Presence Of Warping Research Articles

Entanglement entropy in internal spaces and Ryu-Takayanagi surfaces

We study minimum area surfaces associated with a region, R, of an internal space. For example, for a warped product involving an asymptotically AdS space and an internal space K, the region R lies in K and the surface ends on ∂R. We find that the result of Graham and Karch can be avoided in the presence of warping, and such surfaces can sometimes exist for a general region R. When such a warped product geometry arises in the IR from a higher dimensional asymptotic AdS, we argue that the area of the surface can be related to the entropy arising from entanglement of internal degrees of freedom of the boundary theory. We study several examples, including warped or direct products involving AdS2, or higher dimensional AdS spaces, with the internal space, K = Rm, Sm; Dp brane geometries and their near horizon limits; and several geometries with a UV cut-off. We find that such RT surfaces often exist and can be useful probes of the system, revealing information about finite length correlations, thermodynamics and entanglement. We also make some preliminary observations about the role such surfaces can play in bulk reconstruction, and their relation to subalgebras of observables in the boundary theory.

Nonlinear Hall effect in topological insulator Bi2Te3 with hexagonal warping

A new addition to the family of Hall effects is the nonlinear Hall effect. We investigate the role of hexagonal warping of the band structure of surface Dirac fermions in the nonlinear Hall effect in 3D topological insulators. Most relevant to our study is Bi2Te3, where we show that its surface states exhibit pronounced nonlinear Hall effect in the presence of warping. We investigate this nonlinear Hall effect as a function of Fermi energy, bandgap, warping strength, and temperature.

Identification warp and flare milky way’s disk in the third galactic quadrant

Milky Way’s disk has a feature called warp and flare. Warp is a bending phenomenon of the galactic disk. This feature is noticeable in the first and third galactic quadrant. Meanwhile, flare define as the increment of galactic disk scale high depends on galactocentric distance. Galactic disk tracers (dust, gaseous, and stars) can be used to explain the presence of both structures. The reddening of 10 young open clusters (OC) and 2985 early-type (OB) stars chosen in this work. Both components predicted to represent the galactic disk component where the warp and flare occurred. The Milky Way Star Cluster (MWSC) catalogue used to select the open clusters initial parameters. Then, we used proper motion data from GAIA DR2 combined with photometric data from Two Micron All Sky Survey (2MASS) catalogue to determine the open cluster membership and reddening. The open cluster memberships are selected using scatter algorithm. Then, the JHKs photometric data used to build the Two Colour Diagram (TCD) and Colour-Magnitude Diagram (CMD). We selected the reddening of OB stars data from Tycho 2 catalogue. The result is an increment of colour excess depends on galactocentric distance. This distribution could indicate the presence of warp and flare of the Milky Way’s disk.

A novel 3D technique to study the kinematics of lensed galaxies

We present a 3D Bayesian method to model the kinematics of strongly lensed galaxies from spatially-resolved emission-line observations. This technique enables us to simultaneously recover the lens-mass distribution and the source kinematics directly from the 3D data cube. We have tested this new method with simulated OSIRIS observations for nine star-forming lensed galaxies with different kinematic properties. The simulated rotation curves span a range of shapes which are prototypes of different morphological galaxy types, from dwarf to massive spiral galaxies. We have found that the median relative accuracy on the inferred lens and kinematic parameters are at the level of 1 and 2 per cent, respectively. We have also tested the robustness of the technique against different inclination angles, signal-to-noise ratios, the presence of warps or non-circular motions and we have found that the accuracy stays within a few per cent in most cases. This technique represents a significant step forward with respect to the methods used until now, as the lens parameters and the kinematics of the source are derived from the same 3D data. This enables us to study the possible degeneracies between the two and estimate the uncertainties on all model parameters consistently.

Observational signatures of linear warps in circumbinary discs

In recent years an increasing number of observational studies have hinted at the presence of warps in protoplanetary discs, however a general comprehensive description of observational diagnostics of warped discs was missing. We performed a series of 3D SPH hydrodynamic simulations and combined them with 3D radiative transfer calculations to study the observability of warps in circumbinary discs, whose plane is misaligned with respect to the orbital plane of the central binary. Our numerical hydrodynamic simulations confirm previous analytical results on the dependence of the warp structure on the viscosity and the initial misalignment between the binary and the disc. To study the observational signatures of warps we calculate images in the continuum at near-infrared and sub-millimetre wavelengths and in the pure rotational transition of CO in the sub-millimetre. Warped circumbinary discs show surface brightness asymmetry in near-infrared scattered light images as well as in optically thick gas lines at sub-millimetre wavelengths. The asymmetry is caused by self-shadowing of the disc by the inner warped regions, thus the strength of the asymmetry depends on the strength of the warp. The projected velocity field, derived from line observations, shows characteristic deviations, twists and a change in the slope of the rotation curve, from that of an unperturbed disc. In extreme cases even the direction of rotation appears to change in the disc inwards of a characteristic radius. The strength of the kinematical signatures of warps decreases with increasing inclination. The strength of all warp signatures decreases with decreasing viscosity.

The shape of dark matter haloes – III. Kinematics and structure of the H i disc

We present a new strategy for fitting the structure and kinematics of the HI in edge-on galaxies using a fit to the terminal-velocity channel maps of a HI data cube. The strategy can deal with self-absorbing HI gas and the presence of warps. The method is first tested on a series of models. We demonstrate that fitting optically thin models to real galaxies will lead to an overestimation of the thickness and velocity dispersion, and to a serious underestimation of the HI face-on column densities. We subsequently fit both self-absorption and optically thin models to the HI data of six edge-on galaxies. In three of these we have also measured the velocity dispersion. On average 27 \pm 6 % of the total HI mass of edge-on galaxies is hidden by self-absorption. This implies that the HI mass, thickness and velocity dispersion of galaxies is typically underestimated in the literature.

Simplified Approaches to Design Medium-Rise Unbraced Steel Storage Pallet Racks. II: Fundamental Period Estimates

Abstract This paper concludes a two-part paper, which addresses the reliability of simplified approaches for rack design. The first part presents a parametric study on medium-rise, unbraced racks differing for components, geometry, and flexural stiffness degree of beam-to-column joints and base-plate connections. The evaluation of the elastic critical load multiplier, which is required to select the analysis method and check member instability, is considered through a simplified approach that is adequately calibrated for the more traditional steel structures. This second part focuses on seismic design, which is governed by the value of the fundamental period of vibrations (T1). Simplified approaches from the literature on typical steel frames and recommendations to predict period T1 are applied to two beam formulations differing in the absence or presence of warping. Research outcomes are discussed, considering the limits of the simplified approaches, and improvements to increase the accuracy of fundament...

Costal cartilage nasal augmentation rhinoplasty: Study on warping

Background:To retrospectively study the costochondral graft (CCG) based nasal dorsum augmentation failures due to warping.Materials and Methods:All patients fulfilling inclusion and exclusion criteria between January 2008 and December 2011 were included in the study. The details of the dorsal nasal length (DNL) immediate postoperative and 1 week postoperative period as well as the degree of divergence from midline by warping noted down in mm along with age, gender, and nature of graft.Statistics:Data analyzed using Statistical Package for the Social Sciences version 17. Descriptive statistics, Chi-square test and one-way analysis of variance are presented. P value ≤0.05 was considered significant.Result:One hundred and fifty seven cases fulfilled the criteria. Of these, 44 (28%) were males and rest were females. The mean age of the patients was 24.41 ± 4.9 years with a range of 17-37 years. In 102 cases (65%) had soft CCG while 55 (35%) were identified to be gritty type of CCG. Of the 157 cases, warping was identified in 41 cases (26.1%) and required revision of the surgery. Age group was significantly associated with presence of warping (P = 0.000).Discussion:With increase in age, the number of patients with gritty CCG was higher. Older patients had lesser incidence of warping while younger patients had more incidence of warping. The incidence was not significantly related to gender or the DNL. The grafts that were relatively straight had less incidence of warping.

Transition from ballistic to diffusive behavior of graphene ribbons in the presence of warping and charged impurities

We study the effects of the long-range disorder potential and warping on the conductivity and mobility of graphene ribbons using the Landauer formalism and the tight-binding p-orbital Hamiltonian. We demonstrate that as the length of the structure increases the system undergoes a transition from the ballistic to the diffusive regime. This is reflected in the calculated electron density dependencies of the conductivity and the mobility. In particular, we show that the mobility of graphene ribbons varies as mu(n) n^(-lambda), with 0<lambda<0.5. The exponent lambda depends on the length of the system with lambda=0.5 corresponding to short structures in the ballistic regime, whereas the diffusive regime lambda=0 (when the mobility is independent on the electron density) is reached for sufficiently long structures. Our results can be used for the interpretation of experimental data when the value of lambda can be used to distinguish the transport regime of the system (i.e. ballistic, quasi-ballistic or diffusive). Based on our findings we discuss available experimental results.

Open string wavefunctions in warped compactifications

We analyze the wavefunctions for open strings in warped compactifications, and compute the warped Kähler potential for the light modes of a probe D-brane. This analysis not only applies to the dynamics of D-branes in warped backgrounds, but also allows to deduce warping corrections to the closed string Kähler metrics via their couplings to open strings. We consider in particular the spectrum of D7-branes in warped Calabi-Yau orientifolds, which provide a string theory realizations of the Randall-Sundrum scenario. We find that certain background fluxes, necessary in the presence of warping, couple to the fermionic wavefunctions and qualitatively change their behavior. This modified dependence of the wavefunctions are needed for consistency with supersymmetry, though it is present in non-supersymmetric vacua as well. We discuss the deviations of our setup from the RS scenario and, as an application of our results, compute the warping corrections to Yukawa couplings in a simple model. Our analysis is performed both with and without the presence of D-brane world-volume flux, as well as for the case of backgrounds with varying dilaton.

Robust and computationally efficient superresolution algorithm

Superresolution is the process of combining information from multiple subpixel-shifted low-resolution images to form a high-resolution image. It works quite well under ideal conditions but deteriorates rapidly with inaccuracies in motion estimates. We model the original high-resolution image as a Markov random field (MRF) with a discontinuity adaptive regularizer. Given the low-resolution observations, an estimate of the superresolved image is obtained by using the iterated conditional modes (ICM) algorithm, which maximizes the local posterior conditional probability sequentially. The proposed method not only preserves edges but also lends robustness to errors in the estimates of motion and blur parameters. We derive theoretically the neighborhood structure for the posterior distribution in the presence of warping, blurring, and downsampling operations and use this to effectively reduce the overall computations. Results are given on synthetic as well as real data to validate our method.

Large Magellanic Cloud Bar: Evidence of a Warped Bar

The geometry of the LMC bar is studied using the dereddened mean magnitudes of the red clump stars (I0) from the Optical Gravitational Lensing Experiment II catalog. The value of I0 is found to vary in the east-west direction such that both the east and the west end of the bar are closer to us with respect to the center of the bar. The maximum observed variation has a statistical significance of more than 7.6 σ with respect to the maximum value of random error. The variation in I0 indicates the presence of warp in the bar of the LMC. The warp and the structures seen in the bar indicate that the bar could be a dynamically disturbed structure.

The shear strain influence on the dynamics of thin-walled beams

The influence of middle-surface shear strains on the dynamics of thin-walled beams is analyzed. By means of a suitable choice of the axial displacement field, shear lag effects in bending and torsion are taken into account for open and closed cross-sections. The equations of motion are obtained via Hamilton's principle. The flexural-torsional natural frequencies in the presence of warping which varies along the beam axis are compared with those given by Timoshenko-Vlasov models. The solution to the problem is pursued by means of the most natural choice, i.e. the classical trigonometric series expansion. A suitable algorithm is developed to solve the resulting eigenvalue problem which turns out to be strongly ill-conditioned.