In this work, the notion of a slant helix is extended to the space E. First, we introduce the type-2 harmonic curvatures of a regular curve. Thereafter, by using this, we present some necessary and sufficient conditions for a curve to be a slant helix in Euclidean n-space. We also express some integral characterizations of such curves in terms of the curvature functions. Finally, we give some c...

In two dimensions, the exponential X-ray transform has been wellstudied due to its applications of correcting attenuation effects in Single Photon Emission Computed Tomography (SPECT). Explicit inversion formulas have been known for over 15 years. The threedimensional (3D) case has not been as thoroughly examined, and inversion formulas are available for only a few of the wide range of possible...

A slant immersion is an isometric immersion from a Riemannian manifold into an almost Hermitian manifold with constant Wirtinger angle (1~ . In this article we study and characterize slant surfaces in the complex 2-plane ~2 via the Gauss map. We also prove that every surface without complex tangent points in a 4-dimensional almost Hermitian manifold M is slant with respect to a suitably chosen ...

Koffka's (1935, pp. 224-235) explanation of shape-constancy is based on the assumption of an invariant linkage between slant and shape. Koffka's hypothesis has been formulated in the following way by Beck and Gibson (1955): "A retinal projection of a given form determines a unique relation of apparent shape to apparent slant" (p. 126). The invariance hypothesis requires that perceived shape var...

The RSH SPECT scanner provides parallel-beam attenuated projections for a fully 3D acquisition geometry. The geometry can be represented by circles on the unit sphere of projection directions, one circle for each position of the detector head. Unlike most other fully 3D geometries this one is particularly challenging because there are no 2D subsets in the data. When no attenuation is present, i...

0018-9251/03/$17.00 @ 2003 IEEE Two-way antenna radiation pattern at frequency w + wc, Slow-time Doppler two-way antenna radiation pattern Pulse bandwidth Speed of light Covariance of w(k,,t) at time t Cross-range aperture length Energy of RJt) Energy of p( t ) Point target refectivity Fourier transform operator Inverse Fourier transform operator Fourier transform of electric field in antenna a...

The results of several experiments demonstrate that the estimated magnitude of perceived slant of large stereoscopic surfaces increases with the duration of the presentation. In these experiments, subjects were free to make eye movements. A possible explanation for the increase is that the visual system needs to scan the stimulus with eye movements (which take time) before it can make a reliabl...

Rotating a surface about a horizontal axis alters the retinal horizontal-shear disparities. Opposed torsional eye movements (cyclovergence) also change horizontal shear. If there were no compensation for the horizontal disparities created by cyclovergence, slant estimates would be erroneous. We asked whether compensation for cyclovergence occurs, and, if it does, whether it occurs by use of an ...

There have been many experiments reported in the literature that have employed discrimination procedures to estimate the variance of observers' slant judgments from texture and binocular disparity, both individually and in combination. The research described in the present article identifies two serious methodological flaws in these studies. Although discrimination thresholds can be influenced ...