Perceptron-like computation based on biologically-inspired neurons with heterosynaptic mechanisms

Perceptrons are one of the fundamental paradigms in artificial neural networks and a keyprocessing scheme in supervised classification tasks. However, the algorithm they provideis given in terms of unrealistically simple processing units and connections andtherefore, its implementation in real neural networks is hard to be fulfilled. In thiswork, we present a neural circuit able to perform perceptron’s computation based onrealistic models of neurons and synapses. The model uses Wang-Buzsáki neurons withcoupling provided by axodendritic and axoaxonic synapses (heterosynapsis). The maincharacteristics of the feedforward perceptron operation are conserved, which allows tocombine both approaches: whereas the classical artificial system can be used to learn aparticular problem, its solution can be directly implemented in this neural circuit. As aresult, we propose a biologically-inspired system able to work appropriately in a widerange of frequencies and system parameters, while keeping robust to noise and error.     

SIMPRE: A software package to calculate crystal field parameters,energy levels,and magnetic properties on mononuclear lanthanoid complexes based on charge distributions

This work presents a fortran77 code based on an effective electrostatic model of point charges around a rare earth ion. The program calculates the full set of crystal field parameters, energy levels spectrum, and wave functions, as well as the magnetic properties such as the magnetization, the temperature dependence of the magnetic susceptibility, and the Schottky contribution to the specific heat. It is designed for real systems that need not bear ideal symmetry and it is able to determine the easy axis of magnetization. Its systematic application to different coordination environments allows magneto‐structural studies. The package has already been successfully applied to several mononuclear systems with single‐molecule magnetic behavior. The determination of effective point charge parameters in these studies facilitates its application to new systems. In this article, we illustrate its usage with two example studies: (a) an ideal cubic structure coordinating a lanthanoid ion and (b) a system with slow relaxation of the magnetization, LiHo_xY_(1‐x)F₄. © 2013 Wiley Periodicals, Inc.     

Combining Spontaneous Polymerization and Click Reactions for the Synthesis of Polymer Brushes: A “Grafting Onto” Approach

Two novel benzofulvene monomers bearing propargyl or allyl groups have been synthesized by means of readily accessible reactions, and were found to polymerize spontaneously by solvent removal, in the apparent absence of catalysts or initiators, to give the corresponding polybenzofulvene derivatives bearing clickable propargyl or allyl moieties. The clickable propargyl and allyl groups were exploited in appropriate click reactions to develop a powerful and versatile “grafting onto” synthetic methodology for obtaining tailored polymer brushes.     

Structure-Based Design of Covalent Siah Inhibitors

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Chiral textures inside 2D achiral domains

Chiral interfaces are of capital importance for biorecognition processes and nanotechnology. In this work, a mixed Langmuir monolayer was built using a surface-active dye and a phospholipid. The monolayer displayed optical activity. The driving force for the formation of the supramolecular chirality is the self-assembly of the polar headgroups of the dye. The existence of supramolecular chirality inside nonchirally-shaped domains is shown.     

Fast Pirouetting Motion in a Pyridine Bisamine‐Containing Copper‐Complexed Rotaxane

The present work reports the introduction of pyridine bisamine terdentate ligands in the structure of a pirouetting copper rotaxane. Rotaxane 2 [PF₆] constitutes the first example of the incorporation of imine‐based dynamic covalent chemistry in the synthesis of switchable copper‐complexed interlocked systems. In this rotaxane, the substitution of the classical terpyridine terdentate unit by a pyridine bisamine moiety has led to a significant stabilization of the pentacoordinated site. That fact has been evidenced by EPR spectroscopy and cyclic voltammetry. Regarding the tetracoordinated site, the congestion around the coordination sphere has been reduced to accelerate the typically slow reorganization of the Cu^II. Ethynyl‐3,8‐substitution on the axis phenanthroline along with the 2,9‐diphenyl‐1,10‐phenanthroline (dpp) present in the macrocycle afforded a very stable coordination environment for Cu^I, which is at the same time labile upon oxidation. In summary, the incorporation of a pyridine bisamine unit as a terdentate ligand and the optimization of the bidentate ligand of the axle not only has led to a simplification of the synthetic procedures, but it has also given rise to a bistable systems with an enhanced energetic separation between states and an acceleration of the reorganization processes. Thus far, rotaxane 2 [PF₆] presents the fastest switching cycle reported to date in copper‐interlocked dynamic systems.     

Characterization of Strict Positive Definiteness on products of complex spheres

Positivity - In this paper we consider Positive Definite functions on products $$\Omega _{2q}\times \Omega _{2p}$$ of complex spheres, and we obtain a condition, in terms of the coefficients in...     

Macrophage Migration Inhibitory Factor (MIF) and Its Homologue D-Dopachrome Tautomerase (DDT) Inversely Correlate with Inflammation in Discoid Lupus Erythematosus

Discoid Lupus Erythematosus (DLE) is a chronic cutaneous disease of unknown etiology and of immunoinflammatory origin that is characterized by inflammatory plaques and may lead to disfiguring scarring and skin atrophy. Current treatments are limited, with a large proportion of patients either poorly or not responsive, which makes DLE an unmet medical need. Macrophage migration inhibitory factor (MIF) is the prototype of a pleiotropic family of cytokine that also includes the recently discovered homologue D-dopachrome tautomerase (DDT) or MIF2. MIF and DDT/MIF-2 exert several biological properties, primarily, but not exclusively of a proinflammatory nature. MIF and DDT have been suggested to play a key role in the pathogenesis of several autoimmune diseases, such as multiple sclerosis and type 1 diabetes, as well as in the development and progression of certain forms of cancers. In the present study, we have performed an immunohistochemistry analysis for the evaluation of MIF in DLE lesions and normal skin. We found high levels of MIF in the basal layer of the epidermis as well as in the cutaneous appendage (eccrine glands and sebocytes) of normal skin. In DLE lesions, we observed a significant negative correlation between the expression of MIF and the severity of inflammation. In addition, we performed an analysis of MIF and DDT expression levels in the skin of DLE patients in a publicly available microarray dataset. Interestingly, while these in silico data only evidenced a trend toward reduced levels of MIF, they demonstrated a significant pattern of expression and correlation of DDT with inflammatory infiltrates in DLE skins. Overall, our data support a protective role for endogenous MIF and possibly DDT in the regulation of homeostasis and inflammation in the skin and open up novel avenues for the treatment of DLE.