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61.
Analysis of carbohydrates and glycoconjugates by matrix‐assisted laser desorption/ionization mass spectrometry: An update for 2009–2010 下载免费PDF全文
David J. Harvey 《Mass spectrometry reviews》2015,34(3):268-422
62.
The oxidation products formed at 500 and 700°C on an amorphous Ta-44.5 at% Ir alloy in an Ar-0.1% O2 gas mixture were characterized using SEM, XRD, EPMA, TEM, STEM, AES, and XPS. Initially, a thin (3–4 nm) layer of Ta2O5 formed at the surface of the alloy. Continued growth of the Ta2O5, which occurred very rapidly, involved diffusion of oxygen anions from the Ta2O5/gas interface to the alloy/Ta2O5 interface, where tantalum was selectively oxidized. Because the oxide grew more quickly than iridium could diffuse back into the alloy, the iridium coalesced into platelets of crystalline iridium-rich alloy that were oriented approximately parallel to the oxide/alloy interface, and which became embedded in a matrix of Ta2O5. The unoxidized core remained in the glassy state. The oxidation process and/or the dissolution of oxygen into the unoxidized alloy caused the alloy to become embrittled. 相似文献
63.
64.
Catherine Easton 《Universal Access in the Information Society》2013,12(1):105-114
Research indicates that inaccessible website design persists despite the existence of anti-discrimination legislation and the influence of the social model of disability on policy development. In this paper, the concept of universal access is examined in the light of the social model of disability in relation to both the physical and virtual environments. The manner in which disability is often deemed a design afterthought is highlighted. The need for universal access is then placed alongside a discussion of access to the Internet in relation to an ageing population and people with cognitive difficulties. Subsequently, anti-discrimination provisions are analysed in relation to how they support designers’ focus on an accepted normality to which reasonable adjustments need to be made, rather than the acquisition of full universal access. 相似文献
65.
Allowing users to actively participate in the development and implementation of a new IS is supposed to increase their satisfaction with it. This type of participation, representing aspects relating to distributive and procedural justice, is increasingly impractical in current organizational settings, because many IS are used by thousands of employees and having them involved is impossible. Nonetheless, there are still benefits to be gained in other ways. Extrapolating from interactional justice, we proposed a passive participation method of engaging users. Its effect was tested in a large company in the USA and proved effective. Interactional justice, the perception of fairness in the way that people were treated at an interpersonal level, was found to increase user assessment of the value of their IS. Implications and expansions to interactional justice theory and how this antecedent affects IS implementation are discussed. 相似文献
66.
Havasi Catherine Speer Robert Pustejovsky James Lieberman Henry 《Intelligent Systems, IEEE》2009,24(4):24-35
Understanding the world we live in requires access to a large amount of background knowledge: the commonsense knowledge that most people have and most computer systems don't. Many of the limitations of artificial intelligence today relate to the problem of acquiring and understanding common sense. The Open Mind Common Sense project began to collect common sense from volunteers on the Internet starting in 2000. The collected information is converted to a semantic network called ConceptNet. Reducing the dimensionality of ConceptNet's graph structure gives a matrix representation called AnalogySpace, which reveals large-scale patterns in the data, smoothes over noise, and predicts new knowledge. Extending this work, we have created a method that uses singular value decomposition to aid in the integration of systems or representations. This technique, called blending, can be harnessed to find and exploit correlations between different resources, enabling commonsense reasoning over a broader domain. 相似文献
67.
Attenuation correction is an important part of accurate image reconstruction in positron tomography. The usual correction method involves direct measurement of attenuation correction factors (ACFs). A reconstruct-reproject method, which has been suggested as providing superior noise properties, is sometimes employed; an attenuation image is first reconstructed from the measurement and then ACFs are obtained by reprojection through this image. Here the authors present a model which follows the signal-to-noise ratio (SNR) through the attenuation correction by both the direct and reconstruct-reproject methods. This model is applicable to both 2D and 3D imaging geometry, but applies to the central elements of emission and transmission objects with circular symmetry and constant amplitude. For this simplified geometry, the model predicts that the SNR of the emission image following attenuation correction is the same for both direct and reconstruct-reproject methods, although the SNRs of the ACFs are themselves substantially different. The authors also present the measured SNR at the various steps of attenuation correction for both the direct and reconstruct-reproject methods using simulated transmission and emission data. The measured SNRs agree with the model; no significant difference between the direct and reconstruct-reproject SNRs was observed. 相似文献
68.
The motionless-head parallel-readout optical-disk system is designed to read out two-dimensional bit planes that are stored as one-dimensional Fourier-transform computer-generated holograms distributed radially on the disk active surface. Such a system, when built at full scale, could offer several potential advantages: high data-transfer rates of 1 Gbyte/s and higher, low access times of less than 15 ms, low retrieval times (the time required to read the entire memory) of less than 25 ms, and simple optical implementation. The experimental results of a scaled-down implementation of the system are presented. 相似文献
69.
Harvey JE 《Applied optics》1995,34(19):3715-3726
Residual surface roughness over the entire range of relevant spatial frequencies must be specified and controlled in many high-performance optical systems. This is particularly true for enhanced reflectance multilayers if both high reflectance and high spatial resolution are desired. If we assume that the interfaces making up a multilayer coating are uncorrelated at high spatial frequencies (microroughness) and perfectly correlated at low spatial and midspatial frequencies, then the multilayer can be thought of as a surface power spectral density (PSD) filter function. Multilayer coatings thus behave as a low-pass spatial frequency filter acting on the substrate PSD, with the exact location and shape of this cutoff being material and process dependent. This concept allows us to apply conventional linear systems techniques to the evaluation of image quality and to the derivation of optical fabrication tolerances for applications utilizing enhanced reflectance x-ray multilayers. 相似文献
70.
The objective of this paper is to propose an architecture for aCAble TeleVision (CATV) network, capable of supporting two-way transmission. This evolution is necessary for the survival of the CATV industry in an era of deregulation and of the development of the B-ISDN by the telecommunications companies. A communication transactional service is then considered and performance analysis is done under realistic assumptions. 相似文献