Javier Santamaría

Bio: Javier Santamaría is an academic researcher from University of Oviedo. The author has contributed to research in topics: Carbene & Transition metal carbene complex. The author has an hindex of 25, co-authored 81 publications receiving 2444 citations. Previous affiliations of Javier Santamaría include Scripps Research Institute & Spanish National Research Council.

Accommodation-dependent model of the human eye with aspherics

Abstract: We consider a schematic human eye with four centered aspheric surfaces. We show that by introducing recent experimental average measurements of cornea and lens into the Gullstrand-Le Grand model, the average spherical aberration of the actual eye is predicted without any shape fitting. The chromatic dispersions are adjusted to fit the experimentally observed chromatic aberration of the eye. The polychromatic point-spread function and modulation transfer function are calculated for several pupil diameters and show good agreement with previous experimental results. Finally, from this schematic eye an accommodation-dependent model is proposed that reproduces the increment of refractive power of the eye during accommodation. The variation of asphericity with accommodation is also introduced in the model and the resulting optical performance studied.

Determination of the point-spread function of human eyes using a hybrid optical-digital method

Abstract: A method for the determination of the bidimensional optical transfer function (OTF) and the point-spread function of human eyes is presented. Aerial short-term images of a point source are directly recorded with a TV camera and fed into a digital image-processing system that allows one to determine and display such functions. The method has been implemented in such a way that recording and computation can be carried out on a routine basis with minimum discomfort for the observer. A detailed description of the method and typical aerial and retinal images of a point source as well as the OTF's results are presented in this paper.

Diels−Alder Reactions through Reversible Encapsulation

Abstract: Experimental details are given for the preparation of large self-complementary molecules capable of assembly into pseudospherical capsules. These structures exist as hydrogen bonded dimers in organ...

Linear and quadratic time-frequency signal representations

Abstract: A tutorial review of both linear and quadratic representations is given. The linear representations discussed are the short-time Fourier transform and the wavelet transform. The discussion of quadratic representations concentrates on the Wigner distribution, the ambiguity function, smoothed versions of the Wigner distribution, and various classes of quadratic time-frequency representations. Examples of the application of these representations to typical problems encountered in time-varying signal processing are provided. >

Functional Molecular Flasks : New Properties and Reactions within Discrete, Self-Assembled Hosts

Abstract: The application of self-assembled hosts as "molecular flasks" has precipitated a surge of interest in the reactivity and properties of molecules within well-defined confined spaces. The facile and modular synthesis of self-assembled hosts has enabled a variety of hosts of differing sizes, shapes, and properties to be prepared. This Review briefly highlights the various molecular flasks synthesized before focusing on their use as functional molecular containers--specifically for the encapsulation of guest molecules to either engender unusual reactions or unique chemical phenomena. Such self-assembled cavities now constitute a new phase of chemistry, which cannot be achieved in the conventional solid, liquid, and gas phases.

Strategies for the Construction of Supramolecular Compounds through Coordination Chemistry

Abstract: Synthetic organic chemists enjoy the luxury of having a large collection of reliable reactions at their disposal for preparing small molecules, mesoscopic structures, and polymers. Coordination chemists, on the other hand, are faced with the fact that transition metal chemistry, when normalized for the number of transition metals, has relatively few high-yielding reactions, when compared to the chemistry of carbon, for preparing even small molecule structures. This lack of control is manifested, in large part, in the weak metal-ligand interactions found in coordination complexes as compared with the strong covalent bonds in organic compounds. Weak bonding often translates into many reaction pathways that are not substantially different from an energetic point of view, and therefore, results in poor selectivity. As a result, many coordination chemists in recent years have come to the realization that it may be easier and more productive to develop straightforward and reliable routes to mesoscopic supramolecular structures by capitalizing on the modest collection of high-yielding reactions in coordination chemistry, the directional bonding afforded by metal centers, and strategies aimed at taking advantage of the weak metal bonds found in coordination complexes. Three emerging synthetic strategies, the symmetry-interaction, directional-bonding, and weak-link synthetic approaches, all use metal centers as structural building blocks to rationally assemble molecular components into supramolecular metallocyclophanes. These three approaches are discussed herein, and the fundamental principles underlying each as well as their capabilities are compared and contrasted.

Computer and Robot Vision

Abstract: Computer and Robot Vision Vol. 1, by R.M. Haralick and Linda G. Shapiro, Addison-Wesley, 1992, ISBN 0-201-10887-1.