A Survey of Adaptive Resonance Theory Neural Network Models for Engineering Applications

This survey samples from the ever-growing family of adaptive resonance theory (ART) neural network models used to perform the three primary machine learning modalities, namely, unsupervised, supervised and reinforcement learning. It comprises a representative list from classic to modern ART models, thereby painting a general picture of the architectures developed by researchers over the past 30 years. The learning dynamics of these ART models are briefly described, and their distinctive characteristics such as code representation, long-term memory and corresponding geometric interpretation are discussed. Useful engineering properties of ART (speed, configurability, explainability, parallelization and hardware implementation) are examined along with current challenges. Finally, a compilation of online software libraries is provided. It is expected that this overview will be helpful to new and seasoned ART researchers

Constrained Allocation Flux Balance Analysis

New experimental results on bacterial growth inspire a novel top-down approach to study cell metabolism, combining mass balance and proteomic constraints to extend and complement Flux Balance Analysis. We introduce here Constrained Allocation Flux Balance Analysis, CAFBA, in which the biosynthetic costs associated to growth are accounted for in an effective way through a single additional genome-wide constraint. Its roots lie in the experimentally observed pattern of proteome allocation for metabolic functions, allowing to bridge regulation and metabolism in a transparent way under the principle of growth-rate maximization. We provide a simple method to solve CAFBA efficiently and propose an "ensemble averaging" procedure to account for unknown protein costs. Applying this approach to modeling E. coli metabolism, we find that, as the growth rate increases, CAFBA solutions cross over from respiratory, growth-yield maximizing states (preferred at slow growth) to fermentative states with carbon overflow (preferred at fast growth). In addition, CAFBA allows for quantitatively accurate predictions on the rate of acetate excretion and growth yield based on only 3 parameters determined by empirical growth laws.Comment: 21 pages, 6 figures (main) + 33 pages, various figures and tables (supporting); for the supplementary MatLab code, see http://tinyurl.com/h763es

Preliminary study on electrophysiological changes after cellular autograft in age-related macular degeneration

Background: Evolving atrophic macular degeneration represents at least 80% of all macular degenerations and is currently without a standardized care. Autologous fat transplantation (AFT) efficacy was demonstrated by several studies, since these cells are able to produce growth factors. The aim of the work was to demonstrate possible therapeutic effect of the joined suprachoroidal graft of adipocytes, adipose derived stem-cells (ADSCs) in tissue adipose’s stromal vascular fractions (SVF), and platelet rich plasma (PRP). Methods: Twelve eyes in 12 dry age macular degeneration (AMD) patients, aged 71.25 (SD ± 6.8) between 62 and 80 years, were analyzed. A complete ocular evaluation was performed using: best corrected visual acuity (BCVA), retinographic analysis, spectral-domain optical coherence tomography, microperimetry, computerized visual field, and standard electroretinogram (ERG). Each eye received a cell in graft between choroid and sclera by means of the variant second Limoli, grafting of mature fat cells and ADSCs in SVF enriched with PRP (LRRT). In order to test if the differences pre- and post-treatment were significant the Wilcoxon signed rank test has been performed. Results: Adverse effects were not reported in the patients. After surgery with LRRT the most significant increase in the ERG values was recorded by scotopic rod-ERG (answer coming from the rods), from 41.26 to 60.83 μVolts (µV) with an average increase of 47.44% highly significant (p<0.05). Moderately significant was the one recorded by scotopic maximal ERG (answer coming from the rods and cones), from 112.22 to 129.68 μV with an average increase of 15.56% (p<0.1). Conclusions: Cell-mediated therapy based on growth factors used appears interesting because it can improve the retinal functionality responses in the short term. The ERG could, therefore, be used to monitor the effect of cell-mediated regenerative therapies

Immune-Neuroendocrine Interactions: Evolution, Ecology, and Susceptibility to Illness

The integration between immune and neuroendocrine systems is crucial for maintaining homeostasis from invertebrates to humans. In the first, the phagocytic cell, i.e., the immunocyte, is the main actor, while in the latter, the principle player is the lymphocyte. Immunocytes are characterized by the presence of pro-opiomelanocortin (POMC) peptides, CRH, and other molecules that display a significant similarity to their mammalian counterparts regarding their functions, as both are mainly involved in fundamental functions such as immune (chemotaxis, phagocytosis, cytotoxicity, etc.) and neuroendocrine (stress) responses. Furthermore, the immune-neuroendocrine system provides vital answers to ecological and immunological demands in terms of economy and efficiency. Finally, susceptibility to disease emerges as the result of a continuous dynamic interaction between the world within and the world outside. New fields such as ecological immunology study the susceptibility to pathogens in an evolutionary perspective while the field of neuro-endocrine-immunology studies the susceptibility from a more immediate perspective

Approximate analytical description of the nonaffine response of amorphous solids

An approximation scheme for model disordered solids is proposed that leads to the fully analytical evaluation of the elastic constants under explicit account of the inhomogeneity (nonaffinity) of the atomic displacements. The theory is in quantitative agreement with simulations for central-force systems and predicts the vanishing of the shear modulus at the isostatic point with the linear law {\mu} ~ (z - 2d), where z is the coordination number. The vanishing of rigidity at the isostatic point is shown to be a consequence of the canceling out of positive affine and negative nonaffine terms

Geometry and topology of knotted ring polymers in an array of obstacles

We study knotted polymers in equilibrium with an array of obstacles which models confinement in a gel or immersion in a melt. We find a crossover in both the geometrical and the topological behavior of the polymer. When the polymers' radius of gyration, $R_G$, and that of the region containing the knot, $R_{G,k}$, are small compared to the distance b between the obstacles, the knot is weakly localised and $R_G$ scales as in a good solvent with an amplitude that depends on knot type. In an intermediate regime where $R_G > b > R_{G,k}$, the geometry of the polymer becomes branched. When $R_{G,k}$ exceeds b, the knot delocalises and becomes also branched. In this regime, $R_G$ is independent of knot type. We discuss the implications of this behavior for gel electrophoresis experiments on knotted DNA in weak fields.Comment: 4 pages, 6 figure

Deflazacort treatment of cystoid macular edema in patients affected by Retinitis Pigmentosa: a pilot study

Background. To investigate the efficacy of a long-term treatment with Deflazacort (DFZ), a third generation synthetic glucocorticoid, in patients affected by Retinitis Pigmentosa (RP) complicated by Cystoid Macular Edema (CME). Methods. A randomized group of 10 RP subjects were selected for this pilot study and treated with DFZ for one year according to a standard protocol. Far and near Best Corrected Visual Acuity (BCVA), fluorescein angiography (Heidelberg Retina Angiograph) and computerized perimetry (Humphrey Visual Field Analyzer) were statistically assessed. Results. Near visual acuities, fluorescein angiographic findings and perimetric data improved significantly (p < 0.01) while far BCVA varied only slightly (p < 0.05). No ocular or systemic side effects were recorded. Conclusions. Further case-control studies, also involving a larger number of patients, are required to confirm these preliminary results. However, the present investigation seem to suggest that DFZ could be effective in reducing fluorescein angiographic findings and improving perimetric data and near visual acuities in RP patients, even though the pathogenesis of CME remains poorly understood

Clinical pathogenesis of macular holes in patients affected by retinitis pigmentosa

Background. To define the main clinical mechanisms involved in the pathogenesis of macular holes (MH) in patients affected by Retinitis Pigmentosa (RP). Methods. 236 RP subjects were enrolled in this study and ophthalmologically examined according to a standard FIARP (Italian Federation of the RP Associations) protocol. The prevalence of posterior vitreous detachment (PVD) as well as all types of RP-related macular abnormalities - especially vitreoretinal interface alterations (VRIA), cystoid macular edema (CME), "bull's eye maculopathy" (BEM) and MH - was reported; statistical analyses and correlations were assessed by means of Student t test and Pearson X2. Results. VRIA and CME were observed in 26.15% and 9.45% of the cases respectively and resulted significantly associated with MH, since they were constantly present in 22 of the 25 eyes affected by MH (88%) (X2 = 50.4; p < 0.01). In particular, in 9 of these cases (40.9%) MH was correlated to both CME and VRIA, while in 11 (50%) and 2 (9.1%) eyes CME or, VRIA were present separately. A normal biomicroscopic macular appearance, PVD and BEM were found in 26.81%, 6.6% and 21.54% of the cases respectively. Conclusions. Further studies involving a larger number of patients are required to complete these preliminary results. However, the present investigation seem to confirm the data already reported in the literature, i.e. that pathogenesis of MH in RP is strictly correlated to the presence of VRIA, cellophane maculopathy and cystic foveal degeneration with CME

The S-layer protein DR_2577 binds deinoxanthin and under desiccation conditions protects against UV-radiation in Deinococcus radiodurans

Deinococcus radiodurans has the puzzling ability to withstand over a broad range of extreme conditions including high doses of ultraviolet radiation and deep desiccation. This bacterium is surrounded by a surface layer (S-layer) built of a regular repetition of several proteins, assembled to form a paracrystalline structure. Here we report that the deletion of a main constituent of this S-layer, the gene DR_2577, causes a decrease in the UVC resistance, especially in desiccated cells. Moreover, we show that the DR_2577 protein binds the carotenoid deinoxanthin, a strong protective antioxidant specific of this bacterium. A further spectroscopical characterization of the deinoxanthin-DR_2577 complex revealed features which could suggest a protective role of DR_2577. We propose that, especially under desiccation, the S-layer shields the bacterium from incident ultraviolet light and could behave as a first lane of defense against UV radiation