Fully automated corneal endothelial morphometry of images captured by clinical specular microscopy

NASA Astrophysics Data System (ADS)

Bucht, Curry; Söderberg, Per; Manneberg, Göran

2009-02-01

The corneal endothelium serves as the posterior barrier of the cornea. Factors such as clarity and refractive properties of the cornea are in direct relationship to the quality of the endothelium. The endothelial cell density is considered the most important morphological factor. Morphometry of the corneal endothelium is presently done by semi-automated analysis of pictures captured by a Clinical Specular Microscope (CSM). Because of the occasional need of operator involvement, this process can be tedious, having a negative impact on sampling size. This study was dedicated to the development of fully automated analysis of images of the corneal endothelium, captured by CSM, using Fourier analysis. Software was developed in the mathematical programming language Matlab. Pictures of the corneal endothelium, captured by CSM, were read into the analysis software. The software automatically performed digital enhancement of the images. The digitally enhanced images of the corneal endothelium were transformed, using the fast Fourier transform (FFT). Tools were developed and applied for identification and analysis of relevant characteristics of the Fourier transformed images. The data obtained from each Fourier transformed image was used to calculate the mean cell density of its corresponding corneal endothelium. The calculation was based on well known diffraction theory. Results in form of estimated cell density of the corneal endothelium were obtained, using fully automated analysis software on images captured by CSM. The cell density obtained by the fully automated analysis was compared to the cell density obtained from classical, semi-automated analysis and a relatively large correlation was found.

Ophthalmic parameters in adult lowland paca (Cuniculus paca) raised in captivity.

PubMed

Balthazar da Silveira, Camila P; Lima, Tiago B; Crivelaro, Roberta M; de Lacerda, Luciana C C; Pádua, Ivan R M; Renzo, Roberta; de Barros Sobrinho, Alexandre A F; Oliveira, Fabrício S; Aldrovani, Marcela; Laus, José L

2018-01-01

To investigate the ophthalmic parameters of lowland pacas, including the anatomic features, tear production, intraocular pressure, central corneal thickness, and morphology of the corneal endothelium. Thirteen adult, anesthetized Cuniculus paca. Eyes were evaluated using slit-lamp biomicroscopy, the Schirmer tear test I, digital applanation tonometry, binocular indirect ophthalmoscopy, and noncontact specular microscopy. The biomicroscopy findings showed blue/brown pigmented bulbar conjunctivae, well-developed cilia (only in the upper eyelid margin), superior and inferior lacrimal puncta, brown irides, round pupils, and vestiges of the nictitating membrane. The results of the Schirmer tear test I revealed (mean ± SD) a lacrimation rate of 4.10 ± 0.44 mm/min. The intraocular pressure was 6.34 ± 0.43 mmHg. Central corneal thickness measured by specular microscopy was 0.35 ± 0.01 mm. The mean values of density, hexagonality, and the area of the endothelial cells were 2083.15 ± 42.47 cells/mm 2 , 67.07 ± 3.30%, and 486.30 ± 9.56 μm 2 , respectively. The ocular parameters defined in this study may be used for reference in future studies and might also contribute to therapeutic approaches appropriate to this species. © 2017 American College of Veterinary Ophthalmologists.

Breathable NIPAAm Network with Controllable Hydration Supports Model Lipid Membrane

NASA Astrophysics Data System (ADS)

Jablin, Michael; Smith, Hillary; Zhernenkov, Mikhail; Vidyasagar, Ajay; Toomey, Ryan; Saiz, Jessica; Toperverg, Boris; Watkins, Erik; Kuhl, Tonya; Hurd, Alan; Majewski, Jaroslaw

2009-03-01

The interaction of a model lipid bilayer composed of DPPC with a surface-tethered poly(N-isopropylacrylamide) (NIPAAm) was explored with neutron reflectometry (NR). The Langmuir-Blodgett / Langmuir-Schaeffer method was used to deposit a lipid bilayer onto the polymer. NR measurements were used to probe the in- and out-of-plane structure of the system as a function of temperature. NR with fluorescence microscopy show that the polymer supports a lipid bilayer, and hydration of the support can be controlled. At low temp. the membrane develops out-of-plane undulations visible in off-specular scattering. Analysis of the off-specular reveals in-plane correlation of the bilayer fluctuations. The separation of the lipid bilayer from the solid support of a substrate constitutes a significant step towards a more realistic model of biological membranes.

Use of specular microscopy to determine corneal endothelial cell morphology and morphometry in enucleated cat eyes.

PubMed

Franzen, Angela A; Pigatto, João A T; Abib, Fernando C; Albuquerque, Luciane; Laus, José L

2010-07-01

The purpose of this study was to investigate the effect of age on endothelial morphology and morphometry in cats. The corneal endothelium was studied using a contact specular microscope. A total of 18 cats (Felis catus Linnaeus, 1758) were evaluated in this study. The subjects were divided into three groups of six cats each in function of age: G1 (1 to 3 months old), G2 (5 to 12 months old), and G3 (24 to 40 months old). The examination presented data as endothelial cell density (ECD), average cell area, corneal thickness, polymegathism, and pleomorphism. Results revealed ECD decrease in corneas of normal cats with age, as well as a corresponding increase in endothelial cell area and pleomorphism. The present work suggests that the endothelial parameters evaluated change with advancing age.

Interfacial phonon scattering and transmission loss in > 1 µm thick silicon-on-insulator thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Puqing; Lindsay, Lucas R.; Huang, Xi

Scattering of phonons at boundaries of a crystal (grains, surfaces, or solid/solid interfaces) is characterized by the phonon wavelength, the angle of incidence, and the interface roughness, as historically evaluated using a specularity parameter p formulated by Ziman [Electrons and Phonons (Clarendon Press, Oxford, 1960)]. This parameter was initially defined to determine the probability of a phonon specularly reflecting or diffusely scattering from the rough surface of a material. The validity of Ziman's theory as extended to solid/solid interfaces has not been previously validated. Here, to better understand the interfacial scattering of phonons and to test the validity of Ziman'smore » theory, we precisely measured the in-plane thermal conductivity of a series of Si films in silicon-on-insulator (SOI) wafers by time-domain thermoreflectance (TDTR) for a Si film thickness range of 1–10 μm and a temperature range of 100–300 K. The Si/SiO 2 interface roughness was determined to be 0.11±0.04nm using transmission electron microscopy (TEM). Furthermore, we compared our in-plane thermal conductivity measurements to theoretical calculations that combine first-principles phonon transport with Ziman's theory. Calculations using Ziman's specularity parameter significantly overestimate values from the TDTR measurements. We attribute this discrepancy to phonon transmission through the solid/solid interface into the substrate, which is not accounted for by Ziman's theory for surfaces. The phonons that are specularly transmitted into an amorphous layer will be sufficiently randomized by the time they come back to the crystalline Si layer, the effect of which is practically equivalent to a diffuse reflection at the interface. Finally, we derive a simple expression for the specularity parameter at solid/amorphous interfaces and achieve good agreement between calculations and measurement values.« less

Interfacial phonon scattering and transmission loss in > 1 µm thick silicon-on-insulator thin films

DOE PAGES

Jiang, Puqing; Lindsay, Lucas R.; Huang, Xi; ...

2018-05-17

Scattering of phonons at boundaries of a crystal (grains, surfaces, or solid/solid interfaces) is characterized by the phonon wavelength, the angle of incidence, and the interface roughness, as historically evaluated using a specularity parameter p formulated by Ziman [Electrons and Phonons (Clarendon Press, Oxford, 1960)]. This parameter was initially defined to determine the probability of a phonon specularly reflecting or diffusely scattering from the rough surface of a material. The validity of Ziman's theory as extended to solid/solid interfaces has not been previously validated. Here, to better understand the interfacial scattering of phonons and to test the validity of Ziman'smore » theory, we precisely measured the in-plane thermal conductivity of a series of Si films in silicon-on-insulator (SOI) wafers by time-domain thermoreflectance (TDTR) for a Si film thickness range of 1–10 μm and a temperature range of 100–300 K. The Si/SiO 2 interface roughness was determined to be 0.11±0.04nm using transmission electron microscopy (TEM). Furthermore, we compared our in-plane thermal conductivity measurements to theoretical calculations that combine first-principles phonon transport with Ziman's theory. Calculations using Ziman's specularity parameter significantly overestimate values from the TDTR measurements. We attribute this discrepancy to phonon transmission through the solid/solid interface into the substrate, which is not accounted for by Ziman's theory for surfaces. The phonons that are specularly transmitted into an amorphous layer will be sufficiently randomized by the time they come back to the crystalline Si layer, the effect of which is practically equivalent to a diffuse reflection at the interface. Finally, we derive a simple expression for the specularity parameter at solid/amorphous interfaces and achieve good agreement between calculations and measurement values.« less

Structured light optical microscopy for three-dimensional reconstruction of technical surfaces

NASA Astrophysics Data System (ADS)

Kettel, Johannes; Reinecke, Holger; Müller, Claas

2016-04-01

In microsystems technology quality control of micro structured surfaces with different surface properties is playing an ever more important role. The process of quality control incorporates three-dimensional (3D) reconstruction of specularand diffusive reflecting technical surfaces. Due to the demand on high measurement accuracy and data acquisition rates, structured light optical microscopy has become a valuable solution to solve this problem providing high vertical and lateral resolution. However, 3D reconstruction of specular reflecting technical surfaces still remains a challenge to optical measurement principles. In this paper we present a measurement principle based on structured light optical microscopy which enables 3D reconstruction of specular- and diffusive reflecting technical surfaces. It is realized using two light paths of a stereo microscope equipped with different magnification levels. The right optical path of the stereo microscope is used to project structured light onto the object surface. The left optical path is used to capture the structured illuminated object surface with a camera. Structured light patterns are generated by a Digital Light Processing (DLP) device in combination with a high power Light Emitting Diode (LED). Structured light patterns are realized as a matrix of discrete light spots to illuminate defined areas on the object surface. The introduced measurement principle is based on multiple and parallel processed point measurements. Analysis of the measured Point Spread Function (PSF) by pattern recognition and model fitting algorithms enables the precise calculation of 3D coordinates. Using exemplary technical surfaces we demonstrate the successful application of our measurement principle.

Propagation of specular and anti-specular Gaussian Schell-model beams in oceanic turbulence

NASA Astrophysics Data System (ADS)

Zhou, Zhaotao; Guo, Mengwen; Zhao, Daomu

2017-01-01

On the basis of the extended Huygens-Fresnel principle and the unified theory of coherence and polarization of light, we investigate the propagation properties of the specular and anti-specular Gaussian Schell-model (GSM) beams through oceanic turbulence. It is shown that the specularity of specular GSM beams and the anti-specularity of anti-specular GSM beams are destroyed on propagation in oceanic turbulence. The spectral density and the spectral degree of coherence are also studied in detail. The results may be helpful for underwater communication.

Optical Interactions at Randomly Rough Surfaces

DTIC Science & Technology

2003-03-10

frequency range. The design of a random surface that acts as a Lambertian diffuser, especially in the infrared region of the optical spectrum, is...FTIR grazing angle microscopy. Recently, an experimental study was performed of the far-field scattering at small grazing angles, especially the enhanced...a specular component in the scattered light, in this frequency range. The design of a random surface that acts as a Lambertian diffuser, especially in

Ocular Biocompatibility of Nitinol Intraocular Clips

PubMed Central

Velez-Montoya, Raul; Erlanger, Michael

2012-01-01

Purpose. To evaluate the tolerance and biocompatibility of a preformed nitinol intraocular clip in an animal model after anterior segment surgery. Methods. Yucatan mini-pigs were used. A 30-gauge prototype injector was used to attach a shape memory nitinol clip to the iris of five pigs. Another five eyes received conventional polypropylene suture with a modified Seipser slip knot. The authors compared the surgical time of each technique. All eyes underwent standard full-field electroretinogram at baseline and 8 weeks after surgery. The animals were euthanized and eyes collected for histologic analysis after 70 days (10 weeks) postsurgery. The corneal thickness, corneal endothelial cell counts, specular microscopy parameters, retina cell counts, and electroretinogram parameters were compared between the groups. A two sample t-test for means and a P value of 0.05 were use for assessing statistical differences between measurements. Results. The injection of the nitinol clip was 15 times faster than conventional suturing. There were no statistical differences between the groups for corneal thickness, endothelial cell counts, specular microscopy parameters, retina cell counts, and electroretinogram measurements. Conclusions. The nitinol clip prototype is well tolerated and showed no evidence of toxicity in the short-term. The injectable delivery system was faster and technically less challenging than conventional suture techniques. PMID:22064995

Fully automated corneal endothelial morphometry of images captured by clinical specular microscopy

NASA Astrophysics Data System (ADS)

Bucht, Curry; Söderberg, Per; Manneberg, Göran

2010-02-01

The corneal endothelium serves as the posterior barrier of the cornea. Factors such as clarity and refractive properties of the cornea are in direct relationship to the quality of the endothelium. The endothelial cell density is considered the most important morphological factor of the corneal endothelium. Pathological conditions and physical trauma may threaten the endothelial cell density to such an extent that the optical property of the cornea and thus clear eyesight is threatened. Diagnosis of the corneal endothelium through morphometry is an important part of several clinical applications. Morphometry of the corneal endothelium is presently carried out by semi automated analysis of pictures captured by a Clinical Specular Microscope (CSM). Because of the occasional need of operator involvement, this process can be tedious, having a negative impact on sampling size. This study was dedicated to the development and use of fully automated analysis of a very large range of images of the corneal endothelium, captured by CSM, using Fourier analysis. Software was developed in the mathematical programming language Matlab. Pictures of the corneal endothelium, captured by CSM, were read into the analysis software. The software automatically performed digital enhancement of the images, normalizing lights and contrasts. The digitally enhanced images of the corneal endothelium were Fourier transformed, using the fast Fourier transform (FFT) and stored as new images. Tools were developed and applied for identification and analysis of relevant characteristics of the Fourier transformed images. The data obtained from each Fourier transformed image was used to calculate the mean cell density of its corresponding corneal endothelium. The calculation was based on well known diffraction theory. Results in form of estimated cell density of the corneal endothelium were obtained, using fully automated analysis software on 292 images captured by CSM. The cell density obtained by the fully automated analysis was compared to the cell density obtained from classical, semi-automated analysis and a relatively large correlation was found.

Corneal edema after phacoemulsification

PubMed Central

Sharma, Namrata; Singhal, Deepali; Nair, Sreelakshmi P; Sahay, Pranita; Sreeshankar, SS; Maharana, Prafulla Kumar

2017-01-01

Phacoemulsification is the most commonly performed cataract surgery in this era. With all the recent advances in investigations and management of cataract through phacoemulsification, most of the patients are able to achieve excellent visual outcome. Corneal edema after phacoemulsification in the immediate postoperative period often leads to patient dissatisfaction and worsening of outcome. Delayed onset corneal edema often warrants endothelial keratoplasty. This review highlights the etiopathogenesis, risk factors, and management of corneal edema in the acute phase including descemet's membrane detachment (DMD) and toxic anterior segment syndrome. Various investigative modalities such as pachymetry, specular microscopy, anterior segment optical coherence tomography, and confocal microscopy have been discussed briefly. PMID:29208818

Measurement and modelization of silica opal optical properties

NASA Astrophysics Data System (ADS)

Avoine, Amaury; Hong, Phan Ngoc; Frederich, Hugo; Aregahegn, Kifle; Bénalloul, Paul; Coolen, Laurent; Schwob, Catherine; Thu Nga, Pham; Gallas, Bruno; Maître, Agnès

2014-03-01

We present the synthesis process and optical characterization of artificial silica opals. The specular reflection spectra are analyzed and compared to band structure calculations and finite difference time domain (FDTD) simulations. The silica optical index is a key parameter to correctly describe an opal and is usually not known and treated as a free parameter. Here we propose a method to infer the silica index, as well as the silica spheres diameter, from the reflection spectra and we validate it by comparison with two independent infrared methods for the index and, scanning electron microscopy (SEM) and atomic force microscopy (AFM) measurements for the spheres diameter.

Microscopic video observation of capillary vessel systems using diffuse back lighting

NASA Astrophysics Data System (ADS)

Sakai, Minako; Arai, Hiroki; Iwai, Toshiaki

2017-04-01

We have been developing a simple and practical video microscopy system based on absorption spectra of biological substance to perform spectroscopic observation of living tissues. The diffuse backlighting effect is actively used in the developed system, which is generated by multiple light scattering in the tissue. It is demonstrated that the light specularly reflected from the skin surface can be completely suppressed in the microscopic observation and the biological activity of the capillary vessel systems distributed under the skin can be successfully observed. As a result, we can confirm the effectiveness of the video microscopy system using diffuse backlighting and the applicability of our developed system.

Automatic specular reflections removal for endoscopic images

NASA Astrophysics Data System (ADS)

Tan, Ke; Wang, Bin; Gao, Yuan

2017-07-01

Endoscopy imaging is utilized to provide a realistic view about the surfaces of organs inside the human body. Owing to the damp internal environment, these surfaces usually have a glossy appearance showing specular reflections. For many computer vision algorithms, the highlights created by specular reflections may become a significant source of error. In this paper, we present a novel method for restoration of the specular reflection regions from a single image. Specular restoration process starts with generating a substitute specular-free image with RPCA method. Then the specular removed image was obtained by taking the binary weighting template of highlight regions as the weighting for merging the original specular image and the substitute image. The modified template was furthermore discussed for the concealment of artificial effects in the edge of specular regions. Experimental results on the removal of the endoscopic image with specular reflections demonstrate the efficiency of the proposed method comparing to the existing methods.

Laser material micro-working (LMμW): some new surface processes

NASA Astrophysics Data System (ADS)

Daurelio, G.; D'Alonzo, M.

2007-05-01

On the last recent years many new Laser Surface Processes have been studied and tested in the field of the L.M. μW. - Laser Material Micro Working. Still today many of these "young" processes are to study and more and more searches are dedicated to they. These are the Marking, Texturing, Fine Texturing, Filling, Polishing, Micro Shot-Penning, Silking and Colouring. This experimental work reports the results obtained in the field of the Laser Surface Fine Texturing on AISI 304 and 430 Stainless Steels by using a Marking System, that is a Nd:YAG Laser, VECTORMARK type by TRUMPH ( D ). So some new laser surface finishes, called by Authors, - Effetto tessuto, con trama e ordito (Woven effect, with weft and warp) - Effetto pelle scamosciata ( Effect shammy leather ) - Effetto pelle uncinata ( Effect hooked skin ) - Effetto pelle unghiata ( Effect skin looking like scratch ) - Effetto pelle damascata ( Effect damask skin ) - Effetto speculare , ottonato ( Specular effect, looking like brass ) Effetto speculare, bronzato ( specular effect looking like bronze ) - Effetto speculare, argenteo ( specular, looking like silver effect ) - Effetto speculare, ramato ( Specular effect, looking like copper ), Effetto Speculare, dorato ( Specular effect, looking like gold ) - Effetto speculare , dorato, a raggiera ( Specular effect, looking like gold, to aureole) , were carried out. The work is still in progress.

Assessment of the reliability of human corneal endothelial cell-density estimates using a noncontact specular microscope.

PubMed

Doughty, M J; Müller, A; Zaman, M L

2000-03-01

We sought to determine the variance in endothelial cell density (ECD) estimates for human corneal endothelia. Noncontact specular micrographs were obtained from white subjects without any history of contact lens wear, or major eye disease or surgery; subjects were within four age groups (children, young adults, older adults, senior citizens). The endothelial image was scanned, and the areas from > or =75 cells measured from an overlay by planimetry. The cell-area values were used to calculate the ECD repeatedly so that the intra- and intersubject variation in an average ECD estimate could be made by using different numbers of cells (5, 10, 15, etc.). An average ECD of 3,519 cells/mm2 (range, 2,598-5,312 cells/mm2) was obtained of counts of 75 cells/ endothelium from individuals aged 6-83 years. Average ECD estimates in each age group were 4,124, 3,457, 3,360, and 3,113 cells/mm2, respectively. Analysis of intersubject variance revealed that ECD estimates would be expected to be no better than +/-10% if only 25 cells were measured per endothelium, but approach +/-2% if 75 cells are measured. In assessing the corneal endothelium by noncontact specular microscopy, cell count should be given, and this should be > or =75/ endothelium for an expected variance to be at a level close to that recommended for monitoring age-, stress-, or surgery-related changes.

Measurement and Modeling of the Optical Scattering Properties of Crop Canopies

NASA Technical Reports Server (NTRS)

Vanderbilt, V. C. (Principal Investigator)

1985-01-01

The specular reflection process is shown to be a key aspect of radiation transfer by plant canopies. Polarization measurements are demonstrated as the tool for determining the specular and diffuse portions of the canopy radiance. The magnitude of the specular fraction of the reflectance is significant compared to the magnitude of the diffuse fraction. Therefore, it is necessary to consider specularly reflected light in developing and evaluating light-canopy interaction models for wheat canopies. Models which assume leaves are diffuse reflectors correctly predict only the diffuse fraction of the canopy reflectance factor. The specular reflectance model, when coupled with a diffuse leaf model, would predict both the specular and diffuse portions of the reflectance factor. The specular model predicts and the data analysis confirms that the single variable, angle of incidence of specularly reflected sunlight on the leaf, explains much of variation in the polarization data as a function of view-illumination directions.

Ocular Toxicity Secondary to Asclepias physocarpa: The Balloon Plant.

PubMed

Pina, Susana; Pedrosa, Catarina; Santos, Cristina; Feijóo, Bernardo; Pego, Peter; Vendrell, Cristina; Santos, Maria João; Prieto, Isabel

2014-01-01

We report a case of a 65-year-old woman with symptoms of blurred vision and ocular irritation a few hours after accidental contact of the right eye with Asclepias physocarpa milky latex. Observation showed a diffuse conjunctival hyperemia and stromal corneal edema with Descemet's membrane folds. Recovery was fast and apparently complete in less than one month. However, specular microscopy at 6-months follow-up showed an abnormal endothelial morphology as sequelae, suggesting this condition is not as innocuous as it has been suggested.

Polarized iridescence of the multilayered elytra of the Japanese jewel beetle, Chrysochroa fulgidissima

PubMed Central

Stavenga, Doekele G.; Wilts, Bodo D.; Leertouwer, Hein L.; Hariyama, Takahiko

2011-01-01

The elytra of the Japanese jewel beetle Chrysochroa fulgidissima are metallic green with purple stripes. Scanning electron microscopy and atomic force microscopy demonstrated that the elytral surface is approximately flat. The accordingly specular green and purple areas have, with normal illumination, 100–150 nm broad reflectance bands, peaking at about 530 and 700 nm. The bands shift progressively towards shorter wavelengths with increasing oblique illumination, and the reflection then becomes highly polarized. Transmission electron microscopy revealed that the epicuticle of the green and purple areas consists of stacks of 16 and 12 layers, respectively. Assuming gradient refractive index values of the layers between 1.6 and 1.7 and applying the classical multilayer theory allowed modelling of the measured polarization- and angle-dependent reflectance spectra. The extreme polarized iridescence exhibited by the elytra of the jewel beetle may have a function in intraspecific recognition. PMID:21282175

Cryopreservation of rabbit corneas: assessment by microscopy and transplantation.

PubMed Central

Fong, L P; Hunt, C J; Taylor, M J; Pegg, D E

1986-01-01

Rabbit corneas were frozen and thawed by three methods and compared by full thickness transplantation as well as specular microscopy, histology, and transmission electron microscopy. Two of the methods used a recently described technique, in which the excised cornea was immersed in a potassium-rich buffered solution containing the cryoprotectant dimethyl sulphoxide (Me2SO, 2 mol/l). This solution was designed to restrict the loss of intracellular potassium and to prevent cell swelling at low temperatures. In one group the corneas were frozen and thawed surrounded by 5 ml of medium, while in the second group corneas were drained of excess fluid and frozen in air. The third group consisted of corneas cryopreserved by Capella and colleagues' method. All the cryopreserved corneas were damaged, but those that had been frozen in air after exposure to the new medium showed better structure and function than corneas frozen by either of the other two techniques. Images PMID:3535871

Assessment of eye bank-prepared posterior lamellar corneal tissue for endothelial keratoplasty.

PubMed

Rose, Linda; Briceño, César A; Stark, Walter J; Gloria, Dante G; Jun, Albert S

2008-02-01

To evaluate eye bank-prepared tissue for Descemet's stripping automated endothelial keratoplasty (DSAEK). Experimental study and retrospective case series. Seventeen human donor corneas and 4 recipient patients undergoing DSAEK surgery. Corneal-scleral discs were obtained. Specular microscopy and pachymetry were performed. A designated Tissue Banks International technician used a microkeratome to prepare a flap. Posterior bed thickness was measured. The sectioned tissue was stored, and at 24 and 48 hours, pachymetry was repeated. At 48 hours, specular microscopy was repeated, and endothelial cell viability was assessed with trypan blue. Descemet's stripping automated endothelial keratoplasty was performed in 4 patients using eye bank-prepared posterior lamellar tissue. Corneal tissue was assessed with the following parameters: corneal thickness measured with ultrasonic pachymetry, cell density counts measured with a keratoanalyzer, and cell viability as observed with trypan blue exclusion. Patient outcomes were measured by changes in visual acuity (VA) and the presence of a clear graft. Donor corneal pachymetry before sectioning averaged 599+/-52 microm. Immediately after sectioning with a microkeratome set at a depth of 300 microm, mean posterior bed thickness was 328+/-95 microm. Thus, the mean cutting depth achieved by the microkeratome when set at 300 micrometers averaged 271+/-83 microm. After storage for 24 hours, the posterior beds measured 352 microm, an average swelling of 24 (7%) microm (P = 0.14). After 48 hours, the posterior beds measured 382 microm, an average swelling of 54 (16%) microm (P = 0.02). Cell counts 48 hours after sectioning decreased by an average of 11% (P = 0.10). Endothelial cell staining confirmed improvement in postsectioning morphology and survival with increased technician experience. All 4 patients receiving eye bank-prepared DSAEK tissue showed uncomplicated postoperative results, with improvement in VA. The microkeratome cutting depth was moderately accurate. Pachymetry, cell density, and cell viability of sectioned tissue after 48 hours in storage were encouraging overall. Initial clinical results of eye bank-prepared DSAEK tissue showed uncomplicated postoperative courses and improved VA. Additional studies are needed to follow the long-term outcomes in the recipients of these tissues.

Simultaneous measurement of X-ray specular reflection and off-specular diffuse scattering from liquid surfaces using a two-dimensional pixel array detector: the liquid-interface reflectometer of BL37XU at SPring-8.

PubMed

Yano, Yohko F; Uruga, Tomoya; Tanida, Hajime; Toyokawa, Hidenori; Terada, Yasuko; Yamada, Hironari

2010-07-01

An X-ray reflectometer for simultaneous measurement of specular and off-specular reflection of liquid surfaces is described. The reflectometer, equipped with a two-dimensional single X-ray photon-counting pixel array detector obtained the full range of X-ray specular and off-specular reflections in an extremely short time (1 s). Both the specular and off-specular reflection of water exhibited good agreement with the predicted capillary-wave theory within the appropriate instrumental resolution. The approach is also demonstrated on an aqueous solution of 1-dodecyl-3-methylimidazolium chloride. The monolayer in which the dodecyl chain faces upwards and the Cl(-) anion locates next to the imidazolium ring formed on the water surface was found to be laterally homogeneous. The use of a pixel array detector will be particularly powerful for in situ measurements to investigate both out-of-plane and in-plane structures simultaneously, not only for liquid surfaces but also for other thin films.

A study of the effect on a typical orbiter payload thermal environment resulting from specular reflections from the forward orbiter radiators

NASA Technical Reports Server (NTRS)

Humphries, R.; Turner, L.; Littles, J. W.

1979-01-01

The orbiter radiator external coating is highly specular silverized Teflon. Solar energy specularly reflected from these radiators on a typical payload which, when deployed, extends above the payload bay envelope was studied. The flux levels are compared assuming both diffuse and specular radiators.

A Geometric Model for Specularity Prediction on Planar Surfaces with Multiple Light Sources.

PubMed

Morgand, Alexandre; Tamaazousti, Mohamed; Bartoli, Adrien

2018-05-01

Specularities are often problematic in computer vision since they impact the dynamic range of the image intensity. A natural approach would be to predict and discard them using computer graphics models. However, these models depend on parameters which are difficult to estimate (light sources, objects' material properties and camera). We present a geometric model called JOLIMAS: JOint LIght-MAterial Specularity, which predicts the shape of specularities. JOLIMAS is reconstructed from images of specularities observed on a planar surface. It implicitly includes light and material properties, which are intrinsic to specularities. This model was motivated by the observation that specularities have a conic shape on planar surfaces. The conic shape is obtained by projecting a fixed quadric on the planar surface. JOLIMAS thus predicts the specularity using a simple geometric approach with static parameters (object material and light source shape). It is adapted to indoor light sources such as light bulbs and fluorescent lamps. The prediction has been tested on synthetic and real sequences. It works in a multi-light context by reconstructing a quadric for each light source with special cases such as lights being switched on or off. We also used specularity prediction for dynamic retexturing and obtained convincing rendering results. Further results are presented as supplementary video material, which can be found on the Computer Society Digital Library at http://doi.ieeecomputersociety.org/10.1109/TVCG.2017.2677445.

Infrared deflectometry for the inspection of diffusely specular surfaces

NASA Astrophysics Data System (ADS)

Höfer, Sebastian; Burke, Jan; Heizmann, Michael

2016-12-01

Deflectometry is a full-field gradient technique that lends itself very well to testing specular surfaces. It uses the geometry of specular reflection to determine the gradient of the surface under inspection. In consequence, a necessary precondition to apply deflectometry is the presence of at least partially specular reflection. Surfaces with larger roughness have increasingly diffuse reflection characteristics, making them inaccessible to usual deflectometry. However, many industrially relevant surfaces exist that change their reflection characteristic during production and processing. An example is metal sheets that are used as car body parts. Whereas the molded but otherwise raw metal sheets show a mostly diffuse reflection without sufficient specular reflection, the final car body panels have a high specular reflectance due to the lacquering. In consequence, it would be advantageous to apply the same inspection approach both for the raw material and for the final product. To solve this challenge, specular reflection from rough surfaces can be achieved using light with a larger wavelength, as the specular reflectivity of a surface depends on the ratio of the surface roughness and the wavelength of the light applied. Wavelengths in the thermal infrared range create enough specular reflection to apply deflectometry on many visually rough metal surfaces. This contribution presents the principles of thermal deflectometry, its special challenges, and illustrates its use with examples from the inspection of industrially produced surfaces.

Ocular Toxicity Secondary to Asclepias physocarpa: The Balloon Plant

PubMed Central

Pina, Susana; Pedrosa, Catarina; Santos, Cristina; Feijóo, Bernardo; Pego, Peter; Vendrell, Cristina; Santos, Maria João; Prieto, Isabel

2014-01-01

We report a case of a 65-year-old woman with symptoms of blurred vision and ocular irritation a few hours after accidental contact of the right eye with Asclepias physocarpa milky latex. Observation showed a diffuse conjunctival hyperemia and stromal corneal edema with Descemet's membrane folds. Recovery was fast and apparently complete in less than one month. However, specular microscopy at 6-months follow-up showed an abnormal endothelial morphology as sequelae, suggesting this condition is not as innocuous as it has been suggested. PMID:25105044

Wave constraints for Titan's Jingpo Lacus and Kraken Mare from VIMS specular reflection lightcurves

USGS Publications Warehouse

Barnes, J.W.; Soderblom, J.M.; Brown, R.H.; Soderblom, L.A.; Stephan, K.; Jaumann, R.; Le Mouélic, Stéphane; Rodriguez, S.; Sotin, Christophe; Buratti, B.J.; Baines, K.H.; Clark, R.N.; Nicholson, P.D.

2011-01-01

Stephan et al. (Stephan, K. et al. [2010]. Geophys. Res. Lett. 37, 7104-+.) first saw the glint of sunlight specularly reflected off of Titan's lakes. We develop a quantitative model for analyzing the photometric lightcurve generated during a flyby in which the specularly reflected light flux depends on the fraction of the solar specular footprint that is covered by liquid. We allow for surface waves that spread out the geographic specular intensity distribution. Applying the model to the VIMS T58 observations shows that the waves on Jingpo Lacus must have slopes of no greater than 0.15??, two orders of magnitude flatter than waves on Earth's oceans. Combining the model with theoretical estimates of the intensity of the specular reflection allows a tighter constraint on the waves: <0.05?? Residual specular signal while the specular point lies on land implies that either the land is wetted, the wave slope distribution is non-Gaussian, or that 5% of the land off the southwest edge of Jingpo Lacus is covered in puddles. Another specular sequence off of Kraken Mare acquired during Cassini's T59 flyby shows rapid flux changes that the static model cannot reproduce. Points just 1. min apart vary in flux by more than a factor of two. The present dataset does not uniquely determine the mechanism causing these rapid changes. We suggest that changing wind conditions, kilometer-wavelength waves, or moving clouds could account for the variability. Future specular observations should be designed with a fast cadence, at least 6 points per minute, in order to differentiate between these hypotheses. Such new data will further constrain the nature of Titan's lakes and their interactions with Titan's atmosphere. ?? 2010 Elsevier Inc.

Time-resolved study of SrTiO3 homoepitaxial pulsed-laser deposition using surface x-ray diffraction

NASA Astrophysics Data System (ADS)

Eres, G.; Tischler, J. Z.; Yoon, M.; Larson, B. C.; Rouleau, C. M.; Lowndes, D. H.; Zschack, P.

2002-05-01

Homoepitaxy of SrTiO3 by pulsed-laser deposition has been studied using in situ time-resolved surface x-ray diffraction in the temperature range of 310 °C to 780 °C. Using a two-detector configuration, surface x-ray diffraction intensities were monitored simultaneously at the (0 0 1/2) specular and the (0 1 1/2) off-specular truncation rod positions. Abrupt intensity changes in both the specular and off-specular rods after laser pulses indicated prompt crystallization into SrTiO3 layers followed by slower intra- and interlayer surface rearrangements on time scales of seconds. Specular rod intensity oscillations indicated layer-by-layer growth, while off-specular rod intensity measurements suggested the presence of transient in-plane lattice distortions for depositions above 600 °C.

The Search for Nanobubbles by Using Specular and Off-Specular Neutron Reflectometry.

PubMed

Gutfreund, Philipp; Maccarini, Marco; Dennison, Andrew J C; Wolff, Max

2016-09-06

We apply specular and off-specular neutron reflection at the hydrophobic silicon/water interface to check for evidence of nanoscopic air bubbles whose presence is claimed after an ad hoc procedure of solvent exchange. Nanobubbles and/or a depletion layer at the hydrophobic/water interface have long been discussed and generated a plethora of controversial scientific results. By combining neutron reflectometry (NR), off-specular reflectometry (OSS), and grazing incidence small angle neutron scattering (GISANS), we studied the interface between hydrophobized silicon and heavy water before and after saturation with nitrogen gas. Our specular reflectometry results can be interpreted by assuming a submolecular sized depletion layer and the off-specular measurements show no change with nitrogen super saturated water. This picture is consistent with the assumption that, following the solvent exchange, no additional nanobubbles are introduced at significant concentrations (if present at all). Furthermore, we discuss the results in terms of the maximum surface coverage of nanobubbles that could be present on the hydrophobic surface compatibly with the sensitivity limit of these techniques.

Effects of Repeated Intravitreal Aflibercept Injection on the Corneal Endothelium in Patients With Age-Related Macular Degeneration: Outcomes From the RE-VIEW Study.

PubMed

Lass, Jonathan H; Benetz, Beth Ann; Menegay, Harry J; Tsipis, Constantinos P; Cook, Jane Caty; Boyer, David S; Singer, Michael; Erickson, Kristine; Saroj, Namrata; Vitti, Robert; Chu, Karen W; Moini, Hadi; Soo, Yuhwen; Cheng, Yenchieh

2018-05-01

The effects of repeated intravitreal aflibercept injection (IAI) on the corneal endothelium were studied in patients with unilateral neovascular age-related macular degeneration. RE-VIEW was a phase 4, open-label, single-arm, multicenter study. Patients received IAI every 8 weeks after 3 monthly doses. Slit-lamp biomicroscopy was performed at all study visits. The central corneal endothelial health was evaluated by specular microscopy in the treated versus untreated fellow eyes at baseline and weeks 24 and 52. No slit-lamp abnormalities were noted in 154 enrolled patients (eyes). Baseline versus 52-week mean (±SD) endothelial morphometric values (n = 118) for the treated versus untreated fellow eyes were respectively as follows: endothelial cell density was 2410 ± 364 versus 2388 ± 384 cells/mm at baseline and remained unchanged at 2401 ± 353 versus 2376 ± 364 cells/mm at 52 weeks (P = 0.87); the coefficient of variation was 33.5 ± 4.4% versus 34.0 ± 5.0% at baseline and remained unchanged at 34.2 ± 4.7% versus 34.1 ± 4.9% at 52 weeks (P = 0.18); the percentage of hexagonal cells was 59.5 ± 5.8% versus 59.6 ± 6.4% at baseline and remained unchanged at 59.5 ± 6.0% versus 59.5 ± 5.8% at 52 weeks (P = 0.96). Repeated IAI for 52 weeks had no apparent corneal endothelial toxicity noted on specular microscopy in patients treated for neovascular age-related macular degeneration.

Specular Andreev reflection in thin films of topological insulators

NASA Astrophysics Data System (ADS)

Majidi, Leyla; Asgari, Reza

2016-05-01

We theoretically reveal the possibility of specular Andreev reflection in a thin film topological insulator normal-superconductor (N/S) junction in the presence of a gate electric field. The probability of specular Andreev reflection increases with the electric field, and electron-hole conversion with unit efficiency happens in a wide experimentally accessible range of the electric field. We show that perfect specular Andreev reflection can occur for all angles of incidence with a particular excitation energy value. In addition, we find that the thermal conductance of the structure displays exponential dependence on the temperature. Our results reveal the potential of the proposed topological insulator thin-film-based N/S structure for the realization of intraband specular Andreev reflection.

Analysis of specular resonance in dielectric bispheres using rigorous and geometrical-optics theories.

PubMed

Miyazaki, Hideki T; Miyazaki, Hiroshi; Miyano, Kenjiro

2003-09-01

We have recently identified the resonant scattering from dielectric bispheres in the specular direction, which has long been known as the specular resonance, to be a type of rainbow (a caustic) and a general phenomenon for bispheres. We discuss the details of the specular resonance on the basis of systematic calculations. In addition to the rigorous theory, which precisely describes the scattering even in the resonance regime, the ray-tracing method, which gives the scattering in the geometrical-optics limit, is used. Specular resonance is explicitly defined as strong scattering in the direction of the specular reflection from the symmetrical axis of the bisphere whose intensity exceeds that of the scattering from noninteracting bispheres. Then the range of parameters for computing a particular specular resonance is specified. This resonance becomes prominent in a wide range of refractive indices (from 1.2 to 2.2) in a wide range of size parameters (from five to infinity) and for an arbitrarily polarized light incident within an angle of 40 degrees to the symmetrical axis. This particular scattering can stay evident even when the spheres are not in contact or the sizes of the spheres are different. Thus specular resonance is a common and robust phenomenon in dielectric bispheres. Furthermore, we demonstrate that various characteristic features in the scattering from bispheres can be explained successfully by using intuitive and simple representations. Most of the significant scatterings other than the specular resonance are also understandable as caustics in geometrical-optics theory. The specular resonance becomes striking at the smallest size parameter among these caustics because its optical trajectory is composed of only the refractions at the surfaces and has an exceptionally large intensity. However, some characteristics are not accounted for by geometrical optics. In particular, the oscillatory behaviors of their scattering intensity are well described by simple two-wave interference models.

Evaluation of the shape of the specular peak for high glossy surfaces

NASA Astrophysics Data System (ADS)

Obein, Gaël.; Ouarets, Shiraz; Ged, Guillaume

2014-02-01

Gloss is the second most relevant visual attribute of a surface beside its colour. While the colour originates from the wavelength repartition of the reflected light, gloss originates from its angular distribution. When an observer is asked to evaluate the gloss of a surface, he always first orientate his eyes along the specular direction before lightly tilting the examined sample. This means that gloss is located in and around the specular direction, in a peak that is called the specular peak. On the one hand, this peak is flat and broad on matte surfaces on the other hand, it is narrow and sharp on high gloss surfaces. For the late ones, the FWHM of the specular peak is less than 2° which can be quite difficult to measure. We developed a dedicated facility capable of measuring specular peak with a FWHM up to 0,1 °. We measured the evolution of the peak according to the angle of illumination and the specular gloss of the sample in the restricted field of very glossy surface. The facility and peaks measured are presented in the paper. The next step will be to identify the correlations between the peak and the roughness of the sample.

Plant canopy specular reflectance model

NASA Technical Reports Server (NTRS)

Vanderbilt, V. C.; Grant, L.

1985-01-01

A model is derived for the amount of light specularly reflected and polarized by a plant canopy. The model is based on the morphological and phenological characteristics of the canopy and upon the Fresnel equations of optics. The theory demonstrates that the specular reflectance of the plant canopy is a function of the angle of incidence and potentially contains information to help discriminate between species. The theory relates the specular reflectance to botanical condition of the canopy - to factors such as development stage, plant vigor, and leaf area index (LAI).

A one-shot-projection method for measurement of specular surfaces.

PubMed

Wang, Zhenzhou

2015-02-09

In this paper, a method is proposed to measure the shapes of specular surfaces with one-shot-projection of structured laser patterns. By intercepting the reflection of the reflected laser pattern twice with two diffusive planes, the closed form solution is achieved for each reflected ray. The points on the specular surface are reconstructed by computing the intersections of the incident rays and the reflected rays. The proposed method can measure both static and dynamic specular shapes due to its one-shot-projection, which is beyond the capability of most of state of art methods that need multiple projections. To our knowledge, the proposed method is the only method so far that could yield the closed form solutions for the dynamic and specular surfaces.

Comparison of central corneal thickness measurements with a rotating scheimpflug camera, a specular microscope, optical low-coherence reflectometry, and ultrasound pachymetry in keratoconic eyes.

PubMed

Cinar, Yasin; Cingu, Abdullah Kursat; Turkcu, Fatih Mehmet; Cinar, Tuba; Sahin, Alparslan; Yuksel, Harun; Ari, Seyhmus

2015-03-01

To compare central corneal thickness (CCT) measurements with a rotating Scheimpflug camera (RSC), noncontact specular microscopy (SM), optical low-coherence reflectometry (OLCR), and ultrasonic pachymetry (UP) in keratoconus (KC) patients. In this prospective study, four CCT measurements taken with an RSC, SM, OLCR, and UP were compared in 81 eyes of 44 consecutive KC patients. The KC patients were divided into four subgroups according to Amsler-Krumeich's KC classification. The RSC and UP measurements of the CCT were not statistically significant in all the groups. Comparison of the SM vs. the OLCR measurements yielded statistically significant differences in all the KC patients and in all KC stages. In all the KC patients, RSC and OLCR showed a high correlation coefficient factor (r = 0.87, p = 0.000). CCT measurements with RSC are comparable to those achieved with UP. Compared with the other devices, according to SM measurements, the central cornea is thicker in all keratoconic eyes and in all KC grades, and it is thinner according to OLCR. RSC, UP, SM, and OLCR should not be used interchangeably in keratoconic eyes.

Key characteristics of specular stereo

PubMed Central

Muryy, Alexander A.; Fleming, Roland W.; Welchman, Andrew E.

2014-01-01

Because specular reflection is view-dependent, shiny surfaces behave radically differently from matte, textured surfaces when viewed with two eyes. As a result, specular reflections pose substantial problems for binocular stereopsis. Here we use a combination of computer graphics and geometrical analysis to characterize the key respects in which specular stereo differs from standard stereo, to identify how and why the human visual system fails to reconstruct depths correctly from specular reflections. We describe rendering of stereoscopic images of specular surfaces in which the disparity information can be varied parametrically and independently of monocular appearance. Using the generated surfaces and images, we explain how stereo correspondence can be established with known and unknown surface geometry. We show that even with known geometry, stereo matching for specular surfaces is nontrivial because points in one eye may have zero, one, or multiple matches in the other eye. Matching features typically yield skew (nonintersecting) rays, leading to substantial ortho-epipolar components to the disparities, which makes deriving depth values from matches nontrivial. We suggest that the human visual system may base its depth estimates solely on the epipolar components of disparities while treating the ortho-epipolar components as a measure of the underlying reliability of the disparity signals. Reconstructing virtual surfaces according to these principles reveals that they are piece-wise smooth with very large discontinuities close to inflection points on the physical surface. Together, these distinctive characteristics lead to cues that the visual system could use to diagnose specular reflections from binocular information. PMID:25540263

Validity of endothelial cell analysis methods and recommendations for calibration in Topcon SP-2000P specular microscopy.

PubMed

van Schaick, Willem; van Dooren, Bart T H; Mulder, Paul G H; Völker-Dieben, Hennie J M

2005-07-01

To report on the calibration of the Topcon SP-2000P specular microscope and the Endothelial Cell Analysis Module of the IMAGEnet 2000 software, and to establish the validity of the different endothelial cell density (ECD) assessment methods available in these instruments. Using an external microgrid, we calibrated the magnification of the SP-2000P and the IMAGEnet software. In both eyes of 36 volunteers, we validated 4 ECD assessment methods by comparing these methods to the gold standard manual ECD, manual counting of cells on a video print. These methods were: the estimated ECD, estimation of ECD with a reference grid on the camera screen; the SP-2000P ECD, pointing out whole contiguous cells on the camera screen; the uncorrected IMAGEnet ECD, using automatically drawn cell borders, and the corrected IMAGEnet ECD, with manual correction of incorrectly drawn cell borders in the automated analysis. Validity of each method was evaluated by calculating both the mean difference with the manual ECD and the limits of agreement as described by Bland and Altman. Preset factory values of magnification were incorrect, resulting in errors in ECD of up to 9%. All assessments except 1 of the estimated ECDs differed significantly from manual ECDs, with most differences being similar (< or =6.5%), except for uncorrected IMAGEnet ECD (30.2%). Corrected IMAGEnet ECD showed the narrowest limits of agreement (-4.9 to +19.3%). We advise checking the calibration of magnification in any specular microscope or endothelial analysis software as it may be erroneous. Corrected IMAGEnet ECD is the most valid of the investigated methods in the Topcon SP-2000P/IMAGEnet 2000 combination.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tucker, Eric; Boreman, Glenn, E-mail: gboreman@uncc.edu; D'Archangel, Jeffrey

Near- and far-field measurements of phase-ramped loop and patch structures are presented and compared to simulations. The far-field deflection measurements show that the phase-ramped structures can deflect a beam away from specular reflection, consistent with simulations. Scattering scanning near-field optical microscopy of the elements comprising the phase ramped structures reveals part of the underlying near-field phase contribution that dictates the far-field deflection, which correlates with the far-field phase behavior that was expected. These measurements provide insight into the resonances, coupling, and spatial phase variation among phase-ramped frequency selective surface (FSS) elements, which are important for the performance of FSS reflectarrays.

Specular Reflection and Diffuse Reflectance Spectroscopy of Soils

USDA-ARS?s Scientific Manuscript database

Studies on the occurrence and effects of specular reflection in mid-infrared spectra of soils have shown that distortions due to specular reflection occur for both organic (humic acid) and non-organic fractions (carbonates, silica, ashed fraction of soil). The results demonstrated explain why the s...

Specularity of longitudinal acoustic phonons at rough surfaces

NASA Astrophysics Data System (ADS)

Gelda, Dhruv; Ghossoub, Marc G.; Valavala, Krishna; Ma, Jun; Rajagopal, Manjunath C.; Sinha, Sanjiv

2018-01-01

The specularity of phonons at crystal surfaces is of direct importance to thermal transport in nanostructures and to dissipation in nanomechanical resonators. Wave scattering theory provides a framework for estimating wavelength-dependent specularity, but experimental validation remains elusive. Widely available thermal conductivity data presents poor validation since the involvement of the infinitude of phonon wavelengths in thermal transport presents an underconstrained test for specularity theory. Here, we report phonon specularity by measuring the lifetimes of individual coherent longitudinal acoustic phonon modes excited in ultrathin (36-205 nm) suspended silicon membranes at room temperature over the frequency range ˜20 -118 GHz. Phonon surface scattering dominates intrinsic Akhiezer damping at frequencies ≳60 GHz, enabling measurements of phonon boundary scattering time over wavelengths ˜72 -140 nm . We obtain detailed statistics of the surface roughness at the top and bottom surfaces of membranes using HRTEM imaging. We find that the specularity of the excited modes are in good agreement with solutions of wave scattering only when the TEM statistics are corrected for projection errors. The often-cited Ziman formula for phonon specularity also appears in good agreement with the data, contradicting previous results. This work helps to advance the fundamental understanding of phonon scattering at the surfaces of nanostructures.

Effect of surface roughness and subsurface damage on grazing-incidence x-ray scattering and specular reflectance.

PubMed

Lodha, G S; Yamashita, K; Kunieda, H; Tawara, Y; Yu, J; Namba, Y; Bennett, J M

1998-08-01

Grazing-incidence specular reflectance and near-specular scattering were measured at Al-K(alpha) (1.486-keV, 8.34-?) radiation on uncoated dielectric substrates whose surface topography had been measured with a scanning probe microscope and a mechanical profiler. Grazing-incidence specular reflectance was also measured on selected substrates at the Cu-K(alpha) (8.047-keV, 1.54-?) wavelength. Substrates included superpolished and conventionally polished fused silica; SiO(2) wafers; superpolished and precision-ground Zerodur; conventionally polished, float-polished, and precision-ground BK-7 glass; and superpolished and precision-ground silicon carbide. Roughnesses derived from x-ray specular reflectance and scattering measurements were in good agreement with topographic roughness values measured with a scanning probe microscope (atomic force microscope) and a mechanical profiler that included similar ranges of surface spatial wavelengths. The specular reflectance was also found to be sensitive to the density of polished surface layers and subsurface damage down to the penetration depth of the x rays. Density gradients and subsurface damage were found in the superpolished fused-silica and precision-ground Zerodur samples. These results suggest that one can nondestructively evaluate subsurface damage in transparent materials using grazing-incidence x-ray specular reflectance in the 1.5-8-keV range.

Influence of the domain structure of nano-oxide layers on the transport properties of specular spin valves

NASA Astrophysics Data System (ADS)

Ventura, J.; Sousa, J. B.; Veloso, A.; Freitas, P. P.

2007-05-01

Specular spin valves show enhanced giant magnetoresistive ratio when compared to other simpler, spin valve structures as a result of specular reflection in nano-oxide layers (NOLs) formed by the partial oxidation of the CoFe pinned and free layers. The oxides forming the NOL were recently shown to order antiferromagnetically below T ˜175K. Here we study the training effect in MnIr /CoFe/NOL/CoFe/Cu/CoFe/NOL specular spin valves at low temperatures (15K). We observed that the training effect is related to the nano-oxide layer antiferromagnet ordering and to the evolution of the corresponding domain structure with the number of cycles performed. This allowed us to study the influence of the NOL domain structure on the magnetotransport of specular spin valves.

Light Field Imaging Based Accurate Image Specular Highlight Removal

PubMed Central

Wang, Haoqian; Xu, Chenxue; Wang, Xingzheng; Zhang, Yongbing; Peng, Bo

2016-01-01

Specular reflection removal is indispensable to many computer vision tasks. However, most existing methods fail or degrade in complex real scenarios for their individual drawbacks. Benefiting from the light field imaging technology, this paper proposes a novel and accurate approach to remove specularity and improve image quality. We first capture images with specularity by the light field camera (Lytro ILLUM). After accurately estimating the image depth, a simple and concise threshold strategy is adopted to cluster the specular pixels into “unsaturated” and “saturated” category. Finally, a color variance analysis of multiple views and a local color refinement are individually conducted on the two categories to recover diffuse color information. Experimental evaluation by comparison with existed methods based on our light field dataset together with Stanford light field archive verifies the effectiveness of our proposed algorithm. PMID:27253083

Dark-field optical coherence microscopy

NASA Astrophysics Data System (ADS)

Pache, C.; Villiger, M. L.; Lasser, T.

2010-02-01

Many solutions have been proposed to produce phase quantitative images of biological cell samples. Among these, Spectral Domain Phase Microscopy combines the fast imaging speed and high sensitivity of Optical Coherence Microscopy (OCM) in the Fourier domain with the high phase stability of common-path interferometry. We report on a new illumination scheme for OCM that enhances the sensitivity for backscattered light and detects the weak sample signal, otherwise buried by the signal from specular reflection. With the use of a Bessel-like beam, a dark-field configuration was realized. Sensitivity measurements for three different illumination configurations were performed to compare our method to standard OCM and extended focus OCM. Using a well-defined scattering and reflecting object, we demonstrated an attenuation of -40 dB of the DC-component and a relative gain of 30 dB for scattered light, compared to standard OCM. In a second step, we applied this technique, referred to as dark-field Optical Coherence Microscopy (dfOCM), to living cells. Chinese hamster ovarian cells were applied in a drop of medium on a coverslide. The cells of ~15 μm in diameter and even internal cell structures were visualized in the acquired tomograms.

Oxygen therapy for corneal edema after cataract surgery.

PubMed

Sharifipour, Farideh; Panahi-Bazaz, Mahmoodreza; Idani, Esmaeil; Hajizadeh, Maryam; Saki, Azadeh

2015-07-01

To evaluate the effects of oxygen therapy on corneal edema after cataract surgery. Imam Khomeini Hospital, Ahvaz, Iran. Randomized controlled trial. Patients with severe corneal edema were randomized into 3 groups. Group 1 (control) received conventional therapy including topical sodium chloride, timolol, and betamethasone. Group 2 received the same therapy in addition to systemic normobaric oxygen at a flow rate of 10 L/min for 1 hour twice daily for 3 weeks. Group 3 received conventional therapy and transcorneal oxygen at a flow rate of 5 L/min for 1 hour twice daily for 3 weeks. Preoperative pachymetry and specular microscopy were performed. Pachymetry was performed 1, 3, 5, 7, 10, and 14 days postoperatively. At 1, 3 and 12 months, pachymetry and specular microscopy were performed. The study enrolled 45 patients. Preoperatively, there was no significant difference between the groups. Pachymetry was more than 1000 μm 1 day postoperatively in all patients. The preoperative pachymetry was restored in 14 days in Group 3 only. After 1 year, the endothelial cell count (ECC) was 1603 cells/mm(2), 1693 cells/mm(2), and 1911 cells/mm(2) with a loss of 37%, 32%, and 25% in Group 1, Group 2, and Group 3, respectively (P = .034, Groups 1 and 3). Group 3 had a higher ECC than the control group at 3 months (P = .037) and 1 year (P = .025). One patient in Group 1 and 1 patient in Group 2 developed bullous keratopathy. Transcorneal oxygen decreased corneal edema more rapidly than conventional and systemic oxygen therapies and preserved more endothelial cells than conventional therapy. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Specular, diffuse and polarized imagery of an oat canopy

NASA Technical Reports Server (NTRS)

Vanderbilt, Vern C.; De Venecia, Kurt J.

1988-01-01

Light, polarized by specular reflection, has been found to be an important part of the light scattered by several measured plant canopies. The authors investigate for one canopy the relative importance of specularly reflected sunlight, specularly reflected light from other sources including skylight, and diffusely upwelling light. Polarization images are used to gain increased understanding of the radiation transfer process in a plant canopy. Analysis of the results suggests that properly analyzed polarized remotely sensed data, acquired under specific atmospheric conditions by a specially designed sensor, potentially provide measures of physiological and morphological states of plants in a canopy.

Limits of agreement between the optical pachymeter and a noncontact specular microscope.

PubMed

Ogbuehi, Kelechi C; Almubrad, Turki M

2005-07-01

To determine the limits of agreement between central corneal thickness (CCT) measurements made with the slit lamp-attached optical pachymeter and the SP2000P noncontact specular microscope. Triplicate readings for CCT were obtained for each of 130 (right) eyes of 130 patients, using the slit lamp-attached optical pachymeter and then the SP2000P noncontact specular microscope. The average CCT measured by each method was compared. Subsequently, the mean difference between both sets of measurements was assessed, and the 95% confidence interval (limits of agreement) between both techniques was determined. The mean +/- SD CCT measured by the optical pachymeter was 543 +/- 34 microm and 532 +/- 34 microm for the specular microscope. We found a statistically significant (P < 0.001) mean bias of 10 mum between CCT values measured with both types of equipment, with the optical pachymeter returning the higher values. The coefficient of variation was 6.3% for the optical pachymeter and 6.4% for the specular microscope. The right eye CCT measurements made by the optical pachymeter are, on average, 10 mum thicker than those made with the SP2000P specular microscope, which suggests that both pieces of equipment cannot be used interchangeably to monitor CCT changes in patients. Excluding left eye measurements, the reliability of the optical pachymeter is identical to that of the noncontact specular microscope.

Endoscopic probe optics for spectrally encoded confocal microscopy.

PubMed

Kang, Dongkyun; Carruth, Robert W; Kim, Minkyu; Schlachter, Simon C; Shishkov, Milen; Woods, Kevin; Tabatabaei, Nima; Wu, Tao; Tearney, Guillermo J

2013-01-01

Spectrally encoded confocal microscopy (SECM) is a form of reflectance confocal microscopy that can achieve high imaging speeds using relatively simple probe optics. Previously, the feasibility of conducting large-area SECM imaging of the esophagus in bench top setups has been demonstrated. Challenges remain, however, in translating SECM into a clinically-useable device; the tissue imaging performance should be improved, and the probe size needs to be significantly reduced so that it can fit into luminal organs of interest. In this paper, we report the development of new SECM endoscopic probe optics that addresses these challenges. A custom water-immersion aspheric singlet (NA = 0.5) was developed and used as the objective lens. The water-immersion condition was used to reduce the spherical aberrations and specular reflection from the tissue surface, which enables cellular imaging of the tissue deep below the surface. A custom collimation lens and a small-size grating were used along with the custom aspheric singlet to reduce the probe size. A dual-clad fiber was used to provide both the single- and multi- mode detection modes. The SECM probe optics was made to be 5.85 mm in diameter and 30 mm in length, which is small enough for safe and comfortable endoscopic imaging of the gastrointestinal tract. The lateral resolution was 1.8 and 2.3 µm for the single- and multi- mode detection modes, respectively, and the axial resolution 11 and 17 µm. SECM images of the swine esophageal tissue demonstrated the capability of this device to enable the visualization of characteristic cellular structural features, including basal cell nuclei and papillae, down to the imaging depth of 260 µm. These results suggest that the new SECM endoscopic probe optics will be useful for imaging large areas of the esophagus at the cellular scale in vivo.

The dark side of gloss.

PubMed

Kim, Juno; Marlow, Phillip J; Anderson, Barton L

2012-11-01

Our visual system relies on the image structure generated by the interaction of light with objects to infer their material properties. One widely studied surface property is gloss, which can provide information that an object is smooth, shiny or wet. Studies have historically focused on the role of specular highlights in modulating perceived gloss. Here we show in human observers that glossy surfaces can generate both bright specular highlights and dark specular 'lowlights', and that the presence of either is sufficient to generate compelling percepts of gloss. We show that perceived gloss declines when the image structure generated by specular lowlights is blurred or misaligned with surrounding surface shading and that perceived gloss can arise from the presence of lowlights in surface regions isolated from highlights. These results suggest that the image structure generated by specular highlights and lowlights is used to construct our experience of surface gloss.

Evaluation of non-specular reflecting silvered Teflon and filled adhesives

NASA Technical Reports Server (NTRS)

Bourland, G.; Cox, R. L.

1981-01-01

A non-specular silver-Teflon tape thermal control coating was tested to provide the data necessary to qualify it for use on the Space Shuttle Orbiter radiators. Effects of cure cycle temperature and pressure on optical and mechanical properties on the silver-Teflon tape were evaluated. The baseline Permacel P-223 adhesive, used with the specular silver-Teflon tape initially qualified for the Orbiter radiators, and four alternate metal-filled and unfilled adhesives were evaluated. Tests showed the cure process has no effect on the silver-Teflon optical properties, and that the baseline adhesive cure cycle gives best results. In addition the P-223 adhesive bond is more reproducible than the alternates, and the non-specular tape meets both the mechanical and the optical requirements of the Orbiter radiator coating specification. Existing Orbiter coating techniques were demonstrated to be effective in aplying the non-specular tape to a curved panel simulating the radiators. Author

Deviation characteristics of specular reflectivity of micro-rough surface from Fresnel's equation

NASA Astrophysics Data System (ADS)

Zhang, W. J.; Qiu, J.; Liu, L. H.

2015-07-01

Specular reflectivity is an important radiative property in thermal engineering applications and reflection-based optical constant determinations, yet it will be influenced by surface micro-roughness which cannot be completely removed during the polishing process. In this work, we examined the deviation characteristics of the specular reflectivity of micro-rough surfaces from that predicted by the Fresnel's equation under the assumption of smooth surface. The effects of incident angle and relative roughness were numerically investigated for both 1D and 2D micro randomly rough surfaces using full wave analysis under the condition that the relative roughness is smaller than 0.05. For transverse magnetic (TM) wave incidence, it is observed that the deviation of specular reflectivity dramatically rises as the incident angle approaches to the pseudo Brewster's angle, which violates the prediction based on Rayleigh criterion. While for the transverse electric (TE) wave incidence, the deviation of the specular reflectivity is much smaller and decreases monotonically with the increase of incident angle, which agrees with the predication from Rayleigh criterion. Generally, the deviation of specular reflectivity for both TM and TE increases with the relative roughness as commonly expected.

Changes in Corneal Endothelial Cell after Ahmed Glaucoma Valve Implantation and Trabeculectomy: 1-Year Follow-up.

PubMed

Kim, Min Su; Kim, Kyoung Nam; Kim, Chang-Sik

2016-12-01

To compare changes in corneal endothelial cell density (CECD) after Ahmed glaucoma valve (AGV) implantation and trabeculectomy. Changes in corneal endothelium in patients that underwent AGV implantation or trabeculectomy were prospectively evaluated. Corneal specular microscopy was performed at the central cornea using a non-contact specular microscope before surgery and 6 months and 12 months after surgery. The CECD, hexagonality of the endothelial cells, and the coefficient of variation of the cell areas were compared between the two groups. Forty eyes of 40 patients with AGV implantation and 28 eyes of 28 patients with trabeculectomy were studied. Intraocular pressure in the AGV implantation group was significantly higher than that in the trabeculectomy group ( p < 0.001), but there was no significant difference in other clinical variables between the two groups. In the AGV implantation group, the mean CECD significantly decreased by 9.4% at 6 months and 12.3% at 12 months compared with baseline values (both, p < 0.001), while it decreased by 1.9% at 6 months and 3.2% at 12 months in the trabeculectomy group ( p = 0.027 and p = 0.015, respectively). The changes at 6 months and 12 months in the AGV implantation group were significantly higher than those in the trabeculectomy group ( p = 0.030 and p = 0.027, respectively). In the AGV implantation group, there was a significant decrease in the CECD between baseline and 6 months and between 6 months and 12 months ( p < 0.001 and p = 0.005, respectively). However, in the trabeculectomy group, a significant decrease was observed only between baseline and 6 months ( p = 0.027). Both the AGV implantation group and the trabeculectomy group showed statistically significant decreases in the CECD 1 year after surgery. The decrease in CECD in the AVG implantation group was greater and persisted longer than that in the trabeculectomy group.

SPECSweb Multistatic Tracking on a Truth-Blind Simulated Scenario of the MSTWG

DTIC Science & Technology

2009-07-01

communications links and fusion/tracking processes, producing too many false tracks. The Specular-Cued Surveillance Web (SPECSweb) multistatic tracker...information from the multistatic nodes to a fusion center. A concept referred to as the “Specular-Cued Surveillance Web (SPECSweb)” is being...producing too many false tracks. The Specular-Cued Surveillance Web (SPECSweb) multistatic tracker mitigates these problems through implementation of two

Low levels of specularity support operational color constancy, particularly when surface and illumination geometry can be inferred

PubMed Central

Lee, Robert J.; Smithson, Hannah E.

2016-01-01

We tested whether surface specularity alone supports operational color constancy – the ability to discriminate changes in illumination or reflectance. Observers viewed short animations of illuminant or reflectance changes in rendered scenes containing a single spherical surface, and were asked to classify the change. Performance improved with increasing specularity, as predicted from regularities in chromatic statistics. Peak performance was impaired by spatial rearrangements of image pixels that disrupted the perception of illuminated surfaces, but was maintained with increased surface complexity. The characteristic chromatic transformations that are available with non-zero specularity are useful for operational color constancy, particularly if accompanied by appropriate perceptual organisation. PMID:26974938

Observations and simulations of specularly reflected He++ at Earth's quasiperpendicular bow shock

NASA Astrophysics Data System (ADS)

Broll, J. M.; Fuselier, S. A.; Trattner, K. J.; Anderson, B. J.; Burch, J. L.; Giles, B. L.

2016-12-01

Specular reflection of protons at Earth's quasiperpendicular bow shock is an important process for supercritical shock dissipation. Previous studies have found evidence of He++ specular reflection from reduced particle distributions downstream from the shock, but confirmation of the process for heavier ions in the shock foot was not possible due to time resolution constraints. We present He++ distributions, observed by MMS in a quasiperpendicular bow shock crossing, that are consistent with specularly reflected He++. We also investigate the He++ dynamics with test-particle simulations in a simulated shock based on this crossing and we conduct wave analysis to determine what processes lead to separate gyrotropization timescales for the transmitted and reflected populations.

Assessment of central corneal thickness and corneal endothelial morphology using ultrasound pachymetry, non-contact specular microscopy, and Confoscan 4 confocal microscopy

PubMed Central

2013-01-01

Background The aim was to compare the repeatability, reproducibility and inherent precision of ultrasound pachymetry (USP), noncontact specular microscopy (SP-2000P) and the Confoscan 4 confocal microscope (z-ring CS4) in measuring endothelial cell density (ECD), coefficient of variation of cell size (CV), and central corneal thickness (CCT) in normal eyes. Methods In this prospective study, one eye was selected from each of 30 subjects for the measurements of ECD, CV and CCT, which were taken by two observers. Results were analyzed statistically by repeated-measures analysis of variance (ANOVA) for intra-observer repeatability, inter-observer reproducibility, unpaired t-test, paired t-test, and Bland–Altman analyses to determine limits of agreement (LOA) between the three instruments. Results Mean ECD, measured by SP-2000P and z-ring CS4, were 3115.50 ± 279.70 cells/mm2 and 3167.50 ± 264.75 cells/mm2, respectively (observer 1), and 3192.63 ± 249.42 cells/mm2 (z-ring, observer 2). Mean CV measurements were 27.12 ± 2.51 and 27.10 ± 2.41 (SP-2000P and z-ring CS4, respectively; observer 1), and 27.17 ± 2.25 (z-ring, observer 2). Mean CCT values were 555.11 ± 35.83 μm (USP), 535.82 ± 41.10 μm (SP-2000P) and 552.57 ± 36.83 μm (z-ring CS4), and 554.97 ± 36.34 μm (z-ring CS4, observer 2). However, pairwise tests in all cases there was good repeatability and reproducibility as shown by inter-observer and intra-observer analysis of variance for each of the instruments. Conclusions The SP-2000P and the z-ring CS4 can be used interchangeably to measure ECD and CV. For CCT, the sample size was too small to test for differences of the CCT measurements between the three instruments. PMID:24274022

Development of a spatially resolved reflectometer to monitor corrosion of solar reflectors

NASA Astrophysics Data System (ADS)

Sutter, Florian; Meyen, Stephanie; Heller, Peter; Pitz-Paal, Robert

2013-06-01

Solar reflectors for Concentrating Solar Power (CSP) concentrators require a high reflectance and high specularity over the whole solar spectrum. During their lifetime of at least 20 years, the reflectors must withstand harsh outdoor conditions without loosing their reflective properties. Currently, there are not many devices available to measure the specular reflectance. In this work a prototype of a specular reflectometer with spatial resolution has been developed. The major advantage of the prototype compared to other reflectometers is the possibility of measuring the specular reflectance on an extended measuring spot of more than 5 cm in diameter with a spatial resolution of 37 pixel/mm. Additionally, measurements can be taken at three different acceptance half angles (φ = 3.5, 6.0, and 12.5 mrad) and at three different wavelengths (λ = 410 nm, 500 nm, and 656 nm). This lab scale instrument can be employed to monitor degradation effects, such as corrosion spots, and evaluate their influence on the specular reflectance of solar mirror materials.

SPECSweb Post-Tracking Classification Method

DTIC Science & Technology

2011-07-01

The Specular-Cued Surveillance Web (SPECSweb) multistatic tracker effectively reduces false track rate through the use of two amplitude thresholds...Cueing – Clutter 1 Introduction A concept referred to as the “Specular-Cued Surveillance Web (SPECSweb)” is being pursued to mitigate the data...on 5-8 July 2011. Sponsored in part by Office of Naval Research and U.S. Army Research Laboratory. 14. ABSTRACT The Specular-Cued Surveillance Web

Thermal stability of Mn-Ir-based specular spin valve structure

NASA Astrophysics Data System (ADS)

Yoon, S. Y.; Lee, D. H.; Jeon, D. M.; Kim, J. H.; Yoon, D. H.; Suh, S. J.

2004-05-01

We studied the thermal properties of specular and conventional spin valves. The specular spin valve showed better thermal properties (e.g. slow MR degradation and sheet resistance increment) than those of conventional spin valve. It is considered that the Mn-Co-Fe-O is formed in the NOL at 543-578 K and this acts as a diffusion barrier for Mn during high-temperature annealing process.

Comparison of central corneal thickness and endothelial cell measurements by Scheimpflug camera system and two noncontact specular microscopes.

PubMed

Karaca, Irmak; Yilmaz, Suzan Guven; Palamar, Melis; Ates, Halil

2017-07-03

To investigate the correlation of Scheimpflug camera system and two noncontact specular microscopes in terms of central corneal thickness (CCT) and corneal endothelial cell morphology measurements. One hundred eyes of 50 healthy subjects were examined by Pentacam Scheimpflug Analyzer, CEM-530 (Nidek Co, Ltd, Gamagori, Japan) and CellChek XL (Konan Medical, California, USA) via fully automated image analysis with no corrections made. Measurement differences and agreement between instruments were determined by intraclass correlation analysis. The mean age of the subjects was 36.74 ± 8.59 (range 22-57). CCTs were well correlated among all devices, with having CEM-530 the thinnest and CellChek XL the thickest measurements (intraclass correlation coefficient (ICC) = 0.83; p < 0.001 and ICC = 0.78; p < 0.001, respectively). Mean endothelial cell density (ECD) given by CEM-530 was lower than CellChek XL (2613.17 ± 228.62 and 2862.72 ± 170.42 cells/mm 2 , respectively; ICC = 0.43; p < 0.001). Mean value for coefficient of variation (CV) was 28.57 ± 3.61 in CEM-530 and 30.30 ± 3.53 in CellChek XL. Cell hexagonality (HEX) with CEM-530 was higher than with CellChek XL (68.70 ± 4.16% and 45.19 ± 6.58%, respectively). ECDs with CellChek XL and CEM-530 have good correlation, but the values obtained by CellChek XL are higher than CEM-530. Measurements for HEX and CV differ significantly and show weak correlation. Thus, we do not recommend interchangeable use of CellChek XL and CEM-530. In terms of CCTs, Pentacam, CEM-530 and CellChek XL specular microscopy instruments are reliable devices.

Role of computer-assisted analysis of the corneal endothelium in vitreoretinal surgery with intraocular silicone oil injection: a technical report.

PubMed

Fruschelli, M; Esposti, P; Caporossi, A

1998-01-01

The innermost lining of the cornea consists of a single layer of cells called the endothelium. Despite its name, the endothelium of the cornea differs considerably from the vascular endothelium, both functionally and morphologically. The corneal endothelium plays a fundamental role in maintaining the transparency of the corneal membrane, as the result of both its function as a barrier against penetration of the aqueous humor in the parenchyma and its ability to remove water from the stroma (usually referred to as the endothelial "pump" function). Any abnormality in the corneal endothelium causes, first, the impairment of its function as a barrier and pump due to the loss of stromal anti-turgor mechanisms, followed by edema and possible development into keratopathy. The specular microscope is an instrument which makes it possible to see the endothelial "mosaic" in the reflected image of the posterior corneal surface. A large variety of clinical specular microscopes is presently available, both contact and non-contact, which allow, for easy and rapid photography of the corneal endothelium "in vivo". In the present case, we used a non-contact computerized specular microscope to analyze the corneal endothelium in a group of patients affected by retinal detachment who needed to undergo vitreoretinal surgery with immission of silicone oil into the vitreal chamber.

Determining the Index of Refraction of an Unknown Object using Passive Polarimetric Imagery Degraded by Atmospheric Turbulence

DTIC Science & Technology

2010-08-09

44 9 A photograph of a goniophotometer used by Bell and a schematic of a goniophotometer used by Mian et al...plane is called the parallel field component because it lies parallel to the specular plane. The incident electric field vector component which...resides in the plane or- thogonal to the specular plane is called the perpendicular field component because it lies perpendicular to the specular plane. If

Image-Based Models for Specularity Propagation in Diminished Reality.

PubMed

Said, Souheil Hadj; Tamaazousti, Mohamed; Bartoli, Adrien

2018-07-01

The aim of Diminished Reality (DR) is to remove a target object in a live video stream seamlessly. In our approach, the area of the target object is replaced with new texture that blends with the rest of the image. The result is then propagated to the next frames of the video. One of the important stages of this technique is to update the target region with respect to the illumination change. This is a complex and recurrent problem when the viewpoint changes. We show that the state-of-the-art in DR fails in solving this problem, even under simple scenarios. We then use local illumination models to address this problem. According to these models, the variation in illumination only affects the specular component of the image. In the context of DR, the problem is therefore solved by propagating the specularities in the target area. We list a set of structural properties of specularities which we incorporate in two new models for specularity propagation. Our first model includes the same property as the previous approaches, which is the smoothness of illumination variation, but has a different estimation method based on the Thin-Plate Spline. Our second model incorporates more properties of the specularity's shape on planar surfaces. Experimental results on synthetic and real data show that our strategy substantially improves the rendering quality compared to the state-of-the-art in DR.

Separation and correlation of structural and magnetic roughness in a Ni thin film by polarized off-specular neutron reflectometry.

PubMed

Singh, Surendra; Basu, Saibal

2009-02-04

Diffuse (off-specular) neutron and x-ray reflectometry has been used extensively for the determination of interface morphology in solids and liquids. For neutrons, a novel possibility is off-specular reflectometry with polarized neutrons to determine the morphology of a magnetic interface. There have been few such attempts due to the lower brilliance of neutron sources, though magnetic interaction of neutrons with atomic magnetic moments is much easier to comprehend and easily tractable theoretically. We have obtained a simple and physically meaningful expression, under the Born approximation, for analyzing polarized diffuse (off-specular) neutron reflectivity (PDNR) data. For the first time PDNR data from a Ni film have been analyzed and separate chemical and magnetic morphologies have been quantified. Also specular polarized neutron reflectivity measurements have been carried out to measure the magnetic moment density profile of the Ni film. The fit to PDNR data results in a longer correlation length for in-plane magnetic roughness than for chemical (structural) roughness. The magnetic interface is smoother than the chemical interface.

Defect mapping system

DOEpatents

Sopori, Bhushan L.

1995-01-01

Apparatus for detecting and mapping defects in the surfaces of polycrystalline materials in a manner that distinguishes dislocation pits from grain boundaries includes a laser for illuminating a wide spot on the surface of the material, a light integrating sphere with apertures for capturing light scattered by etched dislocation pits in an intermediate range away from specular reflection while allowing light scattered by etched grain boundaries in a near range from specular reflection to pass through, and optical detection devices for detecting and measuring intensities of the respective intermediate scattered light and near specular scattered light. A center blocking aperture or filter can be used to screen out specular reflected light, which would be reflected by nondefect portions of the polycrystalline material surface. An X-Y translation stage for mounting the polycrystalline material and signal processing and computer equipment accommodate rastor mapping, recording, and displaying of respective dislocation and grain boundary defect densities. A special etch procedure is included, which prepares the polycrystalline material surface to produce distinguishable intermediate and near specular light scattering in patterns that have statistical relevance to the dislocation and grain boundary defect densities.

Defect mapping system

DOEpatents

Sopori, B.L.

1995-04-11

Apparatus for detecting and mapping defects in the surfaces of polycrystalline materials in a manner that distinguishes dislocation pits from grain boundaries includes a laser for illuminating a wide spot on the surface of the material, a light integrating sphere with apertures for capturing light scattered by etched dislocation pits in an intermediate range away from specular reflection while allowing light scattered by etched grain boundaries in a near range from specular reflection to pass through, and optical detection devices for detecting and measuring intensities of the respective intermediate scattered light and near specular scattered light. A center blocking aperture or filter can be used to screen out specular reflected light, which would be reflected by nondefect portions of the polycrystalline material surface. An X-Y translation stage for mounting the polycrystalline material and signal processing and computer equipment accommodate rastor mapping, recording, and displaying of respective dislocation and grain boundary defect densities. A special etch procedure is included, which prepares the polycrystalline material surface to produce distinguishable intermediate and near specular light scattering in patterns that have statistical relevance to the dislocation and grain boundary defect densities. 20 figures.

Concurrent Acute Retinal Necrosis in a Patient With Iridocorneal Endothelial Syndrome.

PubMed

Vignesh, A P; Srinivasan, Renuka

2016-11-01

To report a rare case of concurrent acute retinal necrosis in a patient with iridocorneal endothelial syndrome (ICE). Case report. A 42-year-old woman showed acute diminution of vision in the right eye. Her fundus examination revealed features of acute retinal necrosis. She had also experienced gradual diminution of vision in her left eye for 5 years. The examination of her left eye revealed corneal edema with mild corectopia and increased intraocular pressure with abnormal endothelium on specular microscopy pointing to a diagnosis of ICE. This is a rare case where concurrent acute retinal necrosis and ICE syndrome are present in the same patient, possibly pointing to a common viral etiology causing both entities.

A novel quantitative methodology for age evaluation of the human corneal endothelium

NASA Astrophysics Data System (ADS)

Rannou, Klervi; Thuret, Gilles; Gain, Philippe; Pinoli, Jean-Charles; Gavet, Yann

2017-03-01

The human corneal endothelium regulates the cornea transparency. Its cells, that cannot regenerate after birth, form a tesselated mosaic with almost perfect hexagonal cells during childhood, becoming progressively bigger and less ordered during aging. This study included 50 patients (in 10 decades groups) and 10 specular microscopy observations per patient. Five different criteria were measured on the manually segmented cells: area and perimeter of the cells as well as reduced Minkowski functionals. All these criteria were used to assess the probability of age group membership. We demonstrated that the age evaluation is near the reality, although a high variability was observed for patients between 30 and 70 years old.

Crystalline Subtype of Pre-Descemetic Corneal Dystrophy

PubMed Central

Dolz-Marco, Rosa; Gallego-Pinazo, Roberto; Pinazo-Durán, María Dolores; Díaz-Llopis, Manuel

2014-01-01

Purpose To report corneal findings in a familial case of the crystalline subtype of pre-Descemetic corneal dystrophy. Case Report A 19-year-old girl and her 44-year-old mother were found to have asymptomatic, bilateral, punctiform and multi-colored crystalline opacities across the whole posterior layer of the corneas. Endothelial specular microscopy revealed the presence of white round flecks located at different levels anterior to the endothelium. No systemic abnormalities or medications could be related to account for these findings. Conclusion To the best of our knowledge, this is the third familial report of this rare corneal disorder. Differential diagnosis may include Schnyder corneal dystrophy, cystinosis, Bietti´s dystrophy and monoclonal gammopathy. PMID:25279130

Giant magnetoresistance in ion beam deposited spin-valve films with specular enhancement

NASA Astrophysics Data System (ADS)

Sant, S.; Mao, M.; Kools, J.; Koi, K.; Iwasaki, H.; Sahashi, M.

2001-06-01

Three different techniques, natural oxidation, remote plasma oxidation and low energy ion beam oxidation, have been proved to be equally effective in forming nano-oxide layers (NOLs) in spin-valve films for specular enhancement of giant magnetoresistance (GMR) effect. GMR values over 12% have been routinely obtained in spin-valve films with NOL, corresponding to a 30% specular enhancement over those without NOL. The consistency and robustness of the oxidation processes has been demonstrated by a very large GMR value ˜19% in a dual spin-valve film with the NOLs formed in both pinned layers, the oscillatory dependence of the interlayer coupling field on Cu layer thickness in specular enhanced spin-valve films and the uniform and repeatable film performance over 5 in. substrates.

A critical examination of the validity of simplified models for radiant heat transfer analysis.

NASA Technical Reports Server (NTRS)

Toor, J. S.; Viskanta, R.

1972-01-01

Examination of the directional effects of the simplified models by comparing the experimental data with the predictions based on simple and more detailed models for the radiation characteristics of surfaces. Analytical results indicate that the constant property diffuse and specular models do not yield the upper and lower bounds on local radiant heat flux. In general, the constant property specular analysis yields higher values of irradiation than the constant property diffuse analysis. A diffuse surface in the enclosure appears to destroy the effect of specularity of the other surfaces. Semigray and gray analyses predict the irradiation reasonably well provided that the directional properties and the specularity of the surfaces are taken into account. The uniform and nonuniform radiosity diffuse models are in satisfactory agreement with each other.

Separation of specular and diffuse components using tensor voting in color images.

PubMed

Nguyen, Tam; Vo, Quang Nhat; Yang, Hyung-Jeong; Kim, Soo-Hyung; Lee, Guee-Sang

2014-11-20

Most methods for the detection and removal of specular reflections suffer from nonuniform highlight regions and/or nonconverged artifacts induced by discontinuities in the surface colors, especially when dealing with highly textured, multicolored images. In this paper, a novel noniterative and predefined constraint-free method based on tensor voting is proposed to detect and remove the highlight components of a single color image. The distribution of diffuse and specular pixels in the original image is determined using tensors' saliency analysis, instead of comparing color information among neighbor pixels. The achieved diffuse reflectance distribution is used to remove specularity components. The proposed method is evaluated quantitatively and qualitatively over a dataset of highly textured, multicolor images. The experimental results show that our result outperforms other state-of-the-art techniques.

First observations and simulations of specularly reflected He++ at Earth's quasi-perpendicular bow shock

NASA Astrophysics Data System (ADS)

Broll, J. M.; Fuselier, S. A.; Trattner, K. J.; Giles, B. L.; Anderson, B. J.; Burch, J. L.

2017-12-01

Proton specular reflection at quasi-perpendicular shocks provides dissipation in cases where the upstream Mach number is too high for fluid dissipation mechanisms alone - as is almost always the case at Earth's bow shock. Some evidence of He++ specular reflection was found in reduced particle distributions measured by previous spacecraft at the bow shock. However, due to resolution constraints it was not possible to confirm that the bow shock was capable of reflecting solar wind He++. We present MMS observations of quasi-perpendicular bow shock crossing that are consistent with He++ specular reflection. These observations are supported by 1D particle-in- cell simulations demonstrating that a small amount of He++ can be turned back despite having twice the mass-per-charge of the protons.

Determination of refractive indices of opaque rough surfaces

NASA Astrophysics Data System (ADS)

Destouches, Nathalie; Deumié, Carole; Giovannini, Hugues; Amra, Claude

2004-02-01

The refractive indices of optical materials are usually determined from spectrophotometric andellipsometric measurements of specular beams. When the roughness of the interfaces increases, the energy in the specularly reflected and transmitted beams decreases and scattering becomes predominant. For strong roughness (compared to the incident wavelength) a surface does not exhibit specular reflection or transmission, making difficult the determination of the refractive index. We describe two techniques, based on scattering measurements, that one can use to determine the refractive indices of opaque inhomogeneous media.

Near specular scatter analysis method with a new goniophotometer

NASA Astrophysics Data System (ADS)

Meyen, Stephanie; Sutter, Florian; Heller, Peter

2014-09-01

The challenge of improving component quality and reducing cost has focused the attention of the solar thermal power industry on reliable component characterization methods. Since the reflector plays a key role in the energy conversion chain, the analysis of its reflectance properties has become a lively discussed issue in recent years. State of the art measurement instruments for specular reflectance do not give satisfying results, because they do not resolve sufficiently the near specular scatter of possible low cost mirror material candidates. The measurement of the BRDF offers a better solution than the traditional approach of placing a detector in the specular reflected beam path. However, due to the requirement of high angular resolution in the range of 1 mrad (0.057°) or better and the challenge of measuring high dynamic differences between the specular peak and the scatter signal, typical commercial scanning goniophotometers capable of this are rare. These instruments also face the disadvantages of impractically long acquisition times and, to reach the high angular resolution, occupy a large space (several meters side length). We have taken on the appealing idea of a parallel imaging goniophotometer and designed a prototype based on this principle. A mirrored ellipsoid is used to redirect the reflected light coming from a sample towards a camera with a fisheye lens. This way the complete light distribution is captured simultaneously. A key feature allows the distinction of the high intensity specular peak and the low intensity scatter. In this article we explain the prototype design and demonstrate its functionality based on comparison measurements done with a commercial scanning goniophotometer. We identify limitations related in part to the concept and in part to the specific prototype and suggest improvements. Finally we conclude that the concept is well suitable for the analysis of near specular scatter of mirror materials, although less adequate for the analysis of rough surfaces that require a full 180° view angle. Results obtained with this instrument are useful to evaluate the performance of a reflector material for a specific concentrating solar collector design and also serve in other applications that require near specular scatter analysis like degradation and soiling research.

Investigation of converging and collimated beam instrument geometry on specular gloss measurements

NASA Astrophysics Data System (ADS)

Zwinkels, Joanne C.; Côté, Éric; Morgan, John

2018-02-01

Specular gloss is an important appearance property of a wide variety of manufactured goods. Depending upon the application, e.g. paints, paper, ceramics, etc. different instrument designs and measurement geometries are specified in standard test methods. For a given specular angle, these instrument designs can be broadly classified as converging beam (TAPPI method) and collimated beam (DIN method). In recent comparisons of specular gloss measurements using different glossmeters, very large standard deviations have been reported, well exceeding the manufacturers claims. In this paper, we investigate the effect of instrument beam geometry on gloss measurements. These results indicate that this difference in beam geometry can give the magnitude of gloss differences reported in these comparisons and highlights the importance of educating the user community of best measurement practices and obtaining appropriate traceability for their glossmeters.

Improved thermal stability of Mn-Ir-based magnetic tunnel junction with nano-oxide layer

NASA Astrophysics Data System (ADS)

Yoon, S. Y.; Kim, Y. I.; Lee, D. H.; Kim, Y. S.; Suh, S. J.

2004-06-01

Si/SiO2/Ta/NiFe/Mn-Ir/CoFe/NOL/CoFe/Al-O/CoFe/NiFe/Ta bottom conventional (without nano-oxide layer, NOL) and specular (with NOL) MTJs were prepared by DC magnetron sputtering methods. In the case of a conventional MTJ, the TMR ratio increased up to 300 °C but the TMR ratio of a specular MTJ increased up to 400 °C. The highest TMR ratios of two samples after annealing at each optimal temperature were 21.6% (conventional MTJ) and 22.7% (specular MTJ), respectively, This improved thermal property of the specular MTJ is due to the NOL, which could act as a diffusion barrier for Mn. The bias-voltage dependence of both samples was vastly improved after annealing at each optimal temperature.

Effects of the specular Orbiter forward radiators on a typical Spacelab payload thermal environment

NASA Technical Reports Server (NTRS)

Turner, L. D.; Humphries, W. R.; Littles, J. W.

1981-01-01

Orbiter radiators, having a specular reflection, must be considered when determining the design environment for payloads which can view the forward deployed radiators. Unlike most surfaces on the Orbiter, which reflect energy diffusely, the radiators are covered with a highly specular silverized Teflon material, with high emissivity, and have a concave contour, producing a local concentration of reflected energy towards the region of angle incidence. The combined effects of radiator specularity and geometry were analyzed using the Thermal Radiation Analysis System (TRASYS II), a specialized ray trace program, and a generalized Monte-Carlo-based thermal radiation program. Data given for a 0 deg payload inclination angle at orbital noon at 3.454 m indicate that the maximum total flux and average flux can increase 173% and 63%, respectively, when compared to diffuse radiators.

Wavelength dependence in radio-wave scattering and specular-point theory

NASA Technical Reports Server (NTRS)

Tyler, G. L.

1976-01-01

Radio-wave scattering from natural surfaces contains a strong quasispecular component that at fixed wavelengths is consistent with specular-point theory, but often has a strong wavelength dependence that is not predicted by physical optics calculations under the usual limitations of specular-point models. Wavelength dependence can be introduced by a physical approximation that preserves the specular-point assumptions with respect to the radii of curvature of a fictitious, effective scattering surface obtained by smoothing the actual surface. A uniform low-pass filter model of the scattering process yields explicit results for the effective surface roughness versus wavelength. Interpretation of experimental results from planetary surfaces indicates that the asymptotic surface height spectral densities fall at least as fast as an inverse cube of spatial frequency. Asymptotic spectral densities for Mars and portions of the lunar surface evidently decrease more rapidly.

An improved method to estimate reflectance parameters for high dynamic range imaging

NASA Astrophysics Data System (ADS)

Li, Shiying; Deguchi, Koichiro; Li, Renfa; Manabe, Yoshitsugu; Chihara, Kunihiro

2008-01-01

Two methods are described to accurately estimate diffuse and specular reflectance parameters for colors, gloss intensity and surface roughness, over the dynamic range of the camera used to capture input images. Neither method needs to segment color areas on an image, or to reconstruct a high dynamic range (HDR) image. The second method improves on the first, bypassing the requirement for specific separation of diffuse and specular reflection components. For the latter method, diffuse and specular reflectance parameters are estimated separately, using the least squares method. Reflection values are initially assumed to be diffuse-only reflection components, and are subjected to the least squares method to estimate diffuse reflectance parameters. Specular reflection components, obtained by subtracting the computed diffuse reflection components from reflection values, are then subjected to a logarithmically transformed equation of the Torrance-Sparrow reflection model, and specular reflectance parameters for gloss intensity and surface roughness are finally estimated using the least squares method. Experiments were carried out using both methods, with simulation data at different saturation levels, generated according to the Lambert and Torrance-Sparrow reflection models, and the second method, with spectral images captured by an imaging spectrograph and a moving light source. Our results show that the second method can estimate the diffuse and specular reflectance parameters for colors, gloss intensity and surface roughness more accurately and faster than the first one, so that colors and gloss can be reproduced more efficiently for HDR imaging.

Specular gloss scales comparison between the SIMT and the NIST

NASA Astrophysics Data System (ADS)

Yin, Dejin; Li, Tiecheng; Huang, Biyong; Cheng, Weihai; Lin, Fangsheng

2016-09-01

Specular gloss is the fraction of light reflected in the specular direction for specified incident and receptor apertures, it is the perception by an observer of the mirror-like appearance of a surface. The measurement of specular gloss consists of comparing the luminous reflectance from a test sample to that from a calibrated gloss standard which generally is a polished piece of black glass, under the same experimental conditions. Gloss is a dimensionless quantity whose accurate determination requires standardized experimental conditions such as spectral distribution of the incident beam of light, incident and viewing angles, and a gloss standard. The Shanghai Institute of Measurement and Testing Technology (SIMT) provides test service to calibrate gloss reference standards. This facility is built around a reference goniophotometer, containing an instrument that measures flux as a function of angles of illumination or observation and a primary gloss standard, which is a piece of three wedges of highly polished, high-quality optical glass. The system has an overall (k=2) uncertainty of 0.5 Gloss Unit(GU). The service offers calibration measurements of working gloss standards at the geometries of 20°, 60°, and 85°, in compliance with the ISO 2813 and the ASTM D523 documentary standards. This article describes a bilateral comparison of specular gloss scales between SIMT and the National Institute of Standards and Technology (NIST) that has been performed. The results of this comparison show agreement within the combined uncertainties for the measurement of specular gloss of highly polished black glass.

Comparison between semiconducting and oxide layers as a reflection layer in spin-valve films

NASA Astrophysics Data System (ADS)

Dinia, A.; Schmerber, G.; Ulhaq, C.

2003-07-01

It is well established that appropriate oxide capping is effective in forming nano-oxide layers (NOL) in spin-valve films for specular enhancement of giant magnetoresistance (GMR) effect. However, the beneficial effect of a NOL is strongly dependent on its process of formation. Therefore, we are interested to use a nano-semiconducting layer (NSL) for specular reflection instead of oxide layers because its achievement is easier since no specific growth conditions are needed. Moreover, we intend to compare the efficiency of the electronic confinement inside the spin valve induced either by NSL or NOLs for structures with the same stack. We have prepared hard-soft spin valve structures by sputtering on glass substrates with the following stacking sequence: Fe6 nm/Cu3 nm/CoFe1.8 nmRu0.8 nmCoFe3 nmCu2 nmRu2 nm. The reflecting layers have been inserted in the middle of the Fe soft layer and on the top of the spin valve. The GMR effect is enhanced by 60% and 75% respectively for the NSL and the NOL. This shows that the NOL is more efficient in term of electronic confinement. To understand the origin of the difference between the NOL and NSL magnetization measurements as well as transmission electron microscopy are presented.

Nano-oxide-layer specular spin valve heads with synthetic pinned layer: Head performance and reliability

NASA Astrophysics Data System (ADS)

Hasegawa, N.; Koike, F.; Ikarashi, K.; Ishizone, M.; Kawamura, M.; Nakazawa, Y.; Takahashi, A.; Tomita, H.; Iwasaki, H.; Sahashi, M.

2002-05-01

To implement the specular nano-oxide-layer (NOL) spin valve (SV) heads for use in practical applications, it is key to simultaneously achieve a good specular effect of the NOL inserted in the synthetic ferrimagnet pinned layer (i.e., high magnetoresistance MR performance) and a strong pinning field through the NOL. By using CoFe+X as a substance to be subjected to oxidation, we obtained the NOL specular SV films simultaneously achieving a high MR ratio of 17%-18% and a high pinning field of 1100-1500 Oe. Narrow track (0.12 μm) heads were fabricated and they showed a high sensitivity of 10 mV/μm. Several reliability tests were done both at the sheet film level and the actual head level. The oxygen inside NOL was found to be stable up to 350 °C, and pinned layer magnetization canting after orthogonal field annealing was found to be almost the same as today's non-NOL SV films. An electrostatic discharge test and accelerated lifetime test were also performed and NOL specular heads were demonstrated to have almost the same robustness as today's non-NOL heads.

Light polarization measurements - A method to determine the specular and diffuse light-scattering properties of both leaves and plant canopies

NASA Technical Reports Server (NTRS)

Vanderbilt, V. C.; Grant, L.

1984-01-01

The contributions of diffuse and specular reflection to the total canopy reflection of sunlight are determined experimentally for wheat at two stages of development using spectroradiometer measurements obtained at 13 wavelengths in the 480-720-nm range with a polarizing film in maximum and minimum signal-amplitude positions. The data and computation techniques are presented in tables, diagrams, and graphs, and the need to take specular reflection into account in constructing models of light/canopy interaction is stressed.

Specular Reflection of Sunlight from Earth

NASA Astrophysics Data System (ADS)

Varnai, T.; Marshak, A.

2018-02-01

The Deep Space Gateway vantage point offers advantages in observing specular reflection from water surfaces or ice crystals in clouds. Such data can give information on clouds and atmospheric aerosols, and help test algorithms of future exoplanet characterization.

Split off-specular reflection and surface scattering from woven materials

NASA Astrophysics Data System (ADS)

Pont, Sylvia C.; Koenderink, Jan J.

2003-03-01

We measured radiance distributions for black lining cloth and copper gauze using the convenient technique of wrapping the materials around a circular cylinder, irradiating it with a parallel light source and collecting the scattered radiance by a digital camera. One family of parallel threads (weave or weft) was parallel to the cylinder generator. The most salient features for such glossy plane weaves are a splitting up of the reflection peak due to the wavy variations in local slopes of the threads around the cylinders and a surface scattering lobe due to the threads that run along the cylinder. These scattering characteristics are quite different from the (off-)specular peaks and lobes that were found before for random rough specular surfaces. The split off-specular reflection is due to the regular structures in our samples of man-made materials. We derived simple approximations for these reflectance characteristics using geometrical optics.

Global Variation of Meteor Trail Plasma Turbulence

NASA Technical Reports Server (NTRS)

Dyrud, L. P.; Hinrichs, J.; Urbina, J.

2011-01-01

We present the first global simulations on the occurrence of meteor trail plasma irregularities. These results seek to answer the following questions: when a meteoroid disintegrates in the atmosphere will the resulting trail become plasma turbulent, what are the factors influencing the development of turbulence, and how do they vary on a global scale. Understanding meteor trail plasma turbulence is important because turbulent meteor trails are visible as non-specular trails to coherent radars, and turbulence influences the evolution of specular radar meteor trails, particularly regarding the inference of mesospheric temperatures from trail diffusion rates, and their usage for meteor burst communication. We provide evidence of the significant effect that neutral atmospheric winds and density, and ionospheric plasma density have on the variability of meteor trail evolution and the observation of nonspecular meteor trails, and demonstrate that trails are far less likely to become and remain turbulent in daylight, explaining several observational trends using non-specular and specular meteor trails.

Distribution of blocking temperatures in nano-oxide layers of specular spin valves

NASA Astrophysics Data System (ADS)

Ventura, J.; Araujo, J. P.; Sousa, J. B.; Veloso, A.; Freitas, P. P.

2007-06-01

Specular spin valves show enhanced giant magnetoresistive (GMR) ratio when compared to other, simpler, spin valve structures. The enhancement of GMR results from specular reflection in nano-oxide layers (NOLs) formed by the partial oxidation of the pinned and free layer. These oxides forming the NOL order antiferromagnetically (AFM) below a temperature T ˜175 K. Here, we study the effects of the pinned layer magnetization and its domain structure on the AFM ordering of the NOL by performing field cooling measurements with different cooling fields (H0). We observe enhanced (reduced) exchange field and magnetoresistive ratio for H0>0(<0), i.e., parallel (antiparallel) to the pinned magnetization. These measurements allowed us to confirm the existence of a wide distribution of blocking temperatures (TB) in the NOL of specular spin valves, having a maximum at T ≈175 K, and extending to NOL regions with TB as low as 15 K.

Full-field 3D shape measurement of specular object having discontinuous surfaces

NASA Astrophysics Data System (ADS)

Zhang, Zonghua; Huang, Shujun; Gao, Nan; Gao, Feng; Jiang, Xiangqian

2017-06-01

This paper presents a novel Phase Measuring Deflectometry (PMD) method to measure specular objects having discontinuous surfaces. A mathematical model is established to directly relate the absolute phase and depth, instead of the phase and gradient. Based on the model, a hardware measuring system has been set up, which consists of a precise translating stage, a projector, a diffuser and a camera. The stage locates the projector and the diffuser together to a known position during measurement. By using the model-based and machine vision methods, system calibration is accomplished to provide the required parameters and conditions. The verification tests are given to evaluate the effectiveness of the developed system. 3D (Three-Dimensional) shapes of a concave mirror and a monolithic multi-mirror array having multiple specular surfaces have been measured. Experimental results show that the proposed method can obtain 3D shape of specular objects having discontinuous surfaces effectively

Specular reflection on Titan: Liquids in Kraken Mare

USGS Publications Warehouse

Stephan, Katrin; Jaumann, Ralf; Brown, Robert H.; Soderblom, Jason M.; Soderblom, Laurence A.; Barnes, Jason W.; Sotin, Christophe; Griffith, Caitlin A.; Kirk, Randolph L.; Baines, Kevin H.; Buratti, Bonnie J.; Clark, Roger N.; Lytle, Dyer M.; Nelson, Robert M.; Nicholson, Phillip D.

2010-01-01

After more than 50 close flybys of Titan by the Cassini spacecraft, it has become evident that features similar in morphology to terrestrial lakes and seas exist in Titan's polar regions. As Titan progresses into northern spring, the much more numerous and larger lakes and seas in the north-polar region suggested by Cassini RADAR data, are becoming directly illuminated for the first time since the arrival of the Cassini spacecraft. This allows the Cassini optical instruments to search for specular reflections to provide further confirmation that liquids are present in these evident lakes. On July 8, 2009 Cassini VIMS detected a specular reflection in the north-polar region of Titan associated with Kraken Mare, one of Titan's large, presumed seas, indicating the lake's surface is smooth and free of scatterers with respect to the wavelength of 5 μm, where VIMS detected the specular signal, strongly suggesting it is liquid.

The toxic effect of different concentrations of povidone iodine on the rabbit's cornea.

PubMed

Jiang, Jin; Wu, Miaoqin; Shen, Ting

2009-01-01

To investigate the effects of polyvinylpyrrolidone (i.e., povidone) iodine (PVP-I) in different concentrations on the rabbit's cornea. PVP-I in various concentrations was instilled into the conjunctival sac and injected into the anterior chamber independently. The toxicity to the cornea was assessed by fluorescence dye, specular microscopy, and corneal pachymetry. After conjunctival sac PVP-I instillation, severe epithelial damage was observed at the concentrations of 5.0% and 2.5%. After anterior chamber PVP-I injection, significant corneal edema was observed at the concentrations of 2.0% and 1.5%. It can be safe and feasible to use 0.5% or 1.0% concentrations of PVP-I in conjunctival sac instillation for preoperative antisepsis.

Acquisition and analysis of coastal ground-truth data for correlation with ERTS-1 imagery. [surface radiance data for Santa Monica Bay and Santa Barbara Channel

NASA Technical Reports Server (NTRS)

Anikouchine, W. A. (Principal Investigator)

1973-01-01

The author has identified the following significant results. Radiance profiles drawn along cruise tracks have been examined for use in correlating digital radiance levels with ground truth data. Preliminary examination results are encouraging. Adding weighted levels from the 4 MSS bands appears to enhance specular surface reflections while rendering sensor noise white. Comparing each band signature to the added specular signature ought to enhance non-specular effects caused by ocean turbidity. Preliminary examination of radiance profiles and ground truth turbidity measurements revealed substantial correlation.

An intelligent system for real time automatic defect inspection on specular coated surfaces

NASA Astrophysics Data System (ADS)

Li, Jinhua; Parker, Johné M.; Hou, Zhen

2005-07-01

Product visual inspection is still performed manually or semi automatically in most industries from simple ceramic tile grading to complex automotive body panel paint defect and surface quality inspection. Moreover, specular surfaces present additional challenge to conventional vision systems due to specular reflections, which may mask the true location of objects and lead to incorrect measurements. There are some sophisticated visual inspection methods developed in recent years. Unfortunately, most of them are highly computational. Systems built on those methods are either inapplicable or very costly to achieve real time inspection. In this paper, we describe an integrated low-cost intelligent system developed to automatically capture, extract, and segment defects on specular surfaces with uniform color coatings. The system inspects and locates regular surface defects with lateral dimensions as small as a millimeter. The proposed system is implemented on a group of smart cameras using its on-board processing ability to achieve real time inspection. The experimental results on real test panels demonstrate the effectiveness and robustness of proposed system.

Radar sea reflection for low-e targets

NASA Astrophysics Data System (ADS)

Chow, Winston C.; Groves, Gordon W.

1998-09-01

Modeling radar signal reflection from a wavy sea surface uses a realistic characteristic of the large surface features and parameterizes the effect of the small roughness elements. Representation of the reflection coefficient at each point of the sea surface as a function of the Specular Deviation Angle is, to our knowledge, a novel approach. The objective is to achieve enough simplification and retain enough fidelity to obtain a practical multipath model. The 'specular deviation angle' as used in this investigation is defined and explained. Being a function of the sea elevations, which are stochastic in nature, this quantity is also random and has a probability density function. This density function depends on the relative geometry of the antenna and target positions, and together with the beam- broadening effect of the small surface ripples determined the reflectivity of the sea surface at each point. The probability density function of the specular deviation angle is derived. The distribution of the specular deviation angel as function of position on the mean sea surface is described.

Performance analysis and evaluation of direct phase measuring deflectometry

NASA Astrophysics Data System (ADS)

Zhao, Ping; Gao, Nan; Zhang, Zonghua; Gao, Feng; Jiang, Xiangqian

2018-04-01

Three-dimensional (3D) shape measurement of specular objects plays an important role in intelligent manufacturing applications. Phase measuring deflectometry (PMD)-based methods are widely used to obtain the 3D shapes of specular surfaces because they offer the advantages of a large dynamic range, high measurement accuracy, full-field and noncontact operation, and automatic data processing. To enable measurement of specular objects with discontinuous and/or isolated surfaces, a direct PMD (DPMD) method has been developed to build a direct relationship between phase and depth. In this paper, a new virtual measurement system is presented and is used to optimize the system parameters and evaluate the system's performance in DPMD applications. Four system parameters are analyzed to obtain accurate measurement results. Experiments are performed using simulated and actual data and the results confirm the effects of these four parameters on the measurement results. Researchers can therefore select suitable system parameters for actual DPMD (including PMD) measurement systems to obtain the 3D shapes of specular objects with high accuracy.

SuperADAM: Upgraded polarized neutron reflectometer at the Institut Laue-Langevin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Devishvili, A.; Zhernenkov, K.; Institut Laue-Langevin, BP 156, 38042 Grenoble

2013-02-15

A new neutron reflectometer SuperADAM has recently been built and commissioned at the Institut Laue-Langevin, Grenoble, France. It replaces the previous neutron reflectometer ADAM. The new instrument uses a solid state polarizer/wavelength filter providing a highly polarized (up to 98.6%) monochromatic neutron flux of 8 Multiplication-Sign 10{sup 4} n cm{sup -2} s{sup -1} with monochromatization {Delta}{lambda}/{lambda}= 0.7% and angular divergence {Delta}{alpha}= 0.2 mrad. The instrument includes both single and position sensitive detectors. The position sensitive detector allows simultaneous measurement of specular reflection and off-specular scattering. Polarization analysis for both specular reflection and off-specular scattering is achieved using either mirror analyzersmore » or a {sup 3}He spin filter cell. High efficiency detectors, low background, and high flux provides a dynamic range of up to seven decades in reflectivity. Detailed specifications and the instrument capabilities are illustrated with examples of recently collected data in the fields of thin film magnetism and thin polymer films.« less

SuperADAM: Upgraded polarized neutron reflectometer at the Institut Laue-Langevin

NASA Astrophysics Data System (ADS)

Devishvili, A.; Zhernenkov, K.; Dennison, A. J. C.; Toperverg, B. P.; Wolff, M.; Hjörvarsson, B.; Zabel, H.

2013-02-01

A new neutron reflectometer SuperADAM has recently been built and commissioned at the Institut Laue-Langevin, Grenoble, France. It replaces the previous neutron reflectometer ADAM. The new instrument uses a solid state polarizer/wavelength filter providing a highly polarized (up to 98.6%) monochromatic neutron flux of 8 × 104 n cm-2 s-1 with monochromatization Δλ/λ = 0.7% and angular divergence Δα = 0.2 mrad. The instrument includes both single and position sensitive detectors. The position sensitive detector allows simultaneous measurement of specular reflection and off-specular scattering. Polarization analysis for both specular reflection and off-specular scattering is achieved using either mirror analyzers or a 3He spin filter cell. High efficiency detectors, low background, and high flux provides a dynamic range of up to seven decades in reflectivity. Detailed specifications and the instrument capabilities are illustrated with examples of recently collected data in the fields of thin film magnetism and thin polymer films.

SuperADAM: upgraded polarized neutron reflectometer at the Institut Laue-Langevin.

PubMed

Devishvili, A; Zhernenkov, K; Dennison, A J C; Toperverg, B P; Wolff, M; Hjörvarsson, B; Zabel, H

2013-02-01

A new neutron reflectometer SuperADAM has recently been built and commissioned at the Institut Laue-Langevin, Grenoble, France. It replaces the previous neutron reflectometer ADAM. The new instrument uses a solid state polarizer/wavelength filter providing a highly polarized (up to 98.6%) monochromatic neutron flux of 8 × 10(4) n cm(-2) s(-1) with monochromatization Δλ∕λ = 0.7% and angular divergence Δα = 0.2 mrad. The instrument includes both single and position sensitive detectors. The position sensitive detector allows simultaneous measurement of specular reflection and off-specular scattering. Polarization analysis for both specular reflection and off-specular scattering is achieved using either mirror analyzers or a (3)He spin filter cell. High efficiency detectors, low background, and high flux provides a dynamic range of up to seven decades in reflectivity. Detailed specifications and the instrument capabilities are illustrated with examples of recently collected data in the fields of thin film magnetism and thin polymer films.

Evidence for specularly reflected ions upstream from the quasi-parallel bow shock

NASA Technical Reports Server (NTRS)

Gosling, J. T.; Thomsen, M. F.; Bame, S. J.; Feldman, W. C.; Paschmann, G.; Sckopke, N.

1982-01-01

Ion velocity distributions in the form of bunches of gyrating particles traveling along helical paths have been observed moving sunward immediately upstream from quasi-parallel parts of the earth's bow shock using Los Alamos/Garching instruments on ISEE-1 and -2. These distributions have characteristics which indicate that they are produced by the nearly specular reflection at the shock of a portion of the incident solar wind ions. In particular, the guiding center motion and the gyrospeeds of the gyrating ions are quantitatively consistent with simple geometrical considerations for specular reflection. These considerations reveal that specularly reflected ions can escape upstream when the angle between the upstream magnetic field and the local shock normal is less than 45 deg but not when the angle is greater than 45 deg. These upstream gyrating ions are an important signature of one of the processes by which solar wind streaming energy is dissipated into other forms of energy at the shock.

Ion mobilities in diatomic gases: measurement versus prediction with non-specular scattering models.

PubMed

Larriba, Carlos; Hogan, Christopher J

2013-05-16

Ion/electrical mobility measurements of nanoparticles and polyatomic ions are typically linked to particle/ion physical properties through either application of the Stokes-Millikan relationship or comparison to mobilities predicted from polyatomic models, which assume that gas molecules scatter specularly and elastically from rigid structural models. However, there is a discrepancy between these approaches; when specular, elastic scattering models (i.e., elastic-hard-sphere scattering, EHSS) are applied to polyatomic models of nanometer-scale ions with finite-sized impinging gas molecules, predictions are in substantial disagreement with the Stokes-Millikan equation. To rectify this discrepancy, we developed and tested a new approach for mobility calculations using polyatomic models in which non-specular (diffuse) and inelastic gas-molecule scattering is considered. Two distinct semiempirical models of gas-molecule scattering from particle surfaces were considered. In the first, which has been traditionally invoked in the study of aerosol nanoparticles, 91% of collisions are diffuse and thermally accommodating, and 9% are specular and elastic. In the second, all collisions are considered to be diffuse and accommodating, but the average speed of the gas molecules reemitted from a particle surface is 8% lower than the mean thermal speed at the particle temperature. Both scattering models attempt to mimic exchange between translational, vibrational, and rotational modes of energy during collision, as would be expected during collision between a nonmonoatomic gas molecule and a nonfrozen particle surface. The mobility calculation procedure was applied considering both hard-sphere potentials between gas molecules and the atoms within a particle and the long-range ion-induced dipole (polarization) potential. Predictions were compared to previous measurements in air near room temperature of multiply charged poly(ethylene glycol) (PEG) ions, which range in morphology from compact to highly linear, and singly charged tetraalkylammonium cations. It was found that both non-specular, inelastic scattering rules lead to excellent agreement between predictions and experimental mobility measurements (within 5% of each other) and that polarization potentials must be considered to make correct predictions for high-mobility particles/ions. Conversely, traditional specular, elastic scattering models were found to substantially overestimate the mobilities of both types of ions.

Smartphone-based imaging of the corneal endothelium at sub-cellular resolution

NASA Astrophysics Data System (ADS)

Toslak, Devrim; Thapa, Damber; Erol, Muhammet Kazim; Chen, Yanjun; Yao, Xincheng

2017-07-01

This aim of this study was to test the feasibility of smartphone-based specular microscopy of the corneal endothelium at a sub-cellular resolution. Quantitative examination of endothelial cells is essential for evaluating corneal disease such as determining a diagnosis, monitoring progression and assessing treatment. Smartphone-based technology promises a new opportunity to develop affordable devices to foster quantitative examination of endothelial cells in rural and underserved areas. In our study, we incorporated an iPhone 6 and a slit lamp to demonstrate the feasibility of smartphone-based microscopy of the corneal endothelium at a sub-cellular resolution. The sub-cellular resolution images allowed quantitative calculation of the endothelial cell density. Comparative measurements revealed a normal endothelial cell density of 2978 cells/mm2 in the healthy cornea, and a significantly reduced cell density of 1466 cells/mm2 in the diseased cornea with Fuchs' dystrophy. Our ultimate goal is to develop a smartphone-based telemedicine device for low-cost examination of the corneal endothelium, which can benefit patients in rural areas and underdeveloped countries to reduce health care disparities.

The reflectance of Ames 24E, Infrablack, and Martin black. [anodizing coatings for far-infrared space telescopes

NASA Technical Reports Server (NTRS)

Smith, Sheldon M.

1989-01-01

Results are reported from measurements of the specular reflectances (SRs) and bidirectional reflectance distribution functions (BRDFs) of three black optical coatings in the FIR wavelength range. The nonspecular reflectometer apparatus described by Smith (1984) is employed, and the data are presented in tables and graphs and discussed in detail. It is found that Ames 24E has an FIR SR one order of magnitude lower than that of Martin black (MB), with BRDF values characteristic of a nearly Lambertian surface, while Infrablack has SR two orders lower than MB and a specular-diffuse surface; MB itself has a very specular surface.

The calibration of specular gloss meters and gloss plates

NASA Astrophysics Data System (ADS)

Li, Tiecheng; Lai, Lei; Yin, Dejin; Ji, Muyao; Lin, Fangsheng; Shi, Leibing; Xia, Ming; Fu, Yi

2017-10-01

Specular gloss is the perception by an observer of the mirror-like appearance of a surface. Specular gloss is usually measured by a glossmeter, which can be calibrated by a group of gloss plates according to JJG 696-2015. The characteristics of a gloss meter include stability, zero error, and error of indication. The characteristics of a gloss plate include roughness and spectral transmissivity of a high gloss plate, spectral reflectivity of a ceramic gloss plate. The experiment results indicate that calibration of both gloss meters and gloss plates should be carefully performed according to the latest verification regulation in order to reduce the measurement error.

A functional equation for the specular reflection of rays.

PubMed

Le Bot, A

2002-10-01

This paper aims to generalize the "radiosity method" when applied to specular reflection. Within the field of thermics, the radiosity method is also called the "standard procedure." The integral equation for incident energy, which is usually derived for diffuse reflection, is replaced by a more appropriate functional equation. The latter is used to solve some specific problems and it is shown that all the classical features of specular reflection, for example, the existence of image sources, are embodied within this equation. This equation can be solved with the ray-tracing technique, despite the implemented mathematics being quite different. Several interesting features of the energy field are presented.

Specular reflectance of soiled glass mirrors - Study on the impact of incidence angles

NASA Astrophysics Data System (ADS)

Heimsath, Anna; Lindner, Philip; Klimm, Elisabeth; Schmid, Tobias; Moreno, Karolina Ordonez; Elon, Yehonatan; Am-Shallem, Morag; Nitz, Peter

2016-05-01

The accumulation of dust and soil on the surface of solar reflectors is an important factor reducing the power output of solar power plants. Therefore the effect of accumulated dust on the specular reflectance of solar mirrors should be understood well in order to improve the site-dependent performance prediction. Furthermore, an optimization of the CSP System maintenance, in particular the cleaning cycles, can be achieved. Our measurements show a noticeable decrease of specular reflectance when the angle of incidence is increased. This effect may be explained by shading and blocking mechanisms caused by dirt particles. The main physical causes of radiation loss being absorption and scattering, the near-angle scattering leads to a further decrease of specular reflectance for smaller angles of acceptance. Within this study mirror samples were both outdoor exposed and indoor artificially soiled. For indoor soiling, the mirror samples were artificially soiled in an in-house developed dusting device using both artificial-standardized dust and real dust collected from an arid outdoor test field at the Negev desert. A model function is proposed that approximates the observed reduction of specular reflectance with the incidence angle with a sufficient accuracy and by simple means for this soil type. Hence a first step towards a new approach to improve site dependent performance prediction of solar power plants is taken.

Conformal Membrane Reflectors for Deployable Optics

NASA Technical Reports Server (NTRS)

Hood, Patrick J.; Keys, Andrew S. (Technical Monitor)

2002-01-01

This presentation reports the Phase I results on NASA's Gossamer Spacecraft Exploratory Research and Technology Program. Cornerstone Research Group, Inc., the University of Rochester, and International Photonics Consultants collaborated to investigate the feasibility of free-standing, liquid-crystal-polymer (LCP) reflectors for integration into space-based optical systems. The goal of the program was to achieve large-diameter, broadband. reflective membranes that are resistant to the effects of space, specifically cryogenic environments and gamma-ray irradiation. Additionally, we assessed the applicability of utilizing the technology as tight sails, since, by their very nature, these films offer high-reflectivity at specified wavelengths. Previous research programs have demonstrated all-polymer, narrow-band Specular reflectors and diffuse membrane reflectors. The feasibility of fabricating an all-polymer broadband specular reflector and a narrow-band specular membrane reflector was assessed in the Phase I Gossamer program. In addition, preliminary gamma irradiation studies were conducted to determine the stability of the polymer reflectors to radiation. Materials and process technology were developed to fabricate coupon-scale reflectors of both broad- and narrow-band specular reflectors in Phase 1. This presentation will report the results of these studies, including, the performance of a narrow-band specular membrane. Gamma irradiation exposures indicate limited impact on the optical performance although additional exposure studies are warranted. Plans to scale up the membrane fabrication process will be presented.

Specular Reflection from Rough Surfaces Revisited

ERIC Educational Resources Information Center

Yasuda, Kensei; Kim, Alvin; Cho, Hayley; Timofejev, Timofej; Walecki, Wojciech J.; Klep, James; Edelson, Amy S.; Walecki, Abigail S.; Walecki, Eve S.; Walecki, Peter S.

2016-01-01

In his beautiful paper, Hasan Fakhruddin reported observations of mirror-like reflections in the rough surface of a ground glass plate. Similar effects have been recently employed for metrology of the roughness of optical diffusers used in modern light emitting device illumination systems. We report the observations of specular reflection in…

Shading of a computer-generated hologram by zone plate modulation.

PubMed

Kurihara, Takayuki; Takaki, Yasuhiro

2012-02-13

We propose a hologram calculation technique that enables reconstructing a shaded three-dimensional (3D) image. The amplitude distributions of zone plates, which generate the object points that constitute a 3D object, were two-dimensionally modulated. Two-dimensional (2D) amplitude modulation was determined on the basis of the Phong reflection model developed for computer graphics, which considers the specular, diffuse, and ambient reflection light components. The 2D amplitude modulation added variable and constant modulations: the former controlled the specular light component and the latter controlled the diffuse and ambient components. The proposed calculation technique was experimentally verified. The reconstructed image showed specular reflection that varied depending on the viewing position.

Effect of sampling location on L* values and pH measurements and their relationship in broiler breast fillets

USDA-ARS?s Scientific Manuscript database

Lightness (CIELAB L*) and pH values are the most widely measured quality indicators for broiler breast fillets (pectoralis major). Measurement of L* values with a spectrophotometer can be done through Specular Component Included (SCI) or Specular Component Excluded (SCE) modes. The intra-fillet loca...

Three-Dimensional Shape Measurements of Specular Objects Using Phase-Measuring Deflectometry

PubMed Central

Wang, Yuemin; Huang, Shujun; Liu, Yue; Chang, Caixia; Gao, Feng; Jiang, Xiangqian

2017-01-01

The fast development in the fields of integrated circuits, photovoltaics, the automobile industry, advanced manufacturing, and astronomy have led to the importance and necessity of quickly and accurately obtaining three-dimensional (3D) shape data of specular surfaces for quality control and function evaluation. Owing to the advantages of a large dynamic range, non-contact operation, full-field and fast acquisition, high accuracy, and automatic data processing, phase-measuring deflectometry (PMD, also called fringe reflection profilometry) has been widely studied and applied in many fields. Phase information coded in the reflected fringe patterns relates to the local slope and height of the measured specular objects. The 3D shape is obtained by integrating the local gradient data or directly calculating the depth data from the phase information. We present a review of the relevant techniques regarding classical PMD. The improved PMD technique is then used to measure specular objects having discontinuous and/or isolated surfaces. Some influential factors on the measured results are presented. The challenges and future research directions are discussed to further advance PMD techniques. Finally, the application fields of PMD are briefly introduced. PMID:29215600

Modeling of efficient light extraction in light-pipes through specular surfaces with elliptical and lineal front shapes

NASA Astrophysics Data System (ADS)

Sánchez-Guerrero, Guillermo E.; Viera-González, Perla M.; Ceballos-Herrera, Daniel E.; Martínez-Guerra, Edgar

2016-09-01

Extraction light in light-pipes with different specular surfaces was analyzed. In the analysis, the impact of the surface shape in all properties of the extracted light in order to obtain an efficient extraction and a uniform illumination using a LED as light source. Also, several parameters of the specular surface to obtain spatial uniformity inside the light-pipe are considered. In this case, the simulation was made for a rectangular light­pipe. One objective of this work is to compare how the front face shape of the specular surface can affect the extraction of light in the lateral face of the light-pipe, only straight and elliptical front faces were used in this work and the comparison between them at different tilts and lengths were made. The main purpose of the front face was extract the light uniformly at the lateral face and this was done by studying simulations on OpticStudio Zemax. The results show how the extraction length is lower in the elliptical front but its total power performs better than the line front.

Three-Dimensional Shape Measurements of Specular Objects Using Phase-Measuring Deflectometry.

PubMed

Zhang, Zonghua; Wang, Yuemin; Huang, Shujun; Liu, Yue; Chang, Caixia; Gao, Feng; Jiang, Xiangqian

2017-12-07

The fast development in the fields of integrated circuits, photovoltaics, the automobile industry, advanced manufacturing, and astronomy have led to the importance and necessity of quickly and accurately obtaining three-dimensional (3D) shape data of specular surfaces for quality control and function evaluation. Owing to the advantages of a large dynamic range, non-contact operation, full-field and fast acquisition, high accuracy, and automatic data processing, phase-measuring deflectometry (PMD, also called fringe reflection profilometry) has been widely studied and applied in many fields. Phase information coded in the reflected fringe patterns relates to the local slope and height of the measured specular objects. The 3D shape is obtained by integrating the local gradient data or directly calculating the depth data from the phase information. We present a review of the relevant techniques regarding classical PMD. The improved PMD technique is then used to measure specular objects having discontinuous and/or isolated surfaces. Some influential factors on the measured results are presented. The challenges and future research directions are discussed to further advance PMD techniques. Finally, the application fields of PMD are briefly introduced.

Subjective and objective perceptions of specular gloss and surface roughness of esthetic resin composites before and after artificial aging.

PubMed

Barucci-Pfister, Nadine; Göhring, Till N

2009-04-01

To correlate measurements of specular gloss and surface roughness of resin composite materials with subjective perception of luster before and after artificial aging. Polished specimens of eight composites were compared with human enamel (HE): microfilled SR Adoro (SR); microhybrid Artemis (AR), Enamel HFO (EHFO), Miris (MI), Tetric Ceram (TC), Venus (VE); and nanohybrid CeramX (CX) and nanofilled Filtek Supreme (FS). Before, during and after artificial aging (6000 thermal changes between 5 degrees C and 50 degrees C in an artificial oral environment, 240 hours storage in a container with ethanol, 300 minutes of toothbrushing), specular gloss and surface roughness were measured. Initial and endpoint gloss results were correlated with subjective luster rankings of 10 individuals. Artificial aging resulted in minor (EHFO, CX, FS), moderate (SR, MI, TC, VE) to high (AR) increases in surface roughness. Specular gloss decreased linearly for SR and FS, but decreased after an initial increase for all other materials. Subjectively, AR and FS were rated more and TC, VE and CX less lustrous than HE at baseline. After aging, luster of EHFO and FS was ranked higher and AR, TC, and VE lower than HE. Surface roughness was consistent with subjective perceptions (correlation coefficient: initial r = 0.913; endpoint r = 0.944, P < or = 0.0006), whereas specular gloss was consistent with subjective perceptions only after artificial aging (initial r = 0.616, P = 0.1084; endpoint r = 0.834, P = 0.0072).

Chemical properties and GMR improvement of specular spin valves with nano-oxide layers, formed in ambient mixed gases

NASA Astrophysics Data System (ADS)

Quang, H. D.; Hien, N. T.; Oh, S. K.; Sinh, N. H.; Yu, S. C.

2004-12-01

Specular spin valves (SVs) containing nano-oxide layers (NOLs) structured as substrate/seed/AF/P1/NOL/P2/Cu/F/NOL, have been fabricated. The NOLs were formed by natural oxidation in different ambient atmospheres of pure oxygen, oxygen/nitrogen and oxygen/argon gas mixtures. The fabrication conditions were optimized to enhance the magnetoresistance (MR) ratio, to suppress the interlayer coupling fields (Hf) between the free and pinned layers, to suppress the high interface density of the NOL, to ease the control of the NOL thickness and to form a smooth NOL/P2 interface for promoting specular electron scattering. The characteristics of our specular SVs are the MR ratio of 14.1%, the exchange bias field of 44-45 mT, and Hf weaker than 1.0 mT. The optimal conditions for oxidation time, total oxidation pressure and the annealing temperature were found to be 300 s, 0.14 Pa (oxygen/argon = 80/20) and 250°C, respectively. Also, the origin of thermal stability of MMn-based (M = Fe, Pt, Ir, etc) specular SVs has been explained in detail by chemical properties of NOL using secondary-ion mass spectroscopy and x-ray photoelectron spectroscopy depth profile analyses. Thermal stability turns out to be caused by a decrease in MR ratios at high temperatures (>250°C), which is a serious problem for device applications using the SV structure as a high density read head device.

Improved classification and visualization of healthy and pathological hard dental tissues by modeling specular reflections in NIR hyperspectral images

NASA Astrophysics Data System (ADS)

Usenik, Peter; Bürmen, Miran; Fidler, Aleš; Pernuš, Franjo; Likar, Boštjan

2012-03-01

Despite major improvements in dental healthcare and technology, dental caries remains one of the most prevalent chronic diseases of modern society. The initial stages of dental caries are characterized by demineralization of enamel crystals, commonly known as white spots, which are difficult to diagnose. Near-infrared (NIR) hyperspectral imaging is a new promising technique for early detection of demineralization which can classify healthy and pathological dental tissues. However, due to non-ideal illumination of the tooth surface the hyperspectral images can exhibit specular reflections, in particular around the edges and the ridges of the teeth. These reflections significantly affect the performance of automated classification and visualization methods. Cross polarized imaging setup can effectively remove the specular reflections, however is due to the complexity and other imaging setup limitations not always possible. In this paper, we propose an alternative approach based on modeling the specular reflections of hard dental tissues, which significantly improves the classification accuracy in the presence of specular reflections. The method was evaluated on five extracted human teeth with corresponding gold standard for 6 different healthy and pathological hard dental tissues including enamel, dentin, calculus, dentin caries, enamel caries and demineralized regions. Principal component analysis (PCA) was used for multivariate local modeling of healthy and pathological dental tissues. The classification was performed by employing multiple discriminant analysis. Based on the obtained results we believe the proposed method can be considered as an effective alternative to the complex cross polarized imaging setups.

Polarimetric phenomenology in the reflective regime: a case study using polarized hyperspectral data

NASA Astrophysics Data System (ADS)

Gibney, Mark

2016-05-01

Understanding the phenomenology of polarimetric data is necessary if we want to obtain the maximum benefit when we exploit that data. To first order, polarimetric phenomenology is driven by two things; the target material type (specular or diffuse) and the illuminating source (point (sun) or extended (body emission)). Polarimetric phenomenology can then be broken into three basic categories; ([specular material/sun source], [diffuse/sun], [specular/body]) where we have assigned body emission to the IR passband where materials are generally specular. The task of interest determines the category of interest since the task determines the dominant target material and the illuminating source (eg detecting diffuse targets under trees in VNIR = [diffuse/sun] category). In this paper, a specific case study for the important [diffuse/sun] category will be presented. For the reflective regime (0.3 - 3.0um), the largest polarimetric signal is obtained when the sun illuminates a significant portion of the material BRDF lobe. This naturally points us to problems whose primary target materials are diffuse since the BRDF lobe for specular materials is tiny (low probability of acquiring on the BRDF lobe) and glinty (high probability of saturating the sensor when on lobe). In this case study, we investigated signatures of solar illuminated diffuse paints acquired by a polarimetric hyperspectral sensor. We will discuss the acquisition, reduction and exploitation of that data, and use it to illustrate the primary characteristics of reflective polarimetric phenomenology.

Towards robust specularity detection and inpainting in cardiac images

NASA Astrophysics Data System (ADS)

Alsaleh, Samar M.; Aviles, Angelica I.; Sobrevilla, Pilar; Casals, Alicia; Hahn, James

2016-03-01

Computer-assisted cardiac surgeries had major advances throughout the years and are gaining more popularity over conventional cardiac procedures as they offer many benefits to both patients and surgeons. One obvious advantage is that they enable surgeons to perform delicate tasks on the heart while it is still beating, avoiding the risks associated with cardiac arrest. Consequently, the surgical system needs to accurately compensate the physiological motion of the heart which is a very challenging task in medical robotics since there exist different sources of disturbances. One of which is the bright light reflections, known as specular highlights, that appear on the glossy surface of the heart and partially occlude the field of view. This work is focused on developing a robust approach that accurately detects and removes those highlights to reduce their disturbance to the surgeon and the motion compensation algorithm. As a first step, we exploit both color attributes and Fuzzy edge detector to identify specular regions in each acquired image frame. These two techniques together work as restricted thresholding and are able to accurately identify specular regions. Then, in order to eliminate the specularity artifact and give the surgeon a better perception of the heart, the second part of our solution is dedicated to correct the detected regions using inpainting to propagate and smooth the results. Our experimental results, which we carry out in realistic datasets, reveal how efficient and precise the proposed solution is, as well as demonstrate its robustness and real-time performance.

Polarization Signals of Common Spacecraft Materials

NASA Technical Reports Server (NTRS)

Gravseth, Ian; Culp, Robert D.; King, Nicole

1996-01-01

This is the final report documenting the results of the polarization testing of near-planar objects with various reflectance properties. The purpose of this investigation was to determine the portion of the reflected signal which is polarized for materials commonly used in space applications. Tests were conducted on several samples, with surface characteristics ranging from highly reflective to relatively dark. The measurements were obtained by suspending the test object in a beam of collimated light. The amount of light falling on the sample was controlled by a circular aperture placed in the light field. The polarized reflectance at various phase angles was then measured. A nonlinear least squares fitting program was used for analysis. For the specular test objects, the reflected signals were measured in one degree increments near the specular point. Otherwise, measurements were taken every five degrees in phase angle. Generally, the more diffuse surfaces had lower polarized reflectances than their more specular counterparts. The reflected signals for the more diffuse surfaces were spread over a larger phase angle range, while the signals from the more specular samples were reflected almost entirely within five degrees of angular deviation from the specular point. The method used to test all the surfaces is presented. The results of this study will be used to support the NASA Orbital Debris Optical Signature Tests. These tests are intended to help better understand the reflectance properties of materials often used in space applications. This data will then be used to improve the capabilities for identification and tracking of space debris.

On specular reflectivity measurements in high and low-contrast relativistic laser-plasma interactions

NASA Astrophysics Data System (ADS)

Kemp, G. E.; Link, A.; Ping, Y.; McLean, H. S.; Patel, P. K.; Freeman, R. R.; Schumacher, D. W.; Tiedje, H. F.; Tsui, Y. Y.; Ramis, R.; Fedosejevs, R.

2015-01-01

Using both experiment and 2D3V particle-in-cell (PIC) simulations, we describe the use of specular reflectivity measurements to study relativistic (Iλ2 > 1018 W/cm2ṡμm2) laser-plasma interactions for both high and low-contrast 527 nm laser pulses on initially solid density aluminum targets. In the context of hot-electron generation, studies typically rely on diagnostics which, more-often-than-not, represent indirect processes driven by fast electrons transiting through solid density materials. Specular reflectivity measurements, however, can provide a direct measure of the interaction that is highly sensitive to how the EM fields and plasma profiles, critical input parameters for modeling of hot-electron generation, evolve near the interaction region. While the fields of interest occur near the relativistic critical electron density, experimental reflectivity measurements are obtained centimeters away from the interaction region, well after diffraction has fully manifested itself. Using a combination of PIC simulations with experimentally inspired conditions and an analytic, non-paraxial, pulse propagation algorithm, we calculate reflected pulse properties, both near and far from the interaction region, and compare with specular reflectivity measurements. The experiment results and PIC simulations demonstrate that specular reflectivity measurements are an extremely sensitive qualitative, and partially quantitative, indicator of initial laser/target conditions, ionization effects, and other details of intense laser-matter interactions. The techniques described can provide strong constraints on many systems of importance in ultra-intense laser interactions with matter.

Stroke Hemiplegia and Specular Image: Lessons from Self-Portraits

ERIC Educational Resources Information Center

Morin, Catherine; Pradat-Diehl, Pascale; Robain, Gilberte; Bensalah, Yamina; Perrigot, Michel

2003-01-01

Hemiplegic patients suffer from difficulties in self-awareness, either due to specific neurological disturbances of body image or to psychological problems with their I images. Both types of difficulty have to do with the specular image as defined by Lacan (1966a) (i.e., the psychic structure that links the body with the "symbolic" and "imaginary"…

Quasi-resonant enhancement of a grazing diffracted wave and deep suppression of specular reflection on shallow metal gratings in terahertz

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tymchenko, M., E-mail: mtymchenko@utexas.edu; Gavrikov, V. K.; Spevak, I. S.

2015-06-29

We report on a previously unexamined anomaly at diffraction of THz radiation on metal gratings. This anomaly consists in a nearly complete redirection of energy to a non-specular homogeneous diffraction order propagating at a specific grazing angle and deep suppression of the specular reflection. We show that this anomaly is located far enough from the well-known one caused by the resonant excitation of the surface plasmon-polariton. The effect under consideration is of general nature and can exist in all spectrum regions; however, it is especially pronounced in THz region, where it should be taken into account when analyzing relevant experimentalmore » results.« less

The effects of transducer geometry on artifacts common to diagnostic bone imaging with conventional medical ultrasound.

PubMed

Mauldin, F William; Owen, Kevin; Tiouririne, Mohamed; Hossack, John A

2012-06-01

The portability, low cost, and non-ionizing radiation associated with medical ultrasound suggest that it has potential as a superior alternative to X-ray for bone imaging. However, when conventional ultrasound imaging systems are used for bone imaging, clinical acceptance is frequently limited by artifacts derived from reflections occurring away from the main axis of the acoustic beam. In this paper, the physical source of off-axis artifacts and the effect of transducer geometry on these artifacts are investigated in simulation and experimental studies. In agreement with diffraction theory, the sampled linear-array geometry possessed increased off-axis energy compared with single-element piston geometry, and therefore, exhibited greater levels of artifact signal. Simulation and experimental results demonstrated that the linear-array geometry exhibited increased artifact signal when the center frequency increased, when energy off-axis to the main acoustic beam (i.e., grating lobes) was perpendicularly incident upon off-axis surfaces, and when off-axis surfaces were specular rather than diffusive. The simulation model used to simulate specular reflections was validated experimentally and a correlation coefficient of 0.97 between experimental and simulated peak reflection contrast was observed. In ex vivo experiments, the piston geometry yielded 4 and 6.2 dB average contrast improvement compared with the linear array when imaging the spinous process and interlaminar space of an animal spine, respectively. This work indicates that off-axis reflections are a major source of ultrasound image artifacts, particularly in environments comprising specular reflecting (i.e., bone or bone-like) objects. Transducer geometries with reduced sensitivity to off-axis surface reflections, such as a piston transducer geometry, yield significant reductions in image artifact.

Nanostructured PdO Thin Film from Langmuir-Blodgett Precursor for Room-Temperature H2 Gas Sensing.

PubMed

Choudhury, Sipra; Betty, C A; Bhattacharyya, Kaustava; Saxena, Vibha; Bhattacharya, Debarati

2016-07-06

Nanoparticulate thin films of PdO were prepared using the Langmuir-Blodgett (LB) technique by thermal decomposition of a multilayer film of octadecylamine (ODA)-chloropalladate complex. The stable complex formation of ODA with chloropalladate ions (present in subphase) at the air-water interface was confirmed by the surface pressure-area isotherm and Brewster angle microscopy. The formation of nanocrystalline PdO thin film after thermal decomposition of as-deposited LB film was confirmed by X-ray diffraction and Raman spectroscopy. Nanocrystalline PdO thin films were further characterized by using UV-vis and X-ray photoelectron spectroscopic (XPS) measurements. The XPS study revealed the presence of prominent Pd(2+) with a small quantity (18%) of reduced PdO (Pd(0)) in nanocrystalline PdO thin film. From the absorption spectroscopic measurement, the band gap energy of PdO was estimated to be 2 eV, which was very close to that obtained from specular reflectance measurements. Surface morphology studies of these films using atomic force microscopy and field-emission scanning electron microscopy indicated formation of nanoparticles of size 20-30 nm. These PdO film when employed as a chemiresistive sensor showed H2 sensitivity in the range of 30-4000 ppm at room temperature. In addition, PdO films showed photosensitivity with increase in current upon shining of visible light.

Neutral ion sources in precision manufacturing

NASA Technical Reports Server (NTRS)

Fawcett, Steven C.; Drueding, Thomas W.

1994-01-01

Ion figuring of optical components is a relatively new technology that can alleviate some of the problems associated with traditional contact polishing. Because the technique is non contacting, edge distortions and rib structure print through do not occur. This initial investigation was aimed at determining the effect of ion figuring on surface roughness of previously polished or ductile ground ceramic optical samples. This is the first step in research directed toward the combination of a pre-finishing process (ductile grinding or polishing) with ion figuring to produce finished ceramic mirrors. The second phase of the project is focusing on the development of mathematical algorithms that will deconvolve the ion beam profile from the surface figure errors so that these errors can be successfully removed from the optical components. In the initial phase of the project, multiple, chemical vapor deposited silicon carbide (CVD SiC) samples were polished or ductile ground to specular or near-specular roughness. These samples were then characterized to determine topographic surface information. The surface evaluation consisted of stylus profilometry, interferometry, and optical and scanning electron microscopy. The surfaces, were ion machined to depths from 0-5 microns. The finished surfaces were characterized to evaluate the effects of the ion machining process with respect to the previous processing methods and the pre-existing subsurface damage. The development of the control algorithms for figuring optical components has been completed. These algorithms have been validated with simulations and future experiments have been planned to verify the methods. This paper will present the results of the initial surface finish experiments and the control algorithms simulations.

AC electrokinetic drug delivery in dentistry using an interdigitated electrode assembly powered by inductive coupling.

PubMed

Ivanoff, Chris S; Wu, Jie Jayne; Mirzajani, Hadi; Cheng, Cheng; Yuan, Quan; Kevorkyan, Stepan; Gaydarova, Radostina; Tomlekova, Desislava

2016-10-01

AC electrokinetics (ACEK) has been shown to deliver certain drugs into human teeth more effectively than diffusion. However, using electrical wires to power intraoral ACEK devices poses risks to patients. The study demonstrates a novel interdigitated electrode arrays (IDE) assembly powered by inductive coupling to induce ACEK effects at appropriate frequencies to motivate drugs wirelessly. A signal generator produces the modulating signal, which multiplies with the carrier signal to produce the amplitude modulated (AM) signal. The AM signal goes through the inductive link to appear on the secondary coil, then rectified and filtered to dispose of its carrier signal, and the positive half of the modulating signal appears on the load. After characterizing the device, the device is validated under light microscopy by motivating carboxylate-modified microspheres, tetracycline, acetaminophen, benzocaine, lidocaine and carbamide peroxide particles with induced ACEK effects. The assembly is finally tested in a common dental bleaching application. After applying 35 % carbamide peroxide to human teeth topically or with the IDE at 1200 Hz, 5 Vpp for 20 min, spectrophotometric analysis showed that compared to diffusion, the IDE enhanced whitening in specular optic and specular optic excluded modes by 215 % and 194 % respectively. Carbamide peroxide absorbance by the ACEK group was two times greater than diffusion as measured by colorimetric oxidation-reduction and UV-Vis spectroscopy at 550 nm. The device motivates drugs of variable molecular weight and structure wirelessly. Wireless transport of drugs to intraoral targets under ACEK effects may potentially improve the efficacy and safety of drug delivery in dentistry.

Gloss measurements and rugometric inspection in dental biomaterials

NASA Astrophysics Data System (ADS)

Fernández-Oliveras, Alicia; Costa, Manuel F. M.; Yebra, Ana; Rubiño, Manuel; Pérez, María. M.

2013-11-01

In dental applications, optimizing appearance is desirable and increasingly demanded by patients. The specular gloss is among the major appearance properties of dental biomaterials, and its relationship with surface roughness has been reported. Roughness and gloss are key surface aspects that complement each other. We have experimentally analyzed the specular gloss and surface roughness of two different types of dental-resin composites and pre-sintered and sintered zirconia ceramics. We have studied two shades of both composite types and two sintered zirconia ceramics: colored and uncolored. Moreover, a surface treatment was applied to one specimen of each dental resin. Gloss measurements were performed with a standardized reflectometer and the corresponding gloss percentages were calculated. All the samples were submitted to rugometric non-invasive inspection with the MICROTOP.06.MFC laser microtopographer in order to determine meaningful statistical parameters such as the average roughness (Ra) and the root-mean-square deviation (Rq). For a comparison of the different biomaterials, the uncertainties associated to the measure of the surface gloss and roughness were also determined. The differences between the two shades of both kinds of composites proved significant in the case of the roughness parameters but not for the specular gloss. The surface treatment applied to the dental-resin composites increased the average roughness but the changes in the specular gloss were significant only for the A2 enamel nano-composite. For the zirconia ceramic the sintered process resulted in an increase in the surface roughness with a decrease of the specular gloss, corroborating that the relationship between the gloss and the roughness shows the expected behavior.

Metrological issues related to BRDF measurements around the specular direction in the particular case of glossy surfaces

NASA Astrophysics Data System (ADS)

Obein, Gaël.; Audenaert, Jan; Ged, Guillaume; Leloup, Frédéric B.

2015-03-01

Among the complete bidirectional reflectance distribution function (BRDF), visual gloss is principally related to physical reflection characteristics located around the specular reflection direction. This particular part of the BRDF is usually referred to as the specular peak. A good starting point for the physical description of gloss could be to measure the reflection properties around this specular peak. Unfortunately, such a characterization is not trivial, since for glossy surfaces the width of the specular peak can become very narrow (typically a full width at half maximum inferior to 0.5° is encountered). In result, new BRDF measurement devices with a very small solid angle of detection are being introduced. Yet, differences in the optical design of BRDF measurement instruments engender different measurement results for the same specimen, complicating direct comparison of the measurement results. This issue is addressed in this paper. By way of example, BRDF measurement results of two samples, one being matte and the other one glossy, obtained by use of two high level goniospectrophotometers with a different optical design, are described. Important discrepancies in the results of the glossy sample are discussed. Finally, luminance maps obtained from renderings with the acquired BRDF data are presented, exemplifying the large visual differences that might be obtained. This stresses the metrological aspects that must be known for using BRDF data. Indeed, the comprehension of parameters affecting the measurement results is an inevitable step towards progress in the metrology of surface gloss, and thus towards a better metrology of appearance in general.

Interface-based two-way tuning of the in-plane thermal transport in nanofilms

NASA Astrophysics Data System (ADS)

Hua, Yu-Chao; Cao, Bing-Yang

2018-03-01

Here, the two-way tuning of in-plane thermal transport is obtained in the bi-layer nanofilms with an interfacial effect by using the Boltzmann transport equation (BTE) and the phonon Monte Carlo (MC) technique. A thermal conductivity model was derived from the BTE and verified by the MC simulations. Both the model and the MC simulations indicate that the tuning of the thermal transport can be bidirectional (reduced or enhanced), depending on the interface conditions (i.e., roughness and adhesion energy) and the phonon property dissimilarity at the interface. For the identical-material interface, the emergence of thermal conductivity variation requires two conditions: (a) the interface is not completely specular and (b) the transmission specularity parameter differs from the reflection specularity parameter at the interface. When the transmission specularity parameter is larger than the reflection specularity parameter at the interface, the thermal conductivity improvement effect emerges, whereas the thermal conductivity reduction effect occurs. For the disparate-material interface, the phonon property perturbation near the interface causes the thermal conductivity variation, even when neither the above two conditions are satisfied. The mean free path ratio (γ) between the disparate materials was defined to characterize the phonon property dissimilarity. γ > 1 can lead to the thermal conductivity improvement effect, while γ < 1 corresponds to the thermal conductivity reduction effect. Our work provides a more in-depth understanding of the interfacial effect on the nanoscale thermal transport, with an applicable predictive model, which can be helpful for predicting and manipulating phonon transport in nanofilms.

Diffuse and specular characteristics of leaf reflectance

NASA Technical Reports Server (NTRS)

Grant, Lois

1987-01-01

In this paper, the evolution of current understanding of the mechanisms of leaf reflectance is reviewed. The use of measurements of polarized reflectance to separate leaf reflectance into diffuse and specular components is discussed. A section on the factors influencing leaf reflectance - leaf structure and physiological disturbances - is included along with discussion on the manner in which these influences are manifested.

X-ray off-specular reflectivity studies of electrochemical pitting of Cu surfaces in sodium bicarbonate solution

NASA Astrophysics Data System (ADS)

Feng, Y. P.; Sinha, S. K.; Melendres, C. A.; Lee, D. D.

1996-02-01

We have studied the electrochemically-induced pitting process on a Cu electrode in NaHCO 3 solution using in-situ X-ray off-specular reflectivity measurements. The morphology and growth dynamics of the localized corrosion sites or pits were studied as the applied potential was varied from the cathodic region where the Cu surface is relatively free of oxide films to the anodic region where surface roughening occurs by general corrosion with concomitant formation of an oxide film. Quantitative analysis of the experimental results indicates that early pitting proceeds in favor of nucleation of pit clusters over individual pit growth. It was found that the lateral distribution of the pits is not random but exhibits a short-range order as evidenced by the appearance of a side peak in the transverse off-specular reflectivity. The position, height, and width of the peak was modeled to yield the average size, nearest-neighbor distance (within any one of the clusters), and over-all density of the pits averaged over the entire illuminated surface. In addition, measurements of the longitudinal off-specular reflectivity indicate a bimodal depth distribution for the pits, suggesting a “film breaking” type of pitting mechanism.

Specular spin-valve films with an FeCo nano-oxide layer by ion-assisted oxidation

NASA Astrophysics Data System (ADS)

Fukuzawa, Hideaki; Koi, Katsuhiko; Tomita, Hiroshi; Fuke, Hiromi Niu; Iwasaki, Hitoshi; Sahashi, Masashi

2002-05-01

We compared the specular spin-valve films with an Fe50Co50 nano-oxide layer (NOL) and a Co90Fe10 NOL in a pinned layer, prepared by natural oxidation (NO) and ion-assisted oxidation (IAO). For the IAO, an Ar-ion beam was used for the energy-assist effect during the oxidation, resulting in thermally stable NOL formation. With small oxygen exposures during the oxidation for the Fe50Co50 NOL by IAO, good ferromagnetic coupling through the NOL and high specularity at the NOL interface were concurrently obtained. Moreover, twisted coupling through the NOL was observed for the Fe50Co50 NOL by IAO for higher oxygen exposures. On the other hand, the NO did not cause large magnetoresistance (MR) enhancement for either the Co90Fe10 or Fe50Co50 NOLs, and the Co90Fe10 NOL by IAO caused weak magnetic coupling through the NOL, resulting in a small MR ratio. The Fe50Co50 NOL for small oxygen exposures is a good candidate for a final specular spin-valve film head for 100-Giga-bit per square inch recording.

Ion acceleration by multiple reflections at Martian bow shock

NASA Astrophysics Data System (ADS)

Yamauchi, M.; Futaana, Y.; Fedorov, A.; Frahm, R. A.; Dubinin, E.; Lundin, R.; Sauvaud, J.-A.; Winningham, J. D.; Barabash, S.; Holmström, M.

2012-02-01

The ion mass analyzer (IMA) on board Mars Express revealed bundled structures of ions in the energy domain within a distance of a proton gyroradius from the Martian bow shock. Seven prominent traversals during 2005 were examined when the energy-bunched structure was observed together with pick-up ions of exospheric origin, the latter of which is used to determine the local magnetic field orientation from its circular trajectory in velocity space. These seven traversals include different bow shock configurations: (a) quasi-perpendicular shock with its specular direction of the solar wind more perpendicular to the magnetic field (QT), (b) quasi-perpendicular shock with its specular reflection direction of the solar wind more along the magnetic field (FS), and (c) quasi-parallel (QL) shock. In all seven cases, the velocity components of the energy-bunched structure are consistent with multiple specular reflections of the solar wind at the bow shock up to at least two reflections. The accelerated solar wind ions after two specular reflections have large parallel components with respect to the magnetic field for both QL cases whereas the field-aligned speed is much smaller than the perpendicular speed for all QT cases.

A comparison of partially specular radiosity and ray tracing for room acoustics modeling

NASA Astrophysics Data System (ADS)

Beamer, C. Walter; Muehleisen, Ralph T.

2005-04-01

Partially specular (PS) radiosity is an extended form of the general radiosity method. Acoustic radiosity is a form of bulk transfer of radiant acoustic energy. This bulk transfer is accomplished through a system of energy balance equations that relate the bulk energy transfer of each surface in the system to all other surfaces in the system. Until now acoustic radiosity has been limited to modeling only diffuse surface reflection. The new PS acoustic radiosity method can model all real surface types, diffuse, specular and everything in between. PS acoustic radiosity also models all real source types and distributions, not just point sources. The results of the PS acoustic radiosity method are compared to those of well known ray tracing programs. [Work supported by NSF.

Hazard calculations of diffuse reflected laser radiation for the SELENE program

NASA Technical Reports Server (NTRS)

Miner, Gilda A.; Babb, Phillip D.

1993-01-01

The hazards from diffuse laser light reflections off water clouds, ice clouds, and fog and from possible specular reflections off ice clouds were assessed with the American National Standards (ANSI Z136.1-1986) for the free-electron-laser parameters under consideration for the Segmented Efficient Laser Emission for Non-Nuclear Electricity (SELENE) Program. Diffuse laser reflection hazards exist for water cloud surfaces less than 722 m in altitude and ice cloud surfaces less than 850 m in altitude. Specular reflections from ice crystals in cirrus clouds are not probable; however, any specular reflection is a hazard to ground observers. The hazard to the laser operators and any ground observers during heavy fog conditions is of such significant magnitude that the laser should not be operated in fog.

Gleaming and dull surface textures from photonic-crystal-type nanostructures in the butterfly Cyanophrys remus.

PubMed

Kertész, Krisztián; Bálint, Zsolt; Vértesy, Zofia; Márk, Géza I; Lousse, Virginie; Vigneron, Jean Pol; Rassart, Marie; Biró, László P

2006-08-01

Photonic-crystal-type nanostructures occurring in the scales of the butterfly Cyanophrys remus were investigated by optical and electron microscopy (scanning and transmission electron microscopy), reflectance measurements (specular, integrated, and goniometric), by fast Fourier transform analysis of micrographs, by modeling, and by numerical simulation of the measured reflectance data. By evaluating the collected data in a cross-correlated way, we show that the metallic blue dorsal coloration originates from scales which individually are photonic single crystals of 50 x 120 microm2 , while the matt pea-green coloration of the ventral side arises from the cumulative effect of randomly arranged, bright photonic crystallites (blue, green, and yellow) with typical diameters in the 3-10-mum range. Both structures are based on a very moderate refractive index contrast between air and chitin. Using a bleached specimen in which the pigment has decayed with time, we investigated the role of pigment in photonic-crystal material in the process of color generation. The possible biologic utility of the metallic blue (single-crystal) and dull green (polycrystal) textures both achieved with photonic crystals are briefly discussed. Potential applications in the field of colorants, flat panel displays, smart textiles, and smart papers are surveyed.

Effect of gatifloxacin ophthalmic solution 0.3% on human corneal endothelial cell density and aqueous humor gatifloxacin concentration.

PubMed

Price, Marianne O; Quillin, Clorissa; Price, Francis W

2005-07-01

To evaluate the effect of gatifloxacin ophthalmic solution 0.3% (Zymar, Allergan, Inc., Irvine, CA, USA) on corneal endothelial cell density and morphology and to measure gatifloxacin penetration into aqueous humor. This was a single-center, open-label clinical study. Ten patients undergoing standard cataract surgery and 20 nonsurgical subjects instilled gatifloxacin 0.3% four times per day for 2 days, then every 10 min for 1 hr on the third day (the surgery day for the cataract patients). Corneal endothelial cells were counted using noncontact specular microscopy. Anterior chamber fluid was withdrawn from the surgical patients, and the gatifloxacin concentration was quantified by high-pressure liquid chromatography. Baseline endothelial cell counts (mean +/- SD) were 2400 +/- 442 in the surgical group and 2520 +/- 212 in the nonsurgical group. The mean differences from baseline 1 hr after the last dose of gatifloxacin 0.3% were -51 +/- 213 (p = 0.23) in the surgical group and -7 +/- 150 (p = 0.42) in the nonsurgical group. In the nonsurgical group, the mean difference from baseline 3 weeks after the last dose was 18 +/- 147 (p = 0.71). The mean concentration (+/- SD) of gatifloxacin in aqueous humor was 1.26 +/- 0.55 microg/ml. A preoperative, prophylactic course of gatifloxacin 0.3% ophthalmic solution did not significantly affect endothelial cell density or morphology, while meaningful drug concentration was achieved in the aqueous humor.

Descemet’s Stripping Automated Endothelial Keratoplasty Outcomes Compared with Penetrating Keratoplasty from the Cornea Donor Study

PubMed Central

Price, Marianne O.; Gorovoy, Mark; Benetz, Beth A.; Price, Francis W.; Menegay, Harry J.; Debanne, Sara M.; Lass, Jonathan H.

2010-01-01

Purpose To assess outcomes 1 year after Descemet’s stripping automated endothelial keratoplasty (DSAEK) in comparison with penetrating keratoplasty (PKP) from the Specular Microscopy Ancillary Study (SMAS) of the Cornea Donor Study. Design Multicenter, prospective, nonrandomized clinical trial. Participants A total of 173 subjects undergoing DSAEK for a moderate risk condition (principally Fuchs’ dystrophy or pseudophakic/aphakic corneal edema) compared with 410 subjects undergoing PKP from the SMAS who had clear grafts with at least 1 postoperative specular image within a 15-month follow-up period. Methods The DSAEK procedures were performed by 2 experienced surgeons per their individual techniques, using the same donor and similar recipient criteria as for the PKP procedures in the SMAS performed by 68 surgeons at 45 sites, with donors provided from 31 eye banks. Graft success and complications for the DSAEK group were assessed and compared with the SMAS group. Endothelial cell density (ECD) was determined from baseline donor, 6-month (range, 5–7 months), and 12-month (range, 9–15 months) postoperative central endothelial images by the same reading center used in the SMAS. Main Outcome Measures Endothelial cell density and graft survival at 1 year. Results Although the DSAEK recipient group criteria were similar to the PKP group, Fuchs’ dystrophy was more prevalent in the DSAEK group (85% vs. 64%) and pseudophakic corneal edema was less prevalent (13% vs. 32%, P<0.001). The regraft rate within 15 months was 2.3% (DSAEK group) and 1.3% (PKP group) (P = 0.50). Percent endothelial cell loss was 34±22% versus 11±20% (6 months) and 38±22% versus 20±23% (12 months) in the DSAEK and PKP groups, respectively (both P<0.001). Preoperative diagnosis affected endothelial cell loss over time; in the PKP group, the subjects with pseudophakic/aphakic corneal edema experienced significantly higher 12-month cell loss than the subjects with Fuchs’ dystrophy (28% vs. 16%, P = 0.01), whereas in the DSAEK group, the 12-month cell loss was comparable for the 2 diagnoses (41% vs. 37%, P = 0.59). Conclusions One year post-transplantation, overall graft success was comparable for DSAEK and PKP procedures and endothelial cell loss was higher with DSAEK. PMID:20031230

Observations of specular reflective particles and layers in crystal clouds.

PubMed

Balin, Yurii S; Kaul, Bruno V; Kokhanenko, Grigorii P; Penner, Ioganes E

2011-03-28

In the present article, results of observations of high crystal clouds with high spatial and temporal resolution using the ground-based polarization LOSA-S lidar are described. Cases of occurrence of specularly reflective layers formed by particles oriented predominantly in the horizontal plane are demonstrated. Results of measuring echo-signal depolarization are compared for linear and circular polarization states of the initial laser beam.

Training effect in specular spin valves

NASA Astrophysics Data System (ADS)

Ventura, J.; Araujo, J. P.; Sousa, J. B.; Veloso, A.; Freitas, P. P.

2008-05-01

Specular spin valves show an enhanced giant magnetoresistive (GMR) ratio due to specular reflection in nano-oxide layers (NOLs) formed by the partial oxidation of CoFe pinned and free layers. The oxides that form the (pinned layer) NOL were recently shown to antiferromagnetically order at Ttilde 175K . Here, we study the training effect (TE) in MnIr/CoFe/NOL/CoFe/Cu/CoFe/NOL/Ta specular spin valves in the 300-15 K temperature range. The exchange bias direction between the MnIr and CoFe layers impressed during annealing is taken as the positive direction. The training effect is observed in antiferromagnetic (AFM)/ferromagnetic (FM) exchange systems and related to the rearrangement of interfacial AFM spin structure with the number of hysteretic cycles performed (n) , resulting in the decrease of the exchange field (Hexch) . Here, in the studied specular spin valve, TE was only observed for T<175K and is thus related to the pinned layer NOL-AFM ordering and to the evolution of the corresponding spin structure with n . We show that FM spins that are strongly coupled to AFM domains do not align with the applied positive magnetic field (H) , giving rise to a residual MR at H≫0 . Such nonsaturating MR will be related with a spin-glass-like behavior of the interfacial magnetism induced by the nano-oxide layer. The observed dependence of the training effect on the field cooling procedure is also likely associated with the existence of different spin configurations available in the magnetically disordered oxide. Furthermore, anomalous magnetoresistance cycles measured after cooling runs under -500Oe are here related to induced NOL exchange bias/applied magnetic field misalignment. The temperature dependence of the training effect was obtained and fitted by using a recent theoretical model.

System for characterizing semiconductor materials and photovoltaic device

DOEpatents

Sopori, B.L.

1996-12-03

Apparatus for detecting and mapping defects in the surfaces of polycrystalline material in a manner that distinguishes dislocation pits from grain boundaries includes a first laser of a first wavelength for illuminating a wide spot on the surface of the material, a second laser of a second relatively shorter wavelength for illuminating a relatively narrower spot on the surface of the material, a light integrating sphere with apertures for capturing light scattered by etched dislocation pits in an intermediate range away from specular reflection while allowing light scattered by etched grain boundaries in a near range from specular reflection to pass through, and optical detection devices for detecting and measuring intensities of the respective intermediate scattered light and near specular scattered light. A center blocking aperture or filter can be used to screen out specular reflected light, which would be reflected by nondefect portions of the polycrystalline material surface. An X-Y translation stage for mounting the polycrystalline material and signal processing and computer equipment accommodate raster mapping, recording, and displaying of respective dislocation and grain boundary defect densities. A special etch procedure is included, which prepares the polycrystalline material surface to produce distinguishable intermediate and near specular light scattering in patterns that have statistical relevance to the dislocation and grain boundary defect densities. A reflectance measurement of the piece of material is obtained by adding together the signals from the optical detection devices. In the case where the piece of material includes a photovoltaic device, the current induced in the device by the illuminating light can be measured with a current sensing amplifier after the light integrating sphere is moved away from the device. 22 figs.

Optical and adhesive properties of dust deposits on solar mirrors and their effects on specular reflectivity and electrodynamic cleaning for mitigating energy-yield loss

NASA Astrophysics Data System (ADS)

Mazumder, Malay; Yellowhair, Julius; Stark, Jeremy; Heiling, Calvin; Hudelson, John; Hao, Fang; Gibson, Hannah; Horenstein, Mark

2014-10-01

Large-scale solar plants are mostly installed in semi-arid and desert areas. In those areas, dust layer buildup on solar collectors becomes a major cause for energy yield loss. Development of transparent electrodynamic screens (EDS) and their applications for self-cleaning operation of solar mirrors are presented with a primary focus on the removal dust particles smaller than 30 µm in diameter while maintaining specular reflection efficiency < 90%. An EDS consists of thin rectangular array of parallel transparent conducting electrodes deposited on a transparent dielectric surface. The electrodes are insulated from each other and are embedded within a thin transparent dielectric film. The electrodes are activated using three-phase high-voltage pulses at low current (< 1 mA/m2 ). The three-phase electric field charges the deposited particles, lifts them form the substrate by electrostatic forces and propels the dust layer off of the collector's surface by a traveling wave. The cleaning process takes less than 2 minutes; needs energy less than 1 Wh/m2 without requiring any water or manual labor. The reflection efficiency can be restored > 95% of the original clean-mirror efficiency. We briefly present (1) loss of specular reflection efficiency as a function of particle size distribution of deposited dust, and (2) the effects of the electrode design and materials used for minimizing initial loss of specular reflectivity in producing EDS-integrated solar mirrors. Optimization of EDS by using a figure of merit defined by the ratio of dust removal efficiency to the initial loss of specular reflection efficiency is discussed.

Determination of the effective transverse coherence of the neutron wave packet as employed in reflectivity investigations of condensed-matter structures. I. Measurements

NASA Astrophysics Data System (ADS)

Majkrzak, Charles F.; Metting, Christopher; Maranville, Brian B.; Dura, Joseph A.; Satija, Sushil; Udovic, Terrence; Berk, Norman F.

2014-03-01

The primary purpose of this investigation is to determine the effective coherent extent of the neutron wave packet transverse to its mean propagation vector k when it is prepared in a typical instrument used to study the structure of materials in thin film form via specular reflection. There are two principal reasons for doing so. One has to do with the fundamental physical interest in the characteristics of a free neutron as a quantum object, while the other is of a more practical nature, relating to the understanding of how to interpret elastic scattering data when the neutron is employed as a probe of condensed-matter structure on an atomic or nanometer scale. Knowing such a basic physical characteristic as the neutron's effective transverse coherence can dictate how to properly analyze specular reflectivity data obtained for material film structures possessing some amount of in-plane inhomogeneity. In this study we describe a means of measuring the effective transverse coherence length of the neutron wave packet by specular reflection from a series of diffraction gratings of different spacings. Complementary nonspecular measurements of the widths of grating reflections were also performed, which corroborate the specular results. (This paper principally describes measurements interpreted according to the theoretical picture presented in a companion paper.) Each grating was fabricated by lift-off photolithography patterning of a nickel film (approximately 1000 Å thick) formed by physical vapor deposition on a flat silicon crystal surface. The grating periods ranged from 10 μm (5 μm Ni stripe, 5 μm intervening space) to several hundred microns. The transverse coherence length, modeled as the width of the wave packet, was determined from an analysis of the specular reflectivity curves of the set of gratings.

Study of interface correlation in W/C multilayer structure by specular and non-specular grazing incidence X-ray reflectivity measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Biswas, A., E-mail: arupb@barc.gov.in; Bhattacharyya, D.; Sahoo, N. K.

2015-10-28

W/C/W tri-layer thin film samples have been deposited on c-Si substrates in a home-built Ion Beam Sputtering system at 1.5 × 10{sup −3} Torr Ar working pressure and 10 mA grid current. The tri-layer samples have been deposited at different Ar{sup +} ion energies between 0.6 and 1.2 keV for W layer deposition and the samples have been characterized by specular and non-specular grazing incidence X-ray reflectivity (GIXR) measurements. By analyzing the GIXR spectra, various interface parameters have been obtained for both W-on-C and C-on-W interfaces and optimum Ar{sup +} ion energy for obtaining interfaces with low imperfections has been found. Subsequently, multilayermore » W/C samples with 5-layer, 7-layer, 9-layer, and 13-layer have been deposited at this optimum Ar{sup +} ion energy. By fitting the specular and diffused GIXR data of the multilayer samples with the parameters of each interface as fitting variables, different interface parameters, viz., interface width, in-plane correlation length, interface roughness, and interface diffusion have been estimated for each interface and their variation across the depth of the multilayers have been obtained. The information would be useful in realizing W/C multilayers for soft X-ray mirror application in the <100 Å wavelength regime. The applicability of the “restart of the growth at the interface” model in the case of these ion beam sputter deposited W/C multilayers has also been investigated in the course of this study.« less

System for characterizing semiconductor materials and photovoltaic device

DOEpatents

Sopori, Bhushan L.

1996-01-01

Apparatus for detecting and mapping defects in the surfaces of polycrystalline material in a manner that distinguishes dislocation pits from grain boundaries includes a first laser of a first wavelength for illuminating a wide spot on the surface of the material, a second laser of a second relatively shorter wavelength for illuminating a relatively narrower spot on the surface of the material, a light integrating sphere with apertures for capturing light scattered by etched dislocation pits in an intermediate range away from specular reflection while allowing light scattered by etched grain boundaries in a near range from specular reflection to pass through, and optical detection devices for detecting and measuring intensities of the respective intermediate scattered light and near specular scattered light. A center blocking aperture or filter can be used to screen out specular reflected light, which would be reflected by nondefect portions of the polycrystalline material surface. An X-Y translation stage for mounting the polycrystalline material and signal processing and computer equipment accommodate raster mapping, recording, and displaying of respective dislocation and grain boundary defect densities. A special etch procedure is included, which prepares the polycrystalline material surface to produce distinguishable intermediate and near specular light scattering in patterns that have statistical relevance to the dislocation and grain boundary defect densities. A reflectance measurement of the piece of material is obtained by adding together the signals from the optical detection devices. In the case where the piece of material includes a photovoltaic device, the current induced in the device by the illuminating light can be measured with a current sensing amplifier after the light integrating sphere is moved away from the device.

Goniometric measurements of light scattered in the principal plane from leaves

NASA Technical Reports Server (NTRS)

Brakke, Thomas W.

1992-01-01

A laboratory goniometer was designed and built by NASA for acquiring bidirectional scattering data in the principal plane from leaves. Goniometric measurements were taken on individual tree leaves of yellow poplar, red maple, and red oak. Reflectance measurements were taken every 5* and transmittance measurements every 10 in the principal plane. The results indicate that light reflected from leaves usually has a significant specular component. Reflectances measured for 60 incident angle were the most specular. The most isotropic scattering occurred with transmitted light and with 0 incident light reflected from the abaxial surface. The most significant difference observed between the species was due to the heavy wax layer found on the abaxial surface of red oak, which caused the abaxial reflectance to be more specular than it was in the other two species.

Attitude Estimation for Unresolved Agile Space Objects with Shape Model Uncertainty

DTIC Science & Technology

2012-09-01

Simulated lightcurve data using the Cook-Torrance [8] Bidirectional Reflectivity Distribution Function ( BRDF ) model was first applied in a batch estimation...framework to ellipsoidal SO models in geostationary orbits [9]. The Ashikhmin-Shirley [10] BRDF has also been used to study estimation of specular...non-convex 300 facet model and simulated lightcurves using a combination of Lambertian and Cook-Torrance (specular) BRDF models with an Unscented

Nano-oxide-layer insertion and specular effects in spin valves: Experiment and theory

NASA Astrophysics Data System (ADS)

Wang, L.; Qiu, J. J.; McMahon, W. J.; Li, K. B.; Wu, Y. H.

2004-06-01

We report a systematic study of NOL (nano-oxide-layer) insertion and specular effects on the giant magnetoresistance (GMR) of single, synthetic, and dual spin valves, using a semiclassical Boltzmann theory. It is confirmed that the GMR ratio is enhanced by NOL insertion inside the pinned layer or after the free layer. The enhancements are primarily due to the contribution of the majority carriers. The NOL insertions inside the inactive layers of spin valves such as the seed, under, and capping layers reduce the GMR ratio. Though introducing a NOL before or after the Cu spacer would, in principle, significantly suppress the GMR ratio due to the blocking effect or the average effect of different spin channels, large positive or negative (inverse) GMR is found by assuming spin-dependent NOL specular reflections. We have also demonstrated that specular reflection, even beyond a capping layer, may result in reduction of GMR. Upon appropriate NOL insertion, the amplitude of curve of GMR versus thickness of individual layer of spin valves may be generally enhanced, but the shape may change, depending on whether the distance of the NOL to the layer is small or large (distance effect). Finally, it is found that most results obtained for the single realistic spin valves are applicable to synthetic and dual spin valves.

A proposed experimental diagnosing of specular Andreev reflection using the spin orbit interaction

PubMed Central

Yang, Yanling; Zhao, Bing; Zhang, Ziyu; Bai, Chunxu; Xu, Xiaoguang; Jiang, Yong

2016-01-01

Based on the Dirac-Bogoliubov-de Gennes equation, we theoretically investigate the chirality-resolved transport properties through a superconducting heterojunction in the presence of both the Rashba spin orbit interaction (RSOI) and the Dresselhaus spin orbit interaction (DSOI). Our results show that, if only the RSOI is present, the chirality-resolved Andreev tunneling conductance can be enhanced in the superconducting gap, while it always shows a suppression effect for the case of the DSOI alone. In contrast to the similar dependence of the specular Andreev zero bias tunneling conductance on the SOI, the retro-Andreev zero bias tunneling conductance exhibit the distinct dependence on the RSOI and the DSOI. Moreover, the zero-bias tunneling conductances for the retro-Andreev reflection (RAR) and the specular Andreev reflection (SAR) also show a qualitative difference with respect to the barrier parameters. When the RSOI and the DSOI are finite, three orders of magnitude enhancement of specular Andreev tunneling conductance is revealed. Furthermore, by analyzing the balanced SOI case, we find that the RAR is in favor of a parabolic dispersion, but a linear dispersion is highly desired for the SAR. These results shed light on the diagnosing of the SAR in graphene when subjected to both kinds of SOI. PMID:27388426

Ion Acceleration by Multiple Reflections at Martian Bow Shock

NASA Astrophysics Data System (ADS)

Yamauchi, M.; Futaana, Y.; Fedorov, A.; Frahm, R. A.; Dubinin, E.; Lundin, R.; Sauvaud, J.-A.; Winningham, J. D.; Barabash, S.; Holmström, H.

2012-04-01

The ion mass analyzer (IMA) on board Mars Express revealed bundled structures of ions in the energy domain within a distance of a proton gyroradius from the Martian bow shock. Seven prominent traversals during 2005 were examined when the energy-bunched structure was observed together with pick-up ions of exospheric origin, the latter of which is used to determine the local magnetic field orientation from its circular trajectory in velocity space. These seven traversals include different bow shock configurations: (a) quasi-perpendicular shock with its specular direction of the solar wind more perpendicular to the magnetic field (QT), (b) quasi-perpendicular shock with its specular reflection direction of the solar wind more along the magnetic field (FS), and (c) quasi-parallel (QL) shock. In all seven cases, the velocity components of the energy-bunched structure are consistent with multiple specular reflections of the solar wind at the bow shock up to at least two reflections. The accelerated solar wind ions after two specular reflections have large parallel components with respect to the magnetic field for the QL shock whereas the field-aligned speed is much smaller than the perpendicular speed for the QT shock. The reflected ions escape into the solar wind when and only when the reflection is in the field-aligned direction.

A fundamental study of the sticking of insect residues to aircraft wings

NASA Technical Reports Server (NTRS)

Eiss, N. S., Jr.; Wightman, J. P.; Gilliam, D. R.; Siochi, E. J.

1985-01-01

The aircraft industry has long been concerned with the increase of drag on airplanes due to fouling of the wings by insects. The present research studied the effects of surface energy and surface roughness on the phenomenon of insect sticking. Aluminum plates of different roughnesses were coated with thin films of polymers with varying surface energies. The coated plates were attached to a custom jig and mounted on top of an automobile for insect collection. Contact angle measurements, X-ray photoelectron spectroscopy and specular reflectance infrared spectroscopy were used to characterize the surface before and after the insect impact experiments. Scanning electron microscopy showed the topography of insect residues on the exposed plates. Moments were calculated in order to find a correlation between the parameters studied and the amount of bugs collected on the plates. An effect of surface energy on the sticking of insect residues was demonstrated.

Pulsed laser deposition for the synthesis of monolayer WSe2

NASA Astrophysics Data System (ADS)

Mohammed, A.; Nakamura, H.; Wochner, P.; Ibrahimkutty, S.; Schulz, A.; Müller, K.; Starke, U.; Stuhlhofer, B.; Cristiani, G.; Logvenov, G.; Takagi, H.

2017-08-01

Atomically thin films of WSe2 from one monolayer up to 8 layers were deposited on an Al2O3 r-cut ( 1 1 ¯ 02 ) substrate using a hybrid-Pulsed Laser Deposition (PLD) system where a laser ablation of pure W is combined with a flux of Se. Specular X-ray reflectivities of films were analysed and were consistent with the expected thickness. Raman measurement and atomic force microscopy confirmed the formation of a WSe2 monolayer and its spatial homogeneity over the substrate. Grazing-incidence X-ray diffraction uncovered an in-plane texture in which WSe2 [ 10 1 ¯ 0 ] preferentially aligned with Al2O3 [ 11 2 ¯ 0 ]. These results present a potential to create 2D transition metal dichalcogenides by PLD, where the growth kinetics can be steered in contrast to common growth techniques like chemical vapor deposition and molecular beam epitaxy.

Radar evidence for liquid surfaces on Titan.

PubMed

Campbell, Donald B; Black, Gregory J; Carter, Lynn M; Ostro, Steven J

2003-10-17

Arecibo radar observations of Titan at 13-centimeter wavelength indicate that most of the echo power is in a diffusely scattered component but that a small specular component is present for about 75% of the subearth locations observed. These specular echoes have properties consistent with those expected for areas of liquid hydrocarbons. Knowledge of the areal extent and depth of any deposits of liquid hydrocarbons could strongly constrain the history of Titan's atmosphere and surface.

Neutron reflectometry as a tool to study magnetism.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Felcher, G. P.

1999-09-21

Polarized-neutron specular reflectometry (PNR) was developed in the 1980's as a means of measuring magnetic depth profiles in flat films. Starting from simple profiles, and gradually solving structures of greater complexity, PNR has been used to observe or clarify a variety of magnetic phenomena. It has been used to measure the absolute magnetization of films of thickness not exceeding a few atomic planes, the penetration of magnetic fields in micron-thick superconductors, and the detailed magnetic coupling across non-magnetic spacers in multilayers and superlattices. Although PNR is considered a probe of depth dependent magnetic structure, laterally averaged in the plane ofmore » the film, the development of new scattering techniques promises to enable the characterization of lateral magnetic structures. Retaining the depth-sensitivity of specular reflectivity, off-specular reflectivity may be brought to resolve in-plane structures over nanometer to micron length scales.« less

Tailoring Thin Film-Lacquer Coatings for Space Application

NASA Technical Reports Server (NTRS)

Peters, Wanda C.; Harris, George; Miller, Grace; Petro, John

1998-01-01

Thin film coatings have the capability of obtaining a wide range of thermal radiative properties, but the development of thin film coatings can sometimes be difficult and costly when trying to achieve highly specular surfaces. Given any space mission's thermal control requirements, there is often a need for a variation of solar absorptance (Alpha(s)), emittance (epsilon) and/or highly specular surfaces. The utilization of thin film coatings is one process of choice for meeting challenging thermal control requirements because of its ability to provide a wide variety of Alpha(s)/epsilon ratios. Thin film coatings' radiative properties can be tailored to meet specific thermal control requirements through the use of different metals and the variation of dielectric layer thickness. Surface coatings can be spectrally selective to enhance radiative coupling and decoupling. The application of lacquer to a surface can also provide suitable specularity for thin film application without the cost and difficulty associated with polishing.

Tailoring Thin Film-Lacquer Coatings for Space Applications

NASA Technical Reports Server (NTRS)

Peters, Wanda C.; Harris, George; Miller, Grace; Petro, John

1998-01-01

Thin film coatings have the capability of obtaining a wide range of thermal radiative properties, but the development of thin film coatings can sometimes be difficult and costly when trying to achieve highly specular surfaces. Given any space mission's then-nal control requirements, there is often a need for a variation of solar absorptance (alpha(sub s)), emittance (epsilon) and/or highly specular surfaces. The utilization of thin film coatings is one process of choice for meeting challenging thermal control requirements because of its ability to provide a wide variety of alpha(sub s)/epsilon ratios. Thin film coatings' radiative properties can be tailored to meet specific thermal control requirements through the use of different metals and the variation of dielectric layer thickness. Surface coatings can be spectrally selective to enhance radiative coupling and decoupling. The application of lacquer to a surface can also provide suitable specularity for thin film application without the cost and difficulty associated with polishing.

Detection and Purging of Specular Reflective and Transparent Object Influences in 3d Range Measurements

NASA Astrophysics Data System (ADS)

Koch, R.; May, S.; Nüchter, A.

2017-02-01

3D laser scanners are favoured sensors for mapping in mobile service robotics at indoor and outdoor applications, since they deliver precise measurements at a wide scanning range. The resulting maps are detailed since they have a high resolution. Based on these maps robots navigate through rough terrain, fulfil advanced manipulation, and inspection tasks. In case of specular reflective and transparent objects, e.g., mirrors, windows, shiny metals, the laser measurements get corrupted. Based on the type of object and the incident angle of the incoming laser beam there are three results possible: a measurement point on the object plane, a measurement behind the object plane, and a measurement of a reflected object. It is important to detect such situations to be able to handle these corrupted points. This paper describes why it is difficult to distinguish between specular reflective and transparent surfaces. It presents a 3DReflection- Pre-Filter Approach to identify specular reflective and transparent objects in point clouds of a multi-echo laser scanner. Furthermore, it filters point clouds from influences of such objects and extract the object properties for further investigations. Based on an Iterative-Closest-Point-algorithm reflective objects are identified. Object surfaces and points behind surfaces are masked according to their location. Finally, the processed point cloud is forwarded to a mapping module. Furthermore, the object surface corners and the type of the surface is broadcasted. Four experiments demonstrate the usability of the 3D-Reflection-Pre-Filter. The first experiment was made in a empty room containing a mirror, the second experiment was made in a stairway containing a glass door, the third experiment was made in a empty room containing two mirrors, the fourth experiment was made in an office room containing a mirror. This paper demonstrate that for single scans the detection of specular reflective and transparent objects in 3D is possible. It is more reliable in 3D as in 2D. Nevertheless, collect the data of multiple scans and post-filter them as soon as the object was bypassed should pursued. This is why future work concentrates on implementing a post-filter module. Besides, it is the aim to improve the discrimination between specular reflective and transparent objects.

Heteroepitaxial growth of cadmium carbonate at dolomite and calcite surfaces: Mechanisms and rates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Callagon, Erika Blanca R.; Lee, Sang Soo; Eng, Peter J.

Here, the systematic variation of rates and the mechanism of cadmium uptake on the (104) surface of dolomite (CaMg(CO 3) 2) were investigated using in situ and ex situ atomic force microscopy (AFM), ex situ specular X-ray reflectivity (XR), and ex situ X-ray fluorescence (XRF). Selected experiments were performed on the calcite (CaCO 3) (104) surface for comparison. Aqueous solutions of CdCl 2, CaCl 2, and NaHCO 3, undersaturated with respect to calcite and supersaturated with respect to otavite (CdCO 3) and the (Cd xCa 1-x)CO 3 solid solution, were reacted with dolomite surfaces for minutes to days. Calcite substratesmore » were reacted with solutions containing 1-50 μM CdCl 2, and with no added Ca or CO 3. Thin carbonate films following the Stranski-Krastanov growth mode were observed on both substrates. Specular XR and XRF revealed the formation of nm-thick Cd-rich carbonate films that were structurally ordered with respect to the dolomite (104) plane. Epitaxial films adopted the calcite crystal structure with a d 104- spacing (3.00 Å) larger than those of pure dolomite (2.88 Å) and otavite (2.95 Å) indicating either a solid solution with x approximate to 0.5, or a strained Cd-rich carbonate with a composition near that of otavite. The growth rate r of this phase increases with the initial supersaturation of the solution with respect to the solid solution, beta max, and follows the empirical relationship, as determined from XRF measurements, given by: r = 10 -4.88 ± 0.42 (β 2.29 ± 0.24 max - 1), (in units of atoms of Cd/Å 2/h).The morphology of the overgrowth also varied with β max, as exemplified by AFM observations. Growth at step edges occurred over the entire β max range considered, and additional growth features including 3 Å high monolayer islands and ~ 25 Å high tall islands were observed when log β max > 1. On calcite, in situ XR indicated that this phase is similar to the Cd-rich overgrowth formed on dolomite and images obtained from X-ray reflection interface microscopy (XRIM) reveal the existence of laterally variable Cd-rich domains.« less

Heteroepitaxial growth of cadmium carbonate at dolomite and calcite surfaces: Mechanisms and rates

DOE PAGES

Callagon, Erika Blanca R.; Lee, Sang Soo; Eng, Peter J.; ...

2016-12-10

Here, the systematic variation of rates and the mechanism of cadmium uptake on the (104) surface of dolomite (CaMg(CO 3) 2) were investigated using in situ and ex situ atomic force microscopy (AFM), ex situ specular X-ray reflectivity (XR), and ex situ X-ray fluorescence (XRF). Selected experiments were performed on the calcite (CaCO 3) (104) surface for comparison. Aqueous solutions of CdCl 2, CaCl 2, and NaHCO 3, undersaturated with respect to calcite and supersaturated with respect to otavite (CdCO 3) and the (Cd xCa 1-x)CO 3 solid solution, were reacted with dolomite surfaces for minutes to days. Calcite substratesmore » were reacted with solutions containing 1-50 μM CdCl 2, and with no added Ca or CO 3. Thin carbonate films following the Stranski-Krastanov growth mode were observed on both substrates. Specular XR and XRF revealed the formation of nm-thick Cd-rich carbonate films that were structurally ordered with respect to the dolomite (104) plane. Epitaxial films adopted the calcite crystal structure with a d 104- spacing (3.00 Å) larger than those of pure dolomite (2.88 Å) and otavite (2.95 Å) indicating either a solid solution with x approximate to 0.5, or a strained Cd-rich carbonate with a composition near that of otavite. The growth rate r of this phase increases with the initial supersaturation of the solution with respect to the solid solution, beta max, and follows the empirical relationship, as determined from XRF measurements, given by: r = 10 -4.88 ± 0.42 (β 2.29 ± 0.24 max - 1), (in units of atoms of Cd/Å 2/h).The morphology of the overgrowth also varied with β max, as exemplified by AFM observations. Growth at step edges occurred over the entire β max range considered, and additional growth features including 3 Å high monolayer islands and ~ 25 Å high tall islands were observed when log β max > 1. On calcite, in situ XR indicated that this phase is similar to the Cd-rich overgrowth formed on dolomite and images obtained from X-ray reflection interface microscopy (XRIM) reveal the existence of laterally variable Cd-rich domains.« less

Magnetoresistance of antiferromagnetic Ir22Mn78-pinned spin filter specular spin valves

NASA Astrophysics Data System (ADS)

Hwang, J. Y.; Kim, M. Y.; Rhee, J. R.; Lee, S. S.; Hwang, D. G.; Yu, S. C.; Lee, H. B.

2004-06-01

Specular spin valves (SSVs) having the spin filter layer (SFL) in contact with the ultrathin free layer of composition Ta3/NiFe2/IrMn7/CoFe1/(NOL1)/CoFe2/Cu1.8/CoFe(tF)/Cu(tSF)/(NOL2)/Ta3.5 (in nm) deposited by magnetron sputtering were studied. For these antiferromagnetic Ir22Mn78-pinned spin filter specular spin valve (SFSSV) films, an optimal magnetoresistance (MR) ratio of 11.9% was obtained when both the free layer thickness (tF) and the SFL thickness (tSF) were 1.5 nm, and a MR ratio higher than 11% was maintained even when tF was reduced to 1.0 nm. This was due to an increase of specular electrons by the nano-oxide layer (NOL) and of current shunting through the SFL. Moreover, the interlayer coupling field (Hint) between the free layer and pinned layer could be explained by considering the RKKY and magnetostatic coupling. The coercivity of the free layer (Hcf) was significantly reduced as compared to traditional spin valves (TSV), and remained as low as 4 Oe when tF varied from 1 to 4 nm. It was found that the SFL made it possible to reduce the free layer thickness and enhance the MR ratio without degrading the soft magnetic property of the free layer.

Tracking Solar Energy Conersion Unit Adapted For Field Assembly

DOEpatents

Kaminar, Neil R.; Ross, III, James G.; Carrie, Peter J.

2000-02-01

A modular solar energy collector having elongated V-shaped side walls formed by a pair of coplanar panels for each side wall. The upper panels, occupying most of the wall area are diffusely reflective, but the lower panels are specularly reflective. A Fresnel lens, having a snap fit relation to the side walls focuses some light on the lower specularly reflective panels which direct light to the solar cells at the base of the V-shaped walls. A heat sink provides support for the two panels with two opposed, upwardly extending wings terminating in opposed linear clips located near the lengthwise seam of the coplanar panels, each clip holding two coplanar panels in parallel alignment. The clips not only provide support for the panels, but also transfer heat to the remainder of the heat sink. The clips are shaped so that edges of the panels engage each clip by a snap fit, outside of the clip in one embodiment and inside of the clip in another embodiment. End caps are also formed with structures which snap to the wall panels. Since all junctions of components snap together, the collector of the present invention is easily assembled without specialized tools. Using side walls which are only partly specularly reflective permits a large angle of acceptance, yet provides an economical wall design because the entire wall need not be specularly reflective.

Surface Chemistry Interactions of Cationorm with Films by Human Meibum and Tear Film Compounds

PubMed Central

Georgiev, Georgi As.; Yokoi, Norihiko; Nencheva, Yana; Peev, Nikola; Daull, Philippe

2017-01-01

Cationorm® (CN) cationic nanoemulsion was demonstrated to enhance tear film (TF) stability in vivo possibly via effects on tear film lipid layer (TFLL). Therefore the interactions of CN with human meibum (MGS) and TFLL in vitro and in vivo deserve special study. MGS and CN were spread at the air/water interface of a Langmuir surface balance to ensure a range of MGS/CN oil phase ratios: 20/1, 10/1, 5/1, 3/1, 2/1 and 1/1. The films capability to reorganize during dynamic area changes was evaluated via the surface pressure-area compression isotherms and step/relaxation dilatational rheology studies. Films structure was monitored with Brewster angle microscopy. CN/TFLL interactions at the ocular surface were monitored with non-contact specular microscopy. The in vitro studies of MGS/CN layers showed that (i) CN inclusion (at fixed MGS content) increased film elasticity and thickness and that (ii) CN can compensate for moderate meibum deficiency in MGS/CN films. In vivo CN mixed with TFLL in a manner similar to CN/MGS interactions in vitro, and resulted in enhanced thickness of TFLL. In vitro and in vivo data complement each other and facilitated the study of the composition-structure-function relationship that determines the impact of cationic nanoemulsions on TF. PMID:28718823

Corneal endothelial morphology and function after torsional and longitudinal ultrasound mode phacoemulsification.

PubMed

Módis, László Jr; Szalai, Eszter; Flaskó, Zsuzsa; Németh, Gábor

2016-01-01

To study the endothelial cell morphology and corneal thickness changes after phacoemulsification by using the OZil torsional and longitudinal ultrasound techniques (Infiniti Vision System, Alcon Laboratories). Department of Ophthalmology, Clinical Center, University of Debrecen, Debrecen, Hungary. 52 patients with cataract were randomly assigned to longitudinal ultrasound and torsional mode group. All surgeries were performed through a 2.2 mm clear corneal incision, the method employed being divide and conquer. The endothelial morphometry such as cell density (ECD), mean cell area, coefficient of variation of cell area, and central corneal thickness were examined with specular microscopy (EM-1000, Tomey) preoperatively and 4, 8 weeks postoperatively. ECD values decreased significantly in both surgical groups (P < .001, repeated- mesures ANOVA), the postoperative endothelial cell loss was higher in the longitudinal ultrasound mode group (3.5% and 6.5%, at 4 and 8 weeks after surgery) than in the torsional group (3.3% and 5.5%, at 4 and 8 weeks after surgery), the difference not being significant between the two groups (P = .164 and P = .479, at 4 and 8 weeks after surgery, Mann-Whitney test). There was no statistically significant difference in any of the assessed parameters between the two surgical groups (P > .05). No significant correlation was found between the endothelial cell loss and the nucleus density. Both phacoemulsification techniques were safe and effective. The torsional handpiece performs oscillatory movements and delivers less energy into the eye than the longitudinal ultrasound technique, therefore providing more favorable energy and thermal safety profile.

Investigation of Overrun-Processed Porous Hyaluronic Acid Carriers in Corneal Endothelial Tissue Engineering

PubMed Central

Lai, Jui-Yang; Cheng, Hsiao-Yun; Ma, David Hui-Kang

2015-01-01

Hyaluronic acid (HA) is a linear polysaccharide naturally found in the eye and therefore is one of the most promising biomaterials for corneal endothelial regenerative medicine. This study reports, for the first time, the development of overrun-processed porous HA hydrogels for corneal endothelial cell (CEC) sheet transplantation and tissue engineering applications. The hydrogel carriers were characterized to examine their structures and functions. Evaluations of carbodiimide cross-linked air-dried and freeze-dried HA samples were conducted simultaneously for comparison. The results indicated that during the fabrication of freeze-dried HA discs, a technique of introducing gas bubbles in the aqueous biopolymer solutions can be used to enlarge pore structure and prevent dense surface skin formation. Among all the groups studied, the overrun-processed porous HA carriers show the greatest biological stability, the highest freezable water content and glucose permeability, and the minimized adverse effects on ionic pump function of rabbit CECs. After transfer and attachment of bioengineered CEC sheets to the overrun-processed HA hydrogel carriers, the therapeutic efficacy of cell/biopolymer constructs was tested using a rabbit model with corneal endothelial dysfunction. Clinical observations including slit-lamp biomicroscopy, specular microscopy, and corneal thickness measurements showed that the construct implants can regenerate corneal endothelium and restore corneal transparency at 4 weeks postoperatively. Our findings suggest that cell sheet transplantation using overrun-processed porous HA hydrogels offers a new way to reconstruct the posterior corneal surface and improve endothelial tissue function. PMID:26296087

Proceedings of the Space Surveillance Workshop (11th) Held at Lexington, Massachusetts on 30 March-1 April 1993. Volume 2

DTIC Science & Technology

1993-04-01

modulation mentioned above is hardly noticeable in the magnitude plots, suggesting it is much weaker than the typical phase function behavior for the...measurements with the overall behavior virtually the same for both. Thus a single representation is sought. Searches for the best analytical representation...nightly phase function behavior , the specular function is found by fitting only the nightly peak count in each case. The specular function is thus

Increased clutter level in echocardiography due to specular reflection

NASA Astrophysics Data System (ADS)

Fatemi, Ali; Torp, Hans; Aakhus, Svend; Rodriguez-Molares, Alfonso

2017-03-01

State-of-the-art echocardiography allows to correctly diagnose most of cardiovascular diseases. An unknown source of clutter, however, hinders the visualization of the heart in some cases. We believe this clutter is caused by the ultrasound beam being partially reflected by the ribs into the elevation direction, so that structures outside the imaging plane are displayed on top of the heart image as clutter noise. We conducted in vitro experiments in a water tank using a synthetic ventricle and pig ribs. By partially blocking the probe with the ribs in the elevation direction, objects outside the imaging plane were rendered in the B-mode image, which confirms that the ribs can behave as specular reflectors. In addition, we succeeded in reproducing clutter noise using a piece of polystyrene to simulate the reflections from the lungs. This indicates that the origin of the clutter noise in echocardiograms can be reverberation coming from the lungs via specular reflection at the ribs.

Broadband diffuse terahertz wave scattering by flexible metasurface with randomized phase distribution

PubMed Central

Zhang, Yin; Liang, Lanju; Yang, Jing; Feng, Yijun; Zhu, Bo; Zhao, Junming; Jiang, Tian; Jin, Biaobing; Liu, Weiwei

2016-01-01

Suppressing specular electromagnetic wave reflection or backward radar cross section is important and of broad interests in practical electromagnetic engineering. Here, we present a scheme to achieve broadband backward scattering reduction through diffuse terahertz wave reflection by a flexible metasurface. The diffuse scattering of terahertz wave is caused by the randomized reflection phase distribution on the metasurface, which consists of meta-particles of differently sized metallic patches arranged on top of a grounded polyimide substrate simply through a certain computer generated pseudorandom sequence. Both numerical simulations and experimental results demonstrate the ultralow specular reflection over a broad frequency band and wide angle of incidence due to the re-distribution of the incident energy into various directions. The diffuse scattering property is also polarization insensitive and can be well preserved when the flexible metasurface is conformably wrapped on a curved reflective object. The proposed design opens up a new route for specular reflection suppression, and may be applicable in stealth and other technology in the terahertz spectrum. PMID:27225031

Broadband diffuse terahertz wave scattering by flexible metasurface with randomized phase distribution.

PubMed

Zhang, Yin; Liang, Lanju; Yang, Jing; Feng, Yijun; Zhu, Bo; Zhao, Junming; Jiang, Tian; Jin, Biaobing; Liu, Weiwei

2016-05-26

Suppressing specular electromagnetic wave reflection or backward radar cross section is important and of broad interests in practical electromagnetic engineering. Here, we present a scheme to achieve broadband backward scattering reduction through diffuse terahertz wave reflection by a flexible metasurface. The diffuse scattering of terahertz wave is caused by the randomized reflection phase distribution on the metasurface, which consists of meta-particles of differently sized metallic patches arranged on top of a grounded polyimide substrate simply through a certain computer generated pseudorandom sequence. Both numerical simulations and experimental results demonstrate the ultralow specular reflection over a broad frequency band and wide angle of incidence due to the re-distribution of the incident energy into various directions. The diffuse scattering property is also polarization insensitive and can be well preserved when the flexible metasurface is conformably wrapped on a curved reflective object. The proposed design opens up a new route for specular reflection suppression, and may be applicable in stealth and other technology in the terahertz spectrum.

Application of Sol-Gel Method as a Protective Layer on a Specular Reflective Surface for Secondary Reflector in a Solar Receiver

DOE Office of Scientific and Technical Information (OSTI.GOV)

Afrin, Samia; Dagdelen, John; Ma, Zhiwen

Highly-specular reflective surfaces that can withstand elevated-temperatures are desirable for many applications including reflective heat shielding in solar receivers and secondary reflectors, which can be used between primary concentrators and heat collectors. A high-efficiency, high-temperature solar receiver design based on arrays of cavities needs a highly-specular reflective surface on its front section to help sunlight penetrate into the absorber tubes for effective flux spreading. Since this application is for high-temperature solar receivers, this surface needs to be durable and to maintain its optical properties through the usable life. Degradation mechanisms associated with elevated temperatures and thermal cycling, which include cracking,more » delamination, corrosion/oxidation, and environmental effects, could cause the optical properties of surfaces to degrade rapidly in these conditions. Protected mirror surfaces for these applications have been tested by depositing a thin layer of SiO2 on top of electrodeposited silver by means of the sol-gel method. To obtain an effective thin film structure, this sol-gel procedure has been investigated extensively by varying process parameters that affect film porosity and thickness. Endurance tests have been performed in a furnace at 150 degrees C for thousands of hours. This paper presents the sol-gel process for intermediate-temperature specular reflective coatings and provides the long-term reliability test results of sol-gel protected silver-coated surfaces.« less

A laser-based eye-tracking system.

PubMed

Irie, Kenji; Wilson, Bruce A; Jones, Richard D; Bones, Philip J; Anderson, Tim J

2002-11-01

This paper reports on the development of a new eye-tracking system for noninvasive recording of eye movements. The eye tracker uses a flying-spot laser to selectively image landmarks on the eye and, subsequently, measure horizontal, vertical, and torsional eye movements. Considerable work was required to overcome the adverse effects of specular reflection of the flying-spot from the surface of the eye onto the sensing elements of the eye tracker. These effects have been largely overcome, and the eye-tracker has been used to document eye movement abnormalities, such as abnormal torsional pulsion of saccades, in the clinical setting.

Reflectance of metallic indium for solar energy applications

NASA Technical Reports Server (NTRS)

Bouquet, F. L.; Hasegawa, T.

1984-01-01

An investigation has been conducted in order to compile quantitative data on the reflective properties of metallic indium. The fabricated samples were of sufficiently high quality that differences from similar second-surface silvered mirrors were not apparent to the human eye. Three second-surface mirror samples were prepared by means of vacuum deposition techniques, yielding indium thicknesses of approximately 1000 A. Both hemispherical and specular measurements were made. It is concluded that metallic indium possesses a sufficiently high specular reflectance to be potentially useful in many solar energy applications.

Air-guided manual deep lamellar keratoplasty.

PubMed

Caporossi, A; Simi, C; Licignano, R; Traversi, C; Balestrazzi, A

2004-01-01

To evaluate the efficacy of a new modified technique of deep lamellar keratoplasty (DLK). Nine eyes of eight patients with keratoconus of moderate degree were included. All patients underwent DLK with manual dissection from a limbal side port after an air bubble injection in the anterior chamber. The patients underwent a complete ophthalmologic examination 6 months after the suture removal, evaluating best-corrected visual acuity, corneal thickness, endothelial cell count, and topographic astigmatism. One case (11.1%) was converted to penetrating keratoplasty because of microperforation. In the eight successful cases, 7 eyes (77.8%) achieved 20/30 or better visual acuity 6 months after suture removal. Mean postoperative pachymetry was 604.76 microm (SD 46.76). Specular microscopy 6 months after suture removal revealed average endothelial cell count of 2273/mm2 (SD 229). This modified DLK technique is a safe and effective procedure and could facilitate, after a short learning curve, this kind of surgery with a low risk of conversion to penetrating keratoplasty.

Influence of nano-oxide layer on the giant magnetoresistance and exchange bias of NiMn/Co/Cu/Co spin valve sensors

NASA Astrophysics Data System (ADS)

Gupta, Anoop; Mohanan, Senthilnathan; Kinyanjui, Michael; Chuvilin, Andrey; Kaiser, Ute; Herr, Ulrich

2010-05-01

NiMn is an interesting material for achieving a high exchange bias in spin valve systems. We investigated the influence of a nano-oxide layer (NOL) inserted in the pinned Co layer on the magnetotransport properties of NiMn/Co/Cu/Co spin valve sensors. The samples were annealed at 350 °C for 10 min to achieve the antiferromagnetic L10 ordered structure of NiMn. The NOL has been characterized by small angle x-ray reflectivity, transmission electron microscopy (TEM), and energy filtered TEM. The inclusion of the NOL leads to an increase in the giant magnetoresistance (GMR) by 20 % indicating a high degree of specular reflection at the NOL. For NOL positions close to the NiMn/Co interface, a decrease in the exchange bias field (Hex) is observed. The best combination of high GMR value and large Hex was found when the NOL was inserted in the center of the pinned Co layer.

Activation of Cytomegalovirus corneal endotheliitis following laser in situ keratomileusis.

PubMed

Tan, Tien-En; Cheung, Chui Ming Gemmy; Mehta, Jodhbir S

2016-11-29

A case of Cytomegalovirus (CMV) corneal endotheliitis following laser in-situ keratomileusis (LASIK) is presented. A 32-year-old man presented 3 weeks after uncomplicated myopic LASIK with unilateral LASIK flap oedema, interface fluid accumulation, keratic precipitates, anterior uveitis and raised intraocular pressure. Despite treatment with topical corticosteroids, he had 3 further recurrent episodes. Specular microscopy showed decreased endothelial cell density and aqueous humour. Polymerase chain reaction (PCR) testing was positive for CMV DNA. He was treated with topical ganciclovir and ketorolac, and the inflammation and oedema resolved. Repeat aqueous humour PCR testing was negative for CMV DNA, and he remained well at last follow-up (3 months after stopping all medications). CMV corneal endotheliitis can be reactivated after LASIK, and CMV DNA PCR of aqueous humour samples can help in definitive diagnosis. Early recognition and treatment of this condition is important to prevent permanent endothelial cell loss and corneal decompensation. 2016 BMJ Publishing Group Ltd.

3D shape reconstruction of specular surfaces by using phase measuring deflectometry

NASA Astrophysics Data System (ADS)

Zhou, Tian; Chen, Kun; Wei, Haoyun; Li, Yan

2016-10-01

The existing estimation methods for recovering height information from surface gradient are mainly divided into Modal and Zonal techniques. Since specular surfaces used in the industry always have complex and large areas, considerations must be given to both the improvement of measurement accuracy and the acceleration of on-line processing speed, which beyond the capacity of existing estimations. Incorporating the Modal and Zonal approaches into a unifying scheme, we introduce an improved 3D shape reconstruction version of specular surfaces based on Phase Measuring Deflectometry in this paper. The Modal estimation is firstly implemented to derive the coarse height information of the measured surface as initial iteration values. Then the real shape can be recovered utilizing a modified Zonal wave-front reconstruction algorithm. By combining the advantages of Modal and Zonal estimations, the proposed method simultaneously achieves consistently high accuracy and dramatically rapid convergence. Moreover, the iterative process based on an advanced successive overrelaxation technique shows a consistent rejection of measurement errors, guaranteeing the stability and robustness in practical applications. Both simulation and experimentally measurement demonstrate the validity and efficiency of the proposed improved method. According to the experimental result, the computation time decreases approximately 74.92% in contrast to the Zonal estimation and the surface error is about 6.68 μm with reconstruction points of 391×529 pixels of an experimentally measured sphere mirror. In general, this method can be conducted with fast convergence speed and high accuracy, providing an efficient, stable and real-time approach for the shape reconstruction of specular surfaces in practical situations.

Estimating the spin axis orientation of the Echostar-2 box-wing geosynchronous satellite

NASA Astrophysics Data System (ADS)

Earl, Michael A.; Somers, Philip W.; Kabin, Konstantin; Bédard, Donald; Wade, Gregg A.

2018-04-01

For the first time, the spin axis orientation of an inactive box-wing geosynchronous satellite has been estimated from ground-based optical photometric observations of Echostar-2's specular reflections. Recent photometric light curves obtained of Echostar-2 over four years suggest that unusually bright and brief specular reflections were occurring twice within an observed spin period. These bright and brief specular reflections suggested two satellite surfaces with surface normals separated by approximately 180°. The geometry between the satellite, the Sun, and the observing location at the time of each of the brightest observed reflections, was used to estimate Echostar-2's equatorial spin axis orientation coordinates. When considering prograde and retrograde rotation, Echostar-2's spin axis orientation was estimated to have been located within 30° of either equatorial coordinate pole. Echostar-2's spin axis was observed to have moved approximately 180° in right ascension, within a time span of six months, suggesting a roughly one year spin axis precession period about the satellite's angular momentum vector.

Specular reflection treatment for the 3D radiative transfer equation solved with the discrete ordinates method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Le Hardy, D.; Favennec, Y., E-mail: yann.favennec@univ-nantes.fr; Rousseau, B.

The contribution of this paper relies in the development of numerical algorithms for the mathematical treatment of specular reflection on borders when dealing with the numerical solution of radiative transfer problems. The radiative transfer equation being integro-differential, the discrete ordinates method allows to write down a set of semi-discrete equations in which weights are to be calculated. The calculation of these weights is well known to be based on either a quadrature or on angular discretization, making the use of such method straightforward for the state equation. Also, the diffuse contribution of reflection on borders is usually well taken intomore » account. However, the calculation of accurate partition ratio coefficients is much more tricky for the specular condition applied on arbitrary geometrical borders. This paper presents algorithms that calculate analytically partition ratio coefficients needed in numerical treatments. The developed algorithms, combined with a decentered finite element scheme, are validated with the help of comparisons with analytical solutions before being applied on complex geometries.« less

Aging and visual 3-D shape recognition from motion.

PubMed

Norman, J Farley; Adkins, Olivia C; Dowell, Catherine J; Hoyng, Stevie C; Shain, Lindsey M; Pedersen, Lauren E; Kinnard, Jonathan D; Higginbotham, Alexia J; Gilliam, Ashley N

2017-11-01

Two experiments were conducted to evaluate the ability of younger and older adults to recognize 3-D object shape from patterns of optical motion. In Experiment 1, participants were required to identify dotted surfaces that rotated in depth (i.e., surface structure portrayed using the kinetic depth effect). The task difficulty was manipulated by limiting the surface point lifetimes within the stimulus apparent motion sequences. In Experiment 2, the participants identified solid, naturally shaped objects (replicas of bell peppers, Capsicum annuum) that were defined by occlusion boundary contours, patterns of specular highlights, or combined optical patterns containing both boundary contours and specular highlights. Significant and adverse effects of increased age were found in both experiments. Despite the fact that previous research has found that increases in age do not reduce solid shape discrimination, our current results indicated that the same conclusion does not hold for shape identification. We demonstrated that aging results in a reduction in the ability to visually recognize 3-D shape independent of how the 3-D structure is defined (motions of isolated points, deformations of smooth optical fields containing specular highlights, etc.).

Temporal correlation measurements of pulsed dual CO2 lidar returns. [for atmospheric pollution detection

NASA Technical Reports Server (NTRS)

Menyuk, N.; Killinger, D. K.

1981-01-01

A pulsed dual-laser direct-detection differential-absorption lidar DIAL system, operating near 10.6 microns, is used to measure the temporal correlation and statistical properties of backscattered returns from specular and diffuse topographic targets. Results show that atmospheric-turbulence fluctuations can effectively be frozen for pulse separation times on the order of 1-3 msec or less. The diffuse target returns, however, yielded a much lower correlation than that obtained with the specular targets; this being due to uncorrelated system noise effects and different statistics for the two types of target returns.

Milne problem for non-absorbing medium with extremely anisotropic scattering kernel in the case of specular and diffuse reflecting boundaries

NASA Astrophysics Data System (ADS)

Güleçyüz, M. Ç.; Şenyiğit, M.; Ersoy, A.

2018-01-01

The Milne problem is studied in one speed neutron transport theory using the linearly anisotropic scattering kernel which combines forward and backward scatterings (extremely anisotropic scattering) for a non-absorbing medium with specular and diffuse reflection boundary conditions. In order to calculate the extrapolated endpoint for the Milne problem, Legendre polynomial approximation (PN method) is applied and numerical results are tabulated for selected cases as a function of different degrees of anisotropic scattering. Finally, some results are discussed and compared with the existing results in literature.

Low Temperature Film Growth of the Oxides of Zinc, Aluminum, and Vanadium (and Related Systems, Oxides of Gold and Germanium, Nitrides of Aluminum and Tungsten) by Reactive Sputter Deposition.

DTIC Science & Technology

1988-02-01

the optical behavior of the material in its preswitched, or A Perkin-Elmer Model 330 UV - Visible -IR double beam ,% spectrophotometer with a specular...S ~ * ." at.* U a * . a. *%~ ~9g 0 ~ --- a.. ’ a * ~ .r~vaa- *a,~ * ~ * ~****.,*a,* *** UV - Visible -IR Optical Behavior of Sputter Deposited Gee x...Films deposited in 0 to 60% Ar were nominally germania. However, transmission in the UV - visible , the strength of the 245nm defect center, the optical

Suits reflectance models for wheat and cotton - Theoretical and experimental tests

NASA Technical Reports Server (NTRS)

Chance, J. E.; Lemaster, E. W.

1977-01-01

Plant canopy reflectance models developed by Suits are tested for cotton and Penjamo winter wheat. Properties of the models are discussed, and the concept of model depth is developed. The models' predicted exchange symmetry for specular irradiance with respect to sun polar angle and observer polar angle agreed with field data for cotton and wheat. Model calculations and experimental data for wheat reflectance vs sun angle disagreed. Specular reflectance from 0.50 to 1.10 micron shows fair agreement between the model and wheat measurements. An Appendix includes the physical and optical parameters for wheat necessary to apply Suits' models.

Corneal endothelial morphology and function after torsional and longitudinal ultrasound mode phacoemulsification

PubMed Central

Módis, László Jr.; Szalai, Eszter; Flaskó, Zsuzsa; Németh, Gábor

2016-01-01

Purpose. To study the endothelial cell morphology and corneal thickness changes after phacoemulsification by using the OZil torsional and longitudinal ultrasound techniques (Infiniti Vision System, Alcon Laboratories). Setting. Department of Ophthalmology, Clinical Center, University of Debrecen, Debrecen, Hungary. Methods. 52 patients with cataract were randomly assigned to longitudinal ultrasound and torsional mode group. All surgeries were performed through a 2.2 mm clear corneal incision, the method employed being divide and conquer. The endothelial morphometry such as cell density (ECD), mean cell area, coefficient of variation of cell area, and central corneal thickness were examined with specular microscopy (EM-1000, Tomey) preoperatively and 4, 8 weeks postoperatively. Results. ECD values decreased significantly in both surgical groups (P < .001, repeated- mesures ANOVA), the postoperative endothelial cell loss was higher in the longitudinal ultrasound mode group (3.5% and 6.5%, at 4 and 8 weeks after surgery) than in the torsional group (3.3% and 5.5%, at 4 and 8 weeks after surgery), the difference not being significant between the two groups (P = .164 and P = .479, at 4 and 8 weeks after surgery, Mann-Whitney test). There was no statistically significant difference in any of the assessed parameters between the two surgical groups (P > .05). No significant correlation was found between the endothelial cell loss and the nucleus density. Conclusions. Both phacoemulsification techniques were safe and effective. The torsional handpiece performs oscillatory movements and delivers less energy into the eye than the longitudinal ultrasound technique, therefore providing more favorable energy and thermal safety profile. PMID:29450332

Comparison of endothelial cell density of organ cultured corneas with cornea donor study.

PubMed

Campolmi, Nelly; He, Zhiguo; Acquart, Sophie; Trone, Marie-Caroline; Bernard, Aurélien; Gauthier, Anne-Sophie; Garraud, Olivier; Forest, Fabien; Péocʼh, Michel; Gain, Philippe; Thuret, Gilles

2014-06-01

Determination of the endothelial cell density (ECD) by eye banks is paramount in donor cornea qualification. Unbiased measurement avoids wastage and grafts with an increased risk of premature failure. Internal calibration of the counting method is essential, but external validation would add an extra stage in the assessment of reliability. In this respect, data published by the multicenter Cornea Donor Study (CDS) in 2005 is a reference. The aim of the study was to compare ECD determined within a single eye bank, which uses calibrated image analysis software designed for transmitted light microscopy images of organ cultured corneas, with the CDS data determined on specular microscopy images of corneas stored at 4°C. ECD of consecutive corneas retrieved between 2005 and 2013 was determined after exposure to 0.9% NaCl. More than 300 ECs were counted on 3 fields of the central 8 mm. Endothelial cell boundaries were automatically drawn and verified by a skilled technician who performed all necessary corrections. Three thousand fifty-two corneas were analyzed, of which 48.5% donors were >75 years (CDS upper age limit). Between 10 and 75 years, the ECD varied according to donor age exactly in the same manner as in the CDS, but were consistently higher of 100 ± 25 cells per square millimeter (P < 0.001). ECD determined by a computer-aided method from transmitted light microscopy images compares favorably with the American CDS reference series. The slight systematic difference on either side of the Atlantic Ocean could be due to (1) differences in counting principles and/or (2) higher shrinkage of the cornea caused by stromal edema in organ culture.

Implementation of cost-effective diffuse light source mechanism to reduce specular reflection and halo effects for resistor-image processing

NASA Astrophysics Data System (ADS)

Chen, Yung-Sheng; Wang, Jeng-Yau

2015-09-01

Light source plays a significant role to acquire a qualified image from objects for facilitating the image processing and pattern recognition. For objects possessing specular surface, the phenomena of reflection and halo appearing in the acquired image will increase the difficulty of information processing. Such a situation may be improved by the assistance of valuable diffuse light source. Consider reading resistor via computer vision, due to the resistor's specular reflective surface it will face with a severe non-uniform luminous intensity on image yielding a higher error rate in recognition without a well-controlled light source. A measurement system including mainly a digital microscope embedded in a replaceable diffuse cover, a ring-type LED embedded onto a small pad carrying a resistor for evaluation, and Arduino microcontrollers connected with PC, is presented in this paper. Several replaceable cost-effective diffuse covers made by paper bowl, cup and box inside pasted with white paper are presented for reducing specular reflection and halo effects and compared with a commercial diffuse some. The ring-type LED can be flexibly configured to be a full or partial lighting based on the application. For each self-made diffuse cover, a set of resistors with 4 or 5 color bands are captured via digital microscope for experiments. The signal-to-noise ratio from the segmented resistor-image is used for performance evaluation. The detected principal axis of resistor body is used for the partial LED configuration to further improve the lighting condition. Experimental results confirm that the proposed mechanism can not only evaluate the cost-effective diffuse light source but also be extended as an automatic recognition system for resistor reading.

Comparative study of radiometric and calorimetric methods for total hemispherical emissivity measurements

NASA Astrophysics Data System (ADS)

Monchau, Jean-Pierre; Hameury, Jacques; Ausset, Patrick; Hay, Bruno; Ibos, Laurent; Candau, Yves

2018-05-01

Accurate knowledge of infrared emissivity is important in applications such as surface temperature measurements by infrared thermography or thermal balance for building walls. A comparison of total hemispherical emissivity measurement was performed by two laboratories: the Laboratoire National de Métrologie et d'Essais (LNE) and the Centre d'Études et de Recherche en Thermique, Environnement et Systèmes (CERTES). Both laboratories performed emissivity measurements on four samples, chosen to cover a large range of emissivity values and angular reflectance behaviors. The samples were polished aluminum (highly specular, low emissivity), bulk PVC (slightly specular, high emissivity), sandblasted aluminum (diffuse surface, medium emissivity), and aluminum paint (slightly specular surface, medium emissivity). Results obtained using five measurement techniques were compared. LNE used a calorimetric method for direct total hemispherical emissivity measurement [1], an absolute reflectometric measurement method [2], and a relative reflectometric measurement method. CERTES used two total hemispherical directional reflectometric measurement methods [3, 4]. For indirect techniques by reflectance measurements, the total hemispherical emissivity values were calculated from directional hemispherical reflectance measurement results using spectral integration when required and directional to hemispherical extrapolation. Results were compared, taking into account measurement uncertainties; an added uncertainty was introduced to account for heterogeneity over the surfaces of the samples and between samples. All techniques gave large relative uncertainties for a low emissive and very specular material (polished aluminum), and results were quite scattered. All the indirect techniques by reflectance measurement gave results within ±0.01 for a high emissivity material. A commercial aluminum paint appears to be a good candidate for producing samples with medium level of emissivity (about 0.4) and with good uniformity of emissivity values (within ±0.015).

In-Plane Correlations in a Polymer-Supported Lipid Membrane Measured by Off-Specular Neutron Scattering

NASA Astrophysics Data System (ADS)

Jablin, Michael S.; Zhernenkov, Mikhail; Toperverg, Boris P.; Dubey, Manish; Smith, Hillary L.; Vidyasagar, Ajay; Toomey, Ryan; Hurd, Alan J.; Majewski, Jaroslaw

2011-04-01

Polymer-supported single lipid bilayers are models to study configurations of cell membranes. We used off-specular neutron scattering to quantify in-plane height-height correlations of interfacial fluctuations of such a lipid bilayer. As temperature decreased from 37°C to 25°C, the polymer swells and the polymer-supported lipid membrane deviates from its initially nearly planar structure. A correlation length characteristic of capillary waves changes from 30μm at 37°C to 11μm at 25°C, while the membrane bending rigidity remains roughly constant in this temperature range.

Crystalisation of aqueous ferrofluids at the free liquid interface investigated by specular and off-specular x-ray reflectometry

NASA Astrophysics Data System (ADS)

Gapon, I. V.; Petrenko, V. I.; Soltwedel, O.; Khaydukov, Yu N.; Kubovcikova, M.; Kopcansky, P.; Bulavin, L. A.; Avdeev, M. V.

2018-03-01

Structural organization of nanoparticles from aqueous ferrofluids on free liquid surface was studied by X-ray reflectometry. The observed layered structure at interface is associated with the evaporation of the solvent. By orienting an external magnetic during evaporation of the aqueos ferrofluids their structural organization can be manipulated. For a magnetic field applied perpendicular to the surface a more pronounced ordering along the surface normal is observed as in the case of a parallel field. Independent on the orientation of the magantic field a ∼ 20 μm thick surface layer of depleted nanoparticle concentration is found at the interface.

Application of Diamond Nanoparticles in Low-Energy Neutron Physics

PubMed Central

Nesvizhevsky, Valery; Cubitt, Robert; Lychagin, Egor; Muzychka, Alexei; Nekhaev, Grigory; Pignol, Guillaume; Protasov, Konstantin; Strelkov, Alexander

2010-01-01

Diamond, with its exceptionally high optical nuclear potential and low absorption cross-section, is a unique material for a series of applications in VCN (very cold neutron) physics and techniques. In particular, powder of diamond nanoparticles provides the best reflector for neutrons in the complete VCN energy range. It allowed also the first observation of quasi-specular reflection of cold neutrons (CN) from disordered medium. Effective critical velocity for such a quasi-specular reflection is higher than that for the best super-mirror. Nano-diamonds survive in high radiation fluxes; therefore they could be used, under certain conditions, in the vicinity of intense neutron sources.

Synthesis of optical polarization signatures of military aircraft

NASA Astrophysics Data System (ADS)

Egan, Walter G.; Duggin, Michael J.

2002-01-01

Focal plane wide band IR imagery will be compared with visual wide band focal plane digital imagery of a camouflaged B-52 bomber. Extreme enhancement is possible using digital polarized imagery. The experimental observations will be compared to theoretical calculations and modeling result of both specular and shadowed areas to allow extrapolations to the synthesis of the optical polarization signatures of other aircraft. The relationship of both the specular and the shadowed areas to surface structure, orientation, specularlity, roughness, shadowing and the complex index of refraction will be illustrated. The imagery was obtained in two plane-polarized directions. Many aircraft locations were measured as well as sky background.

Effective emissivities of isothermal blackbody cavities calculated by the Monte Carlo method using the three-component bidirectional reflectance distribution function model.

PubMed

Prokhorov, Alexander

2012-05-01

This paper proposes a three-component bidirectional reflectance distribution function (3C BRDF) model consisting of diffuse, quasi-specular, and glossy components for calculation of effective emissivities of blackbody cavities and then investigates the properties of the new reflection model. The particle swarm optimization method is applied for fitting a 3C BRDF model to measured BRDFs. The model is incorporated into the Monte Carlo ray-tracing algorithm for isothermal cavities. Finally, the paper compares the results obtained using the 3C model and the conventional specular-diffuse model of reflection.

Analysis of the applicability of the modified kinematic approximation to describe the off-specular neutron scattering from the surface of micro- and nanostructured objects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Belushkin, A. V., E-mail: belushk@nf.jinr.ru; Manoshin, S. A., E-mail: manoshin@nf.jinr.ru; Rikhvitskiy, V. S.

2016-09-15

The applicability of the modified kinematic approximation to describe the off-specular neutron scattering from interfaces between media is analyzed. It is demonstrated that in some cases one can expect not only a qualitative but also a quantitative agreement between the data and the results of experiments and calculations based on more accurate techniques. Diffuse scattering from rough surfaces and thin films with correlated and noncorrelated roughness of the upper and lower interfaces and the neutron diffraction by stripe magnetic domains and magnetic domains with a random size distribution (magnetic roughness) are considered as examples.

Luminance-based specular gloss characterization.

PubMed

Leloup, Frédéric B; Pointer, Michael R; Dutré, Philip; Hanselaer, Peter

2011-06-01

Gloss is a feature of visual appearance that arises from the directionally selective reflection of light incident on a surface. Especially when a distinct reflected image is perceptible, the luminance distribution of the illumination scene above the sample can strongly influence the gloss perception. For this reason, industrial glossmeters do not provide a satisfactory gloss estimation of high-gloss surfaces. In this study, the influence of the conditions of illumination on specular gloss perception was examined through a magnitude estimation experiment in which 10 observers took part. A light booth with two light sources was utilized: the mirror image of only one source being visible in reflection by the observer. The luminance of both the reflected image and the adjacent sample surface could be independently varied by separate adjustment of the intensity of the two light sources. A psychophysical scaling function was derived, relating the visual gloss estimations to the measured luminance of both the reflected image and the off-specular sample background. The generalization error of the model was estimated through a validation experiment performed by 10 other observers. In result, a metric including both surface and illumination properties is provided. Based on this metric, improved gloss evaluation methods and instruments could be developed.

Influence of length and conformation of saccharide head groups on the mechanics of glycolipid membranes: Unraveled by off-specular neutron scattering

NASA Astrophysics Data System (ADS)

Yamamoto, Akihisa; Abuillan, Wasim; Burk, Alexandra S.; Körner, Alexander; Ries, Annika; Werz, Daniel B.; Demé, Bruno; Tanaka, Motomu

2015-04-01

The mechanical properties of multilayer stacks of Gb3 glycolipid that play key roles in metabolic disorders (Fabry disease) were determined quantitatively by using specular and off-specular neutron scattering. Because of the geometry of membrane stacks deposited on planar substrates, the scattered intensity profile was analyzed in a 2D reciprocal space map as a function of in-plane and out-of-plane scattering vector components. The two principal mechanical parameters of the membranes, namely, bending rigidity and compression modulus, can be quantified by full calculation of scattering functions with the aid of an effective cut-off radius that takes the finite sample size into consideration. The bulkier "bent" Gb3 trisaccharide group makes the membrane mechanics distinctly different from cylindrical disaccharide (lactose) head groups and shorter "bent" disaccharide (gentiobiose) head groups. The mechanical characterization of membranes enriched with complex glycolipids has high importance in understanding the mechanisms of diseases such as sphingolipidoses caused by the accumulation of non-degenerated glycosphingolipids in lysosomes or inhibition of protein synthesis triggered by the specific binding of Shiga toxin to Gb3.

Color analysis and image rendering of woodblock prints with oil-based ink

NASA Astrophysics Data System (ADS)

Horiuchi, Takahiko; Tanimoto, Tetsushi; Tominaga, Shoji

2012-01-01

This paper proposes a method for analyzing the color characteristics of woodblock prints having oil-based ink and rendering realistic images based on camera data. The analysis results of woodblock prints show some characteristic features in comparison with oil paintings: 1) A woodblock print can be divided into several cluster areas, each with similar surface spectral reflectance; and 2) strong specular reflection from the influence of overlapping paints arises only in specific cluster areas. By considering these properties, we develop an effective rendering algorithm by modifying our previous algorithm for oil paintings. A set of surface spectral reflectances of a woodblock print is represented by using only a small number of average surface spectral reflectances and the registered scaling coefficients, whereas the previous algorithm for oil paintings required surface spectral reflectances of high dimension at all pixels. In the rendering process, in order to reproduce the strong specular reflection in specific cluster areas, we use two sets of parameters in the Torrance-Sparrow model for cluster areas with or without strong specular reflection. An experiment on a woodblock printing with oil-based ink was performed to demonstrate the feasibility of the proposed method.

Shearography for Non-destructive Inspection with applications to BAT Mask Tile Adhesive Bonding and Specular Surface Honeycomb Panels

NASA Technical Reports Server (NTRS)

Lysak, Daniel B.

2003-01-01

The applicability of shearography techniques for non-destructive evaluation in two unique application areas is examined. In the first application, shearography is used to evaluate the quality of adhesive bonds holding lead tiles to the B.4T gamma ray mask for the NASA Swift program. Using a vibration excitation, the more poorly bonded tiles are readily identifiable in the shearography image. A quantitative analysis is presented that compares the shearography results with a destructive pull test measuring the force at bond failure. The second application is to evaluate the bonding between the skin and core of a honeycomb structure with a specular (mirror-like) surface. In standard shearography techniques, the object under test must have a diffuse surface to generate the speckle patterns in laser light, which are then sheared. A novel configuration using the specular surface as a mirror to image speckles from a diffuser is presented, opening up the use of shearography to a new class of objects that could not have been examined with the traditional approach. This new technique readily identifies large scale bond failures in the panel, demonstrating the validity of this approach.

The New Horizons Bistatic Radio Science Experiment to Measure Pluto's Surface Properties

NASA Astrophysics Data System (ADS)

Linscott, I.; Hinson, D. P.; Tyler, G. L.; Vincent, M.

2014-12-01

The New Horizons (NH) payload includes a Radio Science Experiment (REX) for principally occultation and radiometric measurement of Pluto and Charon during the flyby in July 2015. The REX subsystem is contained, together with the NH X-Band radio, in the Integrated Electronics Module (IEM) in the New Horizons spacecraft. REX samples and records in two polarizations both total RF power in a 4.5 MHz bandwidth, and radio signal waveforms in a narrow, 1.25 kHz band. During the encounter, and at closest approach to Pluto, the spacecraft's high gain antenna (HGA) will scan Pluto's equatorial latitudes, intercepting the specular zone, a region near Pluto's limb that geometrically favors reflection from the earth's direction. At the same time, a powerful 80 kW uplink beacon will have been transmitted from earth by the DSN to arrive at Pluto during spacecraft closest approach. Reflection from the specular zone is expected to be sufficiently strong to observe the bistatic uplink in the REX narrowband record. Measurements in both polarizations will then be combined to yield surface reflectivity, roughness and limits on the dielectric constant in the specular zone.

In-Situ Observation of Nano-Oxide Formation in Magnetic Thin Films

NASA Astrophysics Data System (ADS)

McCallum, Andrew; Russek, Stephen

2004-03-01

Exposure of a metal surface in a spin valve structure to oxygen creates a nano-oxide layer, or NOL, on that surface. Inclusion of NOLs into spin valve structures has been shown by many researchers to lower the resistance and increase the giant magnetoresistance effect. Four point in-situ conductance measurements were made during the deposition and oxidation of Co layers. These measurements show an initial decrease in conductance followed by an increase in conductance, due to a specularity increase of at least 0.10. RHEED measurements taken simultaneously with conductance measurements show the formation an amorphous oxide while the specularity increases. With further exposure of oxygen to the surface a CoO structure with a (111) texture forms. Magnetoconductance measurements during the oxidation of the free layer of bottom pinned spin valves show increases in the GMR of the spin valves. Estimates of the change in specularity and Co layer thickness were determined from the change in conductance and the change in magnetoconductance. Also determined from the magnetoconductance measurements was an increase in the coercivity of the free layer with oxidation. Adding Co onto the oxide had a strong effect on the coercivity and coupling between free and pinned layers.

Ultra-wideband, Wide Angle and Polarization-insensitive Specular Reflection Reduction by Metasurface based on Parameter-adjustable Meta-Atoms

PubMed Central

Su, Jianxun; Lu, Yao; Zhang, Hui; Li, Zengrui; (Lamar) Yang, Yaoqing; Che, Yongxing; Qi, Kainan

2017-01-01

In this paper, an ultra-wideband, wide angle and polarization-insensitive metasurface is designed, fabricated, and characterized for suppressing the specular electromagnetic wave reflection or backward radar cross section (RCS). Square ring structure is chosen as the basic meta-atoms. A new physical mechanism based on size adjustment of the basic meta-atoms is proposed for ultra-wideband manipulation of electromagnetic (EM) waves. Based on hybrid array pattern synthesis (APS) and particle swarm optimization (PSO) algorithm, the selection and distribution of the basic meta-atoms are optimized simultaneously to obtain the ultra-wideband diffusion scattering patterns. The metasurface can achieve an excellent RCS reduction in an ultra-wide frequency range under x- and y-polarized normal incidences. The new proposed mechanism greatly extends the bandwidth of RCS reduction. The simulation and experiment results show the metasurface can achieve ultra-wideband and polarization-insensitive specular reflection reduction for both normal and wide-angle incidences. The proposed methodology opens up a new route for realizing ultra-wideband diffusion scattering of EM wave, which is important for stealth and other microwave applications in the future. PMID:28181593

Ultra-wideband, Wide Angle and Polarization-insensitive Specular Reflection Reduction by Metasurface based on Parameter-adjustable Meta-Atoms.

PubMed

Su, Jianxun; Lu, Yao; Zhang, Hui; Li, Zengrui; Lamar Yang, Yaoqing; Che, Yongxing; Qi, Kainan

2017-02-09

In this paper, an ultra-wideband, wide angle and polarization-insensitive metasurface is designed, fabricated, and characterized for suppressing the specular electromagnetic wave reflection or backward radar cross section (RCS). Square ring structure is chosen as the basic meta-atoms. A new physical mechanism based on size adjustment of the basic meta-atoms is proposed for ultra-wideband manipulation of electromagnetic (EM) waves. Based on hybrid array pattern synthesis (APS) and particle swarm optimization (PSO) algorithm, the selection and distribution of the basic meta-atoms are optimized simultaneously to obtain the ultra-wideband diffusion scattering patterns. The metasurface can achieve an excellent RCS reduction in an ultra-wide frequency range under x- and y-polarized normal incidences. The new proposed mechanism greatly extends the bandwidth of RCS reduction. The simulation and experiment results show the metasurface can achieve ultra-wideband and polarization-insensitive specular reflection reduction for both normal and wide-angle incidences. The proposed methodology opens up a new route for realizing ultra-wideband diffusion scattering of EM wave, which is important for stealth and other microwave applications in the future.

Knudsen pump inspired by Crookes radiometer with a specular wall

NASA Astrophysics Data System (ADS)

Baier, Tobias; Hardt, Steffen; Shahabi, Vahid; Roohi, Ehsan

2017-03-01

A rarefied gas is considered in a channel consisting of two infinite parallel plates between which an evenly spaced array of smaller plates is arranged normal to the channel direction. Each of these smaller plates is assumed to possess one ideally specularly reflective and one ideally diffusively reflective side. When the temperature of the small plates differs from the temperature of the sidewalls of the channel, these boundary conditions result in a temperature profile around the edges of each small plate that breaks the reflection symmetry along the channel direction. This in turn results in a force on each plate and a net gas flow along the channel. The situation is analyzed numerically using the direct simulation Monte Carlo method and compared with analytical results where available. The influence of the ideally specularly reflective wall is assessed by comparing with simulations using a finite accommodation coefficient at the corresponding wall. The configuration bears some similarity to a Crookes radiometer, where a nonsymmetric temperature profile at the radiometer vanes is generated by different temperatures on each side of the vane, resulting in a motion of the rotor. The described principle may find applications in pumping gas on small scales driven by temperature gradients.

Choice of crystal surface finishing for a dual-ended readout depth-of-interaction (DOI) detector.

PubMed

Fan, Peng; Ma, Tianyu; Wei, Qingyang; Yao, Rutao; Liu, Yaqiang; Wang, Shi

2016-02-07

The objective of this study was to choose the crystal surface finishing for a dual-ended readout (DER) DOI detector. Through Monte Carlo simulations and experimental studies, we evaluated 4 crystal surface finishing options as combinations of crystal surface polishing (diffuse or specular) and reflector (diffuse or specular) options on a DER detector. We also tested one linear and one logarithm DOI calculation algorithm. The figures of merit used were DOI resolution, DOI positioning error, and energy resolution. Both the simulation and experimental results show that (1) choosing a diffuse type in either surface polishing or reflector would improve DOI resolution but degrade energy resolution; (2) crystal surface finishing with a diffuse polishing combined with a specular reflector appears a favorable candidate with a good balance of DOI and energy resolution; and (3) the linear and logarithm DOI calculation algorithms show overall comparable DOI error, and the linear algorithm was better for photon interactions near the ends of the crystal while the logarithm algorithm was better near the center. These results provide useful guidance in DER DOI detector design in choosing the crystal surface finishing and DOI calculation methods.

Influence of length and conformation of saccharide head groups on the mechanics of glycolipid membranes: Unraveled by off-specular neutron scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamamoto, Akihisa, E-mail: ayamamoto@icems.kyoto-u.ac.jp, E-mail: tanaka@uni-heidelberg.de; Tanaka, Motomu, E-mail: ayamamoto@icems.kyoto-u.ac.jp, E-mail: tanaka@uni-heidelberg.de; Institute for Integrated Cell-Material Sciences

2015-04-21

The mechanical properties of multilayer stacks of Gb3 glycolipid that play key roles in metabolic disorders (Fabry disease) were determined quantitatively by using specular and off-specular neutron scattering. Because of the geometry of membrane stacks deposited on planar substrates, the scattered intensity profile was analyzed in a 2D reciprocal space map as a function of in-plane and out-of-plane scattering vector components. The two principal mechanical parameters of the membranes, namely, bending rigidity and compression modulus, can be quantified by full calculation of scattering functions with the aid of an effective cut-off radius that takes the finite sample size into consideration.more » The bulkier “bent” Gb3 trisaccharide group makes the membrane mechanics distinctly different from cylindrical disaccharide (lactose) head groups and shorter “bent” disaccharide (gentiobiose) head groups. The mechanical characterization of membranes enriched with complex glycolipids has high importance in understanding the mechanisms of diseases such as sphingolipidoses caused by the accumulation of non-degenerated glycosphingolipids in lysosomes or inhibition of protein synthesis triggered by the specific binding of Shiga toxin to Gb3.« less

A fast method for optical simulation of flood maps of light-sharing detector modules.

PubMed

Shi, Han; Du, Dong; Xu, JianFeng; Moses, William W; Peng, Qiyu

2015-12-01

Optical simulation of the detector module level is highly desired for Position Emission Tomography (PET) system design. Commonly used simulation toolkits such as GATE are not efficient in the optical simulation of detector modules with complicated light-sharing configurations, where a vast amount of photons need to be tracked. We present a fast approach based on a simplified specular reflectance model and a structured light-tracking algorithm to speed up the photon tracking in detector modules constructed with polished finish and specular reflector materials. We simulated conventional block detector designs with different slotted light guide patterns using the new approach and compared the outcomes with those from GATE simulations. While the two approaches generated comparable flood maps, the new approach was more than 200-600 times faster. The new approach has also been validated by constructing a prototype detector and comparing the simulated flood map with the experimental flood map. The experimental flood map has nearly uniformly distributed spots similar to those in the simulated flood map. In conclusion, the new approach provides a fast and reliable simulation tool for assisting in the development of light-sharing-based detector modules with a polished surface finish and using specular reflector materials.

Analysis of Specular Reflections Off Geostationary Satellites

NASA Astrophysics Data System (ADS)

Jolley, A.

2016-09-01

Many photometric studies of artificial satellites have attempted to define procedures that minimise the size of datasets required to infer information about satellites. However, it is unclear whether deliberately limiting the size of datasets significantly reduces the potential for information to be derived from them. In 2013 an experiment was conducted using a 14 inch Celestron CG-14 telescope to gain multiple night-long, high temporal resolution datasets of six geostationary satellites [1]. This experiment produced evidence of complex variations in the spectral energy distribution (SED) of reflections off satellite surface materials, particularly during specular reflections. Importantly, specific features relating to the SED variations could only be detected with high temporal resolution data. An update is provided regarding the nature of SED and colour variations during specular reflections, including how some of the variables involved contribute to these variations. Results show that care must be taken when comparing observed spectra to a spectral library for the purpose of material identification; a spectral library that uses wavelength as the only variable will be unable to capture changes that occur to a material's reflected spectra with changing illumination and observation geometry. Conversely, colour variations with changing illumination and observation geometry might provide an alternative means of determining material types.

[Evaluation of corneal tissue by slit lamp and specular microscopy during the preservation period].

PubMed

Farias, Roberta Jansen de Mello; Kubokawa, Karen Miyuki; Schirmer, Maurício; Sousa, Luciene Barbosa de

2007-01-01

To analyze changes evaluation of corneal grafts by slit lamp and electron microscopy examination in order to ensure a donor cornea of good quality level for the patient. 203 corneas donated to the Sorocaba Eye Bank between September 2002 and February 2003 were prospectively evaluated. The evaluation was graded from 0 to 3 according to the following factors: exposure and epithelial damage, stromal opacity, Descemet folds, pleomorphism, polymegatism and guttata, endothelial snail track, edema, reflectivity. The data were correlated with time between death and preservation, endothelial cell count and donor's age. 203 corneas were evaluated. The mean age of donors was 55 years (dp= 14.8 years). The mean time between death and preservation was 9.1 h (minimum of 2 h and maximum of 25 h). Eighty-six corneas suffered worsening of evaluation, whereby 66.3% had less than 2,500 endothelial cell count and 59.3% presented time between death and preservation over 6 hours. The mean day of the grading change was the 5th. Corneal grafts from younger donors had significantly better evaluation than those of older donors. The mean time of the evaluation change was on the 5th day in 50% of the corneas, however, an expressive number of corneas suffered changes on the 6th, 7th and 8th day. Corneal graft preserved after 6 hours of death had a greater tendency to lower cell count and to decrease in evaluation grades.

Mechanical characterization at material interfaces through dark field Brillouin microscopy (Conference Presentation)

NASA Astrophysics Data System (ADS)

Fiore, Antonio; Scarcelli, Giuliano

2017-02-01

Brillouin microscopy allows high-resolution mapping of the mechanical properties of a sample by measuring the spectra of acoustically induced light scattering therein, and thus has been widely investigated for biomedical application. Measuring the Brillouin spectral shift is challenging when the light is focused onto the interfaces between two materials of different refractive index, because a sizeable portion of the incident light is Fresnel-reflected into the Brillouin spectrometer. To address this need, here, we designed a Brillouin confocal microscope in which the specular reflection at the interface between two materials is physically rejected without significant loss to the Brillouin signal. To achieve this goal, we illuminate the sample with a small-diameter Gaussian beam focused by a high numerical aperture objective lens. In the collection path, the beam reflected from the sample has the same diameter as the incident beam, while the scattered light beam is as large as the clear aperture of the microscope objective. Therefore, using a small blocking filter allows to efficiently reject the reflected light. We calculated the tradeoff between extinction improvement and signal loss when the diameter of the blocking filter is changed. Experimentally, we demonstrated extinction improvement of over 60dB with only 30% signal loss while achieving submicron resolutions. This innovation can be useful for in vivo measurements of the cornea to avoid artifacts in the epithelium and anterior portions of the stroma, as well as to investigate cells cultured on glass coverslips without necessity of index-matching materials.

Estimation of gloss from rough surface parameters

NASA Astrophysics Data System (ADS)

Simonsen, Ingve; Larsen, Åge G.; Andreassen, Erik; Ommundsen, Espen; Nord-Varhaug, Katrin

2005-12-01

Gloss is a quantity used in the optical industry to quantify and categorize materials according to how well they scatter light specularly. With the aid of phase perturbation theory, we derive an approximate expression for this quantity for a one-dimensional randomly rough surface. It is demonstrated that gloss depends in an exponential way on two dimensionless quantities that are associated with the surface randomness: the root-mean-square roughness times the perpendicular momentum transfer for the specular direction, and a correlation function dependent factor times a lateral momentum variable associated with the collection angle. Rigorous Monte Carlo simulations are used to access the quality of this approximation, and good agreement is observed over large regions of parameter space.

NOL specular spin-valve heads using an ultrathin CoFe free layer

NASA Astrophysics Data System (ADS)

Fukuzawa, Hideaki; Koi, Katsuhiko; Tomita, Hiroshi; Fuke, Hiromi Niu; Kamiguchi, Yuzo; Iwasaki, Hitoshi; Sahashi, Masashi

2001-10-01

This paper reports the film and head performance of specular spin valves with nano-oxide layer (NOL-SPSV). A large MR ratio of 17% was obtained by using an ultrathin CoFe free layer with a high conductance Cu layer, which decreases the sense current field of a free layer and brings good soft magnetic characteristics. Prototype heads with a read track width of 0.47-0.61 μm were fabricated by using NOL-SPSV films with an MR ratio of 14-15%, Hua˜400 Oe, and Hc˜5 Oe. High output signal voltage of 8-11 mV/μm was realized in the NOL-SPSV heads.

A comparison of radiosity with current methods of sound level prediction in commercial spaces

NASA Astrophysics Data System (ADS)

Beamer, C. Walter, IV; Muehleisen, Ralph T.

2002-11-01

The ray tracing and image methods (and variations thereof) are widely used for the computation of sound fields in architectural spaces. The ray tracing and image methods are best suited for spaces with mostly specular reflecting surfaces. The radiosity method, a method based on solving a system of energy balance equations, is best applied to spaces with mainly diffusely reflective surfaces. Because very few spaces are either purely specular or purely diffuse, all methods must deal with both types of reflecting surfaces. A comparison of the radiosity method to other methods for the prediction of sound levels in commercial environments is presented. [Work supported by NSF.

Polarized BRDF for coatings based on three-component assumption

NASA Astrophysics Data System (ADS)

Liu, Hong; Zhu, Jingping; Wang, Kai; Xu, Rong

2017-02-01

A pBRDF(polarized bidirectional reflection distribution function) model for coatings is given based on three-component reflection assumption in order to improve the polarized scattering simulation capability for space objects. In this model, the specular reflection is given based on microfacet theory, the multiple reflection and volume scattering are given separately according to experimental results. The polarization of specular reflection is considered from Fresnel's law, and both multiple reflection and volume scattering are assumed depolarized. Simulation and measurement results of two satellite coating samples SR107 and S781 are given to validate that the pBRDF modeling accuracy can be significantly improved by the three-component model given in this paper.

Model of bidirectional reflectance distribution function for metallic materials

NASA Astrophysics Data System (ADS)

Wang, Kai; Zhu, Jing-Ping; Liu, Hong; Hou, Xun

2016-09-01

Based on the three-component assumption that the reflection is divided into specular reflection, directional diffuse reflection, and ideal diffuse reflection, a bidirectional reflectance distribution function (BRDF) model of metallic materials is presented. Compared with the two-component assumption that the reflection is composed of specular reflection and diffuse reflection, the three-component assumption divides the diffuse reflection into directional diffuse and ideal diffuse reflection. This model effectively resolves the problem that constant diffuse reflection leads to considerable error for metallic materials. Simulation and measurement results validate that this three-component BRDF model can improve the modeling accuracy significantly and describe the reflection properties in the hemisphere space precisely for the metallic materials.

Simulation of the dynamical transmission of several-hundred-keV protons through a conical capillary

NASA Astrophysics Data System (ADS)

Yang, A. X.; Zhu, B. H.; Niu, S. T.; Pan, P.; Han, C. Z.; Song, H. Y.; Shao, J. X.; Chen, X. M.

2018-05-01

The time evolution of the trajectories, angular distributions, and two-dimensional images of intermediate-energy protons being transmitted through a conical capillary was simulated. The simulation results indicate that the charge deposited in the capillary significantly enhances the probability of surface specular scattering and thus greatly enhances the transmission rate. Furthermore, this deposited-charge-assisted specular reflection causes the transmission rate to exhibit an energy dependence proportional to E-1, which is very consistent with the experimental data. After transmission at nonzero tilt angles, the angular distribution of several-hundred-keV protons is far from symmetric, unlike in the case of keV protons.

Prototyping hexagonal light concentrators using high-reflectance specular films for the Large-Sized Telescopes of the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Okumura, A.; Dang, T. V.; Ono, S.; Tanaka, S.; Hayashida, M.; Hinton, J.; Katagiri, H.; Noda, K.; Teshima, M.; Yamamoto, T.; Yoshida, T.

2017-12-01

We have developed a prototype hexagonal light concentrator for the Large-Sized Telescopes of the Cherenkov Telescope Array. To maximize the photodetection efficiency of the focal-plane camera pixels for atmospheric Cherenkov photons and to lower the energy threshold, a specular film with a very high reflectance of 92-99% has been developed to cover the inner surfaces of the light concentrators. The prototype has a relative anode sensitivity (which can be roughly regarded as collection efficiency) of about 95 to 105% at the most important angles of incidence. The design, simulation, production procedure, and performance measurements of the light-concentrator prototype are reported.

Far-infrared /FIR/ optical black bidirectional reflectance distribution function /BRDF/

NASA Technical Reports Server (NTRS)

Smith, S. M.

1981-01-01

A nonspecular reflectometer and its operation at far-infrared wavelengths are described. Large differences in nonspecular reflectance were found to exist between different optically black coatings. Normal incidence bidirectional reflectance distribution function /BRDF) measurements at wavelengths between 12 and 316 microns of three black coatings show that their mean BRDFs increase with wavelength. The specularity of two of these coatings also showed a strong wavelength dependence, while the specularity of one coating seemed independent of wavelength. The BRDF of one coating depended on the angle of incidence at 12 and 38 microns, but not at 316 microns. Beyond 200 microns, it was found necessary to correct the measurements for the beam spread of the instrument.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pirozhkov, A. S.; Mori, M.; Yogo, A.

High-power laser contrast is challenging to measure, especially in the real target irradiation conditions. We present a convenient and relatively simple contrast diagnostic technique based on the measurement of target specular reflectivity at full laser power. The reflectivity remains high even at intensities above 10{sup 19} W/cm{sup 2} in the case of a high-contrast prepulse-free laser. On the contrary, the specular reflectivity drops in the case of lower contrast, due to the beam break-up and increased absorption caused by the preformed plasma. The technique was demonstrated using three different laser systems with several contrast conditions: Astra (CLF, RAL), TiS lasermore » at APRI, GIST, and J-KAREN (APRC, JAEA).« less

Rapid testing for malaria in settings where microscopy is available and peripheral clinics where only presumptive treatment is available: a randomised controlled trial in Ghana.

PubMed

Ansah, Evelyn K; Narh-Bana, Solomon; Epokor, Michael; Akanpigbiam, Samson; Quartey, Alberta Amu; Gyapong, John; Whitty, Christopher J M

2010-03-05

To test in West Africa the impact of rapid diagnostic tests on the prescription of antimalarials and antibiotics both where microscopy is used for the diagnosis of malaria and in clinical (peripheral) settings that rely on clinical diagnosis. Randomised, controlled, open label clinical trial. Four clinics in the rural Dangme West district of southern Ghana, one in which microscopy is used for diagnosis of malaria ("microscopy setting") and three where microscopy is not available and diagnosis of malaria is made on the basis of clinical symptoms ("clinical setting"). Patients with suspected malaria. Interventions Patients were randomly assigned to either a rapid diagnostic test or the current diagnostic method at the clinic (microscopy or clinical diagnosis). A blood sample for a research microscopy slide was taken for all patients. The primary outcome was the prescription of antimalarials to patients of any age whose double read research slide was negative for malaria. The major secondary outcomes were the correct prescription of antimalarials, the impact of test results on antibiotic prescription, and the correct prescription of antimalarials in children under 5 years. Of the 9236 patients screened, 3452 were randomised in the clinical setting and 3811 in the microscopy setting. Follow-up to 28 days was 97.6% (7088/7263). In the microscopy setting, 722 (51.6%) of the 1400 patients with negative research slides in the rapid diagnostic test arm were treated for malaria compared with 764 (55.0%) of the 1389 patients in the microscopy arm (adjusted odds ratio 0.87, 95% CI 0.71 to 1.1; P=0.16). In the clinical setting, 578 (53.9%) of the 1072 patients in the rapid diagnostic test arm with negative research slides were treated for malaria compared with 982 (90.1%) of the 1090 patients with negative slides in the clinical diagnosis arm (odds ratio 0.12, 95% CI 0.04 to 0.38; P=0.001). The use of rapid diagnostic tests led to better targeting of antimalarials and antibiotics in the clinical but not the microscopy setting, in both children and adults. There were no deaths in children under 5 years at 28 days follow-up in either arm. Where microscopy already exists, introducing rapid diagnostic tests had limited impact on prescriber behaviour. In settings where microscopy was not available, however, using rapid diagnostic tests led to a significant reduction in the overprescription of antimalarials, without any evidence of clinical harm, and to better targeting of antibiotics. Trial registration ClinicalTrials.gov NCT00493922.

Organic-vapor detection using carbon-nanotubes nanocomposite microacoustic sensors

NASA Astrophysics Data System (ADS)

Penza, M.; Tagliente, M. A.; Aversa, P.; Cassano, G.

2005-06-01

We have developed highly sensitive microacoustic vapor sensors based on surface acoustic waves (SAWs) ST,X quartz 315 and 433 MHz two-port resonator oscillators. A nanocomposite film of single-walled carbon nanotubes (SWCNTs) embedded in a cadmium arachidate (CdA) amphiphilic matrix was prepared by Langmuir-Blodgett technique with a fixed SWCNTs weight filler-content as nanostructured and nanosensing interface, for vapor detection at room temperature. The structural properties and surface morphology of the nanocomposite have been examined by X-ray Specular Reflectivity and Field-Emission Gun Scanning Electron Microscopy, respectively. The measured acoustic sensing characteristics indicate that the SAW sensitivity to polar and nonpolar tested organic molecules (ethanol, ethylacetate, and toluene) of the SWCNTs/CdA nanocomposite is up to two times higher than that of unembedded CdA device; also the SWCNTs/CdA nanocomposite vapor sensitivity results significantly enhanced with respect to traditional organic molecular cavities materials and increases with SAW oscillating frequency with a linear dependence in the frequency change response up to a very low sub-ppm limit of detection.

Nanostructuring-induced modification of optical properties of p-GaAs (1 0 0)

NASA Astrophysics Data System (ADS)

Naddaf, M.; Saloum, S.

2009-10-01

A pulsed anodic etching method has been utilized for nanostructuring of p-type GaAs (1 0 0) surface, using HCl-based solution as electrolyte. The resulting porous GaAs layer is characterized by atomic force microscopy (AFM), room temperature photoluminescence (PL), Raman spectroscopy and optical reflectance measurements. AFM imaging reveals that the porous GaAs layer is consisted of a pillar-like of few nm in width distributed between more-reduced size nanostructures. In addition to the “infrared” PL band of un-etched GaAs, a strong “green” PL band is observed in the etched sample. The broad visible PL band of a high-energy (3.82 eV) excitation is found to compose of two PL band attributed to excitons confinement in two different sizes distribution of GaAs nanocrystals. The quantum confinement effects in GaAs nanocrystallites is also evidenced from Raman spectroscopy through the pronounced appearance of the transverse optical (TO) phonon line in the spectra of the porous sample. Porosity-induced a significant reduction of the specular reflection, in the spectral range (400-800 nm), is also demonstrated.

Plasmonic resonances in hybrid systems of aluminum nanostructured arrays and few layer graphene within the UV-IR spectral range

NASA Astrophysics Data System (ADS)

González-Campuzano, R.; Saniger, J. M.; Mendoza, D.

2017-11-01

The size-controllable and ordered Al nanocavities and nanodomes arrays were synthesized by electrochemical anodization of aluminum using phosphoric acid, citric acid and mixture both acids. Few layer graphene (FLG) was transferred directly on top of Al nanostructures and their morphology were evaluated by scanning electron microscopy. The interaction between FLG and the plasmonic properties of Al nanostructures arrays were investigated based on specular reflectivity in the ultraviolet-visible-infrared range and Raman spectroscopy. We found that their optical reflectivity was dramatically reduced as compared with unstructured Al. At the same time pronounced reflectivity dips were detectable in the 200-896 nm wavelength range, which were ascribed to plasmonic resonances. The plasmonic properties of these nanostructures do not exhibit evident changes by the presence of FLG in the UV-vis range of the electromagnetic spectrum. By contrast, the surface-enhanced Raman spectroscopy of FLG was observed in nanocavities and nanodomes structures that result in an intensity increase of the characteristic G and 2D bands of FLG induced by the plasmonic properties of Al nanostructures.

Effect of surface modification on protein retention and cell proliferation under strain.

PubMed

Dunkers, J P; Lee, H-J; Matos, M A; Pakstis, L M; Taboas, J M; Hudson, S D; Cicerone, M T

2011-07-01

When culturing cells on flexible surfaces, it is important to consider extracellular matrix treatments that will remain on the surface under mechanical strain. Here we investigate differences in laminin deposited on oxidized polydimethylsiloxane (PDMS) with plasma treatment (plasma-only) vs. plasma and aminopropyltrimethoxysilane treatment (silane-linked). We use specular X-ray reflectivity (SXR), transmission electron microscopy (TEM), and immunofluorescence to probe the quantity and uniformity of laminin. The surface coverage of laminin is approximately 45% for the plasma-only and 50% for the silane-linked treatment as determined by SXR. TEM and immunofluorescence reveal additional islands of laminin aggregates on the plasma-only PDMS compared with the relatively smooth and uniform silane-linked laminin surface. We also examine laminin retention under strain and vascular smooth muscle cell viability and proliferation under static and strain conditions. Equibiaxial stretching of the PDMS surfaces shows greatly improved retention of the silane-linked laminin over plasma-only. There are significantly more cells on the silane-linked surface after 4 days of equibiaxial strain. Published by Elsevier Ltd.

A fast method for optical simulation of flood maps of light-sharing detector modules

PubMed Central

Shi, Han; Du, Dong; Xu, JianFeng; Moses, William W.; Peng, Qiyu

2016-01-01

Optical simulation of the detector module level is highly desired for Position Emission Tomography (PET) system design. Commonly used simulation toolkits such as GATE are not efficient in the optical simulation of detector modules with complicated light-sharing configurations, where a vast amount of photons need to be tracked. We present a fast approach based on a simplified specular reflectance model and a structured light-tracking algorithm to speed up the photon tracking in detector modules constructed with polished finish and specular reflector materials. We simulated conventional block detector designs with different slotted light guide patterns using the new approach and compared the outcomes with those from GATE simulations. While the two approaches generated comparable flood maps, the new approach was more than 200–600 times faster. The new approach has also been validated by constructing a prototype detector and comparing the simulated flood map with the experimental flood map. The experimental flood map has nearly uniformly distributed spots similar to those in the simulated flood map. In conclusion, the new approach provides a fast and reliable simulation tool for assisting in the development of light-sharing-based detector modules with a polished surface finish and using specular reflector materials. PMID:27660376

Angular and Seasonal Variation of Spectral Surface Reflectance Ratios: Implications for the Remote Sensing of Aerosol over Land

NASA Technical Reports Server (NTRS)

Remer, L. A.; Wald, A. E.; Kaufman, Y. J.

1999-01-01

We obtain valuable information on the angular and seasonal variability of surface reflectance using a hand-held spectrometer from a light aircraft. The data is used to test a procedure that allows us to estimate visible surface reflectance from the longer wavelength 2.1 micrometer channel (mid-IR). Estimating or avoiding surface reflectance in the visible is a vital first step in most algorithms that retrieve aerosol optical thickness over land targets. The data indicate that specular reflection found when viewing targets from the forward direction can severely corrupt the relationships between the visible and 2.1 micrometer reflectance that were derived from nadir data. There is a month by month variation in the ratios between the visible and the mid-IR, weakly correlated to the Normalized Difference Vegetation Index (NDVI). If specular reflection is not avoided, the errors resulting from estimating surface reflectance from the mid-IR exceed the acceptable limit of DELTA-rho approximately 0.01 in roughly 40% of the cases, using the current algorithm. This is reduced to 25% of the cases if specular reflection is avoided. An alternative method that uses path radiance rather than explicitly estimating visible surface reflectance results in similar errors. The two methods have different strengths and weaknesses that require further study.

A Precise Visual Method for Narrow Butt Detection in Specular Reflection Workpiece Welding

PubMed Central

Zeng, Jinle; Chang, Baohua; Du, Dong; Hong, Yuxiang; Chang, Shuhe; Zou, Yirong

2016-01-01

During the complex path workpiece welding, it is important to keep the welding torch aligned with the groove center using a visual seam detection method, so that the deviation between the torch and the groove can be corrected automatically. However, when detecting the narrow butt of a specular reflection workpiece, the existing methods may fail because of the extremely small groove width and the poor imaging quality. This paper proposes a novel detection method to solve these issues. We design a uniform surface light source to get high signal-to-noise ratio images against the specular reflection effect, and a double-line laser light source is used to obtain the workpiece surface equation relative to the torch. Two light sources are switched on alternately and the camera is synchronized to capture images when each light is on; then the position and pose between the torch and the groove can be obtained nearly at the same time. Experimental results show that our method can detect the groove effectively and efficiently during the welding process. The image resolution is 12.5 μm and the processing time is less than 10 ms per frame. This indicates our method can be applied to real-time narrow butt detection during high-speed welding process. PMID:27649173

Virtual-stereo fringe reflection technique for specular free-form surface testing

NASA Astrophysics Data System (ADS)

Ma, Suodong; Li, Bo

2016-11-01

Due to their excellent ability to improve the performance of optical systems, free-form optics have attracted extensive interest in many fields, e.g. optical design of astronomical telescopes, laser beam expanders, spectral imagers, etc. However, compared with traditional simple ones, testing for such kind of optics is usually more complex and difficult which has been being a big barrier for the manufacture and the application of these optics. Fortunately, owing to the rapid development of electronic devices and computer vision technology, fringe reflection technique (FRT) with advantages of simple system structure, high measurement accuracy and large dynamic range is becoming a powerful tool for specular free-form surface testing. In order to obtain absolute surface shape distributions of test objects, two or more cameras are often required in the conventional FRT which makes the system structure more complex and the measurement cost much higher. Furthermore, high precision synchronization between each camera is also a troublesome issue. To overcome the aforementioned drawback, a virtual-stereo FRT for specular free-form surface testing is put forward in this paper. It is able to achieve absolute profiles with the help of only one single biprism and a camera meanwhile avoiding the problems of stereo FRT based on binocular or multi-ocular cameras. Preliminary experimental results demonstrate the feasibility of the proposed technique.

Thermal stability and specular reflection behaviour of CoNbZr-based bottom spin valves with nano-oxide layer

NASA Astrophysics Data System (ADS)

Kim, Jong Soo; Lee, Seong-Rae

2004-06-01

The thermal stability and specularity aspects of a CoNbZr-based bottom spin valve (SV) employing a nano-oxide layer (NOL) were investigated. The magnetoresistance (MR) ratio of the as-deposited CoNbZr-based bottom SV increased by 62% (from 6.3 to 10.2%) with incorporation of the NOL. The enhancement of the MR ratio was considered to be due to the specular effect ( increased from 0.722 to 1.363 cm) of the NOL. The MR ratio of a Ta-based bottom SV decreased by about 45% (from 6.9 to 3.8%) when the samples were annealed at 300 °C for 240 min. By contrast, the MR ratio of the CoNbZr-based bottom SV with NOL increase d by 14 % (from 10.2 to 11.7%). The root mean square roughness value of the CoNbZr layer (0.07 nm) was superior to that of the Ta layer (0.43 nm). Although Mn in IrMn diffused out to the surface through the active layers resulting in the formation of Mn oxide at the surface in the CoNbZr-based bottom SV, no trace of Mn was found in the active layers and no significant degradation occurred.

Numerical reproduction and explanation of road surface mirages under grazing-angle scattering.

PubMed

Lu, Jia; Zhou, Huaichun

2017-07-01

The mirror-like reflection image of the road surface under grazing-angle scattering can be easily observed in daily life. It was suggested that road surface mirages may occur due to a light-enhancing effect of the rough surface under grazing-angle scattering. The main purpose of this work is to explain the light-enhancing mechanism of rough surfaces under grazing-angle scattering. The off-specular reflection from a random rough magnesium oxide ceramic surface is analyzed by using the geometric optics approximation method. Then, the geometric optics approximation method is employed to develop a theoretical model to predict the observation effect of the grazing-angle scattering phenomenon of the road surface. The rough surface is assumed to consist of small-scale rough surface facets. The road surface mirage is reproduced from a large number of small-scale rough surface facets within the eye's resolution limit at grazing scattering angles, as the average bidirectional reflectance distribution function value at the bright location is about twice that of the surface in front of the mirage. It is suggested that the light-enhancing effect of the rough surface under grazing-angle scattering is not proper to be termed as "off-specular reflection," since it has nothing to do with the "specular" direction with respect to the incident direction.

Experimental evaluation of radiosity for room sound-field prediction.

PubMed

Hodgson, Murray; Nosal, Eva-Marie

2006-08-01

An acoustical radiosity model was evaluated for how it performs in predicting real room sound fields. This was done by comparing radiosity predictions with experimental results for three existing rooms--a squash court, a classroom, and an office. Radiosity predictions were also compared with those by ray tracing--a "reference" prediction model--for both specular and diffuse surface reflection. Comparisons were made for detailed and discretized echograms, sound-decay curves, sound-propagation curves, and the variations with frequency of four room-acoustical parameters--EDT, RT, D50, and C80. In general, radiosity and diffuse ray tracing gave very similar predictions. Predictions by specular ray tracing were often very different. Radiosity agreed well with experiment in some cases, less well in others. Definitive conclusions regarding the accuracy with which the rooms were modeled, or the accuracy of the radiosity approach, were difficult to draw. The results suggest that radiosity predicts room sound fields with some accuracy, at least as well as diffuse ray tracing and, in general, better than specular ray tracing. The predictions of detailed echograms are less accurate, those of derived room-acoustical parameters more accurate. The results underline the need to develop experimental methods for accurately characterizing the absorptive and reflective characteristics of room surfaces, possible including phase.

Interface morphology of Mo/Si multilayer systems with varying Mo layer thickness studied by EUV diffuse scattering.

PubMed

Haase, Anton; Soltwisch, Victor; Braun, Stefan; Laubis, Christian; Scholze, Frank

2017-06-26

We investigate the influence of the Mo-layer thickness on the EUV reflectance of Mo/Si mirrors with a set of unpolished and interface-polished Mo/Si/C multilayer mirrors. The Mo-layer thickness is varied in the range from 1.7 nm to 3.05 nm. We use a novel combination of specular and diffuse intensity measurements to determine the interface roughness throughout the multilayer stack and do not rely on scanning probe measurements at the surface only. The combination of EUV and X-ray reflectivity measurements and near-normal incidence EUV diffuse scattering allows to reconstruct the Mo layer thicknesses and to determine the interface roughness power spectral density. The data analysis is conducted by applying a matrix method for the specular reflection and the distorted-wave Born approximation for diffuse scattering. We introduce the Markov-chain Monte Carlo method into the field in order to determine the respective confidence intervals for all reconstructed parameters. We unambiguously detect a threshold thickness for Mo in both sample sets where the specular reflectance goes through a local minimum correlated with a distinct increase in diffuse scatter. We attribute that to the known appearance of an amorphous-to-crystallization transition at a certain thickness threshold which is altered in our sample system by the polishing.

Motion of glossy objects does not promote separation of lighting and surface colour

PubMed Central

2017-01-01

The surface properties of an object, such as texture, glossiness or colour, provide important cues to its identity. However, the actual visual stimulus received by the eye is determined by both the properties of the object and the illumination. We tested whether operational colour constancy for glossy objects (the ability to distinguish changes in spectral reflectance of the object, from changes in the spectrum of the illumination) was affected by rotational motion of either the object or the light source. The different chromatic and geometric properties of the specular and diffuse reflections provide the basis for this discrimination, and we systematically varied specularity to control the available information. Observers viewed animations of isolated objects undergoing either lighting or surface-based spectral transformations accompanied by motion. By varying the axis of rotation, and surface patterning or geometry, we manipulated: (i) motion-related information about the scene, (ii) relative motion between the surface patterning and the specular reflection of the lighting, and (iii) image disruption caused by this motion. Despite large individual differences in performance with static stimuli, motion manipulations neither improved nor degraded performance. As motion significantly disrupts frame-by-frame low-level image statistics, we infer that operational constancy depends on a high-level scene interpretation, which is maintained in all conditions. PMID:29291113

Optical fringe-reflection deflectometry with bundle adjustment

NASA Astrophysics Data System (ADS)

Xiao, Yong-Liang; Li, Sikun; Zhang, Qican; Zhong, Jianxin; Su, Xianyu; You, Zhisheng

2018-06-01

Liquid crystal display (LCD) screens are located outside of a camera's field of view in fringe-reflection deflectometry. Therefore, fringes that are displayed on LCD screens are obtained through specular reflection by a fixed camera. Thus, the pose calibration between the camera and LCD screen is one of the main challenges in fringe-reflection deflectometry. A markerless planar mirror is used to reflect the LCD screen more than three times, and the fringes are mapped into the fixed camera. The geometrical calibration can be accomplished by estimating the pose between the camera and the virtual image of fringes. Considering the relation between their pose, the incidence and reflection rays can be unified in the camera frame, and a forward triangulation intersection can be operated in the camera frame to measure three-dimensional (3D) coordinates of the specular surface. In the final optimization, constraint-bundle adjustment is operated to refine simultaneously the camera intrinsic parameters, including distortion coefficients, estimated geometrical pose between the LCD screen and camera, and 3D coordinates of the specular surface, with the help of the absolute phase collinear constraint. Simulation and experiment results demonstrate that the pose calibration with planar mirror reflection is simple and feasible, and the constraint-bundle adjustment can enhance the 3D coordinate measurement accuracy in fringe-reflection deflectometry.

Wide-band/angle Blazed Surfaces using Multiple Coupled Blazing Resonances

PubMed Central

Memarian, Mohammad; Li, Xiaoqiang; Morimoto, Yasuo; Itoh, Tatsuo

2017-01-01

Blazed gratings can reflect an oblique incident wave back in the path of incidence, unlike mirrors and metal plates that only reflect specular waves. Perfect blazing (and zero specular scattering) is a type of Wood’s anomaly that has been observed when a resonance condition occurs in the unit-cell of the blazed grating. Such elusive anomalies have been studied thus far as individual perfect blazing points. In this work, we present reflective blazed surfaces that, by design, have multiple coupled blazing resonances per cell. This enables an unprecedented way of tailoring the blazing operation, for widening and/or controlling of blazing bandwidth and incident angle range of operation. The surface can thus achieve blazing at multiple wavelengths, each corresponding to different incident wavenumbers. The multiple blazing resonances are combined similar to the case of coupled resonator filters, forming a blazing passband between the incident wave and the first grating order. Blazed gratings with single and multi-pole blazing passbands are fabricated and measured showing increase in the bandwidth of blazing/specular-reflection-rejection, demonstrated here at X-band for convenience. If translated to appropriate frequencies, such technique can impact various applications such as Littrow cavities and lasers, spectroscopy, radar, and frequency scanned antenna reflectors. PMID:28211506

Design Rules for Tailoring Antireflection Properties of Hierarchical Optical Structures

DOE PAGES

Leon, Juan J. Diaz; Hiszpanski, Anna M.; Bond, Tiziana C.; ...

2017-05-18

Hierarchical structures consisting of small sub-wavelength features stacked atop larger structures have been demonstrated as an effective means of reducing the reflectance of surfaces. However, optical devices require different antireflective properties depending on the application, and general unifying guidelines on hierarchical structures' design to attain a desired antireflection spectral response are still lacking. The type of reflectivity (diffuse, specular, or total/hemispherical) and its angular- and spectral-dependence are all dictated by the structural parameters. Through computational and experimental studies, guidelines have been devised to modify these various aspects of reflectivity across the solar spectrum by proper selection of the features ofmore » hierarchical structures. In this wavelength regime, micrometer-scale substructures dictate the long-wavelength spectral response and effectively reduce specular reflectance, whereas nanometer-scale substructures dictate primarily the visible wavelength spectral response and reduce diffuse reflectance. Coupling structures having these two length scales into hierarchical arrays impressively reduces surfaces' hemispherical reflectance across a broad spectrum of wavelengths and angles. Furthermore, such hierarchical structures in silicon are demonstrated having an average total reflectance across the solar spectrum of 1.1% (average weighted reflectance of 1% in the 280–2500 nm range of the AM 1.5 G spectrum) and specular reflectance <1% even at angles of incidence as high as 67°.« less

A fast method for optical simulation of flood maps of light-sharing detector modules

DOE PAGES

Shi, Han; Du, Dong; Xu, JianFeng; ...

2015-09-03

Optical simulation of the detector module level is highly desired for Position Emission Tomography (PET) system design. Commonly used simulation toolkits such as GATE are not efficient in the optical simulation of detector modules with complicated light-sharing configurations, where a vast amount of photons need to be tracked. Here, we present a fast approach based on a simplified specular reflectance model and a structured light-tracking algorithm to speed up the photon tracking in detector modules constructed with polished finish and specular reflector materials. We also simulated conventional block detector designs with different slotted light guide patterns using the new approachmore » and compared the outcomes with those from GATE simulations. And while the two approaches generated comparable flood maps, the new approach was more than 200–600 times faster. The new approach has also been validated by constructing a prototype detector and comparing the simulated flood map with the experimental flood map. The experimental flood map has nearly uniformly distributed spots similar to those in the simulated flood map. In conclusion, the new approach provides a fast and reliable simulation tool for assisting in the development of light-sharing-based detector modules with a polished surface finish and using specular reflector materials.« less

Prototype Development and Evaluation of Self-Cleaning Concentrated Solar Power Collectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mazumder, Malay K.; Horenstein, Mark N.; Joglekar, Nitin R.

The feasibility of integrating and retrofitting transparent electrodynamic screens (EDS) on the front surfaces of solar collectors was established as a means to provide active self-cleaning properties for parabolic trough and heliostat reflectors, solar panels, and Fresnel lenses. Prototype EDS-integrated solar collectors, including second-surface glass mirrors, metallized Acrylic-film mirrors, and dielectric mirrors, were produced and tested in environmental test chambers for removing the dust layer deposited on the front surface of the mirrors. The evaluation of the prototype EDS-integrated mirrors was conducted using dust and environmental conditions that simulate the field conditions of the Mojave Desert. Test results showed thatmore » the specular reflectivity of the mirrors could be maintained at over 90% over a wide range of dust loadings ranging from 0 to 10 g/m 2, with particle diameter varying from 1 to 50 μm. The measurement of specular reflectivity (SR) was performed using a D&S Reflectometer at wavelength 660 nm. A non-contact reflectometer was designed and constructed for rapid measurement of specular reflectivity at the same wavelength. The use of this new noncontact instrument allowed us to measure SR before and after EDS activation. Several EDS prototypes were constructed and evaluated with different electrode configurations, electrode materials, and encapsulating dielectric materials.« less

A Precise Visual Method for Narrow Butt Detection in Specular Reflection Workpiece Welding.

PubMed

Zeng, Jinle; Chang, Baohua; Du, Dong; Hong, Yuxiang; Chang, Shuhe; Zou, Yirong

2016-09-13

During the complex path workpiece welding, it is important to keep the welding torch aligned with the groove center using a visual seam detection method, so that the deviation between the torch and the groove can be corrected automatically. However, when detecting the narrow butt of a specular reflection workpiece, the existing methods may fail because of the extremely small groove width and the poor imaging quality. This paper proposes a novel detection method to solve these issues. We design a uniform surface light source to get high signal-to-noise ratio images against the specular reflection effect, and a double-line laser light source is used to obtain the workpiece surface equation relative to the torch. Two light sources are switched on alternately and the camera is synchronized to capture images when each light is on; then the position and pose between the torch and the groove can be obtained nearly at the same time. Experimental results show that our method can detect the groove effectively and efficiently during the welding process. The image resolution is 12.5 μm and the processing time is less than 10 ms per frame. This indicates our method can be applied to real-time narrow butt detection during high-speed welding process.

GINA--a polarized neutron reflectometer at the Budapest Neutron Centre.

PubMed

Bottyán, L; Merkel, D G; Nagy, B; Füzi, J; Sajti, Sz; Deák, L; Endrőczi, G; Petrenko, A V; Major, J

2013-01-01

The setup, capabilities, and operation parameters of the neutron reflectometer GINA, the recently installed "Grazing Incidence Neutron Apparatus" at the Budapest Neutron Centre, are introduced. GINA, a dance-floor-type, constant-energy, angle-dispersive reflectometer is equipped with a 2D position-sensitive detector to study specular and off-specular scattering. Wavelength options between 3.2 and 5.7 Å are available for unpolarized and polarized neutrons. Spin polarization and analysis are achieved by magnetized transmission supermirrors and radio-frequency adiabatic spin flippers. As a result of vertical focusing by a five-element pyrolytic graphite monochromator, the reflected intensity from a 20 × 20 mm(2) sample has been doubled. GINA is dedicated to studies of magnetic films and heterostructures, but unpolarized options for non-magnetic films, membranes, and other surfaces are also provided. Shortly after its startup, reflectivity values as low as 3 × 10(-5) have been measured by the instrument. The instrument capabilities are demonstrated by a non-polarized and a polarized reflectivity experiment on a Si wafer and on a magnetic film of [(62)Ni/(nat)Ni](5) isotope-periodic layer composition. The facility is now open for the international user community. Its further development is underway establishing new sample environment options and spin analysis of off-specularly scattered radiation as well as further decreasing the background.

Interface or bulk scattering in the semiclassical theory for spin valves

NASA Astrophysics Data System (ADS)

Wang, L.; McMahon, W. J.; Liu, B.; Wu, Y. H.; Chong, C. T.

2004-06-01

By taking into account spin asymmetries of the interface transmissions and the bulk mean free paths, we have treated pure interface, non-pure interface, bulk, and interface plus bulk scattering within the semiclassical Boltzmann theory. First, the optimizations of NOL (nano-oxide-layers) insertions in bottom, synthetic, and dual spin valves and the variations of the giant magnetoresistance (GMR) with the thickness of the free layer have been examined. For non-pure interface, bulk, and interface plus bulk scattering, qualitative trends of GMR versus NOL positions in spin valves are similar to each other. For pure interface scattering, there is no optimized NOL insertion positions and the blocking effect of the NOL inserted in the spacer remains effective as other three kinds of scattering. The GMR ratio for bulk scattering simply approaches zero when the free layer thickness becomes short; in contrast, for interface scattering or interface plus bulk scattering, the GMR ratio is nonzero at zero thickness of the free layer. Second, the relationships between GMR and specular and diffusive scattering have been explored. As far as specular reflection is concerned, our results imply that for a realistic bottom spin filter spin valve, Ta/NiFe/IrMn/CoFe/Cu/CoFe/Cu/Ta, roughness of the surfaces of Ta and the interfaces of Ta/NiFe, NiFe/IrMn, pinned layer/spacer, and spacer/free layer may lead to large GMR. We also find that the enhancement of GMR due to surface specular reflection is only a pure interface effect. The dependences of GMR on the specular transmissions roughly follow square relations. The trends of GMR against the spin-down diffusive scattering depend on the values of the spin-up transmission. Finally, impurity scattering was investigated and our semiclassical results are in qualitative agreement with the experiments and the quantum theory.

Panoramic view of human corneal endothelial cell layer observed by a prototype slit-scanning wide-field contact specular microscope.

PubMed

Tanaka, Hiroshi; Okumura, Naoki; Koizumi, Noriko; Sotozono, Chie; Sumii, Yasuhiro; Kinoshita, Shigeru

2017-05-01

To observe the most peripheral region of the corneal endothelial cell (CEC) layer as long as optically recordable by use of a prototype slit-scanning wide-field contact specular microscope and produce a panoramic image to evaluate the variation of CEC density with ageing. Observational case series study. This study involved 15 eyes of 15 normal healthy subjects divided into three groups according to age: A (20-40 years), B (41-60 years) and C (>60 years). The corneal endothelial layer of each eye was recorded in a horizontal direction, from nasal to temporal, with a slit-scanning wide-field contact specular microscope (Konan) and endothelial cell density (ECD) in three specific regions (central, mid-peripheral, and peripheral) was automatically calculated via built-in analysis software. Corneal endothelial images from near the surgical limbus to limbus in all eyes were clearly recorded and panoramic images were made by combining still images. ECD in groups A, B and C were 2809±186, 2717±91 and 2580±129 cells/mm 2 at the centre, 2902±242, 2772±97 and 2604±187 cells/mm 2 at the mid-periphery and 2893±308, 2691±99 and 2533±112 cells/mm 2 at the periphery. Significance differences in ECD was found between groups A and C in all regions and groups between B and C at mid-peripheral region. A prototype slit-scanning wide-field contact specular microscope enabled us to record the endothelial layer from the surgical limbus to limbus of the cornea and compare specific areas among subjects, and showed that ECD in each region of the cornea decreases with ageing. UMIN000021264, Results. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Perceiving Object Shape from Specular Highlight Deformation, Boundary Contour Deformation, and Active Haptic Manipulation.

PubMed

Norman, J Farley; Phillips, Flip; Cheeseman, Jacob R; Thomason, Kelsey E; Ronning, Cecilia; Behari, Kriti; Kleinman, Kayla; Calloway, Autum B; Lamirande, Davora

2016-01-01

It is well known that motion facilitates the visual perception of solid object shape, particularly when surface texture or other identifiable features (e.g., corners) are present. Conventional models of structure-from-motion require the presence of texture or identifiable object features in order to recover 3-D structure. Is the facilitation in 3-D shape perception similar in magnitude when surface texture is absent? On any given trial in the current experiments, participants were presented with a single randomly-selected solid object (bell pepper or randomly-shaped "glaven") for 12 seconds and were required to indicate which of 12 (for bell peppers) or 8 (for glavens) simultaneously visible objects possessed the same shape. The initial single object's shape was defined either by boundary contours alone (i.e., presented as a silhouette), specular highlights alone, specular highlights combined with boundary contours, or texture. In addition, there was a haptic condition: in this condition, the participants haptically explored with both hands (but could not see) the initial single object for 12 seconds; they then performed the same shape-matching task used in the visual conditions. For both the visual and haptic conditions, motion (rotation in depth or active object manipulation) was present in half of the trials and was not present for the remaining trials. The effect of motion was quantitatively similar for all of the visual and haptic conditions-e.g., the participants' performance in Experiment 1 was 93.5 percent higher in the motion or active haptic manipulation conditions (when compared to the static conditions). The current results demonstrate that deforming specular highlights or boundary contours facilitate 3-D shape perception as much as the motion of objects that possess texture. The current results also indicate that the improvement with motion that occurs for haptics is similar in magnitude to that which occurs for vision.

Perceiving Object Shape from Specular Highlight Deformation, Boundary Contour Deformation, and Active Haptic Manipulation

PubMed Central

Cheeseman, Jacob R.; Thomason, Kelsey E.; Ronning, Cecilia; Behari, Kriti; Kleinman, Kayla; Calloway, Autum B.; Lamirande, Davora

2016-01-01

It is well known that motion facilitates the visual perception of solid object shape, particularly when surface texture or other identifiable features (e.g., corners) are present. Conventional models of structure-from-motion require the presence of texture or identifiable object features in order to recover 3-D structure. Is the facilitation in 3-D shape perception similar in magnitude when surface texture is absent? On any given trial in the current experiments, participants were presented with a single randomly-selected solid object (bell pepper or randomly-shaped “glaven”) for 12 seconds and were required to indicate which of 12 (for bell peppers) or 8 (for glavens) simultaneously visible objects possessed the same shape. The initial single object’s shape was defined either by boundary contours alone (i.e., presented as a silhouette), specular highlights alone, specular highlights combined with boundary contours, or texture. In addition, there was a haptic condition: in this condition, the participants haptically explored with both hands (but could not see) the initial single object for 12 seconds; they then performed the same shape-matching task used in the visual conditions. For both the visual and haptic conditions, motion (rotation in depth or active object manipulation) was present in half of the trials and was not present for the remaining trials. The effect of motion was quantitatively similar for all of the visual and haptic conditions–e.g., the participants’ performance in Experiment 1 was 93.5 percent higher in the motion or active haptic manipulation conditions (when compared to the static conditions). The current results demonstrate that deforming specular highlights or boundary contours facilitate 3-D shape perception as much as the motion of objects that possess texture. The current results also indicate that the improvement with motion that occurs for haptics is similar in magnitude to that which occurs for vision. PMID:26863531

Global analysis of the temperature and flow fields in samples heated in multizone resistance furnaces

NASA Astrophysics Data System (ADS)

Pérez-Grande, I.; Rivas, D.; de Pablo, V.

The temperature field in samples heated in multizone resistance furnaces will be analyzed, using a global model where the temperature fields in the sample, the furnace and the insulation are coupled; the input thermal data is the electric power supplied to the heaters. The radiation heat exchange between the sample and the furnace is formulated analytically, taking into account specular reflections at the sample; for the solid sample the reflectance is both diffuse and specular, and for the melt it is mostly specular. This behavior is modeled through the exchange view factors, which depend on whether the sample is solid or liquid, and, therefore, they are not known a priori. The effect of this specular behavior in the temperature field will be analyzed, by comparing with the case of diffuse samples. A parameter of great importance is the thermal conductivity of the insulation material; it will be shown that the temperature field depends strongly on it. A careful characterization of the insulation is therefore necessary, here it will be done with the aid of experimental results, which will also serve to validate the model. The heating process in the floating-zone technique in microgravity conditions will be simulated; parameters like the Marangoni number or the temperature gradient at the melt-crystal interface will be estimated. Application to the case of compound samples (graphite-silicon-graphite) will be made; the temperature distribution in the silicon part will be studied, especially the temperature difference between the two graphite rods that hold the silicon, since it drives the thermocapillary flow in the melt. This flow will be studied, after coupling the previous model with the convective effects. The possibility of suppresing this flow by the controlled vibration of the graphite rods will be also analyzed. Numerical results show that the thermocapillary flow can indeed be counterbalanced quite effectively.

Structured Light Based 3d Scanning for Specular Surface by the Combination of Gray Code and Phase Shifting

NASA Astrophysics Data System (ADS)

Zhang, Yujia; Yilmaz, Alper

2016-06-01

Surface reconstruction using coded structured light is considered one of the most reliable techniques for high-quality 3D scanning. With a calibrated projector-camera stereo system, a light pattern is projected onto the scene and imaged by the camera. Correspondences between projected and recovered patterns are computed in the decoding process, which is used to generate 3D point cloud of the surface. However, the indirect illumination effects on the surface, such as subsurface scattering and interreflections, will raise the difficulties in reconstruction. In this paper, we apply maximum min-SW gray code to reduce the indirect illumination effects of the specular surface. We also analysis the errors when comparing the maximum min-SW gray code and the conventional gray code, which justifies that the maximum min-SW gray code has significant superiority to reduce the indirect illumination effects. To achieve sub-pixel accuracy, we project high frequency sinusoidal patterns onto the scene simultaneously. But for specular surface, the high frequency patterns are susceptible to decoding errors. Incorrect decoding of high frequency patterns will result in a loss of depth resolution. Our method to resolve this problem is combining the low frequency maximum min-SW gray code and the high frequency phase shifting code, which achieves dense 3D reconstruction for specular surface. Our contributions include: (i) A complete setup of the structured light based 3D scanning system; (ii) A novel combination technique of the maximum min-SW gray code and phase shifting code. First, phase shifting decoding with sub-pixel accuracy. Then, the maximum min-SW gray code is used to resolve the ambiguity resolution. According to the experimental results and data analysis, our structured light based 3D scanning system enables high quality dense reconstruction of scenes with a small number of images. Qualitative and quantitative comparisons are performed to extract the advantages of our new combined coding method.

Geometry of illumination, luminance contrast, and gloss perception.

PubMed

Leloup, Frédéric B; Pointer, Michael R; Dutré, Philip; Hanselaer, Peter

2010-09-01

The influence of both the geometry of illumination and luminance contrast on gloss perception has been examined using the method of paired comparison. Six achromatic glass samples having different lightness were illuminated by two light sources. Only one of these light sources was visible in reflection by the observer. By separate adjustment of the intensity of both light sources, the luminance of both the reflected image and the adjacent off-specular surroundings could be individually varied. It was found that visual gloss appraisal did not correlate with instrumentally measured specular gloss; however, psychometric contrast seemed to be a much better correlate. It has become clear that not only the sample surface characteristics determine gloss perception: the illumination geometry could be an even more important factor.

Digital curation and online resources: digital scanning of surgical tools at the royal college of physicians and surgeons of Glasgow for an open university learning resource.

PubMed

Earley, Kirsty; Livingstone, Daniel; Rea, Paul M

2017-01-01

Collection preservation is essential for the cultural status of any city. However, presenting a collection publicly risks damage. Recently this drawback has been overcome by digital curation. Described here is a method of digitisation using photogrammetry and virtual reality software. Items were selected from the Royal College of Physicians and Surgeons of Glasgow archives, and implemented into an online learning module for the Open University. Images were processed via Agisoft Photoscan, Autodesk Memento, and Garden Gnome Object 2VR. Although problems arose due to specularity, 2VR digital models were developed for online viewing. Future research must minimise the difficulty of digitising specular objects.

GPS Multipath Fade Measurements to Determine L-Band Ground Reflectivity Properties

NASA Technical Reports Server (NTRS)

Kavak, Adnan; Xu, Guanghan; Vogel, W. J.

1996-01-01

In personal satellite communications, especially when the line-of-sight is clear, ground specular reflected signals along with direct signals are received by low gain, almost omni-directional subscriber antennas. A six-channel, C/A code processing, global positioning system (GPS) receiver with an almost omni-directional patch antenna was used to take measurements over three types of ground to characterize 1.575 GHz specular ground reflections and ground dielectric properties. Fade measurements were taken over grass, asphalt, and lake water surfaces by placing the antenna in a vertical position at a fixed height from the ground. Electrical characteristics (conductivity and dielectric constant) of these surfaces (grass, asphalt, lake water) were obtained by matching computer simulations to the experimental results.

GPS Multipath Fade Measurements to Determine L-Band Ground Reflectivity Properties

NASA Technical Reports Server (NTRS)

Kavak, Adnan; Xu, Guang-Han; Vogel, Wolfhard J.

1996-01-01

In personal satellite communications, especially when the line-of-sight is clear, ground specular reflected signals along with direct signals are received by low gain, almost omni-directional subscriber antennas. A six-channel, C/A code processing, GPS receiver with an almost omni-directional patch antenna was used to take measurements over three types of ground to characterize 1.575 GHz specular ground reflections and ground dielectric properties. Fade measurements were taken over grass, asphalt, and lake water surfaces by placing the antenna in a vertical position at a fixed height from the ground. Electrical characteristics (conductivity and dielectric constant) of these surfaces (grass, asphalt, lake water) were obtained by matching computer simulations to the experimental results.

Optical reflectivity study of silicon ion implanted poly(methyl methacrylate)

NASA Astrophysics Data System (ADS)

Hadjichristov, Georgi B.; Stefanov, Ivan L.; Florian, Bojana I.; Blaskova, Gergana D.; Ivanov, Victor G.; Faulques, Eric

2009-11-01

The optical reflectivity (both specular and off-specular) of poly(methyl methacrylate) (PMMA) implanted with silicon ions (Si +) at energy of 50 keV, is studied in the spectral range 0.25-25 μm. The effect from the Si + implantation on the reflectivity of two PMMA materials is examined in the dose range from 10 14 to 10 17 ions/cm 2 and is linked to the structure formed in this ion implanted plastic. As compared to the pristine PMMA, an enhancement of the reflectivity of Si + implanted PMMA is observed, that is attributed to the modification of the subsurface region of PMMA upon the ion implantation. The ion-produced subsurface organic interface is also probed by laser-induced thermo-lens.

Refractive index inversion based on Mueller matrix method

NASA Astrophysics Data System (ADS)

Fan, Huaxi; Wu, Wenyuan; Huang, Yanhua; Li, Zhaozhao

2016-03-01

Based on Stokes vector and Jones vector, the correlation between Mueller matrix elements and refractive index was studied with the result simplified, and through Mueller matrix way, the expression of refractive index inversion was deduced. The Mueller matrix elements, under different incident angle, are simulated through the expression of specular reflection so as to analyze the influence of the angle of incidence and refractive index on it, which is verified through the measure of the Mueller matrix elements of polished metal surface. Research shows that, under the condition of specular reflection, the result of Mueller matrix inversion is consistent with the experiment and can be used as an index of refraction of inversion method, and it provides a new way for target detection and recognition technology.

Measurement and Modeling of the Optical Scattering Properties of Crop Canopies

NASA Technical Reports Server (NTRS)

Vanderbilt, V. C.; Grant, L.

1984-01-01

Efforts in measuring, analyzing, and mathematically modeling the specular, polarized, and diffuse light scattering properties of several plant canopies and their component parts (leaves, stems, fruit, soil) as a function of view angle and illumination angle are reported. Specific objectives were: (1) to demonstrate a technique for determining the specular and diffuse components of the reflectance factor of plant canopies; (2) to acquire the measurements and begin assembling a data set for developing and testing canopy reflectance models; (3) to design and build a new optical instrument to measure the light scattering properties of individual leaves; and (4) to use this instrument to survey and investigate the information in the light scattering properties of individual leaves of crops, forests, weeds, and horticulture.

Solution of the 2-D steady-state radiative transfer equation in participating media with specular reflections using SUPG and DG finite elements

NASA Astrophysics Data System (ADS)

Le Hardy, D.; Favennec, Y.; Rousseau, B.

2016-08-01

The 2D radiative transfer equation coupled with specular reflection boundary conditions is solved using finite element schemes. Both Discontinuous Galerkin and Streamline-Upwind Petrov-Galerkin variational formulations are fully developed. These two schemes are validated step-by-step for all involved operators (transport, scattering, reflection) using analytical formulations. Numerical comparisons of the two schemes, in terms of convergence rate, reveal that the quadratic SUPG scheme proves efficient for solving such problems. This comparison constitutes the main issue of the paper. Moreover, the solution process is accelerated using block SOR-type iterative methods, for which the determination of the optimal parameter is found in a very cheap way.

Secondary-electron emission by 0.5-MeV/u H, He, and Li ions specularly reflected from a SnTe(001) surface: Possibility of the surface track potential reducing the secondary-electron yield at a semiconductor surface

NASA Astrophysics Data System (ADS)

Kimura, Kenji; Usui, Satoshi; Nakajima, Kaoru

2000-12-01

We have measured secondary-electron (SE) yield γ induced by 0.5 MeV/u H, He, and Li ions specularly reflected from a SnTe(001) surface. The position-dependent SE production rate is derived from the observed γ. The SE production rate normalized by the observed mean square charge of the reflected ions is almost independent of the atomic number of the projectile ion. This indicates that the surface track potential induced by the projectile ion is negligibly small to affect the SE emission at semiconductor surfaces probably due to rapid relaxation processes.

Calibration of a laboratory spectrophotometer for specular light by means of stacked glass plates.

NASA Technical Reports Server (NTRS)

Allen, W. A.; Richardson, A. J.

1971-01-01

Stacked glass plates have been used to calibrate a laboratory spectrophotometer, over the spectral range 0.5-2.5 microns, for specular light. The uncalibrated instrument was characterized by systematic errors when used to measure the reflectance and transmittance of stacked glass plates. Calibration included first, a determination of the reflectance of a standard composed of barium sulfate paint deposited on an aluminum plate; second, the approximation of the reflectance and transmittance residuals between observed and computed values by means of cubic equations; and, finally, the removal of the systematic errors by a computer. The instrument, after calibration, was accurate to 1% when used to measure the reflectance and transmittance of stacked glass plates.

Polarization sensitive camera for the in vitro diagnostic and monitoring of dental erosion

NASA Astrophysics Data System (ADS)

Bossen, Anke; Rakhmatullina, Ekaterina; Lussi, Adrian; Meier, Christoph

Due to a frequent consumption of acidic food and beverages, the prevalence of dental erosion increases worldwide. In an initial erosion stage, the hard dental tissue is softened due to acidic demineralization. As erosion progresses, a gradual tissue wear occurs resulting in thinning of the enamel. Complete loss of the enamel tissue can be observed in severe clinical cases. Therefore, it is essential to provide a diagnosis tool for an accurate detection and monitoring of dental erosion already at early stages. In this manuscript, we present the development of a polarization sensitive imaging camera for the visualization and quantification of dental erosion. The system consists of two CMOS cameras mounted on two sides of a polarizing beamsplitter. A horizontal linearly polarized light source is positioned orthogonal to the camera to ensure an incidence illumination and detection angles of 45°. The specular reflected light from the enamel surface is collected with an objective lens mounted on the beam splitter and divided into horizontal (H) and vertical (V) components on each associate camera. Images of non-eroded and eroded enamel surfaces at different erosion degrees were recorded and assessed with diagnostic software. The software was designed to generate and display two types of images: distribution of the reflection intensity (V) and a polarization ratio (H-V)/(H+V) throughout the analyzed tissue area. The measurements and visualization of these two optical parameters, i.e. specular reflection intensity and the polarization ratio, allowed detection and quantification of enamel erosion at early stages in vitro.

Changes in corneal endothelial cell density and the cumulative risk of corneal decompensation after Ahmed glaucoma valve implantation.

PubMed

Kim, Kyoung Nam; Lee, Sung Bok; Lee, Yeon Hee; Lee, Jong Joo; Lim, Hyung Bin; Kim, Chang-Sik

2016-07-01

To evaluate changes in the corneal endothelial cell density (ECD) and corneal decompensation following Ahmed glaucoma valve (AGV) implantation. This study was retrospective and observational case series. Patients with refractory glaucoma who underwent AGV implantation and were followed >5 years were consecutively enrolled. We reviewed the medical records, including the results of central corneal specular microscopy. Of the 127 enrolled patients, the annual change in ECD (%) was determined using linear regression for 72 eyes evaluated at least four times using serial specular microscopic examination and compared with 31 control eyes (fellow glaucomatous eyes under medical treatment). The main outcome measures were cumulative risk of corneal decompensation and differences in the ECD loss rates between subjects and controls. The mean follow-up after AGV implantation was 43.1 months. There were no cases of postoperative tube-corneal touch. The cumulative risk of corneal decompensation was 3.3%, 5 years after AGV implantation. There was a more rapid loss of ECD in the 72 subject eyes compared with the 31 controls (-7.0% and -0.1%/year, respectively; p<0.001). However, the rate of loss decreased over time and statistical significance compared with control eyes disappeared after 2 years postoperatively: -10.7% from baseline to 1 year (p<0.01), -7.0% from 1 year to 2 years (p=0.037), -4.2% from 2 years to 3 years (p=0.230) and -2.7% from 3 years to the final follow-up (p=0.111). In case of uncomplicated AGV implantation, the cumulative risk of corneal decompensation was 3.3%, 5 years after the operation. The ECD loss was statistically greater in eyes with AGV than in control eyes without AGV, but the difference was significant only up to 2 years post surgery. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Optical Reflectance Measurements for Commonly Used Reflectors

NASA Astrophysics Data System (ADS)

Janecek, Martin; Moses, William W.

2008-08-01

When simulating light collection in scintillators, modeling the angular distribution of optical light reflectance from surfaces is very important. Since light reflectance is poorly understood, either purely specular or purely diffuse reflectance is generally assumed. In this paper we measure the optical reflectance distribution for eleven commonly used reflectors. A 440 nm, output power stabilized, un-polarized laser is shone onto a reflector at a fixed angle of incidence. The reflected light's angular distribution is measured by an array of silicon photodiodes. The photodiodes are movable to cover 2pi of solid angle. The light-induced current is, through a multiplexer, read out with a digital multimeter. A LabVIEW program controls the motion of the laser and the photodiode array, the multiplexer, and the data collection. The laser can be positioned at any angle with a position accuracy of 10 arc minutes. Each photodiode subtends 6.3deg, and the photodiode array can be positioned at any angle with up to 10 arc minute angular resolution. The dynamic range for the current measurements is 10 5:1. The measured light reflectance distribution was measured to be specular for several ESR films as well as for aluminum foil, mostly diffuse for polytetrafluoroethylene (PTFE) tape and titanium dioxide paint, and neither specular nor diffuse for Lumirrorreg, Melinexreg and Tyvekreg. Instead, a more complicated light distribution was measured for these three materials.

SPALEED Studies of the Growth of Zero to Mono-layer Graphene on SiC(0001)

NASA Astrophysics Data System (ADS)

Hupalo, M.; Hershberger, M. T.; Hattab, H.; McDougall, D. C.; Horn von Hoegen, M.; Tringides, M. C.

The growth of graphene on SiC was studied in detail with SPA LEED to understand the transition from zero to monolayer graphene with increasing temperature starting at 1200°C. Both the changing diffraction spots with annealing and their line shapes are studied in detail until a fully completed monolayer is obtained with only 6x6 spots remaining. In particular we focus on two strong features not investigated previously: (i) superstructures spots at n/13 locations present between the specular and the graphene spots. These spots are possibly related to different coincidence lattices before graphene locks into its final 6x6 orientation. (ii) The presence of a very broad background intensity covering ~60% of the BZ both around the specular and graphene spots whose origin is still unknown. Detailed studies of the dependence of this background component on energy and comparison between the graphene and specular spots suggest that the origin is not due to the standard variation with electron energy, i.e. a g(s) curve caused by the topography. Throughout the literature this broad background has been seen in graphene grown in different types of substrates. We comment on possible reasons for the origin of the background. Ames Laboratory is operated by the US-DOE under Contract No. DE-AC02-07CH11358.

Matrix isolation apparatus with extended sample collection capability

DOEpatents

Reedy, Gerald T.

1987-01-01

A gas-sample collection device provides for the matrix isolation of increased amounts of a sample material for spectrographic analysis from a gas chromatographic separation. The device includes an evacuated sample collection chamber containing a disc-like specular carousel having a generally circular lateral surface upon which the sample is deposited in an inert gas matrix for infrared (IR) spectral analysis. The evacuated sample chamber is mounted in a fixed manner and is coupled to and supports a rotating cryostatic coupler which, in turn, supports the specular carousel within the collection chamber. A rotational drive system connected to the cryostatic coupler provides for its rotational displacement as well as that of the sample collecting carousel. In addition, rotation of the cryostatic coupler effects vertical displacement of the carousel to permit the collection of an extended sample band in a helical configuration on the entire lateral surface of the carousel. The various components of the carousel's angular/linear displacement drive system are located exterior to the cryostatic coupler for easy access and improved operation. The cryostatic coupler includes a 360.degree. rotary union assembly for permitting the delivery of a high pressure working fluid to the cryostatic coupler in a continuous flow manner for maintaining the specular carousel at a low temperature, e.g., 10.degree.-20.degree. K., for improved uninterrupted gas sample collection and analysis.

Optical losses of solar mirrors due to atmospheric contamination at Liberal, Kansas and Oologah, Oklahoma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dake, L.S.; Lind, M.A.

An assessment is presented of the effect of outdoor exposure on mirrors located at two sites selected for potential solar cogeneration/repowering facilities: Liberal, Kansas and Oologah, Oklahoma. Mirror coupons were placed on tracking heliostat simulators located in the proposed heliostat fields and were removed periodically. The spectral hemispherical and diffuse reflectances of these coupons were measured. Representative samples were analyzed for the chemical composition of the dust particulates using SEM/EDX. Other samples were washed with a high pressure spray and recharacterized to determine the effects of the residual dust. Average specular reflectance losses over the entire test period (up tomore » 504 days) were 6 to 12%, with a range of 1 to 30%. Specular reflectance losses varied widely from day to day depending on local weather conditions. The losses due to scattering were 2 to 5 times greater than the losses due to absorptance. The average degradation rate over the first thirty days was an order of magnitude larger than the average degradation rate over the entire sampling period. Specular reflectance loss rates averaged 0.5% per day and greater between periods of natural cleaning. The chemical composition of the dust on the mirrors was characteristic of the indigenous soil, with some samples also showing the presence of sulfur and chlorine, possibly from cooling tower drift.« less

Composition dependence of charge and magnetic length scales in mixed valence manganite thin films

PubMed Central

Singh, Surendra; Freeland, J. W.; Fitzsimmons, M. R.; Jeen, H.; Biswas, A.

2016-01-01

Mixed-valence manganese oxides present striking properties like the colossal magnetoresistance, metal-insulator transition (MIT) that may result from coexistence of ferromagnetic, metallic and insulating phases. Percolation of such phase coexistence in the vicinity of MIT leads to first-order transition in these manganites. However the length scales over which the electronic and magnetic phases are separated across MIT which appears compelling for bulk systems has been elusive in (La1−yPry)1−xCaxMnO3 films. Here we show the in-plane length scale over which charge and magnetism are correlated in (La0.4Pr0.6)1−xCaxMnO3 films with x = 0.33 and 0.375, across the MIT temperature. We combine electrical transport (resistance) measurements, x-ray absorption spectroscopy (XAS), x-ray magnetic circular dichroism (XMCD), and specular/off-specular x-ray resonant magnetic scattering (XRMS) measurements as a function of temperature to elucidate relationships between electronic, magnetic and morphological structure of the thin films. Using off-specular XRMS we obtained the charge-charge and charge-magnetic correlation length of these LPCMO films across the MIT. We observed different charge-magnetic correlation length for two films which increases below the MIT. The different correlation length shown by two films may be responsible for different macroscopic (transport and magnetic) properties. PMID:27461993

A robust motion estimation system for minimal invasive laparoscopy

NASA Astrophysics Data System (ADS)

Marcinczak, Jan Marek; von Öhsen, Udo; Grigat, Rolf-Rainer

2012-02-01

Laparoscopy is a reliable imaging method to examine the liver. However, due to the limited field of view, a lot of experience is required from the surgeon to interpret the observed anatomy. Reconstruction of organ surfaces provide valuable additional information to the surgeon for a reliable diagnosis. Without an additional external tracking system the structure can be recovered from feature correspondences between different frames. In laparoscopic images blurred frames, specular reflections and inhomogeneous illumination make feature tracking a challenging task. We propose an ego-motion estimation system for minimal invasive laparoscopy that can cope with specular reflection, inhomogeneous illumination and blurred frames. To obtain robust feature correspondence, the approach combines SIFT and specular reflection segmentation with a multi-frame tracking scheme. The calibrated five-point algorithm is used with the MSAC robust estimator to compute the motion of the endoscope from multi-frame correspondence. The algorithm is evaluated using endoscopic videos of a phantom. The small incisions and the rigid endoscope limit the motion in minimal invasive laparoscopy. These limitations are considered in our evaluation and are used to analyze the accuracy of pose estimation that can be achieved by our approach. The endoscope is moved by a robotic system and the ground truth motion is recorded. The evaluation on typical endoscopic motion gives precise results and demonstrates the practicability of the proposed pose estimation system.

Composition dependence of electronic, magnetic, transport and morphological properties of mixed valence manganite thin films

DOE PAGES

Singh, Surendra; Freeland, J. W.; Fitzsimmons, Michael R.; ...

2016-07-27

Mixed-valence manganese oxides present striking properties like the colossal magnetoresistance, metal-insulator transition (MIT) that may result from coexistence of ferromagnetic, metallic and insulating phases. Percolation of such phase coexistence in the vicinity of MIT leads to first-order transition in these manganites. However the length scales over which the electronic and magnetic phases are separated across MIT which appears compelling for bulk systems has been elusive in (La 1-yPr y) 1-xCaxMnO 3 films. Here we show the in-plane length scale over which charge and magnetism are correlated in (La 0.4Pr 0.6) 1-xCaxMnO3 films with x = 0.33 and 0.375, across themore » MIT temperature. We combine electrical transport (resistance) measurements, x-ray absorption spectroscopy (XAS), x-ray magnetic circular dichroism (XMCD), and specular/off-specular x-ray resonant magnetic scattering (XRMS) measurements as a function of temperature to elucidate relationships between electronic, magnetic and morphological structure of the thin films. Using off-specular XRMS we obtained the charge-charge and charge-magnetic correlation length of these LPCMO films across the MIT. We observed different charge-magnetic correlation length for two films which increases below the MIT. The different correlation length shown by two films may be responsible for different macroscopic (transport and magnetic) properties.« less

Reflective properties of randomly rough surfaces under large incidence angles.

PubMed

Qiu, J; Zhang, W J; Liu, L H; Hsu, P-f; Liu, L J

2014-06-01

The reflective properties of randomly rough surfaces at large incidence angles have been reported due to their potential applications in some of the radiative heat transfer research areas. The main purpose of this work is to investigate the formation mechanism of the specular reflection peak of rough surfaces at large incidence angles. The bidirectional reflectance distribution function (BRDF) of rough aluminum surfaces with different roughnesses at different incident angles is measured by a three-axis automated scatterometer. This study used a validated and accurate computational model, the rigorous coupled-wave analysis (RCWA) method, to compare and analyze the measurement BRDF results. It is found that the RCWA results show the same trend of specular peak as the measurement. This paper mainly focuses on the relative roughness at the range of 0.16<σ/λ<5.35. As the relative roughness decreases, the specular peak enhancement dramatically increases and the scattering region significantly reduces, especially under large incidence angles. The RCWA and the Rayleigh criterion results have been compared, showing that the relative error of the total integrated scatter increases as the roughness of the surface increases at large incidence angles. In addition, the zero-order diffractive power calculated by RCWA and the reflectance calculated by Fresnel equations are compared. The comparison shows that the relative error declines sharply when the incident angle is large and the roughness is small.

A semi-automated, field-portable microscopy platform for clinical diagnostic applications

NASA Astrophysics Data System (ADS)

Jagannadh, Veerendra Kalyan; Srinivasan, Rajesh; Gorthi, Sai Siva

2015-08-01

Clinical microscopy is a versatile diagnostic platform used for diagnosis of a multitude of diseases. In the recent past, many microfluidics based point-of-care diagnostic devices have been developed, which serve as alternatives to microscopy. However, these point-of-care devices are not as multi-functional and versatile as clinical microscopy. With the use of custom designed optics and microfluidics, we have developed a versatile microscopy-based cellular diagnostic platform, which can be used at the point of care. The microscopy platform presented here is capable of detecting infections of very low parasitemia level (in a very small quantity of sample), without the use of any additional computational hardware. Such a cost-effective and portable diagnostic device, would greatly impact the quality of health care available to people living in rural locations of the world. Apart from clinical diagnostics, it's applicability to field research in environmental microbiology has also been outlined.

Improving sputum microscopy services for the diagnosis of tuberculosis in Peru and Bolivia.

PubMed

Siddiqi, K; Newell, J N; Van der Stuyft, P; Gotuzzo, E; Torrico, F; Van Deun, A; Walley, J

2007-06-01

Sixteen primary care health centres in Peru and Bolivia. To assess the utilisation of microscopy services in Peru and Bolivia and determine if clinical audit, a quality improvement tool, improves the utilisation of these services. We estimated the percentage of patients with suspected tuberculosis (TB) in whom sputum microscopy was effectively utilised in Peru and Bolivia over two 6-month periods before and after a clinical audit intervention that included standards setting, measuring clinical performance and feedback. Before the intervention, only 31% (95%CI 27-35) of TB suspects were assessed with sputum microscopy in Peru. In Bolivia, 30% (95%CI 25-35) underwent at least two sputum microscopy examinations. After clinical audit, the availability of sputum microscopy results improved by respectively 7% (95%CI 1-12, P < 0.05) and 23% (95%CI 15-30, P < 0.05) over 2 years in Peru and Bolivia. Despite World Health Organization recommendations that all TB suspects should undergo sputum microscopy before treatment, results are available for further assessment for only one third. This is a potentially serious obstacle to TB case detection. Clinical audit can bring some improvement. We recommend regular monitoring of effective utilisation of microscopy services and investigations to ascertain organisational and structural issues in their uptake and use.

Modulation of matrix metalloproteinase activity by EDTA prevents posterior capsular opacification

PubMed Central

Guha, Rajdeep; Jongkey, Geram; Palui, Himangshu; Mishra, Akhilesh; Vemuganti, Geeta K.; Basak, Samar K.; Mandal, Tapan Kumar; Konar, Aditya

2012-01-01

Purpose To evaluate the effect of ethylenediaminetetraacetic acid (EDTA) on posterior capsular opacification (PCO) of rabbits and to assess its effect on intraocular tissues. Methods Modulation of matrix metalloproteinase (MMP) activity in the aqueous following cataract surgery in rabbits and its prevention by different doses of EDTA was determined by zymography. For evaluation of PCO, lensectomized rabbits were intracamerally injected with single dose of either 5 mg EDTA or normal saline. After one month, the degree of PCO was determined by slitlamp biomicroscopy, Miyake-Apple view, and histology of the lens capsule. The effect of EDTA on intra ocular pressure (IOP), corneal endothelial cells, and the retina was evaluated by tonometry, specular microscopy and scanning electron microscopy, and electroretinography. The concentration of EDTA in the aqueous was determined by high performance liquid chromatography (HPLC) at different time points. Results The MMP activity was significantly increased in the aqueous of the operated eyes, and EDTA reduced the degree of increase in a dose-dependent manner. EDTA treatment significantly reduced the degree of PCO (p<0.05). Histopathology of the lens capsule showed a reduction in the number of proliferating and migrating cells as well as MMP2 expression in the EDTA-treated eyes. EDTA treatment did not change the IOP; density, morphology and ultrastructure of the corneal endothelial cells; and electroretinography (ERG). EDTA was detectable in the aqueous humor up to 72 h following a single intracameral injection. Conclusions EDTA reduces the degree of PCO by suppressing the MMP activity and it is not toxic to intra ocular structures at the concentration used. PMID:22815623

Alkylidenediquinocyclopropanes and Diarylcyclopropenes and method for preparation

DOEpatents

West, Robert C.; Beyer, Douglas E.; Komatsu, Koichi

1979-01-01

Alkylidenediquinocyclopropanes and diarylcyclopropenes and the preparation of the former by oxidation of the latter and which are characterized by low energy electronic absorption, pronounced dichroism and characteristic specular reflectance.

Specular Reflection from Rough Surfaces Revisited

NASA Astrophysics Data System (ADS)

Yasuda, Kensei; Kim, Alvin; Cho, Hayley; Timofejev, Timofej; Walecki, Wojciech J.; Klep, James; Edelson, Amy S.; Walecki, Abigail S.; Walecki, Eve S.; Walecki, Peter S.

2016-10-01

In his beautiful paper, Hasan Fakhruddin reported observations of mirror-like reflections in the rough surface of a ground glass plate. Similar effects have been recently employed for metrology of the roughness of optical diffusers used in modern light emitting device illumination systems. We report the observations of specular reflection in nontransparent rough surfaces at oblique angles, where roughness was treated as a variable. We present a simple trigonometry-based model explaining the observed phenomenon, which we experimentally validated using aluminum surfaces that have controlled roughness. The reported demonstration requires no special equipment, other than cellphone cameras, dielectric or metal plate, and sandpaper, and serves as an introduction to wave optics. This activity can be used to get further insight into everyday applications of wave optics for students already familiar with wave optics fundamentals.

Radiant exchange in partially specular architectural environments

NASA Astrophysics Data System (ADS)

Beamer, C. Walter; Muehleisen, Ralph T.

2003-10-01

The radiant exchange method, also known as radiosity, was originally developed for thermal radiative heat transfer applications. Later it was used to model architectural lighting systems, and more recently it has been extended to model acoustic systems. While there are subtle differences in these applications, the basic method is based on solving a system of energy balance equations, and it is best applied to spaces with mainly diffuse reflecting surfaces. The obvious drawback to this method is that it is based around the assumption that all surfaces in the system are diffuse reflectors. Because almost all architectural systems have at least some partially specular reflecting surfaces in the system it is important to extend the radiant exchange method to deal with this type of surface reflection. [Work supported by NSF.

Local surface curvature analysis based on reflection estimation

NASA Astrophysics Data System (ADS)

Lu, Qinglin; Laligant, Olivier; Fauvet, Eric; Zakharova, Anastasia

2015-07-01

In this paper, we propose a novel reflection based method to estimate the local orientation of a specular surface. For a calibrated scene with a fixed light band, the band is reflected by the surface to the image plane of a camera. Then the local geometry between the surface and reflected band is estimated. Firstly, in order to find the relationship relying the object position, the object surface orientation and the band reflection, we study the fundamental theory of the geometry between a specular mirror surface and a band source. Then we extend our approach to the spherical surface with arbitrary curvature. Experiments are conducted with mirror surface and spherical surface. Results show that our method is able to obtain the local surface orientation merely by measuring the displacement and the form of the reflection.

Atmospheric radiation model for water surfaces

NASA Technical Reports Server (NTRS)

Turner, R. E.; Gaskill, D. W.; Lierzer, J. R.

1982-01-01

An atmospheric correction model was extended to account for various atmospheric radiation components in remotely sensed data. Components such as the atmospheric path radiance which results from singly scattered sky radiation specularly reflected by the water surface are considered. A component which is referred to as the virtual Sun path radiance, i.e. the singly scattered path radiance which results from the solar radiation which is specularly reflected by the water surface is also considered. These atmospheric radiation components are coded into a computer program for the analysis of multispectral remote sensor data over the Great Lakes of the United States. The user must know certain parameters, such as the visibility or spectral optical thickness of the atmosphere and the geometry of the sensor with respect to the Sun and the target elements under investigation.

Light transport on path-space manifolds

NASA Astrophysics Data System (ADS)

Jakob, Wenzel Alban

The pervasive use of computer-generated graphics in our society has led to strict demands on their visual realism. Generally, users of rendering software want their images to look, in various ways, "real", which has been a key driving force towards methods that are based on the physics of light transport. Until recently, industrial practice has relied on a different set of methods that had comparatively little rigorous grounding in physics---but within the last decade, advances in rendering methods and computing power have come together to create a sudden and dramatic shift, in which physics-based methods that were formerly thought impractical have become the standard tool. As a consequence, considerable attention is now devoted towards making these methods as robust as possible. In this context, robustness refers to an algorithm's ability to process arbitrary input without large increases of the rendering time or degradation of the output image. One particularly challenging aspect of robustness entails simulating the precise interaction of light with all the materials that comprise the input scene. This dissertation focuses on one specific group of materials that has fundamentally been the most important source of difficulties in this process. Specular materials, such as glass windows, mirrors or smooth coatings (e.g. on finished wood), account for a significant percentage of the objects that surround us every day. It is perhaps surprising, then, that it is not well-understood how they can be accommodated within the theoretical framework that underlies some of the most sophisticated rendering methods available today. Many of these methods operate using a theoretical framework known as path space integration. But this framework makes no provisions for specular materials: to date, it is not clear how to write down a path space integral involving something as simple as a piece of glass. Although implementations can in practice still render these materials by side-stepping limitations of the theory, they often suffer from unusably slow convergence; improvements to this situation have been hampered by the lack of a thorough theoretical understanding. We address these problems by developing a new theory of path-space light transport which, for the first time, cleanly incorporates specular scattering into the standard framework. Most of the results obtained in the analysis of the ideally smooth case can also be generalized to rendering of glossy materials and volumetric scattering so that this dissertation also provides a powerful new set of tools for dealing with them. The basis of our approach is that each specular material interaction locally collapses the dimension of the space of light paths so that all relevant paths lie on a submanifold of path space. We analyze the high-dimensional differential geometry of this submanifold and use the resulting information to construct an algorithm that is able to "walk" around on it using a simple and efficient equation-solving iteration. This manifold walking algorithm then constitutes the key operation of a new type of Markov Chain Monte Carlo (MCMC) rendering method that computes lighting through very general families of paths that can involve arbitrary combinations of specular, near-specular, glossy, and diffuse surface interactions as well as isotropic or highly anisotropic volume scattering. We demonstrate our implementation on a range of challenging scenes and evaluate it against previous methods.

Measurements of ultrasonic backscattered spectral centroid shift from spine in vivo: methodology and preliminary results.

PubMed

Garra, Brian S; Locher, Melanie; Felker, Steven; Wear, Keith A

2009-01-01

Ultrasonic backscatter measurements from vertebral bodies (L3 and L4) in nine women were performed using a clinical ultrasonic imaging system. Measurements were made through the abdomen. The location of a vertebra was identified from the bright specular reflection from the vertebral anterior surface. Backscattered signals were gated to isolate signal emanating from the cancellous interiors of vertebrae. The spectral centroid shift of the backscattered signal, which has previously been shown to correlate highly with bone mineral density (BMD) in human calcaneus in vitro, was measured. BMD was also measured in the nine subjects' vertebrae using a clinical bone densitometer. The correlation coefficient between centroid shift and BMD was r = -0.61. The slope of the linear fit was -160 kHz / (g/cm(2)). The negative slope was expected because the attenuation coefficient (and therefore magnitude of the centroid downshift) is known from previous studies to increase with BMD. The centroid shift may be a useful parameter for characterizing bone in vivo.

Efficient Geometric Sound Propagation Using Visibility Culling

NASA Astrophysics Data System (ADS)

Chandak, Anish

2011-07-01

Simulating propagation of sound can improve the sense of realism in interactive applications such as video games and can lead to better designs in engineering applications such as architectural acoustics. In this thesis, we present geometric sound propagation techniques which are faster than prior methods and map well to upcoming parallel multi-core CPUs. We model specular reflections by using the image-source method and model finite-edge diffraction by using the well-known Biot-Tolstoy-Medwin (BTM) model. We accelerate the computation of specular reflections by applying novel visibility algorithms, FastV and AD-Frustum, which compute visibility from a point. We accelerate finite-edge diffraction modeling by applying a novel visibility algorithm which computes visibility from a region. Our visibility algorithms are based on frustum tracing and exploit recent advances in fast ray-hierarchy intersections, data-parallel computations, and scalable, multi-core algorithms. The AD-Frustum algorithm adapts its computation to the scene complexity and allows small errors in computing specular reflection paths for higher computational efficiency. FastV and our visibility algorithm from a region are general, object-space, conservative visibility algorithms that together significantly reduce the number of image sources compared to other techniques while preserving the same accuracy. Our geometric propagation algorithms are an order of magnitude faster than prior approaches for modeling specular reflections and two to ten times faster for modeling finite-edge diffraction. Our algorithms are interactive, scale almost linearly on multi-core CPUs, and can handle large, complex, and dynamic scenes. We also compare the accuracy of our sound propagation algorithms with other methods. Once sound propagation is performed, it is desirable to listen to the propagated sound in interactive and engineering applications. We can generate smooth, artifact-free output audio signals by applying efficient audio-processing algorithms. We also present the first efficient audio-processing algorithm for scenarios with simultaneously moving source and moving receiver (MS-MR) which incurs less than 25% overhead compared to static source and moving receiver (SS-MR) or moving source and static receiver (MS-SR) scenario.

Auditing the use and assessing the clinical utility of microscopy as a point-of-care test for Neisseria gonorrhoeae in a Sexual Health clinic.

PubMed

Mensforth, Sarah; Thorley, Nicola; Radcliffe, Keith

2018-02-01

We assessed whether urethral microscopy was performed as per clinic protocol for male clinic attendees reporting contact with Neisseria gonorrhoeae (GC), urethral symptoms or given a diagnosis of epididymo-orchitis (EO) over a 12-month period (9732 patients). Prevalence of gonorrhoea in the contacts, urethral symptoms and EO groups was 50, 12.7 and 1.6%, respectively. Microscopy was performed reliably for contacts (96%), those with discharge/dysuria with evidence of urethritis on examination (98%), but not those with EO (43%). We explored the clinical utility of microscopy as a point-of-care test for identifying urethral GC in each subgroup, using the APTIMA Combo 2 CT/GC nucleic acid amplification test as the comparator (1710 patients). Sensitivity of microscopy for each subgroup was good; there was no statistical difference between subgroup sensitivity using Fisher's exact test. Microscopy is valuable to ensure prompt diagnosis and contact tracing. All GC contacts were treated 'epidemiologically'; however, half of GC contacts did not have GC. Microscopy identified the majority of GC cases, including amongst contacts (71% of heterosexual contacts, 66% of contacts reporting sex with men). We propose that epidemiological treatment for GC contacts should be reconsidered on the grounds of antibiotic stewardship, favouring use of microscopy to guide treatment decisions.

Clinical usefulness of reflectance confocal microscopy in the management of facial lentigo maligna melanoma.

PubMed

Alarcón, I; Carrera, C; Puig, S; Malvehy, J

2014-04-01

Facial lentigo maligna melanoma can be a diagnostic challenge in daily clinical practice as it has similar clinical and morphological features to other lesions such as solar lentigines and pigmented actinic keratoses. Confocal microscopy is a noninvasive technique that provides real-time images of the epidermis and superficial dermis with cellular-level resolution. We describe 3 cases of suspected facial lentigo maligna that were assessed using dermoscopy and confocal microscopy before histopathology study. In the first case, diagnosed as lentigo maligna melanoma, presurgical mapping by confocal microscopy was performed to define the margins more accurately. In the second and third cases, with a clinical and dermoscopic suspicion of lentigo maligna melanoma, confocal microscopy was used to identify the optimal site for biopsy. Copyright © 2012 Elsevier España, S.L. and AEDV. All rights reserved.

Millimeter wave absorption in the nonhuman primate eye at 35 GHz and 94 GHz.

PubMed

Chalfin, Steven; D'Andrea, John A; Comeau, Paul D; Belt, Michael E; Hatcher, Donald J

2002-07-01

The purpose of this study was to evaluate anterior segment bioeffects of pulsed 35 GHz and 94 GHz microwave exposure in the nonhuman primate eye. Five juvenile rhesus monkeys (Macaca mulatta) underwent baseline anterior segment ocular assessment consisting of slit lamp examination, corneal topography, specular microscopy, and pachymetry. These studies were repeated after exposure of one eye to pulsed 35 GHz or 94 GHz microwaves at varied fluences, with the other eye serving as a control. The mean fluence required to produce a threshold corneal lesion (faint epithelial edema and fluorescein staining) was 7.5 J cm(-2) at 35 GHz and 5 J cm(-2) at 94 GHz. Transient changes in corneal topography and pachymetry were noted at these fluences. Endothelial cell counts remained unchanged. Threshold corneal injury from 35 GHz and 94 GHz microwave exposure is produced at fluences below those previously reported for CO2 laser radiation. These data may help elucidate the mechanism of thermal injury to the cornea, and resolve discrepancies between IEEE C95.1 (1999), NCRP (1986), and ICNIRP (1998) safety standards for exposure to non-ionizing radiation at millimeter wavelengths.

Towards plasma cleaning of ITER first mirrors

NASA Astrophysics Data System (ADS)

Moser, L.; Marot, L.; Eren, B.; Steiner, R.; Mathys, D.; Leipold, F.; Reichle, R.; Meyer, E.

2015-06-01

To avoid reflectivity losses in ITER's optical diagnostic systems, on-site cleaning of metallic first mirrors via plasma sputtering is foreseen to remove deposit build-ups migrating from the main wall. In this work, the influence of aluminium and tungsten deposits on the reflectivity of molybdenum mirrors as well as the possibility to clean them with plasma exposure is investigated. Porous ITER-like deposits are grown to mimic the edge conditions expected in ITER, and a severe degradation in the specular reflectivity is observed as these deposits build up on the mirror surface. In addition, dense oxide films are produced for comparisons with porous films. The composition, morphology and crystal structure of several films were characterized by means of scanning electron microscopy, x-ray photoelectron spectroscopy, x-ray diffraction and secondary ion mass spectrometry. The cleaning of the deposits and the restoration of the mirrors' optical properties are possible either with a Kaufman source or radio frequency directly applied to the mirror (or radio frequency plasma generated directly around the mirror surface). Accelerating ions of an external plasma source through a direct current applied onto the mirror does not remove deposits composed of oxides. A possible implementation of plasma cleaning in ITER is addressed.

Gloss as an aspect of the measurement of appearance.

PubMed

Ji, Wei; Pointer, Mike R; Luo, Ronnier M; Dakin, John

2006-01-01

The perception and measurement of gloss is just one part of the concept of appearance measurement. We describe the comparison between data derived by 20 observers who each scaled the perceived gloss of a set of 84 neutral and colored test samples and measurements of those samples made using a glossmeter and a sphere-based spectrophotometer. With a glossmeter, the relationship between the visual-scaled data and the measured gloss values could be described by a three-part linear fit or, with a higher correlation, a cubic function. For the sphere-based spectrophotometer, the difference in the luminance factor, deltaY, between specular-included and specular-excluded measurements, was found to give a better linear correlation with the observer-scaled data. The color of the samples did not appear to significantly change the perceived gloss of the surface.

Gloss as an aspect of the measurement of appearance

NASA Astrophysics Data System (ADS)

Ji, Wei; Pointer, Mike R.; Luo, Ronnier M.; Dakin, John

2006-01-01

The perception and measurement of gloss is just one part of the concept of appearance measurement. We describe the comparison between data derived by 20 observers who each scaled the perceived gloss of a set of 84 neutral and colored test samples and measurements of those samples made using a glossmeter and a sphere-based spectrophotometer. With a glossmeter, the relationship between the visual-scaled data and the measured gloss values could be described by a three-part linear fit or, with a higher correlation, a cubic function. For the sphere-based spectrophotometer, the difference in the luminance factor, DeltaY, between specular-included and specular-excluded measurements, was found to give a better linear correlation with the observer-scaled data. The color of the samples did not appear to significantly change the perceived gloss of the surface.

A radiometric model of an earth radiation budget radiometer optical system with diffuse-specular surfaces

NASA Technical Reports Server (NTRS)

Luther, M. R.

1981-01-01

The Earth Radiation Budget Experiment (ERBE) is to fly on NASA's Earth Radiation Budget Satellite (ERBS) and on NOAA F and NOAA G. Large spatial scale earth energy budget data will be derived primarily from measurements made by the ERBE nonscanning instrument (ERBE-NS). A description is given of a mathematical model capable of simulating the radiometric response of any of the ERBE-NS earth viewing channels. The model uses a Monte Carlo method to accurately account for directional distributions of emission and reflection from optical surfaces which are neither strictly diffuse nor strictly specular. The model computes radiation exchange factors among optical system components, and determines the distribution in the optical system of energy from an outside source. Attention is also given to an approach for implementing the model and results obtained from the implementation.

Polarization-based and specular-reflection-based noncontact latent fingerprint imaging and lifting

NASA Astrophysics Data System (ADS)

Lin, Shih-Schön; Yemelyanov, Konstantin M.; Pugh, Edward N., Jr.; Engheta, Nader

2006-09-01

In forensic science the finger marks left unintentionally by people at a crime scene are referred to as latent fingerprints. Most existing techniques to detect and lift latent fingerprints require application of a certain material directly onto the exhibit. The chemical and physical processing applied to the fingerprint potentially degrades or prevents further forensic testing on the same evidence sample. Many existing methods also have deleterious side effects. We introduce a method to detect and extract latent fingerprint images without applying any powder or chemicals on the object. Our method is based on the optical phenomena of polarization and specular reflection together with the physiology of fingerprint formation. The recovered image quality is comparable to existing methods. In some cases, such as the sticky side of tape, our method shows unique advantages.

Bright color optical switching device by polymer network liquid crystal with a specular reflector.

PubMed

Lee, Gae Hwang; Hwang, Kyu Young; Jang, Jae Eun; Jin, Yong Wan; Lee, Sang Yoon; Jung, Jae Eun

2011-07-04

The color optical switching device by polymer network liquid crystal (PNLC) with color filter on a specular reflector shows excellent performance; white reflectance of 22%, color gamut of 32%, and contrast ratio up to 50:1 in reflective mode measurement. The view-angle dependence of the reflectance can be adjusted by changing the PNLC thickness. The color chromaticity shown by the device is close to the limit value of color filters, and its value nearly remains with respect to the operating voltage. These optical properties of the device can be explained from the prediction based on multiple interactions between the light and the droplets of liquid crystal. The high reflectance, vivid color image, and moderate responds time allow the PNLC device to drive good color moving image. It can widely extend the applications of the reflective device.

When beauty is only skin deep; optimizing the sensitivity of specular neutron reflectivity for probing structure beneath the surface of thin filmsa)

NASA Astrophysics Data System (ADS)

Majkrzak, Charles F.; Carpenter, Elisabeth; Heinrich, Frank; Berk, Norman F.

2011-11-01

Specular neutron reflectometry has become an established probe of the nanometer scale structure of materials in thin film and multilayered form. It has contributed especially to our understanding of soft condensed matter of interest in polymer science, organic chemistry, and biology and of magnetic hard condensed matter systems. In this paper we examine a number of key factors which have emerged that can limit the sensitivity of neutron reflection as such a probe. Among these is loss of phase information, and we discuss how knowledge about material surrounding a film of interest can be applied to help resolve the problem. In this context we also consider what role the quantum phenomenon of interaction-free measurement might play in enhancing the statistical efficiency for obtaining reflectivity or transmission data.

Cassini/VIMS observes rough surfaces on Titan's Punga Mare in specular reflection.

PubMed

Barnes, Jason W; Sotin, Christophe; Soderblom, Jason M; Brown, Robert H; Hayes, Alexander G; Donelan, Mark; Rodriguez, Sebastien; Mouélic, Stéphane Le; Baines, Kevin H; McCord, Thomas B

Cassini /VIMS high-phase specular observations of Titan's north pole during the T85 flyby show evidence for isolated patches of rough liquid surface within the boundaries of the sea Punga Mare. The roughness shows typical slopes of 6°±1°. These rough areas could be either wet mudflats or a wavy sea. Because of their large areal extent, patchy geographic distribution, and uniform appearance at low phase, we prefer a waves interpretation. Applying theoretical wave calculations based on Titan conditions our slope determination allows us to infer winds of 0.76±0.09 m/s and significant wave heights of [Formula: see text] cm at the time and locations of the observation. If correct, these would represent the first waves seen on Titan's seas, and also the first extraterrestrial sea-surface waves in general.

Study of the adsorbed layer on a solid electrode surface by specular reflection measurement

NASA Astrophysics Data System (ADS)

Kusu, Fumiyo; Takamura, Kiyoko

1985-07-01

Specular reflection measurements were carried out to study the adsorbed layers of certain heterocyclic compounds such as adenine, barbital, 2'-deoxyadenosine, phenobarbital, pyridine and thymine. When pyridine was present in 0.1M NaClO 4, a marked decrease in the reflectivity of a gold electrode was observed. In the potential range near the point of zero charge on the reflectivity-potential curve, the decrease was due to the adsorption of pyridine. Assuming the reflectivity change to be proportional to the surface coverage, the potential and concentration dependence of pyridine adsorption was determined and analysed on the basis of a Langmuir-type adsorption isotherm. The refractive indices and extinction coefficients for the adsorbed layers of the compounds investigated were evaluated using the observed reflectivity change, according to relations proposed by McIntyre and Aspnes.

Photometric variability in earthshine observations.

PubMed

Langford, Sally V; Wyithe, J Stuart B; Turner, Edwin L

2009-04-01

The identification of an extrasolar planet as Earth-like will depend on the detection of atmospheric signatures or surface non-uniformities. In this paper we present spatially unresolved flux light curves of Earth for the purpose of studying a prototype extrasolar terrestrial planet. Our monitoring of the photometric variability of earthshine revealed changes of up to 23% per hour in the brightness of Earth's scattered light at around 600 nm, due to the removal of specular reflection from the view of the Moon. This variability is accompanied by reddening of the spectrum and results from a change in surface properties across the continental boundary between the Indian Ocean and Africa's east coast. Our results based on earthshine monitoring indicate that specular reflection should provide a useful tool in determining the presence of liquid water on extrasolar planets via photometric observations.

Spectral data of specular reflectance, narrow-angle transmittance and angle-resolved surface scattering of materials for solar concentrators.

PubMed

Good, Philipp; Cooper, Thomas; Querci, Marco; Wiik, Nicolay; Ambrosetti, Gianluca; Steinfeld, Aldo

2016-03-01

The spectral specular reflectance of conventional and novel reflective materials for solar concentrators is measured with an acceptance angle of 17.5 mrad over the wavelength range 300-2500 nm at incidence angles 15-60° using a spectroscopic goniometry system. The same experimental setup is used to determine the spectral narrow-angle transmittance of semi-transparent materials for solar collector covers at incidence angles 0-60°. In addition, the angle-resolved surface scattering of reflective materials is recorded by an area-scan CCD detector over the spectral range 350-1050 nm. A comprehensive summary, discussion, and interpretation of the results are included in the associated research article "Spectral reflectance, transmittance, and angular scattering of materials for solar concentrators" in Solar Energy Materials and Solar Cells.

Detection of reflecting surfaces by a statistical model

NASA Astrophysics Data System (ADS)

He, Qiang; Chu, Chee-Hung H.

2009-02-01

Remote sensing is widely used assess the destruction from natural disasters and to plan relief and recovery operations. How to automatically extract useful features and segment interesting objects from digital images, including remote sensing imagery, becomes a critical task for image understanding. Unfortunately, current research on automated feature extraction is ignorant of contextual information. As a result, the fidelity of populating attributes corresponding to interesting features and objects cannot be satisfied. In this paper, we present an exploration on meaningful object extraction integrating reflecting surfaces. Detection of specular reflecting surfaces can be useful in target identification and then can be applied to environmental monitoring, disaster prediction and analysis, military, and counter-terrorism. Our method is based on a statistical model to capture the statistical properties of specular reflecting surfaces. And then the reflecting surfaces are detected through cluster analysis.

Resonant nuclear scattering of synchrotron radiation: Detector development and specular scattering from a thin layer of {sup 57}Fe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baron, A.Q.R.

1995-04-01

This thesis explores resonant nudear scattering of synchrotron radiation. An introductory chapter describes some useful concepts, such as speedup and coherent enhancement, in the context of some basic physical principles. Methods of producing highly monochromatic synchrotron beams usmg either electronic or nuclear scattering are also discussed. The body of the thesis concentrates on detector development and specular scattering from iynthetic layered materials. A detector employing n-dcrochannel plate electron multipliers is shown to have good ({approximately}50%) effidency for detecting 14.4 key x-rays incident at small ({approximately}0.5 degree) grazing angles onto Au or CsI photocathodes. However, being complicated to use, it wasmore » replaced with a large area (>=lan2) avalanche photodiode (APD) detector. The APD`s are simpler to use and have comparable (30--70%) efficiencies at 14.4 key, subnanosecond time resolution, large dynan-dc range (usable at rates up to {approximately}10{sup 8} photons/second) and low (<{approximately}0.01 cts/sec) background rates. Maxwell`s equations are used to derive the specular x-ray reflectivity of layered materials with resonant transitions and complex polarization dependencies. The effects of interfadal roughness are treated with some care, and the distorted wave Born approximation (DWBA) used to describe electronic scattering is generalized to the nuclear case. The implications of the theory are discussed in the context of grazing incidence measurements with emphasis on the kinematic and dynamical aspects of the scattering.« less

Multiple View Zenith Angle Observations of Reflectance From Ponderosa Pine Stands

NASA Technical Reports Server (NTRS)

Johnson, Lee F.; Lawless, James G. (Technical Monitor)

1994-01-01

Reflectance factors (RF(lambda)) from dense and sparse ponderosa pine (Pinus ponderosa) stands, derived from radiance data collected in the solar principal plane by the Advanced Solid-State Array Spectro-radiometer (ASAS), were examined as a function of view zenith angle (theta(sub v)). RF(lambda) was maximized with theta(sub v) nearest the solar retrodirection, and minimized near the specular direction throughout the ASAS spectral region. The dense stand had much higher RF anisotropy (ma)dmurn RF is minimum RF) in the red region than did the sparse stand (relative differences of 5.3 vs. 2.75, respectively), as a function of theta(sub v), due to the shadow component in the canopy. Anisotropy in the near-infrared (NIR) was more similar between the two stands (2.5 in the dense stand and 2.25 in the sparse stand); the dense stand exhibited a greater hotspot effect than 20 the sparse stand in this spectral region. Two common vegetation transforms, the NIR/red ratio and the normalized difference vegetation index (NDVI), both showed a theta(sub v) dependence for the dense stand. Minimum values occurred near the retrodirection and maximum values occurred near the specular direction. Greater relative differences were noted for the NIR/red ratio (2.1) than for the NDVI (1.3). The sparse stand showed no obvious dependence on theta(sub v) for either transform, except for slightly elevated values toward the specular direction.

Electromagnetic wave scattering from rough terrain

NASA Astrophysics Data System (ADS)

Papa, R. J.; Lennon, J. F.; Taylor, R. L.

1980-09-01

This report presents two aspects of a program designed to calculate electromagnetic scattering from rough terrain: (1) the use of statistical estimation techniques to determine topographic parameters and (2) the results of a single-roughness-scale scattering calculation based on those parameters, including comparison with experimental data. In the statistical part of the present calculation, digitized topographic maps are used to generate data bases for the required scattering cells. The application of estimation theory to the data leads to the specification of statistical parameters for each cell. The estimated parameters are then used in a hypothesis test to decide on a probability density function (PDF) that represents the height distribution in the cell. Initially, the formulation uses a single observation of the multivariate data. A subsequent approach involves multiple observations of the heights on a bivariate basis, and further refinements are being considered. The electromagnetic scattering analysis, the second topic, calculates the amount of specular and diffuse multipath power reaching a monopulse receiver from a pulsed beacon positioned over a rough Earth. The program allows for spatial inhomogeneities and multiple specular reflection points. The analysis of shadowing by the rough surface has been extended to the case where the surface heights are distributed exponentially. The calculated loss of boresight pointing accuracy attributable to diffuse multipath is then compared with the experimental results. The extent of the specular region, the use of localized height variations, and the effect of the azimuthal variation in power pattern are all assessed.

A Novel Active Imaging Model to Design Visual Systems: A Case of Inspection System for Specular Surfaces

PubMed Central

Azorin-Lopez, Jorge; Fuster-Guillo, Andres; Saval-Calvo, Marcelo; Mora-Mora, Higinio; Garcia-Chamizo, Juan Manuel

2017-01-01

The use of visual information is a very well known input from different kinds of sensors. However, most of the perception problems are individually modeled and tackled. It is necessary to provide a general imaging model that allows us to parametrize different input systems as well as their problems and possible solutions. In this paper, we present an active vision model considering the imaging system as a whole (including camera, lighting system, object to be perceived) in order to propose solutions to automated visual systems that present problems that we perceive. As a concrete case study, we instantiate the model in a real application and still challenging problem: automated visual inspection. It is one of the most used quality control systems to detect defects on manufactured objects. However, it presents problems for specular products. We model these perception problems taking into account environmental conditions and camera parameters that allow a system to properly perceive the specific object characteristics to determine defects on surfaces. The validation of the model has been carried out using simulations providing an efficient way to perform a large set of tests (different environment conditions and camera parameters) as a previous step of experimentation in real manufacturing environments, which more complex in terms of instrumentation and more expensive. Results prove the success of the model application adjusting scale, viewpoint and lighting conditions to detect structural and color defects on specular surfaces. PMID:28640211

A satellite constellation optimization for a regional GNSS remote sensing mission

NASA Astrophysics Data System (ADS)

Gavili Kilaneh, Narin; Mashhadi Hossainali, Masoud

2017-04-01

Due to the recent advances in the Global Navigation Satellite System Remote sensing (GNSS¬R) applications, optimization of a satellite orbit to investigate the Earth's properties seems significant. The comparison of the GNSS direct and reflected signals received by a Low Earth Orbit (LEO) satellite introduces a new technique to remotely sense the Earth. Several GNSS¬R missions including Cyclone Global Navigation Satellite System (CYGNSS) have been proposed for different applications such as the ocean wind speed and height monitoring. The geometric optimization of the satellite orbit before starting the mission is a key step for every space mission. Since satellite constellation design varies depending on the application, we have focused on the required geometric criteria for oceanography applications in a specified region. Here, the total number of specular points, their spatial distribution and the accuracy of their position are assumed to be sufficient for oceanography applications. Gleason's method is used to determine the position of specular points. We considered the 2-D lattice and 3-D lattice theory of flower constellation to survey whether a circular orbit or an elliptical one is suitable to improve the solution. Genetic algorithm is implemented to solve the problem. To check the visibility condition between the LEO and GPS satellites, the satellite initial state is propagated by a variable step size numerical integration method. Constellation orbit parameters achieved by optimization provide a better resolution and precession for the specular points in the study area of this research.

Polarization of Light by Leaves and Plant Canopies

NASA Technical Reports Server (NTRS)

Vanderbilt, V. C.

2006-01-01

This talk will focus first on the information contained in the surface-scattered light from leaves, plant canopies and surface waters. This light is in general polarized and depends upon surface roughness. Thus, for example, - The surface reflection from shiny green leaves measured in the specular direction shows no chlorophyll absorption bands, no 'red edge.' - Conversely, the degree of linear polarization of such light displays marked variation with wavelength having local maxima in the chlorophyll absorption bands and an inverted red edge. - Plant canopies with shiny leaves distributed in angle like the area on a sphere, specularly reflect sunlight in the subsolar or specular direction- but also in every other view direction. - Canopies of green plants may appear white not green when viewed obliquely toward the sun. - In a light to moderate wind, the often blindingly bright glitter of sunlight off smooth water surfaces provides a strong, angularly narrow signature reflection characteristic of inundated vegetated areas that are big sources of atmospheric methane, a climatically important greenhouse gas. (Conversely, a blindingly bright glitter-type reflection is uncharacteristic of upland or wind ruffled open water areas that are poor sources of atmospheric methane.) Because some of these results may be 'head scratchers,' it's always important to properly calibrate ones instruments. Indeed, as the second portion of the talk will show, the characteristics of the light measuring instrument, particularly its entrance aperture, may affect the results and should be taken into account during across-instrument data comparisons.

Topography reconstruction of specular surfaces

NASA Astrophysics Data System (ADS)

Kammel, Soren; Horbach, Jan

2005-01-01

Specular surfaces are used in a wide variety of industrial and consumer products like varnished or chrome plated parts of car bodies, dies, molds or optical components. Shape deviations of these products usually reduce their quality regarding visual appearance and/or technical performance. One reliable method to inspect such surfaces is deflectometry. It can be employed to obtain highly accurate values representing the local curvature of the surfaces. In a deflectometric measuring system, a series of illumination patterns is reflected at the specular surface and is observed by a camera. The distortions of the patterns in the acquired images contain information about the shape of the surface. This information is suited for the detection and measurement of surface defects like bumps, dents and waviness with depths in the range of a few microns. However, without additional information about the distances between the camera and each observed surface point, a shape reconstruction is only possible in some special cases. Therefore, the reconstruction approach described in this paper uses data observed from at least two different camera positions. The data obtained is used separately to estimate the local surface curvature for each camera position. From the curvature values, the epipolar geometry for the different camera positions is recovered. Matching the curvature values along the epipolar lines yields an estimate of the 3d position of the corresponding surface points. With this additional information, the deflectometric gradient data can be integrated to represent the surface topography.

The performance and clinical utility of cervical microscopy for the diagnosis of gonorrhoea in women in the era of the NAAT.

PubMed

Thorley, Nicola; Radcliffe, Keith

2015-08-01

We evaluated the performance and clinical utility of cervical microscopy for diagnosing genital gonorrhoea (GC) in women, using the APTIMA Combo 2 dual GC/Chlamydia trachomatis assay as the gold standard. Test performance was assessed overall and for patient subgroups (symptomatic, GC contacts, pelvic inflammatory disease [PID] diagnosis). It was found that 93 women had positive GC genital NAAT results; 15 had positive cervical microscopy (8 were GC contacts). In all subgroups except GC contacts, the PPV of cervical microscopy was below the nationally accepted target of 90%. Compared to APTIMA Combo 2, cervical microscopy has poor sensitivity for diagnosing GC in women (16.1% overall, 17.3% symptomatic, 25% GC contacts, 10.5% PID). GC contacts accounted for over 50% of the positive microscopy results and would have received epidemiological treatment for GC, regardless of the microscopy result. Discontinuing the routine use of cervical microscopy would improve patient flow through the sexual health clinic and resources could be utilised more effectively. © The Author(s) 2014.

Specular reflectivity and hot-electron generation in high-contrast relativistic laser-plasma interactions

NASA Astrophysics Data System (ADS)

Kemp, Gregory Elijah

Ultra-intense laser (> 1018 W/cm2) interactions with matter are capable of producing relativistic electrons which have a variety of applications in state-of-the-art scientific and medical research conducted at universities and national laboratories across the world. Control of various aspects of these hot-electron distributions is highly desired to optimize a particular outcome. Hot-electron generation in low-contrast interactions, where significant amounts of under-dense pre-plasma are present, can be plagued by highly non-linear relativistic laser-plasma instabilities and quasi-static magnetic field generation, often resulting in less than desirable and predictable electron source characteristics. High-contrast interactions offer more controlled interactions but often at the cost of overall lower coupling and increased sensitivity to initial target conditions. An experiment studying the differences in hot-electron generation between high and low-contrast pulse interactions with solid density targets was performed on the Titan laser platform at the Jupiter Laser Facility at Lawrence Livermore National Laboratory in Livermore, CA. To date, these hot-electrons generated in the laboratory are not directly observable at the source of the interaction. Instead, indirect studies are performed using state-of-the-art simulations, constrained by the various experimental measurements. These measurements, more-often-than-not, rely on secondary processes generated by the transport of these electrons through the solid density materials which can susceptible to a variety instabilities and target material/geometry effects. Although often neglected in these types of studies, the specularly reflected light can provide invaluable insight as it is directly influenced by the interaction. In this thesis, I address the use of (personally obtained) experimental specular reflectivity measurements to indirectly study hot-electron generation in the context of high-contrast, relativistic laser-plasma interactions. Spatial, temporal and spectral properties of the incident and specular pulses, both near and far away from the interaction region where experimental measurements are obtained, are used to benchmark simulations designed to infer dominant hot-electron acceleration mechanisms and their corresponding energy/angular distributions. To handle this highly coupled interaction, I employed particle-in-cell modeling using a wide variety of algorithms (verified to be numerically stable and consistent with analytic expressions) and physical models (validated by experimental results) to reasonably model the interaction's sweeping range of plasma densities, temporal and spatial scales, electromagnetic wave propagation and its interaction with solid density matter. Due to the fluctuations in the experimental conditions and limited computational resources, only a limited number of full-scale simulations were performed under typical experimental conditions to infer the relevant physical phenomena in the interactions. I show the usefulness of the often overlooked specular reflectivity measurements in constraining both high and low-contrast simulations, as well as limitations of their experimental interpretations. Using these experimental measurements to reasonably constrain the simulation results, I discuss the sensitivity of relativistic electron generation in ultra-intense laser plasma interactions to initial target conditions and the dynamic evolution of the interaction region.

Evaluating Malaria Prevalence Using Clinical Diagnosis Compared with Microscopy and Rapid Diagnostic Tests in a Tertiary Healthcare Facility in Rivers State, Nigeria.

PubMed

Wogu, M N; Nduka, F O

2018-01-01

The World Health Organization's policy on laboratory test of all suspected malaria cases before treatment has not yielded significant effects in several rural areas of Sub-Saharan Africa due to inadequate diagnostic infrastructure, leading to high morbidity and mortality rates. A cross-sectional randomized study was conducted to evaluate the validity of clinical malaria diagnosis through comparison with microscopy and rapid diagnostic test kits (RDTs) using 1000 consenting outpatients of a tertiary hospital in Nigeria. Physicians conducted clinical diagnosis, and blood samples were collected through venous procedure and analyzed for malaria parasites using Giemsa microscopy and RDT kits. Microscopy was considered the diagnostic "gold standard" and all data obtained were statistically analyzed using Chi-square test with a P value <0.05 considered significant. Malaria prevalence values of 20.1%, 43.1%, and 29.7% were obtained for clinical diagnosis, microscopy, and RDTs, respectively ( P < 0.05). Values of 47.2%, 95.9%, and 77.8% were obtained for sensitivity, specificity, and diagnostic accuracy, respectively, in clinical diagnosis, while RDTs had sensitivity, specificity, and diagnostic accuracy values of 73.7%, 97.3%, and 88.3%, respectively, when compared to microscopy ( P < 0.05). Clinical diagnosed malaria cases should be confirmed with a parasite-based laboratory diagnosis and more qualitative research is needed to explore why clinicians still use clinical diagnosis despite reported cases of its ineffectiveness.

Distribution of escaping ions produced by non-specular reflection at the stationary quasi-perpendicular shock front

NASA Astrophysics Data System (ADS)

Gedalin, M.; Liverts, M.; Balikhin, M. A.

2008-05-01

Field-aligned and gyrophase bunched ion beams are observed in the foreshock of the Earth bow shock. One of the mechanisms proposed for their production is non-specular reflection at the shock front. We study the distributions which are formed at the stationary quasi-perpendicular shock front within the same process which is responsible for the generation of reflected ions and transmitted gyrating ions. The test particle motion analysis in a model shock allows one to identify the parameters which control the efficiency of the process and the features of the escaping ion distribution. These parameters are: the angle between the shock normal and the upstream magnetic field, the ratio of the ion thermal velocity to the flow velocity upstream, and the cross-shock potential. A typical distribution of escaping ions exhibits a bimodal pitch angle distribution (in the plasma rest frame).

Dual frequency scatterometer measurement of ocean wave height

NASA Technical Reports Server (NTRS)

Johnson, J. W.; Jones, W. L.; Swift, C. T.; Grantham, W. L.; Weissman, D. E.

1975-01-01

A technique for remotely measuring wave height averaged over an area of the sea surface was developed and verified with a series of aircraft flight experiments. The measurement concept involves the cross correlation of the amplitude fluctuations of two monochromatic reflected signals with variable frequency separation. The signal reflected by the randomly distributed specular points on the surface is observed in the backscatter direction at nadir incidence angle. The measured correlation coefficient is equal to the square of the magnitude of the characteristic function of the specular point height from which RMS wave height can be determined. The flight scatterometer operates at 13.9 GHz and 13.9 - delta f GHz with a maximum delta f of 40 MHz. Measurements were conducted for low and moderate sea states at altitudes of 2, 5, and 10 thousand feet. The experimental results agree with the predicted decorrelation with frequency separation and with off-nadir incidence angle.

Design of a tubular skylight system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chao, B.L.

1996-10-01

Since its introduction to the US market in 1991, tubular skylight provides a solution to the problem of lighting up dark corners in a house. Over the years, design of similar products has emphasized on quantity alone and attention to a range of other equally important issues: efficient collecting system, selection of higher specular reflectance material, seals, distribution and quality of light, was not noted. In this paper, the fundamental design concept of an efficient tubular skylight and the possibility of collimating diffuse light is reviewed. The importance of specular reflectance of the tube material on the performance of tubularmore » skylight is demonstrated. Visual appearance (quality) of transmitted light down the tube is related in part to the yellowness index of various materials. Discussion of adequacy of current building and energy code requirements on tubular skylights is briefly touched on and energy simulation results based on a numerical code are presented.« less

Exchange coupling and NOL magnetism consideration in Co 1-xFe x specular spin-valves

NASA Astrophysics Data System (ADS)

Doi, M.; Izumi, M.; Abe, Y.; Fukuzawa, H.; Fuke, H. N.; Iwasaki, H.; Sahashi, M.

2005-02-01

To confirm the origin of the exchange coupling through the nano-oxide layer (NOL), the detailed analyses of the magnetization curve and the temperature dependence on magnetization for the Co1-xFex-NOL samples with various oxidation processes are investigated. The field cooling effect is observed for NOL-inserted samples, which suggests the existence of the antiferromagnetic (AFM) component in the NOL. The characteristic temperature (blocking temperature) increases with increase in the Fe content for Co1-xFex(x=0.08,0.17,0.26)-NOL. These results support that NOL pinning appears higher than room temperature. Further, the twisted coupling through the NOL observed for the Co0.50Fe0.50-NOL is discussed from the viewpoint of the magnetic roughness due to the ferrimagnetic nature of the very thin NOL in specular spin valve (SPSV).

Magnetoresistance enhancement in specular, bottom-pinned, Mn83Ir17 spin valves with nano-oxide layers

NASA Astrophysics Data System (ADS)

Veloso, A.; Freitas, P. P.; Wei, P.; Barradas, N. P.; Soares, J. C.; Almeida, B.; Sousa, J. B.

2000-08-01

Bottom-pinned Mn83Ir17 spin valves with enhanced specular scattering were fabricated, showing magnetoresistance (MR) values up to 13.6%, lower sheet resistance R□ and higher ΔR□. Two nano-oxide layers (NOL) are grown on both sides of the CoFe/Cu/CoFe spin valve structure by natural oxidation or remote plasma oxidation of the starting CoFe layer. Maximum MR enhancement is obtained after just 1 min plasma oxidation. Rutherford backscattering analysis shows that a 15±2 Å oxide layer grows at the expense of the initial (prior to oxidation) CoFe layer, with ˜12% reduction of the initial 40 Å CoFe thickness. X-ray reflectometry indicates that Kiessig fringes become better defined after NOL growth, indicating smoother inner interfaces, in agreement with the observed decrease of the spin valve ferromagnetic Néel coupling.

Combination of acoustical radiosity and the image source method.

PubMed

Koutsouris, Georgios I; Brunskog, Jonas; Jeong, Cheol-Ho; Jacobsen, Finn

2013-06-01

A combined model for room acoustic predictions is developed, aiming to treat both diffuse and specular reflections in a unified way. Two established methods are incorporated: acoustical radiosity, accounting for the diffuse part, and the image source method, accounting for the specular part. The model is based on conservation of acoustical energy. Losses are taken into account by the energy absorption coefficient, and the diffuse reflections are controlled via the scattering coefficient, which defines the portion of energy that has been diffusely reflected. The way the model is formulated allows for a dynamic control of the image source production, so that no fixed maximum reflection order is required. The model is optimized for energy impulse response predictions in arbitrary polyhedral rooms. The predictions are validated by comparison with published measured data for a real music studio hall. The proposed model turns out to be promising for acoustic predictions providing a high level of detail and accuracy.

Surface periodicity of Ir(110) from time-of-flight scattering and recoiling spectrometry (TOF-SARS)

NASA Astrophysics Data System (ADS)

Bu, H.; Shi, M.; Rabalais, J. W.

1991-03-01

The surface periodicity of the Ir(110) surface in both the clean reconstructed (1×3) and oxygen stabilized unreconstructed (1×1) phases have been investigated using time-of-flight scattering and recoiling spectrometry (TOF-SARS). A pulsed 4 keV Ar + ion beam is directed at a grazing incident angle to the surface and the scattered neutral plus ion flux is monitored as a function of beam exit angle and crystal azimuthal angle. It is demonstrated that either maxima or minima are obtained in the scattered flux along the low-index crystallographic directions depending on whether near-specular or off-specular scattering conditions, respectively, are used. These scattering intensity patterns as a function of crystal azimuthal angle provide a direct measure of the surface periodicity. These intensity variations are explained in terms of the Lindhard critical angle, semichannel focusing effects, and trajectory simulations.

Effects of Refractive Index and Diffuse or Specular Boundaries on a Radiating Isothermal Layer

NASA Technical Reports Server (NTRS)

Siegel, R.; Spuckler, C. M.

1994-01-01

Equilibrium temperatures of an absorbing-emitting layer were obtained for exposure to incident radiation and with the layer boundaries either specular or diffuse. For high refractive indices the surface condition can influence the radiative heat balance if the layer optical thickness is small. Hence for a spectrally varying absorption coefficient the layer temperature is affected if there is significant radiative energy in the spectral range with a small absorption coefficient. Similar behavior was obtained for transient radiative cooling of a layer where the results are affected by the initial temperature and hence the fraction of energy radiated in the short wavelength region where the absorption coefficient is small. The results are a layer without internal scattering. If internal scattering is significant, the radiation reaching the internal surface of a boundary is diffused and the effect of the two different surface conditions would become small.

Aging and the perception of local surface orientation from optical patterns of shading and specular highlights.

PubMed

Norman, J Farley; Wiesemann, Elizabeth Y

2007-01-01

Younger and older observers' ability to perceive local surface orientation from optical patterns of shading and specular highlights was investigated in two experiments. On each trial, the observers viewed a randomly generated, smoothly curved 3-D object and manipulated an adjustable gauge figure until its orientation matched that of a specific local region on the object's surface (cf. Koenderink, van Doom, & Kappers, 1992). The performance of both age groups was facilitated by the presence of binocular disparity (Experiment 1) and object rotation in depth (Experiment 2). Observers in both age groups were able to judge the surface tilt component of orientation more precisely than the slant component. Significant, but modest, effects of age were found in Experiment 1, but not in Experiment 2. The ability to perceive local surface orientation appears to be relatively well preserved with increasing age, at least through the age of 80.

A unified account of gloss and lightness perception in terms of gamut relativity.

PubMed

Vladusich, Tony

2013-08-01

A recently introduced computational theory of visual surface representation, termed gamut relativity, overturns the classical assumption that brightness, lightness, and transparency constitute perceptual dimensions corresponding to the physical dimensions of luminance, diffuse reflectance, and transmittance, respectively. Here I extend the theory to show how surface gloss and lightness can be understood in a unified manner in terms of the vector computation of "layered representations" of surface and illumination properties, rather than as perceptual dimensions corresponding to diffuse and specular reflectance, respectively. The theory simulates the effects of image histogram skewness on surface gloss/lightness and lightness constancy as a function of specular highlight intensity. More generally, gamut relativity clarifies, unifies, and generalizes a wide body of previous theoretical and experimental work aimed at understanding how the visual system parses the retinal image into layered representations of surface and illumination properties.

Reproduction and optical analysis of Morpho-inspired polymeric nanostructures

NASA Astrophysics Data System (ADS)

Tippets, Cary A.; Fu, Yulan; Jackson, Anne-Martine; Donev, Eugenii U.; Lopez, Rene

2016-06-01

The brilliant blue coloration of the Morpho rhetenor butterfly originates from complex nanostructures found on the surface of its wings. The Morpho butterfly exhibits strong short-wavelength reflection and a unique two-lobe optical signature in the incident (θ) and reflected (ϕ) angular space. Here, we report the large-area fabrication of a Morpho-like structure and its reproduction in perfluoropolyether. Reflection comparisons of periodic and quasi-random ‘polymer butterfly’ nanostructures show similar normal-incidence spectra but differ in the angular θ-ϕ dependence. The periodic sample shows strong specular reflection and simple diffraction. However, the quasi-random sample produces a two-lobe angular reflection pattern with minimal specular refection, approximating the real butterfly’s optical behavior. Finite-difference time-domain simulations confirm that this pattern results from the quasi-random periodicity and highlights the significance of the inherent randomness in the Morpho’s photonic structure.

Coupled thermo-elastic and optical performance analyses of a reflective baffle for the BepiColombo laser altimeter (BELA) receiver

NASA Astrophysics Data System (ADS)

Heesel, E.; Weigel, T.; Lochmatter, P.; Rugi Grond, E.

2017-11-01

For the BepiColombo mission, the extreme thermal environment around Mercury requires good heat shields for the instruments. The BepiColombo Laser altimeter (BELA) Receiver will be equipped with a specular reflective baffle in order to limit the solar power impact. The design uses a Stavroudis geometry with alternating elliptical and hyperbolic vanes to reflect radiation at angles >38° back into space. The thermal loads on the baffle lead to deformations, and the resulting changes in the optical performance can be modeled by ray-tracing. Conventional interfaces, such as Zernike surface fitting, fail to provide a proper import of the mechanical distortions into optical models. We have studied alternative models such as free form surface representations and compared them to a simple modeling approach with straight segments. The performance merit is presented in terms of the power rejection ratio and the absence of specular stray-light.

Method and apparatus for inspecting reflection masks for defects

DOEpatents

Bokor, Jeffrey; Lin, Yun

2003-04-29

An at-wavelength system for extreme ultraviolet lithography mask blank defect detection is provided. When a focused beam of wavelength 13 nm is incident on a defective region of a mask blank, three possible phenomena can occur. The defect will induce an intensity reduction in the specularly reflected beam, scatter incoming photons into an off-specular direction, and change the amplitude and phase of the electric field at the surface which can be monitored through the change in the photoemission current. The magnitude of these changes will depend on the incident beam size, and the nature, extent and size of the defect. Inspection of the mask blank is performed by scanning the mask blank with 13 nm light focused to a spot a few .mu.m in diameter, while measuring the reflected beam intensity (bright field detection), the scattered beam intensity (dark-field detection) and/or the change in the photoemission current.

Application of the three-component bidirectional reflectance distribution function model to Monte Carlo calculation of spectral effective emissivities of nonisothermal blackbody cavities.

PubMed

Prokhorov, Alexander; Prokhorova, Nina I

2012-11-20

We applied the bidirectional reflectance distribution function (BRDF) model consisting of diffuse, quasi-specular, and glossy components to the Monte Carlo modeling of spectral effective emissivities for nonisothermal cavities. A method for extension of a monochromatic three-component (3C) BRDF model to a continuous spectral range is proposed. The initial data for this method are the BRDFs measured in the plane of incidence at a single wavelength and several incidence angles and directional-hemispherical reflectance measured at one incidence angle within a finite spectral range. We proposed the Monte Carlo algorithm for calculation of spectral effective emissivities for nonisothermal cavities whose internal surface is described by the wavelength-dependent 3C BRDF model. The results obtained for a cylindroconical nonisothermal cavity are discussed and compared with results obtained using the conventional specular-diffuse model.

Polarized BRDF measurement of the type E235B low carbon structural steel

NASA Astrophysics Data System (ADS)

Liu, Yanlei; Yu, Kun; Zhang, Kaihua; Liu, Yufang

2018-01-01

Bidirectional reflectance distribution function (BRDF) offers complete description of the spectral and spatial characteristics of opaque materials. The polarized BRDF contains more information, especially for the painted objects and target recognition. In this letter, we measured the in plane polarized spectral BRDF for the steel E235B in the wavelength range of 450-600 nm. The reliability of our results is verified by comparing the experimental data of polytetrafluoroethylene with the reference data. The measuring results indicates that the wavelength of incident light has a positive effect on the BRDF near the specular direction, and has a negative influence for other direction. BRDF increases slowly with reflected zenith angle and decreases rapidly with peak occurs at specular direction, which may be attributed to the shadowing effect. In addition, the results presents that the polarization of incident light has a slight influence on the BRDF of the sample.

Magnetic resonance microscopy of prostate tissue: How basic science can inform clinical imaging development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bourne, Roger

2013-03-15

This commentary outlines how magnetic resonance imaging (MRI) microscopy studies of prostate tissue samples and whole organs have shed light on a number of clinical imaging mysteries and may enable more effective development of new clinical imaging methods.

Three dimensional metafilms with dual channel unit cells

DOE PAGES

Burckel, D. Bruce; Campione, Salvatore; Davids, Paul S.; ...

2017-04-04

Three-dimensional (3D) metafilms composed of periodic arrays of silicon unit cells containing single and multiple micrometer-scale vertical split ring resonators (SRRs) per unit cell were fabricated. In contrast to planar and stacked planar structures, these 3D metafilms have a thickness t ~λ d/4, allowing for classical thin film effects in the long wavelength limit. The infrared specular far-field scattering response was measured for metafilms containing one and two resonators per unit cell and compared to numerical simulations. Excellent agreement in the frequency region below the onset of diffractive scattering was obtained. For dense arrays of unit cells containing single SRRs,more » normally incident linearly polarized plane waves which do not excite a resonant response result in thin film interference fringes in the reflected spectra and are virtually indistinguishable from the scattering response of an undecorated array of unit cells. For the resonant linear polarization, the specular reflection for arrays is highly dependent on the SRR orientation on the vertical face for gap-up, gap-down, and gap-right orientations. For dense arrays of unit cells containing two SRRs per unit cell positioned on adjacent faces, the specular reflection spectra are slightly modified due to near-field coupling between the orthogonally oriented SRRs but otherwise exhibit reflection spectra largely representative of the corresponding single-SRR unit cell structures. Lastly, the ability to pack the unit cell with multiple inclusions which can be independently excited by choice of incident polarization suggests the construction of dual-channel films where the scattering response is selected by altering the incident polarization.« less

General solution for high dynamic range three-dimensional shape measurement using the fringe projection technique

NASA Astrophysics Data System (ADS)

Feng, Shijie; Zhang, Yuzhen; Chen, Qian; Zuo, Chao; Li, Rubin; Shen, Guochen

2014-08-01

This paper presents a general solution for realizing high dynamic range three-dimensional (3-D) shape measurement based on fringe projection. Three concrete techniques are involved in the solution for measuring object with large range of reflectivity (LRR) or one with shiny specular surface. For the first technique, the measured surface reflectivities are sub-divided into several groups based on its histogram distribution, then the optimal exposure time for each group can be predicted adaptively so that the bright as well as dark areas on the measured surface are able to be handled without any compromise. Phase-shifted images are then captured at the calculated exposure times and a composite phase-shifted image is generated by extracting the optimally exposed pixels in the raw fringes images. For the second technique, it is proposed by introducing two orthogonal polarizers which are placed separately in front of the camera and projector into the first technique and the third one is developed by combining the second technique with the strategy of properly altering the angle between the transmission axes of the two polarizers. Experimental results show that the first technique can effectively improve the measurement accuracy of diffuse objects with LRR, the second one is capable of measuring object with weak specular reflection (WSR: e.g. shiny plastic surface) and the third can inspect surface with strong specular reflection (SSR: e.g. highlight on aluminum alloy) precisely. Further, more complex scene, such as the one with LRR and WSR, or even the one simultaneously involving LRR, WSR and SSR, can be measured accurately by the proposed solution.

A FALSE POSITIVE FOR OCEAN GLINT ON EXOPLANETS: THE LATITUDE-ALBEDO EFFECT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cowan, Nicolas B.; Abbot, Dorian S.; Voigt, Aiko

2012-06-10

Identifying liquid water on the surface of planets is a high priority, as this traditionally defines habitability. One proposed signature of oceans is specular reflection ('glint'), which increases the apparent albedo of a planet at crescent phases. We post-process a global climate model of an Earth-like planet to simulate reflected light curves. Significantly, we obtain glint-like phase variations even though we do not include specular reflection in our model. This false positive is the product of two generic properties: (1) for modest obliquities, a planet's poles receive less orbit-averaged stellar flux than its equator, so the poles are more likelymore » to be covered in highly reflective snow and ice; and (2) we show that reflected light from a modest-obliquity planet at crescent phases probes higher latitudes than at gibbous phases, therefore a planet's apparent albedo will naturally increase at crescent phase. We suggest that this 'latitude-albedo effect' will operate even for large obliquities: in that case the equator receives less orbit-averaged flux than the poles, and the equator is preferentially sampled at crescent phase. Using rotational and orbital color variations to map the surfaces of directly imaged planets and estimate their obliquity will therefore be a necessary pre-condition for properly interpreting their reflected phase variations. The latitude-albedo effect is a particularly convincing glint false positive for zero-obliquity planets, and such worlds are not amenable to latitudinal mapping. This effect severely limits the utility of specular reflection for detecting oceans on exoplanets.« less

Correlations of oriented ice and precipitation in marine midlatitude low clouds using collocated CloudSat, CALIOP, and MODIS observations

NASA Astrophysics Data System (ADS)

Ross, Alexa; Holz, Robert E.; Ackerman, Steven A.

2017-08-01

In April 2006, the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) launched aboard the CALIPSO satellite and into the A-Train constellation of satellites with its transmitter pointed near nadir. This proved problematic due to specular reflection from horizontally oriented ice crystals occurring more frequently than expected. Because the specular backscatter from oriented ice crystals has large attenuated backscatter and almost no depolarization, the standard lidar inversions cannot be applied. To mitigate this issue, the CALIOP transmitter was moved to 3° off nadir in November 2007. Though problematic for global CALIOP retrievals, the sensitivity to oriented ice during the first year of observations provides a unique data set to investigate scenes of this ice crystal signature. This study focuses on the CALIOP-oriented signature that occurs in midlatitude ocean regions whose cloud tops are relatively warm and low, existing below 6 km. A significant seasonal dependence is found in the Northern Hemisphere with up to 19% of clouds below 6 km yielding specular reflection by CALIOP during the colder months. In contrast, the Southern Hemisphere lacks such seasonal dependence and sees fewer oriented ice crystals. Using collocated CloudSat observations with both CALIOP and Moderate Resolution Imaging Spectroradiometer (MODIS), we investigate the correlations of the oriented signature with MODIS cloud properties. Comparing with CloudSat precipitation retrievals, we find that the oriented signature is strongly correlated with surface precipitation with 64% of CALIOP-oriented ice crystal cases precipitating compared to 40% for nonoriented cases.

Delay and Standard Deviation Beamforming to Enhance Specular Reflections in Ultrasound Imaging.

PubMed

Bandaru, Raja Sekhar; Sornes, Anders Rasmus; Hermans, Jeroen; Samset, Eigil; D'hooge, Jan

2016-12-01

Although interventional devices, such as needles, guide wires, and catheters, are best visualized by X-ray, real-time volumetric echography could offer an attractive alternative as it avoids ionizing radiation; it provides good soft tissue contrast, and it is mobile and relatively cheap. Unfortunately, as echography is traditionally used to image soft tissue and blood flow, the appearance of interventional devices in conventional ultrasound images remains relatively poor, which is a major obstacle toward ultrasound-guided interventions. The objective of this paper was therefore to enhance the appearance of interventional devices in ultrasound images. Thereto, a modified ultrasound beamforming process using conventional-focused transmit beams is proposed that exploits the properties of received signals containing specular reflections (as arising from these devices). This new beamforming approach referred to as delay and standard deviation beamforming (DASD) was quantitatively tested using simulated as well as experimental data using a linear array transducer. Furthermore, the influence of different imaging settings (i.e., transmit focus, imaging depth, and scan angle) on the obtained image contrast was evaluated. The study showed that the image contrast of specular regions improved by 5-30 dB using DASD beamforming compared with traditional delay and sum (DAS) beamforming. The highest gain in contrast was observed when the interventional device was tilted away from being orthogonal to the transmit beam, which is a major limitation in standard DAS imaging. As such, the proposed beamforming methodology can offer an improved visualization of interventional devices in the ultrasound image with potential implications for ultrasound-guided interventions.

Calculating Angle Lambda (λ) Using Zernike Tilt Measurements in Specular Reflection Corneal Topography

PubMed Central

Braaf, Boy; van de Watering, Thomas Christiaan; Spruijt, Kees; van der Heijde, Rob G.L.; Sicam, Victor Arni D.P.

2010-01-01

Purpose To develop a method to calculate the angle λ of the human eye using Zernike tilt measurements in specular reflection corneal topography. Methods The meaning of Zernike tilt in specular reflection corneal topography is demonstrated by measurements on translated artificial surfaces using the VU Topographer. The relationship derived from the translation experiments is used to determine the angle λ. Corneal surfaces are measured for a set of eight different fixation points, for which tilt angles ρ are obtained from the Zernike tilt coefficients. The angles ρ are used with respect to the fixation target angles to determine angle λ by fitting a geometrical model. This method is validated with Orbscan II's angle-κ measurements in 9 eyes. Results The translation experiments show that the Zernike tilt coefficient is directly related to an angle ρ, which describes a tilt orientation of the cornea and can therefore be used to derive a value for angle λ. A significant correlation exists between measured values for angle λ with the VU Topographer and the angle κ with the Orbscan II (r=0.95, P<0.001). A Bland-Altman plot indicates a mean difference of -0.52 degrees between the two instruments, but this is not statistically significant as indicated by a matched-pairs Wilcoxon signed-rank test (P≤0.1748). The mean precision for measuring angle λ using the VU topographer is 0.6±0.3 degrees. Conclusion The method described above to determine angle λ is sufficiently repeatable and performs similarly to the angle-κ measurements made with the Orbscan II.

Optimizing Waveform Maximum Determination for Specular Point Tracking in Airborne GNSS-R.

PubMed

Motte, Erwan; Zribi, Mehrez

2017-08-16

Airborne GNSS-R campaigns are crucial to the understanding of signal interactions with the Earth's surface. As a consequence of the specific geometric configurations arising during measurements from aircraft, the reflected signals can be difficult to interpret under certain conditions like over strongly attenuating media such as forests, or when the reflected signal is contaminated by the direct signal. For these reasons, there are many cases where the reflectivity is overestimated, or a portion of the dataset has to be flagged as unusable. In this study we present techniques that have been developed to optimize the processing of airborne GNSS-R data, with the goal of improving its accuracy and robustness under non-optimal conditions. This approach is based on the detailed analysis of data produced by the instrument GLORI, which was recorded during an airborne campaign in the south west of France in June 2015. Our technique relies on the improved determination of reflected waveform peaks in the delay dimension, which is related to the loci of the signals contributed by the zone surrounding the specular point. It is shown that when developing techniques for the correct localization of waveform maxima under conditions of surfaces of low reflectivity, and/or contamination from the direct signal, it is possible to correct and extract values corresponding to the real reflectivity of the zone in the neighborhood of the specular point. This algorithm was applied to a reanalysis of the complete campaign dataset, following which the accuracy and sensitivity improved, and the usability of the dataset was improved by 30%.

Italy

Atmospheric Science Data Center

2013-04-17

... standing water appear in blue or purple-blue hues, because sun glitter (an ensemble of specular reflection points, see below) causes ... to look brighter to a camera that is pointing toward the Sun. The purple-blue areas indicate the extensive irrigation network that ...

78 FR 46932 - Notice of Availability of Government-Owned Inventions; Available for Licensing

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-02

... APPARATUS, Issued on June 18, 2013//U.S. Patent Number 8,477,308: POLARIZED, SPECULAR REFLECTOMETER APPARATUS, Issued on July 2, 2013. ADDRESSES: Requests for copies of the inventions cited should be directed...

Is There Ecological Information in Optical Polarization Data?

NASA Technical Reports Server (NTRS)

Vanderbilt, Vern; Daughtry, Craig; Dahlgren, Robert

2015-01-01

Optical linear polarization? In remote sensing it's due to specular reflection. The first surface that incident light encounters - a smooth water surface or the waxy first surface of a leaf's cuticle, if it's even somewhat smooth (i.e. shiny) - will specularly reflect and linearly polarize the incident light. We provide three examples of the types of ecological information contained in remotely sensed optical linear polarization measurements. Remove the surface reflection to better see the interior. The linearly polarized light reflected by leaf surfaces contains no information about cellular pigments, metabolites, or water contained in the leaf interiors of a plant canopy, because it never enters the leaf interior to interact with them. Thus, for purposes of remotely sensing the leaf interiors of a plant canopy, the linearly polarized light should be subtracted from the total reflected light, because including it would add noise to the measurement. In particular 'minus specular' vegetation indices should allow improved monitoring of a plant canopy's physiological processes. Estimate plant development stage and yield. Wheat and sorghum grain heads, following emergence, rapidly extend upward and very quickly tower over nearby leaves, partially blocking our view of the sunlight reflected by those leaf surfaces. The resulting decrease in the amount of surface reflected and polarized sunlight, if monitored over time, potentially allows per-field estimates of the dates of the heading and flowering development stages to be interleaved with weather data in models, which is key to better estimating per-field grain yield. Similar polarization changes may occur in other grasses, such as oats, barley, corn and rice, each a crop so widely grown that it potentially affects climate at the regional scale. Wetlands Mapping. The sunlight specularly reflected by surface waters is blindingly bright, spectrally flat and polarized - all of which telegraphs that the ground area is inundated. Inundated soils exchange methane with the atmosphere; non-inundated soils, carbon dioxide. Aquatic plants growing through the water surface pipe the soil-produced methane via the stomata to the atmosphere, enhancing exchanges rates by factors of 10-20 compared to ebullition (bubbling) or diffusion through the water column to the atmosphere. Thus, mapping wetland areas into three community types - inundated areas with emergent vegetation, open water and uplands - provides potentially key information to water, carbon and energy budgets at landscape to global scales.

Surface roughness scattering of electrons in bulk mosfets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zuverink, Amanda Renee

2015-11-01

Surface-roughness scattering of electrons at the Si-SiO 2 interface is a very important consideration when analyzing Si metal-oxide-semiconductor field-effect transistors (MOSFETs). Scattering reduces the mobility of the electrons and degrades the device performance. 250-nm and 50-nm bulk MOSFETs were simulated with varying device parameters and mesh sizes in order to compare the effects of surface-roughness scattering in multiple devices. The simulation framework includes the ensemble Monte Carlo method used to solve the Boltzmann transport equation coupled with a successive over-relaxation method used to solve the two-dimensional Poisson's equation. Four methods for simulating the surface-roughness scattering of electrons were implemented onmore » both devices and compared: the constant specularity parameter, the momentum-dependent specularity parameter, and the real-space-roughness method with both uniform and varying electric fields. The specularity parameter is the probability of an electron scattering speculariy from a rough surface. It can be chosen as a constant, characterizing partially diffuse scattering of all electrons from the surface the same way, or it can be momentum dependent, where the size of rms roughness and the normal component of the electron wave number determine the probability of electron-momentum randomization. The real-space rough surface method uses the rms roughness height and correlation length of an actual MOSFET to simulate a rough interface. Due to their charge, electrons scatter from the electric field and not directly from the surface. If the electric field is kept uniform, the electrons do not perceive the roughness and scatter as if from a at surface. However, if the field is allowed to vary, the electrons scatter from the varying electric field as they would in a MOSFET. These methods were implemented for both the 50-nm and 250-nm MOSFETs, and using the rms roughness heights and correlation lengths for real devices. The current-voltage and mobility-electric field curves were plotted for each method on the two devices and compared. The conclusion is that the specularity-parameter methods are valuable as simple models for relatively smooth interfaces. However, they have limitations, as they cannot accurately describe the drastic reduction in the current and the electron mobility that occur in MOSFETs with very rough Si-SiO 2 interfaces.« less

Synchrotron X-Ray Diffraction Study of Structure and Growth of Adsorbed Layers

NASA Astrophysics Data System (ADS)

Dai, Pengcheng

Synchrotron x-ray diffraction and scanning-tunneling -microscopy (STM) experiments reveal a new commensurate monolayer structure of 10CB (decylcyanobiphenyl) molecules adsorbed on the (0001) graphite surface. Our results are consistent with two generic structures for nCB monolayers on surfaces of hexagonal symmetry. The monolayer d spacing of the new phase inferred by STM is 10% layer than that obtained by x-ray diffraction on the same sample. We suggest that part of this discrepancy results from a systematic error introduced in calibration of the STM length scale against the graphite substrate. For multilayer nCB films, we find that a polycrystalline structure is formed and most of the adsorbed molecules are aligned with their long axis perpendicular to the graphite surface. Synchrotron x-ray scattering has been used to investigate the structure and growth of xenon physisorbed on the Ag(111) surface using a specially designed ultra -high vacuum (UHV) chamber. For growth under quasi-equilibrium conditions, the bulk Xe-Xe spacing is reached at monolayer completion and solid films of thickness >= 220 A are observed in which an 'ABC' stacking sequence predominates. Under kinetic growth conditions, intensity oscillations at the Xe anti-Bragg position of the specular rod are observed as a function of time, indicating layer -by-layer growth. Analysis of the specular reflectivity at different coverages yields the fractional layer occupancies and the spacing between the Ag(111) surface and first Xe layer. We have conducted a series of low-energy electron diffraction (LEED) 'kinetic isotherm' experiments on both xenon and hexane rm(C_6H_{14 }) films adsorbed on the Ag(111) surface. Our preliminary results show that under the pressure and temperature range accessible to the experiments, all of the Xe kinetic isotherms fall on a universal curve which is concave upward. However, the hexane kinetic isotherms have a qualitatively different shape (S-like) at the higher temperatures while being similar to Xe at low temperatures. From these experiments, we determine that the growth of xenon from submonolayer to 0.9 monolayer is 'zero-order'. However, the growth of hexane is more complicated. It follows the 'first-order' at low temperatures, and changes to S-like shape at high temperatures which we do not yet understand.

Neurosurgical confocal endomicroscopy: A review of contrast agents, confocal systems, and future imaging modalities

PubMed Central

Zehri, Aqib H.; Ramey, Wyatt; Georges, Joseph F.; Mooney, Michael A.; Martirosyan, Nikolay L.; Preul, Mark C.; Nakaji, Peter

2014-01-01

Background: The clinical application of fluorescent contrast agents (fluorescein, indocyanine green, and aminolevulinic acid) with intraoperative microscopy has led to advances in intraoperative brain tumor imaging. Their properties, mechanism of action, history of use, and safety are analyzed in this report along with a review of current laser scanning confocal endomicroscopy systems. Additional imaging modalities with potential neurosurgical utility are also analyzed. Methods: A comprehensive literature search was performed utilizing PubMed and key words: In vivo confocal microscopy, confocal endomicroscopy, fluorescence imaging, in vivo diagnostics/neoplasm, in vivo molecular imaging, and optical imaging. Articles were reviewed that discussed clinically available fluorophores in neurosurgery, confocal endomicroscopy instrumentation, confocal microscopy systems, and intraoperative cancer diagnostics. Results: Current clinically available fluorescent contrast agents have specific properties that provide microscopic delineation of tumors when imaged with laser scanning confocal endomicroscopes. Other imaging modalities such as coherent anti-Stokes Raman scattering (CARS) microscopy, confocal reflectance microscopy, fluorescent lifetime imaging (FLIM), two-photon microscopy, and second harmonic generation may also have potential in neurosurgical applications. Conclusion: In addition to guiding tumor resection, intraoperative fluorescence and microscopy have the potential to facilitate tumor identification and complement frozen section analysis during surgery by providing real-time histological assessment. Further research, including clinical trials, is necessary to test the efficacy of fluorescent contrast agents and optical imaging instrumentation in order to establish their role in neurosurgery. PMID:24872922

Innovative Strategies for Clinical Microscopy Instruction: Virtual Versus Light Microscopy.

PubMed

McDaniel, M Jane; Russell, Gregory B; Crandall, Sonia J

2018-06-01

The purpose of the study was to compare virtual microscopy with light microscopy to determine differences in learning outcomes and learner attitudes in teaching clinical microscopy to physician assistant (PA) students. A prospective, randomized, crossover design study was conducted with a convenience sample of 67 first-year PA students randomized to 2 groups. One group used light microscopes to find microscopic structures, whereas the other group used instructor-directed video streaming of microscopic elements. At the midpoint of the study, the groups switched instructional strategies. Learning outcomes were assessed via posttest after each section of the study, with comparison of final practical examination results to previous cohorts. Attitudes about the 2 educational strategies were assessed through a postcourse questionnaire with a Likert scale. Analysis of the first posttest demonstrated that students in the video-streamed group had significantly better learning outcomes than those in the light microscopy group (P = .004; Cohen's d = 0.74). Analysis of the posttest after crossover showed no differences between the 2 groups (P = .48). Between the 2 posttests, students first assigned to the light microscopy group scored a 6.6 mean point increase (±10.4 SD; p = .0011), whereas students first assigned to the virtual microscopy group scored a 1.3 mean point increase (±7.1 SD; p = .29). The light microscopy group improved more than the virtual microscopy group (P = .019). Analysis of practical examination data revealed higher scores for the study group compared with 5 previous cohorts of first-year students (P < .0001; Cohen's d = 0.66). Students preferred virtual microscopy to traditional light microscopy. Virtual microscopy is an effective educational strategy, and students prefer this method when learning to interpret images of clinical specimens.

Nanoscale imaging of clinical specimens using pathology-optimized expansion microscopy

PubMed Central

Zhao, Yongxin; Bucur, Octavian; Irshad, Humayun; Chen, Fei; Weins, Astrid; Stancu, Andreea L.; Oh, Eun-Young; DiStasio, Marcello; Torous, Vanda; Glass, Benjamin; Stillman, Isaac E.; Schnitt, Stuart J.; Beck, Andrew H.; Boyden, Edward S.

2017-01-01

Expansion microscopy (ExM), a method for improving the resolution of light microscopy by physically expanding the specimen, has not been applied to clinical tissue samples. Here we report a clinically optimized form of ExM that supports nanoscale imaging of human tissue specimens that have been fixed with formalin, embedded in paraffin, stained with hematoxylin and eosin (H&E), and/or fresh frozen. The method, which we call expansion pathology (ExPath), converts clinical samples into an ExM-compatible state, then applies an ExM protocol with protein anchoring and mechanical homogenization steps optimized for clinical samples. ExPath enables ~70 nm resolution imaging of diverse biomolecules in intact tissues using conventional diffraction-limited microscopes, and standard antibody and fluorescent DNA in situ hybridization reagents. We use ExPath for optical diagnosis of kidney minimal-change disease, which previously required electron microscopy (EM), and demonstrate high-fidelity computational discrimination between early breast neoplastic lesions that to date have challenged human judgment. ExPath may enable the routine use of nanoscale imaging in pathology and clinical research. PMID:28714966

Nanoscale imaging of clinical specimens using pathology-optimized expansion microscopy.

PubMed

Zhao, Yongxin; Bucur, Octavian; Irshad, Humayun; Chen, Fei; Weins, Astrid; Stancu, Andreea L; Oh, Eun-Young; DiStasio, Marcello; Torous, Vanda; Glass, Benjamin; Stillman, Isaac E; Schnitt, Stuart J; Beck, Andrew H; Boyden, Edward S

2017-08-01

Expansion microscopy (ExM), a method for improving the resolution of light microscopy by physically expanding a specimen, has not been applied to clinical tissue samples. Here we report a clinically optimized form of ExM that supports nanoscale imaging of human tissue specimens that have been fixed with formalin, embedded in paraffin, stained with hematoxylin and eosin, and/or fresh frozen. The method, which we call expansion pathology (ExPath), converts clinical samples into an ExM-compatible state, then applies an ExM protocol with protein anchoring and mechanical homogenization steps optimized for clinical samples. ExPath enables ∼70-nm-resolution imaging of diverse biomolecules in intact tissues using conventional diffraction-limited microscopes and standard antibody and fluorescent DNA in situ hybridization reagents. We use ExPath for optical diagnosis of kidney minimal-change disease, a process that previously required electron microscopy, and we demonstrate high-fidelity computational discrimination between early breast neoplastic lesions for which pathologists often disagree in classification. ExPath may enable the routine use of nanoscale imaging in pathology and clinical research.

What makes a feather shine? A nanostructural basis for glossy black colours in feathers.

PubMed

Maia, Rafael; D'Alba, Liliana; Shawkey, Matthew D

2011-07-07

Colours in feathers are produced by pigments or by nanostructurally organized tissues that interact with light. One of the simplest nanostructures is a single layer of keratin overlying a linearly organized layer of melanosomes that create iridescent colours of feather barbules through thin-film interference. Recently, it has been hypothesized that glossy (i.e. high specular reflectance) black feathers may be evolutionarily intermediate between matte black and iridescent feathers, and thus have a smooth keratin layer that produces gloss, but not the layered organization of melanosomes needed for iridescence. However, the morphological bases of glossiness remain unknown. Here, we use a theoretical approach to generate predictions about morphological differences between matte and glossy feathers that we then empirically test. Thin-film models predicted that glossy spectra would result from a keratin layer 110-180 nm thick and a melanin layer greater than 115 nm thick. Transmission electron microscopy data show that nanostructure of glossy barbules falls well within that range, but that of matte barbules does not. Further, glossy barbules had a thinner and more regular keratin cortex, as well as a more continuous underlying melanin layer, than matte barbules. Thus, their quasi-ordered nanostructures are morphologically intermediate between matte black and iridescent feathers, and perceived gloss may be a form of weakly chromatic iridescence.

Changes in the cornea related to sickle cell disease: a pilot investigation.

PubMed

Coşkun, Mesut; İlhan, Özgür; İlhan, Nilüfer; Tuzcu, Esra Ayhan; Daglioğlu, Mutlu Cihan; Kahraman, Hilal; Elbeyli, Ahmet; Yarbağ, Abdulhekim; Helvaci, Mehmet Rami

2015-01-01

To investigate corneal structural changes (central corneal thickness, endothelial cell count, and cellular morphology) in patients with sickle cell disease (SCD). This prospective study included 56 patients with SCD and 50 age- and sex-matched healthy subjects without any eye disease aside from refractive errors. Endothelial cell density (ECD), percentage of hexagonality, and the coefficient of variation in cell size (CV) were measured using noncontact specular microscopy, and central corneal thickness (CCT) was measured by pachymetry. The mean CCT value was 509.6 ± 20.7 μm in the study group and 520.8 ± 23.6 μm in the control group. The mean ECD, CV, and percentage of hexagonality values in the study group were 2712 ± 335 cells/mm², 34.5 ± 5.3%, and 57.2 ± 6.6%, respectively, and 3030 ± 247 cells/mm², 31.6 ± 5.0%, and 60.4 ± 6.9% in the control group, respectively. Endothelial cell density (p = 0.001), CCT (p = 0.011), CV (p = 0.005), and percentage of hexagonality values (p = 0.018) were significantly different between the study and control groups. The results of the current study indicate that patients with SCD had considerable morphologic changes in the structure of the cornea when compared to healthy subjects.

Surface cytologic features on intraocular lenses: can increased biocompatibility have disadvantages?

PubMed

Hollick, E J; Spalton, D J; Ursell, P G

1999-07-01

To compare the anterior surface cytologic features and effect on blood-aqueous barrier of polymethyl methacrylate, silicone, and hydrogel intraocular lens (IOL) implants to give an indication of their biocompatibility. This prospective study was performed at an English-teaching hospital. Ninety eyes were randomized to receive a polymethyl methacrylate, silicone, or hydrogel implant. A standardized surgical protocol was performed by a single surgeon using phacoemulsification. Patients were seen at intervals for 1 year. Measurements of visual acuity, contrast sensitivity, and anterior chamber laser flare and cells were obtained; and an assessment of lens cytologic features using specular microscopy of the anterior IOL surface was performed. Visual acuity and contrast sensitivity were not significantly different among the 3 groups. Hydrogel IOLs were associated with fewer inflammatory cells on their surface than polymethyl methacrylate and silicone IOLs (P<.001), but with significantly more lens epithelial cells (LECs) (P<.001). Patients with hydrogel implants without LECs had greater blood-aqueous barrier breakdown than those with LECs. The hydrogel IOLs were associated with a reduced inflammatory cell reaction but had many more LECs on their anterior surface. Those IOLs associated with increased blood-aqueous barrier damage did not develop LECs. If an IOL is too biocompatible, then it may incite the growth of LECs over its surface, which could have disadvantages.

Uniform enhancement of optical micro-angiography images using Rayleigh contrast-limited adaptive histogram equalization.

PubMed

Yousefi, Siavash; Qin, Jia; Zhi, Zhongwei; Wang, Ruikang K

2013-02-01

Optical microangiography is an imaging technology that is capable of providing detailed functional blood flow maps within microcirculatory tissue beds in vivo. Some practical issues however exist when displaying and quantifying the microcirculation that perfuses the scanned tissue volume. These issues include: (I) Probing light is subject to specular reflection when it shines onto sample. The unevenness of the tissue surface makes the light energy entering the tissue not uniform over the entire scanned tissue volume. (II) The biological tissue is heterogeneous in nature, meaning the scattering and absorption properties of tissue would attenuate the probe beam. These physical limitations can result in local contrast degradation and non-uniform micro-angiogram images. In this paper, we propose a post-processing method that uses Rayleigh contrast-limited adaptive histogram equalization to increase the contrast and improve the overall appearance and uniformity of optical micro-angiograms without saturating the vessel intensity and changing the physical meaning of the micro-angiograms. The qualitative and quantitative performance of the proposed method is compared with those of common histogram equalization and contrast enhancement methods. We demonstrate that the proposed method outperforms other existing approaches. The proposed method is not limited to optical microangiography and can be used in other image modalities such as photo-acoustic tomography and scanning laser confocal microscopy.

Proximate bases of silver color in anhinga (Anhinga anhinga) feathers.

PubMed

Shawkey, Matthew D; Maia, Rafael; D'Alba, Liliana

2011-11-01

Colors of living organisms are produced by selective light absorption from pigments and/or by light scattering from highly ordered nanostructures (i.e., structural color). While the physical bases of metallic colors of arthropods and fish are fairly well-known, those of birds are not. Here we examine structurally based silver color and its production in feathers of the waterbird species Anhinga. This achromatic color is distinguished from grey by high specular reflectance, from white by low diffuse reflectance, and from both by high gloss. Light and electron microscopy revealed three modifications of feathers likely leading to silver color. First, proximal barbules were highly elongated and contained glossy black color at their base and white color at their pennulum. Second, this glossy black portion contained a single outer layer of keratin weakly bounded by melanosomes. Finally, the white portion contained a disordered amorphous matrix of keratin and air. Optical analyzes suggest that these structures produce, respectively, glossy black color through thin-film interference and white color through incoherent light scattering. Silver color likely results from the combined reflectance of these adjacent structures. This represents a distinct mechanism for attaining silver colors that may have been partially derived through selection for display, thermoregulation or decreased hydrophobicity. Copyright © 2011 Wiley-Liss, Inc.

Corneal endothelial cell density and morphology in Phramongkutklao Hospital

PubMed Central

Sopapornamorn, Narumon; Lekskul, Manapon; Panichkul, Suthee

2008-01-01

Objective To describe the corneal endothelial density and morphology in patients of Phramongkutklao Hospital and the relationship between endothelial cell parameters and other factors. Methods Four hundred and four eyes of 202 volunteers were included. Noncontact specular microscopy was performed after taking a history and testing the visual acuity, intraocular pressure measurement, Schirmer’s test and routine eye examination by slit lamp microscope. The studied parameters included mean endothelial cell density (MCD), coefficient of variation (CV), and percentage of hexagonality. Results The mean age of volunteers was 45.73 years; the range being 20 to 80 years old. Their MCD (SD), mean percentage of CV (SD) and mean (SD) percentage of hexagonality were 2623.49(325) cell/mm2, 39.43(8.23)% and 51.50(10.99)%, respectively. Statistically, MCD decreased significantly with age (p < 0.01). There was a significant difference in the percentage of CV between genders. There was no statistical significance between parameters and other factors. Conclusion The normative data of the corneal endothelium of Thai eyes indicated that, statistically, MCD decreased significantly with age. Previous studies have reported no difference in MCD, percentage of CV, and percentage of hexagonality between gender. Nevertheless, significantly different percentages of CV between genders were presented in this study. PMID:19668398

Compact 3D printed module for fluorescence and label-free imaging using evanescent excitation

NASA Astrophysics Data System (ADS)

Pandey, Vikas; Gupta, Shalini; Elangovan, Ravikrishnan

2018-01-01

Total internal reflection fluorescence (TIRF) microscopy is widely used for selective excitation and high-resolution imaging of fluorophores, and more recently label-free nanosized objects, with high vertical confinement near a liquid-solid interface. Traditionally, high numerical aperture objectives (>1.4) are used to simultaneously generate evanescent waves and collect fluorescence emission signals which limits their use to small area imaging (<0.1 mm2). Objective-based TIRFs are also expensive as they require dichroic mirrors and efficient notch filters to prevent specular reflection within the objective lenses. We have developed a compact 3D module called cTIRF that can generate evanescent waves in microscope glass slides via a planar waveguide illumination. The module can be attached as a fixture to any existing optical microscope, converting it into a TIRF and enabling high signal-to-noise ratio (SNR) fluorescence imaging using any magnification objective. As the incidence optics is perpendicular to the detector, label-free evanescent scattering-based imaging of submicron objects can also be performed without using emission filters. SNR is significantly enhanced in this case as compared to cTIRF alone, as seen through our model experiments performed on latex beads and mammalian cells. Extreme flexibility and the low cost of our approach makes it scalable for limited resource settings.

Atypical Presentation of Iridocorneal Endothelial Syndrome With Band Keratopathy but No Corneal Edema Managed With Descemet Membrane Endothelial Keratoplasty.

PubMed

Zygoura, Vasiliki; Lavy, Itay; Verdijk, Robert M; Santander-García, Diana; Baydoun, Lamis; Dapena, Isabel; Melles, Gerrit R J

2018-04-17

To report an unusual presentation of iridocorneal endothelial (ICE) syndrome associated with band keratopathy and its management with ethylenediamine-tetraacetic acid (EDTA) chelation and Descemet membrane endothelial keratoplasty (DMEK). A 57-year-old female patient presented with unilateral progressive painless visual impairment, corneal band keratopathy, and morphological corneal endothelial changes without corneal edema or any previous ophthalmic, medical, or family history. Routine specular and confocal microscopy imaging, as well as biomicroscopy, best-corrected visual acuity, and pachymetry measurements were performed before and after the surgical procedures. Histopathologic and immunohistochemical evaluations of the surgically excised diseased DM-endothelium were performed. Superficial epithelial keratectomy with EDTA chelation was performed. After an initial period of a few months of corneal clearance, the patient presented with recurrence of visually significant band keratopathy. After 1 year, she underwent retreatment with superficial epithelial keratectomy and EDTA chelation, followed by DMEK. Histopathologic and immunohistochemical analysis showed ICE syndrome. Two years after DMEK surgery, the cornea was still clear and band keratopathy had not recurred. To the best of our knowledge, this is the first case in the literature that reports the association of ICE syndrome with band keratopathy. As band keratopathy recurred shortly after EDTA chelation, endothelial keratoplasty (DMEK) may be indicated to successfully treat such cases.

Effect of laser peripheral iridotomy using argon and neodymium-YAG lasers on corneal endothelial cell density: 7-year longitudinal evaluation.

PubMed

Ono, Takashi; Iida, Masaharu; Sakisaka, Toshihiro; Minami, Keiichiro; Miyata, Kazunori

2018-03-01

To evaluate the changes in corneal endothelial cell density (ECD) over a 7-year period after laser peripheral iridotomy (LPI) using argon and neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers. Retrospective case series. Eyes that underwent prophylactic LPI using argon and Nd:YAG lasers were followed up for 7 years. Central corneal endothelial cells were observed by use of noncontact specular microscopy preoperatively and at 1 and 7 years postoperatively. Changes in ECD and the associations between preoperative ECD and the total energy of the Nd:YAG laser were evaluated. Fifty-one eyes of 51 patients were followed up for 7 years. The ECD significantly decreased after LPI (P < 0.049), and the reduction rate at 1 year after the surgery (1.69 ± 4.80%, 95% CI: 0.34%-3.04%) was significantly higher than the annual reduction rates after 1 year (0.17 ± 0.85%/y, P = 0.036, 95% CI: -0.07% to 0.41%). No association was found between the preoperative ECD and the total laser energy. Long-term evaluation indicated that the reduction in ECD after argon-Nd:YAG laser LPI was present but small during the initial year and was negligible after 1 year.

Shearography for Non-Destructive Evaluation with Applications to BAT Mask Tile Adhesive Bonding and Specular Surface Honeycomb Panels

NASA Technical Reports Server (NTRS)

Lysak, Daniel B.

2003-01-01

In this report we examine the applicability of shearography techniques for nondestructive inspection and evaluation in two unique application areas. In the first application, shearography is used to evaluate the quality of adhesive bonds holding lead tiles to the BAT gamma ray mask for the NASA Swift program. By exciting the mask with a vibration, the more poorly bonded tiles can be distinguished by their greater displacement response, which is readily identifiable in the shearography image. A quantitative analysis is presented that compares the shearography results with a destructive pull test measuring the force at bond failure. Generally speaking, the results show good agreement. Further investigation would be useful to optimize certain test parameters such as vibration frequency and amplitude. The second application is to evaluate the bonding between the skin and core of a honeycomb structure with a specular (mirror-like) surface. In standard shearography techniques, the object under test must have a diffuse surface to generate the speckle patterns in laser light, which are then sheared. A novel configuration using the specular surface as a mirror to image speckles from a diffuser is presented, opening up the use of shearography to a new class of objects that could not have been examined with the traditional approach. This new technique readily identifies large scale bond failures in the panel, demonstrating the validity of this approach. For the particular panel examined here, some scaling issues should be examined further to resolve the measurement scale down to the very small size of the core cells. In addition, further development should be undertaken to determine the general applicability of the new approach and to establish a firm quantitative foundation.

Metrological characterization methods for confocal chromatic line sensors and optical topography sensors

NASA Astrophysics Data System (ADS)

Seppä, Jeremias; Niemelä, Karri; Lassila, Antti

2018-05-01

The increasing use of chromatic confocal technology for, e.g. fast, in-line optical topography, and measuring thickness, roughness and profiles implies a need for the characterization of various aspects of the sensors. Single-point, line and matrix versions of chromatic confocal technology, encoding depth information into wavelength, have been developed. Of these, line sensors are particularly suitable for in-line process measurement. Metrological characterization and development of practical methods for calibration and checking is needed for new optical methods and devices. Compared to, e.g. tactile methods, optical topography measurement techniques have limitations related to light wavelength and coherence, optical properties of the sample including reflectivity, specularity, roughness and colour, and definition of optical versus mechanical surfaces. In this work, metrological characterization methods for optical line sensors were developed for scale magnification and linearity, sensitivity to sample properties, and dynamic characteristics. An accurate depth scale calibration method using a single prototype groove depth sample was developed for a line sensor and validated with laser-interferometric sample tracking, attaining (sub)micrometre level or better than 0.1% scale accuracy. Furthermore, the effect of different surfaces and materials on the measurement and depth scale was studied, in particular slope angle, specularity and colour. In addition, dynamic performance, noise, lateral scale and resolution were measured using the developed methods. In the case of the LCI1200 sensor used in this study, which has a 11.3 mm  ×  2.8 mm measurement range, the instrument depth scale was found to depend only minimally on sample colour, whereas measuring steeply sloped specular surfaces in the peripheral measurement area, in the worst case, caused a somewhat larger relative sample-dependent change (1%) in scale.

Effect of dry air on interface smoothening in reactive sputter deposited Co/Ti multilayer

NASA Astrophysics Data System (ADS)

Biswas, A.; Porwal, A.; Bhattacharya, Debarati; Prajapat, C. L.; Ghosh, Arnab; Nand, Mangla; Nayak, C.; Rai, S.; Jha, S. N.; Singh, M. R.; Bhattacharyya, D.; Basu, S.; Sahoo, N. K.

2017-09-01

Top surface roughness and interface roughness are one of the key elements which determine the performance of X-ray and neutron thin film multilayer devices. It has been observed that by mixing air with argon in sputtering ambience during deposition of Co layers, polarized neutron reflectivity (PNR) of Co/Ti supermirror polarizers can be improved substantially. Cross-sectional HRTEM measurement reveals that sharper interfaces in the supermirror can be achieved in case of deposition of the multilayer under mixed ambience of argon and air. In order to investigate this interface modification mechanism further, in this communication two sets of tri-layer Co/Ti/Co samples and 20-layer Co/Ti periodic multilayer samples have been prepared; in one set all the layers are deposited only under argon ambience and in the other set, Co layers are deposited under a mixed ambience of argon and air. These samples have been characterized by measuring specular and non-specular X-ray reflectivities (GIXR) with X-rays of 1.54 Å wavelength and polarized neutron reflectivity (PNR) with neutron of 2.5 Å wavelength at grazing angle of incidence. It has been observed that the X-ray and neutron specular reflectivities at Bragg peaks of 20 layer periodic multilayer increase when Co layers are deposited under mixed ambience of argon and air. The detail information regarding the effect of air on the interfaces and magnetic properties has been obtained by fitting the measured spectra. The above information has subsequently been supplemented by XRD and magnetic measurements on the samples. XPS and XANES measurements have also been carried out to investigate whether cobalt oxide or cobalt nitride layers are being formed due to use of air in sputtering ambience.

Specular Reflectivity and Hot-Electron Generation in High-Contrast Relativistic Laser-Plasma Interactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kemp, Gregory Elijah

2013-01-01

Ultra-intense laser (> 1018 W/cm2) interactions with matter are capable of producing relativistic electrons which have a variety of applications in state-of-the-art scientific and medical research conducted at universities and national laboratories across the world. Control of various aspects of these hot-electron distributions is highly desired to optimize a particular outcome. Hot-electron generation in low-contrast interactions, where significant amounts of under-dense pre-plasma are present, can be plagued by highly non-linear relativistic laser-plasma instabilities and quasi-static magnetic field generation, often resulting in less than desirable and predictable electron source characteristics. High-contrast interactions offer more controlled interactions but often at the costmore » of overall lower coupling and increased sensitivity to initial target conditions. An experiment studying the differences in hot-electron generation between high and low-contrast pulse interactions with solid density targets was performed on the Titan laser platform at the Jupiter Laser Facility at Lawrence Livermore National Laboratory in Livermore, CA. To date, these hot-electrons generated in the laboratory are not directly observable at the source of the interaction. Instead, indirect studies are performed using state-of-the-art simulations, constrained by the various experimental measurements. These measurements, more-often-than-not, rely on secondary processes generated by the transport of these electrons through the solid density materials which can susceptible to a variety instabilities and target material/geometry effects. Although often neglected in these types of studies, the specularly reflected light can provide invaluable insight as it is directly influenced by the interaction. In this thesis, I address the use of (personally obtained) experimental specular reflectivity measurements to indirectly study hot-electron generation in the context of high-contrast, relativistic laser-plasma interactions.« less

Sliding to predict: vision-based beating heart motion estimation by modeling temporal interactions.

PubMed

Aviles-Rivero, Angelica I; Alsaleh, Samar M; Casals, Alicia

2018-03-01

Technical advancements have been part of modern medical solutions as they promote better surgical alternatives that serve to the benefit of patients. Particularly with cardiovascular surgeries, robotic surgical systems enable surgeons to perform delicate procedures on a beating heart, avoiding the complications of cardiac arrest. This advantage comes with the price of having to deal with a dynamic target which presents technical challenges for the surgical system. In this work, we propose a solution for cardiac motion estimation. Our estimation approach uses a variational framework that guarantees preservation of the complex anatomy of the heart. An advantage of our approach is that it takes into account different disturbances, such as specular reflections and occlusion events. This is achieved by performing a preprocessing step that eliminates the specular highlights and a predicting step, based on a conditional restricted Boltzmann machine, that recovers missing information caused by partial occlusions. We carried out exhaustive experimentations on two datasets, one from a phantom and the other from an in vivo procedure. The results show that our visual approach reaches an average minima in the order of magnitude of [Formula: see text] while preserving the heart's anatomical structure and providing stable values for the Jacobian determinant ranging from 0.917 to 1.015. We also show that our specular elimination approach reaches an accuracy of 99% compared to a ground truth. In terms of prediction, our approach compared favorably against two well-known predictors, NARX and EKF, giving the lowest average RMSE of 0.071. Our approach avoids the risks of using mechanical stabilizers and can also be effective for acquiring the motion of organs other than the heart, such as the lung or other deformable objects.

Interferometric Meteor Head Echo Observations using the Southern Argentina Agile Meteor Radar (SAAMER)

NASA Technical Reports Server (NTRS)

Janches, D.; Hocking, W.; Pifko, S.; Hormaechea, J. L.; Fritts, D. C.; Brunini, C; Michell, R.; Samara, M.

2013-01-01

A radar meteor echo is the radar scattering signature from the free-electrons in a plasma trail generated by entry of extraterrestrial particles into the atmosphere. Three categories of scattering mechanisms exist: specular, nonspecular trails, and head-echoes. Generally, there are two types of radars utilized to detect meteors. Traditional VHF meteor radars (often called all-sky1radars) primarily detect the specular reflection of meteor trails traveling perpendicular to the line of sight of the scattering trail, while High Power and Large Aperture (HPLA) radars efficiently detect meteor head-echoes and, in some cases, non-specular trails. The fact that head-echo measurements can be performed only with HPLA radars limits these studies in several ways. HPLA radars are very sensitive instruments constraining the studies to the lower masses, and these observations cannot be performed continuously because they take place at national observatories with limited allocated observing time. These drawbacks can be addressed by developing head echo observing techniques with modified all-sky meteor radars. In addition, the fact that the simultaneous detection of all different scattering mechanisms can be made with the same instrument, rather than requiring assorted different classes of radars, can help clarify observed differences between the different methodologies. In this study, we demonstrate that such concurrent observations are now possible, enabled by the enhanced design of the Southern Argentina Agile Meteor Radar (SAAMER) deployed at the Estacion Astronomica Rio Grande (EARG) in Tierra del Fuego, Argentina. The results presented here are derived from observations performed over a period of 12 days in August 2011, and include meteoroid dynamical parameter distributions, radiants and estimated masses. Overall, the SAAMER's head echo detections appear to be produced by larger particles than those which have been studied thus far using this technique.

Real-time catheter localization and visualization using three-dimensional echocardiography

NASA Astrophysics Data System (ADS)

Kozlowski, Pawel; Bandaru, Raja Sekhar; D'hooge, Jan; Samset, Eigil

2017-03-01

Real-time three-dimensional transesophageal echocardiography (RT3D-TEE) is increasingly used during minimally invasive cardiac surgeries (MICS). In many cath labs, RT3D-TEE is already one of the requisite tools for image guidance during MICS. However, the visualization of the catheter is not always satisfactory making 3D- TEE challenging to use as the only modality for guidance. We propose a novel technique for better visualization of the catheter along with the cardiac anatomy using TEE alone - exploiting both beamforming and post processing methods. We extended our earlier method called Delay and Standard Deviation (DASD) beamforming to 3D in order to enhance specular reflections. The beam-formed image was further post-processed by the Frangi filter to segment the catheter. Multi-variate visualization techniques enabled us to render both the standard tissue and the DASD beam-formed image on a clinical ultrasound scanner simultaneously. A frame rate of 15 FPS was achieved.

Magnetic domain formation in monolayer nanoparticle films

NASA Astrophysics Data System (ADS)

Maranville, Brian; Krycka, Kathryn; Borchers, Julie; Hogg, Charles; Majetich, Sara; Ijiri, Yumi

2009-03-01

Self-assembled magnetic nanoparticle films offer promise as data storage media, but an understanding of the interactions is missing. Modified Langmuir-Blodgett methods were used to prepare monolayer films of 7 and 11 nm diameter Fe3O4 nanoparticles with large structural domains. Small-angle neutron scattering (SANS) shows a peak at a wavevector Q corresponding to the particle size and spacing, and scattering at intermediate Q indicating possible long-range correlations. We extend to lower Q with off-specular neutron reflectivity, achieving high intensity by sacrificing resolution along one in-plane direction y while retaining high resolution in the other in-plane direction x and the normal direction z. We measure in saturation and zero field to extract magnetic scattering. In high fields, the specular scattering (Qx=0) is increased, consistent with aligned moments. Preliminary results show weak magnetic scattering for nonzero Qx . Since the maximal Qx roughly corresponds to the lowest Q in SANS, the combination of these techniques allows us to quantify field-dependent magnetic domain size.

Correcting geometric and photometric distortion of document images on a smartphone

NASA Astrophysics Data System (ADS)

Simon, Christian; Williem; Park, In Kyu

2015-01-01

A set of document image processing algorithms for improving the optical character recognition (OCR) capability of smartphone applications is presented. The scope of the problem covers the geometric and photometric distortion correction of document images. The proposed framework was developed to satisfy industrial requirements. It is implemented on an off-the-shelf smartphone with limited resources in terms of speed and memory. Geometric distortions, i.e., skew and perspective distortion, are corrected by sending horizontal and vertical vanishing points toward infinity in a downsampled image. Photometric distortion includes image degradation from moiré pattern noise and specular highlights. Moiré pattern noise is removed using low-pass filters with different sizes independently applied to the background and text region. The contrast of the text in a specular highlighted area is enhanced by locally enlarging the intensity difference between the background and text while the noise is suppressed. Intensive experiments indicate that the proposed methods show a consistent and robust performance on a smartphone with a runtime of less than 1 s.

Application of Monte Carlo techniques to transient thermal modeling of cavity radiometers having diffuse-specular surfaces

NASA Technical Reports Server (NTRS)

Mahan, J. R.; Eskin, L. D.

1981-01-01

A viable alternative to the net exchange method of radiative analysis which is equally applicable to diffuse and diffuse-specular enclosures is presented. It is particularly more advantageous to use than the net exchange method in the case of a transient thermal analysis involving conduction and storage of energy as well as radiative exchange. A new quantity, called the distribution factor is defined which replaces the angle factor and the configuration factor. Once obtained, the array of distribution factors for an ensemble of surface elements which define an enclosure permits the instantaneous net radiative heat fluxes to all of the surfaces to be computed directly in terms of the known surface temperatures at that instant. The formulation of the thermal model is described, as is the determination of distribution factors by application of a Monte Carlo analysis. The results show that when fewer than 10,000 packets are emitted, an unsatisfactory approximation for the distribution factors is obtained, but that 10,000 packets is sufficient.

Estimation of photosynthetic capacity using MODIS polarization: 1988 proposal to NASA Headquarters

NASA Technical Reports Server (NTRS)

Vanderbilt, Vern C.

1992-01-01

The remote sensing community has clearly identified the utility of NDVI (normalized difference vegetation index) and SR (simple ratio) and other vegetation indices for estimating such metrics of landscape ecology as green foliar biomass, photosynthetic capacity, and net primary production. Both theoretical and empirical investigations have established cause and effect relationships between the photosynthetic process in plant canopies and these combinations of remotely sensed data. Yet it has also been established that the relationships exhibit considerable variability that appears to be ecosystem-dependent and may represent a source of ecologically important information. The overall hypothesis of this proposal is that the ecosystem-dependent variability in the various vegetation indices is in part attributable to the effects of specular reflection. The polarization channels on MODIS provide the potential to estimate this specularly reflected light and allow the modification of the vegetation indices to better measure the photosynthetic process in plant canopies. In addition, these polarization channels potentially provide additional ecologically important information about the plant canopy.

ERTS-1 anomalous dark patches

NASA Technical Reports Server (NTRS)

Strong, A. E. (Principal Investigator)

1973-01-01

The author has identified the following significant results. Through combined use of imagery from ERTS-1 and NOAA-2 satellites was found that when the sun elevation exceeds 55 degrees, the ERTS-1 imagery is subject to considerable contamination by sunlight even though the actual specular point is nearly 300 nautical miles from nadir. Based on sea surface wave slope information, a wind speed of 10 knots will theoretically provide approximately 0.5 percent incident solar reflectance under observed ERTS multispectral scanner detectors. This reflectance nearly doubles under the influence of a 20 knot wind. The most pronounced effect occurs in areas of calm water where anomalous dark patches are observed. Calm water at distances from the specular point found in ERTS scenes will reflect no solar energy to the multispectral scanner, making these regions stand out as dark areas in all bands in an ocean scene otherwise comprosed by a general diffuse sunlight from rougher ocean surfaces. Anomalous dark patches in the outer parts of the glitter zones may explain the unusual appearance of some scenes.

Quantum transport in new two-dimensional heterostructures: Thin films of topological insulators, phosphorene

NASA Astrophysics Data System (ADS)

Majidi, Leyla; Zare, Moslem; Asgari, Reza

2018-06-01

The unusual features of the charge and spin transport characteristics are investigated in new two-dimensional heterostructures. Intraband specular Andreev reflection is realized in a topological insulator thin film normal/superconducting junction in the presence of a gate electric field. Perfect specular electron-hole conversion is shown for different excitation energy values in a wide experimentally available range of the electric field and also for all angles of incidence when the excitation energy has a particular value. It is further demonstrated that the transmission probabilities of the incoming electrons from different spin subbands to the monolayer phosphorene ferromagnetic/normal/ferromagnetic (F/N/F) hybrid structure have different behavior with the angle of incidence and perfect transmission occurs at defined angles of incidence to the proposed structure with different length of the N region, and different alignments of magnetization vectors. Moreover, the sign change of the spin-current density is demonstrated by tuning the chemical potential and exchange field of the F region.

Galerkin methods for Boltzmann-Poisson transport with reflection conditions on rough boundaries

NASA Astrophysics Data System (ADS)

Morales Escalante, José A.; Gamba, Irene M.

2018-06-01

We consider in this paper the mathematical and numerical modeling of reflective boundary conditions (BC) associated to Boltzmann-Poisson systems, including diffusive reflection in addition to specularity, in the context of electron transport in semiconductor device modeling at nano scales, and their implementation in Discontinuous Galerkin (DG) schemes. We study these BC on the physical boundaries of the device and develop a numerical approximation to model an insulating boundary condition, or equivalently, a pointwise zero flux mathematical condition for the electron transport equation. Such condition balances the incident and reflective momentum flux at the microscopic level, pointwise at the boundary, in the case of a more general mixed reflection with momentum dependant specularity probability p (k →). We compare the computational prediction of physical observables given by the numerical implementation of these different reflection conditions in our DG scheme for BP models, and observe that the diffusive condition influences the kinetic moments over the whole domain in position space.

The effect of leveling coatings on the atomic oxygen durability of solar concentrator surfaces

NASA Technical Reports Server (NTRS)

Degroh, Kim K.; Dever, Therese M.; Quinn, William F.

1990-01-01

Space power systems for Space Station Freedom will be exposed to the harsh environment of low earth orbit (LEO). Neutral atomic oxygen is the major constituent in LEO and has the potential of severely reducing the efficiency of solar dynamic power systems through degradation of the concentrator surfaces. Several transparent dielectric thin films have been found to provide atomic oxygen protection, but atomic oxygen undercutting at inherent defect sites is still a threat to solar dynamic power system survivability. Leveling coatings smooth microscopically rough surfaces, thus eliminating potential defect sites prone to oxidation attack on concentrator surfaces. The ability of leveling coatings to improve the atomic oxygen durability of concentrator surfaces was investigated. The application of a EPO-TEK 377 epoxy leveling coating on a graphite epoxy substrate resulted in an increase in solar specular reflectance, a decrease in the atomic oxygen defect density by an order of magnitude and a corresponding order of magnitude decrease in the percent loss of specular reflectance during atomic oxygen plasma ashing.

Corrosion of Highly Specular Vapor Deposited Aluminum (VDA) on Earthshade Door Sandwich Structure

NASA Technical Reports Server (NTRS)

Plaskon, Daniel; Hsieh, Cheng

2003-01-01

High-resolution infrared (IR) imaging requires spacecraft instrument design that is tightly coupled with overall thermal control design. The JPL Tropospheric Emission Spectrometer (TES) instrument measures the 3-dimensional distribution of ozone and its precursors in the lower atmosphere on a global scale. The TES earthshade must protect the 180-K radiator and the 230-K radiator from the Earth IR and albedo. Requirements for specularity, emissivity, and solar absorptance of inner surfaces could only be met with vapor deposited aluminum (VDA). Circumstances leading to corrosion of the VDA are described. Innovative materials and processing to meet the optical and thermal cycle requirements were developed. Examples of scanning electronmicroscope (SEM), atomic force microscope (AFM), and other surface analysis techniques used in failure analysis, problem solving, and process development are given. Materials and process selection criteria and development test results are presented in a decision matrix. Examples of conditions promoting and preventing galvanic corrosion between VDA and graphite fiber-reinforced laminates are provided.

Simulating synchrotron radiation in accelerators including diffuse and specular reflections

DOE PAGES

Dugan, G.; Sagan, D.

2017-02-24

An accurate calculation of the synchrotron radiation flux within the vacuum chamber of an accelerator is needed for a number of applications. These include simulations of electron cloud effects and the design of radiation masking systems. To properly simulate the synchrotron radiation, it is important to include the scattering of the radiation at the vacuum chamber walls. To this end, a program called synrad3d has been developed which simulates the production and propagation of synchrotron radiation using a collection of photons. Photons generated by a charged particle beam are tracked from birth until they strike the vacuum chamber wall wheremore » the photon is either absorbed or scattered. Both specular and diffuse scattering is simulated. If a photon is scattered, it is further tracked through multiple encounters with the wall until it is finally absorbed. This paper describes the synrad3d program, with a focus on the details of its scattering model, and presents some examples of the program’s use.« less

Surface color perception under two illuminants: the second illuminant reduces color constancy

NASA Technical Reports Server (NTRS)

Yang, Joong Nam; Shevell, Steven K.

2003-01-01

This study investigates color perception in a scene with two different illuminants. The two illuminants, in opposite corners, simultaneously shine on a (simulated) scene with an opaque dividing wall, which controls how much of the scene is illuminated by each source. In the first experiment, the height of the dividing wall was varied. This changed the amount of each illuminant reaching objects on the opposite side of the wall. Results showed that the degree of color constancy decreased when a region on one side of the wall had cues to both illuminants, suggesting that cues from the second illuminant are detrimental to color constancy. In a later experiment, color constancy was found to improve when the specular highlight cues from the second illuminant were altered to be consistent with the first illuminant. This corroborates the influence of specular highlights in surface color perception, and suggests that the reduced color constancy in the first experiment is due to the inconsistent, though physically correct, cues from the two illuminants.

Thermally induced gas flows in ratchet channels with diffuse and specular boundaries

PubMed Central

Shahabi, Vahid; Baier, Tobias; Roohi, Ehsan; Hardt, Steffen

2017-01-01

A net gas flow can be induced in the gap between periodically structured surfaces held at fixed but different temperatures when the reflection symmetry along the channel axis is broken. Such a situation arises when one surface features a ratchet structure and can be augmented by altering the boundary conditions on different parts of this surface, with some regions reflecting specularly and others diffusely. In order to investigate the physical mechanisms inducing the flow in this configuration at various Knudsen numbers and geometric configurations, direct simulation Monte Carlo (DSMC) simulations are employed using transient adaptive subcells for collision partner selection. At large Knudsen numbers the results compare favorably with analytical expressions, while for small Knudsen numbers a qualitative explanation for the flow in the strong temperature inhomogeneity at the tips of the ratchet is provided. A detailed investigation of the performance for various ratchet geometries suggests optimum working conditions for a Knudsen pump based on this mechanism. PMID:28128309

Reflection high energy electron diffraction study of nitrogen plasma interactions with a GaAs (100) surface

NASA Astrophysics Data System (ADS)

Hauenstein, R. J.; Collins, D. A.; Cai, X. P.; O'Steen, M. L.; McGill, T. C.

1995-05-01

Effect of a nitrogen electron-cyclotron-resonance (ECR) microwave plasma on near-surface composition, crystal structure, and morphology of the As-stabilized GaAs (100) surface is investigated with the use of digitally image-processed in situ reflection high energy electron diffraction. Nitridation is performed on molecular beam epitaxially (MBE) grown GaAs surfaces near 600 °C under typical conditions for ECR microwave plasma-assisted MBE growth of GaN films on GaAs. Brief plasma exposures (≊3-5 s) are shown to result in a specular, coherently strained, relatively stable, GaN film approximately one monolayer in thickness, which can be commensurately overgrown with GaAs while longer exposures (up to 1 min) result in incommensurate zincblende epitaxial GaN island structures. Specular and nonspecular film formations are explained in terms of N-for-As surface and subsurface anion exchange reactions, respectively. Commensurate growth of ultrathin buried GaN layers in GaAs is achieved.

Flexible and polarization-controllable diffusion metasurface with optical transparency

NASA Astrophysics Data System (ADS)

Zhuang, Yaqiang; Wang, Guangming; Liang, Jiangang; Cai, Tong; Guo, Wenlong; Zhang, Qingfeng

2017-11-01

In this paper, a novel coding metasurface is proposed to realize polarization-controllable diffusion scattering. The anisotropic Jerusalem-cross unit cell is employed as the basic coding element due to its polarization-dependent phase response. The isotropic random coding sequence is firstly designed to obtain diffusion scattering, and the anisotropic random coding sequence is subsequently realized by adding different periodic coding sequences to the original isotropic one along different directions. For demonstration, we designed and fabricated a flexible polarization-controllable diffusion metasurface (PCDM) with both chessboard diffusion and hedge diffusion under different polarizations. The specular scattering reduction performance of the anisotropic metasurface is better than the isotropic one because the scattered energies are redirected away from the specular reflection direction. For potential applications, the flexible PCDM wrapped around a cylinder structure is investigated and tested for polarization-controllable diffusion scattering. The numerical and experimental results coincide well, indicating anisotropic low scatterings with comparable performances. This paper provides an alternative approach for designing high-performance, flexible, low-scattering platforms.

An assessment of regional differences in corneal thickness in normal human eyes, using the Orbscan II or ultrasound pachymetry.

PubMed

Doughty, Michael J; Jonuscheit, Sven

2007-04-01

In recent years, there has been increasing interest in the characteristics of the peripheral cornea close to the limbus, in both tonometry measures and refractive surgery, but there is relatively little information on these characteristics as provided by modern day pachymetry instruments such as the Orbscan (Bausch & Lomb, Rochester, New York). The current study was therefore undertaken to assess the corneal thickness profile along the horizontal meridian by this scanning slit light method, comparing the data with that obtained with an ultrasound pachymeter. Noncontact specular microscopy was first performed on 17 adults (aged between 20 and 64 years) to check that the corneas were normal. Then, 3 assessments of the corneal thickness profile across the horizontal meridian were taken using the Orbscan II, and both the regional map data (7-mm-diameter measurement ring, 1-mm sample zones) and the point data from the numerical pachymetry output were used to extract data at specific locations nominally 0.5 mm apart. Ultrasound pachymetry (under topical anesthesia with benoxinate 0.4%) was then used to obtain thickness values at central, mid-peripheral (2.75 mm), and peripheral locations close to the limbus (4.5 mm). Specular microscopy yielded mean thickness of 0.529 +/- 0.032 mm, whereas single-point Orbscan readings at the geometric center of the cornea averaged 0.579 +/- 0.037 mm. Orbscan readings around the 7-mm-diameter measurement zone along the horizontal meridian averaged 0.681 +/- 0.034 mm (i.e., were 0.101 mm or 17.6% greater; P < 0.001). Mid-peripheral readings taken from the numerical maps at 2.5 to 3.0 mm averaged 0.645 mm (or 11% higher than central point readings), whereas peripheral readings between 4.0 and 4.5 mm averaged 0.727 mm (i.e., 26% higher than central point values). In marked contrast, ultrasound readings in the mid-periphery (2.75 mm) averaged just 0.553 mm (or 5.5% greater than the central corneal thickness [CCT]) and just 0.612 mm (i.e., 16.6% higher) in the periphery (4.5 mm). CCT profiles generated from the Orbscan numerical output across the horizontal meridian showed a predictable progressive increase in thickness from the center to the 4.5-mm location on both the temporal and nasal side. The mean differences between the Orbscan II and ultrasound pachymetry measures were thus not constant across the cornea. Without correction, these differences were close to 0.05 mm at the center but more than 0.100 mm at the peripheral sites, and proportional differences persisted after application of the default acoustic factor of 0.92 for the Orbscan readings. Orbscan II and ultrasound pachymetry measures generate a rather different profile for corneal thickness. The data from the 2 techniques should be considered as reporting different characteristics, rather than attempts being made to align Orbscan measurements to those of the ultrasound method. A single acoustic correction factor cannot be logically applied to all corneal thickness measures made with an Orbscan II.

[Embryo selection in IVF/ICSI cycles using time-lapse microscopy and the clinical outcomes].

PubMed

Chen, Minghao; Huang, Jun; Zhong, Ying; Quan, Song

2015-12-01

To compare the clinical outcomes of embryos selected using time-lapse microscopy and traditional morphological method in IVF/ICSI cycles and evaluate the clinical value of time-lapse microscopy in early embryo monitoring and selection. e retrospectively analyzed the clinical data of 139 IVF/ICSI cycles with embryo selection based on time-lapse monitoring (TLM group, n=68) and traditional morphological method (control group, n=71). The βHCG-positive rate, clinical pregnancy rate and embryo implantation rate were compared between the 2 groups. Subgroup analysis was performed in view of female patients age and the fertilization type. The βHCG-positive rate, clinical pregnancy rate and implantation rate were 66.2%, 61.8% and 47.1% in TLM group, significantly higher than those in the control group (47.9%, 43.7% and 30.3%, respectively; P<0.05). Compared with patients below 30 years of age, patients aged between 31 and 35 years benefited more from time-lapse monitoring with improved clinical outcomes. time-lapse monitoring significantly increased the βHCG-positive rate, clinical pregnancy rate and implantation rate for patients undergoing IVF cycles, but not for those undergoing ICSI or TESA cycles. Compared with those selected using traditional morphological method, the embryos selected with time-lapse microscopy have better clinical outcomes, especially in older patients (31-35 years of age) and in IVF cycles.

Real-time, non-invasive microscopic confirmation of clinical diagnosis of bullous pemphigoid using in vivo reflectance confocal microscopy.

PubMed

Ardigò, M; Agozzino, M; Amorosi, B; Moscarella, E; Cota, C; de Abreu, L; Berardesca, E

2014-05-01

Bullous pemphigoid is an autoimmune disease affecting prevalently the elder. In vivo reflectance confocal microscopy is a non-invasive technique for real-time imaging of the skin with cellular-level resolution. No previous data has been reported about confocal microscopy of bullous pemphigoid. Aim of this preliminary study is the evaluation of the potential of in vivo reflectance confocal microscopy for real-time, microscopical confirmation of clinical bullous pemphigoid diagnosis. A total of nine lesions from patients affected by pemphigoid underwent in vivo reflectance confocal microscopy before histological examination. In our preliminary study, confocal microscopy showed high grade of correspondence to histopathology. In particular, presence of sub-epidermal cleft and variable amount of oedema of the upper dermis associated with inflammatory cells infiltration were seen as prevalent confocal features in the bullous lesions considered. Differently, in urticarial lesions, no specific features could be appreciated at confocal analysis beside the presence of signs of spongiosis and perivascular inflammation. Confocal microscopy seems to be useful for in vivo, microscopical confirmation of the clinical suspect of bullous pemphigoid and for biopsy site selection in urticarial lesions to obtain a more significant specimen for histopathological examination. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

40 CFR 59.412 - Incorporations by reference.

Code of Federal Regulations, 2010 CFR

2010-07-01

... address: American Society for Testing and Materials (ASTM), 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959. (1) ASTM Method C 1315-95, Standard Specification for Liquid Membrane-Forming Compounds....401, Concrete curing and sealing compound. (2) ASTM Method D 523-89, Standard Test Method for Specular...

Precision Antenna Measurement System (PAMS) Engineering Services

DTIC Science & Technology

1978-04-01

8217) = receiving antenna gain for vertical polarization. The total direct signal power is Following Beck /narn and Spizzachino , the specular component...method may be valid for the problem. Very often, however, the physical optics 92 approach baaed on a solution of the wave equation will have to

RGB imaging system for monitoring of skin vascular malformation's laser therapy

NASA Astrophysics Data System (ADS)

Jakovels, Dainis; Kuzmina, Ilona; Berzina, Anna; Spigulis, Janis

2012-06-01

A prototype RGB imaging system for mapping of skin chromophores consists of a commercial RGB CMOS sensor, RGB LEDs ring-light illuminator and orthogonally orientated polarizers for reducing specular reflectance. The system was used for monitoring of vascular malformations (hemagiomas and telangiectasias) therapy.

Retroreflector for Photonic Doppler Velocimetry

DTIC Science & Technology

2009-03-01

devices . . . . . . . . . . . . . . 58 3.24 SOI device after DRIE and hinge deposition . . . . . . . . . . . . . 59 3.25 MEMS micromirror etch hole layout...61 3.26 Amplitude transmittance functions for MEMS micromirrors . . . . 62 3.27 Diffraction pattern of a square flat...weight of micromirror . . . . . . . . . . . . . . . . . 54 tA amplitude transmittance function . . . . . . . . . . . . . . . . . . . 62 Rspec specular

Time delay estimation using new spectral and adaptive filtering methods with applications to underwater target detection

NASA Astrophysics Data System (ADS)

Hasan, Mohammed A.

1997-11-01

In this dissertation, we present several novel approaches for detection and identification of targets of arbitrary shapes from the acoustic backscattered data and using the incident waveform. This problem is formulated as time- delay estimation and sinusoidal frequency estimation problems which both have applications in many other important areas in signal processing. Solving time-delay estimation problem allows the identification of the specular components in the backscattered signal from elastic and non-elastic targets. Thus, accurate estimation of these time delays would help in determining the existence of certain clues for detecting targets. Several new methods for solving these two problems in the time, frequency and wavelet domains are developed. In the time domain, a new block fast transversal filter (BFTF) is proposed for a fast implementation of the least squares (LS) method. This BFTF algorithm is derived by using data-related constrained block-LS cost function to guarantee global optimality. The new soft-constrained algorithm provides an efficient way of transferring weight information between blocks of data and thus it is computationally very efficient compared with other LS- based schemes. Additionally, the tracking ability of the algorithm can be controlled by varying the block length and/or a soft constrained parameter. The effectiveness of this algorithm is tested on several underwater acoustic backscattered data for elastic targets and non-elastic (cement chunk) objects. In the frequency domain, the time-delay estimation problem is converted to a sinusoidal frequency estimation problem by using the discrete Fourier transform. Then, the lagged sample covariance matrices of the resulting signal are computed and studied in terms of their eigen- structure. These matrices are shown to be robust and effective in extracting bases for the signal and noise subspaces. New MUSIC and matrix pencil-based methods are derived these subspaces. The effectiveness of the method is demonstrated on the problem of detection of multiple specular components in the acoustic backscattered data. Finally, a method for the estimation of time delays using wavelet decomposition is derived. The sub-band adaptive filtering uses discrete wavelet transform for multi- resolution or sub-band decomposition. Joint time delay estimation for identifying multi-specular components and subsequent adaptive filtering processes are performed on the signal in each sub-band. This would provide multiple 'look' of the signal at different resolution scale which results in more accurate estimates for delays associated with the specular components. Simulation results on the simulated and real shallow water data are provided which show the promise of this new scheme for target detection in a heavy cluttered environment.

Tidal Currents between Titan's Seas Detected by Solar Glints

NASA Astrophysics Data System (ADS)

Sotin, C.; Barnes, J. W.; Lawrence, K. J.; Soderblom, J. M.; Audi, E.; Brown, R. H.; Le Mouelic, S.; Baines, K. H.; Buratti, B. J.; Clark, R. N.; Nicholson, P. D.

2015-12-01

Titan is the only place in the solar system, besides Earth, to have stable bodies of liquids on its surface. The three large seas and most of the lakes are located in the northern pole area [1]. They are major reservoirs of organic material [2]. Questions related to the variability in composition of the seas [2] and their interaction [3] can be addressed by dedicated observations. For this purpose, the Visual and Infrared Mapping Spectrometer (VIMS) observed the area between Ligeia Mare and Kraken Mare, Titan's two largest seas on February 12, 2015. The location of the specular point was close to the strait that has been suggested to link Ligeia and Kraken [4]. As demonstrated by previous observations of specular reflections on the lakes and seas [5, 6], such observations provide a means to assess the presence of liquids and the dynamics of the liquid surface. The VIMS observation provides images of the strait, named Trevize fretum, with a footprint of about 3 km. It shows a remarkable correlation with the radar images, suggesting that no major changes in the level of the seas have occurred in the last 10 years, a third of a Titan year. Very strong values of I/F at 5-μm suggest specular reflection away from the specular point on the Ligiea outlet. This is consistent with the presence of waves which can be generated by either winds or strong currents between Kraken Mare and Ligeia mare. Such currents can be generated during Titan's orbital motion around Saturn. We have investigated the volume of liquids that would transit through Trevize fretum during a Titan day and have found that the flow would be in a turbulent regime for the value of the mean anomaly at the time of the VIMS observation. Although subsurface communication between the two seas cannot be ruled out, the present observation underlines the role of the strait in providing exchange of fluids between the two large seas. This work has been performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA. [1] Stofan et al. (2007) Nature, 445, 61-64. [2] Lorenz et al. (2014) Icarus, 237, 9-15. [3] Tokano et al. (2014) Icarus, 242, 188-201. [4] Sotin et al. (2014), AGU, P43C-3999. [5] Soderblom et al. (2012) Icarus, 220, 744-751. [6] Barnes et al. (2013) Astrophysical J., 777, 161.

Optimization of illumination for a diffuse-spectroscopy-based early melanoma diagnostic imager

NASA Astrophysics Data System (ADS)

Rawicz, Andrew H.; Melnyk, Ivan; Oldham, Bradley

2004-10-01

An optical system injecting light directly to the skin and collecting the backscattered portion of the light that has been spectrally modified within the skin has been designed and fabricated. This method reduces the noise generated by the specular component practically to zero. The initial device involved a single channel, optical-fibre-based illuminator and collector connected with a spectroscope. The single channel probing head scanned the skin using a mechanical shifting device. Seven clinical tests performed on patients with suspect skin lesions have been tested with our device, and later biopsy was taken as a "gold standard" procedure. Three cases proved to be melanoma and our spectra indicated differences from those collected from non-melanoma lesions. The process of collecting spectral data was time consuming (about 30 min) and thus not acceptable for a medical procedure. To accelerate the process of data collection from the skin, using the same principle of diffuse spectroscopy, an imaging device was conceived which is able to collect the skin spectral response at once from a relatively sizeable skin area. The requirement of negligible specular component was considered of paramount importance. Two possible approaches are feasible to satisfy this requirement: 1. Collection of backscattered light directly from the skin 2. Injection of illuminating light directly to the skin without creating reflections directly from skin. We decided to use the second approach and construct a circular, circumferential illuminator with angled light injection. Before fabricating this illuminator, a thorough analysis was performed to optimize its radius and angle of injection in order to receive the highest uniformity of diffuse light in the skin. Monte-Carlo simulation was applied to a three layer skin approximation. Only three layers were considered due to the assumption that the device must be able to diagnose early melanoma before reaching metastasis. The results of the simulation are presented.

Clinical diagnosis of oral erosive lichen planus by direct oral microscopy

PubMed Central

Drogoszewska, Barbara; Polcyn, Adam; Michcik, Adam

2014-01-01

Introduction Direct oral microscopy is a novel, non-invasive diagnostic technique that aids clinical examination of the oral cavity. The basic principles of this method derive from colposcopy and dermoscopy. The principle is to reveal precancerous lesions of oral mucosae in their subclinical phase in order to begin their treatment as early as possible and prevent malignant transformation. Oral lichen planus (OLP) is an autoimmune, inflammatory, chronic disease affecting oral mucous membranes. Buccal mucosae are most often affected. Aim To describe the in vivo picture of erosive OLP in direct oral microscopy in terms of the pattern and density of subepithelial blood vessels, surface texture, color, transparency and borders of the lesions. The study also demonstrates the utility of the method in the selection of the most appropriate biopsy site. Material and methods A total of 30 patients with erosive OLP were examined. Clinical examination of the oral cavity with the naked eye was performed, followed by direct oral microscopy. The most appropriate biopsy sites based on both examinations were chosen for every individual and biopsies were taken for histopathological evaluation. Results Biopsies obtained based on direct oral microscopy revealed dysplasia in 16 patients (53.3%). Biopsies obtained based on clinical examination with the naked eye revealed dysplasia in 3 cases (10%). Conclusions Direct oral microscopy makes it possible to obtain a repeated picture of erosive OLP and constitutes an alternative to the clinical examination with the naked eye in election of the most appropriate biopsy site. Thus, introduction of the most accurate and early therapy is possible. PMID:25254007

STED super-resolution microscopy of clinical paraffin-embedded human rectal cancer tissue.

PubMed

Ilgen, Peter; Stoldt, Stefan; Conradi, Lena-Christin; Wurm, Christian Andreas; Rüschoff, Josef; Ghadimi, B Michael; Liersch, Torsten; Jakobs, Stefan

2014-01-01

Formalin fixed and paraffin-embedded human tissue resected during cancer surgery is indispensable for diagnostic and therapeutic purposes and represents a vast and largely unexploited resource for research. Optical microscopy of such specimen is curtailed by the diffraction-limited resolution of conventional optical microscopy. To overcome this limitation, we used STED super-resolution microscopy enabling optical resolution well below the diffraction barrier. We visualized nanoscale protein distributions in sections of well-annotated paraffin-embedded human rectal cancer tissue stored in a clinical repository. Using antisera against several mitochondrial proteins, STED microscopy revealed distinct sub-mitochondrial protein distributions, suggesting a high level of structural preservation. Analysis of human tissues stored for up to 17 years demonstrated that these samples were still amenable for super-resolution microscopy. STED microscopy of sections of HER2 positive rectal adenocarcinoma revealed details in the surface and intracellular HER2 distribution that were blurred in the corresponding conventional images, demonstrating the potential of super-resolution microscopy to explore the thus far largely untapped nanoscale regime in tissues stored in biorepositories.

STED Super-Resolution Microscopy of Clinical Paraffin-Embedded Human Rectal Cancer Tissue

PubMed Central

Wurm, Christian Andreas; Rüschoff, Josef; Ghadimi, B. Michael; Liersch, Torsten; Jakobs, Stefan

2014-01-01

Formalin fixed and paraffin-embedded human tissue resected during cancer surgery is indispensable for diagnostic and therapeutic purposes and represents a vast and largely unexploited resource for research. Optical microscopy of such specimen is curtailed by the diffraction-limited resolution of conventional optical microscopy. To overcome this limitation, we used STED super-resolution microscopy enabling optical resolution well below the diffraction barrier. We visualized nanoscale protein distributions in sections of well-annotated paraffin-embedded human rectal cancer tissue stored in a clinical repository. Using antisera against several mitochondrial proteins, STED microscopy revealed distinct sub-mitochondrial protein distributions, suggesting a high level of structural preservation. Analysis of human tissues stored for up to 17 years demonstrated that these samples were still amenable for super-resolution microscopy. STED microscopy of sections of HER2 positive rectal adenocarcinoma revealed details in the surface and intracellular HER2 distribution that were blurred in the corresponding conventional images, demonstrating the potential of super-resolution microscopy to explore the thus far largely untapped nanoscale regime in tissues stored in biorepositories. PMID:25025184

Thermal Coatings Seminar Series Training Part 1: Properties of Thermal Coatings

NASA Technical Reports Server (NTRS)

Triolo, Jack

2015-01-01

This course will present an overview of a variety of thermal coatings-related topics, including: coating types and availability, thermal properties measurements, environmental testing (lab and in-flight), environmental impacts, contamination impacts, contamination liabilities, determination of BOLEOL values, and what does specularity mean to the thermal engineer.

A Study of Bi-Directional Reflectance Distribution Functions and Their Effect on Infrared Signature Models

DTIC Science & Technology

2007-03-01

66 3.5.1 Specular Reflection Assumption . . . . . . . . . . . . . . . . . . . 70 3.5.2 Radiosity ...69 3.31. Radiosity Algorithm Flowchart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 3.32. POV...3.5.2 Radiosity . The first algorithm implemented to attempt to hemispher- ically integrate the irradiance contribution was classical radiosity as

Thermal Coatings Seminar Series Training Part 2: Environmental Effects

NASA Technical Reports Server (NTRS)

Triolo, Jack

2015-01-01

This course will present an overview of a variety of thermal coatings-related topics, including: coating types and availability, thermal properties measurements, environmental testing (lab and in-flight), environmental impacts, contamination impacts, contamination liabilities, determination of BOLEOL values, and what does specularity mean to the thermal engineer.

Foil Panel Mirrors for Nonimaging Applications

NASA Technical Reports Server (NTRS)

Kuyper, D. J.; Castillo, A. A.

1984-01-01

Large durable, lightweight mirrors made by bonding thick aluminum foil to honeycomb panels or other rigid, flat backings. Mirrors suitable for use as infrared shields, telescope doors, solar-furnance doors, advertising displays, or other reflectors that require low thermal emissivity and high specularity but do not require precise surface figure necessary for imaging.

A Bayesian Method for Managing Uncertainties Relating to Distributed Multistatic Sensor Search

DTIC Science & Technology

2006-07-01

before - detect process. There will also be an increased probability of high signal-to-noise ratio (SNR) detections associated with specular and near...and high target strength and high Doppler opportunities give rise to the expectation of an increased number of detections that could feed a track

Non-destructive Techniques for Classifying Aircraft Coating Degradation

DTIC Science & Technology

2015-03-26

model is bidirectional reflectance distribution func- tions ( BRDF ) which describes how much radiation is reflected for each solid angle and each...incident angle. An intermediate model between ideal reflectors and BRDF is to assume all reflectance is a combination of diffuse and specular reflectance...19 K-Fold Cross Validation

Nonimaging light concentration using total internal reflection films.

PubMed

Ouellette, G; Waltham, C E; Drees, R M; Poon, A; Schubank, R; Whitehead, L A

1992-05-01

We present a method of fabricating nonimaging light concentrators from total internal reflection film. A prototype has been made and tested and found to operate in agreement with predictions of ray-tracing codes. The performance of the prototype is comparable with that of concentrators made from specular reflecting materials.

Cost-effectiveness of malaria diagnosis using rapid diagnostic tests compared to microscopy or clinical symptoms alone in Afghanistan.

PubMed

Hansen, Kristian S; Grieve, Eleanor; Mikhail, Amy; Mayan, Ismail; Mohammed, Nader; Anwar, Mohammed; Baktash, Sayed H; Drake, Thomas L; Whitty, Christopher J M; Rowland, Mark W; Leslie, Toby J

2015-05-28

Improving access to parasitological diagnosis of malaria is a central strategy for control and elimination of the disease. Malaria rapid diagnostic tests (RDTs) are relatively easy to perform and could be used in primary level clinics to increase coverage of diagnostics and improve treatment of malaria. A cost-effectiveness analysis was undertaken of RDT-based diagnosis in public health sector facilities in Afghanistan comparing the societal and health sector costs of RDTs versus microscopy and RDTs versus clinical diagnosis in low and moderate transmission areas. The effect measure was 'appropriate treatment for malaria' defined using a reference diagnosis. Effects were obtained from a recent trial of RDTs in 22 public health centres with cost data collected directly from health centres and from patients enrolled in the trial. Decision models were used to compare the cost of RDT diagnosis versus the current diagnostic method in use at the clinic per appropriately treated case (incremental cost-effectiveness ratio, ICER). RDT diagnosis of Plasmodium vivax and Plasmodium falciparum malaria in patients with uncomplicated febrile illness had higher effectiveness and lower cost compared to microscopy and was cost-effective across the moderate and low transmission settings. RDTs remained cost-effective when microscopy was used for other clinical purposes. In the low transmission setting, RDTs were much more effective than clinical diagnosis (65.2% (212/325) vs 12.5% (40/321)) but at an additional cost (ICER) of US$4.5 per appropriately treated patient including a health sector cost (ICER) of US$2.5 and household cost of US$2.0. Sensitivity analysis, which varied drug costs, indicated that RDTs would remain cost-effective if artemisinin combination therapy was used for treating both P. vivax and P. falciparum. Cost-effectiveness of microscopy relative to RDT is further reduced if the former is used exclusively for malaria diagnosis. In the health service setting of Afghanistan, RDTs are a cost-effective intervention compared to microscopy. RDTs remain cost-effective across a range of drug costs and if microscopy is used for a range of diagnostic services. RDTs have significant advantages over clinical diagnosis with minor increases in the cost of service provision. The trial was registered at ClinicalTrials.gov under identifier NCT00935688.

Direct Microscopy: A Useful Tool to Diagnose Oral Candidiasis in Children and Adolescents.

PubMed

Marty, Mathieu; Bourrat, Emmanuelle; Vaysse, Frédéric; Bonner, Mark; Bailleul-Forestier, Isabelle

2015-12-01

Oral candidiasis is one of the most common opportunistic fungal infections of the oral cavity in human. Among children, this condition represents one of the most frequent affecting the mucosa. Although most diagnoses are made based on clinical signs and features, a microbiological analysis is sometimes necessary. We performed a literature review on the diagnosis of oral candidiasis to identify the techniques most commonly employed in routine clinical practice. A Medline-PubMed search covering the last 10 years was performed. Microbiological techniques were used in cases requiring confirmation of the clinical diagnosis. In such cases, direct microscopy was the method most commonly used for diagnosing candidiasis. Direct microscopy appears as the method of choice for confirming clinical diagnosis and could become a routine chair-side technique.

Going glass to digital: virtual microscopy as a simulation-based revolution in pathology and laboratory science.

PubMed

Nelson, Danielle; Ziv, Amitai; Bandali, Karim S

2012-10-01

The recent technological advance of digital high resolution imaging has allowed the field of pathology and medical laboratory science to undergo a dramatic transformation with the incorporation of virtual microscopy as a simulation-based educational and diagnostic tool. This transformation has correlated with an overall increase in the use of simulation in medicine in an effort to address dwindling clinical resource availability and patient safety issues currently facing the modern healthcare system. Virtual microscopy represents one such simulation-based technology that has the potential to enhance student learning and readiness to practice while revolutionising the ability to clinically diagnose pathology collaboratively across the world. While understanding that a substantial amount of literature already exists on virtual microscopy, much more research is still required to elucidate the full capabilities of this technology. This review explores the use of virtual microscopy in medical education and disease diagnosis with a unique focus on key requirements needed to take this technology to the next level in its use in medical education and clinical practice.

Republished: going glass to digital: virtual microscopy as a simulation-based revolution in pathology and laboratory science.

PubMed

Nelson, Danielle; Ziv, Amitai; Bandali, Karim S

2013-10-01

The recent technological advance of digital high resolution imaging has allowed the field of pathology and medical laboratory science to undergo a dramatic transformation with the incorporation of virtual microscopy as a simulation-based educational and diagnostic tool. This transformation has correlated with an overall increase in the use of simulation in medicine in an effort to address dwindling clinical resource availability and patient safety issues currently facing the modern healthcare system. Virtual microscopy represents one such simulation-based technology that has the potential to enhance student learning and readiness to practice while revolutionising the ability to clinically diagnose pathology collaboratively across the world. While understanding that a substantial amount of literature already exists on virtual microscopy, much more research is still required to elucidate the full capabilities of this technology. This review explores the use of virtual microscopy in medical education and disease diagnosis with a unique focus on key requirements needed to take this technology to the next level in its use in medical education and clinical practice.

Evaluation of the therapeutic results of actinic keratosis treated with topical 5% fluorouracil by reflectance confocal laser microscopy: preliminary study*

PubMed Central

Ishioka, Priscila; Maia, Marcus; Rodrigues, Sarita Bartholomei; Marta, Alessandra Cristina; Hirata, Sérgio Henrique

2015-01-01

Topical treatment for actinic keratosis with 5% fluorouracil has a recurrence rate of 54% in 12 months of follow-up. This study analyzed thirteen actinic keratoses on the upper limbs through confocal microscopy, at the time of clinical diagnosis and after 4 weeks of treatment with fluorouracil. After the treatment was established and evidence of clinical cure was achieved, in two of the nine actinic keratoses, confocal microscopy enabled visualization of focal areas of atypical honeycomb pattern in the epidermis indicating therapeutic failure. Preliminary data suggest the use of confocal microscopy as a tool for diagnosis and therapeutic control of actinic keratosis. PMID:26131881

Brillouin microscopy: assessing ocular tissue biomechanics.

PubMed

Yun, Seok Hyun; Chernyak, Dimitri

2018-07-01

Assessment of corneal biomechanics has been an unmet clinical need in ophthalmology for many years. Many researchers and clinicians have identified corneal biomechanics as source of variability in refractive procedures and one of the main factors in keratoconus. However, it has been difficult to accurately characterize corneal biomechanics in patients. The recent development of Brillouin light scattering microscopy heightens the promise of bringing biomechanics into the clinic. The aim of this review is to overview the progress and discuss prospective applications of this new technology. Brillouin microscopy uses a low-power near-infrared laser beam to determine longitudinal modulus or mechanical compressibility of tissue by analyzing the return signal spectrum. Human clinical studies have demonstrated significant difference in the elastic properties of normal corneas versus corneas diagnosed with mild and severe keratoconus. Clinical data have also shown biomechanical changes after corneal cross-linking treatment of keratoconus patients. Brillouin measurements of the crystalline lens and sclera have also been demonstrated. Brillouin microscopy is a promising technology under commercial development at present. The technique enables physicians to characterize the biomechanical properties of ocular tissues.

In vivo confocal microscopy in dermatology: from research to clinical application

NASA Astrophysics Data System (ADS)

Ulrich, Martina; Lange-Asschenfeldt, Susanne

2013-06-01

Confocal laser scanning microscopy (CLSM) represents an emerging technique for the noninvasive histomorphological analysis of skin in vivo and has shown its applicability for dermatological research as well as its value as an adjunct tool in the clinical management of skin cancer patients. Herein, we aim to give an overview on the current clinical indications for CLSM in dermatology and also highlight the diverse applications of CLSM in dermatological research.

Quantification and Reconstruction in Photoacoustic Tomography

NASA Astrophysics Data System (ADS)

Guo, Zijian

Optical absorption is closely associated with many physiological important parameters, such as the concentration and oxygen saturation of hemoglobin. Conventionally, accurate quantification in PAT requires knowledge of the optical fluence attenuation, acoustic pressure attenuation, and detection bandwidth. We circumvent this requirement by quantifying the optical absorption coefficients from the acoustic spectra of PA signals acquired at multiple optical wavelengths. We demonstrate the method using the optical-resolution photoacoustic microscopy (OR-PAM) and the acoustical-resolution photoacoustic microscopy (AR-PAM) in the optical ballistic regime and in the optical diffusive regime, respectively. The data acquisition speed in photoacoustic computed tomography (PACT) is limited by the laser repetition rate and the number of parallel ultrasound detecting channels. Reconstructing an image with fewer measurements can effectively accelerate the data acquisition and reduce the system cost. We adapted Compressed Sensing (CS) for the reconstruction in PACT. CS-based PACT was implemented as a non-linear conjugate gradient descent algorithm and tested with both phantom and in vivo experiments. Speckles have been considered ubiquitous in all scattering-based coherent imaging technologies. As a coherent imaging modality based on optical absorption, photoacoustic (PA) tomography (PAT) is generally devoid of speckles. PAT suppresses speckles by building up prominent boundary signals, via a mechanism similar to that of specular reflection. When imaging smooth boundary absorbing targets, the speckle visibility in PAT, which is defined as the ratio of the square root of the average power of speckles to that of boundaries, is inversely proportional to the square root of the absorber density. If the surfaces of the absorbing targets have uncorrelated height fluctuations, however, the boundary features may become fully developed speckles. The findings were validated by simulations and experiments. The first- and second-order statistics of PAT speckles were also studied experimentally. While the amplitude of the speckles follows a Gaussian distribution, the autocorrelation of the speckle patterns tracks that of the system point spread function.

Multiwavelength micromirrors in the cuticle of scarab beetle Chrysina gloriosa.

PubMed

Agez, Gonzague; Bayon, Chloé; Mitov, Michel

2017-01-15

Beetles from the genus Chrysina show vivid reflections from bright green to metallic silver-gold as a consequence of the cholesteric liquid crystal organization of chitin molecules. Particularly, the cuticle of Chrysina gloriosa exhibits green and silver stripes. By combining confocal microscopy and spectrophotometry, scanning electron microscopy and numerical simulations, the relationship between the reflectance and the structural parameters for both stripes at the micro- and nanoscales are established. Over the visible and near IR spectra, polygonal cells in tessellated green stripes behave as multiwavelength selective micro-mirrors and the silver stripes as specular broadband mirrors. Thermoregulation, conspecifics or intra-species communication, or camouflage against predators are discussed as possible functions. As a prerequisite to bio-inspired artificial replicas, the physical characteristics of the polygonal texture in Chrysina gloriosa cuticle are compared to their equivalents in synthetic cholesteric oligomers and their fundamental differences are ascertained. It is shown that the cuticle has concave cells whereas the artificial films have convex cells, contrary to expectation and assumption in the literature. The present results may provide inspiration for fabricating multiwavelength selective micromirrors or spatial wavelength-specific light modulators. Many insects own a tessellated carapace with bumps, pits or indentations. Little is known on the physical properties of these geometric variations and biological functions are unknown or still debated. We show that the polygonal cells in scarab beetle Chrysina gloriosa behave as multiwavelength selective micromirrors over the visible and infrared spectra, with a variety of spatial patterns. In the context of biomimetic materials, we demonstrate that the carapace has concave cells whereas the artificial films have convex cells, contrary to expectation in the literature. Thermoregulation, communication or camouflage are discussed as advanced functions. Results may provide inspiration for fabricating spatial wavelength-specific light modulators and optical packet switching in routing technologies. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Interface fluid syndrome in human eye bank corneas after LASIK: causes and pathogenesis.

PubMed

Dawson, Daniel G; Schmack, Ingo; Holley, Glenn P; Waring, George O; Grossniklaus, Hans E; Edelhauser, Henry F

2007-10-01

To evaluate the effects of corneal edema on human donor corneas that had previous LASIK using a laboratory model with histologic and ultrastructural correlations. Experimental study. Thirty human eye bank corneas from 15 donors (mean age +/- standard deviation, 49.9+/-8.9 years) who had had previous LASIK surgery (2-8 years before death). The corneas were mounted in an artificial anterior chamber and the corneal endothelium was perfused for up to 5.0 hours with 0.9% saline solution (endothelial cell damage group) or BSS Plus at a pressure of 15 mmHg (control group), or BSS Plus at a pressure of 55 mmHg (high-pressure group). The corneas were evaluated by confocal and specular microscopy before, during, and at the end of the experimental period. Subsequently, the specimens were evaluated by light and electron microscopy. Corneal thickness, reflectivity, histology, and ultrastructure. Endothelial cell damage resulted in an increased (141.5+/-38.8 microm) total corneal thickness relative to controls (52.3+/-33.7 microm), whereas high pressure resulted in a decreased thickness (24.8+/-14.1 microm) relative to controls. This ultimately was due to swelling of the LASIK interface in both groups and swelling of the residual stromal bed (RSB) in the endothelial cell damage group or compression of the RSB and, possibly, the flap in the high-pressure group. A significant increase in corneal reflectivity at the LASIK interface occurred in both groups, primarily due to varying degrees of fluid accumulation and associated hydropic keratocyte degeneration, as well as increased corneal reflectivity in the RSB only in the endothelial cell damage group. After LASIK surgery, edematous corneas preferentially hydrate and swell in the paracentral and central interface wound, commonly resulting in a hazy corneal appearance primarily due to keratocyte hydropic degeneration. More severe corneal edema is characterized by the formation of an optically empty space corresponding to an interface fluid pocket. The spectrum of interface fluid syndrome can be described in 3 stages.

Atomic force measurements of 16-mercaptohexadecanoic acid and its salt with CH 3, OH, and CONHCH 3 functionalized self-assembled monolayers

NASA Astrophysics Data System (ADS)

Morales-Cruz, Angel L.; Tremont, Rolando; Martínez, Ramón; Romañach, Rodolfo; Cabrera, Carlos R.

2005-03-01

Chemical and mechanical properties of different compounds can be elucidated by measuring fundamental forces such as adhesion, attraction and repulsion, between modified surfaces by means of atomic force microscopy (AFM) in force mode calibration. This work presents a combination of AFM, self-assembled monolayers (SAMs), and crystallization techniques to study the forces of interaction between excipients and active ingredients used in pharmaceutical formulations. SAMs of 16-mercaptohexadecanoate, which represent magnesium stereate, were used to modify the probe tip, whereas CH3-, OH- and CONHCH3-functional SAMs were formed on a gold-coated mica substrate, and used as examples of the surfaces of lactose and theophylline. The crystals of lactose and theophylline were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The modification of gold surfaces with 16-mercaptohexadecanoate, 10-mercapto-1-decanol (OH-functional SAM), 1-decanethiol (CH3-functional) and N-methyl-11-mercaptoundecanamide (CONHCH3-functional SAM) was studied by X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and Fourier transform-infrared spectroscopy (FT-IR) in specular reflectance mode. XPS and AES results of the modified surfaces showed the presence of sulfur binding, and kinetic energies that correspond to the presence of 10-mercapto-1-decanol, 1-decanethiol, N-methyl-11-mercaptoundecanamide and the salt of 16-mercaptohexadecanoic acid. The absorption bands in the IR spectra further confirm the modification of the gold-coated substrates with these compounds. Force versus distance measurements were performed between the modified tip and the modified gold-coated mica substrates. The mean adhesion forces between the COO-Ca2+ functionalized tip and the CH3-, OH-, and CONHCH3-modified substrates were determined to be 4.5, 8.9 and 6.3 nN, respectively. The magnitude of the adhesion force (ion-dipole) interaction between the modified tip and substrate decreases in the following order: COO-Ca2+/OH > COO-Ca2+/CONHCH3 > COO-Ca2+/CH3.

Rainbow holography and its applications

NASA Astrophysics Data System (ADS)

Vlasov, N. G.; Ivanov, Vladimir S.

1993-09-01

The general equations of the rainbow holography are deduced. Their analysis makes it possible to offer different methods of the rainbow holographic images production. A new way of using the rainbow holograms as optical elements for effective color illuminating of transparent, specular, and polished objects is proposed. Application fields are the advertising industry, shop windows design, etc.

(abstract) Dynamics of Meteor Trails Deposited in the Equatorial Electrojet

NASA Technical Reports Server (NTRS)

Chapin, Elaine; Kudeki, Erhan

1996-01-01

Previously we reported that the meteor echoes detected at the Jicamarca Radio Observatory exhibit some unusual properties. In summary, the echo durations are very long ..., radio wave scattering is non-specular ..., and the doppler spectra of the scattered signals contain components that are red-shifted ... immediately after the onset of the echoes.

SENSIT.FOR: A program for sensitometric reduction

NASA Astrophysics Data System (ADS)

Maury, A.; Marchal, J.

1984-09-01

A FORTRAN program for sensitometric evaluation of processes involved in hypering astronomical plates was written. It contains subroutines for full or quick description of the operation being done; choice of type of sensitogram; creation of 16 subfiles in the scan; density filtering; correction for area; specular PDS to diffuse ISO density calibration; and fog correction.

40 CFR 63.14 - Incorporations by reference.

Code of Federal Regulations, 2013 CFR

2013-07-01

...., Washington, DC, and at the EPA Library (MD-35), U.S. EPA, Research Triangle Park, North Carolina. For... (ASTM), 100 Barr Harbor Drive, Post Office Box C700, West Conshohocken, PA 19428-2959, Telephone (610... following Web site: http://www.proquest.com. (1) ASTM D523-89, Standard Test Method for Specular Gloss, IBR...

40 CFR 63.14 - Incorporations by reference.

Code of Federal Regulations, 2012 CFR

2012-07-01

...., Washington, DC, and at the EPA Library (MD-35), U.S. EPA, Research Triangle Park, North Carolina. For... (ASTM), 100 Barr Harbor Drive, Post Office Box C700, West Conshohocken, PA 19428-2959; or ProQuest, 300 North Zeeb Road, Ann Arbor, MI 48106. (1) ASTM D523-89, Standard Test Method for Specular Gloss, IBR...

Advances in Urine Microscopy.

PubMed

Becker, Gavin J; Garigali, Giuseppe; Fogazzi, Giovanni B

2016-06-01

Urine microscopy is an important tool for the diagnosis and management of several conditions affecting the kidneys and urinary tract. In this review, we describe the automated instruments, based either on flow cytometry or digitized microscopy, that are currently in use in large clinical laboratories. These tools allow the examination of large numbers of samples in short periods. We also discuss manual urinary microscopy commonly performed by nephrologists, which we encourage. After discussing the advantages of phase contrast microscopy over bright field microscopy, we describe the advancements of urine microscopy in various clinical conditions. These include persistent isolated microscopic hematuria (which can be classified as glomerular or nonglomerular on the basis of urinary erythrocyte morphology), drug- and toxin-related cystalluria (which can be a clue for the diagnosis of acute kidney injury associated with intrarenal crystal precipitation), and some inherited conditions (eg, adenine phosphoribosyltransferase deficiency, which is associated with 2,8-dihydroxyadenine crystalluria, and Fabry disease, which is characterized by unique urinary lamellated fatty particles). Finally, we describe the utility of identifying "decoy cells" and atypical malignant cells, which can be easily done with phase contrast microscopy in unfixed samples. Copyright © 2016 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

High sensitivity optical measurement of skin gloss

PubMed Central

Ezerskaia, Anna; Ras, Arno; Bloemen, Pascal; Pereira, Silvania F.; Urbach, H. Paul; Varghese, Babu

2017-01-01

We demonstrate a low-cost optical method for measuring the gloss properties with improved sensitivity in the low gloss regime, relevant for skin gloss properties. The gloss estimation method is based on, on the one hand, the slope of the intensity gradient in the transition regime between specular and diffuse reflection and on the other on the sum over the intensities of pixels above threshold, derived from a camera image obtained using unpolarized white light illumination. We demonstrate the improved sensitivity of the two proposed methods using Monte Carlo simulations and experiments performed on ISO gloss calibration standards with an optical prototype. The performance and linearity of the method was compared with different professional gloss measurement devices based on the ratio of specular to diffuse intensity. We demonstrate the feasibility for in-vivo skin gloss measurements by quantifying the temporal evolution of skin gloss after application of standard paraffin cream bases on skin. The presented method opens new possibilities in the fields of cosmetology and dermatopharmacology for measuring the skin gloss and resorption kinetics and the pharmacodynamics of various external agents. PMID:29026683

Study of cylindrical optical micro-structure technology used in infrared laser protection

NASA Astrophysics Data System (ADS)

Sun, Yanjun; Liu, Shunrui; Wang, Zhining; Zhao, Yixuan; Wu, Boqi; Leng, Yanbing; Wang, Li

2016-10-01

The paper aimed at the problem that strong absorption in visible wavelengths and equipment or operator injury caused by specular reflection exist in infrared laser protection technology to propose an infrared laser non-specular reflection optical micro-structure formed from optical window surface. It has the function of little effect on visible light transmission and large-angle scattering to 1064nm infrared laser in order to enable laser protection. The paper uses light track method to design double-side micro-cylindrical lens arrays with dislocation construction. Array period T and curvature radius of lens units R should meet the condition:0

BioRef: A versatile time-of-flight reflectometer for soft matter applications at Helmholtz-Zentrum Berlin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Strobl, M.; Kreuzer, M.; Helmholtz-Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin

2011-05-15

BioRef is a versatile novel time-of-flight reflectometer featuring a sample environment for in situ infrared spectroscopy at the reactor neutron source BER II of the Helmholtz Zentrum Berlin fuer Materialien und Energie (HZB). After two years of design and construction phase the instrument has recently undergone commissioning and is now available for specular and off-specular neutron reflectivity measurements. BioRef is especially dedicated to the investigation of soft matter systems and studies at the solid-liquid interface. Due to flexible resolution modes and variable addressable wavelength bands that allow for focusing onto a selected scattering vector range, BioRef enables a broad rangemore » of surface and interface investigations and even kinetic studies with subsecond time resolution. The instrumental settings can be tailored to the specific requirements of a wide range of applications. The performance is demonstrated by several reference measurements, and the unique option of in situ on-board infrared spectroscopy is illustrated by the example of a phase transition study in a lipid multilayer film.« less

A new x-ray interface and surface scattering environmental cell design for in situ studies of radioactive and atmosphere-sensitive samples.

PubMed

Schmidt, M; Eng, P J; Stubbs, J E; Fenter, P; Soderholm, L

2011-07-01

We present a novel design of a purpose-built, portable sample cell for in situ x-ray scattering experiments of radioactive or atmosphere sensitive samples. The cell has a modular design that includes two independent layers of containment that are used simultaneously to isolate the sensitive samples. Both layers of containment can be flushed with an inert gas, thus serving a double purpose as containment of radiological material (either as a solid sample or as a liquid phase) and in separating reactive samples from the ambient atmosphere. A remote controlled solution flow system is integrated into the containment system that allows sorption experiments to be performed on the diffractometer. The cell's design is discussed in detail and we demonstrate the cell's performance by presenting first results of crystal truncation rod measurements. The results were obtained from muscovite mica single crystals reacted with 1 mM solutions of Th(IV) with 0.1 M NaCl background electrolyte. Data were obtained in specular as well as off-specular geometry.

Low earth orbit durability of protected silicone for refractive photovoltaic concentrator arrays

NASA Technical Reports Server (NTRS)

McCollum, Timothy A.; deGroh, Kim K.

1995-01-01

Photovoltaic power systems with novel refractive silicone solar concentrators are being developed for use in low Earth orbit (LEO). Because of the vulnerability of silicones to atomic oxygen and ultraviolet radiation, these lenses are coated with a multilayer metal oxide protective coating. The objective of this work was to evaluate the effects of atomic oxygen and thermal exposures on multilayer coated silicone. Samples were exposed to high-fluence ground-laboratory and low-fluence in-space atomic oxygen. Ground testing resulted in decreases in both total and specular transmittance, while in-space exposure resulted in only small decreases in specular transmittance. A contamination film, attributed to exposed silicone at coating crack sites, was found to cause transmittance decreases during ground testing. Propagation of coating cracks was found to be the result of sample heating during exposure. The potential for silicone exposure, with the resulting degradation of optical properties from silicone contamination, indicates that this multilayer coated silicone is not durable for LEO space applications where thermal exposures will cause coating crack development and propagation.

Detection of nanoscale embedded layers using laboratory specular X-ray diffraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beekman, Matt, E-mail: matt.beekman@oit.edu; Rodriguez, Gabriel; Atkins, Ryan

Unusual specular X-ray diffraction patterns have been observed from certain thin film intergrowths of metal monochalcogenide (MX) and transition metal dichalcogenide (TX{sub 2}) structures. These patterns exhibit selective “splitting” or broadening of selected (00l) diffraction peaks, while other (00l) reflections remain relatively unaffected [Atkins et al., Chem. Mater. 24, 4594 (2012)]. Using a simplified optical model in the kinematic approximation, we illustrate that these peculiar and somewhat counterintuitive diffraction features can be understood in terms of additional layers of one of the intergrowth components, MX or TX{sub 2}, interleaved between otherwise “ideal” regions of MX-TX{sub 2} intergrowth. The interpretation ismore » in agreement with scanning transmission electron microscope imaging, which reveals the presence of such stacking “defects” in films prepared from non-ideal precursors. In principle, the effect can be employed as a simple, non-destructive laboratory probe to detect and characterize ultrathin layers of one material, e.g., 2-dimensional crystals, embedded between two slabs of a second material, effectively using the two slabs as a highly sensitive interferometer of their separation distance.« less

Ecological model of glittering texture

NASA Astrophysics Data System (ADS)

Vallet, Matthieu; Paille, Damien; Monot, Annie; Kemeny, Andras

2003-06-01

The perceptual effects of changes of texture luminance either between the eyes or over time have been studied in several experiments and have led to a better comprehension of phenomenons such as sieve effect, binocular and monocular lustre and rivaldepth. In this paper, we propose an ecological model of glittering texture and analyze glitter perception in terms of variations of texture luminance and animation frequency, in dynamic illumination conditions. Our approach is based on randomly oriented mirrors that are computed according to the specular term of Phong's image rendering formula. The sparkling effect is thus correlated to the relative movements of the resulting textured object, the light array and the observer's point of view. The perceptual effect obtained with this model depends on several parameters: mirrors' density, the Phong specular exponent and the statistical properties of the mirrors' normal vectors. The ability to independently set these properties offers a way to explore a characterization space of glitter. A rating procedure provided a first approximation of the numerical values that lead to the best feeling of typical sparkling surfaces such as metallic paint, granite or sea shore.

Directional reflectance and milli-scale feather morphology of the African Emerald Cuckoo, Chrysococcyx cupreus.

PubMed

Harvey, Todd Alan; Bostwick, Kimberly S; Marschner, Steve

2013-09-06

Diverse plumages have evolved among birds through complex morphological modifications. We investigate how the interplay of light with surface and subsurface feather morphology determines the direction of light propagation, an understudied aspect of avian visual signalling. We hypothesize that milli-scale modifications of feathers produce anisotropic reflectance, the direction of which may be predicted by the orientation of the milli-scale structure. The subject of this study is the African Emerald Cuckoo, Chrysococcyx cupreus, noted for its shimmering green iridescent appearance. Using a spherical gantry, we measured the change in the directional reflectance across the feather surface and over a hemisphere of incident lighting directions. Using a microCT scanner, we also studied the morphology of the structural branches of the barb. We tracked the changes in the directional reflectance to the orientation of the structural branches as observed in the CT data. We conclude that (i) the far-field signal of the feather consists of multiple specular components, each associated with a different structural branch and (ii) the direction of each specular component is correlated to the orientation of the corresponding structure.

NASA Goddard Space Flight Center Cooperative Enterprise

NASA Technical Reports Server (NTRS)

Fredley, Joseph E.; Lysak, Daniel B.

2004-01-01

The viability of a Capillary Heat Pump (CHP) concept using a Loop Heat Pipe evaporator and an eductor in a closed loop to reject heat at a higher temperature than it is acquired at with the goal of reducing spacecraft radiator area is examined. Eductor inefficiency resulting from the mixing of high velocity motive flow with low velocity suction flow may preclude spacecraft radiator area savings. The utility of a CHP for thermal management may be limited to those missions where system mass is of secondary concern compared to system reliability, or where a heat pump is required to accommodate relatively high thermal rejection temperatures. Shearography techniques for nondestructive inspection and evaluation were examined for two unique applications. Shearography is shown to give good results in evaluating the quality of bonds holding lead tiles to the SWIFT spacecraft BAT gamma ray mask. Also, a novel technique was developed allowing specular objects to be inspected using shearography to evaluate bonding between the skin and core of a specular surface honeycomb structure. Large-scale bond failures are readily identified.

Non-lambertian reflectance modeling and shape recovery of faces using tensor splines.

PubMed

Kumar, Ritwik; Barmpoutis, Angelos; Banerjee, Arunava; Vemuri, Baba C

2011-03-01

Modeling illumination effects and pose variations of a face is of fundamental importance in the field of facial image analysis. Most of the conventional techniques that simultaneously address both of these problems work with the Lambertian assumption and thus fall short of accurately capturing the complex intensity variation that the facial images exhibit or recovering their 3D shape in the presence of specularities and cast shadows. In this paper, we present a novel Tensor-Spline-based framework for facial image analysis. We show that, using this framework, the facial apparent BRDF field can be accurately estimated while seamlessly accounting for cast shadows and specularities. Further, using local neighborhood information, the same framework can be exploited to recover the 3D shape of the face (to handle pose variation). We quantitatively validate the accuracy of the Tensor Spline model using a more general model based on the mixture of single-lobed spherical functions. We demonstrate the effectiveness of our technique by presenting extensive experimental results for face relighting, 3D shape recovery, and face recognition using the Extended Yale B and CMU PIE benchmark data sets.

A diffuse radar scattering model from Martian surface rocks

NASA Technical Reports Server (NTRS)

Calvin, W. M.; Jakosky, B. M.; Christensen, P. R.

1987-01-01

Remote sensing of Mars has been done with a variety of instrumentation at various wavelengths. Many of these data sets can be reconciled with a surface model of bonded fines (or duricrust) which varies widely across the surface and a surface rock distribution which varies less so. A surface rock distribution map from -60 to +60 deg latitude has been generated by Christensen. Our objective is to model the diffuse component of radar reflection based on this surface distribution of rocks. The diffuse, rather than specular, scattering is modeled because the diffuse component arises due to scattering from rocks with sizes on the order of the wavelength of the radar beam. Scattering for radio waves of 12.5 cm is then indicative of the meter scale and smaller structure of the surface. The specular term is indicative of large scale surface undulations and should not be causally related to other surface physical properties. A simplified model of diffuse scattering is described along with two rock distribution models. The results of applying the models to a planet of uniform fractional rock coverage with values ranging from 5 to 20% are discussed.

Specular reflectance of optical-black coatings in the far infrared

NASA Technical Reports Server (NTRS)

Smith, S. M.

1984-01-01

Far-infrared specular reflectance spectra of seven optically black coatings near normal incidence are presented. Seven photometric spectra were obtained using eleven bandpass transmission filters in the wavelength range between 12 and 500 microns, and three interferometric spectra were obtained for corroboration. Data on the construction, thickness, and rms surface roughness of the coatings are also presented. The chemical composition of three coatings can be distinguished from that of the others by a strong absorption feature between 20 and 40 microns, which can be largely attributed to amorphous silicate material. At 100 microns, the most and least reflective coatings differ by nearly 3 orders of magnitude. Inverse relationships observed between the spectra and the roughness and thickness of the coatings led to development of a reflecting-layer model for the measured reflectance. The model successfully describes the spectra at wavelengths outside the silicate absorption, and optical constants are deduced from a nonlinear least squares fit to the data. Parametric errors are estimated by chi-square analysis, and sensitivity tests are performed to determine which parameters control reflectance in different spectral regions.

A versatile optical profilometer based on conoscopic holography sensors for acquisition of specular and diffusive surfaces in artworks

NASA Astrophysics Data System (ADS)

Gaburro, Nicola; Marchioro, Giacomo; Daffara, Claudia

2017-07-01

Surface metrology of artworks requires the design of suitable devices for in-situ non-destructive measurement together with reliable procedures for an effective analysis of such non-engineered variegate objects. To advance the state-of-the-art it has been implemented a versatile optical micro-profilometry taking advantage of the adapt- ability of conoscopic holography sensors, able to operate with irregular shapes and composite materials (diffusive, specular, and polychrome) of artworks. The scanning technique is used to obtain wide field and high spatially resolved areal profilometry. The prototype has a modular scheme based on a set of conoscopic sensors, extending the typical design based on a scanning stage and a single probe with a limited bandwidth, thus allowing the collection of heights data from surface with different scales and materials with variegate optical response. The system was optimized by characterizing the quality of the measurement with the probes triggered in continuous scanning modality. The results obtained on examples of cultural heritage objects (2D paintings, 3D height-relief) and materials (pictorial, metallic) demonstrate the versatility of the implemented device.

Development of response models for the Earth Radiation Budget Experiment (ERBE) sensors. Part 1: Dynamic models and computer simulations for the ERBE nonscanner, scanner and solar monitor sensors

NASA Technical Reports Server (NTRS)

Halyo, Nesim; Choi, Sang H.; Chrisman, Dan A., Jr.; Samms, Richard W.

1987-01-01

Dynamic models and computer simulations were developed for the radiometric sensors utilized in the Earth Radiation Budget Experiment (ERBE). The models were developed to understand performance, improve measurement accuracy by updating model parameters and provide the constants needed for the count conversion algorithms. Model simulations were compared with the sensor's actual responses demonstrated in the ground and inflight calibrations. The models consider thermal and radiative exchange effects, surface specularity, spectral dependence of a filter, radiative interactions among an enclosure's nodes, partial specular and diffuse enclosure surface characteristics and steady-state and transient sensor responses. Relatively few sensor nodes were chosen for the models since there is an accuracy tradeoff between increasing the number of nodes and approximating parameters such as the sensor's size, material properties, geometry, and enclosure surface characteristics. Given that the temperature gradients within a node and between nodes are small enough, approximating with only a few nodes does not jeopardize the accuracy required to perform the parameter estimates and error analyses.

Image Registration Using Single Cluster PHD Methods

NASA Astrophysics Data System (ADS)

Campbell, M.; Schlangen, I.; Delande, E.; Clark, D.

Cadets in the Department of Physics at the United States Air Force Academy are using the technique of slitless spectroscopy to analyze the spectra from geostationary satellites during glint season. The equinox periods of the year are particularly favorable for earth-based observers to detect specular reflections off satellites (glints), which have been observed in the past using broadband photometry techniques. Three seasons of glints were observed and analyzed for multiple satellites, as measured across the visible spectrum using a diffraction grating on the Academy’s 16-inch, f/8.2 telescope. It is clear from the results that the glint maximum wavelength decreases relative to the time periods before and after the glint, and that the spectral reflectance during the glint is less like a blackbody. These results are consistent with the presumption that solar panels are the predominant source of specular reflection. The glint spectra are also quantitatively compared to different blackbody curves and the solar spectrum by means of absolute differences and standard deviations. Our initial analysis appears to indicate a potential method of determining relative power capacity.

Comparison of Geosynchronous Satellites Spectral Signatures During Glint Season

NASA Astrophysics Data System (ADS)

Weisz, D.; Dunsmore, A.; Key, J.; Tucker, R.; Weld, E.; Chun, F.; Tippets, R.

2016-09-01

Cadets in the Department of Physics at the United States Air Force Academy are using the technique of slitless spectroscopy to analyze the spectra from geostationary satellites during glint season. The equinox periods of the year are particularly favorable for earth-based observers to detect specular reflections off satellites (glints), which have been observed in the past using broadband photometry techniques. Three seasons of glints were observed and analyzed for multiple satellites, as measured across the visible spectrum using a diffraction grating on the Academy's 16-inch, f/8.2 telescope. It is clear from the results that the glint maximum wavelength decreases relative to the time periods before and after the glint, and that the spectral reflectance during the glint is less like a blackbody. The glint spectra are also quantitatively compared to different blackbody curves and the solar spectrum by means of absolute differences. Our initial analysis appears to indicate a potential method of determining relative power capacity. These results are consistent with the presumption that solar panels are the predominant source of specular reflection.

Directional reflectance and milli-scale feather morphology of the African Emerald Cuckoo, Chrysococcyx cupreus

PubMed Central

Harvey, Todd Alan; Bostwick, Kimberly S.; Marschner, Steve

2013-01-01

Diverse plumages have evolved among birds through complex morphological modifications. We investigate how the interplay of light with surface and subsurface feather morphology determines the direction of light propagation, an understudied aspect of avian visual signalling. We hypothesize that milli-scale modifications of feathers produce anisotropic reflectance, the direction of which may be predicted by the orientation of the milli-scale structure. The subject of this study is the African Emerald Cuckoo, Chrysococcyx cupreus, noted for its shimmering green iridescent appearance. Using a spherical gantry, we measured the change in the directional reflectance across the feather surface and over a hemisphere of incident lighting directions. Using a microCT scanner, we also studied the morphology of the structural branches of the barb. We tracked the changes in the directional reflectance to the orientation of the structural branches as observed in the CT data. We conclude that (i) the far-field signal of the feather consists of multiple specular components, each associated with a different structural branch and (ii) the direction of each specular component is correlated to the orientation of the corresponding structure. PMID:23825113

Optical fringe-reflection deflectometry with sparse representation

NASA Astrophysics Data System (ADS)

Xiao, Yong-Liang; Li, Sikun; Zhang, Qican; Zhong, Jianxin; Su, Xianyu; You, Zhisheng

2018-05-01

Optical fringe-reflection deflectometry is a surprisingly attractive scratch detection technique for specular surfaces owing to its unparalleled local sensibility. Full-field surface topography is obtained from a measured normal field using gradient integration. However, there may not be an ideal measured gradient field for deflectometry reconstruction in practice. Both the non-integrability condition and various kinds of image noise distributions, which are present in the indirect measured gradient field, may lead to ambiguity about the scratches on specular surfaces. In order to reduce misjudgment of scratches, sparse representation is introduced into the Southwell curl equation for deflectometry. The curl can be represented as a linear combination of the given redundant dictionary for curl and the sparsest solution for gradient refinement. The non-integrability condition and noise permutation can be overcome with sparse representation for gradient refinement. Numerical simulations demonstrate that the accuracy rate of judgment of scratches can be enhanced with sparse representation compared to the standard least-squares integration. Preliminary experiments are performed with the application of practical measured deflectometric data to verify the validity of the algorithm.

Sequential fitting-and-separating reflectance components for analytical bidirectional reflectance distribution function estimation.

PubMed

Lee, Yu; Yu, Chanki; Lee, Sang Wook

2018-01-10

We present a sequential fitting-and-separating algorithm for surface reflectance components that separates individual dominant reflectance components and simultaneously estimates the corresponding bidirectional reflectance distribution function (BRDF) parameters from the separated reflectance values. We tackle the estimation of a Lafortune BRDF model, which combines a nonLambertian diffuse reflection and multiple specular reflectance components with a different specular lobe. Our proposed method infers the appropriate number of BRDF lobes and their parameters by separating and estimating each of the reflectance components using an interval analysis-based branch-and-bound method in conjunction with iterative K-ordered scale estimation. The focus of this paper is the estimation of the Lafortune BRDF model. Nevertheless, our proposed method can be applied to other analytical BRDF models such as the Cook-Torrance and Ward models. Experiments were carried out to validate the proposed method using isotropic materials from the Mitsubishi Electric Research Laboratories-Massachusetts Institute of Technology (MERL-MIT) BRDF database, and the results show that our method is superior to a conventional minimization algorithm.

High sensitivity optical measurement of skin gloss.

PubMed

Ezerskaia, Anna; Ras, Arno; Bloemen, Pascal; Pereira, Silvania F; Urbach, H Paul; Varghese, Babu

2017-09-01

We demonstrate a low-cost optical method for measuring the gloss properties with improved sensitivity in the low gloss regime, relevant for skin gloss properties. The gloss estimation method is based on, on the one hand, the slope of the intensity gradient in the transition regime between specular and diffuse reflection and on the other on the sum over the intensities of pixels above threshold, derived from a camera image obtained using unpolarized white light illumination. We demonstrate the improved sensitivity of the two proposed methods using Monte Carlo simulations and experiments performed on ISO gloss calibration standards with an optical prototype. The performance and linearity of the method was compared with different professional gloss measurement devices based on the ratio of specular to diffuse intensity. We demonstrate the feasibility for in-vivo skin gloss measurements by quantifying the temporal evolution of skin gloss after application of standard paraffin cream bases on skin. The presented method opens new possibilities in the fields of cosmetology and dermatopharmacology for measuring the skin gloss and resorption kinetics and the pharmacodynamics of various external agents.

Polytype Stability and Microstructural Characterization of Silicon Carbide Epitaxial Films Grown on [ {11}overline{{2}} {0} ]- and [0001]-Oriented Silicon Carbide Substrates

NASA Astrophysics Data System (ADS)

Bishop, S. M.; Reynolds, C. L.; Liliental-Weber, Z.; Uprety, Y.; Zhu, J.; Wang, D.; Park, M.; Molstad, J. C.; Barnhardt, D. E.; Shrivastava, A.; Sudarshan, T. S.; Davis, R. F.

2007-04-01

The polytype and surface and defect microstructure of epitaxial layers grown on 4H( {11}overline{{2}} {0} ), 4H(0001) on-axis, 4H(0001) 8° off-axis, and 6H(0001) on-axis substrates have been investigated. High-resolution x-ray diffraction (XRD) revealed the epitaxial layers on 4H( {11}overline{{2}} {0} ) and 4H(0001) 8° off-axis to have the 4H-SiC (silicon carbide) polytype, while the 3C-SiC polytype was identified for epitaxial layers on 4H(0001) and 6H(0001) on-axis substrates. Cathodoluminescence (CL), Raman spectroscopy, and transmission electron microscopy (TEM) confirmed these results. The epitaxial surface of 4H( {11}overline{{2}} {0} ) films was specular with a roughness of 0.16-nm root-mean-square (RMS), in contrast to the surfaces of the other epitaxial layer-substrate orientations, which contained curvilinear boundaries, growth pits (˜3 × 104 cm-2), triangular defects >100 μm, and significant step bunching. Molten KOH etching revealed large defect densities within 4H( {11}overline{{2}} {0} ) films that decreased with film thickness to ˜106 cm-2 at 2.5 μm, while cross-sectional TEM studies showed areas free of defects and an indistinguishable film-substrate interface for 4H( {11}overline{{2}} {0} ) epitaxial layers.

Strategies for electrooptic film fabrication. Influence of pyrrole-pyridine-based dibranched chromophore architecture on covalent self-assembly, thin-film microstructure, and nonlinear optical response.

PubMed

Facchetti, Antonio; Beverina, Luca; van der Boom, Milko E; Dutta, Pulak; Evmenenko, Guennadi; Shukla, Atindra D; Stern, Charlotte E; Pagani, Giorgio A; Marks, Tobin J

2006-02-15

The new dibranched, heterocyclic "push-pull" chromophores bis{1-(pyridin-4-yl)-2-[2-(N-methylpyrrol-5-yl)]ethane}methane (1), 1-(pyrid-4-yl)-2-(N-methyl-5-formylpyrrol-2-yl)ethylene (2), {1-(N-methylpyridinium-4-yl)-2-[2-(N-methylpyrrol-5-yl)]ethane}{(1-(pyridin-4-yl)-2-[2-(N-methylpyrrol-5-yl)]ethane}methane (3), N-methyl-2-[1-(N-methylpyrid-4-yl)ethen-2-yl]-5-[pyrid-4-yl]ethen-2-yl]pyrrole iodide (4), bis{1-(N-methyl-4-pyridinio)-2-[2-(N-methylpyrrol-5-yl)]ethane}methane iodide (5), and N-methyl-2,5-[1-(N-methylpyrid-4-yl)ethen-2-yl]pyrrole iodide (6) have been synthesized and characterized. The neutral (1 and 2) and monomethyl salts (3 and 4) undergo chemisorptive reaction with iodobenzyl-functionalized surfaces to afford chromophore monolayers SA-1/SA-2 and SA-3/SA-4, respectively. Molecular structures and other physicochemical properties have been defined by (1)H NMR, optical spectroscopy, and XRD. Thin-film characterization by a variety of techniques (optical spectroscopy, specular X-ray reflectivity, atomic force microscopy, X-ray photoelectron spectroscopy, and angle-dependent polarized second harmonic generation) underscore the importance of the chromophore molecular architecture as well as film growth method on film microstructure and optical/electrooptic response.

Uniform enhancement of optical micro-angiography images using Rayleigh contrast-limited adaptive histogram equalization

PubMed Central

Yousefi, Siavash; Qin, Jia; Zhi, Zhongwei

2013-01-01

Optical microangiography is an imaging technology that is capable of providing detailed functional blood flow maps within microcirculatory tissue beds in vivo. Some practical issues however exist when displaying and quantifying the microcirculation that perfuses the scanned tissue volume. These issues include: (I) Probing light is subject to specular reflection when it shines onto sample. The unevenness of the tissue surface makes the light energy entering the tissue not uniform over the entire scanned tissue volume. (II) The biological tissue is heterogeneous in nature, meaning the scattering and absorption properties of tissue would attenuate the probe beam. These physical limitations can result in local contrast degradation and non-uniform micro-angiogram images. In this paper, we propose a post-processing method that uses Rayleigh contrast-limited adaptive histogram equalization to increase the contrast and improve the overall appearance and uniformity of optical micro-angiograms without saturating the vessel intensity and changing the physical meaning of the micro-angiograms. The qualitative and quantitative performance of the proposed method is compared with those of common histogram equalization and contrast enhancement methods. We demonstrate that the proposed method outperforms other existing approaches. The proposed method is not limited to optical microangiography and can be used in other image modalities such as photo-acoustic tomography and scanning laser confocal microscopy. PMID:23482880

Corneal endothelial cell density and morphology in normal Iranian eyes

PubMed Central

Hashemian, Mohammad Nasser; Moghimi, Sasan; Fard, Masood Aghsaie; Fallah, Mohammad Reza; Mansouri, Mohammad Reza

2006-01-01

Background We describe corneal endothelial cell density and morphology in normal Iranian eyes and compare endothelial cell characteristics in the Iranian population with data available in the literature for American and Indian populations. Methods Specular microscopy was performed in 525 eyes of normal Iranian people aged 20 to 85 years old. The studied parameters including mean endothelial cell density (MCD), mean cell area (MCA) and coefficient of variation (CV) in cell area were analyzed in all of the 525 eyes. Results MCD was 1961 ± 457 cell/mm2 and MCA was 537.0 ± 137.4 μm2. There was no statistically significant difference in MCD, MCA and CV between genders (Student t-test, P = 0.85, P = 0.97 and P = 0.15 respectively). There was a statistically significant decrease in MCD with age (P < 0.001, r = -0.64). The rate of cell loss was 0.6% per year. There was also a statistically significant increase in MCA (P < 0.001,r = 0.56) and CV (P < 0.001, r = 0.30) from 20 to 85 years of age. Conclusion The first normative data for the endothelium of Iranian eyes seems to confirm that there are no differences in MCD, MCA and CV between genders. Nevertheless, the values obtained in Iranian eyes seem to be different to those reported by the literature in Indian and American populations. PMID:16519812

Corneal endothelial cell density and morphology in normal Iranian eyes.

PubMed

Hashemian, Mohammad Nasser; Moghimi, Sasan; Fard, Masood Aghsaie; Fallah, Mohammad Reza; Mansouri, Mohammad Reza

2006-03-06

We describe corneal endothelial cell density and morphology in normal Iranian eyes and compare endothelial cell characteristics in the Iranian population with data available in the literature for American and Indian populations. Specular microscopy was performed in 525 eyes of normal Iranian people aged 20 to 85 years old. The studied parameters including mean endothelial cell density (MCD), mean cell area (MCA) and coefficient of variation (CV) in cell area were analyzed in all of the 525 eyes. MCD was 1961 +/- 457 cell/mm2 and MCA was 537.0 +/- 137.4 microm2. There was no statistically significant difference in MCD, MCA and CV between genders (Student t-test, P = 0.85, P = 0.97 and P = 0.15 respectively). There was a statistically significant decrease in MCD with age (P < 0.001, r = -0.64). The rate of cell loss was 0.6% per year. There was also a statistically significant increase in MCA (P < 0.001,r = 0.56) and CV (P < 0.001, r = 0.30) from 20 to 85 years of age. The first normative data for the endothelium of Iranian eyes seems to confirm that there are no differences in MCD, MCA and CV between genders. Nevertheless, the values obtained in Iranian eyes seem to be different to those reported by the literature in Indian and American populations.

Rapid and Facile Formation of P3HT Organogels via Spin Coating: Tuning Functional Properties of Organic Electronic Thin Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Cameron S.; Yin, Wen; Holt, Adam P.

Poly(3-hexyl thiophene) (P3HT) is widely regarded as the benchmark polymer when studying the physics of conjugated polymers used in organic electronic devices. P3HT can self-assemble via stacking of its backbone, leading to an assembly and growth of P3HT fi brils into 3D percolating organogels. These structures are capable of bridging the electrodes, providing multiple pathways for charge transport throughout the active layer. Here, a novel set of conditions is identified and discussed for P3HT organogel network formation via spin coating by monitoring the spin-coating process from various solvents. The development of organogel formation is detected by in situ static lightmore » scattering, which measures both the thinning rate by refl ectance and structural development in the fi lm via off-specular scattering during fi lm formation. Optical microscopy and thermal annealing experiments provide ex situ confi rmation of organogel fabrication. The role of solution characteristics, including solvent boiling point, P3HT solubility, and initial P3HT solution concentration on organogel formation, is examined to correlate these parameters to the rate of film formation, organogel-onset concentration, and overall network size. The correlation of film properties to the fabrication parameters is also analyzed within the context of the hole mobility and density-of-states measured by impedance spectroscopy.« less

Idiosyncrasies of Physical Vapor Deposition Processes from Various Knudsen Cells for Quinacridone Thin Film Growth on Silicon Dioxide

PubMed Central

2015-01-01

Thin films of quinacridone deposited by physical vapor deposition on silicon dioxide were investigated by thermal desorption spectroscopy (TDS), mass spectrometry (MS), atomic force microscopy (AFM), specular and grazing incidence X-ray diffraction (XRD, GIXD), and Raman spectroscopy. Using a stainless steel Knudsen cell did not allow the preparation of a pure quinacridone film. TDS and MS unambiguously showed that in addition to quinacridone, desorbing at about 500 K (γ-peak), significant amounts of indigo desorbed at about 420 K (β-peak). The existence of these two species on the surface was verified by XRD, GIXD, and Raman spectroscopy. The latter spectroscopies revealed that additional species are contained in the films, not detected by TDS. In the film mainly composed of indigo a species was identified which we tentatively attribute to carbazole. The film consisting of mainly quinacridone contained in addition p-sexiphenyl. The reason for the various decomposition species effusing from the metal Knudsen cell is the comparably high sublimation temperature of the hydrogen bonded quinacridone. With special experimental methods and by using glass Knudsen-type cells we were able to prepare films which exclusively consist of molecules either corresponding to the β-peak or the γ-peak. These findings are of relevance for choosing the proper deposition techniques in the preparation of quinacridone films in the context of organic electronic devices. PMID:26401189

In vivo correlation mapping microscopy

NASA Astrophysics Data System (ADS)

McGrath, James; Alexandrov, Sergey; Owens, Peter; Subhash, Hrebesh; Leahy, Martin

2016-04-01

To facilitate regular assessment of the microcirculation in vivo, noninvasive imaging techniques such as nailfold capillaroscopy are required in clinics. Recently, a correlation mapping technique has been applied to optical coherence tomography (OCT), which extends the capabilities of OCT to microcirculation morphology imaging. This technique, known as correlation mapping optical coherence tomography, has been shown to extract parameters, such as capillary density and vessel diameter, and key clinical markers associated with early changes in microvascular diseases. However, OCT has limited spatial resolution in both the transverse and depth directions. Here, we extend this correlation mapping technique to other microscopy modalities, including confocal microscopy, and take advantage of the higher spatial resolution offered by these modalities. The technique is achieved as a processing step on microscopy images and does not require any modification to the microscope hardware. Results are presented which show that this correlation mapping microscopy technique can extend the capabilities of conventional microscopy to enable mapping of vascular networks in vivo with high spatial resolution in both the transverse and depth directions.

A clinically viable capsule endoscopy video analysis platform for automatic bleeding detection

NASA Astrophysics Data System (ADS)

Yi, Steven; Jiao, Heng; Xie, Jean; Mui, Peter; Leighton, Jonathan A.; Pasha, Shabana; Rentz, Lauri; Abedi, Mahmood

2013-02-01

In this paper, we present a novel and clinically valuable software platform for automatic bleeding detection on gastrointestinal (GI) tract from Capsule Endoscopy (CE) videos. Typical CE videos for GI tract run about 8 hours and are manually reviewed by physicians to locate diseases such as bleedings and polyps. As a result, the process is time consuming and is prone to disease miss-finding. While researchers have made efforts to automate this process, however, no clinically acceptable software is available on the marketplace today. Working with our collaborators, we have developed a clinically viable software platform called GISentinel for fully automated GI tract bleeding detection and classification. Major functional modules of the SW include: the innovative graph based NCut segmentation algorithm, the unique feature selection and validation method (e.g. illumination invariant features, color independent features, and symmetrical texture features), and the cascade SVM classification for handling various GI tract scenes (e.g. normal tissue, food particles, bubbles, fluid, and specular reflection). Initial evaluation results on the SW have shown zero bleeding instance miss-finding rate and 4.03% false alarm rate. This work is part of our innovative 2D/3D based GI tract disease detection software platform. While the overall SW framework is designed for intelligent finding and classification of major GI tract diseases such as bleeding, ulcer, and polyp from the CE videos, this paper will focus on the automatic bleeding detection functional module.

Multiplex real-time quantitative PCR, microscopy and rapid diagnostic immuno-chromatographic tests for the detection of Plasmodium spp: performance, limit of detection analysis and quality assurance.

PubMed

Khairnar, Krishna; Martin, Donald; Lau, Rachel; Ralevski, Filip; Pillai, Dylan R

2009-12-09

Accurate laboratory diagnosis of malaria species in returning travelers is paramount in the treatment of this potentially fatal infectious disease. A total of 466 blood specimens from returning travelers to Africa, Asia, and South/Central America with suspected malaria infection were collected between 2007 and 2009 at the reference public health laboratory. These specimens were assessed by reference microscopy, multipex real-time quantitative polymerase chain reaction (QPCR), and two rapid diagnostic immuno-chromatographic tests (ICT) in a blinded manner. Key clinical laboratory parameters such as limit of detection (LOD) analysis on clinical specimens by parasite stage, inter-reader variability of ICTs, staffing implications, quality assurance and cost analysis were evaluated. QPCR is the most analytically sensitive method (sensitivity 99.41%), followed by CARESTART (sensitivity 88.24%), and BINAXNOW (sensitivity 86.47%) for the diagnosis of malaria in returning travelers when compared to reference microscopy. However, microscopy was unable to specifically identify Plasmodia spp. in 18 out of 170 positive samples by QPCR. Moreover, the 17 samples that were negative by microscopy and positive by QPCR were also positive by ICTs. Quality assurance was achieved for QPCR by exchanging a blinded proficiency panel with another reference laboratory. The Kappa value of inter-reader variability among three readers for BINAXNOW and CARESTART was calculated to be 0.872 and 0.898 respectively. Serial dilution studies demonstrated that the QPCR cycle threshold correlates linearly with parasitemia (R(2) = 0.9746) in a clinically relevant dynamic range and retains a LOD of 11 rDNA copies/microl for P. falciparum, which was several log lower than reference microscopy and ICTs. LOD for QPCR is affected not only by parasitemia but the parasite stage distribution of each clinical specimen. QPCR was approximately 6-fold more costly than reference microscopy. These data suggest that multiplex QPCR although more costly confers a significant diagnostic advantage in terms of LOD compared to reference microscopy and ICTs for all four species. Quality assurance of QPCR is essential to the maintenance of proficiency in the clinical laboratory. ICTs showed good concordance between readers however lacked sensitivity for non-falciparum species due to antigenic differences and low parasitemia. Multiplex QPCR but not ICTs is an essential adjunct to microscopy in the reference laboratory detection of malaria species specifically due to the superior LOD. ICTs are better suited to the non-reference laboratory where lower specimen volumes challenge microscopy proficiency in the non-endemic setting.

Interpreting Circularly Polarized 75-cm Oblique-Incidence Martian Surface Echoes Received by Mars Odyssey

NASA Astrophysics Data System (ADS)

Gunnarsdottir, Hrefna M.; Linscott, I. R.; Callas, J. L.; Tyler, G. L.; Cousins, M. D.

2006-09-01

Between August and December 2005, we conducted 76 oblique-incidence scattering experiments using the SRI 46-m antenna in the Stanford foothills to illuminate Mars for 20 min. periods with an unmodulated 75 cm-λ, circularly polarized wave. The direct signal and a Martian surface echo, which are separated by Doppler frequency, were received simultaneously by the one-bit receiver on board the Mars Odyssey spacecraft. Out of 45 experiments with high signal-to-noise ratios, 27 were in the northern hemisphere, while 18 were in the southern hemisphere, where preliminary data analysis is available. The surface echoes are characterized by both fluctuating amplitude and varying spectral width, which correspond roughly to the surface reflectivity and roughness, respectively. Analysis of the data is based on quasi-specular scattering theory, but interpretation of the echoes is complicated by Odyssey's reception of only the right-circular polarized (RCP) wave component, and by the high incidence angles involved (f > 60 deg.), for which the scattering theory is not well developed. Our analysis of the echoes makes use of MOLA topographic maps at a resolution of 128 points per deg. of longitude and latitude, to model the scattering surface in three dimensions along the specular track. We can account for most of the echo amplitude fluctuations by the variation in number of surface-model facets tilted to produce a specular reflection towards Odyssey, indicating that MOLA scale topography is sufficient to capture an important scattering mechanism at this wavelength. With this we have accomplished a first step in differentiating between changes in echo signal strength due to surface reflectivity and surface shape. At the same time, we obtain a measure of the small scale surface roughness by finding the maximum tilt angle away from a perfectly mirroring surface facet which contributes significantly to the echo at each time step.

Methods for quantitative infrared directional-hemispherical and diffuse reflectance measurements using an FTIR and a commercial integrating sphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blake, Thomas A.; Johnson, Timothy J.; Tonkyn, Russell G.

Infrared integrating sphere measurements of solid samples are important in providing reference data for contact, standoff and remote sensing applications. At the Pacific Northwest National Laboratory (PNNL) we have developed protocols to measure both the directional-hemispherical ( and diffuse (d) reflectances of powders, liquids, and disks of powders and solid materials using a commercially available, matte gold-coated integrating sphere and Fourier transform infrared spectrometer. Detailed descriptions of the sphere alignment and its use for making these reflectance measurements are given. Diffuse reflectance values were found to be dependent on the bidirectional reflection distribution function (BRDF) of the sample and themore » solid angle intercepted by the sphere’s specular exclusion port. To determine how well the sphere and protocols produce quantitative reflectance data, measurements were made of three diffuse and two specular standards prepared by the National institute of Standards and Technology (NIST, USA), LabSphere Infragold and Spectralon standards, hand-loaded sulfur and talc powder samples, and water. The five NIST standards behaved as expected: the three diffuse standards had a high degree of “diffuseness,” d/ = D > 0.9, whereas the two specular standards had D ≤ 0.03. The average absolute differences between the NIST and PNNL measurements of the NIST standards for both directional-hemispherical and diffuse reflectances are on the order of 0.01 reflectance units. Other quantitative differences between the PNNL-measured and calibration (where available) or literature reflectance values for these standards and materials are given and the possible origins of discrepancies are discussed. Random uncertainties and estimates of systematic uncertainties are presented. Corrections necessary to provide better agreement between the PNNL reflectance values as measured for the NIST standards and the NIST reflectance values for these same standards are also discussed.« less

The ego, the ocular, and the uncanny: why are metaphors of vision central in accounts of the uncanny?

PubMed

Rahimi, Sadeq

2013-06-01

I am my own twin, Always with me, same as me, and always watching me! From interview with a psychotic patient Every man carries with him through life a mirror, as unique and impossible to get rid of as his shadow W.H. Auden, 1989, p.93 I cannot urge you too strongly to a meditation on optics. Jacques Lacan, 1991, p.76 This paper outlines the basic arguments for a reading of the notion of the uncanny that draws on direct and metaphorical significances of the ocular in the development of human ego. It is argued that a specular-oriented reading of the uncanny as made possible through Lacan's model for ego development introduces a significant analytic device capable of explaining diverse features of the uncanny experience that escaped the traditional phallic/castration-based reading. To examine this claim, evidence is presented from a number of contexts to demonstrate how uncanny experiences are typically constructed through and associated with themes and metaphors of vision, blindness, mirrors and other optical tropes. Evidence is also presented from a historical point of view to demonstrate the strong presence of ocular and specular themes, devices and associations in a tradition of literary and psychological writing out of which the notion of 'the uncanny' (including Freud's own formulation) emerged. It is demonstrated that the main instances of the uncanny, such as doppelgangers, ghosts, déjà vu, alter egos, self-alienations and split personhoods, phantoms, twins, living dolls and many more in the list of 'things of terror' typically share two important features: they are closely tied with visual tropes, and they are variations on the theme of doubling. It is then argued that both of these features are integrally associated with the developmental processes of ego formation and self-identity, thus explaining the strong association of the uncanny accounts and experiences with ocular and specular motifs and metaphors. Copyright © 2013 Institute of Psychoanalysis.

An analytical two-flow model to simulate the distribution of irradiance in coastal waters with a wind-roughed surface and bottom reflectance

NASA Astrophysics Data System (ADS)

Ma, Wei-Ming

1997-06-01

An analytical two-flow model is derived from the radiative transfer equation to simulate the distribution of irradiance in coastal waters with a wind-roughed surface and bottom reflectance. The model utilizes unique boundary conditions, including the surface slope of the downwelling and upwelling irradiance as well as the influence of wind and bottom reflectance on simulated surface reflectance. The developed model provides a simple mathematical concept for understanding the irradiant light flux and associated processes in coastal or fresh water as well as turbid estuarine waters. The model is applied to data from the Banana River and coastal Atlantic Ocean water off the east coast of central Florida, USA. The two-flow irradiance model is capable of simulating realistic above-surface reflectance signatures under wind-roughened air-water surface given realistic input parameters including a specular flux conversion coefficient, absorption coefficient, backscattering coefficient, atmospheric visibility, bottom reflectance, and water depth. The root-mean-squared error of the calculated above-surface reflectances is approximately 3% in the Banana River and is less than 15% in coastal Atlantic Ocean off the east of Florida. Result of the subsurface reflectance sensitivity analysis indicates that the specular conversion coefficient is the most sensitive parameter in the model, followed by the beam attenuation coefficient, absorption coefficient, water depth, backscattering coefficient, specular irradiance, diffuse irradiance, bottom reflectance, and wind speed. On the other hand, result of the above-surface reflectance sensitivity analysis indicates that the wind speed is the most important parameter, followed by bottom reflectance, attenuation coefficient, water depth, conversion coefficient, specular irradiance, downwelling irradiance, absorption coefficient, and backscattering coefficient. Model results depend on the accuracy of these parameters to a large degree and more important the water depth and value of the bottom reflectance. The results of this work indicates little change of subsurface or in-water reflectances, due to variations of wind speed and observation angle. Simulations of the wind effect on the total downwelling irradiance from the two- flow model indicates that the total downwelling irradiance just below a wind-roughened water surface increases to about 1% of the total downwelling irradiance on a calm water surface when the sun is near zenith and increases to about 3% when the sun is near the horizon. This analytically based model, solved or developed utilizing the unique boundary conditions, can be applied to remote sensing of oceanic upper mixed layer dynamics, plant canopies, primary production, and shallow water environments with different bottom type reflectances. Future applications may include determining effects of sediment resuspension of bottom sediments in the bottom boundary layer on remotely sensed data.

Malaria and Chikungunya Detected Using Molecular Diagnostics Among Febrile Kenyan Children.

PubMed

Waggoner, Jesse; Brichard, Julie; Mutuku, Francis; Ndenga, Bryson; Heath, Claire Jane; Mohamed-Hadley, Alisha; Sahoo, Malaya K; Vulule, John; Lefterova, Martina; Banaei, Niaz; Mukoko, Dunstan; Pinsky, Benjamin A; LaBeaud, A Desiree

2017-01-01

In sub-Saharan Africa, malaria is frequently overdiagnosed as the cause of an undifferentiated febrile illness, whereas arboviral illnesses are presumed to be underdiagnosed. Sera from 385 febrile Kenyan children, who presented to 1 of 4 clinical sites, were tested using microscopy and real-time molecular assays for dengue virus (DENV), chikungunya virus (CHIKV), malaria, and Leptospira . Malaria was the primary clinical diagnosis for 254 patients, and an arboviral infection (DENV or CHIKV) was the primary diagnosis for 93 patients. In total, 158 patients (41.0%) had malaria and 32 patients (8.3%) had CHIKV infections. Compared with real-time polymerase chain reaction, microscopy demonstrated a percent positive agreement of 49.7%. The percentage of malaria cases detected by microscopy varied significantly between clinical sites. Arboviral infections were the clinical diagnosis for patients on the Indian Ocean coast (91 of 238, 38.2%) significantly more often than patients in the Lake Victoria region (2 of 145, 1.4%; P < .001). However, detection of CHIKV infections was significantly higher in the Lake Victoria region (19 of 145 [13.1%] vs 13 of 239 [5.4%]; P = .012). The clinical diagnosis of patients with an acute febrile illness, even when aided by microscopy, remains inaccurate in malaria-endemic areas, contributing to inappropriate management decisions.

Clinical Nonlinear Laser Imaging of Human Skin: A Review

PubMed Central

Pavone, Francesco Saverio

2014-01-01

Nonlinear optical microscopy has the potential of being used in vivo as a noninvasive imaging modality for both epidermal and dermal imaging. This paper reviews the capabilities of nonlinear microscopy as a noninvasive high-resolution tool for clinical skin inspection. In particular, we show that two-photon fluorescence microscopy can be used as a diagnostic tool for characterizing epidermal layers by means of a morphological examination. Additional functional information on the metabolic state of cells can be provided by measuring the fluorescence decay of NADH. This approach allows differentiating epidermal layers having different structural and cytological features and has the potential of diagnosing pathologies in a very early stage. Regarding therapy follow-up, we demonstrate that nonlinear microscopy could be successfully used for monitoring the effect of a treatment. In particular, combined two-photon fluorescence and second-harmonic generation microscopy were used in vivo for monitoring collagen remodeling after microablative fractional laser resurfacing and for quantitatively monitoring psoriasis on the basis of the morphology of epidermal cells and dermal papillae. We believe that the described microscopic modalities could find in the near future a stable place in a clinical dermatological setting for quantitative diagnostic purposes and as a monitoring method for various treatments. PMID:25250337

Comparison of the effects of intraocular irrigating solutions on the corneal endothelium in intraocular lens implantation.

PubMed Central

Matsuda, M; Kinoshita, S; Ohashi, Y; Shimomura, Y; Ohguro, N; Okamoto, H; Omoto, T; Hosotani, H; Yoshida, H

1991-01-01

We conducted a randomised prospective controlled study to determine the effects of a glucose glutathione bicarbonate solution (BSS Plus) and a citrate acetate bicarbonate solution (S-MA2) on the corneal endothelium in patients undergoing extracapsular cataract extraction with posterior chamber lens implantation. One eye of each patient was randomly assigned to receive BSS Plus, and the other eye to receive S-MA2. BSS Plus caused significantly less corneal swelling on the first postoperative day than did S-MA2. There was no difference between the two solutions in their effect on corneal thickness one week and one month postoperatively. Computer assisted morphometric analysis of wide-field specular microscopic photographs demonstrated minimal changes in endothelial morphological characteristics in the eyes irrigated with BSS Plus. By comparison S-MA2, caused a significant loss of endothelial cells and a marked reduction in the figure coefficient. These results indicated that BSS Plus has a clinical advantage over S-MA2 with respect to the corneal endothelium. PMID:1873266

Serial corneal endothelial cell loss with lathe-cut and injection-molded posterior chamber intraocular lenses.

PubMed

Kraff, M C; Sanders, D R; Lieberman, H L

1983-01-01

We compared endothelial cell loss of patients implanted with lathe-cut posterior chamber lenses and those implanted with injection-molded lenses over a three-year postoperative period. Results were based on more than 2,500 measurements of corneal endothelial density. Although the technique of cataract extraction (anterior chamber phacoemulsification, posterior chamber phacoemulsification, or planned extracapsular extraction) significantly affected cell loss (P less than .01), the type of implant (lathe-cut or injection-molded) did not. Significant continuing endothelial cell loss did not occur during the first three postoperative years with injection-molded lenses. There was, however, a statistically significant 7% to 15% additional cell loss after surgery over the first two to three postoperative years with lathe-cut implants. There have been no cases of corneal endothelial decompensation developing after implantation of injection-molded or lathe-cut lenses. Because a standard field clinical specular microscope was used in this study, cell counting errors cannot be ruled out as a cause of these findings.

Initial Investigation of a Novel Thermal Storage Concept as Part of a Renewable Energy System

DTIC Science & Technology

2013-06-01

stress (pascal) z-component of shear stress (pascal) Fslip constant Esl ip constant surface tension gradient (n/m-k) specularity coefficient...Axis x-component of ¥-Component of z- component of x -component of v-component of z-component of Fs l ip constant Esl i p constant Rotation

Recognition of the Multi Specularity Objects using the Eigen-Window,

DTIC Science & Technology

1996-02-29

analysis to each eigen-window [21]. The basic idea is that, even if some of the windows are occluded, the remaining windows are still effective and can...K.Ikeuchi, “The Machanical Manipulation of Randomly Oriented Parts”, Scientific American, Vol.251, No.2, pp.100-111, 1984. [5] S.A.Hutchinson and A.C.Kak

Measuring Incorporation Of Arsenic In Molecular-Beam Expitaxy

NASA Technical Reports Server (NTRS)

Lewis, Blair F.; Fernandez, Rouel F.; Madhukar, Anupam; Grunthaner, Frank J.

1988-01-01

Changes in surface layers cause oscillations in RHEED measurements. Specular RHEED Beam intensity measured before, during, and after deposition of seven to eight monomolecular layers of gallium during 1.5 seconds. Arsenic pressure was 1.7x10 to the negative seventh power torr (2.3x10 to the negative fifth power Pa) throughout measurements.

Coherent gradient sensing method and system for measuring surface curvature

NASA Technical Reports Server (NTRS)

Rosakis, Ares J. (Inventor); Moore, Jr., Nicholas R. (Inventor); Singh, Ramen P. (Inventor); Kolawa, Elizabeth (Inventor)

2000-01-01

A system and method for determining a curvature of a specularly reflective surface based on optical interference. Two optical gratings are used to produce a spatial displacement in an interference field of two different diffraction components produced by one grating from different diffraction components produced by another grating. Thus, the curvature of the surface can be determined.

40 CFR 63.14 - Incorporations by reference.

Code of Federal Regulations, 2011 CFR

2011-07-01

... (MD-35), U.S. EPA, Research Triangle Park, North Carolina. For information on the availability of this..., Post Office Box C700, West Conshohocken, PA 19428-2959; or ProQuest, 300 North Zeeb Road, Ann Arbor, MI 48106. (1) ASTM D523-89, Standard Test Method for Specular Gloss, IBR approved for § 63.782. (2) ASTM...

DETAILED DATA ANALYSIS OF ECHO I, ECHO II AND MOON REFLECTED SIGNALS. VOLUME 2. AUTOCORRELATION FUNCTIONS OF ECHO II REFLECTED SIGNALS,

DTIC Science & Technology

techniques is presented. Two methods for linearizing the data are given. An expression for the specular-to-spattered power ratio is derived, and the inverse ... transform of the autocorrelation function is discussed. The surface roughness of the reflector, the discrete fading rates, and fading frequencies

Rose-K versus Soper contact lens in keratoconus: a randomized comparative trial.

PubMed

Gupta, Raghav; Sinha, Rajesh; Singh, Pooja; Sharma, Namrata; Tandon, Radhika; Titiyal, Jeewan S

2014-01-01

To perform a comparative evaluation of the efficacy and acceptability of Rose-K and Soper contact lenses in Keratoconus. Dr. Rajendra Prasad Center for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi. A randomized comparative clinical trial was performed in keratoconic eyes fitted with Rose-K (Rose-K group) and Soper (Soper group) contact lenses. Patients data were evaluated for best spectacle corrected visual acuity, best contact lens corrected visual acuity (BCLCVA), corneal topography, glare acuity, contrast sensitivity, tear function tests and specular microscopy. Patients were also asked to complete a self-reported comfort questionnaire at each visit. Sixty eyes were randomized to the Rose-K and Soper groups. The two groups were comparable in all the baseline parameters. There was a statistically significant improvement in BCLCVA in both groups at 3 months (P < 0.01, both groups). The difference between in BCLCVA in both groups was not statistically significant. In both groups, there was a significant improvement in the comfort score at 3 months compared to baseline (P < 0.05, both group). The Rose-K group had statistically significantly better scores at 1 and 3 months compared with the Soper group (P = 0.006 and P < 0.001 respectively). Both groups were associated with a significant (P < 0.01), but comparable improvement in glare acuity at 3 months. There was a significant improvement in contrast sensitivity at 3 months in both groups (P < 0.01); the Rose-K group was significantly better than the Soper group at 1 and 3 months (P = 0.001 and 0.002 respectively). The mean number of trial lenses required for fitting Rose-K lens (2.00 ± 0.59) was significantly lower than the Soper lens (3.43 ± 0.82; P < 0.001). Both the contact lens designs provide an equal improvement in visual acuity in patients with Keratoconus. However, Rose-K contact lens provides greater comfort, better quality of vision and requires less chair time compared with the Soper lens and hence may possibly have a greater acceptability.

Validation of wet mount microscopy against Trichomonas culture among women of reproductive age group in Western province, Sri Lanka.

PubMed

Banneheke, H; Fernandopulle, R; Gunasekara, U; Barua, A; Fernando, N; Wickremasinghe, R

2015-06-01

Wet mount microscopy is the most commonly used diagnostic method for trichomoniasis in clinical diagnostic services all over the world including Sri Lanka due to its availability, simplicity and is relatively inexpensive. However, Trichomonas culture and PCR are the gold standard tests. Unfortunately, neither the culture nor PCR is available for the diagnosis of trichomoniasis in Sri Lanka. Thus, it is important to validate the wet mount microscopy as it is the only available diagnostic test and has not been validated to date in Sri Lanka. The objective was to evaluate the validity and reliability of wet mount microscopy against gold standard Trichomonas culture among clinic based population of reproductive age group women in Western province, Sri Lanka. Women attending hospital and institutional based clinics were enrolled. They were interviewed and high vaginal swabs were taken for laboratory diagnosis by culture and wet mount microscopy. There were 601 participants in the age group of 15-45 years. Wet mount microscopy showed 68% sensitivity, 100% specificity, 100% positive (PPV) and 98% negative predictive values (NPV) (P=0.001, kappa=0.803) respectively against the gold standard culture. The area under the ROC curve was 0.840. Sensitivity of wet mount microscopy is low. However it has high validity and reliability as a specific diagnostic test for trichomoniasis. If it is to be used among women of reproductive age group in Western province, Sri Lanka, a culture method could be adopted as a second test to confirm the negative wet mount for symptomatic patients.

Intravital Microscopy Imaging Approaches for Image-Guided Drug Delivery Systems

PubMed Central

Kirui, Dickson K.; Ferrari, Mauro

2016-01-01

Rapid technical advances in the field of non-linear microscopy have made intravital microscopy a vital pre-clinical tool for research and development of imaging-guided drug delivery systems. The ability to dynamically monitor the fate of macromolecules in live animals provides invaluable information regarding properties of drug carriers (size, charge, and surface coating), physiological, and pathological processes that exist between point-of-injection and the projected of site of delivery, all of which influence delivery and effectiveness of drug delivery systems. In this Review, we highlight how integrating intravital microscopy imaging with experimental designs (in vitro analyses and mathematical modeling) can provide unique information critical in the design of novel disease-relevant drug delivery platforms with improved diagnostic and therapeutic indexes. The Review will provide the reader an overview of the various applications for which intravital microscopy has been used to monitor the delivery of diagnostic and therapeutic agents and discuss some of their potential clinical applications. PMID:25901526

Impact of routine real-time PCR testing of imported malaria over 4 years of implementation in a clinical laboratory.

PubMed

Shokoples, Sandra; Mukhi, Shamir N; Scott, Allison N; Yanow, Stephanie K

2013-06-01

In clinical laboratories, diagnosis of imported malaria is commonly performed by microscopy. However, the volume of specimens is generally low and maintaining proficiency in reading blood smears, particularly at the species level, is challenging in this setting. To address this problem, the Provincial Laboratory for Public Health (ProvLab) in Alberta, Canada, implemented real-time PCR for routine confirmation of all smear-positive samples in the province. Here we report our experience over a 4-year period (2008 to 2012) with this new diagnostic algorithm. While detection of Plasmodium falciparum by microscopy alone was accurate, real-time PCR served as an important adjunct to microscopy for the identification of non-falciparum species. In 18% of cases, the result was reported as non-falciparum or the species could not be identified by microscopy alone, and in all cases, the species was resolved by real-time PCR. In another 4% of cases, the species was misidentified by microscopy. To enhance surveillance for malaria, we integrated our demographic, clinical, and laboratory data into a new system developed by the Canadian Network for Public Health Intelligence, called the Malaria System for Online Surveillance (SOS). Using this application, we characterized our patient populations and travel history to identify risk factors associated with malaria infection abroad.

Comparative evaluation of fluorescent in situ hybridization and Giemsa microscopy with quantitative real-time PCR technique in detecting malaria parasites in a holoendemic region of Kenya.

PubMed

Osoga, Joseph; Waitumbi, John; Guyah, Bernard; Sande, James; Arima, Cornel; Ayaya, Michael; Moseti, Caroline; Morang'a, Collins; Wahome, Martin; Achilla, Rachel; Awinda, George; Nyakoe, Nancy; Wanja, Elizabeth

2017-07-24

Early and accurate diagnosis of malaria is important in treatment as well as in the clinical evaluation of drugs and vaccines. Evaluation of Giemsa-stained smears remains the gold standard for malaria diagnosis, although diagnostic errors and potential bias estimates of protective efficacy have been reported in practice. Plasmodium genus fluorescent in situ hybridization (P-Genus FISH) is a microscopy-based method that uses fluorescent labelled oligonucleotide probes targeted to pathogen specific ribosomal RNA fragments to detect malaria parasites in whole blood. This study sought to evaluate the diagnostic performance of P-Genus FISH alongside Giemsa microscopy compared to quantitative reverse transcription polymerase chain reaction (qRT-PCR) in a clinical setting. Five hundred study participants were recruited prospectively and screened for Plasmodium parasites by P-Genus FISH assay, and Giemsa microscopy. The microscopic methods were performed by two trained personnel and were blinded, and if the results were discordant a third reading was performed as a tie breaker. The diagnostic performance of both methods was evaluated against qRT-PCR as a more sensitive method. The number of Plasmodium positive cases was 26.8% by P-Genus FISH, 33.2% by Giemsa microscopy, and 51.2% by qRT-PCR. The three methods had 46.8% concordant results with 61 positive cases and 173 negative cases. Compared to qRT-PCR the sensitivity and specificity of P-Genus FISH assay was 29.3 and 75.8%, respectively, while microscopy had 58.2 and 93.0% respectively. Microscopy had a higher positive and negative predictive values (89.8 and 68.0% respectively) compared to P-Genus FISH (56.0 and 50.5%). In overall, microscopy had a good measure of agreement (76%, k = 0.51) compared to P-Genus FISH (52%, k = 0.05). The diagnostic performance of P-Genus FISH was shown to be inferior to Giemsa microscopy in the clinical samples. This hinders the possible application of the method in the field despite the many advantages of the method especially diagnosis of low parasite density infections. The P-Genus assay has great potential but application of the method in clinical setting would rely on extensive training of microscopist and continuous proficiency testing.

Disorganization of cell division of methicillin-resistant Staphylococcus aureus by methanolic extract from Phyllanthus columnaris stem bark

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adnalizawati, A. Siti Noor; Nazlina, I.; Yaacob, W. A.

The in vitro activity of methanolic extract from Phyllanthus columnaris stem bark was studied against Methicillin-resistant Staphylococcus aureus (MRSA) ATCC 43300 and MRSA BM1 (clinical strain) using time-kill curves in conjunction with scanning and transmission electron microscopy. The extract showed more markedly bactericidal activity in MRSA BM1 clinical strain within less than 4 h by 6.25-12.5 mg/mL and within 6 h by 1.56 mg/mL. Scanning electron microscopy of MRSA BM1 revealed distortion of cell whilst transmission electron microscopy revealed disruption in cell wall division.

Disorganization of cell division of methicillin-resistant Staphylococcus aureus by methanolic extract from Phyllanthus columnaris stem bark

NASA Astrophysics Data System (ADS)

Adnalizawati, A. Siti Noor; Nazlina, I.; Yaacob, W. A.

2013-11-01

The in vitro activity of methanolic extract from Phyllanthus columnaris stem bark was studied against Methicillin-resistant Staphylococcus aureus (MRSA) ATCC 43300 and MRSA BM1 (clinical strain) using time-kill curves in conjunction with scanning and transmission electron microscopy. The extract showed more markedly bactericidal activity in MRSA BM1 clinical strain within less than 4 h by 6.25-12.5 mg/mL and within 6 h by 1.56 mg/mL. Scanning electron microscopy of MRSA BM1 revealed distortion of cell whilst transmission electron microscopy revealed disruption in cell wall division.

Coherent anti-Stokes Raman scattering microscopy: overcoming technical barriers for clinical translation

PubMed Central

Tu, Haohua; Boppart, Stephen A.

2015-01-01

Clinical translation of coherent anti-Stokes Raman scattering microscopy is of great interest because of the advantages of noninvasive label-free imaging, high sensitivity, and chemical specificity. For this to happen, we have identified and review the technical barriers that must be overcome. Prior investigations have developed advanced techniques (features), each of which can be used to effectively overcome one particular technical barrier. However, the implementation of one or a small number of these advanced features in previous attempts for clinical translation has often introduced more tradeoffs than benefits. In this review, we outline a strategy that would integrate multiple advanced features to overcome all the technical barriers simultaneously, effectively reduce tradeoffs, and synergistically optimize CARS microscopy for clinical translation. The operation of the envisioned system incorporates coherent Raman micro-spectroscopy for identifying vibrational biomolecular markers of disease and single-frequency (or hyperspectral) Raman imaging of these specific biomarkers for real-time in vivo diagnostics and monitoring. An optimal scheme of clinical CARS micro-spectroscopy for thin ex vivo tissues. PMID:23674234

Diagnosis of clinical bovine mastitis by fine needle aspiration followed by staining and scanning electron microscopy in a Prototheca zopfii outbreak.

PubMed

da Costa, Elizabeth Oliveira; Ribeiro, Márcio Garcia; Ribeiro, Andréa Rentz; Rocha, Noeme Sousa; de Nardi Júnior, Geraldo

2004-07-01

Biopsy by fine needle aspiration together with microbiological examination and scanning electron microscopy were evaluated in diagnosis of clinical bovine mastitis in a Prototheca zopfii outbreak. Fine needle aspiration was performed in 21 mammary quarters from ten Holstein cows presenting clinical mastitis caused by P. zopfii. The algae were previously identified in the microbiological examination of milk collected from these cows. Material aspirated from these 21 mammary glands was submitted to cytological staining (Gram, Giemsa and/or Shor staining). Fine needle aspiration enabled cytological identification of the algae in these 21 mammary glands, from which P. zopfii was isolated in the milk. Simultaneously, five mammary fragments collected by fine needle aspiration from these 21 mammary glands presenting clinical mastitis were also submitted to microbiological examination. P. zopfii was also isolated from these five fragments. Scanning electron microscopy technique also identified three of these five P zopfii strains isolated from mammary fragments collected by cytological aspiration. These results suggest that fine needle aspiration may be an alternative method for the diagnosis of clinical mastitis.

Evaluation of intracameral injection of ranibizumab and bevacizumab on the corneal endothelium by scanning electron microscopy.

PubMed

Ari, Seyhmus; Nergiz, Yusuf; Aksit, Ihsan; Sahin, Alparslan; Cingu, Kursat; Caca, Ihsan

2015-03-01

To evaluate the effects of intracameral injection of ranibizumab and bevacizumab on the corneal endothelium by scanning electron microscopy (SEM). Twenty-eight female rabbits were randomly divided into four equal groups. Rabbits in groups 1 and 2 underwent intracameral injection of 1 mg/0.1 mL and 0.5 mg/0.05 mL ranibizumab, respectively; group 3 was injected with 1.25 mg/0.05 mL bevacizumab. All three groups were injected with a balanced salt solution (BSS) into the anterior chamber of the left (fellow) eye. None of the rabbits in group 4 underwent an injection. Corneal thickness and intraocular pressure were measured before the injections, on the first day, and in the first month after injection. The rabbits were sacrificed and corneal tissues were excised in the first month after injection. Specular microscopy was used for the corneal endothelial cell count. Endothelial cell density was assessed and comparisons drawn between the groups and the control. Micrographs were recorded for SEM examination. The structure of the corneal endothelial cells, the junctional area of the cell membrane, the distribution of microvillus, and the cell morphology of the eyes that underwent intracameral injection of vascular endothelial growth factor (VEGF), BSS, and the control group were compared. Corneal thickness and intraocular pressure were not significantly different between the groups that underwent anti-VEGF or BSS injection and the control group on the first day and in the first month of injection. The corneal endothelial cell count was significantly diminished in all three groups; predominantly in group 1 and 2 (P<0.05). The SEM examination revealed normal corneal endothelial histology in group 3 and the control group. Eyes in group 1 exhibited indistinctness of corneal endothelial cell borders, microvillus loss in the luminal surface, excessive blebbing, and disintegration of intercellular junctions. In group 2, the cell structure of the corneal endothelium and intercellular junctions were normal. However, a relative reduction was observed in the microvillus density of endothelial cells. Although eyes in group 3 were morphologically similar to fellow eyes and the control group, disarrangement in endothelial cell borders was evident. The SEM examination pointed out deterioration in endothelial cell morphology after intracameral injection of 1 and 0.5 mg ranizumab. However, the effects of intracameral bevacizumab injection on corneal endothelial cells were similar to those found in fellow eyes and the control group. Further large-scale studies that examine the cellular changes by transmission electron microscopy are required to support the results of the present study that evaluates the structural changes in endothelial cells by SEM.

High Sensitivity and Specificity of Clinical Microscopy in Rural Health Facilities in Western Kenya Under an External Quality Assurance Program

PubMed Central

Wafula, Rebeccah; Sang, Edna; Cheruiyot, Olympia; Aboto, Angeline; Menya, Diana; O'Meara, Wendy Prudhomme

2014-01-01

Microscopic diagnosis of malaria is a well-established and inexpensive technique that has the potential to provide accurate diagnosis of malaria infection. However, it requires both training and experience. Although it is considered the gold standard in research settings, the sensitivity and specificity of routine microscopy for clinical care in the primary care setting has been reported to be unacceptably low. We established a monthly external quality assurance program to monitor the performance of clinical microscopy in 17 rural health centers in western Kenya. The average sensitivity over the 12-month period was 96% and the average specificity was 88%. We identified specific contextual factors that contributed to inadequate performance. Maintaining high-quality malaria diagnosis in high-volume, resource-constrained health facilities is possible. PMID:24935953

The Surface of Titan: Arecibo Radar Observations

NASA Technical Reports Server (NTRS)

Campbell, D. B.; Black, G. J.; Carter, L. M.; Hine, A. A.; Margot, J. L.; Nolan, M. C.; Ostro, S. J.

2002-01-01

The Arecibo 12.6 cm radar system was used to observe Titan in 1999, 2000 and 2001. The mean value of the radar albedo is 0.16 and the polarization ratio is 0.35. For some longitudes the echo has a specular component although most of the echo power is contained in a diffuse component. Additional information is contained in the original extended abstract.

Intelligent Network-Centric Sensors Development Program

DTIC Science & Technology

2012-07-31

Image sensor Configuration: ; Cone 360 degree LWIR PFx Sensor: •■. Image sensor . Configuration: Image MWIR Configuration; Cone 360 degree... LWIR PFx Sensor: Video Configuration: Cone 360 degree SW1R, 2. Reasoning Process to Match Sensor Systems to Algorithms The ontological...effects of coherent imaging because of aberrations. Another reason is the specular nature of active imaging. Both contribute to the nonuniformity

Scattering from Rock and Rock Outcrops

DTIC Science & Technology

2014-09-30

orientations and size distributions reflect the internal fault organization of the bedrock. The plot in Fig. 3 displays experimentally determined PFA...mechanisms contributing could be scattering from small scale roughness combined with specular scattering from facets oriented close to normal incidence to...Larvik, Norway made with a stereo photogrammetry system. 7 IMPACT/APPLICATIONS The primary work completed over the course of this project

Charge-induced equilibrium dynamics and structure at the Ag(001)–electrolyte interface

DOE PAGES

Karl Jr., Robert M.; Barbour, Andi; Komanicky, Vladimir; ...

2015-06-08

We have measured the applied potential dependent rate of atomic step motion of the Ag (001) surface in weak NaF electrolyte using a new extension of the technique of X-ray Photon Correlation Spectroscopy (XPCS). Furthermore, concurrent specular x-ray scattering measurements reveal how the ordering of the water layers at the interface correlates with the dynamics.

PASSIVELY ESTIMATING INDEX OF REFRACTION FOR SPECULAR REFLECTORS USING POLARIMETRIC HYPERSPECTRAL IMAGING

DTIC Science & Technology

2016-12-22

23 6 Band-averaged radiance image with checkerboard is shown in the upper left. The 2-D Fourier transform of the image is...red is 1) that is multiplied by the Fourier transform of the original image. The inverse Fourier transform is then taken to get the final image with...Polarization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 IFTS Imaging Fourier Transform Spectrometer

A general method for computing the total solar radiation force on complex spacecraft structures

NASA Technical Reports Server (NTRS)

Chan, F. K.

1981-01-01

The method circumvents many of the existing difficulties in computational logic presently encountered in the direct analytical or numerical evaluation of the appropriate surface integral. It may be applied to complex spacecraft structures for computing the total force arising from either specular or diffuse reflection or even from non-Lambertian reflection and re-radiation.

Modern Display Technologies for Airborne Applications.

DTIC Science & Technology

1983-04-01

the case of LED head-down direct view displays, this requires that special attention be paid to the optical filtering , the electrical drive/address...effectively attenuates the LED specular reflectance component, the colour and neutral density filtering attentuate the diffuse component and the... filter techniques are planned for use with video, multi- colour and advanced versions of numeric, alphanumeric and graphic displays; this technique

Etch depth mapping of phase binary computer-generated holograms by means of specular spectroscopic scatterometry

NASA Astrophysics Data System (ADS)

Korolkov, Victor P.; Konchenko, Alexander S.; Cherkashin, Vadim V.; Mironnikov, Nikolay G.; Poleshchuk, Alexander G.

2013-09-01

Detailed analysis of etch depth map for phase binary computer-generated holograms intended for testing aspheric optics is a very important task. In particular, diffractive Fizeau null lenses need to be carefully tested for uniformity of etch depth. We offer a simplified version of the specular spectroscopic scatterometry method. It is based on the spectral properties of binary phase multi-order gratings. An intensity of zero order is a periodical function of illumination light wave number. The grating grooves depth can be calculated as it is inversely proportional to the period. Measurement in reflection allows one to increase the phase depth of the grooves by a factor of 2 and measure more precisely shallow phase gratings. Measurement uncertainty is mainly defined by the following parameters: shifts of the spectrum maximums that occur due to the tilted grooves sidewalls, uncertainty of light incidence angle measurement, and spectrophotometer wavelength error. It is theoretically and experimentally shown that the method we describe can ensure 1% error. However, fiber spectrometers are more convenient for scanning measurements of large area computer-generated holograms. Our experimental system for characterization of binary computer-generated holograms was developed using a fiber spectrometer.

Colour Model for Outdoor Machine Vision for Tropical Regions and its Comparison with the CIE Model

NASA Astrophysics Data System (ADS)

Sahragard, Nasrolah; Ramli, Abdul Rahman B.; Hamiruce Marhaban, Mohammad; Mansor, Shattri B.

2011-02-01

Accurate modeling of daylight and surface reflectance are very useful for most outdoor machine vision applications specifically those which are based on color recognition. Existing daylight CIE model has drawbacks that limit its ability to predict the color of incident light. These limitations include lack of considering ambient light, effects of light reflected off the ground, and context specific information. Previously developed color model is only tested for a few geographical places in North America and its accountability is under question for other places in the world. Besides, existing surface reflectance models are not easily applied to outdoor images. A reflectance model with combined diffuse and specular reflection in normalized HSV color space could be used to predict color. In this paper, a new daylight color model showing the color of daylight for a broad range of sky conditions is developed which will suit weather conditions of tropical places such as Malaysia. A comparison of this daylight color model and daylight CIE model will be discussed. The colors of matte and specular surfaces have been estimated by use of the developed color model and surface reflection function in this paper. The results are shown to be highly reliable.

Acoustic radiosity for computation of sound fields in diffuse environments

NASA Astrophysics Data System (ADS)

Muehleisen, Ralph T.; Beamer, C. Walter

2002-05-01

The use of image and ray tracing methods (and variations thereof) for the computation of sound fields in rooms is relatively well developed. In their regime of validity, both methods work well for prediction in rooms with small amounts of diffraction and mostly specular reflection at the walls. While extensions to the method to include diffuse reflections and diffraction have been made, they are limited at best. In the fields of illumination and computer graphics the ray tracing and image methods are joined by another method called luminous radiative transfer or radiosity. In radiosity, an energy balance between surfaces is computed assuming diffuse reflection at the reflective surfaces. Because the interaction between surfaces is constant, much of the computation required for sound field prediction with multiple or moving source and receiver positions can be reduced. In acoustics the radiosity method has had little attention because of the problems of diffraction and specular reflection. The utility of radiosity in acoustics and an approach to a useful development of the method for acoustics will be presented. The method looks especially useful for sound level prediction in industrial and office environments. [Work supported by NSF.

[Development and application of electroanalytical methods in biomedical fields].

PubMed

Kusu, Fumiyo

2015-01-01

To summarize our electroanalytical research in the biomedical field over the past 43 years, this review describes studies on specular reflection measurement, redox potential determination, amperometric acid sensing, HPLC with electrochemical detection, and potential oscillation across a liquid membrane. The specular reflection method was used for clarifying the adsorption of neurotransmitters and their related drugs onto a gold electrode and the interaction between dental alloys and compound iodine glycerin. A voltammetric screening test using a redox potential for the antioxidative effect of flavonoids was proposed. Amperometric acid sensing based on the measurement of the reduction prepeak current of 2-methyl-1,4-naphthoquinone (VK3) or 3,5-di-tert-buty1-1,2-benzoquinone (DBBQ) was applied to determine acid values of fats and oils, titrable acidity of coffee, and enzyme activity of lipase, free fatty acids (FFAs) in serum, short-chain fatty acids in feces, etc. The electrode reactions of phenothiazines, catechins, and cholesterol were applied to biomedical analysis using HPLC with electrochemical detection. A three-channel electrochemical detection system was utilized for the sensitive determination of redox compounds in Chinese herbal medicines. The behavior of barbituric acid derivatives was examined based on potential oscillation measurements.

Interpretation of lunar and planetary electromagnetic scattering using the full wave solutions

NASA Technical Reports Server (NTRS)

Bahar, E.; Haugland, M.

1993-01-01

Bistatic radar experiments carried out during the Apollo 14, 15, and 16 missions provide a very useful data set with which to compare theoretical models and experimental data. Vesecky, et al. report that their model for near grazing angles compares favorably with experimental data. However, for angles of incidence around 80 degrees, all the analytical models considered by Vesecky, et al. predict values for the quasi-specular cross sections that are about half the corresponding values taken from the Apollo 16 data. In this work, questions raised by this discrepancy between the reported analytical and experimental results are addressed. The unified full wave solutions are shown to be in good agreement with the bistatic radar taken during Apollo 14 and 16 missions. Using the full wave approach, the quasi-specular contributions to the scattered field from the large scale surface roughness as well as the diffuse Bragg-like scattering from the small scale surface roughness are accounted for in a unified self-consistent manner. Since the full wave computer codes for the scattering cross sections contain ground truth data only, it is shown how it can be reliably used to predict the rough surface parameters of planets based on the measured data.

Numerical modeling of laser assisted tape winding process

NASA Astrophysics Data System (ADS)

Zaami, Amin; Baran, Ismet; Akkerman, Remko

2017-10-01

Laser assisted tape winding (LATW) has become more and more popular way of producing new thermoplastic products such as ultra-deep sea water riser, gas tanks, structural parts for aerospace applications. Predicting the temperature in LATW has been a source of great interest since the temperature at nip-point plays a key role for mechanical interface performance. Modeling the LATW process includes several challenges such as the interaction of optics and heat transfer. In the current study, numerical modeling of the optical behavior of laser radiation on circular surfaces is investigated based on a ray tracing and non-specular reflection model. The non-specular reflection is implemented considering the anisotropic reflective behavior of the fiber-reinforced thermoplastic tape using a bidirectional reflectance distribution function (BRDF). The proposed model in the present paper includes a three-dimensional circular geometry, in which the effects of reflection from different ranges of the circular surface as well as effect of process parameters on temperature distribution are studied. The heat transfer model is constructed using a fully implicit method. The effect of process parameters on the nip-point temperature is examined. Furthermore, several laser distributions including Gaussian and linear are examined which has not been considered in literature up to now.

Polychromatic flow cytometry is more sensitive than microscopy in detecting small monoclonal plasma cell populations.

PubMed

Tran, Daniel N; Smith, Sandy A B C; Brown, David A; Parker, Andrew J C; Joseph, Joanne E; Armstrong, Nicola; Sewell, William A

2017-03-01

There is an emerging role for flow cytometry (FC) in the assessment of small populations of plasma cells (PC). However, FC's utility has been questioned due to consistent underestimation of the percentage of PC compared to microscopy. A retrospective study was performed on bone marrow samples analysed by 8-colour FC. Plasma cell populations were classified as polyclonal or monoclonal based on FC analysis. FC findings were compared with microscopy of aspirates, histology and immunohistochemistry of trephine biopsies, and immunofixation (IFX) of serum and/or urine. FC underestimated PC compared to aspirate and trephine microscopy. The 10% diagnostic cutoff for MM on aspirate microscopy corresponded to a 3.5% cutoff on FC. Abnormal plasma cell morphology by aspirate microscopy and clonality by FC correlated in 229 of 294 cases (78%). However, in 50 cases, FC demonstrated a monoclonal population but microscopy reported no abnormality. In 15 cases, abnormalities were reported by microscopy but not by FC. Clonality assessment by trephine microscopy and FC agreed in 251/280 cases (90%), but all 29 discordant cases were monoclonal by FC and not monoclonal by microscopy. These cases had fewer PC and proportionally more polyclonal PC, and when IFX detected a paraprotein, it had the same light chain as in the PC determined by FC. FC was more sensitive in detecting monoclonal populations that were small or accompanied by polyclonal PC. This study supports the inclusion of FC in the evaluation of PC, especially in the assessment of small populations. © 2016 International Clinical Cytometry Society. © 2016 International Clinical Cytometry Society.

Comparison between reflectance confocal microscopy and two-photon microscopy in early detection of cutaneous radiation injury in a mouse model in-vivo.

PubMed

Jang, Won Hyuk; Kwon, Soonjae; Shim, Sehwan; Jang, Won-Suk; Myung, Jae Kyung; Yang, Sejung; Park, Sunhoo; Kim, Ki Hean

2018-05-12

Cutaneous radiation injury (CRI) is a skin injury caused by high dose exposure of ionizing radiation (IR). For proper treatment, early detection of CRI before clinical symptoms is important. Optical microscopic techniques such as reflectance confocal microscopy (RCM) and two-photon microscopy (TPM) have been tested as the early diagnosis method by detecting cellular changes. In this study, RCM and TPM were compared in the detection of cellular changes caused by CRI in an in-vivo mouse model. CRI was induced on the mouse hindlimb skin with various IR doses and the injured skin regions were imaged longitudinally by both modalities until the onset of clinical symptoms. Both RCM and TPM detected the changes of epidermal cells and sebaceous glands before clinical symptoms in different optical contrasts. RCM detected changes of cell morphology and scattering property based on light reflection. TPM detected detail changes of cellular structures based on autofluorescence of cells. Since both RCM and TPM were sensitive to the early-stage CRI by using different contrasts, the optimal method for clinical CRI diagnosis could be either individual methods or their combination. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

The Use of Routine Postoperative Microscopy and Culture Screening Following Elective Hip and Knee Arthroplasty: An Unnecessary Cost With No Effect on Clinical Management?

PubMed

Kemp, Mark A; Martina, Ka; Collins, Claire L; Salmon, Lucy J; Gooden, Benjamin R; Lyons, Matthew C

2017-04-01

The use of microscopy and culture screening to detect pathogenic microorganisms followed by a decolonization protocol is a widely performed practice prior to elective hip and knee arthroplasty. In our center, the routine care of hip and knee arthroplasty also involves postoperative screening including direct culture of the surgical site. The aim of this study was to assess the frequency of pathogen detection following these tests and to determine whether routine postoperative screening, with particular reference to postoperative surgical site culture, led to any change in clinical management of these patients. A series of 1000 patients undergoing hip or knee arthroplasty at The Mater Hospital between January 2014 and December 2015 were identified from our arthroplasty database. Results of preoperative and postoperative microscopy and culture screening were reviewed by 2 independent researchers. Of the 1000 subjects, positive microscopy and culture results were identified in 88 patients (8.8%) preoperatively and 5 patients (0.5%) postoperatively. None of the 1000 postoperative surgical site swabs had a positive microscopy and culture screen. All the 5 positive postoperative microscopy and culture screen results were in patients who had positive cultures preoperatively. There were no positive postoperative microscopy and culture screen results in patients who had had negative preoperative results. Postoperative screening was performed at a cost of AUS$213 per patient. Routine postoperative surgical site culture following hip and knee arthroplasty does not alter clinical management, has a significant associated financial cost, and has the potential to expose the patient to a risk of surgical site infection and is therefore not supported. Copyright © 2016 Elsevier Inc. All rights reserved.

In vivo multiphoton microscopy of deep tissue with gradient index lenses

NASA Astrophysics Data System (ADS)

Levene, Michael J.; Dombeck, Daniel A.; Williams, Rebecca M.; Skoch, Jesse; Hickey, Gregory A.; Kasischke, Karl A.; Molloy, Raymond P.; Ingelsson, Martin; Stern, Edward A.; Klucken, Jochen; Bacskai, Brian J.; Zipfel, Warren R.; Hyman, Bradley T.; Webb, Watt W.

2004-06-01

Gradient index lenses enable multiphoton microscopy of deep tissues in the intact animal. In order to assess their applicability to clinical research, we present in vivo multiphoton microscopy with gradient index lenses in brain regions associated with Alzheimer's disease and Parkinson's disease in both transgenic and wild-type mice. We also demonstrate microscopy of ovary in wild type mouse using only intrinsic fluorescence and second harmonic generation, signal sources which may prove useful for both the study and diagnosis of cancer.

Safety and efficacy of two ocular anesthetic methods for phacoemulsification: topical anesthesia and viscoanesthesia (VisThesia).

PubMed

Perone, J M; Popovici, A; Ouled-Moussa, R; Herasymyuk, O; Reynders, S

2007-01-01

VisThesia is a new ophthalmic viscosurgical device (OVD) which has 1% lidocaine combined with 1.5% sodium hyaluronate. This is a prospective evaluation of the safety and efficacy of VisThesia used in association with phacoemulsification. A total of 114 eyes were divided into two groups. Fifty-nine eyes were treated with tetracaine + oxybuprocaine topical anesthesia and DuoVisc OVD and 55 eyes were treated with VisThesia, for use as both topical anesthetic and OVD. Endothelial cell counts were measured at 30 days postoperatively and compared to preoperative baseline values. Pain and discomfort was subjectively evaluated by patients using a visual analog pain scale (0-10). All surgeries were uneventful with no intraoperative or immediate postoperative complications. Patients receiving topical anesthesia had a mean pain score of 1.1+/-6.8 compared to a mean score of 1.3+/-4.6 for patients receiving VisThesia (p=0.59). Postoperatively, endothelial cell loss at 1 month was greater for patients receiving VisThesia (20.32%+/-43.75) than for those receiving the topical anesthetic (8.8%+/-59.6; p<0.0001). The results from the visual analog pain scale were comparable between groups, showing that VisThesia provides similar pain relief to topical anesthesia. Specular microscopy performed at 30 days postoperatively showed a significantly greater loss of endothelial cells with the use of VisThesia, suggesting that the 1% lidocaine concentration used in VisThesia may be toxic to corneal endothelial cells.

Corneal endothelial cell density and morphology in patients with acromegaly.

PubMed

Hatipoglu, Esra; Arici, Ceyhun; Arslan, Osman Sevki; Dikkaya, Funda; Sultan, Pinar; Kadioglu, Pinar; Gundogdu, Sadi

2014-12-01

Acromegaly has various impacts on many organs. The ophthalmologic effects of acromegaly have not yet been investigated in detail. The aim of the current study was to evaluate qualitative and quantitative changes in corneal endothelial cells and central corneal thickness (CCT) of the patients with acromegaly. In this prospective, cross-sectional study, 128 eyes of 64 patients with acromegaly (female/male=40/24) and 208 eyes of 104 age and gender-matched healthy volunteers (female/male=69/35) were included. Endothelial cell density (ECD), cellular area (CA), coefficient of variation (CV) in cell size, percentage of hexagonal cells, and CCT were measured in patients with acromegaly and in healthy volunteers using the noncontact specular microscopy (SP-3000P: Topcon Corporation, Tokyo, Japan). ECD and CA were lower in cases with acromegaly than in controls (ECD in acromegaly: 2615.65 cell/mm(2) and in controls: 2700.35 cell/mm(2); p=0.002. CA in acromegaly: 382.30μm(2) and in controls: 400.30μm(2); p=0.02). In the entire group with acromegaly, the time elapsed since diagnosis was positively correlated with CA and was negatively correlated with ECD (r=+0.39, p=0.001 and r=-0.42, p=0.001). The endothelial layer of the cornea may be under risk of impairment with prolonged disease duration in acromegaly. Consistency of the corneal endothelium should be also sought during long-term follow-up of the cases with acromegaly. Copyright © 2014 Elsevier Ltd. All rights reserved.

Performance of rapid diagnostic test, blood-film microscopy and PCR for the diagnosis of malaria infection among febrile children from Korogwe District, Tanzania.

PubMed

Mahende, Coline; Ngasala, Billy; Lusingu, John; Yong, Tai-Soon; Lushino, Paminus; Lemnge, Martha; Mmbando, Bruno; Premji, Zul

2016-07-26

Rapid diagnostic tests (RDT) and light microscopy are still recommended for diagnosis to guide the clinical management of malaria despite difficult challenges in rural settings. The performance of these tests may be affected by several factors, including malaria prevalence and intensity of transmission. The study evaluated the diagnostic performance of malaria RDT, light microscopy and polymerase chain reaction (PCR) in detecting malaria infections among febrile children at outpatient clinic in Korogwe District, northeastern Tanzania. The study enrolled children aged 2-59 months with fever and/or history of fever in the previous 48 h attending outpatient clinics. Blood samples were collected for identification of Plasmodium falciparum infection using histidine-rich-protein-2 (HRP-2)-based malaria RDT, light microscopy and conventional PCR. A total of 867 febrile patients were enrolled into the study. Malaria-positive samples were 85/867 (9.8 %, 95 % CI, 7.9-12.0 %) by RDT, 72/867 (8.3 %, 95 % CI, 6.5-10.1 %) by microscopy and 79/677 (11.7 %, 95 % CI, 9.3-14.3 %) by PCR. The performance of malaria RDT compared with microscopy results had sensitivity and positive predictive value (PPV) of 88.9 % (95 % CI, 79.3-95.1 %) and 75.3 % (95 % CI, 64.8-84.0 %), respectively. Confirmation of P. falciparum infection with PCR analysis provided lower sensitivity and PPV of 88.6 % (95 % CI, 79.5-94.7 %) and 84.3 % (95 % CI, 74.7-91.4 %) for RDT compared to microscopy. Diagnosis of malaria infection is still a challenge due to variation in results among diagnostic methods. HRP-2 malaria RDT and microscopy were less sensitive than PCR. Diagnostic tools with high sensitivity are required in areas of low malaria transmission.

Rapid Diagnosis of Ethylene Glycol Poisoning by Urine Microscopy.

PubMed

Sheta, Hussam Mahmoud; Al-Najami, Issam; Christensen, Heidi Dahl; Madsen, Jonna Skov

2018-06-14

BACKGROUND Ethylene glycol poisoning remains an important presentation to Emergency Departments. Quick diagnosis and treatment are essential to prevent renal failure and life-threating complications. CASE REPORT In this case report, we present a patient who was admitted unconscious to the hospital. Ethylene glycol poisoning was immediately suspected, because the patient had previously been hospitalized with similar symptoms after intake of antifreeze coolant. A urine sample was sent for microscopy and showed multiple calcium oxalate monohydrate (COM) crystals, which supported the clinical suspicion of ethylene glycol poisoning. The patient was treated with continuous intravenous ethyl alcohol infusion and hemodialysis. Two days after admission, the patient was awake and in clinical recovery. CONCLUSIONS Demonstration of COM crystals using microscopy of a urine sample adds valuable information supporting the clinical suspicion of ethylene glycol poisoning, and may serve as an easy, quick, and cheap method that can be performed in any emergency setting.

High sensitivity and specificity of clinical microscopy in rural health facilities in western Kenya under an external quality assurance program.

PubMed

Wafula, Rebeccah; Sang, Edna; Cheruiyot, Olympia; Aboto, Angeline; Menya, Diana; O'Meara, Wendy Prudhomme

2014-09-01

Microscopic diagnosis of malaria is a well-established and inexpensive technique that has the potential to provide accurate diagnosis of malaria infection. However, it requires both training and experience. Although it is considered the gold standard in research settings, the sensitivity and specificity of routine microscopy for clinical care in the primary care setting has been reported to be unacceptably low. We established a monthly external quality assurance program to monitor the performance of clinical microscopy in 17 rural health centers in western Kenya. The average sensitivity over the 12-month period was 96% and the average specificity was 88%. We identified specific contextual factors that contributed to inadequate performance. Maintaining high-quality malaria diagnosis in high-volume, resource-constrained health facilities is possible. © The American Society of Tropical Medicine and Hygiene.

Proposed Standards for Ladar Signatures

DTIC Science & Technology

1977-04-01

BDR and LRCS geometricas . parometers --------------------- 5 Figure 2. Geometry for sphere LRC:-------------------------------- 18 Figure 3. Mirror...take in the followinig LRCS definitions. Strictly speaking it is not correct to associate the LRCS of a specular spnere (a = la 2) with the "effective... Corrections due to near- field geometry or a radius of curvature on the impin ging beam have been mentioned before (36]. Also, errors due to surface

Automated Synthetic Scene Generation

DTIC Science & Technology

2014-07-01

Using the Beard-Maxwell BRDF model , the BRDF from Equations (3.3) and (3.4) is composed of specular, diffuse, and volumetric terms such that x y zSun... models help organizations developing new remote sensing instruments anticipate sensor performance by enabling the ability to create synthetic imagery...for proposed sensor before a sensor is built. One of the largest challenges in modeling realistic synthetic imagery, however, is generating the

Formulation of Ames 24E2 IR-black coating

NASA Technical Reports Server (NTRS)

Smith, Sheldon M.

1991-01-01

The formulation of Ames 24E2 IR-black coating and a rationale for the selection of its components are given. The objective was to make a very rough, very thick, and highly absorbing coating to attenuate the specular reflectance of telescope baffles at far-IR wavelengths. Application and curing instructions are also given. Outgassing measurements are quite low following a 24-hour radiative cure.

Electromagnetic scattering from microwave absorbers - Laboratory verification of the coupled wave theory

NASA Technical Reports Server (NTRS)

Gasiewski, A. J.; Jackson, D. M.

1992-01-01

W-band measurements of the bistatic scattering function of some common microwave absorbing structures, including periodic wedge-type and pyramid-type iron-epoxy calibration loads and flat carbon-foam 'Echosorb' samples, were made using a network analyzer interface to a focused-lens scattering range. Swept frequency measurements over the 75-100 GHz band revealed specular and Bragg reflection characteristics in the measured data.