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Wilder D. Bancroft

Bio: Wilder D. Bancroft is an academic researcher from Cornell University. The author has contributed to research in topics: Coagulation (water treatment) & Colloid. The author has an hindex of 13, co-authored 150 publications receiving 1729 citations.


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Journal ArticleDOI
23 Jun 2006-Science
TL;DR: This work shows how electromagnetic fields can be redirected at will and proposes a design strategy that has relevance to exotic lens design and to the cloaking of objects from electromagnetic fields.
Abstract: Using the freedom of design that metamaterials provide, we show how electromagnetic fields can be redirected at will and propose a design strategy. The conserved fields-electric displacement field D, magnetic induction field B, and Poynting vector B-are all displaced in a consistent manner. A simple illustration is given of the cloaking of a proscribed volume of space to exclude completely all electromagnetic fields. Our work has relevance to exotic lens design and to the cloaking of objects from electromagnetic fields.

7,811 citations

Journal ArticleDOI
TL;DR: Optical trapping of dielectric particles by a single-beam gradient force trap was demonstrated for the first reported time, confirming the concept of negative light pressure due to the gradient force.
Abstract: Optical trapping of dielectric particles by a single-beam gradient force trap was demonstrated for the first reported time. This confirms the concept of negative light pressure due to the gradient force. Trapping was observed over the entire range of particle size from 10 μm to ~25 nm in water. Use of the new trap extends the size range of macroscopic particles accessible to optical trapping and manipulation well into the Rayleigh size regime. Application of this trapping principle to atom trapping is considered.

6,434 citations

Journal ArticleDOI
23 Jun 2006-Science
TL;DR: A general recipe for the design of media that create perfect invisibility within the accuracy of geometrical optics is developed, which can be applied to escape detection by other electromagnetic waves or sound.
Abstract: An invisibility device should guide light around an object as if nothing were there, regardless of where the light comes from. Ideal invisibility devices are impossible, owing to the wave nature of light. This study develops a general recipe for the design of media that create perfect invisibility within the accuracy of geometrical optics. The imperfections of invisibility can be made arbitrarily small to hide objects that are much larger than the wavelength. With the use of modern metamaterials, practical demonstrations of such devices may be possible. The method developed here can also be applied to escape detection by other electromagnetic waves or sound.

3,850 citations

Journal ArticleDOI
TL;DR: In this paper, a review of scattering theory required for analysis of light reflected by planetary atmospheres is presented, which demonstrates the dependence of single-scattered radiation on the physical properties of the scatterers.
Abstract: This paper reviews scattering theory required for analysis of light reflected by planetary atmospheres. Section 1 defines the radiative quantities which are observed. Section 2 demonstrates the dependence of single-scattered radiation on the physical properties of the scatterers. Section 3 describes several methods to compute the effects of multiple scattering on the reflected light.

2,691 citations

Journal ArticleDOI
TL;DR: In this article, a standard method of analysis of proanthocyanidins based on use of an n-BuOH-HCl-FeIII mixture is given, and the ratio of absorbance maxima of the cyanidin (550 nm) produced to that near 280 nm for the original procyanidin polymer solution was ∼ 3.5.

2,074 citations