5,874 research outputs found

    A general purpose wideband optical spatial frequency spectrum analyzer

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    The light scattered at various angles by a transparent media is studied. An example of these applications is the optical Fourier spectrum measurement resulting from various spatial frequencies which were recorded on a photographic emulsion. A method for obtaining these measurements consists of illuminating the test object with parallel monochromatic light. A stationary lens, placed in the resulting wavefield at a distance of one focal length from the object, will focus parallel waves emanating from the test object at a point lying in the focal plane of the lens. A light detector with a small filtering aperture is then used to measure the intensity variation of the light in the focal or transform plane of the lens. Such measurements require the use of a lens which is highly corrected for all of the common aberrations except chromatic aberration

    Production-decay interferences at NLO in QCD for t-channel single-top production

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    We present a calculation of O(\alpha_s) contributions to the process of t-channel single-top production and decay, which include virtual and real corrections arising from interference of the production and decay subprocesses. The calculation is organized as a simultaneous expansion of the matrix elements in the couplings \alpha_{ew},\alpha_s and the virtuality of the intermediate top quark, (p_t^2-m_t^2)/m_t^2 ~ \Gamma_t/m_t, and extends earlier results beyond the narrow-width approximation.Comment: 33 pages, 6 Figure

    Cauchy horizon singularity without mass inflation

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    A perturbed Reissner-Nordstr\"om-de Sitter solution is used to emphasize the nature of the singularity along the Cauchy horizon of a charged spherically symmetric black hole. For these solutions, conditions may prevail under which the mass function is bounded and yet the curvature scalar RαβγδRαβγδR_{\alpha\beta\gamma\delta} R^{\alpha\beta\gamma\delta} diverges.Comment: typeset in RevTex, 13 page

    High-resolution 3D weld toe stress analysis and ACPD method for weld toe fatigue crack initiation

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    Weld toe fatigue crack initiation is highly dependent on the local weld toe stress-concentrating geometry including any inherent flaws. These flaws are responsible for premature fatigue crack initiation (FCI) and must be minimised to maximise the fatigue life of a welded joint. In this work, a data-rich methodology has been developed to capture the true weld toe geometry and resulting local weld toe stress-field and relate this to the FCI life of a steel arc-welded joint. To obtain FCI lives, interrupted fatigue test was performed on the welded joint monitored by a novel multi-probe array of alternating current potential drop (ACPD) probes across the weld toe. This setup enabled the FCI sites to be located and the FCI life to be determined and gave an indication of early fatigue crack propagation rates. To understand fully the local weld toe stress-field, high-resolution (5 mu m) 3D linear-elastic finite element (FE) models were generated from X-ray micro-computed tomography (mu-CT) of each weld toe after fatigue testing. From these models, approximately 202 stress concentration factors (SCFs) were computed for every 1 mm of weld toe. These two novel methodologies successfully link to provide an assessment of the weld quality and this is correlated with the fatigue performance

    Christian belief in the Religious Society of Friends (Quakers): a response to the claim that British Friends are post-Christian

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    In 1996 British Quaker Pink Dandelion published his PhD thesis, an extensive sociological survey of British Quakers. In his thesis Dandelion claimed that the Religious Society of Friends in Britain had become post-Christian. In response to Dandelion’s claim that Quakers are post-Christian, in 2005 and 2006 I conducted a short survey of the same population: the approximately 25,600 Members and Attenders of the Religious Society of Friends (Quakers) who are affiliated with Britain Yearly Meeting (the British national Quaker body). 1,035 of the 1,578 Quakers I approached responded to my questionnaire. Of these, 863 or 83.4% indicated that they believe in God. 751, or 72.6% of those who took part, indicated that they consider themselves to be Christian. 833, or 80.5% of those who took part, indicated that they would answer that they are Christian on an anonymous survey. Fewer than 5% of those who took part in the survey are clearly not Christian. This research suggests that the majority in the Religious Society of Friends in Britain still considers Quakers to be Christian. In the first chapter of this dissertation I examine the background of the debate about whether Quakers are a Christian group. In the second chapter I examine other surveys into Quaker belief. In the third chapter, I give the results of my survey and analyze some of the answers. In the fourth chapter, I introduce the three types of Christians that emerged from my results. In the fifth chapter I also look at some of the questions and, more importantly, the answers, giving examples from written comments. In the sixth chapter, I consider the concept of Toxic Language, the nature of belief within the Religious Society of Friends in Britain, the theories of Gay Pilgrim and also of Rex Ambler, and consider the importance of ‘Truth’ to Quakerism. Finally, I point to other areas of further research before giving my overall conclusions

    Electric power scheduling: A distributed problem-solving approach

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    Space Station Freedom's power system, along with the spacecraft's other subsystems, needs to carefully conserve its resources and yet strive to maximize overall Station productivity. Due to Freedom's distributed design, each subsystem must work cooperatively within the Station community. There is a need for a scheduling tool which will preserve this distributed structure, allow each subsystem the latitude to satisfy its own constraints, and preserve individual value systems while maintaining Station-wide integrity. The value-driven free-market economic model is such a tool

    A Nonpolymorphic Class I Gene in the Murine Major Histocompatibility Complex

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    DNA sequence analysis of a class I gene (QlO), which maps to the Qa2,3 locus in the C57BL/lO (H- 2b haplotype) mouse, reveals that it is almost identical to a cDNA clone (pH16) isolated from a SWR/J (H-2q haplotype) mouse liver cDNA library. Exon 5, in particular, has an unusual structure such that a polypeptide product is unlikely to be anchored in the cell membrane. Our findings suggest that the two sequences are derived from allelic class I genes, which are nonpolymorphic, in contrast to H-2K allelic sequences from the same mice, and they may encode liver-specific polypeptides of unknown function. Our previous studies indicate that the QlO gene is a potential donor gene for the generation of mutations at the H-2K locus by inter-gene transfer of genetic information. Thus the lack of polymorphism in class I genes at the QlO locus implies either that they are not recipients for such exchanges or that selective pressure prevents the accumulation of mutations in genes at this locus
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