In vivo stability of ester- and ether-linked phospholipid-containing liposomes as measured by perturbed angular correlation spectroscopy

To evaluate liposome formulations for use as intracellular sustained-release drug depots, we have compared the uptake and degradation in rat liver and spleen of liposomes of various compositions, containing as their bulk phospholipid an ether-linked phospholipid or one of several ester-linked phospholipids, by perturbed angular correlation spectroscopy. Multilamellar and small unilamellar vesicles (MLVs and SUVs), composed of egg phosphatidylcholine, sphingomyelin, distearoyl phosphatidylcholine (DSPC), dipalmitoyl phosphatidylcholine (DPPC) or its analog dihexadecylglycerophosphorylcholine (DHPC), and cholesterol plus phosphatidylserine, and containing (111)In complexed to nitrilotriacetic acid, were injected intravenously in rats. Recovery of (111)In-labeled liposomes in blood, liver, and spleen was assessed at specific time points after injection and the percentage of liposomes still intact in liver and spleen was determined by measurement of the time-integrated angular perturbation factor ([G22(∞)] of the (111)In label. We found that MLVs but not SUVs, having DHPC as their bulk phospholipid, showed an increased resistance against lysosomal degradation as compared to other phospholipid-containing liposomes. The use of diacyl phospholipids with a high gel/liquid-crystalline phase-transition temperature, such as DPPC and DSPC, also retarded degradation of MLV, but not of SUV in the dose range tested, while the rate of uptake of these liposomes by the liver was lower

Colonialism, Consumption, and Control: The Illinois Country Liquor Trade, 1750-1803

The liquor trade has been a popular topic of study for many historians examining colonial North America. Due to the detrimental impact alcohol had on Indigenous societies, this historiography has focused on the relationship between Indigenous drinking, cultural degradation, and demographic destitution, which contributed to the establishment of European hegemony in North America. Breaking away from this Euro-centric narrative, this thesis uses liquor as an analytical lens to re-evaluate how colonial society functioned on the ground over the Illinois Country’s successive French, Spanish, British, and American regimes between 1750 and 1803. This examination of the liquor trade reveals that despite colonial discourses of superiority, colonial authority was restricted in the Illinois Country. Colonized Indigenous and French Creole inhabitants retained the power to shape the Illinois Country’s organization and development over the region’s four colonial regimes

Linear equations over multiplicative groups, recurrences, and mixing I

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135647/1/plms1045.pd

Report on the east central Saskatchewan Soil Conservation Project

Non-Peer Reviewe

Observations on Arctic and Red-throated Loons at Storkersen Point, Alaska

Habitat requirements of arctic loons (Gavia arctica) and red-throated loons (Gavia stellata) were studied at Storkersen Point on the Arctic coastal plain of Alaska from 1971 to 1975. Nest success ranged from 28 to 92 per cent and 33 to 78 per cent for arctic and red-throated loons, respectively. Loons were ecologically isolated in their feeding habits and use of wetlands. Arctic loons fed to their young invertebrates captured in the nest pond, and red-throated loons fed to theirs fish captured from the Beaufort Sea. Both species preferred islands as nest substrates, but arctic loons utilized large ponds with stands of Arctophila fulva wetlands for nesting, whereas, red-throated loons used smaller, partially-drained basins most frequently

Interactions between wild oat and a weed-competitive and non-competitive wheat cultivar as influenced by arbuscular mycorrhizal fungi

Non-Peer ReviewedThe response of a weed-competitive (Columbus) and non-competitive (Oslo) wheat (Triticum aestivum L.) cultivar, alone and in competition with wild oat (Avena fatua L.) to arbuscular mycorrhizal fungi (AMF) was assessed in a greenhouse study using four AMF species. Plants were inoculated with 300 spores of Glomus clarum, G. etunicatum, G. intraradices or G. mosseae and grown for 77 d in field soil containing low levels of indigenous AMF populations. The AMF species had no significant (P<0.05) effect on the shoot fresh or dry weight of single stands of Oslo or Columbus compared to the uninoculated controls. However, G. etunicatum significantly (P<0.05) enhanced the shoot fresh weight of single stands of wild oat, and G. intraradices significantly (P<0.05) increased the shoot fresh and dry weight of wild oat compared to the uninoculated control. The competitiveness of wild oat in competition with Oslo was significantly (P<0.05) enhanced by inoculation with G. mosseae, whereas the other AMF species had no effect. In contrast, inoculation of Oslo with G. clarum significantly (P<0.05) increased the ability of Oslo to withstand wild oat competition. On the other hand, there were no differences in the ability of any of the AMF species to impact on wild oat growth in competition with Columbus. However, G. intraradices significantly (P<0.05) increased the shoot dry weight of Columbus in competition with wild oat. These preliminary results indicate that different AMF species interact differently with various hosts, and that these interactions may be specific. In addition, it is apparent that these specific interactions may enhance the competitiveness of a non-competitive host against weeds

Spatial and temporal variability of soil fertility in relation to crop yield zones on hummocky terrain

Non-Peer ReviewedA field study was conducted on hummocky terrain at the Manitoba Zero Tillage Association Research Farm to determine the variability of crop yield as related to landscape position, soil properties, weed populations and plant disease. This information was also used to evaluate technology required for delineation of management units related to precision farming. Variable rate fertiliser management systems can improve efficiency of fertilizer use and environmental sustainability. Adoption of this technology has been hampered due to the difficulty of classifying fields into management units, the high cost of sampling soils on a grid basis, and the variability of soil and plant properties in the landscape. Technology for variable rate fertilizer systems is available, but there is little information available related to yield response in clay soils on hummocky terrain, and the relationship of plant tissue test levels in relation to soil fertility as measured by soil test nitrate nitrogen. Current soil test recommendations for nitrogen are based on soil test nitrate nitrogen from samples bulked from samples in several locations in the field preferably grouped according to topography. Yield data for 1997-2001 were classified into groups with the fuzzy k means, normal mixtures and self-organizing map variants of cluster analysis. Although fuzzy k means commonly used for classification of crop yield and soil properties, a method based on self-organizing maps provided consistent classes when compared across years. Soil nitrate nitrogen varied considerably across the landscape at the site, but was not significantly different (P<0.05) between classes based on crop yield. Yield data can be used to delineate zones for variable management, although fertilizer inputs may be a function of spring soil moisture, runoff and growing season precipitation as they affect seeding, crop emergence and establishment

The response of weed communities to changing management practices

Non-Peer ReviewedThe response of weed communities to changing management practices was assessed as part of the Crop Management Study at the Indian Head Experimental Farm from 1988 to 1990. A split plot design with four reps (144 plots), zero, minimum, and conventional tillage as the main plots, two continuous crop rotations and one crop-fallow rotation as the sub-plots, and spring wheat, winter wheat, flax, and field pea as the crops. Each crop in a rotation was present each year. Weeds were sampled during July each year, after the application of post-emergent herbicides, in order to assess the density and composition of the residual weed flora. In each plot (except the 12 fallow plots) the weeds were counted in 20 quadrats, each 0.25 m^2. Multivariate statistical methods were used to determine if weed communities differed among years, tillages, rotations, and crops. Weed densities were generally low for all years (< 10 plants m-2). From 1988 to 1990, the proportional abundance of different weed types changed. Annual broad-leaved weeds accounted for 40% of the total weed abundance during 1988 and 70% during 1990. Redroot pigweed, kochia, Russian thistle, and thyme-leaved spurge were the major weeds in this group and all increased in frequency of occurrence. Winter annuals decreased from 35% of the total abundance to 19% during the same period. Stinkweed and flixweed were the major weeds in this group. The annual grasses, wild oats and green foxtail, accounted for 5% or less of the abundance in all three years. The perennial group, Canada thistle, perennial sow-thistle, and foxtail barley and the volunteer crop group, spring wheat, winter wheat, and flax were less than 11% of the total abundance in each of the three years. The year to year variation in weed abundance was greater than any variation due to tillage system. The highest weed densities were associated with the rotation that included field pea

Standard model plethystics

We study the vacuum geometry prescribed by the gauge invariant operators of the minimal supersymmetric standard model via the plethystic program. This is achieved by using several tricks to perform the highly computationally challenging Molien-Weyl integral, from which we extract the Hilbert series, encoding the invariants of the geometry at all degrees. The fully refined Hilbert series is presented as the explicit sum of 1422 rational functions. We found a good choice of weights to unrefine the Hilbert series into a rational function of a single variable, from which we can read off the dimension and the degree of the vacuum moduli space of the minimal supersymmetric standard model gauge invariants. All data in Mathematica format are also presented