Spotting System Research Articles

Heat transport and electron distribution function in laser produced plasmas with hot spots

Using Fokker–Planck and particle-in-cell simulations, the evolution of a single hot spot and multiple hot spot systems have been studied in laser produced plasmas. A practical formula for nonlocal heat flux has been derived as a generalized expression of a nonlocal linear approach [Bychenkov et al., Phys. Rev. Lett. 75, 4405 (1995)] and is tested in simulations. The electron distribution function is studied at different spatial locations with respect to a localized heating source. The electron distribution function displays several non-Maxwellian features which depend on the interplay between the effects of inverse bremsstrahlung heating and nonlocal transport. In particular, significant high-energy tails are found. They may have impact on the behavior of parametric instabilities in nonuniformly heated laser plasma.

Simulations of electron transport in laser hot spots

Simulations of electron transport are carried out by solving the Fokker–Planck equation in the diffusive approximation. The system of a single laser hot spot, with open boundary conditions, is systematically studied by performing a scan over a wide range of the two relevant parameters. (1) Ratio of the stopping length over the width of the hot spot. (2) Relative importance of the heating through inverse Bremsstrahlung compared to the thermalization through self-collisions. As for uniform illumination [J. P. Matte et al., Plasma Phys. Controlled Fusion 30, 1665 (1988)], the bulk of the velocity distribution functions (VDFs) present a super-Gaussian dependence. However, as a result of spatial transport, the tails are observed to be well represented by a Maxwellian. A similar dependence of the distributions is also found for multiple hot spot systems. For its relevance with respect to stimulated Raman scattering, the linear Landau damping of the electron plasma wave is estimated for such VDFs. Finally, the nonlinear Fokker–Planck simulations of the single laser hot spot system are also compared to the results obtained with the linear nonlocal hydrodynamic approach [A. V. Brantov et al., Phys. Plasmas 5, 2742 (1998)], thus providing a quantitative limit to the latter method: The hydrodynamic approach presents more than 10% inaccuracy in the presence of temperature variations of the order ΔT/T≳1%, and similar levels of deformation of the Gaussian shape of the Maxwellian background.

Manipulation of Solitary Structures in a Nonlinear Optical Single Feedback Experiment

Interest in spatial solitary structures originates from their characteristics to enable a locally self-confined switching between a dark background state and a bright spot. We report on the control and addressing of solitary structures in a single feedback experiment with a liquid crystal based reflective optically addressable spatial light modulator (OaSLM) as nonlinearity. In general the lateral positions of solitary structures are strongly influenced by mutual spot interaction and system inhomogeneities. Pinning, drifting and spontaneous disappearance of solitary spots determines the system behavior. For photonic applications these effects must be minimized. A control method based on a Fourier filtering method was studied in order to position solitary spots. Numerical and experimental results show that solitary spots can be aligned to periodic grids of hexagonal or square geometries.

Manipulation of Solitary Structures in a Nonlinear Optical Single Feedback Experiment

Interest in spatial solitary structures originates from their characteristics to enable a locally self-confined switching between a dark background state and a bright spot. We report on the control and addressing of solitary structures in a single feedback experiment with a liquid crystal based reflective optically addressable spatial light modulator (OaSLM) as nonlinearity. In general the lateral positions of solitary structures are strongly influenced by mutual spot interaction and system inhomogeneities. Pinning, drifting and spontaneous disappearance of solitary spots determines the system behavior. For photonic applications these effects must be minimized. A control method based on a Fourier filtering method was studied in order to position solitary spots. Numerical and experimental results show that solitary spots can be aligned to periodic grids of hexagonal or square geometries.

COMPARISON OF SATELLITE AND AERIAL IMAGERY FOR DETECTING LEAF CHLOROPHYLL CONTENT IN CORN

Inseason sitespecific nitrogen application has the potential to improve the efficiency of nitrogen use and reduceenvironmental contamination. Identification of withinfield crop nitrogen stress is essential for improved nitrogenmanagement. Corn nitrogen stress is frequently associated with leaf chlorophyll content, which can be characterized byspectral reflectance measurements. Therefore, satellite remote sensing has potential for characterizing corn nitrogendeficiency on a wholefield scale. To evaluate the use of satellite imagery to detect nitrogen deficiency in corn during thegrowing season, this study compared spectral variables extracted from SPOT satellite imagery and digital aerial imagery,and investigated the relationship between spectral variables of the SPOT imagery and the measurement data of a handheldchlorophyll meter (or SPAD meter). SPOT images and aerial images were acquired on one commercial field in 1999 andanother one in 2000.<br><br>The correlation coefficient (r) between the NDVIs derived from the SPOT image and the aerial image was 0.73 in 1999,and 0.54 in 2000, respectively. When the field had large spatial variability in crop development in 1999, the spectral variablesfrom the SPOT image were strongly correlated with those from the aerial image. However, when the crop development wasmore uniform in 2000, the correlation between the SPOT image and the aerial image was not as good. The limited range ofavailable digital counts that can be used to represent the reflectance from an individual farm field for the SPOT system limitedits sensitivity in detecting crop stress. Nevertheless, the NDVIs from SPOT images were significantly correlated with SPADdata in both fields, with correlation coefficients of 0.90 in 1999 and 0.68 in 2000. The correlation between SPOT images andSPAD data was similar to that between aerial images and SPAD data, indicating that SPOT imagery may have potential fordetecting chlorophyll levels and nitrogen stress in corn during the growing season.

Anti-neutrophil cytoplasmic antibodies (ANCA) from patients with systemic vasculitis recognize restricted epitopes of proteinase 3 involving the catalytic site.

ANCA with specificity for proteinase 3 (PR3), a neutrophil primary granule enzyme, are of diagnostic value in Wegener's granulomatosis (WG) and certain other forms of systemic vasculitis. There is evidence to suggest that they play a pathogenic role in disease, and that the interaction of ANCA with PR3 is likely to be important. We showed, using a resonant mirror biosensor, that C-ANCA from different patients recognized the same or closely related epitopes on PR3. Studies using linear peptides in the SPOT system confirmed the highly restricted nature of this interaction and identified five linear epitopes. Fluid-phase inhibition studies, using a different set of peptides, validated the sequences involved. Using a computer-generated model of the structure of PR3, four of five epitopes were shown to be intimately linked with the catalytic site. The restricted number of epitopes, and their location at the catalytic site, has important implications for the role of C-ANCA in the pathogenesis of vasculitis.

Tracing a mantle plume: Isotopic and trace element variations of Galápagos seamounts

Isotopic and trace element analyses of basalts dredged from across the Galápagos Platform confirm the previously established east facing horseshoe pattern of depleted geochemical signatures at the center of the archipelago and more enriched signatures along the periphery. Statistical analysis of the isotopic data indicates that geochemical variations in the Galápagos cannot be explained by mixing between only the plume and the depleted asthenosphere. Instead, four isotopically distinct end‐members must be interacting to account for the subtleties of the Sr, Nd, Pb, and He isotopic data. Three of the components are geographically restricted: one in the south, one in the central region, and one in the north. These three plume components then mix with the fourth component, depleted mantle, which is indistinguishable from the MORB source. The central component resembles the high 3He/4He mantle reservoir that may be common to many plumes and has variously been called PHEM, FOZO, and C by others. Whereas this mantle reservoir appears to make a minor contribution to the composition of most hot spot systems, it may constitute the main body of the Galápagos plume. Geographic distribution of the end‐members suggests that the plume is centered near Fernandina ∼92°N but may be significantly diluted by depleted mantle even near the main conduit. The geochemically distinct end‐members trace an eastward mantle flow, manifested as decreasing contributions of the plume in the direction of plate motion. The plume may be tilted by shear in the asthenosphere from plate motion and ambient mantle flow. As it is bent, the plume thermally entrains surrounding upper mantle, resulting in the horseshoe‐shaped distribution of depleted and enriched material. The end‐members may also outline a deep, strong lateral flow of mantle toward the Galápagos Spreading Center, supplying plume material to the ridge system. Overall, our results suggest that the Galápagos hot spot is both compositionally and dynamically complex owing to its tectonic setting adjacent to a mid‐ocean ridge.

Characterization and identification of allergen epitopes: recombinant peptide libraries and synthetic, overlapping peptides

For the understanding of the relationship between protein structure and allergenicity, it is important to identify allergenic epitopes. Two methods to characterize primarily linear epitopes are compared using the major allergen from brown shrimp ( Penaeus aztecus), Pen a 1, as an example. A recombinant peptide library was constructed and synthetic, overlapping peptides, spanning the entire Pen a 1 molecule, were synthesized and tested for specific IgE reactivity. Both methods identified IgE-binding of Pen a 1, however, the SPOTs procedure resulted in the identification of more epitopes of the major shrimp allergen Pen a 1 than the usage of the recombinant peptide library. For detection of specific IgE antibodies, the usage of 125I-labeled detection antibody seems to be superior over enzyme-labeled anti IgE antibodies. The regeneration of SPOTs membranes is possible, but it is prudent to test regenerated membranes for residual activity. If a given food allergen contains significant linear epitopes, which seems to be true for stable major allergens such as those of peanut and shrimp the SPOTs system may be more advantageous than the use of recombinant peptides libraries. However, if allergens are studied that contain more conformational epitopes, recombinant peptide libraries may help to identify the relevant epitopes. It has to be emphasized that no system for epitope identification will detect all epitopes and that the relevance of identified epitopes has to be confirmed with other methods such as inhibition studies, crystallographic analysis or the immunological evaluation of modified whole allergens.

回折格子を用いた球面波アンギュラシェアリング法によるＤＶＤピックアップレンズ検査

For high-speed and high-accuracy of aberration inspection process for pickup lens of optical head for digital versatile disc (DVD), an optical system based on shearing interference of spherical wavefront from pickup lens using grating has been applied. A simple algorithm, that processes points allocated on certain lines in fringe and fits relations between distance from basis point to the measurement points and phase difference at these points to equations of higher degree as curve fitting, has been devised. Coma, astigmatism and SA3 have been numerically estimated as the size of certain coefficient Inspection system based on this optical system and algorithm has been developed. Difference of measured value between the developed system and the conventional interferometer that has been treated as the standard is 3.9mλ and below at σ, this value is equal to difference between two conventional interferometers. Therefore accuracy of the developed system is equal to conventional interferometer. In comparison with the conventional spot system, this system has obtained higher accuracy, as well as 1/3 inspection time and 1/2 and under tact time.

Applying Machine Learning for High‐Performance Named‐Entity Extraction

This paper describes a machine learning approach to building an efficient and accurate name spotting system. Finding names in free text is an important task in many text‐based applications. Most previous approaches were based on hand‐crafted modules encoding language and genre‐specific knowledge. These approaches had at least two shortcomings: They required large amounts of time and expertise to develop and were not easily portable to new languages and genres. This paper describes an extensible system that automatically combines weak evidence from different, easily available sources: parts‐of‐speech tags, dictionaries, and surface‐level syntactic information such as capitalization and punctuation. Individually, each piece of evidence is insufficient for robust name detection. However, the combination of evidence, through standard machine learning techniques, yields a system that achieves performance equivalent to the best existing hand‐crafted approaches.

Different confidence measures for word verification in speech recognition

Recent research in Automatic Speech Recognition (ASR) technologies has shown the key-word spotting (KWS) systems as one of the most interesting options for accessing information using speech. KWS systems can accept spontaneous speech, which allows potential users to ask for information without learning complex protocols for the human–machine communication. One of the most relevant aspects in KWS systems is the verification of key-word candidates. Utterances detected as key-words could be either `false alarms' (non-key-words or incorrectly recognized key-words) or `correct key-words'. The use of confidence measurements allows (by additional processing of the spoken sentence) the verification of the candidates and the decision as to whether each utterance must be accepted as a correctly recognized key-word or rejected as a false alarm. In this work we propose a novel method for verification in those KWS systems based on phone models. Under our new approach, a phonematic speech recognizer decodes the spoken sentence in parallel with the KWS recognizer. The first one produces a phone string as output while the second one generates a key-word/filler-model string. By aligning both strings, a set of characteristics is extracted which are used to verify the putatives key-word. For that we have built two classifiers; in the first one the euclidean metric is modified and adapted in a local and iterative way in order to give greater importance to the most discriminate directions between the classes. The second is a vector quantizer which was trained using adaptative technique learning. We have applied the proposed method to several KWS tasks. Experimental results presented in this paper show that the proposed verification method improves the performance of the KWS systems by reducing the false alarm rate without a significant increase in the rejection of correctly detected key-words.

The Cornea is Not a Piece of Plastic

he future of laser refractive surgery is exciting with the potential for ever-improved postoperative visual performance. In the past, the operative goal has been 20/20 uncorrected visual acuity with zero residual refractive error. Criteria for a successful procedure are no longer 20/40 or better with ±1.00 diopter (D) of residual refractive error, because neither surgeons nor patients are satisfied with such gross measurements of visual performance. Hence, considerable research effort is being devoted to develop customized procedures for each patient. The new goal is 20/10 uncorrected visual acuity with aberration-free postoperative vision. How can these lofty goals be accomplished? First, lasers have been improved with the development of scanning, small spot systems, as opposed to broad-beam systems. Scanning systems have brought customized procedures into the realm of feasibility. Second, more comprehensive and sophisticated input data can be used to guide the laser based on individual patient measurements, as opposed to the simple refractive sphere and cylinder. Two types of approaches are currently being pursued—wavefront-guided and topography-guided procedures. Early results are promising, yet neither approach has demonstrated consistently superior results to non-guided procedures in controlled, scientific studies. Is a piece of the perfect vision puzzle still missing? Is there an additional, complimentary approach to customization that has yet to emerge? Are we leaping into the future ahead of our understanding of how these procedures may be implemented to be optimally successful? Munnerlyn and colleagues 1 gave us an elegant analysis of how corneal surface shape may be altered to correct both myopia and hyperopia. His geometric approach can be thought of as a “shapesubtraction” model, where tissue of an appropriate profile is simply “subtracted” using an excimer laser to produce the desired surface curvature. Essentially, the cornea is treated like a piece of plastic to be sculpted into the ideal surface shape. The Munnerlyn approach, combined with empirical experience, has been relatively successful in correcting spherical and cylindrical errors for the majority of patients treated to date. However, only 50% to 85% achieve 20/20, despite greater than 90% of patients being “satisfied.” In addition, significant postoperative optical aberrations are produced using conventional algorithms 2-4 , encouraging the development of aberration-reducing ablation profiles.

Dynamics of Volcanic Systems in Iceland: Example of Tectonism and Volcanism at Juxtaposed Hot Spot and Mid-Ocean Ridge Systems

Volcanic systems are swarms of tectonic fractures and basalt volcanoes formed as a result of plate-pull (as the plates are pulled apart) associated with the mid-ocean ridges and the magma dynamics of the Iceland Mantle Plume. Most systems are 40–150 km long, 5–20 km wide, and develop a central volcano. They supply magma to all eruptions in Iceland. Data obtained in the last few years have greatly improved our knowledge of their volcanotectonic environment; as a result, the geometry of the plume is better constrained, and the crust, previously considered thin (∼10 km), is now modeled as thick (∼20–40 km). Depending on the location of the volcanic systems, their activity either decreases or increases faulting in the two main seismic zones. From this, we can infer that emplacement of the feeder-dike to the largest historical eruption in Iceland (that of Laki in 1783) increased shear stress in the South Iceland Seismic Zone and almost certainly triggered the largest (M∼7.1 in 1784) historical earthquake in Iceland. [ Addendum posted 20 April, 2010 ]

Ignition of a system of hot spots in the presence of heat transfer through the side surface

An asymptotic analysis is used to study the ignition of a reactive cylindrical body in which, initially, there is a periodic system of hot spots. The effects of the heat transfer through the side surface of the cylinder and the adjacency of hot spots on the ignition regimes are studied. The solution shows that the critical ignition conditions depend considerably on the heat-transfer regime. The adjacency of the hot spots leads to finite changes in the parameters only if they are sufficiently close to each other. The results obtained for a heat-insulated side surface are compared with known solutions.

System and device for advanced voice recognition word spotting

A speaker independent, continuous speech, word spotting voice recognition system and method. The edges of phonemes in an utterance are quickly and accurately isolated. The utterance is broken into wave segments based upon the edges of the phonemes. A voice recognition engine is consulted multiple times for several wave segments and the results are analyzed to correctly identify the words in the utterance.

Petrological and structural significance of the Santa Elena-Nicoya ophiolitic complex in Costa Rica and geodynamic implications

Detailed structural and petrological investigations were carried out on the Santa Elena-Nicoya ophiolitic complex in Costa Rica, which is represented by a classic association of mantle tectonites (Santa Elena Peninsula), a cumulitic gabbroic-plagiogranite sequence, and basaltic volcanics and sills (Matapalo and Esperanza Units of the Nicoya Peninsula), with discontinuous radiolarian covers. Despite biostratigraphically different ages (Late Jurassic for Matapalo and Mid-Late Cretaceous for Esperanza) in both units, the major and trace element data, Sr-Nd isotope systematics, and mineral phase crystallization order show identical tholeiitic fractionation trends, where the marked Fe-Ti enrichment of the volcanics is reflected in the gabbroic-Fe gabbroic-plagiogranite intrusives which, in turn, represent the cumulitic counterparts of an essentially analogous magmatic system. Parental basaltic magmas for the Nicoya complex share geochemical features with both Pacific MORB and oceanic plateaus, as indicated by the characteristic flat REE patterns, Zr/Y and Zr/Nb ratios, and Sr-Nd isotopic data ( 87 Sr/ 86 Sr: 0.70295-0.70323; 144 Nd/ 143 Nd: 0.51309-0.51275). On the other hand, basalts and gabbros from Santa Elena display typical N-MORB affinity, as shown by their LREE-depleted patterns. These data, together with the unusual abundance of Fe-Ti differentiated rocks, suggest that the Santa Elena-Nicoya ophiolites may have been generated at oceanic spreading centres in a mantle plume region, analogous to the present Galapagos ridge/hot spot system. The present fore-arc structural setting of the deformed Costa Rica ophiolites is the result of several tectogenetic events recorded by three main ductile deformation phases (from Late Cretaceous to Tertiary): the oldest d1 related to W-E convergent tectonics, followed by d2 related to N-S compression, and the youngest d3 related to NE-SW convergence. The oceanic lithosphere represented by the Costa Rica ophiolites may have been generated at the westernmost termination of the spreading system, leading to the formation of the Caribbean plateau, and later involved in complicated intra-oceanic convergence and rotation processes. These resulted in the progressive building and insertion of the Chorotega block (present Costa Rica) between the Maya-Chortis and Choco-South America continental blocks.

The skin pattern of young plaice and its rapid modification in response to graded changes in background tint and pattern

Young plaice, kept on a standard background and trained for 3–4 weeks, were photographed to record short‐term nervously controlled responses to plain grey and patterned backgrounds, graded and quantitatively defined with regard to reflectivity and dimensions. Systems of primary, secondary and lower‐order black and white spots and flecks became prominent or hidden in hierarchical order. Spots at any one level in a hierarchy were approximately evenly distributed. Black spots enlarged with increased size or number of black circles in the background but responded differently to unpatterned grey backgrounds. White spots had a centre and surrounding annulus both of which could be pale or independently variably occluded centrally, peripherally or overall. Peripheral occlusion of the annuli contributed to skin darkening and by extending inwards to include the centre it progressively diminished the white spots. The system of white spots was responsible for the smaller skin patterns, the finest being produced through disruption by the white flecks of the annuli, black spots and dark patches. There was great variation in response of individuals. Erratic and poor background responses were generally associated with abnormalities in the white spots.

A New Approach to Calculation of Contact Characteristics

A new method of calculation of contact characteristics for rough surfaces is proposed based on integral relations that express the normal contact stress as an explicit function of the surface shape. To produce calculations by this method, a region having a simple shape should be chosen first, where the contact is supposed to be nominally complete. An iterative procedure with regard to the shape is applied within the load-free surface portion, and allows the normal stresses, surface displacement and the real area of contact to be determined. The method is applicable to rough bodies of arbitrary shape for which the half-space formulation and equivalent roughness concepts apply; the real contact area should lie within the initially chosen contact region and can include a system of unconnected contact spots. Both 2D and 3D cases are considered in the present work. The 2D analysis is based on known integral relations for nonperiodic and periodic contact problems. In the 3D case, new analytical relations are obtained and their properties are analyzed. An iteration algorithm based on these relations and its efficient numerical implementation are described. Application of the method to the contact of real rough surfaces is discussed.

Relationship between loading properties and resistance weldability, and an optimum loading system for weldability: Optimisation of the loading system in high current density spot welding with a short energising time (2nd Report)

Summary The load is an important factor in spot welding. In high current density spot welding with a short energising time, the electromagnetic force increases proportionally to the square of the peak current in the opposite direction to the load direction, which consequently reduces the actual loading of the work. This paper describes an investigation of the effect of the loading properties on the weldability and the design of an optimum loading system for high current density spot welding with a short energising time. In a loading system with a small spring constant, the nugget forms under low current conditions, but defects readily form at the interface, and the load decreases because the electrodes move in response to the electromagnetic force. In a loading system with a large spring constant, it is difficult to produce welded joints because the electrode movement is restrained, and the load is increased by the thermal expansion. This feature more strongly affects a material with a high thermal conductivity, such as Al alloy. In high current density spot welding with a short energising time, it is important to design the loading system with regard for equivalence between the thermal expansion and the electrode displacement due to the electromagnetic force.

Periodic noise suppression techniques applied to remote sensing images

The image data collected by the JERS-1 OPS, SPOT and AVHRR systems are affected by a variety of periodic (coherent) noise problems, which can be severe in many cases. This paper examines some of these defects and also describes and evaluates a series of methodologies to recover partially or totally the information contained in these data by means of: (i) filtering in the spatial domain (convolution filters), (ii) Principal Components Analysis (PCA) and (iii) filtering in the frequency domain (using Fast Fourier Transforms). Filtering in the spatial domain using relatively small convolution filters can be successfully applied to tackle elementary periodic noise problems. However, variations of theoretically efficient kernels experimented in this study were only able to minimise the effect of such complex noise structures at the expense of significant modification or complete loss of important raw image data. Principal Component Analysis transforms the data so that the noise component is cast into one or more of the high-order principal components. Our experiments show that this technique is able to confine the noise in the higher order PCs, but a significant amount of residual noise was present in the low-order components. Filtering in the frequency domain proved to be a suitable technique to achieve image restoration whilst preserving most of the raw scene information intact. Conventional Fourier operators like the Notch Filter and the Low-pass Elliptically Symmetric Filter (with a Gaussian-shaped intensity profile) can tackle the problems with some noisy images quite reasonably. However, such filters are unable to recover images on which the amplitude of the noise varies heterogeneously producing a series of impulses from low to high frequencies. Both the Zonal Notch Filter (based on the difference of the Fourier spectra of two channels) and the Synergistic Filter (which relies on the convolution theorem) are designed to contour this problem. These are interactive restoration methods that can successfully eliminate or minimise the effects of multiple two-dimensional periodic structures superimposed on both multi-channel and single channel data, respectively.