The need for higher data rates in WLANs boosts drastically because tremendous consumer interest in emerging multimedia applications, such as HDTV, has been increased. Currently, the IEEE 802.11a/b/g WLANs provide a limited data rate for the current user application requirements. In order to overcome substantial limitations of the existing WLANs, the next generation of WLANs, IEEE 802.11n, is in the course of development and expected to support higher throughput, larger coverage area and better QoS. The high performance IEEE 802.11n WLAN can improve data rate significantly by using smart antenna systems in the physical layer to take advantage of multi-path fading of wireless channels. In this thesis, an analytical model is developed to study the MAC performance and the underlying smart antenna technologies used in multi-path fading channels. Multiple antennas employed in the AP arise two popular approaches to provide a significant performance improvement, diversity and multiplexing. Considering the diversity gain of multiple antennas at the AP in which the AP with multiple antennas serves one user at a time, the capacity and throughput can be obtained. In addition, the AP is possible to serve multiple users in the downlink, by exploiting the multiplexing gain of the wireless channel. We investigate the maximum network throughput when the traffic intensity of the AP approaches to one. Unlike most of previous research which focus on either the physical or the MAC layer performance, our analytical model jointly considers the MAC protocol and the smart antenna technology.

The need for higher data rates in WLANs boosts drastically because tremendous consumer interest in emerging multimedia applications, such as HDTV, has been increased. Currently, the IEEE 802.11a/b/g WLANs provide a limited data rate for the current user application requirements. In order to overcome substantial limitations of the existing WLANs, the next generation of WLANs, IEEE 802.11n, is in the course of development and expected to support higher throughput, larger coverage area and better QoS. The high performance IEEE 802.11n WLAN can improve data rate significantly by using smart antenna systems in the physical layer to take advantage of multi-path fading of wireless channels. In this thesis, an analytical model is developed to study the MAC performance and the underlying smart antenna technologies used in multi-path fading channels. Multiple antennas employed in the AP arise two popular approaches to provide a significant performance improvement, diversity and multiplexing. Considering the diversity gain of multiple antennas at the AP in which the AP with multiple antennas serves one user at a time, the capacity and throughput can be obtained. In addition, the AP is possible to serve multiple users in the downlink, by exploiting the multiplexing gain of the wireless channel. We investigate the maximum network throughput when the traffic intensity of the AP approaches to one. Unlike most of previous research which focus on either the physical or the MAC layer performance, our analytical model jointly considers the MAC protocol and the smart antenna technology.

No description available.

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

Objectives of this study were to characterize feed efficiency traits and examine phenotypic relationships with feeding behavior traits in bulls. Performance, feed intake and feeding behavior traits were measured in bulls (n = 5,165) representing 2 breeds (4100 Angus and 952 Red Angus). Intake and feeding behavior traits were measured for 70-d using a GrowSafe system while fed a corn silage based diet (ME = 2.50 Mcal/kg DM). BW was measured at 14-d intervals. Residual feed intake (RFI) was calculated as the difference between actual DMI and that expected from regression of DMI on mid-test BW0.75 (MBW) and ADG, and residual gain (RG) as the difference between actual ADG and that expected from regression of ADG on MBW and DMI. Residual gain and intake (RIG) was computed as the sum of -1 x RFI and RG, both standardized to a variance of 1. Results from the study indicate that RFI was correlated with DMI (r = 0.71, P < 0.0001) but not MBW or ADG, whereas, RG was correlated with ADG (r = 0.87, P < 0.0001) but not MBW or DMI. RFI was negatively correlated with G:F (r = -0.53, P < 0.0001) and RG (r = -0.40, P < 0.0001). Feeding bout (FB) frequency and duration were correlated with RFI (r = 0.30, 0.36; P < 0.001), but were not significant or weakly correlated (r < 0.10) with RG and G:F. Meal criterion and duration were both correlated (r = -0.13, 0.22; P < 0.0001) with RFI, but not with RG or G:F. Bulls with low RFI spent less time at the feed bunk (129 vs 151 ± 31.2 min/d) and had fewer FB events (79 vs 91 ± 23.4 events/d) than high-RFI bulls. Low-RFI bulls had longer (P < 0.001) meal criterion (9.9 vs 8.5 ± 6.6 min) indicating they took longer to initiate new meals, and had longer meal durations (223 vs 244 ± 43.5 min/d) than high-RFI bulls. Bulls have distinctive feeding behavior patterns that contribute to between-animal variation in RFI, but not associated with RG or G:F.

Title from first page of PDF document. Includes bibliographical references (p. 29-32).

Thesis (Ph. D.)--University of Texas Health Science Center at Houston, School of Public Health, 1995. / Includes bibliographical references (leaves 100-107).

Resumo: Este estudo objetivou avaliar os efeitos da torta de algodão (TA) como fonte lipídica na terminação de bovinos confinados. Para tanto, foram utilizados 40 machos da raça Nelore, não-castrados, com idade média inicial de 17 meses e peso vivo médio inicial de 313,8±41,2 kg, confinados por 102 dias com dietas contendo TA ou soja (SO). A inclusão da TA foi com base no teor de extrato etéreo (EE) da dieta: 3%, 4% e 5%. Também foram testados outros dois tratamentos referências, com teores de 3% e 5% de EE, tendo SO como fonte lipídica. As médias foram comparadas por meio de quatro contrastes não ortogonais: C1 = 3SO versus 3TA; C2 = 5SO versus 5TA; C3 = 3TA versus 5TA, e C4 = 3TA + 5TA versus 4TA. Nas dietas com 3% de EE, a TA não alterou as variáveis estudadas, contudo, nas dietas com 5% de EE, os animais alimentados com TA apresentaram maior consumo de matéria seca, 8,94 para 10,3 kg/dia, e redução da eficiência alimentar, 166 g/kg com SO e 145 g/kg com TA. Porém, por ser um ingrediente de menor custo, houve redução do custo do ganho, 3,15 e 2,63 R$/kg, respectivamente para SO e TA. Maior inclusão do teor de TA na dieta propiciou aumento do peso vivo final dos animais, respectivamente, 433, 454 e 467 kg nas dietas 3TA, 4TA e 5TA; e também aumentou do consumo de matéria seca, respectivamente, 8,34, 9,90 e 10,3 kg/dia. Além de, o aumento da TA nas dietas elevou o tempo despendido em ruminação pelos animais, sem alterar o tempo gasto na alimentação. Assim, o uso da torta de algodão não alterou o ganho de peso, as características de carcaça, e o comportamento ingestivo animais, contudo, nas dietas com maior teor lipídico, a TA elevou o consumo de matéria seca, mas reduziu o custo do ganho de peso. O aumento do teor de TA na dieta elevou o ganho de peso, o consumo de matéria seca e o tempo despendido em ruminação pelos animais, sem alterar a eficiência alimentar... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This study aimed to evaluate effects of cottonseed cake (CC) inclusion as fat source in finishing diet of beef cattle. Forty Nellore males, no castrated, with 17 months of initial age and 313.8±41.2 kg of average initial weight, were finished on feedlot for 102 days with diets containing CC or soybean products (SO). CC inclusion was based on diet ether extract (EE): 3%, 4% and 5%. Others control treatments, with 3% and 5% of EE, having SO as fat source were also tested. Means were tested using four non-orthogonal contrasts: C1 = 3SO versus 3CC; C2 = 5SO versus 5CC; C3 = 3CC versus 5CC, e C4 = 3CC + 5CC versus 4CC. In diets with 3% of EE, CC did not change the variables studied, but, in diets with 5% of EE, animals fed with CC showed major dry matter intake, 8.94 to 10.3 kg/day, and gain:feed reduction, 166 g/kg to SO and 145 g/kg to CC. However, to be a cheap ingredient, promoted gain cost reduction, 3.15 and 2.63 R$/kg, respectively to SO and CC. Major CC diet inclusion increased final live weight of the animals, respectively, 433, 454 and 467 kg on 3CC, 4CC and 5CC diets; and increased dry matter intake too, respectively, 8.34, 9.90 and 10.3 kg/day. In addition, major CC on diet increased chewing time, without changed intake spending time. So, CC use did not change weight gain, carcass traits, and intake behavior, but, in high fat level diets, CC increased dry matter intake and reduced gain cost of the animals. The diet CC inclusion, increased weight gain, dry matter intake, and chewing time, without change gain:feed, gain cost, intake spending time and carcass traits of Nellore bulls, on feedlot / Orientador: Roberto de Oliveira Roça / Coorientador: Renata Helena Branco Arnandes / Banca: Heraldo César Gonçalves / Banca: Mário De Beni Arrigoni / Banca: Paulo Sérgio Andrade Moreira / Banca: Sarah Figueiredo Martins Bonilha / Doutor

Les traitements anthelminthiques (AH) visant à maîtriser l’impact des strongles gastro-intestinaux (SGI) sur la croissance des jeunes bovins doivent être rationnalisés afin de préserver durablement leur efficacité. L’objectif de cette thèse a été de développer et d’évaluer des stratégies de traitement ciblé sélectif (TCS) basées sur la croissance chez les génisses laitières de première saison de pâturage afin de préserver des populations refuges de SGI, non exposées aux AH, et ainsi de retarder l’apparition de résistance. La relation croissance/parasitisme en fin de saison a tout d’abord été étudiée dans des environnements variés ce qui a permis d’appréhender des lots plus infestés et, à l’intérieur de ces lots, des individus plus fortement infestés. Un arbre de décision de traitement de rentrée a été ensuite proposé en combinant des indicateurs de conduite au pâturage pour identifier les groupes à risque et plusieurs seuils de GMQ pour identifier les animaux souffrant le plus du parasitisme. Une stratégie de TCS basée sur le GMQ moyen réalisé à mi- saison a été évaluée sur le terrain par comparaison avec un traitement collectif. Aucune différence significative, en termes de croissance et de parasitisme, n’a été observée à la rentrée entre le groupe TCS et le groupe traité collectivement. Enfin, les attitudes et les perceptions des vétérinaires vis-à-vis du contrôle des parasitoses digestives en élevage bovin laitier et notamment d’une gestion plus raisonnée des anthelminthiques, ont été évaluées. Les vétérinaires reconnaissent la nécessité d’appréhender les traitements AH de manière raisonnée mais identifient de nombreux freins relatifs au développement du conseil et à la disponibilité d’outils simples, fiables et peu couteux. Les résultats de cette thèse montrent qu’il est possible de cibler l’utilisation des AH chez les génisses laitières de première saison de pâturage en se basant sur des indicateurs individuels et de groupe simples d’emploi. / In first grazing season calves (FGSC), the anthelmintic (AH) treatments used to control the negative impact of gastrointestinal nematodes (GIN) on growth must be rationalized to preserve their long-term efficacy. The aim of this PhD thesis was to develop and assess targeted selective treatment (TST) strategies based on growth in FGSC, in order to preserve GIN populations in refugia i.e. not exposed to AH, and thus delay the emergence of AH resistance. Firstly, the relation growth/GIN infection at housing was demonstrated in different environments which allowed identifying groups, and within groups, the most infected animals. Then, a tree treatment decision at housing was proposed combing grazing management indicators to identify the groups at risk, and several average daily weight gain (ADWG) thresholds to identify, within groups, the animals suffering the most of infection. A TST strategy based on mid- season mean ADWG was assessed in field survey in comparison with whole group treatment (WGT). No significant difference, in terms of growth and GIN infection, was observed at housing between the TST and the WGT groups. Lastly, the veterinarians’ behaviors and perceptions about the control of GIN in dairy cattle farming, including a more rational AH management, were assessed. The veterinarians recognize the need to consider the sustainability of the AH treatment but identify serval obstacles as the development of advices and the availability of simple, reliable and cheap tools.The results of this thesis show that it is possible to target the use of AH in FGSC basing on individual and group indicators.

Dans cette thèse, nous avons étudié la relation entre le traitement par antidépresseurs, la prise du poids et le syndrome métabolique sur un échantillon de patients atteints de TDM. Les résultats cliniques ont suggéré que la prise du poids précoce due au traitement par antidépresseurs augmenterait le risque de prise du poids ultérieure et d’incidence ultérieure du syndrome métabolique. Ainsi que la relation entre l'utilisation des antidépresseurs, la réponse au traitement et la prise du poids reste complexe. Malgré l'augmentation simultanée de la consommation d'antidépresseurs et la tendance à l'obésité dans les sociétés occidentales, des cohortes prospectives supplémentaires sont nécessaires pour tester pleinement l'hypothèse traitant que la prise du poids chez les utilisateurs des antidépresseurs est un effet iatrogène. Bien que l'impact des antidépresseurs sur la morbidité cardiovasculaire ne puisse toujours pas être déterminé, les résultats du premier chapitre ont montré que l'utilisation des antidépresseurs, indépendamment de leurs classes, avait un impact sur les dérèglements métaboliques, nécessitant une attention clinique spécifique. Une étude de cohorte à long terme est nécessaire pour confirmer si l'interruption et la réinstauration du traitement par des antidépresseurs seraient liées à la fluctuation des dysrégulations du syndrome métabolique. / In this dissertation we have studied the relationship between AD treatment, weight gain and MetS on a sample of MDD patients. Clinical findings have suggested that early weight gain due to AD treatment would increase the risk of both later weight gain and later MetS incidence. The relationship between AD use, response to treatment and weight gain remain complex. Despite the simultaneous increase in AD use and obesity trends in Western societies, additional prospective cohorts are needed to fully test the hypothesis that weight gain among AD users is indeed an iatrogenic effect. Although impact of AD on cardiovascular morbidity still cannot be ascertained, the results from the first chapter showed that AD use – irrespective of the class - does impact and worsen metabolic dysregulations, which would require specific clinical attention. A long term cohort study is required to confirm whether discontinuation and re-initiation of AD treatment would be linked to fluctuation in MetS dysregulations.