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Illumination Conditions (illumination + condition)
Selected AbstractsInteractive Global Photon MappingCOMPUTER GRAPHICS FORUM, Issue 4 2009B. Fabianowski Abstract We present a photon mapping technique capable of computing high quality global illumination at interactive frame rates. By extending the concept of photon differentials to efficiently handle diffuse reflections, we generate footprints at all photon hit points. These enable illumination reconstruction by density estimation with variable kernel bandwidths without having to locate the k nearest photon hits first. Adapting an efficient BVH construction process for ray tracing acceleration, we build photon maps that enable the fast retrieval of all hits relevant to a shading point. We present a heuristic that automatically tunes the BVH build's termination criterion to the scene and illumination conditions. As all stages of the algorithm are highly parallelizable, we demonstrate an implementation using NVidia's CUDA manycore architecture running at interactive rates on a single GPU. Both light source and camera may be freely moved with global illumination fully recalculated in each frame. [source] Controlling Photoactivity in Ultrathin Hematite Films for Solar Water-SplittingADVANCED FUNCTIONAL MATERIALS, Issue 7 2010Florian Le Formal Abstract A promising route to increase the performance of hematite (,-Fe2O3) photoelectrodes for solar hydrogen production through water-splitting is to use an extremely thin layer of this visible light absorber on a nanostructured scaffold. However, the typically poor performance of ultrathin (ca. 20,nm) films of hematite has been the limiting factor in implementing this approach. Here, the surprising effect of a substrate pretreatment using tetraethoxysilicate (TEOS) is reported; it results in drastic improvements in the photoperformance of 12.5,nm thick films of hematite. These films exhibit a water oxidation photocurrent onset potential at 1.1,V versus the reversible hydrogen electrode (vs. RHE) and a plateau current of 0.63,mA cm,2 at 1.5,V vs. RHE under standard illumination conditions, representing the highest reported performance for ultrathin hematite films. In contrast, almost no photoactivity is observed for the photoanode with the same amount of hematite on an untreated substrate. A detailed study of the effects of the TEOS treatment shows that a monolayer of SiOx is formed, which acts to change the hematite nucleation and growth mechanism, increases its crystallinity, reduces the concentration of carrier trapping states of the ultrathin films, and suggests its further application to quantum-dot and extremely-thin-absorber (ETA)-type solar cells. [source] Bigger is better: implications of body size for flight ability under different light conditions and the evolution of alloethism in bumblebeesFUNCTIONAL ECOLOGY, Issue 6 2007A. KAPUSTJANSKIJ Summary 1In social insects, reproductive success and survival of the colony critically depend on the colony's ability to efficiently allocate workers to the various tasks which need to be performed. In bumblebees, workers show a large variation of body size within a colony. Large workers tend to leave the nest and forage for nectar and pollen, whereas small workers stay inside the nest and fulfill nest duties. It was speculated that size-related differences of the sensory system might contribute to alloethism found in bumblebee colonies. 2In the first part, we investigated how body size determines eye morphology. We measured several eye parameters of Bombus terrestris workers and drones. In both, workers and drones, larger individuals had larger eyes with larger facet diameters, more ommatidia and larger ocelli. At similar body size, drones exhibited larger eyes and ocelli compared to workers. Due to theoretical considerations, we predict that large individuals with large eyes should be better able to operate in illumination conditions of lower intensity than small individuals, since ommatidial sensitivity is proportional to the square of facet diameter. 3In the second part, we tested this prediction. In a behavioural experiment, we first caught bumblebees of various sizes in the field and then determined the lowest light intensity level at which they are just able to fly under controlled laboratory conditions. We tested workers of B. terrestris and B. pascuorum, and workers and drones of B. lapidarius. Large bumblebees were able to fly under lower light levels compared to small bees, with light intensity thresholds ranging from 1·1 to 5·5 lux. 4Our results indicate that the increased light sensitivity of the visual system of large bumblebees allows them to fly under poor light conditions, for example, very early in the morning or late at dusk. This is of potential benefit to the survival of a bumblebee colony since flowers that open early in the morning usually have accumulated a relatively high amount of nectar and pollen throughout the night, and large bumblebees can utilize these resources earlier than most other bees. Thus, our findings have important implications for the understanding of the functional significance and evolution of alloethism in bumblebee colonies. [source] Three-Dimensional Bulk Heterojunction Morphology for Achieving High Internal Quantum Efficiency in Polymer Solar CellsADVANCED FUNCTIONAL MATERIALS, Issue 15 2009Jang Jo Abstract Here, an investigation of three-dimensional (3D) morphologies for bulk heterojunction (BHJ) films based on regioregular poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61 -butyric acid methyl ester (PCBM) is reported. Based on the results, it is demonstrated that optimized post-treatment, such as solvent annealing, forces the PCBM molecules to migrate or diffuse toward the top surface of the BHJ composite films, which induces a new vertical component distribution favorable for enhancing the internal quantum efficiency (,IQE) of the devices. To investigate the 3D BHJ morphology, novel time-of-flight secondary-ion mass spectroscopy studies are employed along with conventional methods, such as UV-vis absorption, X-ray diffraction, and high-resolution transmission electron microscopy studies. The ,IQE of the devices are also compared after solvent annealing for different times, which clearly shows the effect of the vertical component distribution on the performance of BHJ polymer solar cells. In addition, the fabrication of high-performance P3HT:PCBM solar cells using the optimized solvent-annealing method is reported, and these cells show a mean power-conversion efficiency of 4.12% under AM 1.5G illumination conditions at an intensity of 100,mW cm,2. [source] UV-vis-Induced Vitrification of a Molecular Crystal,ADVANCED FUNCTIONAL MATERIALS, Issue 10 2007T. Naito Abstract A charge-transfer complex of 2,5-dimethyl- N,N,-dicyanoquinonediimine (DM) with silver (crystalline Ag(DM)2, defined as ,) is irreversibly transformed by UV-vis illumination. Depending on the illumination conditions, three new types of solids (defined as ,, ,, and ,) with different structural and physical properties are obtained and examined by a variety of analytical techniques, including solid-state, high-resolution, cross-polarization magic angle spinning (CP-MAS) 13C,NMR, elemental analysis (EA), mass spectrometry (MS), X-ray absorption fine structure (XAFS), and powder X-ray diffraction (XRD). The CP-MAS, EA, MS, and XAFS results indicate that compound , is a glass state of Ag(DM)2. The transformation from crystalline (,) to amorphous (,) solid Ag(DM)2 is an irreversible exothermic glass transition (glass-transition temperature 155.2,°C; ,H,=,,126.8,kJ,mol,1), which implies that the glass form is thermodynamically more stable than the crystalline form. Compound , (Ag(DM)1.5) consists of silver nanoparticles (diameter (7,±,2),nm ) dispersed in a glassy matrix of neutral DM molecules. The N,CN,Ag coordination bonds of the , form are not maintained in the , form. Decomposition of , by intense illumination results in a white solid (,), identified as being composed of silver nanoparticles (diameter (60,±,10),nm). Physical and spectroscopic (XAFS) measurements, together with XRD analysis, indicate that the silver nanoparticles in both , and , are crystalline with lattice parameters similar to bulk silver; however, the magnetic susceptibilities differ from bulk silver. [source] Formation of Silver Nanoprisms with Surface Plasmons at Communication Wavelengths,ADVANCED FUNCTIONAL MATERIALS, Issue 6 2006V. Bastys Abstract Silver nanoprisms with strong absorption in the near-IR have been synthesized using a modification of the photoinduced method by illuminating preformed silver seeds under different illumination conditions. Low-intensity light-emitting diodes and white light combined with different color filters are used as light sources. The lateral dimensions of the nanoprisms are found to be correlated in a quasilinear fashion with the emission wavelength and the position of the main in-plane dipole plasmon band. The structural characterization of the Ag nanoparticles, carried out using scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, and electron diffraction, reveal that the particles are flat and have a single-crystal face-centered-cubic structure. Time-resolved studies suggest that the nanoprisms are formed by steady consumption of the original Ag seeds with little variation of the aspect ratio after a short induction time. [source] Original article: Thermal and light degradation kinetics of anthocyanin extracts from mangosteen peel (Garcinia mangostana L.)INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 9 2010Renan C. Chisté Summary The stability and half-life time of anthocyanin extracts from mangosteen peel were studied under controlled oxygen supply, undergoing the influence of light source (fluorescent, incandescent, infrared and ultraviolet) and storage temperature (5, 28, 40 and 50 °C). The kinetic parameters for anthocyanin degradation, under different illumination conditions fit the first-order reaction model, and the exposition under fluorescent light resulted in a higher half-life time (597 h), followed by incandescent (306 h), ultraviolet (177 h) and infrared (100 h). The kinetic behaviour for the storage in different temperatures also fit the first order, and at 5 °C the highest half-life time (4006 h) was found, followed by 28 °C (370 h), 40 °C (125 h) and 50 °C (93 h). The activation energy was 14.7 Kcal.mol,1, and Q10 values showed that at 5 °C the anthocyanin extracts were more sensitive to storage temperature changes compared to the other tested temperatures. [source] Enhanced visualization of histological samples with an adjustable RGB contrast system with application for tissue used in photodynamic therapyMICROSCOPY RESEARCH AND TECHNIQUE, Issue 6 2008Wilma Regina Barrionuevo Abstract The analysis of histological sections has long been a valuable tool in the pathological studies. The interpretation of tissue conditions, however, relies directly on visual evaluation of tissue slides, which may be difficult to interpret because of poor contrast or poor color differentiation. The Chromatic Contrast Visualization System (CCV) combines an optical microscope with electronically controlled light-emitting diodes (LEDs) in order to generate adjustable intensities of RGB channels for sample illumination. While most image enhancement techniques rely on software post-processing of an image acquired under standard illumination conditions, CCV produces real-time variations in the color composition of the light source itself. The possibility of covering the entire RGB chromatic range, combined with the optical properties of the different tissues, allows for a substantial enhancement in image details. Traditional image acquisition methods do not exploit these visual enhancements which results in poorer visual distinction among tissue structures. Photodynamic therapy (PDT) procedures are of increasing interest in the treatment of several forms of cancer. This study uses histological slides of rat liver samples that were induced to necrosis after being exposed to PDT. Results show that visualization of tissue structures could be improved by changing colors and intensities of the microscope light source. PDT-necrosed tissue samples are better differentiated when illuminated with different color wavelengths, leading to an improved differentiation of cells in the necrosis area. Due to the potential benefits it can bring to interpretation and diagnosis, further research in this field could make CCV an attractive technique for medical applications. Microsc. Res. Tech., 2008. © 2008 Wiley-Liss, Inc. [source] Metastability in multicomponent oxide transistorsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 3 2010Warren B. Jackson Abstract Results of an investigation of bias stress metastability of multicomponent, zinc,indium and zinc,tin oxides, transistors are investigated. The bias stress as a function of various dielectrics, passivation layers, and illumination conditions indicate that for negative gate bias stressing defects often are created in the semiconductor, probably near or at the surface, particularly if the devices are unpassivated. Oxygen vacancy formation is a likely candidate. For many dielectrics, the positive gate bias metastability appears to be dominated by charge trapping within the insulator. For zinc,tin oxide devices, the kinetics of the metastability follows a stretched exponential behavior with a power law dependence on gate voltage. Correcting for the observed Meyer,Neldel behavior, the activation energy of , is about 1.2,eV for defect generation and the disorder energy from , is about 0.06,eV. By using passivation, the best gate dielectrics and annealing protocols, we have reduced the bias stress metastability to about 0.1,V for a 25,000,s stress at 22,°C. [source] Macroscopic movement of azo polymer chains by near-field probes: Dependence on the illumination conditionsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 8 2010Matteo Savoini Abstract The movement of photosensitive azo polymers induced by scanning near-field illumination is studied. As a function of the photon flux illuminating the sample and exposure time, different effects are obtained: from a nanoscopic reorientation, inducing birefringence in the sample, to a macroscopic movement of the photosensitive polymers. It is also shown that this movement is strongly influenced by the state of incident light polarization. The combination of azo polymers and near-field illumination allows encoding sub diffraction information and can be exploited in applications as nanomachining and nanofabrication. Birefringence signal associated to nanoscopic reorientation of the azomers. [source] ZnO nanostructures for photovoltaic cellsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 7 2010Belete A. Gonfa Abstract In this work the use of different ZnO nanostructures has been studied to assess the effect of morphology and surface modification on the performance of photovoltaic devices. ZnO nanostructures (nanoparticles, nanowires and nanofibres) have been produced by different techniques, and surface modified with pyrene-1-carboxylic acid (PCA). The materials prepared were characterized by XRD, UV,Visible spectroscopy, TEM and SEM. The photovoltaic devices have been prepared in two different configurations: glass/ITO/PEDOT:PSS/photoactive layer/Al and glass/ITO/ZnO/photoactive layer/PEDOT:PSS/Ag paste using spin coating and were characterized by current,voltage characteristics measurement under simulated standard illumination conditions. Whilst ZnO nanoparticles yielded the best results, surface modification with PCA resulted in solar cells with higher short circuit current densities but lower open circuit voltage pointing to a better carrier collection but also higher recombination. [source] Preparation and properties of In/p-Cu(In1,xGax)(S1,ySey)2 surface-barrier structuresPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 5 2009Ellen Zaretskaya Abstract Cu(In1,xGax)(S1,ySey)2 (CIGSS) thin films were prepared by the simultaneous selenizarion/sulfurization of Cu-In-Ga metallic alloys. Full characterizations have been carried out using XRD, SEM, EDX, AES and Raman scattering measurements. Photosensitive In/p -CIGSS surface-barrier rectifying structures were created by thermal deposition of pure Incontacts onto the surface of the CIGSS as grown films. The influences of the thin films chemical composition and the illumination conditions on the photo-electric parameters of In/p -CIGSS structures were studied. Analysis of the results showed the availability of the prepared CIGSS films for creation of high efficiency thin films photovoltaic devices. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Visual function of police officers who have undergone refractive surgeryAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 11 2006Jeffery K. Hovis OD Abstract Introduction The visual acuity and contrast sensitivity of police recruits and officers was evaluated in both normal and dim illumination conditions to determine whether officers who have had refractive surgery have compromised night vision. Methods The control group consisted of 76 officers and recruits who have not had refractive surgery and the refractive surgery group consisted of 22 officers and recruits who had refractive surgery. Visual acuity and contrast sensitivity were measured under both room illumination and dim illumination. The room illumination test series included high contrast acuity, low contrast acuity and Pelli-Robson contrast sensitivity. The dim illumination test series included high contrast acuity, low contrast acuity, Pelli-Robson contrast sensitivity, license plate number acuity (with and without glare) and the Mesotest. Results The general findings were that the refractive surgery group had lower acuity scores on low contrast targets in both room and dim light levels along with a reduction in the Mesotest scores with a glare source compared to the control group. Conclusions Although refractive surgery police recruits and officers had reduced performance on some vision tests, these reductions were small and it is unlikely that their performance on vision related tasks would be compromised, on average. The major concern is the small number of refractive surgery candidates whose results were well outside the range of the non-surgical candidates. Their vision may be unacceptable for policing. Am. J. Ind. Med. 49:885,894, 2006. © 2006 Wiley-Liss, Inc. [source] Spatially resolved evaluation of power losses in industrial solar cells by illuminated lock-in thermographyPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 5 2004Joerg Isenberg Abstract The principles of a recently introduced measurement technique for power losses in solar cells, illuminated lock-in thermography (ILT), are reviewed. The main advantage of ILT over dark lock-in Thermography (DLT) is measurement under realistic operational conditions of solar cells. The main focus of this paper is to demonstrate the wide range of applications of ILT in identifying the causes of power losses in solar cells. For this purpose different evaluation methods are presented. A method for the evaluation of improvement potentials within a given cell technology is demonstrated. It is shown that different types of series resistance may be localized. Small areas of recombination losses (e.g., grain boundaries) can routinely be detected, which is not possible in dark lock-in thermography. Good correspondence with light-beam-induced current images is found. A realistic evaluation of the impact of recombination losses on solar cell performance is demonstrated on two examples. Finally, process- or treatment-induced recombination losses are investigated. In summary ILT is shown to be an extremely powerful tool in localizing, identifying and quantifying power losses of solar cells under realistic illumination conditions. Copyright © 2004 John Wiley & Sons, Ltd. [source] Advances in rearing techniques of Pagrus pagrus, (Linnaeus, 1758): comparison between intensive and semi-intensive larval rearing systemsAQUACULTURE RESEARCH, Issue 3 2010Francisco Javier Roo Abstract Red porgy, Pagrus pagrus L., is a potential candidate for marine finfish diversification on commercial Mediterranean and Atlantic coastal aquaculture. This paper described the development of a suitable larval rearing protocol for commercial application. Red porgy eggs were reared under Intensive and Semi-intensive systems until 50 days after hatching. In addition, two different weaning protocols were tested for each rearing system. The effects of these treatments were evaluated on the growth, survival and whole-body biochemical and fatty acid composition of red porgy larvae. Significant differences in growth but not in survival at 50 days after hatching were detected in trial A for the semi-intensive and intensive rearing system (23.5 ± 2.7,18.9 ± 3.4 mm; 4.4,4.9%); however, modifications in initial prey density and illumination conditions, implemented in trials B (29.5 ± 3.0,25.2 ± 1.9 mm; 21.8,5.3%) and C (26.2 ± 2.6,24.6 ± 2.6 mm; 22.7,3.8%), significantly improved survival and growth rates in the semi-intensive rearing system. Furthermore, the results in trial C confirmed the feasibility of a partial reduction in Artemia use and the significant improvement in survival rates with the new weaning protocol applied (26.4 ± 2.3,24.1 ± 3.9 mm; 28.7,12.5%) in the intensive systems. The results of this study concluded that the best larval rearing protocol for commercial production of red porgy fingerlings should include the use of semi-intensive systems. [source] | |||||||||||||