False-color Maps Research Articles

TISSUE CLASSIFICATION FOR COLORECTAL CANCER UTILIZING TECHNIQUES OF DEEP LEARNING AND MACHINE LEARNING

Since the introduction of image pattern recognition and computer vision processing, the classification of cancer tissues has been a challenge at pixel-level, slide-level, and patient-level. Conventional machine learning techniques have given way to Deep Learning (DL), a contemporary, state-of-the-art approach to texture classification and localization of cancer tissues. Colorectal Cancer (CRC) is the third ranked cause of death from cancer worldwide. This paper proposes image-level texture classification of a CRC dataset by deep convolutional neural networks (CNN). Simple DL techniques consisting of transfer learning and fine-tuning were exploited. VGG-16, a Keras pre-trained model with initial weights by ImageNet, was applied. The transfer learning architecture and methods responding to VGG-16 are proposed. The training, validation, and testing sets included 5000 images of 150 × 150 pixels. The application set for detection and localization contained 10 large original images of 5000 × 5000 pixels. The model achieved F1-score and accuracy of 0.96 and 0.99, respectively, and produced a false positive rate of 0.01. AUC-based evaluation was also measured. The model classified ten large previously unseen images from the application set represented in false color maps. The reported results show the satisfactory performance of the model. The simplicity of the architecture, configuration, and implementation also contributes to the outcome this work.

Assessing the reliability of an automated system for mineral identification using LWIR Hyperspectral Infrared imagery

Application of hyperspectral infrared imagery for mineral grain identification suffers from a lack of prediction on the irregular grain’s surface along with the mineral aggregates. Here, we present an investigation to determine the reliability of automatic mineral identification in the longwave Infrared (LWIR, 7.7–11.8 μm) with an LWIR-macro lens having a spatial resolution of 100 μm. We attempt to identify eleven different mineral grains (biotite, epidote, goethite, diopside, smithsonite, tourmaline, kyanite, scheelite, pyrope, olivine, and quartz). A machine learning-based algorithm (implemented by software) compares all of the pixel-spectra to the ASTER spectral library of JPL/NASA using spectral angle mapper (SAM) and normalized cross-correlation (NCC) to create false-color maps. Then a hue-saturation-value (HSV) principle component analysis (PCA) based K-means clustering approach groups the mineral regions in different categories. The results were compared to two different ground truths (GT) (i.e. rigid-GT and observed-GT) for quantitative calculation and as an integrated step for validating our approach. Observed-GT increased the accuracy up to 1.5 times higher than rigid-GT, from 45.67% to 69.39%. The samples were also examined by micro X-ray fluorescence (μXRF) and scanning electron microscope (SEM) in order to retrieve information on the mineral aggregates and the grain’s surface. The results of μXRF imagery (aggregate map) were compared to the results of automatic mineral identification techniques, using ArcGIS software, and the results represent a promising performance for automatic identification.

TRACKING AUTHIGENIC MINERAL CEMENTS IN FOSSIL BONES FROM THE UPPER CRETACEOUS (CAMPANIAN) TWO MEDICINE AND JUDITH RIVER FORMATIONS, MONTANA

ABSTRACT Previous studies have yielded mixed results as to whether authigenic mineral infill in fossilized bone tracks specific lithologies or depositional environments, with most suggesting weak to no correlation between infill composition and host lithofacies. This study documents infill patterns in a suite of fossil bones from the Upper Cretaceous Two Medicine and Judith River formations of Montana. The composition and distribution of void-filling materials, including authigenic mineral precipitates (e.g., calcite, chlorite, iron oxides/hydroxides, sulfides, and sulfates) and sedimentary detritus, were identified (petrography and SEM-EDS), imaged (photomicrographs, BSE maps), and quantified on false color maps using ImageJ. The authigenic cement content of fossil bone is distinct at the formation scale, with Two Medicine specimens characterized by pervasive calcite infill (non-ferroan followed by ferroan phase) and local chlorite infill. In contrast, Judith River specimens are characterized by abundant unfilled primary void space, with iron oxides and sulfides, along with rare sulfates, present in all bones, albeit in low abundance. Calcite infills are rare, chlorite is absent, and detrital infill is more abundant in Judith River specimens, presumably reflecting the rapid and more complete permineralization of Two Medicine bones. The sequencing of mineral cements in voids is generally consistent within formations, but is more complex in Two Medicine specimens. Authigenic cement content does not serve to effectively distinguish among facies or localities in either formation. This study compliments previous work on rare earth element (REE) content in the same general suite of fossil bones. In the previous study, patterns in REE uptake also served to readily distinguish fossils at the formation scale, and proved more effective than authigenic cements at differentiating fossils recovered from different facies.

Thin Filament Pyrometry Field Measurements in a Medium-Scale Pool Fire

This paper presents the development of a thin filament pyrometry method to characterize the time-varying temperature field in a medium-scale pool fire burning in a quiescent environment. A digital camera with optical filters and zoom lens was used to record the high temperature emission intensity of 14 μm diameter, Silicon-Carbide filaments oriented horizontally at various heights above the center of a steadily burning 0.30 m diameter methyl alcohol (methanol; CH3OH) pool fire. Experiments collected 30 Hz video of the planar filament array. In a separate experiment, a 50 μm diameter thermocouple was used to acquire independent temperature measurements in the high temperature zone of the fire. A correlation was developed between the probability density functions of the radiation-corrected thermocouple measurements and the camera grayscale pixel intensity of the filaments. This arrangement enables measurement of the time-varying temperature field over a temperature range from about 1150 K to 1900 K with a spatial resolution of 160 μm, a temporal resolution of 0.033 s, and an expanded uncertainty of about 150 K (at a mean temperature of 1300 K). Measurements of the grayscale pixel intensities of the filaments were obtained. False color maps of the temperature field were produced to characterize the high temperature field as a function of time. Using statistical analysis, the local time-averaged temperatures and their variance for each location on the filaments were determined. Time-averaged temperatures were compared favorably to previously reported measurements. The dominant frequency of the puffing fire was determined. The temperature field time series was transformed to consider its character during consecutive phases of the fire's puffing cycle. The analysis emphasizes the cyclic nature of a pool fire, providing insight on its complex dynamic structure.

Mapping of hydrothermally altered zones in Aravalli Supergroup of rocks around Dungarpur and Udaipur, India, using Landsat-8 OLI and spectroscopy

We explored the utilization of Landsat-8 Operational Land Imager (OLI) data for mapping of hydrothermal alteration zones. The region in and around the cities of Dungarpur and Udaipur of Rajasthan state in India was selected for this study. The rock types of Dungarpur and Udaipur are serpentinites, talc-carbonate, talc-schist, and quartzite of the Aravalli Supergroup. Hydrothermally altered zones and resultant hydrous minerals play an important role in the genesis of these rocks. We aimed to identify possible locations of hydrothermally altered zones in regional context around Dungarpur and Udaipur using Landsat-8 OLI data. False-color composite maps and band ratios were prepared from Landsat-8 bands. Band ratios such as band 6/band 7 (short-wave infrared 1 (SWIR1)/short wave infrared 2 (SWIR2)), band 4/band 3 (red/green), and band 5/band 6 (near infrared (NIR)/SWIR1) and visual interpretation techniques were used to identify the hydrothermally altered zones. Spectroscopic analyses of field rock samples were done to validate the hydrothermal alteration zones delineated from the analysis of Landsat-8 data. We present the combined results of Landsat-8 and field spectroradiometer analysis which brings out the hydrothermal alteration zones associated with hydrous minerals (antigorite, lizardite, montmorillonite, vermiculite, talc, and saponite). The study demonstrates the utility Landsat-8 OLI (with field spectroradiometer data) in the mapping of hydrothermally altered zones as a key in understanding geological processes.

A walk in the maze: variation in Late Jurassic tridactyl dinosaur tracks from the Swiss Jura Mountains (NW Switzerland).

BackgroundMinute to medium-sized (footprint length (FL) less than 30 cm) tridactyl dinosaur tracks are the most abundant in the Late Jurassic tracksites of Highway A16 (Reuchenette Formation, Kimmeridgian) in the Jura Mountains (NW Switzerland). During excavations, two morphotypes, one gracile and one robust, were identified in the field. Furthermore, two large-sized theropod ichnospecies (Megalosauripus transjuranicus and Jurabrontes curtedulensis) and an ornithopod-like morphotype (Morphotype II) have recently been described at these sites.MethodsThe quality of morphological preservation (preservation grade), the depth of the footprint, the shape variation, and the footprint proportions (FL/footprint width (FW) ratio and mesaxony) along the trackways have been analyzed using 3D models and false-color depth maps in order to determine the exact number of small to medium-sized morphotypes present in the tracksites.ResultsThe study of footprints (n = 93) recovered during the excavations has made it possible to identify and characterize the two morphotypes distinguished in the field. The gracile morphotype is mainly characterized by a high FL/FW ratio, high mesaxony, low divarication angles and clear, sharp claw marks, and phalangeal pads (2-3-4). By contrast, the robust morphotype is characterized by a lower FL/FW ratio, weaker mesaxony, slightly higher divarication angles and clear, sharp claw marks (when preserved), whereas the phalangeal pads are not clearly preserved although they might be present.DiscussionThe analysis does not allow the two morphotypes to be associated within the same morphological continuum. Thus, they cannot be extramorphological variations of similar tracks produced by a single trackmaker. Comparison of the two morphotypes with the larger morphotypes described in the formation (M. transjuranicus, J. curtedulensis, and Morphotype II) and the spatio-temporal relationships of the trackways suggest that the smaller morphotypes cannot reliably be considered as small individuals of any of the larger morphotypes. The morphometric data of some specimens of the robust morphotype (even lower values for the length/width ratio and mesaxony) suggest that more than one ichnotaxon might be represented within the robust morphotype. The features of the gracile morphotype (cf. Kalohipus isp.) are typical of “grallatorid” ichnotaxa with low mesaxony whereas those of the robust morphotype (cf. Therangospodus isp. and Therangospodus? isp.) are reminiscent of Therangospodus pandemicus. This work sheds new light on combining an analysis of variations in footprint morphology through 3D models and false-color depth maps, with the study of possible ontogenetic variations and the identification of small-sized tridactyl ichnotaxa for the description of new dinosaur tracks.

Understanding the Origin of Jupiter's Diffuse Aurora Using Juno's First Perijove Observations

AbstractJuno observed the low‐altitude polar region during perijove 1 on 27 August 2016 for the first time. Auroral intensity and false‐color maps from the Ultraviolet Spectrograph (UVS) instrument show extensive diffuse aurora observed equatorward of the main auroral oval. Juno passed over the diffuse auroral region near the System III longitude of 120°–150° (90°–120°) in the northern (southern) hemisphere. In the region where these diffuse auroral emissions were observed, the Jupiter Energetic Particle Detector Instrument (JEDI) and Jovian Auroral Distributions Experiment (JADE) instruments measured nearly full loss cone distributions for the downward going electrons over energies of 0.1–700 keV but very few upward going electrons. The false‐color maps from UVS indicate more energetic electron precipitation at lower latitudes than less energetic electron precipitation, consistent with observations of precipitating electrons measured by JEDI and JADE. The comparison between particle and aurora measurements provides first direct evidence that these precipitating energetic electrons are mainly responsible for the diffuse auroral emissions at Jupiter.

A Proposed Methodology for Evaluating HDR False Color Maps

Color mapping, which involves assigning colors to the individual elements of an underlying data distribution, is a commonly used method for data visualization. Although color maps are used in many disciplines and for a variety of tasks, in this study we focus on its usage for visualizing luminance maps. Specifically, we ask ourselves the question of how to best visualize a luminance distribution encoded in a high-dynamic-range (HDR) image using false colors such that the resulting visualization is the most descriptive . To this end, we first propose a definition for descriptiveness. We then propose a methodology to evaluate it subjectively. Then, we propose an objective metric that correlates well with the subjective evaluation results. Using this metric, we evaluate several false coloring strategies using a large number of HDR images. Finally, we conduct a second psychophysical experiment using images representing a diverse set of scenes. Our results indicate that the luminance compression method has a significant effect and the commonly used logarithmic compression is inferior to histogram equalization. Furthermore, we find that the default color scale of the Radiance global illumination software consistently performs well when combined with histogram equalization. On the other hand, the commonly used rainbow color scale was found to be inferior. We believe that the proposed methodology is suitable for evaluating future color mapping strategies as well.

Cortical structure of hallucal metatarsals and locomotor adaptations in hominoids.

Diaphyseal morphology of long bones, in part, reflects in vivo loads experienced during the lifetime of an individual. The first metatarsal, as a cornerstone structure of the foot, presumably expresses diaphyseal morphology that reflects loading history of the foot during stance phase of gait. Human feet differ substantially from those of other apes in terms of loading histories when comparing the path of the center of pressure during stance phase, which reflects different weight transfer mechanisms. Here we use a novel approach for quantifying continuous thickness and cross-sectional geometric properties of long bones in order to test explicit hypotheses about loading histories and diaphyseal structure of adult chimpanzee, gorilla, and human first metatarsals. For each hallucal metatarsal, 17 cross sections were extracted at regularly-spaced intervals (2.5% length) between 25% and 65% length. Cortical thickness in cross sections was measured in one degree radially-arranged increments, while second moments of area were measured about neutral axes also in one degree radially-arranged increments. Standardized thicknesses and second moments of area were visualized using false color maps, while penalized discriminant analyses were used to evaluate quantitative species differences. Humans systematically exhibit the thinnest diaphyseal cortices, yet the greatest diaphyseal rigidities, particularly in dorsoplantar regions. Shifts in orientation of maximum second moments of area along the diaphysis also distinguish human hallucal metatarsals from those of chimpanzees and gorillas. Diaphyseal structure reflects different loading regimes, often in predictable ways, with human versus non-human differences probably resulting both from the use of arboreal substrates by non-human apes and by differing spatial relationships between hallux position and orientation of the substrate reaction resultant during stance. The novel morphological approach employed in this study offers the potential for transformative insights into form-function relationships in additional long bones, including those of extinct organisms (e.g., fossils).

Local State of Charge Mapping and Analysis of Lithium-Manganese Rich NMC High Voltage Electrodes

Current R&D efforts in lithium-ion batteries are directed towards increasing energy density with reduced cost, improved cycle-life and safety performance. Among other important factors, developing high energy density lithium-ion cathodes is a high priority area. Recently, there has been significant progress made on a number of high voltage cathode chemistries such as LiMn1.5Ni0.5O4 1 and lithium-manganese rich NMC (LMR-NMC) 2, 3 cathodes. However, significant technical challenges still need to be addressed at both materials and electrode level for their practical use. Issues include structural and phase stability under continuous high voltage cycling, transition Metal (TM) dissolution, oxygen evolution etc. We have carried out confocal-Raman imaging and spectral analysis of LMR-NMC cathode having nominal composition of Li1.2Mn0.525Ni0.175Co0.1O2, maintained at different state of charge (SOC) and cycled 25 and 200 times between a voltage window of 4.9-2.5V.Figure 1. Raman mapping (top) and spectral analysis (bottom) of pristine LMR NMC electrode. The false color maps show carbon rich regions (red), metal oxide (cyan) and mixed colors for both carbon-LMR-NMC regions.The Raman maps and their spectral behavior change as the electrodes are charged (discharged). Both spectral position and full width at half maximum (FWHM) change with the voltage (SOC) and also under continuous electrochemical cycling. To quantify the inhomegneities of the LMR-NMC electrodes we undertake Raman analysis for cathode particle selected from different regions of electrodes charged at 3.9, 4.2, 4.5 and 4.9V, and compare to pristine electrode. Analysis was carried out at least on 5-6 cathode particles and results are summarized in terms of the ratio of their Eg to A1g band areal intensities and their respective Raman band positions. There are some interesting trends from this analysis: (i) for a given bulk electrode SOC (or voltage) the cathode particles at different electrode locations vary widely in terms of the areal ratios and band positions; (ii) The A1gband shifts consistently to red with increasing SOC or voltage. In addition, we notice a relatively larger inhomogeneity for cathode particles for the 4.2 and 4.9 V electrodes measured in terms of local spectroscopic SOC. Acknowledgement This research at Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U. S. Department of Energy, is sponsored by the Vehicle Technologies Program for the Office of Energy Efficiency and Renewable Energy.

Exploring the extreme universe with the Fermi Gamma-Ray Space Telescope

The Fermi orbiter, mapping the entire gamma-ray sky every three hours, monitors the cosmos for high-energy phenomena both fleeting and enduring.

Vitreoretinal traction in impending branch retinal vein occlusion: A pathogenetic role?

A 25-year-old woman noticed floaters in her left visual field since a few days earlier. She was positive for the heterozygous A1298C mutation on MTHFR gene, betafibrinogen gene –455G/A polymorphism, and 4G/5G plasminogen activator inhibitor-1 (PAI-1). Blood test and a systemic workup did not reveal any abnormality. Blood pressure was 120/80 mmHg. Visual acuity was 20/20 in both eyes. Following a complete ophthalmologic examination an impending upper temporal branch retinal vein occlusion (BRVO) was diagnosed ( Fig. 1). The patient was followed for one month without any particular treatment. Visual acuity remained unchanged and ophthalmic examination demonstrated improvement in the retinal vascular configuration with complete resolution of retinal hemorrhages, venous tortuosity and congestion ( Fig. 2). BRVO is the second most common vascular disorder of the retina, after diabetic retinopathy. It typically occurs at an arteriovenous (AV) crossing, where the retinal arteriole and venule share a common adventitial sheath (1). Although the pathogenesis of BRVO is not clear, there is evidence suggesting a multifactorial process including genetic, environmental and local factors. Mechanical narrowing of venous lumen may alter the normal blood flow downstream of the AV crossing, leading to turbulent flow. The preexisting endothelial vascular damage from different systemic Figure 1: Findings at first presentation of the patient. A) Fundus photograph of the left eye showing a moderate tortuous and engorged upper temporal retinal vein (white arrows), with some small flame-shaped retinal hemorrhages along the territory of the affected vessel (black arrows). B) Fluoresceingraphy disclosed delayed venous filling and a localised partial obstruction in the venous lumen near optic nerve (arrow). C) SD-OCT directed to the site of obstruction revealed a vitreovascular traction (arrow) and tissue elevation (asterisks) by an obliquely directed posterior hyaloids. D) SD-OCT dense protocol of false-color maps provided qualitative information of perivascular edema, showing an intense red colour at the involved blood vessel segment. A B

Compact pnCCD-Based X-ray Camera with High Spatial and Energy Resolution: A Color X-ray Camera

For many applications there is a requirement for nondestructive analytical investigation of the elemental distribution in a sample. With the improvement of X-ray optics and spectroscopic X-ray imagers, full field X-ray fluorescence (FF-XRF) methods are feasible. A new device for high-resolution X-ray imaging, an energy and spatial resolving X-ray camera, is presented. The basic idea behind this so-called "color X-ray camera" (CXC) is to combine an energy dispersive array detector for X-rays, in this case a pnCCD, with polycapillary optics. Imaging is achieved using multiframe recording of the energy and the point of impact of single photons. The camera was tested using a laboratory 30 μm microfocus X-ray tube and synchrotron radiation from BESSY II at the BAMline facility. These experiments demonstrate the suitability of the camera for X-ray fluorescence analytics. The camera simultaneously records 69,696 spectra with an energy resolution of 152 eV for manganese K(α) with a spatial resolution of 50 μm over an imaging area of 12.7 × 12.7 mm(2). It is sensitive to photons in the energy region between 3 and 40 keV, limited by a 50 μm beryllium window, and the sensitive thickness of 450 μm of the chip. Online preview of the sample is possible as the software updates the sums of the counts for certain energy channel ranges during the measurement and displays 2-D false-color maps as well as spectra of selected regions. The complete data cube of 264 × 264 spectra is saved for further qualitative and quantitative processing.

Apparent density of the primate calcaneo‐cuboid joint and its association with locomotor mode, foot posture, and the “midtarsal break”

Primates use a range of locomotor modes during which they incorporate various foot postures. Humans are unique compared with other primates in that humans lack a mobile fore- and midfoot. Rigidity in the human foot is often attributed to increased propulsive and stability requirements during bipedalism. Conversely, fore- and midfoot mobility in nonhuman primates facilitates locomotion in arboreal settings. Here, we evaluated apparent density (AD) in the subchondral bone of human, ape, and monkey calcanei exhibiting different types of foot loading. We used computed tomography osteoabsorptiometry and maximum intensity projection (MIP) maps to visualize AD in subchondral bone at the cuboid articular surface of calcanei. MIPs represent 3D volumes (of subchondral bone) condensed into 2D images by extracting AD maxima from columns of voxels comprising the volumes. False-color maps are assigned to MIPs by binning pixels in the 2D images according to brightness values. We compared quantities and distributions of AD pixels in the highest bin to test predictions relating AD patterns to habitual locomotor modes and foot posture categories of humans and several nonhuman primates. Nonhuman primates exhibit dorsally positioned high AD concentrations, where maximum compressive loading between the calcaneus and cuboid likely occurs during "midtarsal break" of support. Humans exhibit less widespread areas of high AD, which could reflect reduced fore- and midfoot mobility. Analysis of the internal morphology of the tarsus, such as subchondral bone AD, potentially offers new insights for evaluating primate foot function during locomotion.

The properties of Titan's surface at the Huygens landing site from DISR observations

The descent imager/spectral radiometer (DISR) onboard the Huygens probe investigated the radiation balance inside Titan's atmosphere and took hundreds of images and spectra of the ground during the descent. The scattering of the aerosols in the atmosphere and the absorption by methane strongly influence the irradiation reaching the surface and the signals received by the various instruments. The physical properties of the surface can only be assessed after the influence of the atmosphere has been taken into account and properly removed. In the broadband visible images (660 to 1000 nm) the contrast of surface features is strongly reduced by the aerosol scattering. Calculations show that for an image taken from an altitude of 14.5 km, the corrected contrast is about three times higher than in the raw image. Spectral information of the surface by the imaging spectrometers in the visible and near infrared range can only be retrieved in the methane absorption windows. Intensity ratios from the methane windows can be used to make false color maps. The elevated bright ‘land’ terrain is redder than the flat dark ‘lake bed’ terrain. The reflectance spectra of the land and lake bed area in the IR are derived, as well as the reflectance phase function in the limited range from 20 ∘ to 50 ∘ phase angle. An absorption feature at 1.55 μ m which may be attributed tentatively to water ice is found in the lake bed, but not in the land area. Otherwise the surface exhibits a featureless blue slope in the near-IR region (0.9– 1.6 μ m ). Brightness profiles perpendicular to the coast line show that the bottoms of the channels of the large scale flow pattern become darker the further they are away from the land area. This could be interpreted as sedimentation of the bright land material transported by the rivers into the lake bed area. The river beds in the deeply incised valleys need not to be covered by dark material. Their roughly 10% brightness decrease could be caused by the illumination as illustrated by a model calculation. The size distribution of cobbles seen in the images after landing is in agreement with a single major flooding of the area with a flow speed of about 1 m s - 1 .

Recent aeolian erosion and deposition in the north polar plateau of Mars

Background: Planum Boreum, the north polar plateau of Mars, displays four extensive low-albedo regions covered with widespread sedimentary deposits that are thick enough to partly or completely suppress the signature of the residual water ice that forms the uppermost zone of the polar layered deposits. These sedimentary deposits appear to have a source primarily in a buried sedimentary layer preferentially exposed along the walls and floors of some polar troughs. The deposits extend and drape over circum-polar dunes. Method: The data analyses in this research were conducted with Geographic Information Systems (GIS) mapping tools. The following data sets have been used: (1) Mars Odyssey (MO) Thermal Emission Imaging System (THEMIS) summer north polar visible light mosaics at 18 m/pixel and 32 m /pixel, as well as 18 m/pixel visible multiband images (THEMIS mosaic provided by P.H. Christensen and the THEMIS Team, Arizona State U.), (2) Mars Express (MEX) High Resolution Stereo Camera (HRSC) images at 10 m/pixel, (3) Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) narrow-angle (NA; >1.4 m/pixel) and a wide-angle image mosaic, 64 pixels/degree, (4) Mars Reconnaissance Orbiter (MRO) High Resolution Imaging Science Experiment (HiRISE) camera images at resolutions that range from 31.8 cm/pixel (with 1 x 1 binning) to 63.5 cm/pixel (with 2 x 2 binning), (5) MGS Mars Orbiter Laser Altimeter (MOLA) 512 pixels/degree digital elevation models, and (6) MEX OMEGA Vis/IR imaging spectrometer. False color maps have been derived from OMEGA data in which all three color planes are proportional to albedo (0.1: level 0, 0.45: level 255). The red plane scales inversely with the fraction of the area covered by ice, derived from the band strength at 1.5 μm (factor of 0 for 30% fractional ice coverage within the pixel, factor of 1 for ice-free pixels). The H2O ice spectral signatures have been observed by OMEGA in November 2004, during early northern summer (Ls 109° to 114°). The incidence at the time of observations was nearly optimal for such latitude regions (57.6°). Sampling on the ground was 1.7 to 2 km. Conclusion: The most recent history of the north polar plateau of Mars includes highly dynamic sedimentary processes involving large-scale wind-driven mass transfer from Planum Boreum towards its periphery. The proposed polar processes involved: (I) retreat along undulations within upper layered deposits (ULD), thereby exposing underlying dark sedimentary deposits, (II) mobilization of these deposits to form extensive dark mantles, which are water-ice free and that terminate in circum-polar terrains, and (III) complete removal of these deposits leading to the exhumation of pre-existing

Full-wafer spatial mapping of macrodefects on HgCdTe epitaxial wafers grown by MBE

We have constructed an optical microscopy system to automatically locate, count, and determine the size of polycrystalline “void” defects on epitaxial layers of HgCdTe grown on CdZnTe or Si substrates. Void macrodefects are readily imaged because their polycrystalline surface is rough, and consequently they scatter light out of the image under specular reflection imaging conditions. Using a computer-controlled stage to move the wafer, a succession of individual, contiguous bright-field images is recorded over the entire wafer. Each image is analyzed by software to locate and characterize all the light-scattering objects present in the frame. Several different representations of the spatial distribution and size of defects are generated, and these can be presented either as false-color density maps or dot-location maps. In addition, various types of statistics on the defect population and size distributions are also available. These data not only convey overall information on the quality of a given wafer, and as such are quite useful for screening to determine which wafers are suitable for array fabrication, but they also allow inferences to be made concerning the origin or root cause of different classes of defects. Several examples are presented to illustrate the use of full-wafer defect mapping to identify macrodefect problems in HgCdTe growth on CdZnTe that can arise from substrate temperature lateral nonuniformity, nonmatched source flux angular distributions, substrate contamination, and intrinsic substrate imperfections.

Delimitation of squamous cell cervical carcinoma using infrared microspectroscopic imaging

Infrared (IR) spectroscopic imaging coupled with microscopy has been used to investigate thin sections of cervix uteri encompassing normal tissue, precancerous structures, and squamous cell carcinoma. Methods for unsupervised distinction of tissue types based on IR spectroscopy were developed. One-hundred and twenty-two images of cervical tissue were recorded by an FTIR spectrometer with a 64x64 focal plane array detector. The 499,712 IR spectra obtained were grouped by an approach which used fuzzy C-means clustering followed by hierarchical cluster analysis. The resulting false color maps were correlated with the morphological characteristics of an adjacent section of hematoxylin and eosin-stained tissue. In the first step, cervical stroma, epithelium, inflammation, blood vessels, and mucus could be distinguished in IR images by analysis of the spectral fingerprint region (950-1480 cm(-1)). In the second step, analysis in the spectral window 1420-1480 cm(-1) enables, for the first time, IR spectroscopic distinction between the basal layer, dysplastic lesions and squamous cell carcinoma within a particular sample. The joint application of IR microspectroscopic imaging and multivariate spectral processing combines diffraction-limited lateral optical resolution on the single cell level with highly specific and sensitive spectral classification on the molecular level. Compared with previous reports our approach constitutes a significant progress in the development of optical molecular spectroscopic techniques toward an additional diagnostic tool for the early histopathological characterization of cervical cancer.

Imaging linear birefringence and dichroism in cerebral amyloid pathologies.

New advances in polarized light microscopy were used to image Congo red-stained cerebral amyloidosis in sharp relief. The rotating-polarizer method was used to separate the optical effects of transmission, linear birefringence, extinction, linear dichroism, and orientation of the electric dipole transition moments and to display them as false-color maps. These effects are typically convolved in an ordinary polarized light microscope. In this way, we show that the amyloid deposits in Alzheimer's disease plaques contain structurally disordered centers, providing clues to mechanisms of crystallization of amyloid in vivo. Comparisons are made with plaques from tissues of subjects having Down's syndrome and a prion disease. In plaques characteristic of each disease, the Congo red molecules are oriented radially. The optical orientation in amyloid deposited in blood vessels from subjects having cerebral amyloid angiopathy was 90 degrees out of phase from that in the plaques, suggesting that the fibrils run tangentially with respect to the circumference of the blood vessels. Our result supports an early model in which Congo red molecules are aligned along the long fiber axis and is in contrast to the most recent binding models that are based on computation. This investigation illustrates that the latest methods for the optical analysis of heterogeneous substances are useful for in situ study of amyloid.

Electric organ discharges of the gymnotiform fishes: III. Brachyhypopomus.

We measured and mapped the electric fields produced by three species of neotropical electric fish of the genus Brachyhypopomus (Gymnotiformes, Rham phichthyoidea, Hypopomidae), formerly Hypopomus. These species produce biphasic pulsed discharges from myogenic electric organs. Spatio-temporal false-color maps of the electric organ discharges measured on the skin show that the electric field is not a simple dipole in Brachyhypopomus. Instead, the dipole center moves rostro-caudally during the 1st phase (P1) of the electric organ discharge, and is stationary during the 2nd phase (P2). Except at the head and tip of tail, electric field lines rotate in the lateral and dorso-ventral planes. Rostrocaudal differences in field amplitude, field lines, and spatial stability suggest that different parts of the electric organ have undergone selection for different functions; the rostral portions seem specialized for electrosensory processing, whereas the caudal portions show adaptations for d.c. signal balancing and mate attraction as well. Computer animations of the electric field images described in this paper are available on web sites http:/(/) www.bbb.caltech.edu/ElectricFish or http:/(/)www.fiu.edu/-stoddard/electric fish.html.