Sparse Occlusion Detection with Optical Flow

We tackle the problem of detecting occluded regions in a video stream. Under assumptions of Lambertian reflection and static illumination, the task can be posed as a variational optimization problem, and its solution approximated using convex minimization. We describe efficient numerical schemes that reach the global optimum of the relaxed cost functional, for any number of independently moving objects, and any number of occlusion layers. We test the proposed algorithm on benchmark datasets, expanded to enable evaluation of occlusion detection performance, in addition to optical flow.     

A cognition-centered personalization framework for cultural-heritage content

User Modeling and User-Adapted Interaction - The heterogeneity of the audience of cultural heritage institutions introduces numerous challenges to the delivery of the content. Considering that...     

Pilot study of 5-azacytidine (5-AZA) and carboplatin (CBDCA) in patients with relapsed/refractory leukemia

The principle of bowel detubularization to decrease peristaltic pressure and increase reservoir capacity is applied in contemporary continent urinary diversions. The process of detubularization and refashioning of the spatulated bowel segment approximates 1 of operating time and is the most time-consuming aspect of pouch construction. The employment of devices applying absorbable staples ("absorbable staplers") has substantially reduced the time required to fashion bowel reservoirs. This article reviews the adaptation of the absorbable stapler to continent urinary diversion using small- and large-bowel segments.     

Lithographically fabricated disposable bismuth-film electrodes for the trace determination of Pb(II) and Cd(II) by anodic stripping voltammetry

This work reports the photolithographic fabrication of disposable bismuth-film electrodes (BiFEs) using a thin-film deposition approach. The deposition of the bismuth layer was carried out by sputtering of metallic bismuth on a silicon substrate while the exact geometry of the BiFEs was produced by photolithography. The utility of these sensors was tested for the simultaneous trace determination of Cd(II) and Pb(II) by square wave anodic stripping voltammetry (SWASV). Using the selected conditions, the limits of detection were 0.5 μg l⁻¹ for Pb(II) and 1 μg l⁻¹ for Cd(II) at a preconcentration time of 4 min. The interference caused by Cu(II) was alleviated by the addition of ferrocyanide in the sample solution. Finally, the proposed BiFEs were successfully applied to the determination of Cd and Pb in a phosphate fertilizer and a river water sample. These sensors offer wide scope for trace metal analysis in terms of mass-production of mercury-free disposable sensors with performance comparable to their mercury counterparts.     

Tamoxifen metabolite isomer separation and quantification by liquid chromatography-tandem mass spectrometry

Tamoxifen (Tam), the antiestrogen used to treat estrogen receptor-positive breast cancer is a pro-drug that is converted to its major active metabolites, endoxifen and 4-hydroxy-tamoxifen (4-OH-Tam) by various biotransformation enzymes of which cytochrome P450-2D6 (CYP2D6) is key. The usual Tam dose is 20 mg daily; however, the plasma active metabolite concentrations vary due to common genetic variants encoding the biotransformation enzymes and environmental factors (e.g., concomitant drugs) that inhibit these enzymes. Effective treatment depends on adequate Tam conversion to its active isomers. To monitor metabolite plasma levels, a novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed to separate and quantitate Tam, N-desmethyl-tamoxifen (ND-Tam), and tamoxifen-N-oxide (Tam-N-oxide), and the E, Z, and Z' isomers of endoxifen and 4-OH-Tam. Known standards were used to identify each metabolite/isomer. Quantitation of these metabolites in plasma was linear from 0.6 to 2000 nM. Intra- and inter-assay reproducibilities were 0.2-8.4% and 0.6-6.3%, respectively. Accuracy determined by spike experiments with known standards was 86-103%. Endoxifen, 4-OH-Tam, and their isomers were stable in fresh frozen plasma for ≥6 months. This method provides the first sensitive, specific, accurate, and reproducible quantitation of Tam and its metabolite isomers for monitoring Tam-treated breast cancer patients.     

Swelling and dissolution behavior of poly(methyl methacrylate) films in methyl ethyl ketone/methyl alcohol mixtures studied by optical techniques

Swelling and dissolution behavior of poly(methyl methacrylate) (PMMA) films during unidimensional penetration of methyl ethyl ketone/methyl alcohol (MEK/MA) liquid mixtures at 22°C is presented. Optical microscopy and two‐beam interferometry were applied to clamped PMMA films to obtain information on penetration kinetics and penetrant concentration profiles. Dissolution by pure MEK was initially controlled by Case II penetration kinetics and at later stages of the process, by stress cracking in the absence of a surface layer. Introduction of increasing amounts of MA in the liquid solvent resulted in moderation of the fragmentation process, enhanced penetration rates at the early stages of the process, deviations from Case II kinetics at the later stages, and the existence of a surface layer. These results indicate that penetration of MEK/MA mixtures and dissolution of PMMA are characterized by lower diffusion Deborah, and higher dissolution, numbers compared to those of pure MEK. Swelling by pure MA, as well as by nonsolvent MEK/MA mixtures, was characterized by Case II penetration kinetics. A pronounced minimum in the penetration rate versus liquid mixture composition plot was observed at 30 : 70 v/v MEK/MA composition. Laser interferometry was applied to very thin PMMA films, supported on a silicon substrate, to study selected cases. The results obtained were very similar to those obtained by optical microscopy. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2823–2834, 2002; DOI 10.1002/app.10258     

In situ monitoring of thermal transitions in thin polymeric films via optical interferometry

A novel, low-cost, rapid, accurate, non-invasive and high throughput method based on the principles of Optical Interferometry (OPTI method) has been developed and applied for the in situ monitoring in one simple run of first (melting) and second (glass transition) order transitions as well as of the thermally induced decomposition of various thin polymeric films spin coated on flat reflective substrates (untreated silicon wafers). The new method has been applied successfully for measuring the glass transition, melting and decomposition temperatures of six commercially available polymers [poly(methyl methacrylate) (PMMA), poly(2-hydroxyethyl methacrylate), (PHEMA), poly(vinyl acetate-co-crotonic acid), (PVACA), poly(vinyl pyrrolidone) (PVP), poly(vinyl chloride-co-vinyl acetate) (PVCVA) and crystalline poly(vinylidene fluoride-co-hexafluoropropylene) (PVFHP)] of known T_gs or T_ms. The recorded interferometric signals were identified and characteristic signal patterns were qualitatively correlated to specific transitions. The monitoring of first and second order transitions in thin polymeric films is based on detectable differentiations of the total energy of a fixed wavelength laser beam incident almost vertically (angle of incidence <5°) onto a thin polymeric film spin coated on a flat reflective substrate. These differentiations are caused by film thickness and/or refractive index changes of the polymeric film both resulted from the significant change of the polymer's free volume taking place on the transitions. For film thicknesses over approx. 200-250 nm, the T_g or T_m of the polymeric films measured with the OPTI method were in excellent agreement with the corresponding values of the polymer, measured by DSC. An investigation on the trends of the T_g of PHEMA and PMMA films in a wide thickness range (30-1735 nm) was also carried out. Ultra-thin (∼30 nm) films of PMMA and PHEMA showed significant increase in their T_g values by approx. 30 °C upon comparing to their corresponding bulk T_gs. This behavior was attributed to an enhanced polymer-surface interaction through hydrogen bonding and/or to changes in the tacticity of the polymer.     

Raman enhancement of rhodamine adsorbed on Ag nanoparticles self-assembled into nanowire-like arrays

ABSTRACT: This work reports on Raman scattering of rhodamine (R6G) molecules absorbed on either randomly distributed or grating-like arrays of approximately 8-nm Ag nanoparticles developed by inert gas aggregation. Optimal growth and surface-enhanced Raman scattering (SERS) parameters have been obtained for the randomly distributed nanoparticles, while effects related to the aging of the silver nanoparticles were studied. Grating-like arrays of nanoparticles have been fabricated using line arrays templates formed either by fracture-induced structuring or by standard lithographic techniques. Grating structures fabricated by both methods exhibit an enhancement of the SERS signal, in comparison to the corresponding signal from randomly distributed Ag nanoparticles, as well as a preferential enhancement in the areas of the sharp features, and a dependence on the polarization direction of the incident exciting laser beam, with respect to the orientation of the gratings structuring. The observed spectroscopic features are consistent with a line-arrangement of hot-spots due to the self- alignment of metallic nanoparticles, induced by the grating-like templates.     

An alternative approach of acousto-ultrasonic technique formonitoring material anisotropy of fiber-reinforced composites

An alternative acousto-ultrasonic (AU) technique has been developed for nondestructive evaluation (NDE) of fiber-reinforced composites. The technique measures the time of flight (TOF) of AU waves, instead of the stress wave factor, by two low-frequency (0.5 MHz) transducers and relates TOF to material properties and fiber orientation. As the transducer separation increases, the measured time-domain AU signals clearly separate into two groups, since the excitation is under the first critical frequency, which correspond to the first two fundamental modes of the Lamb waves. One is an antisymmetric mode with slower propagation velocity and is highly dispersive, while the other is a symmetric mode with faster propagation velocity, which is very close to that of the longitudinal bulk wave, and is nearly nondispersive. The phase velocity in the composites can be accurately determined from the slopes of the TOF curves, and depends strongly on the azimuthal angle, frequency, and plate thickness. If the wave propagates away from the fiber direction, a slower but more attenuated wave is observed. Phase-velocity curves in azimuthal angles were obtained for E-glass/polyester, S-2-glass/epoxy, and Kevlar 49 composites. The theoretical solutions, for the longitudinal bulk wave and Lamb wave, are obtained by solving an eigenproblem once the material mechanical properties are defined. Good agreement is obtained between the measurements and the theoretical calculations     

Effects of annealing atmosphere and substrate on the photoluminescence and Raman scattering from Si nanocrystals in a SiO2 matrix

Thin films of SiO _x have been prepared on quartz or c-Si substrates by thermal evaporation of SiO in vacuum and post-annealed at 1373 K in an argon or hydrogen atmosphere. High-resolution electron microscopy has shown the existence of silicon nanocrystals in the annealed films, and this result has been confirmed by Raman scattering. Photoluminescence has been observed from annealed films and attributed to radiative recombination in Si nanocrystals. Its intensity is appreciably higher upon annealing in Ar than in H₂. It is shown that substrates strongly affect the Raman scattering from Si nanocrystals in nc-Si–SiO₂ thin films with low filling factors.