Combining experimental and numerical analysis to estimate stress fields along the surface crack front

Combining experimental and computational method for determination of the singular and the non-singular stress terms along the front of the 3D surface crack is proposed. Evaluation of the terms is based on comprehensive comparison between deformation responses (for measurement points on the surface) obtained experimentally and from numerical solutions of the corresponding boundary problem of solid mechanics. The proposed approach allows carrying out an adequate and a comprehensive assessment of stress fields in the vicinity of the surface crack front

Суздаль. Зарядье. Активация: Концепция развития и благоустройства территории Зарядья в городе Суздаль Владимирской области

The authors feature the historical and cultural background of the reconstruction project for shopping arcade in Suzdal. The article analyzes the disadvantages of the present-day status of Suzdal as one of the centers of the Goldan Ring. It describes the principles, the plan and the approach to the reconstruction, as well as the possibility to return the money from tourism to the city budget.Авторы излагают историко-культурные основания проекта реконструкции торговых рядов Суздаля. Анализируются недостатки современного статуса Суздаля как одного из центров Золотого кольца. Излагаются принципы реконструкции, ее план и способы реализации, а также возможность возвращения туристических денег в бюджет города

Ecology of a marginal carrion crow population. I: Distribution and abundance

Répartition et utilisation de l'espace en Camargu

The effect of residual stress on the nonsingular T-stresses

The effect of residual stresses on surface fatigue crack propagation and fracture mechanics parameters of intersecting orthogonal cracks is discussed. Mutual influence of intersecting cracks and biaxiality affects the nonsingular parameters Txx and Tzz. At the same time, the effect on the stress intensity factor is negligible. Two-parameter fracture mechanics is employed for an analysis of fatigue crack propagation taking into account residual stresses. The final configuration of the crack front is close to the semi-elliptical configuration

Spontaneous symmetry breaking in genome evolution

The quest for evolutionary mechanisms providing separation between the coding (exons) and noncoding (introns) parts of genomic DNA remains an important focus of genetics. This work combines an analysis of the most recent achievements of genomics and fundamental concepts of random processes to provide a novel point of view on genome evolution. Exon sizes in sequenced genomes show a lognormal distribution typical of a random Kolmogoroff fractioning process. This implies that the process of intron incretion may be independent of exon size, and therefore could be dependent on intron–exon boundaries. All genomes examined have two distinctive classes of exons, each with different evolutionary histories. In the framework proposed in this article, these two classes of exons can be derived from a hypothetical ancestral genome by (spontaneous) symmetry breaking. We note that one of these exon classes comprises mostly alternatively spliced exons

Взаимная диффузия в системах на основе тугоплавких металлов с ОЦК-решеткой: титан–тантал и титан – многокомпонентный (высокоэнтропийный) сплав

In this work, the interdiffusion features in multicomponent (high-entropy) alloys of refractory metals were studied. The following pairs were chosen as the diffusion study objects: titanium–equiatomic alloy (Hf–Nb–Ta–Ti–Zr–Mo) and titanium–tantalum for the sake of comparison. The article covers the issues of sample preparation, microstructure study, sample preparation methodology for diffusion research, and experimental results. Diffusion annealing was carried out for 12 h in a vacuum at a residual argon pressure of 6.65·10–3 Pa and a temperature of 1200 °С. Particular attention was paid to the method of combining diffusion pairs (titanium with tantalum, titanium with alloy) by thermal cycling near the polymorphic transformation temperature in titanium (882 °C) within ± 50 °C. The behaviour of the most characteristic elements (Ta, Zr, Ti) in the weld area after the titanium and alloy diffusion pair joining was demonstrated. This is the first time that data on the dependence of the intensity of the corresponding spectral line for titanium and elements of a multicomponent alloy on the penetration depth were obtained. A change in the signal intensity for system elements was observed at a depth of 150–200 μm, whereas a sharp drop in the signal intensity was seen to occur at depths of about 50 μm. The effective value of the coefficient of diffusion of elements into titanium averaged over all elements of the alloying system (except for titanium) at a temperature of 1200 °C was calculated. The obtained value was compared to reference data: the self-diffusion coefficient in β-titanium and diffusion coefficients in titanium pairs with alloy doping elements.Изучены особенности взаимной диффузии в многокомпонентных (высокоэнтропийных) сплавах на основе тугоплавких металлов. В качестве объектов диффузионного исследования были выбраны следующие пары: титан – эквиатомный сплав (Hf–Nb–Ta–Ti–Zr–Mo) и, для сравнения, титан–тантал. Рассмотрены вопросы приготовления образцов, исследования микроструктуры, методика подготовки образцов для изучения диффузии и экспериментальные результаты. Диффузионный отжиг был проведен в течение 12 ч в вакууме с остаточным давлением аргона 6,65·10–3 Па при температуре 1200 °С. Особое внимание уделено методике соединения диффузионных пар (титана с танталом, титана со сплавом) путем термоциклирования вблизи температуры полиморфного превращения в титане (882 °С) в пределах ±50 °С. Показано поведение наиболее характерных элементов (Ta, Zr, Ti) в области сварного шва после соединения диффузионной пары титана и сплава. Впервые получены данные о зависимости интенсивности соответствующей линии спектра для титана и элементов многокомпонентного сплава от глубины проникновения. Изменение интенсивности сигнала для элементов систем наблюдается на глубине 150–200 мкм, а резкое падение интенсивности сигнала происходит на глубинах порядка 50 мкм. Рассчитано усредненное по всем элементам системы легирования сплава (за исключением титана) эффективное значение коэффициента диффузии элементов в титан при температуре 1200 °С. Проведено сравнение полученного значения со справочными данными: коэффициентом самодиффузии в β-титане, коэффициентами диффузии в парах титана с легирующими элементами сплава

Chern-Simons like term generation in an extended model of QED under external conditions

The possibility of a Chern-Simons like term generation in an extended model of QED, in which a Lorentz and CPT non-covariant interaction term for fermions is present, has been investigated at finite temperature and in the presence of a background color magnetic field. To this end, the photon polarization operator in an external constant axial-vector field has been considered. One-loop contributions to its antisymmetric component due to fermions in the linear order of the axial-vector field have been obtained. Moreover, the first nontrivial correction to the induced CS term due to the presence of a weak constant homogeneous color magnetic field has been derived.Comment: RevTex, 10 pages with 3 figure

Laparoscopic open Kasai portoenterostomy: our experience

The question of feasibility of laparoscopic Kasai procedure for biliary atresia in infants has been a subject of discussion for a long time, and still remains unsolved. 110 children with different bile duct malformations were operated on in our clinic since 2000. The first laparoscopic Kasai portoenterostomy was performed in January, 2008 to a 2 month old child. Since then, laparoscopic Kasai portoenterostomies were performed in 42 children with biliary atresia. The age of the children varied from 50 days to 3.5 months. The mean weight of the patients was 4693±767g. 24 patients between the years 2000- 2008 were operated on by conventional (“open”) procedures. All procedures were performed with 4 to 5 trocars using 3 and 5-mm ports. Excision of the fibrous biliary remnant was performed laparoscopically in all cases. The Roux loop was fashioned outside of the abdominal cavity through the umbilical incision in 23 children, and in 18 infants the Ruox loop was performed laparoscopically. Laparoscopic biliary reconstruction was performed successfully in all patients. Results: 79% of children who underwent laparoscopic Kasai had a normal postoperative bilirubin level, whereas the other 9 children did not drain bile and required liver transplantation. In the “open” surgery group, 74% of patients had good results. The duration of laparoscopic Kasai procedure was significantly longer than open surgery (p < 0.05). There were no conversions. We observed significantly fewer complications (40%) after laparoscopic hepaticojejunostomy than after traditional hepaticojejunoduodenostomy (84.6%, p < 0.05). The average length of stay in the ICU, and the duration of analgesia after laparoscopy was significantly lower than after open surgery (p < 0.05). Cholangitis was found in 21.4% in the laparoscopic group and 25% in the open surgery group. Intraperitoneal adhesions in patients who underwent liver transplantation were less pronounced after laporoscopy, compared with open Kasai procedure. Conclusion: Our experience leads us to conclude that laparoscopic Kasai operations can be used as the procedure of choice in the treatment of children with biliary atresia