Miracle-dz/UniFAR-FTUs huggingface dataset:
On the overstability of axisymmetric oscillations in thin accretion disks

We examine the stability of geometrically thin and optically thick and thin accretion disks to axisymmetric perturbations. We show that the standard . cap alpha. -disk models admit not only classical thermal and viscous instabilities, which are generally associated with regions where electron scattering and radiation pressure are dominant, but also radial pulsational instabilities. We derive a general dispersion relationship and examine the eigenvectors' response to local axisymmetric perturbations. These general results are applied for various choices of viscosity, opacity and equation of state. Our results indicate that there are pulsationally overstable regions, which are otherwise thermally and viscously stable. The underlaying physical origin and the implications of these instabilities are discussed. Finally, we speculate that quasi-periodic oscillation found in dwarf nova systems may be a manifestation of these pulsation overstabilities.
Plasmonic nanoparticles: fabrication, simulation and experiments

Some of the optical effects produced by plasmonic nanoparticles have been known since antiquity. However, the physical understanding of these properties only began in the first decade of the 20th century. The discovery of the dispersion relation of surface plasmons, almost 40 years later, unified the physical description of the plasmonic phenomena. Later, advances in nanofabrication initiated a revolution in the preparation of metallic nanostructures supporting surface plasmons. In parallel, modern electromagnetic computational methods have permitted the theoretical investigation of the optics of nanoscale and tailor plasmonic particles for experiments. A large range of applications based on the properties of surface plasmons has been recently developed, namely, strong light localization, elastic and inelastic scattering of light and interaction between optical and other physical properties of matter. In this topical review I address the preparation techniques of single plasmonic nanostructures, supported in homogeneous media or on substrates, and the study of their optical properties by experimental and theoretical methods. In the last decade new research directions were initiated towards metamaterials, nanoantennas, plasmonic trapping and heating. The study of quantum effects in plasmonic nanoparticles has attracted broad attention. A summary of the latest developments is presented.
Theoretical study of a tunable phononic band gap system

The control of acoustic-frequency gaps by altering the geometry of the system is analyzed in the particular case of a set of parallel solid square-section columns distributed in air on a square lattice. This system is shown to be sensitive enough to the rotation of the columns to be considered for practical sonic band-gap-width engineering. For different geometric configurations, specific interpretation models are used, taking into account the important mismatch of the impedance between the compounds. The accuracy of the plane-wave calculation is discussed in the different cases.
Simulation of electron diffraction patterns from III–V alloys with CuPt ordering: Effect of clusters and antiphase boundaries

A method for the simulation of electron diffraction patterns from partially ordered semiconductor compounds with CuPt-type ordering is proposed. The simulation procedure is based on the generation of two-dimensional model structures containing different types of imperfections. The defects are randomly dispersed in the structure and they are characterized by statistical parameters (density, average size, shape, etc.). Performing the intensity calculations for electron diffraction, the influence of the selected types of defects on the diffuse scattering in the transmission electron microscopy (TEM) diffraction patterns can be analyzed and the correlation between the statistical parameters describing the defects and the fine structure of the diffuse scattering can be established. By means of this method the influence of the plate-like clusters and of the antiphase boundaries (APBs) on the TEM diffraction pattern is analyzed. It is shown that the slope of the diffuse streaks around the ordering diffraction sp.
Combined electron beam imaging and ab initio modeling of T1 precipitates in Al–Li–Cu alloys

Among the many considerable challenges faced in developing a rational basis for advanced alloy design, establishing accurate atomistic models is one of the most fundamental. Here we demonstrate how advanced imaging techniques in a double-aberration-corrected transmission electron microscope, combined with ab initio modeling, have been used to determine the atomic structure of embedded 1 nm thick T1 precipitates in precipitation-hardened Al–Li–Cu aerospace alloys. The results provide an accurate determination of the controversial T1 structure, and demonstrate how next-generation techniques permit the characterization of embedded nanostructures in alloys and other nanostructured materials.
A magnetic manipulator for studying local rheology and micromechanical properties of biological systems

A magnetic micromanipulator capable of generating two‐dimensional translational and rotational motions on a microscope stage is described. With 3 μm‐diam paramagnetic beads, forces in the piconewton range and torques on the order of 10−14 N m are obtained and can be modulated in time at moderate frequencies (<5 Hz). Typical magnetic fields between 0.1 and 0.2 T, and gradients between 10 and 20 T m−1 are created by four independent feedback‐controlled electromagnets. Video microscopy and computerized image analysis are used to locate the beads on each image with a resolution of 0.1 pixel (20 nm). The device is primarily designed to study, at a microscopic scale, the local mechanical properties of biological polymers such as actin in solution, and of cell cytoplasm. Possible applications include the in situ manipulation of intracellular organelles.
Bayesian analysis of time series Poisson data

This paper provides a practical simulation-based Bayesian analysis of parameter-driven models for time series Poisson data with the AR(1) latent process. The posterior distribution is simulated by a Gibbs sampling algorithm. Full conditional posterior distributions of unknown variables in the model are given in convenient forms for the Gibbs sampling algorithm. The case with missing observations is also discussed. The methods are applied to real polio data from 1970 to 1983.
Nonparametric methods of inference for finite-state, inhomogeneous Markov processes

In some inferential problems involving Markov process data, the inhomogeneity of the process is of central interest. One example is of a binary time series of data on the presence or absence of a species at a particular site over time. Here the two states correspond to 'presence' or 'absence,' respectively, of the species, and the main topic of interest is temporal variation in the process. In principle this variation can be modelled parametrically, but in the absence of information about the physical mechanism causing species numbers to fluctuate, it is usually very difficult to suggest a plausible model that explains the data, at least until a more adaptive analysis is conducted. These issues argue in favour of nonparametric methods for estimating probabilities of transition, and for estimating probabilities of the process being in a given state at a given time. Such techniques, which in practice might be a prelude to parametric modelling, will be introduced and explored, under assumptions motivated by characteristics of the data set mentioned above. These assumptions will be shown to lead to consistent estimation of probabilities, and so to imply that nonparametric methodology gives accurate information about properties of the process.
Traffic assignment problem for a general network

A tra ns portatio n network is co ns ide red . The traffic de mands assoc iat ed wit h pairs of nodes and the (convex) trave ling cos t functions associat ed with the links a re assumed give n. The twu prob le ms of findin g the traffi c patte rn s whi c h e ither minimize the total cos t or equilibrate the use rs' cos ts are formulated , and a lgo rithms are co ns truc ted for the so lutio n of these prob lems.
Prophylactic UV Radiation and CIE Standard on Photobiological Safety of Lamps and Lamp Systems

Two aspects of UV photobiology have come up almost simultaneously for discussion. On the one hand, the CIE has, for all practical purposes, completed discussions of a new standard “CIE S 009/E: 2002 Photobiological Safety of Lamps and Lamp Systems”1), and it was adopted without any amendments. On the other hand, some national standards (for example, in Russia) have for decades insisted on UVA+UVB radiation being used for prophylactic purposes at actinic erythemal doses (around 140 J m-2 per 8 hours of irradiation), which are significantly higher than prohibitive doses of actinic UV hazard (30 J m-2) suggested in the CIE standard. It seems that this arisen situation is to be thought about more carefully.
G291.0–0.1, a centrally bright supernova remnant, in Carina

On presente de nouvelles observations de haute resolution a 843 MHz, 5 et 8,4 GHz de G291,0-0,1. La polarisation de la composante principale implique un champ magnetique ordonne aligne suivant l'axe principal. Le spectre radio est relativement plat. (Sαν −0,23 )
Flow-Induced Vibrations of Prismatic Bodies and Grids of Prisms

Abstract Flow-induced transverse, torsional, streamwise, and plunging vibrations of prismatic bodies and grids composed of prisms are reviewed for a wide range of cross-sectional shapes and angles of incidence. For flow at zero incidence, rectangular prisms are susceptible to three kinds of vortex-induced excitation, in addition to galloping and wake breathing, depending on their chord-to-thickness ratio. These include leading-edge vortex shedding (LEVS), impinging leading-edge vortices (ILEV), and trailing-edge vortex shedding (TEVS). A prism with elongated cross-section typical of elements of a trashrack or a headlight screen, which is free to vibrate in the transverse direction, may be excited by different harmonics of ILEV for incidence angles up to 13° and by alternate-edge vortex shedding (AEVS) for larger angles. Excitation by ILEV diminishes drastically with increases of the degree of turbulence in the approach flow. If a rectangular prism of elongated section has a degree of freedom in the longitudinal direction, on the other hand, it may undergo violent plunging vibrations, excited by AEVS, for incidence angles of about 13° and larger. Rounding the leading and trailing edges amplifies this excitation. As demonstrated by a practical example, serious vibrations can be avoided if the grid or trashrack is stiff enough, so that the maximum reduced velocity stays below the critical values marking the onsets of all the possible sources of excitation.
Charge separation and photovoltaic conversion in polymer composites with internal donor/acceptor heterojunctions

The photosensitivity of semiconducting polymers can be enhanced by blending donor and acceptor polymers to optimize photoinduced charge separation. We describe a novel phase‐separated polymer blend (composite) made with poly[2‐methoxy‐5‐(2′‐ethyl‐hexyloxy)‐1,4‐phenylene vinylene], MEH‐PPV, as donor and cyano‐PPV, CN‐PPV, as acceptor. The photoluminescence and electroluminescence of both component polymers are quenched in the blend, indicative of rapid and efficient separation of photogenerated electron‐hole pairs with electrons on the acceptor and holes on the donor. Diodes made with such a composite semiconducting polymer as the photosensitive medium show promising photovoltaic characteristics with carrier collection efficiency of 5% electrons/photon and energy conversion efficiency of 0.9%, ∼20 times larger than in diodes made with pure MEH‐PPV and ∼100 times larger than in diodes made with CN‐PPV. The photosensitivity and the quantum yield increase with reverse bias voltage, to 0.3 A/W and 80% electron.
NGC 2110 - An X-ray/radio galaxy with elliptical morphology

The detection of X-ray emission from NGC 2110, a narrow-emission-line galaxy of apparently elliptical morphology, is reported. A relatively hard 2-11-keV energy spectrum with an index of 0.1 + or - 0.3 is obtained, and the X-ray luminosity in this energy band is shown to be 1.2 x 10 to the 43rd erg/s for the redshift distance of 43 Mpc. Optical and radio observations are discussed which indicate a galactocentric redshift of approximately 0.0071, a resolved nonstellar optical nucleus about 4 arcsec in extent, Seyfert type 2 emission lines from the nucleus, and a nonthermal radio source located 3.0 arcsec from the position of the optical nucleus. No evidence is found for X-ray source variability in NGC 2110. It is suggested that the four to seven known X-ray-emitting high-excitation narrow-emission-line galaxies appear to be nearby examples of the Seyfert type 2 phenomenon and that the elliptical morphology of NGC 2110, if confirmed, may be unique among known Seyfert galaxies.
Structurally Stable Riemann Solutions

Abstract We study the structure of solutions of Riemann problems for systems of two conservation laws. Such a solution comprises a sequence of elementary waves, viz . , rarefaction and shock waves of various types; shock waves are required to have viscous profiles. We construct a Riemann solution by solving a system of equations characterizing its component waves. A Riemann solution is “structurally stable” if the number and types of its component waves are preserved when the initial data and the flux function are perturbed. Under the assumption that rarefaction waves and shock states lie in the stricly hyperbolic region, we characterize Riemann solutions for which the definition equations have maximal rank and we prove that such solutions are structurally stable. Structurally stable Riemann solutions cannot contain overcompressive shock waves, but they can contain transitional shock waves, including doubly sonic transitional shock waves, including doubly sonic transitional shock waves that have not been observed before.
The effect of thermal radiation on the heat transfer characteristics of lid-driven cavity with a moving surface

Purpose – There are industrial applications for varying speed lid-driven flow and heat transfer such as the float glass process where the glass film stretches or thickens depending on the desired thickness. Hence the tin cavity underneath or the nitrogen cavity above is being driven by a variable speed. The purpose of this paper is to simulate such behavior. Design/methodology/approach – Numerical solution of variable speed lid-driven cavity is carried out with thermal radiation being considered using control volume approach and staggered grid and applying the SIMPLE algorithm. Transient simulation is used for 2D model in the present study. Second order upwind schemes were used for discretization of momentum, energy equations and time. Findings – Under laminar conditions, thermal radiation plays a significant role in the heat transfer characteristics of the lid-driven cavity. This effect is more significant for blackbody radiation and decreases as the surface emissivity decreases. Nusselt number (Nu) beha.
Formation of color centers in nanodiamonds by plasma assisted diffusion of impurities from the growth substrate

A technique to create nickel-related single color centers in individual nanodiamonds is demonstrated. The method involves implantation of nickel ions into a substrate onto which the diamond nanocrystals are subsequently grown by chemical vapor deposition. The nickel is transported during the growth from the implanted substrate to the plasma and incorporates itself into the growing nanodiamonds. The nanodiamonds grown by this method reveal narrow photoluminescence peaks and proved to be single photon emitters. The results demonstrate a significant advance in the control of nickel-related color centers in diamond which are core candidates for quantum information processing.
Balancing user preferences for aircraft schedule recovery during irregular operations

In this paper, the irregular operations problem is approached for the first time in a way that allows an airline to provide for schedule recovery with minimal deviations from the original aircraft routings. A network model with side constraints is presented in which delays and cancellations are used to deal with aircraft shortages in a way that ensures a significant portion of the original aircraft routings remain intact. The model is flexible, allowing user preferences in the objective, and thereby reflecting the immediate concerns of the decision-maker in the recovery schedule. The model can be tailored by airline operations personnel to emphasize differing solution characteristics. Fleet data provided by Continental Airlines are used to demonstrate the approach. Extensive testing indicates that optimal or near-optimal solutions are routinely obtained from the LP relaxation of the network formulation. When integrality is not achieved, a rounding heuristic is provided that finds feasible solutions within a small fraction of the optimum.
New upper bounds of the Hausdorff dimensions of graphs of continuous functions

Let $f$ be a real function, continuous over ${\mathbb R}^d$, $d\geq1$, and let $\Gamma(f,D)\,{\hbox{\sun}}\,\{(x,f(x))|x\in D\}$ be its graph over a domain $D\subseteq {\mathbb R}^d$ and $\Gamma{f}$ its graph over ${\mathbb R}^d$. The question naturally arises about which (and how) smoothness properties of $f$ are related to the Hausdorff dimension of $\Gamma(f)$. It is a well-known result that if $f$ is locally $\alpha$-Hölder, which we denote by $f\in\Fspaceloc{C}{\alpha}$, for some $\alpha>0$, then $\mathrm{dim}_{\mathcal{H}}(\Gamma(f))\leq \max(d,d+1-\alpha)$. Of course, in this inequality, one can replace $\alpha$ by the Höolder exponent of $f$, i.e. by $\sup\{s:f\in\Fspaceloc{C}{s}\}$. The question of the sharpness of the obtained bound yields different outputs depending on $f$: one can show that the equality is satisfied over some classes of functions (see [5] and [1, chapter 8]) but it is not difficult to find examples for which the inequality is strict. One should also mention that in the simple case of the well-known Weierstrass function, neither the equality nor a smaller upper bound could be proved (see [11] for related results).
Monomial Realization of the Tensor Product of Crystals for Quantum Finite Algebras

In this paper, we give a combinatorial description of the crystal bases of the tensor products of the irreducible highest weight modules over quantum finite algebras in terms of Nakajima monomials. Also, we explain how to decompose the tensor product of irreducible highest weight crystals into irreducibles by giving a bijection defined by multiplication of monomials.
Phase diagram of the modified XY model

A modified two-dimensional XY model, in which the energy of the nearest-neighbour interaction is a function with two minima has been considered. The extrema of Hamiltonian have been classified and transformations to a dual model and Coulomb gas have been performed. It has been shown that a large depth of an additional minimum of the interaction function can lead to the splitting of the phase transition into two. One of them (of the Ising type) is connected with appearance of solitons of an infinite length, and the second one with dissociation of pairs of vortices with half of the circulation quantum. A corresponding phase diagram is constructed. It is proposed that recursion relations of the Migdal-Kadanoff moving bonds approximation can be modified. This new version shows the presence of a line of true fixed points in the XY model, and can be applied for studying the modification of the XY model introduced in this paper. The modified XY model can be applied for describing the behaviour of superfluid 3He thin films.
Resonant second harmonic generation of a Gaussian electromagnetic beam in a collisional magnetoplasma

Second harmonic generation of a right circularly polarized Gaussian electromagnetic beam in a magnetized plasma is investigated. The beam causes Ohmic heating of electrons and subsequent redistribution of the plasma, leading to self-defocusing. The radial density gradient, in conjunction with the oscillatory electron velocity, produces density oscillation at the wave frequency. The density oscillation beats with the oscillatory velocity to produce second harmonic current density, giving rise to resonant second harmonic radiation when the wave frequency is one-third of electron cyclotron frequency. The second harmonic field has azimuthal dependence as exp(iθ). The self-defocusing causes a reduction in the efficiency of harmonic generation.
Asymptotic form of level density distributions for a class of inhomogeneous 1D vertex models

Level density distributions for some Haldane-Shastry like spin chains associated with AN−1 root system have been computed recently by Enciso et al., using the connection of these spin chains with inhomogeneous one-dimensional vertex models. The energy functions of such vertex models are given by specific polynomials of first or second degree. Here we consider a much broader class of one-dimensional vertex models whose energy functions are given by arbitrary polynomials of any possible degree and show that the level densities for this class of vertex models asymptotically follow the Gaussian distribution for large number of vertices.
Stability and Chaos in the υ Andromedae Planetary System

The detection of three planets orbiting the star υ Andromedae marks the first discovery of a multiple-planet extrasolar system associated with a main-sequence star (Butler et al. 1999). The unusual arrangement of υ Andromedae's planetary companions immediately raises the question of long-term dynamical stability within the system. Focusing on the two outer planets, we have performed a number of extended numerical integrations that indicate that the system experiences extremely chaotic evolution for all regions of parameter space allowed by the observations. Of the three nominal sets of system parameters (reported by Butler et al. 1999), our integrations show that two of the configurations can be dynamically unstable on timescales shorter than the present age of the star. The third reported configuration (representing the nominal Lick parameters) appears to be quite stable. We conclude that there are significant regions of observationally allowed parameter space in which the outer two planets can remain on noncrossing orbits over the present 2-3 Gyr age of the system. Our results also suggest that the overall inclination for the system is likely to be quite low, and hence the objects responsible for the observed velocity signatures are almost certainly planets (rather than brown dwarfs or small stars). The system tends to favor configurations in which the two outer planets exhibit a significant relative inclination (i ≈ 15°-20°) between their two orbital planes. Dynamical studies of this type thus provide useful constraints on the observationally indeterminate properties of the system.