146 research outputs found

    Eden growth model for aggregation of charged particles

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    The stochastic Eden model of charged particles aggregation in two-dimensional systems is presented. This model is governed by two parameters: screening length of electrostatic interaction, λ\lambda , and short range attraction energy, EE. Different patterns of finite and infinite aggregates are observed. They are of following types of morphologies: linear or linear with bending, warm-like, DBM (dense-branching morphology), DBM with nucleus, and compact Eden-like. The transition between the different modes of growth is studied and phase diagram of the growth structures is obtained in λ,E\lambda, E co-ordinates. The detailed aggregate structure analysis, including analysis of their fractal properties, is presented. The scheme of the internal inhomogeneous structure of aggregates is proposed.Comment: Revtex, 9 pages with 12 postscript figure

    Deterministic growth model of Laplacian charged particle aggregates

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    The results of the computer simulation of the aggregates growth of the similarly charged particles in the framework of deterministic Laplacian growth model on a square lattice are presented. Cluster growth is controlled by three parameters p,E,λ{p, E,\lambda}, where pp - Laplacian growth parameter, EE - energy of a particle sticking to a cluster, λ\lambda - the screening length of electrostatic interactions. The phase diagram of cluster growth is built in the co-ordinates E,λ{E,\lambda}. The zones of different cluster morphology are selected: I-the zone of finite X-like structures,II-the zone of infinite ramified structures, controlled by electrostatic interactions, III-the zone of infinite structures with electrostatic interactions effectively switched off. Simple electrostatic estimations of the locations of the zone boundaries are presented. It is shown that in general case within the zone II the continuous change of DfD_f, controlled by parameters p,E,λ{p, E,\lambda}, takes place. In the degeneration limit when the given model transforms into deterministic version of the Eden model (at p=0p=0), the crossover from linear (Df=1)(D_f=1) to compact (Df=2)(D_f=2) structures is observed when passing through the boundary between the zones I and II.Comment: REVTEX, 3 pages with 4 postscript figure

    Integral functions of electron lateral distribution and their fluctuations in electron-photon cascades

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    Monte Carlo simulated lateral distribution functions for electrons of EPC developing in lead, at superhigh energies (.1-1 PeV) for depths t or = 60 c.u. delta t=1t. c.u. are presented. The higher moment characteristics, i.e., variation, asymmetry, excess, are presented along with analytical solutions for the same characteristics at fixed observation level calculated to theory approximations A and B by using numerical inversion of the Laplace transformation. The conclusion is made of a complex, usually non-Gaussian shape of the function of the particle number distribution within a circle of given radius at fixed depth

    Comparative and legal study of the concept of crime under legislation of cis countries

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    This article analyzes the concept of crime under the criminal law of CIS countries, and reveals the specifics of the signs that make up this concept. The present study is based on the features that are most often found in the legislation of CIS countrie

    Tapping into rhythm generation circuitry in humans during simulated weightlessness conditions

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    An ability to produce rhythmic activity is ubiquitous for locomotor pattern generation and modulation. The role that the rhythmogenesis capacity of the spinal cord plays in injured populations has become an area of interest and systematic investigation among researchers in recent years, despite its importance being long recognized by neurophysiologists and clinicians. Given that each individual interneuron, as a rule, receives a broad convergence of various supraspinal and sensory inputs and may contribute to a vast repertoire of motor actions, the importance of assessing the functional state of the spinal locomotor circuits becomes increasingly evident. Air-stepping can be used as a unique and important model for investigating human rhythmogenesis since its manifestation is largely facilitated by a reduction of external resistance. This article aims to provide a review on current issues related to the "locomotor" state and interactions between spinal and supraspinal influences on the central pattern generator (CPG) circuitry in humans, which may be important for developing gait rehabilitation strategies in individuals with spinal cord and brain injuries

    Shape of primary proton spectrum in multi-TeV region from data on vertical muon flux

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    It is shown, that primary proton spectrum, reconstructed from sea-level and underground data on muon spectrum with the use of QGSJET 01, QGSJET II, NEXUS 3.97 and SIBYLL 2.1 interaction models, demonstrates not only model-dependent intensity, but also model-dependent form. For correct reproduction of muon spectrum shape primary proton flux should have non-constant power index for all considered models, except SIBYLL 2.1, with break at energies around 10-15 TeV and value of exponent before break close to that obtained in ATIC-2 experiment. To validate presence of this break understanding of inclusive spectra behavior in fragmentation region in p-air collisions should be improved, but we show, that it is impossible to do on the basis of the existing experimental data on primary nuclei, atmospheric muon and hadron fluxes.Comment: Submitted to Phys. Rev.

    Locating functionalized gold nanoparticles using electrical impedance tomography

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    Objective: An imaging device to locate functionalised nanoparticles, whereby therapeutic agents are transported from the site of administration specifically to diseased tissues, remains a challenge for pharmaceutical research. Here, we show a new method based on electrical impedance tomography (EIT) to provide images of the location of gold nanoparticles (GNPs) and the excitation of GNPs with radio frequencies (RF) to change impedance permitting an estimation of their location in cell models Methods: We have created an imaging system using quantum cluster GNPs as contrast agent, activated with RF fields to heat the functionalized GNPs, which causes a change in impedance in the surrounding region. This change is then identified with EIT. Results: Images of impedance changes of around 80±4% are obtained for a sample of citrate stabilized GNPs in a solution of phosphate-buffered saline. A second quantification was carried out using colorectal cancer cells incubated with culture media, and the internalization of GNPs into the colorectal cancer cells was undertaken to compare them with the EIT images. When the cells were incubated with functionalised GNPs, the change was more apparent, approximately 40±2%. This change was reflected in the EIT image as the cell area was more clearly identifiable from the rest of the area. Significance: EIT can be used as a new method to locate functionalized GNPs in human cells and help in the development of GNP-based drugs in humans to improve their efficacy in the future

    Анализ электромагнитной совместимости рельсовых цепей и тягового электроснабжения

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    [For the English abstract and full text of the article please see the attached PDF-File (English version follows Russian version)].ABSTRACT The issues of electromagnetic compatibility of traction power supply devices with track circuits are considered in case ice phenomena on the contact wire. The calculated ratios for determining the value of the bias currents of the choke-transformers in the electric arc, which arises from the formation of ice on the contact wire, as well as the reasons for false occupation of track circuits at the station are analyzed. Keywords: electromagnetic compatibility, track circuit, electric arc, asymmetry coefficient, traction current, contact wire, resistivity of rails.Текст аннотации на англ. языке и полный текст статьи на англ. языке находится в прилагаемом файле ПДФ (англ. версия следует после русской версии).Рассмотрены вопросы электромагнитной совместимости устройств тягового электроснабжения с рельсовыми цепями при гололёдных явлениях на контактном проводе. Приводятся расчетные соотношения для определения значения токов подмагничивания дроссель- трансформаторов при электрической дуге, возникающей вследствие образования наледи на контактном проводе, а также анализируются причины ложной занятости рельсовых цепей на станции

    International standards of penitentiary activity: impact on the development of the penitentiary activity of the CIS countries

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    Overcrowding in prisons is a common problem that affects many countries. It is difficult to define this term because there is no single internationally accepted standard. This article presents a comparative study of international standards for the activities of doctors in penitentiary institutions as an integral part of international standards of penitentiary activity. The authors investigated the methods and the degree of their impact on the penitentiary legislation of the Russian Federation and other CIS countries. The conclusion is drawn about the positive role of such standards in improving the national penitentiary legislation in order to increase the level of medical care for prisoner

    Locating Functionalized Gold Nanoparticles Using Electrical Impedance Tomography

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    Abstract Objective: An imaging device to locate functionalized nanoparticles, whereby therapeutic agents are transported from the site of administration specifically to diseased tissues, remains a challenge for pharmaceutical research. Here, we show a new method based on electrical impedance tomography (EIT) to provide images of the location of gold nanoparticles (GNPs) and the excitation of GNPs with radio frequencies (RF) to change impedance permitting an estimation of their location in cell models Methods: We have created an imaging system using quantum cluster GNPs as a contrast agent, activated with RF fields to heat the functionalized GNPs, which causes a change in impedance in the surrounding region. This change is then identified with EIT. Results: Images of impedance changes of around 804% are obtained for a sample of citrate stabilized GNPs in a solution of phosphate-buffered saline. A second quantification was carried out using colorectal cancer cells incubated with culture media, and the internalization of GNPs into the colorectal cancer cells was undertaken to compare them with the EIT images. When the cells were incubated with functionalized GNPs, the change was more apparent, approximately 402%. This change was reflected in the EIT image as the cell area was more clearly identifiable from the rest of the area. Significance: EIT can be used as a new method to locate functionalized GNPs in human cells and help in the development of GNP-based drugs in humans to improve their efficacy in the future
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