ERISA’s Title IV and the Multiemployer Pension Plan

Understanding the dynamics of thin elastic rods that are immersed in fluid is fundamental in explaining many problems that arise in biology, physics and engineering. Solving the coupled system of rod-fluid in 3D is usually very costly, however in case of low Reynolds number, the three-dimensional problem can be reduced a one-dimensional problem on the centerline of the rod. In this thesis we examine the method of regularized Stokeslets which is a numerical algorithm for an elastic rod immersed in viscous, incompressible fluid at zero Reynolds number governed by Stokes equations. In this method, the elastic rod is represented by a space curve corresponding to the centerline of the rod. In addition, an orthonormal triad is varying along the curve, with one vector being tangent to the curve, and the others describing the material twist. The model that is used for the elastic forces based on this, allows for natural configurations for the rods that are far from straight, as described by curvature and torsion. In this way, the basic or equilibrium configuration for the rod can be e.g. a helix. The linearity of Stokes equations allows us to evaluate the linear and angular fluid velocity only at centerline of the rod. We also examine the dependency to the numerical parameters together with the accuracy and convergence properties of the method. As a bench mark, we compare the numerical result of this method to those produced by the non-local slender body method for the case of elastic rods with no intrinsic curvature and twist inside a planar shear flow. We also present the simulation of the extension of helical rods when they are placed within a constant background flow and we provide a fast converging formula for the periodic summation of the fundamental solutions to the Stokes equations.  Förståelsen för dynamiken hos tunna elastiska fibrer eller stavar inuti en vätska är fundamental för att förklara många problem som uppstår inom biologi, fysik och ingenjörsvetenskap. Att lösa det sammanbundna stav-vätska systemet i 3D är vanligtvis väldigt kostsamt; men vid ett lågt Reynoldstal kan det tredimensionella problemet reduceras till ett endimensionellt längs stavens centrumlinje. I det här arbetet har vi undersökt metoden med regulariserande Stokeslets, vilken är en numerisk algoritm som används på elastiska stavar inuti en viskös, inkompressibel vätska med Reynoldstal noll, modellerad med Stokes ekvation. I den här metoden så är den elastiska staven representerad av en kurva i rummet som beskriver stavens centrumlinje. Dessutom används en ortogonal triad som varierar längs kurvan, och som beskriver materialets vridning. Med den modell som används för de elastiska krafterna baserat på detta, så kan stavarnas naturliga konfiguration vara allt annat än raka, och beskrivas med kurvatur och torsion. På detta sätt kan grundläget för staven vara tex spiralformad. Lineariteten av Stokes ekvation möjliggör att vi kan beräkna både den linjära och vinkel-flödeshastigheten endast längs med stavens centrumlinje. Vi undersöker också hur metoden beror av de numeriska parametrarna och metodens noggrannhets- och konvergens-egenskaper. Som ett riktmärke jämför vi de numeriska resultaten av metoden med resultaten producerade av den så kallade ”non-local slender body” metoden som använts för elastiska stavar utan naturlig kurvatur och vridning som placeras i ett plant skjuvflöde. Vi presenterar också simuleringar av utsträckning av spiralformade stavar då dessa är placerade i ett konstant bakgrundsflöde, och dessutom så tillhandahåller vi en snabbt konvergerande formel för den periodiska summeringen av de fundamentala lösningarna till Stokes ekvation

The lightcraft project

Rensselaer Polytechnic Institute has been developing a transatmospheric 'Lightcraft' technology which uses beamed laser energy to propel advanced shuttle craft to orbit. In the past several years, Rensselaer students have analyzed the unique combined-cycle Lightcraft engine, designed a small unmanned Lightcraft Technology Demonstrator, and conceptualized larger manned Lightcraft - to name just a few of the interrelated design projects. The 1990-91 class carried out preliminary and detailed design efforts for a one-person 'Mercury' Lightcraft, using computer-aided design and finite-element structural modeling techniques. In addition, they began construction of a 2.6 m-diameter, full-scale engineering prototype mockup. The mockup will be equipped with three robotic legs that 'kneel' for passenger entry and exit. More importantly, the articulated tripod gear is crucial for accurately pointing at, and tracking the laser relay mirrors, a maneuver that must be performed just prior to liftoff. Also accomplished were further design improvements on a 6-inch-diameter Lightcraft model (for testing in RPI's hypersonic tunnel), and new laser propulsion experiments. The resultant experimental data will be used to calibrate Computational Fluid Dynamic (CFD) codes and analytical laser propulsion models that can simulate vehicle/engine flight conditions along a transatmospheric boost trajectory. These efforts will enable the prediction of distributed aerodynamic and thruster loads over the entire full-scale spacecraft

VASCULAR CELL DYSFUNCTION AND TRANSENDOTHELIAL MIGRATION OF NEUTROPHILS IN PREECLAMPSIA

Oxidative stress, hyperlipidemia, neutrophil activation and endothelial cell dysfunction are characteristic of women with preeclampsia. We used in vitro experiments to test if a combination of oxidative stress and linoleic acid favors a mechanism for neutrophil transendothelial migration. We used linoleic acid because it is one of the fatty acids elevated in preeclampsia and the precursor for arachidonic acid and its inflammatory metabolites. For these studies, we developed a methodology for isolating and Culturing human vascular smooth muscle cells from placental chorionic plate arteries. Treatment of these cells with an oxidizing solution enriched with linoleic acid, but neither component alone, led to increased production of interleukin-8 (IL-8), a potent neutrophil chemotactic agent, This treatment solution also stimulated arachidonic acid metabolites, including leukotriene B4, another potent neutrophil chemotactic agent. The same treatment solution rapidly activated neutrophils to produce superoxide, These observations suggested there might be neutrophil transendothelial migration in women with preeclampsia because increased expression of IL-8 by vascular smooth muscle would attract neutrophils to the vasculature, and activation of neutrophils would prime them for transendothelial migration. These predictions were confirmed using immunohistochemical staining of systemic vascular tissue in preeclamptic women, as compared to normal pregnant and normal non-pregnant women, by demonstrating vascular smooth muscle cell expression of lL-8 coincident with neutrophil infiltration into systemic vessels. Endothelial cells and vascular smooth muscle cells also expressed ICAM-1, a cell adhesion molecule necessary for neutrophil infiltration. This investigation is the first to demonstrate vascular smooth muscle cell expression of IL-8 and ICAM-1 coincident with neutrophil transendothelial migration into systemic vascular tissue in women with preeclampsia. These observations provide evidence for total ‘Vascular cell dysfunction”, not only endothelial cell dysfunction, in women with preeclampsia. Together they link vascular cell dysfunction to a single mechanism, transendothelial migration of neutrophils, which could explain the clinical symptoms of hypertension, proteinuria, and pathological edema. These results bolster the use of antioxidants in preventing preeclampsia and suggest novel treatments for preeclampsia based on neutralizing antibodies to IL-8 or cell adhesion molecules

LABORATORY SCALE EVALUATION OF THE FEASIBILITY OF USING GUANIDINIUM SALTS AS A MEANS OF INSITU SOIL STRENGTHENING FOR WEAK CLAYS

Deep-seated, slow moving landslides are widespread throughout the prairie provinces of Canada, especially in Saskatchewan and eastern Alberta. These landslides are characterized by a thick deposit of glacial drift underlain by poorly lithified cretaceous shale (Bearpaw, Lea Park formations). Multiple thin layers of extremely weak, smectite rich, clayey soils are often found within the upper portions of these cretaceous shale formations. The interfaces of these smectitic clay lenses typically produce a pronounced shear plane, turning the overlying soils into a large slump block. Landslides of this nature can span several hundred meters in length, which provides a threat to infrastructure such as roads, bridges, and pipelines. Due to the depth of these shear zones, and the scale of these types of creeping failures, remediation via traditional geotechnical engineering solutions is either not feasible or extremely costly to pursue. The lack of available solutions for this common problem has prompted research that stems from a multi-disciplinary approach. The current research is intended to evaluate the feasibility of modifying the porewater chemistry of these smectitic shear zones by using guanidinium chloride to propagate mineralogical alteration through ion exchange, as a means of insitu soil strengthening. This study was limited to laboratory scale testing. The specific objectives for this research were to: i.) characterise the mechanism by which guanidinium salts can alter the mineralogical and macroscopically observable properties of natural expansive clay soils; and, ii.) assess fundamental questions pertaining to the full-scale implementation of the proposed insitu strengthening technique. A local prairie soil, Regina Clay, was used for the majority of testing procedures, as it is readily available and is representative of the types of soils associated with the problem that this research aimed to address. The results from a series of batch-style geotechnical and mineralogical testing procedures contributed to a clearer understanding of the mechanisms associated with this treatment, the required strengths of saline solution for treatment, quantified the effects of treatment, and the permanence of the effects associated with this treatment. Treating expansive soils with concentrations of 0.1 molar guanidinium chloride saline solutions were found to cause permanent alterations to the smectite mineral’s basal spacing and soil fabric, increase the permeability by half an order of magnitude, and increase the residual shear strength by up to 100%, all without reducing the oedometric stiffness. As the present study is limited to laboratory-scale trials, a full-scale test site is recommended to further validate the effects found in this research. However, despite the limitations of this work, the potential for insitu soil strengthening via guanidinium salts appears to be significant

Energy Beam Highways Through the Skies

The emergence of Energy Beam Flight Transportation Systems could dramatically change the way we travel in the 21st Century. A framework for formulating 'Highways of Light' and the top level architectures that invoke radically new Space Power Grid infrastructure, are introduced. Basically, such flight systems, hereafter called Lightcraft, would employ off-board energy beam sources (either laser or microwave) to energize on-board dependent 'motors' -- instead of the traditional autonomous 'engines' with their on-board energy sources (e.g., chemical fuels). Extreme reductions in vehicle dry mass appear feasible with the use of off-board power and a high degree of on-board artificial intelligence. Such vehicles may no longer need airports for refueling (since they require no propellant), and could possibly pick up travelers at their homes -- before motoring over to one of many local boost stations, for the flight out. With off-board power, hyper-energetic acceleration performance and boost-glide trajectories become feasible. Hypersonic MS airbreathing propulsion can enable boosts up to twice escape velocity, which will cut trip times to the moon down to 5.5 hours. The predominant technological, environmental and social factors that will result from such transportation systems will be stressed. This presentation first introduces the remote source siting options for the space power system infrastructure, and then provides three representative laser/microwave Lightcraft options (derived from historical Case Studies): i.e., 'Acorn', 'Toy Top', and 'Disc.' Next the gamut of combined-cycle engine options developed for these Lightcraft are examined -- to illuminate the 'emerging technologies' that must be harnessed to produce flight hardware. Needed proof-of concept experiments are identified, along with the Macro-Level Issues that can springboard these revolutionary concepts into hardware reality

What does your profile picture say about you? The accuracy of thin-slice personality judgments from social networking sites made at zero-acquaintance

The myocardium exhibits heterogeneous nature due to scarring after Myocardial Infarction (MI). In Cardiac Magnetic Resonance (CMR) imaging, Late Gadolinium (LG) contrast agent enhances the intensity of scarred area in the myocardium. In this paper, we propose a probability mapping technique using Texture and Intensity features to describe heterogeneous nature of the scarred myocardium in Cardiac Magnetic Resonance (CMR) images after Myocardial Infarction (MI). Scarred tissue and non-scarred tissue are represented with high and low probabilities, respectively. Intermediate values possibly indicate areas where the scarred and healthy tissues are interwoven. The probability map of scarred myocardium is calculated by using a probability function based on Bayes rule. Any set of features can be used in the probability function. In the present study, we demonstrate the use of two different types of features. One is based on the mean intensity of pixel and the other on underlying texture information of the scarred and non-scarred myocardium. Examples of probability maps computed using the mean intensity of pixel and the underlying texture information are presented. We hypothesize that the probability mapping of myocardium offers alternate visualization, possibly showing the details with physiological significance difficult to detect visually in the original CMR image. The probability mapping obtained from the two features provides a way to define different cardiac segments which offer a way to identify areas in the myocardium of diagnostic importance (like core and border areas in scarred myocardiu

Development and Testing of a Refractory Millimeter-Wave Absorbent Heat Exchanger

Central to the Millimeter-Wave Thermal Launch System (MTLS) is the millimeter-wave absorbent heat exchanger. We have developed metallic and ceramic variants, with the key challenge being the millimeter-wave absorbent coatings for each. The ceramic heat exchanger came to fruition first, demonstrating for the first time 1800 K peak surface temperatures under illumination by a 110 GHz Gaussian beam. Absorption efficiencies of up to 80 are calculated for mullite heat exchanger tubes and up to 50 are calculated for alumina tubes. These are compared with estimates based on stratified layer and finite element analyses. The problem of how to connect the 1800 K end of the ceramic tubes to a graphite outlet manifold and nozzle is solved by press fitting, or by threading the ends of the ceramic tubes and screwing them into place. The problem of how to connect the ceramic tubes to a metallic or nylon inlet pipe is solved by using soft compliant PTFE and PVC tubes that accommodate thermal deformations of the ceramic tubes during startup and operation. We show the resulting heat exchangers in static tests using argon and helium as propellants

Profile of Earnings for Female-Headed Families.

Center for Urban and Regional Affairs, University of Minnesota

The networked seceder model: Group formation in social and economic systems

The seceder model illustrates how the desire to be different than the average can lead to formation of groups in a population. We turn the original, agent based, seceder model into a model of network evolution. We find that the structural characteristics our model closely matches empirical social networks. Statistics for the dynamics of group formation are also given. Extensions of the model to networks of companies are also discussed