A pointed endofunctor (and in particular a reflector) (R, r) in a category X is direct iff for each morphism f : X→ Y the pullback of Rf against rY exists and the unique fill-in morphism u from X to the pullback is such that Ru is an isomorphism. (This is close to the concept of a simple reflector introduced by Cassidy, Hébert and Kelly in 1985.) We give sufficient conditions for directness, an...

We present an image-based method for separating diffuse and specular reflections using environmental structured illumination. Two types of structured illumination are discussed: phase-shifted sine wave patterns, and phaseshifted binary stripe patterns. In both cases the low-pass filtering nature of diffuse reflections is utilized to separate the reflection components. We illustrate our method o...

We prove a conjecture of Aanjaneya, Bishnu, and Pal that the maximum number of diffuse reflections needed for a point light source to illuminate the interior of a simple polygon with n walls is bn/2c − 1. Light reflecting diffusely leaves a surface in all directions, rather than at an identical angle as with specular reflections.

6 We propose a new numerical scheme for a class of one-dimensional reflected stochastic differential equations (SDEs) by virtue of their explicit solutions, which enables us to carry out the simulation of this class of reflected SDEs by simulating some related SDEs without reflections. The new scheme yields the same order of convergence as the scheme for the SDEs without reflections.

We provide a concrete criterion to determine whether or not two given elements of PU(2,1) can be written as products of real reflections, with one reflection in common. As an application, we show that the Picard modular groups PU(2, 1,Od) with d = 1, 2, 3, 7, 11 are generated by real reflections up to index 1, 2, 4 or 8.

Learning ought to Ilf' motiyated by its subjed matter and by the material to be learned. not b~' pressure. foree. 01' reward from the teacher 01' parents. Institutionalised learning differs from the aequisition of information outside of school: in the former. learning is demanded more 01' less independently of the needs and wishes ofthe indiyid· uals concerned. whereas thf' latter is "naturally...

The 50th anniversary of the publication of the proposed double-helix structure for DNA by James Watson and Francis Crick last year was widely celebrated. But historically, we are still perhaps too close to the event to realise its ultimate significance. Therefore, the more people who were involved or who subsequently worked with the molecule write and tell of their experiences, the richer histo...

Coloration is defined as changes in Timbre/”Klangfarbe”. Adding a reflection automatically changes the frequency response of a signal, giving some kind of coloration. This might be looked upon as distortion. However, reflections have been a part of sound distribution since the Greek amphi-theatres, indicating that some coloration must be acceptable, even “wanted”. The question is: “Which reflec...

Fibered image guides for confocal reflectance endomicroscopy suffer from Fresnel reflections at the fiber terminals, which can limit signal-to-noise ratio in these systems. A model that describes these terminal reflections is presented to better understand how they can be managed most effectively. An expression for the refractive index of termination that minimizes the reflection as a function ...

In this work we develop some reflections on the thresholding algorithm proposed by Tizhoosh in [16]. The purpose of these reflections is to complete the considerations published recently in [17,18] on said algorithm. We also prove that under certain constructions, Tizhoosh’s algorithm makes it possible to obtain additional information from commonly used fuzzy algorithms. & 2010 Elsevier Ltd. Al...