Recently time-reversal techniques have emerged as a new, important and fascinating discipline within wave propagation. Many of the problems involved can best be understood, analysed and optimized based on a random field model for the medium. Here we discuss stable refocusing of second-order time-reversed reflections. This phenomenon may appear as surprising at first. However, we show how it can...

The “screen mapping” introduced by Susskind to implement ’t Hooft’s holographic hypothesis is studied. For a single screen time, there are an infinite number of images of a black hole event horizon, almost all of which have smaller area on the screen than the horizon area. This is consistent with the focusing equation because of the existence of focal points. However, the boundary of the past (...

1. Isoelectric focusing of human liver alkaline phosphatase in a sucrose density gradient with LKB Ampholine as carrier ampholytes is described. 2. Problems due to the chelating properties of the ampholytes and the pH gradient were examined. 3. A reactivation procedure to counter these effects was devised that can probably be used for other alkaline phosphatases. 4. The isoelectric point of hum...

Nanomaterials have unique physical and chemical properties that are useful for various consumer and industrial applications, but these very same properties may give rise to unique biological reactivity. This has led to mounting concerns over the safety of nanomaterials, and pressure to control the potential risks. The toxicological properties of metal, metal oxide nanoparticles, quantum dots, f...

Reconstruction of noise-corrupted surfaces may be stated as a (in general nonconvex) functional minimization problem. For functionals with quadratic data term, this paper addresses the criteria for such functionals to be convex, and the variational approach for minimization. I present two automatic and general methods of approximation with convex functionals based on Gaussian convolution. They ...

This paper studies the problem of obtaining depth information from focusing and defocusing, which have long been noticed as important sources of depth information for human and machine vision. In depth from focusing, we try to eliminate the local maxima problem which is the main source of inaccuracy in focusing; in depth from defocusing, a new computational model is proposed to achieve higher a...

Investigations into the mechanisms which regulate entry of integral membrane proteins, and associated ligands, into the cell through vesicular carriers (endocytosis) have greatly benefited from the application of live-cell imaging. Several excellent recent reviews have detailed specific aspects of endocytosis, such as entry of particular cargo, or the different routes of internalization. The ai...

It is well known how to use an intuitionistic meta-logic to specify natural deduction systems. It is also possible to use linear logic as a meta-logic for the specification of a variety of sequent calculus proof systems. Here, we show that if we adopt different focusing annotations for such linear logic specifications, a range of other proof systems can also be specified. In particular, we show...

OBJECTIVE To review office management of elderly hypertensive patients and to focus on cognition and function both as ways to stratify who gets treated and as end points for treatment. QUALITY OF EVIDENCE Relevant papers were identified through a MEDLINE search from January 1994 to March 2000, using the MeSH terms hypertension, aged, aged 80 and over, cognition, activities of daily living, ther...

Dynamic focusing has been proposed[1] as a way to eliminate a conventional collimation and final focus system in linear colliders, and is a scheme that is more readily extended to colliders at several TeV center-of-mass energy. In this paper we examine several outstanding issues, in particular, the optimization of the lens and main beam parameters. Simulations of the lens-lens, lens-main, and m...