41,308 research outputs found
Symmetries in QFT
This document contains notes from the graduate lecture course, "Symmetries in
QFT" given by J.F.Wheater at Oxford University in Hilary term. The course gives
an informal introduction to QFT.Comment: Lecture note
Isobar-free neon isotope measurements of flux-fused potential reference minerals on a Helix-MC-Plus^(10K) mass spectrometer
This work presents new analytical techniques for extraction and analysis of neon from a suite of different mineral phases, including quartz, pyroxene, hematite, apatite, zircon, topaz, and fluorite. Neon was quantitatively extracted at 1100 °C from all of these minerals using an in-vacuum lithium borate-flux fusion technique. Evolved neon was purified using a cryogenic method capable of separating Ne from He present in abundances ~8 orders of magnitude higher, typical of samples carrying nucleogenic/radiogenic noble gases. The purified neon was measured on a Helix-MC-Plus^(10K) mass spectrometer that permits isobar-free measurement of all three neon isotopes. When operated at its highest mass resolving power (MRP) of ~10,300, the shoulder representing solely ²²Ne on the low mass-side of the ²²Ne-CO₂⁺² doublet is wide enough to permit measurement of isobar free ²²Ne. Operating in this mode comes with the penalty of a 50% reduction in neon sensitivity. Coupled with a mathematical isobar-stripping method, this approach excludes 99.5% of the CO₂⁺² while still collecting >99% of the ²²Ne beam. Routine edge-centering on the dynamic CO₂⁺² peak prior to introduction of a sample permits rapid and robust relocation of the desired measure point in the mass spectrum.
Cosmogenic ²¹Ne and ²²Ne concentrations obtained using these methods on the Cronus-A quartz and Cronus-P pyroxene international reference materials are in excellent agreement with previous work or expectations. Similarly, the concentration of nucleogenic ²¹Ne and ²²Ne in Durango apatite and the CIT hematite standard agree well with previous work. Durango apatite has notable heterogeneity in neon concentrations, consistent with previous observations of heterogeneous He, U and Th concentrations in this apatite. Nucleogenic neon concentrations are also presented for previously unstudied minerals including a Sri Lanka zircon (SLC), a topaz from the Imperial Topaz mine in Brazil (ITP1), and a fluorite (W-90) from New Hampshire. Taken together this set of potential reference minerals and the associated dataset provide a starting point for intercalibration among multiple mineral phases carrying ²¹Ne and ²²Ne of cosmogenic or nucleogenic origin
A New \u3ci\u3eFlexamia\u3c/i\u3e (Homoptera: Cicadellidae: Deltocephalinae) From Southern Michigan
A new species, Flexamia huroni, is described from a prairie fen in south- eastern Michigan. This leafhopper is closely related to the western F. serrata B & T, a specialist on mat muhly (Muhlenbergia richardsonis). Like its sister species, F. huroni was found only in close association with mat muhly, a grass listed as a threatened species in Michigan and Wisconsin. The regional rarity of mat muhly, its association with a globally imperiled plant commnity (prairie fen) and the absence of F. huroni from several fens known to contain this grass, make this new Flexamia a strong candidate for listing as endangered in Michigan
Multi-objective/loading optimization for rotating composite flexbeams
With the evolution of advanced composites, the feasibility of designing bearingless rotor systems for high speed, demanding maneuver envelopes, and high aircraft gross weights has become a reality. These systems eliminate the need for hinges and heavily loaded bearings by incorporating a composite flexbeam structure which accommodates flapping, lead-lag, and feathering motions by bending and twisting while reacting full blade centrifugal force. The flight characteristics of a bearingless rotor system are largely dependent on hub design, and the principal element in this type of system is the composite flexbeam. As in any hub design, trade off studies must be performed in order to optimize performance, dynamics (stability), handling qualities, and stresses. However, since the flexbeam structure is the primary component which will determine the balance of these characteristics, its design and fabrication are not straightforward. It was concluded that: pitchcase and snubber damper representations are required in the flexbeam model for proper sizing resulting from dynamic requirements; optimization is necessary for flexbeam design, since it reduces the design iteration time and results in an improved design; and inclusion of multiple flight conditions and their corresponding fatigue allowables is necessary for the optimization procedure
The answers are within me. An evaluation of a person centred counselling service for men at HMP Doncaster who have had experience of domestic violence 2005-2007
This report is the second year evaluation of the person centred counselling service for male victims and perpetrators of domestic violence at HMP Doncaster in 2006/7. This report follows on from the previous year's evaluation, Raging Anger Within Me, which evaluated this project in 2005/6. Initiated by the Doncaster Rape and Sexual Abuse Counselling Centre (DRSACC), the second year of counselling service delivery was also funded by Lloyds TSB and the Tudor Trust.
The report provides a background to the service offered, details the key factors in the service's success and makes recommendations for the future sustainability of this innovative service. The report also contains a particularly interesting section detailing how the appropriateness of the service is perceived by experienced prison staff
Field-guided proton acceleration at reconnecting X-points in flares
An explicitly energy-conserving full orbit code CUEBIT, developed originally
to describe energetic particle effects in laboratory fusion experiments, has
been applied to the problem of proton acceleration in solar flares. The model
fields are obtained from solutions of the linearised MHD equations for
reconnecting modes at an X-type neutral point, with the additional ingredient
of a longitudinal magnetic field component. To accelerate protons to the
highest observed energies on flare timescales, it is necessary to invoke
anomalous resistivity in the MHD solution. It is shown that the addition of a
longitudinal field component greatly increases the efficiency of ion
acceleration, essentially because it greatly reduces the magnitude of drift
motions away from the vicinity of the X-point, where the accelerating component
of the electric field is largest. Using plasma parameters consistent with flare
observations, we obtain proton distributions extending up to gamma-ray-emitting
energies (>1MeV). In some cases the energy distributions exhibit a bump-on-tail
in the MeV range. In general, the shape of the distribution is sensitive to the
model parameters.Comment: 14 pages, 4 figures, accepted for publication in Solar Physic
Calculation of inviscid flow over shuttle-like vehicles at high angles of attack and comparisons with experimental data
A computer code HALIS, designed to compute the three dimensional flow about shuttle like configurations at angles of attack greater than 25 deg, is described. Results from HALIS are compared where possible with an existing flow field code; such comparisons show excellent agreement. Also, HALIS results are compared with experimental pressure distributions on shuttle models over a wide range of angle of attack. These comparisons are excellent. It is demonstrated that the HALIS code can incorporate equilibrium air chemistry in flow field computations
Structural evaluation of candidate designs for the large space telescope primary mirror
Structural performance analyses were conducted on two candidate designs (Itek and Perkin-Elmer designs) for the large space telescope three-meter mirror. The mirror designs and the finite-element models used in the analyses evaluation are described. The results of the structural analyses for several different types of loading are presented in tabular and graphic forms. Several additional analyses are also reported: the evaluation of a mirror design concept proposed by the Boeing Co., a study of the global effects of local cell plate deflections, and an investigation of the fracture mechanics problems likely to occur with Cervit and ULE. Flexibility matrices were obtained for the Itek and Perkin-Elmer mirrors to be used in active figure control studies. Summary, conclusions, and recommendations are included
Understanding children as consumers
Kathy Hamilton reviews "Understanding children as consumers" which takes as its starting point the active role that children play within consumer culture, focusing primarily on children between 8 and 12 years old. David Marshall has edited a collection derived from a mixed set of disciplines including marketing, consumer research, developmental, applied and social psychology, modern history and organisation studies. It is split into four sections covering children as consumers, encountering marketing, kids' stuff and looking forward. Hamilton concludes that there is a range of interesting and relevant material presented. However, given the overall aim of the book, there would have been potential for more of the chapters to emphasise children's experiences in the marketplace from their perspective, to gain a greater understanding of children's agency within the consumption arena
Nuclear Model of Binding alpha-particles
The model of binding alpha-particles in nuclei is suggested. It is shown good
(with the accuracy of 1-2%) description of the experimental binding energies in
light and medium nuclear systems. Our preliminary calculations show enhancement
of the binding energy for super heavy nuclei with Z~120.Comment: 4 pages, 2 figures, Will be puplished in World Scientific as Procs.
Int. Symposium on Exotic Nuclei, "EXON - 2004", July 5 - 12, 2004, Peterhof,
Russi
- …