Ultrahigh vacuum gauge having two collector electrodes

A gauge for measuring ultrahigh vacuums with great accuracy is described. It provides a means for ionizing the gas whose pressure is being measured, and consists of a collector electrode, a suppressor, radiation shielding, and a second collector

An electron backscatter diffraction study of geesops: a broader view of trilobite vision?

The calcite eyes of trilobites have been studied for over 100 years using methods including light microscopy (e.g. Clarke 1889; Campbell 1975; Towe 1973; Clarkson 1979 and Bruton and Haas 2003) and more recently cathodoluminescence (CL) imaging coupled with scanning electron microscopy (SEM) of samples etched in EDTA (Miller and Clarkson 1980). This work has provided a great deal of information on the mechanisms by which lenses collected light, drawing attention to the importance of the crystallographic orientation of lens calcite for focusing, and leading to sophisticated models of trilobite vision (Clarkson and Levi-Setti, 1975; Gál et al., 2000). The morphology and mode of life of phacopids, in particular Geesops, are well understood (Bruton and Haas, 2003a; 2003b) but observations on the internal structure of their lenses contradict the generally accepted models for image formation by schizochroal eyes. Recent technological advances have given new impetus to the analysis of crystalline materials and especially important has been electron backscatter diffraction (EBSD). This is a SEM-based technique that can be used to accurately ‘map’ variations in the crystallographic orientation of a sample down to the sub-micrometre scale by recording on a sensitive camera Kikuchi patterns that are formed by diffraction of an electron beam when focused on a polished sample tilted at 70°. Although this technique has been understood for over 50 years (Alam et al., 1954) and has been extensively used in disciplines such as metallography (Humphreys, 2001), until recently its Earth Science applications were limited to studies of structural geology and petrology (Nuchter and Stockhert, 2007). Recent applications of EBSD to biomineralisation research (Dalbeck and Cusack, 2006; Griesshaber et al., 2007) have mapped the crystal orientation and microstructure of calcite shells and in 2006 Lee et al. were able to apply this technique to investigating the microstructure of lenses in the schizochroal eye of Dalmanites. This paper describes results of an EBSD study of eyes of Geesops schlotheimi (Bronn, 1825) combined with more traditional microscopy techniques to reveal new aspects of trilobite lens structure

Absence of kinetic effects in reaction-diffusion processes in scale-free networks

We show that the chemical reactions of the model systems of A+A->0 and A+B->0 when performed on scale-free networks exhibit drastically different behavior as compared to the same reactions in normal spaces. The exponents characterizing the density evolution as a function of time are considerably higher than 1, implying that both reactions occur at a much faster rate. This is due to the fact that the discerning effects of the generation of a depletion zone (A+A) and the segregation of the reactants (A+B) do not occur at all as in normal spaces. Instead we observe the formation of clusters of A (A+A reaction) and of mixed A and B (A+B reaction) around the hubs of the network. Only at the limit of very sparse networks is the usual behavior recovered.Comment: 4 pages, 4 figures, to be published in Physical Review Letter

Microstructure and growth of the lenses of schizochroal trilobite eyes

Lenses within the schizochroal eyes of phacopine trilobites are made principally of calcite and characterisation of them using light microscopy and high-resolution electron imaging and diffraction has revealed an array of microstructural arrangements that suggest a common original pattern across the suborder. The low convexity lenses of Odontochile hausmanni and Dalmanites sp. contain calcite fibres termed trabeculae. The c axis of trabecular calcite lies parallel to the lens axis, and adjacent trabeculae are distinguished by small differences in their a axis orientations. Despite the common alignment, the boundaries between trabeculae cross-cut the c axis as they fan out towards the lens base. Trabeculae are absent from the lens immediately beneath the visual surface and instead a radial fringe is present and is composed of micrometre-thick sheets of calcite whose c axes are oriented at a low angle to the visual surface. High convexity lenses are more common than those of lower convexity among the species studied, and they have a much thicker radial fringe. Beneath this fringe all of the lens calcite is oriented with its c axis parallel to the lens axis and it lacks trabeculae. We propose that both the high and low convexity lenses formed by rapid growth of calcite from a surface that migrated inwards from the cornea, and they may have had an amorphous calcium carbonate precursor. The trabeculae and radial fringes are unlikely to have had any beneficial effect on the transmission or focusing of light but rather are the outcomes of an elegant solution to the problem of how to construct a biconvex lens from a crystalline solid

Lunar mass spectrometer test program

The procedures are described along with results obtained in a test program conducted to demonstrate the performance of a candidate lunar mass spectrometer. The instrument was designed to sample and measure gases believed to exist in the lunar atmosphere at the surface. The subject instrument consists of a cold cathode ion source, a small quadrupole mass analyzer and an off axis electron multiplier ion counting detector. The major program emphasis was placed on demonstrating instrument resolution, sensitivity and S/N ratio over the mass range 0-150 amu and over a partial pressure range from 10 to the minus 9th power to 10 to the minus 13th power torr. Ultrahigh vacuum tests were conducted and the minimum detectable partial pressure for neon, argon, krypton and xenon was successfully determined for the spectrometer using isotopes of these gases. With the exception of neon, the minimum detectable partial pressure is approximately 4 x 10 to the minus 14th power torr for the above gases

Framework for the Integration of Service and Technology Strategies

Organised by: Cranfield UniversityAfter sales service is a highly profitable business for manufacturers of technology-driven products. Due to this fact competitors want to share in high profit margins. At the same time after sales business has to deal with an increasing range of variants of products and technologies, shorter life cycles and changing customer demands. In spite of these manifold challenges, often neither after sales departments are involved in the early product development stage nor are customer demands and technical parameters considered in the service development processes entirely. Therefore an integration of service and technology strategies is necessary. This paper presents a framework for this integration that visualises the complex interdependencies and interfaces between service as well as product and motor vehicle workshop technologies.Mori Seiki – The Machine Tool Compan

The Case of Climate Change

In recent years, a growing literature has focused on how the EU is perceived beyond its borders. One of the aims of these studies is to shed light on the ability of the EU to exercise external influence. This working paper argues, however, that outsiders’ perceptions of the EU are not necessarily a reliable guide to the EU’s external influence. It illustrates the argument by examining the case of climate change in which, despite broadly positive external perceptions, the EU has often failed in attempts to influence the positions of other states. Focusing on Chinese and Indian perceptions of the EU, the current paper argues that this apparent tension results from the fact that the EU on the one hand, and China and India on the other, have framed global climate governance in starkly contrasting ways. In particular, they have differed with respect to whether “climate leadership” by the EU should generate “followership” on the part of China and India. This paper uses the example of negotiations on a “second commitment period” under the Kyoto Protocol to demonstrate this point. It concludes by urging that greater attention be paid to the relationship between external perceptions and external influence

the limits of diffusion in EU relations with China and India

1\. Introduction 5 2\. Diffusion and Domestic Politics 7 3\. European and Global Ideas Concerning Climate Change Mitigation 9 4\. Limited Socialization and Lesson-Drawing: The Development of Chinese Climate Change Policy 12 5\. Resistance to Diffusion: The Development of Indian Climate Change Policy 18 6\. Conclusions 23 Literature 25The EU has for a long time claimed the title of “leader” in the international politics of climate change. However, existing research has generally failed to specify whether the EU’s purported leadership has induced the “followership” of other states. This working paper seeks to shed light on this somewhat neglected topic by examining the attempted diffusion of climate change norms, policies, and institutions by the EU to China and India. The paper makes two principal arguments. First, the development of Chinese and Indian climate change policy should be understood as primarily domestic developments. Nonetheless, there was limited evidence of diffusion from the EU, but there was significant variation between the Chinese and Indian responses to the EU’s diffusion attempts. The Chinese response was one increasing accommodation; the Indian response was a more straightforward case of resistance. Second, domestic factors help to explain the variation in the Chinese and Indian responses to EU attempts at diffusion and, related, the observed pattern of diffusion from the EU to China and India. Particularly important is the degree to which new external ideas and concepts resonate with pre-existing domestic ideas and concepts. The paper thus paints a picture of limited EU leadership, but also suggests that the EU attempts to secure “followership” could be enhanced by paying greater attention to the domestic politics and preferences of third countries