Results for "S. Poedts"

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Cumulative whistler instability in fast solar winds: Constraints of electron temperature anisotropyApr 12 2019Context. Solar outflows are a considerable source of free energy which accumulates in multiple forms like beaming (or drifting) components and/or temperature anisotropies. However, kinetic anisotropies of plasma particles do not grow indefinitely and ... More
Nonlinear three wave interaction in pair plasmasJul 27 2010It is shown that nonlinear three-wave interaction, described by vector-product type nonlinearities, in pair plasmas implies much more restrictive conditions for a double energy transfer, as compared to electron-ion plasmas.
A new paradigm for solar coronal heatingApr 29 2009The solar coronal heating problem refers to the question why the temperature of the Sun's corona is more than two orders of magnitude higher than that of its surface. Almost 70 years after the discovery, this puzzle is still one of the major challenges ... More
Global convective cell formation in pair-ion plasmasMay 30 2008The global electrostatic mode in pair-ion plasmas is discussed for cylindric geometry and for a radially inhomogeneous equilibrium density. In the case of a Gaussian radial density profile, exact analytical eigen solutions are found in terms of the Kummer ... More
Features of ion acoustic waves in collisional plasmasFeb 12 2010The effects of friction on the ion acoustic (IA) wave in fully and partially ionized plasmas are studied. In a quasi-neutral electron-ion plasma the friction between the two species cancels out exactly and the wave propagates without any damping. If the ... More
Comment on 'Alfven Instability in a Compressible Flow' [Phys. Rev. Lett. 101, 245001 (2008)]Apr 28 2009In a recent paper [Y. Taroyan, Phys. Rev. Lett 101, 245001 (2008) it is claimed that a new MHD instability of the Alfven wave has been found: incompressible Alfven modes propagating in a compressible spatially varying flow were apparently exponentially ... More
Comment on "Drift instabilities in the solar corona within the multi-fluid description" [Astron. Astrophys. {\bf 481}, 853 (2008)]Nov 14 2008Mecheri and Marsch concluded that drift currents caused by density gradients can serve as an energy source for a plasma instability, in particular for the excitation of ion-cyclotron waves in the solar corona. It is pointed out that these authors overlooked ... More
Note on the role of friction-induced momentum conservation in the collisional drift wave instabilityMay 16 2008The collisional drift wave instability is reexamined taking into account the ion response in the direction parallel to the magnetic field lines, which appears due to friction with electrons and which can not be omitted in view of the momentum conservation. ... More
Drift waves in the corona: heating and acceleration of ions at frequencies far below the gyro frequencyJul 27 2010In the solar corona, several mechanisms of the drift wave instability can make the mode growing up to amplitudes at which particle acceleration and stochastic heating by the drift wave take place. The stochastic heating, well known from laboratory plasma ... More
The universally growing mode in the solar atmosphere: coronal heating by drift wavesJun 11 2009The heating of the plasma in the solar atmosphere is discussed within both frameworks of fluid and kinetic drift wave theory. We show that the basic ingredient necessary for the heating is the presence of density gradients in the direction perpendicular ... More
Growing drift-cyclotron modes in the hot solar atmosphereMay 31 2008Well-known analytical results dealing with ion cyclotron and drift waves and which follow from the kinetic theory are used and the dispersion equation, which describes coupled two modes, is solved numerically. The numerical results obtained by using the ... More
Kinetic instability of drift-Alfven waves in solar corona and stochastic heatingJul 28 2010The solar atmosphere is structured and inhomogeneous both horizontally and vertically. The omnipresence of coronal magnetic loops implies gradients of the equilibrium plasma quantities like the density, magnetic field and temperature. These gradients ... More
Solar nanoflares and other smaller energy release events as growing drift wavesSep 09 2009Rapid energy releases (RERs) in the solar corona extend over many orders of magnitude, the largest (flares) releasing an energy of $10^{25} $J or more. Other events, with a typical energy that is a billion times less, are called nanoflares. A basic difference ... More
Perpendicular electron collisions in drift and acoustic wave instabilitiesDec 31 2008Perpendicular electron dynamics and the associated collisions are discussed in relation to the collisional drift wave instability. In addition, the limit of small parallel wave numbers of this instability is studied and it is shown to yield a reduced ... More
Electric fields in solar magnetic structures due to gradient driven instabilities: heating and acceleration of particlesSep 03 2009The electrostatic instabilities driven by the gradients of the density, temperature and magnetic field, are discussed in their application to solar magnetic structures. Strongly growing modes are found for some typical plasma parameters. These instabilities ... More
On the effect of the inhomogeneous subsurface flows on the high degree solar p-modesApr 14 2005The observed power spectrum of high-degree solar p-modes (l>200) shows discrepancies with the power spectrum predicted by the stochastic excitement and damping theory. In an attempt to explain these discrepancies, the present paper is concerned with the ... More
On the evolution of pre-flare patterns of a 3-dimensional model of AR 11429Jan 01 2018We apply a novel pre-flare tracking of sunspot groups towards improving the estimation of flare onset time by focusing on the evolution of the 3D magnetic field construction of AR 11429. The 3D magnetic structure is based on potential field extrapolation ... More
Weak and strong regimes of incompressible magnetohydrodynamic turbulenceJul 06 2009It is shown that in the framework of the weak turbulence theory, the autocorrelation and cascade timescales are always of the same order of magnitude. This means that, contrary to the general belief, any model of turbulence which implies a large number ... More
Self Heating of Corona by Electrostatic Fields Driven by Sheared FlowsJan 03 2012A mechanism of self-heating of solar corona is pointed out. It is shown that the free energy available in the form of sheared flows gives rise to unstable electrostatic waves which accelerate the particles and heat them. The electrostatic perturbations ... More
On quantum plasma: a plea for a common senseJul 15 2012The quantum plasma theory has flourished in the past few years without much regard to the physical validity of the formulation or its connection to any real physical system. It is argued here that there is a very limited physical ground for the application ... More
Kinetic instability of ion acoustic mode in permeating plasmasJun 19 2009In plasmas with electron drift (current) relative to static ions, the ion acoustic wave is subject to the kinetic instability which takes place if the directed electron speed exceeds the ion acoustic speed. The instability threshold becomes different ... More
Is the Weibel instability enhanced by the suprathermal populations, or not?Apr 15 2010The kinetic instabilities of the Weibel-type are presently invoked in a large variety of astrophysical scenarios because anisotropic plasma structures are ubiquitous in space. The Weibel instability is driven by a temperature anisotropy which is commonly ... More
Response to Comment of Shukla and Akbari-MoghanjoughiAug 13 2012Aug 15 2012Shukla and Akbari-Moghanjoughi have {\it corrected} their Comment (see their version 1 on `arXiv:1207.7029v1) to EPL on our work [1] after receiving our Response from the Editors of EPL. We have a pleasant duty at hand to present our second Response to ... More
Electrostatic ion perturbations in kinematically complex shear flowsApr 16 2015The scope of the present paper is to determine how ion electrostatic wave perturbations in plasma flows are influenced by the presence of a kinematically complex velocity shear. For this purpose we consider a model based on the following set of physical ... More
A modified orbital motion limited (OML) theoryOct 28 2011The validity of the orbital motion limited (OML) theory is reviewed with reference to the floating potential acquired by a spherical object immersed in a plasma. A new and perhaps more realistic approach for obtaining the floating potential is introduced ... More
Comparative analysis of solar radio bursts before and during CME propagationMar 28 2019As is well known, CME propagation often results in the fragmentation of the solar atmosphere on smaller regions of density (magnetic field) enhancement (depletion). It is expected that this type of fragmentation may have radio signatures. The general ... More
Firehose constraints for the solar wind suprathermal electronsApr 19 2016The indefinite increase of temperature predicted by the solar wind expansion in the direction parallel to the interplanetary magnetic field is already notorious for not being confirmed by the observations. In hot and dilute plasmas from space particle-particle ... More
Shaping the solar wind temperature anisotropy by the interplay of electron and proton instabilitiesDec 03 2016A variety of nonthermal characteristics like kinetic, e.g., temperature, anisotropies and suprathermal populations (enhancing the high energy tails of the velocity distributions) are revealed by the in-situ observations in the solar wind indicating quasistationary ... More
Observational Characteristics of CMEs without Low Coronal SignaturesSep 04 2014Solar eruptions are usually associated with a variety of phenomena occurring in the low corona before, during, and after onset of eruption. Though easily visible in coronagraph observations, so-called stealth coronal mass ejections (CMEs) do not obviously ... More
Collisional energy transfer in two-component plasmasAug 18 2008The friction in plasmas consisting of two species with different temperatures is discussed together with the consequent energy transfer. It is shown that the friction between the two species has no effect on the ion acoustic mode in a quasi-neutral plasma. ... More
Effects of suprathermal electrons on the proton temperature anisotropy in space plasmas: Electromagnetic ion-cyclotron instabilityFeb 12 2016May 11 2016In collision-poor plasmas from space, e.g., the solar wind and planetary magnetospheres, the kinetic anisotropy of the plasma particles is expected to be regulated by the kinetic instabilities. Driven by an excess of ion (proton) temperature perpendicular ... More
Amplification of compressional MHD waves in systems with forced entropy oscillationsSep 06 2007The propagation of compressional MHD waves is studied for an externally driven system. It is assumed that the combined action of the external sources and sinks of the entropy results in the harmonic oscillation of the entropy (and temperature) in the ... More
On electrostatic modes in multi-ion and pair-ion collisional plasmasMay 16 2008The physics of plasmas containing positive and negative ions is discussed with special attention to the recently produced pair-ion plasma containing ions of equal mass and opposite charge. The effects of the density gradient in the direction perpendicular ... More
Ion thermal effects in oscillating multi-ion plasma sheath theoryNov 03 2008The effects of ion temperature are discussed in a two-ion electron plasma and for a model applicable to the oscillating sheath theory that has recently been much in the focus of researchers. The differences between the fluid and kinetic models have been ... More
Modelling three-dimensional transport of solar energetic protons in a corotating interaction region generated with EUHFORIAJan 28 2019We introduce a new solar energetic particle (SEP) transport code that aims at studying the effects of different solar wind configurations on SEP events. We focus on the influence of varying solar wind velocities on the energy changes of SEPs, and study ... More
Constraints for the aperiodic O-mode streaming instabilityNov 06 2014Dec 21 2014In plasmas where the thermal energy density exceeds the magnetic energy density ($\beta_\parallel > 1$), the aperiodic ordinary mode (O-mode) instability is driven by an excess of parallel temperature $A = T_\perp /T_\parallel < 1$ (where $\parallel$ ... More
Acoustic oscillations in the field-free, gravitationally stratified Acoustic oscillations in the field-free, gravitationally stratified cavities under solar bipolar magnetic canopiesMay 14 2009The main goal is to study the dynamics of the gravitationally stratified, field-free cavities in the solar atmosphere, located under small-scale, cylindrical magnetic canopies, in response to explosive events in the lower-lying regions (due to granulation, ... More
'Swing Absorption' of fast magnetosonic waves in inhomogeneous mediaAug 05 2004Oct 07 2004The recently suggested swing interaction between fast magnetosonic and Alfven waves (Zaqarashvili and Roberts 2002) is generalized to inhomogeneous media. We show that the fast magnetosonic waves propagating across an applied non-uniform magnetic field ... More
Is the solar corona nonmodally self-heated?Oct 11 2004Recently it was pointed out that nonmodally (transiently and/or adiabatically) pre-amplified waves in shear flows, undergoing subsequent viscous damping, can ultimately heat the ambient flow. The key ingredient of this process is the ability of waves ... More
The Electron Firehose and Ordinary-Mode Instabilities in Space PlasmasJul 02 2013The selfgenerated wave fluctuations are particularly interesting in the solar wind and magnetospheric plasmas, where Coulomb collisions are rare and cannot explain the observed states of quasi-equilibrium. Linear theory predicts that the firehose and ... More
Modeling space plasma dynamics with anisotropic Kappa distributionsApr 02 2012Space plasmas are collisionpoor and kinetic effects prevail leading to wave fluctuations, which transfer the energy to small scales: wave-particle interactions replace collisions and enhance dispersive effects heating particles and producing suprathermal ... More
The Interplay of the Solar Wind Core and Suprathermal Electrons: A Quasilinear Approach for Firehose InstabilityJan 31 2019In the solar wind an equipartition of kinetic energy densities can be easily established between thermal and suprathermal electrons and the instability conditions are markedly altered by the interplay of these two populations. The new thresholds derived ... More
The mechanism of Swing Absorption of fast magnetosonic waves in inhomogeneous mediaOct 11 2004The recently suggested swing interaction between fast magnetosonic and Alfv\'en waves (2002) is generalized to inhomogeneous media. We show that the fast magnetosonic waves propagating across an applied non-uniform magnetic field can parametrically amplify ... More
Magnetic clouds in the solar wind: A numerical assessment study of analytical modelsSep 17 2011Magnetic clouds (MCs) are "magnetized plasma clouds" moving in the solar wind. MCs transport magnetic flux and helicity away from the Sun. These structures are not stationary but feature temporal evolution as they propagate in the solar wind. Simplified ... More
Electrostatic plasma instabilities driven by neutral gas flows in the solar chromosphereDec 19 2013We investigate electrostatic plasma instabilities of Farley-Buneman (FB) type driven by quasi-stationary neutral gas flows in the solar chromosphere. The role of these instabilities in the chromosphere is clarified. We find that the destabilizing ion ... More
Farley-Buneman Instability in the Solar ChromosphereFeb 25 2009The Farley-Buneman instability is studied in the partially ionized plasma of the solar chromosphere taking into account the finite magnetization of the ions and Coulomb collisions. We obtain the threshold value for the relative velocity between ions and ... More
Energy flux of Alfven waves in weakly ionized plasmaMay 29 2008The overshooting convective motions in the solar photosphere are frequently proposed as the source for the excitation of Alfv\'en waves. However, the photosphere is a) very weakly ionized, and, b) the dynamics of the plasma particles in this region is ... More
Observation-based modelling of magnetised Coronal Mass Ejections with EUHFORIAApr 15 2019Coronal Mass Ejections (CMEs) are the primary source of strong space weather disturbances at Earth. Their geoeffectiveness is largely determined by their dynamic pressure and internal magnetic fields, for which reliable predictions at Earth are not possible ... More
The Electron Temperature and Anisotropy in the Solar Wind. I. Comparison of the Core and Halo PopulationsFeb 26 2016Estimating the temperature of the solar wind particles and their anisotropies is particularly important for understanding the origin of these deviations from thermal equilibrium as well as their effects. In the absence of energetic events the velocity ... More
Overstability of acoustic waves in strongly magnetized anisotropic MHD shear flowsJul 25 2014Dec 08 2015We present a linear stability analysis of the perturbation modes in anisotropic MHD flows with velocity shear and strong magnetic field. Collisionless or weakly collisional plasma is described within the 16-momentum MHD fluid closure model, that takes ... More
Dissipation of parallel and oblique Alfvén-cyclotron waves: implications for minor ion heating in the solar windJun 17 2015We perform 2.5D hybrid simulations with massless fluid electrons and kinetic particle-in-cell ions to study the temporal evolution of ion temperatures, temperature anisotropies and velocity distribution functions in relation to the dissipation and turbulent ... More
Variation of proton flux profiles with the observer's latitude in simulated gradual SEP eventsOct 17 2013We study the variation of the shape of the proton intensity-time profiles in simulated gradual Solar Energetic Particle (SEP) events with the relative observer's position in space with respect to the main direction of propagation of an interplanetary ... More
Solar Wind Electron Strahls Associated with a High-Latitude CME: \emph{Ulysses} ObservationsMay 22 2014Counterstreaming beams of electrons are ubiquitous in coronal mass ejections (CMEs) - although their existence is not unanimously accepted as a necessary and/or sufficient signature of these events. We continue the investigations of a high-latitude CME ... More
Acceleration of dust particles by vortex ringNov 11 2009It is shown that nonlinear interaction between large amplitude circularly polarized EM wave and dusty plasma leads to a nonstationary ponderomotive force which in turn produces a vortex ring, and magnetic field. Then the ensuing vortex ring in the direction ... More
Quasilinear Approach of the Whistler Heat-Flux Instability in the Solar WindMar 19 2019The hot beaming (or strahl) electrons responsible for the main electron heat-flux in the solar wind are believed to be self-regulated by the electromagnetic beaming instabilities, also known as the heat-flux instabilities. Here we report the first quasi-linear ... More
Dynamics of a solar prominence tornado observed by SDO/AIA on 2012 November 7-8Aug 27 2015We study the detailed dynamics of a solar prominence tornado using time series of 171, 304, 193 and 211 {\AA} spectral lines obtained by Solar Dynamics Observatory/ Atmospheric Imaging Assembly during 2012 November 7-8. The tornado first appeared at 08:00 ... More
Acoustic oscillations in a field-free cavity under solar small-scale bipolar magnetic canopyJan 18 2008Observations show the increase of high-frequency wave power near magnetic network cores and active regions in the solar lower atmosphere. This phenomenon can be explained by the interaction of acoustic waves with a magnetic field. We consider small-scale, ... More
Fine and superfine structure of Decameter-Hectometer type II burst on 2011 June 7Aug 27 2015The characteristics of the type II bursts with herringbone structure observed both by ground based radio telescopes (UTR-2, URAN-2) and spaceborn spectrometers (STEREO A-B) are discussed. The burst was recorded on 7 June, 2011 in the frequency band 3--33~MHz. ... More
Formation and evolution of coronal rain observed by SDO/AIA on February 22, 2012Apr 14 2015The formation and dynamics of coronal rain are currently not fully understood. Coronal rain is the fall of cool and dense blobs formed by thermal instability in the solar corona towards the solar surface with acceleration smaller than gravitational free ... More
Linking two consecutive nonmerging magnetic clouds with their solar sourcesDec 21 2012On 15 May 2005, a huge interplanetary coronal mass ejection (ICME) was observed near Earth. It triggered one of the most intense geomagnetic storms of solar cycle 23 (Dst peak = -263 nT). This structure has been associated with the two-ribbon flare, filament ... More
Long-period oscillations of active region patterns: least-squares mapping on second-order curvesOct 05 2016Oct 06 2016Active regions (ARs) are the main sources of variety in solar dynamic events. Automated detection and identification tools need to be developed for solar features for a deeper understanding of the solar cycle. Of particular interest here are the dynamical ... More
On over-reflection and generation of Gravito-Alfven waves in solar-type starsApr 30 2007The dynamics of linear perturbations is studied in magnetized plasma shear flows with a constant shearing rate and with gravity-induced stratification. The general set of linearized equations is derived and the two-dimensional case is considered in detail. ... More
Magnetic Field Configuration Models and Reconstruction Methods for Interplanetary Coronal Mass EjectionsSep 27 2012This study aims to provide a reference to different magnetic field models and reconstruction methods for interplanetary coronal mass ejections (ICMEs). In order to understand the differences in the outputs of those models and codes, we analyze 59 events ... More
Quantifying shear-induced wave transformations in the solar windMar 20 2007The possibility of velocity shear-induced linear transformations of different magnetohydrodynamic waves in the solar wind is studied both analytically and numerically. A quantitative analysis of the wave transformation processes for all possible plasma-$\beta$ ... More
Self-heating and its possible relationship to chromospheric heating in slowly rotating starsSep 29 2009The efficiency of nonmodal self-heating by acoustic wave perturbations is examined. Considering different kinds of kinematically complex velocity patterns we show that nonmodal instabilities arising in these inhomogeneous flows may lead to significant ... More
Effect of gravitational stratification on the propagation of a CMEOct 25 2013Our aim is to study the role of gravitational stratification on the propagation of CMEs. In particular, we assess how it influences the speed and shape of CMEs and under what conditions the flux rope ejection becomes a CME or when it is quenched. We ran ... More
Self-heating in kinematically complex magnetohydrodynamic flowsNov 17 2012The non-modal self-heating mechanism driven by the velocity shear in kinematically complex magnetohydrodynamic (MHD) plasma flows is considered. The study is based on the full set of MHD equations including dissipative terms. The equations are linearized ... More
Simulating AIA observations of a flux rope ejectionJul 31 2014Extreme ultraviolet (EUV) images from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamic Observatory (SDO) are providing new insights into the early phase of CME evolution. Observations now show the ejection of magnetic flux ropes from ... More
The Effect of Limited Sample Sizes on the Accuracy of the Estimated Scaling Parameter for Power-Law-Distributed Solar DataMay 23 2016Many natural processes exhibit power-law behavior. The power-law exponent is linked to the underlying physical process and therefore its precise value is of interest. With respect to the energy content of nanoflares, for example, a power-law exponent ... More
Interplanetary spread of solar energetic protons near a high-speed solar wind streamMar 21 2019We study how a high-speed solar wind stream embedded in a slow solar wind influences the spread of solar energetic protons in interplanetary space. To model the energetic protons, we used a recently developed particle transport code that computes particle ... More
Halo Coronal Mass Ejections during Solar Cycle 24: reconstruction of the global scenario and geoeffectivenessDec 15 2017In this study we present a statistical analysis of 53 fast Earth-directed halo CMEs observed by the SOHO/LASCO instrument during the period Jan. 2009-Sep. 2015, and we use this CME sample to test the capabilities of a Sun-to-Earth prediction scheme for ... More
Investigation of Dynamics of Self-Similarly Evolving Magnetic CloudsOct 18 2010Magnetic clouds (MCs) are "magnetized plasma clouds" moving in the solar wind. MCs transport magnetic flux and helicity away from the Sun. These structures are not stationary but feature temporal evolution. Commonly, simplified MC models are considered. ... More
Multifluid modeling of magnetosonic wave propagtion in the solar chromosphere -- effects of impact ionization and radiative recombinationNov 25 2016In order to study chromospheric magnetosonic wave propagation including, for the first time, the effects of ion-neutral interactions in the partially ionized solar chromosphere, we have developed a new multi-fluid computational model, accounting for ionization ... More
Multifluid modeling of magnetosonic wave propagation in the solar chromosphere -- effects of impact ionization and radiative recombinationNov 25 2016Dec 01 2016In order to study chromospheric magnetosonic wave propagation including, for the first time, the effects of ion-neutral interactions in the partially ionized solar chromosphere, we have developed a new multi-fluid computational model, accounting for ionization ... More
A GPU-enabled implicit Finite Volume solver for the ideal two-fluid plasma model on unstructured gridsSep 07 2018Dec 23 2018This paper describes the main features of a pioneering unsteady solver for simulating ideal two-fluid plasmas on unstructured grids, taking profit of GPGPU (General-purpose computing on graphics processing units). The code, which has been implemented ... More
Observational evidence of torus instability as trigger mechanism for coronal mass ejections: the 2011 August 4 filament eruptionJan 23 2014Solar filaments are magnetic structures often observed in the solar atmosphere and consist of plasma that is cooler and denser than their surroundings. They are visible for days -- and even weeks -- which suggests that they are often in equilibrium with ... More
Rieger-type periodicity during solar cycles 14-24: estimation of dynamo magnetic field strength in the solar interiorMay 13 2016Solar activity undergoes a variation over time scales of several months known as Rieger-type periodicity, which usually occurs near maxima of sunspot cycles. An early analysis showed that the periodicity appears only in some cycles, and is absent in other ... More
Evidence for precursors of the coronal hole jets in solar bright pointsMar 01 2018A set of 23 observations of coronal jet events that occurred in coronal bright points has been analyzed. The focus was on the temporal evolution of the mean brightness before and during coronal jet events. In the absolute majority of the cases either ... More
Statistical properties of coronal hole rotation rates: Are they linked to the solar interior?Jun 14 2017The present paper discusses results of a statistical study of the characteristics of coronal hole (CH) rotation in order to find connections to the internal rotation of the Sun. The goal is to measure CH rotation rates and study their distribution over ... More
Band insulator to Mott insulator transition in a bilayer Hubbard modelMar 27 2007The ground state phase diagram of the half-filled repulsive Hubbard model in a bilayer is investigated using cluster dynamical mean field theory. For weak to intermediate values of Coulomb repulsion $U$, the system undergoes a transition from a Mott insulating ... More
Event-Driven Molecular Dynamics in ParallelFeb 03 2003Sep 16 2003Although event-driven algorithms have been shown to be far more efficient than time-driven methods such as conventional molecular dynamics, they have not become as popular. The main obstacle seems to be the difficulty of parallelizing event-driven molecular ... More
Band dispersion and electronic lifetimes in crystalline organic semiconductorsJan 11 2011Mar 31 2011The consequences of several microscopic interactions on the photoemission spectra of crystalline organic semiconductors (OSC) are studied theoretically. It is argued that their relative roles can be disentangled by analyzing both their temperature and ... More
Band-like motion and mobility saturation in organic molecular semiconductorsOct 22 2009Dec 07 2009We analyze a model that accounts for the inherently large thermal lattice fluctuations associated to the weak van der Waals inter-molecular bonding in crystalline organic semiconductors. In these materials the charge mobility generally exhibits a "metallic-like" ... More
Optical properties of small polarons from dynamical mean-field theoryDec 09 2005Feb 27 2006The optical properties of polarons are studied in the framework of the Holstein model by applying the dynamical mean-field theory. This approach allows to enlighten important quantitative and qualitative deviations from the limiting treatments of small ... More
Hopping dynamics of interacting polaronsOct 02 2008We derive an effective cluster model to address the transport properties of mutually interacting small polarons. We propose a decoupling scheme where the hopping dynamics of any given particle is determined by separating out explicitly the degrees of ... More
Metric-affine $f(R)$-gravity with torsion: an overviewOct 27 2009Torsion and curvature could play a fundamental role in explaining cosmological dynamics. f(R)-gravity with torsion is an approach aimed to encompass in a comprehensive scheme all the Dark Side of the Universe (Dark Energy and Dark Matter). We discuss ... More
Groups of quasi-invariance and the Pontryagin dualityDec 09 2008Oct 01 2009A Polish group $G$ is called a group of quasi-invariance or a QI-group, if there exist a locally compact group $X$ and a probability measure $\mu$ on $X$ such that 1) there exists a continuous monomorphism of $G$ to $X$, and 2) for each $g\in X$ either ... More
The Higgs Boson Production Cross Section as a Precision Observable?Mar 06 2002Jul 30 2002We investigate what can be learned at a linear collider about the sector of electroweak symmetry breaking from a precise measurement of the Higgs boson production cross section through the process e+e- -> hZ. We focus on deviations from the Standard Model ... More
X-ray observations of cluster outskirts: current status and future prospectsMay 03 2010Dec 22 2010Past and current X-ray mission allow us to observe only a fraction of the volume occupied by the ICM. After reviewing the state of the art of cluster outskirts observations we discuss some important constraints that should be met when designing an experiment ... More
Lower and upper bounds on the mass of light quark-antiquark scalar resonance in the SVZ sum rulesMay 23 2016The calculation of the mass of light scalar isosinglet meson within the Shifman--Vainshtein--Zakharov (SVZ) sum rules is revisited. We develop simple analytical methods for estimation of hadron masses in the SVZ approach and try to reveal the origin of ... More
Low-energy holographic models for QCDFeb 01 2011Apr 09 2011We consider the bottom-up holographic models for QCD which contain the ultraviolet (UV) cutoff. Such models are supposed to describe exclusively the low-energy sector of QCD. The introduction of UV cutoff in the soft wall model is shown to result in a ... More
AdS/QCD models describing a finite number of excited mesons with Regge spectrumMar 02 2009The typical AdS/QCD models deal with the large-N_c limit of QCD, as a consequence the meson spectrum consists of the infinite number of states that is far from the real situation. Basing on introduction of anharmonic corrections to the holographic potential, ... More
Generalized Soft Wall ModelOct 18 2012Jan 27 2013We develop an exactly solvable generalization of the soft wall holographic model for the vector mesons. The generalization preserves the ultraviolet and infrared asymptotics of the soft wall model and contains an additional free parameter. This new parameter ... More
Comment on "Parity Doubling and SU(2)_L X SU(2)_R Restoration in the Hadronic Spectrum" and "Parity Doubling Among the Baryons"May 09 2006Some aspects of two recent papers on parity doubling in the hadronic spectrum and its relation to restoration of linearly realized chiral symmetry are critically discussed.
Steenrod operations and the diagonal morphismJul 04 2013Jan 15 2014We show how to find the Steenrod operations in H^*(X) (the coefficients in F_p) given the diagonal morphism d_#:S_*(X)->S_*(X^p) and the action of the cyclic group C_p on S_*(X^p). Our construction needs no other data such as Eilenberg-Zilber morphisms. ... More
The Game of Cipher BeadsMay 20 2009Jul 29 2009Comparison between the various impact factors of a few Russian journals demonstrates the deficiencies of the popular citation indices.
On Grothendieck SubspacesApr 04 2005The modulus of an order bounded functional on a Riesz space is the sum of a pair of Riesz homomorphisms if and only if the kernel of this functional is a Grothendieck subspace of the ambient Riesz space. An operator version of this fact is given.
Generalized Integral Siding Mode Manifold Design: A Sum of Squares ApproachMar 30 2015May 21 2015This paper presents a general form of integral sliding mode manifold, and proposes an algorithmic approach based on Sum of Squares (SOS) programming to design generalized integral sliding mode manifold and controller for nonlinear systems with both matched ... More
Effective Use of Human Computer Interaction in Digital Academic Supportive DevicesJan 03 2015In this research, a literature in human-computer interaction is reviewed and the technology aspect of human computer interaction related with digital academic supportive devices is also analyzed. According to all these concerns, recommendations to design ... More
Influence of Facebook in Academic Performance of Sri Lankan University StudentsJan 03 2015Facebook is only an electronic communication between human but unfortunately it has become an addiction for all. This paper examines the usage of Facebook among university students and its influence in their academic performance. The impact of Facebook ... More