Knots on a positive template have a bounded number of prime factors

Templates are branched 2-manifolds with semi-flows used to model `chaotic' hyperbolic invariant sets of flows on 3-manifolds. Knotted orbits on a template correspond to those in the original flow. Birman and Williams conjectured that for any given template the number of prime factors of the knots realized would be bounded. We prove a special case when the template is positive; the general case is now known to be false.Comment: Published by Algebraic and Geometric Topology at http://www.maths.warwick.ac.uk/agt/AGTVol5/agt-5-24.abs.htm

Poincare duality for K-theory of equivariant complex projective spaces

We make explicit Poincare duality for the equivariant K-theory of equivariant complex projective spaces. The case of the trivial group provides a new approach to the K-theory orientation

Unfair competition governs the interaction of pCPI-17 with myosin phosphatase (PP1-MYPT1).

The small phosphoprotein pCPI-17 inhibits myosin light-chain phosphatase (MLCP). Current models postulate that during muscle relaxation, phosphatases other than MLCP dephosphorylate and inactivate pCPI-17 to restore MLCP activity. We show here that such hypotheses are insufficient to account for the observed rapidity of pCPI-17 inactivation in mammalian smooth muscles. Instead, MLCP itself is the critical enzyme for pCPI-17 dephosphorylation. We call the mutual sequestration mechanism through which pCPI-17 and MLCP interact inhibition by unfair competition: MLCP protects pCPI-17 from other phosphatases, while pCPI-17 blocks other substrates from MLCP\u27s active site. MLCP dephosphorylates pCPI-17 at a slow rate that is, nonetheless, both sufficient and necessary to explain the speed of pCPI-17 dephosphorylation and the consequent MLCP activation during muscle relaxation

Two Middle Holocene Marker Beds in Vertically Accreted Floodplain Deposits, Lower Fraser River, British Columbia

Drill cores obtained from the eastern Fraser Delta and adjoining Fraser River floodplain reveal two middle Holocene marker beds—a peat with an age of about 6000 14C yr BP and a tephra bed, identified as Mazama (6800 yr BP). These marker beds, in conjunction with 14C dates from the flood-plain sediments, indicate that the Fraser River floodplain aggraded in response to a rise in sea-level, between about 8000 and 2250 yr BP, and that aggradation kept pace with sea-level rise. The aggradational deposits form a sediment wedge consisting mainly of organic-rich silts and fine sands of overbank origin. The wedge extends at least 20 km into the lower Fraser River Valley. Preservation of the marker beds indicates considerable channel stability in the lower reaches of the Fraser River over about the last 7000 years.Des carottes recueillies dans la partie est du delta du Fraser et de la plaine d'inondation adjacente montrent deux lits repères datant du milieu de l'Holocène, un lit de tourbe datant d'à peu près 6000 BP et un lit de tephra, correspondant à l'éruption du mont Mazama (6800 BP). Ces lits repères, ainsi que les datations au radiocarbone obtenues dans les sédiments de crue, montrent que la plaine d'inondation du Fraser a progressé en réponse à une hausse du niveau marin survenue entre environ 8000 et 2250 BP et que l'aggradation suivait la hausse du niveau marin. L'accumulation de sédiments, de forme triangulaire, est composée principalement de limons riches en matière organique et de sables fins d'origine alluviale. Le triangle s'étend jusqu'à au moins 20 km dans la vallée inférieure du Fraser. La conservation des lits repères démontre la grande stabilité des biefs du Fraser inférieur depuis environ 7000 ans.Bohrkerne von dem ôstlichen Fraser-Delta und der angrenzenden Hochflutebene lassen zwei Betten aus dem mittleren Holozân erkennen, die als Anhalt dienen: ein Torfbett das auf etwa 6000 "1C Jahre v.u.Z. datiert wird und ein Tephra-Bett, das aus der Zeit des Ausbruchs des Mazamabergs stammt (6800 Jahre v.u.Z.). Die als Anhaltspunkt dienenden Betten weisen zusammen mit den von den Hochflutsedimenten gewonnenen 14C-Daten darauf hin, dass die Hochflut des Fraser-Flusses als Reaktion auf eine Anhebung des Meeresspiegels zwischen etwa 8000 und 2250 Jahren v.u.Z. zugenommen hat. und dass diese Zunahme der Hebung des Meeresspiegels entsprach. Die Akkumulationssedimente bilden einen Sedimentkeil, der vor allem aus organisch reichem Schlamm und feinem Sand alluvialer Herkunft besteht. Der Keil erstreckt sich mindestens 20 km in das TaI des unteren Fraser. Die Erhaltung der als Anhaltspunkte dienenden Betten beweist eine beachtliche Kanalstabilitât in den unteren Stillen des Fraser wâhrend ungefàhr 7000 Jahren

Mechanical Evidence of the Orbital Angular Momentum to Energy Ratio of Vortex Beams

We measure, in a single experiment, both the radiation pressure and the torque due to a wide variety of propagating acoustic vortex beams. The results validate, for the first time directly, the theoretically predicted ratio of the orbital angular momentum to linear momentum in a propagating beam. We experimentally determine this ratio using simultaneous measurements of both the levitation force and the torque on an acoustic absorber exerted by a broad range of helical ultrasonic beams produced by a 1000-element matrix transducer array. In general, beams with helical phase fronts have been shown to contain orbital angular momentum as the result of the azimuthal component of the Poynting vector around the propagation axis. Theory predicts that for both optical and acoustic helical beams the ratio of the angular momentum current of the beam to the power should be given by the ratio of the beam’s topological charge to its angular frequency. This direct experimental observation that the ratio of the torque to power does convincingly match the expected value (given by the topological charge to angular frequency ratio of the beam) is a fundamental result

Pedagogical Considerations that May Encourage Character Development in a Distance Education Course

The aims espoused by institutions of higher education often entail the development of students’ character. Rarely, however, are these character development aims connected to the unique design and delivery of distance education programs, and the research literature that explores the moral and character development aspects of distance education is sparse. This case study examines instructor and student perceptions of approaches, instructional methods, and other factors that contributed to perceived character development in a fantasy literature distance education course. The findings indicate that the instructor and students perceived myriad kinds of character development and corresponding approaches and methods for bringing about such development in the context of the course. This article considers possible implications for character development in the context of distance education and directions for future research

Microgravity Droplet Combustion in CO2 Enriched Environments at Elevated Pressures

Microgravity droplet combustion experiments were performed in elevated concentrations of CO2 at pressures of 1.0 atm, 3.0 atm, and 5.0 atm to examine the effects of a radiatively participating suppression agent in space applications. Methanol and n-heptane droplets, with an initial diameter of 2.0 mm supported on a quartz fiber, were used in these experiments. The ambient O2 concentration was held constant at 21% and the CO2 concentrations ranged from 0% to a maximum of 70%, by volume with the balance consisting of N2 . Results from the methanol tests showed slight decreases in burning rates with increased CO2 concentrations at all ambient pressures. The n-heptane tests show slight increases in burning rates with increasing CO2 concentrations at each pressure level. Instantaneous radiative heat flux was also measured using both a broadband radiometer (i.e., wavelengths from 0.6 microns to 40.0 microns) and a narrowband radiometer (i.e., centered at 5.6 microns with a filter width at half maximum of 1.5 microns). Radiative exchanges between the droplet and surrounding gases as well as the soot field produce departures from the classical quasisteady theory which would predict a decrease in burning rates with increasing CO2 concentrations in microgravity

The Phenomenon of Character Development in a Distance Education Course

Rarely are character development-related aims espoused by higher education reflected in the design and delivery of distance education programs. Further, literature exploring the character development aspects of distance education is sparse. This study finds that the instructor and students in a fantasy literature distance course perceived myriad kinds of character development related to performance, moral, relational, and spiritual character traits and strengths. This paper considers implications for character development in distance education and directions for future research