Fast-Match: Fast Affine Template Matching

Fast-Match is a fast algorithm for approximate template matching under 2D affine transformations that minimizes the Sum-of-Absolute-Differences (SAD) error measure. There is a huge number of transformations to consider but we prove that they can be sampled using a density that depends on the smoothness of the image. For each potential transformation, we approximate the SAD error using a sublinear algorithm that randomly examines only a small number of pixels. We further accelerate the algorithm using a branch-and-bound-like scheme. As images are known to be piecewise smooth, the result is a practical affine template matching algorithm with approximation guarantees, that takes a few seconds to run on a standard machine. We perform several experiments on three different datasets, and report very good results.     

Trimeric plasmonic molecules: the role of symmetry

Artificial plasmonic molecules possess excitation modes that are defined by their symmetry and obey group theory rules, just like conventional molecules. We follow the evolution of surface-plasmon spectra of plasmonic trimers, assembled from equal-sized silver nanoparticles, as gradual geometric changes break their symmetry. The spectral modes of an equilateral triangle, the most symmetric structure of a trimer, are degenerate. This degeneracy is lifted as the symmetry is lowered when one of the vertex angles in opened, which also leads to a subtle transition between bright and dark modes. Our experimental results are quantitatively explained using numerical simulations and plasmon hybridization theory.     

Failure criteria for brittle elastic materials

The validity of several known failure initiation criteria at reentrant corners in brittle elastic materials is examined and a simple one is proposed. Their predictions, under mode I stress field, are compared to experimental observations carried out on PMMA (polymer) and Alumina-7%Zirconia (ceramic) V-notched specimens. Because all realistic V-notched reentrant corners are blunt, a detailed experimental procedure has been followed, focusing on specimens with different notch tip radii. It is demonstrated that by assuming a sharp V-notch, some failure criteria predict reasonably well the experimental findings, and that corrections are needed in order for these to take into consideration the realistic radius at the notch tip.     

Protection by inhibition of poly (ADP-ribose) synthetase against oxidant injury in cardiac myoblasts In vitro

Peroxynitrite and hydroxyl radical are reactive oxidants produced during myocardial reperfusion injury. In various cell types, including macrophages and smooth muscle cells, peroxynitrite and hydrogen peroxide cause DNA single strand breakage, which triggers the activation of the nuclear enzyme poly (ADP-ribose) synthetase (PARS), resulting in cytotoxicity. Using 3-aminobenzamide and nicotinamide, inhibitors of PARS, we investigated the role of PARS in the pathogenesis of myocardial oxidant injury in H9c2 cardiac myoblasts in vitro. Peroxynitrite (100-1000 microM), hydrogen peroxide (0.3-10 microM) and the NO donor compounds S-nitroso-N-accetyl-DL-penicillamine (SNAP) and diethyltriamine NONOate all caused a dose-dependent reduction of the mitochondrial respiration of the cells, as measured by the mitochondrial-dependent conversion of MTT to formazan. Peroxynitrite and hydrogen peroxide, but not the NO donors caused activation of cellular PARS activity. The suppression of mitochondrial respiration by peroxynitrite and hydrogen peroxide, but not by the NO donors, was ameliorated by pharmacological inhibition of PARS. The protection by the PARS inhibitors diminished at extremely high concentrations of the oxidants. Hypoxia (1 h) followed by reoxygenation (1-24 h) also resulted in a significant activation of PARS, and caused a suppression of mitochondrial respiration, which was prevented by inhibition of PARS. Similar to the results obtained with the pharmacological inhibitors of PARS, a fibroblast cell line which derives from the PARS knockout mouse was protected against the suppression of mitochondrial respiration in response to peroxynitrite and reoxygenation, but not to NO donors, when compared to the result of cells derived from wild-type animals. Based on our data, we suggest that activation of PARS plays a role in the myocardial oxidant injury.     

Interplay between sex steroids and melatonin in regulation of human benign prostate epithelial cell growth

Human benign prostatic epithelial cells contain functional melatonin receptors that can suppress cell growth and viability. The development of benign prostatic hyperplasia in men is assumed to result from androgen-estrogen imbalance. The impact of sex steroids on melatonin receptors in human benign prostate epithelial cells was investigated. The suppression by melatonin of [3H]thymidine incorporation and cGMP, and the enhancement of cAMP levels in the cells were used as markers of melatonin responses. Dihydrotestosterone (DHT) and 17 beta-estradiol (E2) separately increased [3H]thymidine incorporation into the cells, but suppressed it when combined. In cells grown with DHT, melatonin responses were extenuated. E2 greatly reduced the apparent affinity of [125I]melatonin binding in these cells without affecting binding site density. In parallel, the ability of melatonin to suppress [3H]thymidine incorporation into the cells was ablated within 1 h after the addition of E2. The melatonin-mediated increase in cAMP and decrease in cGMP concentrations were also ablated by E2. Preincubation of the cells with bis-indolylmaleimide (GF 102903X), a specific inhibitor of protein kinase C, prevented the E2-mediated inactivation of melatonin binding and the inhibitory action on [3H]thymidine incorporation. Prolonged (18-h) incubation of the cells with phorbol 12-myristate 13-acetate to down regulate protein kinase activity, partially restored [125I]melatonin binding and responsiveness in the E2-treated cells. These data indicate that 1) DHT and E2 enhance prostate epithelial cells growth, but reduce cell growth when combined; 2) DHT extenuates the inhibitory effects of melatonin on epithelial cell growth; and 3) E2 acts to inactivate melatonin receptors and consequently responses in human epithelial benign prostatic hyperplasia cells. This process is probably mediated by protein kinase C. Together, these results show an interplay between melatonin and sex steroids in the regulation of benign prostatic epithelial cell growth.     

Mixed mode failure criteria for brittle elastic V-notched structures

Three mixed mode failure initiation criteria at reentrant corners in brittle elastic materials are examined. Prediction of failure load and crack initiation angle are compared to experimental observations carried out on PMMA (polymer) and MACOR (glass ceramic) V-notched specimens. Since the mode mixity ratio influences greatly both the failure load and crack initiation angle, a detailed experimental procedure has been followed, focusing on obtaining a wide range of mode mixity ratios. It is demonstrated that by assuming a sharp V-notch tip some failure criteria predict reasonably well both the crack initiation angle and failure load.     

Production of catalase from Rhodopseudomonas spheroides

The large-scale fermentation of Rhodopseudomonas spheroides L-28, a high catalase mutant, was studied. High concentrations of cells containing high contents of catalase were obtained in a fermentor in which the culture was titrated throughout the fermentation with an organic acid. Extraction of the cells after acetone treatment resulted in a partly purified catalase suitable for industrial purposes. Increased purity could be achieved by additional purification steps.