Topological Constraints in Directed Polymer Melts

Polymers in a melt may be subject to topological constraints, as in the example of unlinked polymer rings. How to do statistical mechanics in the presence of such constraints remains a fundamental open problem. We study the effect of topological constraints on a melt of directed polymers, using simulations of a simple quasi-2D model. We find that fixing the global topology of the melt to be trivial changes the polymer conformations drastically. Polymers of length $L$ wander in the transverse direction only by a distance of order $(\ln L)^\zeta$ with $\zeta \simeq 1.5$. This is strongly suppressed in comparison with the Brownian $L^{1/2}$ scaling which holds in the absence of the topological constraint. It is also much smaller than the predictions of standard heuristic approaches - in particular the $L^{1/4}$ of a mean-field-like `array of obstacles' model - so our results present a sharp challenge to theory. Dynamics are also strongly affected by the constraints, and a tagged monomer in an infinite system performs logarithmically slow subdiffusion in the transverse direction. To cast light on the suppression of the strands' wandering, we analyse the topological complexity of subregions of the melt: the complexity is also logarithmically small, and is related to the wandering by a power law. We comment on insights the results give for 3D melts, directed and non-directed.Comment: 4 pages + appendices, 11 figures. Published versio

Effects of Major Flooding on Water and Sediment Characteristics in an Urban Enviromnent

Spring flooding of the Red River of the North is a common phenomenon, but no infonnation exits on how these flooding events impact both water and sediment quality within an urban area. The objectives of this study were to assess if urban enviromnents affect floodwater quality and to determine the quality of sediment deposited in an urban environment after floodwaters recede. Water samples were taken on 12 dates from two locations before and after the city limits of Pargo, North Dakota and Moorhead, Minnesota (F-M), and were measured for 12 variables including total sediment, P04, 17/3-estradiol, and diesel range organics. Sediment and underlying soil samples were collected from three locations within F-M where, at each location, there were three equidistant transects parallel to the river channel, and analyzed for 40 variables including dry sediment mass, carbon, nitrogen, diesel and gasoline range organics, and trace elements. Considering river discharge and total sediment and P04 concentrations at each sampling date, about 4500 Mg of sediment and 30 Mg of P04 were estimated to have been deposited within F-M. l 7Bestradiol was detected in 9 of 24 water samples with an average concentration of0.61 ng L1 and diesel range organics were detected in 8 of 24 samples with an average concentration of 80.0 ?g L-1. Average mass of sediment across locations and transects ranged from about 2 to 1 O kg m?2 where transects closest to the river channel had the higher mass deposits of sediment. Total carbon and nitrogen within the sediment was determined to be mostly organic and ranged from about 40 to 59 g kg' 1 and about 1,760 to 4,930 mg kg?1, respectively, with the highest concentrations occurring at the transect furthest from the river channel. No gasoline range organics were detected, but diesel range organics were detected in 26 of the 27 sediment samples analyzed with a maximum concentration of 49.2 ?g g-1? Total Hg concentrations in the sediment and soil averaged about 55 and 61 ng g-1, respectively, and all trace elements detected in the sediments were within ranges for noncontaminated sites. Although sediments remaining after floodwaters recede can be unsightly and cleanup efforts can be labor intensive, these sediments can also provide essential plant nutrients for urban riverine ecosystems, which may include turf grass, fruits and vegetables, and horticultural plants

Human and Black Bear Interactions in Buncombe County, North Carolina, from 1993–2013

Over the past 20 years the frequency of interactions between humans and black bears in Buncombe County, North Carolina has been increasing, posing threats to human safety, black bear populations, ecological stability, and conservation support. During this time, both the human population and the American black bear population increased in southern Appalachia, which, combined with both urban expansion and landscape fragmentation, led to an increase in human and black bear interactions. Reducing future interactions with black bears is important as these interactions put support for conservation at risk. I performed a landscape analysis to better understand where human and black bear interactions occurred in this county from 1993–2013. After performing statistical analyses, I concluded that landscape fragmentation and urban characteristics likely played a role in where human and black bear interactions took place. Results of this statistical analysis were that human population density, proportion of forested landscape per block group, urban edge density, and the effective forest mesh size per census tract had statistically significant relationships with the geographic distribution of human and black bear interactions. This research can assist planning and conservation initiatives that aim to reduce human and wildlife interactions. This research will also contribute to the growing literature on human and wildlife interactions and the spatial analysis techniques employed to understand them

Phylotranscriptomic investigation into the evolution of endothermy in fish

Regional endothermy, where metabolically-derived heat is used to maintain elevated temperatures in parts of the body, has independently evolved in several lineages of pelagic, predatory fish, including billfish, tuna, lamnid sharks and the opah. The lamnid sharks and tunas demonstrate a striking phenotypic convergence, despite 450 million years of independent evolution. This is characterised by a distinctive muscle morphology, which has enabled them to utilise a unique stiff-bodied swimming style and maintain elevated muscular temperatures and metabolic capacities. This has facilitated expansions in thermal niche and increases in swimming speed and exercise recovery rate. We find selection has acted on one gene independently in both groups, glycogenin-1, which is associated with post-exercise glycogen replenishment. Different metabolic pathways have been targeted by selection in either group. Amongst the endothermic fish, there is considerable variability between species in endothermic capacity and cold-tolerance. By investigating diversification among the eight Thunnus tuna species, we find that the three highly cold-tolerant and endothermic bluefin tuna species are paraphyletic. We infer that parallel selection on ancestral genetic variation is likely to have enabled their evolution. This includes selection for variants in genes associated with metabolism and thermogenesis in other animals. Adaptations in the cardiac system of bluefin tuna are crucial to their ability to tolerate cold-water, as their heart operates at ambient temperature yet must supply oxygen for metabolically demanding warm muscle. We show that this elevated cardiac capacity is associated with increased expression of a key sarcoplasmic reticulum calcium-cycling gene, SERCA2b, in the atrium. Tuna muscle has a thermal gradient, with temperatures highest in the centre of the body. We found no upregulation of metabolic or thermogenesis genes in regions of warm muscle, indicating that intrinsic muscular contraction is sufficient for heat production. Our results provide insight into the genomic basis of endothermy in fish.Open Acces

Re-deliniating Paul's boundaries of porneia in the early church via the sexually available bodies of first-century slaves

Title from PDF of title page (University of Missouri--Columbia, viewed on September 17, 2012).The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file.Thesis advisor: Dr. Rabia GregoryIncludes bibliographical references.M.A. University of Missouri--Columbia 2012."May 2012"This work attempts to re-delineate Paul's theological boundaries of sexual immorality, porneia, in the early church by way of the sexually available bodies of first-century slaves. While most scholars of Paul's ideas of sexuality have studied his theology on sexual immorality via the individual situations dealt with particularly at Corinth, this work seeks to outline a more broad theology that would be applicable not only to free individuals acting of their own accord, but those without the ability to control their bodies, i.e. the ancient slave. Using Jennifer Glancy's book, Slavery in Early Christianity as a point of reference, which argues that since slaves could not have held up to the high moral standard Paul insisted of his congregants in the realm of sexuality since their bodies were always at the disposal of their masters that they would have been excluded from participation in the early church, I attempt to re-imagine Paul's theology on sexuality with this stratum of Greco-Roman society and the early church in mind. I argue that when Paul spoke of sexual immorality or porneia that he did so with the knowledge that certain members of his communities would not be able to protect the boundaries of their bodies. Thus, for Paul, porneia was not sexual activity outside of marriage full stop, but was instead imbued with notions of ontology, volition, and consent. Since slaves were regarded as less than fully human in a Greco-Roman context, without the ability to control their bodies, Paul would not have expected them to reach this most ideal standard

The Effect of Uncertainty on Monetary Policy: How Good are the Brakes?

In practice, monetary policy changes tend to produce a smooth path for interest rates while the path of policy interest rates generated by models is often considerably more variable. This paper investigates whether the inclusion of uncertainty can help reconcile the theory to the practice. It shows that parameter uncertainty does not induce much smoothness when its effects are directly incorporated into a model. Uncertainty about the interest sensitivity of output can increase the smoothness of optimal policy in a model, but the path of policy interest rates generated is still considerably more variable than that observed in practice.interest rate smoothing; monetary policy; parameter uncertainty