Suction-based grasping tool for removal of regular- and irregular-shaped intraocular foreign bodies.

PubMed

Erlanger, Michael S; Velez-Montoya, Raul; Mackenzie, Douglas; Olson, Jeffrey L

2013-01-01

To describe a suction-based grasping tool for the surgical removal of irregular-shaped and nonferromagnetic intraocular foreign bodies. A surgical tool with suction capabilities, consisting of a stainless steel shaft with a plastic handle and a customizable and interchangeable suction tip, was designed in order to better engage and manipulate irregular-shaped in-traocular foreign bodies of various sizes and physical properties. The maximal suction force and surgical capabilities were assessed in the laboratory and on a cadaveric eye vitrectomy model. The suction force of the water-tight seal between the intraocular foreign body and the suction tip was estimated to be approximately 40 MN. During an open-sky vitrectomy in a porcine model, the device was successful in engaging and firmly securing foreign bodies of different sizes and shapes. The suction-based grasping tool enables removal of irregular-shaped and nonferromagnetic foreign bodies. Copyright 2013, SLACK Incorporated.

Effect of Irregularity in Shape and Boundary of a Macro-Texture Region in Titanium (Postprint)

DTIC Science & Technology

2015-10-15

AFRL-RX-WP-JA-2016-0328 EFFECT OF IRREGULARITY IN SHAPE AND BOUNDARY OF A MACRO-TEXTURE REGION IN TITANIUM (POSTPRINT) James L...2 October 2014 – 15 September 2015 4. TITLE AND SUBTITLE EFFECT OF IRREGULARITY IN SHAPE AND BOUNDARY OF A MACRO-TEXTURE REGION IN TITANIUM ...aerospace grade titanium alloy material are measured to be about the same level as corner trapped shear wave signals. In addition to the abnormally high

Colors and Shapes of the Irregular Planetary Satellites

NASA Astrophysics Data System (ADS)

Graykowski, Ariel; Jewitt, David

2018-04-01

It is widely recognized that the irregular satellites of the giant planets were captured from initially heliocentric orbits. However, the mechanism of capture and the source region from which they were captured both remain unknown. We present an optical color survey of 43 irregular satellites of the outer planets conducted using the LRIS camera on the 10 m telescope at the Keck Observatory in Hawaii. The measured colors are compared to other planetary bodies in search for similarities and differences that may reflect upon the origin of the satellites. We find that ultrared matter (with color index B–R ≥ 1.6), while abundant in the Kuiper Belt and Centaur populations, is depleted from the irregular satellites. We also use repeated determinations of the absolute magnitudes to make a statistical estimate of the average shape of the irregular satellites. The data provide no evidence that the satellites and the main-belt asteroids are differently shaped, consistent with collisions as the major agent shaping both.

A comparison of 3 wound measurement techniques: effects of pressure ulcer size and shape.

PubMed

Bilgin, Mehtap; Güneş, Ulkü Yapucu

2013-01-01

The aim of this study was to examine the levels of agreement among 3 techniques used in wound measurement comparing more spherical versus irregularly shaped wounds. The design of this study is evaluative research. Sixty-five consecutive patients with 80 pressure ulcers of various sizes referred from a university hospital in Izmir, Turkey, were evaluated. The 80 pressure ulcers identified on the 65 participants were divided into 2 groups based on pressure ulcer shape and wound surface area. Twenty-four of the 80 ulcers (30%) were characterized as irregularly shaped and greater than 10 cm. Fifty-six were regularly shaped (approximating a circle) and less than 10 cm. Pressure ulcer areas were measured using 3 techniques: measurement with a ruler (wound area was calculated by measuring and multiplying the greatest length by the greatest width perpendicular to the greatest length), wound tracing using graduated acetate paper, and digital planimetry. The level of agreement among the techniques was explored using the intraclass correlation coefficient (ICC). Strong agreement was observed among the techniques when assessing small, more regularly shaped wounds (ICC = 0.95). Modest agreement was achieved when measuring larger, irregularly shaped wounds (ICC = 0.70). Each of these techniques is adequate for measuring surface areas of smaller wounds with an approximately circular shape. Measurement of pressure ulcer area via the ruler method tended to overestimate surface area in larger and more irregularly shaped wounds when compared to acetate and digital planimetry. We recommend digital planimetry or acetate tracing for measurement of larger and more irregularly shaped pressure ulcers in the clinical setting.

3D-shape recognition and size measurement of irregular rough particles using multi-views interferometric out-of-focus imaging.

PubMed

Ouldarbi, L; Talbi, M; Coëtmellec, S; Lebrun, D; Gréhan, G; Perret, G; Brunel, M

2016-11-10

We realize simplified-tomography experiments on irregular rough particles using interferometric out-of-focus imaging. Using two angles of view, we determine the global 3D-shape, the dimensions, and the 3D-orientation of irregular rough particles whose morphologies belong to families such as sticks, plates, and crosses.

Shape functions for velocity interpolation in general hexahedral cells

USGS Publications Warehouse

Naff, R.L.; Russell, T.F.; Wilson, J.D.

2002-01-01

Numerical methods for grids with irregular cells require discrete shape functions to approximate the distribution of quantities across cells. For control-volume mixed finite-element (CVMFE) methods, vector shape functions approximate velocities and vector test functions enforce a discrete form of Darcy's law. In this paper, a new vector shape function is developed for use with irregular, hexahedral cells (trilinear images of cubes). It interpolates velocities and fluxes quadratically, because as shown here, the usual Piola-transformed shape functions, which interpolate linearly, cannot match uniform flow on general hexahedral cells. Truncation-error estimates for the shape function are demonstrated. CVMFE simulations of uniform and non-uniform flow with irregular meshes show first- and second-order convergence of fluxes in the L2 norm in the presence and absence of singularities, respectively.

Evaluation of the Gini Coefficient in Spatial Scan Statistics for Detecting Irregularly Shaped Clusters

PubMed Central

Kim, Jiyu; Jung, Inkyung

2017-01-01

Spatial scan statistics with circular or elliptic scanning windows are commonly used for cluster detection in various applications, such as the identification of geographical disease clusters from epidemiological data. It has been pointed out that the method may have difficulty in correctly identifying non-compact, arbitrarily shaped clusters. In this paper, we evaluated the Gini coefficient for detecting irregularly shaped clusters through a simulation study. The Gini coefficient, the use of which in spatial scan statistics was recently proposed, is a criterion measure for optimizing the maximum reported cluster size. Our simulation study results showed that using the Gini coefficient works better than the original spatial scan statistic for identifying irregularly shaped clusters, by reporting an optimized and refined collection of clusters rather than a single larger cluster. We have provided a real data example that seems to support the simulation results. We think that using the Gini coefficient in spatial scan statistics can be helpful for the detection of irregularly shaped clusters. PMID:28129368

Analysis and characterization of high-resolution and high-aspect-ratio imaging fiber bundles.

PubMed

Motamedi, Nojan; Karbasi, Salman; Ford, Joseph E; Lomakin, Vitaliy

2015-11-10

High-contrast imaging fiber bundles (FBs) are characterized and modeled for wide-angle and high-resolution imaging applications. Scanning electron microscope images of FB cross sections are taken to measure physical parameters and verify the variations of irregular fibers due to the fabrication process. Modal analysis tools are developed that include irregularities in the fiber core shapes and provide results in agreement with experimental measurements. The modeling demonstrates that the irregular fibers significantly outperform a perfectly regular "ideal" array. Using this method, FBs are designed that can provide high contrast with core pitches of only a few wavelengths of the guided light. Structural modifications of the commercially available FB can reduce the core pitch by 60% for higher resolution image relay.

Particle morphology influence on mechanical and biocompatibility properties of injection molded Ti alloy powder.

PubMed

Gülsoy, H Özkan; Gülsoy, Nagihan; Calışıcı, Rahmi

2014-01-01

Titanium and Titanium alloys exhibits properties that are excellent for various bio-applications. Metal injection molding is a processing route that offers reduction in costs, with the added advantage of near net-shape components. Different physical properties of Titanium alloy powders, shaped and processed via injection molding can achieve high complexity of part geometry with mechanical and bioactivity properties, similar or superior to wrought material. This study describes that the effect of particle morphology on the microstructural, mechanical and biocompatibility properties of injection molded Ti-6Al-4V (Ti64) alloy powder for biomaterials applications. Ti64 powders irregular and spherical in shape were injection molded with wax based binder. Binder debinding was performed in solvent and thermal method. After debinding the samples were sintered under high vacuum. Metallographic studies were determined to densification and the corresponding microstructural changes. Sintered samples were immersed in a simulated body fluid (SBF) with elemental concentrations that were comparable to those of human blood plasma for a total period of 15 days. Both materials were implanted in fibroblast culture for biocompatibility evaluations were carried out. The results show that spherical and irregular powder could be sintered to a maximum theoretical density. Maximum tensile strength was obtained for spherical shape powder sintered. The tensile strength of the irregular shape powder sintered at the same temperature was lower due to higher porosity. Finally, mechanical tests show that the irregular shape powder has lower mechanical properties than spherical shape powder. The sintered irregular Ti64 powder exhibited better biocompatibility than sintered spherical Ti64 powder. Results of study showed that sintered spherical and irregular Ti64 powders exhibited high mechanical properties and good biocompatibility properties.

Multiple patterns of diblock copolymer confined in irregular geometries with soft surface

NASA Astrophysics Data System (ADS)

Li, Ying; Sun, Min-Na; Zhang, Jin-Jun; Pan, Jun-Xing; Guo, Yu-Qi; Wang, Bao-Feng; Wu, Hai-Shun

2015-12-01

The different confinement shapes can induce the formation of various interesting and novel morphologies, which might inspire potential applications of materials. In this paper, we study the directed self-assembly of diblock copolymer confined in irregular geometries with a soft surface by using self-consistent field theory. Two types of confinement geometries are considered, namely, one is the concave pore with one groove and the other is the concave pore with two grooves. We obtain more novel and different structures which could not be produced in other two-dimensional (2D) confinements. Comparing these new structures with those obtained in regular square confinement, we find that the range of ordered lamellae is enlarged and the range of disordered structure is narrowed down under the concave pore confinement. We also compare the different structures obtained under the two types of confinement geometries, the results show that the effect of confinement would increase, which might induce the diblock copolymer to form novel structures. We construct the phase diagram as a function of the fraction of B block and the ratio of h/L of the groove. The simulation reveals that the wetting effect of brushes and the shape of confinement geometries play important roles in determining the morphologies of the system. Our results improve the applications in the directed self-assembly of diblock copolymer for fabricating the irregular structures. Project supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20121404110004), the Research Foundation for Excellent Talents of Shanxi Provincial Department of Human Resources and Social Security, China, and the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi Province, China.

Greenstone belts: Their components and structure

NASA Technical Reports Server (NTRS)

Vearncombe, J. R.; Barton, J. M., Jr.; Vanreenen, D. D.; Phillips, G. N.; Wilson, A. H.

1986-01-01

Greenstone sucessions are defined as the nongranitoid component of granitoid-greenstone terrain and are linear to irregular in shape and where linear are termed belts. The chemical composition of greenstones is described. Also discussed are the continental environments of greenstone successions. The effects of contact with granitoids, geophysical properties, recumbent folds and late formation structures upon greenstones are examined. Large stratigraphy thicknesses are explained.

Broad-area detection of structural irregularities in composites using fibre Bragg gratings

NASA Astrophysics Data System (ADS)

Davis, Claire E.; Norman, Patrick; Moss, Scott; Ratcliffe, Colin; Crane, Roger

2010-04-01

The Structural Irregularity and Damage Evaluation Routine (SIDER) is a broadband vibration-based technique that uses features in complex curvature operating shapes to locate damage and other areas with structural stiffness variations. It is designed for the inspection of large-scale composite structures not amenable to more conventional inspection methods. The current SIDER methodology relies on impact excitation at a series of grid points on the structure and records the response using a small number of accelerometers to determine the operational curvature shapes. This paper reports on a modification to the SIDER technique whereby the acceleration measurements are replaced with in-plane strain measurements using Fibre Bragg Gratings (FBGs). One of the major challenges associated with using Bragg gratings for this type of response measurement is that the strains induced by structural vibrations tend to be low, particularly at higher frequencies. This paper also reports on the development of an intensity-based, swept wavelength interrogation system to facilitate these measurements. The modified SIDER system was evaluated on an E-glass/vinyl ester composite test beam containing a machined notch. The measurements accurately detected the presence and location of the notch. The distributive capacity of FBGs means that these sensors have the potential to replace the excitation grid with a measurement grid, allowing for single point or environmental excitation. The spatially separated measurements of strain can be used to provide the curvature shapes directly. This change in approach could potentially transition SIDER from an interval-based, broad-area inspection tool to an in-service structural health monitoring system.

Determination of Slake Durability Index (Sdi) Values on Different Shape of Laminated Marl Samples

NASA Astrophysics Data System (ADS)

Ankara, Hüseyin; Çiçek, Fatma; Talha Deniz, İsmail; Uçak, Emre; Yerel Kandemir, Süheyla

2016-10-01

The slake durability index (SDI) test is widely used to determine the disintegration characteristic of the weak and clay-bearing rocks in geo-engineering problems. However, due to the different shapes of sample pieces, such as, irregular shapes displayed mechanical breakages in the slaking process, the SDI test has some limitations that affect the index values. In addition, shape and surface roughness of laminated marl samples have a severe influence on the SDI. In this study, a new sample preparation method called Pasha Method was used to prepare spherical specimens from the laminated marl collected from Seyitomer collar (SLI). Moreover the SDI tests were performed on equal size and weight specimens: three sets with different shapes were used. The three different sets were prepared as the test samples which had sphere shape, parallel to the layers in irregular shape, and vertical to the layers in irregular shape. Index values were determined for the three different sets subjected to the SDI test for 4 cycles. The index values at the end of fourth cycle were found to be 98.43, 98.39 and 97.20 %, respectively. As seen, the index values of the sphere sample set were found to be higher than irregular sample sets.

Hubble Paints a Spattering of Blue

NASA Image and Video Library

2014-09-12

Far beyond the stars in the constellation of Leo (The Lion) is irregular galaxy IC 559. IC 559 is not your everyday galaxy. With its irregular shape and bright blue spattering of stars, it is a fascinating galactic anomaly. It may look like sparse cloud, but it is in fact full of gas and dust which is spawning new stars. Discovered in 1893, IC 559 lacks the symmetrical spiral appearance of some of its galactic peers and not does not conform to a regular shape. It is actually classified as a “type Sm” galaxy — an irregular galaxy with some evidence for a spiral structure. Irregular galaxies make up about a quarter of all known galaxies and do not fall into any of the regular classes of the Hubble sequence. Most of these uniquely shaped galaxies were not always so — IC 559 may have once been a conventional spiral galaxy that was then distorted and twisted by the gravity of a nearby cosmic companion. This image, captured by the NASA/ESA Hubble Space Telescope’s Wide Field Camera 3, combines a wide range of wavelengths spanning the ultraviolet, optical, and infrared parts of the spectrum. Image credit: ESA/Hubble, NASA, D. Calzetti (UMass) and the LEGUS Team NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Manipulating the transmission through valve structure composed of zero-index metamaterial

NASA Astrophysics Data System (ADS)

Wang, Yongxing; Sun, Zhouzhou; Xu, Ping

2017-11-01

We propose a valve structure composed of zero-index metamaterial to manipulate the electromagnetic wave conveniently and effectively through regulating the phase of reflected waves. Both the structure and characteristics of zero-index metamaterial need not to be changed when manipulating the transmission, which maintains the stability of zero-index metamaterial. Moreover, the good performance of tuning the electromagnetic wave is not limited by the shape and size of our proposed structure. By using our proposed valve structure, we demonstrate the realization of the tunable curved anisotropic ɛ-near-zero material waveguide with irregular shape, arbitrarily sized isotropic ɛ-near-zero material waveguide with high transmittance and the curved isotropic impedance matched ɛ-near-zero material waveguide without polarization limitations.

Uniform irradiation of irregularly shaped cavities for photodynamic therapy.

PubMed

Rem, A I; van Gemert, M J; van der Meulen, F W; Gijsbers, G H; Beek, J F

1997-03-01

It is difficult to achieve a uniform light distribution in irregularly shaped cavities. We have conducted a study on the use of hollow 'integrating' moulds for more uniform light delivery of photodynamic therapy in irregularly shaped cavities such as the oral cavity. Simple geometries such as a cubical box, a sphere, a cylinder and a 'bottle-neck' geometry have been investigated experimentally and the results have been compared with computed light distributions obtained using the 'radiosity method'. A high reflection coefficient of the mould and the best uniform direct irradiance possible on the inside of the mould were found to be important determinants for achieving a uniform light distribution.

Alignment of Irregular Grains by Mechanical Torques

NASA Astrophysics Data System (ADS)

Hoang, Thiem; Cho, Jungyeon; Lazarian, A.

2018-01-01

We study the alignment of irregular dust grains by mechanical torques due to the drift of grains through the ambient gas. We first calculate mechanical alignment torques (MATs) resulting from specular reflection of gas atoms for seven irregular shapes: one shape of mirror symmetry, three highly irregular shapes (HIS), and three weakly irregular shapes (WIS). We find that the grain with mirror symmetry experiences negligible MATs due to its mirror-symmetry geometry. Three HIS can produce strong MATs, which exhibit some generic properties as radiative torques (RATs), while three WIS produce less efficient MATs. We then study grain alignment by MATs for the different angles between the drift velocity and the ambient magnetic field, for paramagnetic and superparamagnetic grains assuming efficient internal relaxation. We find that for HIS grains, MATs can align subsonically drifting grains in the same way as RATs, with low-J and high-J attractors. For supersonic drift, MATs can align grains with low-J and high-J attractors, analogous to RAT alignment by anisotropic radiation. We also show that the joint action of MATs and magnetic torques in grains with iron inclusions can lead to perfect MAT alignment. Our results point out the potential importance of MAT alignment for HIS grains predicted by the analytical model of Lazarian & Hoang, although more theoretical and observational studies are required due to uncertainty in the shape of interstellar grains. We outline astrophysical environments where MAT alignment is potentially important.

Three-Dimensional Visualization and Imaging of the Entry Tear and Intimal Flap of Aortic Dissection Using CT Virtual Intravascular Endoscopy

PubMed Central

Li, Gang; Ma, Xiangxing; Wang, Qing; Yu, Dexin

2016-01-01

Aims Conventional computed tomography (CT) approaches provides limited visualization of the entire endoluminal changes of aortic dissection (AD), which is essential for its treatment. As an important supplement, three-dimensional CT virtual intravascular endoscopy (VIE) can show relevant details. This study aims to determine the value of VIE in displaying the entry tear and intimal flap of AD. Methods and Results Among 127 consecutive symptomatic patients with suspected AD who underwent CT angiography (CTA), 84 subjects were confirmed to have AD and were included in the study. Conventional CT and VIE images were observed and evaluated. From the 92 entry tears revealed via conventional CT, 88 (95.7%) tears appeared on VIE with round (n = 26), slit-shaped (n = 9), or irregular (n = 53) shapes, whereas the intimal flaps were sheetlike (n = 34), tubular (n = 34), wavelike (n = 13), or irregular (n = 7) in shape. The VIE also showed the spatial relationship between the torn flap and adjacent structures. Among 58 entry tears with multiple-line type flap shown on conventional CT, 41 (70.7%) appeared with an irregular shape on VIE, whereas among 30 tears with single-line type flap, 17 (56.7%) appeared as round or slit-shaped on VIE. These results demonstrated a significant difference (P < 0.05). The poor display of tears on VIE was related to the low CT attenuation values in lumen or in neighboring artifacts (P < 0.01). Conclusion CT VIE presents the complete configurations and details of the intimal tears and flaps of AD better than conventional CT approaches. Accordingly, it should be recommended as a necessary assessment tool for endovascular therapy and as part of strategy planning in pre-surgical patients. PMID:27760170

An Impact Ejecta Behavior Model for Small, Irregular Bodies

NASA Technical Reports Server (NTRS)

Richardson, J. E.; Melosh, H. J.; Greenberg, R.

2003-01-01

In recent years, spacecraft observations of asteroids 951 Gaspra, 243 Ida, 253 Mathilde, and 433 Eros have shown the overriding dominance of impact processes with regard to the structure and surface morphology of these small, irregular bodies. In particular, impact ejecta play an important role in regolith formation, ranging from small particles to large blocks, as well as surface feature modification and obscuration. To investigate these processes, a numerical model has been developed based upon the impact ejecta scaling laws provided by Housen, Schmidt, and Holsapple, and modified to more properly simulate the late-stage ejection velocities and ejecta plume shape changes (ejection angle variations) shown in impact cratering experiments. A target strength parameter has also been added to allow the simulation of strength-dominated cratering events in addition to the more familiar gravity-dominated cratering events. The result is a dynamical simulation which models -- via tracer particles -- the ejecta plume behavior, ejecta blanket placement, and impact crater area resulting from a specified impact on an irregularly shaped target body, which is modeled in 3-dimensional polygon fashion. This target body can be placed in a simple rotation state about one of its principal axes, with the impact site and projectile/target parameters selected by the user. The gravitational force from the irregular target body (on each tracer particle) is determined using the polygonized surface (polyhedron) gravity technique developed by Werner.

Two Growth Modes of Graphitic Carbon Nanofibers with Herring-Bone Structure

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

Merkulov, Igor A; Melechko, Anatoli Vasilievich; Wells, Jack C

2005-01-01

A simple mathematical model of the carbon nanofiber catalytic growth process is presented. Two major types of the fiber-catalyst interface shapes have been identified and described having qualitatively different structure in the center of a nanofiber. Presently, we discuss that the appearance of the irregular structure in the nanofiber central area is a result of curved-interface-growth kinematics. We suggest the method to determine the phenomenological parameters of the developed model from experimental data.

Two growth modes of graphitic carbon nanofibers with herring-bone structure

NASA Astrophysics Data System (ADS)

Merkulov, I. A.; Meleshko, A. V.; Wells, J. C.; Cui, H.; Merkulov, V. I.; Simpson, M. L.; Lowndes, D. H.

2005-07-01

A simple mathematical model of the carbon nanofiber catalytic growth process is presented. Two major types of the fiber-catalyst interface shapes have been identified and described having qualitatively different structure in the center of a nanofiber. Presently, we discuss that the appearance of the irregular structure in the nanofiber central area is a result of curved-interface-growth kinematics. We suggest the method to determine the phenomenological parameters of the developed model from experimental data.

Influence of initial stress, irregularity and heterogeneity on Love-type wave propagation in double pre-stressed irregular layers lying over a pre-stressed half-space

NASA Astrophysics Data System (ADS)

Singh, Abhishek Kumar; Das, Amrita; Parween, Zeenat; Chattopadhyay, Amares

2015-10-01

The present paper deals with the propagation of Love-type wave in an initially stressed irregular vertically heterogeneous layer lying over an initially stressed isotropic layer and an initially stressed isotropic half-space. Two different types of irregularities, viz., rectangular and parabolic, are considered at the interface of uppermost initially stressed heterogeneous layer and intermediate initially stressed isotropic layer. Dispersion equations are obtained in closed form for both cases of irregularities, distinctly. The effect of size and shape of irregularity, horizontal compressive initial stress, horizontal tensile initial stress, heterogeneity of the uppermost layer and width ratio of the layers on phase velocity of Love-type wave are the major highlights of the study. Comparative study has been made to identify the effects of different shapes of irregularity, presence of heterogeneity and initial stresses. Numerical computations have been carried out and depicted by means of graphs for the present study.

"To be or not to be in a good shape": diagnostic and clinical value of nuclear shape irregularities in thyroid and breast cancer.

PubMed

Bussolati, Gianni; Maletta, Francesca; Asioli, Sofia; Annaratone, Laura; Sapino, Anna; Marchiò, Caterina

2014-01-01

Variation in both nuclear shape and size ("pleomorphism"), coupled with changes in chromatin amount and distribution, remains the basic criteria for microscopy in a cytologic diagnosis of cancer. The biological determinants of nuclear shape irregularities are not clarified, so, rather than on the genesis of nuclear irregularities, we here focus our attention on a descriptive analysis of nuclear pleomorphism. We keep in mind that evaluation of nuclear shape as currently practiced in routine preparations is improper because it is indirectly based on the distribution of DNA as revealed by the affinity for basic dyes. Therefore, over the last years we have been using as criteria morphological features of nuclei of thyroid and breast carcinomas as determined by immunofluorescence, in situ hybridization, and 3D reconstruction. We have translated this approach to routine diagnostic pathology on tissue sections by employing immunoperoxidase staining for emerin. Direct detection of nuclear envelope irregularities by tagging nuclear membrane proteins such as lamin B and emerin has resulted in a more objective definition of the shape of the nucleus. In this review we discuss in detail methodological issues as well as diagnostic and prognostic implications provided by decoration/staining of the nuclear envelope in both thyroid and breast cancer, thus demonstrating how much it matters "to be in the right shape" when dealing with pathological diagnosis of cancer.

Unconventional maar diatreme and associated intrusions in the soft sediment-hosted Mardoux structure (Gergovie, France)

NASA Astrophysics Data System (ADS)

Valentine, Greg A.; van Wyk de Vries, Benjamin

2014-03-01

A Miocene age volcanic-hypabyssal structure comprising volcaniclastic deposits and mafic intrusions is exposed with vertical relief of ˜110 m on the side of Gergovie Plateau (Auvergne, France). Three main volcaniclastic facies are: (1) Fluidal tuff breccia composed of juvenile basalt and sediment clasts with dominantly fluidal shapes, with several combinations of basalt and sediment within individual clasts. (2) Thickly bedded lapilli tuff composed of varying proportions of fine-grained sediment derived from Oligocene-Miocene lacustrine marls and mudstones and basaltic lapilli, blocks, and bombs. (3) Planar-bedded tuff forming thin beds of fine to coarse ash-size sedimentary material and basalt clasts. Intrusive bodies in the thickly bedded lapilli tuff range from irregularly shaped and anastomosing dikes and sills of meters to tens of meters in length, to a main feeder dike that is up to ˜20 m wide, and that flares into a spoon-shaped sill at ˜100 m in diameter and 10-20 m thick in the eastern part of the structure. Volcaniclastic deposits and structural features suggest that ascending magma entrained soft, saturated sediment host material into the feeder dike and erupted fluidal magma and wet sediment via weak, Strombolian-like explosions. Host sediment and erupted material subsided to replace the extracted sediments, producing the growth subsidence structure that is similar to upper diatreme facies in typical maar diatremes but lacks evidence for explosive disruption of diatreme fill. Irregularly shaped small intrusions extended from the main feeder dike into the diatreme, and many were disaggregated due to shifting and subsidence of diatreme fill and recycled via eruption. The Mardoux structure is an "unconventional" maar diatreme in that it was produced mainly by weak explosive activity rather than by violent phreatomagmatic explosions and is an example of complex coupling between soft sediment and ascending magma.

Ingestion and Egestion of Microplastics by the Cladoceran Daphnia magna: Effects of Regular and Irregular Shaped Plastic and Sorbed Phenanthrene.

PubMed

Frydkjær, Camilla Krogh; Iversen, Niels; Roslev, Peter

2017-12-01

The presence of microplastics in aquatic ecosystems is of increasing global concern. This study investigated ingestion, egestion and acute effects of polyethylene microplastics in Daphnia magna. Fate of regular shaped microplastic beads (10-106 µm) were compared with irregular shaped microplastic fragments (10-75 µm). Daphnia magna ingested regular and irregular microplastic with uptake between 0.7 and 50 plastic particles/animal/day when exposed to microplastic concentrations of 0.0001-10 g/L. Egestion of irregular fragments was slower than that of microplastic beads. The EC50 for irregular microplastic was 0.065 g/L whereas microplastic beads were less inhibitory. The potential of microplastic to act as vector for hydrophobic pollutants was examined using [ 14 C]phenanthrene as tracer. Polyethylene microplastic sorbed less [ 14 C]phenanthrene compared to natural plankton organisms (bacteria, algae, yeast). As microplastics are much less abundant in most aquatic ecosystems compared to plankton organisms this suggests a limited role as vector for hydrophobic pollutants under current environmental conditions.

Tree branch-shaped cupric oxide for highly effective photoelectrochemical water reduction

NASA Astrophysics Data System (ADS)

Jang, Youn Jeong; Jang, Ji-Wook; Choi, Sun Hee; Kim, Jae Young; Kim, Ju Hun; Youn, Duck Hyun; Kim, Won Yong; Han, Suenghoon; Sung Lee, Jae

2015-04-01

Highly efficient tree branch-shaped CuO photocathodes are fabricated using the hybrid microwave annealing process with a silicon susceptor within 10 minutes. The unique hierarchical, one-dimensional structure provides more facile charge transport, larger surface areas, and increased crystallinity and crystal ordering with less defects compared to irregular-shaped CuO prepared by conventional thermal annealing. As a result, the photocathode fabricated with the tree branch-shaped CuO produces an unprecedently high photocurrent density of -4.4 mA cm-2 at 0 VRHE under AM 1.5 G simulated sunlight compared to -1.44 mA cm-2 observed for a photocathode fabricated by thermal annealing. It is also confirmed that stoichiometric hydrogen and oxygen are produced from photoelectrochemical water splitting on the tree branch-shaped CuO photocathode and a platinum anode.Highly efficient tree branch-shaped CuO photocathodes are fabricated using the hybrid microwave annealing process with a silicon susceptor within 10 minutes. The unique hierarchical, one-dimensional structure provides more facile charge transport, larger surface areas, and increased crystallinity and crystal ordering with less defects compared to irregular-shaped CuO prepared by conventional thermal annealing. As a result, the photocathode fabricated with the tree branch-shaped CuO produces an unprecedently high photocurrent density of -4.4 mA cm-2 at 0 VRHE under AM 1.5 G simulated sunlight compared to -1.44 mA cm-2 observed for a photocathode fabricated by thermal annealing. It is also confirmed that stoichiometric hydrogen and oxygen are produced from photoelectrochemical water splitting on the tree branch-shaped CuO photocathode and a platinum anode. Electronic supplementary information (ESI) available: The detailed schematic diagram for the HMA process, XRD results, the temperature profile during HMA, derivative XANES results, TEM images, J-V curves, lists of previously reported copper oxide photocathode, and parameters extracted from EIS. See DOI: 10.1039/c5nr00208g

78 FR 44917 - Anchorage Regulations; Port of New York

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-25

... Anchorage Ground No. 27(iii) Flynns Knoll, near Sandy Hook, NJ. The irregular shaped area of Anchorage... nautical miles wide). The irregular bowl-shaped area of Anchorage Ground No. 27(iii) Flynns Knoll is about... and property of both the anchored vessels and those operating in the area as well as provide for the...

Using Chebyshev polynomial interpolation to improve the computational efficiency of gravity models near an irregularly-shaped asteroid

NASA Astrophysics Data System (ADS)

Hu, Shou-Cun; Ji, Jiang-Hui

2017-12-01

In asteroid rendezvous missions, the dynamical environment near an asteroid’s surface should be made clear prior to launch of the mission. However, most asteroids have irregular shapes, which lower the efficiency of calculating their gravitational field by adopting the traditional polyhedral method. In this work, we propose a method to partition the space near an asteroid adaptively along three spherical coordinates and use Chebyshev polynomial interpolation to represent the gravitational acceleration in each cell. Moreover, we compare four different interpolation schemes to obtain the best precision with identical initial parameters. An error-adaptive octree division is combined to improve the interpolation precision near the surface. As an example, we take the typical irregularly-shaped near-Earth asteroid 4179 Toutatis to demonstrate the advantage of this method; as a result, we show that the efficiency can be increased by hundreds to thousands of times with our method. Our results indicate that this method can be applicable to other irregularly-shaped asteroids and can greatly improve the evaluation efficiency.

Bacteria form tellurium nanocrystals

USGS Publications Warehouse

Oremland, R.S.

2007-01-01

A team of researchers have found two bacterial species that produce tellurium oxyanions as respiratory electron acceptors for growth, leaving elemental tellurium in the form of nanoparticles. The crystals from the two organisms exhibit distinctively different structures. Bacillus selenitireducens initially forms nanorods that cluster together to form rosettes. Sulfurospirillum barnesii forms irregularly-shaped nanospheres that coalesce into larger composite aggregates.

SEGMENTATION OF MITOCHONDRIA IN ELECTRON MICROSCOPY IMAGES USING ALGEBRAIC CURVES.

PubMed

Seyedhosseini, Mojtaba; Ellisman, Mark H; Tasdizen, Tolga

2013-01-01

High-resolution microscopy techniques have been used to generate large volumes of data with enough details for understanding the complex structure of the nervous system. However, automatic techniques are required to segment cells and intracellular structures in these multi-terabyte datasets and make anatomical analysis possible on a large scale. We propose a fully automated method that exploits both shape information and regional statistics to segment irregularly shaped intracellular structures such as mitochondria in electron microscopy (EM) images. The main idea is to use algebraic curves to extract shape features together with texture features from image patches. Then, these powerful features are used to learn a random forest classifier, which can predict mitochondria locations precisely. Finally, the algebraic curves together with regional information are used to segment the mitochondria at the predicted locations. We demonstrate that our method outperforms the state-of-the-art algorithms in segmentation of mitochondria in EM images.

Single-shot three-dimensional reconstruction based on structured light line pattern

NASA Astrophysics Data System (ADS)

Wang, ZhenZhou; Yang, YongMing

2018-07-01

Reconstruction of the object by single-shot is of great importance in many applications, in which the object is moving or its shape is non-rigid and changes irregularly. In this paper, we propose a single-shot structured light 3D imaging technique that calculates the phase map from the distorted line pattern. This technique makes use of the image processing techniques to segment and cluster the projected structured light line pattern from one single captured image. The coordinates of the clustered lines are extracted to form a low-resolution phase matrix which is then transformed to full-resolution phase map by spline interpolation. The 3D shape of the object is computed from the full-resolution phase map and the 2D camera coordinates. Experimental results show that the proposed method was able to reconstruct the three-dimensional shape of the object robustly from one single image.

Thermoelastic damping effect of the micro-ring resonator with irregular mass and stiffness

NASA Astrophysics Data System (ADS)

Kim, Jung-Hwan; Kim, Ji-Hwan

2016-05-01

Fundamentally, vibration characteristic is a main factor for the stability of structures. In this regard, the irregularity of mass and stiffness distributions for the structure have been an interesting issue for many years. Recently, the Micro Electro Mechanical Systems (MEMS) are developed for various applications such as gyro sensors. In the present work, in-plane vibration of micro-ring structure with multiple finite-sized imperfections is investigated. Then, the unbalance of the structure is represented using Heaviside Step Function for the inextensional modeling of the ring. Also, thermoelastic damping (TED) due to internal friction is studied based on Fourier's one-dimensional heat conduction equation using Laplace Transform. To obtain the quality-factors (Q-factors) for imperfect micro-ring, analytical solutions are calculated from governing equations of motion with TED. And then, the natural frequencies and the Q-factors are observed to separate into lower and higher modes. Additionally, the vibration mode shapes are presented, and the frequency trimming concept due to attached imperfections is investigated.

Toxicological effects of irregularly shaped and spherical microplastics in a marine teleost, the sheepshead minnow (Cyprinodon variegatus).

PubMed

Choi, Jin Soo; Jung, Youn-Joo; Hong, Nam-Hui; Hong, Sang Hee; Park, June-Woo

2018-04-01

The increasing global contamination of plastics in marine environments is raising public concerns about the potential hazards of microplastics to environmental and human health. Microplastics formed by the breakdown of larger plastics are typically irregular in shape. The objective of this study was to compare the effects of spherical or irregular shapes of microplastics on changes in organ distribution, swimming behaviors, gene expression, and enzyme activities in sheepshead minnow (Cyprinodon variegatus). Both types of microplastics accumulated in the digestive system, causing intestinal distention. However, when compared to spherical microplastics, irregular microplastics decreased swimming behavior (i.e., total distance travelled and maximum velocity) of sheepshead minnow. Both microplastics generated cellular reactive oxygen species (ROS), while ROS-related molecular changes (i.e., transcriptional and enzymatic characteristics) differed. This study provides toxicological insights into the impacts of environmentally relevant (fragmented) microplastics on fish and improves our understanding of the environmental effects of microplastics in the ecosystem. Copyright © 2018 Elsevier Ltd. All rights reserved.

Electromagnetic properties of material coated surfaces

NASA Technical Reports Server (NTRS)

Beard, L.; Berrie, J.; Burkholder, R.; Dominek, A.; Walton, E.; Wang, N.

1989-01-01

The electromagnetic properties of material coated conducting surfaces were investigated. The coating geometries consist of uniform layers over a planar surface, irregularly shaped formations near edges and randomly positioned, electrically small, irregularly shaped formations over a surface. Techniques to measure the scattered field and constitutive parameters from these geometries were studied. The significance of the scattered field from these geometries warrants further study.

Laser cutting of irregular shape object based on stereo vision laser galvanometric scanning system

NASA Astrophysics Data System (ADS)

Qi, Li; Zhang, Yixin; Wang, Shun; Tang, Zhiqiang; Yang, Huan; Zhang, Xuping

2015-05-01

Irregular shape objects with different 3-dimensional (3D) appearances are difficult to be shaped into customized uniform pattern by current laser machining approaches. A laser galvanometric scanning system (LGS) could be a potential candidate since it can easily achieve path-adjustable laser shaping. However, without knowing the actual 3D topography of the object, the processing result may still suffer from 3D shape distortion. It is desirable to have a versatile auxiliary tool that is capable of generating 3D-adjusted laser processing path by measuring the 3D geometry of those irregular shape objects. This paper proposed the stereo vision laser galvanometric scanning system (SLGS), which takes the advantages of both the stereo vision solution and conventional LGS system. The 3D geometry of the object obtained by the stereo cameras is used to guide the scanning galvanometers for 3D-shape-adjusted laser processing. In order to achieve precise visual-servoed laser fabrication, these two independent components are integrated through a system calibration method using plastic thin film target. The flexibility of SLGS has been experimentally demonstrated by cutting duck feathers for badminton shuttle manufacture.

The peculiar shapes of Saturn's small inner moons as evidence of mergers of similar-sized moonlets

NASA Astrophysics Data System (ADS)

Leleu, A.; Jutzi, M.; Rubin, M.

2018-05-01

The Cassini spacecraft revealed the spectacular, highly irregular shapes of the small inner moons of Saturn1, ranging from the unique 'ravioli-like' forms of Pan and Atlas2,3 to the highly elongated structure of Prometheus. Closest to Saturn, these bodies provide important clues regarding the formation process of small moons in close orbits around their host planet4, but their range of irregular shapes has not been explained yet. Here, we show that the spectrum of shapes among Saturn's small moons is a natural outcome of merging collisions among similar-sized moonlets possessing physical properties and orbits that are consistent with those of the current moons. A significant fraction of such merging collisions take place either at the first encounter or after 1-2 hit-and-run events, with impact velocities in the range of 1-5 times the mutual escape velocity. Close to head-on mergers result in flattened objects with large equatorial ridges, as observed on Atlas and Pan. With slightly more oblique impact angles, collisions lead to elongated, Prometheus-like shapes. These results suggest that the current forms of the small moons provide direct evidence of the processes at the final stages of their formation, involving pairwise encounters of moonlets of comparable size4-6. Finally, we show that this mechanism may also explain the formation of Iapetus' equatorial ridge7, as well as its oblate shape8.

Investigations of formation of quasi-static vortex-structures in granular bodies using DEM

NASA Astrophysics Data System (ADS)

Kozicki, Jan; Tejchman, Jacek

2017-06-01

The paper presents some two-dimensional simulation results of vortex-structures in cohesionless initially dense sand during quasi-static passive wall translation. The sand behaviour was simulated using the discrete element method (DEM). Sand grains were modelled by spheres with contact moments to approximately capture the irregular grain shape. In order to detect vortex-structures, the Helmholtz-Hodge decomposition of a flow displacement field from DEM calculations was used. This approach enabled us to distinguish both incompressibility and vorticity in the granular displacement field.

Kinetic Shapes: Analysis, Verification, and Applications.

PubMed

Handz̆ić, Ismet; Reed, Kyle B

2014-06-01

A circular shape placed on an incline will roll; similarly, an irregularly shaped object, such as the Archimedean spiral, will roll on a flat surface when a force is applied to its axle. This rolling is dependent on the specific shape and the applied force (magnitude and location). In this paper, we derive formulas that define the behavior of irregular 2D and 3D shapes on a flat plane when a weight is applied to the shape's axle. These kinetic shape (KS) formulas also define and predict shapes that exert given ground reaction forces when a known weight is applied at the axle rotation point. Three 2D KS design examples are physically verified statically with good correlation to predicted values. Motion simulations of unrestrained 2D KS yielded expected results in shape dynamics and self-stabilization. We also put forth practical application ideas and research for 2D and 3D KS such as in robotics and gait rehabilitation.

Cartography of irregularly shaped satellites

NASA Technical Reports Server (NTRS)

Batson, R. M.; Edwards, Kathleen

1987-01-01

Irregularly shaped satellites, such as Phobos and Amalthea, do not lend themselves to mapping by conventional methods because mathematical projections of their surfaces fail to convey an accurate visual impression of the landforms, and because large and irregular scale changes make their features difficult to measure on maps. A digital mapping technique has therefore been developed by which maps are compiled from digital topographic and spacecraft image files. The digital file is geometrically transformed as desired for human viewing, either on video screens or on hard copy. Digital files of this kind consist of digital images superimposed on another digital file representing the three-dimensional form of a body.

Contamination detection NDE for cleaning process inspection

NASA Technical Reports Server (NTRS)

Marinelli, W. J.; Dicristina, V.; Sonnenfroh, D.; Blair, D.

1995-01-01

In the joining of multilayer materials, and in welding, the cleanliness of the joining surface may play a large role in the quality of the resulting bond. No non-intrusive techniques are currently available for the rapid measurement of contamination on large or irregularly shaped structures prior to the joining process. An innovative technique for the measurement of contaminant levels in these structures using laser based imaging is presented. The approach uses an ultraviolet excimer laser to illuminate large and/or irregular surface areas. The UV light induces fluorescence and is scattered from the contaminants. The illuminated area is viewed by an image-intensified CCD (charge coupled device) camera interfaced to a PC-based computer. The camera measures the fluorescence and/or scattering from the contaminants for comparison with established standards. Single shot measurements of contamination levels are possible. Hence, the technique may be used for on-line NDE testing during manufacturing processes.

Study of shale reservoir nanometer-sized pores in Member 1 of Shahejie Formation in JX area, Liaozhong sag

NASA Astrophysics Data System (ADS)

Cheng, Yong; Zhang, Yu; Wen, Yiming

2018-02-01

The microscopic pore structure is the key of the shale reservoir study; however, traditional Scanning Electron Microscopy (SEM) methods cannot identify the irregular morphology caused by mechanical polishing. In this work, Scanning Electron Microscopy combined argon ion polishing technology was taken to study the characteristics of shale reservoir pores of Member 1 of Shahejie Formation (E3s1) located in JX1-1 area of Liaozhong Sag. The results show that pores between clay platelets, intraplatelet pores within clay aggregates and organic-matter pores are very rich in the area and with good pore connectivity, so these types of pores are of great significance for oil-gas exporation. Pores between clay platelets are formed by directional or semi-directional contact between edge and surface, edge and edge or surface and surface of laminated clay minerals, whose shapes are linear, mesh, and irregular with the size of 500 nm to 5 μm. The intraplatelet pores within clay aggregates are formed in the process of the transformation and compaction of clay minerals, whose shapes are usually linear with the width of 30 to 500 nm and the length of 2 to 50 μm. The organic-matter pores are from the process of the conversion from organic matters to the hydrocarbon under thermal evolution, whose shapes are gneissic, irregular, pitted and elliptical with the size of 100 nm to 2 μm. This study is of certain guiding significance to selecting target zones, evaluating resource potential and exploring & developing of shale gas in this region.

Two coffins and a funeral: early or late caspase activation determines two types of apoptosis induced by DNA damaging agents.

PubMed

Oropesa-Ávila, Manuel; de la Cruz-Ojeda, Patricia; Porcuna, Jesús; Villanueva-Paz, Marina; Fernández-Vega, Alejandro; de la Mata, Mario; de Lavera, Isabel; Rivero, Juan Miguel Suarez; Luzón-Hidalgo, Raquel; Álvarez-Córdoba, Mónica; Cotán, David; Zaderenko, Ana Paula; Cordero, Mario D; Sánchez-Alcázar, José A

2017-03-01

Cell cytoskeleton makes profound changes during apoptosis including the organization of an Apoptotic Microtubule Network (AMN). AMN forms a cortical structure which plays an important role in preserving plasma membrane integrity during apoptosis. Here, we examined the cytoskeleton rearrangements during apoptosis induced by camptothecin (CPT), a topoisomerase I inhibitor, in human H460 and porcine LLCPK-1α cells. Using fixed and living cell imaging, we showed that CPT induced two dose- and cell cycle-dependent types of apoptosis characterized by different cytoskeleton reorganizations, time-dependent caspase activation and final apoptotic cell morphology. In the one referred as "slow" (~h) or round-shaped, apoptosis was characterized by a slow contraction of the actinomyosin ring and late caspase activation. In "slow" apoptosis the γ-tubulin complexes were not disorganized and microtubules were not depolymerized at early stages. In contrast, "fast" (~min) or irregular-shaped apoptosis was characterized by early caspase activation followed by full contraction of the actinomyosin ring. In fast apoptosis γ-tubulin complexes were disorganized and microtubules were initially depolymerized. However, after actinomyosin contraction, microtubules were reformed adopting a cortical but irregular disposition near plasma membrane. In addition to distinctive cytoskeleton reorganization kinetics, round and irregular-shaped apoptosis showed different biological properties with respect to AMN maintenance, plasma membrane integrity and phagocytes response. Our results suggest that the knowledge and modulation of the type of apoptosis promoted by genotoxic agents may be important for deciding a better therapeutic option and predicting the immune response in cancer treatment.

Structural study of Bombyx mori silk fibroin during processing for regeneration

NASA Astrophysics Data System (ADS)

Ha, Sung-Won

Bombyx mori silk fibroin has excellent mechanical properties combined with flexibility, tissue compatibility, and high oxygen permeability in the wet condition. This important material should be dissolved and regenerated to be utilized as useful forms such as gel, film, fiber, powder, or non-woven. However, it has long been a problem that the regenerated fibroin materials show poor mechanical properties and brittleness. These problems were technically solved by improving a fiber processing method reported here. The regenerated fibroin fibers showed much better mechanical properties compared to the original silk fibers. This improved technique for the fiber processing of Bombyx mori silk fibroin may be used as a model system for other semi-crystalline fiber forming proteins, becoming available through biotechnology. The physical and chemical properties of the regenerated fibers were characterized by SinTechRTM tensile testing, X-ray diffraction, solid state 13C NMR spectroscopy, and SEM. Unlike synthetic polymers, the molecular weight distribution of Bombyx mori silk fibroin is mono-disperse because silk fibroin is synthesized from DNA template. Genetic studies have revealed the entire amino acid sequence of Bombyx mori silk fibroin. It is known that the crystalline silk II structure is composed of hexa-amino acid sequences, GAGAGS. However, in the amino acid sequence of Bombyx mori silk fibroin heavy chain, there are present 11 chemically irregular but evolutionarily conserved sequences with about 31 amino acid residues (irregular GT˜GT sequences). The structure and role of these irregular sequences have remained unknown. One of the most frequently appearing irregular sequences was synthesized by a peptide synthesizer. The three-dimensional structure of this irregular silk peptide was studied by the high resolution two-dimensional NMR technique. The three-dimensional structure of this peptide shows that it makes a turn or loop structure (distorted O shape), which means the proceeding backbone direction is changed 180° by this sequence. This may facilitate the beta-sheet formation of the crystal forming building blocks, GAGAGS/GY˜GY sequences, in fibroin heavy chain. It may also facilitate the solubilization of the fibroin heavy chain within the silk gland.

Agglomerates, smoke oxide particles, and carbon inclusions in condensed combustion products of an aluminized GAP-based propellant

NASA Astrophysics Data System (ADS)

Ao, Wen; Liu, Peijin; Yang, Wenjing

2016-12-01

In solid propellants, aluminum is widely used to improve the performance, however the condensed combustion products especially the large agglomerates generated from aluminum combustion significantly affect the combustion and internal flow inside the solid rocket motor. To clarify the properties of the condensed combustion products of aluminized propellants, a constant-pressure quench vessel was adopted to collect the combustion products. The morphology and chemical compositions of the collected products, were then studied by using scanning electron microscopy coupled with energy dispersive (SEM-EDS) method. Various structures have been observed in the condensed combustion products. Apart from the typical agglomerates or smoke oxide particles observed before, new structures including the smoke oxide clusters, irregular agglomerates and carbon-inclusions are discovered and investigated. Smoke oxide particles have the highest amount in the products. The highly dispersed oxide particle is spherical with very smooth surface and is on the order of 1-2 μm, but due to the high temperature and long residence time, these small particles will aggregate into smoke oxide clusters which are much larger than the initial particles. Three types of spherical agglomerates have been found. As the ambient gas temperature is much higher than the boiling point of Al2O3, the condensation layer inside which the aluminum drop is burning would evaporate quickly, which result in the fact that few "hollow agglomerates" has been found compared to "cap agglomerates" and "solid agglomerates". Irregular agglomerates usually larger than spherical agglomerates. The formation of irregular agglomerates likely happens by three stages: deformation of spherical aluminum drops; combination of particles with various shape; finally production of irregular agglomerates. EDS results show the ratio of O to Al on the surface of agglomerates is lower in comparison to smoke oxide particles. C and O account for most element compositions for all the carbon inclusions. The rough, spherical, strip shape and flake shape carbon-inclusions are believed to be derived from the degradation products of the binder or oxidizer, while the fiber silk is possibly the combustion product of fiber inside the heat insulation layer of the propellants. Images of products at different pressures reveal high pressure reduces the degree of agglomeration. The chemical compositions, size range and content of all the observed structures are given in this paper. Results of our study are expected to provide better insight in the working process of solid rocket motor.

Getting Things Sorted With Lagrangian Coherent Structures

NASA Astrophysics Data System (ADS)

Atis, Severine; Peacock, Thomas; Environmental Dynamics Laboratory Team

2014-11-01

The dispersion of a tracer in a fluid flow is influenced by the Lagrangian motion of fluid elements. Even in laminar regimes, the irregular chaotic behavior of a fluid flow can lead to effective stirring that rapidly redistributes a tracer throughout the domain. For flows with arbitrary time-dependence, the modern approach of Lagrangian Coherent Structures (LCSs) provide a method for identifying the key material lines that organize flow transport. When the advected tracer particles possess a finite size and nontrivial shape, however, their dynamics can differ markedly from passive tracers, thus affecting the dispersion phenomena. We present details of numerical simulations and laboratory experiments that investigate the behavior of finite size particles in 2-dimensional chaotic flows. We show that the shape and the size of the particles alter the underlying LCSs, facilitating segregation between tracers of different shape in the same flow field.

Effect of microstructure of nano- and micro-particle filled polymer composites on their tribo-mechanical performance

NASA Astrophysics Data System (ADS)

Devaprakasam, D.; Hatton, P. V.; Möbus, G.; Inkson, B. J.

2008-08-01

In this work we have investigated the influence of nanoscale and microscale structure on the tribo-mechanical performance and failure mechanisms of two biocompatible dental polymer composites, with different reinforcing particulates, using advanced microscopy techniques. Nano- and micro structural analysis reveals the shape, size and distribution of the particles in the composites. In the microparticle filled polymer composite (microcomposite), the particles are of irregular shape with sharp edges with non-uniform distribution in the matrix. However, in the nanoparticle filled composites (nanocomposite), filler particles are spherical in shape with uniform distribution in the matrix. From nanoindentation measurements, hardness and reduced modulus of the microcomposite were found to be heterogeneous. However, the hardness and reduced modulus of the nanocomposite were found to be homogeneous. The nanocomposite shows better tribo-mechanical performance compared to that of the microcomposite.

Neptune

NASA Image and Video Library

1999-08-08

NASA Voyager 2 obtained these images of satellite 1989N2 and revealed it to be and irregularly shaped, dark object. The satellite appeared to have several craters. The irregular outline suggests that this moon has remained cold and rigid throughout much

Characterizing neural activities evoked by manual acupuncture through spiking irregularity measures

NASA Astrophysics Data System (ADS)

Xue, Ming; Wang, Jiang; Deng, Bin; Wei, Xi-Le; Yu, Hai-Tao; Chen, Ying-Yuan

2013-09-01

The neural system characterizes information in external stimulations by different spiking patterns. In order to examine how neural spiking patterns are related to acupuncture manipulations, experiments are designed in such a way that different types of manual acupuncture (MA) manipulations are taken at the ‘Zusanli’ point of experimental rats, and the induced electrical signals in the spinal dorsal root ganglion are detected and recorded. The interspike interval (ISI) statistical histogram is fitted by the gamma distribution, which has two parameters: one is the time-dependent firing rate and the other is a shape parameter characterizing the spiking irregularities. The shape parameter is the measure of spiking irregularities and can be used to identify the type of MA manipulations. The coefficient of variation is mostly used to measure the spike time irregularity, but it overestimates the irregularity in the case of pronounced firing rate changes. However, experiments show that each acupuncture manipulation will lead to changes in the firing rate. So we combine four relatively rate-independent measures to study the irregularity of spike trains evoked by different types of MA manipulations. Results suggest that the MA manipulations possess unique spiking statistics and characteristics and can be distinguished according to the spiking irregularity measures. These studies have offered new insights into the coding processes and information transfer of acupuncture.

Damage localization by statistical evaluation of signal-processed mode shapes

NASA Astrophysics Data System (ADS)

Ulriksen, M. D.; Damkilde, L.

2015-07-01

Due to their inherent, ability to provide structural information on a local level, mode shapes and t.lieir derivatives are utilized extensively for structural damage identification. Typically, more or less advanced mathematical methods are implemented to identify damage-induced discontinuities in the spatial mode shape signals, hereby potentially facilitating damage detection and/or localization. However, by being based on distinguishing damage-induced discontinuities from other signal irregularities, an intrinsic deficiency in these methods is the high sensitivity towards measurement, noise. The present, article introduces a damage localization method which, compared to the conventional mode shape-based methods, has greatly enhanced robustness towards measurement, noise. The method is based on signal processing of spatial mode shapes by means of continuous wavelet, transformation (CWT) and subsequent, application of a generalized discrete Teager-Kaiser energy operator (GDTKEO) to identify damage-induced mode shape discontinuities. In order to evaluate whether the identified discontinuities are in fact, damage-induced, outlier analysis of principal components of the signal-processed mode shapes is conducted on the basis of T2-statistics. The proposed method is demonstrated in the context, of analytical work with a free-vibrating Euler-Bernoulli beam under noisy conditions.

Steady state temperature distribution in dermal regions of an irregular tapered shaped human limb with variable eccentricity.

PubMed

Agrawal, M; Pardasani, K R; Adlakha, N

2014-08-01

The investigators in the past have developed some models of temperature distribution in the human limb assuming it as a regular circular or elliptical tapered cylinder. But in reality the limb is not of regular tapered cylindrical shape. The radius and eccentricity are not same throughout the limb. In view of above a model of temperature distribution in the irregular tapered elliptical shaped human limb is proposed for a three dimensional steady state case in this paper. The limb is assumed to be composed of multiple cylindrical substructures with variable radius and eccentricity. The mathematical model incorporates the effect of blood mass flow rate, metabolic activity and thermal conductivity. The outer surface is exposed to the environment and appropriate boundary conditions have been framed. The finite element method has been employed to obtain the solution. The temperature profiles have been computed in the dermal layers of a human limb and used to study the effect of shape, microstructure and biophysical parameters on temperature distribution in human limbs. The proposed model is one of the most realistic model as compared to conventional models as this can be effectively employed to every regular and nonregular structures of the body with variable radius and eccentricity to study the thermal behaviour. Copyright © 2014 Elsevier Ltd. All rights reserved.

Lumpy Janus

NASA Image and Video Library

2013-07-01

The Cassini spacecraft catches a glimpse of Janus, an irregularly shaped moon. Lacking sufficient gravity to pull itself into a round shape, Janus has had its lumpy primordial shape only slightly modified by impacts since its formation.

The shape of the F-region irregularities which produce satellite scintillations Evidence for axial asymmetry.

NASA Technical Reports Server (NTRS)

Moorcroft, D. R.; Arima, K. S.

1972-01-01

Correlation analysis of three-station observations of satellite amplitude scintillations, recorded at London, Canada during the summer of 1968, have been interpreted to give information on the height, size and shape of the ionospheric irregularities. The irregularities had a mean height of 390 km, and when interpreted in terms of the usual axially-symmetric, field-aligned model, had a mean axial ratio of 6.5, and a mean dimension transverse to the magnetic field of 0.7 km. None of these parameters showed any systematic trend with geomagnetic latitude. The data for one of the passes analyzed were inconsistent with axial symmetry, and when examined in terms of a more general model, 3 of 9 passes showed evidence of irregularities which were elongated both along and transverse to the earth's magnetic field, the elongation transverse to the field tending to lie in a north-south direction.

Coupling Inductor Based Hybrid Millimeter-Wave Switch

NASA Technical Reports Server (NTRS)

Gu, Qun (Inventor); Drouin, Brian J. (Inventor); Tang, Adrian J. (Inventor); Shu, Ran (Inventor)

2017-01-01

A switch comprising a plurality of inductors and a plurality of shunt transistors is described. Each inductor can be electrically coupled between adjacent shunt transistors to form a distributed switch structure. At least two inductors in the plurality of inductors can be inductively coupled with each other. The plurality of inductors can correspond to portions of a coupling inductor, wherein the coupling inductor can have an irregular octagonal shape.

Nodal domains of a non-separable problem—the right-angled isosceles triangle

NASA Astrophysics Data System (ADS)

Aronovitch, Amit; Band, Ram; Fajman, David; Gnutzmann, Sven

2012-03-01

We study the nodal set of eigenfunctions of the Laplace operator on the right-angled isosceles triangle. A local analysis of the nodal pattern provides an algorithm for computing the number νn of nodal domains for any eigenfunction. In addition, an exact recursive formula for the number of nodal domains is found to reproduce all existing data. Eventually, we use the recursion formula to analyse a large sequence of nodal counts statistically. Our analysis shows that the distribution of nodal counts for this triangular shape has a much richer structure than the known cases of regular separable shapes or completely irregular shapes. Furthermore, we demonstrate that the nodal count sequence contains information about the periodic orbits of the corresponding classical ray dynamics.

Postoperative corneal shape changes: microincision versus small-incision coaxial cataract surgery.

PubMed

Hayashi, Ken; Yoshida, Motoaki; Hayashi, Hideyuki

2009-02-01

To compare changes in corneal topography and in regular and irregular astigmatism after coaxial clear corneal microincision cataract surgery (MICS) and after coaxial small-incision cataract surgery (SICS). Hayashi Eye Hospital, Fukuoka, Japan. Induced corneal astigmatism was determined using vector analysis. The averaged corneal shape changes and degree of irregular astigmatism were examined using videokeratography preoperatively as well as 2 days and 1, 2, 4, and 8 weeks postoperatively. One hundred twenty eyes of 60 patients scheduled for phacoemulsification were evaluated. Sixty eyes had MICS (2.00 mm), and the 60 contralateral eyes had SICS (2.65 mm). The mean induced corneal astigmatism was significantly less in the MICS group than in the SICS group (P

Gravitational perturbation of irregular bodies modeled with regular polyhedra

NASA Astrophysics Data System (ADS)

Venditti, Flaviane; Prado, Antonio

In this work the study of the dynamics around bodies with non-spherical shapes is considered. The gravitational field of an irregular body, meaning that the mass distribution is asymmetric, generates orbits around this body to perform different from a keplerian orbit. In this case, there is a perturbation on the gravitational field that must be analyzed. To know the gravitational force of an irregular object, first it is necessary to model this body, which is not an easy thing to do, considering that, usually, they are not symmetric figures. To better model the irregular objects, a combination of several geometric figures can be used, like parallelepipeds. This can be applied to asteroids, which are objects with non-spherical shapes. The disturbing force generated by these bodies can then be obtained as the sum of the force on each figure. Here the equation for the potential of a cube is considered (MacMillan, 1930), which makes it possible to have analytical results. The main idea is to build a body with several cubes, and having the gravitational potential of each cube, it is possible to obtain the total perturbation as the sum of the forces acting on each piece. This methodology can be very helpful on space missions to small bodies, because when a spacecraft is in the vicinity of an irregular body, the gravitational perturbation generated by its shape must be considered to compensate this effect.

[Morphology of gametes in sea urchins from Peter the Great Bay, Sea of Japan].

PubMed

Drozdov, A L; Vinnikova, V V

2010-01-01

The fine structure of the gametes in six sea urchin species of the Sea of Japan was studied. The spermatozoons in Strongylocentrotus nudus, S. intermedius, Echinocardium cordatum, Scaphechinus mirabilis, Sc. grizeus and Echinarachnius parma are species-specific. The conical head and symmetrically disposed ring-shape mitochondrion are common to regular sea urchin sperm cells. S. nudus is characterized by the bulb-shaped head of the zoosperm; S. intermedius, by a bullet-shaped one. The zoosperm spearhead and small amount of postacrosome material are common to irregular sea urchins; the sperm width: length ratio varies for different species, with the highest for Sc. mirabilis. The zoosperm of Sc. griseus is characterized by two lipid drops in the cell center. Asymmetrical mitochondrion disposal is usual for E. parma. Actin filaments are found in the postacrosome material in the zoosperm of cordiform sea urchins. The differences in the fine structure of zoosperm in eurybiont species Ech. cordatum inhabiting the Sea of Japan and coastal areas of the Northeast Atlantic may bear record to the complex existence of species Ech. cordatum. The fine structure of zoosperm is unique for each of the studied families, Strongylocentrotidae, Scutellidae, and Loveniidae. The eggs of all the species are characterized by vitelline and tremelloid membranes. The vitelline membrane is formed by cytoplasm protrusions; the area between them is filled with fubrillary material. The tremelloid membrane is formed by fubrillary material associated with apical parts of microvilli of the vitelline membrane. The irregular sea urchins Sc. griseus, Sc. mirabilis and E. parma are characterized by chromatophores situated in the tremelloid membrane, with the highest abundance in Sc. mirabilis.

Sol-gel optics for biomeasurements

NASA Astrophysics Data System (ADS)

Lechna-Marczynska, Monika I.; Podbielska, Halina; Ulatowska-Jarza, Agnieszka; Holowacz, Iwona; Andrzejewski, Damian

2001-10-01

Sol-gel technique is a method for producing of glass-like materials without involving a melting process. Organic compounds such as alcoholates of silicon, sodium or calcium can be used. The irregular non-crystalline network forms a gel structure where the metallic atoms are bonded to oxygen atoms. Low-temperature treatment turns this gel into an inorganic glass-like structure. There are numbers of applications of these materials that can be produced in various forms and shapes. Here, silica based sol-gel bulks and thin films optodes for biomedical applications will be presented.

Penalized likelihood and multi-objective spatial scans for the detection and inference of irregular clusters

PubMed Central

2010-01-01

Background Irregularly shaped spatial clusters are difficult to delineate. A cluster found by an algorithm often spreads through large portions of the map, impacting its geographical meaning. Penalized likelihood methods for Kulldorff's spatial scan statistics have been used to control the excessive freedom of the shape of clusters. Penalty functions based on cluster geometry and non-connectivity have been proposed recently. Another approach involves the use of a multi-objective algorithm to maximize two objectives: the spatial scan statistics and the geometric penalty function. Results & Discussion We present a novel scan statistic algorithm employing a function based on the graph topology to penalize the presence of under-populated disconnection nodes in candidate clusters, the disconnection nodes cohesion function. A disconnection node is defined as a region within a cluster, such that its removal disconnects the cluster. By applying this function, the most geographically meaningful clusters are sifted through the immense set of possible irregularly shaped candidate cluster solutions. To evaluate the statistical significance of solutions for multi-objective scans, a statistical approach based on the concept of attainment function is used. In this paper we compared different penalized likelihoods employing the geometric and non-connectivity regularity functions and the novel disconnection nodes cohesion function. We also build multi-objective scans using those three functions and compare them with the previous penalized likelihood scans. An application is presented using comprehensive state-wide data for Chagas' disease in puerperal women in Minas Gerais state, Brazil. Conclusions We show that, compared to the other single-objective algorithms, multi-objective scans present better performance, regarding power, sensitivity and positive predicted value. The multi-objective non-connectivity scan is faster and better suited for the detection of moderately irregularly shaped clusters. The multi-objective cohesion scan is most effective for the detection of highly irregularly shaped clusters. PMID:21034451

A Model Based Deconvolution Approach for Creating Surface Composition Maps of Irregularly Shaped Bodies from Limited Orbiting Nuclear Spectrometer Measurements

NASA Astrophysics Data System (ADS)

Dallmann, N. A.; Carlsten, B. E.; Stonehill, L. C.

2017-12-01

Orbiting nuclear spectrometers have contributed significantly to our understanding of the composition of solar system bodies. Gamma rays and neutrons are produced within the surfaces of bodies by impacting galactic cosmic rays (GCR) and by intrinsic radionuclide decay. Measuring the flux and energy spectrum of these products at one point in an orbit elucidates the elemental content of the area in view. Deconvolution of measurements from many spatially registered orbit points can produce detailed maps of elemental abundances. In applying these well-established techniques to small and irregularly shaped bodies like Phobos, one encounters unique challenges beyond those of a large spheroid. Polar mapping orbits are not possible for Phobos and quasistatic orbits will realize only modest inclinations unavoidably limiting surface coverage and creating North-South ambiguities in deconvolution. The irregular shape causes self-shadowing both of the body to the spectrometer but also of the body to the incoming GCR. The view angle to the surface normal as well as the distance between the surface and the spectrometer is highly irregular. These characteristics can be synthesized into a complicated and continuously changing measurement system point spread function. We have begun to explore different model-based, statistically rigorous, iterative deconvolution methods to produce elemental abundance maps for a proposed future investigation of Phobos. By incorporating the satellite orbit, the existing high accuracy shape-models of Phobos, and the spectrometer response function, a detailed and accurate system model can be constructed. Many aspects of this model formation are particularly well suited to modern graphics processing techniques and parallel processing. We will present the current status and preliminary visualizations of the Phobos measurement system model. We will also discuss different deconvolution strategies and their relative merit in statistical rigor, stability, achievable resolution, and exploitation of the irregular shape to partially resolve ambiguities. The general applicability of these new approaches to existing data sets from Mars, Mercury, and Lunar investigations will be noted.

Form drag in rivers due to small-scale natural topographic features: 2. Irregular sequences

USGS Publications Warehouse

Kean, J.W.; Smith, J.D.

2006-01-01

The size, shape, and spacing of small-scale topographic features found on the boundaries of natural streams, rivers, and floodplains can be quite variable. Consequently, a procedure for determining the form drag on irregular sequences of different-sized topographic features is essential for calculating near-boundary flows and sediment transport. A method for carrying out such calculations is developed in this paper. This method builds on the work of Kean and Smith (2006), which describes the flow field for the simpler case of a regular sequence of identical topographic features. Both approaches model topographic features as two-dimensional elements with Gaussian-shaped cross sections defined in terms of three parameters. Field measurements of bank topography are used to show that (1) the magnitude of these shape parameters can vary greatly between adjacent topographic features and (2) the variability of these shape parameters follows a lognormal distribution. Simulations using an irregular set of topographic roughness elements show that the drag on an individual element is primarily controlled by the size and shape of the feature immediately upstream and that the spatial average of the boundary shear stress over a large set of randomly ordered elements is relatively insensitive to the sequence of the elements. In addition, a method to transform the topography of irregular surfaces into an equivalently rough surface of regularly spaced, identical topographic elements also is given. The methods described in this paper can be used to improve predictions of flow resistance in rivers as well as quantify bank roughness.

Discrete dipole approximation models of chrystalline forsterite: Applications to cometary crystalline silicates

NASA Astrophysics Data System (ADS)

Lindsay, Sean Stephen

The shape, size, and composition of crystalline silicates observed in comet comae and external proto-planetary disks are indicative of the formation and evolution of the dust grains during the processes of planetary formation. In this dissertation, I present the 3 -- 40 mum absorption efficiencies( Qabs) of irregularly shaped forsterite crystals computed with the discrete dipole approximation (DDA) code DDSCAT developed by Draine and Flatau and run on the NASA Advanced Supercomputing facility Pleiades. An investigation of grain shapes ranging from spheroidal to irregular indicate that the strong spectral features from forsterite are sensitive to grain shape and are potentially degenerate with the effects of crystal solid state composition (Mg-content). The 10, 11, 18, 23, and 33.5 mum features are found to be the most crystal shape sensitive and should be avoided in determining Mg-content. The distinct spectral features for the three shape classes are connected with crystal formation environment using a condensation experiment by (Kobatake et al., 2008). The condensation experiment demonstrates that condensed forsterite crystal shapes are dependent on the condensation environmental temperature. I generate DDSCAT target analog shapes to the condensed crystal shapes. These analog shapes are represented by the three shape classes: 1) equant, 2) a, c-columns, and 3) b-shortened platelets. Each of these shape classes exhibit distinct spectral features that can be used to interpret grain shape characteristics from 8 --- 40 mum spectroscopy of astronomical objects containing crystalline silicates. Synthetic spectral energy distributions (SEDs) of the coma of Hale-Bopp at rh = 2.8 AU are generated by thermally modeling the flux contributions of 5 mineral species present in comets. The synthetic SEDs are constrained using a chi2- minimization technique. The mineral species are amorphous carbon, amorphous pyroxene, amorphous olivine, crystalline enstatite, and crystalline forsterite. Using the DDSCAT computed absorption efficiencies for a large variety of forsterite crystal shapes, which are computed for 66 grain sizes between 0.1 -- 5.0 mum, the flux contribution of irregularly shaped forsterite is computed. The forsterite flux contribution is then summed with the amorphous and crystalline enstatite contributions to generate the total synthetic SED. The DDSCAT forsterite grain shape synthetic SEDs reveal that the crystalline silicates in the coma of Hale-Bopp are irregular in shape with two distinct shape characteristics related to specific formation mechanisms: 1) equant grains with sharp ( ≲ 90°) angles between the faces, edges, and vertices that formed as high temperature condensates in the inner 1 -- 3 AU radial region of the Solar System's protoplanetary disk; and 2) c-shortened platelet shapes that likely formed from collisional processing of the crystals. The 8 -- 40 mum silicate spectral features of Hale-Bopp's coma are compared to the silicate spectral features of the comae of 17P/Holmes during 2007 outburst and 9P/Tempel 1 during the Deep Impact experiment to show that the silicate features with crystalline resonances are remarkably similar. The similarity in silicate spectral features suggests that the grain populations in the comae of these comets are similar in shape, size, and compositon. However, Hale-Bopp is a nearly isotropic comet (NIC) that dynamically came from the Oort cloud, and 17P and 9P are ecliptic comets (ECs) that dynamically came from the Scattered Disk. The different dynamical source regions yet similar silicate (amorphous and crystalline) grain populations suggest that ECs and NICs innately have similar grains and that the typically weaker silicate features of ECs are an effect of the surface grains becoming compacted with numerous perihelion passages. Hence, the differences in silicate between ECs and NICs are the result of grain structure and not grain composition. (Abstract shortened by UMI.)

Nanocrystal grain growth and device architectures for high-efficiency CdTe ink-based photovoltaics.

PubMed

Crisp, Ryan W; Panthani, Matthew G; Rance, William L; Duenow, Joel N; Parilla, Philip A; Callahan, Rebecca; Dabney, Matthew S; Berry, Joseph J; Talapin, Dmitri V; Luther, Joseph M

2014-09-23

We study the use of cadmium telluride (CdTe) nanocrystal colloids as a solution-processable "ink" for large-grain CdTe absorber layers in solar cells. The resulting grain structure and solar cell performance depend on the initial nanocrystal size, shape, and crystal structure. We find that inks of predominantly wurtzite tetrapod-shaped nanocrystals with arms ∼5.6 nm in diameter exhibit better device performance compared to inks composed of smaller tetrapods, irregular faceted nanocrystals, or spherical zincblende nanocrystals despite the fact that the final sintered film has a zincblende crystal structure. Five different working device architectures were investigated. The indium tin oxide (ITO)/CdTe/zinc oxide structure leads to our best performing device architecture (with efficiency >11%) compared to others including two structures with a cadmium sulfide (CdS) n-type layer typically used in high efficiency sublimation-grown CdTe solar cells. Moreover, devices without CdS have improved response at short wavelengths.

Application of Landscape Mosaic Technology to Complement Coral Reef Resource Mapping and Monitoring

DTIC Science & Technology

2010-10-01

irregular shapes pose a challenge for divers trying to delimit live tissue boundaries. Future improvements in the 3D representation of benthic mosaics...benthic habitats can be especially challenging when the spatial extent of injuries exceeds tens of square meters. These large injuries are often too...the impacts of severe physical disturbance on coral reefs can be especially challenging when large-scale modifications to the reef structure takes

City rats: insight from rat spatial behavior into human cognition in urban environments.

PubMed

Yaski, Osnat; Portugali, Juval; Eilam, David

2011-09-01

The structure and shape of the urban environment influence our ability to find our way about in the city. Understanding how the physical properties of the environment affect spatial behavior and cognition is therefore a necessity. However, there are inherent difficulties in empirically studying complex and large-scale urban environments. These include the need to isolate the impact of specific urban features and to acquire data on the physical activity of individuals. In the present study, we attempted to overcome the above obstacles and examine the relation between urban environments and spatial cognition by testing the spatial behavior of rats. This idea originated from the resemblance in the operative brain functions and in the mechanisms and strategies employed by humans and other animals when acquiring spatial information and establishing an internal representation, as revealed in past studies. Accordingly, we tested rats in arenas that simulated a grid urban layout (e.g. Manhattan streets) and an irregular urban layout (e.g. Jerusalem streets). We found that in the grid layout, rat movement was more structured and extended over a greater area compared with their restricted movement in the irregular layout. These movement patterns recall those of humans in respective urban environments, illustrating that the structure and shape of the environment affect spatial behavior similarly in humans and rats. Overall, testing rats in environments that simulate facets of urban environments can provide new insights into human spatial cognition in urban environments.

Man-made objects cuing in satellite imagery

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

Skurikhin, Alexei N

2009-01-01

We present a multi-scale framework for man-made structures cuing in satellite image regions. The approach is based on a hierarchical image segmentation followed by structural analysis. A hierarchical segmentation produces an image pyramid that contains a stack of irregular image partitions, represented as polygonized pixel patches, of successively reduced levels of detail (LOOs). We are jumping off from the over-segmented image represented by polygons attributed with spectral and texture information. The image is represented as a proximity graph with vertices corresponding to the polygons and edges reflecting polygon relations. This is followed by the iterative graph contraction based on Boruvka'smore » Minimum Spanning Tree (MST) construction algorithm. The graph contractions merge the patches based on their pairwise spectral and texture differences. Concurrently with the construction of the irregular image pyramid, structural analysis is done on the agglomerated patches. Man-made object cuing is based on the analysis of shape properties of the constructed patches and their spatial relations. The presented framework can be used as pre-scanning tool for wide area monitoring to quickly guide the further analysis to regions of interest.« less

Growth of surface structures correlated with structural and mechanical modifications of brass by laser-induced Si plasma ions implantation

NASA Astrophysics Data System (ADS)

Ahmad, Shahbaz; Bashir, Shazia; Rafique, M. Shahid; Yousaf, Daniel

2017-04-01

Laser-produced Si plasma is employed as an ion source for implantation on the brass substrate for its surface, structural, and mechanical modifications. Thomson parabola technique is employed for the measurement of energy and flux of Si ions using CR-39. In response to stepwise increase in number of laser pulses from 3000 to 12000, four brass substrates were implanted by laser-induced Si plasma ions of energy 290 keV at different fluxes ranging from 45 × 1012 to 75 × 1015 ions/cm2. SEM analysis reveals the formation of nano/micro-sized irregular shaped cavities and pores for the various ion fluxes for varying numbers of laser pulses from 3000 to 9000. At the maximum ion flux for 12,000 pulses, distinct and organized grains with hexagonal and irregular shaped morphology are revealed. X-ray diffractometer (XRD) analysis exhibits that a new phase of CuSi (311) is identified which confirms the implantation of Si ions in brass substrate. A significant decrease in mechanical properties of implanted brass, such as Yield Stress (YS), Ultimate Tensile Strength (UTS), and hardness, with increasing laser pulses from 3000 to 6000 is observed. However, with increasing laser pulses from 9000 to a maximum value of 12,000, an increase in mechanical properties like hardness, YS, and UTS is observed. The generation as well as annihilation of defects, recrystallization, and intermixing of Si precipitates with brass matrix is considered to be responsible for variations in surface, structural, and mechanical modifications of brass.

Light Scattering by Gaussian Particles: A Solution with Finite-Difference Time Domain Technique

NASA Technical Reports Server (NTRS)

Sun, W.; Nousiainen, T.; Fu, Q.; Loeb, N. G.; Videen, G.; Muinonen, K.

2003-01-01

The understanding of single-scattering properties of complex ice crystals has significance in atmospheric radiative transfer and remote-sensing applications. In this work, light scattering by irregularly shaped Gaussian ice crystals is studied with the finite-difference time-domain (FDTD) technique. For given sample particle shapes and size parameters in the resonance region, the scattering phase matrices and asymmetry factors are calculated. It is found that the deformation of the particle surface can significantly smooth the scattering phase functions and slightly reduce the asymmetry factors. The polarization properties of irregular ice crystals are also significantly different from those of spherical cloud particles. These FDTD results could provide a reference for approximate light-scattering models developed for irregular particle shapes and can have potential applications in developing a much simpler practical light scattering model for ice clouds angular-distribution models and for remote sensing of ice clouds and aerosols using polarized light. (copyright) 2003 Elsevier Science Ltd. All rights reserved.

Radio Aurora Explorer : Mission overview and the science objectives

NASA Astrophysics Data System (ADS)

Bahcivan, H.; Cutler, J.; Buonocore, J.; Bennett, M.

2009-12-01

Radio Aurora Explorer (RAX) is the first CubeSat mission funded by the NSF Small Satellite Program as a collaborative research of SRI International and the University of Michigan. The mission is a ground-to-space bi-static radar experiment enabling exploration of small-scale turbulent ionospheric structures in the high latitudes not accessible from the ground or space alone. The primary science objective is to understand the microphysics of plasma instabilities that lead to meter-scale plasma turbulence in the form of field-aligned irregularities of electron density between the altitudes of 80 and 400 km. The best-known radar target for the mission is the Farley-Buneman (two-stream) instability occurring in the ionospheric E region when the convection electric field exceeds a threshold of ~20 mV/m. Other targets include spiky structures associated with electrostatic ion cyclotron waves, Post-Rosenbluth, lower, and upper hybrid waves. The science objectives are (1) to determine the altitude distribution of high-latitude ionospheric irregularities as a function of the convection electric field magnitude and direction, (2) to identify the plasma waves responsible for the scattering, and (3) to determine to what extent the irregularities are field-aligned? The mission will measure for the first time the 3-D k-spectrum of the irregularities, in particular measuring their magnetic field alignment. The irregularities will be irradiated by an incoherent scatter radar (PFISR for the first experiments) and the scattered radiation will form a hallow cone-shaped radio aurora into space as illustrated in the figure below. The satellite radar receiver will the scattered signals as the satellite passes through the radio aurora. Irregularity locations will be determined using the time delay between ISR transmissions and satellite receptions. Experiments throughout the lifetime of the mission will determine irregularity intensities as a function altitude, magnetic aspect angle, and as a function of plasma parameters such as convection electric field, plasma density, and temperatures, which are measured effectively simultaneously by the ISR. In this regard, the mission is a well-controlled plasma experiment in a wall-less laboratory.

Shape evolution of a melting nonspherical particle

NASA Astrophysics Data System (ADS)

Kintea, Daniel M.; Hauk, Tobias; Roisman, Ilia V.; Tropea, Cameron

2015-09-01

In this study melting of irregular ice crystals was observed in an acoustic levitator. The evolution of the particle shape is captured using a high-speed video system. Several typical phenomena have been discovered: change of the particle shape, appearance of a capillary flow of the melted liquid on the particle surface leading to liquid collection at the particle midsection (where the interface curvature is smallest), and appearance of sharp cusps at the particle tips. No such phenomena can be observed during melting of spherical particles. An approximate theoretical model is developed which accounts for the main physical phenomena associated with melting of an irregular particle. The agreement between the theoretical predictions for the melting time, for the evolution of the particle shape, and the corresponding experimental data is rather good.

Output calculation of electron therapy at extended SSD using an improved LBR method.

PubMed

Alkhatib, Hassaan A; Gebreamlak, Wondesen T; Tedeschi, David J; Mihailidis, Dimitris; Wright, Ben W; Neglia, William J; Sobash, Philip T; Fontenot, Jonas D

2015-02-01

To calculate the output factor (OPF) of any irregularly shaped electron beam at extended SSD. Circular cutouts were prepared from 2.0 cm diameter to the maximum possible size for 15 × 15 applicator cone. In addition, two irregular cutouts were prepared. For each cutout, percentage depth dose (PDD) at the standard SSD and doses at different SSD values were measured using 6, 9, 12, and 16 MeV electron beam energies on a Varian 2100C LINAC and the distance at which the central axis electron fluence becomes independent of cutout size was determined. The measurements were repeated with an ELEKTA Synergy LINAC using 14 × 14 applicator cone and electron beam energies of 6, 9, 12, and 15 MeV. The PDD measurements were performed using a scanning system and two diodes-one for the signal and the other a stationary reference outside the tank. The doses of the circular cutouts at different SSDs were measured using PTW 0.125 cm(3) Semiflex ion-chamber and EDR2 films. The electron fluence was measured using EDR2 films. For each circular cutout, the lateral buildup ratio (LBR) was calculated from the measured PDD curve using the open applicator cone as the reference field. The effective SSD (SSDeff) of each circular cutout was calculated from the measured doses at different SSD values. Using the LBR value and the radius of the circular cutout, the corresponding lateral spread parameter [σR(z)] was calculated. Taking the cutout size dependence of σR(z) into account, the PDD curves of the irregularly shaped cutouts at the standard SSD were calculated. Using the calculated PDD curve of the irregularly shaped cutout along with the LBR and SSDeff values of the circular cutouts, the output factor of the irregularly shaped cutout at extended SSD was calculated. Finally, both the calculated PDD curves and output factor values were compared with the measured values. The improved LBR method has been generalized to calculate the output factor of electron therapy at extended SSD. The percentage difference between the calculated and the measured output factors of irregularly shaped cutouts in a clinical useful SSD region was within 2%. Similar results were obtained for all available electron energies of both Varian 2100C and ELEKTA Synergy machines.

Fine structure of the eggs of Anopheles (Anopheles) apicimacula (Diptera:Culicidae).

PubMed

Rodriguez, M H; Chávez, B; Orozco, A; Martínez-Palomo, A

1996-09-01

The eggs of Anopheles (Anopheles) apicimacula Dyar and Knab are described from scanning electron micrographs. The eggs are boat-shaped, with frills that extend ventrally along the length of the egg and surround the deck region. The ornamentation on the dorsal and lateral surfaces is formed by groups of smooth, round tubercles. The ventral surface is covered by irregularly jagged tubercles. Prominent lobed tubercles are present at the anterior and posterior ends of the deck.

Lightweight Concrete Produced Using a Two-Stage Casting Process.

PubMed

Yoon, Jin Young; Kim, Jae Hong; Hwang, Yoon Yi; Shin, Dong Kyu

2015-03-25

The type of lightweight aggregate and its volume fraction in a mix determine the density of lightweight concrete. Minimizing the density obviously requires a higher volume fraction, but this usually causes aggregates segregation in a conventional mixing process. This paper proposes a two-stage casting process to produce a lightweight concrete. This process involves placing lightweight aggregates in a frame and then filling in the remaining interstitial voids with cementitious grout. The casting process results in the lowest density of lightweight concrete, which consequently has low compressive strength. The irregularly shaped aggregates compensate for the weak point in terms of strength while the round-shape aggregates provide a strength of 20 MPa. Therefore, the proposed casting process can be applied for manufacturing non-structural elements and structural composites requiring a very low density and a strength of at most 20 MPa.

Swiveling Lathe Jaw Concept for Holding Irregular Pieces

NASA Technical Reports Server (NTRS)

David, J.

1966-01-01

Clamp holds irregularly shaped pieces in lathe chuck without damage and eliminates excessive time in selecting optimum mounting. Interchangeable jaws ride in standard jaw slots but swivel so that the jaw face bears evenly against the workpiece regardless of contour. The jaws can be used on both engine and turret lathes.

A Novel Method of Aircraft Detection Based on High-Resolution Panchromatic Optical Remote Sensing Images.

PubMed

Wang, Wensheng; Nie, Ting; Fu, Tianjiao; Ren, Jianyue; Jin, Longxu

2017-05-06

In target detection of optical remote sensing images, two main obstacles for aircraft target detection are how to extract the candidates in complex gray-scale-multi background and how to confirm the targets in case the target shapes are deformed, irregular or asymmetric, such as that caused by natural conditions (low signal-to-noise ratio, illumination condition or swaying photographing) and occlusion by surrounding objects (boarding bridge, equipment). To solve these issues, an improved active contours algorithm, namely region-scalable fitting energy based threshold (TRSF), and a corner-convex hull based segmentation algorithm (CCHS) are proposed in this paper. Firstly, the maximal variance between-cluster algorithm (Otsu's algorithm) and region-scalable fitting energy (RSF) algorithm are combined to solve the difficulty of targets extraction in complex and gray-scale-multi backgrounds. Secondly, based on inherent shapes and prominent corners, aircrafts are divided into five fragments by utilizing convex hulls and Harris corner points. Furthermore, a series of new structure features, which describe the proportion of targets part in the fragment to the whole fragment and the proportion of fragment to the whole hull, are identified to judge whether the targets are true or not. Experimental results show that TRSF algorithm could improve extraction accuracy in complex background, and that it is faster than some traditional active contours algorithms. The CCHS is effective to suppress the detection difficulties caused by the irregular shape.

Design Optimization of Irregular Cellular Structure for Additive Manufacturing

NASA Astrophysics Data System (ADS)

Song, Guo-Hua; Jing, Shi-Kai; Zhao, Fang-Lei; Wang, Ye-Dong; Xing, Hao; Zhou, Jing-Tao

2017-09-01

Irregularcellular structurehas great potential to be considered in light-weight design field. However, the research on optimizing irregular cellular structures has not yet been reporteddue to the difficulties in their modeling technology. Based on the variable density topology optimization theory, an efficient method for optimizing the topology of irregular cellular structures fabricated through additive manufacturing processes is proposed. The proposed method utilizes tangent circles to automatically generate the main outline of irregular cellular structure. The topological layoutof each cellstructure is optimized using the relative density informationobtained from the proposed modified SIMP method. A mapping relationship between cell structure and relative densityelement is builtto determine the diameter of each cell structure. The results show that the irregular cellular structure can be optimized with the proposed method. The results of simulation and experimental test are similar for irregular cellular structure, which indicate that the maximum deformation value obtained using the modified Solid Isotropic Microstructures with Penalization (SIMP) approach is lower 5.4×10-5 mm than that using the SIMP approach under the same under the same external load. The proposed research provides the instruction to design the other irregular cellular structure.

Clusters in irregular areas and lattices.

PubMed

Wieczorek, William F; Delmerico, Alan M; Rogerson, Peter A; Wong, David W S

2012-01-01

Geographic areas of different sizes and shapes of polygons that represent counts or rate data are often encountered in social, economic, health, and other information. Often political or census boundaries are used to define these areas because the information is available only for those geographies. Therefore, these types of boundaries are frequently used to define neighborhoods in spatial analyses using geographic information systems and related approaches such as multilevel models. When point data can be geocoded, it is possible to examine the impact of polygon shape on spatial statistical properties, such as clustering. We utilized point data (alcohol outlets) to examine the issue of polygon shape and size on visualization and statistical properties. The point data were allocated to regular lattices (hexagons and squares) and census areas for zip-code tabulation areas and tracts. The number of units in the lattices was set to be similar to the number of tract and zip-code areas. A spatial clustering statistic and visualization were used to assess the impact of polygon shape for zip- and tract-sized units. Results showed substantial similarities and notable differences across shape and size. The specific circumstances of a spatial analysis that aggregates points to polygons will determine the size and shape of the areal units to be used. The irregular polygons of census units may reflect underlying characteristics that could be missed by large regular lattices. Future research to examine the potential for using a combination of irregular polygons and regular lattices would be useful.

Morphology of the Physiological Apical Foramen in Maxillary and Mandibular First Molars

PubMed Central

Abarca, J.; Zaror, C.; Monardes, H.; Hermosilla, V.; Muñoz, C.; Cantin, M.

2015-01-01

SUMMARY Information regarding the anatomy of the physiological apical foramen is limited. Knowing its diameter and shapes contributes to clinical work, specifically to the cleaning and shaping of the apical third. The aim of this ex vivo study was to determine the minimum and maximum diameters and shape of the physiological apical foramen in the roots of maxillary and mandibular first molars. A descriptive study was conducted on 89 recently extracted first molars. Roots 3–5 mm from the apex were sectioned and prepared for analysis at 40× magnification. The minimum and maximum diameters of each physiological foramen were measured using the program Motic Images plus 2.0 ML. The shape of the foramina, classified as round, oval or irregular, was determined by the difference between the maximum and minimum diameters. A total of 174 physiological foramina were analyzed. The average of the minimum and maximum diameters was between 0.24–0.33 mm in maxillary first molars and between 0.25–0.33 mm in mandibular first molars. In maxillary molars, the most common shape of the foramen was oval (50%), then irregular (32%), then round (18%). In mandibular molars, the oval shape was also the most frequent (59%), followed by irregular (23%) and round (18%). The findings of this study regarding the morphology of physiological apical foramina in first molars make it easier for the operator to choose the appropriately-sized instruments to perform endodontic therapy successfully. PMID:25937698

Morphology of the Physiological Apical Foramen in Maxillary and Mandibular First Molars.

PubMed

Abarca, J; Zaror, C; Monardes, H; Hermosilla, V; Muñoz, C; Cantin, M

2014-06-01

Information regarding the anatomy of the physiological apical foramen is limited. Knowing its diameter and shapes contributes to clinical work, specifically to the cleaning and shaping of the apical third. The aim of this ex vivo study was to determine the minimum and maximum diameters and shape of the physiological apical foramen in the roots of maxillary and mandibular first molars. A descriptive study was conducted on 89 recently extracted first molars. Roots 3-5 mm from the apex were sectioned and prepared for analysis at 40× magnification. The minimum and maximum diameters of each physiological foramen were measured using the program Motic Images plus 2.0 ML. The shape of the foramina, classified as round, oval or irregular, was determined by the difference between the maximum and minimum diameters. A total of 174 physiological foramina were analyzed. The average of the minimum and maximum diameters was between 0.24-0.33 mm in maxillary first molars and between 0.25-0.33 mm in mandibular first molars. In maxillary molars, the most common shape of the foramen was oval (50%), then irregular (32%), then round (18%). In mandibular molars, the oval shape was also the most frequent (59%), followed by irregular (23%) and round (18%). The findings of this study regarding the morphology of physiological apical foramina in first molars make it easier for the operator to choose the appropriately-sized instruments to perform endodontic therapy successfully.

Early-Time HANE Simulation and Experiment

DTIC Science & Technology

1987-05-01

we suggest attacking the question of structure with target variation. Irregular structure in laboratory simulations of HANE’s can arise from...plasma instabilities even when the illuminating laser beam and target are optimized to yield a very uniform initial expansion. Irregularities ... irregular structure be purposely explored. In particular we encourage the use of a wide variety of inhomogeneous targets. Target irregularities

Fractal dimension based damage identification incorporating multi-task sparse Bayesian learning

NASA Astrophysics Data System (ADS)

Huang, Yong; Li, Hui; Wu, Stephen; Yang, Yongchao

2018-07-01

Sensitivity to damage and robustness to noise are critical requirements for the effectiveness of structural damage detection. In this study, a two-stage damage identification method based on the fractal dimension analysis and multi-task Bayesian learning is presented. The Higuchi’s fractal dimension (HFD) based damage index is first proposed, directly examining the time-frequency characteristic of local free vibration data of structures based on the irregularity sensitivity and noise robustness analysis of HFD. Katz’s fractal dimension is then presented to analyze the abrupt irregularity change of the spatial curve of the displacement mode shape along the structure. At the second stage, the multi-task sparse Bayesian learning technique is employed to infer the final damage localization vector, which borrow the dependent strength of the two fractal dimension based damage indication information and also incorporate the prior knowledge that structural damage occurs at a limited number of locations in a structure in the absence of its collapse. To validate the capability of the proposed method, a steel beam and a bridge, named Yonghe Bridge, are analyzed as illustrative examples. The damage identification results demonstrate that the proposed method is capable of localizing single and multiple damages regardless of its severity, and show superior robustness under heavy noise as well.

Visible light scattering properties of irregularly shaped silica microparticles using laser based laboratory simulations for remote sensing and medical applications

NASA Astrophysics Data System (ADS)

Boruah, Manash J.; Ahmed, Gazi A.

2018-01-01

Laser based experimental light scattering studies of irregularly shaped silica microparticles have been performed at three incident wavelengths 543.5 nm, 594.5 nm and 632.8 nm supported by laboratory based computations and 3D realistic simulations, using an indigenously fabricated light scattering setup. A comparative analysis of the computational and experimentally acquired results is done and a good agreement is found in the forward scattering lobes in all cases for each of the measured scattering parameters. This study also provides an efficient way of detecting and measuring particle size distribution for irregular micro- and nanoparticles and is highly applicable in remote sensing, atmospheric, astrophysical, and medical applications and also for finding potential health hazards in the form of inhalable and respirable small particulate matter.

Structure, photoluminescence and thermoluminescence study of a composite ZnTa2O6/ZnGa2O4 compound doped with Pr3+

NASA Astrophysics Data System (ADS)

Noto, L. L.; Shaat, S. K. K.; Poelman, D.; Dhlamini, M. S.; Mothudi, B. M.; Swart, H. C.

2016-05-01

The study of persistent luminescence is interesting for applications related to biological imaging, self-lit roads and security signs. Composite Pr-doped samples were prepared in one pot by solid chemical reaction at 1200 °C for 4 h. The X-ray diffraction patterns of the samples showed mixed phases which correspond to ZnGa2O4 and ZnTa2O6 phases. Interestingly, the secondary electron microscopy images showed that the surface morphology is composed of particles with different shapes: irregular, rhombus and rod shapes. The X-ray maps obtained using field emission scanning electron microscopy, confirmed that the irregular particles correspond to ZnTa2O6, and the rods correspond to ZnGa2O4. Red emission was observed from 1D2 → 3H4, 3P0 → 3H6, 3P0 → 3F2 and 1D2 → 3H5 transitions of Pr3+. The lifetime of the persistent luminescence was measured, and the corresponding trapping centres were investigated using thermoluminescence spectroscopy.

Lattice Boltzmann simulations of settling behaviors of irregularly shaped particles

NASA Astrophysics Data System (ADS)

Zhang, Pei; Galindo-Torres, S. A.; Tang, Hongwu; Jin, Guangqiu; Scheuermann, A.; Li, Ling

2016-06-01

We investigated the settling dynamics of irregularly shaped particles in a still fluid under a wide range of conditions with Reynolds numbers Re varying between 1 and 2000, sphericity ϕ and circularity c both greater than 0.5, and Corey shape factor (CSF) less than 1. To simulate the particle settling process, a modified lattice Boltzmann model combined with a turbulence module was adopted. This model was first validated using experimental data for particles of spherical and cubic shapes. For irregularly shaped particles, two different types of settling behaviors were observed prior to particles reaching a steady state: accelerating and accelerating-decelerating, which could be distinguished by a critical CSF value of approximately 0.7. The settling dynamics were analyzed with a focus on the projected areas and angular velocities of particles. It was found that a minor change in the starting projected area, an indicator of the initial particle orientation, would not strongly affect the settling velocity for low Re. Periodic oscillations developed for all simulated particles when Re>100 . The amplitude of these oscillations increased with Re. However, the periods were not sensitive to Re. The critical Re that defined the transition between the steady and periodically oscillating behaviors depended on the inertia tensor. In particular, the maximum eigenvalue of the inertia tensor played a major role in signaling this transition in comparison to the intermediate and minimum eigenvalues.

Electromagnetic Scattering From a Polygonal Thin Metallic Plate Using Quadrilateral Meshing

NASA Technical Reports Server (NTRS)

Deshpande, Manohar D.

2003-01-01

The problem of electromagnetic (EM) scattering from irregularly shaped, thin, metallic flat plates in free space is solved using the electric field integral equation (EFIE) approach in conjunction with the method of moments (MoM) with quadrilateral meshing. An irregularly shaped thin plate is discretized into quadrilateral patches and the unknown electric surface current over the plate is expressed in terms of proper basis functions over these patches. The basis functions for the electric surface current density that satisfy the proper boundary conditions on these quadrilateral patches are derived. The unknown surface current density on these quadrilateral patches is determined by setting up and solving the electric field integral equation by the application of the MoM. From the knowledge of the surface current density, the EM scattering from various irregularly shaped plates is determined and compared with the earlier published results. The novelty in the present approach is the use of quadrilateral patches instead of well known and often used triangular patches. The numerical results obtained using the quadrilateral patches compare favorably with measured results.

Test functions for three-dimensional control-volume mixed finite-element methods on irregular grids

USGS Publications Warehouse

Naff, R.L.; Russell, T.F.; Wilson, J.D.; ,; ,; ,; ,; ,

2000-01-01

Numerical methods based on unstructured grids, with irregular cells, usually require discrete shape functions to approximate the distribution of quantities across cells. For control-volume mixed finite-element methods, vector shape functions are used to approximate the distribution of velocities across cells and vector test functions are used to minimize the error associated with the numerical approximation scheme. For a logically cubic mesh, the lowest-order shape functions are chosen in a natural way to conserve intercell fluxes that vary linearly in logical space. Vector test functions, while somewhat restricted by the mapping into the logical reference cube, admit a wider class of possibilities. Ideally, an error minimization procedure to select the test function from an acceptable class of candidates would be the best procedure. Lacking such a procedure, we first investigate the effect of possible test functions on the pressure distribution over the control volume; specifically, we look for test functions that allow for the elimination of intermediate pressures on cell faces. From these results, we select three forms for the test function for use in a control-volume mixed method code and subject them to an error analysis for different forms of grid irregularity; errors are reported in terms of the discrete L2 norm of the velocity error. Of these three forms, one appears to produce optimal results for most forms of grid irregularity.

Effects of target shape and impact speed on the outcome of catastrophic disruptions

NASA Astrophysics Data System (ADS)

Campo~Bagatin, A.; Durda, D.; Alemañ, R.; Flynn, G.; Strait, M.; Clayton, A.; Patmore, E.

2014-07-01

Because of the propensity of previous laboratory investigations to focus on idealized spherical targets, there is a bit of ambiguity in decoupling the relative importance/influence of low speed or spherical shape in producing the 'onion shell' fragment shape outcomes found in impacts into spherical targets [1,2]. If due primarily to impact speed/energy density as suggested by [3], this could play an important role in main-belt impacts due to the presence of non-spherical targets and non-negligible probability of low-speed (i.e., below about 3-4 km/s, subsonic in rock) impacts [4]. Also, [5] and [6] suggested that the shape of targets may affect the outcome of shattering processes, both in terms of fragment shape and mass distribution. To examine explicitly the effects of target shape in impact outcomes, we chose to conduct impact experiments on both spherical and naturally-occurring irregularly-shaped basalt targets. We impacted a total of six targets (two spheres and four irregular targets). We focused on shots with impact speeds in the ˜4 to 6 km/s range by 3/16th-inch diameter Al-sphere projectiles fired at the NASA AVGR. Following each shot, the debris were recovered (>95 %) and large fragments (>0.20 g) were individually weighed, allowing us to carefully measure the mass-frequency distribution from each impact experiment. The 36 largest fragments of each shot were photographed and their largest axes accurately measured by the program ''ImageJ''. Their shortest axes were measured by means of a digital caliber. High-speed video of each impact was obtained to aid interpretation of the fragmentation mode of the targets. Images clearly show that shell-like fragments can be produced in shattering events not in the target's surface. Instead, those fragments may form around the core, well inside the target structure, independently on the target shape itself. This is a feature not reported to date. In order to understand what the bulk macro-porosity of a non-coherent set of fragments is, we gathered randomly together the fragments with weighed mass mimicking the post-shattering gravitational re-accumulation of fragments into an asteroid rubble-pile. For each set, we wrapped the fragments in a thin plastic film and measured the bulk volume by hanging and plunging the assemblage into distilled water. The volume is calculated straightforward from the density of water at the given temperature. Cumulative mass distributions are derived and exponents 0.75<β <1.2 are found for the relationship N(>m)=A m^{-β} (m is the fragment mass, A is the corresponding constant) in the stationary part of the distribution. The exponent of each distribution and the mass of each largest fragment are found to be related to the corresponding specific energy of each impact as expected [3]. The mass distributions seem to show slightly larger values of β in the case of spherical targets when comparing two sets of close specific energy impacts. However, this feature needs further sets of impact experiments to be properly investigated. As for the shapes of fragments, b/a and c/a ratios were calculated along with the shape metrics Ψ=[ c^2/(ab)]^{1/3}, F=(a-b)/(a-c) for deviation from the spherical shape and relative flatness, respectively [7,8]. The average relationship between a, b, and c axes is 1:0.7:0.4, slightly different (flatter) than reported by former investigations (1:0.7:0.5) carried on in the 70s and 80s [7]. This result is quite stable and no differences are found in average shapes among spherical and irregular targets nor for different specific energy up to a factor of ˜3. This does not mean that fragments look like triaxial ellipsoids, instead they are quite irregular but their average relative sizes are distributed very nicely as described. Finally, the study of the macro-porosities of randomly aggregated fragments shows values in the 45 to 50 % range. This result may be useful in the interpretation of small asteroids' bulk densities and in the calibration of numerical modelling of internal structures.

Mimas: Tectonic structure and geologic history

NASA Technical Reports Server (NTRS)

Croft, Steven K.

1991-01-01

Mimas, the innermost of the major saturnian satellites, occupies an important place in comparative studies of icy satellites. It is the smallest icy satellite known to have a mostly spherical shape. Smaller icy objects like Hyperion and Puck are generally irregular in shape, while larger ones like Miranda and Enceladus are spherical. Thus Mimas is near the diameter where the combination of increasing surface gravity and internal heating begin to have a significant effect on global structure. The nature and extent of endogenic surface features provide important constraints on the interior structure and history of this transitional body. The major landforms on Mimas are impact craters. Mimas has one of the most heavily cratered surfaces in the solar system. The most prominent single feature on Mimas is Herschel, an unrelaxed complex crater 130 km in diameter. The only other recognized landforms on Mimas are tectonic grooves and lineaments. Groove locations were mapped by Schenk, but without analysis of groove structures or superposition relationships. Mimas' tectonic structures are remapped here in more detail than previously has been done, as part of a general study of tectonic features on icy satellites.

Lightweight Concrete Produced Using a Two-Stage Casting Process

PubMed Central

Yoon, Jin Young; Kim, Jae Hong; Hwang, Yoon Yi; Shin, Dong Kyu

2015-01-01

The type of lightweight aggregate and its volume fraction in a mix determine the density of lightweight concrete. Minimizing the density obviously requires a higher volume fraction, but this usually causes aggregates segregation in a conventional mixing process. This paper proposes a two-stage casting process to produce a lightweight concrete. This process involves placing lightweight aggregates in a frame and then filling in the remaining interstitial voids with cementitious grout. The casting process results in the lowest density of lightweight concrete, which consequently has low compressive strength. The irregularly shaped aggregates compensate for the weak point in terms of strength while the round-shape aggregates provide a strength of 20 MPa. Therefore, the proposed casting process can be applied for manufacturing non-structural elements and structural composites requiring a very low density and a strength of at most 20 MPa. PMID:28788007

Accurate bulk density determination of irregularly shaped translucent and opaque aerogels

NASA Astrophysics Data System (ADS)

Petkov, M. P.; Jones, S. M.

2016-05-01

We present a volumetric method for accurate determination of bulk density of aerogels, calculated from extrapolated weight of the dry pure solid and volume estimates based on the Archimedes' principle of volume displacement, using packed 100 μm-sized monodispersed glass spheres as a "quasi-fluid" media. Hard particle packing theory is invoked to demonstrate the reproducibility of the apparent density of the quasi-fluid. Accuracy rivaling that of the refractive index method is demonstrated for both translucent and opaque aerogels with different absorptive properties, as well as for aerogels with regular and irregular shapes.

Study of Various Slanted Air-Gap Structures of Interior Permanent Magnet Synchronous Motor with Brushless Field Excitation

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

Tolbert, Leon M; Lee, Seong T

2010-01-01

This paper shows how to maximize the effect of the slanted air-gap structure of an interior permanent magnet synchronous motor with brushless field excitation (BFE) for application in a hybrid electric vehicle. The BFE structure offers high torque density at low speed and weakened flux at high speed. The unique slanted air-gap is intended to increase the output torque of the machine as well as to maximize the ratio of the back-emf of a machine that is controllable by BFE. This irregularly shaped air-gap makes a flux barrier along the d-axis flux path and decreases the d-axis inductance; as amore » result, the reluctance torque of the machine is much higher than a uniform air-gap machine, and so is the output torque. Also, the machine achieves a higher ratio of the magnitude of controllable back-emf. The determination of the slanted shape was performed by using magnetic equivalent circuit analysis and finite element analysis (FEA).« less

Confined semiflexible polymers suppress fluctuations of soft membrane tubes.

PubMed

Mirzaeifard, Sina; Abel, Steven M

2016-02-14

We use Monte Carlo computer simulations to investigate tubular membrane structures with and without semiflexible polymers confined inside. At small values of membrane bending rigidity, empty fluid and non-fluid membrane tubes exhibit markedly different behavior, with fluid membranes adopting irregular, highly fluctuating shapes and non-fluid membranes maintaining extended tube-like structures. Fluid membranes, unlike non-fluid membranes, exhibit a local maximum in specific heat as their bending rigidity increases. The peak is coincident with a transition to extended tube-like structures. We further find that confining a semiflexible polymer within a fluid membrane tube reduces the specific heat of the membrane, which is a consequence of suppressed membrane shape fluctuations. Polymers with a sufficiently large persistence length can significantly deform the membrane tube, with long polymers leading to localized bulges in the membrane that accommodate regions in which the polymer forms loops. Analytical calculations of the energies of idealized polymer-membrane configurations provide additional insight into the formation of polymer-induced membrane deformations.

Arsenate adsorption on three types of granular schwertmannite.

PubMed

Dou, Xiaomin; Mohan, Dinesh; Pittman, Charles U

2013-06-01

Schwertmannite was synthesized on a 2 m(3)-scale and fabricated to irregular, cylindrical and spherical shape granules using drum granulation, extrusion and spray coating, respectively. The granules were systematically evaluated for As(V) removal from drinking water in terms of both performance and safety. The irregular and cylindrical shape granules (IS and CS) had larger schwertmannite loadings, higher porosity, more abundant pore structure and larger micropore volumes than those with a spherical shape (SS). As(V) adsorption kinetics on IS, CS and SS schwertmannite granules followed a pseudo-second order rate equation and two-stages of intraparticle diffusion. The rate parameters were in an order of IS > CS > SS granules. The faster uptake kinetics of the IS granules was due to their largest pore volume and interparticle porosity. Furthermore, adsorption capacities of 34, 21 and 5 mg/g, for IS, CS and SS granular schwertmannite samples were achieved at an initial As(V) concentration of 20 mg/L and adsorbent dose of 0.5 g/L. IS and CS samples performed much better over a wide pH range versus SS samples. Except for humic acid, PO4(3-) and SiO4(4-) did not inhibit As(V) adsorption on IS and CS granular specimens. SS samples worked poorly even in the absence or presence of co-existing anions. Regeneration was achieved using 0.1 M NaOH. The recycled IS and CS granular specimens can be used for 4 different cycles with no or nominal loss of adsorption capacity. Column experiments were also conducted. The IS, CS and SS granular specimens treated 8100, 4200 and 120 bed volumes (BVs) of contaminated water. No heavy metals leached from the packed granular adsorbent and appeared in the column effluent. Furthermore, the toxicity characteristic leaching procedure (TCLP) showed that the spent IS and CS granules were inert and could safely be disposed of in landfills. In short, irregular-shaped granules (IS) fabricated by drum granulation is a good candidate for arsenic removal from drinking water with a high future application potential. Copyright © 2013 Elsevier Ltd. All rights reserved.

Geometrical frustration yields fibre formation in self-assembly

NASA Astrophysics Data System (ADS)

Lenz, Martin; Witten, Thomas A.

2017-11-01

Controlling the self-assembly of supramolecular structures is vital for living cells, and a central challenge for engineering at the nano- and microscales. Nevertheless, even particles without optimized shapes can robustly form well-defined morphologies. This is the case in numerous medical conditions where normally soluble proteins aggregate into fibres. Beyond the diversity of molecular mechanisms involved, we propose that fibres generically arise from the aggregation of irregular particles with short-range interactions. Using a minimal model of ill-fitting, sticky particles, we demonstrate robust fibre formation for a variety of particle shapes and aggregation conditions. Geometrical frustration plays a crucial role in this process, and accounts for the range of parameters in which fibres form as well as for their metastable character.

Improving whole brain structural MRI at 4.7 Tesla using 4 irregularly shaped receiver coils.

PubMed

Carmichael, David W; Thomas, David L; De Vita, Enrico; Fernández-Seara, Maria A; Chhina, Navjeet; Cooper, Mark; Sunderland, Colin; Randell, Chris; Turner, Robert; Ordidge, Roger J

2006-09-01

Both higher magnetic field strengths (> or =3 T) and multiple receiver "array coils" can provide increased signal-to-noise ratio (SNR) for MRI. This increase in SNR can be used to obtain images with higher resolution, enabling better visualisation of structures within the human brain. However, high field strength systems also suffer from increased B(1) non-uniformity and increased power deposition, reaching specific absorption rate (SAR) limits more quickly. For these problems to be mitigated, a careful choice of both the pulse sequence design and transmit RF coil is required. This paper describes the use of a prototype array coil consisting of 4 irregularly shaped coils within a standard configuration for neuroimaging at 4.7 T (a head transmit/receive volume coil to minimise SAR and a head gradient insert for maximum gradient performance). With a fast spin echo (FSE) pulse sequence optimised for 4.7 T, this provides dramatically increased quality and resolution over a large brain volume. Using the array coil, a SNR improvement relative to the volume coil of 1-1.5 times in central brain areas and 2-3 times in cortical regions was obtained. Array coil images with a resolution of 352 x 352 x 2000 mum had a SNR of 16.0 to 26.2 in central regions and 19.9 to 34.8 in cortical areas. Such images easily demonstrate cortical myeloarchitecture, while still covering most of the brain in a approximately 12 min scan.

Calculating electronic tunnel currents in networks of disordered irregularly shaped nanoparticles by mapping networks to arrays of parallel nonlinear resistors

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

Aghili Yajadda, Mir Massoud

2014-10-21

We have shown both theoretically and experimentally that tunnel currents in networks of disordered irregularly shaped nanoparticles (NPs) can be calculated by considering the networks as arrays of parallel nonlinear resistors. Each resistor is described by a one-dimensional or a two-dimensional array of equal size nanoparticles that the tunnel junction gaps between nanoparticles in each resistor is assumed to be equal. The number of tunnel junctions between two contact electrodes and the tunnel junction gaps between nanoparticles are found to be functions of Coulomb blockade energies. In addition, the tunnel barriers between nanoparticles were considered to be tilted at highmore » voltages. Furthermore, the role of thermal expansion coefficient of the tunnel junction gaps on the tunnel current is taken into account. The model calculations fit very well to the experimental data of a network of disordered gold nanoparticles, a forest of multi-wall carbon nanotubes, and a network of few-layer graphene nanoplates over a wide temperature range (5-300 K) at low and high DC bias voltages (0.001 mV–50 V). Our investigations indicate, although electron cotunneling in networks of disordered irregularly shaped NPs may occur, non-Arrhenius behavior at low temperatures cannot be described by the cotunneling model due to size distribution in the networks and irregular shape of nanoparticles. Non-Arrhenius behavior of the samples at zero bias voltage limit was attributed to the disorder in the samples. Unlike the electron cotunneling model, we found that the crossover from Arrhenius to non-Arrhenius behavior occurs at two temperatures, one at a high temperature and the other at a low temperature.« less

Shape‐Controlled, Self‐Wrapped Carbon Nanotube 3D Electronics

PubMed Central

Wang, Huiliang; Wang, Yanming; Tee, Benjamin C.‐K.; Kim, Kwanpyo; Lopez, Jeffrey; Cai, Wei

2015-01-01

The mechanical flexibility and structural softness of ultrathin devices based on organic thin films and low‐dimensional nanomaterials have enabled a wide range of applications including flexible display, artificial skin, and health monitoring devices. However, both living systems and inanimate systems that are encountered in daily lives are all 3D. It is therefore desirable to either create freestanding electronics in a 3D form or to incorporate electronics onto 3D objects. Here, a technique is reported to utilize shape‐memory polymers together with carbon nanotube flexible electronics to achieve this goal. Temperature‐assisted shape control of these freestanding electronics in a programmable manner is demonstrated, with theoretical analysis for understanding the shape evolution. The shape control process can be executed with prepatterned heaters, desirable for 3D shape formation in an enclosed environment. The incorporation of carbon nanotube transistors, gas sensors, temperature sensors, and memory devices that are capable of self‐wrapping onto any irregular shaped‐objects without degradations in device performance is demonstrated. PMID:27980972

An efficient algorithm for global periodic orbits generation near irregular-shaped asteroids

NASA Astrophysics Data System (ADS)

Shang, Haibin; Wu, Xiaoyu; Ren, Yuan; Shan, Jinjun

2017-07-01

Periodic orbits (POs) play an important role in understanding dynamical behaviors around natural celestial bodies. In this study, an efficient algorithm was presented to generate the global POs around irregular-shaped uniformly rotating asteroids. The algorithm was performed in three steps, namely global search, local refinement, and model continuation. First, a mascon model with a low number of particles and optimized mass distribution was constructed to remodel the exterior gravitational potential of the asteroid. Using this model, a multi-start differential evolution enhanced with a deflection strategy with strong global exploration and bypassing abilities was adopted. This algorithm can be regarded as a search engine to find multiple globally optimal regions in which potential POs were located. This was followed by applying a differential correction to locally refine global search solutions and generate the accurate POs in the mascon model in which an analytical Jacobian matrix was derived to improve convergence. Finally, the concept of numerical model continuation was introduced and used to convert the POs from the mascon model into a high-fidelity polyhedron model by sequentially correcting the initial states. The efficiency of the proposed algorithm was substantiated by computing the global POs around an elongated shoe-shaped asteroid 433 Eros. Various global POs with different topological structures in the configuration space were successfully located. Specifically, the proposed algorithm was generic and could be conveniently extended to explore periodic motions in other gravitational systems.

Morphologically controlled synthesis of ferric oxide nano/micro particles and their catalytic application in dry and wet media: a new approach.

PubMed

Janjua, Muhammad Ramzan Saeed Ashraf; Jamil, Saba; Jahan, Nazish; Khan, Shanza Rauf; Mirza, Saima

2017-05-31

Morphologically controlled synthesis of ferric oxide nano/micro particles has been carried out by using solvothermal route. Structural characterization displays that the predominant morphologies are porous hollow spheres, microspheres, micro rectangular platelets, octahedral and irregular shaped particles. It is also observed that solvent has significant effect on morphology such as shape and size of the particles. All the morphologies obtained by using different solvents are nearly uniform with narrow size distribution range. The values of full width at half maxima (FWHM) of all the products were calculated to compare their size distribution. The FWHM value varies with size of the particles for example small size particles show polydispersity whereas large size particles have shown monodispersity. The size of particles increases with decrease in polarity of the solvent whereas their shape changes from spherical to rectangular/irregular with decrease in polarity of the solvent. The catalytic activities of all the products were investigated for both dry and wet processes such as thermal decomposition of ammonium per chlorate (AP) and reduction of 4-nitrophenol in aqueous media. The results indicate that each product has a tendency to act as a catalyst. The porous hollow spheres decrease the thermal decomposition temperature of AP by 140 °C and octahedral Fe 3 O 4 particles decrease the decomposition temperature by 30 °C. The value of apparent rate constant (k app ) of reduction of 4-NP has also been calculated.

A Novel Method of Aircraft Detection Based on High-Resolution Panchromatic Optical Remote Sensing Images

PubMed Central

Wang, Wensheng; Nie, Ting; Fu, Tianjiao; Ren, Jianyue; Jin, Longxu

2017-01-01

In target detection of optical remote sensing images, two main obstacles for aircraft target detection are how to extract the candidates in complex gray-scale-multi background and how to confirm the targets in case the target shapes are deformed, irregular or asymmetric, such as that caused by natural conditions (low signal-to-noise ratio, illumination condition or swaying photographing) and occlusion by surrounding objects (boarding bridge, equipment). To solve these issues, an improved active contours algorithm, namely region-scalable fitting energy based threshold (TRSF), and a corner-convex hull based segmentation algorithm (CCHS) are proposed in this paper. Firstly, the maximal variance between-cluster algorithm (Otsu’s algorithm) and region-scalable fitting energy (RSF) algorithm are combined to solve the difficulty of targets extraction in complex and gray-scale-multi backgrounds. Secondly, based on inherent shapes and prominent corners, aircrafts are divided into five fragments by utilizing convex hulls and Harris corner points. Furthermore, a series of new structure features, which describe the proportion of targets part in the fragment to the whole fragment and the proportion of fragment to the whole hull, are identified to judge whether the targets are true or not. Experimental results show that TRSF algorithm could improve extraction accuracy in complex background, and that it is faster than some traditional active contours algorithms. The CCHS is effective to suppress the detection difficulties caused by the irregular shape. PMID:28481260

Controllable growth of shaped graphene domains by atmospheric pressure chemical vapour deposition

NASA Astrophysics Data System (ADS)

Fan, Lili; Li, Zhen; Li, Xiao; Wang, Kunlin; Zhong, Minlin; Wei, Jinquan; Wu, Dehai; Zhu, Hongwei

2011-12-01

Graphene domains in different shapes have been grown on copper substrates via atmospheric pressure chemical vapour deposition by controlling the growth process parameters. Under stabilized conditions, graphene domains tend to be six-fold symmetric hexagons under low flow rate methane with some domains in an irregular hexagonal shape. After further varying the growth duration, methane flow rate, and temperature, graphene domains have developed shapes from hexagon to shovel and dendrite. Two connecting modes, through overlap and merging of adjacent graphene domains, are proposed.Graphene domains in different shapes have been grown on copper substrates via atmospheric pressure chemical vapour deposition by controlling the growth process parameters. Under stabilized conditions, graphene domains tend to be six-fold symmetric hexagons under low flow rate methane with some domains in an irregular hexagonal shape. After further varying the growth duration, methane flow rate, and temperature, graphene domains have developed shapes from hexagon to shovel and dendrite. Two connecting modes, through overlap and merging of adjacent graphene domains, are proposed. Electronic supplementary information (ESI) available: Schematics of CVD setups for graphene growth, Raman spectra and SEM images. See DOI: 10.1039/c1nr11480h

Dynamic Reorganization of the Cytoskeleton during Apoptosis: The Two Coffins Hypothesis.

PubMed

Povea-Cabello, Suleva; Oropesa-Ávila, Manuel; de la Cruz-Ojeda, Patricia; Villanueva-Paz, Marina; de la Mata, Mario; Suárez-Rivero, Juan Miguel; Álvarez-Córdoba, Mónica; Villalón-García, Irene; Cotán, David; Ybot-González, Patricia; Sánchez-Alcázar, José A

2017-11-11

During apoptosis, cells undergo characteristic morphological changes in which the cytoskeleton plays an active role. The cytoskeleton rearrangements have been mainly attributed to actinomyosin ring contraction, while microtubule and intermediate filaments are depolymerized at early stages of apoptosis. However, recent results have shown that microtubules are reorganized during the execution phase of apoptosis forming an apoptotic microtubule network (AMN). Evidence suggests that AMN is required to maintain plasma membrane integrity and cell morphology during the execution phase of apoptosis. The new "two coffins" hypothesis proposes that both AMN and apoptotic cells can adopt two morphological patterns, round or irregular, which result from different cytoskeleton kinetic reorganization during the execution phase of apoptosis induced by genotoxic agents. In addition, round and irregular-shaped apoptosis showed different biological properties with respect to AMN maintenance, plasma membrane integrity and phagocyte responses. These findings suggest that knowing the type of apoptosis may be important to predict how fast apoptotic cells undergo secondary necrosis and the subsequent immune response. From a pathological point of view, round-shaped apoptosis can be seen as a physiological and controlled type of apoptosis, while irregular-shaped apoptosis can be considered as a pathological type of cell death closer to necrosis.

Dynamic Reorganization of the Cytoskeleton during Apoptosis: The Two Coffins Hypothesis

PubMed Central

Povea-Cabello, Suleva; Oropesa-Ávila, Manuel; de la Cruz-Ojeda, Patricia; Villanueva-Paz, Marina; de la Mata, Mario; Álvarez-Córdoba, Mónica; Villalón-García, Irene; Cotán, David; Ybot-González, Patricia

2017-01-01

During apoptosis, cells undergo characteristic morphological changes in which the cytoskeleton plays an active role. The cytoskeleton rearrangements have been mainly attributed to actinomyosin ring contraction, while microtubule and intermediate filaments are depolymerized at early stages of apoptosis. However, recent results have shown that microtubules are reorganized during the execution phase of apoptosis forming an apoptotic microtubule network (AMN). Evidence suggests that AMN is required to maintain plasma membrane integrity and cell morphology during the execution phase of apoptosis. The new “two coffins” hypothesis proposes that both AMN and apoptotic cells can adopt two morphological patterns, round or irregular, which result from different cytoskeleton kinetic reorganization during the execution phase of apoptosis induced by genotoxic agents. In addition, round and irregular-shaped apoptosis showed different biological properties with respect to AMN maintenance, plasma membrane integrity and phagocyte responses. These findings suggest that knowing the type of apoptosis may be important to predict how fast apoptotic cells undergo secondary necrosis and the subsequent immune response. From a pathological point of view, round-shaped apoptosis can be seen as a physiological and controlled type of apoptosis, while irregular-shaped apoptosis can be considered as a pathological type of cell death closer to necrosis. PMID:29137119

The normal squamocolumnar junction is circumferentially even and minimal irregularities are manifestations of gastroesophageal acid reflux.

PubMed

Guerrero Garcia Hall, Mats; Wenner, Jörgen; Öberg, Stefan

2017-03-01

The macroscopic appearance of the normal squamocolumnar junction (SCJ) is often described as serrated with short projections of columnar mucosa that extend into the esophagus. As studies of the normal SCJ are sparse, the aim of this study was to test the hypothesis that the normal SCJ is even and that irregularities are manifestations of acid reflux. Fifty asymptomatic subjects and 149 patients with symptoms suggestive of gastroesophageal reflux disease underwent endoscopy and 48-h pH monitoring with a pH electrode positioned immediately above the SCJ. The shape of the SCJ was assessed according to the Z-line appearance classification and correlated with clinical characteristics and the degree of esophageal acid exposure in the most distal esophagus. Even SCJs without irregularities were significantly more common in asymptomatic subjects compared with patients (50% versus 10%, p < .001) and were never found in patients with erosive esophagitis. The median degree of distal esophageal acid exposure in individuals with an even SCJ was within normal limits. With increasing degree of irregularity of the SCJ, the frequency and duration of reflux episodes, the degree of distal esophageal acid exposure, and the prevalence of abnormal acid exposure increased progressively and significantly. The shape of the normal SCJ is even and also minimal irregularities are a consequence of acid reflux, likely due to the formation of small areas of metaplastic columnar mucosa.

Automatic estimation of dynamics of ionospheric disturbances with 1–15 minute lifetimes as derived from ISTP SB RAS fast chirp-ionosonde data

NASA Astrophysics Data System (ADS)

Berngardt, Oleg; Bubnova, Tatyana; Podlesnyi, Aleksey

2018-03-01

We propose and test a method of analyzing ionograms of vertical ionospheric sounding, which is based on detecting deviations of the shape of an ionogram from its regular (averaged) shape. We interpret these deviations in terms of reflection from the electron density irregularities at heights corresponding to the effective height. We examine the irregularities thus discovered within the framework of a model of a localized uniformly moving irregularity, and determine their characteristic parameters: effective heights and observed vertical velocities. We analyze selected experimental data for three seasons (spring, winter, autumn) obtained nearby Irkutsk with a fast chirp ionosonde of ISTP SB RAS in 2013-2015. The analysis of six days of observations conducted in these seasons has shown that in the observed vertical drift of the irregularities there are two characteristic distributions: wide velocity distribution with nearly 0 m/s mean and with the standard deviation of ∼250 m/s and narrow distribution with nearly -160 m/s mean. The analysis has demonstrated the effectiveness of the proposed algorithm for the automatic analysis of vertical sounding data with high repetition rate.

The Evolution of Dwarf-Irregular Galaxy NGC 1569: A Kinematic Study of the Stars and Gas

NASA Astrophysics Data System (ADS)

Johnson, Megan C.

2011-12-01

The evolution and formation of dwarf galaxies has great importance to our knowledge of cosmological history from the Big Bang through the present day structure we observe in our local universe. Dwarf galaxies are believed to be the "building blocks" of larger galaxies, which implies that interactions and mergers of these small systems must have occurred frequently in the early universe. There is a population of starburst dwarf irregular (dIm) galaxies that seem to have characteristics indicative of interactions or mergers. One of these dIm galaxies is the nearby post-starburst NGC 1569. This dissertation project explores the stellar and gas kinematics of NGC 1569 as well as examines a deep neutral Hydrogen (HI) map made using the Robert C. Byrd Green Bank Telescope (GBT). From these observations, this dissertation analyzes the evolution of NGC 1569 by understanding the three-dimensional shape of this dIm system for the first time. The structure of dIm galaxies is an important fundamental, physical property necessary to understand the evolution and formation of these common systems. However, the intrinsic shape of dIm galaxies remains controversial. Projected minor-to-major axis ratios provide insufficient data to determine the shapes of dIm galaxies. Fortunately, there is another method by which accurate structures can be measured. The stellar velocity dispersion, coupled with the maximum rotational velocity derived from HI observations, gives a measure of how kinematically hot a system is, and, therefore, indicates its structure. In this dissertation, we present the stellar kinematics, including the stellar velocity dispersion, of NGC 1569 obtained using the Kitt Peak National Observatory (KPNO) Mayall 4-m+Echelle spectrograph. These data are combined with an in depth analysis of high resolution HI data and a discussion of the nature of this starburst dwarf system. The dissertation concludes with a deep HI map of NGC 1569 and three of its nearest neighbors in the IC 342 galaxy group. Extended HI structures are observed in this map and are likely associated with NGC 1569. However, distinguishing if these structures are from an interaction or a merger is not possible and hydrodynamic simulations are needed. These simulations are for future work.

Effects of the phosphatase inhibitors, okadaic acid, ATPgammaS, and calyculin A on the dividing sand dollar egg.

PubMed

Hamaguchi, Yukihisa; Kuriyama, Ryoko

2002-06-01

The effects of the phosphatase inhibitors, okadaic acid (OA), adenosine 5'-O-(3-thiotriphosphate) (ATPgammaS), and calyculin A (CL-A) on anaphase chromosome movement, cytokinesis, and cytoskeletal structures at cell division were examined by being microinjected into mitotic sand dollar eggs. When OA was injected, chromosome movement was inhibited and, moreover, chromosomes were ejected from the polar regions of the mitotic apparatus. By immunofluorescence, microtubules were observed to be severed in the OA-injected eggs, causing the smooth cell surface to be changed to an irregular surface. When ATPgammaS and CL-A were injected, the effect on cell shape was remarkable: In dividing eggs, furrowing stopped within several seconds after injection, small blebs appeared on the cell surface and became large, spherical or dumbbell cell shapes then changed to irregular forms, and subsequently cytoplasmic flow occurred. Microfilament detection revealed that actin accumulation in the cortex, which was not limited to the furrow cortex, occurred shortly after injection. Cortical accumulation of actin is thought to induce force generation and random cortical contraction, and accordingly to result in bleb extrusion from the cortex. Consequently, the phosphatase inhibitors inhibited the transition from mitosis to interphase by mediating cortical accumulation of actin filaments and/or fragmentation of microtubules.

Porous material based on spongy titanium granules: structure, mechanical properties, and osseointegration.

PubMed

Rubshtein, A P; Trakhtenberg, I Sh; Makarova, E B; Triphonova, E B; Bliznets, D G; Yakovenkova, L I; Vladimirov, A B

2014-02-01

A porous material has been produced by pressing spongy titanium granules with subsequent vacuum sintering. The material with porosity of more than 30% has an open system of interconnecting pores. The Young's modulus and 0.2% proof strength have been measured for the samples having 20-55% porosity. If the porosity is between 30 and 45%, the mechanical properties are determined by irregular shape of pores, which is due to spongy titanium granules. The experiment in vivo was performed on adult rabbits. Before surgery the implants were saturated with adherent autologous bone marrow cells. The implants were introduced into the defects formed in the condyles of tibias and femurs. Investigations of osseointegration of implants having 40% porosity showed that the whole system of pores was filled with mature bone tissue in 16 weeks after surgery. Neogenic bone tissue has an uneven surface formed by lacunas and craters indicative of active resorption and subsequent rearrangement (SEM examination). The bone tissue is pierced by neoformed vessels. Irregular-shaped pores with tortuous walls and numerous lateral channels going through the granules provide necessary conditions for the formation of functional bone tissue in the implant volume and the periimplant region. Copyright © 2013 Elsevier B.V. All rights reserved.

Shape and size distribution of chaos areas on Europa

NASA Astrophysics Data System (ADS)

Mikell, T.; Cox, R.

2008-12-01

Chaos terrain is ubiquitous on Europa's surface, but not randomly distributed. The global distribution of chaos areas shows a significant concentration between 30° N and S latitude, decreasing dramatically at higher latitudes. The low-latitude clustering is not an artifact of recognizability, as there is a greater proportion of images with high solar incidence angle (low light) at higher latitudes. Clustering is especially marked in context of the few but vast regional chaos tracts (>15,000 km2) that occupy a substantial proportion of the equatorial region: i.e. the low latitudes have not only greater numbers but much greater areal chaos coverage. Apex-antapex asymmetry is difficult to evaluate because the Galileo longitudinal coverage is so poor; but comparison of the image swaths that follow great circles across the leading and trailing hemispheres respectively shows greater numbers of chaos areas on the leading side. In spite of the equatorial location of a few vast chaos tracts, there is no apparent relationship between chaos area size and latitude. Chaos area outlines vary from smoothly circular to extremely jagged: the irregularity index ranges from 2- 270% (based on the ratio between measured chaos area perimeter and the circumference of a circle of equal area). There is a range of shapes in all size brackets, but smaller chaos areas on average have simpler, more equidimensional shapes, and edge complexity increases for larger chaos areas. Chaos areas of ~10 km equivalent circle diameter (ECD) have outlines that are 4-90% irregular, ones ~50 km ECD are 15-180% and those >100 km ECD are 35-270% irregular. In general, chaos areas with higher irregularity indices also have a higher raft:matrix ratio. These results, while preliminary, are consistent with experimental evidence suggesting an impact origin for some chaos terrain on Europa. In particular, the relationship between shape and size parallels the results of impact experiments into ice over water, in which lower-energy impacts produce small, circular bullet-holes with few or no rafts; and higher-energy impacts generate wide-field fragmentation of the ice, producing large and highly irregular openings with abundant floating crustal blocks.

Dissipation of ionospheric irregularities by wave-particle and collisional interactions

NASA Technical Reports Server (NTRS)

Bernhardt, P. A.; Pongratz, M. B.; Gray, S. P.; Thomsen, M. F.

1982-01-01

The nonlinear dissipation of plasma irregularities aligned parallel to an ambient magnetic field is studied numerically using a model which employs both wave-particle and collisional diffusion. A wave-particle diffusion coefficient derived from a local theory of the universal drift instability is used. This coefficient is effective in regions of nonzero plasma gradients and produces triangular-shaped irregularities with spectra which vary as f to the -4th, where f is the spatial frequency. Collisional diffusion acts rapidly on the vertices of the irregularities to reduce their amplitude. The simultaneous action of the two dissipative processes is more efficient than collisions acting alone. In this model, wave-particle diffusion mimics the forward cascade process of wave-wave coupling.

Finite Element Estimation of Meteorite Structural Properties

NASA Technical Reports Server (NTRS)

Hart, Kenneth Arthur

2015-01-01

The goal of the project titled Asteroid Threat Assessment at NASA Ames Research Center is to develop risk assessment tools. The expertise in atmospheric entry in the Entry Systems and Technology Division is being used to describe the complex physics of meteor breakup in the atmosphere. The breakup of a meteor is dependent on its structural properties, including homogeneity of the material. The present work describes an 11-week effort in which a literature survey was carried for structural properties of meteoritic material. In addition, the effect of scale on homogeneity isotropy was studied using a Monte Carlo approach in Nastran. The properties were then in a static structural response simulation of an irregularly-shape meteor (138-scale version of Asteroid Itokawa). Finally, an early plan was developed for doctoral research work at Georgia Tech. in the structural failure fragmentation of meteors.

Results from Radio Tracking the Rosetta Spacecraft: Gravity, Internal Structure and Nucleus Composition of 67P/Churyumov-Gerasimenko

NASA Astrophysics Data System (ADS)

Hahn, M.; Andert, T.; Asmar, S.; Bird, M. K.; Häusler, B.; Peter, K.; Tellmann, S.; Weissman, P. R.; Barriot, J. P.; Sierks, H.

2017-12-01

When Rosetta arrived at its target comet 67P/Churyumov-Gerasimenko it first performed a series of distant flybys (100 - 30 km). During this mission phase the mass of the comets nucleus could be determined by analyzing the RSI radio tracking data. In combination with the volume from images of the OSIRIS camera this resulted in a precise bulk density determination. That already gave first insights into the comets interior structure. The nucleus appears to be a low-density, highly porous dusty body. From bound orbits with distances below 30 km the low degree and order gravity field coefficients could be derived. The gravity field coefficients strongly depend on the nucleus irregular shape and on the interior mass distribution. The shape is very well reconstructed from of the OSIRIS camera images. Various models of the interior nucleus structure and density distributions are used to compute simulated values of the gravity field coefficients. A comparison with the observed coefficients yields the feasibility of the theoretical interior structure. Thus, the gravity field helps constraining models of the internal structure, the composition and also of the origin and formation of the comets nucleus.

"Reinventing" Techniques for the Estimation of the Area of Irregular Plane Figures: From the Eighteenth Century to the Modern Classroom

ERIC Educational Resources Information Center

Papadopoulos, Ioannis

2010-01-01

The issue of the area of irregular shapes is absent from the modern mathematical textbooks in elementary education in Greece. However, there exists a collection of books written for educational purposes by famous Greek scholars dating from the eighteenth century, which propose certain techniques concerning the estimation of the area of such…

49 CFR 393.136 - What are the rules for securing large boulders?

Code of Federal Regulations, 2011 CFR

2011-10-01

... adequately secured. (3) Rock which has been formed or cut to a shape and which provides a stable base for... blocking used to support the boulder. (e) Securement of a non-cubic shaped boulder—with a stable base. In... piece of natural, irregularly shaped rock weighing in excess of 5,000 kg (11,000 lb.) or with a volume...

Correlation of changes of (non)exfoliated endometrial organelles and expressions of Musashi-1 and β-catenin with endometriosis in menstrual period.

PubMed

Yu, Cong-Xiang; Song, Jing-Hui; Liang, Lei

2014-01-01

This study aims to investigate the correlation of structural changes of endometrial organelles and expressions of Musashi-1 (Msi-1) and β-catenin with the endometriosis (EMs) in the menstrual period. The structural changes of exfoliated and nonexfoliated endometrial organelles in the experimental group and the control group were observed by the transmission electron microscopy (TEM) on the first and fifth day of menstruation. (1) TEM: compared with the control group, the exfoliated endometrial organelles in the experimental group on the first day were rich, with irregular nucleus, the bi-nucleolus could be seen, with rich chromatin; while the shapes of epithelial secretory cells in the nonexfoliated endometrial gland were irregular, with abundant organelles, the basal film varied in width, with abnormal curvature, and a lot of intercellular collagen fibers could be seen. (2) The expressions of Msi-1 and β-catenin in the exfoliated and nonexfoliated endometrium of the experimental group were higher than those of the control group and exhibited positively correlation, while no correlation could be found within the control group. (1) The organelles' structural changes might cause the changes of endometrial cellular functions. (2) Msi-1 might participate in the formation of EMs through activating the Wnt/β-catenin signaling pathway.

Parameters assessment of the inductively-coupled circuit for wireless power transfer

NASA Astrophysics Data System (ADS)

Isaev, Yu N.; Vasileva, O. V.; Budko, A. A.; Lefebvre, S.

2017-02-01

In this paper, a wireless power transfer model through the example of inductively-coupled coils of irregular shape in software package COMSOL Multiphysics is studied. Circuit parameters, such as inductance, coil resistance and self-capacitance were defined through electromagnetic energy by the finite-element method. The study was carried out according to Helmholtz equation. Spatial distribution of current per unit depending on frequency and the coupling coefficient for analysis of resonant frequency and spatial distribution of the vector magnetic potential at different distances between coils were presented. The resulting algorithm allows simulating the wireless power transfer between the inductively coupled coils of irregular shape with the assessment of the optimal parameters.

Can high resolution 3D topographic surveys provide reliable grain size estimates in gravel bed rivers?

NASA Astrophysics Data System (ADS)

Pearson, E.; Smith, M. W.; Klaar, M. J.; Brown, L. E.

2017-09-01

High resolution topographic surveys such as those provided by Structure-from-Motion (SfM) contain a wealth of information that is not always exploited in the generation of Digital Elevation Models (DEMs). In particular, several authors have related sub-metre scale topographic variability (or 'surface roughness') to sediment grain size by deriving empirical relationships between the two. In fluvial applications, such relationships permit rapid analysis of the spatial distribution of grain size over entire river reaches, providing improved data to drive three-dimensional hydraulic models, allowing rapid geomorphic monitoring of sub-reach river restoration projects, and enabling more robust characterisation of riverbed habitats. However, comparison of previously published roughness-grain-size relationships shows substantial variability between field sites. Using a combination of over 300 laboratory and field-based SfM surveys, we demonstrate the influence of inherent survey error, irregularity of natural gravels, particle shape, grain packing structure, sorting, and form roughness on roughness-grain-size relationships. Roughness analysis from SfM datasets can accurately predict the diameter of smooth hemispheres, though natural, irregular gravels result in a higher roughness value for a given diameter and different grain shapes yield different relationships. A suite of empirical relationships is presented as a decision tree which improves predictions of grain size. By accounting for differences in patch facies, large improvements in D50 prediction are possible. SfM is capable of providing accurate grain size estimates, although further refinement is needed for poorly sorted gravel patches, for which c-axis percentiles are better predicted than b-axis percentiles.

[Study on structure and phase transformation laws of natural FeS2 whisker by Raman spectroscopy].

PubMed

Huang, Fei; Kou, Da-Ming; Yao, Yu-Zeng; Ni, Pei; Ding, Jun-Ying

2009-08-01

FeS2 belongs to sulfide, including pyrite of isometric system and marcasite of orthorhombic system. The FeS2 discovered in Gengzhuang, Shanxi Province, was growing in the form of whisker. The study with scanning electron microscopy and electron probe show that the mineral components of FeS2 vary regularly. The structure of natural nano-micron FeS2 whisker was determined by micro-Raman spectroscopy. The results show that there exist two types of structure in FeS2 whiskers: pyrite and marcasite. Marcasite presents irregular shapes, such as coarse lotus root joints, crude columnar or beaded. Pyrite exists in the shape of straight line and smooth surface. In the early growing stage, Gengzhuang FeS2 whisker was mainly marcasite-type structure; in the middle stage it was coexistent structure of pyrite- and marcasite-type; in the late stage it was mainly pyrite-type. The growing stages of the whisker FeS2 show the phase transformation laws. Moreover, during the growing process marcasite was growing with pyrite coated on. Study on FeS2 whisker structure shows that there are correlations between phase transformation laws of the structure and forms, and between the forming time and the composition characteristics.

Curve Appeal: Exploring Individual Differences in Preference for Curved Versus Angular Objects

PubMed Central

Cotter, Katherine N.; Bertamini, Marco; Palumbo, Letizia; Vartanian, Oshin

2017-01-01

A preference for smooth curvature, as opposed to angularity, is a well-established finding for lines, two-dimensional shapes, and complex objects, but little is known about individual differences. We used two-dimensional black-and-white shapes—randomly generated irregular polygons, and arrays of circles and hexagons—and measured many individual differences, including artistic expertise, personality, and cognitive style. As expected, people preferred curved over angular stimuli, and people’s degree of curvature preference correlated across the two sets of shapes. Multilevel models showed varying patterns of interaction between shape and individual differences. For the irregular polygons, people higher in artistic expertise or openness to experience showed a greater preference for curvature. This pattern was not evident for the arrays of circles and hexagons. We discuss the results in relation to the nature of the stimuli, and we conclude that individual differences do play a role in moderating the preference for smooth curvature. PMID:28491269

Selection of stationary phase particle geometry using X-ray computed tomography and computational fluid dynamics simulations.

PubMed

Schmidt, Irma; Minceva, Mirjana; Arlt, Wolfgang

2012-02-17

The X-ray computed tomography (CT) is used to determine local parameters related to the column packing homogeneity and hydrodynamics in columns packed with spherically and irregularly shaped particles of same size. The results showed that the variation of porosity and axial dispersion coefficient along the column axis is insignificant, compared to their radial distribution. The methodology of using the data attained by CT measurements to perform a CFD simulation of a batch separation of model binary mixtures, with different concentration and separation factors is demonstrated. The results of the CFD simulation study show that columns packed with spherically shaped particles provide higher yield in comparison to columns packed with irregularly shaped particles only below a certain value of the separation factor. The presented methodology can be used for selecting a suited packing material for a particular separation task. Copyright © 2012 Elsevier B.V. All rights reserved.

DC heating induced shape transformation of Ge structures on ultraclean Si(5 5 12) surfaces.

PubMed

Dash, J K; Rath, A; Juluri, R R; Raman, P Santhana; Müller, K; Rosenauer, A; Satyam, P V

2011-04-06

We report the growth of Ge nanostructures and microstructures on ultraclean, high vicinal angle silicon surfaces and show that self-assembled growth at optimum thickness of the overlayer leads to interesting shape transformations, namely from nanoparticle to trapezoidal structures, at higher thickness values. Thin films of Ge of varying thickness from 3 to 12 ML were grown under ultrahigh vacuum conditions on a Si(5 5 12) substrate while keeping the substrate at a temperature of 600 °C. The substrate heating was achieved by two methods: (i) by heating a filament under the substrate (radiative heating, RH) and (ii) by passing direct current through the samples in three directions (perpendicular, parallel and at 45° to the (110) direction of the substrate). We find irregular, more spherical-like island structures under RH conditions. The shape transformations have been found under DC heating conditions and for Ge deposition more than 8 ML thick. The longer sides of the trapezoid structures are found to be along (110) irrespective of the DC current direction. We also show the absence of such a shape transformation in the case of Ge deposition on Si(111) substrates. Scanning transmission electron microscopy measurements suggested the mixing of Ge and Si. This has been confirmed with a quantitative estimation of the intermixing using Rutherford backscattering spectrometry (RBS) measurements. The role of DC heating in the formation of aligned structures is discussed. Although the RBS simulations show the presence of a possible SiO(x) layer, under the experimental conditions of the present study, the oxide layer would not play a role in determining the formation of the various structures that were reported here.

Using Fractal And Morphological Criteria For Automatic Classification Of Lung Diseases

NASA Astrophysics Data System (ADS)

Vehel, Jacques Levy

1989-11-01

Medical Images are difficult to analyze by means of classical image processing tools because they are very complex and irregular. Such shapes are obtained for instance in Nuclear Medecine with the spatial distribution of activity for organs such as lungs, liver, and heart. We have tried to apply two different theories to these signals: - Fractal Geometry deals with the analysis of complex irregular shapes which cannot well be described by the classical Euclidean geometry. - Integral Geometry treats sets globally and allows to introduce robust measures. We have computed three parameters on three kinds of Lung's SPECT images: normal, pulmonary embolism and chronic desease: - The commonly used fractal dimension (FD), that gives a measurement of the irregularity of the 3D shape. - The generalized lacunarity dimension (GLD), defined as the variance of the ratio of the local activity by the mean activity, which is only sensitive to the distribution and the size of gaps in the surface. - The Favard length that gives an approximation of the surface of a 3-D shape. The results show that each slice of the lung, considered as a 3D surface, is fractal and that the fractal dimension is the same for each slice and for the three kind of lungs; as for the lacunarity and Favard length, they are clearly different for normal lungs, pulmonary embolisms and chronic diseases. These results indicate that automatic classification of Lung's SPECT can be achieved, and that a quantitative measurement of the evolution of the disease could be made.

Reproducibility of image quality for moving objects using respiratory-gated computed tomography: a study using a phantom model

PubMed Central

Fukumitsu, Nobuyoshi; Ishida, Masaya; Terunuma, Toshiyuki; Mizumoto, Masashi; Hashimoto, Takayuki; Moritake, Takashi; Okumura, Toshiyuki; Sakae, Takeji; Tsuboi, Koji; Sakurai, Hideyuki

2012-01-01

To investigate the reproducibility of computed tomography (CT) imaging quality in respiratory-gated radiation treatment planning is essential in radiotherapy of movable tumors. Seven series of regular and six series of irregular respiratory motions were performed using a thorax dynamic phantom. For the regular respiratory motions, the respiratory cycle was changed from 2.5 to 4 s and the amplitude was changed from 4 to 10 mm. For the irregular respiratory motions, a cycle of 2.5 to 4 or an amplitude of 4 to 10 mm was added to the base data (i.e. 3.5-s cycle, 6-mm amplitude) every three cycles. Images of the object were acquired six times using respiratory-gated data acquisition. The volume of the object was calculated and the reproducibility of the volume was decided based on the variety. The registered image of the object was added and the reproducibility of the shape was decided based on the degree of overlap of objects. The variety in the volumes and shapes differed significantly as the respiratory cycle changed according to regular respiratory motions. In irregular respiratory motion, shape reproducibility was further inferior, and the percentage of overlap among the six images was 35.26% in the 2.5- and 3.5-s cycle mixed group. Amplitude changes did not produce significant differences in the variety of the volumes and shapes. Respiratory cycle changes reduced the reproducibility of the image quality in respiratory-gated CT. PMID:22966173

The Umov effect in application to an optically thin two-component cloud of cosmic dust

NASA Astrophysics Data System (ADS)

Zubko, Evgenij; Videen, Gorden; Zubko, Nataliya; Shkuratov, Yuriy

2018-04-01

The Umov effect is an inverse correlation between linear polarization of the sunlight scattered by an object and its geometric albedo. The Umov effect has been observed in particulate surfaces, such as planetary regoliths, and recently it also was found in single-scattering small dust particles. Using numerical modeling, we study the Umov effect in a two-component mixture of small irregularly shaped particles. Such a complex chemical composition is suggested in cometary comae and other types of optically thin clouds of cosmic dust. We find that the two-component mixtures of small particles also reveal the Umov effect regardless of the chemical composition of their end-member components. The interrelation between log(Pmax) and log(A) in a two-component mixture of small irregularly shaped particles appears either in a straight linear form or in a slightly curved form. This curvature tends to decrease while the index n in a power-law size distribution r-n grows; at n > 2.5, the log(Pmax)-log(A) diagrams are almost straight linear in appearance. The curvature also noticeably decreases with the packing density of constituent material in irregularly shaped particles forming the mixture. That such a relation exists suggest the Umov effect may also be observed in more complex mixtures.

Different Volumetric Measurement Methods for Pituitary Adenomas and Their Crucial Clinical Significance

PubMed Central

Chuang, Chi-Cheng; Lin, Shinn-Yn; Pai, Ping-Ching; Yan, Jiun-Lin; Toh, Cheng-Hong; Lee, Shih-Tseng; Wei, Kuo-Chen; Liu, Zhuo-Hao; Chen, Chung-Ming; Wang, Yu-Chi; Lee, Cheng-Chi

2017-01-01

Confirming the status of residual tumors is crucial. In stationary or spontaneous regression cases, early treatments are inappropriate. The long-used geometric calculation formula is 1/2 (length × width × height). However, it yields only rough estimates and is particularly unreliable for irregularly shaped masses. In our study, we attempted to propose a more accurate method. Between 2004 and 2014, 94 patients with pituitary tumors were enrolled in this retrospective study. All patients underwent transsphenoidal surgery and received magnetic resonance imaging (MRI). The pre- and postoperative volumes calculated using the traditional formula were termed A1 and A2, and those calculated using the proposed method were termed O1 and O2, respectively. Wilcoxon signed rank test revealed no significant difference between the A1 and O1 groups (P = 0.1810) but a significant difference between the A2 and O2 groups (P < 0.0001). Significant differences were present in the extent of resection (P < 0.0001), high-grade cavernous sinus invasion (P = 0.0312), and irregular shape (P = 0.0116). Volume is crucial in evaluating tumor status and determining treatment. Therefore, a more scientific method is especially useful when lesions are irregularly shaped or when treatment is determined exclusively based on the tumor volume. PMID:28098212

Risk Factors for the Rupture of Intracranial Aneurysms Using Computed Tomography Angiography.

PubMed

Wang, Guang-Xian; Wen, Li; Yang, Liu; Zhang, Qi-Chuang; Yin, Jin-Bo; Duan, Chun-Mei; Zhang, Dong

2018-02-01

To study the clinical and morphologic characteristics associated with risk factors for the rupture of intracranial aneurysms (IAs). A total of 1115 consecutive patients with 1282 IAs were reviewed from August 2011 to February 2016. The patients and IAs were divided into ruptured and unruptured groups. Based on the clinical and morphologic findings, the risk factors for IA rupture were assessed using statistical methods. Age, hypertension, diabetes mellitus, and cerebral atherosclerosis were associated with ruptured IAs. IAs located in the anterior cerebral artery, the anterior communicating artery, the posterior communicating artery, and the internal carotid artery were associated with ruptured IAs. Ruptures were also associated with arterial bifurcations, irregular aneurysm shapes, and all continuous data, except neck width. Binary logistic regression showed that IAs located at bifurcations (odds ratio [OR], 1.804), with irregular shapes (OR, 4.677), with high aspect ratios (ARs) (OR, 5.037) or with small mean diameters (MDs) (OR, 0.495) are more prone to rupture. Receiver operating characteristic analysis showed that the threshold values of the AR and MD were 1 and 3.70 mm, respectively. Morphologic characteristics, such as being located at bifurcations, being irregularly shaped, having a high AR (>1), and having a small MD (<3.70 mm), were better predictors of rupture. Copyright © 2017 Elsevier Inc. All rights reserved.

The Umov effect in application to an optically thin two-component cloud of cosmic dust

NASA Astrophysics Data System (ADS)

Zubko, Evgenij; Videen, Gorden; Zubko, Nataliya; Shkuratov, Yuriy

2018-07-01

The Umov effect is an inverse correlation between linear polarization of the sunlight scattered by an object and its geometric albedo. The Umov effect has been observed in particulate surfaces, such as planetary regoliths, and recently it also was found in single-scattering small dust particles. Using numerical modelling, we study the Umov effect in a two-component mixture of small irregularly shaped particles. Such a complex chemical composition is suggested in cometary comae and other types of optically thin clouds of cosmic dust. We find that the two-component mixtures of small particles also reveal the Umov effect regardless of the chemical composition of their end-member components. The interrelation between log(Pmax) and log(A) in a two-component mixture of small irregularly shaped particles appears either in a straight linear form or in a slightly curved form. This curvature tends to decrease while the index n in a power-law size distribution r-n grows; at n > 2.5, the log(Pmax)-log(A) diagrams are almost straight linear in appearance. The curvature also noticeably decreases with the packing density of constituent material in irregularly shaped particles forming the mixture. That such a relation exists suggests the Umov effect may also be observed in more complex mixtures.

A Coherent Fiber for an Airborne Heterodyne Sensor.

DTIC Science & Technology

1982-04-01

17 4 TlBr /KRS-5 fiber showing irregular core shape . ....... ... 20 5 Enlargement of fiber cross section showing highly irregular core...21 6 TIBr/KRS-5 billet after extrusion ...... ............. 22 7 Side view of TlBr /KRS-5 fiber extruded at high...material. The composite billet is then extruded into fiber. Our composite billets were made of TlBr /KRS-5 and KRS-6/TlCl (clad/core). The extruded

Barium Cloud Test in Peru.

DTIC Science & Technology

1981-11-01

site. The irregularity would be measured by the AFWAL and AFGL equipped aircraft, the Jacamarca radar site, and receivers set at several Peruvian ground...The launch was made from Punta Lobos, Peru, a station of the Peruvian Space Commission (CONIDA). 1I AFWAL-TR-81-1178 SECTION II DESCRIPTION OF TEST...forming a football -shaped irregularity ion cloud (Figure 2). The clouds were then expected to drift eastwardly with the neutral ionospheric winds, crossing

Safe structures for future aircraft

NASA Technical Reports Server (NTRS)

Mccomb, H. G., Jr.

1983-01-01

The failure mechanisms, design lessons, and test equipment employed by NASA in establishing the airworthiness and crashworthiness of aircraft components for commercial applications are described. The composites test programs have progressed to medium primary structures such as stabilizers and a vertical fin. The failures encountered to date have been due to the nonyielding nature of composites, which do not diffuse loads like metals, and the presence of eccentricities, irregular shapes, stiffness changes, and discontinuities that cause tension and shear. Testing to failure, which always occurred in first tests before the design loads were reached, helped identify design changes and reinforcements that produced successful products. New materials and NDE techniques are identified, together with aircraft structural design changes that offer greater protection to the passengers, fuel antimisting agents, and landing gear systems.

Modeling photoacoustic spectral features of micron-sized particles

NASA Astrophysics Data System (ADS)

Strohm, Eric M.; Gorelikov, Ivan; Matsuura, Naomi; Kolios, Michael C.

2014-10-01

The photoacoustic signal generated from particles when irradiated by light is determined by attributes of the particle such as the size, speed of sound, morphology and the optical absorption coefficient. Unique features such as periodically varying minima and maxima are observed throughout the photoacoustic signal power spectrum, where the periodicity depends on these physical attributes. The frequency content of the photoacoustic signals can be used to obtain the physical attributes of unknown particles by comparison to analytical solutions of homogeneous symmetric geometric structures, such as spheres. However, analytical solutions do not exist for irregularly shaped particles, inhomogeneous particles or particles near structures. A finite element model (FEM) was used to simulate photoacoustic wave propagation from four different particle configurations: a homogeneous particle suspended in water, a homogeneous particle on a reflecting boundary, an inhomogeneous particle with an absorbing shell and non-absorbing core, and an irregularly shaped particle such as a red blood cell. Biocompatible perfluorocarbon droplets, 3-5 μm in diameter containing optically absorbing nanoparticles were used as the representative ideal particles, as they are spherical, homogeneous, optically translucent, and have known physical properties. The photoacoustic spectrum of micron-sized single droplets in suspension and on a reflecting boundary were measured over the frequency range of 100-500 MHz and compared directly to analytical models and the FEM. Good agreement between the analytical model, FEM and measured values were observed for a droplet in suspension, where the spectral minima agreed to within a 3.3 MHz standard deviation. For a droplet on a reflecting boundary, spectral features were correctly reproduced using the FEM but not the analytical model. The photoacoustic spectra from other common particle configurations such as particle with an absorbing shell and a biconcave-shaped red blood cell were also investigated, where unique features in the power spectrum could be used to identify them.

Light Scattering Analysis of Irregularly Shaped Dust Particles: A Study Using 3-Dimensional Reconstructions from Focused Ion-Beam (FIB) Tomography and Q-Space Analysis

NASA Astrophysics Data System (ADS)

Ortiz-Montalvo, D. L.; Conny, J. M.

2017-12-01

We study the scattering properties of irregularly shaped ambient dust particles. The way in which they scatter and absorb light has implications for aerosol optical remote sensing and aerosol radiative forcing applications. However, understanding light scattering and absorption by non-spherical particles can be very challenging. We used focused ion-beam scanning electron microscopy and energy-dispersive x-ray spectroscopy (FIB-SEM-EDS) to reconstruct three-dimensional (3-D) configurations of dust particles collected from urban and Asian sources. The 3-D reconstructions were then used in a discrete dipole approximation method (DDA) to determine their scattering properties for a range of shapes, sizes, and refractive indices. Scattering properties where obtained using actual-shapes of the particles, as well as, (theoretical) equivalently-sized geometrical shapes like spheres, ellipsoids, cubes, rectangular prisms, and tetrahedrons. We use Q-space analysis to interpret the angular distribution of the scattered light obtained for each particle. Q-space analysis has been recently used to distinguish scattering by particles of different shapes, and it involves plotting the scattered intensity versus the scattering wave vector (q or qR) on a log-log scale, where q = 2ksin(θ/2), k = 2π/λ, and R = particle effective radius. Results from a limited number of particles show that when Q-space analysis is applied, common patterns appear that agree with previous Q-space studies done on ice crystals and other irregularly shaped particles. More specifically, we found similar Q-space regimes including a forward scattering regime of constant intensity when qR < 1, followed by the Guinier regime when qR ≈ 1, which is then followed by a complex power law regime with a -3 slope regime, a transition regime, and then a -4 slope regime. Currently, Q-space comparisons between actual- and geometric shapes are underway with the objective of determining which geometric shape best represents the angular distribution and magnitude of the scattered light. Current work also focuses on the effects of the imaginary part of the refractive index on the light scattering of our dust particles.

A new surface fractal dimension for displacement mode shape-based damage identification of plate-type structures

NASA Astrophysics Data System (ADS)

Shi, Binkai; Qiao, Pizhong

2018-03-01

Vibration-based nondestructive testing is an area of growing interest and worthy of exploring new and innovative approaches. The displacement mode shape is often chosen to identify damage due to its local detailed characteristic and less sensitivity to surrounding noise. Requirement for baseline mode shape in most vibration-based damage identification limits application of such a strategy. In this study, a new surface fractal dimension called edge perimeter dimension (EPD) is formulated, from which an EPD-based window dimension locus (EPD-WDL) algorithm for irregularity or damage identification of plate-type structures is established. An analytical notch-type damage model of simply-supported plates is proposed to evaluate notch effect on plate vibration performance; while a sub-domain of notch cases with less effect is selected to investigate robustness of the proposed damage identification algorithm. Then, fundamental aspects of EPD-WDL algorithm in term of notch localization, notch quantification, and noise immunity are assessed. A mathematical solution called isomorphism is implemented to remove false peaks caused by inflexions of mode shapes when applying the EPD-WDL algorithm to higher mode shapes. The effectiveness and practicability of the EPD-WDL algorithm are demonstrated by an experimental procedure on damage identification of an artificially-induced notched aluminum cantilever plate using a measurement system of piezoelectric lead-zirconate (PZT) actuator and scanning laser Doppler vibrometer (SLDV). As demonstrated in both the analytical and experimental evaluations, the new surface fractal dimension technique developed is capable of effectively identifying damage in plate-type structures.

Contemplative Janus

NASA Image and Video Library

2015-01-19

Janus (111 miles or 179 kilometers across) seems to almost stare off into the distance, contemplating deep, moonish thoughts as the F ring stands by at the bottom of this image. From this image, it is easy to distinguish Janus' shape from that of a sphere. Many of Saturn's smaller moons have similarly irregular shapes that scientists believe may give clues to their origins and internal structure. Models combining the dynamics of this moon with its shape imply the existence of mass inhomogeneities within Janus. This would be a surprising result for a body the size of Janus. By studying more images of Janus, scientists may be able confirm this finding and determine just how complicated the internal structure of this small body is. This image is roughly centered on the side of Janus which faces away from Saturn. North on Janus is up and rotated 3 degrees to the right. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on March 28, 2012. The view was obtained at a distance of approximately 54,000 miles (87,000 kilometers) from Janus. Image scale is 1,700 feet (520 meters) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA18299

Syntactic methods of shape feature description and its application in analysis of medical images

NASA Astrophysics Data System (ADS)

Ogiela, Marek R.; Tadeusiewicz, Ryszard

2000-02-01

The paper presents specialist algorithms of morphologic analysis of shapes of selected organs of abdominal cavity proposed in order to diagnose disease symptoms occurring in the main pancreatic ducts and upper segments of ureters. Analysis of the correct morphology of these structures has been conducted with the use of syntactic methods of pattern recognition. Its main objective is computer-aided support to early diagnosis of neoplastic lesions and pancreatitis based on images taken in the course of examination with the endoscopic retrograde cholangiopancreatography (ERCP) method and a diagnosis of morphological lesions in ureter based on kidney radiogram analysis. In the analysis of ERCP images, the main objective is to recognize morphological lesions in pancreas ducts characteristic for carcinoma and chronic pancreatitis. In the case of kidney radiogram analysis the aim is to diagnose local irregularity of ureter lumen. Diagnosing the above mentioned lesion has been conducted with the use of syntactic methods of pattern recognition, in particular the languages of shape features description and context-free attributed grammars. These methods allow to recognize and describe in a very efficient way the aforementioned lesions on images obtained as a result of initial image processing into diagrams of widths of the examined structures.

Enhancing Zeolite Performance by Catalyst Shaping in a Mesoscale Continuous-Flow Diels-Alder Process.

PubMed

Seghers, Sofie; Lefevere, Jasper; Mullens, Steven; De Vylder, Anton; Thybaut, Joris W; Stevens, Christian V

2018-03-26

In contrast to most lab-scale batch procedures, a continuous-flow implementation requires a thorough consideration of the solid catalyst design. In a previous study, irregular zeolite pellets were applied in a miniaturized continuous-flow reactor for the Diels-Alder reaction in the construction of norbornene scaffolds. After having faced the challenges of continuous operation, the aim of this study is to exploit catalyst structuring. To this end, microspheres with high uniformity and various sphere diameters were synthesized according to the vibrational droplet coagulation method. The influence of the use of these novel zeolite shapes in a mesoscale continuous-flow Diels-Alder process of cyclopentadiene and methyl acrylate is discussed. An impressive enhancement of catalyst lifetime is demonstrated, as even after a doubled process time of 14 h, the microspheres still exceeded the conversion after 7 h when using zeolite pellets by 30 %. A dual reason is found for this beneficial impact of catalyst shaping. The significant improvement in catalyst longevity can be attributed to the interplay of the chemical composition and the porosity structure of the microspheres. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Microstructural effect on radiative scattering coefficient and asymmetry factor of anisotropic thermal barrier coatings

NASA Astrophysics Data System (ADS)

Chen, X. W.; Zhao, C. Y.; Wang, B. X.

2018-05-01

Thermal barrier coatings are common porous materials coated on the surface of devices operating under high temperatures and designed for heat insulation. This study presents a comprehensive investigation on the microstructural effect on radiative scattering coefficient and asymmetry factor of anisotropic thermal barrier coatings. Based on the quartet structure generation set algorithm, the finite-difference-time-domain method is applied to calculate angular scattering intensity distribution of complicated random microstructure, which takes wave nature into account. Combining Monte Carlo method with Particle Swarm Optimization, asymmetry factor, scattering coefficient and absorption coefficient are retrieved simultaneously. The retrieved radiative properties are identified with the angular scattering intensity distribution under different pore shapes, which takes dependent scattering and anisotropic pore shape into account implicitly. It has been found that microstructure significantly affects the radiative properties in thermal barrier coatings. Compared with spherical shape, irregular anisotropic pore shape reduces the forward scattering peak. The method used in this paper can also be applied to other porous media, which designs a frame work for further quantitative study on porous media.

Management of irregular astigmatism.

PubMed

Goggin, M; Alpins, N; Schmid, L M

2000-08-01

Using a liberal definition of corneal irregularity, modern videokeratoscopy may define approximately 40% of normal corneas with a toric refractive error as possessing primary irregular astigmatism. The causes of secondary forms of irregular astigmatism include corneal surgery, trauma, dystrophies, and infections. Internal refractive surface and media irregularity or noncorneal astigmatism (ocular residual astigmatism) contribute to irregular astigmatism of the entire refractive path of which crystaline lenticular astigmatism is usually the principal contributing component. Treatment options have increased in recent years, particularly, though not exclusively, through the advent of tailored corneal excimer laser ablations. However, discussion continues concerning the systematic approach necessary to enable treatment to achieve an optimal optical surface for the eye. Discussion also continues as to what constitutes the optimal corneal shape. Some refractive procedures may increase higher order aberrations in the attempt to neutralize refractive astigmatism. The way to further refinement of the commonly performed refractive techniques will ultimately lie in the integrated inclusion of a trio of technologies: topographic analysis of the corneal surface, wavefront analysis of ocular refractive aberrations, and vector planning to enable the appropriate balance in emphasis between these two diagnostic modalities. For the uncommon, irregularly roughened corneas, the ablatable polymer techniques show some promise.

Orbital and Collisional Evolution of the Irregular Satellites

NASA Astrophysics Data System (ADS)

Nesvorný, David; Alvarellos, Jose L. A.; Dones, Luke; Levison, Harold F.

2003-07-01

The irregular moons of the Jovian planets are a puzzling part of the solar system inventory. Unlike regular satellites, the irregular moons revolve around planets at large distances in tilted and eccentric orbits. Their origin, which is intimately linked with the origin of the planets themselves, is yet to be explained. Here we report a study of the orbital and collisional evolution of the irregular satellites from times after their formation to the present epoch. The purpose of this study is to find out the features of the observed irregular moons that can be attributed to this evolution and separate them from signatures of the formation process. We numerically integrated ~60,000 test satellite orbits to map orbital locations that are stable on long time intervals. We found that the orbits highly inclined to the ecliptic are unstable due to the effect of the Kozai resonance, which radially stretches them so that satellites either escape from the Hill sphere, collide with massive inner moons, or impact the parent planet. We also found that prograde satellite orbits with large semimajor axes are unstable due to the effect of the evection resonance, which locks the orbit's apocenter to the apparent motion of the Sun around the parent planet. In such a resonance, the effect of solar tides on a resonant moon accumulates at each apocenter passage of the moon, which causes a radially outward drift of its orbital apocenter; once close to the Hill sphere, the moon escapes. By contrast, retrograde moons with large orbital semimajor axes are long-lived. We have developed an analytic model of the distant satellite orbits and used it to explain the results of our numerical experiments. In particular, we analytically studied the effect of the Kozai resonance. We numerically integrated the orbits of the 50 irregular moons (known by 2002 August 16) for 108 yr. All orbits were stable on this time interval and did not show any macroscopic variations that would indicate instabilities operating on longer time spans. The average orbits calculated from this experiment were then used to probe the collisional evolution of the irregular satellite systems. We found that (1) the large irregular moons must have collisionally eliminated many small irregular moons, thus shaping their population to the currently observed structures; (2) some dynamical families of satellites could have been formed by catastrophic collisions among the irregular moons; and (3) Phoebe's surface must have been heavily cratered by impacts from an extinct population of Saturnian irregular moons, much larger than the present one. We therefore suggest that the Cassini imaging of Phoebe in 2004 can be used to determine the primordial population of small irregular moons of Saturn. In such a case, we will also better understand the overall efficiency of the formation process of the irregular satellites and the physical conditions that existed during planetary formation. We discovered two dynamical families of tightly clustered orbits within the Jovian retrograde group. We believe that these two clusters may be the remnants of two collisionally disrupted bodies. We found that the entire Jovian retrograde group and the Saturnian inclination groups were not produced by single breakups, because the ejection velocities derived from the orbital structures of these groups greatly exceed values calculated by modern numerical models of collisional breakups. Taken together, the evidence presented here suggests that many properties of the irregular moons previously assigned to their formation process may have resulted from their later dynamical and collisional evolution. Finally, we have found that several irregular moons, namely, Pasiphae, Sinope, S/2001 J10, S/2000 S5, S/2000 S6, and S/2000 S3, have orbits characterized by secular resonances. The orbits of some of these moons apparently evolved by some slow dissipative process in the past and became captured in tiny resonant volumes.

Irregular Applications: Architectures & Algorithms

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

Feo, John T.; Villa, Oreste; Tumeo, Antonino

Irregular applications are characterized by irregular data structures, control and communication patterns. Novel irregular high performance applications which deal with large data sets and require have recently appeared. Unfortunately, current high performance systems and software infrastructures executes irregular algorithms poorly. Only coordinated efforts by end user, area specialists and computer scientists that consider both the architecture and the software stack may be able to provide solutions to the challenges of modern irregular applications.

Cosmic dust synthesis by accretion and coagulation

NASA Technical Reports Server (NTRS)

Praburam, G.; Goree, J.

1995-01-01

The morphology of grains grown by accretion and coagulation is revaled by a new laboratory method of synthesizing cosmic dust analogs. Submicron carbon particles, grown by accretion of carbon atoms from a gas, have a spherical shape with a cauliflower-like surface and an internal micro-structure of radial columns. This shape is probably common for grains grown by accretion at a temperature well below the melting point. Coagulated grains, consisting of spheres that collided to form irregular strings, were also synthesized. Another shape we produced had a bumpy non- spherical morphology, like an interplanetary particle collected in the terrestrial stratosphere. Besides these isolated grains, large spongy aggregates of nanometer-size particles were also found for various experimental conditions. Grains were synthesized using ions to sputter a solid target, producing an atomic vapor at a low temperature. The ions were provided by a plasma, which also provided electrostatic levitation of the grains during their growth. The temporal development of grain growth was studied by extinguishing the plasma after various intervals.

Synthetic control of the size, shape, and polydispersity of anisotropic silica colloids

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

Murphy, Ryan P.; Hong, Kunlun; Wagner, Norman J.

The particle size and shape determine the microstructure and rheological properties of colloidal suspensions. This work aims to further control the size, shape, and polydispersity of anisotropic silica colloids, to reduce particle size, and to provide additional mechanistic insights on a prevalent, water-in-oil emulsion synthesis method. Key findings show that the dimensions of anisotropic silica particles can be systematically varied by approximately fivefold, with a limiting minimum particle size (D ≈ 60 nm, L ≈ 300 nm) obtained from emulsions with excess polyvinylpyrrolidone (PVP) and sodium citrate. The synthesis conditions are identified and discussed for which the emulsion composition, temperature,more » sonication, polymer entanglements, mixing, and other perturbations may induce or mitigate emulsion instabilities, citrate precipitation, a competing mechanism of templated growth, termination of anisotropic growth, irregular silica structures, and fiber formation. An improved mechanistic understanding will expand the roadmap for rational design and synthetic control of anisotropic colloids using sol-gel silica chemistry confined within water-in-oil emulsions.« less

Synthetic control of the size, shape, and polydispersity of anisotropic silica colloids

DOE PAGES

Murphy, Ryan P.; Hong, Kunlun; Wagner, Norman J.

2017-09-01

The particle size and shape determine the microstructure and rheological properties of colloidal suspensions. This work aims to further control the size, shape, and polydispersity of anisotropic silica colloids, to reduce particle size, and to provide additional mechanistic insights on a prevalent, water-in-oil emulsion synthesis method. Key findings show that the dimensions of anisotropic silica particles can be systematically varied by approximately fivefold, with a limiting minimum particle size (D ≈ 60 nm, L ≈ 300 nm) obtained from emulsions with excess polyvinylpyrrolidone (PVP) and sodium citrate. The synthesis conditions are identified and discussed for which the emulsion composition, temperature,more » sonication, polymer entanglements, mixing, and other perturbations may induce or mitigate emulsion instabilities, citrate precipitation, a competing mechanism of templated growth, termination of anisotropic growth, irregular silica structures, and fiber formation. An improved mechanistic understanding will expand the roadmap for rational design and synthetic control of anisotropic colloids using sol-gel silica chemistry confined within water-in-oil emulsions.« less

Surface Plasmon Damping Quantified with an Electron Nanoprobe

PubMed Central

Bosman, Michel; Ye, Enyi; Tan, Shu Fen; Nijhuis, Christian A.; Yang, Joel K. W.; Marty, Renaud; Mlayah, Adnen; Arbouet, Arnaud; Girard, Christian; Han, Ming-Yong

2013-01-01

Fabrication and synthesis of plasmonic structures is rapidly moving towards sub-nanometer accuracy in control over shape and inter-particle distance. This holds the promise for developing device components based on novel, non-classical electro-optical effects. Monochromated electron energy-loss spectroscopy (EELS) has in recent years demonstrated its value as a qualitative experimental technique in nano-optics and plasmonic due to its unprecedented spatial resolution. Here, we demonstrate that EELS can also be used quantitatively, to probe surface plasmon kinetics and damping in single nanostructures. Using this approach, we present from a large (>50) series of individual gold nanoparticles the plasmon Quality factors and the plasmon Dephasing times, as a function of energy/frequency. It is shown that the measured general trend applies to regular particle shapes (rods, spheres) as well as irregular shapes (dendritic, branched morphologies). The combination of direct sub-nanometer imaging with EELS-based plasmon damping analysis launches quantitative nanoplasmonics research into the sub-nanometer realm. PMID:23425921

Investigating Evolved Compositions Around Wolf Crater

NASA Technical Reports Server (NTRS)

Greenhagen, B. T.; Cahill, J. T. S.; Jolliff, B. L.; Lawrence, S. J.; Glotch, T. D.

2017-01-01

Wolf crater is an irregularly shaped, approximately 25 km crater in the south-central portion of Mare Nubium on the lunar nearside. While not previously identified as a lunar "red spot", Wolf crater was identified as a Th anomaly by Lawrence and coworkers. We have used data from the Lunar Reconnaissance Orbiter (LRO) to determine the area surrounding Wolf crater has composition more similar to highly evolved, non-mare volcanic structures than typical lunar crustal lithology. In this presentation, we will investigate the geomorphology and composition of the Wolf crater and discuss implications for the origin of the anomalous terrain.

Free-Standing, Flexible, Superomniphobic Films.

PubMed

Vahabi, Hamed; Wang, Wei; Movafaghi, Sanli; Kota, Arun K

2016-08-31

Fabrication of most superomniphobic surfaces requires complex process conditions or specialized and expensive equipment or skilled personnel. In order to circumvent these issues and make them end-user-friendly, we developed the free-standing, flexible, superomniphobic films. These films can be stored and delivered to the end-users, who can readily attach them to virtually any surface (even irregular shapes) and impart superomniphobicity. The hierarchical structure, the re-entrant texture, and the low solid surface energy render our films superomniphobic for a wide variety of liquids. We demonstrate that our free-standing, flexible, superomniphobic films have applications in enhanced chemical resistance and enhanced weight bearing.

Two-dimensional liquid crystalline growth within a phase-field-crystal model.

PubMed

Tang, Sai; Praetorius, Simon; Backofen, Rainer; Voigt, Axel; Yu, Yan-Mei; Wang, Jincheng

2015-07-01

By using a two-dimensional phase-field-crystal (PFC) model, the liquid crystalline growth of the plastic triangular phase is simulated with emphasis on crystal shape and topological defect formation. The equilibrium shape of a plastic triangular crystal (PTC) grown from an isotropic phase is compared with that grown from a columnar or smectic-A (CSA) phase. While the shape of a PTC nucleus in the isotropic phase is almost identical to that of the classical PFC model, the shape of a PTC nucleus in CSA is affected by the orientation of stripes in the CSA phase, and irregular hexagonal, elliptical, octagonal, and rectangular shapes are obtained. Concerning the dynamics of the growth process, we analyze the topological structure of the nematic order, which starts from nucleation of +1/2 and -1/2 disclination pairs at the PTC growth front and evolves into hexagonal cells consisting of +1 vortices surrounded by six satellite -1/2 disclinations. It is found that the orientational and the positional order do not evolve simultaneously; the orientational order evolves behind the positional order, leading to a large transition zone, which can span over several lattice spacings.

The occultation of Kappa Geminorum by Eros. [stellar occultation observed for asteroid size and shape

NASA Technical Reports Server (NTRS)

Oleary, B.; Marsden, B. G.; Dragon, R.; Hauser, E.; Mcgrath, M.; Backus, P.; Robkoff, H.

1976-01-01

The paper discusses predictions and observations of the occultation of Kappa Gem by (433) Eros on January 24, 1975. Several positive and negative observations made in western New England are described. Local circumstances for the occultation are reconstructed, and the size and shape of Eros are determined analytically as well as graphically. The calculations yield two extremes for the cross section: a circle 23 km in diameter or a somewhat irregular figure 20 km by 6 or 7 km. Arguments based on the expected albedo of the asteroid suggest that the circle should be warped into an ellipse 21 by 13 km or that the irregular figure might be one component of a dumbbell-like profile.

The inter-rater reliability of estimating the size of burns from various burn area chart drawings.

PubMed

Wachtel, T L; Berry, C C; Wachtel, E E; Frank, H A

2000-03-01

The accuracy and variability of burn size calculations using four Lund and Browder charts currently in clinical use and two Rule of Nine's diagrams were evaluated. The study showed that variability in estimation increased with burn size initially, plateaued in large burns and then decreased slightly in extensive burns. The Rule of Nine's technique often overestimates the burn size and is more variable, but can be performed somewhat faster than the Lund and Browder method. More burn experience leads to less variability in burn area chart drawing estimates. Irregularly shaped burns and burns on the trunk and thighs had greater variability than less irregularly shaped burns or burns on more defined anatomical parts of the body.

Tree shadow patterns and illumination measurements with clearcut strips and irregular openings in a true fir forest

Treesearch

Donald T. Gordon

1968-01-01

Daily progression of shadows cast by red and white fir trees in forest stand openings is illustrated by vertical aerial photographs made on the summer solstice at 2-hour intervals from 7 a.m. to 5 p.m. The aerial photos show shade patterns in three irregularly - shaped, natural stand openings and two different widths (3-chains and 5-chains) of clearcut strips....

A composite scaffold of MSC affinity peptide-modified demineralized bone matrix particles and chitosan hydrogel for cartilage regeneration

NASA Astrophysics Data System (ADS)

Meng, Qingyang; Man, Zhentao; Dai, Linghui; Huang, Hongjie; Zhang, Xin; Hu, Xiaoqing; Shao, Zhenxing; Zhu, Jingxian; Zhang, Jiying; Fu, Xin; Duan, Xiaoning; Ao, Yingfang

2015-12-01

Articular cartilage injury is still a significant challenge because of the poor intrinsic healing potential of cartilage. Stem cell-based tissue engineering is a promising technique for cartilage repair. As cartilage defects are usually irregular in clinical settings, scaffolds with moldability that can fill any shape of cartilage defects and closely integrate with the host cartilage are desirable. In this study, we constructed a composite scaffold combining mesenchymal stem cells (MSCs) E7 affinity peptide-modified demineralized bone matrix (DBM) particles and chitosan (CS) hydrogel for cartilage engineering. This solid-supported composite scaffold exhibited appropriate porosity, which provided a 3D microenvironment that supports cell adhesion and proliferation. Cell proliferation and DNA content analysis indicated that the DBM-E7/CS scaffold promoted better rat bone marrow-derived MSCs (BMMSCs) survival than the CS or DBM/CS groups. Meanwhile, the DBM-E7/CS scaffold increased matrix production and improved chondrogenic differentiation ability of BMMSCs in vitro. Furthermore, after implantation in vivo for four weeks, compared to those in control groups, the regenerated issue in the DBM-E7/CS group exhibited translucent and superior cartilage-like structures, as indicated by gross observation, histological examination, and assessment of matrix staining. Overall, the functional composite scaffold of DBM-E7/CS is a promising option for repairing irregularly shaped cartilage defects.

Dose calculation for electron therapy using an improved LBR method.

PubMed

Gebreamlak, Wondesen T; Tedeschi, David J; Alkhatib, Hassaan A

2013-07-01

To calculate the percentage depth dose (PDD) of any irregularly shaped electron beam using a modified lateral build-up ratio (LBR) method. Percentage depth dose curves were measured using 6, 9, 12, and 15 MeV electron beam energies for applicator cone sizes of 6 × 6, 10 × 10, 14 × 14, and 20 × 20 cm(2). Circular cutouts for each cone were prepared from 2.0 cm diameter to the maximum possible size for each cone. In addition, three irregular cutouts were prepared. The LBR for each circular cutout was calculated from the measured PDD curve using the open field of the 14 × 14 cm(2) cone as the reference field. Using the LBR values and the radius of the circular cutouts, the corresponding lateral spread parameter [σR(z)] of the electron shower was calculated. Unlike the commonly accepted assumption that σR(z) is independent of cutout size, it is shown that its value increases linearly with circular cutout size (R). Using this characteristic of the lateral spread parameter, the PDD curves of irregularly shaped cutouts were calculated. Finally, the calculated PDD curves were compared with measured PDD curves. In this research, it is shown that the lateral spread parameter σR(z) increases with cutout size. For radii of circular cutout sizes up to the equilibrium range of the electron beam, the increase of σR(z) with the cutout size is linear. The percentage difference of the calculated PDD curve from the measured PDD data for irregularly shaped cutouts was under 1.0% in the region between the surface and therapeutic range of the electron beam. Similar results were obtained for four electron beam energies (6, 9, 12, and 15 MeV).

Matrix cracking with irregular fracture fronts as observed in fiber reinforced ceramic composites

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

Hu, K.X.; Yeh, C.P.; Wyatt, K.W.

1998-01-01

As a result of matrix cracking in fiber reinforced composites, fracture planforms assume a wide variation of profiles due to the fact that fiber bridging strongly affects the behavior of local crack fronts. This observation raises the question on the legitimacy of commonly used penny-shaped crack solutions when applied to fiber reinforced composites. Accordingly, investigation of the effects of fracture front profiles on mechanical responses is the thrust of this paper. The authors start with the solution of a penny-shaped crack in a unidirectional, fiber reinforced composite, which demonstrates necessity of considering wavy fracture fronts in fiber reinforced composites. Amore » theoretical framework for fiber reinforced composites with irregular fracture fronts due to matrix cracking is then established via a micromechanics model. The difference between small crack-size matrix cracking and large crack-size matrix cracking is investigated in detail. It is shown that the bridging effect is insignificant when matrix crack size is small and solution of effective property are obtained using Mori-Tanaka`s method by treating cracks and reinforcing fibers as distinct, but interacting phases. When the crack size becomes large, the bridging effects has to be taken into consideration. With bridging tractions obtained in consistency with the micromechanics solution, and corresponding crack energy backed out, the effective properties are obtained through a modification of standard Mori-Tanaka`s treatment of multiphase composites. Analytical solutions show that the generalization of a crack density of a penny-shaped planform is insufficient in describing the effective responses of fiber-reinforced composites with matrix cracking. Approximate solutions that account for the effects of the irregularity of crack planforms are given in closed forms for several irregular crack planforms, including cracks of cross rectangle, polygon and rhombus.« less

Classifying the hierarchy of nonlinear-Schrödinger-equation rogue-wave solutions.

PubMed

Kedziora, David J; Ankiewicz, Adrian; Akhmediev, Nail

2013-07-01

We present a systematic classification for higher-order rogue-wave solutions of the nonlinear Schrödinger equation, constructed as the nonlinear superposition of first-order breathers via the recursive Darboux transformation scheme. This hierarchy is subdivided into structures that exhibit varying degrees of radial symmetry, all arising from independent degrees of freedom associated with physical translations of component breathers. We reveal the general rules required to produce these fundamental patterns. Consequently, we are able to extrapolate the general shape for rogue-wave solutions beyond order 6, at which point accuracy limitations due to current standards of numerical generation become non-negligible. Furthermore, we indicate how a large set of irregular rogue-wave solutions can be produced by hybridizing these fundamental structures.

Fabrication of a Bioactive, PCL-based "Self-fitting" Shape Memory Polymer Scaffold.

PubMed

Nail, Lindsay N; Zhang, Dawei; Reinhard, Jessica L; Grunlan, Melissa A

2015-10-23

Tissue engineering has been explored as an alternative strategy for the treatment of critical-sized cranio-maxillofacial (CMF) bone defects. Essential to the success of this approach is a scaffold that is able to conformally fit within an irregular defect while also having the requisite biodegradability, pore interconnectivity and bioactivity. By nature of their shape recovery and fixity properties, shape memory polymer (SMP) scaffolds could achieve defect "self-fitting." In this way, following exposure to warm saline (~60 ºC), the SMP scaffold would become malleable, permitting it to be hand-pressed into an irregular defect. Subsequent cooling (~37 ºC) would return the scaffold to its relatively rigid state within the defect. To meet these requirements, this protocol describes the preparation of SMP scaffolds prepared via the photochemical cure of biodegradable polycaprolactone diacrylate (PCL-DA) using a solvent-casting particulate-leaching (SCPL) method. A fused salt template is utilized to achieve pore interconnectivity. To realize bioactivity, a polydopamine coating is applied to the surface of the scaffold pore walls. Characterization of self-fitting and shape memory behaviors, pore interconnectivity and in vitro bioactivity are also described.

On the interpolation of light-scattering responses from irregularly shaped particles

NASA Astrophysics Data System (ADS)

Videen, Gorden; Zubko, Evgenij; Arnold, Jessica A.; MacCall, Benjamin; Weinberger, Alycia J.; Shkuratov, Yuriy; Muñoz, Olga

2018-05-01

Common particle characteristics needed for many applications may include size, eccentricity, porosity and refractive index. Determining such characteristics from scattered light is a primary goal of remote sensing. For other applications, like differentiating a hazardous particle from the natural background, information about higher fidelity particle characteristics may be required, including specific shape or chemical composition. While a complete characterization of a particle system from its scattered light through the inversion process remains unachievable, great strides have been made in providing information in the form of constraints on particle characteristics. Recent advances have been made in quantifying the characteristics of polydispersions of irregularly shaped particles by making comparisons of the light-scattering signals from model simulant particles. We show that when the refractive index is changed, the light-scattering characteristics from polydispersions of such particles behave monotonically over relatively large parameter ranges compared with those of monodisperse distributions of particles having regular shapes, like spheres, spheroids, etc. This allows for their properties to be interpolated, which results in a significant reduction of the computational load when performing inversions.

An ERP study of regular and irregular English past tense inflection.

PubMed

Newman, Aaron J; Ullman, Michael T; Pancheva, Roumyana; Waligura, Diane L; Neville, Helen J

2007-01-01

Compositionality is a critical and universal characteristic of human language. It is found at numerous levels, including the combination of morphemes into words and of words into phrases and sentences. These compositional patterns can generally be characterized by rules. For example, the past tense of most English verbs ("regulars") is formed by adding an -ed suffix. However, many complex linguistic forms have rather idiosyncratic mappings. For example, "irregular" English verbs have past tense forms that cannot be derived from their stems in a consistent manner. Whether regular and irregular forms depend on fundamentally distinct neurocognitive processes (rule-governed combination vs. lexical memorization), or whether a single processing system is sufficient to explain the phenomena, has engendered considerable investigation and debate. We recorded event-related potentials while participants read English sentences that were either correct or had violations of regular past tense inflection, irregular past tense inflection, syntactic phrase structure, or lexical semantics. Violations of regular past tense and phrase structure, but not of irregular past tense or lexical semantics, elicited left-lateralized anterior negativities (LANs). These seem to reflect neurocognitive substrates that underlie compositional processes across linguistic domains, including morphology and syntax. Regular, irregular, and phrase structure violations all elicited later positivities that were maximal over midline parietal sites (P600s), and seem to index aspects of controlled syntactic processing of both phrase structure and morphosyntax. The results suggest distinct neurocognitive substrates for processing regular and irregular past tense forms: regulars depending on compositional processing, and irregulars stored in lexical memory.

Automatic tracking of arbitrarily shaped implanted markers in kilovoltage projection images: A feasibility study

PubMed Central

Regmi, Rajesh; Lovelock, D. Michael; Hunt, Margie; Zhang, Pengpeng; Pham, Hai; Xiong, Jianping; Yorke, Ellen D.; Goodman, Karyn A.; Rimner, Andreas; Mostafavi, Hassan; Mageras, Gig S.

2014-01-01

Purpose: Certain types of commonly used fiducial markers take on irregular shapes upon implantation in soft tissue. This poses a challenge for methods that assume a predefined shape of markers when automatically tracking such markers in kilovoltage (kV) radiographs. The authors have developed a method of automatically tracking regularly and irregularly shaped markers using kV projection images and assessed its potential for detecting intrafractional target motion during rotational treatment. Methods: Template-based matching used a normalized cross-correlation with simplex minimization. Templates were created from computed tomography (CT) images for phantom studies and from end-expiration breath-hold planning CT for patient studies. The kV images were processed using a Sobel filter to enhance marker visibility. To correct for changes in intermarker relative positions between simulation and treatment that can introduce errors in automatic matching, marker offsets in three dimensions were manually determined from an approximately orthogonal pair of kV images. Two studies in anthropomorphic phantom were carried out, one using a gold cylindrical marker representing regular shape, another using a Visicoil marker representing irregular shape. Automatic matching of templates to cone beam CT (CBCT) projection images was performed to known marker positions in phantom. In patient data, automatic matching was compared to manual matching as an approximate ground truth. Positional discrepancy between automatic and manual matching of less than 2 mm was assumed as the criterion for successful tracking. Tracking success rates were examined in kV projection images from 22 CBCT scans of four pancreas, six gastroesophageal junction, and one lung cancer patients. Each patient had at least one irregularly shaped radiopaque marker implanted in or near the tumor. In addition, automatic tracking was tested in intrafraction kV images of three lung cancer patients with irregularly shaped markers during 11 volumetric modulated arc treatments. Purpose-built software developed at our institution was used to create marker templates and track the markers embedded in kV images. Results: Phantom studies showed mean ± standard deviation measurement uncertainty of automatic registration to be 0.14 ± 0.07 mm and 0.17 ± 0.08 mm for Visicoil and gold cylindrical markers, respectively. The mean success rate of automatic tracking with CBCT projections (11 frames per second, fps) of pancreas, gastroesophageal junction, and lung cancer patients was 100%, 99.1% (range 98%–100%), and 100%, respectively. With intrafraction images (approx. 0.2 fps) of lung cancer patients, the success rate was 98.2% (range 97%–100%), and 94.3% (range 93%–97%) using templates from 1.25 mm and 2.5 mm slice spacing CT scans, respectively. Correction of intermarker relative position was found to improve the success rate in two out of eight patients analyzed. Conclusions: The proposed method can track arbitrary marker shapes in kV images using templates generated from a breath-hold CT acquired at simulation. The studies indicate its feasibility for tracking tumor motion during rotational treatment. Investigation of the causes of misregistration suggests that its rate of incidence can be reduced with higher frequency of image acquisition, templates made from smaller CT slice spacing, and correction of changes in intermarker relative positions when they occur. PMID:24989384

Automatic tracking of arbitrarily shaped implanted markers in kilovoltage projection images: A feasibility study

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

Regmi, Rajesh; Lovelock, D. Michael; Hunt, Margie

Purpose: Certain types of commonly used fiducial markers take on irregular shapes upon implantation in soft tissue. This poses a challenge for methods that assume a predefined shape of markers when automatically tracking such markers in kilovoltage (kV) radiographs. The authors have developed a method of automatically tracking regularly and irregularly shaped markers using kV projection images and assessed its potential for detecting intrafractional target motion during rotational treatment. Methods: Template-based matching used a normalized cross-correlation with simplex minimization. Templates were created from computed tomography (CT) images for phantom studies and from end-expiration breath-hold planning CT for patient studies. Themore » kV images were processed using a Sobel filter to enhance marker visibility. To correct for changes in intermarker relative positions between simulation and treatment that can introduce errors in automatic matching, marker offsets in three dimensions were manually determined from an approximately orthogonal pair of kV images. Two studies in anthropomorphic phantom were carried out, one using a gold cylindrical marker representing regular shape, another using a Visicoil marker representing irregular shape. Automatic matching of templates to cone beam CT (CBCT) projection images was performed to known marker positions in phantom. In patient data, automatic matching was compared to manual matching as an approximate ground truth. Positional discrepancy between automatic and manual matching of less than 2 mm was assumed as the criterion for successful tracking. Tracking success rates were examined in kV projection images from 22 CBCT scans of four pancreas, six gastroesophageal junction, and one lung cancer patients. Each patient had at least one irregularly shaped radiopaque marker implanted in or near the tumor. In addition, automatic tracking was tested in intrafraction kV images of three lung cancer patients with irregularly shaped markers during 11 volumetric modulated arc treatments. Purpose-built software developed at our institution was used to create marker templates and track the markers embedded in kV images. Results: Phantom studies showed mean ± standard deviation measurement uncertainty of automatic registration to be 0.14 ± 0.07 mm and 0.17 ± 0.08 mm for Visicoil and gold cylindrical markers, respectively. The mean success rate of automatic tracking with CBCT projections (11 frames per second, fps) of pancreas, gastroesophageal junction, and lung cancer patients was 100%, 99.1% (range 98%–100%), and 100%, respectively. With intrafraction images (approx. 0.2 fps) of lung cancer patients, the success rate was 98.2% (range 97%–100%), and 94.3% (range 93%–97%) using templates from 1.25 mm and 2.5 mm slice spacing CT scans, respectively. Correction of intermarker relative position was found to improve the success rate in two out of eight patients analyzed. Conclusions: The proposed method can track arbitrary marker shapes in kV images using templates generated from a breath-hold CT acquired at simulation. The studies indicate its feasibility for tracking tumor motion during rotational treatment. Investigation of the causes of misregistration suggests that its rate of incidence can be reduced with higher frequency of image acquisition, templates made from smaller CT slice spacing, and correction of changes in intermarker relative positions when they occur.« less

Kilometer-Spaced GNSS Array for Ionospheric Irregularity Monitoring

NASA Astrophysics Data System (ADS)

Su, Yang

This dissertation presents automated, systematic data collection, processing, and analysis methods for studying the spatial-temporal properties of Global Navigation Satellite Systems (GNSS) scintillations produced by ionospheric irregularities at high latitudes using a closely spaced multi-receiver array deployed in the northern auroral zone. The main contributions include 1) automated scintillation monitoring, 2) estimation of drift and anisotropy of the irregularities, 3) error analysis of the drift estimates, and 4) multi-instrument study of the ionosphere. A radio wave propagating through the ionosphere, consisting of ionized plasma, may suffer from rapid signal amplitude and/or phase fluctuations known as scintillation. Caused by non-uniform structures in the ionosphere, intense scintillation can lead to GNSS navigation and high-frequency (HF) communication failures. With specialized GNSS receivers, scintillation can be studied to better understand the structure and dynamics of the ionospheric irregularities, which can be parameterized by altitude, drift motion, anisotropy of the shape, horizontal spatial extent and their time evolution. To study the structuring and motion of ionospheric irregularities at the sub-kilometer scale sizes that produce L-band scintillations, a closely-spaced GNSS array has been established in the auroral zone at Poker Flat Research Range, Alaska to investigate high latitude scintillation and irregularities. Routinely collecting low-rate scintillation statistics, the array database also provides 100 Hz power and phase data for each channel at L1/L2C frequency. In this work, a survey of seasonal and hourly dependence of L1 scintillation events over the course of a year is discussed. To efficiently and systematically study scintillation events, an automated low-rate scintillation detection routine is established and performed for each day by screening the phase scintillation index. The spaced-receiver technique is applied to cross-correlated phase and power measurements from GNSS receivers. Results of horizontal drift velocities and anisotropy ellipses derived from the parameters are shown for several detected events. Results show the possibility of routinely quantifying ionospheric irregularities by drifts and anisotropy. Error analysis on estimated properties is performed to further evaluate the estimation quality. Uncertainties are quantified by ensemble simulation of noise on the phase signals carried through to the observations of the spaced-receiver linear system. These covariances are then propagated through to uncertainties on drifts. A case study of a single scintillating satellite observed by the array is used to demonstrate the uncertainty estimation process. The distributed array is used in coordination with other measuring techniques such as incoherent scatter radar and optical all-sky imagers. These scintillations are correlated with auroral activity, based on all-sky camera images. Measurements and uncertainty estimates made over a 30-minute period are made and compared to a collocated incoherent scatter radar, and show good agreement in horizontal drift speed and direction during periods of scintillation for cases when the characteristic velocity is less than the drift velocity. The methods demonstrated are extensible to other zones and other GNSS arrays of varying size, number, ground distribution, and transmitter frequency.

Volume Quantification of Acute Infratentorial Hemorrhage with Computed Tomography: Validation of the Formula 1/2ABC and 2/3SH

PubMed Central

Zhang, Yunyun; Yan, Jing; Fu, Yi; Chen, Shengdi

2013-01-01

Objective To compare the accuracy of formula 1/2ABC with 2/3SH on volume estimation for hypertensive infratentorial hematoma. Methods One hundred and forty-seven CT scans diagnosed as hypertensive infratentorial hemorrhage were reviewed. Based on the shape, hematomas were categorized as regular or irregular. Multilobular was defined as a special shape of irregular. Hematoma volume was calculated employing computer-assisted volumetric analysis (CAVA), 1/2ABC and 2/3SH, respectively. Results The correlation coefficients between 1/2ABC (or 2/3SH) and CAVA were greater than 0.900 in all subgroups. There were neither significant differences in absolute values of volume deviation nor percentage deviation between 1/2ABC and 2/3SH for regular hemorrhage (P>0.05). While for cerebellar, brainstem and irregular hemorrhages, the absolute values of volume deviation and percentage deviation by formula 1/2ABC were greater than 2/3SH (P<0.05). 1/2ABC and 2/3SH underestimated hematoma volume each by 10% and 5% for cerebellar hemorrhage, 14% and 9% for brainstem hemorrhage, 19% and 16% for regular hemorrhage, 9% and 3% for irregular hemorrhage, respectively. In addition, for the multilobular hemorrhage, 1/2ABC underestimated the volume by 9% while 2/3SH overestimated it by 2%. Conclusions For regular hemorrhage volume calculation, the accuracy of 2/3SH is similar to 1/2ABC. While for cerebellar, brainstem or irregular hemorrhages (including multilobular), 2/3SH is more accurate than 1/2ABC. PMID:23638025

Permian-Triassic boundary microbialites at Zuodeng Section, Guangxi Province, South China: Geobiology and palaeoceanographic implications

NASA Astrophysics Data System (ADS)

Fang, Yuheng; Chen, Zhong-Qiang; Kershaw, Stephen; Yang, Hao; Luo, Mao

2017-05-01

A previously unknown microbialite bed in the Permian-Triassic (P-Tr) boundary beds of Zuodeng section, Tiandong County, Guangxi, South China comprises a thin (5 cm maximum thickness) stromatolite in the lower part and the remaining 6 m is thrombolite. The Zuodeng microbialite has a pronounced irregular contact between the latest Permian bioclastic limestone and microbialite, as in other sites in the region. The stromatolite comprises low-relief columnar and broad domal geometries, containing faint laminations. The thrombolite displays an irregular mixture of sparitic dark coloured altered microbial fabric and light coloured interstitial sediment in polished blocks. Abundant microproblematic calcimicrobe structures identified here as Gakhumella are preserved in dark coloured laminated areas of the stromatolite and sparitic areas in thrombolites (i.e. the calcimicrobial part, not the interstitial sediment) and are orientated perpendicular to stromatolitic laminae. Each Gakhumella individual has densely arranged segments, which form a column- to fan-shaped structure. Single segments are arch-shaped and form a thin chamber between segments. Gakhumella individuals in the stromatolite and thrombolite are slightly different from each other, but are readily distinguished from the Gakhumella- and Renalcis-like fossils reported from other P-Tr boundary microbialites in having a smaller size, unbranching columns and densely arranged, arch-shaped segments. Renalcids usually possess a larger body size and branching, lobate outlines. Filament sheath aggregates are also observed in the stromatolite and they are all orientated in one direction. Both Gakhumella and filament sheath aggregates may be photosynthetic algae, which may have played an important role in constructing the Zuodeng microbialites. Other calcimicrobes in the Zuodeng microbialite are spheroids, of which a total of five morphological types are recognized from both stromatolite and thrombolite: (1) sparry calcite spheroid without outer sheaths, (2) a large sparry calcite nucleus coated with a thin sparry calcite sheath, (3) a large nucleus of micrite framboid aggregates rimmed by a thin sparry calcite sheath (bacterial clump-like spheroids), (4) a large nucleus of micrite framboid aggregates coated with a thin micritic sheath, and (5) a small sparry nuclei rimmed by coarse-grained, radiated euhedral rays. The irregular contact beneath the Zuodeng microbialites is interpreted as a subaerial exposure surface due to regional regression in South China. The demise of the Zuodeng microbialites may have been due to rapid rise in sea-level because they grew in relatively shallow marine conditions and are overlain by muddy limestones containing pelagic conodonts. Also siliciclastic content increases above the microbialite, suggesting a possible climate-related increase in weathering as the transgression progressed.

A distinctly disorganised dwarf

NASA Image and Video Library

2016-03-28

Despite being less famous than their elliptical and spiral galactic cousins, irregular dwarf galaxies, such as the one captured in this NASA/ESA Hubble Space Telescope image, are actually one of the most common types of galaxy in the Universe. Known as UGC 4459, this dwarf galaxy is located approximately 11 million light-years away in the constellation of Ursa Major (The Great Bear), a constellation that is also home to the Pinwheel Galaxy (M101), the Owl Nebula (M97), Messier 81, Messier 82 and several other galaxies all part of the M81 group. UGC 4459’s diffused and disorganised appearance is characteristic of an irregular dwarf galaxy. Lacking a distinctive structure or shape, irregular dwarf galaxies are often chaotic in appearance, with neither a nuclear bulge — a huge, tightly packed central group of stars — nor any trace of spiral arms — regions of stars extending from the centre of the galaxy. Astronomers suspect that some irregular dwarf galaxies were once spiral or elliptical galaxies, but were later deformed by the gravitational pull of nearby objects. Rich with young blue stars and older red stars, UGC 4459 has a stellar population of several billion. Though seemingly impressive, this is small when compared to the 200 to 400 billion stars in the Milky Way! Observations with Hubble have shown that because of their low masses, star formation is very low compared to larger galaxies. Only very little of their original gas has been turned into stars. Thus, these small galaxies are interesting to study to better understand primordial environments and the star formation process.

Retrospective Methods Analysis of Semiautomated Intracerebral Hemorrhage Volume Quantification From a Selection of the STICH II Cohort (Early Surgery Versus Initial Conservative Treatment in Patients With Spontaneous Supratentorial Lobar Intracerebral Haematomas).

PubMed

Haley, Mark D; Gregson, Barbara A; Mould, W Andrew; Hanley, Daniel F; Mendelow, Alexander David

2018-02-01

The ABC/2 method for calculating intracerebral hemorrhage (ICH) volume has been well validated. However, the formula, derived from the volume of an ellipse, assumes the shape of ICH is elliptical. We sought to compare the agreement of the ABC/2 formula with other methods through retrospective analysis of a selection of the STICH II cohort (Early Surgery Versus Initial Conservative Treatment in Patients With Spontaneous Supratentorial Lobar Intracerebral Haematomas). From 390 patients, 739 scans were selected from the STICH II image archive based on the availability of a CT scan compatible with OsiriX DICOM viewer. ICH volumes were calculated by the reference standard semiautomatic segmentation in OsiriX software and compared with calculated arithmetic methods (ABC/2, ABC/2.4, ABC/3, and 2/3SC) volumes. Volumes were compared by difference plots for specific groups: randomization ICH (n=374), 3- to 7-day postsurgical ICH (n=206), antithrombotic-associated ICH (n=79), irregular-shape ICH (n=703) and irregular-density ICH (n=650). Density and shape were measured by the Barras ordinal shape and density groups (1-5). The ABC/2.4 method had the closest agreement to the semiautomatic segmentation volume in all groups, except for the 3- to 7-day postsurgical ICH group where the ABC/3 method was superior. Although the ABC/2 formula for calculating elliptical ICH is well validated, it must be used with caution in ICH scans where the elliptical shape of ICH is a false assumption. We validated the adjustment of the ABC/2.4 method in randomization, antithrombotic-associated, heterogeneous-density, and irregular-shape ICH. URL: http://www.isrctn.com/ISRCTN22153967. Unique identifier: ISRCTN22153967. © 2018 American Heart Association, Inc.

Hard convex lens-shaped particles: Densest-known packings and phase behavior

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

Cinacchi, Giorgio, E-mail: giorgio.cinacchi@uam.es; Torquato, Salvatore, E-mail: torquato@princeton.edu

2015-12-14

By using theoretical methods and Monte Carlo simulations, this work investigates dense ordered packings and equilibrium phase behavior (from the low-density isotropic fluid regime to the high-density crystalline solid regime) of monodisperse systems of hard convex lens-shaped particles as defined by the volume common to two intersecting congruent spheres. We show that, while the overall similarity of their shape to that of hard oblate ellipsoids is reflected in a qualitatively similar phase diagram, differences are more pronounced in the high-density crystal phase up to the densest-known packings determined here. In contrast to those non-(Bravais)-lattice two-particle basis crystals that are themore » densest-known packings of hard (oblate) ellipsoids, hard convex lens-shaped particles pack more densely in two types of degenerate crystalline structures: (i) non-(Bravais)-lattice two-particle basis body-centered-orthorhombic-like crystals and (ii) (Bravais) lattice monoclinic crystals. By stacking at will, regularly or irregularly, laminae of these two crystals, infinitely degenerate, generally non-periodic in the stacking direction, dense packings can be constructed that are consistent with recent organizing principles. While deferring the assessment of which of these dense ordered structures is thermodynamically stable in the high-density crystalline solid regime, the degeneracy of their densest-known packings strongly suggests that colloidal convex lens-shaped particles could be better glass formers than colloidal spheres because of the additional rotational degrees of freedom.« less

Silver iodide microstructures of a uniform towerlike shape: morphology purification via a chemical dissolution, simultaneously boosted catalytic durability, and enhanced catalytic performances.

PubMed

Lei, Bin; Zhu, Mingshan; Chen, Penglei; Chen, Chuncheng; Ma, Wanhong; Li, Tiesheng; Liu, Minghua

2014-03-26

The fabrication of microstructures/nanostructures of a uniform yet well-defined morphology has attracted broad interest from a variety of fields of advanced functional materials, especially catalysts. Most of the conventional methods generally suffer from harsh synthesis conditions, requirement of bulky apparatus, or incapability of scalable production, etc. To meet these formidable challenges, it is strongly desired to develop a facile, cost-effective, scalable method to fulfill a morphology purification. By a precipitation reaction between AgNO3 and KI, we report that irregular AgI structures, or their mixture with towerlike AgI architectures could be fabricated. Compared to the former, the mixed structures exhibit enhanced catalytic reactivity toward the photodegradation of Methyl Orange pollutant. However, its catalytic durability, which is one of the most crucial criteria that are required by superior catalysts, is poor. We further show that the irregular structures could be facilely removed from the mixture via a KI-assisted chemical dissolution, producing AgI of a uniform towerlike morphology. Excitingly, after such simple morphology purification, our towerlike AgI displays not only a boosted catalytic durability but also an enhanced catalytic reactivity. Our chemical dissolution-based morphology purification protocol might be extended to other systems, wherein high-quality advanced functional materials of desired properties might be developed.

Universal router concept

NASA Technical Reports Server (NTRS)

Pesch, W. A.

1970-01-01

Portable universal router can cut holes of large diameter and irregular shapes, machine recesses, and drill holes with certain edge-distance limitations. Rectangular and round holes may be cut without a template.

Anisotropic nanocolloids: self-assembly, interfacial adsorption, and electrostatic screening

NASA Astrophysics Data System (ADS)

de Graaf, J.

2012-06-01

In this thesis we consider the influence of anisotropy on the behaviour of colloids using theory and simulations. The recent increase in the ability to synthesize anisotropic particles (cubes, caps, octapods, etc.) has led to samples of sufficient quality to perform self-assembly experiments. Our investigation is therefore particularly relevant to current and future experimental studies of colloids. We examine several topics for which shape anisotropy plays an important role: (1.) - Interfacial adsorption. We introduced the triangular-tessellation technique to approximate the surface areas and line length which are associated with a plane-particle intersection. Our method allowed us to determine the free energy of adsorption for a single irregular colloid with heterogeneous surface properties adsorbed at a flat liquid-liquid interface in the Pieranski approximation. Ellipsoids only adsorbed at the interface perpendicular to the interfacial normal. However, for cylinders we could find a metastable adsorption minimum corresponding to parallel adsorption. We also considered the possible time dependence of the adsorption process using simple dynamics. Finally, we studied the adsorption of truncated nanocubes with a contact-angle surface pattern and we observed that there are three prototypical equilibrium adsorption configurations for these particles. (2.) - Crystal-structure prediction. We extended an existing crystal-structure-prediction algorithm to predict structures for systems comprised of irregular hard particles. Using this technique we examined the high-density crystal structures for 17 irregular nonconvex shapes and we confirmed several mathematical conjectures for the packings of a large set of 142 convex polyhedra. We also proved that we have obtained the densest configurations for rhombicuboctahedra and rhombic enneacontrahedra, respectively. Moreover, we considered a family of truncated cubes, which interpolates between a cube and an octahedron, for which we obtained a fascinating richness in crystal structures. For the octahedron we determined the equation of state and we obtained a liquid, a (metastable) body-centred-cubic rotator phase, and a crystal phase. (3.) - Octapod hierarchical self-assembly. We analysed the recently observed hierarchical self-assembly of octapod-shaped nanocrystals (octapods) into three-dimensional (3D) superstructures. We constructed an empirical simulation model capable of reproducing the initial chain-formation step of the self-assembly. The van-der-Waals (vdW) interactions between octapods suspended in an (a)polar medium were obtained by means of a Hamaker-de-Boer-type integration and the nature of these interactions allowed us to justify elements of our empirical model. We used the theoretical vdW calculation, together with the experimental and simulation results, to formulate a mechanism which explained the observed self-assembly in terms of the solvent-dependence and directionality of the octapod-octapod interactions. (4.) - Ionic screening of charged Janus particles. We studied the screening of charged Janus particles in an electrolyte by primitive-model Monte Carlo (MC) simulations for a wide variety of parameters. We also introduced a method to compare these results to the predictions of nonlinear Poisson-Boltzmann (PB) theory. The comparison of MC and PB results allowed us to probe the range of validity of the PB approximation. This range of validity corresponds well to the range that was predicted by field-theoretical studies of homogeneously charged flat surfaces.

Influence of emulsifiers on the characteristics of polyurethane structures used as drug carrier

PubMed Central

2013-01-01

Background Emulsifiers have a significant role in the emulsion polymerization by reducing the interfacial tension thus increasing the stability of colloidal dispersions of polymer nanostructures. This study evaluates the impact of four emulsifiers on the characteristics of polyurethane hollow structures used as drug delivery system. Results Polyurethane (PU) structures with high stability and sizes ranging from nano- to micro-scale were obtained by interfacial polyaddition combined with spontaneous emulsification. The pH of PU aqueous solutions (0.1% w/w) was slightly acidic, which is acceptable for products intended to be used on human skin. Agglomerated structures with irregular shapes were observed by scanning electron microscopy. The synthesized structures have melting points between 245-265°C and reveal promising results in different evaluations (TEWL, mexametry) on murine skin. Conclusions In this study hollow PU structures of reduced noxiousness were synthesized, their size and stability being influenced by emulsifiers. Such structures could be used in the pharmaceutical field as future drug delivery systems. PMID:23575277

Impaired capacity of cerebellar patients to perceive and learn two-dimensional shapes based on kinesthetic cues.

PubMed

Shimansky, Y; Saling, M; Wunderlich, D A; Bracha, V; Stelmach, G E; Bloedel, J R

1997-01-01

This study addresses the issue of the role of the cerebellum in the processing of sensory information by determining the capability of cerebellar patients to acquire and use kinesthetic cues received via the active or passive tracing of an irregular shape while blindfolded. Patients with cerebellar lesions and age-matched healthy controls were tested on four tasks: (1) learning to discriminate a reference shape from three others through the repeated tracing of the reference template; (2) reproducing the reference shape from memory by drawing blindfolded; (3) performing the same task with vision; and (4) visually recognizing the reference shape. The cues used to acquire and then to recognize the reference shape were generated under four conditions: (1) "active kinesthesia," in which cues were acquired by the blindfolded subject while actively tracing a reference template; (2) "passive kinesthesia," in which the tracing was performed while the hand was guided passively through the template; (3) "sequential vision," in which the shape was visualized by the serial exposure of small segments of its outline; and (4) "full vision," in which the entire shape was visualized. The sequential vision condition was employed to emulate the sequential way in which kinesthetic information is acquired while tracing the reference shape. The results demonstrate a substantial impairment of cerebellar patients in their capability to perceive two-dimensional irregular shapes based only on kinesthetic cues. There also is evidence that this deficit in part relates to a reduced capacity to integrate temporal sequences of sensory cues into a complete image useful for shape discrimination tasks or for reproducing the shape through drawing. Consequently, the cerebellum has an important role in this type of sensory information processing even when it is not directly associated with the execution of movements.

Low Vision Rehabilitation Intervention for People with Ring Scotomas

ERIC Educational Resources Information Center

Schoessow, Kimberly A.; Gilbert, Leah M.; Jackson, Mary Lou

2010-01-01

Central scotomas--areas of the nonseeing retina within the central 20 degrees of the visual field--are present in approximately 90% of vision rehabilitation patients. They vary in size and shape and can be small or large, symmetrical or asymmetrical, round or irregularly shaped. Most central scotomas border fixation on one side and can be overcome…

Shaping-lathe headrig now commercially available

Treesearch

P. Koch

1975-01-01

On September 12, 1975, twenty-five sawmillers from throughout North America watched as a new headrig produced cants of various shapes and a usable residue of flakes from logs of irregular contour. The demonstration at the Stetson-Ross plant in Seattle, Washington, was the unveiling of the commercial model of a design introduced by the Southern Forest Experiment Station...

Optimized micromirror arrays for adaptive optics

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

Michalicek, M. Adrian

This paper describes the design, layout, fabrication, and surface characterization of highly optimized surface micromachined micromirror devices. Design considerations and fabrication capabilities are presented. These devices are fabricated in the state-of-the-art, four-level, planarized, ultra-low-stress polysilicon process available at Sandia National Laboratories known as the Sandia Ultra-planar Multi-level MEMS Technology (SUMMiT). This enabling process permits the development of micromirror devices with near-ideal characteristics that have previously been unrealizable in standard three-layer polysilicon processes. The reduced 1 {mu}m minimum feature sizes and 0.1 {mu}m mask resolution make it possible to produce dense wiring patterns and irregularly shaped flexures. Likewise, mirror surfaces canmore » be uniquely distributed and segmented in advanced patterns and often irregular shapes in order to minimize wavefront error across the pupil. The ultra-low-stress polysilicon and planarized upper layer allow designers to make larger and more complex micromirrors of varying shape and surface area within an array while maintaining uniform performance of optical surfaces. Powerful layout functions of the AutoCAD editor simplify the design of advanced micromirror arrays and make it possible to optimize devices according to the capabilities of the fabrication process. Micromirrors fabricated in this process have demonstrated a surface variance across the array from only 2{endash}3 nm to a worst case of roughly 25 nm while boasting active surface areas of 98{percent} or better. Combining the process planarization with a {open_quotes}planarized-by-design{close_quotes} approach will produce micromirror array surfaces that are limited in flatness only by the surface deposition roughness of the structural material. Ultimately, the combination of advanced process and layout capabilities have permitted the fabrication of highly optimized micromirror arrays for adaptive optics. {copyright} {ital 1999 American Institute of Physics.}« less

Visuomotor learning in cerebellar patients.

PubMed

Timmann, D; Shimansky, Y; Larson, P S; Wunderlich, D A; Stelmach, G E; Bloedel, J R

1996-11-01

The aim of the present study was to demonstrate that patients with pathology affecting substantial regions of the cerebellum can improve their performance in a series of two-dimensional tracing tasks, thus supporting the view that this type of motor behavior can be acquired even when the integrity of this structure is compromised. Eight patients with chronic, isolated cerebellar lesions and eight age- and sex-matched healthy controls were tested. Three patients had mild, five had moderate upper limb ataxia. The experiment was divided into two parts. In the first, subjects traced an irregularly shaped outline over 20 consecutive trials ('Trace 1' task). Next, subjects were asked to redraw the object without any underlying template as a guide ('Memory 1' task). In the second part of the study, subjects were asked to trace a different, irregularly shaped outline over 20 consecutive trials ('Trace 2' task). Next, they were required to redraw it by memory with its axis rotated 90 degrees ('Memory 2' task). In each of the memory tasks the template was placed over the drawn image after each trial and shown to the subjects. The error of performance was determined by calculating three different measurements, each focused on different aspects of the task. Based on these measurements, the cerebellar patients showed improvement in both memory tasks. In the 'Memory 1' task the calculated error decreased significantly for the patients with mild ataxia. In the 'Memory 2' task all cerebellar patients improved their performance substantially enough to reduce significantly the magnitude of all three error measurements. The experiments demonstrate that patients with cerebellar lesions are capable of improving substantially their performance of a complex motor task involving the recall of memorized shapes and the visuomotor control of a tracing movement.

Spongy Surface

NASA Image and Video Library

2015-06-02

NASA Cassini imaging scientists processed this view of Saturn moon Hyperion, taken during a close flyby on May 31, 2015. This flyby marks the mission final close approach to Saturn largest irregularly shaped moon.

Residual Cap

NASA Image and Video Library

2006-05-10

This MOC image shows a summertime view of the south polar residual cap of Mars. In this image, mesas composed largely of solid carbon dioxide are separated from one another by irregularly-shaped depressions

An investigation of water production rates by irregularly shaped cometary nuclei.

NASA Astrophysics Data System (ADS)

Gutierrez, P. J.; Ortiz, J. L.; Rodrigo, R.; Lopez-Moreno, J. J.

1999-09-01

A computer code has been developed to derive water production rates for rotating irregularly shaped nuclei with topography (both craters and mountains) as a function of heliocentric distance. The code solves the surface energy balance equation including heat diffusion in the normal direction and taking into account shadowing effects, for any combination of orbital parameters, spin axis orientation, rotation period, and physical properties of the nucleus (geometric albedo, emissivity, thermodynamical properties). Preliminary results are presented for several representative objects. The research described in this abstract is being carried out at the Instituto de Astrofísica de Andalucía and is supported by the Comision Interministerial de Ciencia y Tecnología under contracts ESP96-0623 and ESP97-1773-CO3-01.

Irregularities at Sub-Auroral, Middle, and Low Latitudes in the Topside Ionosphere Observed During Geomagnetic Storms with the DEMETER and DMSP Satellites

NASA Technical Reports Server (NTRS)

Pfaff, R.; Liebrecht, C.; Berthelier, J.-J.; Parrot, M.; Lebreton, J.-P.

2008-01-01

Detailed observations of the plasma structure and irregularities that characterize the topside ionosphere at sub-auroral, middle, and low-latitudes are presented that were gathered with probes on the DEMETER and DMSP satellites during geomagnetic storms. Data from successive orbits reveal how the density structure and irregularities evolve with changes in the Dst. The observations reveal that precisely during the main phase of severe geomagnetic storms, increased ambient plasma densities and broad regions of irregularities are observed at 700 km, initially at storm commencement near the magnetic equator and then extending to mid- and sub-auroral latitudes within the approximately 8 hour period corresponding to the negative Dst excursions. Furthermore, intense, broadband electric and magnetic field irregularities are often observed at sub-auroral latitudes and are typically associated with the trough region and its poleward plasma density gradient. The observations provide a general framework showing how low, mid, and sub-auroral latitude plasma density structuring and associated irregularities respond to geomagnetic storms.

Farewell to Hyperion

NASA Image and Video Library

2015-06-02

NASA Cassini imaging scientists processed this view of Saturn moon Hyperion, taken during a close flyby on May 31, 2015. This flyby marks the mission final close approach to Saturn largest irregularly shaped moon.

7 CFR 51.1317 - Well formed.

Code of Federal Regulations, 2010 CFR

2010-01-01

... FRESH FRUITS, VEGETABLES AND OTHER PRODUCTS 1,2 (INSPECTION, CERTIFICATION, AND STANDARDS) United States... characteristic of the variety. Slight irregularities of shape from type which do not appreciably detract from the...

Shaping planetary nebulae with jets in inclined triple stellar systems

NASA Astrophysics Data System (ADS)

Akashi, Muhammad; Soker, Noam

2017-08-01

We conduct three-dimensional hydrodynamical simulations of two opposite jets launched obliquely to the orbital plane around an asymptotic giant branch (AGB) star and within its dense wind, and demonstrate the formation of a 'messy' planetary nebula (PN), namely a PN lacking any type of symmetry (I.e. highly irregular). In building the initial conditions, we assume that a tight binary system orbits the AGB star and that the orbital plane of the tight binary system is inclined to the orbital plane of the binary system and the AGB star (the triple system plane). We further assume that the accreted mass on to the tight binary system forms an accretion disc around one of the stars and that the plane of the disc is tilted to the orbital plane of the triple system. The highly asymmetrical and filamentary structures that we obtain support the notion that messy PNe might be shaped by triple stellar systems.

Small satellites

NASA Technical Reports Server (NTRS)

Thomas, P.; Veverka, J.; Dermott, S.

1986-01-01

Satellites smaller than Mimas (r = 195 km) are distinguished by irregular overall shapes and by rough limb topography. Material properties and impact cratering dominate the shaping of these objects. Long fragmentation histories can produce a variety of internal structures, but so far there is no direct evidence that any small satellite is an equilibrium ellipsoid made up of noncohesive gravitationally bound rubble. One many bodies that orbit close to their primary the tidal and rotational components of surface gravity strongly affect the directions of local g and thereby affect the redistribution of regolith by mass wasting. Downslope movement of regolith is extensive on Deimos, and is probably effective on many other small satellites. It is shown that in some cases observed patterns of downslope mass wasting cold produce useful constraints on the satellite's mean density. The diversity of features seen in the few high-resolution images of small satellites currently available suggests that these objects have undergone complex histories of cratering, fragmentation, and regolith evolution.

INFERRING THE CORONAL DENSITY IRREGULARITY FROM EUV SPECTRA

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

Hahn, M.; Savin, D. W., E-mail: mhahn@astro.columbia.edu

2016-09-20

Understanding the density structure of the solar corona is important for modeling both coronal heating and the solar wind. Direct measurements are difficult because of line-of-sight integration and possible unresolved structures. We present a new method for quantifying such structures using density-sensitive extreme ultraviolet line intensities to derive a density irregularity parameter, a relative measure of the amount of structure along the line of sight. We also present a simple model to relate the inferred irregularities to physical quantities, such as the filling factor and density contrast. For quiet-Sun regions and interplume regions of coronal holes, we find a densitymore » contrast of at least a factor of 3–10 and corresponding filling factors of about 10%–20%. Our results are in rough agreement with other estimates of the density structures in these regions. The irregularity diagnostic provides a useful relative measure of unresolved structure in various regions of the corona.« less

Are Complex Magnetic Field Structures Responsible for the Confined X-class Flares in Super Active Region 12192?

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

Zhang, Jun; Li, Ting; Chen, Huadong, E-mail: zjun@nao.cas.cn, E-mail: hdchen@nao.cas.cn

From 2014 October 19 to 27, six X-class flares occurred in super active region (AR) 12192. They were all confined flares and were not followed by coronal mass ejections. To examine the structures of the four flares close to the solar disk center from October 22 to 26, we firstly employ composite triple-time images in each flare process to display the stratified structure of these flare loops. The loop structures of each flare in both the lower (171 Å) and higher (131 Å) temperature channels are complex, e.g., the flare loops rooting at flare ribbons are sheared or twisted (enwound)more » together, and the complex structures were not destroyed during the flares. For the first flare, although the flare loop system appears as a spindle shape, we can estimate its structures from observations, with lengths ranging from 130 to 300 Mm, heights from 65 to 150 Mm, widths at the middle part of the spindle from 40 to 100 Mm, and shear angles from 16° to 90°. Moreover, the flare ribbons display irregular movements, such as the left ribbon fragments of the flare on October 22 sweeping a small region repeatedly, and both ribbons of the flare on October 26 moved along the same direction instead of separating from each other. These irregular movements also imply that the corresponding flare loops are complex, e.g., several sets of flare loops are twisted together. Although previous studies have suggested that the background magnetic fields prevent confined flares from erupting,based on these observations, we suggest that complex flare loop structures may be responsible for these confined flares.« less

Organizational Learning and the Marine Corps: The Counterinsurgency Campaign in Iraq (CIWAG Case Study on Irregular Warfare and Armed Groups)

DTIC Science & Technology

2012-01-01

and institutional memory are seen as keys to their success in Anbar. Ten lessons are drawn from this case that relate to the future irregular conflict...organizational culture. Specialists on the topic like Richard Downie find that institutional memory and history, key factors that shape organizational culture...and practiced” they will “form … the organization’s institutional memory .” That memory is then socialized into its members, making the organization

The Haw River Sites: Archaeological Investigations at Two Stratified Sites in the North Carolina Piedmont. Volume II.

DTIC Science & Technology

1982-04-01

area of irregular shape. The area was filled with a mixture of tan alluvial sand and red clay. The irregular outline of the depression would suggest...suggests possible association of skinning racks. In the Navajo case (Binford and Bertram 1977) the use of the ax was greatly facilited by the suspension...llIlllllllllhll IIIIIIIIIIIIIIfllfllf mh•hE h E 1.5 MICROCOPY RESOLUTION TEST CHART NATIONAL BUREAU OF STANDA r I9. A IU ... . ... ... *II l .. .. .... . . I

Effect of filler properties in composite resins on light transmittance characteristics and color.

PubMed

Arikawa, Hiroyuki; Kanie, Takahito; Fujii, Koichi; Takahashi, Hideo; Ban, Seiji

2007-01-01

The purpose of this investigation was to examine the effect of filler particle size and shape as well as filler content on light transmittance characteristics and color of experimental composite resins. A mixture of 30 mol% Bis-GMA and 70 mol% TEGDMA was prepared as a base monomer and to which a photoinitiator (camphorquinone) and a co-initiator (N,N-dimethylaminoethyl methacrylate) were added. Four different irregular- and spherical-shaped filler types with an average particle size of 1.9-11.1 microm were added to the mixture in three different filler contents of 20, 30, and 40 vol%. Light transmittance characteristics including light diffusion characteristics of the materials were evaluated. Color values and color differences among filler contents of the materials were also determined. Materials containing smaller and irregular-shaped fillers showed higher light transmittance and diffusion angle distribution with a sharper peak, as compared with those containing larger and spherical-shape fillers. It was also found that there was a significant correlation between the specific surface area of fillers and the color difference of the materials containing the fillers. Our results indicated that the shape of filler particles, as well as particle size and filler content, significantly affected the light transmittance characteristics--including light diffusion characteristics--and color of composite resins.

Extended Multiscale Image Segmentation for Castellated Wall Management

NASA Astrophysics Data System (ADS)

Sakamoto, M.; Tsuguchi, M.; Chhatkuli, S.; Satoh, T.

2018-05-01

Castellated walls are positioned as tangible cultural heritage, which require regular maintenance to preserve their original state. For the demolition and repair work of the castellated wall, it is necessary to identify the individual stones constituting the wall. However, conventional approaches using laser scanning or integrated circuits (IC) tags were very time-consuming and cumbersome. Therefore, we herein propose an efficient approach for castellated wall management based on an extended multiscale image segmentation technique. In this approach, individual stone polygons are extracted from the castellated wall image and are associated with a stone management database. First, to improve the performance of the extraction of individual stone polygons having a convex shape, we developed a new shape criterion named convex hull fitness in the image segmentation process and confirmed its effectiveness. Next, we discussed the stone management database and its beneficial utilization in the repair work of castellated walls. Subsequently, we proposed irregular-shape indexes that are helpful for evaluating the stone shape and the stability of the stone arrangement state in castellated walls. Finally, we demonstrated an application of the proposed method for a typical castellated wall in Japan. Consequently, we confirmed that the stone polygons can be extracted with an acceptable level. Further, the condition of the shapes and the layout of the stones could be visually judged with the proposed irregular-shape indexes.

Canuleia Crater

NASA Image and Video Library

2012-04-24

This image from NASA Dawn spacecraft of asteroid Vesta shows Canuleia crater, a large, irregularly shaped crater. Other interesting features of Canuleia include the diffuse bright material that is both inside and outside of its rim.

Capturing Nix and Hydra

NASA Image and Video Library

2015-07-21

NASA New Horizons spacecraft captured these images of Pluto moon Nix which shows a reddish spot that has attracted the interest of the mission scientists left, and the small, irregularly shaped moon Hydra right.

Macroscopic and stereomicroscopic comparison of hacking trauma of bones before and after carbonization.

PubMed

Alunni, Véronique; Nogueira, Luísa; Quatrehomme, Gérald

2018-03-01

This experimental study examined lesions produced by a hatchet on pig femurs before and after carbonization. A total of 30 lesions were produced and analyzed using stereomicroscopy and then reexamined after carbonization. Not only was the sharp-blunt mechanism of the hacking trauma (V-shape, regularity of one edge, irregularity of the other edge, upraising, lateral pushing back, fossae dug laterally to the edge) still recognizable after carbonization; in some instances, the carbonization actually enhanced the features observed. Carbonization also did not significantly alter the measurements of the lesions. Carbonization tends to alter the structure of the bone especially in areas weakened by the blunt trauma.

Analysis of a Spatial Point Pattern: Examining the Damage to Pavement and Pipes in Santa Clara Valley Resulting from the Loma Prieta Earthquake

USGS Publications Warehouse

Phelps, G.A.

2008-01-01

This report describes some simple spatial statistical methods to explore the relationships of scattered points to geologic or other features, represented by points, lines, or areas. It also describes statistical methods to search for linear trends and clustered patterns within the scattered point data. Scattered points are often contained within irregularly shaped study areas, necessitating the use of methods largely unexplored in the point pattern literature. The methods take advantage of the power of modern GIS toolkits to numerically approximate the null hypothesis of randomly located data within an irregular study area. Observed distributions can then be compared with the null distribution of a set of randomly located points. The methods are non-parametric and are applicable to irregularly shaped study areas. Patterns within the point data are examined by comparing the distribution of the orientation of the set of vectors defined by each pair of points within the data with the equivalent distribution for a random set of points within the study area. A simple model is proposed to describe linear or clustered structure within scattered data. A scattered data set of damage to pavement and pipes, recorded after the 1989 Loma Prieta earthquake, is used as an example to demonstrate the analytical techniques. The damage is found to be preferentially located nearer a set of mapped lineaments than randomly scattered damage, suggesting range-front faulting along the base of the Santa Cruz Mountains is related to both the earthquake damage and the mapped lineaments. The damage also exhibit two non-random patterns: a single cluster of damage centered in the town of Los Gatos, California, and a linear alignment of damage along the range front of the Santa Cruz Mountains, California. The linear alignment of damage is strongest between 45? and 50? northwest. This agrees well with the mean trend of the mapped lineaments, measured as 49? northwest.

Reproduction of microseism H/V spectral features using a three-dimensional complex topographical model of the sediment-bedrock interface in the Osaka sedimentary basin

NASA Astrophysics Data System (ADS)

Uebayashi, Hirotoshi; Kawabe, Hidenori; Kamae, Katsuhiro

2012-05-01

Estimating the velocity structure of microseisms based on the horizontal-to-vertical spectral ratio (HVSR) is an extremely practical means of modelling the subsurface structure necessary for strong ground motion predictions. Thus, beyond the traditional framework of the 1-D velocity structure, the HVSR, derived from observation records of microseisms (microtremors with a frequency of about 1 Hz or lower originating from ocean waves) in areas where the sediment-bedrock interface has irregular topographies, was reproduced by finite differential method (FDM)-based simulation. This study was conducted for the Osaka sedimentary basin, the sediment-bedrock interface of which is three-dimensionally complicated and contains grabens, steps and ramps, because high-precision models for this basin have been constructed based on a wide range of existing exploration information. The HVSRs of two components (the east-west direction and the north-south direction to the vertical direction) derived from the FDM simulations were both well reproduced in terms of not only the peak frequency (HVfp) but also the spectral curves for a number of observation sites above the sediment-bedrock interface with complex geological features. These results suggest that with a sufficient number of observation sites for microtremors and highly accurate a priori information on geophysical constants in the sedimentary layer that spatially serves as the reference, the irregular-shaped sediment-bedrock interface may be estimated based on how well the HVSR curves and the HVfp agree between the observations and simulations. Furthermore, the FDM simulations confirmed observed phenomena such as the polarization of the amplitude of horizontal motions and broad or 'plateau-like' HVSR peaks of microseisms in grabens and step structures. It was determined that the HVfps in areas with these strong irregularities are higher than the peak frequency of Rayleigh wave ellipticity for the fundamental mode (RHVfp) based on the 1-D velocity structure. In addition, there was a difference of about 20 per cent at most between the HVfp derived from FDM simulations and the RHVfp in areas where the depth of the sediment-bedrock interface varies only slightly.

A flexibly shaped space-time scan statistic for disease outbreak detection and monitoring.

PubMed

Takahashi, Kunihiko; Kulldorff, Martin; Tango, Toshiro; Yih, Katherine

2008-04-11

Early detection of disease outbreaks enables public health officials to implement disease control and prevention measures at the earliest possible time. A time periodic geographical disease surveillance system based on a cylindrical space-time scan statistic has been used extensively for disease surveillance along with the SaTScan software. In the purely spatial setting, many different methods have been proposed to detect spatial disease clusters. In particular, some spatial scan statistics are aimed at detecting irregularly shaped clusters which may not be detected by the circular spatial scan statistic. Based on the flexible purely spatial scan statistic, we propose a flexibly shaped space-time scan statistic for early detection of disease outbreaks. The performance of the proposed space-time scan statistic is compared with that of the cylindrical scan statistic using benchmark data. In order to compare their performances, we have developed a space-time power distribution by extending the purely spatial bivariate power distribution. Daily syndromic surveillance data in Massachusetts, USA, are used to illustrate the proposed test statistic. The flexible space-time scan statistic is well suited for detecting and monitoring disease outbreaks in irregularly shaped areas.

Structural and ultrastructural study of rat testes influenced by electromagnetic radiation.

PubMed

Almášiová, Viera; Holovská, Katarína; Cigánková, Viera; Račeková, Enikö; Fabianová, Kamila; Martončíková, Marcela

2014-01-01

This study was conducted to investigate the influence of whole-body electromagnetic radiation (EMR) on testicular parenchyma of Wistar rats. Sexually mature rats were subjected to pulsed electromagnetic field at frequency of 2.45 GHz and mean power density 2.8 mW/cm(2) by 3-h daily applications for 3 wk. Tissue samples were obtained 3 h after the last irradiation and processed by histological techniques for light and transmission electron microscopy. Testes showed apparent degenerative changes of seminiferous epithelium. The seminiferous tubules were mostly irregular in shape, and seminiferous epithelium contained a number of empty spaces of different size. Subsequently, groups of sloughed epithelial cells were often found inside the lumina of tubules. Except for relatively unchanged Sertoli cells, some locations of basal compartment of seminiferous epithelium contained shriveled Sertoli cells with dark cytoplasm. These areas showed degenerative features including necrotizing and shriveled spermatogonia surrounded by empty irregular spaces, and undulating basement membrane. The intertubular spaces were enlarged but interstitial Leydig cells did not show any marked morphological changes. Evidence demonstrates the adverse effects of EMR on testicular parenchyma in rats.

Binary asteroid orbit evolution due to primary shape deformation

NASA Astrophysics Data System (ADS)

Hirabayashi, Masatoshi; Jacobson, Seth A.; Davis, Alex

2017-10-01

About a sixth of all small asteroid systems are binary [Margot et al., Science, 2002]. Many binary asteroids consist of an elongated synchronous secondary body orbiting a fast-rotating spheroidal primary body with ridges on its equator. The primary in such systems has experienced a long-term spin-up due to the YORP effect [Vokrouhlick'y et al., Asteroid IV, 2015]. This spin-up process can make the primary reach its spin barrier inducing shape deformation processes that ease the structural condition for failure inside the primary [e.g., Holsapple, Icarus, 2010]. Earlier works have shown that structural heterogeneities in the primary such as the shape and density distribution induce asymmetric deformation [Sánchez and Scheeres, Icarus, 2016]. Here, we investigate how asymmetric shape deformation in the primary affects the mutual motion of a binary system. We use a dynamics model for an irregularly shaped binary system that accounts for possible deformation of the primary [Hirabayashi et al., LPSC, 2017]. In this model, we consider asymmetric deformation that occurs based on structural failure in the primary and thus it modifies the location of the center of mass of the system. Using 1999 KW4 as an example, we study a hypothetical case in which the primary is initially identical to the current shape [Ostro et al., Science, 2006] with an aspect ratio (AR) of 0.83 and then suddenly changes its shape to an AR of 0.76. The results show that the asymmetric deformation process and the shift of the center of mass excite the eccentricity of the mutual orbit. Considering that the original mutual orbit has an eccentricity of 0.0004, after the primary shape change the eccentricity reaches values up to 0.15. Also, since the gravity field is modified after deformation, the secondary’s spin is desynchronized from the mutual orbit. Since synchronicity is a requirement for the binary YORP (BYORP) effect, which modifies the semi-major axis of binary asteroids, a primary shape change temporarily pauses the BYORP effect, in effect lengthening the effective BYORP timescale.

Effect of Fractal Dimension on the Strain Behavior of Particulate Media

NASA Astrophysics Data System (ADS)

Altun, Selim; Sezer, Alper; Goktepe, A. Burak

2016-12-01

In this study, the influence of several fractal identifiers of granular materials on dynamic behavior of a flexible pavement structure as a particulate stratum is considered. Using experimental results and numerical methods as well, 15 different grain-shaped sands obtained from 5 different sources were analyzed as pavement base course materials. Image analyses were carried out by use of a stereomicroscope on 15 different samples to obtain quantitative particle shape information. Furthermore, triaxial compression tests were conducted to determine stress-strain and shear strength parameters of sands. Additionally, the dynamic response of the particulate media to standard traffic loads was computed using finite element modeling (FEM) technique. Using area-perimeter, line divider and box counting methods, over a hundred grains for each sand type were subjected to fractal analysis. Relationships among fractal dimension descriptors and dynamic strain levels were established for assessment of importance of shape descriptors of sands at various scales on the dynamic behavior. In this context, the advantage of fractal geometry concept to describe irregular and fractured shapes was used to characterize the sands used as base course materials. Results indicated that fractal identifiers can be preferred to analyze the effect of shape properties of sands on dynamic behavior of pavement base layers.

Structural mass irregularities and fiber volume influence on morphology and mechanical properties of unsaturated polyester resin in matrix composites

PubMed Central

Ahmed, Khalil; Nasir, Muhammad; Fatima, Nasreen; Khan, Khalid M.; Zahra, Durey N.

2014-01-01

This paper presents the comparative results of a current study on unsaturated polyester resin (UPR) matrix composites processed by filament winding method, with cotton spun yarn of different mass irregularities and two different volume fractions. Physical and mechanical properties were measured, namely ultimate stress, stiffness, elongation%. The mechanical properties of the composites increased significantly with the increase in the fiber volume fraction in agreement with the Counto model. Mass irregularities in the yarn structure were quantitatively measured and visualized by scanning electron microscopy (SEM). Mass irregularities cause marked decrease in relative strength about 25% and 33% which increases with fiber volume fraction. Ultimate stress and stiffness increases with fiber volume fraction and is always higher for yarn with less mass irregularities. PMID:26644920

Dynamics of the High-latitude Ionospheric Irregularities During the 2015 St. Patrick's Day Storm

NASA Astrophysics Data System (ADS)

Cherniak, I.; Zakharenkova, I.; Redmon, R. J.; Andrzej, K.

2015-12-01

We presents results on the study of the high-latitude ionospheric irregularities observed in worldwide GPS data during the St. Patrick's Day geomagnetic storm (March 17, 2015). Multi-site GPS observations from more than 2500 ground-based GPS stations were used to analyze the dynamics of the ionospheric irregularities in the Northern and Southern Hemispheres. The most intense ionospheric irregularities lasted for more than 24 hours starting at 07 UT of March 17. This period correlates well with an increase of the auroral Hemispheric Power index. We find hemispheric asymmetries in the intensity and spatial structure of the ionospheric irregularities. Over North America the ionospheric irregularities zone expanded equatorward below ~45°N geographic latitude. Additionally, the strong mid and high latitude GPS phase irregularities in the auroral oval were found to be related to the formation of storm enhanced density, polar tongues of ionization and deepening of the main ionospheric trough through upper atmosphere ionization by energetic particle precipitations. Significant increases in the intensity of the irregularities within the polar cap region of both hemispheres were associated with the formation and evolution of the SED/TOI structures and polar patches.

Age-dependent change in the morphology of nucleoli and methylation of genes of the Nucleolar Organizer Region in Japanese quail Coturnix japonica) model (Temminck and Schlegel, 1849) (Galliformes: Aves).

PubMed

Andraszek, Katarzyna; Gryzińska, Magdalena; Wójcik, Ewa; Knaga, Sebastian; Smalec, Elżbieta

2014-01-01

Nucleoli are the product of the activity of nucleolar organizer regions (NOR) in certain chromosomes. Their main functions are the formation of ribosomal subunits from ribosomal protein molecules and the transcription of genes encoding rRNA. The aim of the study was to determine the shape of nucleoli and analyse methylation in the gene RN28S in the spermatocytes of male Japanese quail (Coturnixjaponica) in two age groups. Nucleoli were analysed in cells of the first meiotic prophase. Their number and shape were determined and they were classified as regular, irregular or defragmented. In the cells of the young birds no defragmented nucleoli were observed, with regular and irregular nucleoli accounting for 97% and 3%, respectively. In the cells of older birds no regular nucleoli were observed, while irregular and defragmented nucleoli accounted for 37% and 67%, respectively. MSP (methylation-specific PCR) showed that the gene RN28S is methylated in both 15-week-old and 52-week-old quails. In recent years an association has been established between nucleolus morphology and cellular ageing processes.

Reynolds number effects on the aerodynamic characteristics of irregular planform wings at Mach number 0.3. [in the Ames 12 ft pressure wind tunnel

NASA Technical Reports Server (NTRS)

Kruse, R. L.; Lovette, G. H.; Spencer, B., Jr.

1977-01-01

The subsonic aerodynamic characteristics of a series of irregular planform wings were studied in wind tunnel tests conducted at M = 0.3 over a range of Reynolds numbers from 1.6 million to 26 million/m. The five basic wing planforms varied from a trapezoidal to a delta shape. Leading edge extensions, added to the basic shape, varied in approximately 5 deg increments from the wing leading edge sweep-back angle to a maximum 80 deg. Most of the tests were conducted using an NACA 0008 airfoil section with grit boundary layer trips. Tests were also conducted using an NACA 0012 airfoil section and an 8% thick wedge. In addition, the effect of free transition (no grit) was investigated. A body was used on all models.

Adaptive striping watershed segmentation method for processing microscopic images of overlapping irregular-shaped and multicentre particles.

PubMed

Xiao, X; Bai, B; Xu, N; Wu, K

2015-04-01

Oversegmentation is a major drawback of the morphological watershed algorithm. Here, we study and reveal that the oversegmentation is not only because of the irregular shapes of the particle images, which people are familiar with, but also because of some particles, such as ellipses, with more than one centre. A new parameter, the striping level, is introduced and the criterion for striping parameter is built to help find the right markers prior to segmentation. An adaptive striping watershed algorithm is established by applying a procedure, called the marker searching algorithm, to find the markers, which can effectively suppress the oversegmentation. The effectiveness of the proposed method is validated by analysing some typical particle images including the images of gold nanorod ensembles. © 2014 The Authors Journal of Microscopy © 2014 Royal Microscopical Society.

High-resolution investigation of longitudinal modes of a GaN-based blue laser diode

NASA Astrophysics Data System (ADS)

Al-Basheer, Watheq; Aljalal, Abdulaziz; Gasmi, Khaled; Adigun, Taofeek O.

2017-05-01

Typical emission spectra of GaN-based blue laser diodes are known to have irregular shapes. Hence, well-resolved study of their spectra may help in understanding the origin of their spectral shapes irregularity. In this paper, the spectra of a commercial GaN-based blue laser diode are studied as a function of injection current and temperature using a spectrometer with highresolution of 0.003-nm over the spectral region 440 - 450 nm. The obtained laser spectra are used to track the longitudinal modes evolution as a function of operating currents and temperatures as well as to precisely map single mode operation. In addition, yielded laser spectra will be utilized to evaluate few parameters related to the laser diode, such as mode spacing, optical gain, slope efficiency and threshold current at certain temperature.

Clinical, morphological, and hemodynamic independent characteristic factors for rupture of posterior communicating artery aneurysms.

PubMed

Zhang, Ying; Jing, Linkai; Liu, Jian; Li, Chuanhui; Fan, Jixing; Wang, Shengzhang; Li, Haiyun; Yang, Xinjian

2016-08-01

To identify clinical, morphological, and hemodynamic independent characteristic factors that discriminate posterior communicating artery (PCoA) aneurysm rupture status. 173 patients with single PCoA aneurysms (108 ruptured, 65 unruptured) between January 2012 and June 2014 were retrospectively collected. Patient-specific models based on their three-dimensional digital subtraction angiography images were constructed and analyzed by a computational fluid dynamic method. All variables were analyzed by univariate analysis and multivariate logistic regression analysis. Two clinical factors (younger age and atherosclerosis), three morphological factors (higher aspect ratio, bifurcation type, and irregular shape), and six hemodynamic factors (lower mean and minimum wall shear stress, higher oscillatory shear index, a greater portion of area under low wall shear stress, unstable and complex flow pattern) were significantly associated with PCoA aneurysm rupture. Independent factors characterizing the rupture status were identified as age (OR 0.956, p=0.015), irregular shape (OR 6.709, p<0.001), and minimum wall shear stress (OR 0.001, p=0.038). We combined clinical, morphological, and hemodynamic characteristics analysis and found the three strongest independent factors for PCoA aneurysm rupture were younger age, irregular shape, and low minimum wall shear stress. This may be useful for guiding risk assessments and subsequent treatment decisions for PCoA aneurysms. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Volume determination of irregularly-shaped quasi-spherical nanoparticles.

PubMed

Attota, Ravi Kiran; Liu, Eileen Cherry

2016-11-01

Nanoparticles (NPs) are widely used in diverse application areas, such as medicine, engineering, and cosmetics. The size (or volume) of NPs is one of the most important parameters for their successful application. It is relatively straightforward to determine the volume of regular NPs such as spheres and cubes from a one-dimensional or two-dimensional measurement. However, due to the three-dimensional nature of NPs, it is challenging to determine the proper physical size of many types of regularly and irregularly-shaped quasi-spherical NPs at high-throughput using a single tool. Here, we present a relatively simple method that determines a better volume estimate of NPs by combining measurements from their top-down projection areas and peak heights using two tools. The proposed method is significantly faster and more economical than the electron tomography method. We demonstrate the improved accuracy of the combined method over scanning electron microscopy (SEM) or atomic force microscopy (AFM) alone by using modeling, simulations, and measurements. This study also exposes the existence of inherent measurement biases for both SEM and AFM, which usually produce larger measured diameters with SEM than with AFM. However, in some cases SEM measured diameters appear to have less error compared to AFM measured diameters, especially for widely used IS-NPs such as of gold, and silver. The method provides a much needed, proper high-throughput volumetric measurement method useful for many applications. Graphical Abstract The combined method for volume determination of irregularly-shaped quasi-spherical nanoparticles.

Manganese modified structural and optical properties of zinc soda lime silica glasses.

PubMed

Samsudin, Nur Farhana; Matori, Khamirul Amin; Wahab, Zaidan Abdul; Fen, Yap Wing; Liew, Josephine Ying Chi; Lim, Way Foong; Mohd Zaid, Mohd Hafiz; Omar, Nur Alia Sheh

2016-03-20

A series of MnO-doped zinc soda lime silica glass systems was prepared by a conventional melt and quenching technique. In this study, the x-ray diffraction analysis was applied to confirm the amorphous nature of the glasses. Fourier transform infrared spectroscopy shows the glass network consists of MnO₄, SiO₄, and ZnO₄ units as basic structural units. The glass samples under field emission scanning electron microscopy observation demonstrated irregularity in shape and size with glassy phase-like structure. The optical absorption studies revealed that the optical bandgap (E_opt) values decrease with an increase of MnO content. Through the results of various measurements, the doping of MnO in the glass matrix had effects on the performance of the glasses and significantly improved the properties of the glass sample as a potential host for phosphor material.

Structural and magnetic properties of ytterbium substituted spinel ferrites

NASA Astrophysics Data System (ADS)

Alonizan, Norah H.; Qindeel, Rabia

2018-06-01

Chemical co-precipitation route adopted to synthesize the magnetic materials. In the present work, iron is replaced by ytterbium ion in manganese-based spinel ferrites. The yield chemically represented by MnYb x Fe2- x O4 ( x = 0.00, 0.025, 0.05, 0.075, 0.10) and its structural, magnetic and electrical properties were observed. The cubic structure of spinel ferrites was confirmed by X-ray diffraction analysis. Spherically shaped grains were perceived in SEM pictures and size lessened with the growth of ytterbium concentration. SEM profile also shows little irregularity in spherical particles. The substitution of ytterbium (Yb) results in the enhancement of electrical resistivity. The resistivity was reduced with the gradual increase in temperature from 303 to 693 K. The trend of activation energy was found to be similar to that of room temperature resistivity. The coercivity of samples was raised with Yb-ion substitution while saturation magnetization and remanence reduced.

Circular blurred shape model for multiclass symbol recognition.

PubMed

Escalera, Sergio; Fornés, Alicia; Pujol, Oriol; Lladós, Josep; Radeva, Petia

2011-04-01

In this paper, we propose a circular blurred shape model descriptor to deal with the problem of symbol detection and classification as a particular case of object recognition. The feature extraction is performed by capturing the spatial arrangement of significant object characteristics in a correlogram structure. The shape information from objects is shared among correlogram regions, where a prior blurring degree defines the level of distortion allowed in the symbol, making the descriptor tolerant to irregular deformations. Moreover, the descriptor is rotation invariant by definition. We validate the effectiveness of the proposed descriptor in both the multiclass symbol recognition and symbol detection domains. In order to perform the symbol detection, the descriptors are learned using a cascade of classifiers. In the case of multiclass categorization, the new feature space is learned using a set of binary classifiers which are embedded in an error-correcting output code design. The results over four symbol data sets show the significant improvements of the proposed descriptor compared to the state-of-the-art descriptors. In particular, the results are even more significant in those cases where the symbols suffer from elastic deformations.

Hydra Emerges from the Shadows

NASA Image and Video Library

2015-07-15

Since its discovery in 2005, Pluto's moon Hydra has been known only as a fuzzy dot of uncertain shape, size, and reflectivity. Imaging obtained during NASA's New Horizons' historic transit of the Pluto-Charon system and transmitted to Earth early this morning has definitively resolved these fundamental properties of Pluto's outermost moon. Long Range Reconnaissance Imager (LORRI) observations revealed an irregularly shaped body characterized by significant brightness variations over the surface. With a resolution of 2 miles (3 kilometers) per pixel, the LORRI image shows the tiny potato-shaped moon measures 27 miles (43 kilometers) by 20 miles (33 kilometers). Like that of Charon, Hydra's surface is probably covered with water ice, the most abundant ice in the universe. Observed within Hydra's bright regions is a darker circular structure with a diameter of approximately 6 miles (10 kilometers). Hydra's reflectivity (the percentage of incident light reflected from the surface) is intermediate between that of Pluto and Charon. Hydra was approximately 400,000 miles away from New Horizons when this image was acquired. http://photojournal.jpl.nasa.gov/catalog/PIA19711

The inverse problem of argon diffusion from minerals: Determination of kinetic parameters from stepwise-heating experiments

USGS Publications Warehouse

Brandt, Stephen B.; Rasskazov, S.V.; Brandt, I.S.; Ivanov, A.V.; Kunk, Michael J.

1997-01-01

Results of two routine 40Ar/39Ar stepwise heating experiments on a biotite and a basanite are interpreted in terms of Fick's and Arrhenius' laws. Both patterns represent a saddle-shaped 39Ar release. Argon isotope spectra are suggested to be controlled by the activation energy of diffusion E and the frequency factor D(o). The activation energy of 39Ar is lower than the one of 40Ar. This results in a preferable release of 40Ar relatively to 39Ar at high-temperature steps and an increasing high-temperature wing in the saddle-shaped age spectrum. At low temperatures, considerable losses and irregularities in release of mainly 39Ar are observed, which cause the decreasing low-temperature wing in the 'saddle'. The suggestion of argon losses (mainly of 39Ar) from a loose, 'unstable' zone of the mineral structures becomes justified. The n-irradiation of the samples and the shift of E of 39Ar towards lower values seems to explain the saddle-shaped age-spectra often encountered in 40Ar/39Ar-geochronometry.

AN ERP STUDY OF REGULAR AND IRREGULAR ENGLISH PAST TENSE INFLECTION

PubMed Central

Newman, Aaron J.; Ullman, Michael T.; Pancheva, Roumyana; Waligura, Diane L.; Neville, Helen J.

2006-01-01

Compositionality is a critical and universal characteristic of human language. It is found at numerous levels, including the combination of morphemes into words and of words into phrases and sentences. These compositional patterns can generally be characterized by rules. For example, the past tense of most English verbs (“regulars”) is formed by adding an -ed suffix. However, many complex linguistic forms have rather idiosyncratic mappings. For example, “irregular” English verbs have past tense forms that cannot be derived from their stems in a consistent manner. Whether regular and irregular forms depend on fundamentally distinct neurocognitive processes (rule-governed combination vs. lexical memorization), or whether a single processing system is sufficient to explain the phenomena, has engendered considerable investigation and debate. We recorded event-related potentials while participants read English sentences that were either correct or had violations of regular past tense inflection, irregular past tense inflection, syntactic phrase structure, or lexical semantics. Violations of regular past tense and phrase structure, but not of irregular past tense or lexical semantics, elicited left-lateralized anterior negativities (LANs). These seem to reflect neurocognitive substrates that underlie compositional processes across linguistic domains, including morphology and syntax. Regular, irregular, and phrase structure violations all elicited later positivities that were maximal over right parietal sites (P600s), and which seem to index aspects of controlled syntactic processing of both phrase structure and morphosyntax. The results suggest distinct neurocognitive substrates for processing regular and irregular past tense forms: regulars depending on compositional processing, and irregulars stored in lexical memory. PMID:17070703

SU-F-BRCD-03: Dose Calculation of Electron Therapy Using Improved Lateral Buildup Ratio Method.

PubMed

Gebreamlak, W; Tedeschi, D; Alkhatib, H

2012-06-01

To calculate the percentage depth dose of any irregular shape electron beam using modified lateral build-up-ratio method. Percentage depth dose (PDD) curves were measured using 6, 9, 12, and 15MeV electron beam energies for applicator cone sizes of 6×6, 10×10, 14×14, and 14×14cm 2 . Circular cutouts for each cone were prepared from 2.0cm diameter to the maximum possible size for each cone. In addition, three irregular cutouts were prepared. The scanning was done using a water tank and two diodes - one for the signal and the other a stationary reference outside the tank. The water surface was determined by scanning the signal diode slowly from water to air and by noting the sharp change of the percentage depth dose curve at the water/air interface. The lateral build-up-ratio (LBR) for each circular cutout was calculated from the measured PDD curve using the open field of the 14×14 cm 2 cone as the reference field. Using the LBR values and the radius of the circular cutouts, the corresponding lateral spread parameter (sigma) of the electron shower was calculated. Unlike the commonly accepted assumption that sigma is independent of cutout size, it is shown that the sigma value increases linearly with circular cutout size. Using this characteristic of sigma, the PDD curves of irregularly shaped cutouts were calculated. Finally, the calculated PDD curves were compared with measured PDD curves. In this research, it is shown that sigma increases with cutout size. For radius of circular cutout sizes up to the equilibrium range of the electron beam, the increase of sigma with the cutout size is linear. The percentage difference of the calculated PDD from the measured PDD for irregularly shaped cutouts was under 1.0%. Similar Result was obtained for four electron beam energies (6, 9, 12, and 15MeV). © 2012 American Association of Physicists in Medicine.

Efficient iteration in data-parallel programs with irregular and dynamically distributed data structures

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

Littlefield, R.J.

1990-02-01

To implement an efficient data-parallel program on a non-shared memory MIMD multicomputer, data and computations must be properly partitioned to achieve good load balance and locality of reference. Programs with irregular data reference patterns often require irregular partitions. Although good partitions may be easy to determine, they can be difficult or impossible to implement in programming languages that provide only regular data distributions, such as blocked or cyclic arrays. We are developing Onyx, a programming system that provides a shared memory model of distributed data structures and extends the concept of data distribution to include irregular and dynamic distributions. Thismore » provides a powerful means to specify irregular partitions. Perhaps surprisingly, programs using it can also execute efficiently. In this paper, we describe and evaluate the Onyx implementation of a model problem that repeatedly executes an irregular but fixed data reference pattern. On an NCUBE hypercube, the speed of the Onyx implementation is comparable to that of carefully handwritten message-passing code.« less

Synthesis and characterization of copper zinc oxide nanoparticles obtained via metathesis process

NASA Astrophysics Data System (ADS)

Phoohinkong, Weerachon; Foophow, Tita; Pecharapa, Wisanu

2017-09-01

Copper-doped zinc oxide nanoparticles were successfully synthesized by grinding copper acetate and zinc acetate powder with different starting molar ratios in combined with sodium hydroxide. The effect of initial copper and zinc molar ratios on the product samples was investigated and discussed. Relevant ligand coordination type of reactant acetate salt precursors and product samples were investigated by Fourier transform infrared spectroscopy (FTIR). The particle shapes and surface morphologies were characterized by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Phase structures of prepared samples were studied by x-ray powder diffraction (XRD) and x-ray absorption near-edge spectroscopy (XANES) was applied to investigate the local structure of Cu and Zn environment atoms. The results demonstrate that the, particle size of as-synthesized products affected by copper concentration in the precursor trend to gradually decreases from nanorod shape with diameter around 50-100 nm to irregular particle structure around 5 nm associated with an increase in the concentration of copper in precursor. Moreover, it is noticed that shape and morphology of the products are strongly dependent on Cu:Zn ratios during the synthesis. Nanocrystallines Cu-doped ZnO by the substitution in Zn site with a high crystallization degree of hexagonal wurtzite structure were obtained. This synthesis technique is suggested as a potential effective technique for preparing copper zinc oxide nanoparticles with various atomic ratio in wide range of applications. Contribution at the 4th Southeast Asia Conference on Thermoelectrics 2016 (SACT 2016), 15-18 December 2016, Da Nang City, Vietnam.

Modification of WS2 nanosheets with controllable layers via oxygen ion irradiation

NASA Astrophysics Data System (ADS)

Song, Honglian; Yu, Xiaofei; Chen, Ming; Qiao, Mei; Wang, Tiejun; Zhang, Jing; Liu, Yong; Liu, Peng; Wang, Xuelin

2018-05-01

As one kind of two-dimensional materials, WS2 nanosheets have drawn much attention with different kinds of research methods. Yet ion irradiation method was barely used for WS2 nanosheets. In this paper, the structure, composition and optical band gap (Eg) of the multilayer WS2 films deposited by chemical vapor deposition (CVD) method on sapphire substrates before and after oxygen ion irradiation with different energy and fluences were studied. Precise tailored layer-structures and a controllable optical band gap of WS2 nanosheets were achieved after oxygen ion irradiation. The results shows higher energy oxygen irradiation changed the shape from triangular shaped grains to irregular rectangle shape but did not change 2H-WS2 phase structure. The intensity of E2g1 (Г) and A1g (Г) modes decreased and have small shifts after oxygen ion irradiation. The peak frequency difference between the E2g1 (Г) and A1g (Г) modes (Δω) decreased after oxygen ion irradiation, and this result indicates the number of layers decreased after oxygen ion irradiation. The Eg decreased with the increase of the energy and the fluence of oxygen ions. The number of layers, thickness and optical band gap changed after ion irradiation with different ion fluences and energies. The results proposed a new strategy for precise control of multilayer nanosheets and demonstrated the high applicability of ion irradiation in super-capacitors, field effect transistors and other applications.

Electroerosion micro- and nanopowders for the production of hard alloys

NASA Astrophysics Data System (ADS)

Latypov, R. A.; Ageeva, E. V.; Kruglyakov, O. V.; Latypova, G. R.

2016-06-01

The shape and the surface morphology of the powder particles fabricated by the electroerosion dispersion of tungsten-containing wastes in illuminating oil are studied. The hard alloy fabricated from these powder particles is analyzed by electron-probe microanalysis. The powder synthesized by the electroerosion dispersion of the wastes of sintered hard alloys is found to consist of particles of a spherical or elliptical shape, an irregular shape (conglomerates), and a fragment shape. It is shown that W, Ti, and Co are the main elements in the hard alloy fabricated from the powder synthesized by electroerosion dispersion in illuminating oil.

Dynamic apical surface rings in superficial layer cells of koi Cyprinus carpio scale epidermis.

PubMed

DePasquale, J A

2016-09-01

This study examined the novel ring-shaped structures found in the apical surface of individual cells of the scale epidermis of koi Cyprinus carpio. These apical rings are highly dynamic structures with lifetimes ranging from a few to several minutes. While several ring forms were observed, the predominant ring morphology is circular or oval. Two distinct ring forms were identified and designated type I and type II. Type I rings have a well-defined outer border that encircles the surface microridges. Type II rings are smooth-surfaced, dinner-plate-like structures with membranous folds or compressed microridges in the centre. Type II rings appear less frequently than type I rings. Type I rings form spontaneously, arising from swollen or physically interrupted microridges but without initially perturbing the encircled microridges. After persisting for up to several minutes the ring closes in a centripetal movement to form a circular or irregular-shaped structure, the terminal disc. The terminal disc eventually disappears, leaving behind a submembranous vesicle-like structure, the terminal body. Type I rings can undergo multiple cycles of formation and closing. Recycling epidermal apical rings form through centrifugal expansion from the terminal disc followed by apparent contraction back to the disc structure, whereupon the cycle may repeat or cease. The findings demonstrate a novel skin surface structure in fishes and are discussed with respect to communication with the external aqueous environment. © 2016 The Fisheries Society of the British Isles.

Method for producing ceramic particles and agglomerates

DOEpatents

Phillips, Jonathan; Gleiman, Seth S.; Chen, Chun-Ku

2001-01-01

A method for generating spherical and irregularly shaped dense particles of ceramic oxides having a controlled particle size and particle size distribution. An aerosol containing precursor particles of oxide ceramics is directed into a plasma. As the particles flow through the hot zone of the plasma, they melt, collide, and join to form larger particles. If these larger particles remain in the hot zone, they continue melting and acquire a spherical shape that is retained after they exit the hot zone, cool down, and solidify. If they exit the hot zone before melting completely, their irregular shape persists and agglomerates are produced. The size and size distribution of the dense product particles can be controlled by adjusting several parameters, the most important in the case of powder precursors appears to be the density of powder in the aerosol stream that enters the plasma hot zone. This suggests that particle collision rate is responsible for determining ultimate size of the resulting sphere or agglomerate. Other parameters, particularly the gas flow rates and the microwave power, are also adjusted to control the particle size distribution.

A scattering database of marine particles and its application in optical analysis

NASA Astrophysics Data System (ADS)

Xu, G.; Yang, P.; Kattawar, G.; Zhang, X.

2016-12-01

In modeling the scattering properties of marine particles (e.g. phytoplankton), the laboratory studies imply a need to properly account for the influence of particle morphology, in addition to size and composition. In this study, a marine particle scattering database is constructed using a collection of distorted hexahedral shapes. Specifically, the scattering properties of each size bin and refractive index are obtained by the ensemble average associated with distorted hexahedra with randomly tilted facets and selected aspect ratios (from elongated to flattened). The randomness degree in shape-generation process defines the geometric irregularity of the particles in the group. The geometric irregularity and particle aspect ratios constitute a set of "shape factors" to be accounted for (e.g. in best-fit analysis). To cover most of the marine particle size range, we combine the Invariant Imbedding T-matrix (II-TM) method and the Physical-Geometric Optics Hybrid (PGOH) method in the calculations. The simulated optical properties are shown and compared with those obtained from Lorenz-Mie Theory. Using the scattering database, we present a preliminary optical analysis of laboratory-measured optical properties of marine particles.

Morphology and phase identification of synthesized precipitated calcium carbonate from acetylene gas industry waste

NASA Astrophysics Data System (ADS)

Sabri, Siti Noorzidah Mohd; Othman, Rohaya; Othman, Anuar

2017-12-01

Precipitated calcium carbonate (PCC) is also known as synthetic calcium carbonate. In this paper, PCC was synthesized from carbide lime, which is the by-product from acetylene gas industry. The method used to produce PCC from carbide lime waste was ionic sucrose precipitation technique. The experiments were performed by varying the stirring rate. In this technique, carbide lime was first dissolved in ionic sucrose solution and then chilled at 10 °C for 24 hours before carbon dioxide gasses was introduced into the solution. The carbonation and precipitation process was took place and PCC was formed. The PCC was further filtered to obtain the solid PCC. The sample was then further characterised by using FESEM and XRD to determine the morphology and to identify the phase that exists in the synthesized compound respectively. The XRD and FESEM results clearly shown that the PCC obtained has mixed phases of calcite and vaterite, with mixtures of spherical and irregular shape morphologies formed. The irregular shapes corresponded to vaterite formation, meanwhile spherical shapes corresponded to calcite formation.

Particle shape accounts for instrumental discrepancy in ice core dust size distributions

NASA Astrophysics Data System (ADS)

Folden Simonsen, Marius; Cremonesi, Llorenç; Baccolo, Giovanni; Bosch, Samuel; Delmonte, Barbara; Erhardt, Tobias; Kjær, Helle Astrid; Potenza, Marco; Svensson, Anders; Vallelonga, Paul

2018-05-01

The Klotz Abakus laser sensor and the Coulter counter are both used for measuring the size distribution of insoluble mineral dust particles in ice cores. While the Coulter counter measures particle volume accurately, the equivalent Abakus instrument measurement deviates substantially from the Coulter counter. We show that the difference between the Abakus and the Coulter counter measurements is mainly caused by the irregular shape of dust particles in ice core samples. The irregular shape means that a new calibration routine based on standard spheres is necessary for obtaining fully comparable data. This new calibration routine gives an increased accuracy to Abakus measurements, which may improve future ice core record intercomparisons. We derived an analytical model for extracting the aspect ratio of dust particles from the difference between Abakus and Coulter counter data. For verification, we measured the aspect ratio of the same samples directly using a single-particle extinction and scattering instrument. The results demonstrate that the model is accurate enough to discern between samples of aspect ratio 0.3 and 0.4 using only the comparison of Abakus and Coulter counter data.

Structural and electronic investigations of PbTa4O11 and BiTa7O19 constructed from α-U3O8 types of layers

NASA Astrophysics Data System (ADS)

Boltersdorf, Jonathan; Maggard, Paul A.

2015-09-01

The PbTa4O11 and BiTa7O19 phases were prepared by ion-exchange and solid-state methods, respectively, and their structures were characterized by neutron time-of-flight diffraction and Rietveld refinement methods (PbTa4O11, R 3 (No. 146), a=6.23700(2) Å, c=36.8613(1) Å; BiTa7O19, P 6 bar c 2 (No. 188), a=6.2197(2) Å, c=20.02981(9) Å). Their structures are comprised of layers of TaO6 octahedra surrounded by three 7-coordinate Pb(II) cations or two 8-coordinate Bi(III) cations. These layers alternate down the c-axis with α-U3O8 types of single and double TaO7 pentagonal bipyramid layers. In contrast to earlier studies, both phases are found to crystallize in noncentrosymmetric structures. Symmetry-lowering structural distortions within PbTa4O11, i.e. R 3 bar c →R3, are found to be a result of the displacement of the Ta atoms within the TaO7 and TaO6 polyhedra, towards the apical and facial oxygen atoms, respectively. In BiTa7O19, relatively lower reaction temperatures leads to an ordering of the Bi/Ta cations within a lower-symmetry structure, i.e., P63/mcm→ P 6 bar c 2 . In the absence of Bi/Ta site disorder, the Ta-O-Ta bond angles decrease and the Ta-O bond distances increase within the TaO7 double layers. Scanning electron microscopy images reveal two particle morphologies for PbTa4O11, hexagonal rods and finer irregularly-shaped particles, while BiTa7O19 forms as aggregates of irregularly-shaped particles. Electronic-structure calculations confirm the highest-energy valence band states are comprised of O 2p-orbitals and the respective Pb 6s-orbital and Bi 6s-orbital contributions. The lowest-energy conduction band states are composed of Ta 5d-orbital contributions that are delocalized over the TaO6 octahedra and layers of TaO7 pentagonal bipyramids. The symmetry-lowering distortions in the PbTa4O11 structure, and the resulting effects on its electronic structure, lead to its relatively higher photocatalytic activity compared to similar structures without these distortions.

Prenatal diagnosis of periventricular nodular heterotopia in borderline ventriculomegaly using sonography and magnetic resonance imaging.

PubMed

Sahinoglu, Zeki; Yapicier, Ozlem; Ozcan, Nahit

2016-10-01

Periventricular nodular heterotopia (PNH) is usually missed on prenatal sonographic examinations, even on targeted scans. Irregular ventricular walls on axial view and irregular square-shaped lateral ventricles on coronal view are suggestive of PNH in the early third trimester. To achieve an early prenatal diagnosis, it is important to keep in mind the possible coexistence of PNH with brain malformations such as ventriculomegaly, posterior fossa anomalies, or agenesis of corpus callosum. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 44:510-513, 2016. © 2016 Wiley Periodicals, Inc.

The Particle Shape of WC Governing the Fracture Mechanism of Particle Reinforced Iron Matrix Composites.

PubMed

Li, Zulai; Wang, Pengfei; Shan, Quan; Jiang, Yehua; Wei, He; Tan, Jun

2018-06-11

In this work, tungsten carbide particles (WC p , spherical and irregular particles)-reinforced iron matrix composites were manufactured utilizing a liquid sintering technique. The mechanical properties and the fracture mechanism of WC p /iron matrix composites were investigated theoretically and experimentally. The crack schematic diagram and fracture simulation diagram of WC p /iron matrix composites were summarized, indicating that the micro-crack was initiated both from the interface for spherical and irregular WC p /iron matrix composites. However, irregular WC p had a tendency to form spherical WC p . The micro-cracks then expanded to a wide macro-crack at the interface, leading to a final failure of the composites. In comparison with the spherical WC p , the irregular WC p were prone to break due to the stress concentration resulting in being prone to generating brittle cracking. The study on the fracture mechanisms of WC p /iron matrix composites might provide a theoretical guidance for the design and engineering application of particle reinforced composites.

Estimating network parameters from combined dynamics of firing rate and irregularity of single neurons.

PubMed

Hamaguchi, Kosuke; Riehle, Alexa; Brunel, Nicolas

2011-01-01

High firing irregularity is a hallmark of cortical neurons in vivo, and modeling studies suggest a balance of excitation and inhibition is necessary to explain this high irregularity. Such a balance must be generated, at least partly, from local interconnected networks of excitatory and inhibitory neurons, but the details of the local network structure are largely unknown. The dynamics of the neural activity depends on the local network structure; this in turn suggests the possibility of estimating network structure from the dynamics of the firing statistics. Here we report a new method to estimate properties of the local cortical network from the instantaneous firing rate and irregularity (CV(2)) under the assumption that recorded neurons are a part of a randomly connected sparse network. The firing irregularity, measured in monkey motor cortex, exhibits two features; many neurons show relatively stable firing irregularity in time and across different task conditions; the time-averaged CV(2) is widely distributed from quasi-regular to irregular (CV(2) = 0.3-1.0). For each recorded neuron, we estimate the three parameters of a local network [balance of local excitation-inhibition, number of recurrent connections per neuron, and excitatory postsynaptic potential (EPSP) size] that best describe the dynamics of the measured firing rates and irregularities. Our analysis shows that optimal parameter sets form a two-dimensional manifold in the three-dimensional parameter space that is confined for most of the neurons to the inhibition-dominated region. High irregularity neurons tend to be more strongly connected to the local network, either in terms of larger EPSP and inhibitory PSP size or larger number of recurrent connections, compared with the low irregularity neurons, for a given excitatory/inhibitory balance. Incorporating either synaptic short-term depression or conductance-based synapses leads many low CV(2) neurons to move to the excitation-dominated region as well as to an increase of EPSP size.

Analysis of an Irregular RC Multi-storeyed Building Subjected to Dynamic Loading

NASA Astrophysics Data System (ADS)

AkashRaut; Pachpor, Prabodh; Dautkhani, Sanket

2018-03-01

Many buildings in the present scenario have irregular configurations both in plan and elevation. This in future may subject to devastating earthquakes. So it is necessary to analyze the structure. The present paper is made to study three type of irregularity wiz vertical, mass and plan irregularity as per clause 7.1 of IS 1893 (part1)2002 code. The paper discusses the analysis of RC (Reinforced Concrete) Buildings with vertical irregularity. The study as a whole makes an effort to evaluate the effect of vertical irregularity on RC buildings for which comparison of three parameters namely shear force, bending moment and deflection are taken into account.

Effects of the infectious period distribution on predicted transitions in childhood disease dynamics

PubMed Central

Krylova, Olga; Earn, David J. D.

2013-01-01

The population dynamics of infectious diseases occasionally undergo rapid qualitative changes, such as transitions from annual to biennial cycles or to irregular dynamics. Previous work, based on the standard seasonally forced ‘susceptible–exposed–infectious–removed’ (SEIR) model has found that transitions in the dynamics of many childhood diseases result from bifurcations induced by slow changes in birth and vaccination rates. However, the standard SEIR formulation assumes that the stage durations (latent and infectious periods) are exponentially distributed, whereas real distributions are narrower and centred around the mean. Much recent work has indicated that realistically distributed stage durations strongly affect the dynamical structure of seasonally forced epidemic models. We investigate whether inferences drawn from previous analyses of transitions in patterns of measles dynamics are robust to the shapes of the stage duration distributions. As an illustrative example, we analyse measles dynamics in New York City from 1928 to 1972. We find that with a fixed mean infectious period in the susceptible–infectious–removed (SIR) model, the dynamical structure and predicted transitions vary substantially as a function of the shape of the infectious period distribution. By contrast, with fixed mean latent and infectious periods in the SEIR model, the shapes of the stage duration distributions have a less dramatic effect on model dynamical structure and predicted transitions. All these results can be understood more easily by considering the distribution of the disease generation time as opposed to the distributions of individual disease stages. Numerical bifurcation analysis reveals that for a given mean generation time the dynamics of the SIR and SEIR models for measles are nearly equivalent and are insensitive to the shapes of the disease stage distributions. PMID:23676892

Effects of the infectious period distribution on predicted transitions in childhood disease dynamics.

PubMed

Krylova, Olga; Earn, David J D

2013-07-06

The population dynamics of infectious diseases occasionally undergo rapid qualitative changes, such as transitions from annual to biennial cycles or to irregular dynamics. Previous work, based on the standard seasonally forced 'susceptible-exposed-infectious-removed' (SEIR) model has found that transitions in the dynamics of many childhood diseases result from bifurcations induced by slow changes in birth and vaccination rates. However, the standard SEIR formulation assumes that the stage durations (latent and infectious periods) are exponentially distributed, whereas real distributions are narrower and centred around the mean. Much recent work has indicated that realistically distributed stage durations strongly affect the dynamical structure of seasonally forced epidemic models. We investigate whether inferences drawn from previous analyses of transitions in patterns of measles dynamics are robust to the shapes of the stage duration distributions. As an illustrative example, we analyse measles dynamics in New York City from 1928 to 1972. We find that with a fixed mean infectious period in the susceptible-infectious-removed (SIR) model, the dynamical structure and predicted transitions vary substantially as a function of the shape of the infectious period distribution. By contrast, with fixed mean latent and infectious periods in the SEIR model, the shapes of the stage duration distributions have a less dramatic effect on model dynamical structure and predicted transitions. All these results can be understood more easily by considering the distribution of the disease generation time as opposed to the distributions of individual disease stages. Numerical bifurcation analysis reveals that for a given mean generation time the dynamics of the SIR and SEIR models for measles are nearly equivalent and are insensitive to the shapes of the disease stage distributions.

Solution and surface effects on plasma fibronectin structure

PubMed Central

1983-01-01

As assessed by electron microscopy, the reported shape of the plasma fibronectin molecule ranges from that of a compact particle to an elongated, rod-like structure. In this study, we evaluated the effects of solution and surface conditions on fibronectin shape. Freeze-dried, unstained human plasma fibronectin molecules deposited at pH 7.0-7.4 onto carbon films and examined by scanning transmission electron microscopy appeared relatively compact and pleiomorphic, with approximate average dimensions of 24 nm X 16 nm. Negatively stained molecules also had a similar shape but revealed greater detail in that we observed irregular, yarn-like structures. Glutaraldehyde-induced intramolecular cross-linking did not alter the appearance of plasma fibronectin. Molecules deposited at pH 2.8, pH 9.3, or after succinylation were less compact than those deposited at neutral pH. In contrast, fibronectin molecules sprayed onto mica surfaces at pH 7, rotary shadowed, and examined by transmission electron microscopy were elongated and nodular with a contour length of 120-130 nm. Sedimentation velocity experiments and electron microscopic observations indicate that fibronectin unfolds when it is succinylated, when the ionic strength is raised at pH 7, or when the pH is adjusted to 9.3 or 2.8. Greater unfolding is observed at pH 2.8 at low ionic strength (less than 0.01) compared with material at that pH in 0.15 M NaCl solution. We conclude that (a) the shape assumed by the fibronectin molecule can be strongly affected by solution conditions and by deposition onto certain surfaces; and that (b) the images of fibronectin seen by scanning transmission electron microscopy at neutral pH on carbon film are representative of molecules in physiologic solution. PMID:6417145

Atmospheric Condensational Properties of Ultrafine Chain and Fractal Aerosol Particles

NASA Technical Reports Server (NTRS)

Marlow, William H.

1997-01-01

The purpose for the research sponsored by this grant was to lay the foundations for qualitative understanding and quantitative description of the equilibrium vapor pressure of water vapor over the irregularly shaped, carbonaceous particles that are present in the atmosphere. This work apparently was the first systematic treatment of the subject. Research was conducted in two complementary components: 1. Calculations were performed of the equilibrium vapor pressure of water over particles comprised of aggregates of spheres in the 50-200 nm radius range. The purposes of this work were two-fold. First, since no systematic treatment of this subject had previously been conducted, its availability would be directly useful for quantitative treatment for a limited range of atmospheric aerosols. Second, it would provide qualitative indications of the effects of highly irregular particle shape on equilibrium vapor pressure of aggregates comprised of smaller spheres.

The nature of Trojan asteroid 624 Hektor

NASA Technical Reports Server (NTRS)

Hartmann, W. K.; Cruikshank, D. P.

1978-01-01

Near-simultaneous visual and thermal IR (20-micron) photometry of the Trojan asteroid 624 Hektor is reported which was performed when the asteroid was observed nearly along its rotation axis. The results confirm and refine the low albedo and large size of this asteroid and confirm the general rotational-pole position and aspect angle predicted by Dunlap and Gehrels (1969). Hektor is found to be a truly extraordinary object in that it is larger and far more irregular in shape than other measured Trojans and far more irregular than other belt asteroids of comparable size. It is proposed that Hektor could be a partially coalesced pair of Trojan asteroids which collided with energy too low to cause complete fragmentation, thus forming a dumbbell-shaped object. A possible scenario is outlined according to which the two pre-Hektor objects were neighboring relatively large primitive spheroidal planetesimals trapped in Jupiter's Lagrangian cloud. Observational and theoretical tests of this model are suggested.

Highly Structured Plasma Density and Associated Electric and Magnetic Field Irregularities at Sub-Auroral, Middle, and Low Latitudes in the Topside Ionosphere Observed with the DEMETER and DMSP Satellites

NASA Technical Reports Server (NTRS)

Pfaff, Robert F.; Liebrecht, C; Berthelier, Jean-Jacques; Parrot, M.; Lebreton, Jean-Pierre

2007-01-01

Detailed observations of the plasma structure and irregularities that characterize the topside ionosphere at sub-auroral, middle, and low-latitudes are gathered with probes on the DEMETER and DMSP satellites. In particular, we present DEMETER observations near 700 km altitude that reveal: (1) the electric field irregularities and density depletions at mid-latitudes are remarkably similar to those associated with equatorial spread-F at low latitudes; (2) the mid-latitude density structures contain both depletions and enhancements with scale lengths along the spacecraft trajectory that typically vary from 10's to 100's of km; (3) in some cases, ELF magnetic field irregularities are observed in association with the electric field irregularities on the walls of the plasma density structures and appear to be related to finely-structured spatial currents and/or Alfven waves; (4) during severe geomagnetic storms, broad regions of nightside plasma density structures are typically present, in some instances extending from the equator to the subauroral regions; and (5) intense, broadband electric and magnetic field irregularities are observed at sub-auroral latitudes during geomagnetic storm periods that are typically associated with the trough region. Data from successive DEMETER orbits during storm periods in both the daytime and nighttime illustrate how enhancements of both the ambient plasma density, as well as sub-auroral and mid-latitude density structures, correlate and evolve with changes in the Dst. The DEMETER data are compared with near simultaneous observations gathered by the DMSP satellites near 840 km. The observations are related to theories of sub-auroral and mid-latitude plasma density structuring during geomagnetic storms and penetration electric fields and are highly germane to understanding space weather effects regarding disruption of communication and navigation signals in the near-space environment.

An Amino Acid Code for Irregular and Mixed Protein Packing

PubMed Central

Joo, Hyun; Chavan, Archana; Fraga, Keith; Tsai, Jerry

2015-01-01

To advance our understanding of protein tertiary structure, the development of the knob-socket model is completed in an analysis of the packing in irregular coil and turn secondary structure packing as well as between mixed secondary structure. The knob-socket model simplifies packing based on repeated patterns of 2 motifs: a 3 residue socket for packing within 2° structure and a 4 residue knob-socket for 3° packing. For coil and turn secondary structure, knob-sockets allow identification of a correlation between amino acid composition and tertiary arrangements in space. Coil contributes almost as much as α-helices to tertiary packing. Irregular secondary structure involves 3 residue cliques of consecutive contacting residues or XYZ sockets. In irregular sockets, Gly, Pro, Asp and Ser are favored, while Cys, His, Met and Trp are not. For irregular knobs, the preference order is Arg, Asp, Pro, Asn, Thr, Leu, and Gly, while Cys, His, Met and Trp are not. In mixed packing, the knob amino acid preferences are a function of the socket that they are packing into, whereas the amino acid composition of the sockets does not depend on the secondary structure of the knob. A unique motif of a coil knob with an XYZ β-sheet socket may potentially function to inhibit β-sheet extension. In addition, analysis of the preferred crossing angles for strands within a β-sheet and mixed α-helices/β-sheets identifies canonical packing patterns useful in protein design. Lastly, the knob-socket model abstracts the complexity of protein tertiary structure into an intuitive packing surface topology map. PMID:26370334

Rocket measurements of mesospheric ionization irregularities

NASA Technical Reports Server (NTRS)

Stoltzfus, R. B.; Bowhill, S. A.

1985-01-01

The Langmuir probe technique for measurement of electron concentration in the mesosphere is capable of excellent altitude resolution, of order 1 m. Measurements from nine daytime rocket flights carrying an electron density fine structure experiment frequently show small scale ionization structures in the altitude region 70 to 90 km. The irregularities are believed to be the result of turbulent advection of ions and electrons. The fine structure experiment flown by the University of Illinois is described and methods of analyzing the collected data is presented. Theories of homogeneous, isotropic turbulence are reviewed. Power spectra of the measured irregularities are calculated and compared to spectra predicted by turbulence theories.

Morphology and structure of TixOy nanoparticles generated by femtosecond laser ablation in water

NASA Astrophysics Data System (ADS)

Donėlienė, Jolanta; Rudzikas, Matas; Rades, Steffi; Dörfel, Ilona; Peplinski, Burkhard; Sahre, Mario; Pellegrino, Francesco; Maurino, Valter; Ulbikas, Juras; Galdikas, Algirdas; Hodoroaba, Vasile-Dan

2018-04-01

In this work femto-second pulsed laser ablation in liquid (PLAL) procedure for the generation of titanium oxide nanoparticles (NP) is reported with the purpose of understanding morphology and structure of the newly generated NPs. Ablation duration was varied for optimization of NP generation processes between 10 and 90 min. Surface morphology of NPs as well as their size and shape (distribution) were analysed by various complementary electron microscopy techniques, i.e. SEM, TSEM and TEM. The crystalline structure of titanium oxide particles was investigated by XRD (two instruments operated in different geometries) and HR-TEM. Concentration of generated titanium oxide NPs in liquid was analysed by ICP-MS. A mix of crystalline (mainly anatase), partly crystalline and amorphous spherical titanium oxide NPs can be reported having a mean size between 10 and 20 nm, which is rather independent of the laser ablation (LA) duration. A second component consisting of irregularly shaped, but crystalline titanium oxide nanostructures is co-generated in the LA water, with more pronounced occurrence at longer LA times. The provenance of this component is assigned to those spherical particles generated in suspension and passing through the converging laser beam, being hence subject to secondary irradiation effects, e. g. fragmentation.

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

James K. Neathery; Gary Jacobs; Amitava Sarkar

In the previous reporting period, modifications were completed for integrating a continuous wax filtration system for a 4 liter slurry bubble column reactor. During the current reporting period, a shakedown of the system was completed. Several problems were encountered with the progressive cavity pump used to circulate the wax/catalyst slurry though the cross-flow filter element and reactor. During the activation of the catalyst with elevated temperature (> 270 C) the elastomer pump stator released sulfur thereby totally deactivating the iron-based catalyst. Difficulties in maintaining an acceptable leak rate from the pump seal and stator housing were also encountered. Consequently, themore » system leak rate exceeded the expected production rate of wax; therefore, no online filtration could be accomplished. Work continued regarding the characterization of ultra-fine catalyst structures. The effect of carbidation on the morphology of iron hydroxide oxide particles was the focus of the study during this reporting period. Oxidation of Fe (II) sulfate results in predominantly {gamma}-FeOOH particles which have a rod-shaped (nano-needles) crystalline structure. Carbidation of the prepared {gamma}-FeOOH with CO at atmospheric pressure produced iron carbides with spherical layered structure. HRTEM and EDS analysis revealed that carbidation of {gamma}-FeOOH particles changes the initial nano-needles morphology and generates ultrafine carbide particles with irregular spherical shape.« less

Eliminating the influence of source spectrum of white light scanning interferometry through time-delay estimation algorithm

NASA Astrophysics Data System (ADS)

Zhou, Yunfei; Cai, Hongzhi; Zhong, Liyun; Qiu, Xiang; Tian, Jindong; Lu, Xiaoxu

2017-05-01

In white light scanning interferometry (WLSI), the accuracy of profile measurement achieved with the conventional zero optical path difference (ZOPD) position locating method is closely related with the shape of interference signal envelope (ISE), which is mainly decided by the spectral distribution of illumination source. For a broadband light with Gaussian spectral distribution, the corresponding shape of ISE reveals a symmetric distribution, so the accurate ZOPD position can be achieved easily. However, if the spectral distribution of source is irregular, the shape of ISE will become asymmetric or complex multi-peak distribution, WLSI cannot work well through using ZOPD position locating method. Aiming at this problem, we propose time-delay estimation (TDE) based WLSI method, in which the surface profile information is achieved by using the relative displacement of interference signal between different pixels instead of the conventional ZOPD position locating method. Due to all spectral information of interference signal (envelope and phase) are utilized, in addition to revealing the advantage of high accuracy, the proposed method can achieve profile measurement with high accuracy in the case that the shape of ISE is irregular while ZOPD position locating method cannot work. That is to say, the proposed method can effectively eliminate the influence of source spectrum.

Comparison of Maximum Stretch Forces between Femtosecond Laser-Assisted Capsulotomy and Continuous Curvilinear Capsulorhexis

PubMed Central

Ichikawa, Kei; Tanaka, Yoshiki; Kato, Yukihito; Horai, Rie; Tamaoki, Akeno; Ichikawa, Kazuo

2017-01-01

The current study reports comparing the postoperative mechanical properties of the anterior capsule between femtosecond laser capsulotomy (FLC) and continuous curvilinear capsulorhexis (CCC) of variable size and shape in porcine eyes. All CCCs were created using capsule forceps. Irregular or eccentric CCCs were also created to simulate real cataract surgery. For FLC, capsulotomies 5.3 mm in diameter were created using the LenSx® (Alcon) platform. Fresh porcine eyes were used in all experiments. The edges of the capsule openings were pulled at a constant speed using two L-shaped jigs. Stretch force and distance were recorded over time, and the maximum values in this regard were defined as those that were recorded when the capsule broke. There was no difference in maximum stretch force between CCC and FLC. There were no differences in circularity between FLC and same-sized CCC. However, same-sized CCC did show significantly higher maximum stretch forces than FLC. Teardrop-shaped CCC showed lower maximum stretch forces than same-sized CCC and FLC. Heart-shaped CCC showed lower maximum stretch forces than same-sized CCC. Conclusively, while capsule edge strength after CCC varied depending on size or irregularities, FLC had the advantage of stable maximum stretch forces. PMID:28210504

Comparison of Maximum Stretch Forces between Femtosecond Laser-Assisted Capsulotomy and Continuous Curvilinear Capsulorhexis.

PubMed

Takagi, Mari; Kojima, Takashi; Ichikawa, Kei; Tanaka, Yoshiki; Kato, Yukihito; Horai, Rie; Tamaoki, Akeno; Ichikawa, Kazuo

2017-01-01

The current study reports comparing the postoperative mechanical properties of the anterior capsule between femtosecond laser capsulotomy (FLC) and continuous curvilinear capsulorhexis (CCC) of variable size and shape in porcine eyes. All CCCs were created using capsule forceps. Irregular or eccentric CCCs were also created to simulate real cataract surgery. For FLC, capsulotomies 5.3 mm in diameter were created using the LenSx® (Alcon) platform. Fresh porcine eyes were used in all experiments. The edges of the capsule openings were pulled at a constant speed using two L-shaped jigs. Stretch force and distance were recorded over time, and the maximum values in this regard were defined as those that were recorded when the capsule broke. There was no difference in maximum stretch force between CCC and FLC. There were no differences in circularity between FLC and same-sized CCC. However, same-sized CCC did show significantly higher maximum stretch forces than FLC. Teardrop-shaped CCC showed lower maximum stretch forces than same-sized CCC and FLC. Heart-shaped CCC showed lower maximum stretch forces than same-sized CCC. Conclusively, while capsule edge strength after CCC varied depending on size or irregularities, FLC had the advantage of stable maximum stretch forces.

Cubic spline anchored grid pattern algorithm for high-resolution detection of subsurface cavities by the IR-CAT method

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

Kassab, A.J.; Pollard, J.E.

An algorithm is presented for the high-resolution detection of irregular-shaped subsurface cavities within irregular-shaped bodies by the IR-CAT method. The theoretical basis of the algorithm is rooted in the solution of an inverse geometric steady-state heat conduction problem. A Cauchy boundary condition is prescribed at the exposed surface, and the inverse geometric heat conduction problem is formulated by specifying the thermal condition at the inner cavities walls, whose unknown geometries are to be detected. The location of the inner cavities is initially estimated, and the domain boundaries are discretized. Linear boundary elements are used in conjunction with cubic splines formore » high resolution of the cavity walls. An anchored grid pattern (AGP) is established to constrain the cubic spline knots that control the inner cavity geometry to evolve along the AGP at each iterative step. A residual is defined measuring the difference between imposed and computed boundary conditions. A Newton-Raphson method with a Broyden update is used to automate the detection of inner cavity walls. During the iterative procedure, the movement of the inner cavity walls is restricted to physically realistic intermediate solutions. Numerical simulation demonstrates the superior resolution of the cubic spline AGP algorithm over the linear spline-based AGP in the detection of an irregular-shaped cavity. Numerical simulation is also used to test the sensitivity of the linear and cubic spline AGP algorithms by simulating bias and random error in measured surface temperature. The proposed AGP algorithm is shown to satisfactorily detect cavities with these simulated data.« less

Analysis of the solution structure of Thermosynechococcus elongatus photosystem I in n-dodecyl-β-d-maltoside using small-angle neutron scattering and molecular dynamics simulation

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

Le, Rosemary K.; Harris, Bradley J.; Iwuchukwu, Ifeyinwa J.

2014-05-01

Small-angle neutron scattering (SANS) and molecular dynamics (MD) simulation were used to investigate the structure of trimeric photosystem I (PSI) from Thermosynechococcus elongatus (T. elongatus) stabilized in n-dodecyl-β-d-maltoside (DDM) detergent solution. Scattering curves of detergent and protein–detergent complexes were measured at 18% D2O, the contrast match point for the detergent, and 100% D2O, allowing observation of the structures of protein/detergent complexes. It was determined that the maximum dimension of the PSI–DDM complex was consistent with the presence of a monolayer belt of detergent around the periphery of PSI. A dummy-atom reconstruction of the shape of the complex from the SANSmore » data indicates that the detergent envelope has an irregular shape around the hydrophobic periphery of the PSI trimer rather than a uniform, toroidal belt around the complex. A 50 ns MD simulation model (a DDM ring surrounding the PSI complex with extra interstitial DDM) of the PSI–DDM complex was developed for comparison with the SANS data. The results suggest that DDM undergoes additional structuring around the membrane-spanning surface of the complex instead of a simple, relatively uniform belt, as is generally assumed for studies that use detergents to solubilize membrane proteins.« less

Can we apply the MRI BI-RADS lexicon morphology descriptors on contrast-enhanced spectral mammography?

PubMed

Kamal, Rasha M; Helal, Maha H; Mansour, Sahar M; Haggag, Marwa A; Nada, Omniya M; Farahat, Iman G; Alieldin, Nelly H

2016-07-12

To assess the feasibility of using the MRI breast imaging reporting and data system (BI-RADS) lexicon morphology descriptors to characterize enhancing breast lesions identified on contrast-enhanced spectral mammography (CESM). The study is a retrospective analysis of the morphology descriptors of 261 enhancing breast lesions identified on CESM in 239 patients. We presented the morphological categorization of the included lesions into focus, mass and non-mass. Further classifications included (1) the multiplicity for "focus" category, (2) the shape, margin and internal enhancement for "mass" category and (3) the distribution and internal enhancement for "non-mass" category. Each morphology descriptor was evaluated individually (irrespective of all other descriptors) by calculating its sensitivity, specificity, positive-predictive value (PPV) and negative-predictive value (NPV) and likelihood ratios (LRs). The study included 68/261 (26.1%) benign lesions and 193/261 (73.9%) malignant lesions. Intensely enhancing foci, whether single (7/12, 58.3%) or multiple (2/12, 16.7%), were malignant. Descriptors of "irregular"-shape (PPV: 92.4%) and "non-circumscribed" margin (odds ratio: 55.2, LR positive: 4.77; p-value: <0.001) were more compatible with malignancy. Internal mass enhancement patterns showed a very low specificity (58.0%) and NPV (40.0%). Non-mass enhancement (NME) was detected in 81/261 lesions. Asymmetrical NME in 81% (n = 52/81) lesions was malignant lesions and internal enhancement patterns indicative of malignancy were the heterogeneous and clumped ones. We can apply the MRI morphology descriptors to characterize lesions on CESM, but with few expectations. In many situations, irregular-shaped, non-circumscribed masses and NME with focal, ductal or segmental distribution and heterogeneous or clumped enhancement are the most suggestive descriptors of malignant pathologies. (1) The MRI BI-RADS lexicon morphology descriptors can be applied in the characterization of enhancing lesions on CESM with a few exceptions. (2) Multiple bilateral intensely enhancing foci should not be included under the normal background parenchymal enhancement unless they are proved to be benign by biopsy. (3) Mass lesion features that indicated malignancy were irregular-shaped, spiculated and irregular margins and heterogeneous internal enhancement patterns. The rim enhancement pattern should not be considered as a descriptor of malignant lesions unless CESM is coupled with an ultrasound examination.

Effect of Anions on Nanofiber Formation of β-sheet Propensity Amphiphile Peptide

NASA Astrophysics Data System (ADS)

Shamsudeen, H.; Tan, H. L.; Eshak, Z.

2018-05-01

Peptide self-assembly forms different nanostructures under simple alteration in the solution environment. Understanding the mechanism of the assembly will help us to control and tailor functional nanomaterials. This study aims to investigate the influence of anions on the self-assembly morphology and shape using a synthetic peptide of FFFFKK. Circular Dichoism (CD) and Environmental Scanning Electron Microscope (ESEM) were used to determine the secondary structure and self-assembly morphology, while Image J imaging software was used to measure diameter size. In the absence of anion, FFFFKK formed anti-parallel β-sheet that adopted sizeable fibrillar structure with a minimal increment over the first 7 hours of assembly. Irregular structure was observed in the presence of Iodide ion (I-) with a less stable secondary structure such as β-turn and β-loop. In the presence of perchlorate ion (ClO4 -), needle-like structure was observed with predominantly β-sheet structure. Our study showed that peptide morphology can be controlled by using different anions with careful selection of amino acid residues in peptide sequence.

Detecting space-time disease clusters with arbitrary shapes and sizes using a co-clustering approach.

PubMed

Ullah, Sami; Daud, Hanita; Dass, Sarat C; Khan, Habib Nawaz; Khalil, Alamgir

2017-11-06

Ability to detect potential space-time clusters in spatio-temporal data on disease occurrences is necessary for conducting surveillance and implementing disease prevention policies. Most existing techniques use geometrically shaped (circular, elliptical or square) scanning windows to discover disease clusters. In certain situations, where the disease occurrences tend to cluster in very irregularly shaped areas, these algorithms are not feasible in practise for the detection of space-time clusters. To address this problem, a new algorithm is proposed, which uses a co-clustering strategy to detect prospective and retrospective space-time disease clusters with no restriction on shape and size. The proposed method detects space-time disease clusters by tracking the changes in space-time occurrence structure instead of an in-depth search over space. This method was utilised to detect potential clusters in the annual and monthly malaria data in Khyber Pakhtunkhwa Province, Pakistan from 2012 to 2016 visualising the results on a heat map. The results of the annual data analysis showed that the most likely hotspot emerged in three sub-regions in the years 2013-2014. The most likely hotspots in monthly data appeared in the month of July to October in each year and showed a strong periodic trend.

Detection and estimation of defects in a circular plate using operational deflection shapes

NASA Astrophysics Data System (ADS)

Pai, Perngjin F.; Oh, Yunje; Kim, Byeong-Seok

2002-06-01

This paper investigates dynamic characteristics (mode shapes and natural frequencies) and defect detection of circular plates using a scanning laser vibrometer. Exact dynamic characteristics of a circular aluminum plate having a clamped inner rim and a free outer rim are obtained using two methods; one uses Bessel functions and the other uses a multiple shooting method. An in-house finite element code GESA is also used to analyze the circular plate using the DKT plate element. Numerical results show that some reports in the literature are incorrect and that high-frequency Operational Deflection Shapes (ODSs) are needed in order to locate small defects. Detection of two defects in the circular aluminum plate is experimentally studied using the distributions of RMS velocities under broadband periodic chirp excitations. RMS velocities of ODSs, symmetry breaking of ODSs, splitting of natural frequencies and ODSs, and a Boundary Effect Detection (BED) method. The BED method is non-destructive and model-independent; it processes experimental ODSs to reveal extra local boundary effects caused by defects to reveal locations of defects. Experimental results show that small defects in circular plates can be pinpointed by these approaches. Moreover, a new concept of using the balance of elastic and kinetic energies within a mode cell for detecting defects in two- dimensional structures of irregular shapes is proposed.

Characteristics of convective structures of sodium layer in lower thermosphere (105-120 km) at Haikou (19.99°N, 110.34°E), China

NASA Astrophysics Data System (ADS)

Jiao, Jing; Yang, Guotao; Wang, Jihong; Zhang, Tiemin; Peng, Hongyan; Xun, Yuchang; Liu, Zhengkuan; Wang, Chi

2017-11-01

The atmospheric sodium layer normally occurs in the mesopause (80-105 km) region, but rarely in the lower thermosphere region (>105 km) at low latitude. We observed a kind of peculiar sodium layer in lower thermosphere at Haikou (19.99°N, 110.34°E)-the thermospheric convective sodium layer (TCSL) in a lidargram. The TCSL's sodium density unstably developed over time and appeared as several discontinuous convective shapes vertically. It is the first time convective sodium layer observed in the lower thermosphere region (105-120 km). Based on Haikou lidar data, we obtained 14 TCSL events during 180 nights from March 2010 to August 2012. Most of the apogees of the TCSL events are higher than 108 km. A TCSL event lasts several hours and is composed of several convective structures, with each veitical shape lasting ∼5-30 min. All TCSL events occurred during spring and summer, and generally appear near midnight (22:00-00:00 LT). The TCSL has potential regional feature and appears to be related to the thermospheric sporadic E (Es) layers, winds, and field-aligned ionospheric irregularities (FAI).

Generation of three-dimensional multiple spheroid model of olfactory ensheathing cells using floating liquid marbles

PubMed Central

Vadivelu, Raja K.; Ooi, Chin H.; Yao, Rebecca-Qing; Tello Velasquez, Johana; Pastrana, Erika; Diaz-Nido, Javier; Lim, Filip; Ekberg, Jenny A. K.; Nguyen, Nam-Trung; St John, James A.

2015-01-01

We describe a novel protocol for three-dimensional culturing of olfactory ensheathing cells (OECs), which can be used to understand how OECs interact with other cells in three dimensions. Transplantation of OECs is being trialled for repair of the paralysed spinal cord, with promising but variable results and thus the therapy needs improving. To date, studies of OEC behaviour in a multicellular environment have been hampered by the lack of suitable three-dimensional cell culture models. Here, we exploit the floating liquid marble, a liquid droplet coated with hydrophobic powder and placed on a liquid bath. The presence of the liquid bath increases the humidity and minimises the effect of evaporation. Floating liquid marbles allow the OECs to freely associate and interact to produce OEC spheroids with uniform shapes and sizes. In contrast, a sessile liquid marble on a solid surface suffers from evaporation and the cells aggregate with irregular shapes. We used floating liquid marbles to co-culture OECs with Schwann cells and astrocytes which formed natural structures without the confines of gels or bounding layers. This protocol can be used to determine how OECs and other cell types associate and interact while forming complex cell structures. PMID:26462469

Generation of three-dimensional multiple spheroid model of olfactory ensheathing cells using floating liquid marbles

NASA Astrophysics Data System (ADS)

Vadivelu, Raja K.; Ooi, Chin H.; Yao, Rebecca-Qing; Tello Velasquez, Johana; Pastrana, Erika; Diaz-Nido, Javier; Lim, Filip; Ekberg, Jenny A. K.; Nguyen, Nam-Trung; St John, James A.

2015-10-01

We describe a novel protocol for three-dimensional culturing of olfactory ensheathing cells (OECs), which can be used to understand how OECs interact with other cells in three dimensions. Transplantation of OECs is being trialled for repair of the paralysed spinal cord, with promising but variable results and thus the therapy needs improving. To date, studies of OEC behaviour in a multicellular environment have been hampered by the lack of suitable three-dimensional cell culture models. Here, we exploit the floating liquid marble, a liquid droplet coated with hydrophobic powder and placed on a liquid bath. The presence of the liquid bath increases the humidity and minimises the effect of evaporation. Floating liquid marbles allow the OECs to freely associate and interact to produce OEC spheroids with uniform shapes and sizes. In contrast, a sessile liquid marble on a solid surface suffers from evaporation and the cells aggregate with irregular shapes. We used floating liquid marbles to co-culture OECs with Schwann cells and astrocytes which formed natural structures without the confines of gels or bounding layers. This protocol can be used to determine how OECs and other cell types associate and interact while forming complex cell structures.

Predicting clinical outcomes in chordoma patients receiving immunotherapy: a comparison between volumetric segmentation and RECIST.

PubMed

Fenerty, Kathleen E; Folio, Les R; Patronas, Nicholas J; Marté, Jennifer L; Gulley, James L; Heery, Christopher R

2016-08-23

The Response Evaluation Criteria in Solid Tumors (RECIST) are the current standard for evaluating disease progression or therapy response in patients with solid tumors. RECIST 1.1 calls for axial, longest-diameter (or perpendicular short axis of lymph nodes) measurements of a maximum of five tumors, which limits clinicians' ability to adequately measure disease burden, especially in patients with irregularly shaped tumors. This is especially problematic in chordoma, a disease for which RECIST does not always adequately capture disease burden because chordoma tumors are typically irregularly shaped and slow-growing. Furthermore, primary chordoma tumors tend to be adjacent to vital structures in the skull or sacrum that, when compressed, lead to significant clinical consequences. Volumetric segmentation is a newer technology that allows tumor burden to be measured in three dimensions on either MR or CT. Here, we compared the ability of RECIST measurements and tumor volumes to predict clinical outcomes in a cohort of 21 chordoma patients receiving immunotherapy. There was a significant difference in radiologic time to progression Kaplan-Meier curves between clinical outcome groups using volumetric segmentation (P = 0.012) but not RECIST (P = 0.38). In several cases, changes in volume were earlier and more sensitive reflections of clinical status. RECIST is a useful evaluation method when obvious changes are occurring in patients with chordoma. However, in many cases, RECIST does not detect small changes, and volumetric assessment was capable of detecting changes and predicting clinical outcome earlier than RECIST. Although this study was small and retrospective, we believe our results warrant further research in this area.

IMAGING DIAGNOSIS-ULTRASONOGRAPHIC APPEARANCE OF SKELETAL MUSCLE METASTASES IN A DOG WITH HEMANGIOSARCOMA.

PubMed

Fabbi, Martina; Di Palma, Stefano; Manfredi, Sabrina; Gnudi, Giacomo; Miduri, Francesca; Daga, Eleonora; Melis, Gabriele Costantino; Bianchi, Ezio; Voccia, Simone; Volta, Antonella

2017-11-01

A 13-year-old spayed female German shepherd dog was presented for acute onset of lethargy, anorexia, and disseminated erythematous skin lesions. Thoracic radiographs and abdominal ultrasonographic findings were consistent with metastatic hemangiosarcoma. Multiple, ill-defined, irregularly shaped hypoechoic nodules were also detected within the thoracic and abdominal wall. Hemangiosarcoma metastases to the skeletal muscle were confirmed based on histopathological examination. Multivisceral involvement was also confirmed by necropsy. Metastatic neoplasia should be considered as a differential diagnosis for dogs with ill-defined, irregular, hypoechoic, intramuscular nodules. © 2016 American College of Veterinary Radiology.

Geostatistical regularization operators for geophysical inverse problems on irregular meshes

NASA Astrophysics Data System (ADS)

Jordi, C.; Doetsch, J.; Günther, T.; Schmelzbach, C.; Robertsson, J. OA

2018-05-01

Irregular meshes allow to include complicated subsurface structures into geophysical modelling and inverse problems. The non-uniqueness of these inverse problems requires appropriate regularization that can incorporate a priori information. However, defining regularization operators for irregular discretizations is not trivial. Different schemes for calculating smoothness operators on irregular meshes have been proposed. In contrast to classical regularization constraints that are only defined using the nearest neighbours of a cell, geostatistical operators include a larger neighbourhood around a particular cell. A correlation model defines the extent of the neighbourhood and allows to incorporate information about geological structures. We propose an approach to calculate geostatistical operators for inverse problems on irregular meshes by eigendecomposition of a covariance matrix that contains the a priori geological information. Using our approach, the calculation of the operator matrix becomes tractable for 3-D inverse problems on irregular meshes. We tested the performance of the geostatistical regularization operators and compared them against the results of anisotropic smoothing in inversions of 2-D surface synthetic electrical resistivity tomography (ERT) data as well as in the inversion of a realistic 3-D cross-well synthetic ERT scenario. The inversions of 2-D ERT and seismic traveltime field data with geostatistical regularization provide results that are in good accordance with the expected geology and thus facilitate their interpretation. In particular, for layered structures the geostatistical regularization provides geologically more plausible results compared to the anisotropic smoothness constraints.

The correlation function for density perturbations in an expanding universe. I - Linear theory

NASA Technical Reports Server (NTRS)

Mcclelland, J.; Silk, J.

1977-01-01

The evolution of the two-point correlation function for adiabatic density perturbations in the early universe is studied. Analytical solutions are obtained for the evolution of linearized spherically symmetric adiabatic density perturbations and the two-point correlation function for these perturbations in the radiation-dominated portion of the early universe. The results are then extended to the regime after decoupling. It is found that: (1) adiabatic spherically symmetric perturbations comparable in scale with the maximum Jeans length would survive the radiation-dominated regime; (2) irregular fluctuations are smoothed out up to the scale of the maximum Jeans length in the radiation era, but regular fluctuations might survive on smaller scales; (3) in general, the only surviving structures for irregularly shaped adiabatic density perturbations of arbitrary but finite scale in the radiation regime are the size of or larger than the maximum Jeans length in that regime; (4) infinite plane waves with a wavelength smaller than the maximum Jeans length but larger than the critical dissipative damping scale could survive the radiation regime; and (5) black holes would also survive the radiation regime and might accrete sufficient mass after decoupling to nucleate the formation of galaxies.

An emerging disease in blueberry

USDA-ARS?s Scientific Manuscript database

A new disorder was observed on southern highbush blueberry (Vaccinium corymbosum interspecific hybrids) in several southeastern states. Symptoms included irregularly shaped circular spots or blotches with green centers on the top and bottom of leaves. The disease was reported initially in the state ...

Origin of three-dimensional shapes of chondrules. I. Hydrodynamics simulations of rotating droplet exposed to high-velocity rarefied gas flow

NASA Astrophysics Data System (ADS)

Miura, Hitoshi; Nakamoto, Taishi; Doi, Masao

2008-09-01

The origin of three-dimensional shapes of chondrules is an important information to identify their formation mechanism in the early solar nebula. The measurement of their shapes by using X-ray computed topography suggested that they are usually close to perfect spheres, however, some of them have rugby-ball-like (prolate) shapes [Tsuchiyama, A., Shigeyoshi, R., Kawabata, T., Nakano, T., Uesugi, K., Shirono, S., 2003. Lunar Planet. Sci. 34, 1271-1272]. We considered that the prolate shapes reflect the deformations of chondrule precursor dust particles when they are heated and melted in the high velocity gas flow. In order to reveal the origin of chondrule shapes, we carried out the three-dimensional hydrodynamics simulations of a rotating molten chondrule exposed to the gas flow in the framework of the shock-wave heating model for chondrule formation. We adopted the gas ram pressure acting on the chondrule surface of p=10 dyncm in a typical shock wave. Considering that the chondrule precursor dust particle has an irregular shape before melting, the ram pressure causes a net torque to rotate the particle. The estimated angular velocity is ω=140 rads for the precursor radius of r=1 mm, though it has a different value depending on the irregularity of the shape. In addition, the rotation axis is likely to be perpendicular to the direction of the gas flow. Our calculations showed that the rotating molten chondrule elongates along the rotation axis, in contrast, shrinks perpendicularly to it. It is a prolate shape. The reason why the molten chondrule is deformed to a prolate shape was clearly discussed. Our study gives a complementary constraint for chondrule formation mechanisms, comparing with conventional chemical analyses and dynamic crystallization experiments that have mainly constrained the thermal evolutions of chondrules.

The relationship between dermal papillary structure and skin surface properties, color, and elasticity.

PubMed

Mizukoshi, K; Nakamura, T; Oba, A

2016-08-01

The skin contains an undulating structure called the dermal papillary structure between the border of the epidermis and dermis. The physiological importance of the dermal papillary structures has been discussed, however, the dermal papillary structures have never been evaluated for their contribution to skin appearance. In this study, we investigated the correlation between the dermal papillary structure and skin color and elasticity. In addition, the relationship was validated with skin model experiments. The dermal papillary structures in the skin of the female cheek were quantitatively measured by in vivo confocal laser scanning microscopy images. In addition, the skin color and elasticity were measured at the same site. A skin model with dermal papilla-like structures was created by referring to the optical and shape properties of the skin using agar gel and a scattering sheet. Correlations were found between the dermal papillary structures and skin color irregularity and skin elasticity. These relationships were verified by the experiments employing a skin model. The results of this study indicated that the dermal papillary structure is also an important factor for skin appearance such as color and elasticity. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Quantitative morphometric analysis of hepatocellular carcinoma: development of a programmed algorithm and preliminary application.

PubMed

Yap, Felix Y; Bui, James T; Knuttinen, M Grace; Walzer, Natasha M; Cotler, Scott J; Owens, Charles A; Berkes, Jamie L; Gaba, Ron C

2013-01-01

The quantitative relationship between tumor morphology and malignant potential has not been explored in liver tumors. We designed a computer algorithm to analyze shape features of hepatocellular carcinoma (HCC) and tested feasibility of morphologic analysis. Cross-sectional images from 118 patients diagnosed with HCC between 2007 and 2010 were extracted at the widest index tumor diameter. The tumor margins were outlined, and point coordinates were input into a MATLAB (MathWorks Inc., Natick, Massachusetts, USA) algorithm. Twelve shape descriptors were calculated per tumor: the compactness, the mean radial distance (MRD), the RD standard deviation (RDSD), the RD area ratio (RDAR), the zero crossings, entropy, the mean Feret diameter (MFD), the Feret ratio, the convex hull area (CHA) and perimeter (CHP) ratios, the elliptic compactness (EC), and the elliptic irregularity (EI). The parameters were correlated with the levels of alpha-fetoprotein (AFP) as an indicator of tumor aggressiveness. The quantitative morphometric analysis was technically successful in all cases. The mean parameters were as follows: compactness 0.88±0.086, MRD 0.83±0.056, RDSD 0.087±0.037, RDAR 0.045±0.023, zero crossings 6±2.2, entropy 1.43±0.16, MFD 4.40±3.14 cm, Feret ratio 0.78±0.089, CHA 0.98±0.027, CHP 0.98±0.030, EC 0.95±0.043, and EI 0.95±0.023. MFD and RDAR provided the widest value range for the best shape discrimination. The larger tumors were less compact, more concave, and less ellipsoid than the smaller tumors (P < 0.0001). AFP-producing tumors displayed greater morphologic irregularity based on several parameters, including compactness, MRD, RDSD, RDAR, entropy, and EI (P < 0.05 for all). Computerized HCC image analysis using shape descriptors is technically feasible. Aggressively growing tumors have wider diameters and more irregular margins. Future studies will determine further clinical applications for this morphologic analysis.

Investigation into the Origin and Character of Surficial Sedimentary Deposits at the Midshore Regional Solid Waste Facility near Easton, Maryland

USGS Publications Warehouse

Smoot, Joseph P.; Newell, Wayne L.; DeJong, Benjamin D.

2009-01-01

A temporary exposure at the Midshore Regional Solid Waste Facility near Easton, MD, provided an opportunity to document the characteristics of the complex assemblage of surficial facies in that area. This unusually large cross section allowed interpretation of the changing processes that shaped the landscape in response to climate change through the late Pleistocene. Eight stratigraphic units were recognized: (1) gray, fossiliferous, muddy silt of the marine Miocene Choptank Formation; (2) coarse, crossbedded conglomerate of the late Miocene to Pliocene fluvial Pensauken Formation; (3) bioturbated muddy conglomerate interpreted as deposits of small colluvial fans; (4) pebbly, quartzose sand overlying a planar erosional surface reflecting a marine transgression; (5) irregular pods and lenses of sand and gravel deformed into bowl-shaped folds and faulted, which are interpreted as wind deposits over a semipermanent snow cover (niveo-aeolian deposits); (6) crossbedded sand and conglomerate with abundant mud partings indicating tidal influences on sinuous stream channels; (7) heavily bioturbated silt and sand with abundant root casts and flattened vesicles interpreted as aeolian loess deposits in marshy fens; and (8) pebbly sand and mud with scattered boulders and cobbles that reflect modern infill of the excavation by the operators. Soils formed on units 3, 4, and 7. Superimposed on units 4, 5, and 7 is evidence of deep freezing and permafrost development and subsequent thermokarst development after thawing, which includes large, complexly filled wedge-shaped cracks, deformed bedding and faults, fluid-injection structures, and spherical blobs of sand and mud. Each of the stratigraphic units has irregular distributions and lateral changes. The results of this study provide a unique insight into the geometry of surficial deposits that will help facilitate mapping of units, interpretation of cored intervals, and understanding of ground-penetrating radar profiles. The study also documents the widespread effects of permafrost during the last glacial episode well south of the maximum advance of ice sheets.

Collection strategy, inner morphology, and size distribution of dust particles in ASDEX Upgrade

NASA Astrophysics Data System (ADS)

Balden, M.; Endstrasser, N.; Humrickhouse, P. W.; Rohde, V.; Rasinski, M.; von Toussaint, U.; Elgeti, S.; Neu, R.; the ASDEX Upgrade Team

2014-07-01

The dust collection and analysis strategy in ASDEX Upgrade (AUG) is described. During five consecutive operation campaigns (2007-2011), Si collectors were installed, which were supported by filtered vacuum sampling and collection with adhesive tapes in 2009. The outer and inner morphology (e.g. shape) and elemental composition of the collected particles were analysed by scanning electron microscopy. The majority of the ˜50 000 analysed particles on the Si collectors of campaign 2009 contain tungsten—the plasma-facing material in AUG—and show basically two different types of outer appearance: spheroids and irregularly shaped particles. By far most of the W-dominated spheroids consist of a solid W core, i.e. solidified W droplets. A part of these particles is coated with a low-Z material; a process that seems to happen presumably in the far scrape-off layer plasma. In addition, some conglomerates of B, C and W appear as spherical particles after their contact with plasma. By far most of the particles classified as B-, C- and W-dominated irregularly shaped particles consist of the same conglomerate with varying fraction of embedded W in the B-C matrix and some porosity, which can exceed 50%. The fragile structures of many conglomerates confirm the absence of intensive plasma contact. Both the ablation and mobilization of conglomerate material and the production of W droplets are proposed to be triggered by arcing. The size distribution of each dust particle class is best described by a log-normal distribution allowing an extrapolation of the dust volume and surface area. The maximum in this distribution is observed above the resolution limit of 0.28 µm only for the W-dominated spheroids, at around 1 µm. The amount of W-containing dust is extrapolated to be less than 300 mg on the horizontal areas of AUG.

Study on the Unsteady Creep of Composite Beams with an Irregular Laminar Fibrous Structure Made from Nonlinear Hereditary Materials

NASA Astrophysics Data System (ADS)

Yankovskii, A. P.

2017-09-01

The creep of homogenous and hybrid composite beams of an irregular laminar fibrous structure is investigated. The beams consist of thin walls and flanges (load-carrying layers). The walls may be reinforced longitudinally or crosswise in the plane, and the load-carrying layers are reinforced in the longitudinal direction. The mechanical behavior of phase materials is described by the Rabotnov nonlinear hereditary theory of creep taking into account their possible different resistance to tension and compression. On the basis of hypotheses of the Timoshenko theory, with using the method of time steps, a problem is formulated for the inelastic bending deformation of such beams with account of the weakened resistance of their walls to the transverse shear. It is shown that, at discrete instants of time, the mechanical behavior of such structures can formally be described by the governing relations for composite beams made of nonlinear elastic anisotropic materials with a known initial stress state. The method of successive iterations, similar to the method of variable parameters of elasticity, is used to linearize the boundary-value problem at each instant of time. The bending deformation is investigated for homogeneous and reinforced cantilever and simply supported beams in creep under the action of a uniformly distributed transverse load. The cross sections of the beams considered are I-shaped. It is found that the use of the classical theory for such beams leads to the prediction of indefensibly underestimated flexibility, especially in long-term loading. It is shown that, in beams with reinforced load-carrying layers, the creep mainly develops due to the shear strains of walls. It is found that, in short- and long-term loadings of composite beams, the reinforcement structures rational by the criterion of minimum flexibility are different.

Effect of Particle Morphology on the Reactivity of Explosively Dispersed Titanium Particles

NASA Astrophysics Data System (ADS)

Frost, David L.; Cairns, Malcolm; Goroshin, Samuel; Zhang, Fan

2009-12-01

The effect of particle morphology on the reaction of titanium (Ti) particles explosively dispersed during the detonation of either cylindrical or spherical charges has been investigated experimentally. The explosive charges consisted of packed beds of Ti particles saturated with nitromethane. The reaction behaviour of irregularly-shaped Ti particles in three size ranges is compared with tests with spherical Ti particles. The particle reaction is strongly dependent on particle morphology, e.g., 95 μm spherical Ti particles failed to ignite (in cylinders up to 49 mm in dia), whereas similarly sized irregular Ti particles readily ignited. For irregular particles, the uniformity of ignition on the particle cloud surface was almost independent of particle size, but depended on charge diameter. As the charge diameter was reduced, ignition in the conically expanding particle cloud occurred only at isolated spots or bands. For spherical charges, whereas large irregular Ti particles ignited promptly and uniformly throughout the particle cloud, the smallest particles dispersed nonuniformly and ignition occurred at isolated locations after a delay. Hence the charge geometry, as well as particle morphology, influences the reaction behaviour of the particles.

Characterization of dust from blast furnace cast house de-dusting.

PubMed

Lanzerstorfer, Christof

2017-10-01

During casting of liquid iron and slag, a considerable amount of dust is emitted into the cast house of a blast furnace (BF). Usually, this dust is extracted via exhaust hoods and subsequently separated from the ventilation air. In most BFs the cast house dust is recycled. In this study a sample of cast house dust was split by air classification into five size fractions, which were then analysed. Micrographs showed that the dominating particle type in all size fractions is that of single spherical-shaped particles. However, some irregular-shaped particles were also found and in the finest size fraction also some agglomerates were present. Almost spherical particles consisted of Fe and O, while highly irregular-shaped particles consisted of C. The most abundant element was Fe, followed by Ca and C. These elements were distributed relatively uniformly in the size fractions. As, Cd, Cu, K, Pb, S, Sb and Zn were enriched significantly in the fine size fractions. Thus, air classification would be an effective method for improved recycling. By separating a small fraction of fines (about 10-20%), a reduction of the mass of Zn in the coarse dust recycled in the range of 40-55% would be possible.

Baseline-dependent sampling and windowing for radio interferometry: data compression, field-of-interest shaping, and outer field suppression

NASA Astrophysics Data System (ADS)

Atemkeng, M.; Smirnov, O.; Tasse, C.; Foster, G.; Keimpema, A.; Paragi, Z.; Jonas, J.

2018-07-01

Traditional radio interferometric correlators produce regular-gridded samples of the true uv-distribution by averaging the signal over constant, discrete time-frequency intervals. This regular sampling and averaging then translate to be irregular-gridded samples in the uv-space, and results in a baseline-length-dependent loss of amplitude and phase coherence, which is dependent on the distance from the image phase centre. The effect is often referred to as `decorrelation' in the uv-space, which is equivalent in the source domain to `smearing'. This work discusses and implements a regular-gridded sampling scheme in the uv-space (baseline-dependent sampling) and windowing that allow for data compression, field-of-interest shaping, and source suppression. The baseline-dependent sampling requires irregular-gridded sampling in the time-frequency space, i.e. the time-frequency interval becomes baseline dependent. Analytic models and simulations are used to show that decorrelation remains constant across all the baselines when applying baseline-dependent sampling and windowing. Simulations using MeerKAT telescope and the European Very Long Baseline Interferometry Network show that both data compression, field-of-interest shaping, and outer field-of-interest suppression are achieved.

On the morphology of the scattering medium as seen by MST/ST radars

NASA Technical Reports Server (NTRS)

Gage, K. S.

1983-01-01

Much is learned about the morphology of the small scale structures of the atmosphere from analysis of echoes observed by MST radars. The use of physical models enables a synthesis of diverse observations. Each model contains an implicit assumption about the nature of the irregularity structure of the medium. A comparison is made between the irregularity structure implicit in several models and what is known about the structure of the medium.

Automatic Detection of Blue-White Veil and Related Structures in Dermoscopy Images

PubMed Central

Celebi, M. Emre; Iyatomi, Hitoshi; Stoecker, William V.; Moss, Randy H.; Rabinovitz, Harold S.; Argenziano, Giuseppe; Soyer, H. Peter

2011-01-01

Dermoscopy is a non-invasive skin imaging technique, which permits visualization of features of pigmented melanocytic neoplasms that are not discernable by examination with the naked eye. One of the most important features for the diagnosis of melanoma in dermoscopy images is the blue-white veil (irregular, structureless areas of confluent blue pigmentation with an overlying white “ground-glass” film). In this article, we present a machine learning approach to the detection of blue-white veil and related structures in dermoscopy images. The method involves contextual pixel classification using a decision tree classifier. The percentage of blue-white areas detected in a lesion combined with a simple shape descriptor yielded a sensitivity of 69.35% and a specificity of 89.97% on a set of 545 dermoscopy images. The sensitivity rises to 78.20% for detection of blue veil in those cases where it is a primary feature for melanoma recognition. PMID:18804955

Charging of Aggregate Grains in Astrophysical Environments

NASA Astrophysics Data System (ADS)

Ma, Qianyu; Matthews, Lorin S.; Land, Victor; Hyde, Truell W.

2013-02-01

The charging of dust grains in astrophysical environments has been investigated with the assumption that these grains are homogeneous spheres. However, there is evidence which suggests that many grains in astrophysical environments are irregularly shaped aggregates. Recent studies have shown that aggregates acquire higher charge-to-mass ratios due to their complex structures, which in turn may alter their subsequent dynamics and evolution. In this paper, the charging of aggregates is examined including secondary electron emission and photoemission in addition to primary plasma currents. The results show that the equilibrium charge on aggregates can differ markedly from spherical grains with the same mass, but that the charge can be estimated for a given environment based on structural characteristics of the grain. The "small particle effect" due to secondary electron emission is also important for de terming the charge of micron-sized aggregates consisting of nano-sized particles.

Flow environment and matrix structure interact to determine spatial competition in Pseudomonas aeruginosa biofilms.

PubMed

Nadell, Carey D; Ricaurte, Deirdre; Yan, Jing; Drescher, Knut; Bassler, Bonnie L

2017-01-13

Bacteria often live in biofilms, which are microbial communities surrounded by a secreted extracellular matrix. Here, we demonstrate that hydrodynamic flow and matrix organization interact to shape competitive dynamics in Pseudomonas aeruginosa biofilms. Irrespective of initial frequency, in competition with matrix mutants, wild-type cells always increase in relative abundance in planar microfluidic devices under simple flow regimes. By contrast, in microenvironments with complex, irregular flow profiles - which are common in natural environments - wild-type matrix-producing and isogenic non-producing strains can coexist. This result stems from local obstruction of flow by wild-type matrix producers, which generates regions of near-zero shear that allow matrix mutants to locally accumulate. Our findings connect the evolutionary stability of matrix production with the hydrodynamics and spatial structure of the surrounding environment, providing a potential explanation for the variation in biofilm matrix secretion observed among bacteria in natural environments.

Holcophloeus caldarai (Coleoptera: Curculionidae: Holcorhinini) a new weevil species from Morocco.

PubMed

Borovec, Roman; KoŠŤÁl, Michael; BÁborskÁ, Zuzana

2018-04-05

Holcophloeus caldarai sp. n. is described as a fifth species of the genus from central Morocco. The new species differs from all other species of the genus and, generally the entire tribe, by unique irregularly star-shaped appressed scales.

Equatorial Density Irregularity Structures at Intermediate Scales and Their Temporal Evolution

NASA Technical Reports Server (NTRS)

Kil, Hyosub; Heelis, R. A.

1998-01-01

We examine high resolution measurements of ion density in the equatorial ionosphere from the AE-E satellite during the years 1977-1981. Structure over spatial scales from 18 km to 200 m is characterized by the spectrum of irregularities at larger and smaller scales and at altitudes above 350 km and below 300 km. In the low-altitude region, only small amplitude large-scale (lambda greater than 5 km) density modulations are often observed, and thus the power spectrum of these density structures exhibits a steep spectral slope at kilometer scales. In the high-altitude region, sinusoidal density fluctuations, characterized by enhanced power near 1-km scale, are frequently observed during 2000-0200 LT. However, such fluctuations are confined to regions at the edges of larger bubble structures where the average background density is high. Small amplitude irregularity structures, observed at early local time hours, grow rapidly to high-intensity structures in about 90 min. Fully developed structures, which are observed at late local time hours, decay very slowly producing only-small differences in spectral characteristics even 4 hours later. The local time evolution of irregularity structure is investigated by using average statistics for low-(1% less than sigma less than 5%) and high-intensity (sigma greater than 10%) structures. At lower altitudes, little chance in the spectral slope is seen as a function of local time, while at higher attitudes the growth and maintenance of structures near 1 km scales dramatically affects the spectral slope.

Atomically resolved structural determination of graphene and its point defects via extrapolation assisted phase retrieval

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

Latychevskaia, Tatiana; Fink, Hans-Werner

Previously reported crystalline structures obtained by an iterative phase retrieval reconstruction of their diffraction patterns seem to be free from displaying any irregularities or defects in the lattice, which appears to be unrealistic. We demonstrate here that the structure of a nanocrystal including its atomic defects can unambiguously be recovered from its diffraction pattern alone by applying a direct phase retrieval procedure not relying on prior information of the object shape. Individual point defects in the atomic lattice are clearly apparent. Conventional phase retrieval routines assume isotropic scattering. We show that when dealing with electrons, the quantitatively correct transmission functionmore » of the sample cannot be retrieved due to anisotropic, strong forward scattering specific to electrons. We summarize the conditions for this phase retrieval method and show that the diffraction pattern can be extrapolated beyond the original record to even reveal formerly not visible Bragg peaks. Such extrapolated wave field pattern leads to enhanced spatial resolution in the reconstruction.« less

Fabrication of Multscale Fractal-Like Structures by Controlling Fluid Interface Instability

PubMed Central

Islam, Tanveer ul; Gandhi, Prasanna S.

2016-01-01

Nature, in quest for the best designs has shaped its vital systems into fractal geometries. Effectual way of spontaneous fabrication of scalable, ordered fractal-like structures by controlling Saffman-Taylor instability in a lifted Hele-Shaw cell is deployed here. In lifted Hele-Shaw cell uncontrolled penetration of low-viscosity fluid into its high-viscosity counterpart is known to develop irregular, non-repeatable, normally short-lived, branched patterns. We propose and characterize experimentally anisotropies in a form of spatially distributed pits on the cell plates to control initiation and further penetration of non-splitting fingers. The proposed control over shielding mechanism yields recipes for fabrication of families of ordered fractal-like patterns of multiple generations. As an example, we demonstrate and characterize fabrication of a Cayley tree fractal-like pattern. The patterns, in addition, are retained permanently by employing UV/thermally curable fluids. The proposed technique thus establishes solid foundation for bio-mimicking natural structures spanning multiple-scales for scientific and engineering use. PMID:27849003

Process monitoring of additive manufacturing by using optical tomography

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

Zenzinger, Guenter, E-mail: guenter.zenzinger@mtu.de, E-mail: alexander.ladewig@mtu.de; Bamberg, Joachim, E-mail: guenter.zenzinger@mtu.de, E-mail: alexander.ladewig@mtu.de; Ladewig, Alexander, E-mail: guenter.zenzinger@mtu.de, E-mail: alexander.ladewig@mtu.de

2015-03-31

Parts fabricated by means of additive manufacturing are usually of complex shape and owing to the fabrication procedure by using selective laser melting (SLM), potential defects and inaccuracies are often very small in lateral size. Therefore, an adequate quality inspection of such parts is rather challenging, while non-destructive-techniques (NDT) are difficult to realize, but considerable efforts are necessary in order to ensure the quality of SLM-parts especially used for aerospace components. Thus, MTU Aero Engines is currently focusing on the development of an Online Process Control system which monitors and documents the complete welding process during the SLM fabrication procedure.more » A high-resolution camera system is used to obtain images, from which tomographic data for a 3dim analysis of SLM-parts are processed. From the analysis, structural irregularities and structural disorder resulting from any possible erroneous melting process become visible and may be allocated anywhere within the 3dim structure. Results of our optical tomography (OT) method as obtained on real defects are presented.« less

Fabrication of Multscale Fractal-Like Structures by Controlling Fluid Interface Instability

NASA Astrophysics Data System (ADS)

Islam, Tanveer Ul; Gandhi, Prasanna S.

2016-11-01

Nature, in quest for the best designs has shaped its vital systems into fractal geometries. Effectual way of spontaneous fabrication of scalable, ordered fractal-like structures by controlling Saffman-Taylor instability in a lifted Hele-Shaw cell is deployed here. In lifted Hele-Shaw cell uncontrolled penetration of low-viscosity fluid into its high-viscosity counterpart is known to develop irregular, non-repeatable, normally short-lived, branched patterns. We propose and characterize experimentally anisotropies in a form of spatially distributed pits on the cell plates to control initiation and further penetration of non-splitting fingers. The proposed control over shielding mechanism yields recipes for fabrication of families of ordered fractal-like patterns of multiple generations. As an example, we demonstrate and characterize fabrication of a Cayley tree fractal-like pattern. The patterns, in addition, are retained permanently by employing UV/thermally curable fluids. The proposed technique thus establishes solid foundation for bio-mimicking natural structures spanning multiple-scales for scientific and engineering use.

Adaptive grid embedding for the two-dimensional flux-split Euler equations. M.S. Thesis

NASA Technical Reports Server (NTRS)

Warren, Gary Patrick

1990-01-01

A numerical algorithm is presented for solving the 2-D flux-split Euler equations using a multigrid method with adaptive grid embedding. The method uses an unstructured data set along with a system of pointers for communication on the irregularly shaped grid topologies. An explicit two-stage time advancement scheme is implemented. A multigrid algorithm is used to provide grid level communication and to accelerate the convergence of the solution to steady state. Results are presented for a subcritical airfoil and a transonic airfoil with 3 levels of adaptation. Comparisons are made with a structured upwind Euler code which uses the same flux integration techniques of the present algorithm. Good agreement is obtained with converged surface pressure coefficients. The lift coefficients of the adaptive code are within 2 1/2 percent of the structured code for the sub-critical case and within 4 1/2 percent of the structured code for the transonic case using approximately one-third the number of grid points.

Wound stability and surgically induced corneal astigmatism after transconjunctival single-plane sclerocorneal incision cataract surgery.

PubMed

Hayashi, Ken; Ogawa, Soichiro; Yoshida, Motoaki; Yoshimura, Koichi

2017-01-01

To compare intraocular pressure (IOP) immediately after cataract surgery, and surgically induced corneal astigmatism (SIA) and corneal shape changes between eyes with transconjunctival single-plane sclerocorneal incisions (TSSIs) and eyes with clear corneal incisions (CCIs). Bilateral eyes of 64 patients undergoing phacoemulsification were randomized to undergo 2.4-mm temporal TSSI or CCI. IOP was measured preoperatively, and in the immediate postoperative periods. SIA was determined using vector analysis, and corneal shape changes and irregular astigmatism were evaluated using a videokeratography preoperatively, and in the early postoperative periods. Wound hydration was performed in 23 eyes (35.9 %) of the TSSI group and in 60 (93.8 %) of the CCI group (P < 0.0001). Mean IOP was significantly higher in the TSSI group than in the CCI group at 30, 60, and 120 min postoperatively (P ≤ 0.0179). SIA tended to be smaller in the TSSI group than the CCI group, but the difference was not significant. The higher order irregular astigmatism was smaller in the TSSI group than in the CCI group at 2 days (P = 0.0312). The videokeratography revealed a wound-related flattening postoperatively in both groups; this change disappeared within 4 weeks in the TSSI group, whereas it persisted until 12 weeks in the CCI group. IOP was significantly higher immediately after TSSI than after CCI and required less wound hydration, suggesting better stability with TSSI. Higher order irregular astigmatism and wound-related corneal flattening were smaller after TSSI than after CCI in the early periods, suggesting that fewer corneal shape changes with TSSI.

Numerical simulation of unsteady generalized Newtonian blood flow through differently shaped distensible arterial stenoses.

PubMed

Sarifuddin; Chakravarty, S; Mandal, P K; Layek, G C

2008-01-01

An updated numerical simulation of unsteady generalized Newtonian blood flow through differently shaped distensible arterial stenoses is developed. A shear-thinning fluid modelling the deformation dependent viscosity of blood is considered for the characterization of generalized Newtonian behaviour of blood. The arterial model is treated as two-dimensional and axisymmetric with an outline of the stenosis obtained from a three-dimensional casting of a mildly stenosed artery. The full Navier-Stokes equations governing blood flow are written in the dimensionless form and the solution is accomplished by finite time-step advancement through their finite difference staggered grid representations. The marker and cell (MAC) method comprising the use of a set of marker particles moving with the fluid is used for the purpose. Results are obtained for three differently shaped stenoses - irregular, smooth and cosine curve representations. The present results do agree well with those of existing investigations in the steady state, but contrary to their conclusions the present findings demonstrate that the excess pressure drop across the cosine and the smooth stenoses is caused by neither their smoothness nor their higher degree of symmetry relative to the irregular stenosis, but is rather an effect of area cover with respect to the irregular stenosis. This effect clearly prevails throughout the entire physiological range of Reynolds numbers. Further the in-depth study in flow patterns reveals the development of flow separation zones in the diverging part of the stenosis towards the arterial wall, and they are influenced by non-Newtonian blood rheology, distensibility of the wall and flow unsteadiness in order to validate the applicability of the present model.

Validation of 3D documentation of palatal soft tissue shape, color, and irregularity with intraoral scanning.

PubMed

Deferm, Julie T; Schreurs, Ruud; Baan, Frank; Bruggink, Robin; Merkx, Matthijs A W; Xi, Tong; Bergé, Stefaan J; Maal, Thomas J J

2018-04-01

The purpose of this study was to assess the feasibility of 3D intraoral scanning for documentation of palatal soft tissue by evaluating the accuracy of shape, color, and curvature. Intraoral scans of ten participants' upper dentition and palate were acquired with the TRIOS® 3D intraoral scanner by two observers. Conventional impressions were taken and digitized as a gold standard. The resulting surface models were aligned using an Iterative Closest Point approach. The absolute distance measurements between the intraoral models and the digitized impression were used to quantify the trueness and precision of intraoral scanning. The mean color of the palatal soft tissue was extracted in HSV (hue, saturation, value) format to establish the color precision. Finally, the mean curvature of the surface models was calculated and used for surface irregularity. Mean average distance error between the conventional impression models and the intraoral models was 0.02 ± 0.07 mm (p = 0.30). Mean interobserver color difference was - 0.08 ± 1.49° (p = 0.864), 0.28 ± 0.78% (p = 0.286), and 0.30 ± 1.14% (p = 0.426) for respectively hue, saturation, and value. The interobserver differences for overall and maximum surface irregularity were 0.01 ± 0.03 and 0.00 ± 0.05 mm. This study supports the hypothesis that the intraoral scan can perform a 3D documentation of palatal soft tissue in terms of shape, color, and curvature. An intraoral scanner can be an objective tool, adjunctive to the clinical examination of the palatal tissue.

Pulmonary tumor measurements from x-ray computed tomography in one, two, and three dimensions.

PubMed

Villemaire, Lauren; Owrangi, Amir M; Etemad-Rezai, Roya; Wilson, Laura; O'Riordan, Elaine; Keller, Harry; Driscoll, Brandon; Bauman, Glenn; Fenster, Aaron; Parraga, Grace

2011-11-01

We evaluated the accuracy and reproducibility of three-dimensional (3D) measurements of lung phantoms and patient tumors from x-ray computed tomography (CT) and compared these to one-dimensional (1D) and two-dimensional (2D) measurements. CT images of three spherical and three irregularly shaped tumor phantoms were evaluated by three observers who performed five repeated measurements. Additionally, three observers manually segmented 29 patient lung tumors five times each. Follow-up imaging was performed for 23 tumors and response criteria were compared. For a single subject, imaging was performed on nine occasions over 2 years to evaluate multidimensional tumor response. To evaluate measurement accuracy, we compared imaging measurements to ground truth using analysis of variance. For estimates of precision, intraobserver and interobserver coefficients of variation and intraclass correlations (ICC) were used. Linear regression and Pearson correlations were used to evaluate agreement and tumor response was descriptively compared. For spherical shaped phantoms, all measurements were highly accurate, but for irregularly shaped phantoms, only 3D measurements were in high agreement with ground truth measurements. All phantom and patient measurements showed high intra- and interobserver reproducibility (ICC >0.900). Over a 2-year period for a single patient, there was disagreement between tumor response classifications based on 3D measurements and those generated using 1D and 2D measurements. Tumor volume measurements were highly reproducible and accurate for irregular, spherical phantoms and patient tumors with nonuniform dimensions. Response classifications obtained from multidimensional measurements suggest that 3D measurements provide higher sensitivity to tumor response. Copyright © 2011 AUR. Published by Elsevier Inc. All rights reserved.

Cell structures caused by settling particles in turbulent Rayleigh-Bénard convection

NASA Astrophysics Data System (ADS)

Lee, Changhoon; Park, Sangro

2016-11-01

Turbulent thermal convection is an important phenomenon frequently found in nature and industrial processes, often with laden particles. In the last several decades, the vast majority of studies have addressed single phase convective flow with focus on the scaling relation of flow parameters associated with heat transfer. Particle-laden Rayleigh-Bénard convection, however, has not been sufficiently studied. In this study, modulation of cell structures by settling particles in turbulent Rayleigh-Bénard convection in a doubly periodic square channel is investigated using direct numerical simulation with a point particle approach. Flow parameters are fixed at Rayleigh number=106, Prandtl number=0.7, the aspect ratio=6, and Froude number=0.19. We report from the simulations that settling heavy particles modulate irregular large-scale thermal plume structures into organized polygonal cell structures. Different shapes of flow structures are obtained for different particle diameters and mass loadings. We found that polygonal cell structures arise due to asymmetric feedback force exerted by particles onto hot and cold plumes. Increasing the number of particles augments the asymmetry and the polygonal cell structures become smaller, eventually going to the hexagonal structures.

MO-F-CAMPUS-T-05: Correct Or Not to Correct for Rotational Patient Set-Up Errors in Stereotactic Radiosurgery

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

Briscoe, M; Ploquin, N; Voroney, JP

2015-06-15

Purpose: To quantify the effect of patient rotation in stereotactic radiation therapy and establish a threshold where rotational patient set-up errors have a significant impact on target coverage. Methods: To simulate rotational patient set-up errors, a Matlab code was created to rotate the patient dose distribution around the treatment isocentre, located centrally in the lesion, while keeping the structure contours in the original locations on the CT and MRI. Rotations of 1°, 3°, and 5° for each of the pitch, roll, and yaw, as well as simultaneous rotations of 1°, 3°, and 5° around all three axes were applied tomore » two types of brain lesions: brain metastasis and acoustic neuroma. In order to analyze multiple tumour shapes, these plans included small spherical (metastasis), elliptical (acoustic neuroma), and large irregular (metastasis) tumour structures. Dose-volume histograms and planning target volumes were compared between the planned patient positions and those with simulated rotational set-up errors. The RTOG conformity index for patient rotation was also investigated. Results: Examining the tumour volumes that received 80% of the prescription dose in the planned and rotated patient positions showed decreases in prescription dose coverage of up to 2.3%. Conformity indices for treatments with simulated rotational errors showed decreases of up to 3% compared to the original plan. For irregular lesions, degradation of 1% of the target coverage can be seen for rotations as low as 3°. Conclusions: This data shows that for elliptical or spherical targets, rotational patient set-up errors less than 3° around any or all axes do not have a significant impact on the dose delivered to the target volume or the conformity index of the plan. However the same rotational errors would have an impact on plans for irregular tumours.« less

Simulation of dynamic vehicle-track interaction on small radius curves

NASA Astrophysics Data System (ADS)

Torstensson, Peter T.; Nielsen, Jens C. O.

2011-11-01

A time-domain method for the simulation of general three-dimensional dynamic interaction between a vehicle and a curved railway track, accounting for a prescribed relative wheel-rail displacement excitation in a wide frequency range (up to several hundred Hz), is presented. The simulation model is able to capture the low-frequency vehicle dynamics simultaneously due to curving and the high-frequency track dynamics due to the excitation by, for example, the short-pitch corrugation on the low rail. The adopted multibody dynamics formulation considers inertia forces, such as centrifugal and Coriolis forces, as well as the structural flexibility of vehicle and track components. To represent a wheel/rail surface irregularity, isoparametric two-dimensional elements able to describe generally curved surface shapes are used. The computational effort is reduced by including only one bogie in the vehicle model. The influence of the low-frequency vehicle dynamics of the remaining parts of the vehicle is considered by pre-calculated look-up tables of forces and moments acting in the secondary suspension. For a track model taken as rigid, good agreement is observed between the results calculated with the presented model and a commercial software. The features of the model are demonstrated by a number of numerical examples. The influence of the structural flexibility of the wheelset and track on wheel-rail contact forces is investigated. For a discrete rail irregularity excitation, it is shown that the longitudinal creep force is significantly influenced by the wheelset eigenmodes. The introduction of a velocity-dependent friction law is found to induce an oscillation in the tangential contact force on the low rail with a frequency corresponding to the first anti-symmetric torsional mode of the wheelset. Further, under the application of driving moments on the two wheelsets and excitation by a discrete irregularity on the high rail, the frequency content of the tangential contact forces on the low rail is significantly influenced by the P2 resonance as well as by several wheelset eigenmodes.

Splash control of drop impacts with geometric targets.

PubMed

Juarez, Gabriel; Gastopoulos, Thomai; Zhang, Yibin; Siegel, Michael L; Arratia, Paulo E

2012-02-01

Drop impacts on solid and liquid surfaces exhibit complex dynamics due to the competition of inertial, viscous, and capillary forces. After impact, a liquid lamella develops and expands radially, and under certain conditions, the outer rim breaks up into an irregular arrangement of filaments and secondary droplets. We show experimentally that the lamella expansion and subsequent breakup of the outer rim can be controlled by length scales that are of comparable dimension to the impacting drop diameter. Under identical impact parameters (i.e., fluid properties and impact velocity) we observe unique splashing dynamics by varying the target cross-sectional geometry. These behaviors include (i) geometrically shaped lamellae and (ii) a transition in splashing stability, from regular to irregular splashing. We propose that regular splashes are controlled by the azimuthal perturbations imposed by the target cross-sectional geometry and that irregular splashes are governed by the fastest-growing unstable Plateau-Rayleigh mode.

Modelling the horizontal structure of mid-latitude E(s) from its refraction effects on F-region echoes

NASA Astrophysics Data System (ADS)

Barnes, R. I.

1991-02-01

The observation of the refraction of F-region echoes presently reported implies that significant horizontal structure exists within some E(s) clouds. A modeling of the data collected with the Bribie Island HF radar indicates that wind shear variations can account for examples in which irregularities either pass through, or pass with, existing layers of E(s) which create the cloudy, nonblanketing variety of E(s). The blanketing variety of E(s) seems to have little or no horizontal structure, and most likely drifts with the same velocity as the irregularities which produce nonblanketing E(s). Irregularities with strong horizontal gradients act as diverging lenses, leading to an overestimation of cloud size via simple occulting geometry.

CRAF Mission: An opportunity for exobiology

NASA Technical Reports Server (NTRS)

Neugebauer, Marcia; Weissman, Paul

1992-01-01

The Halley missions of 1986 gave us a first, quick glimpse of a comet nucleus and the first in situ measurements of cometary gas and dust. Many of our basic ideas about cometary nuclei were confirmed while a number of startling new discoveries were also made. However, in many respects the very fast Halley flybys raised more questions than they answered. We learned, for example, that comets contain a large amount of organic material but we were unable to determine precisely which organic molecules were present. We learned, too, that the nucleus of a comet is a dark, irregularly shaped body, but we could determine very little about the physical state and structure of the ices and grains within the comet nucleus.

Differentiation of nonneoplastic and neoplastic gallbladder polyps 1 cm or bigger with multi-detector row computed tomography.

PubMed

Park, Ko Woon; Kim, Seong Hyun; Choi, Seong Ho; Lee, Won Jae

2010-01-01

To evaluate useful computed tomographic features to differentiate nonneoplastic and neoplastic gallbladder polyps 1 cm or bigger. Thirty-one patients with 32 nonneoplastic polyps and 67 patients with 73 neoplastic polyps 1 cm or bigger underwent unenhanced and dual-phase (arterial and portal venous phases) multi-detector row computed tomography. Gallbladder polyps were diagnosed by cholecystectomy. Computed tomographic features including size (1.5 cm), surface (smooth or irregular), shape (pedunculated or sessile), accompanying wall thickening, basal indentation, perception on unenhanced images, and enhancement pattern between 2 groups were compared using univariate and multivariate analyses. On univariate analysis, age 55 years or older (P = 0.0019), size bigger than 1.5 cm (P < 0.0001), irregular surface (P = 0.0033), sessile shape (P = 0.0016), accompanying wall thickening (P = 0.0056), basal indentation (P = 0.0236), and perception on unenhanced images (P < 0.0001) were significantly more frequent in neoplastic polyps as compared with nonneoplastic polyps. On multivariate analysis, size bigger than 1.5 cm (P = 0.0260), sessile shape (P = 0.0397), and perception on unenhanced images (P < 0.0001) were statistically significant. Size bigger than 1.5 cm, sessile shape, and perception on unenhanced images are the main factors that differentiate neoplastic from nonneoplastic gallbladder polyps 1 cm or bigger.

Hierarchical image feature extraction by an irregular pyramid of polygonal partitions

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

Skurikhin, Alexei N

2008-01-01

We present an algorithmic framework for hierarchical image segmentation and feature extraction. We build a successive fine-to-coarse hierarchy of irregular polygonal partitions of the original image. This multiscale hierarchy forms the basis for object-oriented image analysis. The framework incorporates the Gestalt principles of visual perception, such as proximity and closure, and exploits spectral and textural similarities of polygonal partitions, while iteratively grouping them until dissimilarity criteria are exceeded. Seed polygons are built upon a triangular mesh composed of irregular sized triangles, whose spatial arrangement is adapted to the image content. This is achieved by building the triangular mesh on themore » top of detected spectral discontinuities (such as edges), which form a network of constraints for the Delaunay triangulation. The image is then represented as a spatial network in the form of a graph with vertices corresponding to the polygonal partitions and edges reflecting their relations. The iterative agglomeration of partitions into object-oriented segments is formulated as Minimum Spanning Tree (MST) construction. An important characteristic of the approach is that the agglomeration of polygonal partitions is constrained by the detected edges; thus the shapes of agglomerated partitions are more likely to correspond to the outlines of real-world objects. The constructed partitions and their spatial relations are characterized using spectral, textural and structural features based on proximity graphs. The framework allows searching for object-oriented features of interest across multiple levels of details of the built hierarchy and can be generalized to the multi-criteria MST to account for multiple criteria important for an application.« less

Spun-wrapped aligned nanofiber (SWAN) lithography for fabrication of micro/nano-structures on 3D objects

NASA Astrophysics Data System (ADS)

Ye, Zhou; Nain, Amrinder S.; Behkam, Bahareh

2016-06-01

Fabrication of micro/nano-structures on irregularly shaped substrates and three-dimensional (3D) objects is of significant interest in diverse technological fields. However, it remains a formidable challenge thwarted by limited adaptability of the state-of-the-art nanolithography techniques for nanofabrication on non-planar surfaces. In this work, we introduce Spun-Wrapped Aligned Nanofiber (SWAN) lithography, a versatile, scalable, and cost-effective technique for fabrication of multiscale (nano to microscale) structures on 3D objects without restriction on substrate material and geometry. SWAN lithography combines precise deposition of polymeric nanofiber masks, in aligned single or multilayer configurations, with well-controlled solvent vapor treatment and etching processes to enable high throughput (>10-7 m2 s-1) and large-area fabrication of sub-50 nm to several micron features with high pattern fidelity. Using this technique, we demonstrate whole-surface nanopatterning of bulk and thin film surfaces of cubes, cylinders, and hyperbola-shaped objects that would be difficult, if not impossible to achieve with existing methods. We demonstrate that the fabricated feature size (b) scales with the fiber mask diameter (D) as b1.5 ~ D. This scaling law is in excellent agreement with theoretical predictions using the Johnson, Kendall, and Roberts (JKR) contact theory, thus providing a rational design framework for fabrication of systems and devices that require precisely designed multiscale features.Fabrication of micro/nano-structures on irregularly shaped substrates and three-dimensional (3D) objects is of significant interest in diverse technological fields. However, it remains a formidable challenge thwarted by limited adaptability of the state-of-the-art nanolithography techniques for nanofabrication on non-planar surfaces. In this work, we introduce Spun-Wrapped Aligned Nanofiber (SWAN) lithography, a versatile, scalable, and cost-effective technique for fabrication of multiscale (nano to microscale) structures on 3D objects without restriction on substrate material and geometry. SWAN lithography combines precise deposition of polymeric nanofiber masks, in aligned single or multilayer configurations, with well-controlled solvent vapor treatment and etching processes to enable high throughput (>10-7 m2 s-1) and large-area fabrication of sub-50 nm to several micron features with high pattern fidelity. Using this technique, we demonstrate whole-surface nanopatterning of bulk and thin film surfaces of cubes, cylinders, and hyperbola-shaped objects that would be difficult, if not impossible to achieve with existing methods. We demonstrate that the fabricated feature size (b) scales with the fiber mask diameter (D) as b1.5 ~ D. This scaling law is in excellent agreement with theoretical predictions using the Johnson, Kendall, and Roberts (JKR) contact theory, thus providing a rational design framework for fabrication of systems and devices that require precisely designed multiscale features. Electronic supplementary information (ESI) available: SWAN lithography on silicon; comparison of SWAN lithography and state-of-the-art nanopatterning methods; replica molding using SWAN lithography fabricated template; PDMS nanofluidic device, gold nanopattern characterization. See DOI: 10.1039/c6nr03323g

Do Mouthwashes Really Kill Bacteria?

ERIC Educational Resources Information Center

Corner, Thomas R.

1984-01-01

Errors in determining the effectiveness of mouthwashes, disinfectants, and other household products as antibacterial agents may result from using broth cultures and/or irregularly shaped bits of filter paper. Presents procedures for a better technique and, for advanced students, two additional procedures for introducing quantitative analysis into…

Dark and Bright Material in a Crater Wall

NASA Image and Video Library

2012-03-28

This image from NASA Dawn spacecraft shows part of a large crater that has an irregularly shaped, fresh rim and is distinctive because it has many outcrops of dark and bright material originating from its rim and from the interior slope of the crater.

A sampling strategy to estimate the area and perimeter of irregularly shaped planar regions

Treesearch

Timothy G. Gregoire; Harry T. Valentine

1995-01-01

The length of a randomly oriented ray emanating from an interior point of a planar region can be used to unbiasedly estimate the region's area and perimeter. Estimators and corresponding variance estimators under various selection strategies are presented.

Portable Horizontal-Drilling And Positioning Device

NASA Technical Reports Server (NTRS)

Smigocki, Edmund; Johnson, Clarence

1988-01-01

Portable horizontal-drilling and positioning device, constructed mainly of off-the-shelf components, accurately drills horizontal small holes in irregularly shaped objects. Holes precisely placed and drilled in objects that cannot be moved to shop area. New device provides three axes of movement while maintaining horizontal drilling.

Image-guided spatial localization of heterogeneous compartments for magnetic resonance

PubMed Central

An, Li; Shen, Jun

2015-01-01

Purpose: Image-guided localization SPectral Localization Achieved by Sensitivity Heterogeneity (SPLASH) allows rapid measurement of signals from irregularly shaped anatomical compartments without using phase encoding gradients. Here, the authors propose a novel method to address the issue of heterogeneous signal distribution within the localized compartments. Methods: Each compartment was subdivided into multiple subcompartments and their spectra were solved by Tikhonov regularization to enforce smoothness within each compartment. The spectrum of a given compartment was generated by combining the spectra of the components of that compartment. The proposed method was first tested using Monte Carlo simulations and then applied to reconstructing in vivo spectra from irregularly shaped ischemic stroke and normal tissue compartments. Results: Monte Carlo simulations demonstrate that the proposed regularized SPLASH method significantly reduces localization and metabolite quantification errors. In vivo results show that the intracompartment regularization results in ∼40% reduction of error in metabolite quantification. Conclusions: The proposed method significantly reduces localization errors and metabolite quantification errors caused by intracompartment heterogeneous signal distribution. PMID:26328977

Radiofrequency-sputtered coatings for lubrication system components and other complex surfaces

NASA Technical Reports Server (NTRS)

Spalvins, T.

1972-01-01

Irregularly shaped surfaces, such as lubrication system components (ball bearings, seals, gears, etc.), can be coated on all surfaces, including irregular shapes, when radiofrequency sputtering is used. When the specimen is properly located with respect to the sputtering target, the sputtered material covers the entire surface of the object irrespective of its geometrical configuration. An adherent, dense film is formed. The film thickness varies from 20 to 50 percent on, for example, a hearing cage or race depending on its geometry. When sputtered solid film lubricants such as molybdenum disulfide are used, a film thickness only of the order of 10 to the minus 7th power m (thousands of angstroms) is required at the contacting areas. It is only essential to determine the required film thickness at the critical areas in need of lubrication. The sections outside the areas to be lubricated fall within the thickness deviation range of 20 to 50 percent, which still constitutes a negligible change respect to tolerance requirements.

Optimal design approach for heating irregular-shaped objects in three-dimensional radiant furnaces using a hybrid genetic algorithm-artificial neural network method

NASA Astrophysics Data System (ADS)

Darvishvand, Leila; Kamkari, Babak; Kowsary, Farshad

2018-03-01

In this article, a new hybrid method based on the combination of the genetic algorithm (GA) and artificial neural network (ANN) is developed to optimize the design of three-dimensional (3-D) radiant furnaces. A 3-D irregular shape design body (DB) heated inside a 3-D radiant furnace is considered as a case study. The uniform thermal conditions on the DB surfaces are obtained by minimizing an objective function. An ANN is developed to predict the objective function value which is trained through the data produced by applying the Monte Carlo method. The trained ANN is used in conjunction with the GA to find the optimal design variables. The results show that the computational time using the GA-ANN approach is significantly less than that of the conventional method. It is concluded that the integration of the ANN with GA is an efficient technique for optimization of the radiant furnaces.

Morphology of bone particles after harvesting with 4 different devices.

PubMed

Papadimitriou, Dimitrios E V; Schmidt, Erich C; Caton, Jack G; Romanos, Georgios E

2013-04-01

Autogenous bone is routinely used for regeneration of osseous defects around teeth and implants, and different instruments are available for bone harvesting. The purpose of this study was to describe the morphology of bone particles after harvesting with 4 different instruments. Bone particles were harvested from fresh cow ribs with 2 different types of back action chisels, a safescraper and a sonic device. The samples were examined morphologically using light microscopy and scanning electron microscopy. The bone particles after the back action chisel I had an appearance similar to "pencil shavings." With the back action chisel II, they were like thin paper with an "accordion bellows" appearance. After removal with the safescraper, they had an irregular shape (with an irregular surface) resembling "crushed stone." Finally, the appearance of the bone particles obtained with the sonic device was homogenous, condensed and continuous, and had a "seaweed" appearance. Harvesting of bone particles with 4 different devices produce distinctly difference sizes and shapes, which may influence the results of grafting procedures.

Resonant frequencies of irregularly shaped microstrip antennas using method of moments

NASA Technical Reports Server (NTRS)

Deshpande, Manohar D.; Shively, David G.; Cockrell, C. R.

1993-01-01

This paper describes an application of the method of moments to determine resonant frequencies of irregularly shaped microstrip patches embedded in a grounded dielectric slab. For analysis, the microstrip patch is assumed to be excited by a linearly polarized plane wave that is normal to the patch. The surface-current density that is induced on the patch because of the incident field is expressed in terms of subdomain functions by dividing the patch into identical rectangular subdomains. The amplitudes of the subdomain functions, as a function of frequency, are determined using the electric-field integral equation (EFIE) approach in conjunction with the method of moments. The resonant frequencies of the patch are then obtained by selecting the frequency at which the amplitude of the surface-current density is real. The resonant frequencies of the equilateral triangular and other nonrectangular patches are computed using the present technique, and these frequencies are compared with measurements and other independent calculations.

Nonlinear radiated MHD flow of nanoliquids due to a rotating disk with irregular heat source and heat flux condition

NASA Astrophysics Data System (ADS)

Mahanthesh, B.; Gireesha, B. J.; Shehzad, S. A.; Rauf, A.; Kumar, P. B. Sampath

2018-05-01

This research is made to visualize the nonlinear radiated flow of hydromagnetic nano-fluid induced due to rotation of the disk. The considered nano-fluid is a mixture of water and Ti6Al4V or AA7072 nano-particles. The various shapes of nanoparticles like lamina, column, sphere, tetrahedron and hexahedron are chosen in the analysis. The irregular heat source and nonlinear radiative terms are accounted in the law of energy. We used the heat flux condition instead of constant surface temperature condition. Heat flux condition is more relativistic and according to physical nature of the problem. The problem is made dimensionless with the help of suitable similarity constraints. The Runge-Kutta-Fehlberg scheme is adopted to find the numerical solutions of governing nonlinear ordinary differential systems. The solutions are plotted by considering the various values of emerging physical constraints. The effects of various shapes of nanoparticles are drawn and discussed.

Atmospheric pressure, density, temperature and wind variations between 50 and 200 km

NASA Technical Reports Server (NTRS)

Justus, C. G.; Woodrum, A.

1972-01-01

Data on atmospheric pressure, density, temperature and winds between 50 and 200 km were collected from sources including Meteorological Rocket Network data, ROBIN falling sphere data, grenade release and pitot tube data, meteor winds, chemical release winds, satellite data, and others. These data were analyzed by a daily difference method and results on the distribution statistics, magnitude, and spatial structure of the irregular atmospheric variations are presented. Time structures of the irregular variations were determined by the analysis of residuals from harmonic analysis of time series data. The observed height variations of irregular winds and densities are found to be in accord with a theoretical relation between these two quantities. The latitude variations (at 50 - 60 km height) show an increasing trend with latitude. A possible explanation of the unusually large irregular wind magnitudes of the White Sands MRN data is given in terms of mountain wave generation by the Sierra Nevada range about 1000 km west of White Sands. An analytical method is developed which, based on an analogy of the irregular motion field with axisymmetric turbulence, allows measured or model correlation or structure functions to be used to evaluate the effective frequency spectra of scalar and vector quantities of a spacecraft moving at any speed and at any trajectory elevation angle.

A new look at the Saturn system: The Voyager 2 images

USGS Publications Warehouse

Smith, B.A.; Soderblom, L.; Batson, R.; Bridges, P.; Inge, J.; Masursky, H.; Shoemaker, E.; Beebe, R.; Boyce, J.; Briggs, G.; Bunker, A.; Collins, S.A.; Hansen, C.J.; Johnson, T.V.; Mitchell, J.L.; Terrile, R.J.; Cook, A.F.; Cuzzi, J.; Pollack, James B.; Danielson, G.E.; Ingersoll, A.P.; Davies, M.E.; Hunt, G.E.; Morrison, D.; Owen, Timothy W.; Sagan, C.; Veverka, J.; Strom, R.; Suomi, V.E.

1982-01-01

Voyager 2 photography has complemented that of Voyager 1 in revealing many additional characteristics of Saturn and its satellites and rings. Saturn's atmosphere contains persistent oval cloud features reminiscent of features on Jupiter. Smaller irregular features track out a pattern of zonal winds that is symmetric about Saturn's equator and appears to extend to great depth. Winds are predominantly eastward and reach 500 meters per second at the equator. Titan has several haze layers with significantly varying optical properties and a northern polar "collar" that is dark at short wavelengths. Several satellites have been photographed at substantially improved resolution. Enceladus' surface ranges from old, densely cratered terrain to relatively young, uncratered plains crossed by grooves and faults. Tethys has a crater 400 kilometers in diameter whose floor has domed to match Tethys' surface curvature and a deep trench that extends at least 270?? around Tethys' circumference. Hyperion is cratered and irregular in shape. Iapetus' bright, trailing hemisphere includes several dark-floored craters, and Phoebe has a very low albedo and rotates in the direction opposite to that of its orbital revolution with a period of 9 hours. Within Saturn's rings, the "birth" of a spoke has been observed, and surprising azimuthal and time variability is found in the ringlet structure of the outer B ring. These observations lead to speculations about Saturn's internal structure and about the collisional and thermal history of the rings and satellites. Copyright ?? 1982 AAAS.

A simple homogeneous model for regular and irregular metallic wire media samples

NASA Astrophysics Data System (ADS)

Kosulnikov, S. Y.; Mirmoosa, M. S.; Simovski, C. R.

2018-02-01

To simplify the solution of electromagnetic problems with wire media samples, it is reasonable to treat them as the samples of a homogeneous material without spatial dispersion. The account of spatial dispersion implies additional boundary conditions and makes the solution of boundary problems difficult especially if the sample is not an infinitely extended layer. Moreover, for a novel type of wire media - arrays of randomly tilted wires - a spatially dispersive model has not been developed. Here, we introduce a simplistic heuristic model of wire media samples shaped as bricks. Our model covers WM of both regularly and irregularly stretched wires.

The effect of sputter temperature on vacancy island behavior on Ni(111) measured by photoemission of adsorbed xenon

NASA Astrophysics Data System (ADS)

Malafsky, Geoffrey P.

1994-04-01

The temperature dependence of vacancy coalescence on an ion bombarded Ni(111) surface is measured by photoemission of adsorbed xenon (PAX). The Ni(111) crystal is sputtered by a low fluence (0.06 ML incident ions) Ar + ion beam with incident kinetic energies of 500-3000 eV. The Xe coverage decreases rapidly with increasing temperature between 88 and 375 K with little additional change from 375 to 775 K. The PAX spectra are acquired with a Xe chamber pressure of 8 × 10 -10 Torr and at a temperature of 88 K. Under these conditions, the Xe is selectively adsorbed at defect sites which would make the Xe coverage proportional to the surface defect density on simple defect structures but the large size of the Xe atom relative to the Ni atom prevents the direct relationship of Xe coverage to the defect density when complex and varying defect structures are present. The decrease in Xe coverage is not attributed to the loss of defect sites by adatom-vacancy recombination but the changing vacancy island shape and size with temperature which alters the ratio of adsorbed Xe atoms to surface vacancy sites. This ratio decreases with increasing temperature as the vacancy islands progress from small and irregularly shaped islands to larger and hexagonally shaped islands. This transition is seen in Monte Carlo simulations of the kinetically driven atomic diffusion on the sputtered surface.

Seismic performance for vertical geometric irregularity frame structures

NASA Astrophysics Data System (ADS)

Ismail, R.; Mahmud, N. A.; Ishak, I. S.

2018-04-01

This research highlights the result of vertical geometric irregularity frame structures. The aid of finite element analysis software, LUSAS was used to analyse seismic performance by focusing particularly on type of irregular frame on the differences in height floors and continued in the middle of the building. Malaysia’s building structures were affected once the earthquake took place in the neighbouring country such as Indonesia (Sumatera Island). In Malaysia, concrete is widely used in building construction and limited tension resistance to prevent it. Analysing structural behavior with horizontal and vertical static load is commonly analyses by using the Plane Frame Analysis. The case study of this research is to determine the stress and displacement in the seismic response under this type of irregular frame structures. This study is based on seven-storey building of Clinical Training Centre located in Sungai Buloh, Selayang, Selangor. Since the largest earthquake occurs in Acheh, Indonesia on December 26, 2004, the data was recorded and used in conducting this research. The result of stress and displacement using IMPlus seismic analysis in LUSAS Modeller Software under the seismic response of a formwork frame system states that the building is safe to withstand the ground and in good condition under the variation of seismic performance.

Total absorption peak by use of a rigid frame porous layer backed by a rigid multi-irregularities grating.

PubMed

Groby, J-P; Lauriks, W; Vigran, T E

2010-05-01

The acoustic properties of a low resistivity porous layer backed by a rigid plate containing periodic rectangular irregularities, creating a multicomponent diffraction gratings, are investigated. Numerical and experimental results show that the structure possesses a total absorption peak at the frequency of the modified mode of the layer, when designed as proposed in the article. These results are explained by an analysis of the acoustic response of the whole structure and especially by the modal analysis of the configuration. When more than one irregularity per spatial period is considered, additional higher frequency peaks are observed.

A Marked Poisson Process Driven Latent Shape Model for 3D Segmentation of Reflectance Confocal Microscopy Image Stacks of Human Skin.

PubMed

Ghanta, Sindhu; Jordan, Michael I; Kose, Kivanc; Brooks, Dana H; Rajadhyaksha, Milind; Dy, Jennifer G

2017-01-01

Segmenting objects of interest from 3D data sets is a common problem encountered in biological data. Small field of view and intrinsic biological variability combined with optically subtle changes of intensity, resolution, and low contrast in images make the task of segmentation difficult, especially for microscopy of unstained living or freshly excised thick tissues. Incorporating shape information in addition to the appearance of the object of interest can often help improve segmentation performance. However, the shapes of objects in tissue can be highly variable and design of a flexible shape model that encompasses these variations is challenging. To address such complex segmentation problems, we propose a unified probabilistic framework that can incorporate the uncertainty associated with complex shapes, variable appearance, and unknown locations. The driving application that inspired the development of this framework is a biologically important segmentation problem: the task of automatically detecting and segmenting the dermal-epidermal junction (DEJ) in 3D reflectance confocal microscopy (RCM) images of human skin. RCM imaging allows noninvasive observation of cellular, nuclear, and morphological detail. The DEJ is an important morphological feature as it is where disorder, disease, and cancer usually start. Detecting the DEJ is challenging, because it is a 2D surface in a 3D volume which has strong but highly variable number of irregularly spaced and variably shaped "peaks and valleys." In addition, RCM imaging resolution, contrast, and intensity vary with depth. Thus, a prior model needs to incorporate the intrinsic structure while allowing variability in essentially all its parameters. We propose a model which can incorporate objects of interest with complex shapes and variable appearance in an unsupervised setting by utilizing domain knowledge to build appropriate priors of the model. Our novel strategy to model this structure combines a spatial Poisson process with shape priors and performs inference using Gibbs sampling. Experimental results show that the proposed unsupervised model is able to automatically detect the DEJ with physiologically relevant accuracy in the range 10- 20 μm .

A Marked Poisson Process Driven Latent Shape Model for 3D Segmentation of Reflectance Confocal Microscopy Image Stacks of Human Skin

PubMed Central

Ghanta, Sindhu; Jordan, Michael I.; Kose, Kivanc; Brooks, Dana H.; Rajadhyaksha, Milind; Dy, Jennifer G.

2016-01-01

Segmenting objects of interest from 3D datasets is a common problem encountered in biological data. Small field of view and intrinsic biological variability combined with optically subtle changes of intensity, resolution and low contrast in images make the task of segmentation difficult, especially for microscopy of unstained living or freshly excised thick tissues. Incorporating shape information in addition to the appearance of the object of interest can often help improve segmentation performance. However, shapes of objects in tissue can be highly variable and design of a flexible shape model that encompasses these variations is challenging. To address such complex segmentation problems, we propose a unified probabilistic framework that can incorporate the uncertainty associated with complex shapes, variable appearance and unknown locations. The driving application which inspired the development of this framework is a biologically important segmentation problem: the task of automatically detecting and segmenting the dermal-epidermal junction (DEJ) in 3D reflectance confocal microscopy (RCM) images of human skin. RCM imaging allows noninvasive observation of cellular, nuclear and morphological detail. The DEJ is an important morphological feature as it is where disorder, disease and cancer usually start. Detecting the DEJ is challenging because it is a 2D surface in a 3D volume which has strong but highly variable number of irregularly spaced and variably shaped “peaks and valleys”. In addition, RCM imaging resolution, contrast and intensity vary with depth. Thus a prior model needs to incorporate the intrinsic structure while allowing variability in essentially all its parameters. We propose a model which can incorporate objects of interest with complex shapes and variable appearance in an unsupervised setting by utilizing domain knowledge to build appropriate priors of the model. Our novel strategy to model this structure combines a spatial Poisson process with shape priors and performs inference using Gibbs sampling. Experimental results show that the proposed unsupervised model is able to automatically detect the DEJ with physiologically relevant accuracy in the range 10 – 20µm. PMID:27723590

Geoboard and Balance Activities for the Gifted Child.

ERIC Educational Resources Information Center

Bondy, Kay W.

1979-01-01

The author describes mathematics activities for gifted children which make use of the geoboard and balance. The problem, solutions, and theoretical backing are provided for determining areas of squares, areas of irregular shapes, the weight of popped and unpopped popcorn, kernels, and liquid mass and density. (SBH)

An emerging disease in blueberry caused by a novel RNA virus

USDA-ARS?s Scientific Manuscript database

A new disorder was observed on southern highbush blueberry (Vaccinium corymbosum interspecific hybrids) in several southeastern states. Symptoms included irregularly shaped circular spots or blotches with green centers on the top and bottom of leaves. The disease was reported initially in the state ...

Blueberry necrotic ring blotch, a new blueberry disease caused by a virus

USDA-ARS?s Scientific Manuscript database

Novel symptoms have been observed on southern highbush blueberries (Vaccinium corymbosum interspecific hybrids) in several southeastern states. Affected plants show irregularly shaped circular spots or blotches with green centers on the top and bottoms of leaves. Diagnostic tests failed to isolate a...

Near-equilibrium dumb-bell-shaped figures for cohesionless small bodies

NASA Astrophysics Data System (ADS)

Descamps, Pascal

2016-02-01

In a previous paper (Descamps, P. [2015]. Icarus 245, 64-79), we developed a specific method aimed to retrieve the main physical characteristics (shape, density, surface scattering properties) of highly elongated bodies from their rotational lightcurves through the use of dumb-bell-shaped equilibrium figures. The present work is a test of this method. For that purpose we introduce near-equilibrium dumb-bell-shaped figures which are base dumb-bell equilibrium shapes modulated by lognormal statistics. Such synthetic irregular models are used to generate lightcurves from which our method is successfully applied. Shape statistical parameters of such near-equilibrium dumb-bell-shaped objects are in good agreement with those calculated for example for the Asteroid (216) Kleopatra from its dog-bone radar model. It may suggest that such bilobed and elongated asteroids can be approached by equilibrium figures perturbed be the interplay with a substantial internal friction modeled by a Gaussian random sphere.

Passive Nosetip Technology (PANT) Program. Volume 14. An Experimental Study to Evaluate the Irregular Nosetip Shape Regime - Data Report

DTIC Science & Technology

1974-04-01

described in Section 2.3. 2.1 MODEL FABRICATION AND MOUNTING Camphor and camphor with distributed glass particles were the materials for the low...temperature ablator shape-change models tested in Series I. The models were fabricated by molding the camphor at room temperature and high pressure (20,000 psi...distributed glass particles were produced by thoroughly mixing glass beads, having diameters of 7.5 t 1.5 mils, with the camphor gran- ules prior to

Percolation in three-dimensional fracture networks for arbitrary size and shape distributions

NASA Astrophysics Data System (ADS)

Thovert, J.-F.; Mourzenko, V. V.; Adler, P. M.

2017-04-01

The percolation threshold of fracture networks is investigated by extensive direct numerical simulations. The fractures are randomly located and oriented in three-dimensional space. A very wide range of regular, irregular, and random fracture shapes is considered, in monodisperse or polydisperse networks containing fractures with different shapes and/or sizes. The results are rationalized in terms of a dimensionless density. A simple model involving a new shape factor is proposed, which accounts very efficiently for the influence of the fracture shape. It applies with very good accuracy in monodisperse or moderately polydisperse networks, and provides a good first estimation in other situations. A polydispersity index is shown to control the need for a correction, and the corrective term is modelled for the investigated size distributions.

Nonlinear multimodal model for TLD of irregular tank geometry and small fluid depth

NASA Astrophysics Data System (ADS)

Love, J. S.; Tait, M. J.

2013-11-01

Tuned liquid dampers (TLDs) utilize sloshing fluid to absorb and dissipate structural vibrational energy. TLDs of irregular or complex tank geometry may be required in practice to avoid tank interference with fixed structural or mechanical components. The literature offers few analytical models to predict the response of this type of TLD, particularly when the fluid depth is small. In this paper, a multimodal model is developed utilizing a Boussinesq-type modal theory which is valid for small TLD fluid depths. The Bateman-Luke variational principle is employed to develop a system of coupled nonlinear ordinary differential equations which describe the fluid response when the tank is subjected to base excitation. Energy dissipation is incorporated into the model from the inclusion of damping screens. The fluid model is used to describe the response of a 2D structure-TLD system when the structure is subjected to external loading and the TLD tank geometry is irregular.

Comparison of Seismic Responses for Reinforced Concrete Buildings with Mass and Stiffness Irregularities Using Pushover and Nonlinear Time History Analysis

NASA Astrophysics Data System (ADS)

Teruna, D. R.

2017-03-01

Pushover analysis or also known as nonlinear static procedures (NSP) have been recognized in recent years for practical evaluation of seismic demands and for structural design by estimating a structural building capacities and deformation demands. By comparing these demands and capacities at the performance level interest, the seismic performance of a building can be evaluated. However, the accuracy of NSP for assessment irregular building is not yet a fully satisfactory solution, since irregularities of a building influence the dynamic responses of the building. The objective of the study presented herein is to understand the nonlinear behaviour of six story RC building with mass irregularities at different floors and stiffness irregularity at first story (soft story) using NSP. For the purpose of comparison on the performance level obtained with NSP, nonlinear time history analysis (THA) were also performed under ground motion excitation with compatible to response spectra design. Finally, formation plastic hinges and their progressive development from elastic level to collapse prevention are presented and discussed.

Striation patterns in serrated blade stabs to cartilage.

PubMed

Pounder, Derrick J; Reeder, Francesca D

2011-05-20

Stab wounds were made in porcine cartilage with 13 serrated knives, amongst which 4 were drop-point and 9 straight-spine; 9 coarsely serrated, 3 finely serrated and 1 with mixed pattern serrations. The walls of the stab tracks were cast with dental impression material, and the casts photographed together with the knife blades for comparison. All 13 serrated blades produced an "irregularly regular" pattern of striations on cartilage in all stabbings. Unusual and distinctive blade serration patterns produced equally distinctive wound striation patterns. A reference collection of striation patterns and corresponding blades might prove useful for striation pattern analysis. Drop-point blades produced similar striations to straight-spine blades except that the striations were not parallel but rather fan-shaped, converging towards the wound exit. The fan-shaped striation pattern characteristic of drop-point blades is explained by the initial lateral movement of the blade through the cartilage imposed by the presence of the drop point shape. It appears that the greater the overall angle of the drop point, the shorter the blade length over which the drop point occurs, and the closer the first serration is to the knife tip, the more obvious is the fan-shaped pattern. We anticipate that micro-irregularities producing individualising characteristics in non-serrated drop point blades, provided they were located at the tip opposite the drop point, should also show a fan-shaped pattern indicative of a drop point blade. The examination of the walls of stab wounds to cartilage represents an under-utilised source of forensic information to assist in knife identification. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

More irregular eye shape in low myopia than in emmetropia.

PubMed

Tabernero, Juan; Schaeffel, Frank

2009-09-01

To improve the description of the peripheral eye shape in myopia and emmetropia by using a new method for continuous measurement of the peripheral refractive state. A scanning photorefractor was designed to record refractive errors in the vertical pupil meridian across the horizontal visual field (up to +/-45 degrees ). The setup consists of a hot mirror that continuously projects the infrared light from a photoretinoscope under different angles of eccentricity into the eye. The movement of the mirror is controlled by using two stepping motors. Refraction in a group of 17 emmetropic subjects and 11 myopic subjects (mean, -4.3 D; SD, 1.7) was measured without spectacle correction. For the analysis of eye shape, the refractive error versus the eccentricity angles was fitted with different polynomials (from second to tenth order). The new setup presents some important advantages over previous techniques: The subject does not have to change gaze during the measurements, and a continuous profile is obtained rather than discrete points. There was a significant difference in the fitting errors between the subjects with myopia and those with emmetropia. Tenth-order polynomials were required in myopic subjects to achieve a quality of fit similar to that in emmetropic subjects fitted with only sixth-order polynomials. Apparently, the peripheral shape of the myopic eye is more "bumpy." A new setup is presented for obtaining continuous peripheral refraction profiles. It was found that the peripheral retinal shape is more irregular even in only moderately myopic eyes, perhaps because the sclera lost some rigidity even at the early stage of myopia.

Nonlinear wave fronts and ionospheric irregularities observed by HF sounding over a powerful acoustic source

NASA Astrophysics Data System (ADS)

Blanc, Elisabeth; Rickel, Dwight

1989-06-01

Different wave fronts affected by significant nonlinearities have been observed in the ionosphere by a pulsed HF sounding experiment at a distance of 38 km from the source point of a 4800-kg ammonium nitrate and fuel oil (ANFO) explosion on the ground. These wave fronts are revealed by partial reflections of the radio sounding waves. A small-scale irregular structure has been generated by a first wave front at the level of a sporadic E layer which characterized the ionosphere at the time of the experiment. The time scale of these fluctuations is about 1 to 2 s; its lifetime is about 2 min. Similar irregularities were also observed at the level of a second wave front in the F region. This structure appears also as diffusion on a continuous wave sounding at horizontal distances of the order of 200 km from the source. In contrast, a third front unaffected by irregularities may originate from the lowest layers of the ionosphere or from a supersonic wave front propagating at the base of the thermosphere. The origin of these structures is discussed.

Small-scale plasma irregularities in the nightside Venus ionosphere

NASA Astrophysics Data System (ADS)

Grebowsky, J. M.; Curtis, S. A.; Brace, L. H.

1991-12-01

The individual volt-ampere curves from the Pioneer Venus Orbiter electron temperature probe showed evidence for small-scale density irregularities, or short-period plasma waves, in regions of the nightside ionosphere where the Orbiter electric field detector observed waves in its 100-Hz channel. A survey of the nightside volt-ampere curves has revealed several hundred examples of such irregularities. The I-V structures correspond to plasma density structure with spatial scale sizes in the range of about 100-2000 m, or alternatively they could be viewed as waves having frequencies extending toward 100 Hz. They are often seen as isolated events, with spatial extent along the orbit frequently less than 80 km. The density irregularities or waves occur in or near prominent gradients in the ambient plasma concentrations both at low altitudes where molecular ions are dominant and at higher altitudes in regions of reduced plasma density where O(+) is the major ion. Electric field 100-Hz bursts occur simultaneously, with the majority of the structured I-V curves providing demonstrative evidence that at least some of the E field signals are produced within the ionosphere.

Dynamic stress compensation by smart actuation

NASA Astrophysics Data System (ADS)

Irschik, Hans; Gusenbauer, Markus; Pichler, Uwe

2004-07-01

The actuating physical mechanisms utilized in smart materials can be described by eigenstrains. E.g., the converse piezoelectric effect in a piezoelastic body may be understood as an actuating eigenstrain. In the last decades, piezoelectricity has been extensively applied for the sake of actuation and sensing of structural vibrations. An important field of research in this respect has been devoted to the goal of compensating force-induced vibrations by means of eigenstrains. Considering the state-of-the-art in structural control and smart materials, almost no research has been performed on the problem of compensating stresses in force-loaded engineering structures by eigenstrains. It is well-known that stresses can influence the characteristics and the age of structures in various unpleasant ways. The present contribution is concerned with corresponding concepts for stress compensation which may have a highly beneficial influence upon the lifetime and structural integrity of the structure under consideration. We discuss the possibilities offered by displacement compensation to reduce the stresses to their quasi-static parts. As a numerical example, we consider the step response of an irregularly shaped cantilevered elastic plate under the action of an assigned traction at its boundary.

[The relations of corneal, lenticular and total astigmatism].

PubMed

Liang, D; Guan, Z; Lin, J

1995-06-01

To determine the relations of corneal, lenticular and total astigmatism and the changes of the astigmatism with age. Out-patients with refractive errors were refracted with retinoscope after using cycloplegic drops and measured the radii of anterior corneal curvature. One hundred and ninety-four cases (382 eyes) with refractive errors were studied. Of the eyes 67.9% had regular corneal astigmatism, 68.1% irregular lenticular astigmatism and 60.7% regular total astigmatism, 88.5% of the corneal astigmatism has the same quality as the total astigmatism. The total astigmatism in 46% of the eyes included the summation of corneal and lenticular astigmatism, but in 41.3% of the eyes irregular lenticular astigmatism corrected the regular corneal astigmatism. The astigmatism of cornea, lens and total astigmatism changed from regular to irregular with the increase of age. The linear correlation analysis showed a positive correlation between the power of horizontal corneal refraction and age, and a negative corrlation between the power of vertical corneal refraction and age. The shape of cornea was the major cause of total astigmatism. The influence of lens on the total astigmatism was different. The reasons for the change of the total astigmatism from regular to irregular with the increase of age were the changes of the power of corneal refraction, particularly the increase of the power of horizontal corneal refraction and lenticular irregular astigmatism.

In situ 3D topographic and shape analysis by synchrotron radiation X-ray microtomography for crystal form identification in polymorphic mixtures

PubMed Central

Yin, Xian-Zhen; Xiao, Ti-Qiao; Nangia, Ashwini; Yang, Shuo; Lu, Xiao-Long; Li, Hai-Yan; Shao, Qun; He, You; York, Peter; Zhang, Ji-Wen

2016-01-01

Polymorphism denotes the existence of more than one crystal structure of a substance, and great practical and theoretical interest for the chemical and pharmaceutical industries. In many cases, it is challenging to produce a pure crystal form and establish a sensitive detection method for the identification of crystal form in a mixture of polymorphs. In this study, an accurate and sensitive method based on synchrotron radiation X-ray computed microtomography (SR-μCT) was devised to identify the polymorphs of clopidogrel bisulphate (CLP). After 3D reconstruction, crystal particles were extracted and dozens of structural parameters were calculated. Whilst, the particle shapes of the two crystal forms were all irregular, the surface of CLP II was found to be rougher than CLP I. In order to classify the crystal form based on the quantitative morphological property of particles, Volume Bias Percentage based on Surface Smoothing (VBP) was defined and a new method based on VBP was successfully developed, with a total matching rate of 99.91% for 4544 particles and a lowest detectable limit of 1%. More important for the mixtures in solid pharmaceutical formulations, the interference of excipients can be avoided, a feature cannot achieved by other available analytical methods. PMID:27097672

Dermoscopic and reflectance confocal microscopic features of exogenous ochronosis.

PubMed

Gil, Inmaculada; Segura, Sonia; Martínez-Escala, Estela; Lloreta, Josep; Puig, Susana; Vélez, Mariano; Pujol, Ramón M; Herrero-González, Josep E

2010-09-01

Exogenous ochronosis presents as an acquired asymptomatic hyperpigmentation on photoexposed areas, predominantly over bony prominences, and is caused by the topical application of several skin-lightening agents. We describe a 63-year-old Hispanic woman who developed exogenous ochronosis lesions on her face after using topical bleaching creams containing hydroquinone, 2% to 3%, and oxybenzone, 2%, for several years. Dermoscopy revealed irregular brown-gray globular, annular, and arciform structures that corresponded to focal deposition of ochronotic pigment on the dermis. These deposits correlated with multiple banana-shaped nonrefractile structures seen using reflectance confocal microscopy. Histopathologic sections revealed the deposition of a banana-shaped, yellow to brown material in the papillary and middle dermis. Ultrastructural examination revealed an amorphous electron-dense material mostly located in the core of elastic fibers and also in smaller amounts in the interstitium with prominent degenerative changes in the elastic fibers. A good correlation was observed between the results of both noninvasive techniques and the diagnostic histologic features of this condition. We characterized by means of dermoscopy, reflectance confocal microscopy, and electronic microscopy a case of exogenous ochronosis. To our knowledge, this is the first description of reflectance confocal microscopic findings in this condition. Dermoscopy and reflectance confocal microscopy are proved to be useful noninvasive techniques for the diagnosis of this pigmentary disorder.

A research about characteristics of longitudinal variations of ES layers irregularities based on CHAMP occultation measurements

NASA Astrophysics Data System (ADS)

Liao, Sunmin

2018-04-01

Based on the data of CHAMP occultation measurements, this paper makes a preliminary analysis of the longitudinal variations of ES irregular structure by using Fourier decomposition and reconstruction technique. It is found that the longitudinal variations of the ES irregular structure show the features of multiple wave-numbers, which is dominated by the wave number 1 to the wave number 5 components, and decrease from the amplitudes of the wave number 6 components. The features of wave number structures are very different in different DIP latitude and different seasons. The number of crests in summer and autumn is mostly 3 or 4 crest structures, while the number of crests in spring achieves 5 at DIP 15°N with small fluctuates, the crests number of winter is the least. In the multiple wave-numbers structure, the wave number 4 component shows a significant dependence on the season, mainly in the summer and autumn, particularly obvious from July to October.

Cloaking of arbitrarily shaped objects with homogeneous coatings

NASA Astrophysics Data System (ADS)

Forestiere, Carlo; Dal Negro, Luca; Miano, Giovanni

2014-05-01

We present a theory for the cloaking of arbitrarily shaped objects and demonstrate electromagnetic scattering cancellation through designed homogeneous coatings. First, in the small-particle limit, we expand the dipole moment of a coated object in terms of its resonant modes. By zeroing the numerator of the resulting rational function, we accurately predict the permittivity values of the coating layer that abates the total scattered power. Then, we extend the applicability of the method beyond the small-particle limit, deriving the radiation corrections of the scattering-cancellation permittivity within a perturbation approach. Our method permits the design of invisibility cloaks for irregularly shaped devices such as complex sensors and detectors.

Effect of Particle Morphology on the Reactivity of Explosively Dispersed Titanium Particles

NASA Astrophysics Data System (ADS)

Frost, David; Cairns, Malcolm; Goroshin, Samuel; Zhang, Fan

2009-06-01

The effect of particle morphology on the reaction of titanium (Ti) particles explosively dispersed during the detonation of either cylindrical or spherical charges has been investigated experimentally. The explosive charges consisted of packed beds of Ti particles saturated with nitromethane. The reaction behavior of irregularly-shaped Ti particles in three size ranges is compared with tests with spherical Ti particles. The particle reaction is strongly dependent on particle morphology, e.g., 95 μm spherical Ti particles failed to ignite (in cylinders up to 49 mm in dia), whereas similarly sized irregular Ti particles readily ignited. For irregular particles, the uniformity of ignition on the particle cloud surface was almost independent of particle size, but depended on charge diameter. As the charge diameter was reduced, ignition in the conically expanding particle cloud occurred only at isolated spots or bands. For spherical charges, although large irregular Ti particles ignited promptly and uniformly throughout the particle cloud, the smallest particles dispersed nonuniformly and ignition occurred at isolated locations. In general, particle ignition is a competition between particle heating (which is influenced by particle morphology, size, number density and the local thermodynamic history) and expansion cooling of the products.

Mathematics without... Irregular Polygons

ERIC Educational Resources Information Center

McLeay, Heather

2007-01-01

In this article, the author reflects on her session at the 2006 conference, including the learning styles and strategies she observed. In her session, they explored some of the more unusual aspects of convex polyhedra (with regular faces), including the notions of "valence" and "species". Although the session was about shape and space, there was…

Hybrid Warfare: How to Shape Special Operations Forces

DTIC Science & Technology

2016-06-10

irregular tactics, information operations, and deliberate terrorism as they waged war against Russia in the territory of Chechnya and o deep in Russian...Russia initially had to withdraw its forces from Chechnya , but later led by a former KGB operative, Vladimir Putin, were able to defeat the Chechen rebels

33 CFR 330.2 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... part 325). (See 33 CFR 322.2(f) and 323.2(h) for the definition of a general permit.) (c) Authorization... several different headwaters or isolated waters, the cumulative total of all filled areas should be the... individual arms of a large, irregularly-shaped wetland or lake, etc., are not separate waterbodies. (j...

33 CFR 330.2 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... part 325). (See 33 CFR 322.2(f) and 323.2(h) for the definition of a general permit.) (c) Authorization... several different headwaters or isolated waters, the cumulative total of all filled areas should be the... individual arms of a large, irregularly-shaped wetland or lake, etc., are not separate waterbodies. (j...

76 FR 11464 - Sunshine Act Meeting; Open Commission Meeting; Thursday, March 3, 2011

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-02

... functional equivalent of Tribal Lands and to Tribal Lands that are small or irregularly shaped; and to adjust... Nations on their lands. 2 Wireless Title: Improving Communications Services Telecommunications. for Native Nations by Promoting Greater Utilization of Spectrum Over Tribal Lands. Summary: The Commission will...

Cellular organization of pre-mRNA splicing factors in several tissues. Changes in the uterus by hormone action.

PubMed

George-Téllez, R; Segura-Valdez, M L; González-Santos, L; Jiménez-García, L F

2002-05-01

In the mammalian cell nucleus, splicing factors are distributed in nuclear domains known as speckles or splicing factor compartments (SFCs). In cultured cells, these domains are dynamic and reflect transcriptional and splicing activities. We used immunofluorescence and confocal microscopy to monitor whether splicing factors in differentiated cells display similar features. Speckled patterns are observed in rat hepatocytes, beta-cells, bronchial and intestine epithelia and also in three cell types of the uterus. Moreover, the number, distribution and sizes of the speckles vary among them. In addition, we studied variations in the circular form (shape) of speckles in uterine cells that are transcriptionally modified by a hormone action. During proestrus of the estral cycle, speckles are irregular in shape while in diestrus I they are circular. Experimentally, in castrated rats luminal epithelial cells show a pattern where speckles are dramatically rounded, but they recover their irregular shape rapidly after an injection of estradiol. The same results were observed in muscle and gland epithelial cells of the uterus. We concluded that different speckled patterns are present in various cells types in differentiated tissues and that these patterns change in the uterus depending upon the presence or absence of hormones such as estradiol.

A Caulobacter MreB mutant with irregular cell shape exhibits compensatory widening to maintain a preferred surface area to volume ratio

PubMed Central

Harris, Leigh K.; Dye, Natalie A.; Theriot, Julie A.

2014-01-01

Summary Rod-shaped bacteria typically elongate at a uniform width. To investigate the genetic and physiological determinants involved in this process, we studied a mutation in the morphogenetic protein MreB in Caulobacter crescentus that gives rise to cells with a variable-width phenotype, where cells have regions that are both thinner and wider than wild-type. During growth, individual cells develop a balance of wide and thin regions, and mutant MreB dynamically localizes to poles and thin regions. Surprisingly, the surface area to volume ratio of these irregularly-shaped cells is, on average, very similar to wild-type. We propose that, while mutant MreB localizes to thin regions and promotes rod-like growth there, wide regions develop as a compensatory mechanism, allowing cells to maintain a wild-type-like surface area to volume ratio. To support this model, we have shown that cell widening is abrogated in growth conditions that promote higher surface area to volume ratios, and we have observed individual cells with high ratios return to wild-type levels over several hours by developing wide regions, suggesting that compensation can take place at the level of individual cells. PMID:25266768

A flexible spatial scan statistic with a restricted likelihood ratio for detecting disease clusters.

PubMed

Tango, Toshiro; Takahashi, Kunihiko

2012-12-30

Spatial scan statistics are widely used tools for detection of disease clusters. Especially, the circular spatial scan statistic proposed by Kulldorff (1997) has been utilized in a wide variety of epidemiological studies and disease surveillance. However, as it cannot detect noncircular, irregularly shaped clusters, many authors have proposed different spatial scan statistics, including the elliptic version of Kulldorff's scan statistic. The flexible spatial scan statistic proposed by Tango and Takahashi (2005) has also been used for detecting irregularly shaped clusters. However, this method sets a feasible limitation of a maximum of 30 nearest neighbors for searching candidate clusters because of heavy computational load. In this paper, we show a flexible spatial scan statistic implemented with a restricted likelihood ratio proposed by Tango (2008) to (1) eliminate the limitation of 30 nearest neighbors and (2) to have surprisingly much less computational time than the original flexible spatial scan statistic. As a side effect, it is shown to be able to detect clusters with any shape reasonably well as the relative risk of the cluster becomes large via Monte Carlo simulation. We illustrate the proposed spatial scan statistic with data on mortality from cerebrovascular disease in the Tokyo Metropolitan area, Japan. Copyright © 2012 John Wiley & Sons, Ltd.

Recent developments in multidimensional transport methods for the APOLLO 2 lattice code

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

Zmijarevic, I.; Sanchez, R.

1995-12-31

A usual method of preparation of homogenized cross sections for reactor coarse-mesh calculations is based on two-dimensional multigroup transport treatment of an assembly together with an appropriate leakage model and reaction-rate-preserving homogenization technique. The actual generation of assembly spectrum codes based on collision probability methods is capable of treating complex geometries (i.e., irregular meshes of arbitrary shape), thus avoiding the modeling error that was introduced in codes with traditional tracking routines. The power and architecture of current computers allow the treatment of spatial domains comprising several mutually interacting assemblies using fine multigroup structure and retaining all geometric details of interest.more » Increasing safety requirements demand detailed two- and three-dimensional calculations for very heterogeneous problems such as control rod positioning, broken Pyrex rods, irregular compacting of mixed- oxide (MOX) pellets at an MOX-UO{sub 2} interface, and many others. An effort has been made to include accurate multi- dimensional transport methods in the APOLLO 2 lattice code. These include extension to three-dimensional axially symmetric geometries of the general-geometry collision probability module TDT and the development of new two- and three-dimensional characteristics methods for regular Cartesian meshes. In this paper we discuss the main features of recently developed multidimensional methods that are currently being tested.« less

Evaporation From Soil Containers With Irregular Shapes

NASA Astrophysics Data System (ADS)

Assouline, Shmuel; Narkis, Kfir

2017-11-01

Evaporation from bare soils under laboratory conditions is generally studied using containers of regular shapes where the vertical edges are parallel to the flow lines in the drying domain. The main objective of this study was to investigate the impact of irregular container shapes, for which the flow lines either converge or diverge toward the surface. Evaporation from initially saturated sand and sandy loam soils packed in cones and inverted cones was compared to evaporation from corresponding cylindrical columns. The initial evaporation rate was higher in the cones, and close to potential evaporation. At the end of the experiment, the cumulative evaporation depth in the sand cone was equal to that in the column but higher than in the inverted cone, while in the sandy loam, the order was cone > column > inverted cone. By comparison to the column, stage 1 evaporation was longer in the cones, and practically similar in the inverted cones. Stage 2 evaporation rate decreased with the increase of the evaporating surface area. These results were more pronounced in the sandy loam. For the sand column, the transition between stage 1 and stage 2 evaporation occurred when the depth of the saturation front was approximately equal to the characteristic length of the soil. However, for the cone and the inverted cone, it occurred for a shallower depth of the saturation front. It seems therefore that the concept of the characteristic length derived from the soil hydraulic properties is related to drying systems of regular shapes.

Studies of small scale irregularities in the cusp ionosphere using sounding rockets: recent results

NASA Astrophysics Data System (ADS)

Spicher, A.; Ilyasov, A. A.; Miloch, W. J.; Chernyshov, A. A.; Moen, J.; Clausen, L. B. N.; Saito, Y.

2017-12-01

Plasma irregularities occurring over many scale sizes are common in the ionosphere. Understanding and characterizing the phenomena responsible for these irregularities is not only important from a theoretical point of view, but also in the context of space weather, as the irregularities can disturb HF communication and Global Navigation Satellite Systems signals. Overall, research about the small-scale turbulence has not progressed as fast for polar regions as for the equatorial ones, and for the high latitude ionosphere there is still no agreement nor detailed explanation regarding the formation of irregularities. To investigate plasma structuring at small scales in the cusp ionosphere, we use high resolution measurements from the Investigation of Cusp Irregularities (ICI) sounding rockets, and investigate a region associated with density enhancements and a region characterized by flow shears. Using the ICI-2 electron density data, we give further evidence of the importance of the gradient drift instability for plasma structuring inside the polar cap. In particular, using higher-order statistics, we provide new insights into the nature of the resulting plasma structures and show that they are characterized by intermittency. Using the ICI-3 data, we show that the entire region associated with a reversed flow event (RFE), with the presence of meter-scale irregularities, several flow shears and particle precipitation, is highly structured. By performing a numerical stability analysis, we show that the inhomogeneous-energy-density-driven instability (IEDDI) may be active in relation to RFEs at the rocket's altitude. In particular, we show that the presence of particle precipitation decreases the growth rates of IEDDI and, using a Local Intermittency Measure, we observe a correlation between IEDDI growth rates and electric field fluctuations over several scales. These findings support the view that large-scale inhomogeneities may provide a background for the development of micro-scale instabilities. Such interplay between macro- and micro-processes might be an important mechanism for the development of small-scale plasma gradients, and as a source for ion heating in the cusp ionosphere.

Listening to galaxies tuning at z ~ 2.5-3.0: The first strikes of the Hubble fork

NASA Astrophysics Data System (ADS)

Talia, M.; Cimatti, A.; Mignoli, M.; Pozzetti, L.; Renzini, A.; Kurk, J.; Halliday, C.

2014-02-01

Aims: We investigate the morphological properties of 494 galaxies selected from the Galaxy Mass Assembly ultra-deep Spectroscopic Survey (GMASS) at z > 1, primarily in their optical rest frame, using Hubble Space Telescope (HST) infrared images, from the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey (CANDELS). Methods: The morphological analysis of Wield Field Camera (WFC3) H160 band images was performed using two different methods: a visual classification identifying traditional Hubble types, and a quantitative analysis using parameters that describe structural properties, such as the concentration of light and the rotational asymmetry. The two classifications are compared. We then analysed how apparent morphologies correlate with the physical properties of galaxies. Results: The fractions of both elliptical and disk galaxies decrease between redshifts z ~ 1 to z ~ 3, while at z > 3 the galaxy population is dominated by irregular galaxies. The quantitative morphological analysis shows that, at 1 < z < 3, morphological parameters are not as effective in distinguishing the different morphological Hubble types as they are at low redshift. No significant morphological k-correction was found to be required for the Hubble type classification, with some exceptions. In general, different morphological types occupy the two peaks of the (U - B)rest colour bimodality of galaxies: most irregulars occupy the blue peak, while ellipticals are mainly found in the red peak, though with some level of contamination. Disks are more evenly distributed than either irregulars and ellipticals. We find that the position of a galaxy in a UVJ diagram is related to its morphological type: the "quiescent" region of the plot is mainly occupied by ellipticals and, to a lesser extent, by disks. We find that only ~33% of all morphological ellipticals in our sample are red and passively evolving galaxies, a percentage that is consistent with previous results obtained at z < 1. Blue galaxies morphologically classified as ellipticals show a remarkable structural similarity to red ones. We search for correlations between our morphological and spectroscopic galaxy classifications. Almost all irregulars have a star-forming galaxy spectrum. In addition, the majority of disks show some sign of star-formation activity in their spectra, though in some cases their red continuum is indicative of old stellar populations. Finally, an elliptical morphology may be associated with either passively evolving or strongly star-forming galaxies. Conclusions: We propose that the Hubble sequence of galaxy morphologies takes shape at redshift 2.5 < z < 3. The fractions of both ellipticals and disks decrease with increasing lookback time at z > 1, such that at redshifts z = 2.5-2.7 and above, the Hubble types cannot be identified, and most galaxies are classified as irregular. Appendix A is available in electronic form at http://www.aanda.org

Coiled-Coil Irregularities and Instabilities in Group A Streptococcus M1 Are Required for Virulence

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

McNamara, Case; Zinkernagel, Annelies S.; Macheboeuf, Pauline

2008-07-21

Antigenically variable M proteins are major virulence factors and immunogens of the human pathogen group A Streptococcus (GAS). Here, we report the -3 angstrom resolution structure of a GAS M1 fragment containing the regions responsible for eliciting type-specific, protective immunity and for binding fibrinogen, which promotes M1 proinflammatory and antiphagocytic functions. The structure revealed substantial irregularities and instabilities throughout the coiled coil of the M1 fragment. Similar structural irregularities occur in myosin and tropomyosin, explaining the patterns of cross-reactivity seen in autoimmune sequelae of GAS infection. Sequence idealization of a large segment of the M1 coiled coil enhanced stability butmore » diminished fibrinogen binding, proinflammatory effects, and antibody cross-reactivity, whereas it left protective immunogenicity undiminished. Idealized M proteins appear to have promise as vaccine immunogens.« less

Discovery of B ring propellers in Cassini UVIS and ISS

NASA Astrophysics Data System (ADS)

Sremcevic, M.; Stewart, G.; Albers, N.; Esposito, L. W.

2011-12-01

One of the successes of the planetary ring theory has been the theoretical prediction of gravitational signatures of bodies embedded in the rings, and their subsequent detection in Cassini data. Bodies within the rings perturb the nearby ring material, and the orbital shear forms a two-armed structure -- dubbed a ``propeller'' -- which is centered at the embedded body. Although direct evidence of the present body or moonlet is still lacking, the observations of their propeller signatures has proved as an indispensable method to extend our knowledge about ring structure and dynamics. So far, propellers have been successfully detected within Saturn's A ring in two populations: a group of small and numerous propellers interior to the Encke gap forming belts, and by far less numerous but larger propellers exterior to Pan's orbit. Although there have been hints of propellers present within the B ring, or even C ring, their detection is less certain (e.g. neither has a single propeller been seen twice, nor has the ubiquitous two armed structure been observed). In this paper we present evidence for the existence of propellers in Saturn's B ring by combining data from Cassini Ultraviolet Imaging Spectrograph (UVIS) and Imaging Science Subsystem (ISS) experiments. A single object is observed for 5 years of Cassini data. The object is seen as a very elongated bright stripe (40 degrees wide) in unlit Cassini images, and dark stripe in lit geometries. In total we report observing the feature in images at 18 different epochs between 2005 and 2010. In UVIS occultations we observe the feature as an optical depth depletion in 14 out of 93 occultation cuts at corrotating longitudes compatible with imaging data. Combining the available Cassini data we infer that the object is a partial gap located at a=112,921km embedded in the high optical depth region of the B ring. The gap moves at Kepler speed appropriate for its radial location. Radial offsets of the gap locations in UVIS occultations are consistent with an asymmetric propeller shape. The asymmetry of the observed shape is most likely a consequence of the strong surface mass density gradient, as the feature is located at an edge between high and relatively low optical depth. From the radial separation of the propeller wings we estimate that the embedded body is about 1.5km in size. We estimate that there are possibly dozen up to 100 other propeller objects in Saturn's B ring. Since the discovered body sits at an edge of a dense ringlet within the B ring this suggests a novel mechanism for the up to now illusive B ring irregular shape of alternating high and low optical depth ringlets. We propose that the long standing search for the mechanism that maintains the B ring irregular shape may have its explanation in the presence of many embedded bodies that shepherd the individual B ring ringlets.

Plasmonic nanoparticles enhanced dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Xu, Qi; Liu, Fang; Meng, Weisi; Huang, Yidong

2013-12-01

Here we present investigations on utilizing two kinds of plasmonic nanoparticles (NPs) to enhance the efficiency of dye sensitized solar cells (DSCs). The Au@PVP NPs is proposed and present the specialty of adhesiveness to dye molecules, which could help to localize additional dye molecules near the plasmonic NPs, hence increasing the optical absorption consequently the power conversion efficiency (PCE) of the DSCs by 30% from 3.3% to 4.3%. Meanwhile, an irregular Au-Ag alloy popcorn-shaped NPs (popcorn NPs) with plenty of fine structures is also proposed and realized to enhance the light absorption of DSC. A pronounced absorption enhancement in a broadband wavelength range is observed due to the excitation of localized surface plasmon at different wavelengths. The PCE is enhanced by 32% from 5.94% to 7.85%.

Stochastic modelling of intermittent fluctuations in the scrape-off layer: Correlations, distributions, level crossings, and moment estimation

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

Garcia, O. E., E-mail: odd.erik.garcia@uit.no; Kube, R.; Theodorsen, A.

A stochastic model is presented for intermittent fluctuations in the scrape-off layer of magnetically confined plasmas. The fluctuations in the plasma density are modeled by a super-position of uncorrelated pulses with fixed shape and duration, describing radial motion of blob-like structures. In the case of an exponential pulse shape and exponentially distributed pulse amplitudes, predictions are given for the lowest order moments, probability density function, auto-correlation function, level crossings, and average times for periods spent above and below a given threshold level. Also, the mean squared errors on estimators of sample mean and variance for realizations of the process bymore » finite time series are obtained. These results are discussed in the context of single-point measurements of fluctuations in the scrape-off layer, broad density profiles, and implications for plasma–wall interactions due to the transient transport events in fusion grade plasmas. The results may also have wide applications for modelling fluctuations in other magnetized plasmas such as basic laboratory experiments and ionospheric irregularities.« less

Cobalt-Assisted Morphology and Assembly Control of Co-Doped ZnO Nanoparticles

PubMed Central

Han, Xianying; Wahl, Sebastian; Russo, Patrícia A.

2018-01-01

The morphology of metal oxide nanostructures influences the response of the materials in a given application. In addition to changing the composition, doping can also modify the morphology of a host nanomaterial. Herein, we determine the effect of dopant concentration, reaction temperature, and reaction time on the morphology and assembly of CoxZn1−xO nanoparticles synthesized through non-aqueous sol-gel in benzyl alcohol. With the increase of the atom % of cobalt incorporated from 0 to 15, the shape of the nanoparticles changes from near spherical, to irregular, and finally to triangular. The tendency of the particles to assemble increases in the same direction, with Co0.05Zn0.95O consisting of non-assembled particles, whereas Co0.15Zn0.85O consists of triangular nanoparticles forming spherical structures. The morphology and assembly process are also sensitive to the reaction temperature. The assembly process is found to occur during the nucleation or the early stages of particle growth. The cobalt ions promote the change in the shape during the growth stage of the nanoparticles. PMID:29673179

Comparing the role of shape and texture on staging hepatic fibrosis from medical imaging

NASA Astrophysics Data System (ADS)

Zhang, Xuejun; Louie, Ryan; Liu, Brent J.; Gao, Xin; Tan, Xiaomin; Qu, Xianghe; Long, Liling

2016-03-01

The purpose of this study is to investigate the role of shape and texture in the classification of hepatic fibrosis by selecting the optimal parameters for a better Computer-aided diagnosis (CAD) system. 10 surface shape features are extracted from a standardized profile of liver; while15 texture features calculated from gray level co-occurrence matrix (GLCM) are extracted within an ROI in liver. Each combination of these input subsets is checked by using support vector machine (SVM) with leave-one-case-out method to differentiate fibrosis into two groups: normal or abnormal. The accurate rate value of all 10/15 types number of features is 66.83% by texture, while 85.74% by shape features, respectively. The irregularity of liver shape can demonstrate fibrotic grade efficiently and texture feature of CT image is not recommended to use with shape feature for interpretation of cirrhosis.

Congenital tri-cavernous hemangiomas of the right buccal region, right accessory parotid gland, and masseter muscle region.

PubMed

Yang, Tao; Gu, Yongchun; Zhang, Li; Hua, Zequan

2014-03-01

We report a rare case of congenital tri-cavernous hemangiomas of the right buccal region, right accessory parotid gland, and masseter muscle region in an adult. The patient, a 25-year-old woman, complained of 3 masses in her right midcheek. Ultrasonographic and computed tomographic findings showed an irregular-shaped mass (multiple calcifications) with a well-defined margin in the masseter muscle region, an ellipse-shaped mass (multiple calcifications) with a well-defined margin in the right buccal region, and a comma-shaped mass (no calcifications) with a well-defined margin separate from the parotid gland in the right accessory parotid gland region. These iconographic findings suggested that the masses were all hemangiomas separately originating from the parotid gland, accessory parotid gland, and masseter muscle. The masses were completely removed through a standard parotid incision without postoperative facial palsy, skin deformity, and difficulty in secreting saliva. Findings from histologic examination of the tumor revealed multiple, thin-walled, and dilated blood vessels, confirming the diagnosis of cavernous hemangiomas. Ultrasonographic and computed tomographic findings were extremely useful in diagnosing the mass/masses as hemangioma before surgery, clarifying relationships between the mass and adjacent structures, and determining the surgical approach to the mass/masses.

The study on spatial distribution features of radiological plume discharged from Nuclear Power Plant based on C4ISRE

NASA Astrophysics Data System (ADS)

Ma, Yunfeng; Shen, Yue; Feng, Bairun; Yang, Fan; Li, Qiangqiang; Du, Boying; Bian, Yushan; Hu, Qiongqong; Wang, Qi; Hu, Xiaomin; Yin, Hang

2018-02-01

When the nuclear emergency accident occurs, it is very important to estimate three-dimensional space feature of the radioactive plume discharged from the source term for the emergency organization, as well as for better understanding of atmospheric dispersion processes. So, taking the Hongyanhe Nuclear Power Plant for example, the study for three-dimensional space feature of the radioactive plume is accomplished by applying atmospheric transport model (coupling of WRF-HYSPLIT) driven by FNL meteorological data of NCEP (04/01/2014-04/02/2014) based on the C4ISRE (Command, Control, Communications, Computer, Intelligence, Surveillance, Reconnaissance, Environmental Impact Assessment).The results show that the whole shape of three-dimensional plume was about irregular cloth influenced by wind; In the spatial domain (height > 16000m),the distribution of radiological plume, which looked more like horseshoe-shaped, presented irregular polygons of which the total length was 2258.7km, where covered the area of 39151km2; In the airspace from 4000m to 16000m, the plume, covered the area of 116269 km2, showed a triangle and the perimeter of that was 2280.4km; The shape of the plume was more like irregular quadrilateral, its perimeter was 2941.8km and coverage area of the plume was 131534km2;The overall distribution of the wind field showed a rectangular shape; Within the area along the horizontal direction 400m from origin to east and under height (lower than 2000m),the closer the distance coordinate (0,0), the denser the plume particles; Within the area of horizontal distance(500m-1000m) and height (4000m- 16000m), the particle density were relatively sparse and the spread extent of the plume particles from west to East was relatively large and the plume particles were mainly in the suspended state without obvious dry sedimentation; Within the area of horizontal distance (800m-1100m) and height (>16000m), there were relatively gentle horizontal diffusion of plume particles with upward drift of particles In local area.

Studies of Ionospheric Plasma Structuring at Low Latitudes from Space and Ground, Their Modeling and Relationship to Scintillations

DTIC Science & Technology

2009-01-01

1 DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited. Studies of Ionospheric Plasma Structuring at Low...program combines observations and modeling of the nighttime ionosphere to come to a better physical understanding of the factors that contribute to...the day-to-day variability of the development of ionospheric irregularities. The scope encompasses irregularities developing at equatorial and mid

Efficient Machine Learning Approach for Optimizing Scientific Computing Applications on Emerging HPC Architectures

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

Arumugam, Kamesh

Efficient parallel implementations of scientific applications on multi-core CPUs with accelerators such as GPUs and Xeon Phis is challenging. This requires - exploiting the data parallel architecture of the accelerator along with the vector pipelines of modern x86 CPU architectures, load balancing, and efficient memory transfer between different devices. It is relatively easy to meet these requirements for highly structured scientific applications. In contrast, a number of scientific and engineering applications are unstructured. Getting performance on accelerators for these applications is extremely challenging because many of these applications employ irregular algorithms which exhibit data-dependent control-ow and irregular memory accesses. Furthermore,more » these applications are often iterative with dependency between steps, and thus making it hard to parallelize across steps. As a result, parallelism in these applications is often limited to a single step. Numerical simulation of charged particles beam dynamics is one such application where the distribution of work and memory access pattern at each time step is irregular. Applications with these properties tend to present significant branch and memory divergence, load imbalance between different processor cores, and poor compute and memory utilization. Prior research on parallelizing such irregular applications have been focused around optimizing the irregular, data-dependent memory accesses and control-ow during a single step of the application independent of the other steps, with the assumption that these patterns are completely unpredictable. We observed that the structure of computation leading to control-ow divergence and irregular memory accesses in one step is similar to that in the next step. It is possible to predict this structure in the current step by observing the computation structure of previous steps. In this dissertation, we present novel machine learning based optimization techniques to address the parallel implementation challenges of such irregular applications on different HPC architectures. In particular, we use supervised learning to predict the computation structure and use it to address the control-ow and memory access irregularities in the parallel implementation of such applications on GPUs, Xeon Phis, and heterogeneous architectures composed of multi-core CPUs with GPUs or Xeon Phis. We use numerical simulation of charged particles beam dynamics simulation as a motivating example throughout the dissertation to present our new approach, though they should be equally applicable to a wide range of irregular applications. The machine learning approach presented here use predictive analytics and forecasting techniques to adaptively model and track the irregular memory access pattern at each time step of the simulation to anticipate the future memory access pattern. Access pattern forecasts can then be used to formulate optimization decisions during application execution which improves the performance of the application at a future time step based on the observations from earlier time steps. In heterogeneous architectures, forecasts can also be used to improve the memory performance and resource utilization of all the processing units to deliver a good aggregate performance. We used these optimization techniques and anticipation strategy to design a cache-aware, memory efficient parallel algorithm to address the irregularities in the parallel implementation of charged particles beam dynamics simulation on different HPC architectures. Experimental result using a diverse mix of HPC architectures shows that our approach in using anticipation strategy is effective in maximizing data reuse, ensuring workload balance, minimizing branch and memory divergence, and in improving resource utilization.« less

Method for hot pressing irregularly shaped refractory articles

DOEpatents

Steinkamp, William E.; Ballard, Ambrose H.

1982-01-01

The present invention is directed to a method for hot pressing irregularly haped refractory articles with these articles of varying thickness being provided with high uniform density and dimensional accuracy. Two partially pressed compacts of the refractory material are placed in a die cavity between displaceable die punches having compact-contacting surfaces of the desired article configuration. A floating, rotatable block is disposed between the compacts. The displacement of the die punches towards one another causes the block to rotate about an axis normal to the direction of movement of the die punches to uniformly distribute the pressure loading upon the compacts for maintaining substantially equal volume displacement of the powder material during the hot pressing operation.

A Simple Device for Lens-to-Sample Distance Adjustment in Laser-Induced Breakdown Spectroscopy (LIBS).

PubMed

Cortez, Juliana; Farias Filho, Benedito B; Fontes, Laiane M; Pasquini, Celio; Raimundo, Ivo M; Pimentel, Maria Fernanda; de Souza Lins Borba, Flávia

2017-04-01

A simple device based on two commercial laser pointers is described to assist in the analysis of samples that present uneven surfaces and/or irregular shapes using laser-induced breakdown spectroscopy (LIBS). The device allows for easy positioning of the sample surface at a reproducible distance from the focusing lens that conveys the laser pulse to generate the micro-plasma in a LIBS system, with reproducibility better than ±0.2 mm. In this way, fluctuations in the fluence (J cm -2 ) are minimized and the LIBS analytical signals can be obtained with a better precision even when samples with irregular surfaces are probed.

The effect of earthquake on architecture geometry with non-parallel system irregularity configuration

NASA Astrophysics Data System (ADS)

Teddy, Livian; Hardiman, Gagoek; Nuroji; Tudjono, Sri

2017-12-01

Indonesia is an area prone to earthquake that may cause casualties and damage to buildings. The fatalities or the injured are not largely caused by the earthquake, but by building collapse. The collapse of the building is resulted from the building behaviour against the earthquake, and it depends on many factors, such as architectural design, geometry configuration of structural elements in horizontal and vertical plans, earthquake zone, geographical location (distance to earthquake center), soil type, material quality, and construction quality. One of the geometry configurations that may lead to the collapse of the building is irregular configuration of non-parallel system. In accordance with FEMA-451B, irregular configuration in non-parallel system is defined to have existed if the vertical lateral force-retaining elements are neither parallel nor symmetric with main orthogonal axes of the earthquake-retaining axis system. Such configuration may lead to torque, diagonal translation and local damage to buildings. It does not mean that non-parallel irregular configuration should not be formed on architectural design; however the designer must know the consequence of earthquake behaviour against buildings with irregular configuration of non-parallel system. The present research has the objective to identify earthquake behaviour in architectural geometry with irregular configuration of non-parallel system. The present research was quantitative with simulation experimental method. It consisted of 5 models, where architectural data and model structure data were inputted and analyzed using the software SAP2000 in order to find out its performance, and ETAB2015 to determine the eccentricity occurred. The output of the software analysis was tabulated, graphed, compared and analyzed with relevant theories. For areas of strong earthquake zones, avoid designing buildings which wholly form irregular configuration of non-parallel system. If it is inevitable to design a building with building parts containing irregular configuration of non-parallel system, make it more rigid by forming a triangle module, and use the formula.A good collaboration is needed between architects and structural experts in creating earthquake architecture.

Postnatal airway growth in cystic fibrosis piglets.

PubMed

Adam, Ryan J; Abou Alaiwa, Mahmoud H; Bouzek, Drake C; Cook, Daniel P; Gansemer, Nicholas D; Taft, Peter J; Powers, Linda S; Stroik, Mallory R; Hoegger, Mark J; McMenimen, James D; Hoffman, Eric A; Zabner, Joseph; Welsh, Michael J; Meyerholz, David K; Stoltz, David A

2017-09-01

Mutations in the gene encoding the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) anion channel cause CF. The leading cause of death in the CF population is lung disease. Increasing evidence suggests that in utero airway development is CFTR-dependent and that developmental abnormalities may contribute to CF lung disease. However, relatively little is known about postnatal CF airway growth, largely because such studies are limited in humans. Therefore, we examined airway growth and lung volume in a porcine model of CF. We hypothesized that CF pigs would have abnormal postnatal airway growth. To test this hypothesis, we performed CT-based airway and lung volume measurements in 3-wk-old non-CF and CF pigs. We found that 3-wk-old CF pigs had tracheas of reduced caliber and irregular shape. Their bronchial lumens were reduced in size proximally but not distally, were irregularly shaped, and had reduced distensibility. Our data suggest that lack of CFTR results in aberrant postnatal airway growth and development, which could contribute to CF lung disease pathogenesis. NEW & NOTEWORTHY This CT scan-based study of airway morphometry in the cystic fibrosis (CF) postnatal period is unique, as analogous studies in humans are greatly limited for ethical and technical reasons. Findings such as reduced airway lumen area and irregular caliber suggest that airway growth and development are CF transmembrane conductance regulator-dependent and that airway growth defects may contribute to CF lung disease pathogenesis. Copyright © 2017 the American Physiological Society.

Modeling and performance improvement of the constant power regulator systems in variable displacement axial piston pump.

PubMed

Park, Sung Hwan; Lee, Ji Min; Kim, Jong Shik

2013-01-01

An irregular performance of a mechanical-type constant power regulator is considered. In order to find the cause of an irregular discharge flow at the cut-off pressure area, modeling and numerical simulations are performed to observe dynamic behavior of internal parts of the constant power regulator system for a swashplate-type axial piston pump. The commercial numerical simulation software AMESim is applied to model the mechanical-type regulator with hydraulic pump and simulate the performance of it. The validity of the simulation model of the constant power regulator system is verified by comparing simulation results with experiments. In order to find the cause of the irregular performance of the mechanical-type constant power regulator system, the behavior of main components such as the spool, sleeve, and counterbalance piston is investigated using computer simulation. The shape modification of the counterbalance piston is proposed to improve the undesirable performance of the mechanical-type constant power regulator. The performance improvement is verified by computer simulation using AMESim software.

Neural substrates of sublexical processing for spelling.

PubMed

DeMarco, Andrew T; Wilson, Stephen M; Rising, Kindle; Rapcsak, Steven Z; Beeson, Pélagie M

2017-01-01

We used fMRI to examine the neural substrates of sublexical phoneme-grapheme conversion during spelling in a group of healthy young adults. Participants performed a writing-to-dictation task involving irregular words (e.g., choir), plausible nonwords (e.g., kroid), and a control task of drawing familiar geometric shapes (e.g., squares). Written production of both irregular words and nonwords engaged a left-hemisphere perisylvian network associated with reading/spelling and phonological processing skills. Effects of lexicality, manifested by increased activation during nonword relative to irregular word spelling, were noted in anterior perisylvian regions (posterior inferior frontal gyrus/operculum/precentral gyrus/insula), and in left ventral occipito-temporal cortex. In addition to enhanced neural responses within domain-specific components of the language network, the increased cognitive demands associated with spelling nonwords engaged domain-general frontoparietal cortical networks involved in selective attention and executive control. These results elucidate the neural substrates of sublexical processing during written language production and complement lesion-deficit correlation studies of phonological agraphia. Copyright © 2016 Elsevier Inc. All rights reserved.

Neural Substrates of Sublexical Processing for Spelling

PubMed Central

Wilson, Stephen M.; Rising, Kindle; Rapcsak, Steven Z.; Beeson, Pélagie M.

2016-01-01

We used fMRI to examine the neural substrates of sublexical phoneme-grapheme conversion during spelling in a group of healthy young adults. Participants performed a writing-to-dictation task involving irregular words (e.g., choir), plausible nonwords (e.g., kroid), and a control task of drawing familiar geometric shapes (e.g., squares). Written production of both irregular words and nonwords engaged a left-hemisphere perisylvian network associated with reading/spelling and phonological processing skills. Effects of lexicality, manifested by increased activation during nonword relative to irregular word spelling, were noted in anterior perisylvian regions (posterior inferior frontal gyrus/operculum/precentral gyrus/insula), and in left ventral occipito-temporal cortex. In addition to enhanced neural responses within domain-specific components of the language network, the increased cognitive demands associated with spelling nonwords engaged domain-general frontoparietal cortical networks involved in selective attention and executive control. These results elucidate the neural substrates of sublexical processing during written language production and complement lesion-deficit correlation studies of phonological agraphia. PMID:27838547

Influence of Size and Shape of Silica Supports on the Sol⁻Gel Surface Molecularly Imprinted Polymers for Selective Adsorption of Gossypol.

PubMed

Zhi, Keke; Wang, Lulu; Zhang, Yagang; Jiang, Yingfang; Zhang, Letao; Yasin, Akram

2018-05-11

The influence of various silica gel supports with different shapes and sizes on the recognition properties of surface molecular imprinted polymers (MIPs) was investigated. MIPs for selective recognition and adsorption of gossypol were synthesized via the sol⁻gel process with a surface imprinting technique on silica gel substrates. 3-aminopropyltriethoxysilane (APTES) and tetraethoxysilane (TEOS) were chosen as the functional monomer and the cross-linker. The morphology and structure of the gossypol-MIPs were characterized using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and a standard Brunauer⁻Emett⁻Teller (BET) analysis. Results indicated that the surface imprinted polymer layer facilitated the removal and rebinding of the template, and thus, achieved fast binding kinetics. Compared with the MIPs prepared on irregularly shaped silica with a broad particle size distribution, the MIPs using regularly-shaped silica of uniform size showed higher imprinting factor (IF), and the MIP made with a relatively larger sized (60 μm) spherical silica, demonstrated higher adsorption capacity compared to the MIPs made with smaller sized, spherical silica. The MIP prepared with 60 μm spherically shaped silica, featured a fast adsorption kinetic of 10 min, and a saturated adsorption capacity of 204 mg·g −1 . The gossypol-MIP had higher selectivity (IF = 2.20) for gossypol over its structurally-similar analogs ellagic acid (IF = 1.13) and quercetin (IF = 1.20). The adsorption data of the MIP correlated well with the pseudo-second-order kinetic model and the Freundlich isotherm model, which implied that chemical adsorption dominated, and that multilayer adsorption occurred. Furthermore, the MIP exhibited an excellent regeneration performance, and the adsorption capacity of the MIP for gossypol only decreased by 6% after six reused cycles, indicating good application potential for selective adsorption of gossypol.

Some implications of populus intensive culture on nongame birds

Treesearch

Richard L. Verch

1983-01-01

Intensive culture of Populus will affect nongame bird habitat. Conversion of old fields to Populus plantations will destroy habitat favorable to certain species and produce habitat that will attract different species. Effects of this conversion can be lessened by planting plantations with irregular shapes and by leaving patches (.4 hectares) of...

Shallow subsurface drip irrigation (S3DI) for small irregular-shaped fields in the southeast

USDA-ARS?s Scientific Manuscript database

Field tests were conducted using S3DI on cotton (Gossypium hirsutum, L.), corn (Zea mays, L.), and peanut (Arachis hypogeae, L.) rotations to investigate yield potential and economic sustainability of this irrigation system. Drip tubing was installed in alternate row middles, strip tillage was used ...

"Rosetta" Mission's "7 Hours of Terror" and "Philae's" Descent

ERIC Educational Resources Information Center

Blanco, Philip

2015-01-01

In November 2014 the "Rosetta" mission to Comet 67P/Churyumov-Gerasimenko made the headlines when its "Philae" lander completed a successful unpowered descent onto the surface of the comet nucleus after "7 hours of terror" for the mission scientists. 67P's irregular shape and rotation made this task even more…

7 CFR 51.1219 - Well formed.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 2 2014-01-01 2014-01-01 false Well formed. 51.1219 Section 51.1219 Agriculture..., CERTIFICATION, AND STANDARDS) United States Standards for Grades of Peaches Definitions § 51.1219 Well formed. “Well formed” means that the shape of the peach may be slightly irregular but not to the extent that its...

7 CFR 51.1219 - Well formed.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 2 2013-01-01 2013-01-01 false Well formed. 51.1219 Section 51.1219 Agriculture..., CERTIFICATION, AND STANDARDS) United States Standards for Grades of Peaches Definitions § 51.1219 Well formed. “Well formed” means that the shape of the peach may be slightly irregular but not to the extent that its...

76 FR 52865 - Special Local Regulations for Marine Events; Patuxent River, Solomons, MD

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-24

... of Transportation, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington... event consists of offshore power boats racing in a counter-clockwise direction on an irregularly-shaped... Private Property This rule will not cause a taking of private property or otherwise have taking...

Special mandrel permits uniform welding of out-of-round tubing

NASA Technical Reports Server (NTRS)

Dor, M. E.; Fueg, L. B.; Whiffen, E. L.

1966-01-01

Clamp holds irregularly shaped pieces in lathe chuck without damage and eliminates excessive time in selecting optimum mounting. Interchangeable jaws ride in standard jaw slots but swivel so that the jaw face bears evenly against the workpiece regardless of contour. The jaws can be used on both engine and turret lathes.

Cotton NDVI response to applied N at different soil EC levels

USDA-ARS?s Scientific Manuscript database

Many fields in the southeastern Coastal Plain are highly variable in soil physical properties and are irregular in shape. These two conditions may make it difficult to determine the ‘best’ area in the field to place nitrogen (N) -rich strips for normalized difference vegetative index (NDVI) -based s...

Development and evaluation of spherical molecularly imprinted polymer beads.

PubMed

Kempe, Henrik; Kempe, Maria

2006-06-01

The majority of studies on molecularly imprinted polymers has until now been carried out on irregularly shaped particles prepared by grinding of polymer monoliths. The preparation procedures are time- and labor-consuming and produce particles of wide size distributions. To answer the need for fast and straightforward routes to spherical molecularly imprinted polymer beads, we have developed a method comprising the formation of droplets of pre-polymerization solution directly in mineral oil by vigorous mixing followed by transformation of the droplets into solid spherical beads by photoinduced free-radical polymerization. No detergents or stabilizers were required for the droplet formation. Factors influencing the bead synthesis have been investigated and are detailed here. The beads were evaluated in parallel with corresponding irregularly shaped particles prepared from polymer monoliths. Conditions for the synthesis of propranolol-imprinted poly(methacrylic acid-co-trimethylolpropane trimethacrylate) beads in the size range of 1-100 microm in almost quantitative yield are described. The beads were applied as the recognition element in a 96-well plate format radioligand assay of propranolol in human serum.

Filler features and their effects on wear and degree of conversion of particulate dental resin composites.

PubMed

Turssi, C P; Ferracane, J L; Vogel, K

2005-08-01

Based on the incomplete understanding on how filler features influence the wear resistance and monomer conversion of resin composites, this study sought to evaluate whether materials containing different shapes and combinations of size of filler particles would perform similarly in terms of three-body abrasion and degree of conversion. Twelve experimental monomodal, bimodal or trimodal composites containing either spherical or irregular shaped fillers ranging from 100 to 1500 nm were examined. Wear testings were conducted in the OHSU wear machine (n = 6) and quantified after 10(5) cycles using a profilometer. Degree of conversion (DC) was measured by FTIR spectrometry at the surface of the composites (n = 6). Data sets were analyzed using one-way Anova and Tukey's test at a significance level of 0.05. Filler size and geometry was found to have a significant effect on wear resistance and DC of composites. At specific sizes and combinations, the presence of small filler particles, either spherical or irregular, may aid in enhancing the wear resistance of composites, without compromising the percentage of reacted carbon double bonds.

Trajectory Design Employing Convex Optimization for Landing on Irregularly Shaped Asteroids

NASA Technical Reports Server (NTRS)

Pinson, Robin M.; Lu, Ping

2016-01-01

Mission proposals that land spacecraft on asteroids are becoming increasingly popular. However, in order to have a successful mission the spacecraft must reliably and softly land at the intended landing site with pinpoint precision. The problem under investigation is how to design a propellant optimal powered descent trajectory that can be quickly computed onboard the spacecraft, without interaction from the ground control. The propellant optimal control problem in this work is to determine the optimal finite thrust vector to land the spacecraft at a specified location, in the presence of a highly nonlinear gravity field, subject to various mission and operational constraints. The proposed solution uses convex optimization, a gravity model with higher fidelity than Newtonian, and an iterative solution process for a fixed final time problem. In addition, a second optimization method is wrapped around the convex optimization problem to determine the optimal flight time that yields the lowest propellant usage over all flight times. Gravity models designed for irregularly shaped asteroids are investigated. Success of the algorithm is demonstrated by designing powered descent trajectories for the elongated binary asteroid Castalia.

Study of a coincident observation between the ROCSAT-1 density irregularity and Ascension Island scintillation

NASA Astrophysics Data System (ADS)

Liu, Y. H.; Chao, C. K.; Su, S.-Y.; Liu, C. H.

2012-10-01

A coincident observation that occurred on 24 March 2000 between the irregularity structure measured by ROCSAT-1 and the scintillation experiment at the Ascension Island has been studied. The study of scintillation statistics is carried out first, and the results show that the Nakagami distribution can portray the normalized intensity of the L-band scintillation at various S4 values, up to S4 equal to 1.4. Moreover, the departure of frequency dependence on S4 predicted by the weak scintillation is noticed due to multiple forward scattering effects. The coincident feature between the characteristics of irregularity structure and the scintillation variation are then studied. The causal relationship between the fluctuation of ion density and the scintillation variation is obtained. A numerical simulation using the parabolic wave equation has been carried out with the ROCSAT-1 data in space to compare with the ground scintillation observation. The results show the reasonable scintillation level at the coincident time to indicate a direct relationship between the irregularity structure and the scintillation in both temporal and amplitudinal variations. Finally, some assumptions and limitations of the simulation model are discussed.

Structural characteristics and crystalline properties of lotus seed resistant starch and its prebiotic effects.

PubMed

Zhang, Yi; Zeng, Hongliang; Wang, Ying; Zeng, Shaoxiao; Zheng, Baodong

2014-07-15

Lotus seed resistant starch (LRS) is a type of retrograded starch that is commonly known as resistant starch type 3 (RS3). The structural and crystalline properties of unpurified LRS (NP-LRS3), enzyme purified LRS after drying (GP-LRS3), and enzyme purified LRS (ZP-LRS3) were characterized. The result showed that the molecular weights of NP-LRS3, GP-LRS3, and ZP-LRS3 were 0.102 × 10(6), 0.014 × 10(6), and 0.025 × 10(6)Da, respectively. Compared with native starch and high amylose maize starch (HAMS), LRS lacked the polarization cross and the irregularly shaped LRS granules had a rougher surface, B-type crystal structure, and greater level of molecular order. The FT-IR measurements indicated no differences in the chemical groups. Analysis by (13)C NMR indicated an increased propensity for double helix formation and higher crystallinity in LRS than in the two other types of starch. Moreover, LRS was more effective than either glucose or HAMS in promoting the proliferation of bifidobacteria. Copyright © 2014 Elsevier Ltd. All rights reserved.

Electrochemical Performance of a V2O5 Cathode for a Sodium Ion Battery

NASA Astrophysics Data System (ADS)

Van Nghia, Nguyen; Long, Pham Duy; Tan, Ta Anh; Jafian, Samuel; Hung, I.-Ming

2017-06-01

In this paper, layered vanadium pentoxide (V2O5) is employed as a cathode material for a sodium ion battery. The V2O5 particle sizes range from 200 nm to 500 nm and the shapes of the aggregated V2O5 particles are non-homogeneous and irregular. The material exhibits a first discharge capacity of approximately 208.1 mAh g-1. The structure of V2O5 changes to a NaxV2O5 structure after Na+ insertion at the first discharge; the structure of NaxV2O5 remains stable␣during cycling. After 40 cycles, the discharge capacity retains 61.2% of the capacity of the second cycle. The capacity of V2O5 at a high charge/discharge current rate of 1.0 C is 49.1% of capacity at 0.1 C. Furthermore, the capacity returns to the initial value as the discharge rate returns to 0.1 C. The results of electrochemical performance tests indicate that V2O5 is a potential cathode material for sodium ion batteries.

Space-coiling fractal metamaterial with multi-bandgaps on subwavelength scale

NASA Astrophysics Data System (ADS)

Man, Xianfeng; Liu, Tingting; Xia, Baizhan; Luo, Zhen; Xie, Longxiang; Liu, Jian

2018-06-01

Acoustic metamaterials are remarkably different from conventional materials, as they can flexibly manipulate and control the propagation of sound waves. Unlike the locally resonant metamaterials introduced in earlier studies, we designed an ultraslow artificial structure with a sound speed much lower than that in air. In this paper, the space-coiling approach is proposed for achieving artificial metamaterial for extremely low-frequency airborne sound. In addition, the self-similar fractal technique is utilized for designing space-coiling Mie-resonance-based metamaterials (MRMMs) to obtain a band-dispersive spectrum. The band structures of two-dimensional (2D) acoustic metamaterials with different fractal levels are illustrated using the finite element method. The low-frequency bandgap can easily be formed, and multi-bandgap properties are observed in high-level fractals. Furthermore, the designed MRMMs with higher order fractal space coiling shows a good robustness against irregular arrangement. Besides, the proposed artificial structure was found to modify and control the radiation field arbitrarily. Thus, this work provides useful guidelines for the design of acoustic filtering devices and acoustic wavefront shaping applications on the subwavelength scale.

Arrested diatreme development: Standing Rocks East, Hopi Buttes, Navajo Nation, USA

NASA Astrophysics Data System (ADS)

Lefebvre, Nathalie S.; White, James D. L.; Kjarsgaard, Bruce A.

2016-01-01

Maar-diatreme volcanoes, defined by their relatively large pyroclastic debris-filled subsurface structures and craters that cut into the pre-eruptive land surface, are typically found in small-volume mafic to ultramafic monogenetic volcanic fields. Diatremes are associated with strong explosions throughout most of their development, focused along feeder dikes and generally attributed to magma-water interaction, or high magmatic volatiles. Detailed mapping of the magnificently exposed Standing Rocks East (SRE) diatreme shows evidence of additional eruptive complexity, and offers new insights into how the plumbing and vent structures of small-volume volcanoes evolve during an eruption. SRE is part of a larger, basanitic volcanic complex that includes several diatremes formed along a series of irregular, offset NW-SE trending dikes exposed 300 m below the pre-eruptive land surface. Its similarly oriented elliptical-shaped diatreme structure comprises predominantly country rock lithic-rich breccia of coarse inhomogeneously mixed wall-rock blocks sourced from above and below the current surface, plus sparse juvenile material. Domains of pyroclastic deposits crosscut the country rock breccia deposits, and the best exposed is the NW massif rising 35 m above the current erosional surface. It represents a cross-section of an evolving crater floor, and comprises matrix-rich lapilli tuff and spatter deposits cut by irregularly distributed dikes, some with very complex textures. The most significant deposit, in terms of volume, is an unbedded lapilli tuff that is poorly sorted and has a well-mixed population of wall-rock and juvenile clast varieties, thus resembling deposits typical of diatremes. It is overlain by and locally intercalated with spatter deposits, and this irregular contact demarcates the base of what was during eruption an uneven, evolving crater floor. The generally massive, variably welded spatter deposits constitute mostly lapilli-sized juvenile clasts with fluidal, folded-over shapes and ropy surfaces, subordinate thermally altered wall-rock and variegated domains of lapilli tuff. SRE shows a progressive transition from fissure to diatreme, and overall evolution from more explosive to weakly explosive eruption styles recorded at the conduit-crater transition. Diatreme development was initiated by deep-quarrying explosive eruptions along a fissure to form the country rock-rich breccia. Only parts of the fissure remained active as magma feeding the highly explosive eruptions along the fissure localized into discrete point sources forming the matrix-rich lapilli tuff deposits. These superimposed deposits record the passage of multiple debris-jets and subvertical fallback from shallow cratering arising from explosions triggered by magma-water interaction at numerous, discrete sites. However, instead of continuing to build a well-formed diatreme, the system switched to weak spattering with intermittent explosive activity and near-surface dike emplacement into the unconsolidated anisotropic, pyroclastic debris of the crater floor. Dominant spatter from strombolian-style bursts accumulated on the topographically varied, evolving unstable syn-eruptive crater floor, and led to local failure and remobilization. This study demonstrates how the combination of fissure behavior and sensitivity of the shallow plumbing system to local conditions during an eruption can lead to a decrease in eruptive footprint within the diatreme structure, and an overall decrease in explosivity resulting in the arrested development of an immature diatreme.

Comparison of morphology and phase composition of hydroxyapatite nanoparticles sonochemically synthesized with dual- or single-frequency ultrasonic reactor

NASA Astrophysics Data System (ADS)

Deng, Shi-ting; Yu, Hong; Liu, Di; Bi, Yong-guang

2017-10-01

To investigate how a dual- or single-frequency ultrasonic reactor changes the morphology and phase composition of hydroxyapatite nanoparticles (nHAPs), we designed and constructed the preparation of nHAPs using dual- or single-frequency ultrasonic devices, i.e., the single frequency ultrasonic generator with ultrasonic horn (25 kHz), the ultrasonic bath (40 kHz) and the dual-frequency sonochemical systems combined with the ultrasonic horn and the ultrasonic bath simultaneously (25 + 40 kHz). The results showed that the sonicated samples displayed a more uniform shape with less agglomeration than non-sonicated sample. The rod-shaped particles with 1.66 stoichiometry and without a second phase were synthesized successfully in the ultrasonic bath or horn systems. The nHAPs obtained from the dual-frequency ultrasonic systems exhibited a regular rod-shaped structure with better dispersion and more uniform shapes than those of obtained in either ultrasonic bath or horn systems. Additionally, the size of rod-shaped particles obtained in the dual-frequency ultrasound with a mean width of 35 nm and a mean length of 64 nm was smaller than other samples. A possible mechanism is that the dual-frequency ultrasound significantly enhances the cavitation yield over single frequency ultrasound and thus improves the dispersion of particles and reduces the size of the crystals. In addition, irregular holes can be observed in the nanoparticles obtained in the dual-frequency ultrasound. Therefore, the dual-frequency ultrasonic systems are expected to become a convenient, efficient and environmentally friendly synthetic technology to obtain well-defined nHAPs for specific biomedical applications.

Effect of catalyst on deposition of vanadium oxide in plasma ambient

NASA Astrophysics Data System (ADS)

Singh, Megha; Kumar, Prabhat; Saini, Sujit K.; Reddy, G. B.

2018-05-01

In this paper, we have studied effect of catalyst (buffer layer) on structure, morphology, crystallinity, uniformity of nanostructured thin films deposited in nitrogen plasma ambient keeping all other process parameters constant. The process used for deposition is novel known as Plasma Assisted Sublimation Process (PASP). Samples were then studied using SEM, TEM, HRTEM, Raman spectroscopy. By structural analysis it was found out that samples deposited on Ni layer composed chiefly of α-V2O5 but minor amount of other phases were present in the sample. Samples deposited on Al catalyst layer revealed different phase of V2O5, where sample deposited on Ag was composed chiefly of VO2±x phase. Further analysis revealed that morphology of samples is also affected by catalyst. While samples deposited in Al and Ag layer tend to have reasonably defined geometry, sample deposited on Ni layer were irregular in shape and size. All the results well corroborate with each other.

Aperiodic topological order in the domain configurations of functional materials

NASA Astrophysics Data System (ADS)

Huang, Fei-Ting; Cheong, Sang-Wook

2017-03-01

In numerous functional materials, such as steels, ferroelectrics and magnets, new functionalities can be achieved through the engineering of the domain structures, which are associated with the ordering of certain parameters within the material. The recent progress in technologies that enable imaging at atomic-scale spatial resolution has transformed our understanding of domain topology, revealing that, along with simple stripe-like or irregularly shaped domains, intriguing vortex-type topological domain configurations also exist. In this Review, we present a new classification scheme of 'Zm Zn domains with Zl vortices' for 2D macroscopic domain structures with m directional variants and n translational antiphases. This classification, together with the concepts of topological protection and topological charge conservation, can be applied to a wide range of materials, such as multiferroics, improper ferroelectrics, layered transition metal dichalcogenides and magnetic superconductors, as we discuss using selected examples. The resulting topological considerations provide a new basis for the understanding of the formation, kinetics, manipulation and property optimization of domains and domain boundaries in functional materials.

Symplasmata are a clonal, conditional, and reversible type of bacterial multicellularity

DOE PAGES

Tecon, Robin; Leveau, Johan H. J.

2016-08-18

Microorganisms are capable of remarkable social behaviours, such as forming transient multicellular assemblages with properties and adaptive abilities exceeding those of individual cells. Here, we report on the formation and structure of genets known as symplasmata produced by Pantoea eucalypti bacteria. Each symplasmatum develops clonally and stochastically from a single bacterium into a membrane-delimited, capsule-embedded cluster of progeny cells and with a frequency that depends on temperature, pH, and nutrient availability. Transposon mutagenesis identified several gene products required for symplasmata formation, including master regulator LrhA, replication inhibitor CspD, polysaccharide transporter RfbX3, and autoinducer synthase PhzI. We also show that bacteriamore » inside symplasmata are shaped irregularly with punctuated cell-to-cell contacts, metabolically responsive to environmental stimuli, dispersal-ready, and transcriptionally reprogrammed to anticipate multiple alternative futures in terms of carbon source availability. In conclusion, the structured and conditionable nature of symplasmata offers exciting prospects towards a mechanistic understanding of multicellular behaviours and their ecological significance.« less

Biomass characterization of laboratory-scale thermophilic-mesophilic wastewater treatment processes.

PubMed

Suvilampi, J; Lehtomäki, A; Rintala, J

2006-01-01

Two thermophilic-mesophilic wastewater treatment processes, one as the combination of the thermophilic activated sludge process (ASP), followed by the mesophilic ASP and the other as thermophilic suspended carrier biofilm process (SCBP), followed by the mesophilic ASP, were used to study sludge characteristics and floc formation. Thermophilic bacteria in both ASP and SCBP were able to form flocs, which were <50 microm in size and had a weak structure and irregular shape. Flocs in both the mesophilic ASPs were larger in size (50-500 microm) and had more compact structures. Filamentous bacteria played an important role in both the thermophilic and mesophilic processes by forming bridges between small flocs. Both thermophilic processes showed a high density of dispersed particles, such as free bacteria. When hydraulic retention time (HRT) was decreased the biofilm was retained in the thermophilic SCBP better than the flocs in the thermophilic ASP. The mesophilic ASPs efficiently removed dispersed particles originating from the thermophilic processes.

Sintering time optimization on red photoluminescence properties of manganese-doped boron carbon oxynitride (BCNO:Mn) phosphor

NASA Astrophysics Data System (ADS)

Wahid Nuryadin, Bebeh; Suryani, Yayu; Yuliani, Yuli; Setiadji, Soni; Yeti Nuryantini, Ade; Iskandar, Ferry

2018-04-01

The effect of sintering time to the transient nature and optimization of red photoluminescence manganese-doped boron carbon oxynitride (BCNO:Mn) phosphor was investigated. The BCNO:Mn samples were synthesized using a facile urea-assisted combustion route involving boric acid, citric acid, manganese salt and urea. The optimized intensity of the dual peak emission at 420 nm (blue emission) and 630 nm (red emission) in the photoluminescence (PL) spectrum could be achieved by controlling the sintering time of the BCNO:Mn. The BCNO:Mn samples in high-crystalline form was found to be in a cubic and hexagonal structure. Based on the PL analysis, it is suggested that the BCNO:Mn symmetric band at 630 nm can be attributed to the 4T1(4G)—6A1(6S) transition absorption of Mn2+ ions into the hexagonal structure. Microstructure analysis showed an irregular and agglomerated shape of the BCNO:Mn sample.

A hybrid multiview stereo algorithm for modeling urban scenes.

PubMed

Lafarge, Florent; Keriven, Renaud; Brédif, Mathieu; Vu, Hoang-Hiep

2013-01-01

We present an original multiview stereo reconstruction algorithm which allows the 3D-modeling of urban scenes as a combination of meshes and geometric primitives. The method provides a compact model while preserving details: Irregular elements such as statues and ornaments are described by meshes, whereas regular structures such as columns and walls are described by primitives (planes, spheres, cylinders, cones, and tori). We adopt a two-step strategy consisting first in segmenting the initial meshbased surface using a multilabel Markov Random Field-based model and second in sampling primitive and mesh components simultaneously on the obtained partition by a Jump-Diffusion process. The quality of a reconstruction is measured by a multi-object energy model which takes into account both photo-consistency and semantic considerations (i.e., geometry and shape layout). The segmentation and sampling steps are embedded into an iterative refinement procedure which provides an increasingly accurate hybrid representation. Experimental results on complex urban structures and large scenes are presented and compared to state-of-the-art multiview stereo meshing algorithms.

Shape, Density, and Geology of the Nucleus of Comet 103P/Hartley 2

NASA Technical Reports Server (NTRS)

Thomas, P.C.; A'hearn, Michael F.; Veverka, Joseph; Belton, Michael J. S.; Kissel, Jochen; Belton, Michael J. S.; Klaasen, Kenneth P.; McFadden, Lucy A.; Melosh, H. Jay; Schultz, Peter H.;

Scanning Electron Microscopic Structure of the Lingual Papillae of the Common Opossum (Didelphis marsupialis)

NASA Astrophysics Data System (ADS)

Okada, Shigenori; Schraufnagel, Dean E.

2005-08-01

The mammalian tongue has evolved for specialized functions in different species. The structure of its papillae tells about the animal's diet, habit, and taxonomy. The opossum has four kinds of lingual papillae (filiform, conical, fungiform, vallate). Scanning electron microscopy of the external features, connective tissue cores, and corrosion casts of the microvasculature show the filiform papillae have a spearhead-like main process and spiny accessory processes around the apical part of the main process. The shape and number of both processes depend on their position on the tongue. On the apex, the main processes have shovel-like capillary networks and the accessory processes have small conical networks. On the lingual radix, the processes have small capillary loops. In the patch region, conical papillae have capillaries arranged as a full sail curving posteriorly. The fungiform papillae are scattered among the filiform papillae and have capillary baskets beneath each taste bud. Giant fungiform papillae on the tongue tip are three to four times larger than the ones on the lingual body. Capillaries of giant papillae form a fan-shaped network. The opossum has three vallate papillae arranged in a triangle. Their tops have secondary capillary loops but not their lateral surfaces. Mucosal folds on the posterolateral border have irregular, fingerlike projections with cylindrical capillary networks. These findings and the structure of the rest of the masticatory apparatus suggest the lingual papillae of opossum have kept their ancestral carnivorous features but also developed the herbivore characteristics of other marsupials.

Scanning electron microscopic structure of the lingual papillae of the common opossum (Didelphis marsupialis).

PubMed

Okada, Shigenori; Schraufnagel, Dean E

2005-08-01

The mammalian tongue has evolved for specialized functions in different species. The structure of its papillae tells about the animal's diet, habit, and taxonomy. The opossum has four kinds of lingual papillae (filiform, conical, fungiform, vallate). Scanning electron microscopy of the external features, connective tissue cores, and corrosion casts of the microvasculature show the filiform papillae have a spearhead-like main process and spiny accessory processes around the apical part of the main process. The shape and number of both processes depend on their position on the tongue. On the apex, the main processes have shovel-like capillary networks and the accessory processes have small conical networks. On the lingual radix, the processes have small capillary loops. In the patch region, conical papillae have capillaries arranged as a full sail curving posteriorly. The fungiform papillae are scattered among the filiform papillae and have capillary baskets beneath each taste bud. Giant fungiform papillae on the tongue tip are three to four times larger than the ones on the lingual body. Capillaries of giant papillae form a fan-shaped network. The opossum has three vallate papillae arranged in a triangle. Their tops have secondary capillary loops but not their lateral surfaces. Mucosal folds on the posterolateral border have irregular, fingerlike projections with cylindrical capillary networks. These findings and the structure of the rest of the masticatory apparatus suggest the lingual papillae of opossum have kept their ancestral carnivorous features but also developed the herbivore characteristics of other marsupials.

A new spinner magnetometer using high sensitivity magneto-impedance sensor

NASA Astrophysics Data System (ADS)

Kodama, Kazuto

2016-04-01

A sensitive spinner magnetometer was developed using a pair of high-resolution Magneto-Impedance sensors. The MI sensor generally utilizes the MI effect of amorphous wire whose impedance changes by the application of a small magnetic field. Various kinds of MI sensors are currently used in many electric devices, for example, a magnetic compass chip built-in smart phones and car navigations. The MI sensor employed in this study is a pico-Tesla MI sensor, an especially sensitive MI sensor originally manufactured for industrial use to detect contamination of small magnetic particles in industrial materials such as fabrics. To detect weak magnetic signals from natural samples and avoid DC drift, a gradiometer system was employed that consists of a pair of the MI sensors and the electronics with analog filter and pre-amplification circuit. This MI gradiometer system was equipped to a commercial spinner magnetometer (SMD-88, Natsuhara Giken, Osaka) with the spinning rate of 5 Hz. It is demonstrated that this new spinner magnetometer is capable of measuring weak magnetic samples of 10-6 mAm2, with the highest resolution being 10-8 mAm2, approximately two orders of magnitude better than the previous one using a ring-core flux-gate sensor. One of the advantages of the MI spinner magnetometer is that it can be easily modified to accommodate samples of any shape and size. Moreover the slow-rotating speed (5 Hz) allows to measure samples for archeomagnetic studies that are usually irregular and fragile. Because the irregularity of shape increases errors in measuring the dipole component of the total magnetization, it is necessary to increase the distance between the sample and sensor, resulting in poorer sensitivity. The high-sensitivity MI sensor enables to measure the NRM of such irregular-shaped samples from an appropriate distance to the sample, with no significant loss of sensitivity.

Morphology and histology of male and female reproductive systems in the inseminating species Scoloplax distolothrix (Ostariophysi: Siluriformes: Scoloplacidae).

PubMed

Spadella, Maria Angélica; Oliveira, Claudio; Quagio-Grassiotto, Irani

2008-09-01

The morphology and histology of male and female reproductive systems were examined in Scoloplax distolothrix. Internal insemination was documented in this species by the presence of sperm within the ovaries. Mature males and females have elongated genital papillae, exhibiting a tubular shape in males and a plain heart-shape with two median protuberances in females. The testes are two elongated structures that converge ventrally, under the intestine, towards the genital papilla. They are joined at the caudal end, forming an ovoid single chamber for sperm storage. Secretory regions were not observed. In the lumen of the testicular tubules, spermatozoa can be tightly packed along their lengths, but do not constitute a spermatozeugmata. The lumen of the sperm storage chamber and spermatic duct are filled with free spermatozoa without the accompanying secretions. The ovaries are bird-wing shaped, saccular structures that converge ventrally under the intestine, towards the genital papilla. They are joined at the caudal end, forming a tubular chamber possibly destined for oocyte storage. An oviduct with an irregular outline connects the chamber to the tubular region of the genital papilla. No distinct sperm storage structure was found in the ovaries. The unique male and female genital papillae suggest that these structures are associated with the reproductive mode in scoloplacids, representing evidence for insemination. The occurrence of free spermatozoa, without the accompanying secretions and not arranged in a spermatozeugmata can be associated with the presence of a tubular male genital papilla for sperm transfer to the female genital tract. This reinforces the idea that sperm packets are not necessary for all inseminating species. The male reproductive system in scoloplacids is very different from that in auchenipterids, a second catfish family with insemination, which indicates that the occurrence of insemination is not connected to the internal morphology of reproductive organs.

Numerical study on 3D composite morphing actuators

NASA Astrophysics Data System (ADS)

Oishi, Kazuma; Saito, Makoto; Anandan, Nishita; Kadooka, Kevin; Taya, Minoru

2015-04-01

There are a number of actuators using the deformation of electroactive polymer (EAP), where fewer papers seem to have focused on the performance of 3D morphing actuators based on the analytical approach, due mainly to their complexity. The present paper introduces a numerical analysis approach on the large scale deformation and motion of a 3D half dome shaped actuator composed of thin soft membrane (passive material) and EAP strip actuators (EAP active coupon with electrodes on both surfaces), where the locations of the active EAP strips is a key parameter. Simulia/Abaqus Static and Implicit analysis code, whose main feature is the high precision contact analysis capability among structures, are used focusing on the whole process of the membrane to touch and wrap around the object. The unidirectional properties of the EAP coupon actuator are used as input data set for the material properties for the simulation and the verification of our numerical model, where the verification is made as compared to the existing 2D solution. The numerical results can demonstrate the whole deformation process of the membrane to wrap around not only smooth shaped objects like a sphere or an egg, but also irregularly shaped objects. A parametric study reveals the proper placement of the EAP coupon actuators, with the modification of the dome shape to induce the relevant large scale deformation. The numerical simulation for the 3D soft actuators shown in this paper could be applied to a wider range of soft 3D morphing actuators.

Frontal belt curvature and oblique ramp development at an obliquely collided irregular margin: Geometry and kinematics of the NW Taiwan fold-thrust belt

NASA Astrophysics Data System (ADS)

Lacombe, Olivier; Mouthereau, FréDéRic; Angelier, Jacques; Chu, Hao-Tsu; Lee, Jian-Cheng

2003-06-01

Combined structural and tectonic analyses demonstrate that the NW Foothills of the Taiwan collision belt constitute mainly an asymmetric "primary arc" type fold-thrust belt. The arcuate belt developed as a basin-controlled salient in the portion of the foreland basin that was initially thicker, due to the presence of a precollisional depocenter (the Taihsi basin). Additional but limited buttress effects at end points related to interaction with foreland basement highs (Kuanyin and Peikang highs) may have also slightly enhanced curvature. The complex structural pattern results from the interaction between low-angle thrusting related to shallow decollement tectonics and oblique inversion of extensional structures of the margin on the southern edge of the Kuanyin basement high. The tectonic regimes and mechanisms revealed by the pattern of paleostress indicators such as striated outcrop-scale faults are combined with the orientation and geometry of offshore and onshore regional faults in order to accurately define the Quaternary kinematics of the propagating units. The kinematics of this curved range is mainly controlled by distributed transpressional wrenching along the southern edge of the Kuanyin high, leading to the development of a regional-scale oblique ramp, the Kuanyin transfer fault zone, which is conjugate of the NW trending Pakua transfer fault zone north of the Peikang basement high. The divergence between the N120° regional transport direction and the maximum compressive trend that evolved from N120° to N150° (and even to N-S) in the northern part of the arc effectively supports distributed wrench deformation along its northern limb during the Pleistocene. The geometry and kinematics of the western Taiwan Foothills therefore appear to be highly influenced by both the preorogenic structural pattern of the irregularly shaped Chinese passive margin and the obliquity of its Plio-Quaternary collision with the Philippine Sea plate.

An analytical method to calculate equivalent fields to irregular symmetric and asymmetric photon fields.

PubMed

Tahmasebi Birgani, Mohamad J; Chegeni, Nahid; Zabihzadeh, Mansoor; Hamzian, Nima

2014-01-01

Equivalent field is frequently used for central axis depth-dose calculations of rectangular- and irregular-shaped photon beams. As most of the proposed models to calculate the equivalent square field are dosimetry based, a simple physical-based method to calculate the equivalent square field size was used as the basis of this study. The table of the sides of the equivalent square or rectangular fields was constructed and then compared with the well-known tables by BJR and Venselaar, et al. with the average relative error percentage of 2.5 ± 2.5% and 1.5 ± 1.5%, respectively. To evaluate the accuracy of this method, the percentage depth doses (PDDs) were measured for some special irregular symmetric and asymmetric treatment fields and their equivalent squares for Siemens Primus Plus linear accelerator for both energies, 6 and 18MV. The mean relative differences of PDDs measurement for these fields and their equivalent square was approximately 1% or less. As a result, this method can be employed to calculate equivalent field not only for rectangular fields but also for any irregular symmetric or asymmetric field. © 2013 American Association of Medical Dosimetrists Published by American Association of Medical Dosimetrists All rights reserved.

Manufacture of Regularly Shaped Sol-Gel Pellets

NASA Technical Reports Server (NTRS)

Leventis, Nicholas; Johnston, James C.; Kinder, James D.

2006-01-01

An extrusion batch process for manufacturing regularly shaped sol-gel pellets has been devised as an improved alternative to a spray process that yields irregularly shaped pellets. The aspect ratio of regularly shaped pellets can be controlled more easily, while regularly shaped pellets pack more efficiently. In the extrusion process, a wet gel is pushed out of a mold and chopped repetitively into short, cylindrical pieces as it emerges from the mold. The pieces are collected and can be either (1) dried at ambient pressure to xerogel, (2) solvent exchanged and dried under ambient pressure to ambigels, or (3) supercritically dried to aerogel. Advantageously, the extruded pellets can be dropped directly in a cross-linking bath, where they develop a conformal polymer coating around the skeletal framework of the wet gel via reaction with the cross linker. These pellets can be dried to mechanically robust X-Aerogel.

Analysis of the shapes of hemocytes of Callista brevisiphonata in vitro (Bivalvia, Veneridae).

PubMed

Karetin, Yu A; Pushchin, I I

2015-08-01

Fractal formalism in conjunction with linear methods of image analysis is suitable for the comparative analysis of such "irregular" shapes (from the point of view of classical Euclidean geometry) as flattened amoeboid cells of invertebrates in vitro. Cell morphology of in vitro spreading hemocytes from the bivalve mollusc Callista brevisiphonata was analyzed using correlation, factor and cluster analysis. Four significantly different cell types were identified on the basis of 36 linear and nonlinear parameters. The analysis confirmed the adequacy of the selected methodology for numerical description of the shape and the adequacy of classification of nonlinear shapes of spread hemocytes belonging to the same species. Investigation has practical significance for the description of the morphology of cultured cells, since cell shape is a result of summation of a number of extracellular and intracellular factors. © 2015 International Society for Advancement of Cytometry.

Hubble Peers at a Distinctly Disorganized Dwarf Galaxy

NASA Image and Video Library

2017-12-08

Despite being less famous than their elliptical and spiral galactic cousins, irregular dwarf galaxies, such as the one captured in this NASA/ESA Hubble Space Telescope image, are actually one of the most common types of galaxy in the universe. Known as UGC 4459, this dwarf galaxy is located approximately 11 million light-years away in the constellation of Ursa Major (The Great Bear), a constellation that is also home to the Pinwheel Galaxy (M101), the Owl Nebula (M97), Messier 81, Messier 82 and several other galaxies all part of the M81 group. UGC 4459’s diffused and disorganized appearance is characteristic of an irregular dwarf galaxy. Lacking a distinctive structure or shape, irregular dwarf galaxies are often chaotic in appearance, with neither a nuclear bulge — a huge, tightly packed central group of stars — nor any trace of spiral arms — regions of stars extending from the center of the galaxy. Astronomers suspect that some irregular dwarf galaxies were once spiral or elliptical galaxies, but were later deformed by the gravitational pull of nearby objects. Rich with young blue stars and older red stars, UGC 4459 has a stellar population of several billion. Though seemingly impressive, this is small when compared to the 200 to 400 billion stars in the Milky Way! Observations with Hubble have shown that because of their low masses of dwarf galaxies like UGC 4459, star formation is very low compared to larger galaxies. Only very little of their original gas has been turned into stars. Thus, these small galaxies are interesting to study to better understand primordial environments and the star formation process. Image Credit: ESA/Hubble and NASA; Acknowledgement: Judy Schmidt NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Nucleoli in human early erythroblasts (K2, K1, K1/2 cells).

PubMed

Smetana, K; Jirásková, I; Klamová, H

2005-01-01

Human early erythroid precursors classified according to the nuclear size were studied to provide information on nucleoli in these cells using simple cytochemical procedures for demonstration of RNA and proteins of silver-stained nucleolar organizers. K2 cells with nuclear diameter larger than 13 microm and K1 cells with nuclear diameter larger than 9 microm corresponding to proerythroblasts and macroblasts (large basophilic erythroblasts) mostly possessed large irregularly shaped nucleoli with multiple fibrillar centres representing "active nucleoli". K1/2 cells with nuclear diameter smaller than 9 microm corresponding to small basophilic erythroblasts were usually characterized by the presence of micronucleoli representing "inactive nucleolar types". On the other hand, a few K1/2 cells contained large nucleoli with multiple fibrillar centres similar to those present in K2 cells and thus appeared as "microproerythroblasts". The nucleolar asynchrony expressed by the presence of large irregularly shaped nucleoli with multiple nucleoli (active nucleoli) and ring-shaped nucleoli (resting nucleoli) in one and the same nucleus of K2 or K1 cells was not exceptional and might reflect a larger resistance of these cells to negative factors influencing the erythropoiesis. The intranucleolar translocation of silver-stained nucleolus organized regions was noted in K2 cells and might indicate the premature aging of these cells without further differentiation. More studies, however, are required in this direction.

Automated Segmentation of Nuclei in Breast Cancer Histopathology Images.

PubMed

Paramanandam, Maqlin; O'Byrne, Michael; Ghosh, Bidisha; Mammen, Joy John; Manipadam, Marie Therese; Thamburaj, Robinson; Pakrashi, Vikram

2016-01-01

The process of Nuclei detection in high-grade breast cancer images is quite challenging in the case of image processing techniques due to certain heterogeneous characteristics of cancer nuclei such as enlarged and irregularly shaped nuclei, highly coarse chromatin marginalized to the nuclei periphery and visible nucleoli. Recent reviews state that existing techniques show appreciable segmentation accuracy on breast histopathology images whose nuclei are dispersed and regular in texture and shape; however, typical cancer nuclei are often clustered and have irregular texture and shape properties. This paper proposes a novel segmentation algorithm for detecting individual nuclei from Hematoxylin and Eosin (H&E) stained breast histopathology images. This detection framework estimates a nuclei saliency map using tensor voting followed by boundary extraction of the nuclei on the saliency map using a Loopy Back Propagation (LBP) algorithm on a Markov Random Field (MRF). The method was tested on both whole-slide images and frames of breast cancer histopathology images. Experimental results demonstrate high segmentation performance with efficient precision, recall and dice-coefficient rates, upon testing high-grade breast cancer images containing several thousand nuclei. In addition to the optimal performance on the highly complex images presented in this paper, this method also gave appreciable results in comparison with two recently published methods-Wienert et al. (2012) and Veta et al. (2013), which were tested using their own datasets.

Automated Segmentation of Nuclei in Breast Cancer Histopathology Images

PubMed Central

Paramanandam, Maqlin; O’Byrne, Michael; Ghosh, Bidisha; Mammen, Joy John; Manipadam, Marie Therese; Thamburaj, Robinson; Pakrashi, Vikram

2016-01-01

The process of Nuclei detection in high-grade breast cancer images is quite challenging in the case of image processing techniques due to certain heterogeneous characteristics of cancer nuclei such as enlarged and irregularly shaped nuclei, highly coarse chromatin marginalized to the nuclei periphery and visible nucleoli. Recent reviews state that existing techniques show appreciable segmentation accuracy on breast histopathology images whose nuclei are dispersed and regular in texture and shape; however, typical cancer nuclei are often clustered and have irregular texture and shape properties. This paper proposes a novel segmentation algorithm for detecting individual nuclei from Hematoxylin and Eosin (H&E) stained breast histopathology images. This detection framework estimates a nuclei saliency map using tensor voting followed by boundary extraction of the nuclei on the saliency map using a Loopy Back Propagation (LBP) algorithm on a Markov Random Field (MRF). The method was tested on both whole-slide images and frames of breast cancer histopathology images. Experimental results demonstrate high segmentation performance with efficient precision, recall and dice-coefficient rates, upon testing high-grade breast cancer images containing several thousand nuclei. In addition to the optimal performance on the highly complex images presented in this paper, this method also gave appreciable results in comparison with two recently published methods—Wienert et al. (2012) and Veta et al. (2013), which were tested using their own datasets. PMID:27649496

Equilibrium shapes and surface selection of nanostructures in 6H-SiC

DOE PAGES

Kondo, Sosuke; Parish, Chad M.; Koyanagi, Takaaki; ...

2017-04-03

Here, the equilibrium shape of 6H-SiC nanostructures and their surfaces were studied by analyzing nano-void (~10 nm) shapes, which were introduced in monocrystalline 6H-SiC by high-temperature neutron irradiation, using transmission electron microscopy. The nano-voids were determined to be irregular icosahedrons truncated with six {1¯100}, twelve {1¯103}, one smaller top-basal, and one larger bottom-basal planes, which suggests that {1¯100} and {1¯103} are the next stable surface class after the basal planes. The relatively frequent absence of the {1¯100} surface in the nano-voids indicated that the (1¯103¯) surface type is energetically rather stable. These non-basal surfaces were found not to be atomicallymore » flat due to the creation of nanofacets with half unit-cell height in the c-axis. The {1¯100} and {1¯103} surfaces were classified as two and four face types according to their possible nanofacets and surface termination, respectively. We also discuss the surface energy difference between the (1¯103¯) and (1¯103) face types in relation to the energy balance within the equilibrium, but irregular, polyhedron, in which the (1¯103) surface had double the surface energy of the (1¯103¯) surface (~3900 erg/cm 2).« less

Computed Tomography Angiography Evaluation of Risk Factors for Unstable Intracranial Aneurysms.

PubMed

Wang, Guang-Xian; Gong, Ming-Fu; Wen, Li; Liu, Lan-Lan; Yin, Jin-Bo; Duan, Chun-Mei; Zhang, Dong

2018-03-19

To evaluate risk factors for instability in intracranial aneurysms (IAs) using computed tomography angiography (CTA). A total of 614 consecutive patients diagnosed with 661 IAs between August 2011 and February 2016 were reviewed. Patients and IAs were divided into stable and unstable groups. Along with clinical characteristics, IA characteristics were evaluated by CTA. Multiple logistic regression analysis was used to identify the independent risk factors associated with unstable IAs. Receiver operating characteristic (ROC) curve analysis was performed on the final model, and optimal thresholds were obtained. Patient age (odds ratio [OR], 0.946), cerebral atherosclerosis (CA; OR, 0.525), and IAs located at the middle cerebral artery (OR, 0.473) or internal carotid artery (OR, 0.512) were negatively correlated with instability, whereas IAs with irregular shape (OR, 2.157), deep depth (OR, 1.557), or large flow angle (FA; OR, 1.015) were more likely to be unstable. ROC analysis revealed threshold values of age, depth, and FA of 59.5 years, 4.25 mm, and 87.8°, respectively. The stability of IAs is significantly affected by several factors, including patient age and the presence of CA. IA shape and location also have an impact on the stability of IAs. Growth into an irregular shape, with a deep depth, and a large FA are risk factors for a change in IAs from stable to unstable. Copyright © 2018 Elsevier Inc. All rights reserved.

Mechanisms of structural colour in the Morpho butterfly: cooperation of regularity and irregularity in an iridescent scale.

PubMed Central

Kinoshita, Shuichi; Yoshioka, Shinya; Kawagoe, Kenji

2002-01-01

Structural colour in the Morpho butterfly originates from submicron structure within a scale and, for over a century, its colour and reflectivity have been explained as interference of light due to the multilayer of cuticle and air. However, this model fails to explain the extraordinarily uniform colour of the wing with respect to the observation direction. We have performed microscopic, optical and theoretical investigations, and have found that the separate lamellar structure with irregular heights is extremely important. Using a simple model, we have shown that the combined action of interference and diffraction is essential for the structural colour of the Morpho butterfly. PMID:12137569

Correlation of In Situ Measurements of Plasma Irregularities with Ground-Based Scintillation Observations

DTIC Science & Technology

2010-06-01

extensive case study of the relationships between the observation of in situ irregularities, UHF scintillation observed by the Scin - tillation Decision...use these space-based measurements, however, the correlation between the structures and the resulting scin - tillation must be quantified. [10] As a

Regenerating oak-dominated forests using irregular, gap-based silvicultural systems

Treesearch

John M. Lhotka; Michael R. Saunders; John M. Kabrick; Daniel C. Dey

2013-01-01

Throughout the Eastern United States, practitioners have primarily focused on using uniformly applied even-aged approaches to regenerate oak species. Irregular, gap-based silvicultural systems offer an alternative that retains continuous canopy cover, creates heterogeneous forest structure, and provides multiple income flows over a rotation. Although commonly used in...

The Irregular Moons of Saturn

NASA Astrophysics Data System (ADS)

Denk, Tilmann; Mottola, Stefano; Tosi, Federico; Bottke, William; Hamilton, Douglas P.

2017-10-01

The 38 irregular moons of Saturn, all but Phoebe discovered between 2000 and 2007, outnumber the planet's classical satellites. Observations from the ground and from near-Earth space have revealed orbits, sizes, and colors and have hinted at the existence of dynamical families, indicative of collisional evolution and common progenitors. More recently, remote observations of many irregular satellites with the Cassini spacecraft produced lightcurves that helped determine rotational periods, coarse shape models, potential hemispheric color heterogeneities, and other basic properties.From Cassini, a total of 25 Saturnian irregulars have been observed with the ISS camera. Their rotational periods range from 5.45 h to 76.13 h. The absence of fast rotators is evident. Among main-belt asteroids of the same size range (~4 to ~45 km), one third of the objects have faster rotations, indicating that many irregulars should be low-density objects.While the origin of the irregulars is still debated, capture of comets via three-body interactions during giant planets encounters does the best job thus far at reproducing the observed prograde/retrograde orbits. Data from the ground, near-Earth spacecraft, and Cassini as well as modeling results suggest the population visible today has experienced substantial collisional evolution. It may be that only Phoebe has survived relatively intact. The small particle debris drifts toward Saturn by P-R drag, with most of it swept up by Titan. Only remnants of this process are visible today.Our current knowledge on the Saturnian irregulars will be summarized in a chapter [1] in the book "Enceladus and the Icy Moons of Saturn" [2]. The talk will give an overview on the chapter's content, which covers the following topics: Orbital "architecture" (a,e,i), sizes and colors, Cassini observations and results, Phoebe, origin, an outlook.[1] Denk, T., Mottola, S., Tosi, F., Bottke, W.F., Hamilton, D.P. (2018): The Irregular Satellites of Saturn. In: Enceladus and the Icy Moons of Saturn (Schenk, P. et al., eds.), Space Science Series, The University of Arizona Press. In press.[2] See http://www.uapress.arizona.edu/Books/bid2726.htm

Onion-like nanoscale structures and fullerene-type cages formed by electron irradiation on turbostratic B{sub x}C{sub 1{minus}x} (x<0.2)

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

Golberg, D.; Bando, Y.; Kurashima, K.

Flakes of CVD grown B{sub x}C{sub 1{minus}x} (x<0.2) films were exposed to intense electron irradiation (flux density up to {approximately}100 A/cm{sup 2}) in a 300 kV high resolution electron microscope equipped with a field emission gun. The starting flakes revealed a turbostratic B{sub x}C{sub 1{minus}x} structure. The composition of the starting materials and irradiated products was determined by using electron energy loss spectroscopy (EELS). Depending on the electron dose applied, irradiation of the turbostratic material led to formation of soap-bubble-like irregularly-shaped objects (linear dimensions of {approximately}2--5 nm), onion- and semi-onion-like structures (d{approximately}10nm), nested fullerenes (3--14 shells) and elementary fullerene-type cagesmore » (d{approximately}0.7 nm). It is thought that these curled and closed nanostructures arise from a continuous bending of the hexagonal B{sub x}C{sub 1{minus}x} sheets under electron irradiation. Finally, some possible structural models of B{sub x}C{sub 1{minus}x} fullerenes are considered.« less

Coating formulation and method for refinishing the surface of surface-damaged graphite articles

DOEpatents

Ardary, Z.L.; Benton, S.T.

1987-07-08

The described development is directed to a coating formulation for filling surface irregularities in graphite articles such as molds, crucibles, and matched die sets used in high-temperature metallurgical operations. The coating formulation of the present invention is formed of carbon black flour, thermosetting resin and a solvent for the resin. In affixing the coating to the article, the solvent is evaporated, the resin cured to bond the coating to the surface of the article and then pyrolyzed to convert the resin to carbon. Upon completion of the pyrolysis step, the coating is shaped and polished to provide the article with a surface restoration that is essentially similar to the original or desired surface finish without the irregularity.

Coating formulation and method for refinishing the surface of surface-damaged graphite articles

DOEpatents

Ardary, Zane L.; Benton, Samuel T.

1988-01-01

The described development is directed to a coating formulation for filling surface irregularities in graphite articles such as molds, crucibles, and matched die sets used in high-temperature metallurgical operations. The coating formulation of the present invention is formed of carbon black flour, thermosetting resin and a solvent for the resin. In affixing the coating to the article, the solvent is evaporated, the resin cured to bond the coating to the surface of the article and then pyrolyzed to convert the resin to carbon. Upon completion of the pyrolysis step, the coating is shaped and polished to provide the article with a surface restoration that is essentially similar to the original or desired surface finish without the irregularity.

Coating formulation and method for refinishing the surface of surface-damaged graphite articles

DOEpatents

Ardary, Z.L.; Benton, S.T.

1988-11-22

The described development is directed to a coating formulation for filling surface irregularities in graphite articles such as molds, crucibles, and matched die sets used in high-temperature metallurgical operations. The coating formulation of the present invention is formed of carbon black flour, thermosetting resin and a solvent for the resin. In affixing the coating to the article, the solvent is evaporated, the resin cured to bond the coating to the surface of the article and then pyrolyzed to convert the resin to carbon. Upon completion of the pyrolysis step, the coating is shaped and polished to provide the article with a surface restoration that is essentially similar to the original or desired surface finish without the irregularity.

Identification and Characterization of Pseudocercospora pyricola Causing Leaf Spots on Aronia melanocarpa.

PubMed

Park, Sung-Hee; Choi, In-Young; Seo, Kyoung-Won; Kim, Jin-Ho; Galea, Victor; Shin, Hyeon-Dong

2017-03-01

Leaf spot disease on black chokeberry ( Aronia melanocarpa ) was observed at several locations in Korea during 2014-2015. Leaf spots were distinct, scattered over the leaf surface and along the leaf border, subcircular to irregular and brown surrounded by a distinct dark color, and were expanded and coalesced into irregularly shaped lesions. Severely infected leaves became dry and fell off eventually. The causative agent was identified as Pseudocercospora pyricola . Morphological observations and phylogenetic analyses of multiple genes, including internal transcribed spacer, translation elongation factor 1-alpha, actin, and the large subunit ribosomal DNA were conducted. The pathogenicity test was conducted twice yielding similar results, fulfilling Koch's postulates. To our knowledge, this is the first report on P. pyricola infection of A. melanocarpa globally.

Geochemistry of impact glasses and target rocks from the Zhamanshin impact structure, Kazakhstan: Implications for mixing of target and impactor matter

NASA Astrophysics Data System (ADS)

Jonášová, Šárka; Ackerman, Lukáš; Žák, Karel; Skála, Roman; Ďurišová, Jana; Deutsch, Alexander; Magna, Tomáš

2016-10-01

Internal structure and element chemistry including contents of highly siderophile elements (HSE) and Os isotope ratios have been studied in target rocks and several groups of impact glasses of the Zhamanshin impact structure, Kazakhstan. These include larger irregularly-shaped fragments and blocks of impact glass (zhamanshinites), and three types of tektite-like splash-form glasses, part of fallback ejecta. These glassy objects typically are up to 30 mm large and are shaped as teardrops, irregularly bent and curved glass rods and fibers. They can be subdivided into acidic types (irghizites; typically 69-76 wt.% SiO2), basic splash-forms (typically 53-56 wt.% SiO2), and rarely occurring highly inhomogeneous composites with abundant mineral inclusions. A comparison with the target rocks shows that zhamanshinites and basic splash-forms usually have no detectable admixture of the projectile matter, indicated by major and trace elements as well as highly siderophile element contents, with the exception of one sample containing Fe-, Cr-, Ni- and Ti-enriched particles and elevated HSE contents. In contrast, irghizites exhibit clear admixture of the projectile matter, which was incorporated by complex processes accompanied by strong element fractionations. Microscopic investigations confirm that irghizites were formed mainly by coalescence of smaller molten glass droplets sized typically below 1 mm. Irghizites exhibit significant enrichments in Ni, Co and Cr, whose concentrations are locally elevated in the rims of the original small droplets. A portion of these elements and also part of Fe and Mn and other elements were derived from the impactor, most likely a Ni-rich carbonaceous chondrite. The contents of HSE are low and strongly fractionated, with moderate depletions of Pt and Pd and strong depletions of other HSE with respect to chondritic element ratios. Osmium shows the strongest depletion, likely related to the presence of oxygen in the post-impact atmosphere causing strong Os loss through volatilization. One composite splash-form contains Fe-Ni-S inclusions and exhibits a less fractionated HSE pattern suggesting the lowest degree of melting, volatilization and condensation. The observed structural and microchemical features of irghizites are interpreted to reflect variable proportions of the uppermost target sediments and the projectile matter, with HSE element ratios influenced by evaporation and condensation processes, and differences in volatility of individual HSE elements and/or their compounds. Two possible pathways of incorporation of the projectile matter into the irghizites include either re-condensation of evaporated projectile matter on the surface of glass droplets, or incorporation of less chemically fractionated microparticles dispersed by the explosion.

Influence of edging practices on cutting yields of Alaska birch lumber

Treesearch

David L. Nicholls; J.W. Funck; C.C. Brunner; J.E. Reeb

2009-01-01

Birch lumber is often characterized by a high degree of knots, bark pockets, heartwood, and other features which force sawmill owners to decide whether to edge and trim boards to produce standard grade lumber vs. proprietary grade character-marked lumber. In addition, the edging strategies used with irregularly shaped flitches can greatly influence cut-stock recovery....

Saturn: Origin and composition of its inner moons and rings

NASA Technical Reports Server (NTRS)

Prentice, A. J. R.

1980-01-01

The contraction of the primitive protosaturnian cloud, using ideas of supersonic turbulent convection was modeled. The model suggested that each of Saturn's inner moons, excepting Rhea, condensed above the ice-point of water and consists primarily of hydrous magnesium silicates. The satellite mean densities steadily increase towards the planet and the rocky moons are irregular in shape.

Finding the Center of Volume of the Forearm

ERIC Educational Resources Information Center

Klein, Stacy S.; Roselli, Robert J.

2008-01-01

A typical first-year physics course teaches students about the center of mass using both regular and irregularly shaped objects. Students often suspend an object in each of two dimensions from a string with the intersection determining the center of mass of the object. While these methods can be effective, they are not particularly exciting or…

Water content measurement in forest soils and decayed wood using time domain reflectometry

Treesearch

Andrew Gray; Thomas Spies

1995-01-01

The use of time domain reflectometry to measure moisture content in forest soils and woody debris was evaluated. Calibrations were developed on undisturbed soil cores from four forest stands and on point samples from decayed logs. An algorithm for interpreting irregularly shaped traces generated by the reflectometer was also developed. Two different calibration...

77 FR 47279 - Special Local Regulations for Marine Events, Patuxent River; Solomons, MD

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-08

... Management Facility in Room W12-140 on the ground floor of the Department of Transportation West Building... on an irregularly-shaped course located between the Governor Thomas Johnson Memorial (SR-4) Bridge..., we do discuss the effects of this rule elsewhere in this preamble. 8. Taking of Private Property This...

Glass/Jamming Transition in Colloidal Aggregation

NASA Technical Reports Server (NTRS)

Segre, Philip N.; Prasad, Vikram; Weitz, David A.; Rose, M. Franklin (Technical Monitor)

2000-01-01

We have studied colloidal aggregation in a model colloid plus polymer system with short-range attractive interactions. By varying the colloid concentration and the strength of the attraction, we explored regions where the equilibrium phase is expected to consist of colloidal crystallites in coexistance with colloidal gas (i.e. monomers). This occurs for moderate values of the potential depth, U approximately equal to 2-5 kT. Crystallization was not always observed. Rather, over an extended sub-region two new metastable phases appear, one fluid-like and one solid-like. These were examined in detail with light scattering and microscopy techniques. Both phases consist of a near uniform distribution of small irregular shaped clusters of colloidal particles. The dynamical and structural characteristics of the ergodic-nonergodic transition between the two phases share much in common with the colloidal hard sphere glass transition.

Influence of stabilizers on the physicochemical characteristics of inhaled insulin powders produced by supercritical antisolvent process.

PubMed

Kim, Yong Ho; Sioutas, Constantinos; Shing, Katherine S

2009-01-01

To examine the effect of stabilizers on aerosol physicochemical characteristics of inhaled insulin particles produced using a supercritical fluid technology. Insulin with stabilizers such as mannitol and trehalose was micronized by aerosol solvent extraction system (ASES). The supercritically-micronized insulin particles were characterized for size, shape, aerosol behavior, crystallinity and secondary structure. Experimental results indicated that when insulin was incorporated with the most commonly used stabilizer mannitol (insulin/mannitol: 15/85 wt.%, designated IM), the particles formed were irregular and needle-shaped and had a tendency to agglomerate. With the incorporation of a second stabilizer trehalose (insulin/mannitol/trehalose: 15/70/15 wt.%, designated IMT), the particles were relatively uniform, more spherical, less cohesive, and less agglomerated in an air flow, when compared to IM particles. The mass median aerodynamic diameter of the IMT particles was 2.32 mum which is suitable for use in inhalation therapy. In vitro deposition test using micro-orifice uniform deposit impactor showed 69 +/- 7 wt.% of the IMT particles was deposited in stage 3, 4, 5 and 6 while 41 +/- 15 wt.% of the IM particles was deposited in the same stages. In terms of insulin stability, secondary structures of insulin particles were not adversely affected by the ASES processing studied here. When properly formulated (as in IMT particles), ASES process can produce particles with appropriate size and size distribution suitable for pulmonary insulin delivery.

Generation of Plasma Density Irregularities in the Midlatitude/Subauroral F Region

NASA Astrophysics Data System (ADS)

Mishin, E. V.

2017-12-01

A concise review is given of the current state of the theoretical understanding of the creation of small- and meso-scale plasma density irregularities in the midlatitude/subauroral F region during quiet and disturbed periods. The former are discussed in terms of the temperature gradient instability (TGI) in the vicinity of the ionospheric projection of the plasmapause and the Perkins instability. During active conditions some part of the midlatitude ionosphere becomes the subauroral region dominated by enhanced westward flows (SAPS and SAID) driven by poleward electric fields. Their irregular, often nonlinear wave structure leads to the formation of plasma density irregularities in the plasmasphere and conjugate ionosphere. Here, meso-scale irregularities are due to the positive feedback magnetosphere-ionosphere coupling instability, while small scales resulted from the gradient drift instability (GDI), temperature GDI, and the ion frictional heating instability. The theoretical predictions are compared with satellite observations in the perturbed subauroral geospace.

Quantitative analysis of morphological changes in yeast colonies growing on solid medium: the eccentricity and Fourier indices.

PubMed

Gil de Prado, Elena; Rivas, Eva-María; de Silóniz, María-Isabel; Diezma, Belén; Barreiro, Pilar; Peinado, José M

2014-11-01

The colony shape of four yeast species growing on agar medium was measured for 116 days by image analysis. Initially, all the colonies are circular, with regular edges. The loss of circularity can be quantitatively estimated by the eccentricity index, Ei , calculated as the ratio between their orthogonal vertical and horizontal diameters. Ei can increase from 1 (complete circularity) to a maximum of 1.17-1.30, depending on the species. One colony inhibits its neighbour only when it has reached a threshold area. Then, Ei of the inhibited colony increases proportionally to the area of the inhibitory colony. The initial distance between colonies affects those threshold values but not the proportionality, Ei /area; this inhibition affects the shape but not the total surface of the colony. The appearance of irregularities in the edges is associated, in all the species, not with age but with nutrient exhaustion. The edge irregularity can be quantified by the Fourier index, Fi , calculated by the minimum number of Fourier coefficients that are needed to describe the colony contour with 99% fitness. An ad hoc function has been developed in Matlab v. 7.0 to automate the computation of the Fourier coefficients. In young colonies, Fi has a value between 2 (circumference) and 3 (ellipse). These values are maintained in mature colonies of Debaryomyces, but can reach values up to 14 in Saccharomyces. All the species studied showed the inhibition of growth in facing colony edges, but only three species showed edge irregularities associated with substrate exhaustion. Copyright © 2014 John Wiley & Sons, Ltd.

Morphology, ultrastructure, and chemical compounds of the osmeterium of Heraclides thoas (Lepidoptera: Papilionidae).

PubMed

Martínez, Luis Carlos; Plata-Rueda, Angelica; da Silva Neves, Guilherme; Cossolin, Jamile Fernanda; Dos Santos, Marcelo Henrique; Zanuncio, José Cola; Serrão, José Eduardo

2018-05-11

The osmeterium, found in papilionoid larvae, is an eversible organ with an exocrine gland that produces substances in response to the mechanical disturbances caused by natural enemies. The anatomy, histology and ultrastructure of the osmeterium, and the chemical composition of its secretion in Heraclides thoas (Lepidoptera: Papilionidae) were studied. Heraclides thoas larvae have a Y-shaped osmeterium in the thorax. The surface of the osmeterium has a rough cuticle lining cells with papillae and irregular folds, whereas the cells that limited the gland pores are irregular, folded, and devoid of papillae. Two types of cells are found: (i) cuticular epidermal cells on the surface of the tubular arms of the osmeterium and (ii) secretory cells of the ellipsoid gland within the region of the glandular pore. Cuticular epidermal cells show a thick cuticle, with several layers divided into epicuticle and lamellar endocuticle. Secretory cells are polygonal, with extensive folds in the basal plasma membrane that formed extracellular channels. The cytoplasm has mitochondria, ribosomes, and numerous vacuoles, whereas the nucleus is irregular in shape with decondensed chromatin. The chemical composition of the osmeterial secretion comprised (Z)-α-bisabolene (25.4%), α-bisabol (20.6%), β-bisabolene (13.1%), (E)-α-bisabolene 8%), β-pinene (9.91%), longipinene epoxide (8.92%), (Z)-β-farnesene (6.96%), β-caryophyllene (2.05%), farnesol (1.86%), linalyl propionate (1.86%), and 1-octyn-4-ol (1.07%). The morphological features suggest that the cuticular epidermal cells play a major role in the maintenance and protection of the osmeterium, whereas secretory cells are responsible for production of osmeterial secretions.

Correlation structures in short-term variabilities of stock indices and exchange rates

NASA Astrophysics Data System (ADS)

Nakamura, Tomomichi; Small, Michael

2007-09-01

Financial data usually show irregular fluctuations and some trends. We investigate whether there are correlation structures in short-term variabilities (irregular fluctuations) among financial data from the viewpoint of deterministic dynamical systems. Our method is based on the small-shuffle surrogate method. The data we use are daily closing price of Standard & Poor's 500 and the volume, and daily foreign exchange rates, Euro/US Dollar (USD), British Pound/USD and Japanese Yen/USD. We found that these data are not independent.

Phonetically Irregular Word Pronunciation and Cortical Thickness in the Adult Brain

PubMed Central

Blackmon, Karen; Barr, William B.; Kuzniecky, Ruben; DuBois, Jonathan; Carlson, Chad; Quinn, Brian T.; Blumberg, Mark; Halgren, Eric; Hagler, Donald J.; Mikhly, Mark; Devinsky, Orrin; McDonald, Carrie R.; Dale, Anders M.; Thesen, Thomas

2010-01-01

Accurate pronunciation of phonetically irregular words (exception words) requires prior exposure to unique relationships between orthographic and phonemic features. Whether such word knowledge is accompanied by structural variation in areas associated with orthographic-to-phonemic transformations has not been investigated. We used high resolution MRI to determine whether performance on a visual word-reading test composed of phonetically irregular words, the Wechsler Test of Adult Reading (WTAR), is associated with regional variations in cortical structure. A sample of 60 right-handed, neurologically intact individuals were administered the WTAR and underwent 3T volumetric MRI. Using quantitative, surface-based image analysis, cortical thickness was estimated at each vertex on the cortical mantle and correlated with WTAR scores while controlling for age. Higher scores on the WTAR were associated with thicker cortex in bilateral anterior superior temporal gyrus, bilateral angular gyrus/posterior superior temporal gyrus, and left hemisphere intraparietal sulcus. Higher scores were also associated with thinner cortex in left hemisphere posterior fusiform gyrus and central sulcus, bilateral inferior frontal gyrus, and right hemisphere lingual gyrus and supramarginal gyrus. These results suggest that the ability to correctly pronounce phonetically irregular words is associated with structural variations in cortical areas that are commonly activated in functional neuroimaging studies of word reading, including areas associated with grapheme-to–phonemic conversion. PMID:20302944

Solar granulation and statistical crystallography: A modeling approach using size-shape relations

NASA Technical Reports Server (NTRS)

Noever, D. A.

1994-01-01

The irregular polygonal pattern of solar granulation is analyzed for size-shape relations using statistical crystallography. In contrast to previous work which has assumed perfectly hexagonal patterns for granulation, more realistic accounting of cell (granule) shapes reveals a broader basis for quantitative analysis. Several features emerge as noteworthy: (1) a linear correlation between number of cell-sides and neighboring shapes (called Aboav-Weaire's law); (2) a linear correlation between both average cell area and perimeter and the number of cell-sides (called Lewis's law and a perimeter law, respectively) and (3) a linear correlation between cell area and squared perimeter (called convolution index). This statistical picture of granulation is consistent with a finding of no correlation in cell shapes beyond nearest neighbors. A comparative calculation between existing model predictions taken from luminosity data and the present analysis shows substantial agreements for cell-size distributions. A model for understanding grain lifetimes is proposed which links convective times to cell shape using crystallographic results.

Effects of an irregular bedtime schedule on sleep quality, daytime sleepiness, and fatigue among university students in Taiwan.

PubMed

Kang, Jiunn-Horng; Chen, Shih-Ching

2009-07-19

An irregular bedtime schedule is a prevalent problem in young adults, and could be a factor detrimentally affecting sleep quality. The goal of the present study was to explore the association between an irregular bedtime schedule and sleep quality, daytime sleepiness, and fatigue among undergraduate students in Taiwan. A total of 160 students underwent a semi-structured interview and completed a survey comprising 4 parts: Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), Fatigue Severity Scale (FSS), and a rating of irregular bedtime frequency. Participants were grouped into 3 groups in terms of irregular bedtime frequency: low, intermediate, or high according to their 2-week sleep log. To screen for psychological disorders or distress that may have affected responses on the sleep assessment measures, the Chinese health questionnaire-12 (CHQ-12) was also administered. We found an increase in bedtime schedule irregularity to be significantly associated with a decrease in average sleep time per day (Spearman r = -0.22, p = 0.05). Multivariate regression analysis revealed that irregular bedtime frequency and average sleep time per day were correlated with PSQI scores, but not with ESS or FSS scores. A significant positive correlation between irregular bedtime frequency and PSQI scores was evident in the intermediate (partial r = 0.18, p = 0.02) and high (partial r = 0.15, p = 0.05) frequency groups as compared to low frequency group. The results of our study suggest a high prevalence of both an irregular bedtime schedule and insufficient sleep among university students in Taiwan. Students with an irregular bedtime schedule may experience poor sleep quality. We suggest further research that explores the mechanisms involved in an irregular bedtime schedule and the effectiveness of interventions for improving this condition.

New Opportunities for Remote Sensing Ionospheric Irregularities by Fitting Scintillation Spectra

NASA Astrophysics Data System (ADS)

Carrano, C. S.; Rino, C. L.; Groves, K. M.

2017-12-01

In a recent paper, we presented a phase screen theory for the spectrum of intensity scintillations when the refractive index irregularities follow a two-component power law [Carrano and Rino, DOI: 10.1002/2015RS005903]. More recently we have investigated the inverse problem, whereby phase screen parameters are inferred from scintillation time series. This is accomplished by fitting the spectrum of intensity fluctuations with a parametrized theoretical model using Maximum Likelihood (ML) methods. The Markov-Chain Monte-Carlo technique provides a-posteriori errors and confidence intervals. The Akaike Information Criterion (AIC) provides justification for the use of one- or two-component irregularity models. We refer to this fitting as Irregularity Parameter Estimation (IPE) since it provides a statistical description of the irregularities from the scintillations they produce. In this talk, we explore some new opportunities for remote sensing ionospheric irregularities afforded by IPE. Statistical characterization of irregularities and the plasma bubbles in which they are embedded provides insight into the development of the underlying instability. In a companion paper by Rino et al., IPE is used to interpret scintillation due to simulated EPB structure. IPE can be used to reconcile multi-frequency scintillation observations and to construct high fidelity scintillation simulation tools. In space-to-ground propagation scenarios, for which an estimate of the distance to the scattering region is available a-priori, IPE enables retrieval of zonal irregularity drift. In radio occultation scenarios, the distance to the irregularities is generally unknown but IPE enables retrieval of Fresnel frequency. A geometric model for the effective scan velocity maps Fresnel frequency to Fresnel scale, yielding the distance to the irregularities. We demonstrate this approach by geolocating irregularities observed by the CORISS instrument onboard the C/NOFS satellite.

Global Distribution of Density Irregularities in the Equatorial Ionosphere

NASA Technical Reports Server (NTRS)

Kil, Hyosub; Heelis, R. A.

1998-01-01

We analyzed measurements of ion number density made by the retarding potential analyzer aboard the Atmosphere Explorer-E (AE-E) satellite, which was in an approximately circular orbit at an altitude near 300 km in 1977 and later at an altitude near 400 km. Large-scale (greater than 60 km) density measurements in the high-altitude regions show large depletions of bubble-like structures which are confined to narrow local time longitude, and magnetic latitude ranges, while those in the low-altitude regions show relatively small depletions which are broadly distributed,in space. For this reason we considered the altitude regions below 300 km and above 350 km and investigated the global distribution of irregularities using the rms deviation delta N/N over a path length of 18 km as an indicator of overall irregularity intensity. Seasonal variations of irregularity occurrence probability are significant in the Pacific regions, while the occurrence probability is always high in die Atlantic-African regions and is always low in die Indian regions. We find that the high occurrence probability in the Pacific regions is associated with isolated bubble structures, while that near 0 deg longitude is produced by large depictions with bubble structures which are superimposed on a large-scale wave-like background. Considerations of longitude variations due to seeding mechanisms and due to F region winds and drifts are necessary to adequately explain the observations at low and high altitudes. Seeding effects are most obvious near 0 deg longitude, while the most easily observed effect of the F region is the suppression of irregularity growth by interhemispheric neutral winds.

Analysis of incidence of keratoconus in relatives of patients who underwent corneal transplant due to advanced keratoconus using the Orbscan II topographic graphs

NASA Astrophysics Data System (ADS)

López Olazagasti, Estela; Hernández y del Callejo, César E.; Ibarra-Galitzia, Jorge; Ramírez-Zavaleta, Gustavo; Tepichín, Eduardo

2011-10-01

Keratoconus is a corneal disease in which the cornea assumes a conical shape due to an irregular alteration of the internal structure of the corneal tissue and sometimes is progressive, especially in young people. Anatomically, the main signs of keratoconus are thinning of the cornea in its central or paracentral region, usually accompanied by an increase in this part of a high irregular astigmatism, with a consequent loss of vision. Its diagnosis requires a thorough study including the family history, a complete ophthalmologic examination and imaging studies. This diagnosis allows classifying the type of keratoconus, which allow determining options of management, with what it is possible to establish a visual prognosis of each eye. One of the indicators that help in the diagnosis of keratoconus is an inherited familiar propensity. The literature reports an incidence of keratoconus of 11%1 in first-degree relatives of patients with keratoconus. Results suggest an ethnic dependence, which implies that the knowledge of the tendency of keratoconus in the Mexican population is important. In this work, we present the preliminary results of the study realized to a group of relatives of patients who underwent corneal transplant by advanced keratoconus using Orbscan II topographic diagnosis, to determine the predisposition to Keratoconus in this group.e

A multiscale analysis of coral reef topographic complexity using lidar-derived bathymetry

USGS Publications Warehouse

Zawada, D.G.; Brock, J.C.

2009-01-01

Coral reefs represent one of the most irregular substrates in the marine environment. This roughness or topographic complexity is an important structural characteristic of reef habitats that affects a number of ecological and environmental attributes, including species diversity and water circulation. Little is known about the range of topographic complexity exhibited within a reef or between different reef systems. The objective of this study was to quantify topographic complexity for a 5-km x 5-km reefscape along the northern Florida Keys reef tract, over spatial scales ranging from meters to hundreds of meters. The underlying dataset was a 1-m spatial resolution, digital elevation model constructed from lidar measurements. Topographic complexity was quantified using a fractal algorithm, which provided a multi-scale characterization of reef roughness. The computed fractal dimensions (D) are a measure of substrate irregularity and are bounded between values of 2 and 3. Spatial patterns in D were positively correlated with known reef zonation in the area. Landward regions of the study site contain relatively smooth (D ??? 2.35) flat-topped patch reefs, which give way to rougher (D ??? 2.5), deep, knoll-shaped patch reefs. The seaward boundary contains a mixture of substrate features, including discontinuous shelf-edge reefs, and exhibits a corresponding range of roughness values (2.28 ??? D ??? 2.61). ?? 2009 Coastal Education and Research Foundation.

Irregular Wave Energy Extraction Analysis for a Slider Crank WEC Power Take-Off System

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

Sang, Yuanrui; Karayaka, H. Bora; Yan, Yanjun

2015-09-02

Slider crank Wave Energy Converter (WEC) is a novel energy conversion device. It converts wave energy into electricity at a relatively high efficiency, and it features a simple structure. Past analysis on this WEC has been done under regular sinusoidal wave conditions, and a suboptimal energy could be achieved. This paper presents the analysis of the system under irregular wave conditions; a time-domain hydrodynamics model is adopted and the control methodology is modified to better serve the irregular wave conditions. Results from the simulations show that the performance of the system under irregular wave conditions is different from that undermore » regular sinusoidal wave conditions, but still a reasonable amount of energy can be extracted.« less

Application of Wuhan Ionospheric Oblique Backscattering Sounding System (WIOBSS) for the investigation of midlatitude ionospheric irregularities

NASA Astrophysics Data System (ADS)

Wang, Jin; Zhou, Xiaoming; Qiao, Lei; Gong, Wanlin

2018-03-01

An upgrade of Wuhan Ionospheric Backscattering Sounding System (WIOBSS) was developed in 2015. Based on the Universal Serial Bus (USB), and a high performance FPGA, the newly designed WIOBSS has a completely digital structure, which makes it portable and flexible. Two identical WIOBSSs, which were situated at Mile (24.31°N, 103.39°E) and Puer (22.74°N, 101.05°E) respectively, were used to investigate the ionospheric irregularities. The comparisons of group distance, Doppler shift and width between Mile-Puer and Puer-Mile VHF ionospheric propagation paths indicate that the reciprocity of the irregularities is satisfied at midlatitude region. The WIOBSS is robust in the detection of ionospheric irregularities.

Internal structure of shock waves in disparate mass mixtures

NASA Technical Reports Server (NTRS)

Chung, Chan-Hong; De Witt, Kenneth J.; Jeng, Duen-Ren; Penko, Paul F.

1992-01-01

The detailed flow structure of a normal shock wave for a gas mixture is investigated using the direct-simulation Monte Carlo method. A variable diameter hard-sphere (VDHS) model is employed to investigate the effect of different viscosity temperature exponents (VTE) for each species in a gas mixture. Special attention is paid to the irregular behavior in the density profiles which was previously observed in a helium-xenon experiment. It is shown that the VTE can have substantial effects in the prediction of the structure of shock waves. The variable hard-sphere model of Bird shows good agreement, but with some limitations, with the experimental data if a common VTE is chosen properly for each case. The VDHS model shows better agreement with the experimental data without adjusting the VTE. The irregular behavior of the light-gas component in shock waves of disparate mass mixtures is observed not only in the density profile, but also in the parallel temperature profile. The strength of the shock wave, the type of molecular interactions, and the mole fraction of heavy species have substantial effects on the existence and structure of the irregularities.

Failure Analysis in Platelet Molded Composite Systems

NASA Astrophysics Data System (ADS)

Kravchenko, Sergii G.

Long-fiber discontinuous composite systems in the form of chopped prepreg tapes provide an advanced, structural grade, molding compound allowing for fabrication of complex three-dimensional components. Understanding of process-structure-property relationship is essential for application of prerpeg platelet molded components, especially because of their possible irregular disordered heterogeneous morphology. Herein, a structure-property relationship was analyzed in the composite systems of many platelets. Regular and irregular morphologies were considered. Platelet-based systems with more ordered morphology possess superior mechanical performance. While regular morphologies allow for a careful inspection of failure mechanisms derived from the morphological characteristics, irregular morphologies are representative of the composite architectures resulting from uncontrolled deposition and molding with chopped prerpegs. Progressive failure analysis (PFA) was used to study the damaged deformation up to ultimate failure in a platelet-based composite system. Computational damage mechanics approaches were utilized to conduct the PFA. The developed computational models granted understanding of how the composite structure details, meaning the platelet geometry and system morphology (geometrical arrangement and orientation distribution of platelets), define the effective mechanical properties of a platelet-molded composite system, its stiffness, strength and variability in properties.

Fingered bola body, bola with same, and methods of use

NASA Technical Reports Server (NTRS)

Dzenitis, John M. (Inventor); Billica, Linda W. (Inventor)

1994-01-01

The present invention discloses bola bodies, bolas, and a snaring method which makes use such devices. A bola body, according to the present invention, is nonspherical or irregular in shape rather than a smooth sphere or ovoid body. One or more fingers extends from the bola body. These fingers may be relatively straight or they may have crooked or bent portions to enhance entanglement with a bola line or lines or with each other. Two or more of such fingers may be used and may be regularly or irregularly spaced apart on a bola body. A bola with such bodies includes lines which are connected to the other bodies. In one particular embodiment of a bola body, according to the present invention, the body has an irregular shape with a bottom rectangular portion and a top pyramid portion forming a nose. A plurality of fingers is extended from the pyramidal top portion with one finger extended up and away from each of four corners of the top portion. Such a bola body tends to be initially oriented with its nose and fingers against an object being snared since the body is pulled nose first when a bola line is secured at the tip of the pyramidal portion of the bola body. With such a bola, an unwrapping bola body can slip around a target member so that two of the rod-shaped fingers catch a bola line and guide it into an area or crook between the fingers and a side of the top pyramidal portion of the bola body. Tension on the bola line maintains the line in the crook and tends to press the fingers against the unwrapped target member to stabilize the wrapping of the line about the target member. With such a bola, it is difficult for two or more lines unwrapping in different directions to move past one another without being forced together by line tension. Also, the fingers of such bola bodies may hook and hold each other. The fingers may also hook or entangle some object on or portion of the target member. A probable known target member has known dimensions and shapes so that the bola may be sized and configured to reliably snare such a known target. The bolas can be optimally sized, fashioned, and configured to contact and hold a probable target of known size, dimension, and shape.

Cell-substrate impedance fluctuations of single amoeboid cells encode cell-shape and adhesion dynamics

NASA Astrophysics Data System (ADS)

Leonhardt, Helmar; Gerhardt, Matthias; Höppner, Nadine; Krüger, Kirsten; Tarantola, Marco; Beta, Carsten

2016-01-01

We show systematic electrical impedance measurements of single motile cells on microelectrodes. Wild-type cells and mutant strains were studied that differ in their cell-substrate adhesion strength. We recorded the projected cell area by time-lapse microscopy and observed irregular oscillations of the cell shape. These oscillations were correlated with long-term variations in the impedance signal. Superposed to these long-term trends, we observed fluctuations in the impedance signal. Their magnitude clearly correlated with the adhesion strength, suggesting that strongly adherent cells display more dynamic cell-substrate interactions.

Simple ectopic kidney in three dogs.

PubMed

Choi, Jiyoung; Lee, Heechun; Lee, Youngwon; Choi, Hojung

2012-10-01

Simple ectopic kidney was diagnosed in three dogs by means of radiography and ultrasonography. A 2-year-old castrated male Schnauzer, a 13-year-old female Schnauzer and a 9-year-old male Jindo were referred with vomiting, hematuria and ocular discharge, respectively. In all three dogs, oval-shaped masses with soft tissue density were observed in the mid to caudal abdomen bilaterally or unilaterally, and kidney silhouettes were not identified at the proper anatomic places on abdominal radiographs. Ultrasonography confirmed the masses were malpositioned kidney. The ectopic kidneys had relatively small size, irregular shape and short ureter but showed normal function on excretory urography.

Influence of substrate micropatterning on biofilm growth

NASA Astrophysics Data System (ADS)

Koehler, Stephan; Li, Yiwei; Liu, Bi-Feng Liu; Weitz, David

2015-11-01

We culture triple reporter Bacillus Subtilis biofilm on micropatterned agar substrates. We track the biofilm development in terms of size, thickness, shape, and phenotype expression. For a tiling composed of elevated rectangles, we observe the biofilm develops an oval shape or triangular shape depending on the rectangle's aspect ratio and orientation. The motile cells are primarily located in the valleys between the rectangles and the matrix producing cells are mostly located on the rectangles. Wrinkles form at the edges of the elevated surfaces, and upon merging form channels centered on the elevated surface. After a few days, the spore-forming cells appear at the periphery. Since biofilms in nature grow on irregular surfaces, our work may provide insight into the complex patterns observed.

Population Structure of Pythium irregulare, P. ultimum, and P. sylvaticum in Forest Nursery Soils of Oregon and Washington.

PubMed

Weiland, Jerry E; Garrido, Patricia; Kamvar, Zhian N; Espíndola, Andrés S; Marek, Stephen M; Grünwald, Niklaus J; Garzón, Carla D

2015-05-01

Pythium species are important soilborne pathogens occurring in the forest nursery industry of the Pacific Northwest. However, little is known about their genetic diversity or population structure and it is suspected that isolates are moved among forest nurseries on seedling stock and shared field equipment. In order to address these concerns, a total of 115 isolates of three Pythium species (P. irregulare, P. sylvaticum, and P. ultimum) were examined at three forest nurseries using simple sequence repeat (SSR) and amplified fragment length polymorphism (AFLP) markers. Analyses revealed distinct patterns of intraspecific variation for the three species. P. sylvaticum exhibited the most diversity, followed by P. irregulare, while substantial clonality was found in P. ultimum. For both P. irregulare and P. sylvaticum, but not P. ultimum, there was evidence for significant variation among nurseries. However, all three species also exhibited at least two distinct lineages not associated with the nursery of origin. Finally, evidence was found that certain lineages and clonal genotypes, including fungicide-resistant isolates, are shared among nurseries, indicating that pathogen movement has occurred.

Modeling and Performance Improvement of the Constant Power Regulator Systems in Variable Displacement Axial Piston Pump

PubMed Central

Park, Sung Hwan; Lee, Ji Min; Kim, Jong Shik

2013-01-01

An irregular performance of a mechanical-type constant power regulator is considered. In order to find the cause of an irregular discharge flow at the cut-off pressure area, modeling and numerical simulations are performed to observe dynamic behavior of internal parts of the constant power regulator system for a swashplate-type axial piston pump. The commercial numerical simulation software AMESim is applied to model the mechanical-type regulator with hydraulic pump and simulate the performance of it. The validity of the simulation model of the constant power regulator system is verified by comparing simulation results with experiments. In order to find the cause of the irregular performance of the mechanical-type constant power regulator system, the behavior of main components such as the spool, sleeve, and counterbalance piston is investigated using computer simulation. The shape modification of the counterbalance piston is proposed to improve the undesirable performance of the mechanical-type constant power regulator. The performance improvement is verified by computer simulation using AMESim software. PMID:24282389

Textural defect detect using a revised ant colony clustering algorithm

NASA Astrophysics Data System (ADS)

Zou, Chao; Xiao, Li; Wang, Bingwen

2007-11-01

We propose a totally novel method based on a revised ant colony clustering algorithm (ACCA) to explore the topic of textural defect detection. In this algorithm, our efforts are mainly made on the definition of local irregularity measurement and the implementation of the revised ACCA. The local irregular measurement defined evaluates the local textural inconsistency of each pixel against their mini-environment. In our revised ACCA, the behaviors of each ant are divided into two steps: release pheromone and act. The quantity of pheromone released is proportional to the irregularity measurement; the actions of the ants to act next are chosen independently of each other in a stochastic way according to some evaluated heuristic knowledge. The independency of ants implies the inherent parallel computation architecture of this algorithm. We apply the proposed method in some typical textural images with defects. From the series of pheromone distribution map (PDM), it can be clearly seen that the pheromone distribution approaches the textual defects gradually. By some post-processing, the final distribution of pheromone can demonstrate the shape and area of the defects well.

Quadtree of TIN: a new algorithm of dynamic LOD

NASA Astrophysics Data System (ADS)

Zhang, Junfeng; Fei, Lifan; Chen, Zhen

2009-10-01

Currently, Real-time visualization of large-scale digital elevation model mainly employs the regular structure of GRID based on quadtree and triangle simplification methods based on irregular triangulated network (TIN). TIN is a refined means to express the terrain surface in the computer science, compared with GRID. However, the data structure of TIN model is complex, and is difficult to realize view-dependence representation of level of detail (LOD) quickly. GRID is a simple method to realize the LOD of terrain, but contains more triangle count. A new algorithm, which takes full advantage of the two methods' merit, is presented in this paper. This algorithm combines TIN with quadtree structure to realize the view-dependence LOD controlling over the irregular sampling point sets, and holds the details through the distance of viewpoint and the geometric error of terrain. Experiments indicate that this approach can generate an efficient quadtree triangulation hierarchy over any irregular sampling point sets and achieve dynamic and visual multi-resolution performance of large-scale terrain at real-time.

Obtaining source current density related to irregularly structured electromagnetic target field inside human body using hybrid inverse/FDTD method.

PubMed

Han, Jijun; Yang, Deqiang; Sun, Houjun; Xin, Sherman Xuegang

2017-01-01

Inverse method is inherently suitable for calculating the distribution of source current density related with an irregularly structured electromagnetic target field. However, the present form of inverse method cannot calculate complex field-tissue interactions. A novel hybrid inverse/finite-difference time domain (FDTD) method that can calculate the complex field-tissue interactions for the inverse design of source current density related with an irregularly structured electromagnetic target field is proposed. A Huygens' equivalent surface is established as a bridge to combine the inverse and FDTD method. Distribution of the radiofrequency (RF) magnetic field on the Huygens' equivalent surface is obtained using the FDTD method by considering the complex field-tissue interactions within the human body model. The obtained magnetic field distributed on the Huygens' equivalent surface is regarded as the next target. The current density on the designated source surface is derived using the inverse method. The homogeneity of target magnetic field and specific energy absorption rate are calculated to verify the proposed method.

Can we apply the MRI BI-RADS lexicon morphology descriptors on contrast-enhanced spectral mammography?

PubMed Central

Kamal, Rasha M; Helal, Maha H; Haggag, Marwa A; Nada, Omniya M; Farahat, Iman G; Alieldin, Nelly H

2016-01-01

Objective: To assess the feasibility of using the MRI breast imaging reporting and data system (BI-RADS) lexicon morphology descriptors to characterize enhancing breast lesions identified on contrast-enhanced spectral mammography (CESM). Methods: The study is a retrospective analysis of the morphology descriptors of 261 enhancing breast lesions identified on CESM in 239 patients. We presented the morphological categorization of the included lesions into focus, mass and non-mass. Further classifications included (1) the multiplicity for “focus” category, (2) the shape, margin and internal enhancement for “mass” category and (3) the distribution and internal enhancement for “non-mass” category. Each morphology descriptor was evaluated individually (irrespective of all other descriptors) by calculating its sensitivity, specificity, positive-predictive value (PPV) and negative-predictive value (NPV) and likelihood ratios (LRs). Results: The study included 68/261 (26.1%) benign lesions and 193/261 (73.9%) malignant lesions. Intensely enhancing foci, whether single (7/12, 58.3%) or multiple (2/12, 16.7%), were malignant. Descriptors of “irregular”-shape (PPV: 92.4%) and “non-circumscribed” margin (odds ratio: 55.2, LR positive: 4.77; p-value: <0.001) were more compatible with malignancy. Internal mass enhancement patterns showed a very low specificity (58.0%) and NPV (40.0%). Non-mass enhancement (NME) was detected in 81/261 lesions. Asymmetrical NME in 81% (n = 52/81) lesions was malignant lesions and internal enhancement patterns indicative of malignancy were the heterogeneous and clumped ones. Conclusion: We can apply the MRI morphology descriptors to characterize lesions on CESM, but with few expectations. In many situations, irregular-shaped, non-circumscribed masses and NME with focal, ductal or segmental distribution and heterogeneous or clumped enhancement are the most suggestive descriptors of malignant pathologies. Advances in knowledge: (1) The MRI BI-RADS lexicon morphology descriptors can be applied in the characterization of enhancing lesions on CESM with a few exceptions. (2) Multiple bilateral intensely enhancing foci should not be included under the normal background parenchymal enhancement unless they are proved to be benign by biopsy. (3) Mass lesion features that indicated malignancy were irregular-shaped, spiculated and irregular margins and heterogeneous internal enhancement patterns. The rim enhancement pattern should not be considered as a descriptor of malignant lesions unless CESM is coupled with an ultrasound examination. PMID:27327403

Large effect of membrane tension on the fluid-solid phase transitions of two-component phosphatidylcholine vesicles.

PubMed

Chen, Dong; Santore, Maria M

2014-01-07

Model phospholipid membranes and vesicles have long provided insight into the nature of confined materials and membranes while also providing a platform for drug delivery. The rich thermodynamic behavior and interesting domain shapes in these membranes have previously been mapped in extensive studies that vary temperature and composition; however, the thermodynamic impact of tension on bilayers has been restricted to recent reports of subtly reduced fluid-fluid transition temperatures. In two-component phosphatidylcholine unilamellar vesicles [1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)/1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC)], we report a dramatic influence of tension on the fluid-solid transition and resulting phases: At fixed composition, systematic variations in tension produce differently shaped solid domains (striped or irregular hexagons), shift fluid-solid transition temperatures, and produce a triple-point-like intersection of coexistence curves at elevated tensions, about 3 mN/m for 30% DOPC/70% DPPC. Tension therefore represents a potential switch of microstructure in responsive engineered materials; it is an important morphology-determining variable in confined systems, and, in biological membranes, it may provide a means to regulate dynamic structure.

A rapid biosynthesis route for the preparation of gold nanoparticles by aqueous extract of cypress leaves at room temperature

NASA Astrophysics Data System (ADS)

Noruzi, Masumeh; Zare, Davood; Davoodi, Daryoush

In the present study, green synthesis of gold nanoparticles was reported using the aqueous extract of cypress leaves. The reduction of gold salt with the extract of cypress leaves resulted in the formation of gold nanoparticles. Effects of extract concentration and extract pH were investigated on the size of the nanoparticles. It was found that the average particle size of synthesized gold nanoparticles depends strongly on extract concentration and extract pH. FT-IR spectroscopy showed that bioorganic capping molecules were bound to the surface of particles. X-ray techniques confirmed the formation of gold nanoparticles and their crystalline structure. The inductively coupled plasma atomic emission spectroscopy analysis displayed that the reaction progress is higher than 90% at room temperature. Gold nanoparticles were mostly spherical in shape along with some irregular shapes. Cypress is an evergreen plant and its leaves are easily available in all four seasons. Also, the rate of the reaction was high and it was completed in only 10 min. For these reasons, this method is cost-effective and environmentally friendly. Thus, it can be used in the synthesis of gold nanoparticles instead of chemical methods and other biosynthesis approaches.

Source fields reconstruction with 3D mapping by means of the virtual acoustic volume concept

NASA Astrophysics Data System (ADS)

Forget, S.; Totaro, N.; Guyader, J. L.; Schaeffer, M.

2016-10-01

This paper presents the theoretical framework of the virtual acoustic volume concept and two related inverse Patch Transfer Functions (iPTF) identification methods (called u-iPTF and m-iPTF depending on the chosen boundary conditions for the virtual volume). They are based on the application of Green's identity on an arbitrary closed virtual volume defined around the source. The reconstruction of sound source fields combines discrete acoustic measurements performed at accessible positions around the source with the modal behavior of the chosen virtual acoustic volume. The mode shapes of the virtual volume can be computed by a Finite Element solver to handle the geometrical complexity of the source. As a result, it is possible to identify all the acoustic source fields at the real surface of an irregularly shaped structure and irrespective of its acoustic environment. The m-iPTF method is introduced for the first time in this paper. Conversely to the already published u-iPTF method, the m-iPTF method needs only acoustic pressure and avoids particle velocity measurements. This paper is focused on its validation, both with numerical computations and by experiments on a baffled oil pan.

Earth Observations taken by Expedition 38 Crewmember

NASA Image and Video Library

2014-02-14

ISS038-E-047388 (14 Feb. 2014) --- As the International Space Station passed over the deserts of central Iran, including Kavir, one of the Expedition 38 crew members used a digital camera equipped with a 200mm lens to record this image featuring an unusual pattern of numerous parallel lines and sweeping curves. The lack of soil and vegetation allows the geological structure of the rocks to appear quite clearly. According to geologists, the patterns result from the gentle folding of numerous, thin, light and dark layers of rock. Later erosion by wind and water, say the scientists, cut a flat surface across the folds, not only exposing hundreds of layers but also showing the shapes of the folds. The dark water of a lake (image center) occupies a depression in a more easily eroded, S-shaped layer of rock. The irregular light-toned patch just left of the lake is a sand sheet thin enough to allow the underlying rock layers to be detected. A small river snakes across the bottom of the image. In this desert landscape there are no fields or roads to give a sense of scale. In fact, the image width represents a distance of 65 kilometers.

Electronic structure and bonding interactions in Ba1- x Sr x Zr0.1Ti0.9O3 ceramics

NASA Astrophysics Data System (ADS)

Mangaiyarkkarasi, Jegannathan; Sasikumar, Subramanian; Saravanan, Olai Vasu; Saravanan, Ramachandran

2017-06-01

An investigation on the precise electronic structure and bonding interactions has been carried out on Ba1- x Sr x Zr0.1Ti0.9O3 (short for BSZT, x = 0, 0.05, 0.07 and 0.14) ceramic systems prepared via high-temperature solid state reaction technique. The influence of Sr doping on the BSZT structure has been examined by characterizing the prepared samples using PXRD, UV-visible spectrophotometry, SEM and EDS. Powder profile refinement of X-ray data confirms that all the synthesized samples have been crystallized in cubic perovskite structure with single phase. Charge density distribution of the BSZT systems has been completely analyzed by the maximum entropy method (MEM). Co-substitution of Sr at the Ba site and Zr at the Ti site into the BaTiO3 structure presents the ionic nature between Ba and O ions and the covalent nature between Ti and O ions, revealed from MEM calculations. Optical band gap values have been evaluated from UV-visible absorption spectra. Particles with irregular shapes and well defined grain boundaries are clearly visualized from SEM images. The phase purity of the prepared samples is further confirmed by EDS qualitative spectral analysis.

The gravitational potential of a homogeneous polyhedron or don't cut corners

NASA Technical Reports Server (NTRS)

Werner, Robert A.

1994-01-01

A polyhedron can model irregularly shaped objects such as asteroids, comet nuclei, and small planetary satellites. With minor effort, such a model can incorporate important surface features such as large craters. Here we develop closed-form expressions for the exterior gravitational potential and acceleration components due to a constant-density polyhedron. An equipotential surface of Phobos is illustrated.

Affirming Irregular Spaces in a School-Wide Curriculum Initiative: A Place for the Animals

ERIC Educational Resources Information Center

Lynch, Julianne; Herbert, Sandra

2015-01-01

School-wide curriculum initiatives are complex fields of activity, held together by a cast of heterogeneous actors who put diverse discourses to work in their everyday efforts to shape their work. This paper draws upon qualitative data collected across an 18-month period in a regional Australian primary school that, since the beginning of 2012,…

Identification and Characterization of Pseudocercospora pyricola Causing Leaf Spots on Aronia melanocarpa

PubMed Central

Park, Sung-Hee; Choi, In-Young; Seo, Kyoung-Won; Kim, Jin-Ho; Galea, Victor

2017-01-01

Leaf spot disease on black chokeberry (Aronia melanocarpa) was observed at several locations in Korea during 2014–2015. Leaf spots were distinct, scattered over the leaf surface and along the leaf border, subcircular to irregular and brown surrounded by a distinct dark color, and were expanded and coalesced into irregularly shaped lesions. Severely infected leaves became dry and fell off eventually. The causative agent was identified as Pseudocercospora pyricola. Morphological observations and phylogenetic analyses of multiple genes, including internal transcribed spacer, translation elongation factor 1-alpha, actin, and the large subunit ribosomal DNA were conducted. The pathogenicity test was conducted twice yielding similar results, fulfilling Koch's postulates. To our knowledge, this is the first report on P. pyricola infection of A. melanocarpa globally. PMID:28435353

The energy components of stacked chromatin layers explain the morphology, dimensions and mechanical properties of metaphase chromosomes

PubMed Central

Daban, Joan-Ramon

2014-01-01

The measurement of the dimensions of metaphase chromosomes in different animal and plant karyotypes prepared in different laboratories indicates that chromatids have a great variety of sizes which are dependent on the amount of DNA that they contain. However, all chromatids are elongated cylinders that have relatively similar shape proportions (length to diameter ratio approx. 13). To explain this geometry, it is considered that chromosomes are self-organizing structures formed by stacked layers of planar chromatin and that the energy of nucleosome–nucleosome interactions between chromatin layers inside the chromatid is approximately 3.6 × 10−20 J per nucleosome, which is the value reported by other authors for internucleosome interactions in chromatin fibres. Nucleosomes in the periphery of the chromatid are in contact with the medium; they cannot fully interact with bulk chromatin within layers and this generates a surface potential that destabilizes the structure. Chromatids are smooth cylinders because this morphology has a lower surface energy than structures having irregular surfaces. The elongated shape of chromatids can be explained if the destabilizing surface potential is higher in the telomeres (approx. 0.16 mJ m−2) than in the lateral surface (approx. 0.012 mJ m−2). The results obtained by other authors in experimental studies of chromosome mechanics have been used to test the proposed supramolecular structure. It is demonstrated quantitatively that internucleosome interactions between chromatin layers can justify the work required for elastic chromosome stretching (approx. 0.1 pJ for large chromosomes). The high amount of work (up to approx. 10 pJ) required for large chromosome extensions is probably absorbed by chromatin layers through a mechanism involving nucleosome unwrapping. PMID:24402918

Observations of pockmark flow structure in Belfast Bay, Maine, Part 1: current-induced mixing

USGS Publications Warehouse

Fandel, Christina L.; Lippmann, Thomas C.; Irish, James D.; Brothers, Laura L.

2017-01-01

Field observations of current profiles and temperature, salinity, and density structure were used to examine vertical mixing within two pockmarks in Belfast Bay, Maine. The first is located in 21 m water depth (sea level to rim), nearly circular in shape with a 45 m rim diameter and 12 m rim-to-bottom relief. The second is located in 25 m water depth, more elongated in shape with an approximately 80 m (36 m) major (minor) axis length at the rim, and 17 m relief. Hourly averaged current profiles were acquired from bottom-mounted acoustic Doppler current profilers deployed on the rim and center of each pockmark over successive 42 h periods in July 2011. Conductivity–temperature–depth casts at the rim and center of each pockmark show warmer, fresher water in the upper water column, evidence of both active and fossil thermocline structure 5–8 m above the rim, and well-mixed water below the rim to the bottom. Vertical velocities show up- and down-welling events that extend into the depths of each pockmark. An observed temperature change at both the rim and center occurs coincident with an overturning event below the rim, and suggests active mixing of the water column into the depths of each pockmark. Vertical profiles of horizontal velocities show depth variation at both the center and rim consistent with turbulent logarithmic current boundary layers, and suggest that form drag may possibly be influencing the local flow regime. While resource limitations prevented observation of the current structure and water properties at a control site, the acquired data suggest that active mixing and overturning within the sampled pockmarks occur under typical benign conditions, and that current flows are influenced by upstream bathymetric irregularities induced by distant pockmarks.

A novel method of the image processing on irregular triangular meshes

NASA Astrophysics Data System (ADS)

Vishnyakov, Sergey; Pekhterev, Vitaliy; Sokolova, Elizaveta

2018-04-01

The paper describes a novel method of the image processing based on irregular triangular meshes implementation. The triangular mesh is adaptive to the image content, least mean square linear approximation is proposed for the basic interpolation within the triangle. It is proposed to use triangular numbers to simplify using of the local (barycentric) coordinates for the further analysis - triangular element of the initial irregular mesh is to be represented through the set of the four equilateral triangles. This allows to use fast and simple pixels indexing in local coordinates, e.g. "for" or "while" loops for access to the pixels. Moreover, representation proposed allows to use discrete cosine transform of the simple "rectangular" symmetric form without additional pixels reordering (as it is used for shape-adaptive DCT forms). Furthermore, this approach leads to the simple form of the wavelet transform on triangular mesh. The results of the method application are presented. It is shown that advantage of the method proposed is a combination of the flexibility of the image-adaptive irregular meshes with the simple form of the pixel indexing in local triangular coordinates and the using of the common forms of the discrete transforms for triangular meshes. Method described is proposed for the image compression, pattern recognition, image quality improvement, image search and indexing. It also may be used as a part of video coding (intra-frame or inter-frame coding, motion detection).

Application of syntactic methods of pattern recognition for data mining and knowledge discovery in medicine

NASA Astrophysics Data System (ADS)

Ogiela, Marek R.; Tadeusiewicz, Ryszard

2000-04-01

This paper presents and discusses possibilities of application of selected algorithms belonging to the group of syntactic methods of patten recognition used to analyze and extract features of shapes and to diagnose morphological lesions seen on selected medical images. This method is particularly useful for specialist morphological analysis of shapes of selected organs of abdominal cavity conducted to diagnose disease symptoms occurring in the main pancreatic ducts, upper segments of ureters and renal pelvis. Analysis of the correct morphology of these organs is possible with the application of the sequential and tree method belonging to the group of syntactic methods of pattern recognition. The objective of this analysis is to support early diagnosis of disease lesions, mainly characteristic for carcinoma and pancreatitis, based on examinations of ERCP images and a diagnosis of morphological lesions in ureters as well as renal pelvis based on an analysis of urograms. In the analysis of ERCP images the main objective is to recognize morphological lesions in pancreas ducts characteristic for carcinoma and chronic pancreatitis, while in the case of kidney radiogram analysis the aim is to diagnose local irregularities of ureter lumen and to examine the morphology of renal pelvis and renal calyxes. Diagnosing the above mentioned lesion has been conducted with the use of syntactic methods of pattern recognition, in particular the languages of description of features of shapes and context-free sequential attributed grammars. These methods allow to recognize and describe in a very efficient way the aforementioned lesions on images obtained as a result of initial image processing of width diagrams of the examined structures. Additionally, in order to support the analysis of the correct structure of renal pelvis a method using the tree grammar for syntactic pattern recognition to define its correct morphological shapes has been presented.

Frog tongue surface microstructures: functional and evolutionary patterns

PubMed Central

Gorb, Stanislav N

2016-01-01

Summary Frogs (Lissamphibia: Anura) use adhesive tongues to capture fast moving, elusive prey. For this, the tongues are moved quickly and adhere instantaneously to various prey surfaces. Recently, the functional morphology of frog tongues was discussed in context of their adhesive performance. It was suggested that the interaction between the tongue surface and the mucus coating is important for generating strong pull-off forces. However, despite the general notions about its importance for a successful contact with the prey, little is known about the surface structure of frog tongues. Previous studies focused almost exclusively on species within the Ranidae and Bufonidae, neglecting the wide diversity of frogs. Here we examined the tongue surface in nine different frog species, comprising eight different taxa, i.e., the Alytidae, Bombinatoridae, Megophryidae, Hylidae, Ceratophryidae, Ranidae, Bufonidae, and Dendrobatidae. In all species examined herein, we found fungiform and filiform papillae on the tongue surface. Further, we observed a high degree of variation among tongues in different frogs. These differences can be seen in the size and shape of the papillae, in the fine-structures on the papillae, as well as in the three-dimensional organization of subsurface tissues. Notably, the fine-structures on the filiform papillae in frogs comprise hair-like protrusions (Megophryidae and Ranidae), microridges (Bufonidae and Dendrobatidae), or can be irregularly shaped or absent as observed in the remaining taxa examined herein. Some of this variation might be related to different degrees of adhesive performance and may point to differences in the spectra of prey items between frog taxa. PMID:27547606

Aggregation in particle rich environments: a textural study of examples from volcanic eruptions, meteorite impacts, and fluidized bed processing

NASA Astrophysics Data System (ADS)

Mueller, Sebastian B.; Kueppers, Ulrich; Huber, Matthew S.; Hess, Kai-Uwe; Poesges, Gisela; Ruthensteiner, Bernhard; Dingwell, Donald B.

2018-04-01

Aggregation is a common process occurring in many diverse particulate gas mixtures (e.g. those derived from explosive volcanic eruptions, meteorite impact events, and fluid bed processing). It results from the collision and sticking of particles suspended in turbulent gas/air. To date, there is no generalized model of the underlying physical processes. Here, we investigate aggregates from 18 natural deposits (16 volcanic deposits and two meteorite impact deposits) as well as aggregates produced experimentally via fluidized bed techniques. All aggregates were analyzed for their size, internal structuring, and constituent particle size distribution. Commonalities and differences between the aggregate types are then used to infer salient features of the aggregation process. Average core to rim ratios of internally structured aggregates (accretionary lapilli) is found to be similar for artificial and volcanic aggregates but up to an order of magnitude different than impact-related aggregates. Rim structures of artificial and volcanic aggregates appear to be physically similar (single, sub-spherical, regularly-shaped rims) whereas impact-related aggregates more often show multiple or irregularly shaped rims. The particle size distributions (PSDs) of all three aggregate types are similar (< 200 μm). This proves that in all three environments, aggregation occurs under broadly similar conditions despite the significant differences in source conditions (particle volume fraction, particle size distribution, particle composition, temperature), residence times, plume conditions (e.g., humidity and temperature), and dynamics of fallout and deposition. Impact-generated and volcanic aggregates share many similarities, and in some cases may be indistinguishable without their stratigraphic context.

Aggregation in particle rich environments: a textural study of examples from volcanic eruptions, meteorite impacts, and fluidized bed processing.

PubMed

Mueller, Sebastian B; Kueppers, Ulrich; Huber, Matthew S; Hess, Kai-Uwe; Poesges, Gisela; Ruthensteiner, Bernhard; Dingwell, Donald B

2018-01-01

Aggregation is a common process occurring in many diverse particulate gas mixtures (e.g. those derived from explosive volcanic eruptions, meteorite impact events, and fluid bed processing). It results from the collision and sticking of particles suspended in turbulent gas/air. To date, there is no generalized model of the underlying physical processes. Here, we investigate aggregates from 18 natural deposits (16 volcanic deposits and two meteorite impact deposits) as well as aggregates produced experimentally via fluidized bed techniques. All aggregates were analyzed for their size, internal structuring, and constituent particle size distribution. Commonalities and differences between the aggregate types are then used to infer salient features of the aggregation process. Average core to rim ratios of internally structured aggregates (accretionary lapilli) is found to be similar for artificial and volcanic aggregates but up to an order of magnitude different than impact-related aggregates. Rim structures of artificial and volcanic aggregates appear to be physically similar (single, sub-spherical, regularly-shaped rims) whereas impact-related aggregates more often show multiple or irregularly shaped rims. The particle size distributions (PSDs) of all three aggregate types are similar (< 200 μm). This proves that in all three environments, aggregation occurs under broadly similar conditions despite the significant differences in source conditions (particle volume fraction, particle size distribution, particle composition, temperature), residence times, plume conditions (e.g., humidity and temperature), and dynamics of fallout and deposition. Impact-generated and volcanic aggregates share many similarities, and in some cases may be indistinguishable without their stratigraphic context.

Multigrid finite element method in stress analysis of three-dimensional elastic bodies of heterogeneous structure

NASA Astrophysics Data System (ADS)

Matveev, A. D.

2016-11-01

To calculate the three-dimensional elastic body of heterogeneous structure under static loading, a method of multigrid finite element is provided, when implemented on the basis of algorithms of finite element method (FEM), using homogeneous and composite threedimensional multigrid finite elements (MFE). Peculiarities and differences of MFE from the currently available finite elements (FE) are to develop composite MFE (without increasing their dimensions), arbitrarily small basic partition of composite solids consisting of single-grid homogeneous FE of the first order can be used, i.e. in fact, to use micro approach in finite element form. These small partitions allow one to take into account in MFE, i.e. in the basic discrete models of composite solids, complex heterogeneous and microscopically inhomogeneous structure, shape, the complex nature of the loading and fixation and describe arbitrarily closely the stress and stain state by the equations of three-dimensional elastic theory without any additional simplifying hypotheses. When building the m grid FE, m of nested grids is used. The fine grid is generated by a basic partition of MFE, the other m —1 large grids are applied to reduce MFE dimensionality, when m is increased, MFE dimensionality becomes smaller. The procedures of developing MFE of rectangular parallelepiped, irregular shape, plate and beam types are given. MFE generate the small dimensional discrete models and numerical solutions with a high accuracy. An example of calculating the laminated plate, using three-dimensional 3-grid FE and the reference discrete model is given, with that having 2.2 milliards of FEM nodal unknowns.

Validation of a Novel Technique and Evaluation of the Surface Free Energy of Food

PubMed Central

Senturk Parreidt, Tugce; Schmid, Markus; Hauser, Carolin

2017-01-01

Characterizing the physical properties of a surface is largely dependent on determining the contact angle exhibited by a liquid. Contact angles on the surfaces of rough and irregularly-shaped food samples are difficult to measure using a contact angle meter (goniometer). As a consequence, values for the surface energy and its components can be mismeasured. The aim of this work was to use a novel contact angle measurement method, namely the snake-based ImageJ program, to accurately measure the contact angles of rough and irregular shapes, such as food samples, and so enable more accurate calculation of the surface energy of food materials. In order to validate the novel technique, the contact angles of three different test liquids on four different smooth polymer films were measured using both the ImageJ software with the DropSnake plugin and the widely used contact angle meter. The distributions of the values obtained by the two methods were different. Therefore, the contact angles, surface energies, and polar and dispersive components of plastic films obtained using the ImageJ program and the Drop Shape Analyzer (DSA) were interpreted with the help of simple linear regression analysis. As case studies, the superficial characteristics of strawberry and endive salad epicarp were measured with the ImageJ program and the results were interpreted with the Drop Shape Analyzer equivalent according to our regression models. The data indicated that the ImageJ program can be successfully used for contact angle determination of rough and strongly hydrophobic surfaces, such as strawberry epicarp. However, for the special geometry of droplets on slightly hydrophobic surfaces, such as salad leaves, the program code interpolation part can be altered. PMID:28425932

Energy Extraction from a Slider-Crank Wave Energy under Irregular Wave Conditions: Preprint

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

Sang, Yuanrui; Karayaka, H. Bora; Yan, Yanjun

2015-08-24

A slider-crank wave energy converter (WEC) is a novel energy conversion device. It converts wave energy into electricity at a relatively high efficiency, and it features a simple structure. Past analysis on this particular WEC has been done under regular sinusoidal wave conditions, and suboptimal energy could be achieved. This paper presents the analysis of the system under irregular wave conditions; a time-domain hydrodynamics model is adopted and a rule-based control methodology is introduced to better serve the irregular wave conditions. Results from the simulations show that the performance of the system under irregular wave conditions is different from thatmore » under regular sinusoidal wave conditions, but a reasonable amount of energy can still be extracted.« less

Energy Extraction from a Slider-Crank Wave Energy Converter under Irregular Wave Conditions

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

Sang, Yuanrui; Karayaka, H. Bora; Yan, Yanjun

2015-10-19

A slider-crank wave energy converter (WEC) is a novel energy conversion device. It converts wave energy into electricity at a relatively high efficiency, and it features a simple structure. Past analysis on this particular WEC has been done under regular sinusoidal wave conditions, and suboptimal energy could be achieved. This paper presents the analysis of the system under irregular wave conditions; a time-domain hydrodynamics model is adopted and a rule-based control methodology is introduced to better serve the irregular wave conditions. Results from the simulations show that the performance of the system under irregular wave conditions is different from thatmore » under regular sinusoidal wave conditions, but a reasonable amount of energy can still be extracted.« less

Ultrastructure of identified fast excitatory, slow excitatory and inhibitory neuromuscular junctions in the locust.

PubMed

Titmus, M J

1981-06-01

The specialized jumping muscle of the locust, the metathoracic extensor tibiae (ETi), is innervated by four physiologically different motoneurons, including FETi, a phasic excitor, SETi, a tonic excitor, and CI, a tonic common inhibitor. FETi neuromuscular junctions were examined in three phasic ETi bundles innervated by FETi. FETi terminals were characterized by patchy contacts on to granular sarcoplasm. The ETi accessory extensor, innervated by both SETi and CI, contains two morphologically different types of axon ending. When this muscle was soaked in horseradish peroxidase, stimulation of SETi led to selective uptake in vesicles in terminals similar to those of FETi axons but containing smaller vesicles, while stimulation by CI caused increased uptake into terminals with more extensive contact directly on to fibrillar sarcoplasm. As has been observed in excitatory and inhibitory synapses in some crustacean and vertebrate nervous systems, the synaptic vesicles in the locust excitatory endings are round and electron-lucent while those in the inhibitory endings are more irregular in shape. The tonic neuromuscular junctions, SETi and CI, are more densely packed with vesicles, larger in cross-sectional area and appear to be of more complex shape than the smaller, vesicle-sparse, phasic FETi terminals. Following long duration stimulation at 10 Hz, the tonic neuromuscular junctions showed little morphological change. FETi endings, which fatigue within minutes at the same stimulation frequency, showed a 20% decrease in synaptic vesicle density and an increase in irregularly shaped membrane inclusions.

Aerodynamic Shape Sensitivity Analysis and Design Optimization of Complex Configurations Using Unstructured Grids

NASA Technical Reports Server (NTRS)

Taylor, Arthur C., III; Newman, James C., III; Barnwell, Richard W.

1997-01-01

A three-dimensional unstructured grid approach to aerodynamic shape sensitivity analysis and design optimization has been developed and is extended to model geometrically complex configurations. The advantage of unstructured grids (when compared with a structured-grid approach) is their inherent ability to discretize irregularly shaped domains with greater efficiency and less effort. Hence, this approach is ideally suited for geometrically complex configurations of practical interest. In this work the nonlinear Euler equations are solved using an upwind, cell-centered, finite-volume scheme. The discrete, linearized systems which result from this scheme are solved iteratively by a preconditioned conjugate-gradient-like algorithm known as GMRES for the two-dimensional geometry and a Gauss-Seidel algorithm for the three-dimensional; similar procedures are used to solve the accompanying linear aerodynamic sensitivity equations in incremental iterative form. As shown, this particular form of the sensitivity equation makes large-scale gradient-based aerodynamic optimization possible by taking advantage of memory efficient methods to construct exact Jacobian matrix-vector products. Simple parameterization techniques are utilized for demonstrative purposes. Once the surface has been deformed, the unstructured grid is adapted by considering the mesh as a system of interconnected springs. Grid sensitivities are obtained by differentiating the surface parameterization and the grid adaptation algorithms with ADIFOR (which is an advanced automatic-differentiation software tool). To demonstrate the ability of this procedure to analyze and design complex configurations of practical interest, the sensitivity analysis and shape optimization has been performed for a two-dimensional high-lift multielement airfoil and for a three-dimensional Boeing 747-200 aircraft.

Ultrastructure of the anterior organ and posterior funnel-shaped canal of Gyrocotyle urna Wagener, 1852 (Cestoda: Gyrocotylidea).

PubMed

Poddubnaya, Larisa G; Kuchta, Roman; Bristow, Glenn A; Scholz, Tomas

2015-05-22

Using scanning and transmission electron microscopy, ultrastructure of the anterior organ and posterior funnel-shaped canal of Gyrocotyle urna Wagener, 1852 (Cestoda: Gyrocotylidea) from ratfish, Chimaera monstrosa (Holocephali), was studied for the first time. The proper anterior organ is localised at a short distance (about 170 µm) from an apical pore surrounded by a receptor field, whereas its distal end is marked by a muscular sphincter. The tegumental surface of this organ is covered with short filitriches of irregular length; large area of muscle layers traverse beneath the tegumental layer. The funnel-shaped canal of G. urna (2.5-3.0 mm long) is a specialised, muscular part of the posterior attachment organ; it opens on the rounded elevation on the dorsal body surface. The tegumental layer bears conical sclerite-like structures (up to 1.5 µm long). It produces electron-dense bodies that are transported into a canal lumen and surrounded thick muscle area mixed with numerous nerve fibres. The present ultrastructural study of G. urna indicates that gyrocotylideans share some ultrastructural characters of the anterior organ with spathebothriidean cestodes with a single anterior attachment sucker-like organ. In contrast, the unique posterior rosette attachment organ with funnel-shaped canal of the Gyrocotylidea resembles the haptor of polyopisthocotylean monogeneans in its position at the posterior end of the body and presumed origin. The above-mentioned features add more clarity to support the basal position of the Gyrocotylidea Poche, 1926 among cestodes. In addition, they also indicate a possible relationship of gyrocotylidean ancestors with monogeneans.

Shape, zonal winds and gravitational field of Jupiter: a fully self-consistent, multi-layered model

NASA Astrophysics Data System (ADS)

Schubert, Gerald; Kong, Dali; Zhang, Keke

2016-10-01

We construct a three-dimensional, finite-element, fully self-consistent, multi-layered,non-spheroidal model of Jupiter consisting of an inner core, a metallic electrically conducting dynamo region and an outer molecular electrically insulating envelope. We assume that the Jovian zonal winds are on cylinders parallel to the rotation axis but, due to the effect of magnetic braking, are confined within the outer molecular envelope. Two related calculations are carried out. The first provides an accurate description of the shape and internal density profile of Jupiter; the effect of rotational distortion is not treated as a small perturbation on a spherically symmetric state. This calculation determines the density, size and shape of the inner core, the irregular shape of the 1-bar pressure level, and the internal structure of Jupiter; the full effect of rotational distortion, without the influence of the zonal winds, is accounted for. Our multi-layered model is able to produce the known mass, the known equatorial and polar radii, and the known zonal gravitational coefficient J2 of Jupiter within their error bars; it also yields the coefficients J4 and J6 within about 5% accuracy, and the core equatorial radius 0.09RJ containing 3.73 Earth masses.The second calculation determines the variation of the gravitational field caused solely by the effect of the zonal winds on the rotationally distorted non-spheroidal Jupiter. Four different cases, ranging from a deep wind profile to a very shallow profile, are considered and implications for accurate interpretation of the zonal gravitational coefficients expected from the Juno mission are discussed.

Mammographic mass classification based on possibility theory

NASA Astrophysics Data System (ADS)

Hmida, Marwa; Hamrouni, Kamel; Solaiman, Basel; Boussetta, Sana

2017-03-01

Shape and margin features are very important for differentiating between benign and malignant masses in mammographic images. In fact, benign masses are usually round and oval and have smooth contours. However, malignant tumors have generally irregular shape and appear lobulated or speculated in margins. This knowledge suffers from imprecision and ambiguity. Therefore, this paper deals with the problem of mass classification by using shape and margin features while taking into account the uncertainty linked to the degree of truth of the available information and the imprecision related to its content. Thus, in this work, we proposed a novel mass classification approach which provides a possibility based representation of the extracted shape features and builds a possibility knowledge basis in order to evaluate the possibility degree of malignancy and benignity for each mass. For experimentation, the MIAS database was used and the classification results show the great performance of our approach in spite of using simple features.

A decametric wavelength radio telescope for interplanetary scintillation observations

NASA Technical Reports Server (NTRS)

Cronyn, W. M.; Shawhan, S. D.

1975-01-01

A phased array, electrically steerable radio telescope (with a total collecting area of 18 acres), constructed for the purpose of remotely sensing electron density irregularity structure in the solar wind, is presented. The radio telescope is able to locate, map, and track large scale features of the solar wind, such as streams and blast waves, by monitoring a large grid of natural radio sources subject to rapid intensity fluctuation (interplanetary scintillation) caused by the irregularity structure. Observations verify the performance of the array, the receiver, and the scintillation signal processing circuitry of the telescope.

Ionospheric irregularity characteristics from quasiperiodic structure in the radio wave scintillation

NASA Astrophysics Data System (ADS)

Chen, K. Y.; Su, S. Y.; Liu, C. H.; Basu, S.

2005-06-01

Quasiperiodic (QP) diffraction pattern in scintillation patches has been known to highly correlate with the edge structures of a plasma bubble (Franke et al., 1984). A new time-frequency analysis method of Hilbert-Huang transform (HHT) has been applied to analyze the scintillation data taken at Ascension Island to understand the characteristics of corresponding ionosphere irregularities. The HHT method enables us to extract the quasiperiodic diffraction signals embedded inside the scintillation data and to obtain the characteristics of such diffraction signals. The cross correlation of the two sets of diffraction signals received by two stations at each end of Ascension Island indicates that the density irregularity pattern that causes the diffraction pattern should have an eastward drift velocity of ˜130 m/s. The HHT analysis of the instantaneous frequency in the QP diffraction patterns also reveals some frequency shifts in their peak frequencies. For the QP diffraction pattern caused by the leading edge of the large density gradient at the east wall of a structured bubble, an ascending note in the peak frequency is observed, and for the trailing edge a descending note is observed. The linear change in the transient of the peak frequency in the QP diffraction pattern is consistent with the theory and the simulation result of Franke et al. Estimate of the slope in the transient frequency provides us the information that allows us to identify the locations of plasma walls, and the east-west scale of the irregularity can be estimated. In our case we obtain about 24 km in the east-west scale. Furthermore, the height location of density irregularities that cause the diffraction pattern is estimated to be between 310 and 330 km, that is, around the F peak during observation.

Converging flow and anisotropy cause large-scale folding in Greenland's ice sheet.

PubMed

Bons, Paul D; Jansen, Daniela; Mundel, Felicitas; Bauer, Catherine C; Binder, Tobias; Eisen, Olaf; Jessell, Mark W; Llorens, Maria-Gema; Steinbach, Florian; Steinhage, Daniel; Weikusat, Ilka

2016-04-29

The increasing catalogue of high-quality ice-penetrating radar data provides a unique insight in the internal layering architecture of the Greenland ice sheet. The stratigraphy, an indicator of past deformation, highlights irregularities in ice flow and reveals large perturbations without obvious links to bedrock shape. In this work, to establish a new conceptual model for the formation process, we analysed the radar data at the onset of the Petermann Glacier, North Greenland, and created a three-dimensional model of several distinct stratigraphic layers. We demonstrate that the dominant structures are cylindrical folds sub-parallel to the ice flow. By numerical modelling, we show that these folds can be formed by lateral compression of mechanically anisotropic ice, while a general viscosity contrast between layers would not lead to folding for the same boundary conditions. We conclude that the folds primarily form by converging flow as the mechanically anisotropic ice is channelled towards the glacier.

Converging flow and anisotropy cause large-scale folding in Greenland's ice sheet

NASA Astrophysics Data System (ADS)

Bons, Paul D.; Jansen, Daniela; Mundel, Felicitas; Bauer, Catherine C.; Binder, Tobias; Eisen, Olaf; Jessell, Mark W.; Llorens, Maria-Gema; Steinbach, Florian; Steinhage, Daniel; Weikusat, Ilka

2016-04-01

The increasing catalogue of high-quality ice-penetrating radar data provides a unique insight in the internal layering architecture of the Greenland ice sheet. The stratigraphy, an indicator of past deformation, highlights irregularities in ice flow and reveals large perturbations without obvious links to bedrock shape. In this work, to establish a new conceptual model for the formation process, we analysed the radar data at the onset of the Petermann Glacier, North Greenland, and created a three-dimensional model of several distinct stratigraphic layers. We demonstrate that the dominant structures are cylindrical folds sub-parallel to the ice flow. By numerical modelling, we show that these folds can be formed by lateral compression of mechanically anisotropic ice, while a general viscosity contrast between layers would not lead to folding for the same boundary conditions. We conclude that the folds primarily form by converging flow as the mechanically anisotropic ice is channelled towards the glacier.

Discovery of Grooves on Gaspra

USGS Publications Warehouse

Veverka, J.; Thomas, P.; Simonelli, D.; Belton, M.J.S.; Carr, M.; Chapman, C.; Davies, M.E.; Greeley, R.; Greenberg, R.; Head, J.; Klaasen, K.; Johnson, T.V.; Morrison, D.; Neukum, G.

1994-01-01

We report the discovery of grooves in Galileo high-resolution images of Gaspra. These features, previously seen only on Mars' satellite Phobos, are most likely related to severe impacts. Grooves on Gaspra occur as linear and pitted depressions, typically 100-200 m wide, 0.8 to 2.5 km long, and 10-20 m deep. Most occur in two major groups, one of which trends approximately parallel to the asteroid's long axis, but is offset by some 15??; the other is approximately perpendicular to this trend. The first of these directions falls along a family of planes which parallel three extensive flat facets identified by Thomas et al., Icarus 107. The occurrence of grooves on Gaspra is consistent with other indications (irregular shape, cratering record) that this asteroid has evolved through a violent collisional history. The bodywide congruence of major groove directions and other structural elements suggests that present-day Gaspra is a globally coherent body. ?? 1994 Academic Press. All rights reserved.

Supervolcanoes Within an Ancient Volcanic Province in Arabia Terra, Mars

NASA Technical Reports Server (NTRS)

Michalski, Joseph. R.; Bleacher, Jacob E.

2014-01-01

Several irregularly shaped craters located within Arabia Terra, Mars represent a new type of highland volcanic construct and together constitute a previously unrecognized martian igneous province. Similar to terrestrial supervolcanoes, these low-relief paterae display a range of geomorphic features related to structural collapse, effusive volcanism, and explosive eruptions. Extruded lavas contributed to the formation of enigmatic highland ridged plains in Arabia Terra. Outgassed sulfur and erupted fine-grained pyroclastics from these calderas likely fed the formation of altered, layered sedimentary rocks and fretted terrain found throughout the equatorial region. Discovery of a new type of volcanic construct in the Arabia volcanic province fundamentally changes the picture of ancient volcanism and climate evolution on Mars. Other eroded topographic basins in the ancient Martian highlands that have been dismissed as degraded impact craters should be reconsidered as possible volcanic constructs formed in an early phase of widespread, disseminated magmatism on Mars.

Investigation on the structures and magnetic properties of carbon or nitrogen doped cobalt ferrite nanoparticles.

PubMed

Cao, Derang; Pan, Lining; Li, Jianan; Cheng, Xiaohong; Zhao, Zhong; Xu, Jie; Li, Qiang; Wang, Xia; Li, Shandong; Wang, Jianbo; Liu, Qingfang

2018-05-21

Carbon or nitrogen doped cobalt ferrite nanoparticles were synthesized in the air by a facile calcination process. X-ray diffraction, mapping, X-ray photoelectron spectroscopy, and mössbauer spectra results indicate that the nonmetal elements as the interstitial one are doped into cobalt ferrite nanoparticles. The morphologies of doped cobalt ferrite nanoparticles change from near-spherical to irregular cubelike shapes gradually with the increased carbon or nitrogen concentration, and their particles sizes also increase more than 200 nm. Furthermore, the saturation magnetization of carbon doped cobalt ferrite is improved. Although the saturation magnetization of N-doped cobalt ferrite is not enhanced obviously due to the involved hematite, they also do not drop drastically. The results reveal an approach to synthesize large scale ferrite nanoparticles, and improve the magnetic properties of ferrite nanoparticles, and also provide the potential candidates to synthesis co-doped functional magnetic materials.

Finite element stress analysis of the human left ventricle whose irregular shape is developed from single plane cineangiocardiogram

NASA Technical Reports Server (NTRS)

Ghista, D. N.; Hamid, M. S.

1977-01-01

The three-dimensional left ventricular chamber geometrical model is developed from single plane cineangiocardiogram. This left ventricular model is loaded by an internal pressure monitored by cardiac catheterization. The resulting stresses in the left ventricular model chamber's wall are determined by computerized finite element procedure. For the discretization of this left ventricular model structure, a 20-node, isoparametric finite element is employed. The analysis and formulation of the computerised procedure is presented in the paper, along with the detailed algorithms and computer programs. The procedure is applied to determine the stresses in a left ventricle at an instant, during systole. Next, a portion (represented by a finite element) of this left ventricular chamber is simulated as being infarcted by making its active-state modulus value equal to its passive-state value; the neighbouring elements are shown to relieve the 'infarcted' element of stress by themselves taking on more stress.

Bim from Laser SCANS… not Just for Buildings: Nurbs-Based Parametric Modeling of a Medieval Bridge

NASA Astrophysics Data System (ADS)

Barazzetti, L.; Banfi, F.; Brumana, R.; Previtali, M.; Roncoroni, F.

2016-06-01

Building Information Modelling is not limited to buildings. BIM technology includes civil infrastructures such as roads, dams, bridges, communications networks, water and wastewater networks and tunnels. This paper describes a novel methodology for the generation of a detailed BIM of a complex medieval bridge. The use of laser scans and images coupled with the development of algorithms able to handle irregular shapes allowed the creation of advanced parametric objects, which were assembled to obtain an accurate BIM. The lack of existing object libraries required the development of specific families for the different structural elements of the bridge. Finally, some applications aimed at assessing the stability and safety of the bridge are illustrated and discussed. The BIM of the bridge can incorporate this information towards a new "BIMonitoring" concept to preserve the geometric complexity provided by point clouds, obtaining a detailed BIM with object relationships and attributes.

Supervolcanoes within an ancient volcanic province in Arabia Terra, Mars.

PubMed

Michalski, Joseph R; Bleacher, Jacob E

2013-10-03

Several irregularly shaped craters located within Arabia Terra, Mars, represent a new type of highland volcanic construct and together constitute a previously unrecognized Martian igneous province. Similar to terrestrial supervolcanoes, these low-relief paterae possess a range of geomorphic features related to structural collapse, effusive volcanism and explosive eruptions. Extruded lavas contributed to the formation of enigmatic highland ridged plains in Arabia Terra. Outgassed sulphur and erupted fine-grained pyroclastics from these calderas probably fed the formation of altered, layered sedimentary rocks and fretted terrain found throughout the equatorial region. The discovery of a new type of volcanic construct in the Arabia volcanic province fundamentally changes the picture of ancient volcanism and climate evolution on Mars. Other eroded topographic basins in the ancient Martian highlands that have been dismissed as degraded impact craters should be reconsidered as possible volcanic constructs formed in an early phase of widespread, disseminated magmatism on Mars.

A new species of the genus Bertholdia Schaus, 1896 (Lepidoptera: Erebidae: Arctiinae) from the Neotropical region: Bertholdia zoenia sp. n.

PubMed

Beccacece, Hernan Mario

2017-03-02

A new species of Bertholdia Schaus is described: Bertholdia zoenia sp. n., based on males and females from Argentina and Paraguay. This new species is closer to Bertholdia myosticta Hampson, 1901 from Costa Rica, Irazú. Bertholdia zoenia sp. n. can be recognized externally because its hyaline spot on forewing is the widest among all species of genus. Also, the shape of this hyaline spot is like a right triangle with smooth outer margin, different from other species of genus, which have an irregular spot. Habitus, male and female genitalia, and particular structures of B. zoenia sp. n. are illustrated. Habitus and male genitalia of B. myosticta are also illustrated. A distribution map and commentaries of habitat of B. zoenia sp. n. and B. myosticta are given. Remarks on nomenclature of the genus are provided.

Ultrasonographic findings of shoulder teno-muscular structures in symptomatic and asymptomatic dogs.

PubMed

Barella, Gabriele; Lodi, Matteo; Faverzani, Stefano

2017-11-14

B-mode sonographic evaluation of shoulder joint in dogs provides qualitative information concerning mainly tendon and muscles structures. Although the sonographic findings of tenomuscular lesions have been described previously, their frequency in symptomatic and asymptomatic patients has not been reported yet. Aim of the study was to describe and compare qualitative ultrasonographic findings of shoulder joint in clinically symptomatic and asymptomatic dogs and to speculate which lesions might be considered major responsible for lameness. Fifty-two dogs with shoulder lameness and 58 asymptomatic dogs (both with unremarkable radiographic findings) underwent ultrasonographic B-mode examination of the scapulohumeral joint. Lesions detected were recorded and statistically compared between groups. Significant differences between groups were observed for the number of ultrasonographic abnormalities detected and for fluid accumulation, biceps brachii tendon (BT) lesions and bone surface irregularities. Sonography was considered useful for the determination of lesions absence and for the detection of BT lesions, fluid accumulation, muscle lacerations and bone surface irregularities. The odds for symptomatic dogs were greater than for asymptomatic patients to ultrasonographically diagnose BT lesions, fluid accumulation and bone surface irregularities. Ultrasound has proven to be a useful tool in the evaluation of tenomusculoskeletal structures of shoulder in dogs with unremarkable radiographic findings. Our results suggest that ultrasonography is useful in the diagnosis of tendon abnormalities, fluid accumulation, muscle lacerations and bone surface irregularities as potential contributors to shoulder lameness in dogs.

Processing of hierarchical syntactic structure in music.

PubMed

Koelsch, Stefan; Rohrmeier, Martin; Torrecuso, Renzo; Jentschke, Sebastian

2013-09-17

Hierarchical structure with nested nonlocal dependencies is a key feature of human language and can be identified theoretically in most pieces of tonal music. However, previous studies have argued against the perception of such structures in music. Here, we show processing of nonlocal dependencies in music. We presented chorales by J. S. Bach and modified versions in which the hierarchical structure was rendered irregular whereas the local structure was kept intact. Brain electric responses differed between regular and irregular hierarchical structures, in both musicians and nonmusicians. This finding indicates that, when listening to music, humans apply cognitive processes that are capable of dealing with long-distance dependencies resulting from hierarchically organized syntactic structures. Our results reveal that a brain mechanism fundamental for syntactic processing is engaged during the perception of music, indicating that processing of hierarchical structure with nested nonlocal dependencies is not just a key component of human language, but a multidomain capacity of human cognition.

Tactile Imaging of an Imbedded Palpable Structure for Breast Cancer Screening

PubMed Central

2015-01-01

Apart from texture, the human finger can sense palpation. The detection of an imbedded structure is a fine balance between the relative stiffness of the matrix, the object, and the device. If the device is too soft, its high responsiveness will limit the depth to which the imbedded structure can be detected. The sensation of palpation is an effective procedure for a physician to examine irregularities. In a clinical breast examination (CBE), by pressing over 1 cm2 area, at a contact pressure in the 70–90 kPa range, the physician feels cancerous lumps that are 8- to 18-fold stiffer than surrounding tissue. Early detection of a lump in the 5–10 mm range leads to an excellent prognosis. We describe a thin-film tactile device that emulates human touch to quantify CBE by imaging the size and shape of 5–10 mm objects at 20 mm depth in a breast model using ∼80 kPa pressure. The linear response of the device allows quantification where the greyscale corresponds to the relative local stiffness. The (background) signal from <2.5-fold stiffer objects at a size below 2 mm is minimal. PMID:25148477

Structural organization of poliovirus RNA replication is mediated by viral proteins of the P2 genomic region

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

Bienz, K.; Egger, D.; Troxler, M.

1990-03-01

Transcriptionally active replication complexes bound to smooth membrane vesicles were isolated from poliovirus-infected cells. In electron microscopic, negatively stained preparations, the replication complex appeared as an irregularly shaped, oblong structure attached to several virus-induced vesicles of a rosettelike arrangement. Electron microscopic immunocytochemistry of such preparations demonstrated that the poliovirus replication complex contains the proteins coded by the P2 genomic region (P2 proteins) in a membrane-associated form. In addition, the P2 proteins are also associated with viral RNA, and they can be cross-linked to viral RNA by UV irradiation. Guanidine hydrochloride prevented the P2 proteins from becoming membrane bound but didmore » not change their association with viral RNA. The findings allow the conclusion that the protein 2C or 2C-containing precursor(s) is responsible for the attachment of the viral RNA to the vesicular membrane and for the spatial organization of the replication complex necessary for its proper functioning in viral transcription. A model for the structure of the viral replication complex and for the function of the 2C-containing P2 protein(s) and the vesicular membranes is proposed.« less

[Observation on eggs of Oncomelania hupensis hupensis with scanning electron microscope].

PubMed

Xia, Q B; Yuan, Y B; Liu, B; Tan, P P

2001-01-01

To observe the structure of the mud hull packed Oncomelania eggs and the surface structure of colloid membrane called the third grade membrane of eggs. Scanning electron microscopy was used to observe Oncomelania snail eggs with integral mud hull collected from eastern Dongting Lake. The mud hull of eggs was made of unshapen small humification combined with earth granules with a diameter of 2.6-9.2 microns. The mud hull in 60 um thickness was honeycomb-like in shape with many small holes and small folds on the wall. There were many round or irregularly round hollownesses on the inner layer of mud hull that contacts colloid membrane but no hole through mud hull. There were some protein fiber networks covering on the colloid membrane and apophysis. The structure of the mud hull showed that the exchange of matter was maintained between eggs and outside, and the mud hull is of great importance to regulating temperature and moisture for the growth of eggs by preventing hydrosoluble substances from penetrating into eggs. The protein fiber networks act on gluing mud hull and buffering outside power. The dense glue membrane might be a main barricade to prevent pharmaceutical molecules from penetrating into eggs.

Study of self-ion irradiated nanostructured ferritic alloy (NFA) and silicon carbide-nanostructured ferritic alloy (SiC-NFA) cladding materials

NASA Astrophysics Data System (ADS)

Ning, Kaijie; Bai, Xianming; Lu, Kathy

2018-07-01

Silicon carbide-nanostructured ferritic alloy (SiC-NFA) materials are expected to have the beneficial properties of each component for advanced nuclear claddings. Fabrication of pure NFA (0 vol% SiC-100 vol% NFA) and SiC-NFAs (2.5 vol% SiC-97.5 vol% NFA, 5 vol% SiC-95 vol% NFA) has been reported in our previous work. This paper is focused on the study of radiation damage in these materials under 5 MeV Fe++ ion irradiation with a dose up to ∼264 dpa. It is found that the material surfaces are damaged to high roughness with irregularly shaped ripples, which can be explained by the Bradley-Harper (B-H) model. The NFA matrix shows ion irradiation induced defect clusters and small dislocation loops, while the crystalline structure is maintained. Reaction products of Fe3Si and Cr23C6 are identified in the SiC-NFA materials, with the former having a partially crystalline structure but the latter having a fully amorphous structure upon irradiation. The different radiation damage behaviors of NFA, Fe3Si, and Cr23C6 are explained using the defect reaction rate theory.

Modeling of DNA-Mediated Self-Assembly from Anisotropic Nanoparticles: A Molecular Dynamics Study

NASA Astrophysics Data System (ADS)

Millan, Jaime; Girard, Martin; Brodin, Jeffrey; O'Brien, Matt; Mirkin, Chad; Olvera de La Cruz, Monica

The programmable selectivity of DNA recognition constitutes an elegant scheme to self-assemble a rich variety of superlattices from versatile nanoscale building blocks, where the natural interactions between building blocks are traded by complementary DNA hybridization interactions. Recently, we introduced and validated a scale-accurate coarse-grained model for a molecular dynamics approach that captures the dynamic nature of DNA hybridization events and reproduces the experimentally-observed crystallization behavior of various mixtures of spherical DNA-modified nanoparticles. Here, we have extended this model to robustly reproduce the assembly of nanoparticles with the anisotropic shapes observed experimentally. In particular, we are interested in two different particle types: (i) regular shapes, namely the cubic and octahedral polyhedra shapes commonly observed in gold nanoparticles, and (ii) irregular shapes akin to those exhibited by enzymes. Anisotropy in shape can provide an analog to the atomic orbitals exhibited by conventional atomic crystals. We present results for the assembly of enzymes or anisotropic nanoparticles and the co-assembly of enzymes and nanoparticles.

Path integration guided with a quality map for shape reconstruction in the fringe reflection technique

NASA Astrophysics Data System (ADS)

Jing, Xiaoli; Cheng, Haobo; Wen, Yongfu

2018-04-01

A new local integration algorithm called quality map path integration (QMPI) is reported for shape reconstruction in the fringe reflection technique. A quality map is proposed to evaluate the quality of gradient data locally, and functions as a guideline for the integrated path. The presented method can be employed in wavefront estimation from its slopes over the general shaped surface with slope noise equivalent to that in practical measurements. Moreover, QMPI is much better at handling the slope data with local noise, which may be caused by the irregular shapes of the surface under test. The performance of QMPI is discussed by simulations and experiment. It is shown that QMPI not only improves the accuracy of local integration, but can also be easily implemented with no iteration compared to Southwell zonal reconstruction (SZR). From an engineering point-of-view, the proposed method may also provide an efficient and stable approach for different shapes with high-precise demand.

Improvement of diagnostic efficiency in distinguishing the benign and malignant thyroid nodules via conventional ultrasound combined with ultrasound contrast and elastography

PubMed Central

Liu, Mei-Juan; Men, Yan-Ming; Zhang, Yong-Lin; Zhang, Yu-Xi; Liu, Hao

2017-01-01

We aimed to evaluate the diagnostic values of conventional ultrasound (US), ultrasound contrast (UC) and ultrasound elastography (UE) in distinguishing the benign and malignant thyroid nodules. A total of 100 patients with thyroid nodules receiving operative treatment were selected; they underwent the conventional US, UE and UC examinations before operation, respectively. The nodules received pathological examination after operation to distinguish benign from malignant lesions. The sensitivity, specificity and diagnostic accordance rate of each diagnostic method was evaluated by receiver operating characteristic (ROC) curve, and the area under the curve (AUC) of ROC was calculated. The manifestations of malignant thyroid nodules in conventional US examination were mostly the hypoecho, heterogeneous echo, irregular shape, unclear boundary, aspect ratio <1, microcalcification and irregular peripheral echo halo, and there were statistically significant differences compared with the benign nodules (P<0.05). UE showed that the differences between benign and malignant nodules in 2, 3 and 4 points were statistically significant (P<0.05). The manifestations of malignant nodules in UC were mostly the irregular shape, obscure boundary, no obvious enhancement, heterogeneous enhancement and visible perfusion defects, and there were statistically significant differences compared with the benign nodules (P<0.05). ROC curve showed that both sensitivity and specificity of UE and UC were superior to those of conventional US. AUC was the largest (AUC = 0.908) and the diagnostic value was the highest in the conventional US combined with UE and UC. Conventional US combined with elastography and UC can significantly improve the sensitivity, specificity and accuracy of diagnosis of benign and malignant thyroid nodules. PMID:28693244

Improvement of diagnostic efficiency in distinguishing the benign and malignant thyroid nodules via conventional ultrasound combined with ultrasound contrast and elastography.

PubMed

Liu, Mei-Juan; Men, Yan-Ming; Zhang, Yong-Lin; Zhang, Yu-Xi; Liu, Hao

2017-07-01

We aimed to evaluate the diagnostic values of conventional ultrasound (US), ultrasound contrast (UC) and ultrasound elastography (UE) in distinguishing the benign and malignant thyroid nodules. A total of 100 patients with thyroid nodules receiving operative treatment were selected; they underwent the conventional US, UE and UC examinations before operation, respectively. The nodules received pathological examination after operation to distinguish benign from malignant lesions. The sensitivity, specificity and diagnostic accordance rate of each diagnostic method was evaluated by receiver operating characteristic (ROC) curve, and the area under the curve (AUC) of ROC was calculated. The manifestations of malignant thyroid nodules in conventional US examination were mostly the hypoecho, heterogeneous echo, irregular shape, unclear boundary, aspect ratio <1, microcalcification and irregular peripheral echo halo, and there were statistically significant differences compared with the benign nodules (P<0.05). UE showed that the differences between benign and malignant nodules in 2, 3 and 4 points were statistically significant (P<0.05). The manifestations of malignant nodules in UC were mostly the irregular shape, obscure boundary, no obvious enhancement, heterogeneous enhancement and visible perfusion defects, and there were statistically significant differences compared with the benign nodules (P<0.05). ROC curve showed that both sensitivity and specificity of UE and UC were superior to those of conventional US. AUC was the largest (AUC = 0.908) and the diagnostic value was the highest in the conventional US combined with UE and UC. Conventional US combined with elastography and UC can significantly improve the sensitivity, specificity and accuracy of diagnosis of benign and malignant thyroid nodules.

PBP deletion mutants of Escherichia coli exhibit irregular distribution of MreB at the deformed zones.

PubMed

Vijayan, Saptha; Mallick, Sathi; Dutta, Mouparna; Narayani, M; Ghosh, Anindya S

2014-02-01

MreB is a cytoskeletal protein, which is responsible for maintaining proper cellular morphology and is essential for cell survival. Likewise, penicillin-binding protein 5 (PBP5) helps in maintaining cell shape, though non-essential for survival. The contradicting feature of these two proteins paves the way for this study, wherein we attempt to draw a relation on the nature of distribution of MreB in PBP deletion mutants. The study revealed that the uniform MreB helices/patches were destabilized/disturbed at the zone of deformities of the PBP mutants, whereas the helical patterns were retained at the regions maintaining a rod shape. We interpret that MreB remains functional irrespective of its distribution being misguided by the aberrant shapes of PBP mutants.