Virtual Polytopes

Originating in diverse branches of mathematics, from polytope algebra and toric varieties to the theory of stressed graphs, virtual polytopes represent a natural algebraic generalization of convex polytopes. Introduced as elements of the Grothendieck group associated to the semigroup of convex polytopes, they admit a variety of geometrizations. The present survey connects the theory of virtual polytopes with other geometrical subjects, describes a series of geometrizations together with relations between them, and gives a selection of applications

Clinical features of spinal cord hemangioblastoma complicated by hematomyelia and subarachnoid hemorrhage: Description of a clinical case and review of literature

The paper describes subarachnoid hemorrhage (SAH) and hematomyelia resulting from bleeding from spinal hemangioblastoma. SAH is encountered in spinal pathology extremely rarely and results from bleeding from malformations in most cases. The described case demonstrates that the tumors may also cause spinal SAH even there is no clinical evidence of gradually progressive spinal cord compression in the history. Patients with hemangioblastoma are at the highest risk for clinically relevant massive bleeding in intramedullary tumors. In this case, of special attention is its clinical picture: SAH began with neck and arm pain, rather than headache, which indicates the primarily spinal level of bleeding. Head and arm pains were joined by SAH -typical headache, nausea, and vomiting in only a few minutes, which was associated with retrograde blood flow into the basal cisterns of the brain and the fourth ventricle. Primary MRI of the cervical spine was a more rational diagnostic scheme in this case

Design and characterization of Al-Cr-Nb-Ti-V-Zr high-entropy alloys for high-temperature applications

High-entropy alloys (HEAs) are a new class of metallic alloys without a principal component. These materials are attractive because of their unique structures and properties, including mechanical ones. Some of HEAs based on refractory metals are considered as advanced high-temperature materials. However, the development of new applicable compositions is complicated by poor understanding of relationships between the chemical and phase composition of HEAs and their effect on mechanical performanc

Microstructure evolution of a novel low-density Ti-Cr-Nb-V refractory high entropy alloy during cold rolling and subsequent annealing

In this work, we report structure and mechanical properties of a novel non-equiatomic Ti1.89CrNbV0.56 alloy produced by vacuum arc melting. The density of the alloy was 6.17 g/cm3. In the as-cast condition, the alloy had a single-phase bcc structure enabling room temperature deformation in compression to ε>50% or cold-rolling to a thickness strain of 80%. Rolling resulted in the formation of a dislocation substructure and development of kink and shear band

Histological classification of mesial temporal sclerosis

Mesial temporal sclerosis (MTS) is the most common histopathology occurring in patients with drug-resistant temporal lobe epilepsy. Over the past decades, there have been various attempts to classify the variants of hippocampal neuronal cell loss in relation to postoperative outcome. However, no consensus on the common international definition and classification of MTS has been reached. The article describes the modern histological classification based on a semiquantitative hippocampal cell loss model. The publications dealing with the histological classification of mesial temporal sclerosis are reviewed

Effect of Mechanical and Thermal Treatment on the Structure and Properties of a Non-Equatomic High Entropy Alloy Ti1,89NbCrV0,56

A Ti1,89NbCrV0,56 high entropy non-equiatomic alloy with a density of 6.17 g cm–3 was developed. The alloy had a single-phase bcc structure in the cast and rolling state. Post-deformation annealing at 800 °C led to a precipitation of the Laves phase C15 (fcc) particles. After annealing at 1200 °C, the alloy returned to the single-phase condition. The as-cast and annealed alloy were brittle.Был разработан высокоэнтропийный неэквиатомный сплав Ti1,89NbCrV0,56 с плотностью 6,17 г/см 3. В литом и прокатанном состоянии сплав имел однофазную ОЦК структуру. Отжиг после прокатки при 800 °C привел к выделению частиц фазы Лавеса С15 (ГЦК). После отжига при 1200 °C сплав имел однофазную ОЦК структуру. В литом и отожженном состоянии наблюдалось хрупкое разрушение

Конечностно-поясная мышечная дистрофия с аутосомно- доминантным типом наследования: пельвиофеморальная форма Лейдена–Мебиуса

The paper considers current approaches to the clinical laboratory diagnosis of limb-girdle muscular dystrophy with emphasis on its autosomal dominant forms. The authors describe their clinical observation of a case of late diagnosis of the pelvifemoral form of autosomal dominant limbgirdle muscular dystrophy in a 37-year-old patient.В статье рассматриваются современные подходы к клинико-лабораторной диагностике конечностно-поясной мышечной дистрофии с акцентом на аутосомно-доминантные формы заболевания. Авторами представлено собственное клиническое наблюдение случая с поздней диагностикой пельвиофеморальной формы конечностно-поясной мышечной дистрофии с аутосомно-доминантным типом наследования у пациентки 37 лет.