A Light and Electron Microscope Survey of Algal Cell Walls. II, Chlorophyceae

Author Institution: Department of Botany, University of South FloridaUnder the light and electron microscopes, the structure of the cell walls of members of the 11 orders in the Class Chlorophyceae, Division Chlorophyta, were examined. With regard to the microfibrillar component of the cell walls, five types of wall structure were distinguished: (A) an apparent lack of a micro fibrillar component (Volvocales, Dasycladales, and some members of the Siphonales), (B) the microfibrils are arranged in a reticulate pattern (Tetrasporales, Schizogoniales), (C) the microfibrils are oriented in an axial direction (Ulotrichales, Oedogoniales, Zygnematales, and some members of the Siphonales), (D) the microfibrils are parallel to one another and arranged in lamellae (Ulvales), and (E) the microfibrils are parallel to one another, arranged in lamellae, and at right angles to the microfibrils in the lamellae above and below forming the crossfibrillar pattern (Cladophorales, Siphonocladales). Members of the Ulvales were found to have a cell wall similar to that of the brown algae while a member of the Schizogoniales, Prasiola, was found to have a cell wall similar to that of the red algae. A discussion of the taxonomic implications of cell wall structure is included

Macrophage-sensory neuronal interaction in HIV-1 gp120-induced neurotoxicity

Acknowledgements We thank Dr Jim Perkins of University College London for his help with the statistical analysis of our gene array data. We thank Prof. Maria Papathanasopoulos from the University of the Witwatersrand, Johannesburg, for the gift of gp120Bal.Peer reviewedPublisher PD

Sociology, Anthropology-Archaeology and Social Work

This departmental history was written on the occasion of the UND Centennial in 1983.https://commons.und.edu/departmental-histories/1023/thumbnail.jp

Social Work

This departmental history was written on the occasion of the UND Centennial in 1983.https://commons.und.edu/departmental-histories/1055/thumbnail.jp

Autoregulation of ketogenesis in fasted sheep

The effects of beta-hydroxybutyrate at rates simulating maximum utilization on portal-drained viscera (PDV), hepatic (HEP), and hindquarter (rump) net fluxes of acetoacetate (AcAc), beta-hydroxybutyrate (BOHB), free fatty acids (FFA), insulin (IN) and glucagon (GN) were measured in normal (NOR), diabetic insulin treated (DIT) and diabetic untreated (OUT) 3-day fasted sheep. The sheep were equipped with chronic indwelling catheters in the femoral artery and portal, hepatic, mesenteric, and femoral veins. Beta-hydroxybutyrate was infused into a jugular vein. Para-aminohippuric acid (PAH) was infused into a mesenteric vein (1.5% at 0.764 ml/min) in order to measure blood flow rates across the downstream tissues. Hindquarter blood flow was determined by infusing PAH into the femoral artery and measuring femoral artery-jugular vein PAH differences. Three pre- and post-BOHB samples were taken simultaneously from the artery and portal, hepatic, and femoral veins. Net fluxes were calculated by multiplying venoarterial differences by whole blood flow rates. Briefly, BOHB infusion decreased FFA levels in the NOR and DIT and to a lesser extent in CUT animals. Hepatic uptake of FFA decreased in NOR and DIT, but not DOT. Portal-drained visceral and RUMP release of FFA decreased in NOR and DIT, but not DUT ewes. Production of both AcAc and BOHB decreased during BOHB infusion in all three groups. Betahydroxybutyrate infusion increased pancreatic production of insulin in the DIT and NOR sheep but had no effect on IN levels in DUT sheep, while exerting no effect on GN production

Distribution, morphology, and genetic affinities of dwarf embedded Fucus populations from the Northwest Atlantic Ocean

Dwarf embedded Fucus populations in the Northwest Atlantic Ocean are restricted to the upper intertidal zone in sandy salt marsh environments; they lack holdfasts and are from attached parental populations of F. spiralis or F. spiralis x F. vesiculosus hybrids after breakage and entanglement with halophytic marsh grasses. Dwarf forms are dichotomously branched, flat, and have a mean overall length and width of 20.3 and 1.3 mm, respectively. Thus, they are longer than Irish (mean 9.3 mm) and Alaskan (mean 15.0 mm) populations identified as F cottonii. Reciprocal transplants of different Fucus taxa in a Maine salt marsh confirm that F spiralis can become transformed into dwarf embedded thalli within the high intertidal zone, while the latter can grow into F. s. ecad lutarius within the mid intertidal zone. Thus, vertical transplantation can modify fucoid morphology and result in varying ecads. Microsatellite markers indicate that attached F spiralis and F vesiculosus are genetically distinct, while dwarf forms may arise via hybridization between the two taxa. The ratio of intermediate to species-specific-genotypes decreased with larger thalli. Also, F s. ecad lutarius consists of a mixture of intermediate and pure genotypes, while dwarf thalli show a greater frequency of hybrids

The Long-Term Erosion of Repeat-Purchase Loyalty

The study investigates the long-term erosion of repeat-purchase loyalty among consumers who purchase brands in a one-year base period. The study utilises a five-year consumer panel of continuous reporters. We identify brand buyers in a base year, then calculate the proportion that fail to buy the brand in later years. We analyse the top 20 brands in 10 consumer goods categories We find pronounced erosion in repeat-buying over the long-term. The proportion of buyers from a base year that fail to buy the brand in a later year increases steadily over time, from 57% in year 2 to 71.5% by year 5. Moreover, we identify brand and marketing mix factors linked to this over-time customer loss, or erosion. The study provides evidence that consumers’ propensity to buy particular brands changes over a period of years, even though those brands continue to exhibit stable market share. This evidence provides a different interpretation than the literature to date, which has viewed purchase propensities as fixed. The study finds that store brands and niche brands exhibit lower levels of erosion in their buyer base; that a broad range is associated with lower erosion, and that high price promotion incidence is associated with lower erosion for manufacturer brands. Loyalty erosion has been reported before (Ehrenberg, 1988; East & Hammond 1996) but only over short periods. This study examines the phenomenon over five years, confirms that the rate of erosion does diminish over time, and that it is related to category and brand characteristics, as well as marketing mix decisions

Insight into High-quality Aerodynamic Design Spaces through Multi-objective Optimization

An approach to support the computational aerodynamic design process is presented and demonstrated through the application of a novel multi-objective variant of the Tabu Search optimization algorithm for continuous problems to the aerodynamic design optimization of turbomachinery blades. The aim is to improve the performance of a specific stage and ultimately of the whole engine. The integrated system developed for this purpose is described. This combines the optimizer with an existing geometry parameterization scheme and a well- established CFD package. The system’s performance is illustrated through case studies – one two-dimensional, one three-dimensional – in which flow characteristics important to the overall performance of turbomachinery blades are optimized. By showing the designer the trade-off surfaces between the competing objectives, this approach provides considerable insight into the design space under consideration and presents the designer with a range of different Pareto-optimal designs for further consideration. Special emphasis is given to the dimensionality in objective function space of the optimization problem, which seeks designs that perform well for a range of flow performance metrics. The resulting compressor blades achieve their high performance by exploiting complicated physical mechanisms successfully identified through the design process. The system can readily be run on parallel computers, substantially reducing wall-clock run times – a significant benefit when tackling computationally demanding design problems. Overall optimal performance is offered by compromise designs on the Pareto trade-off surface revealed through a true multi-objective design optimization test case. Bearing in mind the continuing rapid advances in computing power and the benefits discussed, this approach brings the adoption of such techniques in real-world engineering design practice a ste