Constraints on low energy QCD parameters from η→3π\eta \to 3\pi and ππ\pi\pi scattering

The $\eta \to 3\pi$ decays are a valuable source of information on low energy QCD. Yet they were not used for an extraction of the three flavor chiral symmetry breaking order parameters until now. We use a Bayesian approach in the framework of resummed chiral perturbation theory to obtain constraints on the quark condensate and pseudoscalar decay constant in the chiral limit. We compare our results with recent CHPT and lattice QCD fits and find some tension, as the $\eta \to 3\pi$ data seem to prefer a larger ratio of the chiral order parameters. The results also disfavor a very large value of the pseudoscalar decay constant in the chiral limit, which was found by some recent works. In addition, we present results of a combined analysis including $\eta \to 3\pi$ decays and $\pi\pi$ scattering and though the picture does not changed appreciably, we find some tension between the data we use. We also try to extract information on the mass difference of the light quarks, but the uncertainties prove to be large.Comment: 23 pages, 8 figure

Cumulative Trauma Disorders: OSHA\u27s General Duty Clause and the Need for an Ergonomics Standard

This Note argues that neither the Act nor its underlying policies supports OSHA\u27s current use of the general duty clause to prosecute alleged ergonomics violations and that the only way to protect workers from CTDs fairly and effectively is through the promulgation of an ergonomics standard. Part I examines the purposes of the Act, as well as the function of the Act\u27s general duty clause. Part II analyzes the four requirements of the general duty clause in the context of CTDs and finds that the clause does not apply to CTDs. Part III argues that the Act\u27s intended policies support the promulgation of an ergonomics standard rather than the use of the general duty clause. This Note concludes that the Secretary of Labor should promulgate an ergonomics standard33 as soon as possible and that, until then, the general duty clause should not be used to prosecute employers for alleged ergonomics violations

A Study of Laser Ablation Propulsion Using Polyoxymethelyne and a High Power Diode Laser

With an increased interest by universities, government and commercial groups in using constellations of pico and and nano satellites, the need for micro-thrusters to aid in the station-keeping capabilities has become strong. This report examines using polymers and a laser to ablate material as a potential propulsion option for station-keeping. Homopolymer polyoxymethelyne (POM), commonly known as Delrin™, was tested as a fuel for a high powered (20 Watt 980 nm) solid state diode laser ablation thruster to be used for station-keeping on pico and nano sized satellites. The experiments required a partial vacuum to reduce the effects of air decomposition and remove water vapor during the ablation event. The vacuum chamber, shadowgraph, and an impulse measurement system were all designed and built around the 20-Watt laser. Three different sample thicknesses were tested (.005 , .010 , and .020 ) to determine the behavior of the polymer. The laser was focused onto the POM sample, which was mounted to a load cell and calibrated to measure the impulse of the system imparted by the laser pulse. The calculated thrust values ranged from 600 µN to 1300 µN with a high uncertainty due to the small sample size. The exhaust plume from the ablation event was captured using a shadowgraph. A low velocity was recorded because the chamber was not a complete vacuum, causing the exhaust plume to collide with the air molecules in the test chamber. However the load cell results suggested that 1.30 mN per burst can be produced with an uncertainty of 30%. With the work outlined in this paper, POM shows the promise and challenge of being a good candidate as a fuel material. POM warrants further development and investment as a fuel to be used with a laser ablation micro-thruster

Analysis of CO₂ leakage through "low-permeability" faults from natural reservoirs in the Colorado Plateau, southern Utah

The numerous CO2 reservoirs in the Colorado Plateau region of the United States are natural analogues for potential geologic CO2 sequestration repositories. To better understand the risk of leakage from reservoirs used for long-term underground CO2 storage, we examine evidence for CO2 migration along two normal faults from a reservoir in east-central Utah. CO2 -charged springs, geysers, and a hydrocarbon seep are localised along these faults. These include natural springs that have been active for long periods of time, and springs that were induced by recent drilling. The CO2 -charged spring waters have deposited travertine mounds and carbonate veins. The faults cut siltstones, shales, and sandstones and the fault rocks are fine-grained, clay-rich gouge, generally thought to be barriers to fluid flow. The geologic and geochemical data are consistent with these faults being conduits for CO2 to the surface. Consequently, the injection of CO2 into faulted geologic reservoirs, including faults with clay gouge, must be carefully designed and monitored to avoid slow seepage or fast rupture to the biosphere