Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

The thermodynamic conditions for the behaviour of silicon in the lower part of the blast furnace have been the focus of the thesis. More specifically, the influences of temperature, carbon activity, total gas pressure and Fe reoxidation on silicon have been studied. Calculations show that an increased temperature gives higher equilibrium ratio between silicon in hot metal and slag. Furthermore, laboratory reduction studies shows that the carbon activity in the cohesive zone increase with an increased reduction time. Increased carbon activity will increase the equilibrium silicon content in liquid metal. Equilibrium calculations based on tapped hot metal and slag shows that the equilibrium silicon content of the liquid metal phase is higher than measured at tapping. Around the raceway area the equilibrium silicon content is very high. The high equilibrium silicon content makes it important to differ between the conditions under operation and the conditions of samples taken out of the blast furnace before studied. The equilibrium silicon content is strongly correlated to the CO gas partial pressure. Often this partial pressure is changed during sampling and cooling of samples. At tapping the equilibrium partial pressure of CO has been calculated to higher values than the total gas pressure inside the blast furnace. Metal droplets found in tapped slags are probably formed by reduction of FeO. In the periphery part of the lower part of the blast furnace, it is believed that mainly FeO oxidises silicon in hot metal. It is not expected that the metal droplets in the slag is formed if FeO oxidises dissolved silicon. Instead, the iron droplets may form at reactions with gas, coke carbon or coal powder carbon. Around some droplets increased magnesium content has been found. This may be due to reactions with gaseous magnesium that, according to thermodynamic conditions, is easy to form. It has been reported that much FeO may be formed in the raceway area. The metal droplets may indicate how much FeO that reacts with other components than liquid iron. The iron found in metal droplets in the slag corresponds to between 0.02 and 0.2 wt-% FeO in the slag.

Hos grisar finner man flera stereotypiska beteenden, som rörbitning och svansbitning. Dessa beteenden är relativt vanliga hos grisar. En miljöberikning definieras som förbättring av ett djurs välfärd, både psykologisk och fysiologiskt, genom förändringar hos djurets omgivning. Denna studie har undersökt om miljöberikningar kan minska stereotypiska beteenden hos grisar. De två olika miljöberikningar som har använts är en jutesäck fylld med halm och en Jolly Ball™. De tre stereotypiska beteendena som studerades var rörbitning, svansbitning och bukmassage. Studien utfördes på 107st grisar uppdelade på 12 boxar, under totalt tre veckor. Alla tre stereotypiska beteenden minskade statistiskt signifikant . Detta visar att båda miljöberikningarna hade en positiv effekt på grisarna då de minskade deras stereotypiska beteenden. De interagerade mer med jutesäcken fylld med halm än vad det gjorde med Jolly Ball™.  Grisarna föredrog den miljöberikningen som var omformbar, förstörbar, ätbar, tuggbar, vilket går i linje med liknande studier. / Among fattening pigs you find several stereotypical behaviours, such as bar-biting and tail-biting. These behaviours are quite common among domestic pigs. Environmental enrichments are often used to reduce stereotypical behaviours in animals.  An environmental enrichment is defined as an improvement of an animal’s welfare, both psychologically and physiologically, through changes in the environment of the animal. With this study, different environmental enrichments were studied to see if they can reduce stereotypical behaviour among fattening pigs. The two different environmental enrichments used were a jute sack filled with straw and a Jolly Ball™. The stereotypical behaviours that were looked at were bar-biting, tail-biting and belly-nosing. The study was carried out on 107 pigs divided into 12 pig boxes, during 3 weeks in total. All three stereotypical behaviours decreased significantly. This shows that the environmental enrichments had a positive effect on the pigs, since they reduced their stereotypical behaviour. The pigs interacted more with the jute sack than they did with the Jolly Ball™.  The pigs preferred the environmental enrichment that was destructible, edible, deformable and chewable, which fits well into similar studies that have been executed.

El present treball analitza al microscopi òptic i al microscopi electrònic de transmissió el testicle de Sus domesticus (raça Landrace - varietat anglesa) a partir de mascles reproductors porcins adults i sans. L'objectiu principal de tots els centres d'Inseminació Artificial Porcina i de les Explotacions de Selecció i Multiplicació Porcina és garantir una excel·lent qualitat espermàtica al llarg de la vida reproductiva útil d'un mascle reproductor porcí. Així doncs, un millor coneixement dels patrons estructural i ultraestructural normals del testicle permetrà diagnosticar amb facilitat quina ha estat l'estructura o funció testicular afectada quan s'observa una disminució de la qualitat del semen. Les anàlisis seminals i hormonals són certament crucials en la valoració d'aquests mascles, però, no són totalment informatives de les alteracions testiculars, ja que és necessari conèixer l'organització microscòpica.Diversos estudis sobre testicle han demostrat que els marcadors més sensibles per a l'avaluació de la funció testicular són els següents: (1) la grandària testicular, (2) el gruix i l'organització de la càpsula testicular, (3) el percentatge de túbuls seminífers i de teixit intersticial en el parènquima testicular, (4) el diàmetre dels túbuls seminífers, (5) l'alçada i la composició de cèl·lules germinals de l'epiteli seminífer, (6) el gruix i l'organització de la làmina pròpia i, (7) la morfologia i la grandària de les cèl·lules de Leydig. El primer objectiu concret del present estudi ha estat, per tant, caracteritzar tots aquests paràmetres testiculars en mascles porcins sans i adults. L'organització estructural del testicle i les mesures quantitatives utilitzades com a marcadors no mostren diferències significatives ni entres els mascles porcins (P > 0,01), ni entre el testicle dret i l'esquerre (P > 0,01). Els testicles, de 330,80  16,99 g de pes, estan envoltats per una càpsula, de 2.375,13  246,68 m de gruix, la qual es divideix en tres capes: la túnica vaginalis constitueix l'1,82  0,78 % de la càpsula i està composta per una capa mesotelial externa i una capa interna de teixit conjuntiu dens; la túnica albuginea representa el 37,31  3,27 % i és de teixit conjuntiu dens i, la túnica vasculosa constitueix el 64,24 4,40 % i és de teixit conjuntiu lax. En el parènquima testicular els túbuls seminífers i el teixit intersticial representen el 72,44  2,12 % i el 27,46  2,12 %, respectivament. Els túbuls seminífers, de 226,23  18,08 m de diàmetre, es troben fortament recargolats i empaquetats, i estan compostos per la làmina pròpia i l'epiteli seminífer. La làmina pròpia, de 4-4,5 m de gruix, està formada per la làmina basal i dues capes de cèl·lules peritubulars. L'epiteli seminífer, amb una alçada mitjana de 66,11  10,62 m, és columnar i estratificat amb cèl·lules de Sertoli i diferents generacions d'espermatogònies, espermatòcits i espermàtides. El teixit intersticial és un teixit conjuntiu lax amb abundants cèl·lules de Leydig polièdriques fortament empaquetades (ca. 15 x 12 m).El segon objectiu concret d'aquest estudi ha estat estudiar des del punt de vista morfològic i morfomètric (alçada, longitud, freqüència relativa d'aparició i durada) els estadis del cicle de l'epiteli seminífer en els mascles porcins de la raça Landrace (varietat anglesa), classificats d'acord amb el mètode de la morfologia tubular. Els estadis premeiòtics ( I, II i III) ocupen el 31,9 % del cicle espermatogènic i es caracteritzen, principalment, per la presència de cèl·lules en les fase inicials de la meiosi I. Les primeres etapes de la meiosi I no afecten els paràmetres morfomètrics de l'epiteli seminífer ja que els valors obtinguts per l'alçada de l'epiteli seminífer, la freqüència relativa, la longitud i la durada d'aquests estadis són molt variables. Els estadis meiòtics (IV i V) representen el 16,4 % del cicle espermatogènic i estan constituïts, principlament, per cèl·lules en un estat avançat de la meiosi I i /o cèl·lules en meiosi II. Les últimes fases de la meiosi I i també de la meiosi II tenen lloc ràpidament, la qual cosa resulta en una baixa freqüència relativa d'aparició i, per tant, en una baixa durada dels estadis meiòtics. Els estadis postmeiòtics (VI, VII i VIII) ocupen el 50,6 % del cicle espermatogènic. L'esdeveniment més important que té lloc en aquests estadis és la fase de maduració de l'espermiogènesi. En la fase de maduració, les espermàtides experimenten diverses modificacions morfològiques i estructurals que donen lloc, finalment, als espermatozoides. La complexitat d'aquests processos fa que els estadis postmeiòtics presentin valors més grans de freqüència relativa, longitud i durada.El tercer objectiu concret d'aquest treball ha estat descriure a nivell ultraestructural el procés d'espermiogènesi, i relacionar les transformacions que experimenten les espermàtides en fase d'elongació amb els canvis ultraestructurals que tenen lloc en les diferents cèl·lules que constitueixen el testicle (cèl·lules germinals, de Sertoli i de Leydig, principalment). L'espermiogènesi del mascle porcí de la raça Landrace (varietat anglesa) s'ha dividit en 9 passos que vénen definits per 9 tipus diferents d'espermàtides. Al llarg de l'espermiogènesi no s'observen diferències ultraestructurals significatives (P > 0,01) ni entre els mascles porcins ni entre el testicle esquerre i dret en les cèl·lules que constitueixen el testicle. / The present study describes the structure and ultrastructure of the Sus domesticus testis (Landrace breed -british variety) from healthy adults boars. The main goal of the whole of Porcine Artifitial Insemination Centres and of the Porcine Livestocks is to guarantee an excellent spermatic quality along the boar reproductive life. Therefore, a better knowlegment of the normal structural and ultrastructural patterns of the testis will improve the prognosis of subfertility when a low spermatic quality is observed. Both seminal and hormonal analysis are certainly crucial in the assessment of these males, but it is also necessary to know the microscopic organization.Several studies have demonstrated that the most sensitive markers of impaired function are: (1) the testicular size, (2) the thickness and organization of the testicular capsule, (3) the percentage of seminiferous tubules and interstitial tissue in the testicular parenchyma, (4) the diameter of seminiferous tubules, (5) the height and germ cell composition of the seminiferous epithelium, (6) the thickness and organization of the lamina propria, and (7) the Leydig cell size and morphology. The first aim of this study has been to characterize all these testicular parameters in healthy adults boars. The structural organization of the testis and quantitative measures used as markers did not differ significantly either among boars (P > 0.01), or between left and right testes (P > 0.01). Testes, of 330.80  16.99 g weight, were surrounded by a capsule, of 2,375.13  246.68 m thick, divided into three layers: the tunica vaginalis constituted 1.82  0.78% of the capsule and was composed by an outer mesothelial layer and an inner dense connective tissue layer; the tunica albuginea represented 37.31  3.27% and was of dense connective tissue and the tunica vasculosa constituted 64.26  4.40% and was of loose connective tissue. In the testicular parenchyma, the seminiferous tubules and the interstitial tissue comprised 72.44  2.12% and 27.46  2.12%, respectively. Seminiferous tubules were highly convoluted ducts of 226.23  18.08 m in diameter composed by a lamina propria and the seminiferous epithelium. The lamina propria, of 4-4.5 m thick, was formed by basal lamina and two layers of peritubular cells. The seminiferous epithelium, of 66.11  10.62 m high, was stratified columnar with Sertoli cells and different generations of spermatogonia, spermatocytes and spermatids. The interstitial tissue was loose connective tissue with abundant and closely-packed polyhedral Leydig cells (av. 15 x 12 m).The second aim of this study has been to describe the morphological features of the eight stages of the seminiferous epithelium in Landrace boars (british variety) according to the tubular morphology method, as well as their relative frequency, length, height and duration. Premeiotic stages (I, II and III) occupied the 31.9 % of the spermatogenic cycle and were mainly characterized by the presence of cells in the initial phases of meiosis I. Early meiosis I did not affect the morphometric parameters of the seminiferous epithelium as indicated by the variable values obtained in the seminiferous epithelium height, as well as in the relative frequency, length, and duration of premeiotic stages. Meiotic stages (IV and V) represented the 16.4 % of the spermatogenic cycle and were constituted, mainly, by cells in advanced meiosis I and/or cells in meiosis II. Last phases of meiosis I and also meiosis II occurred rapidly, resulting in low relative frequency and, therefore, in low duration of meiotic stages. Postmeiotic stages (VI, VII and VIII) occupied the 50.6 % of the spermatogenic cycle. The most important event of these stages was the maturation phase of spermiogenesis. The maturation phase included several morphological and ultrastructural modifications in spermatids, resulting in the formation of spermatozoa. The complexity of these processes correlated with the high relative frequency, length, and duration of postmeiotic stages.The third aim of this study has been to describe the spermiogenesis process at ultrastructural level and, to relate the spermatid transformations along the spermiogernesis with the ultraestructural changes undergoing in testicular cells (mainly germinal, Sertoli and Leydig cells).The spermiogenesis of Landrace boars (british variety) was divided into 9 steps, each one characterized by the presence of an specific spermatid type. Significant differences were found neither among the three healthy boars (P > 0.01), nor the left and right testes (P > 0.01) in the ultrastructure of the testiculars cells along spermiogenesis.

This thesis investigates the prehistoric diet of humans and two of their key commensals on Aitutaki using stable carbon and nitrogen isotopes. This technique gives us new insight into the diet of these three groups and results are considered in the context of the development of agricultural systems on Aitutaki, as well as in light of the wider context of cultural developments and environmental change in the Cook Islands and Polynesia as a whole. Ultimately, it allows us to more fully understand the complex interactions between humans and the two largest commensals in order to evaluate the utility of these animals as proxies for humans in dietary analyses. The results indicate that the prehistoric human diet on Aitutaki can be characterised as mixed, dominated by terrestrial plants and marine protein with lesser amounts of terrestrial protein. While the amount of protein eaten by the individuals was very similar, they varied in how much marine or terrestrial protein they ate. The pigs had a slightly more terrestrial diet, with a greater emphasis on plant foods. Their protein intake was more variable and terrestrial in nature than the humans’. Dogs had a higher trophic level, more marine-oriented, diet than either humans or pigs. Like the humans, their diet contained more variation in the source of their protein. Overall, however, the diets of all three groups were very similar. While the overall nature of the human, pig and dog diets, and their relationships to one another, remained relatively constant over time, beginning in the 14th century they show a decline in the amount of fish consumed and had a more terrestrial diet overall. This confirms trends seen in the archaeofaunal assemblages, and throws light on the relationship between environmental change and human subsistence practices in East Polynesia. The similarity of the pig and dog diets to human diet, and the fact that the relationship remained constant over time, demonstrates the usefulness of the Aitutaki commensal animals as proxies for humans in stable isotope analysis. However, the specifics of that relationship vary by species and by place. While the individual dietary variability provides us with new ways of looking at dietary change within populations, it also demonstrates the importance of obtaining as large an assemblage for analysis as possible in order to ensure that samples are representative of the population as a whole.

This thesis is concerned with a theoretical simulation model for pig breeding, as part of the ongoing search for the “perfect” genotype. The starting point is an additive model to investigate how accurately the classical, infinitesimal model predicts genetic gain for traits controlled by few loci and few alleles. This initial investigation demonstrates that the infinitesimal model is robust, providing that at least 15 loci are controlling a trait and there is symmetry in the allele distributions. A Genotype-Pig (GE-Pig) model is then developed to apply the additive effects of alleles on sub-phenotypic traits like maximum protein deposition, minimum lipid to protein content in the whole body, ad libitum digestible energy intake, energy for maintenance requirement and water content in the whole body. These parameters are then used in a nutrient partitioning simulation model to growth a pig and calculate traditional breeding traits such as average daily gain, feed conversion ratio, and backfat thickness for any combination of alleles. Three algorithms, Genetic Algorithm, Tabu Search, and Simulated Annealing, are used to investigate the GE-Pig model and find optimal combination of alleles for different dietary and selection objective situations. The two diets investigated were either of a low or high quality, and the three selection objectives used were, maximising average daily gain, minimizing feed conversion ratio, and minimizing back fat. A graphical method is developed for easy comparison of the genotypes. Of the algorithms, the Genetic Algorithm performed the best, followed by Tabu Search and finally Simulated Annealing. It is demonstrated that, in general, there is a different, single, optimum for any given selection objective and diet. However under the back fat selection objective, both diets produce the same optimal genotype. Also there are many similarities between the optima for the average daily gain and feed conversion ratio selection objectives. When the theoretical minimum number of generations of selection to the optima is considered, the feed conversion ratio selection objective is the quickest for a breeding program to achieve the optimal solutions, followed by back fat, then average daily gain. It is demonstrated that diet also has an effect on the theoretical number of generations. A Multiple selection objective, using relative economic values applied to the individual selection objectives, is also investigated. For both diets, the majority of the multiple selection objective solutions are in the vicinity of the feed conversion ratio optima, indicating that feed conversion ratio is the most prominent factor. It is also demonstrated that the optimal solution is most affected by the objective parameter weights under low diet conditions.

This thesis investigates the prehistoric diet of humans and two of their key commensals on Aitutaki using stable carbon and nitrogen isotopes. This technique gives us new insight into the diet of these three groups and results are considered in the context of the development of agricultural systems on Aitutaki, as well as in light of the wider context of cultural developments and environmental change in the Cook Islands and Polynesia as a whole. Ultimately, it allows us to more fully understand the complex interactions between humans and the two largest commensals in order to evaluate the utility of these animals as proxies for humans in dietary analyses. The results indicate that the prehistoric human diet on Aitutaki can be characterised as mixed, dominated by terrestrial plants and marine protein with lesser amounts of terrestrial protein. While the amount of protein eaten by the individuals was very similar, they varied in how much marine or terrestrial protein they ate. The pigs had a slightly more terrestrial diet, with a greater emphasis on plant foods. Their protein intake was more variable and terrestrial in nature than the humans’. Dogs had a higher trophic level, more marine-oriented, diet than either humans or pigs. Like the humans, their diet contained more variation in the source of their protein. Overall, however, the diets of all three groups were very similar. While the overall nature of the human, pig and dog diets, and their relationships to one another, remained relatively constant over time, beginning in the 14th century they show a decline in the amount of fish consumed and had a more terrestrial diet overall. This confirms trends seen in the archaeofaunal assemblages, and throws light on the relationship between environmental change and human subsistence practices in East Polynesia. The similarity of the pig and dog diets to human diet, and the fact that the relationship remained constant over time, demonstrates the usefulness of the Aitutaki commensal animals as proxies for humans in stable isotope analysis. However, the specifics of that relationship vary by species and by place. While the individual dietary variability provides us with new ways of looking at dietary change within populations, it also demonstrates the importance of obtaining as large an assemblage for analysis as possible in order to ensure that samples are representative of the population as a whole.

This thesis investigates the prehistoric diet of humans and two of their key commensals on Aitutaki using stable carbon and nitrogen isotopes. This technique gives us new insight into the diet of these three groups and results are considered in the context of the development of agricultural systems on Aitutaki, as well as in light of the wider context of cultural developments and environmental change in the Cook Islands and Polynesia as a whole. Ultimately, it allows us to more fully understand the complex interactions between humans and the two largest commensals in order to evaluate the utility of these animals as proxies for humans in dietary analyses. The results indicate that the prehistoric human diet on Aitutaki can be characterised as mixed, dominated by terrestrial plants and marine protein with lesser amounts of terrestrial protein. While the amount of protein eaten by the individuals was very similar, they varied in how much marine or terrestrial protein they ate. The pigs had a slightly more terrestrial diet, with a greater emphasis on plant foods. Their protein intake was more variable and terrestrial in nature than the humans’. Dogs had a higher trophic level, more marine-oriented, diet than either humans or pigs. Like the humans, their diet contained more variation in the source of their protein. Overall, however, the diets of all three groups were very similar. While the overall nature of the human, pig and dog diets, and their relationships to one another, remained relatively constant over time, beginning in the 14th century they show a decline in the amount of fish consumed and had a more terrestrial diet overall. This confirms trends seen in the archaeofaunal assemblages, and throws light on the relationship between environmental change and human subsistence practices in East Polynesia. The similarity of the pig and dog diets to human diet, and the fact that the relationship remained constant over time, demonstrates the usefulness of the Aitutaki commensal animals as proxies for humans in stable isotope analysis. However, the specifics of that relationship vary by species and by place. While the individual dietary variability provides us with new ways of looking at dietary change within populations, it also demonstrates the importance of obtaining as large an assemblage for analysis as possible in order to ensure that samples are representative of the population as a whole.