The complete reducibility of some GF(2)A7-modules

It is proved that, if G is a finite group with a nontrivial normal 2-subgroup Q such that G/Q ∼= A 7 and an element of order 5 from G acts freely on Q, then the extension G over Q is splittable, Q is an elementary abelian group, and Q is the direct product of minimal normal subgroups of G each of which is isomorphic, as a G/Q-module, to one of the two 4-dimensional irreducible GF(2)A7-modules that are conjugate with respect to an outer automorphism of the group A7. © 2013 Pleiades Publishing, Ltd

The David procedure after the Ross operation: case series

Pulmonary autograft in the aortic position provides high survival rate and quality of life for patients, low incidence of valve-related complications, and excellent hemodynamic characteristics both in the early and long-term period. However, in some patients in the long-term period, pulmonary autograft may dilate, which in turn is one of the reasons for reoperations. In patients who require surgery for annuloaortic ectasia with aortic valve (AV) regurgitation or aortic root aneurysm (or both) with normal AV leaflets, David procedure is considered.Aim. To analyze results of David procedure after a prior Ross operation.Material and methods. From April 2009 to December 2020, 212 Ross operations were performed on patients 18 years of age and older. The median age of the operated patients was 34 (27-45) years. In the long-term period, 10 (4,7%) patients required a second AV operation and 7 (3,3%) of them required another intervention on the ascending aorta due to aortic dilatation. Four out of 10 patients underwent David procedure. The follow-up period for patients after David procedure ranged from 2 to 84 months.Results. The age of patients ranged from 23 to 45 years. Three patients had hypertension. The follow-up period from Ross's operation to David's one was 26 to 140 months. All patients had enlarged aortic annulus from 27 to 30 mm. The duration of myocardial ischemia ranged from 87 to 142 minutes, while the duration of artificial circulation — from 119 to 165 minutes. The graft diameter was 30 mm in two patients and 32 mm in the remaining ones. The length of stay in intensive care unit ranged from 16 to 23 hours. In the early postoperative period, no one had following postoperative complications: acute renal failure requiring hemodialysis, perioperative myocardial injury, stroke, sternal infection, respiratory failure requiring mechanical ventilation for ≥24 hours, resternotomy for bleeding and tamponade. In addition, there were no in hospital deaths. All patients had no aortic regurgitation at the time of discharge. All patients are alive and there were no reoperations. In one patient, in the long-term period, there was a mild aortic regurgitation, while in three patients — there is no regurgitation.Conclusion. The presented case series show that David procedure can be performed safely and effectively in a significant number of patients requiring a second autograft surgery due to neosinus dilatation. In the medium term, the David procedure has shown good outcomes in these patients with 100% survival and no aortic regurgitation and reoperation

Landscape science: a Russian geographical tradition

The Russian geographical tradition of landscape science (landshaftovedenie) is analyzed with particular reference to its initiator, Lev Semenovich Berg (1876-1950). The differences between prevailing Russian and Western concepts of landscape in geography are discussed, and their common origins in German geographical thought in the late nineteenth and early twentieth centuries are delineated. It is argued that the principal differences are accounted for by a number of factors, of which Russia's own distinctive tradition in environmental science deriving from the work of V. V. Dokuchaev (1846-1903), the activities of certain key individuals (such as Berg and C. O. Sauer), and the very different social and political circumstances in different parts of the world appear to be the most significant. At the same time it is noted that neither in Russia nor in the West have geographers succeeded in specifying an agreed and unproblematic understanding of landscape, or more broadly in promoting a common geographical conception of human-environment relationships. In light of such uncertainties, the latter part of the article argues for closer international links between the variant landscape traditions in geography as an important contribution to the quest for sustainability

Оценка эффективности лечения новообразований печени по данным КТ и МРТ: дорожная карта для врача лучевой диагностики

The number of available methods for hepatic tumor treatment is steadily increasing. Except traditional surgical resection and systemic chemotherapy there are a lot of effective and increasingly used local methods such as Radiofrequency ablation, cryodestruction, transarterial chemoembolization. Radiologist should be able to assess treatment response and evaluate prognosis. We present review of literature on various systems for hepatic tumor treatment response evaluation. WHO, RECIST 1.0, RECIST 1.1, mRECIST and Choi criteria are thoroughly explained in terms of benefits and drawbacks. Also, texture analysis and diffusion-weighted imaging are discussed.В последние годы выбор различных вариантов терапии образований печени становится все шире, отмечается появление новых вариантов химио- и лучевой терапии. В настоящее время растет количество методов локального воздействия на опухоли, таких как радиочастотная абляция, криодеструкция, трансартериальная эмболизация. Клиническая оценка эффекта терапии не дает необходимого результата, поэтому возрастает потребность в адекватной оценке результатов лечения, основанной на данных методов КТ и МРТ. В данном литературном обзоре приводятся основные критерии оценки эффективности лечения опухолей различными видами воздействия. Отдельно рассматриваются критерии ВОЗ, RECIST, RECIST 1.1, mRECIST, Choi. Помимо этого обсуждаются новые методики объективизации эффектов терапии, основанные на оценке диффузионно-взвешенных изображений и текстурном анализе