The double ionization of argon and xenon in an intense laser field has been studied in detail using an electron-ion coincidence technique. The observed double ionization electron spectra in xenon show resonancelike structures here resolved for the first time. In argon, the featureless spectra are consistent with rescattering. This represents a clear transition in the dynamics of strong-field do...

this paper a novel homotopy perturbation method has been presented for forced convection boundary layer problems in a porous medium. Noting the infinite condition, a homotopy form which is similar to the singular perturbation form has been considered. The inner and outer solutions have been achieved and the coincidence of the results has been investigated with a proper matching method. The resu...

We consider networks of spiking coincidence detectors in continuous time. A single detector is a finite state machine that emits a pulsatile signal whenever the number incoming inputs exceeds a threshold within a time window of some tolerance width. Such finite state models are well-suited for hardware implementations of neural networks, as on integrated circuits (IC) or field programmable arra...

We demonstrate that if k-essence can solve the coincidence problem and play the role of dark energy in the Universe, the fluctuations of the field have to propagate superluminally at some stage. We argue that this implies that successful k-essence models violate causality. It is not possible to define a time ordered succession of events in a Lorentz invariant way. Therefore, k-essence cannot ar...

We observe pronounced transport anisotropies in magnetotransport experiments performed in the two-dimensional electron system of a Si/SiGe heterostructure. They occur when an in-plane field is used to tune two Landau levels with opposite spin to energetic coincidence. The observed anisotropies disappear drastically for temperatures above 1 K. We propose that our experimental findings may be cau...

As the number of systems which offer annotations on digital documents increases, robust anchoring of annotations is a key challenge. It is especially important if the annotator lacks write-access to the document being annotated. For example, if someone makes an annotation on a web page today and the web page changes tomorrow, what happens to the annotation? One approach is simply to “orphan” th...

We consider the coincidence problem for the square lattice that is translated by an arbitrary vector. General results are obtained about the set of coincidence isometries and the coincidence site lattices of a shifted square lattice by identifying the square lattice with the ring of Gaussian integers. To illustrate them, we calculate the set of coincidence isometries, as well as generating func...

A common coincidence point theorem for R-weakly commuting mappings is obtained. Our result extend several ones existing in literature. 2000 Mathematics Subject Classification. 54H25.

Let Y be a finite connected complex and p : Y →N a fibration over a compact nilmanifold N . For any finite complex X and maps f ,g : X → Y , we show that the Nielsen coincidence number N( f ,g) vanishes if the Reidemeister coincidence number R(p f , pg) is infinite. If, in addition, Y is a compact manifold and g is the constant map at a point a∈ Y , then f is deformable to a map f̂ : X → Y such ...