It is well known that a huge number of buried landmines in the post-war countries are still active, and that many civilians are killed or injured by landmine related accidents every year. Therefore, detection and clearance of buried landmines is a very important issue. Metal detectors are the almost universally available fielded devices for landmine detection, but they have great difficulty in ...

We present moderate-resolution Keck spectra of nine candidate globular clusters in the possible merger-remnant elliptical galaxy NGC 3610. Eight of the objects appear to be bona fide globular clusters of NGC 3610. We find that two of the clusters belong to an old metal-poor population, five to an old metal-rich population, and only one to an intermediate-age metal-rich population. The estimated...

We present moderate-resolution Keck spectra of nine candidate globular clusters in the possible merger-remnant elliptical galaxy NGC 3610. Eight of the objects appear to be bona fide globular clusters of NGC 3610. We find that two of the clusters belong to an old metal-poor population, five to an old metal-rich population, and only one to an intermediate-age metal-rich population. The estimated...

Choptuik has demonstrated that naked singularities can arise in gravitational collapse from smooth, asymptotically flat initial data, and that such data have codimension one in spherical symmetry. Here we show, for perfect fluid matter with equation of state p = ρ/3, by perturbing around spherical symmetry, that such data have in fact codimension one in the full phase space, at least in a neigh...

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I propose to use as a window the dark core of an optical vortex to examine a weak background signal hidden in the glare of a bright coherent source. Applications such as the detection of an astronomical object, forward-scattered radiation, and incoherent light are described whereby signal enhancements of at least 7 orders of magnitude may be achieved.

We present new infrared JHK photometry for 61 halo and disk stars around the stellar/substellar boundary. We also present new L ′ photometry for 21 of these stars and for 40 low–mass stars taken from the Leggett 1992 photometry compilation. These data are combined with available optical photometry and astrometric data to produce color–color and absolute magnitude–color diagrams — the current sa...

We give an example of a geometry in which two metallic objects in vacuum experience a repulsive Casimir force. The geometry consists of an elongated metal particle centered above a metal plate with a hole. We prove that this geometry has a repulsive regime using a symmetry argument and confirm it with numerical calculations for both perfect and realistic metals. The system does not support stab...

In Direct Metal Laser Sintering objects are created by sequential sintering loose metal powder particles by means of laser technology. When the laser sintering process involves temperature gradients, thermal stresses develop. Corresponding residual stresses induce warping of the densified structure leading to unacceptable tolerance losses. This paper examines the role of laser beam scan pattern...