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There are three types of hypersurfaces in a pseudoconformal space C^n_1 of Lorentzian signature: spacelike, timelike, and lightlike. These three types of hypersurfaces are considered in parallel. Spacelike hypersurfaces are endowed with a…

Differential Geometry · Mathematics 2009-10-31 Maks A. Akivis , Vladislav V. Goldberg

The best-fitting 2-dimensional plane within the 3-dimensional space of spiral galaxy disk observables (rotational velocity v_{rot}, central disk surface brightness \mu_0 = -2.5log I_0, and disk scale-length h) has been constructed. Applying…

Astrophysics · Physics 2012-04-26 Alister W. Graham

Given a minimum measurable length underlying spacetime, the latter may be effectively regarded as discrete, at scales of order the Planck length. A systematic discretization of continuum physics may be effected most efficiently through the…

High Energy Physics - Theory · Physics 2008-11-26 Cosmas K. Zachos

We present our recent results on the properties of the outskirts of disk galaxies. In particular, we focus on spiral galaxies with stellar disk truncations in their radial surface brightness profiles. Using SDSS, UDF and GOODS data we show…

Astrophysics of Galaxies · Physics 2010-02-08 J. Bakos , I. Trujillo , R. Azzollini , J. E. Beckman , M. Pohlen

This paper investigates the geometry and singularities of parallel surfaces of cuspidal cross caps, the fundamental non-front frontal singularities. We establish a criterion for the degeneracy of the distance squared function in terms of…

Differential Geometry · Mathematics 2026-05-26 Atsuki Hiramatsu

Structured light concerns the control of light in its spatial degrees of freedom (amplitude, phase and polarization), and has proven instrumental in many applications. The creation of structured light usually involves the conversion of a…

Optics · Physics 2023-07-19 Stirling Scholes , Valeria Rodríguez-Fajardo , Andrew Forbes

Directed spiral percolation (DSP), percolation under both directional and rotational constraints, is studied on the triangular lattice in two dimensions (2D). The results are compared with that of the 2D square lattice. Clusters generated…

Disordered Systems and Neural Networks · Physics 2009-11-10 S. Sinha , S. B. Santra

Irradiation of solid surfaces with high intensity, ultrashort laser pulses triggers a variety of secondary processes that can lead to the formation of transient and permanent structures over large range of length scales from mm down to the…

Materials Science · Physics 2025-08-27 Jörn Bonse , Klaus Sokolowski-Tinten

Black hole shadows and photon spheres offer valuable tools for investigating black hole properties. Recent observations by the Event Horizon Telescope Collaboration have confirmed the existence of rotating black holes. Black hole parameters…

General Relativity and Quantum Cosmology · Physics 2024-11-26 Vitalii Vertogradov , Ali Övgün , Reggie C. Pantig

Optical microdisk cavities with certain asymmetric shapes are known to possess unidirectional far-field emission properties. Here, we investigate arrays of these dielectric microresonators with respect to their emission properties resulting…

We study light-beam propagation in a nonlinear coupler with an asymmetric double-channel waveguide and derive various analytical forms of optical modes. The results show that the symmetry-preserving modes in a symmetric double-channel…

Optics · Physics 2015-06-01 Rujiang Li , Fei Lv , Lu Li , Zhiyong Xu

We use orbifold structures to deduce degeneracy statements for holomorphic maps into logarithmic surfaces. We improve former results in the smooth case and generalize them to singular pairs. In particular, we give applications on nodal…

Algebraic Geometry · Mathematics 2009-03-18 Erwan Rousseau

We study resonance patterns of a spiral-shaped dielectric microcavity with chaotic ray dynamics. Many resonance patterns of this microcavity, with refractive indices $n=2$ and 3, exhibit strong localization of simple geometric shape, and we…

Chaotic Dynamics · Physics 2009-11-10 Soo-Young Lee , Sunghwan Rim , Jung-Wan Ryu , Tae-Yoon Kwon , Muhan Choi , Chil-Min Kim

In the absence of external excitation, light trapped within a dielectric medium generally decays by leaking out (and also by getting absorbed within the medium). We analyze the leaky modes of a parallel-plate slab, a solid glass sphere, and…

Optics · Physics 2017-08-02 Masud Mansuripur , Miroslav Kolesik , Per Jakobsen

We demonstrate that shadows cast on a proto-planetary disk can drive it eccentric. Stellar irradiation dominates heating across much of these disks, so an uneven illumination can have interesting dynamical effects. Here, we focus on…

Earth and Planetary Astrophysics · Physics 2024-10-04 Yansong Qian , Yanqin Wu

This paper presents a new approach to studying galactic structures. They are considered as the low-frequency normal modes in a disc of orbits precessing at different angular speeds. Such a concept is an adequate alternative to the commonly…

Astrophysics · Physics 2009-11-10 E. V. Polyachenko

The `maximum' disk hypothesis of galactic disks imbedded in dark matter halos is examined. First, decompositions of the rotation curves of NGC 2613, 3198, 6503, and 7184 are analyzed. For these galaxies the radial velocity dispersions of…

Astrophysics · Physics 2007-05-23 B. Fuchs

We study photon orbits in the background of $(1+3)$-dimensional static, spherically symmetric geometries. In particular, we have obtained exact analytical solutions to the null geodesic equations for light rays in terms of the…

General Relativity and Quantum Cosmology · Physics 2021-05-20 Grigoris Panotopoulos , Angel Rincon , Ilidio Lopes

This paper addresses available constraints on mass models fitted to rotation curves. Mass models of disk galaxies have well-known degeneracies, that prevent a unique mass decomposition. The most notable is due to the unknown value of the…

Astrophysics · Physics 2009-11-10 Aaron A. Dutton , Stephane Courteau , Roelof de Jong , Claude Carignan

The collective dynamics of nonlinear electron waves in an one-dimensional degenerate electron gas is treated using the Lagrangian fluid approach. A new class of solutions with a nontrivial space and time dependence is derived. Both…

Plasma Physics · Physics 2015-06-19 S. Ghosh , N. Chakrabarti , F. Haas