An iterative method for mixed finite element schemes

An iterative method with a saddle preconditioner is proposed for solving a system of nonlinear equations that arises in the approximation of a quasilinear second-order elliptic equation with a mixed scheme of finite elements of Raviart-Thomas type. The ways of choosing the iteration parameter are pointed out that ensure the convergence of the method. The results of numerical experiments are presented. © 2012 Pleiades Publishing, Ltd

SEARCH FOR AEROSOL MICROPARTICLES IN DATED LAYERS OF BOTTOM SEDIMENTS USING SYNCHROTRON RADIATION

The SR-micro-XRF method was used to search for microparticles of extraterrestrial matter in the bottom sediments of Lake Zapovednoye, located 60 km from the epicentre of the explosion of the Tunguska cosmic body (TCB) in 1908. The material of bottom sediments dating back to 1908–1910 was studied. The samples for the study were prepared in the form of a powder applied to a conductive adhesive tape, which made it possible to combine the data of optical observations, electron microscopy, and micro-XRF scanning. The experiments were carried out at the Large-Scale Research Facilities "Kurchatov Centre for Synchrotron Research" using a confocal X-ray microscope developed at the Budker Institute of Nuclear Physics SB RAS. The data obtained indicate the presence of microparticles with an increased Ni/Fe ratio, possibly of extraterrestrial origin

Risk factors for African swine fever incursion in Romanian domestic farms during 2019

African swine fever (ASF) entered Georgia in 2007 and the EU in 2014. In the EU, the virus primarily spread in wild boar (Sus scrofa) in the period from 2014–2018. However, from the summer 2018, numerous domestic pig farms in Romania were affected by ASF. In contrast to the existing knowledge on ASF transmission routes, the understanding of risk factors and the importance of different transmission routes is still limited. In the period from May to September 2019, 655 Romanian pig farms were included in a matched case-control study investigating possible risk factors for ASF incursion in commercial and backyard pig farms. The results showed that close proximity to outbreaks in domestic farms was a risk factor in commercial as well as backyard farms. Furthermore, in backyard farms, herd size, wild boar abundance around the farm, number of domestic outbreaks within 2 km around farms, short distance to wild boar cases and visits of professionals working on farms were statistically significant risk factors. Additionally, growing crops around the farm, which could potentially attract wild boar, and feeding forage from ASF affected areas to the pigs were risk factors for ASF incursion in backyard farms.We acknowledge financial support from EFSA, ANSVSA and from the Danish Veterinary and Food Administration (FVST) as part of the agreement of commissioned work between the Danish Ministry of Food, Agriculture and Fisheries and the University of Copenhagen.Peer reviewe

ПОИСК АЭРОЗОЛЬНЫХ МИКРОЧАСТИЦ В ДАТИРОВАННЫХ СЛОЯХ ДОННЫХ ОТЛОЖЕНИЙ С ИСПОЛЬЗОВАНИЕМ СИНХРОТРОННОГО ИЗЛУЧЕНИЯ

The SR-micro-XRF method was used to search for microparticles of extraterrestrial matter in the bottom sediments of Lake Zapovednoye, located 60 km from the epicentre of the explosion of the Tunguska cosmic body (TCB) in 1908. The material of bottom sediments dating back to 1908–1910 was studied. The samples for the study were prepared in the form of a powder applied to a conductive adhesive tape, which made it possible to combine the data of optical observations, electron microscopy, and micro-XRF scanning. The experiments were carried out at the Large-Scale Research Facilities "Kurchatov Centre for Synchrotron Research" using a confocal X-ray microscope developed at the Budker Institute of Nuclear Physics SB RAS. The data obtained indicate the presence of microparticles with an increased Ni/Fe ratio, possibly of extraterrestrial origin.Методом микро-РФА-СИ проведен поиск микрочастиц внеземного вещества в донных осадках озера Заповедного, расположенного в 60 км от эпицентра взрыва Тунгусского космического тела (ТКТ) в 1908 г. Исследован материал донных отложений, датируемый 1908–1910 гг. Образцы для исследования были приготовлены в виде порошка, нанесенного на токопроводящую клейкую ленту, что позволило совместить данные оптических наблюдений, электронной микроскопии и микро-РФА сканирования. Эксперименты проводились с использованием УНУ «Курчатовский центр синхротронного излучения КИСИ» с использованием конфокального рентгеновского микроскопа, разработанного в ИЯФ СО РАН. Полученные данные свидетельствуют о наличии микрочастиц с повышенным отношением Ni/Fe, возможно имеющих внеземное происхождение. Используемые методики микро-РФА-СИ позволяют проводить поиск и изучение частиц с микрометровым пространственным разрешением в матрицах различного состава на основе данных о распределении породообразующих и следовых элементов

An iterative method for mixed finite element schemes

An iterative method with a saddle preconditioner is proposed for solving a system of nonlinear equations that arises in the approximation of a quasilinear second-order elliptic equation with a mixed scheme of finite elements of Raviart-Thomas type. The ways of choosing the iteration parameter are pointed out that ensure the convergence of the method. The results of numerical experiments are presented. © 2012 Pleiades Publishing, Ltd

An iterative method for mixed finite element schemes

An iterative method with a saddle preconditioner is proposed for solving a system of nonlinear equations that arises in the approximation of a quasilinear second-order elliptic equation with a mixed scheme of finite elements of Raviart-Thomas type. The ways of choosing the iteration parameter are pointed out that ensure the convergence of the method. The results of numerical experiments are presented. © 2012 Pleiades Publishing, Ltd

An iterative method for mixed finite element schemes

An iterative method with a saddle preconditioner is proposed for solving a system of nonlinear equations that arises in the approximation of a quasilinear second-order elliptic equation with a mixed scheme of finite elements of Raviart-Thomas type. The ways of choosing the iteration parameter are pointed out that ensure the convergence of the method. The results of numerical experiments are presented. © 2012 Pleiades Publishing, Ltd