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Optical Images (optical + image)
Selected AbstractsOptical imaging of medullary ventral respiratory network during eupnea and gasping In situEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2006Jeffrey T. Potts Abstract In severe hypoxia, respiratory rhythm is shifted from an eupneic, ramp-like motor pattern to gasping characterized by a decrementing pattern of phrenic motor activity. However, it is not known whether hypoxia reconfigures the spatiotemporal organization of the central respiratory rhythm generator. Using the in situ arterially perfused juvenile rat preparation, we investigated whether the shift from eupnea to gasping was associated with a reconfiguration of the spatiotemporal pattern of respiratory neuronal activity in the ventral medullary respiratory network. Optical images of medullary respiratory network activity were obtained from male rats (4,6 weeks of age). Part of the medullary network was stained with a voltage-sensitive dye (di-2 ANEPEQ) centred both within, and adjacent to, the pre-Bötzinger complex (Pre-BötC). During eupnea, optical signals initially increased prior to the onset of phrenic activity and progressively intensified during the inspiratory phase peaking at the end of inspiration. During early expiration, fluorescence was also detected and slowly declined throughout this phase. In contrast, hypoxia shifted the respiratory motor pattern from eupnea to gasping and optical signals were restricted to inspiration only. Areas active during gasping showed fluorescence that was more intensive and covered a larger region of the rostral ventrolateral medulla compared to eupnea. Regions exhibiting peak inspiratory fluorescence did not coincide spatially during eupnea and gasping. Moreover, there was a recruitment of additional medullary regions during gasping that were not active during eupnea. These results provide novel evidence that the shift in respiratory motor pattern from eupnea to gasping appears to be associated with a reconfiguration of the central respiratory rhythm generator characterized by changes in its spatiotemporal organization. [source] Ultrafine Electrospun Polyamide-6 Fibers: Effects of Solvent System and Emitting Electrode Polarity on Morphology and Average Fiber DiameterMACROMOLECULAR MATERIALS & ENGINEERING, Issue 9 2005Pitt Supaphol Abstract Summary: In the present contribution, polyamide-6 (PA-6) solutions were prepared in various pure and mixed-solvent systems and later electrospun with the polarity of the emitting electrode being either positive or negative. The PA-6 concentration in the as-prepared solutions was fixed at 32% w/v. Some of the solution properties, i.e., shear viscosity, surface tension, and conductivity, were measured. Irrespective of the polarity of the emitting electrode, only the electrospinning of PA-6 solution in formic acid (85 wt.-% aqueous solution) produced uniform electrospun fibers, while solutions of PA-6 in m -cresol or sulfuric acid (either 20 or 40 wt.-% aqueous solution) did not. In the mixed-solvent systems, formic acid (85 wt.-% aqueous solution) was blended with m -cresol, sulfuric acid (either 20 or 40 wt.-% aqueous solution), acetic acid, or ethanol in the compositional range of 10,40 vol.-% (based on the amount of the minor solvent). Generally, the average fiber diameter increased with increasing amount of the minor solvent or liquid. Interestingly, the diameters of the fibers obtained under the negative electrode polarity were larger than those obtained under the positive one. Optical images of electrospun fibers from solutions of polyamide-6 in a mixed solvent of 85 wt.-% formic acid and 20 vol.-% m -cresol under positive (left) and negative (right) electrode polarity. [source] Azimuthal anisotropy of light extraction from photonic crystal light-emitting diodesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2008Chun-Feng Lai Abstract Photonic crystal (PhC) light-emitting diodes (LEDs) exhibiting anisotropic light extraction have been investigated experimentally and theoretically. It is found that the anisotropic light extraction strongly depends on the lattice constant and orientation. Optical images of the anisotropy in the azimuthal direction are obtained using annular structure with triangular lattice. 6-fold symmetric light extraction patterns with varying number of petals are observed. More petals in multiple of 6 appear in the observed image with lattice constant increasing. This anisotropic behavior suggests a new means to optimize the PhC design of GaN LED for light extraction. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Self-Healing Polymers: Self-Healing Polymer Coatings (Adv. Mater.ADVANCED MATERIALS, Issue 6 20096/2009) Dramatic reduction in corrosion of a steel plate coated with a self-healing coating (right) as compared to a conventional coating is demonstrated. Two samples were scratched and placed in 5% NaCl for 5 days. The background is an optical image (2× magnification), in the foreground is an SEM image of the scratch. In the self-healing sample, the scratch has almost completely self-healed, while in the control sample, the scratch remains all the way down to the substrate, as reported by Paul Braun and co-workers on p.645. [source] Demonstration of high lateral resolution in laser confocal microscopy using annular and radially polarized lightMICROSCOPY RESEARCH AND TECHNIQUE, Issue 6 2009Jeongyong Kim Abstract The authors present the experimental result of improved lateral resolution in laser confocal microscopy (LCM) by using annular and radially polarized light as the input illumination of an existing LCM. The authors examined the lateral resolution of the LCM by imaging a single fluorescent bead and measuring the lateral width of the single bead profile appearing in the optical image. Compared to no aperture and linearly polarized light, the central peak of the single bead profile narrowed by ,40%, being as small as 122 nm in full width at half maximum using 405 nm laser excitation in a reflection imaging. In addition, the authors showed that radial polarization helps to preserve the circular shape of the single bead profile whereas linearly polarized light tends to induce an elongation along the polarization direction. Microsc. Res. Tech., 2009. © 2009 Wiley-Liss, Inc. [source] Magnifying Superlenses and other Applications of Plasmonic Metamaterials in Microscopy and SensingCHEMPHYSCHEM, Issue 4 2009Igor I. Smolyaninov Dr. Abstract Every last detail: New advances in the construction of metamaterials enable the creation of artificial optical media, whose use in microscopy can provide resolution that is not determined by the conventional diffraction limit. The picture shows a superposition of an AFM image of a plasmonic metamaterial onto the corresponding optical image obtained using a conventional optical microscope. Over the past century, the resolution of conventional optical microscopes, which rely on optical waves that propagate into the far field, has been limited because of diffraction to a value of the order of a half-wavelength (,0/2) of the light used. Although immersion microscopes have slightly improved resolution, of the order of ,0/2n, the increased resolution is limited by the small range of refractive indices n of available transparent materials. However, now we are experiencing a quick demolition of the diffraction limit in optical microscopy. In the last few years, numerous nonlinear optical microscopy techniques based on photoswitching and saturation of fluorescence have demonstrated far-field resolution of 20 to 30 nm. In a parallel development, recent progress in metamaterials has demonstrated that artificial optical media can be created, whose use in microscopy can provide resolution that is not determined by the conventional diffraction limit. The resolution of linear immersion microscopes based on such metamaterials is only limited by losses, which can be minimized by appropriate selection of the constituents of the metamaterials used and by the wavelength(s) used for imaging. It is also feasible to compensate for losses by adding gain to the structure. Thus, optical microscopy is quickly moving towards resolution of around 10 nm, which should bring about numerous revolutionary advances in lithography and imaging. [source] Fatigue damage analysis in a duplex stainless steel by digital image correlation techniqueFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 2 2008A. EL BARTALI ABSTRACT Strain field measurements by digital image correlation today offer new possibilities for analysing the mechanical behaviour of materials in situ during mechanical tests. The originality of the present study is to use this technique on the micro-structural scale, in order to understand and to obtain quantitative values of the fatigue surface damage in a two-phased alloy. In this paper, low-cycle fatigue damage micromechanisms in an austenitic-ferritic stainless steel are studied. Surface damage is observed in real time, with an in situ microscopic device, during a low-cycle fatigue test performed at room temperature. Surface displacement and strain fields are calculated using digital image correlation from images taken during cycling. A detailed analysis of optical images and strain fields measured enables us to follow precisely the evolution of surface strain fields and the damage micromechanisms. Firstly, strain heterogeneities are observed in austenitic grains. Initially, the austenitic phase accommodates the cyclic plastic strain and is then followed by the ferritic phase. Microcrack initiation takes place at the ferrite/ferrite grain boundaries. Microcracks propagate to the neighbouring austenitic grains following the slip markings. Displacement and strain gradients indicate probable microcrack initiation sites. [source] Multicriteria second-order neural networks approach to imaging through turbulenceINTERNATIONAL JOURNAL OF IMAGING SYSTEMS AND TECHNOLOGY, Issue 2 2003Yuanmei Wang Abstract Atmospheric turbulence can greatly limit the spatial resolution in optical images obtained of space objects when imaged with ground-based telescopes. Two widely used algorithms to remove atmospheric turbulence in this class of images are blind de-convolution and speckle imaging. Both algorithms are effective in removing atmospheric turbulence, but they use different types of prior knowledge and have different strengths and weaknesses. We have developed a multicriteria cross entropy minimization approach to imaging through atmospheric turbulence and a second-order neural network implementations. Our simulations illustrated the efficiency of our method. © 2003 Wiley Periodicals, Inc. Int J Imaging Syst Technol 13, 146,151, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.10037 [source] Techniques for visualization of cavern boundaries in opaque industrial mixing systemsAICHE JOURNAL, Issue 11 2009M. J. H. Simmons Abstract In the agitation of complex fluids, the avoidance of caverns is essential for successful blending. Electrical resistance tomography (ERT) and positron emission projection imaging, which can both image within opaque fluids, have been assessed for visualization of cavern boundaries. A vessel of diameter, T = 154 mm, equipped with a single 57 mm diameter six bladed 45° down pumping pitched blade disc turbine formed the test system. The fluid used was aqueous solution of carbopol 940. Both techniques were used to detect and image caverns at Re from 20,86.6 and compared with optical images. Reasonable agreement on the maximum cavern heights and widths were obtained, with the taller and narrower caverns obtained via 3D ERT measurements being attributed to artifacts of the method and interactions between the polymer and tracer. Caverns were also detectable using a robust linear ERT array, which has potential for use within industrial systems. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Towards automation of palynology 2: the use of texture measures and neural network analysis for automated identification of optical images of pollen grains,JOURNAL OF QUATERNARY SCIENCE, Issue 8 2004P. LI Abstract The automation of palynology (the identification and counting of pollen grains and spores) will be a small step for image recognition, but a giant stride for palynology. Here we show the first successful automated identification, with 100% accuracy, of a realistic number of taxa. The technique used involves a neural network classifier applied to surface texture data from light microscope images. A further significance of the technique is that it could be adapted for the identification of a wide range of biological objects, both microscopic and macroscopic. Copyright © 2004 John Wiley & Sons, Ltd. [source] Near-field probing of photonic crystal directional couplersLASER PHYSICS LETTERS, Issue 6 2006V. S. Volkov Abstract We report the design, fabrication and characterization of a photonic crystal directional coupler with a size of ,20 × 20 µm2 fabricated in silicon-on-insulator material. Using a scanning near-field optical microscope we demonstrate a high coupling efficiency for TM polarized light at telecom wavelengths. By comparing the near-field optical images recorded in and after the directional coupler area, the features of light distribution are analyzed. Finally, the scanning near-field optical microscope observations are found to be in agreement with the transmission measurements conducted with the same sample. (© 2006 by Astro, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Near-field mapping of surface refractive-index distributionsLASER PHYSICS LETTERS, Issue 9 2005I.P. Radko Abstract Scanning near-field optical microscopy (SNOM) in reflection is employed for high-resolution mapping of surface refractive-index distributions. Two different single-mode optical fibers with step-index profiles are characterized using a reflection SNOM setup, in which cross-polarized detection is employed to increase the contrast in optical images and, thereby, the method sensitivity. The SNOM images exhibit a clear ring-shaped structure associated with the fiber step-index profile, indicating that surface refractive-index variations being smaller than 10,2 can be detected. It is found that the quantitative interpretation of SNOM images requires accurate characterization of a fiber tip used, because the detected optical signal is a result of interference between the optical fields reflected by the sample surface and by the fiber tip itself. The possibilities and limitations of this experimental technique are discussed. (© 2005 by Astro, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Delineating melanoma using multimodal polarized light imagingLASERS IN SURGERY AND MEDICINE, Issue 1 2009Zeina Tannous Abstract Background and Significance Melanoma accounts for 3% of all skin cancers but causes 83% of skin cancer deaths. The first step in treatment of melanoma is the removal of the lesions, usually by surgical excision. Currently most lesions are removed without intraoperative margin control. Post-operative methods inspect 1,2% of the surgical margin and are prone to sampling errors. In this study we evaluate the use of reflectance and fluorescence polarization imaging for the demarcation of melanoma in thick fresh skin excisions. Materials and Methods Pigmented lesions clinically suspicious for melanoma were elliptically excised with proper margins. Elliptical surgical excisions were vertically bisected along the short axis of the specimen into two halves in the middle of the pigmented lesions. The vertically bisected tumor face was imaged. After that, one half of the sample was briefly stained in aqueous 2 mg/ml solution of tetracycline, whereas another half was stained in 0.2 mg/ml aqueous solution of methylene blue. Then both specimens were reimaged. Reflectance images were acquired in the spectral range between 390 and 750 nm. Fluorescence images of the tetracycline-stained tissue were excited at 390 nm and registered between 450 and 700 nm. Fluorescence of the methylene blue-stained samples was excited at 630 nm and registered between 650 and 750 nm. After imaging, the tissue was processed for standard H&E histopathology. The resulting histological and optical images were compared to each other. Results and Conclusions Our findings demonstrate that both tetracycline and methylene blue are suitable for imaging dysplastic and benign nevi. Melanoma is better delineated in the samples stained in methylene blue. Accurate and rapid delineation of melanoma in standard fresh surgical excisions appears feasible. Lasers Surg. Med. 41:10,16, 2009. © 2008 Wiley-Liss, Inc. [source] Super-resolution bright-field optical microscopy based on nanometer topographic contrastMICROSCOPY RESEARCH AND TECHNIQUE, Issue 4-5 2004Shu-Wei Huang Abstract By using an expectation-maximization maximum likelihood estimation algorithm to improve the lateral resolution of a recently developed non-interferometric wide-field optical profilometer, we obtain super-resolution bright-field optical images of nanometer features on a flat surface. The optical profilometer employs a 365-nm light source and an ordinary objective lens of a 0.95 numerical aperture. For objects of 100 nm thickness, lateral features about ,/7 can be resolved in the restored images without fluorescence labeling. Current image acquisition rate is 0.1 frame/sec, which is limited by the brightness of the light source. With a brighter light source, the imaging speed can be fast enough for real-time observation of dynamic activities in the nanometer scale. Microsc. Res. Tech. 65:180,185, 2004. © 2005 Wiley-Liss, Inc. [source] Infrared [Fe ii] emission in the circumstellar nebulae of luminous blue variablesMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2002Nathan Smith Abstract After a serendipitous discovery of bright [Fe ii],16435 emission in nebulae around , Carinae and P Cygni, infrared spectra of other luminous blue variables (LBV) and LBV candidates were obtained. Bright infrared [Fe ii] emission appears to be a common property among LBVs with prominent nebulae; this is an interesting discovery because strong [Fe ii],16435 is typically seen in shock-excited objects like supernova remnants and outflows from newly formed massive stars, as well as in active galactic nuclei (AGN), where the excitation mechanism is uncertain. This paper presents spectra in the H-band (1.5 to 1.75 ,m) for the central stars and nebulae of , Car, AG Car, P Cyg, Wra 751, HR Car, HD 168625, HD 160529, R 127 and S Doradus. Seven of nine targets show bright [Fe ii],16435 in their nebulae, while it is absent in all central stars except the LBV candidate Wra 751. The two objects (S Dor and HD 160529) without prominent [Fe ii],16435 are not yet known to have nebulae detected in optical images, and both lack bright thermal infrared emission from dust. The possible excitation mechanisms for this line and the implications of its discovery in LBV nebulae are discussed; there are good reasons to expect shock excitation in some objects, but other mechanisms cannot be ruled out. [source] Design of a slim optical image stabilization actuator for mobile phone camerasPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2007Hsing-Cheng Yu Abstract Mechanical optical image stabilization actuator (OISA) will quickly become a standard feature in a high resolution mobile phone camera (MPC) and the quantity of MPC will exceed that of digital still cameras in several years. Whenever jitter arises from shaky hands or environment in taking photos, optical images projected upon an image sensor blur. Designing a slim OISA in MPC is an effective solution that addresses image quality. Therefore, this work presents a slim OISA utilized in MPC to compensate jitter form camera shake in taking photos. Two proportional-integral-derivative controllers based on transfer functions for dual axes of the slim OISA system in MPC obtained from system identification have been designed. The settling time of dual axes are less than 0.03 sec. Furthermore, a thrust ball bearing in this study has reduced the friction force between the movable and the stationary parts, so as to minimize the driving current to be less than 5 mA. Hence, the slim OISA has satisfied low power consumption requirement, and is also possible to reduce dimension in the MPC application. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Gas and stars in compact (young) radio sourcesASTRONOMISCHE NACHRICHTEN, Issue 2-3 2009R. Morganti Abstract Gas can be used to trace the formation and evolution of galaxies as well as the impact that the nuclear activity has on the surrounding medium. For nearby compact radio sources, we have used observations of neutral hydrogen , that we detected in emission distributed over very large scales , combined with the study of the stellar population and deep optical images to investigate the history of the formation of their host galaxy and the triggering of the activity. For more distant and more powerful compact radio sources, we have used optical spectra and H I , in absorption , to investigate the presence of fast outflows that support the idea that compact radio sources are young radio loud AGN observed during the early stages of their evolution and currently shredding their natal cocoons through extreme circumnuclear outflows. We will review the most recent results obtained from these projects (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Development of a Quadruple Imaging Modality by Using NanoparticlesCHEMISTRY - A EUROPEAN JOURNAL, Issue 37 2009Won Hwang Abstract The combination of nanotechnology with molecular imaging has great potential for the development of diagnostics and therapeutics, and multimodal imaging enables versatile applications from cell tracking in animals to clinical applications. Herein, we report a multimodal nanoparticle imaging system that is capable of concurrent fluorescence, bioluminescence, bioluminescence resonance energy transfer (BRET), positron emission tomography (PET) and magnetic resonance (MR) imaging in vivo. A cobalt,ferrite nanoparticle surrounded by rhodamine (MF) was conjugated with luciferase (MFB) and p -SCNbnNOTA (2-(4-isothiocyanatobenzyl)-1,4,7-triazacyclonane-1,4,7-triacetic acid) followed by 68GaCl3 (magnetic-fluorescent-bioluminescent-radioisotopic particle, MFBR). Confocal microscopy revealed good transfection efficiency of MFB into cells and BRET was also observed in MFB. A good correlation among rhodamine, luciferase, and 68GaCl3 was found in MFBR, and the activities of each imaging modality increased dose-dependently with the amount of MFBR in the C6 cells. In vivo optical images were acquired from the thighs of mice after intramuscular and subcutaneous injections of MFBR-laden cells. MicroPET and MR images showed intense radioactivity and ferromagnetic intensities with MFBR-laden cells. The multimodal imaging strategy could be used as potential imaging tools to track cells. [source] | |||||||||||||||||||