Electromechanical Imaging of Biological Systems with Sub-10 nm Resolution

Electromechanical imaging of tooth dentin and enamel has been performed with sub-10 nm resolution using piezoresponse force microscopy. Characteristic piezoelectric domain size and local protein fiber ordering in dentin have been determined. The shape of a single collagen fibril in enamel is visualized in real space and local hysteresis loops are measured. Because of the ubiquitous presence of piezoelectricity in biological systems, this approach is expected to find broad application in high-resolution studies of a wide range of biomaterials.Comment: 12 pages, 4 figures, submitted for publication in Appl. Phys. Let

Discontinuous Bifurcations under 2-DOF Vibroimpact System Moving

Dynamic behaviour of strongly nonlinear non-smooth discontinuous vibroimpact system isstudied. Under variation of system parameters we find the disconti nuousbi furcati onsthat are the dangerousones. It is phenomenon unique to non-smooth systems with discontinuous right-hand side. We investigate the 2-DOF vibroimpact system by numerical parameter continuation method in conjunction with shooting and Newton-Raphson methods, Wife simulate the impact by nonlinear contact interactive force according to Hertz's contact law. We find the discontinuous bifurcations by Floquet multipliers values. At such points set-valued Floquet multipliers cross the unit circle by jump that istheir moduli becoming more than unit by jump. Wealso learn the bifurcation picture change when the impact between system bodi es became the soft one due the change of system parameters, This paper is the continuation of the previous works

Infrared studies of a La_(0.67)Ca_(0.33)MnO_3 single crystal: Optical magnetoconductivity in a half-metallic ferromagnet

The infrared reflectivity of a La_(0.67)Ca_(0.33)MnO_3 single crystal is studied over a broad range of temperatures (78–340 K), magnetic fields (0–16 T), and wave numbers (20–9000cm^(-1)). The optical conductivity gradually changes from a Drude-like behavior to a broad peak feature near 5000cm-1 in the ferromagnetic state below the Curie temperature T_C=307K. Various features of the optical conductivity bear striking resemblance to recent theoretical predictions based on the interplay between the double exchange interaction and the Jahn-Teller electron-phonon coupling. A large optical magnetoconductivity is observed near T_C

Infrared Studies of a La_{0.67}Ca_{0.33}MnO_3 Single Crystal: Optical Magnetoconductivity in a Half-Metallic Ferromagnet

The infrared reflectivity of a $\rm La_{0.67}Ca_{0.33}MnO_3$ single crystal is studied over a broad range of temperatures (78-340 K), magnetic fields (0-16 T), and wavenumbers (20-9000 cm$^{-1}$). The optical conductivity gradually changes from a Drude-like behavior to a broad peak feature near 5000 cm$^{-1}$ in the ferromagnetic state below the Curie temperature $T_C=307 K$. Various features of the optical conductivity bear striking resemblance to recent theoretical predictions based on the interplay between the double exchange interaction and the Jahn-Teller electron-phonon coupling. A large optical magnetoconductivity is observed near $T_C$.Comment: 4 pages, 4 figures, Latex, PostScript; The 7th Joint MMM-Intermag Conference,San Francisco, January 6-9, 1998; The Int. Conf. on Strongly Correlated Electron Systems, Paris, July 15-18,199

Modelling of continual fracture of spatial bodies under long-term static and cyclic loading

Представлено методику моделювання процесів континуального руйнування кругових та призматичних тіл складної форми в умовах тривалого статичного і багатоциклового навантаження: скінчено-елементна база для визначення напружено-деформованого стану просторових тіл на основі напіваналітичного методу скінчених елементів (НМСЕ), алгоритми визначення феноменологічного параметра пошкодженості та моделювання еволюційних процесів розповсюдження зон континуального руйнування. Наведено результати розв’язання практичних задач із визначення розрахункового і додаткового ресурсу відповідальних просторових об’єктів.Techniques of continual fracture process modelling of complex shape circular and prismatic bodies under elastic high-cycle deformation and in condition of creep under prolonged static load is presented in this paper. The semianalytic finite element method (SFEM) to determine the stress-strain state is used. SFEM involves the application of finite element mesh in the cross section of the body, and using one finite element in the direction of straight or curved creating, which provides significantly lower computational cost for three- dimensional problems solving. The Kachanov-Rabotnov’s scalar damage parameter to describe the continual fracture of the material and the degree dependence of the damage parameter accumulation rate of on the stress state parameters are used. Stepping algorithms for the stress-strain state and damage parameter determining for considered deformation process have been developed. The algorithm of simulation of evolutionary processes of macroscopic defects (continual fracture zone) growth after local loss of material bearing capacity because of damage parameter’s critical value has been obtained. A solution of practical problems of determining of the calculated lifetime (to local loss of material bearing capacity) and the additional lifetime (time of continual fracture zone growth) for high pressure connecting pipe and the gas turbine blade has been presented. It is shown, that for the connecting pipe which represents thick-wall rotation body, lifetime is not limited to local loss of material bearing capacity and can be significantly extended by additional lifetime. At the same time for the blade under creep condition lifetime is completely determined by the local loss of material bearing capacity, because the value of additional lifetime is related to the continual fracture zone growth of only about 5% of the calculated lifetime

Optical vortex generation from molecular chromophore arrays

The generation of light endowed with orbital angular momentum, frequently termed optical vortex light, is commonly achieved by passing a conventional beam through suitably constructed optical elements. This Letter shows that the necessary phase structure for vortex propagation can be directly produced through the creation of twisted light from the vacuum. The mechanism is based on optical emission from a family of chromophore nanoarrays that satisfy specific geometric and symmetry constraints. Each such array can support pairs of electronically delocalized doubly degenerate excitons whose azimuthal phase progression is responsible for the helical wave front of the emitted radiation. The exciton symmetry dictates the maximum magnitude of topological charge; detailed analysis secures the conditions necessary to deliver optical vortices of arbitrary order

Theoretical and methodological approaches to management of resource flow processes of development projects on macro-, mezzo-, microlevels

Paper is devoted to the actual problem of managing resource flows of development projects as complex, unique, and open systems, across the different project lifecycle stages that differ in content and are distributed in space and time. The idea was to create a single throughout system for managing resource flow processes of the long-term projects. The research goal included development of theoretical and methodological approaches that can be used in order to manage the combination of development project resource flows using "order from chaos"paradigm. That includes by-stage organization of resource flow processes on of macro-, meso- and microscale, going from sources and sinks of the chaotic project environment resolve to ordered stages of project life cycles. It is proposed to implement resource flow management in form of the stage and resource-based "project-logistic"relay of a triune movement, ordering and transformation of the resource flow processes. This relay is created within a project-logistic field of project management that change by project phases. Synergetic effects of self-organization and self-control appear in the project logistic field due to horizontal interactions, sharing experience, competences, and values among the stakeholders in course of transforming entropic resource-flow processes into the negentropy processes related to project phase goals (attractors). Results can be used to forecast and develop multilevel resource-flow and process systems arranged by resource sources and sinks, and chaotically ordered for projects in different application areas. Further research perspectives include development of self-control and self-organization forms for development projects stakeholders that would comply with international best practices, and fit corresponding project stages. © Published under licence by IOP Publishing Ltd

INFLUENCE OF HELIOGEOPHYSICAL FACTORS ON HUMAN HEALTH

The purpose of this work is the development of the connection between a level of geomagnetic activity and a quantity of emergency calls for cardiovascular diseases. To perform the study we analyzed data on the quantity of emergency calls in Irkutsk during 8years period (2001-2004, 2007-2010). In total we analyzed 1460 days, 8942 cases of acute myocardial infarction and 1953 cases of intra-cerebral hemorrhage. There is a significant positive correlation between the number of ambulance calls for acute vascular pathology (myocardial infarction, intracerebral hemorrhage) and the Kp index over all years of study