de la façon dont les inventions voient le jour et s'inscrivent dans la société. Le modèle diffusionniste, par exemple, rend compte des mécanismes de diffusion des nouveautés au sein d'une population d'adoptants (Rogers, 1962). Le modèle de la traduction (Akrich, Callon et al., 1988), de son côté, invite à décrire les déplacements et transformations qui permettent aux réseaux sociotechniques de s'étendre ; il s'agit alors de considérer les innovations comme des réagencements de relations entre entités de toutes sortes (acteurs, objets, institutions, normes), redéfinies chemin faisant. Ces transformations, et notamment le sens que les acteurs sociaux leur confèrent, constituent des supports privilégiés d'observation des mutations des sociétés (Vinck 2012). Elles fournissent ainsi des informations anthropologiques précieuses sur les façons dont ces sociétés se transforment et pensent ces transformations ou leur conduite. Parmi les multiples formes de processus d'innovation qui affectent les technologies, les marchés, l'alimentation, l'environnement et les relations à autrui, certaines sont associées non pas à l'introduction d'une nouveauté mais au retrait ou à la suppression d'un élément préexistant. Ce retrait est au coeur d'une série de transformations. Elles sont utiles à comprendre pour l'analyse des innovations elles-mêmes, mais aussi pour ce qu'elles donnent à voir des trajectoires de changement de nos sociétés. Dans cet article, nous discuterons de quelques propriétés de certaines innovations que avons qualifiées d'innovations par retrait (Goulet & Vinck, 2012). Nous examinerons leurs formes, ainsi que les logiques ou valeurs animant les acteurs qui les portent. Nous mettrons au jour quelques pistes de réflexion liées à cette manière de penser l'innovation autrement que comme l'insertion d'une nouveauté au sein de la société

A inovação por sustração : contribução para a sociología do distanciamento

To develop the understanding of innovation processes conceptualized in terms of association through the "sociology of translation" (cf. actor-network theory) studies, this article analyses innovation processes in terms of dissociation and detachment mechanisms, examining innovation through "withdrawal"; that is, innovation based on reducing or withdrawing use of a practice - "subtracting", "detaching" - a given artefact. Specifically, it focuses on the shift to farming techniques that have eliminated ploughing, bringing to light four major mechanisms constitutive of dissociation : centrifugal association ; making entities and associations visible ; making other entities and associations invisible; bringing together or " associating " new entities. The study helps refine our understanding of the detachment processes at work in innovation

Investment Behavior and the Small Firm Effect

Our purpose in this review is to develop one explanation of market behavior which is consistent with the many empirical findings that appear to be inconsistent with the market efficiency hypothesis. To date, researchers have attempted to reconcile their empirical results with market efficiency based on either measurement error or structural inefficiencies. We propose a different approach to market efficiency. We posit that the empirical findings previous researchers report are by their nature ex post, and are a direct result of a market which is best described as efficient. We develop a model and provide a simulation to support this explanation

Évaluation de la capacité de rétention des métaux dissous d'un marais artificiel en utilisant le périphyton et le gastéropode Helisoma trivolvis

Le but de cette étude est de déterminer si le périphyton et le gastéropode pulmoné Helisoma trivolvis peuvent être utilisés pour évaluer la capacité de rétention des métaux dissous d'un marais construit. Cette étude a été menée dans un marais de la région d'Ottawa-Carleton (Ontario, Canada), qui a été construit en 1995 afin d'améliorer la qualité des eaux de ruissellement provenant d'un bassin versant à usage résidentiel et agricole. Au cours du mois de septembre 1999, des échantillons d'eau ont été prélevés, des escargots (H. trivolvis) ont été recoltés et un substrat artificiel a été utilisé pour faire croître du périphyton, à l'entrée et à la sortie d'eau du marais. En moyenne, les calculs de balance de masse indiquaient une rétention des formes dissoutes du Cu, Mn, Ni et Zn dans le marais. Cependant, les tendances observées pour les concentrations de métaux dissous et pour les concentrations dans les organismes différaient pour certains métaux. Les concentrations de Cd et Ni dans les tissus de H. trivolvis et le périphyton étaient significativement plus élevées à l'entrée qu'à la sortie. Cependant, les concentrations de Cr et Al dans les organismes n'étaient pas significativement différentes entre l'entrée et la sortie alors que celle de Mn était significativement plus élevée à la sortie du marais. Pour tous les métaux sauf le Cd et le Zn, les concentrations dans le périphyton étaient en moyenne plus elevées que celles dans les escargots. Le périphyton peut donc fournir une mesure plus conservatrice de la contamination du milieu pas les métaux. Cette étude montre l'importance de considérer, non-seulement les mesures chimiques, mais aussi les mesures biologiques, dans l'évaluation de l'efficacité d'un ouvrage de contrôle de pollution.Urban and agricultural development has had a significant impact on the water quality of rivers and lakes around the world. In the last few decades, constructed wetlands have been designed as wastewater treatment systems to prevent water quality deterioration in natural receiving waters. Constructed wetlands are built because they are considered sinks for many pollutants thereby protecting the water quality of downstream ecosystems. The treatment performance of these wetlands is generally assessed using mass balance calculations. However, the retention of metals by constructed wetlands is highly variable and the factors involved are still poorly understood. If wetlands are sinks for metals, the metal content of organisms should be lower downstream than upstream. In this context, organisms can be useful to assess the retention or transformation of metals by wetlands.The objective of this study was to determine whether periphyton and the gastropod Helisoma trivolvis could be used to evaluate the retention of dissolved metals in a constructed wetland. H. trivolvis is a freshwater pulmonate snail widespread in ponds across North America. It feeds mostly on periphyton and is more or less sedentary. Snails have been used as biomonitors because several species are metal tolerant. However, compared to snails, periphytic microorganisms may track more closely dissolved metal concentrations as they take up metals principally from the water column.This study was conducted at the Monahan Pond in Kanata, Ontario (Canada). This wetland was built in 1995 to treat run-off from an agricultural and residential watershed. Water chemistry samples, snails and periphyton grown on artificial substrata were collected at both the inlet and the outlet of the wetland in the fall of 1999. Tissue samples were digested with concentrated nitric acid and metal analyses were done by ICP-MS (Inductively Coupled Plasma Mass Spectrometry). During the experiment several chemical parameters differed between the inlet and the outlet. Alkalinity was significantly higher at the inflow and all major cation concentrations were higher at the inflow. The temperature was on average 3 ºC higher at the outlet. Mass balance calculations showed that the wetland was a sink for most dissolved metals. Snails and periphyton tissue metal concentrations were higher at the inflow than at the outlet for Cd and Ni. However, no significant differences were observed between inflow and outlet tissue concentrations for Cr and Al, whereas Mn was actually significantly higher at the outlet. As a result, the metal content of the organisms did not consistently reflect the dissolved metal concentrations in water. For all metals except Cd and Zn, periphyton concentrations were on average higher than snail metal concentrations. Periphyton analyses can provide a more conservative measure of metal contamination and, when artificial substrates are used, correspond to defined and known periods of exposure.This study demonstrates that constructed wetlands may lead to increased metal content of downstream organisms even if these wetlands appear to be overall sinks for dissolved metals based on mass balance calculations. It also shows the need to consider not only metal concentrations, but also biological data when assessing the performance of pollution control facilities

FINANCE THEORY AND THE NEW INVESTOR RELATIONS

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73515/1/j.1745-6622.1993.tb00382.x.pd

VARIATIONS IN PITCHING PERFORMANCE DURING A MAJOR LEAGUE BASEBALL GAME: WHAT CAN WE LEARN FROM BALL TRACKING DATA?

The aim of this study was to identify changes in pitching characteristics during nine innings of professional (MLB) baseball. Ball tracking data were obtained for 1,514,304 pitches thrown by 129 pitchers during the 2008–2014 MLB seasons and compared across the nine innings using linear mixed model analyses. Earlier innings contained significantly more hard (i.e., fast-type) pitches. A significant decrease in pitch speed and release height emerged before the sixth inning. These data revealed that aspects of a starting pitcher’s performance significantly change as early as the second or third inning of an MLB game, although these do not influence his effectiveness. Coaches may use these data to inform their decision to relieve a starting pitcher and/or direct in-game strategies to exploit trends in pitcher performance

La agroecología en Argentina y en Francia : miradas cruzadas

Las reflexiones presentadas en esta obra encuentran su origen en un cruce interdisciplinario de miradas sobre el modo en que el campo de la agroecología se fue desarrollando en Francia y en Argentina. El contexto de esta reflexión está marcado por fuertes transformaciones en los modos de producción agropecuaria y en las formas de agenciarse los territorios rurales, transformaciones que provocan desafíos medioambientales, sociales yde riesgo climático. En este marco, "la agroecología" se impuso como uno de los espacios conceptuales que permiten pensar el desarrollo de la durabilidad de los modos de producción en contextos geográficos y agrícolas muy diferentes. Mientras que en Francia aparece un escenario agrorural más homogéneo en dónde habría simples variantes u opciones en el seno de un mismo modelo genérico, o como los productos diferenciados de un mismo gran sistema de conocimiento, en Argentina, se observa la yuxtaposición, a veces anodina, a veces problemática, incluso brutal, de la agricultura llamada "familiar" junto a un modelo que se autoproclama "agribusiness" (basado en biotecnologías, gerenciamiento moderno y nuevas tecnologías informáticas y comunicacionales). En ambos casos, si bien contrastan sus respectivos contextos económicos, sociales y productivos, se plantea de manera urgente la cuestión de los modelos de producción agrícola a privilegiar - o por el contrario a descartar - para asegurar un desarrollo sustentable de las regiones y de las poblaciones concernidas. Por el lado argentino, los conflictos por el acceso a la tierra, la seguridad alimentaria nacional, la salud de las poblaciones rurales y el impacto medioambiental por el uso elevado de agroquímicos son temas que indican aquella urgencia. En Francia, además de estas cuestiones, también existen debates acerca del impacto energético intensivo, la calidad de los alimentos o la naturaleza de los circuitos de distribución, todas problemáticas que alimentan hoy las reflexiones vinculadas al auge de la agroecología. Tanto en Argentina como en Francia las controversias en torno de estos problemas se plantean de manera extremadamente compleja. Las respuestas requieren transformaciones radicales de los modos de desarrollo, conciernen a una gran diversidad de actores (productores, industriales, poderes públicos, consumidores, etc.), cuyas expectativas y desafíos son, a menudo, difíciles de conciliar a corto o mediano plazo. [...