150 research outputs found
Scatter-free pickup ions beyond the heliopause as a model for the Interstellar Boundary Explorer (IBEX) ribbon
We present new kinetic-gasdynamic model of the solar wind interaction with
the local interstellar medium. The model incorporates several processes
suggested by McComas et al. (2009) for the origin of the heliospheric ENA
ribbon -- the most prominent feature seen in the all sky maps of heliospheric
ENAs discovered by the Interstellar Boundary Explorer (IBEX). The ribbon is a
region of enhanced fluxes of ENAs crossing almost the entire sky. Soon after
the ribbon's discovery it was realized (McComas et al., 2009) that the
enhancement of the fluxes could be in the directions where the radial component
of the interstellar magnetic field around the heliopause is close to zero
(Schwadron et al., 2009). Our model includes secondary charge exchange of the
interstellar H atoms with the interstellar pickup protons outside the
heliopause and is a further advancement of the kinetic-gasdynamic model by
Malama et al. (2006) where pickup protons were treated as a separate kinetic
component. Izmodenov et al. (2009) have shown in the frame of Malama's model
that the interstellar pickup protons outside the heliopause maybe a significant
source of ENAs at energies above 1 keV. The difference between the current work
and that of Izmodenov et al. (2009) is in the assumption of no-scattering for
newly created pickup protons outside the heliopause. In this limit the model
produces a feature qualitatively similar to the ribbon observed by IBEX.Comment: submitted to ApJ
Modeling of the heliospheric interface: multi-component nature of the heliospheric plasma
We present a new model of the heliospheric interface - the region of the
solar wind interaction with the local interstellar medium. This new model
performs a multi-component treatment of charged particles in the heliosphere.
All charged particles are divided into several co-moving types. The coldest
type, with parameters typical of original solar wind protons, is considered in
the framework of fluid approximation. The hot pickup proton components created
from interstellar H atoms and heliospheric ENAs by charge exchange, electron
impact ionization and photoionization are treated kinetically. The charged
components are considered self-consistently with interstellar H atoms, which
are described kinetically as well. To solve the kinetic equation for H atoms we
use the Monte Carlo method with splitting of trajectories, which allows us 1)
to reduce statistical uncertainties allowing correct interpretation of
observational data, 2) to separate all H atoms in the heliosphere into several
populations depending on the place of their birth and on the type of parent
protons.Comment: A&A accepte
Heating of the solar wind in the outer heliosphere
International audienceSmall-scale Alfvènic turbulence in the outer heliosphere is mainly determined by a source which is connected with the instability of the initially highly anisotropic velocity distribution of interstellar pick-up protons. The main portion of the generated turbulent energy is subsequently absorbed by the pick-up protons themselves due to the cyclotron-resonant interaction between waves and particles. A small fraction of this energy can be transferred to solar wind protons resulting in their heating. The heating is more efficient in the high-speed solar wind
Fluorescence of the Polymethine Dye Tiks and Diagnostics af Cancert
It is shown that the fluorescence of the polymethine dye TIKS, whose absorption and fluorescence bands are located in the spectral region of transmission of biological tissues, can be recorded from a depth of up to 1.5 cm of an animal’s body. The intensity of the fluorescence recorded from the surface of the animal’s body in intravenous injection of the dye (1–2 mg/kg) is in direct proportion to its concentration in tumor nodes and muscles. In rapidly growing tumors, a high (up to 3.6) degree of contrast of the content of the dye is attained in tumor tissues as compared to the surrounding normal tissues. Over the course of 7 days after the injection, the dye is practically completely removed from both the tumor and normal muscular tissues. From the change in the fluorescence intensity in scanning the surface one can determine the regions of localization of tumor nodes against the background of the surrounding normal tissues and the presence of regions with a nonuniform distribution of the dye
A TOOLBOX FOR SEDIMENT BUDGET RESEARCH IN SMALL CATCHMENTS
© 2017, Lomonosov Moscow State University. All rights reserved. Sediment monitoring and assessment remain one of the most challenging tasks in fluvial geomorphology and water quality studies. As a response to various environmental and human disturbance effects, the main sources and pathways of the sediments transported within catchments, especially most pristine small one, may change. The paper discusses state-of-the-art in the sediment budget research for small catchments. We identified nine independent approaches in the sediment transport assessment and applied them in 11 catchments across Eurasia in the framework of an FP-7 Marie Curie-International Research Staff Exchange Scheme in 2012-2016. These methods were classified as: i) Field-based methods (In-situ monitoring of sediment transport;-Soil morphological methods and dating techniques; Sediment source fingerprinting; Sediment-water discharge relationships), ii) GIS and remote sensing approaches (Riverbed monitoring based on remote sensing/historical maps; parametrization of the channel sediment connectivity; Sediment transport remote sensing modeling), and iii) Numerical approaches (Soil erosion modeling and gully erosion (stochastic and empirical models); channel hydrodynamic modeling). We present the background theory and application examples of all selected methods. Linking fieldbased methods and datasets with numerical approaches, process measurements as well as monitoring can provide enhanced insights into sediment transfer and related water quality impacts. Adopting such integrated and multi-scale approaches in a sediment budget framework might contribute to improved understanding of hydrological and geomorphological responses
A toolbox for sediment budget research in small catchments
© 2017, Lomonosov Moscow State University. All rights reserved. Sediment monitoring and assessment remain one of the most challenging tasks in fluvial geomorphology and water quality studies. As a response to various environmental and human disturbance effects, the main sources and pathways of the sediments transported within catchments, especially most pristine small one, may change. The paper discusses state-of-the-art in the sediment budget research for small catchments. We identified nine independent approaches in the sediment transport assessment and applied them in 11 catchments across Eurasia in the framework of an FP-7 Marie Curie-International Research Staff Exchange Scheme in 2012-2016. These methods were classified as: i) Field-based methods (In-situ monitoring of sediment transport;-Soil morphological methods and dating techniques; Sediment source fingerprinting; Sediment-water discharge relationships), ii) GIS and remote sensing approaches (Riverbed monitoring based on remote sensing/historical maps; parametrization of the channel sediment connectivity; Sediment transport remote sensing modeling), and iii) Numerical approaches (Soil erosion modeling and gully erosion (stochastic and empirical models); channel hydrodynamic modeling). We present the background theory and application examples of all selected methods. Linking fieldbased methods and datasets with numerical approaches, process measurements as well as monitoring can provide enhanced insights into sediment transfer and related water quality impacts. Adopting such integrated and multi-scale approaches in a sediment budget framework might contribute to improved understanding of hydrological and geomorphological responses
On the effect of transport coefficient anisotropy on the plasma flow in heliospheric interface
The plasma flow in the heliospheric interface is considered. The applicability of hydrodynamic description for this flow is studied. The effect of the magnetic field on the transport properties in the interface plasma is discussed and the dimensionless parameters related to the plasma flow are estimated. It is found that both resistivity and Hall effect can be neglected in Ohm's law, so that the classical induction equation of the ideal magnetohydrodynamic can be used. The Reynolds number is moderately large, so the approximation of inviscid plasma is fairly good. The most important dissipative process is thermal conduction along the magnetic field lines. This effect has to be definitely taken into account. The results obtained in the paper are used to outline the ways for advancing the existing models of the heliospheric interface
АКТУАЛЬНЫЕ ЗАДАЧИ ПОВЫШЕНИЯ ЭФФЕКТИВНОСТИ ВЫСШЕЙ ШКОЛЫ НА СОВРЕМЕННОМ ЭТАПЕ РАЗВИТИЯ РОССИИ
The education system continues to be the subject of attention of science and government, business and society. The authors express their own vision of progress based on cooperation of science and higher education.Система образования продолжает оставаться предметом внимания науки и власти, бизнеса и общества. Авторы высказывают собственное видение достижения прогресса на основе взаимодействия науки и высшей школы
Neutral H density at the termination shock: a consolidation of recent results
We discuss a consolidation of determinations of the density of neutral
interstellar H at the nose of the termination shock carried out with the use of
various data sets, techniques, and modeling approaches. In particular, we focus
on the determination of this density based on observations of H pickup ions on
Ulysses during its aphelion passage through the ecliptic plane. We discuss in
greater detail a novel method of determination of the density from these
measurements and review the results from its application to actual data. The H
density at TS derived from this analysis is equal to 0.087 \pm 0.022 cm-3, and
when all relevant determinations are taken into account, the consolidated
density is obtained at 0.09 \pm 0.022 cm-3. The density of H in CHISM based on
literature values of filtration factor is then calculated at 0.16 \pm 0.04
cm-3.Comment: Submitted to Space Science Review
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