Three-dimensional magnetostatic models of the large-scale corona

A special class of magnetostatic equilibria is described, which are mathematically simple and yet sufficiently versatile so as to fit any arbitrary normal magnetic flux prescribed at the photosphere. With these solutions, the corona can be modeled with precisely the same mathematically simple procedure as has previously been done with potential fields. The magnetostatic model predicts, in addition to the coronal magnetic field, the three dimensional coronal density which can be compared with coronagraph observations

An investigation of the plastic fracture of high strength steels

Three generally recognized stages of plastic fracture in high strength steels are considered in detail. These stages consist of void initiation, void growth, and void coalescence. A brief review of the existing literature on plastic fracture is included along with an outline of the experimental approach used in the investigation

New thermocouple-based microwave/millimeter-wave power sensor MMIC techniques in GaAs

We describe a new RF and microwave power sensor monolithic microwave integrated circuit design. The circuit incorporates a number of advances over existing designs. These include a III–V epitaxial structure optimized for sensitivity, the figure-of-merit applicable to the optimization, a mechanism for in-built detection of load ageing and damage to extend calibration intervals, and a novel symmetrical structure to linearize the high-power end of the scale

Chlamydia control activities in Europe: cross-sectional survey

Background: Chlamydia is the most commonly reported bacterial sexually transmitted infection in Europe. The objective of the Screening for Chlamydia in Europe (SCREen) project was to describe current and planned chlamydia control activities in Europe. Methods: The authors sent a questionnaire asking about different aspects of chlamydia epidemiology and control to public health and clinical experts in each country in 2007. The principles of sexually transmitted infection control were used to develop a typology comprising five categories of chlamydia control activities. Each country was assigned to a category, based on responses to the questionnaire. Results: Experts in 29 of 33 (88%) invited countries responded. Thirteen of 29 countries (45%) had no current chlamydia control activities. Six countries in this group stated that there were plans to introduce chlamydia screening programmes. There were five countries (17%) with case management guidelines only. Three countries (10%) also recommended case finding amongst partners of diagnosed chlamydia cases or people with another sexually transmitted infection. Six countries (21%) further specified groups of asymptomatic people eligible for opportunistic chlamydia testing. Two countries (7%) reported a chlamydia screening programme. There was no consistent association between the per capita gross domestic product of a country and the intensity of chlamydia control activities (P = 0.816). Conclusion: A newly developed classification system allowed the breadth of ongoing national chlamydia control activities to be described and categorized. Chlamydia control strategies should ensure that clinical guidelines to optimize chlamydia diagnosis and case management have been implemented before considering the appropriateness of screening programmes

Commuting Position and Momentum Operators, Exact Decoherence and Emergent Classicality

Inspired by an old idea of von Neumann, we seek a pair of commuting operators X,P which are, in a specific sense, "close" to the canonical non-commuting position and momentum operators, x,p. The construction of such operators is related to the problem of finding complete sets of orthonormal phase space localized states, a problem severely constrained by the Balian-Low theorem. Here these constraints are avoided by restricting attention to situations in which the density matrix is reasonably decohered (i.e., spread out in phase space). Commuting position and momentum operators are argued to be of use in discussions of emergent classicality from quantum mechanics. In particular, they may be used to give a discussion of the relationship between exact and approximate decoherence in the decoherent histories approach to quantum theory.Comment: 28 pages, RevTe

Towards a High Energy Theory for the Higgs Phase of Gravity

Spontaneous Lorentz violation due to a time-dependent expectation value for a massless scalar has been suggested as a method for dynamically generating dark energy. A natural candidate for the scalar is a Goldstone boson arising from the spontaneous breaking of a U(1) symmetry. We investigate the low-energy effective action for such a Goldstone boson in a general class of models involving only scalars, proving that if the scalars have standard kinetic terms then at the {\em classical} level the effective action does not have the required features for spontaneous Lorentz violation to occur asymptotically $(t \to \infty)$ in an expanding FRW universe. Then we study the large $N$ limit of a renormalizable field theory with a complex scalar coupled to massive fermions. In this model an effective action for the Goldstone boson with the properties required for spontaneous Lorentz violation can be generated. Although the model has shortcomings, we feel it represents progress towards finding a high energy completion for the Higgs phase of gravity.Comment: 20 pages, 5 figures;fixed typos and added reference

Radiative decay Z_H-> \gamma A_H in the little Higgs model with T-parity

In the little Higgs model with T-parity (LHTM), the only tree-level kinematically allowed two-body decay of the Z_H boson is Z_H-> A_H H and thus one-loop induced two-body decays may have a significant rate. We study the Z_H-> \gamma A_H decay, which is induced at the one-loop level by a fermion triangle and is interesting as it depends on the mechanism of anomaly cancellation of the model. All the relevant two- and three-body decays of the Z_H gauge boson arising at the tree-level are also calculated. We consider a small region of the parameter space where the scale of the symmetry breaking f is still allowed to be as low as 500 GeV by electroweak precision data. We first analyze the scenario of a Higgs boson with a mass of 120 GeV. We found that the Z_H->\gamma A_H branching ratio can be of the order of a tree-level three-body decay and may be at the reach of detection at the LHC for f close to 500 GeV, but it may be difficult to detect for f=1 TeV. There is also an scenario where the Higgs boson has an intermediate mass such that the Z_H-> A_H H decay is closed, the Z_H-> \gamma A_H gets considerably enhanced and the chances of detection get a large boost.Comment: 19 pages, 9 figures, 2 table

Understanding light in lightweight fabric (ETFE foil) structures through field studies

This paper presents an experimental approach to investigate the luminous environment in lightweight fabric structures through field study. Buildings selected for the field study included the Engineering Science Learning Centre at the University of Nottingham and the Clarke Quay in Singapore. By undertaking on site monitoring under different sky conditions in the chosen buildings with distinctively different site context, this research project explores how the typical homogeneously lit and rather dull luminous environment in lightweight fabric structure can be improved for enhanced visual interest, visual comfort, and three-dimensional modelling under both sunny and overcast sky conditions. Research data obtained from the subjective appreciation of the internal luminous environments and the quantitative spot measurement and mapping of light are compared and discussed. This study concluded that selective use of transparent and translucent components in the ETFE envelope can offer architectural designers the opportunities to create well balanced, yet dynamic lit scenes. Also by combining single skin ETFE foil and the double or triple layered ETFE cushion and introducing ETFE cushions with different light transmittance to the building envelope can help improve the overall visual and luminous environment and enhance task illumination. The key findings from this research work are applicable to the design of light in lightweight fabric structure in general

Sintering of titanium with yttrium oxide additions for the scavenging of chlorine impurities

Chloride impurities in titanium powders are extremely difficult to remove and present a long-standing problem in titanium powder metallurgy. We show that the detrimental effects of chlorides on the sintering of titanium can be mitigated with trace additions of yttrium oxide, which has a high affinity for the normally volatile species and forms highly stable oxychloride reaction products. Compacts that would otherwise exhibit gross swelling and excessive porosity due to chloride impurities can be now sintered to near full density by liquid phase sintering. The potency of yttrium oxide additions is observable at levels as low as 500 ppm. The scavenging of chlorine by YO appears to be independent of alloy composition and sintering regime. It is effective when used with high-chloride powders such as Kroll sponge fines but ineffective when used with powders containing NaCl impurities or during solid-state sintering. The identification of highly potent chlorine scavengers may enable the future development of chloride-tolerant powder metallurgy (PM) alloys aimed at utilizing low-cost, high-chloride powder feedstocks

Corrections to deuterium hyperfine structure due to deuteron excitations

We consider the corrections to deuterium hyperfine structure originating from the two-photon exchange between electron and deuteron, with the deuteron excitations in the intermediate states. In particular, the motion of the two intermediate nucleons as a whole is taken into account. The problem is solved in the zero-range approximation. The result is in good agreement with the experimental value of the deuterium hyperfine splitting.Comment: 7 pages, LaTe