Sum-factorization techniques in Isogeometric Analysis

The fast assembling of stiffness and mass matrices is a key issue in isogeometric analysis, particularly if the spline degree is increased. We present two algorithms based on the idea of sum factorization, one for matrix assembling and one for matrix-free methods, and study the behavior of their computational complexity in terms of the spline order $p$. Opposed to the standard approach, these algorithms do not apply the idea element-wise, but globally or on macro-elements. If this approach is applied to Gauss quadrature, the computational complexity grows as $p^{d+2}$ instead of $p^{2d+1}$ as previously achieved.Comment: 34 pages, 8 figure

Initial states in integrable quantum field theory quenches from an integral equation hierarchy

We consider the problem of determining the initial state of integrable quantum field theory quenches in terms of the post-quench eigenstates. The corresponding overlaps are a fundamental input to most exact methods to treat integrable quantum quenches. We construct and examine an infinite integral equation hierarchy based on the form factor bootstrap, proposed earlier as a set of conditions deter- mining the overlaps. Using quenches of the mass and interaction in Sinh-Gordon theory as a concrete example, we present theoretical arguments that the state has the squeezed coherent form expected for integrable quenches, and supporting an Ansatz for the solution of the hierarchy. Moreover we also develop an iterative method to solve numerically the lowest equation of the hierarchy. The iterative solution along with extensive numerical checks performed using the next equation of the hierarchy provide a strong numerical evidence that the proposed Ansatz gives a very good approximation for the solution.Comment: 36 pages, pdflatex file, 11 pdf figures. v2: revised version, accepted for publicatio

Bacterial degradation of polychlorinted biphenyls in sludge from an industrial sewer lagoon

A laboratory experiment was conducted to determine if polychlorinated biphenyls (PCB's) found in an industrial sewer sludge can be effectively degraded by mutant bacteria. The aerated sludge was inoculated daily with mutant bacteria in order to augment the existing bacteria with bacteria that were considered to be capable of degrading PCB's. The pH, nitrogen, and phosphorus levels were monitored daily to maintain an optimum growing medium for the bacteria. A gas chromatographic method was used to determine the PCB concentrations of the sludge initially and also throughout the experiment. Results and discussion of the bacterial treatment of polychlorinated biphenyls are presented

Enrichments of 34S in sulfide minerals of deep-water marine sediments of the Blake Ridge, offshore southeastern United States

Past research shows that active sulfide mineralization occurs at the base of the sulfate reduction zone (SRZ) in modern, deep-water, continental-margin sediments that overlie methane gas hydrate. These sulfide minerals (elemental sulfur, Sº; iron monosulfides, ~FeS; and pyrite, FeS2) are enriched in 34S because of sulfate reduction and anaerobic methane oxidation (AMO) processes occurring above and near the sulfate-methane interface (SMI). The data in this study show that 5 discrete zones of sulfide minerals are preserved in a 703.8-meter sediment column associated with methane gas hydrate. These zones of sulfide minerals are also enriched in 34S. The shallowest zone is the present-day SMI, and we infer that the other 4 zones are past locations of the SMI. Today, enrichments of 34S in sulfide minerals occur because of anaerobic methane oxidation (AMO) carried out by methanotrophs and sulfate-reducing microbes in areas that have significant methane delivery to the SMI in methane gas hydrate terranes. Thus, these 34S enrichments are a diagenetic indicator that point out occurrences of high methane delivery to the sulfate-methane interface and the action of the AMO consortium. From the data, we infer that these conditions exist not only today, but also have existed at several discrete times since the mid-Miocene, when sulfur isotopic composition of sulfide minerals is similar to or heavier than that occurring today

Changes in sulfur concentration and sulfur isotopic composition within authigenic sulfide minerals from sediments of Miocene age to the present, ODP Site 995, Blake Ridge, offshore southeastern United States

The Blake Ridge area (offshore southeastern United States) consists of deep-water continental margin sediments overlying deposits of methane gas hydrate. Authigenic sulfide minerals (elemental sulfur, S˚; iron monosulfides, ~FeS; and pyrite, FeS2) are actively deposited in these sediments due to sulfate reduction and focused anaerobic methane oxidation (AMO) at the sulfate-methane interface (SMI). Sulfide minerals at the present SMI are enriched in 34S relative to those produced by sulfate reduction of organic matter higher in the sulfate reduction zone. 34S enrichments preserved in the sediment column may identify relatively high amounts of AMO and thus record periods of high methane delivery to the SMI. We extracted sulfide sulfur from sulfide minerals in sediment samples using chromium reduction (Holes A and B, Site 995, Ocean Drilling Program Leg 164). Sediment samples spanned a depth of 0 to 703.80 meters (Miocene). We made two separate sulfide sulfur extractions. The first extraction measured sulfide sulfur concentration by precipitating zinc sulfide (ZnS) and subsequently titrating dissolved sulfide via iodimetry. The second extraction precipitated sulfide sulfur as silver sulfide (Ag2S) for sulfur isotopic analysis. Baseline solid-phase sulfide sulfur concentrations are generally low (0.2 weight percent sulfur, dry weight) to 200 m but increase below 250 m (~0.4 wt %). Superimposed on these baseline values are peaks of sulfide sulfur concentration as high as ~1 wt %. Baseline sulfur isotopic data (d34S) generally show relative enrichments of 34S between 0 and 200 m (~ -30‰), and relative depletions in 34S below 250 m (~ -40‰). Some of the high concentration samples are correlative with large 34S enrichments (+2.6 to 44‰) in both depth zones. These correlative peaks may represent authigenic sulfide mineral formation at the SMI, where enrichments in 34S are expected. This is especially likely in samples above 200 m. Baseline shifts indicated by the sulfide sulfur data possibly represent changes in organic matter delivery over time, affecting the geochemical importance of AMO versus sulfate reduction

Isolated large amplitude periodic motions of towed rigid wheels

This study investigates a low degree-of-freedom (DoF) mechanical model of shimmying wheels. The model is studied using bifurcation theory and numerical continuation. Self-excited vibrations, that is, stable and unstable periodic motions of the wheel, are detected with the help of Hopf bifurcation calculations. These oscillations are then followed over a large parameter range for different damping values by means of the software package AUTO97. For certain parameter regions, the branches representing large amplitude stable and unstable periodic motions become isolated following an isola birth. These regions are extremely dangerous from an engineering view-point if they are not identified and avoided at the design stage.Comment: Appeared online in Nonlinear Dynamics Thursday, April 26, 200

Baby Blue

https://digitalcommons.library.umaine.edu/mmb-vp/5935/thumbnail.jp

Exact Maximal Height Distribution of Fluctuating Interfaces

We present an exact solution for the distribution P(h_m,L) of the maximal height h_m (measured with respect to the average spatial height) in the steady state of a fluctuating Edwards-Wilkinson interface in a one dimensional system of size L with both periodic and free boundary conditions. For the periodic case, we show that P(h_m,L)=L^{-1/2}f(h_m L^{-1/2}) for all L where the function f(x) is the Airy distribution function that describes the probability density of the area under a Brownian excursion over a unit interval. For the free boundary case, the same scaling holds but the scaling function is different from that of the periodic case. Numerical simulations are in excellent agreement with our analytical results. Our results provide an exactly solvable case for the distribution of extremum of a set of strongly correlated random variables.Comment: 4 pages revtex (two-column), 1 .eps figure include

The Effects of Aerobic, Concurrent, and Resistance Exercise on Compensatory Eating Behaviors

Please download pdf version here

Georgia Moon

https://digitalcommons.library.umaine.edu/mmb-vp/1504/thumbnail.jp