032ChemInform Abstract The title compounds M(AuF6)2 (M: Mg, Ca, Sr, Ba) are prepared by reacting MF2, Au and KrF2 in anhydrous HF at 0-20 rc C. Their structures are elucidated by Raman spectroscopy and by powder XRD. The compounds Mg(AuF6)2 and Ca(AuF6)2 elong to the space group P4 with Z=1 and the compounds Sr(AuF6)2 and Ba(AuF6)2 crystallize in the space group P43m or P23 (no distinction can be made, so far) with Z=4. The structure of the four compounds consists of AuF6-octahedra and M2+ cations. Further eatures of the structures are discussed.
Systemic rheumatological diseases are often accompanied by the development of central and peripheral nervous system pathology. Data providing evidence of the high incidence of peripheral nervous system lesions in systemic lupus erythematosus and systemic scleroderma are presented. These diseases in particular are characterized by polyneuropathies and tunnel syndromes. Our own observations, along with published data, revealed the following major pathogenetic mechanisms of peripheral nervous system lesions in diffuse connective tissue diseases - ischemic, immunological, and metabolic. Consideration of these mechanisms will lead to pathogenetically based treatment and improved therapeutic outcomes.
Search engines became a de facto place to start information acquisition on the Web. Though due to web spam phenomenon, search results are not always as good as desired. Moreover, spam evolves that makes the problem of providing high quality search even more challenging. Over the last decade research on adversarial information retrieval has gained a lot of interest both from academia and industry. In this paper we present a systematic review of web spam detection techniques with the focus on algorithms and underlying principles. We categorize all existing algorithms into three categories based on the type of information they use: content-based methods, link-based methods, and methods based on non-traditional data such as user behaviour, clicks, HTTP sessions. In turn, we perform a subcategorization of link-based category into five groups based on ideas and principles used: labels propagation, link pruning and reweighting, labels refinement, graph regularization, and featurebased. We also define the concept of web spam numerically and provide a brief survey on various spam forms. Finally, we summarize the observations and underlying principles applied for web spam detection.
A frequent manifestation of multiple sclerosis (MS) is chronic fatigue syndrome, which can be defined as a subjective decrease in the level of physical and/or mental energy. Chronic fatigue syndrome can be divided into asthenia (fatigue at rest), pathological fatigability (fatigue on physical loading), and fatigue on the background of deterioration of other symptoms (exacerbation of MS). There are both central and peripheral mechanisms for the formation of fatigue. The combination of fatigue and affective disturbances, especially depression and sleep disorders (insomnia, restless legs syndrome) is common in MS and may provide evidence that they share common mechanisms--decreases in the activity of the serotoninergic and noradrenergic systems. An important component in the formation of chronic fatigue syndrome consists of endocrine and autoimmune factors, the latter having a greater effect on asthenia than on pathological fatigue. Further studies of the pathogenetic mechanisms of the formation of asthenia and pathological fatigue and clarification of their differential diagnostic signs should allow not only a better understanding of the nature of this syndrome, but also better selection of individual treatment.
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