Trois essais en théorie microéconomique

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal

In vitro characterisation of fresh and frozen sex-sorted bull spermatozoa

peer-reviewedThis study sought to compare the in vitro characteristics of fresh and frozen non-sorted (NS) and sex-sorted (SS) bull spermatozoa. Experiment 1: Holstein–Friesian ejaculates (n = 10 bulls) were split across four treatments and processed: (1) NS fresh at 3 × 106 spermatozoa, (2) X-SS frozen at 2 × 106 spermatozoa, (3) X-SS fresh at 2 × 106 spermatozoa and (4) X-SS fresh at 1 × 106 spermatozoa. NS frozen controls of 20 × 106 spermatozoa per straw were sourced from previously frozen ejaculates (n = 3 bulls). Experiment 2: Aberdeen Angus ejaculates (n = 4 bulls) were split across four treatments and processed as: (1) NS fresh 3 × 106 spermatozoa, (2) Y-SS fresh at 1 × 106 spermatozoa, (3) Y-SS fresh at 2 × 106 spermatozoa and (4) X-SS fresh at 2 × 106 spermatozoa. Controls were sourced as per Experiment 1. In vitro assessments for progressive linear motility, acrosomal status and oxidative stress were carried out on Days 1, 2 and 3 after sorting (Day 0 = day of sorting. In both experiments SS fresh treatments had higher levels of agglutination in comparison to the NS fresh (P < 0.001), NS frozen treatments had the greatest PLM (P < 0.05) and NS spermatozoa exhibited higher levels of superoxide anion production compared with SS spermatozoa (P < 0.05). Experiment 1 found both fresh and frozen SS treatments had higher levels of viable acrosome-intact spermatozoa compared with the NS frozen treatments (P < 0.01).ACCEPTEDpeer-reviewe

LES CONSÉQUENCES DES PROGRAMMES DE CONTRÔLE DES ÉVALUATIONS FONCIÈRES SUR LES TAUX DE TAXATION MUNICIPALE DES ENTREPRISES : LE CAS DE LA NOUVELLE-ÉCOSSE

La bulle immobilière du début du siècle a eu un impact au-delà de l’accessibilité à la propriété. Les évaluations foncières, liées à la valeur des maisons, ont également augmenté durant la même période. Puisque les taxes foncières ont augmenté de façon inégale entre propriétaires, cette hausse a eu un impact réel sur la distribution fiscale entre les membres d’une même communauté. Pour diminuer l’impact de certaines hausses spectaculaires de taxes foncières, le Gouvernement de Nouvelle-Écosse a instauré en 2005 le programme d’évaluation plafonnée (PEP) pour limiter l’augmentation des évaluations foncières. Ce programme a eu comme impacts de limiter la hausse de la base taxable des municipalités qui se sont alors retrouvées face à un manque-à-gagner. Cet article démontre que, pour répondre à la diminution des revenus de taxation, les municipalités ont limité la hausse des taux de taxation (ou les ont gelés) des propriétés résidentielles et ont augmenté le taux de taxes foncières des entreprises. La mise en place du PEP a ainsi contribué à transférer une partie significative du fardeau fiscal des propriétaires résidents aux entreprises par l’augmentation des taux commerciaux de 23 % en moyenne pour l’ensemble des municipalités néo-écossaises alors que les taux résidentiels sont restés inchangés lors de la période 2003-2014.The real estate bubble at the turn of the century had an impact beyond affordability. Property assessments, which are linked to house values, also increased over the same period. Since property taxes increased unevenly among homeowners, this increase had a real impact on the tax distribution among members of the same community. To lessen the impact of some dramatic property tax increases, the Government of Nova Scotia introduced the Capped Assessment Program (CAP) in 2005 to limit the increase in property assessments. This program had the impact of limiting the increase in the tax base of municipalities, which then found themselves facing a shortfall. This article shows that, in response to declining tax revenues, municipalities limited (or froze) tax rate increases for residential properties and increased property tax rates for businesses. The introduction of the PEP has thus contributed to shifting a significant portion of the tax burden from resident homeowners to businesses by increasing commercial rates by an average of 23 % for all Nova Scotia municipalities, while residential rates remained unchanged over the 2003-2014 period

Managerial Collusive Behavior under Asymmetric Incentive Schemes

AbstractWe analyze the effects of asymmetry in incentive contracts on the possibility of collusion between managers. When their compensation is based on the relative performance evaluation contracts, managers can achieve better outcomes by colluding. Using the concept of balanced temptation introduced by</jats:p

Strategic delegation and collusion: Do incentive schemes matter?

This paper introduces delegation decisions and contracts based on relative performance evaluation (RPE) in the analysis of cartel stability. We follow the approach developed by Lambertini and Trombetta [12], where manager's compensation combines pro_ts and sales (CPS) instead. Some of our results are similar while others are distinct from those of Lambertini and Trombetta. In particular, we show that collusion under RPE is always harder to sustain than under CPS.Cartel Stability, Delegation, Relative Performance Evaluation

Epididymis seleno-independent glutathione peroxidase 5 maintains sperm DNA integrity in mice

The mammalian epididymis provides sperm with an environment that promotes their maturation and protects them from external stresses. For example, it harbors an array of antioxidants, including non-conventional glutathione peroxidase 5 (GPX5), to protect them from oxidative stress. To explore the role of GPX5 in the epididymis, we generated mice that lack epididymal expression of the enzyme. Histological analyses of Gpx5–/– epididymides and sperm cells revealed no obvious defects. Furthermore, there were no apparent differences in the fertilization rate of sexually mature Gpx5–/– male mice compared with WT male mice. However, a higher incidence of miscarriages and developmental defects were observed when WT female mice were mated with Gpx5-deficient males over 1 year old compared with WT males of the same age. Flow cytometric analysis of spermatozoa recovered from Gpx5-null and WT male mice revealed that sperm DNA compaction was substantially lower in the cauda epididymides of Gpx5-null animals and that they suffered from DNA oxidative attacks. Real-time PCR analysis of enzymatic scavengers expressed in the mouse epididymis indicated that the cauda epididymidis epithelium of Gpx5-null male mice mounted an antioxidant response to cope with an excess of ROS. These observations suggest that GPX5 is a potent antioxidant scavenger in the luminal compartment of the mouse cauda epididymidis that protects spermatozoa from oxidative injuries that could compromise their integrity and, consequently, embryo viability