Vitrification of immature feline oocytes with a commercial kit for bovine embryo vitrification

The aim of this study was to evaluate the suitability of a commercial kit for bovine embryo vitrification for cryopreserving cat oocytes and to evaluate comparatively the effects of its use with slow freezing procedure on cryotolerance in terms of morphology and oocyte resumption of meiosis. Germinal vesicle stage oocytes isolated from cat ovaries were either vitrified (n = 72) using a vitrification kit for bovine embryo or slow frozen (n = 69) by exposing oocyte to ethylene glycol solution before being transferred to a programmable embryo freezer. After thawing and warming, oocytes were cultured for 48 h and then were examined for meiosis resumption using bisbenzimide fluorescent staining (Hoechst 33342). Fresh immature oocytes (n = 92) were used as the control group. The proportion of oocytes recovered in a morphologically normal state after thawing \u2044 warming was significantly higher in frozen oocytes (94.5%) than in the vitrified ones (75%, p < 0.01). Morphological integrity after culture was similar in vitrified (73.6%) and slow frozen oocytes (76.8%); however, only 37.5% of the morphologically normal oocytes resumed meiosis after vitrification compared to 60.9% of those submitted to slow freezing procedure (p < 0.01). Fresh oocytes showed higher morphological integrity (91.3%) and meiosis resumption rates (82.6%, p < 0.002) than cryopreserved oocytes, irrespective of the procedure used. These results suggest that immature cat oocytes vitrified with a kit for bovine embryos retain their capacity to resume meiosis after warming and culture, albeit at lower rates than slow frozen oocytes. Vitrification and slow freezing methods show similar proportions of oocytes with normal morphology after culture, which demonstrate that thawed and warmed oocytes that resist to cryodamage have the same chances to maintain their integrity after 48 h of culture

Scintillator ageing of the T2K near detectors from 2010 to 2021

The T2K experiment widely uses plastic scintillator as a target for neutrino interactions and an active medium for the measurement of charged particles produced in neutrino interactions at its near detector complex. Over 10 years of operation the measured light yield recorded by the scintillator based subsystems has been observed to degrade by 0.9–2.2% per year. Extrapolation of the degradation rate through to 2040 indicates the recorded light yield should remain above the lower threshold used by the current reconstruction algorithms for all subsystems. This will allow the near detectors to continue contributing to important physics measurements during the T2K-II and Hyper-Kamiokande eras. Additionally, work to disentangle the degradation of the plastic scintillator and wavelength shifting fibres shows that the reduction in light yield can be attributed to the ageing of the plastic scintillator. The long component of the attenuation length of the wavelength shifting fibres was observed to degrade by 1.3–5.4% per year, while the short component of the attenuation length did not show any conclusive degradation

Deep generative models for fast photon shower simulation in ATLAS

The need for large-scale production of highly accurate simulated event samples for the extensive physics programme of the ATLAS experiment at the Large Hadron Collider motivates the development of new simulation techniques. Building on the recent success of deep learning algorithms, variational autoencoders and generative adversarial networks are investigated for modelling the response of the central region of the ATLAS electromagnetic calorimeter to photons of various energies. The properties of synthesised showers are compared with showers from a full detector simulation using geant4. Both variational autoencoders and generative adversarial networks are capable of quickly simulating electromagnetic showers with correct total energies and stochasticity, though the modelling of some shower shape distributions requires more refinement. This feasibility study demonstrates the potential of using such algorithms for ATLAS fast calorimeter simulation in the future and shows a possible way to complement current simulation techniques

In vitro meiosis resumption of feline oocytes isolated from vitrified ovarian tissue

Introduction and aim. In the preovulatory follicle, canine oocytes are exposed to high concentrations of progesterone (P4) and estradiol (E2), and different concentrations of gonadotrophins are present in the pre- and post-ovulatory environment, i.e. oviduct, where full nuclear maturation occurs (1,2,3). Thus, two microenvironments characterized by the presence of different hormonal concentrations contribute to the achievement of Metaphase II (MII) stage. In vitro, maturation conditions should be based on these different pre- and post-ovulatory environments and on the fact that cultural requirements for oocyte maturation may vary along the time. Hence, the aim of this work was to study the influence of different bi-phasic systems with gonadotrophins and steroids on in vitro maturation rates of canine oocytes. Materials and Methods. Ovaries were collected from 14 anestrous bitches (various breeds, age 1- 7 y) by routine ovariohysterectomy and sliced in PBS-PVA to release the cumulus-oocyte complexes (COCs). A total of 363 COCs grade I (two or more dense layers of cumulus cells and darkly pigmented cytoplasm) were selected for culture. Oocytes were randomly allocated in three different cultural systems with the base medium (BM) consisting of TCM-199 (Sigma Chemical Co., USA), with antibiotics, 10% FBS, 2.2 mg/ml sodium bicarbonate and 20 \u3bcl/ml pyruvic acid. The systems were as follows: in system A (control) oocytes (n. 91) were matured for 72h in BM with 10 i.u./ml hCG (Sigma), 1 \u3bcg/ml P4 (Sigma), 1 \u3bcg/ml E2 (Sigma); in bi-phasic system B oocytes (n. 120) were matured for 48h in BM with hCG and for 24h in BM with P4; in bi-phasic system C oocytes (n. 124) were matured for 48h in BM with hCG, P4 and E2, and for 24h in BM with P4. In systems B and C hormones were supplemented at the same doses as in system A. Cumulus-oocyte complexes were incubated at 38\ub0C, 5% CO2 in air and, at the end of maturation (72h), were transferred to PBS containing 0.2% hyaluronidase (Sigma) for removal of cumulus cells by repeated pipetting. Oocytes were stained with Hoechst 33342 (Sigma) for evaluation of meiotic configuration. Data were analyzed by Chi-square test. Results. Anaphase/Metaphase I rates were higher (P<0.02) in oocytes cultured in bi-phasic system B (27.5%; 33/120) and C (29%; 36/124) when compared to control (13.2%; 12/91). Only three oocytes from control group reached MII stage (3.3%), while higher rates (P<0.02) of oocytes cultured in system B (11.7%; 14/120) and C (13.7%; 17/124) were able to complete meiosis. Degeneration rate was remarkably lower (P<0.05) in C system (4%; 5/124) compared to B (12.5%; 15/120) and control (19.8%; 18/91). Conclusions. These results suggest that the use of bi-phasic systems is beneficial for oocyte meiosis in vitro, when compared to the continuous exposition (72h) to the same hormonal association (control). This is the first time that a bi-phasic system with gonadotrophins and steroids had been studied. As no differences were observed between the two associations of hormones (system B and C), further investigation on the effect of other hormonal combinations and concentrations are needed. References. 1) De los Reyes et al., Theriogenology 2005;64:1-11. 2) Willingham-Rocky et al., Reproduction 2003;126:501-8. 3) Luvoni et al., Theriogenology 2005;63:41-59

On the Concept and Dimensions of Human Capital in a Knowledge-Based Economy Context

Technological changes along with the globalization of markets are transforming industrial countries into knowledge-driven economies. This shift away from resource-based toward knowledge-based economies has made human capital (and its main component, education) one of the leading public policy themes. Given the policy relevance of human capital in a knowledge-based economy, it is essential that its definition, measurement and specification in economic models capture its key inherent features. This paper discusses the elements of a comprehensive definition of human capital and identifies the fundamental differences between human and physical capital. It shows that the main features of human capital and its differences with physical capital have implications for national income accounting, the classification of government expenditures, and the endogenous growth literature. This analysis highlights the close interactions of policy, human capital and growth in a knowledge-based economy. Les changements technologiques et la globalisation des marchés sont en train de transformer les pays industrialisés en économies axées sur l’information. Cette substitution des technologies d’information aux ressources naturelles comme moteurs de développement économique a fait du capital humain (dont sa principale composante l’éducation) un thème de prélédiction dans les discussions de politiques économiques. Ces discussions deviendront plus pertinentes lorsque le capital humain sera convenablement défini, mesuré et spécifié dans les modèles économiques. Cet essai discute des multiples dimensions du capital humain et identifie les différences fondamentales entre le capital humain et le capital physique. Les auteurs démontrent que le concept et les dimensions propres au capital humain, de même que ses différences avec le capital physique, ont des implications importantes pour la comptabilité nationale, la classification des dépenses gouvernementales et les modèles de croissance endogène. Cette analyse met en évidence l’intéraction étroite entre le capital humain, la politique économique et la croissance pour les économies axées sur les technologies d’information.

Flat Taxes and Distributional Justice

Income tax reform has become a hot topic in both the United States and Canada. Over the past few years, a variety of proposals have been advanced for the replacement of the current income tax system and most proposals involve a compression of the multi-rate structure into a single rate and a shift to some form of consumption tax base. Flat taxes are advocated on the belief that they will provide a strong stimulus to investment, employment and output. Their supporters are convinced that the economic benefits are sufficiently large to make everyone better off, therefore there is no need to be concerned about the distributional effects of flat taxes. However, the claims about potentially large efficiency gains from flat taxes are not supported by research. Evaluating the effects of a consumption-base flat tax of the type proposed by Hall and Rabushka is one of the main purposes of the paper. Using a microdata set for Canada, which allows identifying taxpayers by both income level and family type, we show that flat taxes not only increase income inequality but also have important horizontal equity implications. We argue that a full debate on income tax reform requires a detailed evaluation of both polar alternatives to the current hybrid income tax: a move to a consumption base and a move to a comprehensive income tax. Toward that end, we have performed a simulation which estimates the distributional effects of a comprehensive income base with across the board rate reductions in order to maintain revenue-neutrality. We show that this option has advantages over the consumption-base flat tax in terms of both vertical and horizontal equity.income tax reform, flat taxes, equity,

Effect of vitrification of feline ovarian cortex on follicular and oocyte quality and competence

Cryopreservation of ovarian cortex has important implications in the preservation of fertility and biodiversity in animal species. Slow freezing of cat ovarian tissue resulted in the preservation of follicular morphology and in the follicular development after xenografting. Vitrification has been recently applied to ovarian tissues of different species, but no information is available on the effect of this method on feline ovarian cortex. Moreover, meiotic competence of fully grown oocytes isolated from cryopreserved tissue has not been reported. The aim of this study was to evaluate the effect of vitrification of feline ovarian cortex on follicular morphology and oocyte integrity, as well as meiotic competence. A total of 352 fragments (1.5\u20132 mm3) were obtained from ovarian cortical tissues: 176 were vitrified and 176 were used fresh as control. Histological evaluation of fresh and vitrified fragments showed intact follicles after cryopreservation procedures with no statistically significant destructive effect from primordial to antral follicles. After IVM, oocytes collected from vitrified ovarian fragment showed a higher proportion of gametes arrested at germinal vesicle (GV) stage compared to those isolated from fresh control tissue (33.8% vs 2.9%; p < 0.001). However, oocytes isolated from vitrified tissues were able to resume meiosis, albeit at lower rate than those collected from fresh tissues (39.8% vs 85.9%; p < 0.00001. Vitrification induced changes in the organization of cytoskeletal elements (actin microfilaments and microtubules) of oocytes, but significantly only for actin network (p < 0.001). Finally, chromatin configuration within the GV was not affected by the cryopreservation procedure. Our study demonstrated that vitrification preserves the integrity of ovarian follicles and that oocytes retrieved from cryopreserved tissue maintain the capability of resuming meiosis. To our knowledge, this has not previously been reported in the cat