95,847 research outputs found
Hessian sufficiency for bordered Hessian
We show that the second–order condition for strict local extrema in both constrained and unconstrained optimization problems can be expressed solely in terms of principal minors of the (Lagrengean) [sic] Hessian. This approach unifies the determinantal tests in the sense that the second-order condition can be always given solely in terms of Hessian matrix
Optical-Near Infrared Color Gradients of Elliptical Galaxies and Their Environmental Dependence
We have studied the environmental effect on optical-NIR color gradients of
273 nearby elliptical galaxies. Color gradient is a good tool to study the
evolutionary history of elliptical galaxies, since the steepness of the color
gradient reflects merging history of early types. When an elliptical galaxy
goes through many merging events, the color gradient can be get less steep or
reversed due to mixing of stars. One simple way to measure color gradient is to
compare half-light radii in different bands. We have compared the optical and
near infrared half-light radii of 273 early-type galaxies from Pahre(1999). Not
surprisingly, we find that r(V)s (half-light radii measured in V-band)
are in general larger than r(K)s (half-light radii measured in K-band).
However, when divided into different environments, we find that elliptical
galaxies in the denser environment have gentler color gradients than those in
the less dense environment. Our finding suggests that elliptical galaxies in
the dense environment have undergone many merging events and the mixing of
stars through the merging have created the gentle color gradients.Comment: 3 pages, 2 figures. Proceedings of the 6th East Asian Meeting of
Astronomy, held at Seoul National University, Korea, from October 18-22, 200
Deal Making in Whitehall: competing and complementary motivations behind the Review of Sub-national Economic Development and Regeneration'
Purpose – The aim of this paper is to explore Whitehall motivations underpinning the Sub-national Review of Economic Development and Regeneration.
Design/methodology/approach – The paper is based on interviews conducted with senior Whitehall officials involved in regional working.
Findings – The Sub-national Review seeks to streamline regional structures and provide regions with enhanced autonomy. However, findings indicate that there are distinct differences of opinion across Whitehall departments regarding the future trajectory of English regionalism and what powers and functions regional bodies should acquire. These contradictory positions raise questions about the implementation and effectiveness of the proposals.
Originality/value – An examination of these phenomena is intended to provide greater clarity regarding the opportunities and constraints presented by the latest phase of regional restructuring
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