54 research outputs found

    Определение объема вычислительных экспериментов при решении задач оптимизационного синтеза динамических систем методом ПЛП-поиска

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    Даются рекомендации по выбору необходимого числа машинных экспериментов при решении конкретных задач исследования и оптимального проектирования методом ПЛП-поиска, позволяющего осуществлять глобальный квазиравномерный просмотр заданной области варьируемых параметров и применить формальные оценки из математической статистики.Recommendations about the choice of necessary number of machine experiments at the solution of specific objectives of a research and optimum design are made by method of the PLP-search allowing to carry out global quasi uniform viewing of the set area of the varied parameters and to apply formal estimates from mathematical statistics

    The Origin and Development of the Geometrical Ideas in Arabic Mathematics : The Synopsis of the Geometrical Works of al-Quhi

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    Arabic Mathematics has been characterized as algebra. Compared with this, Arabic geometry had not influence on the later mathematics, and has not been studied so much. However without this geometry, no solution of cubic equations has not completed in Arabic mathematics. We sketch here the synopsis of the geometrical works of Abu Sahl al-Quhl (second half of the tenth century), 'one of the most eminent mathematicians in Iraq', and investigate the origin and development of his geometrical ideas. Thirty three mathematical works are attributed to him, and almost of them are geometrical. His ideas were from Archimedes, Euclid and Apollonius. The opus magnum of the last one is indispensable for al-Quhl's works, and in the field of conic sections he contributed much. He completed the lacuna of the Greek mathematics, and developed it further. For showing this aspect four treatises are presented with partial translations. 'On Tangent Circles' investigated Apollonian circle problems further, and 'On the Trisection of Angle' solved the famous problem by Apollonian conic sections. 'On the Motion' was a unique treatise in Arabic mathematics, for it dealt with infinity which had been avoided in Greek mathematics. 'On the Perfect Compass (an instrument to draw conies by continuous moving)' gave an idea on the new classification of curves, which anticipates the seventeenth-century European mathematics. The problems and method which he used seems to be analytical and purely Greek, and he might be called as the last Greek-style mathematician. The atmosphere where he studied shows that Arabic science developed under a kind of patronage, and the manuscripts containing his treatises shows that Greek geometry was well established at his times. In conclusion, geometry flourished in Arabic world of the tenth century, and its results were over the Greek ones, and might be compared to the early modern mathematics in Europe

    Stage II/III rectal cancer with intermediate response to preoperative radiochemotherapy: Do we have indications for individual risk stratification?

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    <p>Abstract</p> <p>Background</p> <p>Response to preoperative radiochemotherapy (RCT) in patients with locally advanced rectal cancer is very heterogeneous. Pathologic complete response (pCR) is accompanied by a favorable outcome. However, most patients show incomplete response. The aim of this investigation was to find indications for risk stratification in the group of intermediate responders to RCT.</p> <p>Methods</p> <p>From a prospective database of 496 patients with rectal adenocarcinoma, 107 patients with stage II/III cancers and intermediate response to preoperative 5-FU based RCT (ypT2/3 and TRG 2/3), treated within the German Rectal Cancer Trials were studied. Surgical treatment comprised curative (R0) total mesorectal excision (TME) in all cases. In 95 patients available for statistical analyses, residual transmural infiltration of the mesorectal compartment, nodal involvement and histolologic tumor grading were investigated for their prognostic impact on disease-free (DFS) and overall survival (OS).</p> <p>Results</p> <p>Residual tumor transgression into the mesorectal compartment (ypT3) did not influence DFS and OS rates (p = 0.619, p = 0.602, respectively). Nodal involvement after preoperative RCT (ypN1/2) turned out to be a valid prognostic factor with decreased DFS and OS (p = 0.0463, p = 0.0236, respectively). Persistent tumor infiltration of the mesorectum (ypT3) and histologic tumor grading of residual tumor cell clusters were strongly correlated with lymph node metastases after neoadjuvant treatment (p < 0.001).</p> <p>Conclusions</p> <p>Advanced transmural tumor invasion after RCT does not affect prognosis when curative (R0) resection is achievable. Residual nodal status is the most important predictor of individual outcome in intermediate responders to preoperative RCT. Furthermore, ypT stage and tumor grading turn out to be additional auxiliary factors. Future clinical trials for risk-adapted adjuvant therapy should be based on a synopsis of clinicopathologic parameters.</p

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    Molecular Cytogenetics: Genomic Imbalances in Colorectal Cancer and their Clinical Impact

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    Chromosomal aberrations play a dominant role in colorectal carcinogenesis. The application of fluorescence in situ hybridization (FISH) based techniques such as comparative genomic hybridization (CGH) and spectral karyotyping (SKY) revealed that colorectal carcinomas are characterized by a specific pattern of chromosomal imbalances which sequentially accumulate during cancer progression. This review aims to summarize molecular cytogenetic studies, provides a background on the functional relevance of chromosomal aberrations for colorectal cancer progression and discusses their potential clinical impact
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