Giant popliteal artery aneurysm

Introduction: Popliteal artery aneurysm is a pathology that appears regularly in daily practice of a vascular surgeon since the popliteal artery is the most common location of aneurysms (about 70%). A rare form of aneurysm of the popliteal artery is a giant aneurysm, the diameter of which is more than 7–8 cm. Giant aneurysms are of a great clinical importance due to the high risk of rupture and complications, and the fact that this pathology has its own peculiarities of surgical treatment.Material and methods: We conducted an electronic bibliographic search Pubmed, Cochrane Library, Wiley to find reports about treatment of giant popliteal aneurysms. According to its results the main features of the clinical picture, diagnosis and treatment of giant popliteal aneurysms have been identified.Results and discussion: Surgical treatment of giant popliteal artery aneurysms differs from the treatment of regular popliteal artery aneurysms and is associated with the choice of adequate access and the need for partial or full resection of the aneurysm. Endovascular treatment methods are used much less frequently, however, with the improvement of techniques and the emergence of new technologies, an increase in number of giant aneurysms successful treatment cases is expected

Четыре клеточно-автоматных алгоритма пермутаций матриц

Numerical calculation uses to describe the operation of matrix permutation algorithms based on cyclic shifts of rows and columns. This choice of discrete transformation algorithms justified by the convenience of the cellular automaton (CA) formulation, which is used. Obtained Empirical formulas for the permutation period and for the last algorithm, which period formula is recurrent. For a base scheme period has the asymptotics:  for a matrix  with pairwise different elements. Despite the complexity of the scheme, the other two modifications only give a polynomial growth of period, no higher than 3. Fourth scheme has a non-trivial period dependence, but no higher than the exponential. In some cases algorithms make special permutations: rotate, reflect, and rearrange blocks for the matrix . These formulas are closely related to individual cells paths. And paths connected with the influence of the boundaries that gives branching the matrix order by subtraction class modulo 3,4 or 12. Visualizations of these paths make in the extended CA-field. Two "mixing metrics" analyze as a parameter of CA dynamics on matrix permutations (compared to the initial). For all schemes and most branches, the behavior of these metrics shows in graphs and histograms (conditional density distribution) showing how often the permutation period occurs with the specified interval of metrics. The practical aim of this work is in the field of pseudorandom number generation and cryptography.С помощью численного расчета описывается работа алгоритмов пермутаций матриц, основанных на циклических сдвигах строк и столбцов. Такой выбор алгоритмов дискретного преобразования обоснован удобством клеточно-автоматных формулировок, которые и приводятся. Получены эмпирические формулы для периода пермутаций; для последнего алгоритма формула периода носит рекуррентный характер. Для базовой и наиболее простой схемы период N(n) имеет асимптотику exp(2n)/n для матрицы nxn с попарно различными элементами. Несмотря на усложнение схемы алгоритма, две другие модификации дают лишь полиномиальный рост степени не выше 3. Четвертая схема имеет нетривиальную зависимость периода, но не выше экспоненциальной. В ряде случаев алгоритмы порождают особые пермутации: поворот, отражение и перестановку блоков для матрицы 2kx2k. Эти формулы тесно связаны с индивидуальными траекториями элементов, а они – с влиянием границ, что дает ветвление порядка матрицы по классу вычета по модулю 3,4 или 12. Визуализации этих траекторий приводятся в расширенном поле КА. В качестве параметра динамики КА анализируются две «метрики перемешанности» на пермутациях матрицы (по сравнению с начальной). Для всех схем и большинства ветвей поведение этих метрик представлено на графиках и гистограммах (условно: плотности распределения), показывающих, как часто встречаются по периоду пермутации с заданным интервалом значений метрик. Практическое значение работы состоит в оценке применения КА в областях генерации псевдослучайных чисел и криптографии

Four Cellular Automata Algorithms for Matrix Permutation

Numerical calculation uses to describe the operation of matrix permutation algorithms based on cyclic shifts of rows and columns. This choice of discrete transformation algorithms justified by the convenience of the cellular automaton (CA) formulation, which is used. Obtained Empirical formulas for the permutation period and for the last algorithm, which period formula is recurrent. For a base scheme period has the asymptotics:  for a matrix  with pairwise different elements. Despite the complexity of the scheme, the other two modifications only give a polynomial growth of period, no higher than 3. Fourth scheme has a non-trivial period dependence, but no higher than the exponential. In some cases algorithms make special permutations: rotate, reflect, and rearrange blocks for the matrix . These formulas are closely related to individual cells paths. And paths connected with the influence of the boundaries that gives branching the matrix order by subtraction class modulo 3,4 or 12. Visualizations of these paths make in the extended CA-field. Two "mixing metrics" analyze as a parameter of CA dynamics on matrix permutations (compared to the initial). For all schemes and most branches, the behavior of these metrics shows in graphs and histograms (conditional density distribution) showing how often the permutation period occurs with the specified interval of metrics. The practical aim of this work is in the field of pseudorandom number generation and cryptography

Helicity-Sensitive Plasmonic Terahertz Interferometer

Plasmonic interferometry is a rapidly growing area of research with a huge potential for applications in the terahertz frequency range. In this Letter, we explore a plasmonic interferometer based on graphene field effect transistor connected to specially designed antennas. As a key result, we observe helicity- and phase-sensitive conversion of circularly polarized radiation into dc photovoltage caused by the plasmon-interference mechanism: two plasma waves, excited at the source and drain part of the transistor, interfere inside the channel. The helicity-sensitive phase shift between these waves is achieved by using an asymmetric antenna configuration. The dc signal changes sign with inversion of the helicity. A suggested plasmonic interferometer is capable of measuring the phase difference between two arbitrary phase-shifted optical signals. The observed effect opens a wide avenue for phase-sensitive probing of plasma wave excitations in two-dimensional materials