Search

We have tried to apply the enhanced image by a phase congruency method to the identification of coronal loop structures, and proposed a new coronal loop identification method (simply called the PCB method) based on the enhanced image by the phase congruency method. On account of the smooth morphological variation in the direction along a coronal loop, the propelling direction of coronal loop identification is restricted in a small range for improving the identified result. Beyond that, inspired by the structural characteristics of coronal loops, we firstly suggest that both the variation of propelling direction in the identification process and the magnitude of phase congruency at the identified point are simultaneously taken as the criterion to terminate the identification. Finally, several coronal images are used for testing our coronal loop identification method, and the result indicates that the enhanced image by the phase congruency method is really suitable for the coronal loop identification, and the coronal loop structures identified by the PCB method have simultaneously a good completeness and a high accuracy, hence, the PCB method is a set of practical and feasible method of automated coronal loop identification.

In this paper, the homotopy perturbation method (HPM) has been used to solve some wave equations and a few heat equations. The resultant solution helps to substantiate that HPM is a useful and robust mechanism to solve these equations. An accurate approximation is possible while solving complex and complicated problems using semi-analytical methods, an example of which is the HPM. However, we consider the boundary conditions as one-dimensional when we use this method, and hence these approximations can be considered only for a small range. HPM was developed by J. H. He for solving wave and heat equations. To obtain accurate results for these equations using HPM, standard homotopy technique is merged with the perturbation technique along with some modifications.

In this study, using the projection operator method, we investigated the influence of longitudinal optical (LO)-phonon confinement on the cyclotron resonance (CR) effect in quantum wells by calculating the expression for the absorption power. The full width at half maximum (FWHM) was obtained for the CR peaks using a computational method. The numerical results were determined for GaAs quantum wells based on three models of confined phonons delineated by Ridley, Fuchs–Kliewer, and Huang–Zhu, and for the bulk phonons. The CR absorption FWHM increased as the magnetic field and temperature increased, but decreased as the well width increased. These results are in good agreement with those obtained theoretically by Singh and Kobori et al. In addition, the CR absorption FWHM had a smaller value for the bulk phonons and it changed more slowly than that for the confined phonons. Furthermore, the CR absorption FWHM was largest for the Huang-Zhu model among the three models of confined phonons, and smallest for the Ridley model. These results are also in agreement with those obtained theoretically by Rudin et al. Weber et al., and Bhat et al. In addition, phonon confinement was determined as very important over the small range of the well width and it should be considered when investigating the CR absorption FWHM.

We have computed a grid of theoretical models to fit the twelve oscillation modes of HIP 80088 observed by K2. HIP 80088 is determined to be a pre-main sequence star, in which CN cycle has not arrived at the equilibrium state. Mass fractions of C12 and N14 in metal composition are 0.1277$^{+0.0064}_{-0.0049}$ and 0.1092$^{+0.0057}_{-0.0074}$ respectively, indicating that twenty-eight percent of C12 have turned into N14. Meanwhile, our fitting results show that physical parameters of HIP 80088 converge to a small range: $M$ = 1.68$-$1.78 $M _{\odot}$, $Z$ = 0.015$-$0.018, $\upsilon_{\rm e}$ = 120$-$136 km s$^{-1}$, $\log g$ = 4.114$-$4.125, $R$ = 1.882$-$1.914 $R_{\odot}$, $\tau_{0}$ = 7636$-$7723 s, and age = 9.03$-$10.21 Myr. Based on our model fittings, $f_{3}$ is suggested to be one radial mode, $f_{2}$, $f_{4}$, $f_{8}$, and $f_{11}$ to be four $\ell$ = 1 modes, and $f_{1}$, $f_{5}$, $f_{6}$, $f_{7}$, $f_{9}$, $f_{10}$, and $f_{12}$ to be seven $\ell$ = 2 modes. In particularly, we find that ($f_{2}$, $f_{4}$, $f_{8}$) form one complete triplet with the averaged frequency spacing of 16.045 $\mu$Hz , and ($f_{5}$, $f_{7}$, $f_{9}$, $f_{10}$) form four components of one quintuplet with the averaged frequency spacing of 13.388 $\mu$Hz. The two averaged frequency spacings are not equal. Based on the best-fitting model, those $\ell$ = 2 modes of HIP 80088 are found to be mixed modes, which are p-dominated modes with pronounced g-mode features, while oscillation modes with $\ell$ = 1 are p modes., Comment: 11 pages,6 figures,6 Tables.accepted for publication in ApJ

High-quality X-ray observations of planetary nebulae (PNe) have demonstrated that the X-ray-emitting gas in their hot bubbles have temperatures in the small range TX = (1 &minus, 3) &times, 106 K. However, according to theoretical expectations, adiabatically-shocked wind-blown bubbles should have temperatures up to two orders of magnitude higher. Numerical simulations show that instabilities at the interface between the hot bubble and the nebular material form clumps and filaments that generate an intermediate-temperature turbulent mixing layer. We describe the X-ray properties resulting from simulations of PNe in our Galaxy and the Magellanic Clouds.

We investigate the influence of phonon confinement on the optically detected magneto-phonon resonance (ODMPR) effect and ODMPR line-width in quantum wells. The ODMPR conditions as functions of the well's width and the photon energy are also obtained. The shifts of ODMPR peaks caused by the confined phonon are discussed. The numerical result for the GaAs/AlAs quantum well shows that in the two cases of confined and bulk phonons, the line-width (LW) decreases with increasing well's width and increases with increasing temperature. Furthermore, in the small range of the well's width, the influence of phonon confinement plays an important role and cannot be neglected in reaching the ODMPR line-width.

In isochronous mass spectrometry (IMS) established in heavy-ion storage rings the revolution times of the stored secondary ions should be independent of their velocity spread. However, this isochronous condition is fulfilled only in first order and in a small range of revolution times. To correct for the non-isochronicity an additional measure of the velocity or magnetic rigidity of each stored ion is required. For this purpose two new time-of-flight (TOF) detectors were installed in a straight section of the experimental Cooler Storage Ring CSRe in Lanzhou. The performance of the new time-of-flight (TOF) detectors, which is crucial for the achievable efficiencies and mass resolving power, was significantly improved. The time resolution of the TOF detector in offline tests was σ = 18.5 ± 2 ps . The detector setup was put into operation with a stable beam of 78Kr.

Submerged floating tunnel (SFT) is a novel type traffic structure for crossing the long straits. To analyze the vehicle-tunnel coupled vibration of SFT due to tether parametric excitation, Hamilton principle and D'Alembert's principle are applied to establish the theoretical model. The fourth order Runge-Kutta method is carried out to calculate the responses of the system. The proposed model is verified by the beam on the elastic foundation (BOEF) model without considering tether parametric excitation, and the relative difference is less than 2%. If the initial excitation can be controlled in a small range, the influence of the tether vibration on the vehicle-coupled vibration can be efficiently reduced. Meantime, the effects of some factors, such as the gravity-buoyance ratio (GBR), the inclined angle of the tether (IAT), and the vehicle velocity on the dynamic response are discussed. The results show that the dynamic amplification factors (DAFs) of the deflection and the bending moment decrease with the GBR increasing. Besides, the larger IAT results in larger tether tension fluctuation when the vehicle-tunnel coupled vibration of the SFT subjected to tether parametric excitation. And the slower vehicle is more affected by the tether vibration when the vehicle drives in the tunnel.

The basic principle of the tempo-spatially modulated polarization interference imaging spectrometer (TSMPIIS) is expounded in this paper. Using the electric vector method, the exact expression of TSMPIIS's optical throughput changing with the incident angle i , the polarized orientation angles θ and ϕ , together with the transmittances T oe and T eo is calculated. Furthermore, the effects of various parameters on the optical throughput are analyzed and discussed by computer simulations, and some important conclusions are obtained. In order to obtain a high value of the optical throughput, the incident angle is controlled in a small range, and the optimal values of the polarized orientation angles θ and ϕ are chosen as 0°. This work provides a theoretical and practical guidance for improving the optical throughput of the tempo-spatially modulated polarization interference imaging spectrometer along with its engineering realization.

We investigate the influence of phonon confinement on the optically-detected electrophonon resonance (ODEPR) effect and ODEPR linewidth in rectangular quantum wires (RQW). The ODEPR conditions as functions of the wire’s size and the photon energy are also obtained. The splittings of ODEPR peaks caused by the confined phonon are discussed. The numerical result for a specific RQW shows that in the two cases of confined and bulk phonons, the linewidth decreases with increasing wire size and increases with increasing temperature. Furthermore, in the small range of the wire’s size (L ≤ 40 nm), phonon confinement plays an important role and cannot be neglected in reaching the ODEPR linewidth.

A possibility to control an optical soliton by a much weaker second pulse that is scattered on the soliton attracted considerable attention recently. An important problem here is to quantify the small range of parameters at which the interaction takes place. This has been achived by using adiabatic ODEs for the soliton characteristics, which is much faster than a scan of the full propagation equations for all parameters in question.

Inter-satellite link (ISL) is a system of several satellites, which encircle the earth and spaced at a fixed distance from each other - of about 3000 kilometers. The optical-mechanical module (MOM) for the ISL is designed to transmit data over long distances in a small range of angles.

Coupled trajectory and attitude stability of displaced solar orbits is studied by using sailcraft with a kind of two-folding construction with two unequal rectangular plates forming a right angle. Three-dimensional coupled trajectory and attitude equations are developed for the coupled dynamical system, and the results show that all three types of displaced solar orbits widely referenced can be achieved through selecting an appropriate size of the two-folding sail. An analysis of the corresponding linear stability of the trajectory and attitude coupled system is carried out, and both trajectory and attitude linearly stable orbits are found to exist in a small range of parameters, whose non-linear stability is then examined via numerical simulations. Finally, passively stable orbits are found to have weak stability, and such passive means of station-keeping are attractive and useful in practice because of its simplicity.

Determination of the acceleration of the dynamic microobjects movement, the motion of which is accelerated uniformly or non-uniformly is an important task in television measuring systems. Most of existing measurement systems usually have a small range of determination of the acceleration with a short period of growth.

There are many published values for the pitch angle of individual spiral arms, and their wide distribution (from -3 to -28 degrees) begs for various attempts for a single value. Each of the four statistical methods used here yields a mean pitch angle in a small range, between -12 and -14 degrees (table 7, figure 2). The final result of our meta-analysis yields a mean global pitch angle in the Milky Way's spiral arms of -13.1 degrees, plus or minus 0.6 degree., 18 pages; 2 figures, 7 tables, 1 appendix; accepted on 2015 April 14, by Monthly Notices of the Royal Astronomical Society (in press)

The negative and positive Goos-H\"anchen (GH) shifts in reflected light are revisited for a partial coherent light incident on a cavity. A three-level dilute gaseous atomic medium, which follows two-photon Raman transitions, is considered in a cavity. The anomalous (negative group index) and normal (positive group index) dispersions of the intracavity medium lead to negative and positive GH shifts, respectively. The effects of beam width, spatial coherence, and mode index of partial coherent light fields are studied on the negative and positive GH shifts. It is observed that the amplitude of negative and positive GH shifts are relatively large for a small range of beam width and for a small value of spatial coherence of partial coherent light beams. The amplitude of GH shifts becomes small for large beam width and spatial coherence of incident light. Further, the distortion in the reflected light field increases when the amplitude of the GH shifts increases and vice versa.

A binary in which a slightly evolved star starts mass transfer to a neutron star can evolve towards ultra-short orbital periods under the influence of magnetic braking. This is called magnetic capture. In a previous paper we showed that ultra-short periods are only reached for an extremely small range of initial binary parameters, in particular orbital period and donor mass. Our conclusion was based on one specific choice for the law of magnetic braking, and for the loss of mass and angular momentum during mass transfer. In this paper we show that for less efficient magnetic braking it is impossible to evolve to ultra-short periods, independent of the amount of mass and associated angular momentum lost from the binary., 7 pages, 7 figures, accepted for publication in Astronomy and Astrophysics. See http://www.astro.uu.nl/~sluys/PhD/

Analytic expressions for the demagnetizing energies are obtained in the form of partial series, for long elliptic cylinders and for squat ones where the ellipticity of the cross-section is unrestrained. This leaves just a small range where the demagnetizing energies are not well defined. It is found that by replacing the elliptic cylinders with rectangular blocks, a good approximation to the demagnetizing energy may be made in this small range.

We present optical spectroscopic observations of 93 galaxies taken from the infra-red selected COLA (Compact Objects in Low Power AGN) sample. The sample spans the range of far-IR luminosities from normal galaxies to LIRGs. Of the galaxies observed, 78 (84%) exhibit emission lines. Using a theoretically-based optical emission-line scheme we classify 15% of the emission-line galaxies as Seyferts, 77% as starbursts, and the rest are either borderline AGN/starburst or show ambiguous characteristics. We find little evidence for an increase in the fraction of AGN in the sample as a function of far-IR luminosity but our sample covers only a small range in infrared luminosity and thus a weak trend may be masked. As a whole the Seyfert galaxies exhibit a small, but significant, radio excess on the radio-FIR correlation compared to the galaxies classified as starbursts. Compact (, 24 pages, 4 figures, 6 tables. Accepted for publication in ApJ, February 2003

This study assessed the accuracy of an electronic hinge axis tracing device (Cadiax compact) in measuring the horizontal condylar inclination (HCI) and the Bennett angle. The hinge axis movements were simulated with an articulator to which the hinge axis tracer was attached. On the articulator the pre-set HCI values were 20 degrees, 40 degrees and 60 degrees, the pre-set Bennett angles were 0 degrees, 5 degrees, 10 degrees, 15 degrees, 20 degrees. The maximum measuring errors ranged from 0 to 3.4 degrees (in average 1.2 degrees ) and yielded statistically significant differences between articulator setting and Cadiax compact measurement (P < 0.05) except the HCI of 40 degrees and the Bennett angle of 0 degrees. Because of the small range of the maximum measuring error the Cadiax compact represented reasonable accuracy for clinical application in anterior guidance restorations.

An analysis of Hp photometry of DK Virginis is carried out. The analysis reveals two frequencies, and cycles day~1. These values turn out to be good enough to bridge the f 1 \ 9.2095 f 2 \ 7.5764 gap between the two available series of ground-based data, obtained in 1973 and 1980, so that the fre- quencies can be reÐned. The reÐned values are equal to 9.20945 and 7.57641 cycles day~1. The correspond- ing V amplitudes amount to 8.6 ^ 0.4 and 11.1 ^ 0.4 mmag, and the epochs of maximum light are equal to 2,441,715.0294 ^ 0.0008 and 2,441,715.1205 ^ 0.0007. The synthetic light curve, computed with these JD _ parameters, correctly reproduces the large light range on JD 2,439,177, the night in 1966 when the star was discovered to be variable, and the small range on JD 2,440,682, when the light variation was not detected. In this way, all photometric observations of DK Vir are accounted for, indicating that the two frequencies have not changed appreciably since 1965, and that the V amplitudes were constant over the interval from 1965 to 1980. Using a photometric e†ective temperature and Hipparcos parallax, we plot the star in the H-R diagram. Comparison with evolutionary tracks then shows that DK Vir is at the end of the main-sequence stage of its evolution or slightly beyond, with a mass of 2.1 or somewhat smaller. Finally, an examination of linear M _ nonadiabatic pulsation frequencies of modes with l ¹ 2 indicates that the two observed modes cannot both be radial, and that the mode must be nonradial if the star is still on the main sequence. f 1 The properties of the Hipparcos spectral window are examined in the Appendix.

By introducing a new parameter, slowness deviation, a ray-path-length-dependent slowness model has been previously developed. Synthetic tests indicate that for a horizontal layered slowness structure, the new model gives a good estimate of the weighted average slowness of a ray when the rays considered cover a small range of take-off angles. When the rays considered cover a large range of take-off angles, the new model gives good estimates of the weighted average slowness for the long rays, but large errors still remain for the short rays.

The attractor basin is studied when correlations (symmetries) in the interaction are imposed for diluted Gardner-Derrida neural network. A clear relation between the attractor basin and the symmetry is obtained in a small range of symmetry parameter. The size of the attractor basin is smaller than that in the case without imposed correlations. For special values of the symmetry parameter the model leads to results obtained in the model with no correlations.

Contains fulltext : 168262.pdf (Publisher’s version ) (Open Access) The variability in the numerous tasks in which we use our hands is very large. However, independent movement control of individual fingers is limited. To assess the extent of finger independency during full-range finger flexion including all finger joints, we studied enslaving (movement in non-instructed fingers) and range of independent finger movement through the whole finger flexion trajectory in single and multi-finger movement tasks. Thirteen young healthy subjects performed single- and multi-finger movement tasks under two conditions: active flexion through the full range of movement with all fingers free to move and active flexion while the non-instructed finger(s) were restrained. Finger kinematics were measured using inertial sensors (PowerGlove), to assess enslaving and range of independent finger movement. Although all fingers showed enslaving movement to some extent, highest enslaving was found in adjacent fingers. Enslaving effects in ring and little finger were increased with movement of additional, non-adjacent fingers. The middle finger was the only finger affected by restriction in movement of non-instructed fingers. Each finger showed a range of independent movement before the non-instructed fingers started to move, which was largest for the index finger. The start of enslaving was asymmetrical for adjacent fingers. Little finger enslaving movement was affected by multi-finger movement. We conclude that no finger can move independently through the full range of finger flexion, although some degree of full independence is present for smaller movements. This range of independent movement is asymmetric and variable between fingers and between subjects. The presented results provide insight into the role of finger independency for different types of tasks and populations.

We investigate the influence of phonon confinement on the optically detected electrophonon resonance (ODEPR) effect and ODEPR line-width in quantum wells. The obtained numerical result for the GaAs/AlAs quantum well shows that the ODEPR line-widths depend on the well's width and temperature. Besides, in the two cases of confined and bulk phonons, the linewidth (LW) decreases with the increase of well's width and increases with the increase of temperature. Furthermore, in the small range of the well's width, the influence of phonon confinement plays an important role and cannot be neglected in considering the ODEPR line-width.

Shape coexistence, where different deformed minima compete within a small range of excitation energy, appears to be ubiquitous across the chart of nuclides. In many light alpha-conjugate nuclei, experimental data points to the coexistence of highly deformed nuclear configurations. It has long been suggested, with strong theoretical justification, that these deformed states are attributable to nuclear clustering based on building blocks of alpha particles. This short review will consider how well alpha clustering fits within the shape coexistence canon and point to future opportunities for experiments that can place the topic on a firmer footing.

We present detailed chemical abundances for $>$20 elements in $\sim$30 globular clusters in M31. These results have been obtained using high resolution ($\lambda/\Delta\lambda\sim$24,000) spectra of their integrated light and analyzed using our original method. The globular clusters have galactocentric radii between 2.5 kpc and 117 kpc, and therefore provide abundance patterns for different phases of galaxy formation recorded in the inner and outer halo of M31. We find that the clusters in our survey have a range in metallicity of $-2.2$20 kpc have a small range in abundance of [Fe/H]$=-1.6 \pm 0.10$. We also measure abundances of alpha, r- and s-process elements. These results constitute the first abundance pattern constraints for old populations in M31 that are comparable to those known for the Milky Way halo., Comment: XII International Symposium on Nuclei in the Cosmos August 5-12, 2012 Cairns, Australia. To appear in Proceedings of Science

We report on our recent study of Cold Nuclear Matter effects on the Upsilon production at RHIC in dAu collisions. The first experimental results available on the nuclear modification factor R_dAu have rather large uncertainties. They nevertheless allow to bring qualitative information on the nature of the nuclear effects at play on top of the usual nuclear absorption, since the latter is expected to lie in a quite small range around a value close to ten times smaller as for charmonia. At backward rapidities, the behavior of R_dAu hints at the presence of a gluon EMC effect, analogous to the quark EMC effect -- but possibly stronger. Mid rapidity measurements with a better precision are highly desirable to pin down the gluon anti-shadowing, still under debate. At forward rapidities, the data leave some room for an additional fractional energy loss mechanism, recently revived in the literature., 6 pages, 4 figures, Proceedings for the Sixth International Conference on Quarks and Nuclear Physics QNP2012 (April 2012, Ecole Polytechnique, Palaiseau, Paris France)

In this paper, we study the sensitivity of the fraction of $t\bar{t}$ events arising from gluon-gluon fusion to the chromoelectric and chromomagnetic dipole moments (CEDM and CMDM) as well as the total and differential $t\bar{t}$ cross sections at the LHC and Tevatron. The sensitivity of measured charged asymmetry at the LHC to CEDM and CMDM is also studied. We find that at the Tevatron and the LHC, non-zero values of CMDM could suppress the $t\bar{t}$ production rate. It is shown that the ratio of $\sigma(gg\rightarrow t\bar{t})/\sigma(p\bar{p}\rightarrow t\bar{t})$ at the Tevatron is more sensitive to CEDM and CMDM than the LHC case. The presence of CEDM always increases the contribution of gluon-gluon fusion process in top pair rate at the Tevatron and LHC. Except for a small range of CMDM, the presence of CEDM and CMDM can increase the fraction of gluon-gluon fusion at the Tevatron and LHC. The measured ratio of $\sigma(gg\rightarrow t\bar{t})/\sigma(p\bar{p}\rightarrow t\bar{t})$ at the Tevatron is used to derive bounds on the chromoelectric and chromomagnetic dipole moments as well as the total and differential ($d\sigma/dm_{t\bar{t}}$) cross sections at the LHC and Tevatron, and the measured charged asymmetry at the LHC. The combination of $d\sigma_{TeV}/dm_{t\bar{t}}$ and $\sigma_{LHC}$ provides stringent limits on CMDM and CEDM., Comment: 11 pages,6 figures,2 tables

The brightest planetary nebulae achieve similar maximum luminosities, have similar ratios of chemcial abundances, and apparently share similar kinematics in all galaxies. These similarities, however, are not necessarily expected theoretically and appear to hide important evolutionary differences. As predicted theoretically, metallicity appears to affect nebular kinematics, if subtly, and there is a clear variation with evolutionary stage. To the extent that it can be investigated, the internal kinematics for galactic and extragalactic planetary nebulae are similar. The extragalactic planetary nebulae for which kinematic data exist, though, probably pertain to a small range of progenitor masses, so there may still be much left to learn, particularly concerning the kinematics of planetary nebulae that descend from the more massive progenitors., Comment: Invited Review, IAU Symp. 283, Planetary Nebulae: An Eye to the Future

Restrictions on Yukawa-type hypothetical forces with extremely small range of action are obtained from London force measurements and from spectroscopy of exotic atoms. A new experiment for measuring the attractive force in atomic force microscopy is shown to promise the strengthening of the restrictions obtained up to date by 200 times within the range 1 A .

This article is concerned with the fundamental frequency of vibrating beams carrying a concentrated mass at various locations. An equivalent-center method for obtaining the frequencies of the loaded beams has been presented. The generated design curves can be used generally for beams with different boundary conditions by introducing the dimensionless parameters. Results show that the equivalent-center weight and frequency factors are to evaluate effectively and quickly the fundamental frequency of a beam carrying a mass at various locations through merely the frequency of the center-loaded beam. The weight factor further facilitates the process since only a small range of frequencies is required.

Time domain reflectometry (TDR) technology is an ideal cable length measurement method. The traveling wave propagation velocity is the key to the measuring accuracy of the TDR cable length measurement system. The cable crimp levels effect on traveling wave propagation velocity is analyzed theoretically, and the corresponding experiment is done. The experimental results are match to the theoretical analysis. The experimental results show that the law of the traveling wave propagation velocity influenced by cable crimp levels is different for different types of cable, however, as long as the cable state under test is uniformed, the velocity error can be controlled in a small range. Therefore the measuring accuracy of the TDR cable length measurement system is ensured.

An analysis of the effects of detuning and the superposition angle on amplitude-squared (AS) squeezing is presented for the one- and two-photon Jaynes-Cummings model (JCM) using coherent and squeeze inputs. In the one-photon JCM for squeezed inputs, it is shown that the degree of AS squeezing increases as the detuning increases. The two-photon JCM, on the other hand, displays this characteristic only for coherent input in a small range of values of the detuning. The superposition angle affects the degree of AS squeezing more significantly for a detuned field than for a tuned one

The known intervals of possible stability, on the mgr-axis, of basicfamilies of 3D periodic orbits in the restricted three-body problem areextended into μ-A1 regions for oblate larger primary, A1 beingthe oblateness coefficient. Eight regions, corresponding to the basicstable bifurcation orbits l1v, l′1v, l2v, l3v, m1v, m′1v,m2v, i1v are determined and related branching 3D periodic orbits arecomputed systematically and tested for stability. The regions for l1v,m1v and m2v survive the test emerging as the regions allowing thesimplest types of stable low inclination 3D motion. For l′1v, l2v,l3v, m′1v and m2v oblateness seems to have a stabilising effect,while stability of i1v survives only for a very small range of A1values.

The field-driven domain-wall dynamics in magnetic nanostripes under the influence of transverse fields was examined experimentally and by numerical simulations. For a small range of transverse fields in a regime below the Walker field an unexpected instantaneous change in the domain-wall velocity was found. Micromagnetic simulations have shown that this peculiar behavior is caused by a transformation of the moving asymmetric transverse wall: the wall is stretched along the nanostripe due to different velocities of the upper and lower half antivortices constituting the domain wall.

Many marine animals cruise efficiently within a small range of propulsive Strouhal numbers. More recently it has been proposed that optimal vortex formation is the underlying principle to this universal Strouhal number constraint. The computational fluid dynamics technique known as Smoothed Particle Hydrodynamics (SPH) is used to study the propulsion of high speed marine animals – the Bottlenose Dolphin and the White Pointer Shark. The thrust generation and corresponding vortical flow structures are considered in detail over a range of Strouhal numbers.

We examine the dynamics of neutral black rings, and identify and analyze a selection of possible instabilities. We find the dominating forces of very thin black rings to be a Newtonian competition between a string-like tension and a centrifugal force. We study in detail the radial balance of forces in black rings, and find evidence that all fat black rings are unstable to radial perturbations, while thin black rings are radially stable. Most thin black rings, if not all of them, also likely suffer from Gregory-Laflamme instabilities. We also study simple models for stability against emission/absorption of massless particles. Our results point to the conclusion that most neutral black rings suffer from classical dynamical instabilities, but there may still exist a small range of parameters where thin black rings are stable. We also discuss the absence of regular real Euclidean sections of black rings, and thermodynamics in the grand-canonical ensemble., 39 pages, 17 figures; v2: conclusions concerning radial stability corrected + new appendix + refs added; v3: additional comments regarding stability

The validity of the concept of ``hard-sphere-like'' particles for mixtures of colloids is questioned from a theoretical point of view. This concerns the class of pseudobinary mixtures in which the nonsteric interactions between the colloids are ``residual'' (with very small range and moderate strength). It is shown that contrary to common expectation, such interactions may have unexpected consequences on the theoretical phase diagram. The distinction between this situation and true solute-solvent mixtures is emphasized.

We present H-alpha line-profile analyses for the seven SU UMa type dwarf novae AK Cnc, WX Cet, AQ Eri, VW Hyi, RZ Leo, TU Men, and HS Vir. All data sets are treated in the same manner, applying a sequence of techniques for each system. The basic ingredients of this sequence are the diagnostic diagram to determine the zero point of the orbital phase, and Doppler tomography to visualise the emission distribution. We furthermore introduce a new qualitative way of to evaluate the Doppler fit, by comparing the line profile of the reconstructed with the original spectrum in the form of the V/R plot. We present the results of the analysis in the compact form of an atlas, allowing a direct comparison of the emission distribution in our targets. Although most of the data sets were not taken with the intention of a line-profile analysis, we obtain significant results and are able to indicate the type of the additional emission in these systems. Our objects should have in principle very similar physical properties, i.e. they cover only a small range in orbital periods, mass ratios, and mass-transfer rates. Nevertheless, we find a large variety of phenomena both with respect to the individual systems and also within individual data sets of the same object. This includes `canonical' additional emission components from the secondary star and the bright spot, but also emission from the leading side of the accretion disc., 20 pages, 25 figures, accepted for publication in A&A, figures have been diminished in size and quality

We study the correlation between the speed of two-ribbon separation and the magnetic flux density during the 2001 April 10 solar flare. A weak negative correlation is found between the ribbon separation speed (Vr) and the longitudinal magnetic flux density (Bz). In addition, we estimate the magnetic reconnection rate (Erec). Along the flare ribbons, Erec fluctuates in the small range except near the HXR source. The localized enhancement of the reconnection rate corresponds to the position of the HXR source.

We study the stress response to a steady imposed shear rate in a concentrated suspension of colloidal particles. We show that, in a small range of concentrations and shear rates, stress exhibits giant fluctuations. The amplitude of these fluctuations obeys a power-law behavior, up to the apparition of a new branch of flow, leading to an excess of high amplitude fluctuations which exhibit a well-defined periodicity.

We investigate the role of the interparticle-interaction strength in the distribution of two species of atoms inside a condensate. We focus upon the study of systems for which the minima of the trapping potentials for the species are displaced from each other by a distance that is small compared to the size of the total condensate. We show that in a small range of the interparticle-interaction strength the distribution of species undergoes dramatic changes, and exhibits a variety of different features. We demonstrate that this behavior can be easily understood in terms of the Thomas-Fermi approximation. This effect may be useful in experimentally determining the values of the scattering lengths., Comment: 4 pages, 2 figures, revtex4

MKN 421, repeatedly monitored with BeppoSAX in 1997–2000, showed recurrent ∼1 day duration flares with quasi-symmetric profiles. We show here the most important results of our comprehensive temporal analysis aiming at quantifying time lags between low and high energy photons. Interestingly, time lags were detected in each isolated flare, and constrained to a small range from flare to flare (∼1 hour between the 0.1–1.5 keV and the 3.5–10 keV bands) with various attributes: soft lags, hard lags or zero lags, but no correlation between time lags and flare intensities was found. To account for variable time lags, relative changes of values in the dominant time scales involved in the emitting region must occur in order to produce a variety of complex energy-dependent variability behaviors. The energy-dependence of time lags was well determined for the flares in which a large enough time lags is detected, from which magnetic fields have been constrained to be 0.15–3.0 Gauss (assuming Doppler factor δ=20), if so...

We use the single-histogram technique to study the critical behavior of the three-state Potts model on a (random) Voronoi-Delaunay lattice with size ranging from 250 to 8000 sites. We consider the effect of an exponential decay of the interactions with the distance,$J(r)=J_0\exp(-ar)$, with $a>0$, and observe that this system seems to have critical exponents $\gamma$ and $\nu$ which are different from the respective exponents of the three-state Potts model on a regular square lattice. However, the ratio $\gamma/\nu$ remains essentially the same. We find numerical evidences (although not conclusive, due to the small range of system size) that the specific heat on this random system behaves as a power-law for $a=0$ and as a logarithmic divergence for $a=0.5$ and $a=1.0$, Comment: 3 pages, 5 figures

A new determination of WFPC2 photometric corrections is presented, using HSTphot reduction of the WFPC2 Omega Centauri and NGC 2419 observations from January 1994 through March 2000 and a comparison with ground-based photometry. No evidence is seen for any position-independent photometric offsets (the "long-short anomaly"); all systematic errors appear to be corrected with the CTE and zero point solution. The CTE loss time dependence is determined to be very significant in the Y direction, causing time-independent CTE solutions (Stetson 1998; Saha, Lambert, & Prosser 2000) to be valid only for a small range of times. On average, the present solution produces corrections similar to Whitmore, Heyer, & Casertano (1999), although with an improved functional form that produces less scatter in the residuals and determined with roughly a year of additional data. In addition to the CTE loss characterization, zero point corrections are also determined as functions of chip, gain, filter, and temperature. Of interest, there are chip-to-chip differences of order 0.01-0.02 magnitudes relative to the Holtzman et al. (1995) calibrations, and the present study provides empirical zero point determinations for the non-standard filters such as the frequently-used F450W, F606W, and F702W., 30 pages, 10 figures Accepted for publication in October 2000 PASP

The coefficient of restitution e is usually defined as an empirically determined constant of proportionality that relates normal components of incident and rebound relative velocity for contact points CPi of colliding rigid bodies. Assuming that e represents inelastic behavior, this definition results in calculated kinetic energy increases during eccentric (noncollinear) collisions for some conditions of contact point slip. These paradoxical energy increases arise only in noncollinear collisions where slip at CPi is opposed by friction. In this case e must also depend on the slip process and friction, but then the ‘‘impact law’’ is valid for only a vanishingly small range of incident velocities. To resolve this paradox, we propose a new definition where e is independent of friction; thence e specifically represents internal dissipation by irreversible deformation processes. This definition clearly separates frictional and nonfrictional sources of energy dissipation. The two definitions are only equivalent in the case of nonfrictional or central (collinear) collisions.

We construct an effective three dimensional theory for the MSSM at high temperatures in the limit of large-$m_{A}$. We analyse the two-loop effective potential of the 3D theory for the case of a light right handed stop to determine the precise region in the $m_{h}$-$m_{\tilde{t}_{R}}$ plane for which the sphaleron constraint for preservation of the baryon asymmetry is satisfied. We also compare with results previously obtained usind 3D and 4D calculations of the effective potential. A two-stage phase transition still persists for a small range of values of $m_{\tilde{t}_{R}}$. The allowed region requires a value of $m_{\tilde{t}_{R}} \lsi m_{t}$ and $m_{h} \lsi 100$ (110) GeV for $m_{Q} = 300$ GeV (1 TeV)., 40 pages, 6 Postcsript figures, uses epsf