In this study, features of ecology, behavior, and functional morphology related to feeding activity of two populations of the amphipod Gammarus minus were compared. The two populations occupied different habitats, and I attempted to determine whether differences observed between the two populations were related to habitat. Annual production and life history of the populations were compared and their relationship to factors such as temperature, water-chemistry, and quantity of available organic matter were examined. Mouthpart and foregut morphology were compared between the two populations and between immature and mature amphipods with light and scanning electron microscopy. Measurements of structure were analyzed by linear regression. A behavioral study, comparing feeding of immature and mature G. minus, was conducted in the laboratory. Annual production of G. minus occupying a habitat characterized by the presence of watercress, gravel substrate, and constant temperature (Site 1) was 3.9 g/m² (95% C.I.: 3.2- 4.5), while that in the habitat characterized by leaf detritus and fluctuating temperatures (Site 2) was 1.8 g/m² (95% C.I.: 1.6-2.1). Breeding occurred throughout the year at Site 1, but there was a yearly cycle at Site 2. The greatest numbers of the smallest size classes of amphipod were present at Site 2 when the quantity of ash-free dry mass (AFDM) of wood and bark was greater than AFDM of leaf detritus. Of nine mouthpart and foregut structures studied, three, the number of cuspidate setae on outer plates of maxillipeds, the length of the dactyl on maxilliped palps, and the number of hook setae on the foregut ampullae, were found to be correlated with body length. Of these, rates of increase in maxilliped setae numbers and hook setae numbers were greater for immature than mature animals, and the number of hook setae for a given sized animal was generally greater for animals at Site 1 than Site 2. Animals presented with ground-up leaf material in the laboratory exhibited twenty-one recognizable behaviors. The frequencies of six behaviors were found to be statistically different between immature and mature animals. The differences suggest that immatures may prefer a food type or size other than that provided in the experiment. / Ph. D.

Indiana University-Purdue University Indianapolis (IUPUI) / The benefits of breastfeeding are widely known and documented, yet breastfeeding rates at six months have remained well below desired levels. In order to fully understand the breastfeeding experience in the early postpartum period and all the intricacies involved, researchers need to provide mothers with the opportunity to talk about their experiences during the time when there are the most difficulties and when they are most likely to discontinue, the first four weeks postpartum. The purpose of this study was to more fully understand, in their own words, the experiences of mothers who began breastfeeding their infant after birth and may or may not have been breasting at four weeks postpartum. A single research question guided this study: What are the lived experiences of breastfeeding mothers during the first four weeks postpartum? Eight mothers who delivered in the past four to six weeks were interviewed. Data were analyzed using a Heideggerian hermeneutic phenomenological approach. This method was chosen because it allowed the researcher to conduct interviews and explore the lived experience of breastfeeding mothers and to uncover the concealed meaning within the phenomena. This methodology provided a richness that might not be possible through description alone. The narratives shared by the mothers demonstrated that initiating breastfeeding and sustaining it in the early postpartum period was a complex process. Each mother’s breastfeeding experience was unique to her but also similar to someone else’s. The overall constitutive pattern of Getting the Hang of It was selected and consisted of four themes and nine subthemes. The four themes included: Physical Experiences, Emotional Complexities, Infant Involvement in Breastfeeding Process, and Support. These themes and their subsequent subthemes provide insight into the complexities experienced by mothers in order to acquire the skills they needed to breastfeed their infants. Breastfeeding mothers, who have had favorable and unfavorable experiences, are willing to share a wealth of information. Health professionals should encourage mothers to talk about their experiences and listen to what they are saying. Through listening they can provide mothers with the resources and support needed to meet their breastfeeding goals.

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Thesis (Ph.D.), Faculty of Science, University of the Witwatersrand, 2004

Multiengine first stages are the new trend in recent rockets. Reusability and an oxygen/methane based engine complete this picture. ArianeGroup wants to develop its own rocket following these principles. This thesis presents the study of the feeding system for a seven Prometheus engine rocket. Several ways of connecting propellant tanks to engines were proposed and analyzed. Two configurations were selected and studied with more detail. One consists of a main feeding line which is then split in seven secondary lines. The other one adds one rank of pipes to reduce the number of feeding valves. Their performances were assessed according to classic space industry drivers. Furthermore, the impact of the two solutions on the efficiency of the tank was evaluated. CAD drawings and simulation models were made and could be a base for future work if one of the systems is chosen. The study shows that a falcon 9 like feeding system is performant in terms of mass and pressure losses but another cost-effective configuration is possible and gives good results. / Första stegen med flera motorer är den nya trenden i de senaste raketerna. Återanvändbart och en syre och metan-baserad motor kompletterar denna bild. ArianeGroup vill utveckla sin egen raket enligt dessa principer. Denna avhandling presenterar studien av drivmedelsrör för en sju Prometheus-motorraket. Flera sätt att ansluta drivmedelstankar till motorer föreslogs och analyserades. Två konfigurationer valdes ut och studerades mer detaljerat. En består av en huvudlinje som sedan delas upp i sju sekundära linjer som på SpaceX Falcon 9. Den andra lösningen lägger till en rang av rör för att minska antalet ventiler. Deras prestanda utvärderades först enligt klassiska kriterier för rymdindustrin. Dessutom utvärderades de två lösningarnas påverkan på tankens effektivitet. CAD-ritningar och simuleringsmodeller gjordes och kan vara en bas för framtida arbeten om ett av systemen väljs. Studien visar att ett Falcon 9-liknande konfiguration har bättre prestanda när det gäller massa och tryckförluster men en annan kostnadseffektiv konfiguration är möjlig och ger goda resultat.

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