Disjointness of Linear Fractional Actions on Serre Trees

Serre showed that, for a discrete valuation field, the group of linear fractional transformations acts on an infinite regular tree with vertex degree determined by the residue degree of the field. Since the p-adics and the polynomials over the finite field of order p act on isomorphic trees, we may ask whether pairs of actions from these two groups are ever conjugate as tree automorphisms. We analyze permutations induced on finite vertex sets, and show a permutation classification result for actions by these linear fractional transformation groups. We prove that actions by specific subgroups of these groups are conjugate only in specific special cases

Social Security Comes to the Farm

Ever since the new social security law took effect, questions have swamped the social security and county extension offices. After sorting through stacks of cards and letters, the Social Security Administration has compiled a list of the questions most frequently asked. According to Leo W. Smith, manager of the Des Moines office, here are the questions and their answers

Aligning Forces on Wood Particles in an Electric Field

Electrostatic alignment affords a promising route to improved mechanical properties in anisotropic particleboards aimed at competition with sawn lumber in structural uses. A quartz-fiber torque balance was used to measure the aligning torque exerted on elongated wood particles by DC and AC fields over a range of wood moisture content, field intensity, and frequency. Approximate predicting equations relating aligning torque to relevant process parameters have been developed, which should aid the process designer. The dynamics of free-falling particles in an electric field favors small slender particles and high field intensity for best alignment. However, slender particles have long charge relaxation times and thus require high moisture content for effective alignment in a field of a given frequency

Streaming birefringence in extensional flow of polymer solutions

The stress and birefringence in liquid filaments undergoing an extensional flow were measured in an isothermal filament-spinning apparatus. In conjunction with these measurements, an experimental arrangement is described which, as subsequent analyses show, overcomes the difficulties associated with the measurement of birefringence in this geometry. The fluids studied were 1 1/2% and 2 1/2% solutions of two polyacrylamides (Separan AP 30 and Separan AP 273) in a 1 : 1 water/glycerol mixture and a 5% solution of polystyrene (Styron 686) in Aroclor 1254. For all solutions studied, the measured birefringence exhibited a non-linear relation to the principal stress difference. In addition, for the polystyrene/Aroclor solution, the birefringence measured in extension was nearly two orders of magnitude higher than the birefringence in shear at comparable deformation rates. These observations imply a greater degree of molecular orientation is produced by the extensional flow than the shear flow and suggest that birefringence data obtained in shear and extension are useful complements to depict a wider range of stress-optical behavior. On a mesuré l'éffet Maxwell, c'est-à-dire la biréfringence en fonction de la tension, dans des filaments liquides de solution polymérique soumise a un écoulement extensionel. Au moyen d'un appareil spécial, on a réussi a resoudre les problèmes d'optique provenant de cette configuration expérimentale. Avec cet appareil, on a étudié plusieurs solutions aqueuses des polyacrylamides en glycérine aussi bien q'une solution du polystyrene en Arochlor 1254 (polychlor biphenyl).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47202/1/397_2005_Article_BF01736956.pd

Effect of Iodine on Mercury Concentrations in Dental-unit Wastewater

Dental amalgam is a mixture of mercury, silver, tin, and copper. Mercury typically makes up about 50% of it. The amalgam is used to provide the dental patient with a strong durable filling. Some of the dental amalgam may end up in the dental wastewater along with the water used for rinsing. Iodine is often used to control bacteria in dental-unit fresh waterlines. Could Iodine effect mercury concentrations in the wastewater?ISTC partnered with researchers at the Naval Institute for Dental and Biomedical Research to answer that question. Full results appear in Stone, Mark E., et al (2006). "Effect of Iodine on Mercury Concentrations in Dental-unit Wastewater." Dental Materials 22(2), 119-124. https://doi.org/10.1016/j.dental.2005.04.009.Ope

Arsenic Speciation in Arsenic-Rich Brazilian Soils from Gold Mining Sites under Anaerobic Incubation

Arsenic enters the environment naturally though rock weathering but its concentrations can be dramatically increased by human activity such as mining. ISTC’s senior chemist, John Scott, and collaborators from the Federal University of Viçosa (Brazil), Illinois State Geological Survey, and the University of Illinois at Urbana-Champaign teamed up to find the arsenic release pathways in arsenic rich soils at gold mining sites in Brazil. Full research results available in de Mello, J.W.V., Talbott, J.L., Scott, J. et al. (2007). "Arsenic speciation in arsenic-rich Brazilian soils from gold mining sites under anaerobic incubation." Environmental Science and Pollution Research - International 14(6), 388-396. https://doi.org/10.1065/espr2006.08.330Ope

‘Scots and Scabs from North-by-Tweed’:Undesirable Scottish Migrants in Seventeenth- and Early Eighteenth-Century England

While very prominent in the contemporary world, anxiety about the potentially negative impact that immigrants might have on their host communities has deep historical roots. In a British context, such fears were particularly heightened following the regal union of 1603 when large numbers of Scots began settling in England. This article offers a fresh perspective on these issues by exploring the experiences and reception of poor, deviant or otherwise ‘undesirable’ Scottish migrants to England during the seventeenth and eighteenth centuries. Focusing in particular on chapmen, vagrants and criminals, it suggests that, while in general Scots were able to integrate relatively easily into English society, there existed an unwelcome subset surviving by dubious means. Though not usually attracting unduly severe treatment on account of their nationality, these unwelcome migrants had a disproportionate effect on English perceptions of and attitudes towards the broader cohort of Scottish migrants in their midst

The role of the chemokine receptor CXCR4 in infection with feline immunodeficiency virus

Infection with feline immunodeficiency virus (FIV) leads to the development of a disease state similar to AIDS in man. Recent studies have identified the chemokine receptor CXCR4 as the major receptor for cell culture-adapted strains of FIV, suggesting that FIV and human immunodeficiency virus (HIV) share a common mechanism of infection involving an interaction between the virus and a member of the seven transmembrane domain superfamily of molecules. This article reviews the evidence for the involvement of chemokine receptors in FIV infection and contrasts these findings with similar studies on the primate lentiviruses HIV and SIV (simian immunodeficiency virus)