OCR binarization and image pre-processing for searching historical documents

We consider the problem of document binarization as a pre-processing step for optical character recognition (OCR) for the purpose of keyword search of historical printed documents. A number of promising techniques from the literature for binarization, pre-filtering, and post-binarization denoising were implemented along with newly developed methods for binarization: an error diffusion binarization, a multiresolutional version of Otsu's binarization, and denoising by despeckling. The OCR in the ABBYY FineReader 7.1 SDK is used as a black box metric to compare methods. Results for 12 pages from six newspapers of differing quality show that performance varies widely by image, but that the classic Otsu method and Otsu-based methods perform best on average.     

YedY: A Mononuclear Molybdenum Enzyme with a Redox‐Active Ligand?

A recent electrochemical investigation suggests that the mononuclear molybdenum enzyme YdeY utilizes redox‐active ligands during catalysis.     

Stress-relaxation behavior in gels with ionic and covalent crosslinks

Long-chained polymers in alginate hydrogels can form networks by either ionic or covalent crosslinks. This paper shows that the type of crosslinks can markedly affect the stress-relaxation behavior of the gels. In gels with only ionic crosslinks, stress relaxes mainly through breaking and subsequent reforming of the ionic crosslinks, and the time scale of the relaxation is independent of the size of the sample. By contrast, in gels with only covalent crosslinks, stress relaxes mainly through migration of water, and the relaxation slows down as the size of the sample increases. Implications of these observations are discussed.     

Enhanced spatiotemporal relational probability trees and forests

Many real world domains are inherently spatiotemporal in nature. In this work, we introduce significant enhancements to two spatiotemporal relational learning methods, the spatiotemporal relational probability tree and the spatiotemporal relational random forest, that increase their ability to learn using spatiotemporal data. We enabled the models to formulate questions on both objects and the scalar and vector fields within and around objects, allowing the models to differentiate based on the gradient, divergence, and curl and to recognize the shape of point clouds defined by fields. This enables the model to ask questions about the change of a shape over time or about its orientation. These additions are validated on several real-world hazardous weather datasets. We demonstrate that these additions enable the models to learn robust classifiers that outperform the versions without these new additions. In addition, analysis of the learned models shows that the findings are consistent with current meteorological theories.     

Domain patterns in free-standing nanoferroelectrics

A real space three-dimensional (3-D) Ginzburg–Landau framework is used to investigate the domain patterns in free-standing ferroelectric nanostructures undergoing cubic to tetragonal transitions. The study is motivated by the recent progress in fabricating free-standing single crystalline ferroelectric nanostructures which exhibit complex ferroelastic domain patterns. We demonstrate that for nanostructures with uncompensated surface charges internal stresses generated due to the coupling between electrostatic and elastic interactions can induce bulk-like ferroelastic domain patterns in free-standing ferroelectrics, without invoking any extrinsic mechanisms such as non-transforming surface layers. Further, we show that for very small structures the interplay between electrostatics and elasticity leads to a large diversity of domain patterns that can be observed in 3-D free-standing nanostructures.     

Hetero‐bivalent GLP‐1/Glibenclamide for Targeting Pancreatic β‐Cells

G protein‐coupled receptor (GPCR) cell signalling cascades are initiated upon binding of a specific agonist ligand to its cell surface receptor. Linking multiple heterologous ligands that simultaneously bind and potentially link different receptors on the cell surface is a unique approach to modulate cell responses. Moreover, if the target receptors are selected based on analysis of cell‐specific expression of a receptor combination, then the linked binding elements might provide enhanced specificity of targeting the cell type of interest, that is, only to cells that express the complementary receptors. Two receptors whose expression is relatively specific (in combination) to insulin‐secreting pancreatic β‐cells are the sulfonylurea‐1 (SUR1) and the glucagon‐like peptide‐1 (GLP‐1) receptors. A heterobivalent ligand was assembled from the active fragment of GLP‐1 (7–36 GLP‐1) and glibenclamide, a small organic ligand for SUR1. The synthetic construct was labelled with Cy5 or europium chelated in DTPA to evaluate binding to β‐cells, by using fluorescence microscopy or time‐resolved saturation and competition binding assays, respectively. Once the ligand binds to β‐cells, it is rapidly capped and presumably removed from the cell surface by endocytosis. The bivalent ligand had an affinity approximately fivefold higher than monomeric europium‐labelled GLP‐1, likely a result of cooperative binding to the complementary receptors on the βTC3 cells. The high‐affinity binding was lost in the presence of either unlabelled monomer, thus demonstrating that interaction with both receptors is required for the enhanced binding at low concentrations. Importantly, bivalent enhancement was accomplished in a cell system with physiological levels of expression of the complementary receptors, thus indicating that this approach might be applicable for β‐cell targeting in vivo.     

Redox polymer covalently modified multiwalled carbon nanotube based sensors for sensitive acetaminophen and ascorbic acid detection

A sensitive electrochemical detection method was developed involving multiwalled carbon nanotubes (MWCNTs) covalently modified with osmium-based redox polymer. The polycationic redox polymer, poly[4-vinylpyridine Os(bipyridine)₂Cl]-co-ethylamine (POs-EA), was first synthesized and covalently attached to MWCNTs. The redox polymer modified MWCNTs were then trapped in a hydrogel formed from polyethyleneglycol diacrylate (PEG-DA) using 1-phenyl-2-hydroxy-2-methyl-1-propanone as a photoinitiator. Upon exposure to aqueous media, the gel swelled to allow movement of analytes in and out of the gel without having any effect on the redox polymer modified nanotube signal. Cyclic voltammetry showed reversible pairs of oxidation-reduction peaks at 0.35 V (vs Ag/AgCl) corresponding to the Os^II/Os^III. This assembly was able to catalytically oxidize both acetaminophen and ascorbic acid (AA). Amperometric data showed a linearity between 0 and 100 μM (R² of 0.999, n = 10) 0.5 mV vs Ag/AgCl (sensitivity 0.003 μA/μM) for ascorbic acid, while for acetaminophen the linearity was between 0 and 1.5 μM (R² of 0.9999, n = 8) with a sensitivity of 65 μA/μM. This sensing system was found to exhibit remarkable stability over several weeks with excellent reproducibility.     

Metal nanofibers with highly tunable electrical and magnetic properties via highly loaded water-based electrospinning

Nanofibers are synthesized by electrospinning highly loaded water-based precursor-polymer hybrid solutions followed by thermal treatment to control crystal structure. Electrical conductivity and magnetic coercivity, as shown, are tested displaying independent magnetic and electrical property control from coercive to superparamagnetic and resistive to near-bulk conductivity at room temperature.     

Rapid polarizing field cycling in magnetic resonance imaging

We describe the electronics for controlling the independently pulsed polarizing coil in a prepolarized magnetic resonance imaging (PMRI) system and demonstrate performance with free induction decay measurements and in vivo imaging experiments. A PMRI scanner retains all the benefits of acquiring MRI data at low field, but with the higher signal of the polarizing field. Rapidly and efficiently ramping the polarizing coil without disturbing the data acquisition is one of the major challenges of PMRI. With our modular hardware design, we successfully ramp the 0.4-T polarizing coil of a wrist-sized PMRI scanner at up to 100 T/s without causing image artifacts or otherwise degrading data acquisition.