Vertical Cross-sectional Images Research Articles

Leucine Repeat Rich Kinase 1 Controls Osteoclast Activity by Managing Lysosomal Trafficking and Secretion.

We previously demonstrated that mice with targeted deletion of the leucine repeat rich kinase 1 (Lrrk1) gene were osteopetrotic due to the failure of osteoclasts to resorb bone. To determine how LRRK1 regulates osteoclast activity, we examined the intracellular and extracellular acidification with an acidotropic probe, acridine orange, in live osteoclasts on bone slices. We examined lysosome distribution in osteoclasts by localization of LAMP-2, cathepsin K, and v-ATPase by immunofluorescent staining with specific antibodies. We found that both vertical and horizontal cross-sectional images of the wild-type (WT) osteoclasts showed orange-staining of the intracellular acidic vacuoles/lysosomes dispersed to the ruffled border. By contrast, the LRRK1 deficient osteoclasts exhibited fluorescent orange staining in the cytoplasm away from the extracellular lacunae because of an altered distribution of the acidic vacuoles/lysosomes. In addition, WT osteoclasts displayed a peripheral distribution of LAMP-2 positive lysosomes with a typical actin ring. The clustered F-actin constitutes a peripheral sealing zone and a ruffled border which was stretched out into a resorption pit. The LAMP-2 positive lysosomes were also distributed to the sealing zone, and the cell was associated with a resorption pit. By contrast, LRRK1-deficient osteoclasts showed diffused F-actin throughout the cytoplasm. The sealing zone was weak and not associated with a resorption pit. LAMP-2 positive lysosomes were also diffuse in the cytoplasm and were not distributed to the ruffled border. Although the LRRK1-deficient osteoclast expressed normal levels of cathepsin K and v-ATPase, the lysosomal-associated cathepsin K and v-ATPase were not accumulated at the ruffled border in Lrrk1 KO osteoclasts. Our data indicate that LRRK1 controls osteoclast activity by regulating lysosomal distribution, acid secretion, and protease exocytosis.

Enlarged rete pegs with excessive accumulation of melanosomes leading to darker aging spots revealed by histomorphological measurements of internal structures of the epidermis.

Various histological studies of facial pigmented spot sites such as solar lentigo have been reported, but few studies have used quantitative indices by histomorphometric analysis of the internal structure of pigmented spot sites using non-invasive methods. In the present study, to quantitatively elucidate morphological changes in the epidermis in male, darker-pigmented spots and female, light-pigmented spots, indices that characterize the internal structure of the epidermis in pigmented spot sites were measured using in vivo confocal laser scanning microscopy (CLSM). The darkness of pigmented spots on the cheeks of 69 women and 43 men was analysed using image analysis software. The L* value was calculated from RGB values obtained from facial images. The internal structures of pigmented spots on the cheeks of 13 subjects were observed by CLSM. Various parameters were measured using CLSM images from the surface of the stratum corneum to the bottom of the dermal papillae, including the thickness of the epidermis, melanosome content, and shape of the dermal papillae. Mean ΔL* values between pigmented spots and non-pigmented areas of male subjects were significantly increased in the 40s and 50s compared with those of female subjects. Conspicuous pigmented spots increased in the 40s in male subjects and the 50s in female subjects. In CLSM observations, significant increases in the thickness of the epidermis and melanosome content were confirmed in pigmented spots compared with surrounding non-pigmented areas. In particular, melanosome content in the male subject group with dark-coloured pigmented spots increased significantly to about eight times that of non-pigmented areas, and more than double that of the male subject group with light-coloured pigmented spots. From the measurements of quantitative parameters, morphological changes in the epidermis were clearly related to the surface colour tone of pigmented spots. Darker pigmented spot sites tended to show longer rete pegs in the epidermis. Accumulation of melanosomes in epidermal basal cells could be considered to increase with the degree of elongation of rete pegs at pigmented spot sites and, thus, induce darker pigmented spots.

ODTiD: Optic Nerve Head SD-OCT Image Dataset.

IntroductionOptic disc tilt (ODT) or tilted optic disc is a common finding in the general population. It is due to anomalous development caused by the malclosure of the embryonic optic fissure. ODT is commonly associated with high myopia as well as other conditions. In recent days, the common method to image the optic disc (OD) is by optical coherence tomography (OCT). To the best of our knowledge, there are no datasets of ODT available in the public domain. This dataset aims to make open access raw ODT OCT images to test out new image processing segmentation algorithms.MethodsThis dataset of ODT images contains both horizontal and vertical cross-sectional images obtained using spectral-domain optical coherence tomography (SD-OCT, Cirrus 5000, Carl Zeiss Meditec Inc., Dublin, CA). The optic disc cube 200×200 program was used and all the images are aligned with the center of the optic nerve head. This dataset includes images from both clinically normal (20 eyes) and myopic subjects (101 eyes).ResultsThe dataset consists of clear (121) and manually marked (121) images resulting in a total of 242 images. The age distribution for all subjects combined is 27.24 ± 9.28 (range, 11.0–69.0) years. For normal subjects mean ± SD age distribution is 32.40 ± 17.23 years. Similarly, the myopia age distribution is 26.22 ± 6.37 years. Ground truth images, ie, manually segmented by a clinical expert are provided along with other meta-data includes age, gender, laterality, refractive error classification, spherical equivalent (SE), best-corrected visual acuity (BCVA), intraocular pressure (IOP), and axial length (AXL).ConclusionThis open, public database is online at the ICPSR website of the University of Michigan. The dataset can be used to test and validate newly developed automated segmentation algorithms.

Macular irregularities of optical coherence tomographic vertical cross sectional images in school age children

The purpose of this study was to compare the incidences of macular irregularities of elementary school (ES) and junior high school (JHS) students. This was a prospective cross-sectional observational study of 122 right eyes of 122 ES students (8–9 years) and 173 right eyes of 173 JHS students (12–13 years). Vertical cross-sectional images of the macula were obtained by optical coherence tomography. The eyes were classified based on the vertical symmetry of the posterior pole, and then sub-classified as convex-, flat-, concave-, or dome-shaped based on the direction of the curvature of the retinal pigment epithelium. One hundred and two eyes (83.6%) were placed in the symmetrical group in the ES students and 149 eyes (86.1%) in the JHS students. Twenty eyes (16.4%) were placed in the asymmetric groups in the ES students and 24 eyes (13.9%) in the JHS students. In symmetrical group, 78 and 118 eyes had a convex-shape (76.4 and 79.2%), followed by 22 and 29 eyes of dome-shaped group (21.6 and 19.4%) in ES and JHS students respectively. Because the incidences of the posterior pole shapes were not significantly different between the groups, it is likely that the macular irregularities develop before the age of ES.

3-D X-ray computed tomography on failure characteristics of rock-like materials under coupled hydro-mechanical loading

In this article, influences of confining pressures and internal fluid pressures on fracture behavior in rock-like materials subjected to both mechanical loads and internal hydraulic pressures is experimentally studied using the 3-D X-ray computed tomography combined with 3-D reconstruction techniques. Six different types of the pre-cracked rock-like specimens subjected to different confining pressures and internal fluid pressures are first conducted using a rock mechanics testing system. Then, the broken pre-flawed rock-like specimens are analyzed using a 3-D X-ray computed tomography (CT) scanning system. Subsequently, the internal damage behavior of failed pre-flawed rock-like specimens is evaluated by the 3-D reconstruction techniques, according to the horizontal and vertical cross-sectional CT images. The experimental results demonstrate that the peak strengths of pre-cracked rock-like specimens in the triaxial compression with fixed confining pressures decrease as the internal fluid pressures increases. On the other hand, when the internal fluid pressures are fixed, peak strengths of pre-cracked rock-like specimens in the triaxial compression increase with increasing the confining pressures. Furthermore, the 3-D X-ray Computed Tomography technique provides that the ultimate 3-D internal failure mode in pre-cracked rock-like specimens under the hydro-mechanical loading conditions are affected by both confining pressures and internal fluid pressures. Influences of confining and internal fluid pressures on the crack areas, crack aperture extent and the fractal dimension of 3-D fragments are investigated to reveal the coupled hydro-mechanical fracturing mechanism. In addition, the Scanning Electron Microscope (SEM) observations illustrate that the fracture surface roughness in the regions of crack initiation at the microscale decreases as the internal fluid pressures increases.

Strength, deformability and X-ray micro-CT observations of transversely isotropic composite rock under different confining pressures

In this paper, the strength and deformation behavior of transversely isotropic composite rock-like material, which consists of a hard rock-like material and a weak rock-like material, are first investigated under different confining pressures by using a rock triaxial testing system. The triaxial compression results show that the composite rock-like material shows distinct anisotropy, the strength shows a “U” type variation with respect to the inclination angle, and the apparent friction angle value and cohesion value show dispersion with respect to the inclination angle. With the advance of scientific instrumentation, X-ray computed tomography (CT) scanning has been used as a powerful inspection tool and has been applied to many fields for non-destructive structure and failure analysis. After the compression tests, a Nanotom 160 high-resolution micro-CT was employed to investigate the failure mechanism of transversely isotropic composite rock-like material on the micro-level. The 3D volume renders are in good agreement with the actual surface crack photographs of transversely isotropic composite specimens, which demonstrating that X-ray micro-CT scanning can be used to explore the damage of rock-like material. The internal crack distribution and damage can be clearly observed from the vertical and horizontal cross-section images of 3D volume renders. It further reveals that the failure mode of transversely isotropic composite rock-like specimens is transformed from tensile failure at low inclination angles to shear slippage at medium inclination angles. The impact of confining pressure on the failure mode and crack distribution from the 3D volume renders, which is also discussed, reveals that the mechanical properties of hard and weak rock materials are the key to control the crack distribution with increasing confining pressure.

Fracturing Mechanism of Compressed Hollow-Cylinder Sandstone Evaluated by X-ray Micro-CT Scanning

Triaxial compression experiments under confining pressures of 16 and 35 MPa were first carried out for hollow-cylinder sandstone specimens using a rock mechanics testing system. Four hollow-cylinder sandstone specimens were compressed to various deformation positions before or after the peak strength. Then, the compressed hollow-cylinder sandstone specimens were analysed using a three-dimensional X-ray micro computed tomography (CT) scanning system. Based on the horizontal and vertical cross-sectional CT images, the internal damage behaviour of hollow-cylinder sandstone specimens was evaluated. It can be seen that the crack system of hollow-cylinder sandstone specimens with higher compressed deformation after the peak strength are more complicated than those with lower compressed deformation close to the peak strength. In the present study, the hollow-cylinder sandstone specimens with lower compressed deformation are only dominated by some internal wall fractures resulting mainly from shear cracks, whereas the hollow-cylinder sandstone specimens with higher compressed deformation are mainly dominated by two shear fractures, as well as some tensile cracks. For the same axial stress level, hollow-cylinder sandstone under a higher confining pressure has a more complicated crack system than that under a lower confining pressure. The experimental results demonstrated that the three-dimensional cracks in the hollow specimen under triaxial compression are first initiated from the internal wall due to shear slippage, and then propagate towards the top or bottom boundary of the specimen in shear fracture mode. To better explain the internal crack evolution mechanism of hollow-cylinder sandstone during the entire loading, a conceptual model of hollow-cylinder sandstone material under the action of confining pressure is proposed. At the same time, the effect of the borehole size on the internal damage behaviour of the compressed specimen after the peak strength is also discussed. The investigated conclusions are significant for predicting the instability occurring around deep well bores in petroleum engineering and for ensuring the safety of deep excavation damage zones in tunnel engineering.

Multi-photon vertical cross-sectional imaging with a dynamically-balanced thin-film PZT z-axis microactuator.

Use of a thin-film piezoelectric microactuator for axial scanning during multi-photon vertical cross-sectional imaging is described. The actuator uses thin-film lead-zirconate-titanate (PZT) to generate upward displacement of a central mirror platform, micro-machined from a silicon-on-insulator (SOI) wafer to dimensions compatible with endoscopic imaging instruments. Device modeling in this paper focuses on existence of frequencies near device resonance producing vertical motion with minimal off-axis tilt even in the presence of multiple vibration modes and non-uniformity in fabrication outcomes. Operation near rear resonance permits large stroke lengths at low voltages relative to other vertical microactuators. Highly uniform vertical motion of the mirror platform is a key requirement for vertical cross-sectional imaging in the remote scan architecture being used for multi-photon instrument prototyping. The stage is installed in a benchtop testbed in combination with an electrostatic mirror that performs in-plane scanning. Vertical sectional images are acquired from 15 μm diameter beads and excised mouse colon tissue.

An Electrostatic MEMS Translational Scanner with Large Out-of-Plane Stroke for Remote Axial-Scanning in Multi-Photon Microscopy

We present an electrostatic microelectromechanical systems (MEMS) resonant scanner with large out-of-plane translational stroke for fast axial-scanning in a multi-photon microscope system for real-time vertical cross-sectional imaging. The scanner has a compact footprint with dimensions of 2.1 mm × 2.1 mm × 0.44 mm, and employs a novel lever-based compliant mechanism to enable large vertical displacements of a reflective mirror with slight tilt angles. Test results show that by using parametrical resonance, the scanner can provide a fast out-of-plane translational motion with ≥400 μm displacement and ≤0.14° tilt angle over a wide frequency range of ~390 Hz at ambient pressure. By employing this MEMS translational scanner and a biaxial MEMS mirror for lateral scanning, vertical cross-sectional imaging with a beam axial-scanning range of 200 μm and a frame rate of ~5–10 Hz is enabled in a remote scan multi-photon fluorescence imaging system.

Microarchitecture of the Vitreous Body: A High-Resolution Optical Coherence Tomography Study

To report novel vitreous body microarchitecture findings using high-resolution spectral-domain optical coherence tomography (HR-SD-OCT). Prospective, cross-sectional study. Horizontal and vertical retinal cross-sectional images that were 10mm long were acquired from 17 eyes of 17 young healthy volunteers using HR-SD-OCT with enhanced vitreous imaging (EVI). Images were acquired through the fovea, upper vessel arcade, and lower vessel arcade. Three new findings on vitreous body microarchitecture were found. First, material located between the retina and posterior vitreous cortex was easily detected in 90% of upper and lower vessel arcade scans. Most scans contained hyperreflective dots and multilayered hyperreflective lines around the detached vitreous cortex. Second, a lamellar structure was observed in the vitreous body in 70%-80% of all scans, excluding vertical scans of the upper arcade vessel area. Third, tubular zones of hypodensity were detected in >80% of scans, excluding horizontal scans of the macula. Interestingly, the location of tubular zones of hypodensity seemed to correspond with the location of retinal vessels. Subject age, refractive error, and axial length were not significantly different in scans with and without material between the retina and vitreous, lamellar structures, and tubular zones of hypodensity. The microarchitecture of the vitreous body can be visualized using HR-SD-OCT and EVI.

Integrated monolithic 3D MEMS scanner for switchable real time vertical/horizontal cross-sectional imaging.

We present an integrated monolithic, electrostatic 3D MEMS scanner with a compact chip size of 3.2 × 2.9 mm(2). Use of parametric excitation near resonance frequencies produced large optical deflection angles up to ± 27° and ± 28.5° in the X- and Y-axes and displacements up to 510 μm in the Z-axis with low drive voltages at atmospheric pressure. When packaged in a dual axes confocal endomicroscope, horizontal and vertical cross-sectional images can be collected seamlessly in tissue with a large field-of-view of >1 × 1 mm(2) and 1 × 0.41 mm(2), respectively, at 5 frames/sec.

A three-degree-of-freedom thin-film PZT-actuated microactuator with large out-of-plane displacement

A novel three degree-of-freedom microactuator based on thin-film lead-zirconate-titanate (PZT) is described with its detailed structural model. Its central rectangular-shaped mirror platform, also referred to as the stage, is actuated by four symmetric PZT bending legs such that each leg provides vertical translation for one corner of the stage. It has been developed to support real-time in vivo vertical cross-sectional imaging with a dual axes confocal endomicroscope for early cancer detection, having large displacements in three axes (z, θx, θy) and a relatively high bandwidth in the z-axis direction. Prototype microactuators closely meet the performance requirements for this application; in the out-of-plane (z-axis) direction, it has shown more than 177 μm of displacement and about 84 Hz of structural natural frequency, when two diagonal legs are actuated at 14V. With all four legs, another prototype of the same design with lighter stage mass has achieved more than 430 μm of out-of-plane displacement at 15V and about 200 Hz of bandwidth. The former design has shown approximately 6.4° and 2.9° of stage tilting about the x-axis and y-axis, respectively, at 14V. This paper also presents a modeling technique that uses experimental data to account for the effects of fabrication uncertainties in residual stress and structural dimensions. The presented model predicts the static motion of the stage within an average absolute error of 14.6 μm, which approaches the desired imaging resolution, 5 μm, and also reasonably anticipates the structural dynamic behavior of the stage. The refined model will support development of a future trajectory tracking controller for the system.

Vertical Cross-sectional Imaging of Colonic Dysplasia In Vivo With Multi-spectral Dual Axes Confocal Endomicroscopy

Pathologists evaluate histology sectioned perpendicular to the tissue surface, or vertical cross-section. This orientation (XZ-plane) enables evaluation of mucosal differentiation in the basilar-to-luminal direction. Current endomicroscopes use a conventional (single axis) optical design.1 Imaging is limited to horizontal cross-sections (XY-plane) where the micro-anatomy is frequently similar across the field-of-view (FOV). In the dual axes configuration, light is delivered and collected off-axis, and images can be detected over a much larger range of intensities.2 Molecular images collected using fluorescence can improve specificity for disease detection and reveal functional properties about tissue.3 Proper interpretation of these images requires correlation with the micro-anatomy. We aim to demonstrate the simultaneous collection of two fluorescence images in vivo in vertical cross-sections using a dual axes confocal endomicroscope. An overlay of molecular and anatomical images from normal and dysplastic mouse colonic mucosa will be displayed in real time.

A review of ground-penetrating radar studies related to peatland stratigraphy with a case study on the determination of peat thickness in a northern boreal fen in Quebec, Canada

Ground-penetrating radar (GPR) is a non-intrusive geophysical observation method based on propagation and reflection of high-frequency electromagnetic waves in the shallow subsurface. The vertical cross-sectional images obtained allow the identification of thickness and lithologic horizons of different media, without destruction. Over the last decade, several studies have demonstrated the potential of GPR. This paper presents a review of recent GPR applications to peatlands, particularly to determine peat stratigraphy. An example study of acquisition and comparison of peatland soil thickness of a fen-dominated watershed located in the James Bay region of Quebec, using (1) a meter stick linked to a GPS RTK and (2) a GSSI GPR, is given. A coefficient of determination ( r2) of 56% was obtained between the ordinary krigings performed on data gathered using both techniques. Disparities occurred mainly in the vicinity of ponds which can be explained by the attenuation of GPR signal in open water. Despite these difficulties – the higher time required for analysis and the error margin – it seems more appropriate to use a GPR, instead of a graduated rod linked to a GPS, to measure the peat depths on a site like the one presented in this study. Manual measurements, which are user-dependent in the context of variable mineral substrate densities and with the presence of obstacles in the substrate, may be more subjective.

651 Targeted Vertical Cross-Sectional Imaging With Near-Infrared Dual Axes Confocal Fluorescence Endomicroscope

Background: Pathologists review histology cut perpendicular to the tissue surface or in the vertical cross-section in order to visualize the normal or abnormal differentiation pattern of tissue. Unlike other endomicrosope designs, the dual axes confocal architecture has sufficient dynamic range to image in this orientation. Dysplasia is a pre-malignant condition in the colon that can progress into colorectal cancer. Peptides have demonstrated tremendous potential for in vivo use to detect colonic dysplasia and can be labeled with near-infrared (NIR) dyes for visualizing the full depth of the epithelium. Aims: We aim to demonstrate vertical cross-sectional images over a large field-of-view (FOV) with a dual axes confocal endomicroscope of NIR fluorescence images that visualize specific peptide binding to dysplasia in the mouse colon. Methods: We use a peptide selected with phage display technology. The amino acid sequence LTTHYKL is connected on the C-terminus by a GGGSK linker to the Cy5.5 fluorophore to prevent steric hindrance, hereafter LTT*-Cy5.5. We use CPC;Apc mice that are genetically engineered to spontaneously develop pre-malignant colonic lesions that resemble that of human disease on histology. CPC;Apc mice of age 6-7 months were injected with the Cy5.5-labeled peptide, LTT*-Cy5.5, at a concentration of 400 μM via tail vein. The peptide conjugate was allowed to circulate for 15 minutes. The mice were then euthanized, and the colon was excised, washed, blotted dry, and mounted on glass slides using 3M Vetbond tissue adhesive. The fresh colonic bulk tissues were imaged immediately with 2 mW of excitation at wavelength 671 nm. The tissues were then fixed with 10% buffered formalin for 24 hours, paraffin-embedded and sectioned into 10 μm thin slices and stained with hematoxylin and eosin (H&E). Results: NIR fluorescence images of colonic mucosa show dysplastic crypts in the vertical orientation, demonstrating the histology-like performance over a FOV of 800 μm (width)×400 μm (depth). The contrast from specific binding of the LTT-Cy5.5 peptide can be appreciated by the image of the border between normal colonic mucosa and dysplasia, Fig. a. Vertically oriented crypts can be appreciated in the corresponding histology (H&E), scale bar 200 μm, Fig. b. Use of a specific binding peptide allows for the transition from normal to pre-malignant mucosa to be visualized with high contrast at the same Photomultiplier tube (PMT) gain setting. Compared to normal colonic mucosa, the NIR fluorescence intensity of dysplasia is greater by at least a factor of 3. Conclusions: We demonstrate vertical cross-sectional imaging using a novel dual axes confocal endomicroscope based to collect NIR fluorescence images over a 800 μm ×400 μm field-of-view to detect Cy5.5-labeled peptides that bind specifically to pre-malignant colonic mucosa.

Targeted vertical cross-sectional imaging with handheld near-infrared dual axes confocal fluorescence endomicroscope

We demonstrate vertical cross-sectional (XZ-plane) images of near-infrared (NIR) fluorescence with a handheld dual axes confocal endomicroscope that reveals specific binding of a Cy5.5-labeled peptide to pre-malignant colonic mucosa. This view is perpendicular to the tissue surface, and is similar to that used by pathologists. The scan head is 10 mm in outer diameter (OD), and integrates a one dimensional (1-D) microelectromechanical systems (MEMS) X-axis scanner and a bulky lead zirconate titanate (PZT) based Z-axis actuator. The microscope images in a raster-scanning pattern with a ±6 degrees (mechanical) scan angle at ~3 kHz in the X-axis (fast) and up to 10 Hz (0–400 μm) in the Z-axis (slow). Vertical cross-sectional fluorescence images are collected with a transverse and axial resolution of 4 and 5 μm, respectively, over a field-of-view of 800 μm (width) × 400 μm (depth). NIR vertical cross-sectional fluorescence images of fresh mouse colonic mucosa demonstrate histology-like imaging performance with this miniature instrument.

Visualization of soil arching on reinforced embankment with rigid pile foundation using X-ray CT

The purpose of this paper is to study and compare arching in reinforced and unreinforced piled embankments for different fill materials and pile spacings. Toyoura sand, silica sand no.7, silica sand no.8 and dry powder clay are used as fill materials. In this study, X-ray CT method is used as a non-destructive technique to examine the load distribution mechanism quantitatively. Vertical cross sectional images are constructed by the data obtained from CT scanning. It is seen that low density areas represent the shear planes and dilatancy in the arch within the piled embankment. The angle of density change is defined as the angle formed by the arch-shaped shear plane and the horizontal plane within the inter-pile soil. While Toyoura sand has the smallest angle of density change due to the largest peak internal friction angle and the effective particle size, dry powder clay has the largest angle of density change. The earth reinforcement is found to be effective with the use of pile elements for the purpose of stress re-distribution in the fill. Furthermore, the amount of the embankment loading is visualized by three dimensional extraction images. The effectiveness of the proposed method is verified by conducting a comparative study with the current Japanese design model. It is shown that, using X-ray CT method and visualization techniques provide a better understanding of soil arching in a reinforced embankment with rigid pile foundation system.

Cross Tropopause Transport of Water by Mid-Latitude Deep Convective Storms: A Review

Recent observational and numerical modeling studies of the mechanisms which transport moisture to the stratosphere by deep convective storms at mid-latitudes are reviewed. Observational evidence of the cross-tropopause transport of moisture by thunderstorms includes satellite, aircraft and ground-based data. The primary satellite evidence is taken from both conventional satellite of thunderstorm images and CloudSat vertical cloud cross-section images. The conventional satellite images show cirrus plumes above the anvil tops of some of the convective storms where the anvils are already at the tropopause level. The CloudSat image shows an indication of penetration of cirrus plume into the stratosphere. The aircraft observations consist of earlier observations of the ”jumping cirrus” phenomenon reported by Fujita and recent detection of ice particles in the stratospheric air associated with deep convective storms. The ground-based observations are video camera records of the jumping cirrus phenomenon occurring at the top of thunderstorm cells. Numerical model studies of the penetrative deep convective storms were performed utilizing a three-dimensional cloud dynamical model to simulate a typical severe storm which occurred in the US Midwest region on 2 August 1981. Model results indicate two physical mechanisms that cause water to be injected into the stratosphere from the storm: (1) the jumping cirrus mechanism which is caused by the gravity wave breaking at the cloud top, and (2) an instability caused by turbulent mixing in the outer shell of the overshooting dome. Implications of the penetrative convection on global processes and a brief future outlook are discussed.

Improved rejection of multiply scattered photons in confocal microscopy using dual-axes architecture.

We perform Monte Carlo simulations to show that the dual-axes (DA) confocal architecture has superior rejection of multiply scattered photons in tissue to that of single axis. As a result, the DA configuration provides improved signal-to-noise ratio and dynamic range, and thus is sensitive to ballistic photons from deeper within tissue, features that are particularly useful for performing vertical cross-sectional reflectance images in tissue.

Formation Mechanism and Ferroelectric Behavior of Nano-Domains in Ultra-Thin BaTiO3 Films

Ultra-thin BaTiO3 films (2–10 nm thick) deposited on thin LaNiO3 electrodes show a ferroelectric behavior characterized by a polarization hysteresis loop. Extreme polarization anisotropy is observed between the parallel and vertical directions relative to the film plane. The remanent polarization is higher by two orders of magnitude and the coercive field is lower by 5 orders of magnitude in the parallel compared to the vertical direction of the film plane. This extreme anisotropy is attributed to preferred orientation of nano-domains in parallel to the film plane, as observed in HRTEM vertical cross section images. Only 180° domains are formed in multi-domains structures via the twinning mechanism. The domain formation is accompanied with stress relaxation measured in-situ during cooling through the transition temperatures. The switching time of the nano-domains is in the range of tens of nsec and the switching kinetics is unidirectional. A fatigue edge at about 107 cycles under 5 Vac and 100 kHz is measured.