نتایج جستجو برای: curvature field

تعداد نتایج: 823080  

2003
C. Shen X. Li M. Dunlop Z. X. Liu A. Balogh D. N. Baker M. Hapgood Xinyue Wang

The geometrical structure of the magnetic field is a critical character in the magnetospheric dynamics. Using the magnetic field data measured by the Cluster constellation satellites, the geometrical structure including the curvature radius, directions of curvature and normal of the osculating planes of the magnetic field lines within the current sheet/neutral sheet have been investigated. The ...

Journal: :Vision Research 1995
T.M.H. Dijkstra V. Cornilleau-Pérès C.C.A.M. Gielen J. Droulez

We compare the performance in the detection of the shape of concave, planar and convex surfaces for small-field (8 deg) and large-field (90 deg) stimuli. Shape is perceived from head translations, object translations and object rotations. We find large differences between small-field and large-field stimulation. For small-field stimulation performance is best for object rotation, intermediate f...

2009
Kazuya Koyama Shuntaro Mizuno Filippo Vernizzi David Wands

We compute the non-Gaussianity of the curvature perturbation generated by ekpyrotic collapse with multiple fields. The transition from the multi-field scaling solution to a single-field dominated regime converts initial isocurvature field perturbations to an almost scale-invariant comoving curvature perturbation. In the specific model of two fields, φ1 and φ2, with exponential potentials, −Vi e...

2012
Joseph Elliston David Seery Reza Tavakol

We compute the covariant three-point function near horizon-crossing for a system of slowly-rolling scalar fields during an inflationary epoch, allowing for an arbitrary field-space metric. We show explicitly how to compute its subsequent evolution using a covariantized version of the separate universe or ‘δN ’ expansion, which must be augmented by terms measuring curvature of the field-space ma...

2008
Nicholas T. Ouellette J. P. Gollub

By measuring the tracks of tracer particles in a quasi-two-dimensional spatiotemporally chaotic laboratory flow, we determine the instantaneous curvature along each trajectory and use it to construct the instantaneous curvature field. We show that this field can be used to extract the time-dependent hyperbolic and elliptic points of the flow. These important topological features are created and...

2013
Algirdas Antano Maknickas

With applying of new proposed electromagnetic gravity Lagrangian together with Einstein-Hilbert equation not zero space curvature was derived. The curvature gives “a priory” postulate of equivalence of mass and electro-magnetic field gravity properties. The non-zero trace of energy-stress tensor of electrical field changes space curvature of gravity mass, which yields to prediction of dependenc...

2005

We study the geometrical properties of a unit vector field on a Riemann-ian 2-manifold, considering the field as a local imbedding of the manifold into its tangent sphere bundle with the Sasaki metric. For the case of constant curvature K, we give a description of the totally geodesic unit vector fields for K = 0 and K = 1 and prove a non-existence result for K = 0, 1. We also found a family ξω...

2005

We study the geometrical properties of a unit vector field on a Riemann-ian 2-manifold, considering the field as a local imbedding of the manifold into its tangent sphere bundle with the Sasaki metric. For the case of constant curvature K, we give a description of the totally geodesic unit vector fields for K = 0 and K = 1 and prove a non-existence result for K = 0, 1. We also found a family ξω...

2006
Tomohiro Matsuda

A new mechanism for generating the curvature perturbation at the end of inflaton has been investigated. The dominant contribution to the primordial curvature perturbation may be generated during the period of instant preheating. The mechanism converts isocurvature perturbation related to a light field into curvature perturbation, where the “light field” is not the inflaton field. This mechanism...

Journal: :Physical review letters 2015
G Rosi L Cacciapuoti F Sorrentino M Menchetti M Prevedelli G M Tino

We present the first direct measurement of the gravity-field curvature based on three conjugated atom interferometers. Three atomic clouds launched in the vertical direction are simultaneously interrogated by the same atom interferometry sequence and used to probe the gravity field at three equally spaced positions. The vertical component of the gravity-field curvature generated by nearby sourc...

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