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121.
H Tlaskalová-Hogenová R St?pánková L Tucková MA Farré DP Funda EF Verdú J Sinkora T Hudcovic Z Reháková B Cukrowska H Kozáková L Prokesová 《Canadian Metallurgical Quarterly》1998,43(5):545-550
Despite the fact that target antigens and the genetic basis of several autoimmune diseases are now better understood, the initial events leading to a loss of tolerance towards self-components remain unknown. One of the most attractive explanations for autoimmune phenomena involves various infections as possible natural events capable of initiating the process in genetically predisposed individuals. The most accepted explanation of how infection causes autoimmunity is based on the concept of "molecular mimicry" (similarity between the epitopes of an autoantigen and the epitopes in the environmental antigen). Infectious stimuli may also participate in the development of autoimmunity by inducing an increased expression of stress proteins (hsp), chaperones and transplantation antigens, which leads to abnormal processing and presentation of self antigens. Superantigens are considered to be one of the most effective bacterial components to induce inflammatory reactions and to take part in the development and course of autoimmune mechanisms. It has long been known that defects in the host defense mechanism render the individual susceptible to infections caused by certain microorganisms. Impaired exclusion of microbial antigens can lead to chronic immunological activation which can affect the tolerance to self components. Defects in certain components of the immune system are associated with a higher risk of a development of autoimmune disease. The use of animal models for the studies of human diseases with immunological pathogenesis has provided new insights into the influence of immunoregulatory factors and the lymphocyte subsets involved in the development of disease. One of the most striking conclusion arising from work with genetically engineered immunodeficient mouse models is the existence of a high level of redundancy of the components of the immune system. However, when genes encoding molecules involved in T cell immunoregulatory functions are deleted, spontaneous chronic inflammation of the gut mucosa (similar to human inflammatory bowel disease) develops. Surprisingly, when such immunocompromised animals were placed into germfree environment, intestinal inflammation did not develop. Impairment of the mucosal immune response to the normal bacterial flora has been proposed to play a crucial role in the pathogenesis of chronic intestinal inflammation. The use of immunodeficient models colonized with defined microflora for the analysis of immune reactivity will shed light on the mode of action of different immunologically important molecules responsible for the delicate balance between luminal commensals, nonspecific and specific components of the mucosal immune system. 相似文献
122.
Food allergies are causal factors for atopic dermatitis (AD) in 50% in infancy, in 20 to 30% in childhood, and only in 10 to 15% after puberty and in adulthood. Cow's milk, egg, fish, wheat, soy, nuts and citrus-fruits are the most proven allergens. Pseudoallergens, especially food-additiva, have to be regarded too. For the proof of the clinical relevance that food allergy is causing AD a positive result of elimination and provocation has to be required. When by these diagnostic procedure a special food is found as causing the AD it has to be eliminated in the diet of this patient. In severe cases of AD semi-elementary respectively few foods diets may be necessary. However in most cases of AD the "diet of choice" is an age related normal nutrition. To delay respectively to avoid the manifestation of atopy special recommendations for the nutrition of high risk newborns and infants (especially long breast feeding, late solid feeding) should be considered. 相似文献
123.
Asbjørn Solheim Sverre Rolseth Egil Skybakmoen Lisbet Støen Åsmund Sterten Trond Støre 《Metallurgical and Materials Transactions B》1996,27(5):739-744
Temperatures for primary crystallization of Na3AlF6 in multicomponent electrolyte systems of interest for the aluminum electrolysis process were determined by thermal analysis. The results are presented as binary and quasibinary diagrams and discussed in view of the literature data. An empirical equation describing liquidus temperatures for primary crystallization of Na3AlF6 was derived: $$\begin{gathered} t/(^\circ C) = 1011 + 0.50[AlF_3 ] - 0.13[AIF_3 ] - \frac{{3.45[CaF_2 ]}}{{1 + 0.0173[CaF_2 ]}} \hfill \\ + 0.124[CaF_2 ] \cdot [AlF_3 ] - 0.00542([CaF_2 ] \cdot [AlF_3 ])^{1.5} \hfill \\ - \frac{{7.93[Al_2 O_3 ]}}{{1 + 0.0936[Al_2 O_3 ] - 0.0017[Al_2 O_3 ]^2 - 0.0023[AlF_3 ] \cdot [Al_2 O_3 ]}} \hfill \\ - \frac{{8.90[LiF]}}{{1 + 0.0047[LiF] + 0.0010[AlF3]^2 }} - 3.95[MgF_2 ] - 3.95 \hfill \\ \end{gathered} $$ wheret is the temperature in degree Celsius and the square brackets denote the weight percent of components in the system Na3AlF6-AlF3-CaF2-Al2O3-LiF-MgF2-KF. The composition limitations are [AlF3] ≈ [CaF2] ≈ [LiF] < 20 wt pct, [MgF2] ≈ [KF] < 5 wt pct, and [A12O3] up to saturation. 相似文献
124.
This paper presents an assumption/commitment specification technique and a refinement calculus for networks of agents communicating asynchronously via unbounded FIFO channels in the tradition of Kahn. We define two types of assumption/commitment specifications, namely simple and general specifications. It is shown that semantically, any deterministic agent can be uniquely characterized by a simple specification, and any nondeterministic agent can be uniquely characterized by a general specification. We define two sets of refinement rules, one for simple specifications and one for general specifications. The rules are Hoare-logic inspired. In particular the feedback rules employ invariants in the style of a traditional while-rule. Both sets of rules have been proved to be sound and also (semantic) relative complete. Conversion rules allow the two logics to be combined. This means that general specifications and the rules for general specifications have to be introduced only at the point in a system development where they are really needed. 相似文献
125.
Surrogate modeling approximation using a mixture of experts based on EM joint estimation 总被引:1,自引:1,他引:0
Dimitri Bettebghor Nathalie Bartoli Stéphane Grihon Joseph Morlier Manuel Samuelides 《Structural and Multidisciplinary Optimization》2011,43(2):243-259
An automatic method to combine several local surrogate models is presented. This method is intended to build accurate and
smooth approximation of discontinuous functions that are to be used in structural optimization problems. It strongly relies
on the Expectation−Maximization (EM) algorithm for Gaussian mixture models (GMM). To the end of regression, the inputs are
clustered together with their output values by means of parameter estimation of the joint distribution. A local expert is
then built (linear, quadratic, artificial neural network, moving least squares) on each cluster. Lastly, the local experts
are combined using the Gaussian mixture model parameters found by the EM algorithm to obtain a global model. This method is
tested over both mathematical test cases and an engineering optimization problem from aeronautics and is found to improve
the accuracy of the approximation. 相似文献
126.
本文就目前国际上对以太网基本性能测量的指标进行整理和分析并给出了相应的测试方法。 相似文献
127.
Lars Mönch John W. Fowler Stéphane Dauzère-Pérès Scott J. Mason Oliver Rose 《Journal of Scheduling》2011,14(6):583-599
In this paper, we discuss scheduling problems in semiconductor manufacturing. Starting from describing the manufacturing process,
we identify typical scheduling problems found in semiconductor manufacturing systems. We describe batch scheduling problems,
parallel machine scheduling problems, job shop scheduling problems, scheduling problems with auxiliary resources, multiple
orders per job scheduling problems, and scheduling problems related to cluster tools. We also present important solution techniques
that are used to solve these scheduling problems by means of specific examples, and report on known implementations. Finally,
we summarize some of the challenges in scheduling semiconductor manufacturing operations. 相似文献
128.
Christian Bessiere Stéphane Cardon Romuald Debruyne Christophe Lecoutre 《Constraints》2011,16(1):25-53
In this paper, we propose two original and efficient approaches for enforcing singleton arc consistency. In the first one,
the data structures used to enforce arc consistency are shared between all subproblems where a domain is reduced to a singleton.
This new algorithm is not optimal but it requires far less space and is often more efficient in practice than the optimal
algorithm SAC-Opt. In the second approach, we perform several runs of a greedy search (where at each step, arc consistency
is maintained), possibly detecting the singleton arc consistency of several values in one run. It is an original illustration
of applying inference (i.e., establishing singleton arc consistency) by search. Using a greedy search allows benefiting from
the incrementality of arc consistency, learning relevant information from conflicts and, potentially finding solution(s) during
the inference process. We present extensive experiments that show the benefit of our two approaches. 相似文献
129.
Adaptive IPTV services based on a novel IP Multimedia Subsystem 总被引:1,自引:1,他引:0
Julien Arnaud Daniel Négru Mamadou Sidibé Julien Pauty Harilaos Koumaras 《Multimedia Tools and Applications》2011,55(2):333-352
Heterogeneous communication devices are emerging and changing the way of communication. Innovative multimedia applications
are now accessible through these embedded systems. The 3GPP IP Multimedia Subsystem (IMS) provides a basic architecture framework
for the Next Generation Network (NGN) supporting the convergence platform for service provisioning in heterogeneous networks.
ETSI TISPAN standardization effort focuses on delivering IPTV services on such platform. Nevertheless, IPTV on IMS standardization
suffers from a lack of efficient user-centric network management mechanisms as the end-user may consume IPTV service from
different access networks, on different mobile devices, at anytime. User’s Perceived Quality of Service (PQoS) or Quality
of Experience (QoE) of IPTV service may also suffer from wireless access network impairments. This paper introduces new functionalities
in IPTV over IMS architecture which optimize satisfaction of the end-user and resource utilization of the operator’s networks.
A context-sensitive User Profile (UP) model is used to deliver IPTV streams adapted to the user’s environment. In order to
optimize the operator network usage, the impact of spatiotemporal dynamics of the video content on the deduced perceptual
quality is considered. A Multimedia Content Management System (MCMS) is proposed to perform dynamic cross-layer adaptation
of the IPTV stream based on PQoS measurements at the end-user side. 相似文献
130.