General adaptive-neighborhood technique for improving synthetic aperture radar interferometric coherence estimation

A new method for filtering the coherence map issued from synthetic aperture radar (SAR) interferometric data is presented. For each pixel of the interferogram, an adaptive neighborhood is determined by a region-growing technique driven by the information provided by the amplitude images. Then pixels in the derived adaptive neighborhood are complex averaged to yield the filtered value of the coherence, after a phase-compensation step is performed. An extension of the algorithm is proposed for polarimetric interferometric SAR images. The proposed method has been applied to both European Remote Sensing (ERS) satellite SAR images and airborne high-resolution polarimetric interferometric SAR images. Both subjective and objective performance analysis, including coherence edge detection, shows that the proposed method provides better results than the standard phase-compensated fixed multilook filter and the Lee adaptive coherence filter.     

A small gain theorem for linear stochastic systems

A well-known result in linear control theory is the so-called “small gain” theorem stating that if given two plants with transfer matrix functions T₁ and T₂ in H^∞ such that T₁ < γ and T₂ < 1/γ, when coupling T₂ to T₁ such that u₂ = y₁ and u₁ = y₂ one obtains an internally stable closed system. The aim of the present paper is to describe a corresponding result for stochastic systems with state-dependent white noise.     

Broadband bulk-wave cancellation in acoustic-surface-wave devices

The two halves of a split transducer are arranged so that bulk-wave spurious transmission is cancelled. The surface-wave radiations from the two halves are made to reinforce each other by means of a phase shifter which affects only the surface wave.     

Early and late effects of erythropoietin on glucose metabolism in maintenance hemodialysis patients

The effects of recombinant human erythropoietin (rHuEPO) on the glucose metabolism were evaluated by intravenous glucose tolerance test in 20 maintenance hemodialysis patients. In 8 cases the glucose tolerance tests were performed before and after a single intravenous injection of 50 IU/kg of rHuEPO and in 12 cases before and after 3 months of rHuEPO therapy at doses of 50 IU/kg three times/week and 2 weeks after rHuEPO withdrawal. For each test glucose, immunoreactive insulin (IRI) and C peptide (C-p) plasma values were measured, and glucose constant decay, whole IRI (area IRI) and C-p area C-p) production, insulinogenic index, and insulin resistance index were calculated. After 3 months of rHuEPO therapy, the glucose constant decay increased significantly, area IRI, area C-p, and insulin resistance index decreased significantly, and the insulinogenic index did not change. No correlations were found between changes in hemoglobin values and changes in glucose metabolism parameters. Acute rHuEPO administration and rHuEPO withdrawal had no effect on glucose metabolism, despite significant changes in plasma erythropoietin levels. Long-term rHuEPO therapy improves glucose metabolism in maintenance hemodialysis patients significantly, mainly by reduction of insulin resistance. Neither anemia correction nor a direct effect of rHuEPO on some metabolic steps seem to be responsible of these effects.     

Capitalization and punctuation restoration: a survey

Ensuring proper punctuation and letter casing is a key pre-processing step towards applying complex natural language processing algorithms. This is especially significant for textual sources where punctuation and casing are missing, such as the raw output of automatic speech recognition systems. Additionally, short text messages and micro-blogging platforms offer unreliable and often wrong punctuation and casing. This survey offers an overview of both historical and state-of-the-art techniques for restoring punctuation and correcting word casing. Furthermore, current challenges and research directions are highlighted.

     

Microgrooving and microthreading tools for fabricating curvilinear features

This paper presents techniques for fabricating microscopic, curvilinear features in a variety of workpiece materials. Microgrooving and microthreading tools with cutting widths as small as 13 μm are made by focused ion beam sputtering and used for ultraprecision machining. Tool fabrication involves directing a 20 keV gallium beam at polished cylindrical punches made of cobalt M42 high-speed steel or C2 tungsten carbide to create a number of critically aligned facets. Sputtering produces rake facets of desired angle and cutting edges having radii of curvature equal to 0.4 μm. Clearance for minimizing frictional drag of a tool results from a particular ion beam/target geometry that accounts for the sputter yield dependence on incidence angle. It is believed that geometrically specific cutting tools of this dimension have not been made previously. Numerically controlled, ultraprecision machining with microgrooving tools results in a close match between tool width and feature size. Microtools are used to machine 13-μm wide, 4-μm deep, helical grooves in polymethyl methacrylate and 6061 Al cylindrical workpieces. Microgrooving tools are also used to fabricate sinusoidal cross-sectional features in planar metal samples.     

Recent advances in synthesis, characterization of hydroxyapatite/polyurethane composites and study of their biocompatible properties

The development of engineered biomaterials that mimic bone tissues is a promising research area that benefits from a growing interest. Polymers and polymer–ceramic composites are the principle materials investigated for the development of synthetic bone scaffolds thanks to their proven biocompatibility and biostability. Several polymers have been combined with calcium phosphates (mainly hydroxyapatite) to prepare nanocomposites with improved biocompatible and mechanical properties. Here, we report the hydrothermal synthesis in high pressure conditions of nanostructured composites based on hydroxyapatite and polyurethane functionalized with carboxyl and thiol groups. Cell-material interactions were investigated for potential applications of these new types of composites as coating for orthopedic implants. Physical–chemical and morphological characteristics of hydroxyapatite/polyurethane composites were evaluated for different compositions, showing their dependence on synthesis parameters (pressure, temperature). In vitro experiments, performed to verify if these composites are biocompatible cell culture substrates, showed that they are not toxic and do not affect cell viability.     

One‐Pot Hydroacetylation of Menadione (Vitamin K3) to Menadiol Diacetate (Vitamin K4) by Heterogeneous Catalysis

Vitamin K₄ (menadiol diacetate, MDD) can be easily synthesized through cleaner and more efficient catalytic alternatives following the green chemistry principles. Ionic gold‐based hydroxylated fluorides are active bi‐functional catalysts for the one‐pot hydroacetylation of menadione leading to MDD with 77% selectivity. Unprecedent results were obtained in the presence of oxide‐fluoride catalysts by using a microwave‐assisted hydrogen‐transfer (Meerwein–Ponndorf–Verley reaction) coupled with an acetylation approach, yielding very high selectivities for the target product (95%).