Locating the Body in Medieval Reval

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Multiple planar coincidences with N-fold symmetry

Planar coincidence site lattices and modules with N-fold symmetry are well understood in a formulation based on cyclotomic fields, in particular for the class number one case, where they appear as certain principal ideals in the corresponding ring of integers. We extend this approach to multiple coincidences, which apply to triple or multiple junctions. In particular, we give explicit results for spectral, combinatorial and asymptotic properties in terms of Dirichlet series generating functions.Comment: 13 pages, two figures. For previous related work see math.MG/0511147 and math.CO/0301021. Minor changes and references update

Предпосылки применения просвечивающей электронной микроскопии как геохимической методики выявления миграционных минеральных форм над углеводородными залежами

Актуальность исследования обусловлена необходимостью разработки методики нахождения и определения миграционных форм металлических соединений над контурами углеводородных залежей на поверхности Земли, так как существующая в настоящее время информация о возможности переноса металлов с уровня залежи зачастую противоречива, что ставит под сомнение саму возможность геохимических поисков углеводородных залежей на основе информации о содержании металлов в приповерхностных горизонтах. Обсуждаемая методика сбора и анализа позволяет изучать наноразмерные соединения металлов, мигрирующих в составе газового потока до поверхности Земли. Появляется возможность установления происхождения найденного наноразмерного металлического соединения с допустимостью доказать глубинную природу происхождения вещества, найденного на дневной поверхности. Цель работы: обзор и анализ существующих знаний о геохимических методах поисков месторождений нефти и газа; моделирование новой геохимической методики, связанной с исследованием образцов на просвечивающем электронном микроскопе, с возможностью установления частиц в наноразмерном состоянии. Методы исследования: геохимические методы поиска и разведки месторождений нефти и газа, просвечивающая электронная микроскопия. Результаты. Проведен обзор и анализ литературы на тему геохимических методов поисков залежей нефти и газа, проанализированы закономерности особенностей геохимических полей над месторождениями нефти и газа Западно-Сибирской нефтегазоносной провинции. Предложена новая геохимическая методика поисков и разведки, которая способна выявлять минеральные формы нахождения химических элементов в наноразмерном состоянии на просвечивающем электронном микроскопе, в частности находить и идентифицировать миграционные металлические соединения.The relevance of the discussed issue is caused by the necessity to develop the technique for finding and identifying metal compounds migration forms over the boundaries of hydrocarbon deposits on the Earth surface. The existing information on possibility of metal transfer from the level of deposits is often contradictory and it can cast doubt on the possibility of geochemical prospecting of hydrocarbon deposits on the basis of information on metal content in the subsurface horizons. The technique of collection and analysis allows us to study nanoscale metal compounds migrating as a part of gas flow to the Earth surface. It becomes possible to determine the origin of nanoscale metal compounds with the ability to prove the genesis of the deep nature of the substance found on the surface. The main aim of the research is to review and to analyze the existing knowledge on geochemical methods of prospecting for oil and gas; to model a new geochemical method associated with the study of samples on a transmission electron microscope for identifying nanoscale particles. The methods used in the study: geochemistry methods of prospecting and exploration of oil and gas fields, transmission electron microscopy. The results of the research. The authors have reviewed and analyzed the literature on geochemical methods to search for oil and gas deposits and analyzed the patterns of geochemical features and magnetic fields on deposits of the West Siberian oil and gas province. The paper introduces a new prospecting and exploration geochemical and magnetic technique which can help identify nanoscale mineral forms of chemical elements with a transmission electron microscope, in particular find and identify migration metal compounds

Domain Rearrangement and Denaturation in Ebola Virus Protein VP40

The VP40 protein plays a critical role in coordinating the virion assembly, budding, and replication of the Ebola virus. Efforts have been made in recent years to understand various aspects of VP40 structure, dynamics, and function such as assembly of the protein and its roles in virus replication and penetration of the protein into the plasma membrane. A major conformational transformation is necessary for VP40 to form some of its oligomeric structures and to perform various functions. This conformational change from a compact structure with the N-terminal domain (NTD) and C-terminal domain (CTD) closely associated involves a dissociation or springing-out of the CTD from the NTD. We perform investigations using computational molecular dynamics simulations as well as knowledge-based Monte Carlo simulations. We find that a sharp springing of the CTD from the NTD in a free VP40 protein cannot occur solely by random thermal fluctuations without intermediate oligomerized segments, and therefore is likely triggered by additional molecular events

Evolution of grain boundary network topology in 316L austenitic stainless steel during powder hot isostatic pressing

The grain boundary network evolution of 316L austenitic steel powder during its densification by hot isostatic pressing (HIPing) was investigated. While the as-received powder contained a network of random high angle grain boundaries, the fully consolidated specimen had a large fraction of annealing twins, indicating that during densification, the microstructure evolves via recrystallization. By interrupting the HIPing process at different points in time, microstructural changes were tracked quantitatively at every stage using twin boundary fractions, distribution of different types of triple junctions, and the parameters associated with twin related domains (TRDs). Results revealed that, with increase in temperature, (i) the fraction of annealing twins increased steadily, but they mostly were not part of the grain boundary network in the fully consolidated specimen and (ii) the average number of grains within a TRD, the length of longest chain, and twinning polysynthetism increased during HIPing and (iii) the powder characteristics and the HIPing parameters have a strong influence on the development of grain boundary network. Based on the results obtained, possible alterations to the HIPing process are discussed, which could potentially allow twin induced grain boundary engineering

Magnetic metamaterials in the blue range using aluminum nanostructures

We report an experimental and theoretical study of the optical properties of two-dimensional arrays of aluminum nanoparticle in-tandem pairs. Plasmon resonances and effective optical constants of these structures are investigated and strong magnetic response as well as negative permeability are observed down to 400 nm wavelength. Theoretical calculations based on the finite-difference time-domain method are performed for various particle dimensions and lattice parameters, and are found to be in good agreement with the experimental results. The results show that metamaterials operating across the whole visible wavelength range are feasible.Comment: 3 pages, 4 figure

Multiscale multiphysics model for hydrogen embrittlement in polycrystalline nickel

Référence bibliographique : Rol, 102487Appartient à l’ensemble documentaire : Pho20RolAppartient à l’ensemble documentaire : PACA1Image de press

An endogenous peptide marker differentiates SOD1 stability and facilitates pharmacodynamic monitoring in SOD1 amyotrophic lateral sclerosis

The discovery of novel biomarkers has emerged as a critical need for therapeutic development in amyotrophic lateral sclerosis (ALS). For some subsets of ALS, such as the genetic superoxide dismutase 1 (SOD1) form, exciting new treatment strategies, such as antisense oligonucleotide-mediated (ASO-mediated) SOD1 silencing, are being tested in clinical trials, so the identification of pharmacodynamic biomarkers for therapeutic monitoring is essential. We identify increased levels of a 7-amino acid endogenous peptide of SOD1 in cerebrospinal fluid (CSF) of human SOD1 mutation carriers but not in other neurological cases or nondiseased controls. Levels of peptide elevation vary based on the specific SOD1 mutation (ranging from 1.1-fold greater than control in D90A to nearly 30-fold greater in V148G) and correlate with previously published measurements of SOD1 stability. Using a mass spectrometry-based method (liquid chromatography-mass spectrometry), we quantified peptides in both extracellular samples (CSF) and intracellular samples (spinal cord from rat) to demonstrate that the peptide distinguishes mutation-specific differences in intracellular SOD1 degradation. Furthermore, 80% and 63% reductions of the peptide were measured in SOD1G93A and SOD1H46R rat CSF samples, respectively, following treatment with ASO, with an improved correlation to mRNA levels in spinal cords compared with the ELISA measuring intact SOD1 protein. These data demonstrate the potential of this peptide as a pharmacodynamic biomarker

Residual stress, strain and faults in nanocrystalline palladium and copper

Nanocrystalline Pd and Cu, prepared by inert gas condensation and warm compaction, were studied using x-ray diffraction techniques. A sample of Cu with sub-micrometer grain size produced by severe plastic deformation was also examined. The Warren-Averbach technique was used to separate the line broadening due to grain size, root-mean-squared strain, and faults. Peak shifts and asymmetry were used to determine the long range surface stresses, stacking fault probability, and twin probability. The Young`s modulus of a Pd sample was determined by an ultrasonic technique, and compared with the coarse-grained, fully-dense value