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Sample records for local micrometer scale

  1. Epitaxial integration of nanowires in microsystems by local micrometer-scale vapor-phase epitaxy.

    PubMed

    Mølhave, Kristian; Wacaser, Brent A; Petersen, Dirch Hjorth; Wagner, Jakob B; Samuelson, Lars; Bøggild, Peter

    2008-10-01

    Free-standing epitaxially grown nanowires provide a controlled growth system and an optimal interface to the underlying substrate for advanced optical, electrical, and mechanical nanowire device connections. Nanowires can be grown by vapor-phase epitaxy (VPE) methods such as chemical vapor deposition (CVD) or metal organic VPE (MOVPE). However, VPE of semiconducting nanowires is not compatible with several microfabrication processes due to the high synthesis temperatures and issues such as cross-contamination interfering with the intended microsystem or the VPE process. By selectively heating a small microfabricated heater, growth of nanowires can be achieved locally without heating the entire microsystem, thereby reducing the compatibility problems. The first demonstration of epitaxial growth of silicon nanowires by this method is presented and shows that the microsystem can be used for rapid optimization of VPE conditions. The important issue of the cross-contamination of other parts of the microsystem caused by the local growth of nanowires is also investigated by growth of GaN near previously grown silicon nanowires. The design of the cantilever heaters makes it possible to study the grown nanowires with a transmission electron microscope without sample preparation.

  2. Probing the concepts of the Local Effect Model: The relevance of damage clustering on the nanometer and micrometer scale

    NASA Astrophysics Data System (ADS)

    Scholz, Michael; Friedrich, Thomas; Durante, Marco; Scholz, Uwe; Tommasino, Francesco; Herr, Lisa

    The Local Effect Model (LEM) allows predicting biological effects of ion beams on the basis of amorphous track structure in combination with the known dose response curves for photon radiation. In the recent version LEM IV (Elsässer et al. 2010), track structure and the observable biological effect are linked via the microscopic spatial DSB distribution that is induced by particle traversals through the cell nucleus. In order to determine this distribution, clustering of damages on two different scales, namely the nanometer and the micrometer scale, are particularly considered. On the nanometer scale, due to the extremely high ionization density in the center of tracks the simultaneous induction of two SSB in close vicinity by two independent secondary electrons becomes probable. As a result, additional DSB can be induced, so that a higher yield of DSB as compared to photon radiation is expected. On the micrometer scale, the spatial distribution of DSB with respect to higher order chromatin structure allows the definition of two damage classes. If two or more DSB are induced within chromatin loops of about 2 Mbp size (so called clustered DSB, cDSB) this damage class is assumed to be linked to a significantly increased lethality as compared to the case of a single, isolated DSB (iDSB) induced in a chromatin loop. In the talk, the basic principles of the LEM IV will be briefly reviewed. The focus will then be on the discussion of signatures in radiation response that are expected as a consequence of the above mentioned clustering processes. In order to validate the relevance of these processes, the concept of the LEM is transferred to additional endpoints, e.g. the kinetics of DSB rejoining, as well as to other radiation qualities like high-energy (typically MeV) and ultrasoft (typically keV) photon radiation. First, we briefly discuss the transfer of the concept to high energetic photon radiation that allows explaining the linear quadratic shape of the photon dose

  3. Additive Manufacturing of Metal Structures at the Micrometer Scale.

    PubMed

    Hirt, Luca; Reiser, Alain; Spolenak, Ralph; Zambelli, Tomaso

    2017-05-01

    Currently, the focus of additive manufacturing (AM) is shifting from simple prototyping to actual production. One driving factor of this process is the ability of AM to build geometries that are not accessible by subtractive fabrication techniques. While these techniques often call for a geometry that is easiest to manufacture, AM enables the geometry required for best performance to be built by freeing the design process from restrictions imposed by traditional machining. At the micrometer scale, the design limitations of standard fabrication techniques are even more severe. Microscale AM thus holds great potential, as confirmed by the rapid success of commercial micro-stereolithography tools as an enabling technology for a broad range of scientific applications. For metals, however, there is still no established AM solution at small scales. To tackle the limited resolution of standard metal AM methods (a few tens of micrometers at best), various new techniques aimed at the micrometer scale and below are presently under development. Here, we review these recent efforts. Specifically, we feature the techniques of direct ink writing, electrohydrodynamic printing, laser-assisted electrophoretic deposition, laser-induced forward transfer, local electroplating methods, laser-induced photoreduction and focused electron or ion beam induced deposition. Although these methods have proven to facilitate the AM of metals with feature sizes in the range of 0.1-10 µm, they are still in a prototype stage and their potential is not fully explored yet. For instance, comprehensive studies of material availability and material properties are often lacking, yet compulsory for actual applications. We address these items while critically discussing and comparing the potential of current microscale metal AM techniques. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Flow and evaporation in single micrometer and nanometer scale pipes

    SciTech Connect

    Velasco, A. E.; Yang, C.; Siwy, Z. S.; Taborek, P.; Toimil-Molares, M. E.

    2014-07-21

    We report measurements of pressure driven flow of fluids entering vacuum through a single pipe of micrometer or nanometer scale diameter. Nanopores were fabricated by etching a single ion track in polymer or mica foils. A calibrated mass spectrometer was used to measure the flow rates of nitrogen and helium through pipes with diameter ranging from 10 μm to 31 nm. The flow of gaseous and liquid nitrogen was studied near 77 K, while the flow of helium was studied from the lambda point (2.18 K) to above the critical point (5.2 K). Flow rates were controlled by changing the pressure drop across the pipe in the range 0–31 atm. When the pressure in the pipe reached the saturated vapor pressure, an abrupt flow transition was observed. A simple viscous flow model is used to determine the position of the liquid/vapor interface in the pipe. The observed mass flow rates are consistent with no slip boundary conditions.

  5. Microstructural and Compositional Relations of Granitoid Clasts in Lunar Breccias at the Micrometer to Sub-Micrometer Scale

    NASA Technical Reports Server (NTRS)

    Christoffersen, R.; Simon, J. I.; Mills, R. D.; Ross, D. K.; Tappa, M.

    2015-01-01

    Lunar granitoid lithologies have long been of interest for the information they provide on processes leading to silicic melt compositions on the Moon. The extraction of such melts over time affects the distribution and budget of incompatible materials (i.e., radiogenic heat producing elements and volatiles) of the lunar interior. We have recently shown that in addition to their high concentrations of incompatible lithophile elements, some granitoid clasts in lunar breccias have significant indigenous water contents in their alkali feldspars. This raises the importance of lunar granitoid materials in the expanding search for mineralogic/petrologic hosts of indigenous lunar water-related species. We are undertaking a detailed survey of the petrologic/mineralogical relations of granitoid clasts in lunar breccias to achieve a better understanding of the potential of these diverse assemblages as hosts for volatiles, and as candidates for additional isotope chronology studies. Our preliminary results reported here based on high-resolution field-emission SEM, EPMA and TEM studies uncover immense complexity in these materials at the micrometer to sub-micrometer scale that heretofore have not been fully documented.

  6. Hyperbranched polyglycerols on the nanometer and micrometer scale.

    PubMed

    Steinhilber, Dirk; Seiffert, Sebastian; Heyman, John A; Paulus, Florian; Weitz, David A; Haag, Rainer

    2011-02-01

    We report the preparation of polyglycerol particles on different length scales by extending the size of hyperbranched polyglycerols (3 nm) to nanogels (32 nm) and microgels (140 and 220 μm). We use miniemulsion templating for the preparation of nanogels and microfluidic templating for the preparation of microgels, which we obtain through a free-radical polymerization of hyperbranched polyglycerol decaacrylate and polyethylene glycol-diacrylate. The use of mild polymerization conditions allows yeast cells to be encapsulated into the resultant microgels with cell viabilities of approximately 30%.

  7. Fluctuating Potentials In Micrometer Scale Atomic Ion Traps

    NASA Astrophysics Data System (ADS)

    Britton, J.; Seidelin, S.; Chiaverini, J.; Reichle, R.; Bollinger, J. J.; Leibfried, D.; Wesenberg, J. H.; Blakestad, R. B.; Epstein, R. J.; Shiga, N.; Amini, J. M.; Brown, K. R.; Home, J. P.; Hume, D. B.; Itano, W. M.; Jost, J. D.; Langer, C.; Ozeri, R.; Wineland, D. J.

    2007-03-01

    Electromagnetic confinement of atomic ion qubits coupled with laser cooling has permitted observation of 10 minute coherence times [1, 2]. Recent work to miniaturize electromagnetic traps promises qubit densities attractive for large scale quantum computing [3]. However, motional heating resulting from poorly understood fluctuating trapping potentials is observed to increase as approximately dimensions-4 [4]. We discuss efforts to suppress this heating and present experimental results for several microtrap fabrication techniques [5, 6]. [1] P. T. H. Fisk et al., IEEE Trans. Instrum. Meas. 44, 113 (1995). [2] J. J. Bollinger et al., IEEE Trans. Instrum. Measurement 40, 126 (1991). [3] A. Steane, quant-ph/0412165. [4] L. Deslauriers et al., Phys. Rev. Lett. 97, 103007 (2006). [5] S. Seidelin et al., Phys. Rev. Lett. 96, 253003 (2006). [6] J. Britton et al., quant-ph/0605170.

  8. Micrometer scale spacings between fibronectin nanodots regulate cell morphology and focal adhesions

    NASA Astrophysics Data System (ADS)

    Horzum, Utku; Ozdil, Berrin; Pesen-Okvur, Devrim

    2014-04-01

    Cell adhesion to extracellular matrix is an important process for both health and disease states. Surface protein patterns that are topographically flat, and do not introduce other chemical, topographical or rigidity related functionality and, more importantly, that mimic the organization of the in vivo extracellular matrix are desired. Previous work showed that vinculin and cytoskeletal organization are modulated by size and shape of surface nanopatterns. However, quantitative analysis on cell morphology and focal adhesions as a function of micrometer scale spacings of FN nanopatterns was absent. Here, electron beam lithography was used to pattern fibronectin nanodots with micrometer scale spacings on a K-casein background on indium tin oxide coated glass which, unlike silicon, is transparent and thus suitable for many light microscopy techniques. Exposure times were significantly reduced using the line exposure mode with micrometer scale step sizes. Micrometer scale spacings of 2, 4 and 8 μm between fibronectin nanodots proved to modulate cell adhesion through modification of cell area, focal adhesion number, size and circularity. Overall, cell behavior was shown to shift at the apparent threshold of 4 μm spacing. The findings presented here offer exciting new opportunities for cell biology research.

  9. Method for producing fabrication material for constructing micrometer-scaled machines, fabrication material for micrometer-scaled machines

    SciTech Connect

    Stevens, F.J.

    1995-12-31

    A method for producing fabrication material for use in the construction of nanometer-scaled machines is provided whereby similar protein molecules are isolated and manipulated at predetermined residue positions so as to facilitate noncovalent interaction, but without compromising the folding configuration or native structure of the original protein biomodules. A fabrication material is also provided consisting of biomodules systematically constructed and arranged at specific solution parameters.

  10. Imaging Micrometer Scale Rock Magnetism Using a Quantum Diamond Microscope

    NASA Astrophysics Data System (ADS)

    Fu, R. R.; Glenn, D. R.; Le Sage, D.; Andrade Lima, E.; Weiss, B. P.; Walsworth, R. L.

    2014-12-01

    Optically-detected magnetometry using quantum defects in diamond, known as nitrogen-vacancy (NV) color centers, is an emerging technology that allows high sensitivity and high resolution mapping of magnetic fields. Recent measurements of live magnetotactic bacteria demonstrate that such a "quantum diamond microscope" can image individual magnetic sources with <500 nm resolution, >1 mm field-of-view, and magnetic moment sensitivity <10-16 A m2 under ambient temperatures and pressures. The unprecedented combination of spatial resolution and magnetic sensitivity of the quantum diamond microscope permits magnetic analyses of previously inaccessible geologic samples in which the regions of interest are mixed with undesirable magnetic field sources at the <<100 µm scale. Here we apply this technique to chondritic meteorites, primordial aggregates formed during the accretional phase of the solar system. These meteorites consist of fine-grained matrix mixed with chondrules and other inclusions with characteristic sizes of 0.1 - 1 mm. Each chondrule records a unique magnetic history and potentially constrains nebular magnetic fields, which likely played a key role in accretion disk dynamics. The quantum diamond microscope is unique in its ability to resolve the magnetic signal of single inclusions from surrounding material. We applied the quantum diamond microscope to a variety of natural and artificial samples. Magnetic field maps of a single chondrule from the Allende CV carbonaceous chondrite (Fig. 1) show that the strongest magnetic sources are located in its 20 μm thick rim. Magnetic field sources in the chondrule interior occur in the mesostasis as isolated 10-100 μm patches that generate magnetic fields ~10 times weaker than the rim. These maps highlight the importance of spatial resolution for paleomagnetic measurements of chondrites; lower resolution measurements would permit the nearby rim material to dominate the magnetic signal, precluding accurate recovery

  11. DNA damage on nano- and micrometer scales impacts dicentric induction: computer modelling of ion microbeam experiments

    NASA Astrophysics Data System (ADS)

    Friedland, Werner; Kundrat, Pavel; Schmitt, Elke

    2016-07-01

    Detailed understanding of the enhanced relative biological effectiveness (RBE) of ions, in particular at high linear energy transfer (LET) values, is needed to fully explore the radiation risk of manned space missions. It is generally accepted that the enhanced RBE of high-LET particles results from the DNA lesion patterns, in particular DNA double-strand breaks (DSB), due to the spatial clustering of energy deposits around their trajectories. In conventional experiments on biological effects of radiation types of diverse quality, however, clustering of energy deposition events on nanometer scale that is relevant for the induction and local complexity of DSB is inherently interlinked with regional (sub-)micrometer-scale DSB clustering along the particle tracks. Due to this limitation, the role of both (nano- and micrometer) scales on the induction of diverse biological endpoints cannot be frankly separated. To address this issue in a unique way, experiments at the ion microbeam SNAKE [1] and corresponding track-structure based model calculations of DSB induction and subsequent repair with the biophysical code PARTRAC [2] have been performed. In the experiments, hybrid human-hamster A_{L} cells were irradiated with 20 MeV (2.6 keV/μm) protons, 45 MeV (60 keV/μm) lithium ions or 55 MeV (310 keV/μm) carbon ions. The ions were either quasi-homogeneously distributed or focused to 0.5 x 1 μm^{2} spots on regular matrix patterns of 5.4 μm, 7.6 μm and 10.6 μm grid size, with pre-defined particle numbers per spot so as to deposit a mean dose of 1.7 Gy for all irradiation patterns. As expected, the induction of dicentrics by homogeneous irradiation increased with LET: lithium and carbon ions induced about two- and four-fold higher yields of dicentrics than protons. The induction of dicentrics is, however, affected by µm-scale, too: focusing 20 lithium ions or 451 protons per spot on a 10.6 μm grid induced two or three times more dicentrics, respectively, than a

  12. Laue-DIC: a new method for improved stress field measurements at the micrometer scale

    PubMed Central

    Petit, J.; Castelnau, O.; Bornert, M.; Zhang, F. G.; Hofmann, F.; Korsunsky, A. M.; Faurie, D.; Le Bourlot, C.; Micha, J. S.; Robach, O.; Ulrich, O.

    2015-01-01

    A better understanding of the effective mechanical behavior of polycrystalline materials requires an accurate knowledge of the behavior at a scale smaller than the grain size. The X-ray Laue microdiffraction technique available at beamline BM32 at the European Synchrotron Radiation Facility is ideally suited for probing elastic strains (and associated stresses) in deformed polycrystalline materials with a spatial resolution smaller than a micrometer. However, the standard technique used to evaluate local stresses from the distortion of Laue patterns lacks accuracy for many micromechanical applications, mostly due to (i) the fitting of Laue spots by analytical functions, and (ii) the necessary comparison of the measured pattern with the theoretical one from an unstrained reference specimen. In the present paper, a new method for the analysis of Laue images is presented. A Digital Image Correlation (DIC) technique, which is essentially insensitive to the shape of Laue spots, is applied to measure the relative distortion of Laue patterns acquired at two different positions on the specimen. The new method is tested on an in situ deformed Si single-crystal, for which the prescribed stress distribution has been calculated by finite-element analysis. It is shown that the new Laue-DIC method allows determination of local stresses with a strain resolution of the order of 10−5. PMID:26134802

  13. Correlation between micrometer-scale ripple alignment and atomic-scale crystallographic orientation of monolayer graphene

    SciTech Connect

    Choi, Jin Sik; Chang, Young Jun; Woo, Sungjong; Son, Young-Woo; Park, Yeonggu; Lee, Mi Jung; Byun, Ik-Su; Kim, Jin-Soo; Choi, Choon-Gi; Bostwick, Aaron; Rotenberg, Eli; Park, Bae Ho

    2014-12-01

    Deformation normal to the surface is intrinsic in two-dimensional materials due to phononic thermal fluctuations at finite temperatures. Graphene's negative thermal expansion coefficient is generally explained by such an intrinsic property. Recently, friction measurements on graphene exfoliated on a silicon oxide surface revealed an anomalous anisotropy whose origin was believed to be the formation of ripple domains. Here, we uncover the atomistic origin of the observed friction domains using a cantilever torsion microscopy in conjunction with angle-resolved photoemission spectroscopy. We experimentally demonstrate that ripples on graphene are formed along the zigzag direction of the hexagonal lattice. The formation of zigzag directional ripple is consistent with our theoretical model that takes account of the atomic-scale bending stiffness of carbon-carbon bonds and the interaction of graphene with the substrate. Lastly, the correlation between micrometer-scale ripple alignment and atomic-scale arrangement of exfoliated monolayer graphene is first discovered and suggests a practical tool for measuring lattice orientation of graphene.

  14. Correlation between micrometer-scale ripple alignment and atomic-scale crystallographic orientation of monolayer graphene

    DOE PAGES

    Choi, Jin Sik; Chang, Young Jun; Woo, Sungjong; ...

    2014-12-01

    Deformation normal to the surface is intrinsic in two-dimensional materials due to phononic thermal fluctuations at finite temperatures. Graphene's negative thermal expansion coefficient is generally explained by such an intrinsic property. Recently, friction measurements on graphene exfoliated on a silicon oxide surface revealed an anomalous anisotropy whose origin was believed to be the formation of ripple domains. Here, we uncover the atomistic origin of the observed friction domains using a cantilever torsion microscopy in conjunction with angle-resolved photoemission spectroscopy. We experimentally demonstrate that ripples on graphene are formed along the zigzag direction of the hexagonal lattice. The formation of zigzagmore » directional ripple is consistent with our theoretical model that takes account of the atomic-scale bending stiffness of carbon-carbon bonds and the interaction of graphene with the substrate. Lastly, the correlation between micrometer-scale ripple alignment and atomic-scale arrangement of exfoliated monolayer graphene is first discovered and suggests a practical tool for measuring lattice orientation of graphene.« less

  15. Correlation between micrometer-scale ripple alignment and atomic-scale crystallographic orientation of monolayer graphene

    PubMed Central

    Choi, Jin Sik; Chang, Young Jun; Woo, Sungjong; Son, Young-Woo; Park, Yeonggu; Lee, Mi Jung; Byun, Ik-Su; Kim, Jin-Soo; Choi, Choon-Gi; Bostwick, Aaron; Rotenberg, Eli; Park, Bae Ho

    2014-01-01

    Deformation normal to the surface is intrinsic in two-dimensional materials due to phononic thermal fluctuations at finite temperatures. Graphene's negative thermal expansion coefficient is generally explained by such an intrinsic property. Recently, friction measurements on graphene exfoliated on a silicon oxide surface revealed an anomalous anisotropy whose origin was believed to be the formation of ripple domains. Here, we uncover the atomistic origin of the observed friction domains using a cantilever torsion microscopy in conjunction with angle-resolved photoemission spectroscopy. We experimentally demonstrate that ripples on graphene are formed along the zigzag direction of the hexagonal lattice. The formation of zigzag directional ripple is consistent with our theoretical model that takes account of the atomic-scale bending stiffness of carbon-carbon bonds and the interaction of graphene with the substrate. The correlation between micrometer-scale ripple alignment and atomic-scale arrangement of exfoliated monolayer graphene is first discovered and suggests a practical tool for measuring lattice orientation of graphene. PMID:25434431

  16. Correlation between micrometer-scale ripple alignment and atomic-scale crystallographic orientation of monolayer graphene

    NASA Astrophysics Data System (ADS)

    Choi, Jin Sik; Chang, Young Jun; Woo, Sungjong; Son, Young-Woo; Park, Yeonggu; Lee, Mi Jung; Byun, Ik-Su; Kim, Jin-Soo; Choi, Choon-Gi; Bostwick, Aaron; Rotenberg, Eli; Park, Bae Ho

    2014-12-01

    Deformation normal to the surface is intrinsic in two-dimensional materials due to phononic thermal fluctuations at finite temperatures. Graphene's negative thermal expansion coefficient is generally explained by such an intrinsic property. Recently, friction measurements on graphene exfoliated on a silicon oxide surface revealed an anomalous anisotropy whose origin was believed to be the formation of ripple domains. Here, we uncover the atomistic origin of the observed friction domains using a cantilever torsion microscopy in conjunction with angle-resolved photoemission spectroscopy. We experimentally demonstrate that ripples on graphene are formed along the zigzag direction of the hexagonal lattice. The formation of zigzag directional ripple is consistent with our theoretical model that takes account of the atomic-scale bending stiffness of carbon-carbon bonds and the interaction of graphene with the substrate. The correlation between micrometer-scale ripple alignment and atomic-scale arrangement of exfoliated monolayer graphene is first discovered and suggests a practical tool for measuring lattice orientation of graphene.

  17. Different freezing behavior of millimeter- and micrometer-scaled (NH₄)₂SO₄/H₂O droplets.

    PubMed

    Bogdan, A; Molina, M J; Tenhu, H; Mayer, E; Bertel, E; Loerting, T

    2011-01-26

    Although the freezing of aqueous solutions is important for nature and different branches of science and freeze-applications, our understanding of the freezing process is not complete. For example, numerous measurements of micrometer-scaled (NH(4))(2)SO(4)/H(2)O droplets report one freezing event below the eutectic point. However, measurements of larger millimeter-scaled droplets reveal two freezing events: the freezing out of ice and subsequent freezing of a residual freeze-concentrated solution. To resolve this apparent contradiction we performed numerous calorimetric measurements which indicate that the freezing of a residual solution of millimeter-scaled 5-38 wt% (NH(4))(2)SO(4) droplets occurs mainly between ∼ 210 and 225 K. We also find that micrometer-scaled droplets produce one freezing event which is within or in the vicinity of the ∼ 210-225 K region. This fact and the analysis of thermograms suggest that the residual solution of micrometer-scaled droplets may partly crystallize simultaneously with ice and partly transform to glass at T(g)≈172 K. Our results suggest for the first time that the size of (NH(4))(2)SO(4)/H(2)O droplets may affect the number of freezing events below the eutectic point.

  18. Micrometer-scale mixing with Pickering emulsions: biphasic reactions without stirring.

    PubMed

    Zhang, Wenjuan; Fu, Luman; Yang, Hengquan

    2014-02-01

    A general strategy that avoids stirring for organic/aqueous reactions involving solid catalysts is reported. The strategy involves converting a conventional biphasic system into a Pickering emulsion phase with micrometer-scale droplets ensuring good mixing. In test reactions, nitrotoluene reduction and epoxidation of allylic alcohols, the reaction efficiency is comparable to conventional stirrer-driven biphasic catalysis reaction systems. Short diffusion distances, arising from the compartmentalization of densely packed droplets, play an important role in boosting the reaction efficiency.

  19. Micrometer-Scale Ion Current Rectification at Polyelectrolyte Brush-Modified Micropipets.

    PubMed

    He, Xiulan; Zhang, Kailin; Li, Ting; Jiang, Yanan; Yu, Ping; Mao, Lanqun

    2017-02-01

    Here we report for the first time that ion current rectification (ICR) can be observed at the micrometer scale in symmetric electrolyte solution with polyimidazolium brush (PimB)-modified micropipets, which we call micrometer-scale ion current rectification (MICR). To qualitatively understand MICR, a three-layer model including a charged layer, an electrical double layer, and a bulk layer is proposed, which could also be extended to understanding ICR at the nanoscale. Based on this model, we propose that when charges in the charged layer are comparable with those in the bulk layer, ICR would occur regardless of whether the electrical double layers are overlapped. Finite element simulations based on the solution of Poisson and Nernst-Planck equations and in situ confocal laser scanning microscopy results qualitatively validate the experimental observations and the proposed three-layer model. Moreover, possible factors influencing MICR, including the length of PimB, electrolyte concentration, and the radius of the pipet, are investigated and discussed. This study successfully extends ICR to the micrometer scale and thus opens a new door to the development of ICR-based devices by taking advantage of ease-in-manipulation and designable surface chemistry of micropipets.

  20. Large-scale proton radiography with micrometer spatial resolution using femtosecond petawatt laser system

    SciTech Connect

    Wang, W. P.; Shen, B. F. Zhang, H.; Lu, X. M.; Wang, C.; Liu, Y. Q.; Yu, L. H.; Chu, Y. X.; Li, Y. Y.; Xu, T. J.; Zhang, H.; Zhai, S. H.; Leng, Y. X.; Liang, X. Y.; Li, R. X.; Xu, Z. Z.

    2015-10-15

    An image of dragonfly with many details is obtained by the fundamental property of the high-energy proton source on a femtosecond petawatt laser system. Equal imaging of the dragonfly and high spatial resolution on the micrometer scale are simultaneously obtained. The head, wing, leg, tail, and even the internal tissue structures are clearly mapped in detail by the proton beam. Experiments show that image blurring caused by multiple Coulomb scattering can be reduced to a certain extent and the spatial resolution can be increased by attaching the dragonfly to the RCFs, which is consistent with theoretical assumptions.

  1. Plasticity of Micrometer-Scale Single-Crystals in Compression: A Critical Review (PREPRINT)

    DTIC Science & Technology

    2008-10-01

    AFRL-RX-WP-TP-2008-4326 PLASTICITY OF MICROMETER-SCALE SINGLE- CRYSTALS IN COMPRESSION: A CRITICAL REVIEW (PREPRINT) Michael D. Uchic... Michael D. Uchic and Dennis M. Dimiduk (AFRL/RXLMD) Paul A. Shade (The Ohio State University) 5d. PROJECT NUMBER 4347 5e. TASK NUMBER RG 5f...a critical review    Michael  D. Uchic1, Paul A. Shade2, and Dennis M. Dimiduk1    1 Air Force Research Laboratory, Materials & Manufacturing

  2. In Vivo Penetration Mechanics and Mechanical Properties of Mouse Brain Tissue at Micrometer Scales

    PubMed Central

    Sharp, Andrew A.; Ortega, Alicia M.; Restrepo, Diego; Curran-Everett, Douglas; Gall, Ken

    2010-01-01

    Substantial advancement in the understanding of the neuronal basis of behavior and the treatment of neurological disorders has been achieved via the implantation of various devices into the brain. To design and optimize the next generation of neuronal implants while striving to minimize tissue damage, it is necessary to understand the mechanics of probe insertion at relevant length scales. Unfortunately, a broad based understanding of brain-implant interactions at the necessary micrometer scales is largely missing. This paper presents a generalizable description of the micrometer scale penetration mechanics and material properties of mouse brain tissue in vivo. Cylindrical stainless steel probes were inserted into the cerebral cortex and olfactory bulb of mice. The effects of probe size, probe geometry, insertion rate, insertion location, animal age and the presence of the dura and pia on the resulting forces were measured continuously throughout probe insertion and removal. Material properties (modulus, cutting force, and frictional force) were extracted using mechanical analysis. The use of rigid, incompressible, cylindrical probes allows for a general understanding of how probe design and insertion methods influence the penetration mechanics of brain tissue in vivo that can be applied to the quantitative design of most future implantable devices. PMID:19224718

  3. Micrometer-scale fabrication of complex three dimensional lattice + basis structures in silicon

    SciTech Connect

    Burckel, D. Bruce; Resnick, Paul J.; Finnegan, Patrick S.; Sinclair, Michael B.; Davids, Paul S.

    2015-01-01

    A complementary metal oxide semiconductor (CMOS) compatible version of membrane projection lithography (MPL) for fabrication of micrometer-scale three-dimensional structures is presented. The approach uses all inorganic materials and standard CMOS processing equipment. In a single layer, MPL is capable of creating all 5 2D-Bravais lattices. Furthermore, standard semiconductor processing steps can be used in a layer-by-layer approach to create fully three dimensional structures with any of the 14 3D-Bravais lattices. The unit cell basis is determined by the projection of the membrane pattern, with many degrees of freedom for defining functional inclusions. Here we demonstrate several unique structural motifs, and characterize 2D arrays of unit cells with split ring resonators in a silicon matrix. The structures exhibit strong polarization dependent resonances and, for properly oriented split ring resonators (SRRs), coupling to the magnetic field of a normally incident transverse electromagnetic wave, a response unique to 3D inclusions.

  4. Opto-mechanical subsystem of a 10 micrometer wavelength receiver terminal. Waveguide laser local oscillator. Servo system

    NASA Technical Reports Server (NTRS)

    1975-01-01

    An engineering model opto-mechanical subsystem for a 10.6-micrometer laser heterodyne receiver is developed, and a CO2 waveguide local oscillator and servo electronics are provided for the receiver. Design goals are presented for the subsystems and overall package design is described. Thermal and mechanical distortion loading tests were performed and the results are included.

  5. A simple indentation device for measuring micrometer-scale tissue stiffness

    NASA Astrophysics Data System (ADS)

    Levental, I.; Levental, K. R.; Klein, E. A.; Assoian, R.; Miller, R. T.; Wells, R. G.; Janmey, P. A.

    2010-05-01

    Mechanical properties of cells and extracellular matrices are critical determinants of function in contexts including oncogenic transformation, neuronal synapse formation, hepatic fibrosis and stem cell differentiation. The size and heterogeneity of biological specimens and the importance of measuring their mechanical properties under conditions that resemble their environments in vivo present a challenge for quantitative measurement. Centimeter-scale tissue samples can be measured by commercial instruments, whereas properties at the subcellular (nm) scale are accessible by atomic force microscopy, optical trapping, or magnetic bead microrheometry; however many tissues are heterogeneous on a length scale between micrometers and millimeters which is not accessible to most current instrumentation. The device described here combines two commercially available technologies, a micronewton resolution force probe and a micromanipulator for probing soft biological samples at sub-millimeter spatial resolution. Several applications of the device are described. These include the first measurement of the stiffness of an intact, isolated mouse glomerulus, quantification of the inner wall stiffness of healthy and diseased mouse aortas, and evaluation of the lateral heterogeneity in the stiffness of mouse mammary glands and rat livers with correlation of this heterogeneity with malignant or fibrotic pathology as evaluated by histology.

  6. Constraints on Exotic Dipole-Dipole Couplings between Electrons at the Micrometer Scale.

    PubMed

    Kotler, Shlomi; Ozeri, Roee; Kimball, Derek F Jackson

    2015-08-21

    New constraints on exotic dipole-dipole interactions between electrons at the micrometer scale are established, based on a recent measurement of the magnetic interaction between two trapped 88Sr(+) ions. For light bosons (mass≤0.1  eV) we obtain a 90% confidence interval for an axial-vector-mediated interaction strength of |g(A)(e)g(A)(e)/4πℏc|≤1.2×10(-17). Assuming CPT invariance, this constraint is compared to that on anomalous electron-positron interactions, derived from positronium hyperfine spectroscopy. We find that the electron-electron constraint is 6 orders of magnitude more stringent than the electron-positron counterpart. Bounds on pseudoscalar-mediated interaction as well as on torsion gravity are also derived and compared with previous work performed at different length scales. Our constraints benefit from the high controllability of the experimental system which contained only two trapped particles. It therefore suggests a useful new platform for exotic particle searches, complementing other experimental efforts.

  7. Constraints on Exotic Dipole-Dipole Couplings between Electrons at the Micrometer Scale

    NASA Astrophysics Data System (ADS)

    Kotler, Shlomi; Ozeri, Roee; Kimball, Derek F. Jackson

    2015-08-01

    New constraints on exotic dipole-dipole interactions between electrons at the micrometer scale are established, based on a recent measurement of the magnetic interaction between two trapped 88Sr+ ions. For light bosons (mass≤0.1 eV ) we obtain a 90% confidence interval for an axial-vector-mediated interaction strength of |gAegAe/4 π ℏc | ≤1.2 ×10-17 . Assuming C P T invariance, this constraint is compared to that on anomalous electron-positron interactions, derived from positronium hyperfine spectroscopy. We find that the electron-electron constraint is 6 orders of magnitude more stringent than the electron-positron counterpart. Bounds on pseudoscalar-mediated interaction as well as on torsion gravity are also derived and compared with previous work performed at different length scales. Our constraints benefit from the high controllability of the experimental system which contained only two trapped particles. It therefore suggests a useful new platform for exotic particle searches, complementing other experimental efforts.

  8. IR and green femtosecond laser machining of heat sensitive materials for medical devices at micrometer scale

    NASA Astrophysics Data System (ADS)

    Stolberg, Klaus; Friedel, Susanna; Kremser, Bert; Roehner, Markus

    2014-03-01

    In medical device manufacturing there is an increasing interest to enhance machining of biocompatible materials on a micrometer scale. Obviously there is a trend to generate smaller device structures like cavities, slits or total size of the device to address new applications. Another trend points to surface modification, which allows controlling selective growth of defined biological cell types on medical implants. In both cases it is interesting to establish machining methods with minimized thermal impact, because biocompatible materials often show degradation of mechanical properties under thermal treatment. Typical examples for this effect is embrittlement of stainless steel at the edge of a cutting slit, which is caused by oxidation and phase change. Also for Nitinol (NiTi alloy) which is used as another stent material reduction of shape-memory behavior is known if cutting temperature is too high. For newest biodegradable materials like Polylactic acid (PLA) based polymers, lowest thermal impact is required due to PLA softening point (65°C) and melting temperature (~170 °C ). Laser machining with ultra-short pulse lasers is a solution for this problem. In our work we demonstrate a clean laser cut of NiTi and PLA based polymers with a high repetition-rate 1030 nm, 400-800 fs laser source at a pulse energy of up to 50 μJ and laser repetition rate of up to 500 kHz.

  9. Micrometer-scale fabrication of complex three dimensional lattice + basis structures in silicon

    DOE PAGES

    Burckel, D. Bruce; Resnick, Paul J.; Finnegan, Patrick S.; ...

    2015-01-01

    A complementary metal oxide semiconductor (CMOS) compatible version of membrane projection lithography (MPL) for fabrication of micrometer-scale three-dimensional structures is presented. The approach uses all inorganic materials and standard CMOS processing equipment. In a single layer, MPL is capable of creating all 5 2D-Bravais lattices. Furthermore, standard semiconductor processing steps can be used in a layer-by-layer approach to create fully three dimensional structures with any of the 14 3D-Bravais lattices. The unit cell basis is determined by the projection of the membrane pattern, with many degrees of freedom for defining functional inclusions. Here we demonstrate several unique structural motifs, andmore » characterize 2D arrays of unit cells with split ring resonators in a silicon matrix. The structures exhibit strong polarization dependent resonances and, for properly oriented split ring resonators (SRRs), coupling to the magnetic field of a normally incident transverse electromagnetic wave, a response unique to 3D inclusions.« less

  10. Micrometer scale contact lens movements imaged by ultra-high resolution optical coherence tomography

    PubMed Central

    Cui, Lele; Shen, Meixiao; Wang, Michael R.; Wang, Jianhua

    2011-01-01

    PURPOSE To dynamically evaluate contact lens movement and ocular surface shape using ultra-high resolution and ultra-long scan depth optical coherence tomography (OCT). DESIGN Clinical research study of a laboratory technique. METHODS Four different types of soft contact lenses were tested on the left eye of 10 subjects (6 males and 4 females). Lenses edges at primary gaze and temporal and nasal gazes were imaged by ultra-high resolution OCT. Excursion lag was obtained as the distance between the lens edge at primary gaze and immediately after the eye was quickly turned either nasally or temporally. The inferior lens edges were imaged continuously to track vertical movements during blinking. Ultra-long scan depth OCT provided quantifiable images of the ocular surface, and the contour was acquired using custom software. RESULTS Excursion lag at the horizontal meridian was 366 ± 134 μm at temporal gaze and 320 ± 137 μm at nasal gaze (P > .05). The lens uplift at the vertical meridian was 342 ± 155 μm after blinking. There were significant differences in horizontal lags and vertical movements among different lenses (P < .05). Horizontal lags were correlated with radii of curvatures and sagittal heights at 6- and 14- mm horizontal meridian radii (P < .05). The blink-induced lens uplift first lowered by 104 ± 8 μm, and then lifted 342 ± 155 μm after the blink. CONCLUSIONS Ultra-high resolution and ultra-long scan depth OCT can assess micrometer scale lens movements and ocular surface contours. Both lens design and ocular surface shape affected lens movements. PMID:21920493

  11. Monitoring micrometer-scale collagen organization in rat-tail tendon upon mechanical strain using second harmonic microscopy.

    PubMed

    Goulam Houssen, Y; Gusachenko, I; Schanne-Klein, M-C; Allain, J-M

    2011-07-28

    We continuously monitored the microstructure of a rat-tail tendon during stretch/relaxation cycles. To that purpose, we implemented a new biomechanical device that combined SHG imaging and mechanical testing modalities. This multi-scale experimental device enabled simultaneous visualization of the collagen crimp morphology at the micrometer scale and measurement of macroscopic strain-stress response. We gradually increased the ultimate strain of the cycles and showed that preconditioning mostly occurs in the first stretching. This is accompanied by an increase of the crimp period in the SHG image. Our results indicate that preconditioning is due to a sliding of microstructures at the scale of a few fibrils and smaller, that changes the resting length of the fascicle. This sliding can reverse on long time scales. These results provide a proof of concept that continuous SHG imaging performed simultaneously with mechanical assay allows analysis of the relationship between macroscopic response and microscopic structure of tissues.

  12. Estimation of local spatial scale

    NASA Technical Reports Server (NTRS)

    Watson, Andrew B.

    1987-01-01

    The concept of local scale asserts that for a given class of psychophysical measurements, performance at any two visual field locations is equated by magnifying the targets by the local scale associated with each location. Local scale has been hypothesized to be equal to cortical magnification or alternatively to the linear density of receptors or ganglion cells. Here, it is shown that it is possible to estimate local scale without prior knowledge about the scale or its physiological basis.

  13. In situ ion-beam-induced luminescence analysis for evaluating a micrometer-scale radio-photoluminescence glass dosimeter

    NASA Astrophysics Data System (ADS)

    Kawabata, Shunsuke; Kada, Wataru; Parajuli, Raj Kumar; Matsubara, Yoshinori; Sakai, Makoto; Miura, Kenta; Satoh, Takahiro; Koka, Masashi; Yamada, Naoto; Kamiya, Tomihiro; Hanaizumi, Osamu

    2016-06-01

    Micrometer-scale responses of radio-photoluminescence (RPL) glass dosimeters to focused ionized particle radiation were evaluated by combining ion-beam-induced luminescence (IBIL) and proton beam writing (PBW) using a 3 MeV focused proton microbeam. RPL phosphate glass dosimeters doped with ionic Ag or Cu activators at concentrations of 0.2 and 0.1% were fabricated, and their scintillation intensities were evaluated by IBIL spectroscopy under a PBW micropatterning condition. Compared with the Ag-doped dosimeter, the Cu-doped dosimeter was more tolerant of the radiation, while the peak intensity of its luminescence was lower, under the precise dose control of the proton microprobe. Proton-irradiated areas were successfully recorded using these dosimeters and their RPL centers were visualized under 375 nm ultraviolet light. The reproduction of the irradiated region by post-RPL imaging suggests that precise estimation of irradiation dose using microdosimeters can be accomplished by optimizing RPL glass dosimeters for various proton microprobe applications in organic material analysis and in micrometer-scale material modifications.

  14. One-Step Sub-micrometer-Scale Electrohydrodynamic Inkjet Three-Dimensional Printing Technique with Spontaneous Nanoscale Joule Heating.

    PubMed

    Zhang, Bin; Seong, Baekhoon; Lee, Jaehyun; Nguyen, VuDat; Cho, Daehyun; Byun, Doyoung

    2017-09-06

    A one-step sub-micrometer-scale electrohydrodynamic (EHD) inkjet three-dimensional (3D)-printing technique that is based on the drop-on-demand (DOD) operation for which an additional postsintering process is not required is proposed. Both the numerical simulation and the experimental observations proved that nanoscale Joule heating occurs at the interface between the charged silver nanoparticles (Ag-NPs) because of the high electrical contact resistance during the printing process; this is the reason why an additional postsintering process is not required. Sub-micrometer-scale 3D structures were printed with an above-35 aspect ratio via the use of the proposed printing technique; furthermore, it is evident that the designed 3D structures such as a bridge-like shape can be printed with the use of the proposed printing technique, allowing for the cost-effective fabrication of a 3D touch sensor and an ultrasensitive air flow-rate sensor. It is believed that the proposed one-step printing technique may replace the conventional 3D conductive-structure printing techniques for which a postsintering process is used because of its economic efficiency.

  15. Superresolution imaging reveals nanometer- and micrometer-scale spatial distributions of T-cell receptors in lymph nodes

    PubMed Central

    Hu, Ying S.; Cang, Hu; Lillemeier, Björn F.

    2016-01-01

    T cells become activated when T-cell receptors (TCRs) recognize agonist peptides bound to major histocompatibility complex molecules on antigen-presenting cells. T-cell activation critically relies on the spatiotemporal arrangements of TCRs on the plasma membrane. However, the molecular organizations of TCRs on lymph node-resident T cells have not yet been determined, owing to the diffraction limit of light. Here we visualized nanometer- and micrometer-scale TCR distributions in lymph nodes by light sheet direct stochastic optical reconstruction microscopy (dSTORM) and structured illumination microscopy (SIM). This dSTORM and SIM approach provides the first evidence, to our knowledge, of multiscale reorganization of TCRs during in vivo immune responses. We observed nanometer-scale plasma membrane domains, known as protein islands, on naïve T cells. These protein islands were enriched within micrometer-sized surface areas that we call territories. In vivo T-cell activation caused the TCR territories to contract, leading to the coalescence of protein islands and formation of stable TCR microclusters. PMID:27303041

  16. Optical Coherence Tomography Guided Laser Cochleostomy: Towards the Accuracy on Tens of Micrometer Scale

    PubMed Central

    Weller, Marcel; Wieser, Wolfgang; Huber, Robert; Raczkowsky, Jörg; Schipper, Jörg; Wörn, Heinz; Klenzner, Thomas

    2014-01-01

    Lasers have been proven to be precise tools for bone ablation. Applying no mechanical stress to the patient, they are potentially very suitable for microsurgery on fragile structures such as the inner ear. However, it remains challenging to control the laser-bone ablation without injuring embedded soft tissue. In this work, we demonstrate a closed-loop control of a short-pulsed CO2 laser to perform laser cochleostomy under the monitoring of an optical coherence tomography (OCT) system. A foresighted detection of the bone-endosteum-perilymph boundary several hundred micrometers before its exposure has been realized. Position and duration of the laser pulses are planned based on the residual bone thickness distribution. OCT itself is also used as a highly accurate tracking system for motion compensation between the target area and the optics. During ex vivo experimental evaluation on fresh porcine cochleae, the ablation process terminated automatically when the thickness of the residual tissue layer uniformly reached a predefined value. The shape of the resulting channel bottom converged to the natural curvature of the endosteal layer without injuring the critical structure. Preliminary measurements in OCT scans indicated that the mean absolute accuracy of the shape approximation was only around 20 μm. PMID:25295253

  17. Micrometer accuracy method for small-scale laser focal spot centroid measurement

    NASA Astrophysics Data System (ADS)

    Liu, Xiaoyan; Lu, Zhiwei; Wang, Xin; Ba, Dexin; Zhu, Chengyu

    2015-03-01

    The measurement of the centroid of small-scale laser focal spot is one of the most promising technologies for small-scale laser focal spot precise positioning. A method of two-dimensional scanning with CCD has been conducted to precisely measure the centroid of the small-scale laser focal spot (diameter in microns) by obtaining the change curve for gray value. The theoretical analysis is consistent with the experimental results.

  18. Micrometer-Scale Ballistic Transport of Electron Pairs in LaAlO3/SrTiO3 Nanowires

    NASA Astrophysics Data System (ADS)

    Tomczyk, Michelle; Cheng, Guanglei; Lee, Hyungwoo; Lu, Shicheng; Annadi, Anil; Veazey, Joshua P.; Huang, Mengchen; Irvin, Patrick; Ryu, Sangwoo; Eom, Chang-Beom; Levy, Jeremy

    2016-08-01

    High-mobility complex-oxide heterostructures and nanostructures offer new opportunities for extending the paradigm of quantum transport beyond the realm of traditional III-V or carbon-based materials. Recent quantum transport investigations with LaAlO3/SrTiO3 -based quantum dots reveal the existence of a strongly correlated phase in which electrons form spin-singlet pairs without becoming superconducting. Here, we report evidence for the micrometer-scale ballistic transport of electron pairs in quasi-1D LaAlO3/SrTiO3 nanowire cavities. In the paired phase, Fabry-Perot-like quantum interference is observed, in sync with conductance oscillations observed in the superconducting regime (at a zero magnetic field). Above a critical magnetic field Bp, the electron pairs unbind and the conductance oscillations shift with the magnetic field. These experimental observations extend the regime of ballistic electronic transport to strongly correlated phases.

  19. Filar Micrometer

    NASA Astrophysics Data System (ADS)

    Argyle, Bob; Argyle, R. W.

    The measurement of double stars is central to the theme of this book and there are many ways of doing this, but this chapter is dedicated to the use of the filar micrometer which has been used seriously since the time of William Herschel. For a thorough discussion of the history and development of the filar micrometer see the paper by Brooks(1991). Much of our knowledge of longer period visual binaries depends on micrometric measures over the last 200 years. The filar micrometer is by far the most well-known device for measuring double stars. Its design remains largely the same as the original instrument which was first applied to an astronomical telescope by the Englishman William Gascoigne (ca. 1620-1644) in the late 1630s. The aim is to use fine threads located in the focal plane of the telescope lens or mirror to measure the relative position of the fainter component of a double star with respect to the brighter, regarding the latter as fixed for this purpose. This is done by the measurement of the angle which the line joining the two stars makes with the N reference in the eyepiece and the angular separation of the fainter star (B) from the brighter (A) in seconds of arc. These quantities are usually known as theta ( θ ) and rho ( ρ ) respectively and are defined in Chap. 1 .

  20. Quantifying the Hierarchical Order in Self-Aligned Carbon Nanotubes from Atomic to Micrometer Scale.

    PubMed

    Meshot, Eric R; Zwissler, Darwin W; Bui, Ngoc; Kuykendall, Tevye R; Wang, Cheng; Hexemer, Alexander; Wu, Kuang Jen J; Fornasiero, Francesco

    2017-06-27

    Fundamental understanding of structure-property relationships in hierarchically organized nanostructures is crucial for the development of new functionality, yet quantifying structure across multiple length scales is challenging. In this work, we used nondestructive X-ray scattering to quantitatively map the multiscale structure of hierarchically self-organized carbon nanotube (CNT) "forests" across 4 orders of magnitude in length scale, from 2.0 Å to 1.5 μm. Fully resolved structural features include the graphitic honeycomb lattice and interlayer walls (atomic), CNT diameter (nano), as well as the greater CNT ensemble (meso) and large corrugations (micro). Correlating orientational order across hierarchical levels revealed a cascading decrease as we probed finer structural feature sizes with enhanced sensitivity to small-scale disorder. Furthermore, we established qualitative relationships for single-, few-, and multiwall CNT forest characteristics, showing that multiscale orientational order is directly correlated with number density spanning 10(9)-10(12) cm(-2), yet order is inversely proportional to CNT diameter, number of walls, and atomic defects. Lastly, we captured and quantified ultralow-q meridional scattering features and built a phenomenological model of the large-scale CNT forest morphology, which predicted and confirmed that these features arise due to microscale corrugations along the vertical forest direction. Providing detailed structural information at multiple length scales is important for design and synthesis of CNT materials as well as other hierarchically organized nanostructures.

  1. Effects of applied potential and the initial gap between electrodes on localized electrochemical deposition of micrometer copper columns

    NASA Astrophysics Data System (ADS)

    Wang, Fuliang; Xiao, Hongbin; He, Hu

    2016-05-01

    Micrometer copper columns were fabricated via a technology named localized electrochemical deposition (LECD). This paper studies the effects of applied potential and the initial gap between electrodes on the LECD process. The surface and cross sectional morphologies, as well as the average deposition rate were investigated to evaluate the quality of the deposited copper columns. Results demonstrated that the copper columns tended to be cylinder-shape with few voids inside at lower potential (<2.4 V). Whereas,the copper columns tended to be dendriform-shape with lots of voids inside at larger potential (>2.8 V). The average deposition rate increased with the raise of potential. In addition, the copper columns tended to be cylinder-shape with the initial gap between electrodes to be 10 μm or below. However, the copper columns tended to be cone-shape when the initial gap between electrodes became larger (35 μm or above). The number of voids inside the copper column and the average deposition rate both decreased with the increase of the initial gap. Moreover, the process of LECD under varied electric field has also been simulated using COMSOL software, and the formation of cylindrical and conical copper columns was further explained based on the electric field distribution at the cathode.

  2. Effects of applied potential and the initial gap between electrodes on localized electrochemical deposition of micrometer copper columns

    PubMed Central

    Wang, Fuliang; Xiao, Hongbin; He, Hu

    2016-01-01

    Micrometer copper columns were fabricated via a technology named localized electrochemical deposition (LECD). This paper studies the effects of applied potential and the initial gap between electrodes on the LECD process. The surface and cross sectional morphologies, as well as the average deposition rate were investigated to evaluate the quality of the deposited copper columns. Results demonstrated that the copper columns tended to be cylinder-shape with few voids inside at lower potential (<2.4 V). Whereas,the copper columns tended to be dendriform-shape with lots of voids inside at larger potential (>2.8 V). The average deposition rate increased with the raise of potential. In addition, the copper columns tended to be cylinder-shape with the initial gap between electrodes to be 10 μm or below. However, the copper columns tended to be cone-shape when the initial gap between electrodes became larger (35 μm or above). The number of voids inside the copper column and the average deposition rate both decreased with the increase of the initial gap. Moreover, the process of LECD under varied electric field has also been simulated using COMSOL software, and the formation of cylindrical and conical copper columns was further explained based on the electric field distribution at the cathode. PMID:27185742

  3. Measurement of Strain in Cardiac Myocytes at Micrometer Scale Based on Rapid Scanning Confocal Microscopy and Non-Rigid Image Registration.

    PubMed

    Lichter, J; Li, Hui; Sachse, Frank B

    2016-10-01

    Measurement of cell shortening is an important technique for assessment of physiology and pathophysiology of cardiac myocytes. Many types of heart disease are associated with decreased myocyte shortening, which is commonly caused by structural and functional remodeling. Here, we present a new approach for local measurement of 2-dimensional strain within cells at high spatial resolution. The approach applies non-rigid image registration to quantify local displacements and Cauchy strain in images of cells undergoing contraction. We extensively evaluated the approach using synthetic cell images and image sequences from rapid scanning confocal microscopy of fluorescently labeled isolated myocytes from the left ventricle of normal and diseased canine heart. Application of the approach yielded a comprehensive description of cellular strain including novel measurements of transverse strain and spatial heterogeneity of strain. Quantitative comparison with manual measurements of strain in image sequences indicated reliability of the developed approach. We suggest that the developed approach provides researchers with a novel tool to investigate contractility of cardiac myocytes at subcellular scale. In contrast to previously introduced methods for measuring cell shorting, the developed approach provides comprehensive information on the spatio-temporal distribution of 2-dimensional strain at micrometer scale.

  4. Controlling Strain Bursts and Avalanches at the Nano- to Micrometer Scale.

    PubMed

    Cui, Yinan; Po, Giacomo; Ghoniem, Nasr

    2016-10-07

    We demonstrate, through three-dimensional discrete dislocation dynamics simulations, that the complex dynamical response of nano- and microcrystals to external constraints can be tuned. Under load rate control, strain bursts are shown to exhibit scale-free avalanche statistics, similar to critical phenomena in many physical systems. For the other extreme of displacement rate control, strain burst response transitions to quasiperiodic oscillations, similar to stick-slip earthquakes. External load mode control is shown to enable a qualitative transition in the complex collective dynamics of dislocations from self-organized criticality to quasiperiodic oscillations.

  5. Micrometer-scale magnetic imaging of geological samples using a quantum diamond microscope

    NASA Astrophysics Data System (ADS)

    Glenn, D. R.; Fu, R. R.; Kehayias, P.; Le Sage, D.; Lima, E. A.; Weiss, B. P.; Walsworth, R. L.

    2017-08-01

    Remanent magnetization in geological samples may record the past intensity and direction of planetary magnetic fields. Traditionally, this magnetization is analyzed through measurements of the net magnetic moment of bulk millimeter to centimeter sized samples. However, geological samples are often mineralogically and texturally heterogeneous at submillimeter scales, with only a fraction of the ferromagnetic grains carrying the remanent magnetization of interest. Therefore, characterizing this magnetization in such cases requires a technique capable of imaging magnetic fields at fine spatial scales and with high sensitivity. To address this challenge, we developed a new instrument, based on nitrogen-vacancy centers in diamond, which enables direct imaging of magnetic fields due to both remanent and induced magnetization, as well as optical imaging, of room-temperature geological samples with spatial resolution approaching the optical diffraction limit. We describe the operating principles of this device, which we call the quantum diamond microscope (QDM), and report its optimized image-area-normalized magnetic field sensitivity (20 µTṡµm/Hz1/2), spatial resolution (5 µm), and field of view (4 mm), as well as trade-offs between these parameters. We also perform an absolute magnetic field calibration for the device in different modes of operation, including three-axis (vector) and single-axis (projective) magnetic field imaging. Finally, we use the QDM to obtain magnetic images of several terrestrial and meteoritic rock samples, demonstrating its ability to resolve spatially distinct populations of ferromagnetic carriers.

  6. Micrometer-Scale Spectral Properties of Howardite, Eucrite, and Diogenite Meteorites

    NASA Astrophysics Data System (ADS)

    Fraeman, Abigail; Ehlmann, Bethany; Liu, Yang; Greenberger, Rebecca; Wadhwa, Meenakshi

    2016-10-01

    We used visible-short wavelength infrared (VSWIR) imaging spectroscopy to survey the spectral diversity of the howardite, eucrite, and diogenite (HED) meteorite suite at 80-µm/pixel spatial scale. This group of meteorites is widely believed to originate from the asteroid Vesta. Our goal in this work is to contribute to understanding the petrologic diversity of the HED suite and the evolution of Vesta by (1) resolving spectral end members - i.e., spectra of the mineral constituents of Vesta— for use in interpretation of infrared remote sensing data from the Dawn spacecraft, (2) locating rare phases that can be examined using detailed analytical techniques, and (3) non-destructively and rapidly classifying large numbers of meteorites, including estimating their modal mineralogy within a petrographic context. We analyzed 11 howardite, 8 eucrite, and 9 diogenite fragments using JPL's Ultra-Compact Imaging Spectrometer (UCIS). We identified four major classes of materials based on VSWIR absorptions that include pyroxenes, olivines, Fe-bearing feldspars, and glass-bearing/featureless materials. There is significant HED spectral diversity within the pyroxene class at the microscale. On the whole, band centers are consistent with previous measurements of bulk HED spectra, although there are some intriguing trends that become apparent at this spatial resolution. In the howardite and eucrite samples, the positions of BI and BII centers of single pixel pyroxene spectra, which are controlled primarily by Fe- and Ca-content, plot mostly within established fields of bulk howardite and eucrite spectra. The positions differ from established centers for diogenites, however, and there appear to be two spectral classes within this field. Future work with spatially coregistered SEM/EDS will determine whether these differences are due to compositional differences, the effects of impact shock, or sub-pixel mixtures of multiple phases. Olivine is a rare phase in howardites and

  7. Using active colloids as machines to weave and braid on the micrometer scale.

    PubMed

    Goodrich, Carl P; Brenner, Michael P

    2017-01-10

    Controlling motion at the microscopic scale is a fundamental goal in the development of biologically inspired systems. We show that the motion of active, self-propelled colloids can be sufficiently controlled for use as a tool to assemble complex structures such as braids and weaves out of microscopic filaments. Unlike typical self-assembly paradigms, these structures are held together by geometric constraints rather than adhesive bonds. The out-of-equilibrium assembly that we propose involves precisely controlling the 2D motion of active colloids so that their path has a nontrivial topology. We demonstrate with proof-of-principle Brownian dynamics simulations that, when the colloids are attached to long semiflexible filaments, this motion causes the filaments to braid. The ability of the active particles to provide sufficient force necessary to bend the filaments into a braid depends on a number of factors, including the self-propulsion mechanism, the properties of the filament, and the maximum curvature in the braid. Our work demonstrates that nonequilibrium assembly pathways can be designed using active particles.

  8. Using active colloids as machines to weave and braid on the micrometer scale

    PubMed Central

    Goodrich, Carl P.; Brenner, Michael P.

    2017-01-01

    Controlling motion at the microscopic scale is a fundamental goal in the development of biologically inspired systems. We show that the motion of active, self-propelled colloids can be sufficiently controlled for use as a tool to assemble complex structures such as braids and weaves out of microscopic filaments. Unlike typical self-assembly paradigms, these structures are held together by geometric constraints rather than adhesive bonds. The out-of-equilibrium assembly that we propose involves precisely controlling the 2D motion of active colloids so that their path has a nontrivial topology. We demonstrate with proof-of-principle Brownian dynamics simulations that, when the colloids are attached to long semiflexible filaments, this motion causes the filaments to braid. The ability of the active particles to provide sufficient force necessary to bend the filaments into a braid depends on a number of factors, including the self-propulsion mechanism, the properties of the filament, and the maximum curvature in the braid. Our work demonstrates that nonequilibrium assembly pathways can be designed using active particles. PMID:28034922

  9. Influence of loading control on strain bursts and dislocation avalanches at the nanometer and micrometer scale

    NASA Astrophysics Data System (ADS)

    Cui, Yinan; Po, Giacomo; Ghoniem, Nasr

    2017-02-01

    Through three-dimensional discrete dislocation dynamics simulations, we show that by tuning the mode of external loading, the collective dynamics of dislocations undergo a transition from driven avalanches under stress control to quasiperiodic oscillations under strain control. We directly correlate measured intermittent plastic events with internal dislocation activities and collective dynamics. Under different loading modes, the roles of the weakest dislocation source and the defect population trend are significantly different. This finding raises new possibilities of controlling correlated dislocation activities and obtaining a low defect density in nanostructured devices by tuning external constraints. In addition, the effect of machine stiffness comes to light. The statistical analysis of the burst magnitude is revisited and carefully discussed. Self-organized criticality and scale-free statistics of strain bursts are obeyed under stress control. However, this behavior is shown to break down under strain control. Rapid stress drops under pure strain control force truncation of dislocation avalanches, leading to a dynamical transition to quasiperiodic oscillations.

  10. Using active colloids as machines to weave and braid on the micrometer scale

    NASA Astrophysics Data System (ADS)

    Goodrich, Carl P.; Brenner, Michael P.

    2017-01-01

    Controlling motion at the microscopic scale is a fundamental goal in the development of biologically inspired systems. We show that the motion of active, self-propelled colloids can be sufficiently controlled for use as a tool to assemble complex structures such as braids and weaves out of microscopic filaments. Unlike typical self-assembly paradigms, these structures are held together by geometric constraints rather than adhesive bonds. The out-of-equilibrium assembly that we propose involves precisely controlling the 2D motion of active colloids so that their path has a nontrivial topology. We demonstrate with proof-of-principle Brownian dynamics simulations that, when the colloids are attached to long semiflexible filaments, this motion causes the filaments to braid. The ability of the active particles to provide sufficient force necessary to bend the filaments into a braid depends on a number of factors, including the self-propulsion mechanism, the properties of the filament, and the maximum curvature in the braid. Our work demonstrates that nonequilibrium assembly pathways can be designed using active particles.

  11. Sub-Micrometer Scale Minor Element Mapping in Interplanetary Dust Particles: A Test for Stratospheric Contamination

    NASA Technical Reports Server (NTRS)

    Flynn, G. J.; Keller, L. P.; Sutton, S. R.

    2004-01-01

    Combined X-ray microprobe (XRM), energy dispersive x-ray fluorescence using a Transmission Electron Microscope (TEM), and electron microprobe measurements have determined that the average bulk chemical composition of the interplanetary dust particles (IDPs) collected from the Earth s stratosphere is enriched relative to the CI meteorite composition by a factor of 2 to 4 for carbon and for the moderately volatile elements Na, K, P, Mn, Cu, Zn, Ga, Ge, and Se, and enriched to approximately 30 times CI for Br. However, Jessberger et al., who have reported similar bulk enrichments using Proton Induced X-ray Emission (PIXE), attribute the enrichments to contamination by meteor-derived atmospheric aerosols during the several weeks these IDPs reside in the Earth s atmosphere prior to collection. Using scanning Auger spectroscopy, a very sensitive surface analysis technique, Mackinnon and Mogk have observed S contamination on the surface of IDPs, presumably due to the accretion of sulfate aerosols during stratospheric residence. But the S-rich layer they detected was so thin (approximately 100 angstroms thick) that the total amount of S on the surface was too small to significantly perturb the bulk S-content of a chondritic IDP. Stephan et al. provide support for the contamination hypothesis by reporting the enrichment of Br on the edges of the IDPs using Time-of-Flight Secondary-Ion Mass-Spectrometry (TOFSIMS), but TOF-SIMS is notorious for producing false edge-effects, particularly on irregularly-shaped samples like IDPs. Sutton et al. mapped the spatial distribution of Fe, Ni, Zn, Br, and Sr, at the approximately 2 m scale, in four IDPs using element-specific x-ray fluorescence (XRF) computed microtomography. They found the moderately volatile elements Zn and Br, although spatially inhomogeneous, were not concentrated on the surface of any of the IDPs they examined, suggesting that the Zn and the Br enrichments in the IDPs are not due to contamination during

  12. Sub-Micrometer Scale Minor Element Mapping in Interplanetary Dust Particles: A Test for Stratospheric Contamination

    NASA Technical Reports Server (NTRS)

    Flynn, G. J.; Keller, L. P.; Sutton, S. R.

    2004-01-01

    Combined X-ray microprobe (XRM), energy dispersive x-ray fluorescence using a Transmission Electron Microscope (TEM), and electron microprobe measurements have determined that the average bulk chemical composition of the interplanetary dust particles (IDPs) collected from the Earth s stratosphere is enriched relative to the CI meteorite composition by a factor of 2 to 4 for carbon and for the moderately volatile elements Na, K, P, Mn, Cu, Zn, Ga, Ge, and Se, and enriched to approximately 30 times CI for Br. However, Jessberger et al., who have reported similar bulk enrichments using Proton Induced X-ray Emission (PIXE), attribute the enrichments to contamination by meteor-derived atmospheric aerosols during the several weeks these IDPs reside in the Earth s atmosphere prior to collection. Using scanning Auger spectroscopy, a very sensitive surface analysis technique, Mackinnon and Mogk have observed S contamination on the surface of IDPs, presumably due to the accretion of sulfate aerosols during stratospheric residence. But the S-rich layer they detected was so thin (approximately 100 angstroms thick) that the total amount of S on the surface was too small to significantly perturb the bulk S-content of a chondritic IDP. Stephan et al. provide support for the contamination hypothesis by reporting the enrichment of Br on the edges of the IDPs using Time-of-Flight Secondary-Ion Mass-Spectrometry (TOFSIMS), but TOF-SIMS is notorious for producing false edge-effects, particularly on irregularly-shaped samples like IDPs. Sutton et al. mapped the spatial distribution of Fe, Ni, Zn, Br, and Sr, at the approximately 2 m scale, in four IDPs using element-specific x-ray fluorescence (XRF) computed microtomography. They found the moderately volatile elements Zn and Br, although spatially inhomogeneous, were not concentrated on the surface of any of the IDPs they examined, suggesting that the Zn and the Br enrichments in the IDPs are not due to contamination during

  13. Micrometer-Scale Physical Structure and Microbial Composition of Soil Macroaggregates

    SciTech Connect

    Bailey, Vanessa L.; McCue, Lee Ann; Fansler, Sarah J.; Boyanov, Maxim I.; DeCarlo, F.; Kemner, Kenneth M.; Konopka, Allan

    2013-10-01

    Soil macroaggregates are discrete, separable units of soil that we hypothesize contain smaller assemblages of microorganisms than bulk soil, and represent a scale potentially consistent with naturally occurring microbial communities. We posed two questions to explore microbial community composition in the context of the macroaggregate: 1) Is there a relationship between macroaggregate physical structure and microbial community composition in individual macroaggregates? And, 2) How similar are the bacterial communities in individual sub-millimeter soil macroaggregates sampled from the same 5-cm core? To address these questions, individual macroaggregates of three arbitrary size classes (250–425, 425–841, and 841–1000 μm) were sampled from a grassland field. The physical structures of 14 individual macroaggregates were characterized using synchrotron-radiation based transmission X-ray tomography, revealing that a greater proportion of the pore space in the small- and medium-sized macroaggregates is as relatively smaller pores, resulting in greater overall porosity and pore–mineral interface area in these smaller macroaggregates. Microbial community composition was characterized using 16S rRNA pyrosequencing data. Rarefaction analyses indicated that the membership of each macroaggregate was sufficiently sampled with only a few thousand sequences; in addition, the community membership varied widely between macroaggregates and the structure varied from those communities strongly dominated by a few phylotypes to communities that were evenly distributed among several phylotypes. We found no strong relationship of physical structure with community membership; this may be due to the low number of aggregates (10) for which we have both physical and biological data. Our results do support our initial expectation that individual macroaggregate communities were significantly less diverse than bulk soil from the same grassland field site.

  14. Sub-micrometer scale minor element mapping in interplanetary dust particles: a test for stratospheric contamination

    SciTech Connect

    Flynn, G.J.; Keller, L.P.; Sutton, S.R.

    2006-12-11

    We mapped the spatial distribution of minor elements including K, Mn, and Zn in 3 IDPs and found no evidence for the surface coatings (rims) of these elements that would be expected if the enrichments previously reported were due to contamination. Combined X-ray microprobe (XRM), energy dispersive x-ray fluorescence using a Transmission Electron Microscope (TEM), and electron microprobe measurements have determined that the average bulk chemical composition of the interplanetary dust particles (IDPs) collected from the Earth's stratosphere is enriched relative to the CI meteorite composition by a factor of 2 to 4 for carbon and for the moderately volatile elements Na, K, P, Mn, Cu, Zn, Ga, Ge, and Se, and enriched to {approx}30 times CI for Br. However, Jessberger et al., who have reported similar bulk enrichments using Proton Induced X-ray Emission (PIXE), attribute the enrichments to contamination by meteor-derived atmospheric aerosols during the several weeks these IDPs reside in the Earth's atmosphere prior to collection. Using scanning Auger spectroscopy, a very sensitive surface analysis technique, Mackinnon and Mogk have observed S contamination on the surface of IDPs, presumably due to the accretion of sulfate aerosols during stratospheric residence. But the S-rich layer they detected was so thin ({approx}100 angstroms thick) that the total amount of S on the surface was too small to significantly perturb the bulk S-content of a chondritic IDP. Stephan et al. provide support for the contamination hypothesis by reporting the enrichment of Br on the edges of the IDPs using Time-of-Flight Secondary-Ion Mass-Spectrometry (TOF-SIMS), but TOF-SIMS is notorious for producing false edge-effects, particularly on irregularly-shaped samples like IDPs. Sutton et al. mapped the spatial distribution of Fe, Ni, Zn, Br, and Sr, at the {approx}2 {micro}m scale, in four IDPs using element-specific x-ray fluorescence (XRF) computed microtomography. They found the moderately

  15. Highly Selective Cerebral ATP Assay Based on Micrometer Scale Ion Current Rectification at Polyimidazolium-Modified Micropipettes.

    PubMed

    Zhang, Kailin; He, Xiulan; Liu, Yang; Yu, Ping; Fei, Junjie; Mao, Lanqun

    2017-06-20

    Development of new principles and methods for cerebral ATP assay is highly imperative not only for determining ATP dynamics in brain but also for understanding physiological and pathological processes related to ATP. Herein, we for the first time demonstrate that micrometer scale ion current rectification (MICR) at a polyimidazolium brush-modified micropipette can be used as the signal transduction output for the cerebral ATP assay with a high selectivity. The rationale for ATP assay is essentially based on the competitive binding ability between positively charged polyimidazolium and ATP toward negatively charged ATP aptamer. The method is well responsive to ATP with a good linearity within a concentration range from 5 nM to 100 nM, and high selectivity toward ATP. These properties essentially enable the method to determine the cerebral ATP by combining in vivo microdialysis. The basal dialysate level of ATP in rat brain cortex is determined to be 11.32 ± 2.36 nM (n = 3). This study demonstrates that the MICR-based sensors could be potentially used for monitoring neurochemicals in cerebral systems.

  16. Site-specific immobilization and micrometer and nanometer scale photopatterning of yellow fluorescent protein on glass surfaces.

    PubMed

    Reynolds, Nicholas P; Tucker, Jaimey D; Davison, Paul A; Timney, John A; Hunter, C Neil; Leggett, Graham J

    2009-01-28

    A simple method is described for the site-specific attachment of yellow fluorescent protein (YFP) to glass surfaces on length scales ranging from tens of micrometers to ca. 200 nm. 3-Mercaptopropyl(triethoxy silane) is adsorbed onto a glass substrate and subsequently derivatized using a maleimide-functionalized oligomer of ethylene glycol. The resulting protein-resistant surface is patterned by exposure to UV light, causing photochemical degradation of the oligo(ethylene glycol) units to yield aldehyde groups in exposed regions. These are covalently bound to N-(5-amino-1-carboxypentyl)iminoacetic acid, yielding a nitrilotriacetic acid (NTA)-functionalized surface, which following complexation with Ni(2+), is coupled to His-tagged YFP. Using scanning near-field photolithography, in which a UV laser coupled to a scanning near-field optical microscope is utilized as the light source for photolithography, it is possible to fabricate lines of protein smaller than 200 nm, in which the biomolecules remain strongly optically active, facilitating the acquisition of diffraction-limited fluorescence images by confocal microscopy.

  17. Effect of Micrometer-Scale Roughness of the Surface of Ti6Al4V Pedicle Screws in Vitro and in Vivo

    PubMed Central

    Schwartz, Zvi; Raz, Perry; Zhao, Ge; Barak, Yael; Tauber, Michael; Yao, Hai; Boyan, Barbara D.

    2008-01-01

    Background: Titanium implants that have been grit-blasted and acid-etched to produce a rough microtopography support more bone integration than do smooth-surfaced implants. In vitro studies have suggested that this is due to a stimulatory effect on osteoblasts. It is not known if grit-blasted and acid-etched Ti6Al4V implants also stimulate osteoblasts and increase bone formation clinically. In this study, we examined the effects of micrometer-scale-structured Ti6Al4V surfaces on cell responses in vitro and on tissue responses in vivo. Methods: Ti6Al4V disks were either machined to produce smooth surfaces with an average roughness (Ra) of 0.2 μm or grit-blasted, resulting in an Ra of 2.0, 3.0, or 3.3 μm. Human osteoblast-like cells were cultured on the disks and on tissue culture polystyrene. The cell number, markers of osteoblast differentiation, and levels of local factors in the conditioned media were determined at confluence. In addition, Ti6Al4V pedicle screws with smooth or rough surfaces were implanted into the L4 and L5 vertebrae of fifteen two-year-old sheep. Osteointegration was evaluated at twelve weeks with histomorphometry and on the basis of removal torque. Results: The cell numbers on the Ti6Al4V surfaces were lower than those on the tissue culture polystyrene; the effect was greatest on the roughest surface. The alkaline-phosphatase-specific activity of cell lysates was decreased in a surface-dependent manner, whereas osteocalcin, prostaglandin E2, transforming growth factor-β1, and osteoprotegerin levels were higher on the rough surfaces. Bone-implant contact was greater around the rough-surfaced Ti6Al4V screws, and the torque needed to remove the rough screws from the bone was more than twice that required to remove the smooth screws. Conclusions: Increased micrometer-scale surface roughness increases osteoblast differentiation and local factor production in vitro, which may contribute to increased bone formation and osteointegration in vivo

  18. In situ structural characterization of ageing kinetics in aluminum alloy 2024 across angstrom-to-micrometer length scales

    SciTech Connect

    Zhang, Fan; Levine, Lyle E.; Allen, Andrew J.; Campbell, Carelyn E.; Creuziger, Adam A.; Kazantseva, Nataliya; Ilavsky, Jan

    2016-06-01

    The precipitate structure and precipitation kinetics in an Al-Cu-Mg alloy (AA2024) aged at 190 °C, 208 °C, and 226 °C have been studied using ex situ Transmission Electron Microscopy (TEM) and in situ synchrotron-based, combined ultra-small angle X-ray scattering, small angle X-ray scattering (SAXS), and wide angle X-ray scattering (WAXS) across a length scale from sub-Angstrom to several micrometers. TEM brings information concerning the nature, morphology, and size of the precipitates while SAXS and WAXS provide qualitative and quantitative information concerning the time-dependent size and volume fraction evolution of the precipitates at different stages of the precipitation sequence. Within the experimental time resolution, precipitation at these ageing temperatures involves dissolution of nanometer-sized small clusters and formation of the planar S phase precipitates. Using a three-parameter scattering model constructed on the basis of TEM results, we established the temperature-dependent kinetics for the cluster-dissolution and S-phase formation processes simultaneously. These two processes are shown to have different kinetic rates, with the cluster-dissolution rate approximately double the S-phase formation rate. We identified a dissolution activation energy at (149.5 ± 14.6) kJ mol-1, which translates to (1.55 ± 0.15) eV/atom, as well as an activation energy for the formation of S precipitates at (129.2 ± 5.4) kJ mol-1, i.e. (1.33 ± 0.06) eV/atom. Importantly, the SAXS/WAXS results show the absence of an intermediate Guinier-Preston Bagaryatsky 2 (GPB2)/S" phase in the samples under the experimental ageing conditions. These results are further validated by precipitation simulations that are based on Langer-Schwartz theory and a Kampmann-Wagner numerical method.

  19. Micrometer scale guidance of mesenchymal stem cells to form structurally oriented large-scale tissue engineered cartilage.

    PubMed

    Chou, Chih-Ling; Rivera, Alexander L; Williams, Valencia; Welter, Jean F; Mansour, Joseph M; Drazba, Judith A; Sakai, Takao; Baskaran, Harihara

    2017-09-15

    Current clinical methods to treat articular cartilage lesions provide temporary relief of the symptoms but fail to permanently restore the damaged tissue. Tissue engineering, using mesenchymal stem cells (MSCs) combined with scaffolds and bioactive factors, is viewed as a promising method for repairing cartilage injuries. However, current tissue engineered constructs display inferior mechanical properties compared to native articular cartilage, which could be attributed to the lack of structural organization of the extracellular matrix (ECM) of these engineered constructs in comparison to the highly oriented structure of articular cartilage ECM. We previously showed that we can guide MSCs undergoing chondrogenesis to align using microscale guidance channels on the surface of a two-dimensional (2-D) collagen scaffold, which resulted in the deposition of aligned ECM within the channels and enhanced mechanical properties of the constructs. In this study, we developed a technique to roll 2-D collagen scaffolds containing MSCs within guidance channels in order to produce a large-scale, three-dimensional (3-D) tissue engineered cartilage constructs with enhanced mechanical properties compared to current constructs. After rolling the MSC-scaffold constructs into a 3-D cylindrical structure, the constructs were cultured for 21days under chondrogenic culture conditions. The microstructure architecture and mechanical properties of the constructs were evaluated using imaging and compressive testing. Histology and immunohistochemistry of the constructs showed extensive glycosaminoglycan (GAG) and collagen type II deposition. Second harmonic generation imaging and Picrosirius red staining indicated alignment of neo-collagen fibers within the guidance channels of the constructs. Mechanical testing indicated that constructs containing the guidance channels displayed enhanced compressive properties compared to control constructs without these channels. In conclusion, using a novel

  20. Manipulation of the Wettability of Surfaces on the 0.1 to 1-Micrometer Scale Through Micromachining and Molecular Self-Assembly

    NASA Astrophysics Data System (ADS)

    Abbott, Nicholas L.; Folkers, John P.; Whitesides, George M.

    1992-09-01

    Micromachining allows the formation of micrometer-sized regions of bare gold on the surface of a gold film supporting a self-assembled monolayer (SAM) of alkanethiolate. A second SAM forms on the micromachined surfaces when the entire system-the remaining undisturbed gold-supported SAM and the micromachined features of bare gold-is exposed to a solution of dialkyl disulfide. By preparing an initial hydrophilic SAM from HS(CH_2)15 COOH, micromachining features into this SAM, and covering these features with a hydrophobic SAM formed from [CH_3(CH_2)11S]_2, it is possible to construct micrometer-scale hydrophobic lines in a hydrophilic surface. These lines provide new structures with which to manipulate the shapes of liquid drops.

  1. Efficient large volume electroporation of dendritic cells through micrometer scale manipulation of flow in a disposable polymer chip.

    PubMed

    Selmeczi, David; Hansen, Thomas S; Met, Ozcan; Svane, Inge Marie; Larsen, Niels B

    2011-04-01

    We present a hybrid chip of polymer and stainless steel designed for high-throughput continuous electroporation of cells in suspension. The chip is constructed with two parallel stainless steel mesh electrodes oriented perpendicular to the liquid flow. The relatively high hydrodynamic resistance of the micrometer sized holes in the meshes compared to the main channel enforces an almost homogeneous flow velocity between the meshes. Thereby, very uniform electroporation of the cells can be accomplished. Successful electroporation of 20 million human dendritic cells with mRNA is demonstrated. The performance of the chip is similar to that of the traditional electroporation cuvette, but without an upper limit on the number of cells to be electroporated. The device is constructed with two female Luer parts and can easily be integrated with other microfluidic components. Furthermore it is fabricated from injection molded polymer parts and commercially available stainless steel mesh, making it suitable for inexpensive mass production.

  2. Bridging the scales: Direct SEM imaging of micrometer vibrations for the analysis of stick-slip behavior at microscale

    NASA Astrophysics Data System (ADS)

    Schröter, M.-A.; Weimann, C.; Sturm, H.; Holschneider, M.

    2012-04-01

    Since earthquakes are regarded as a result of stick-slip motions between plate boundaries with instantaneous release of stored elastic energy, the similarity to friction plays an important role in the understanding of this large scale phenomenon. Recent works study by means of Atomic Force Microscopy (AFM) the frictional ageing at nanoscale due to the formation of interfacial bonds and compare it to the evolution effect of static friction at macroscale due to the increase of contacting asperities of rocks. Thus, AFM experiments can be used for a better understanding of the multiscale nature of geophysical phenomena. To this aim, the AFM tip in contact with a surface is used as the basic unit of elementary frictional processes and large scale phenomena, such as friction on macroscopic scale, are addressed in terms of the cooperative action of multiple single events and their long range correlations. Additionally, analysis of vibrations before, during and after a stick-slip process can help to understand basic mechanisms of geological faults. The cantilever spring gives the possibility to store elastic energy and to exploit natural resonances (modes) and non-linear properties (harmonics, bifurcation, etc.) for the performance of experiments. For this reason we propose in this work a new analysis technique that allows the direct observation of vibrational and frictional dynamics at the nanoscale. A cantilever is placed in the chamber of a Scanning Electron Microscope (SEM) and the vibrational dynamics are analyzed with the help of the synchronous dynamic response of the electron detector signal using lock-in techniques. The oscillation itself is excited by a piezo crystal at the base of the cantilever in several different resonance modes. Images of the superimposed AC-modulation such as amplitude/phase shift and real/imaginary part moduli can be obtained at any position of the vibrating cantilever. Thanks to the precise local definition of the electron beam and to the

  3. Optical contact micrometer

    DOEpatents

    Jacobson, Steven D.

    2014-08-19

    Certain examples provide optical contact micrometers and methods of use. An example optical contact micrometer includes a pair of opposable lenses to receive an object and immobilize the object in a position. The example optical contact micrometer includes a pair of opposable mirrors positioned with respect to the pair of lenses to facilitate viewing of the object through the lenses. The example optical contact micrometer includes a microscope to facilitate viewing of the object through the lenses via the mirrors; and an interferometer to obtain one or more measurements of the object.

  4. Non-local thermodynamic equilibrium limb radiance from O3 and CO2 in the 9-11 micrometer spectral region

    NASA Technical Reports Server (NTRS)

    Edwards, David P.; Lopez-Puertas, Manuel; Mlynczak, Martin G.

    1994-01-01

    Satellite remote sensing of mesospheric and thermospheric O3 abundance in the terrestrial atmosphere often uses 9-11 micrometer thermal emission. In this paper, we apply a line-by-line non-local thermodynamic equilibrium (non-LTE) radiance model to this spectral region and investigate the conditions of LTE breakdown and the effect that this has on the limb radiance measured by an i.r. sounder. Monochromatic and band-integrated radiance calculations have been performed for limb view tangent heights between 55 and 105 km under daytime and nighttime conditions. Non-LTE emission from both O3 and CO2 are shown to be important with the divergence of radiance from LTE values and the diurnal variation being band dependent. We have shown that the contribution of the CO2 bands to the Limb Infrared Monitor of the Stratosphere O3 channel is significant for daytime conditions at tangent heights above about 60 km. A study has been made to choose O3 sounding channel spectral passbands for the High Resolution Dynamics Limb Sounder. High resolution calculations are required to determine those spectral intervals that will filter radiance from selected bands and characterize their non-LTE behavior. This will allow for improved O3 retrievals above 70 km and non-LTE studies.

  5. Traveling digital counters for micrometers

    NASA Technical Reports Server (NTRS)

    Haley, C. T.; Moore, J. M.

    1973-01-01

    Five digit micrometer readings are made directly and quickly with no loss of precision. It is virtually impossible for micrometer to be misread. Digitized micrometer can also be used for reptitive measurements.

  6. Micrometer-scale electrical breakdown in high-density fluids with large density fluctuations: Numerical model and experimental assessment.

    PubMed

    Muneoka, Hitoshi; Urabe, Keiichiro; Stauss, Sven; Terashima, Kazuo

    2015-04-01

    Experimentally observed electrical breakdown voltages (U(B)) in high-pressure gases and supercritical fluids deviate from classical theories for low-pressure gas discharges, and the underlying breakdown mechanisms for the high-density fluids making the U(B) differ from those in the classical discharges are not yet well understood. In this study, we developed an electrical breakdown model for the high-density fluids taking into account the effects of density fluctuations and ion-enhanced field emission (IEFE). The model is based on the concept that a critical anomaly of the U(B) (local minimum near the critical point) is caused by long mean free electron path leading to a large first Townsend coefficient in locally low-density spatial domains generated by the density fluctuations. Also, a modified Paschen's curve considering the effect of the IEFE on the second Townsend coefficient was used to reproduce the U(B) curve in the high-density fluids. Calculations based on the novel model showed good agreements with the experimentally measured U(B) even near the critical point and it also suggested that the critical anomaly of the U(B) depends on the gap distance. These results indicate that both the density fluctuations and the IEFE have to be considered to comprehend the plasmas in high-density and density-fluctuating fluids.

  7. Micrometer Instruments, Aviation Quality Control 1: 9225.02.

    ERIC Educational Resources Information Center

    Dade County Public Schools, Miami, FL.

    Second in a series of five, the course consists of the history and principles of the micrometer. The student must have mastered the skills offered in Introduction to Measurement and the Use of Scaled Instruments--9225.01. Techniques in reading and using the micrometer, checking, adjusting, and calibrating the micrometer are topics covered.…

  8. Microstructural investigation of Sr-modified Al-15 wt%Si alloys in the range from micrometer to atomic scale.

    PubMed

    Timpel, M; Wanderka, N; Vinod Kumar, G S; Banhart, J

    2011-05-01

    Strontium-modified Al-15 wt%Si casting alloys were investigated after 5 and 60 min of melt holding. The eutectic microstructures were studied using complementary methods at different length scales: focused ion beam-energy selective backscattered tomography, transmission electron microscopy and 3D atom probe. Whereas the samples after 5 min of melt holding show that the structure of eutectic Si changes into a fine fibrous morphology, the increase of prolonged melt holding (60 min) leads to the loss of Sr within the alloy with an evolution of an unmodified eutectic microstructure displaying coarse interconnected Si plates. Strontium was found at the Al/Si eutectic interfaces on the side of the eutectic Al region, measured by 3D atom probe. The new results obtained using 3D atom probe shed light on the location of Sr within the Al-Si eutectic microstructure.

  9. On the Evolution From Micrometer-Scale Inhomogeneity to Global Overheated Structure During the Intense Joule Heating of a z-Pinch Rod

    DOE PAGES

    Awe, T. J.; Yu, E. P.; Yates, K. C.; ...

    2017-02-21

    Ultrafast optical microscopy of metal z-pinch rods pulsed with megaampere current is contributing new data and critical insight into what provides the fundamental seed for the magneto-Rayleigh-Taylor (MRT) instability. A two-frame near infrared/visible intensified-charge-coupled device gated imager with 2-ns temporal resolution and 3-μm spatial resolution captured emissions from the nonuniformly Joule heated surfaces of ultrasmooth aluminum (Al) rods. Nonuniform surface emissions are consistently first observed from discrete, 10-μm scale, subelectronvolt spots. Aluminum 6061 alloy, with micrometer-scale nonmetallic resistive inclusions, forms several times more spots than 99.999% pure Al 5N; 5-10 ns later, azimuthally stretched elliptical spots and distinct strata (40-100more » μm wide by 10 μm tall) are observed on Al 6061, but not on Al 5N. In such overheat strata, aligned parallel to the magnetic field, we find that they are highly effective seeds for MRT instability growth. Our data give credence to the hypothesis that early nonuniform Joule heating, such as the electrothermal instability, may provide the dominant seed for MRT.« less

  10. The automatic micrometer screw.

    PubMed

    Picker, K M

    2000-03-01

    A new analytical method - the automatic micrometer screw - has been established to measure the edge height of tablets. The equipment offers many advantages compared with other methods. The precision is slightly increased compared to the traditional micrometer screw and the measurement with a small punch and a linear voltage transducer. No longer any touch of the tablet is necessary and influences results. The method works automatically and continuously, no manual measurement of the tablets is necessary. Up to ten tablets can be analyzed at the same time because of a rotary table on which they are positioned. Thus the method is not personal intensive. By combining the results from the measurement of punch displacement which means tablet height in the die and the results of the measurement with the automatic micrometer screw which means tablet height outside the die, a convenient measurement for the decompression process is possible.

  11. Laser interferometer micrometer system

    NASA Technical Reports Server (NTRS)

    Logue, S. H.

    1969-01-01

    Laser micrometer measures dimensions of precision gyro and gas bearing parts using the principle of measuring light phase changes rather than a direct fringe count. The system uses light beams to eliminate errors due to deformations and surface irregularities, and three interferometers.

  12. Local scale effects of disease on biodiversity.

    PubMed

    Smith, Katherine F; Behrens, Michael D; Sax, Dov F

    2009-06-01

    To date, ecologists and conservation biologists have focused much of their attention on the population and ecosystem effects of disease at regional scales and the role that diseases play in global species extinction. Far less research has been dedicated to identifying the effects that diseases can have on local scale species assemblages. We examined the role of infectious disease in structuring local biodiversity. Our intention was to illustrate how variable outcomes can occur by focusing on three case studies: the influence of chestnut blight on forest communities dominated by chestnut trees, the influence of red-spot disease on urchin barrens and kelp forests, and the influence of sylvatic plague on grassland communities inhabited by prairie dogs. Our findings reveal that at local scales infectious disease seems to play an important, though unpredictable, role in structuring species diversity. Through our case studies, we have shown that diseases can cause drastic population declines or local extirpations in keystone species, ecosystem engineers, and otherwise abundant species. These changes in local diversity may be very important, particularly when considered alongside potentially corresponding changes in community structure and function, and we believe that future efforts to understand the importance of disease to species diversity should have an increased focus on these local scales.

  13. Automatic readout micrometer

    DOEpatents

    Lauritzen, Ted

    1982-01-01

    A measuring system is disclosed for surveying and very accurately positioning objects with respect to a reference line. A principal use of this surveying system is for accurately aligning the electromagnets which direct a particle beam emitted from a particle accelerator. Prior art surveying systems require highly skilled surveyors. Prior art systems include, for example, optical surveying systems which are susceptible to operator reading errors, and celestial navigation-type surveying systems, with their inherent complexities. The present invention provides an automatic readout micrometer which can very accurately measure distances. The invention has a simplicity of operation which practically eliminates the possibilities of operator optical reading error, owning to the elimination of traditional optical alignments for making measurements. The invention has an extendable arm which carries a laser surveying target. The extendable arm can be continuously positioned over its entire length of travel by either a coarse or fine adjustment without having the fine adjustment outrun the coarse adjustment until a reference laser beam is centered on the target as indicated by a digital readout. The length of the micrometer can then be accurately and automatically read by a computer and compared with a standardized set of alignment measurements. Due to its construction, the micrometer eliminates any errors due to temperature changes when the system is operated within a standard operating temperature range.

  14. Automatic readout micrometer

    DOEpatents

    Lauritzen, T.

    A measuring system is described for surveying and very accurately positioning objects with respect to a reference line. A principle use of this surveying system is for accurately aligning the electromagnets which direct a particle beam emitted from a particle accelerator. Prior art surveying systems require highly skilled surveyors. Prior art systems include, for example, optical surveying systems which are susceptible to operator reading errors, and celestial navigation-type surveying systems, with their inherent complexities. The present invention provides an automatic readout micrometer which can very accurately measure distances. The invention has a simplicity of operation which practically eliminates the possibilities of operator optical reading error, owning to the elimination of traditional optical alignments for making measurements. The invention has an extendable arm which carries a laser surveying target. The extendable arm can be continuously positioned over its entire length of travel by either a coarse of fine adjustment without having the fine adjustment outrun the coarse adjustment until a reference laser beam is centered on the target as indicated by a digital readout. The length of the micrometer can then be accurately and automatically read by a computer and compared with a standardized set of alignment measurements. Due to its construction, the micrometer eliminates any errors due to temperature changes when the system is operated within a standard operating temperature range.

  15. Optimal geographic scales for local spatial statistics.

    PubMed

    Rogerson, Peter A

    2011-04-01

    Local spatial statistics are used to test for spatial association in some variable of interest, and to test for clustering around predefined locations. Such statistics require that a neighbourhood be defined around the location of interest. This is done by specifying weights for surrounding regions, and this is tantamount to specification of the scale at which the local dependence or clustering is tested. In practice, weights are usually assigned exogenously, with little thought given to their definition. Most common is the definition of binary adjacency - weights are set equal to one if the region is adjacent to the focal region and to zero otherwise. But this implies a spatial scale that may or may not be the best one to evaluate the variable under study - the actual scale of dependence or clustering is one that is smaller or larger. An alternative strategy is to try different sets of weights corresponding to different spatial scales. The purpose of this article is to provide statistical tests that allow for examination of several local statistics across multiple spatial scales, and yet avoid the need for simulation. Application of these tests leads to a choice of spatial scale through the weights, as well as an assessment of statistical significance. The approach is illustrated using data on leukemia from central New York State.

  16. Linking Local Scale Ecosystem Science to Regional Scale Management

    NASA Astrophysics Data System (ADS)

    Shope, C. L.; Tenhunen, J.; Peiffer, S.

    2012-04-01

    Ecosystem management with respect to sufficient water yield, a quality water supply, habitat and biodiversity conservation, and climate change effects requires substantial observational data at a range of scales. Complex interactions of local physical processes oftentimes vary over space and time, particularly in locations with extreme meteorological conditions. Modifications to local conditions (ie: agricultural land use changes, nutrient additions, landscape management, water usage) can further affect regional ecosystem services. The international, inter-disciplinary TERRECO research group is intensively investigating a variety of local processes, parameters, and conditions to link complex physical, economic, and social interactions at the regional scale. Field-based meteorology, hydrology, soil physics, plant production, solute and sediment transport, economic, and social behavior data were measured in a South Korean catchment. The data are used to parameterize suite of models describing local to landscape level water, sediment, nutrient, and monetary relationships. We focus on using the agricultural and hydrological SWAT model to synthesize the experimental field data and local-scale models throughout the catchment. The approach of our study was to describe local scientific processes, link potential interrelationships between different processes, and predict environmentally efficient management efforts. The Haean catchment case study shows how research can be structured to provide cross-disciplinary scientific linkages describing complex ecosystems and landscapes that can be used for regional management evaluations and predictions.

  17. Locality and Scaling of Quenched Overlap Fermions

    SciTech Connect

    Terrence Draper; Nilmani Mathur; Jianbo Zhang; Andrei Alexandru; Ying Chen; Shao-Jing Dong; Ivan Horvath; Frank Lee; Sonali Tamhankar

    2005-07-01

    The overlap fermion offers the tremendous advantage of exact chiral symmetry on the lattice, but is numerically intensive. This can be made affordable while still providing large lattice volumes, by using coarse lattice spacing, given that good scaling and localization properties are established. Here, using overlap fermions on quenched Iwasaki gauge configurations, we demonstrate directly that the overlap Dirac operator's range is comfortably small in lattice units for each of the lattice spacings 0.20 fm, 0.17 fm, and 0.13 fm (and scales to zero in physical units in the continuum limit). In particular, our direct results contradict recent speculation that an inverse lattice spacing of 1 GeV is too low to have satisfactory localization. Furthermore, hadronic masses (available on the two coarser lattices) scale very well.

  18. From dynamical scaling to local scale-invariance: a tutorial

    NASA Astrophysics Data System (ADS)

    Henkel, Malte

    2017-03-01

    Dynamical scaling arises naturally in various many-body systems far from equilibrium. After a short historical overview, the elements of possible extensions of dynamical scaling to a local scale-invariance will be introduced. Schrödinger-invariance, the most simple example of local scale-invariance, will be introduced as a dynamical symmetry in the Edwards-Wilkinson universality class of interface growth. The Lie algebra construction, its representations and the Bargman superselection rules will be combined with non-equilibrium Janssen-de Dominicis field-theory to produce explicit predictions for responses and correlators, which can be compared to the results of explicit model studies. At the next level, the study of non-stationary states requires to go over, from Schrödinger-invariance, to ageing-invariance. The ageing algebra admits new representations, which acts as dynamical symmetries on more general equations, and imply that each non-equilibrium scaling operator is characterised by two distinct, independent scaling dimensions. Tests of ageing-invariance are described, in the Glauber-Ising and spherical models of a phase-ordering ferromagnet and the Arcetri model of interface growth.

  19. Local magnitude scale for earthquakes in Turkey

    NASA Astrophysics Data System (ADS)

    Kılıç, T.; Ottemöller, L.; Havskov, J.; Yanık, K.; Kılıçarslan, Ö.; Alver, F.; Özyazıcıoğlu, M.

    2017-01-01

    Based on the earthquake event data accumulated by the Turkish National Seismic Network between 2007 and 2013, the local magnitude (Richter, Ml) scale is calibrated for Turkey and the close neighborhood. A total of 137 earthquakes (Mw > 3.5) are used for the Ml inversion for the whole country. Three Ml scales, whole country, East, and West Turkey, are developed, and the scales also include the station correction terms. Since the scales for the two parts of the country are very similar, it is concluded that a single Ml scale is suitable for the whole country. Available data indicate the new scale to suffer from saturation beyond magnitude 6.5. For this data set, the horizontal amplitudes are on average larger than vertical amplitudes by a factor of 1.8. The recommendation made is to measure Ml amplitudes on the vertical channels and then add the logarithm scale factor to have a measure of maximum amplitude on the horizontal. The new Ml is compared to Mw from EMSC, and there is almost a 1:1 relationship, indicating that the new scale gives reliable magnitudes for Turkey.

  20. Natural speciation of Mn, Ni, and Zn at the micrometer scale in a clayey paddy soil using X-ray fluorescence, absorption, and diffraction

    NASA Astrophysics Data System (ADS)

    Manceau, Alain; Tommaseo, Caterina; Rihs, Sophie; Geoffroy, Nicolas; Chateigner, Daniel; Schlegel, Michel; Tisserand, Delphine; Marcus, Matthew A.; Tamura, Nobumichi; Chen, Zueng-Sang

    2005-08-01

    The natural speciation of Mn (0.19 g/kg), Ni (46 mg/kg), and Zn (42 mg/kg) in the argillic horizon (120 cm depth, pH = 5.6) of an Ultisol from a paddy soil in northern Taiwan was investigated by advanced X-ray synchrotron techniques. Microchemical associations were imaged by synchrotron-based X-ray microfluorescence, host minerals were identified by standard and micrometer-resolved X-ray diffraction, and the local coordination environment of Mn, Ni, and Zn was probed using extended X-ray absorption fine structure (EXAFS) spectroscopy on a powdered sample and a soil thin section, and polarized EXAFS spectroscopy on a highly textured self-supporting clay film from the <2 μm fraction of the soil. Manganese was concentrated in Fe-Mn soft mottles (44.4 g/kg) as turbostratic hexagonal birnessite and lithiophorite having Mn 3+/Mn 4+ atomic ratios of ˜20% and 50%, respectively. Quantitative analysis of high-order scattering paths of the EXAFS spectrum for natural and synthetic (AlLi)(Mn0.684+Mn0.323+)O( lithiophorite revealed that Mn 3+ and Mn 4+ are ordered in the [ layer. A structural model is proposed, in which Mn 4+ and Mn 3+ are ordered similarly to Al and Li in the [ layer, with Mn 3+ cations being surrounded by six Mn 4+, and Mn 4+ cations by three Mn 3+ and three Mn 4+. Similar cation ordering in the manganese and aluminum layers likely provides a more homogeneous local balance of the excess and deficit of charges in each layer and increases the stability of lithiophorite. Ni ( r = 0.70 Å) substitutes for Mn (r(Mn 4+) = 0.54 Å, r(Mn 3+) = 0.65 Å) in the manganese layer in the natural lithiophorite. In contrast, Zn ( r = 0.74 Å) fills vacant sites in the gibbsitic layer of natural lithiophorite, in a similar manner as lithium ( r = 0.74 Å) in synthetic lithiophorite. The partitioning of Ni and Zn between the two layers is a result of the general preference of Ni, whose size is intermediate between those of Mn 3+ and Li +, for slightly smaller sites. In

  1. Natural speciation of Mn, Ni and Zn at a micrometer scale in aclayey paddy soil using X-ray fluorescence, absorption anddiffraction

    SciTech Connect

    Manceau, Alain; Tommaseo, Caterina; Rihs, Sophie; Geoffroy,Nicolas; Chateigner, Daniel; Schlegel, Michel; Tisserand, Delphine; Marcus, Matthew A.; Tamura, Nobumichi; Chen, Zueng-Sang

    2005-08-29

    The natural speciation of Mn (0.19 g/kg), Ni (46 mg/kg), and Zn (42 mg/kg) in the argillic horizon (120 cm depth, pH = 5.6) of an Ultisol from a paddy soil in northern Taiwan was investigated by advanced X-ray synchrotron techniques. Microchemical associations were imaged by synchrotron-based X-ray microfluorescence, host minerals were identified by standard and micrometer-resolved X-ray diffraction, and the local coordination environment of Mn, Ni, and Zn was probed using extended X-ray absorption fine structure (EXAFS) spectroscopy on a powdered sample and a soil thin section, and polarized EXAFS spectroscopy on a highly textured self-supporting clay film from the <2 mu m fraction of the soil. Manganese was concentrated in Fe-Mn soft mottles (44.4 g/kg) as turbostratic hexagonal birnessite and lithiophorite having Mn3+/Mn4+atomic ratios of {approx} 20 percent and 50 percent, respectively. Quantitative analysis of high-order scattering paths of the EXAFS spectrum for natural and synthetic (Al0.67Li0.32)(Mn0.684+Mn0.323+)O2(OH)2 lithiophorite revealed that Mn3+ and Mn4+ are ordered in the[(Mn0.684+Mn0.323+)O2]0.32- layer. A structural model is proposed, in which Mn4+ and Mn3+ are ordered similarly to Al and Li in the [(Al0.673+Li0.32+)(OH)2]0.32- layer, with Mn3+ cations being surrounded by six Mn4+, and Mn4+ cations by three Mn3+ and three Mn4+. Similar cation ordering in the manganese and aluminum layers likely provides a more homogeneous local balance of the excess and deficit of charges in each layer and increases the stability of lithiophorite. Ni (r = 0.70Angstrom) substitutes for Mn(r(Mn4+) = 0.54 Angstrom, r(Mn3+) = 0.65Angstrom) in the manganese layer in the natural lithiophorite. In contrast, Zn(r = 0.74 Angstrom) fills vacant sites in the gibbsitic layer of natural lithiophorite, in a similar manner as lithium (r = 0.74) Angstrom in synthetic lithiophorite. The partitioning of Ni and Zn between the two layers is a result of the general preference of Ni

  2. Zinc mobility and speciation in soil covered by contaminated dredged sediment using micrometer-scale and bulk-averaging X-ray fluorescence, absorption and diffraction techniques

    NASA Astrophysics Data System (ADS)

    Isaure, Marie-Pierre; Manceau, Alain; Geoffroy, Nicolas; Laboudigue, Agnès; Tamura, Nobumichi; Marcus, Matthew A.

    2005-03-01

    The mobility and solid-state speciation of zinc in a pseudogley soil (pH = 8.2-8.3) before and after contamination by land-disposition of a dredged sediment ([Zn] = 6600 mg kg -1) affected by smelter operations were studied in a 50 m 2 pilot-scale test site and the laboratory using state-of-the-art synchrotron-based techniques. Sediment disposition on land caused the migration of micrometer-sized, smelter-related, sphalerite (ZnS) and franklinite (ZnFe 2O 4) grains and dissolved Zn from the sediment downwards to a soil depth of 20 cm over a period of 18 months. Gravitational movement of fine-grained metal contaminants probably occurred continuously, while peaks of Zn leaching were observed in the summer when the oxidative dissolution of ZnS was favored by non-flooding conditions. The Zn concentration in the <50 μm soil fraction increased from ˜61 ppm to ˜94 ppm in the first 12 months at 0-10 cm depth, and to ˜269 ppm in the first 15 months following the sediment deposition. Higher Zn concentrations and enrichments were observed in the fine (<2 μm) and very fine (<0.2 μm) fractions after 15 months (480 mg kg -1 and 1000 mg kg -1, respectively), compared to 200 mg kg -1 in the <2 μm fraction of the initial soil. In total, 1.2% of the Zn initially present in the sediment was released to the environment after 15 months, representing an integrated quantity of ˜4 kg Zn over an area of 50 m 2. Microfocused X-ray fluorescence (XRF), diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) spectroscopy techniques were used to image chemical associations of Zn with Fe and Mn, and to identify mineral and Zn species in selected points-of-interest in the uncontaminated and contaminated soil. Bulk average powder EXAFS spectroscopy was used to quantify the proportion of each Zn species in the soil. In the uncontaminated soil, Zn is largely speciated as Zn-containing phyllosilicate, and to a minor extent as zincochromite (ZnCr 2O 4), IVZn-sorbed turbostratic

  3. Micrometer for Measuring Trepanned Grooves

    NASA Technical Reports Server (NTRS)

    Bird, S. K.

    1983-01-01

    Special micrometer measures diameter of circular groove on face of large part, while part is mounted in lathe chuck. Tool has curved frame so it can reach around obstruction on centerline of part. At one end of frame is blade/ micrometer spindle for reaching into groove to be measured; this type of spindle does not rotate when micrometer thimble is turned in taking measurement. Other end of frame has sliding foot with blade.

  4. Scaling analysis of Anderson localizing optical fibers

    NASA Astrophysics Data System (ADS)

    Abaie, Behnam; Mafi, Arash

    2017-02-01

    Anderson localizing optical fibers (ALOF) enable a novel optical waveguiding mechanism; if a narrow beam is scanned across the input facet of the disordered fiber, the output beam follows the transverse position of the incoming wave. Strong transverse disorder induces several localized modes uniformly spread across the transverse structure of the fiber. Each localized mode acts like a transmission channel which carries a narrow input beam along the fiber without transverse expansion. Here, we investigate scaling of transverse size of the localized modes of ALOF with respect to transverse dimensions of the fiber. Probability density function (PDF) of the mode-area is applied and it is shown that PDF converges to a terminal shape at transverse dimensions considerably smaller than the previous experimental implementations. Our analysis turns the formidable numerical task of ALOF simulations into a much simpler problem, because the convergence of mode-area PDF to a terminal shape indicates that a much smaller disordered fiber, compared to previous numerical and experimental implementations, provides all the statistical information required for the precise analysis of the fiber.

  5. Local-scale dynamics and local drivers of bushmeat trade.

    PubMed

    Nyaki, Angela; Gray, Steven A; Lepczyk, Christopher A; Skibins, Jeffrey C; Rentsch, Dennis

    2014-10-01

    Bushmeat management policies are often developed outside the communities in which they are to be implemented. These policies are also routinely designed to be applied uniformly across communities with little regard for variation in social or ecological conditions. We used fuzzy-logic cognitive mapping, a form of participatory modeling, to compare the assumptions driving externally generated bushmeat management policies with perceptions of bushmeat trade dynamics collected from local community members who admitted to being recently engaged in bushmeat trading (e.g., hunters, sellers, consumers). Data were collected during 9 workshops in 4 Tanzanian villages bordering Serengeti National Park. Specifically, we evaluated 9 community-generated models for the presence of the central factors that comprise and drive the bushmeat trade and whether or not models included the same core concepts, relationships, and logical chains of reasoning on which bushmeat conservation policies are commonly based. Across local communities, there was agreement about the most central factors important to understanding the bushmeat trade (e.g., animal recruitment, low income, and scarcity of food crops). These matched policy assumptions. However, the factors perceived to drive social-ecological bushmeat trade dynamics were more diverse and varied considerably across communities (e.g., presence or absence of collaborative law enforcement, increasing human population, market demand, cultural preference). Sensitive conservation issues, such as the bushmeat trade, that require cooperation between communities and outside conservation organizations can benefit from participatory modeling approaches that make local-scale dynamics and conservation policy assumptions explicit. Further, communities' and conservation organizations' perceptions need to be aligned. This can improve success by allowing context appropriate policies to be developed, monitored, and appropriately adapted as new evidence is

  6. Local gravity and large-scale structure

    NASA Technical Reports Server (NTRS)

    Juszkiewicz, Roman; Vittorio, Nicola; Wyse, Rosemary F. G.

    1990-01-01

    The magnitude and direction of the observed dipole anisotropy of the galaxy distribution can in principle constrain the amount of large-scale power present in the spectrum of primordial density fluctuations. This paper confronts the data, provided by a recent redshift survey of galaxies detected by the IRAS satellite, with the predictions of two cosmological models with very different levels of large-scale power: the biased Cold Dark Matter dominated model (CDM) and a baryon-dominated model (BDM) with isocurvature initial conditions. Model predictions are investigated for the Local Group peculiar velocity, v(R), induced by mass inhomogeneities distributed out to a given radius, R, for R less than about 10,000 km/s. Several convergence measures for v(R) are developed, which can become powerful cosmological tests when deep enough samples become available. For the present data sets, the CDM and BDM predictions are indistinguishable at the 2 sigma level and both are consistent with observations. A promising discriminant between cosmological models is the misalignment angle between v(R) and the apex of the dipole anisotropy of the microwave background.

  7. Local gravity and large-scale structure

    NASA Technical Reports Server (NTRS)

    Juszkiewicz, Roman; Vittorio, Nicola; Wyse, Rosemary F. G.

    1990-01-01

    The magnitude and direction of the observed dipole anisotropy of the galaxy distribution can in principle constrain the amount of large-scale power present in the spectrum of primordial density fluctuations. This paper confronts the data, provided by a recent redshift survey of galaxies detected by the IRAS satellite, with the predictions of two cosmological models with very different levels of large-scale power: the biased Cold Dark Matter dominated model (CDM) and a baryon-dominated model (BDM) with isocurvature initial conditions. Model predictions are investigated for the Local Group peculiar velocity, v(R), induced by mass inhomogeneities distributed out to a given radius, R, for R less than about 10,000 km/s. Several convergence measures for v(R) are developed, which can become powerful cosmological tests when deep enough samples become available. For the present data sets, the CDM and BDM predictions are indistinguishable at the 2 sigma level and both are consistent with observations. A promising discriminant between cosmological models is the misalignment angle between v(R) and the apex of the dipole anisotropy of the microwave background.

  8. Rules-based correction strategies setup on sub-micrometer line and space patterns for 200mm wafer scale SmartNIL process within an integration process flow

    NASA Astrophysics Data System (ADS)

    Teyssedre, H.; Landis, S.; Brianceau, P.; Mayr, M.; Thanner, C.; Laure, M.; Zorbach, W.; Eibelhuber, M.; Pain, L.; Chouiki, M.; Wimplinger, M.

    2017-03-01

    In this paper the rules-based correction strategies for the nanoimprint lithography (NIL) technology are addressed using complete Scanning Electron Microscopy (SEM) characterizations. Performed onto 200 mm wafers imprinted with the HERCULES NIL equipment platform, Critical Dimension (CD) uniformity analyses are used to measure the evolution of lines and spaces features dimensions from the master to 50 consecutive imprints. The work brings focus on sub micrometer resolution features with duty cycles from 3 to 7. The silicon masters were manufactured with 193 optical lithography and dry etching and were fully characterized prior to the imprint process. Repeatability tests were performed over 50 wafers for two different processes to collect statistical and comparative data. The data revealed that the CD evolutions can be modelled by quadratic functions with respect to the number of imprints and feature dimension (CD and pitch) on the master. These models are used to establish the rules-based corrections for lines arrays in the scope of nanoimprint master manufacturing, and it opens the discussion on the process monitoring through metrology for the nanoimprint soft stamp technologies.

  9. The 10 micrometer transmitter

    NASA Technical Reports Server (NTRS)

    1976-01-01

    The design, fabrication tests, and engineering model components of a 10.6 mum wideband transceiver system are reported. The effort emphasized the transmitter subsystem, including the development of the laser, the modulator driver, and included productization of both the transmitter and local oscillator lasers. The transmitter subsystem is functionally compatible with the receiver engineering model terminal, and has undergone high data rate communication system testing against that terminal.

  10. Micrometer-scale U-Pb age domains in eucrite zircons, impact re-setting, and the thermal history of the HED parent body

    NASA Astrophysics Data System (ADS)

    Hopkins, M. D.; Mojzsis, S. J.; Bottke, W. F.; Abramov, O.

    2015-01-01

    Meteoritic zircons are rare, but some are documented to occur in asteroidal meteorites, including those of the howardite-eucrite-diogenite (HED) achondrite clan (Rubin, A. [1997]. Meteorit. Planet. Sci. 32, 231-247). The HEDs are widely considered to originate from the Asteroid 4 Vesta. Vesta and the other large main belt asteroids record an early bombardment history. To explore this record, we describe sub-micrometer distributions of trace elements (U, Th) and 235,238U-207,206Pb ages from four zircons (>7-40 μm ∅) separated from bulk samples of the brecciated eucrite Millbillillie. Ultra-high resolution (∼100 nm) ion microprobe depth profiles reveal different zircon age domains correlative to mineral chemistry and to possible impact scenarios. Our new U-Pb zircon geochronology shows that Vesta's crust solidified within a few million years of Solar System formation (4561 ± 13 Ma), in good agreement with previous work (e.g. Carlson, R.W., Lugmair, G.W. [2000]. Timescales of planetesimal formation and differentiation based on extinct and extant radioisotopes. In: Canup, R., Righter, K. (Eds.), Origin of the Earth and Moon. University of Arizona Press, Tucson, pp. 25-44). Younger zircon age domains (ca. 4530 Ma) also record crustal processes, but these are interpreted to be exogenous because they are well after the effective extinction of 26Al (t1/2 = 0.72 Myr). An origin via impact-resetting was evaluated with a suite of analytical impact models. Output shows that if a single impactor was responsible for the ca. 4530 Ma zircon ages, it had to have been ⩾10 km in diameter and at high enough velocity (>5 km s-1) to account for the thermal field required to re-set U-Pb ages. Such an impact would have penetrated at least 10 km into Vesta's crust. Later events at ca. 4200 Ma are documented in HED apatite 235,238U-207,206Pb ages (Zhou, Q. et al. [2011]. Early basaltic volcanism and Late Heavy Bombardment on Vesta: U-Pb ages of small zircons and phosphates in

  11. Micrometer-scale U–Pb age domains in eucrite zircons, impact re-setting, and the thermal history of the HED parent body

    USGS Publications Warehouse

    Hopkins, M.D.; Mojzsis, S.J.; Bottke, W.F.; Abramov, Oleg

    2015-01-01

    Meteoritic zircons are rare, but some are documented to occur in asteroidal meteorites, including those of the howardite–eucrite–diogenite (HED) achondrite clan (Rubin, A. [1997]. Meteorit. Planet. Sci. 32, 231–247). The HEDs are widely considered to originate from the Asteroid 4 Vesta. Vesta and the other large main belt asteroids record an early bombardment history. To explore this record, we describe sub-micrometer distributions of trace elements (U, Th) and 235,238U–207,206Pb ages from four zircons (>7–40 μm ∅) separated from bulk samples of the brecciated eucrite Millbillillie. Ultra-high resolution (∼100 nm) ion microprobe depth profiles reveal different zircon age domains correlative to mineral chemistry and to possible impact scenarios. Our new U–Pb zircon geochronology shows that Vesta’s crust solidified within a few million years of Solar System formation (4561 ± 13 Ma), in good agreement with previous work (e.g. Carlson, R.W., Lugmair, G.W. [2000]. Timescales of planetesimal formation and differentiation based on extinct and extant radioisotopes. In: Canup, R., Righter, K. (Eds.), Origin of the Earth and Moon. University of Arizona Press, Tucson, pp. 25–44). Younger zircon age domains (ca. 4530 Ma) also record crustal processes, but these are interpreted to be exogenous because they are well after the effective extinction of 26Al (t1/2 = 0.72 Myr). An origin via impact-resetting was evaluated with a suite of analytical impact models. Output shows that if a single impactor was responsible for the ca. 4530 Ma zircon ages, it had to have been ⩾10 km in diameter and at high enough velocity (>5 km s−1) to account for the thermal field required to re-set U–Pb ages. Such an impact would have penetrated at least 10 km into Vesta’s crust. Later events at ca. 4200 Ma are documented in HED apatite 235,238U–207,206Pb ages (Zhou, Q. et al. [2011]. Early basaltic volcanism and Late Heavy Bombardment on Vesta: U–Pb ages of small

  12. Confocal micrometer-scale X-ray fluorescence and X-ray absorption fine structure studies of uranium speciation in a tertiary sediment from a waste disposal natural analogue site.

    PubMed

    Denecke, Melissa A; Janssens, Koen; Proost, Kristof; Rothe, Jörg; Noseck, Ulrich

    2005-04-01

    Investigations by micrometer-scale X-ray fluorescence and X-ray absorption fine structure (micro-XRF and micro-XAFS) recorded in a confocal geometry on a bore core section of a uranium-rich tertiary sediment are performed in order to assess mechanisms leading to immobilization of the uranium during diagenesis. Results show uranium to be present as a tetravalent phosphate and that U(IV) is associated with As(V). Arsenic present is either As(V) or As(O); we found no evidence for As(III). The As(O) is observed to be intimately associated with the surface of Fe(II) nodules and likely arsenopyrite. A hypothesis for the mechanism of uranium immobilization is proposed, where arsenopyrite acted as reductant of groundwater-dissolved U(VI), leading to precipitation of less soluble U(IV) and thereby forming As(V).

  13. Scaling down: local radio in India.

    PubMed

    Anjaneyulu, K

    1989-01-01

    All India Radio (AIR) is one of the world's largest national radio networks. In the past 5 years, AIR has been experimenting with the idea of local radio stations. The governmental view of local radio is one that supports the idea of a close association with the hub of the community. It also believes that the radio station should act as a "mouthpiece" of the community. A large number of local programs are field-based. Access programs, service programs, and specific programs concerning family welfare, national integration, communal harmony and others relevant to the local broadcast area are produced. Community service broadcasts, the role of a local station as a mediator between local factions and access programs are further discussed. The experiences and development of the 1st local station at Nagercoil in the southern Indian state of Tamilnadu is discussed in detail. The greatest attribute of local radio is that it works directly with and is often directly controlled by the people it is designed to serve.

  14. Validating Large Scale Networks Using Temporary Local Scale Networks

    USDA-ARS?s Scientific Manuscript database

    The USDA NRCS Soil Climate Analysis Network and NOAA Climate Reference Networks are nationwide meteorological and land surface data networks with soil moisture measurements in the top layers of soil. There is considerable interest in scaling these point measurements to larger scales for validating ...

  15. A survey of fractured SrTiO{sub 3} surfaces : from the micro-meter to nano-meter scale.

    SciTech Connect

    Chien, T. Y.; Guisinger, N. P.; Freeland, J. W.

    2010-01-01

    Cross-sectional scanning tunneling microscopy was utilized to study fractured perovskite oxide surfaces. It was found that for the non-cleavable perovskite oxide, SrTiO{sub 3}, atomically flat terraces could be routinely created with a controlled fracturing procedure. Optical, scanning electron and scanning tunneling microscopies, and a profilometer were used to obtain information from submillimeter to submicrometer scales of the fractured surface topography.

  16. Direct mapping of local director field of nematic liquid crystals at the nano-scale

    NASA Astrophysics Data System (ADS)

    Xia, Yu; Serra, Francesca; Yang, Shu; Kamien, Randall

    2015-03-01

    The director field in liquid crystals (LCs) has been characterized mainly via polarized optical microscopy, fluorescence confocal microscopy, and Raman spectroscopy, all of which are limited by optical wavelengths - from hundreds of nanometers to several micrometers. Since LC orientation cannot be resolved directly by these methods, theory is needed to interpret the local director field of LC alignment. In this work, we introduce a new approach to directly visualize the local director field of a nematic LC (NLC) at the nano-scale using scanning electron microscopy (SEM). A new type of NLC monomer bearing crosslinkable groups was designed and synthesized. It can be well-oriented at particle surfaces and patterned polymer substrates, including micron-sized silica colloids, porous membranes, micropillar arrays, and 1D channels. After carefully crosslinking, the molecular orientation of NLCs around the particles or within the patterns could be directly visualized by SEM, showing oriented nanofibers representing LC director from the fractured samples. Here, we could precisely resolve not only the local director field by this approach, but the defect structures of NLCs, including hedgehogs and line defects. The direct mapping of LC directors at the nanoscale using this method will improve our understanding of NLC local director field, and thus their manipulation and applications. More importantly, a theoretical interpretation will no longer be a necessity to resolve a new material system in this field.

  17. Studying Soft-matter and Biological Systems over a Wide Length-scale from Nanometer and Micrometer Sizes at the Small-angle Neutron Diffractometer KWS-2

    PubMed Central

    Radulescu, Aurel; Szekely, Noemi Kinga; Appavou, Marie-Sousai; Pipich, Vitaliy; Kohnke, Thomas; Ossovyi, Vladimir; Staringer, Simon; Schneider, Gerald J.; Amann, Matthias; Zhang-Haagen, Bo; Brandl, Georg; Drochner, Matthias; Engels, Ralf; Hanslik, Romuald; Kemmerling, Günter

    2016-01-01

    The KWS-2 SANS diffractometer is dedicated to the investigation of soft matter and biophysical systems covering a wide length scale, from nm to µm. The instrument is optimized for the exploration of the wide momentum transfer Q range between 1x10-4 and 0.5 Å-1 by combining classical pinhole, focusing (with lenses), and time-of-flight (with chopper) methods, while simultaneously providing high-neutron intensities with an adjustable resolution. Because of its ability to adjust the intensity and the resolution within wide limits during the experiment, combined with the possibility to equip specific sample environments and ancillary devices, the KWS-2 shows a high versatility in addressing the broad range of structural and morphological studies in the field. Equilibrium structures can be studied in static measurements, while dynamic and kinetic processes can be investigated over time scales between minutes to tens of milliseconds with time-resolved approaches. Typical systems that are investigated with the KWS-2 cover the range from complex, hierarchical systems that exhibit multiple structural levels (e.g., gels, networks, or macro-aggregates) to small and poorly-scattering systems (e.g., single polymers or proteins in solution). The recent upgrade of the detection system, which enables the detection of count rates in the MHz range, opens new opportunities to study even very small biological morphologies in buffer solution with weak scattering signals close to the buffer scattering level at high Q. In this paper, we provide a protocol to investigate samples with characteristic size levels spanning a wide length scale and exhibiting ordering in the mesoscale structure using KWS-2. We present in detail how to use the multiple working modes that are offered by the instrument and the level of performance that is achieved. PMID:28060296

  18. Studying Soft-matter and Biological Systems over a Wide Length-scale from Nanometer and Micrometer Sizes at the Small-angle Neutron Diffractometer KWS-2.

    PubMed

    Radulescu, Aurel; Szekely, Noemi Kinga; Appavou, Marie-Sousai; Pipich, Vitaliy; Kohnke, Thomas; Ossovyi, Vladimir; Staringer, Simon; Schneider, Gerald J; Amann, Matthias; Zhang-Haagen, Bo; Brandl, Georg; Drochner, Matthias; Engels, Ralf; Hanslik, Romuald; Kemmerling, Günter

    2016-12-08

    The KWS-2 SANS diffractometer is dedicated to the investigation of soft matter and biophysical systems covering a wide length scale, from nm to µm. The instrument is optimized for the exploration of the wide momentum transfer Q range between 1x10(-4) and 0.5 Å(-1) by combining classical pinhole, focusing (with lenses), and time-of-flight (with chopper) methods, while simultaneously providing high-neutron intensities with an adjustable resolution. Because of its ability to adjust the intensity and the resolution within wide limits during the experiment, combined with the possibility to equip specific sample environments and ancillary devices, the KWS-2 shows a high versatility in addressing the broad range of structural and morphological studies in the field. Equilibrium structures can be studied in static measurements, while dynamic and kinetic processes can be investigated over time scales between minutes to tens of milliseconds with time-resolved approaches. Typical systems that are investigated with the KWS-2 cover the range from complex, hierarchical systems that exhibit multiple structural levels (e.g., gels, networks, or macro-aggregates) to small and poorly-scattering systems (e.g., single polymers or proteins in solution). The recent upgrade of the detection system, which enables the detection of count rates in the MHz range, opens new opportunities to study even very small biological morphologies in buffer solution with weak scattering signals close to the buffer scattering level at high Q. In this paper, we provide a protocol to investigate samples with characteristic size levels spanning a wide length scale and exhibiting ordering in the mesoscale structure using KWS-2. We present in detail how to use the multiple working modes that are offered by the instrument and the level of performance that is achieved.

  19. Airborne astronomy with a 150 micrometer - 500 micrometer heterodyne spectrometer

    NASA Technical Reports Server (NTRS)

    Betz, A. L.

    1991-01-01

    This report summarizes work done under NASA Grant NAG2-254 awarded to the University of California. The project goal was to build a far-infrared heterodyne spectrometer for NASA's Kuiper Airborne Observatory (KAO), and to use this instrument to observe atomic and molecular spectral lines from the interstellar medium. This goal was successfully achieved; the spectrometer is now in routine use aboard the KAO. Detections of particular note have been the 370 micrometers line of neutral atomic carbon, the 158 micrometers transition of ionized carbon, many of the high-J rotational lines of 12CO and 13CO between J=9-8 and J=22-21, the 119 micron ground-state rotational line of OH, and the 219 micron ground-state rotational line of H2D(+). All of these lines were observed at spectral resolutions exceeding 1 part in 10(exp 6), thereby allowing accurate line shapes and Doppler velocities to be measured.

  20. Synchrotron radiation micro-CT at the micrometer scale for the analysis of the three-dimensional morphology of microcracks in human trabecular bone.

    PubMed

    Larrue, Aymeric; Rattner, Aline; Peter, Zsolt-Andrei; Olivier, Cécile; Laroche, Norbert; Vico, Laurence; Peyrin, Françoise

    2011-01-01

    Bone quality is an important concept to explain bone fragility in addition to bone mass. Among bone quality factors, microdamage which appears in daily life is thought to have a marked impact on bone strength and plays a major role in the repair process. The starting point for all studies designed to further our understanding of how bone microdamage initiate or dissipate energy, or to investigate the impact of age, gender or disease, remains reliable observation and measurement of microdamage. In this study, 3D Synchrotron Radiation (SR) micro-CT at the micrometric scale was coupled to image analysis for the three-dimensional characterization of bone microdamage in human trabecular bone specimens taken from femoral heads. Specimens were imaged by 3D SR micro-CT with a voxel size of 1.4 µm. A new tailored 3D image analysis technique was developed to segment and quantify microcracks. Microcracks from human trabecular bone were observed in different tomographic sections as well as from 3D renderings. New 3D quantitative measurements on the microcrack density and morphology are reported on five specimens. The 3D microcrack density was found between 3.1 and 9.4/mm3 corresponding to a 2D density between 0.55 and 0.76 /mm2. The microcrack length and width measured in 3D on five selected microcrack ranged respectively from 164 µm to 209 µm and 100 µm to 120 µm. This is the first time that various microcracks in unloaded human trabecular bone--from the simplest linear crack to more complex cross-hatch cracks--have been examined and quantified by 3D imaging at this scale. The suspected complex morphology of microcracks is here considerably more evident than in the 2D observations. In conclusion, this technique opens new perspective for the 3D investigation of microcracks and the impact of age, disease or treatment.

  1. Broadband and Low-Loss Plasmonic Light Trapping in Dye-Sensitized Solar Cells Using Micrometer-Scale Rodlike and Spherical Core-Shell Plasmonic Particles.

    PubMed

    Malekshahi Byranvand, Mahdi; Nemati Kharat, Ali; Taghavinia, Nima; Dabirian, Ali

    2016-06-29

    Dielectric scattering particles have widely been used as embedded scattering elements in dye-sensitized solar cells (DSCs) to improve the optical absorption of the device. Here we systematically study rodlike and spherical core-shell silica@Ag particles as more effective alternatives to the dielectric scattering particles. The wavelength-scale silica@Ag particles with sufficiently thin Ag shell support hybrid plasmonic-photonic resonance modes that have low parasitic absorption losses and a broadband optical response. Both of these features lead to their successful deployment in light trapping in high-efficiency DSCs. Optimized rodlike silica@Ag@silica particles improve the power conversion efficiency of a DSC from 6.33 to 8.91%. The dimension, surface morphology, and concentration of these particles are optimized to achieve maximal efficiency enhancement. The rodlike silica particles are prepared in a simple one-pot synthesis process and then are coated with Ag in a liquid-phase deposition process by reducing an Ag salt. The aspect ratio of silica rods is tuned by adjusting the temperature and duration of the growth process, whereas the morphology of Ag shell is tailored by controlling the reduction rate of Ag salt, where slower reduction in a polyol process gives a smoother Ag shell. Using optical calculations, the superior performance of the plasmonic core-shell particles is related to the large number of hybrid photonic-plasmonic resonance modes that they support.

  2. Localization of energy on the molecular scale

    SciTech Connect

    Lindenberg, K.; Brown, D.W.

    1997-12-31

    We discuss the spontaneous localization of vibrational energy in translationally invariant anharmonic chains at finite temperatures. In addition to the familiar energy-driven coherent mechanisms, which are rapidly degraded by thermal fluctuations, we identify the entropy-driven phenomenon we call {open_quotes}stochastic localization{close_quotes}, within which we include a number of characteristics of soft anharmonic oscillators in thermal equilibrium. Principal among these are a tendency for soft oscillators to spend more time at higher energies than comparable harmonic oscillators, and for high-energy fluctuations in soft oscillators to persist for longer times than lower-energy fluctuations, leading to a tendency for energy fluctuations to be organized into {open_quotes}bursts{close_quotes} separated by intervals of relative quiet. We illustrate the effects of stochastic localization on a bistable impurity embedded in a chain of soft oscillators by comparing it to an impurity embedded in a harmonic chain. Effects on transition rates at a given system energy can be quite dramatic.

  3. Localization length scales of triplet excitons in singlet fission materials

    NASA Astrophysics Data System (ADS)

    Bayliss, Sam L.; Thorley, Karl J.; Anthony, John E.; Bouchiat, Hélène; Greenham, Neil C.; Chepelianskii, Alexei D.

    2015-09-01

    We measure the dielectric confinement length scales of triplet excitons in organic semiconductors by jointly measuring their microwave-domain electric and magnetic susceptibilities. We apply this technique to characterize triplet excitons in two singlet fission materials with distinct solid-state packing and correlate the extracted localization length scales with the role of the excitonic environment. By using the magnetic susceptibility simultaneously determined through our experiments, we compare the independently extracted dielectric and spin-spin localization length scales, highlighting the role of local anisotropy on the properties of excitonic triplet states.

  4. Local supersymmetry and the problem of the mass scales

    SciTech Connect

    Nilles, H.P.

    1983-02-01

    Spontaneously broken supergravity might help us to understand the puzzle of the mass scales in grand unified models. We describe the general mechanism and point out the remaining problems. Some new results on local supercolor are presented.

  5. Scale dependence of local f{sub NL}

    SciTech Connect

    Byrnes, Christian T.; Nurmi, Sami; Tasinato, Gianmassimo; Wands, David E-mail: s.nurmi@thphys.uni-heidelberg.de E-mail: david.wands@port.ac.uk

    2010-02-01

    We consider possible scale-dependence of the non-linearity parameter f{sub NL} in local and quasi-local models of non-Gaussian primordial density perturbations. In the simplest model where the primordial perturbations are a quadratic local function of a single Gaussian field then f{sub NL} is scale-independent by construction. However scale-dependence can arise due to either a local function of more than one Gaussian field, or due to non-linear evolution of modes after horizon-exit during inflation. We show that the scale dependence of f{sub NL} is typically first order in slow-roll. For some models this may be observable with experiments such as Planck provided that f{sub NL} is close to the current observational bounds.

  6. Fabrication of nanometer- and micrometer-scale protein structures by site-specific immobilization of histidine-tagged proteins to aminosiloxane films with photoremovable protein-resistant protecting groups

    DOE PAGES

    Xia, Sijing; Cartron, Michael; Morby, James; ...

    2016-01-28

    The site-specific immobilization of histidine-tagged proteins to patterns formed by far-field and near-field exposure of films of aminosilanes with protein-resistant photolabile protecting groups is demonstrated. After deprotection of the aminosilane, either through a mask or using a scanning near-field optical microscope, the amine terminal groups are derivatized first with glutaraldehyde and then with N-(5-amino-1-carboxypentyl)iminodiacetic acid to yield a nitrilo-triacetic-acid-terminated surface. After complexation with Ni2+, this surface binds histidine-tagged GFP and CpcA-PEB in a site-specific fashion. The chemistry is simple and reliable and leads to extensive surface functionalization. Bright fluorescence is observed in fluorescence microscopy images of micrometer- and nanometer-scale patterns.more » X-ray photoelectron spectroscopy is used to study quantitatively the efficiency of photodeprotection and the reactivity of the modified surfaces. The efficiency of the protein binding process is investigated quantitatively by ellipsometry and by fluorescence microscopy. We find that regions of the surface not exposed to UV light bind negligible amounts of His-tagged proteins, indicating that the oligo(ethylene glycol) adduct on the nitrophenyl protecting group confers excellent protein resistance; in contrast, exposed regions bind His-GFP very effectively, yielding strong fluorescence that is almost completely removed on treatment of the surface with imidazole, confirming a degree of site-specific binding in excess of 90%. As a result, this simple strategy offers a versatile generic route to the spatially selective site-specific immobilization of proteins at surfaces.« less

  7. Fabrication of Nanometer- and Micrometer-Scale Protein Structures by Site-Specific Immobilization of Histidine-Tagged Proteins to Aminosiloxane Films with Photoremovable Protein-Resistant Protecting Groups

    PubMed Central

    2016-01-01

    The site-specific immobilization of histidine-tagged proteins to patterns formed by far-field and near-field exposure of films of aminosilanes with protein-resistant photolabile protecting groups is demonstrated. After deprotection of the aminosilane, either through a mask or using a scanning near-field optical microscope, the amine terminal groups are derivatized first with glutaraldehyde and then with N-(5-amino-1-carboxypentyl)iminodiacetic acid to yield a nitrilo-triacetic-acid-terminated surface. After complexation with Ni2+, this surface binds histidine-tagged GFP and CpcA-PEB in a site-specific fashion. The chemistry is simple and reliable and leads to extensive surface functionalization. Bright fluorescence is observed in fluorescence microscopy images of micrometer- and nanometer-scale patterns. X-ray photoelectron spectroscopy is used to study quantitatively the efficiency of photodeprotection and the reactivity of the modified surfaces. The efficiency of the protein binding process is investigated quantitatively by ellipsometry and by fluorescence microscopy. We find that regions of the surface not exposed to UV light bind negligible amounts of His-tagged proteins, indicating that the oligo(ethylene glycol) adduct on the nitrophenyl protecting group confers excellent protein resistance; in contrast, exposed regions bind His-GFP very effectively, yielding strong fluorescence that is almost completely removed on treatment of the surface with imidazole, confirming a degree of site-specific binding in excess of 90%. This simple strategy offers a versatile generic route to the spatially selective site-specific immobilization of proteins at surfaces. PMID:26820378

  8. Behavior of local dissipation scales in turbulent pipe flow

    NASA Astrophysics Data System (ADS)

    Bailey, Sean; Hultmark, Marcus; Schumacher, Joerg; Yakhot, Victor; Smits, Alexander

    2010-11-01

    Classically, dissipation of turbulence has been thought to occur around the Kolmogorov scales. However, the Kolmogorov scales are prescribed using mean dissipation rate, whereas dissipation is spatially intermittent. It therefore seems natural to instead describe dissipation using a continuum of local length scales rather than a single scale. By connecting a local dissipation scale η to the velocity increment across this scale δuη, it is possible to derive a probability density function (PDF) of η which show how the dissipation is contained in scales larger and smaller than the Kolmogorov scale. Here we present a comparison between measured PDFs in turbulent pipe flow, the analytically derived PDF, and PDFs determined from direct numerical simulation of homogeneous isotropic turbulence. It was found that there is good general agreement between experiment, simulation and theory amongst both homogeneous and inhomogeneous turbulent flows, pointing to universality in the dissipation scales amongst different flows. It was also found that the PDFs are invariant with distance from the wall except for a region very near the wall (y^+<80), where dissipation was found to occur at increasingly larger length scales as the wall is approached.

  9. Level Indicator On A Tubular Inside Micrometer

    NASA Technical Reports Server (NTRS)

    Malinzak, R. Michael; Booth, Gary N.

    1995-01-01

    Leveling helps to ensure accurate measurements. Attachment helpful because in some situations that involve measurement of large, tight-tolerance inside dimensions, inside micrometers not held level between contact point give inaccurate readings. User adjusts position and orientation of micrometer and verifies level by observing bubble in level indicator. Upon feeling correct drag between micrometer tips and workpiece, user confident that tool used correctly and accurate measurement obtained.

  10. Local scale invariance for wetting and confined interfaces

    NASA Astrophysics Data System (ADS)

    Parry, A. O.; Rascón, C.

    2010-03-01

    When a fluid or Ising-like magnet is confined between two parallel walls that are each completely wet by different bulk phases, the interface separating the phases is subject to large-scale fluctuations determined by the slit width. It was noted some time ago that, in two dimensions, the scaling expression for the probability distribution function describing the interfacial height across the slit shows remarkable similarities with predictions of conformal invariance. However, this local scale invariance appears to contradict the strongly anisotropic nature of (1 + 1)-dimensional interfacial fluctuations along and perpendicular to the interface, characterized by the wandering exponent. In this paper, we show that similarity with conformal invariance is not coincidental and can be understood explicitly as the projection of a local scale invariance for a wandering line in 2 + 1 dimensions.

  11. Scaling and localization of polaritonic states in piezoelectric Fibonacci superlattices

    NASA Astrophysics Data System (ADS)

    Liu, Zhenxing; Zhang, Weiyi

    2005-10-01

    The scaling and localization properties of polaritonic states in piezoelectric Fibonacci superlattices are studied using the generalized 4×4 transfer matrix method. The dynamics of electromagnetic waves and acoustic waves is treated on equal footing. Both polaritonic band structures and transmission spectra possess the pattern of the Cantorset with respect to generations. The scaling parameter α'=4.236 is in agreement with the previous studies on pure electronic and phononic Fibonacci superlattices. Furthermore, the fractal nature of the transmission spectra serves as a proof for the (quasi)localization of polaritons which should be observable in experiments.

  12. Multi-scale non-local denoising method in neuroimaging.

    PubMed

    Chen, Yiping; Wang, Cheng; Wang, Liansheng

    2016-03-17

    Non-local means algorithm can remove image noise in a unique way that is contrary to traditional techniques. This is because it not only smooths the image but it also preserves the information details of the image. However, this method suffers from high computational complexity. We propose a multi-scale non-local means method in which adaptive multi-scale technique is implemented. In practice, based on each selected scale, the input image is divided into small blocks. Then, we remove the noise in the given pixel by using only one block. This can overcome the low efficiency problem caused by the original non-local means method. Our proposed method also benefits from the local average gradient orientation. In order to perform evaluation, we compared the processed images based on our technique with the ones by the original and the improved non-local means denoising method. Extensive experiments are conducted and results shows that our method is faster than the original and the improved non-local means method. It is also proven that our implemented method is robust enough to remove noise in the application of neuroimaging.

  13. Micrometer glass nozzles for flow focusing

    NASA Astrophysics Data System (ADS)

    Montanero, J. M.; Gañán-Calvo, A. M.; Acero, A. J.; Vega, E. J.

    2010-07-01

    We discuss the use of flame-shaped glass micro-nozzles for ultra-fine liquid atomization by flow focusing (DePonte et al 2008 J. Phys. D: Appl. Phys. 41 195505), which may have great importance in very varied technological fields, such as biotechnology, biomedicine and analytical chemistry. Some advantages offered by these nozzles over the original plate orifice configuration (Gañán-Calvo 1998 Phys. Rev. Lett. 80 285) are: (i) they are extraordinarily smooth even at the micrometer scale, (ii) one can readily obtain nozzles with neck diameters in the range of a few tens of microns, (iii) they demand gas flow rates significantly smaller than those required by the plate orifice configuration and (iv) they are transparent. However, highly demanding applications require a precise characterization of their three-dimensional shape by non-destructive means. This characterization cannot be obtained straightforwardly from optical transmission or electron microscopy mainly due to optical distortion. We propose in this paper a method for measuring the shape and size of micrometer nozzles formed inside millimetric and submillimetric capillaries made of transparent materials. The inside of the capillary is colored, and the capillary is put in a liquid bath with almost the same refractive index as that of the capillary to eliminate optical distortion. The nozzle image, acquired with a microscope using back-light illumination to get a silhouette effect, is processed to locate the contours of the nozzle with sub-pixel resolution. To determine the three-dimensional shape of the nozzle, the capillary is rotated in front of the camera. The method provides precise results for nozzle sizes down to a few microns.

  14. Multi-Scale Jacobi Method for Anderson Localization

    NASA Astrophysics Data System (ADS)

    Imbrie, John Z.

    2015-11-01

    A new KAM-style proof of Anderson localization is obtained. A sequence of local rotations is defined, such that off-diagonal matrix elements of the Hamiltonian are driven rapidly to zero. This leads to the first proof via multi-scale analysis of exponential decay of the eigenfunction correlator (this implies strong dynamical localization). The method has been used in recent work on many-body localization (Imbrie in On many-body localization for quantum spin chains, arXiv:1403.7837 , 2014).

  15. Local Large-Scale Structure and the Assumption of Homogeneity

    NASA Astrophysics Data System (ADS)

    Keenan, Ryan C.; Barger, Amy J.; Cowie, Lennox L.

    2016-10-01

    Our recent estimates of galaxy counts and the luminosity density in the near-infrared (Keenan et al. 2010, 2012) indicated that the local universe may be under-dense on radial scales of several hundred megaparsecs. Such a large-scale local under-density could introduce significant biases in the measurement and interpretation of cosmological observables, such as the inferred effects of dark energy on the rate of expansion. In Keenan et al. (2013), we measured the K-band luminosity density as a function of distance from us to test for such a local under-density. We made this measurement over the redshift range 0.01 < z < 0.2 (radial distances D ~ 50 - 800 h 70 -1 Mpc). We found that the shape of the K-band luminosity function is relatively constant as a function of distance and environment. We derive a local (z < 0.07, D < 300 h 70 -1 Mpc) K-band luminosity density that agrees well with previously published studies. At z > 0.07, we measure an increasing luminosity density that by z ~ 0.1 rises to a value of ~ 1.5 times higher than that measured locally. This implies that the stellar mass density follows a similar trend. Assuming that the underlying dark matter distribution is traced by this luminous matter, this suggests that the local mass density may be lower than the global mass density of the universe at an amplitude and on a scale that is sufficient to introduce significant biases into the measurement of basic cosmological observables. At least one study has shown that an under-density of roughly this amplitude and scale could resolve the apparent tension between direct local measurements of the Hubble constant and those inferred by Planck team. Other theoretical studies have concluded that such an under-density could account for what looks like an accelerating expansion, even when no dark energy is present.

  16. Comparison of local magnitude scales in Central Europe

    NASA Astrophysics Data System (ADS)

    Kysel, Robert; Kristek, Jozef; Moczo, Peter; Cipciar, Andrej; Csicsay, Kristian; Srbecky, Miroslav; Kristekova, Miriam

    2015-04-01

    Efficient monitoring of earthquakes and determination of their magnitudes are necessary for developing earthquake catalogues at a regional and national levels. Unification and homogenization of the catalogues in terms of magnitudes has great importance for seismic hazard assessment. Calibrated local earthquake magnitude scales are commonly used for determining magnitudes of regional earthquakes by all national seismological services in the Central Europe. However, at the local scale, each seismological service uses its own magnitude determination procedure. There is no systematic comparison of the approaches and there is no unified procedure. We present a comparison of the local magnitude scales used by the national seismological services of Slovakia (Geophysical Institute, Slovak Academy of Sciences), Czech Republic (Institute of Geophysics, Academy of Sciences of the Czech Republic), Austria (ZAMG), Hungary (Geodetic and Geophysical Institute, Hungarian Academy of Sciences) and Poland (Institute of Geophysics, Polish Academy of Sciences), and by the local network of seismic stations located around the Nuclear Power Plant Jaslovske Bohunice, Slovakia. The comparison is based on the national earthquake catalogues and annually published earthquake bulletins for the period from 1985 to 2011. A data set of earthquakes has been compiled based on identification of common events in the national earthquake catalogues and bulletins. For each pair of seismic networks, magnitude differences have been determined and investigated as a function of time. The mean and standard deviations of the magnitude differences as well as regression coefficients between local magnitudes from the national seismological networks have been computed. Results show relatively big scatter between different national local magnitudes and its considerable time variation. A conversion between different national local magnitudes in a scale 1:1 seems inappropriate, especially for the compilation of the

  17. Local Literacies, Global Scales: The Labor of Global Connectivity

    ERIC Educational Resources Information Center

    Stornaiuolo, Amy; LeBlanc, Robert Jean

    2014-01-01

    While connecting students and teachers in new configurations using digital technologies offers great promise for literacy and learning, this column considers the complexities of negotiating local and global literacies in global collaborations. It introduces the theoretical concept of "scaling" to highlight the ways teachers actively and…

  18. Local Literacies, Global Scales: The Labor of Global Connectivity

    ERIC Educational Resources Information Center

    Stornaiuolo, Amy; LeBlanc, Robert Jean

    2014-01-01

    While connecting students and teachers in new configurations using digital technologies offers great promise for literacy and learning, this column considers the complexities of negotiating local and global literacies in global collaborations. It introduces the theoretical concept of "scaling" to highlight the ways teachers actively and…

  19. Local variance for multi-scale analysis in geomorphometry

    PubMed Central

    Drăguţ, Lucian; Eisank, Clemens; Strasser, Thomas

    2011-01-01

    Increasing availability of high resolution Digital Elevation Models (DEMs) is leading to a paradigm shift regarding scale issues in geomorphometry, prompting new solutions to cope with multi-scale analysis and detection of characteristic scales. We tested the suitability of the local variance (LV) method, originally developed for image analysis, for multi-scale analysis in geomorphometry. The method consists of: 1) up-scaling land-surface parameters derived from a DEM; 2) calculating LV as the average standard deviation (SD) within a 3 × 3 moving window for each scale level; 3) calculating the rate of change of LV (ROC-LV) from one level to another, and 4) plotting values so obtained against scale levels. We interpreted peaks in the ROC-LV graphs as markers of scale levels where cells or segments match types of pattern elements characterized by (relatively) equal degrees of homogeneity. The proposed method has been applied to LiDAR DEMs in two test areas different in terms of roughness: low relief and mountainous, respectively. For each test area, scale levels for slope gradient, plan, and profile curvatures were produced at constant increments with either resampling (cell-based) or image segmentation (object-based). Visual assessment revealed homogeneous areas that convincingly associate into patterns of land-surface parameters well differentiated across scales. We found that the LV method performed better on scale levels generated through segmentation as compared to up-scaling through resampling. The results indicate that coupling multi-scale pattern analysis with delineation of morphometric primitives is possible. This approach could be further used for developing hierarchical classifications of landform elements. PMID:21779138

  20. Local variance for multi-scale analysis in geomorphometry

    NASA Astrophysics Data System (ADS)

    Drăguţ, Lucian; Eisank, Clemens; Strasser, Thomas

    2011-07-01

    Increasing availability of high resolution Digital Elevation Models (DEMs) is leading to a paradigm shift regarding scale issues in geomorphometry, prompting new solutions to cope with multi-scale analysis and detection of characteristic scales. We tested the suitability of the local variance (LV) method, originally developed for image analysis, for multi-scale analysis in geomorphometry. The method consists of: 1) up-scaling land-surface parameters derived from a DEM; 2) calculating LV as the average standard deviation (SD) within a 3 × 3 moving window for each scale level; 3) calculating the rate of change of LV (ROC-LV) from one level to another, and 4) plotting values so obtained against scale levels. We interpreted peaks in the ROC-LV graphs as markers of scale levels where cells or segments match types of pattern elements characterized by (relatively) equal degrees of homogeneity. The proposed method has been applied to LiDAR DEMs in two test areas different in terms of roughness: low relief and mountainous, respectively. For each test area, scale levels for slope gradient, plan, and profile curvatures were produced at constant increments with either resampling (cell-based) or image segmentation (object-based). Visual assessment revealed homogeneous areas that convincingly associate into patterns of land-surface parameters well differentiated across scales. We found that the LV method performed better on scale levels generated through segmentation as compared to up-scaling through resampling. The results indicate that coupling multi-scale pattern analysis with delineation of morphometric primitives is possible. This approach could be further used for developing hierarchical classifications of landform elements.

  1. On the locality of magnetohydrodynamic turbulence scale fluxes

    SciTech Connect

    Teaca, Bogdan; Carati, Daniele; Andrzej Domaradzki, J.

    2011-11-15

    The scale locality of energy fluxes for magnetohydrodynamics (MHD) is investigated numerically for stationary states of turbulence. Two types of forces are used to drive turbulence, a kinetic force that acts only on the velocity field and a kinetic-inductive force, which acts on the velocity and magnetic fields alike. The analysis is performed in spectral space, which is decomposed into a series of shells following a power law for the boundaries. The triadic transfers occurring among these shells are computed, and the fluxes and locality functions are obtained by partial summation over the relevant shells. Employing Kraichnan locality functions, values of 1/3 and 2/3 for the scaling exponents of the four MHD energy fluxes are found. These values are smaller than the value of 4/3 found for hydrodynamic turbulence. To better understand these results, an in depth analysis is performed on the total energy flux.

  2. Time scales of tunneling decay of a localized state

    SciTech Connect

    Ban, Yue; Muga, J. G.; Sherman, E. Ya.; Buettiker, M.

    2010-12-15

    Motivated by recent time-domain experiments on ultrafast atom ionization, we analyze the transients and time scales that characterize, aside from the relatively long lifetime, the decay of a localized state by tunneling. While the tunneling starts immediately, some time is required for the outgoing flux to develop. This short-term behavior depends strongly on the initial state. For the initial state, tightly localized so that the initial transients are dominated by over-the-barrier motion, the time scale for flux propagation through the barrier is close to the Buettiker-Landauer traversal time. Then a quasistationary, slow-decay process follows, which sets ideal conditions for observing diffraction in time at longer times and distances. To define operationally a tunneling time at the barrier edge, we extrapolate backward the propagation of the wave packet that escaped from the potential. This extrapolated time is considerably longer than the time scale of the flux and density buildup at the barrier edge.

  3. Local-scale and watershed-scale determinants of summertime urban stream temperatures

    Treesearch

    Derek B. Booth; Kristin A. Kraseski; C. Rhett. Jackson

    2014-01-01

    The influence of urbanization on the temperature of small streams is widely recognized, but these effects are confounded by the great natural variety of their contributing watersheds. To evaluate the relative importance of local-scale and watershed-scale factors on summer temperatures in urban streams, hundreds of near-instantaneous temperature measurements throughout...

  4. Local and Regional Impacts of Large Scale Wind Energy Deployment

    NASA Astrophysics Data System (ADS)

    Michalakes, J.; Hammond, S.; Lundquist, J. K.; Moriarty, P.; Robinson, M.

    2010-12-01

    The U.S. is currently on a path to produce 20% of its electricity from wind energy by 2030, almost a 10-fold increase over present levels of electricity generated from wind. Such high-penetration wind energy deployment will entail extracting elevated energy levels from the planetary boundary layer and preliminary studies indicate that this will have significant but uncertain impacts on the local and regional environment. State and federal regulators have raised serious concerns regarding potential agricultural impacts from large farms deployed throughout the Midwest where agriculture is the basis of the local economy. The effects of large wind farms have been proposed to be both beneficial (drying crops to reduce occurrences of fungal diseases, avoiding late spring freezes, enhancing pollen viability, reducing dew duration) and detrimental (accelerating moisture loss during drought) with no conclusive investigations thus far. As both wind and solar technologies are deployed at scales required to replace conventional technologies, there must be reasonable certainty that the potential environmental impacts at the micro, macro, regional and global scale do not exceed those anticipated from carbon emissions. Largely because of computational limits, the role of large wind farms in affecting regional-scale weather patterns has only been investigated in coarse simulations and modeling tools do not yet exist which are capable of assessing the downwind affects of large wind farms may have on microclimatology. In this presentation, we will outline the vision for and discuss technical and scientific challenges in developing a multi-model high-performance simulation capability covering the range of mesoscale to sub-millimeter scales appropriate for assessing local, regional, and ultimately global environmental impacts and quantifying uncertainties of large scale wind energy deployment scenarios. Such a system will allow continuous downscaling of atmospheric processes on wind

  5. Improved scaling of temperature-accelerated dynamics using localization.

    PubMed

    Shim, Yunsic; Amar, Jacques G

    2016-07-07

    While temperature-accelerated dynamics (TAD) is a powerful method for carrying out non-equilibrium simulations of systems over extended time scales, the computational cost of serial TAD increases approximately as N(3) where N is the number of atoms. In addition, although a parallel TAD method based on domain decomposition [Y. Shim et al., Phys. Rev. B 76, 205439 (2007)] has been shown to provide significantly improved scaling, the dynamics in such an approach is only approximate while the size of activated events is limited by the spatial decomposition size. Accordingly, it is of interest to develop methods to improve the scaling of serial TAD. As a first step in understanding the factors which determine the scaling behavior, we first present results for the overall scaling of serial TAD and its components, which were obtained from simulations of Ag/Ag(100) growth and Ag/Ag(100) annealing, and compare with theoretical predictions. We then discuss two methods based on localization which may be used to address two of the primary "bottlenecks" to the scaling of serial TAD with system size. By implementing both of these methods, we find that for intermediate system-sizes, the scaling is improved by almost a factor of N(1/2). Some additional possible methods to improve the scaling of TAD are also discussed.

  6. Islands Climatology at Local Scale. Downscaling with CIELO model

    NASA Astrophysics Data System (ADS)

    Azevedo, Eduardo; Reis, Francisco; Tomé, Ricardo; Rodrigues, Conceição

    2016-04-01

    Islands with horizontal scales of the order of tens of km, as is the case of the Atlantic Islands of Macaronesia, are subscale orographic features for Global Climate Models (GCMs) since the horizontal scales of these models are too coarse to give a detailed representation of the islands' topography. Even the Regional Climate Models (RCMs) reveals limitations when they are forced to reproduce the climate of small islands mainly by the way they flat and lowers the elevation of the islands, reducing the capacity of the model to reproduce important local mechanisms that lead to a very deep local climate differentiation. Important local thermodynamics mechanisms like Foehn effect, or the influence of topography on radiation balance, have a prominent role in the climatic spatial differentiation. Advective transport of air - and the consequent induced adiabatic cooling due to orography - lead to transformations of the state parameters of the air that leads to the spatial configuration of the fields of pressure, temperature and humidity. The same mechanism is in the origin of the orographic clouds cover that, besides the direct role as water source by the reinforcement of precipitation, act like a filter to direct solar radiation and as a source of long-wave radiation that affect the local balance of energy. Also, the saturation (or near saturation) conditions that they provide constitute a barrier to water vapour diffusion in the mechanisms of evapotranspiration. Topographic factors like slope, aspect and orographic mask have also significant importance in the local energy balance. Therefore, the simulation of the local scale climate (past, present and future) in these archipelagos requires the use of downscaling techniques to adjust locally outputs obtained at upper scales. This presentation will discuss and analyse the evolution of the CIELO model (acronym for Clima Insular à Escala LOcal) a statistical/dynamical technique developed at the University of the Azores

  7. 11 micrometer emissivities and droplet radii for marine stratocumulus

    NASA Technical Reports Server (NTRS)

    Luo, Gang; Lin, Xijian; Coakley, James A.

    1994-01-01

    The results of a new multispectral infrared retrieval scheme for obtaining fractional cloud cover and 11 micrometer emissivity with those of the spatial coherence method which obtains fractional cloud cover assuming that the clouds are opaque at infrared wavelengths. Both methods are applied to 4-km NOAA advanced very high resolution radiometer global area coverage data for 250-km-scale regions containing single-layered marine stratocumulus off the coast of South America. The average 11 micrometer emissivity for low level clouds is found to be between 0.70 and 0.85. The low emissivity is evidently due to the thinning of clouds at their edges. Semitransparent cloud edges evidently make up a substantial portion of the area covered by such clouds. This result indicates that cloud cover obtained using the spatial coherence method is underestimated by 0.1 to 0.2, as has been claimed in a previous study. The fractional cloud cover for the ensemble of 250-km-scale regions studied here increased slightly from 0.60 for daytime observations to 0.63 for nighttime observations. The 11 micrometer emissivity also increased slightly, but about half of the increase was related to the increase in cloud cover and a decrease in the relative area covered by cloud edge material. Presumably, the other half was due to an increase in cloud liquid water. Cloud height showed no significant change. The average effective droplet radius increased from 9.3 micrometers for daytime observations to 10.2 micrometers at night.

  8. 11 micrometer emissivities and droplet radii for marine stratocumulus

    NASA Technical Reports Server (NTRS)

    Luo, Gang; Lin, Xijian; Coakley, James A.

    1994-01-01

    The results of a new multispectral infrared retrieval scheme for obtaining fractional cloud cover and 11 micrometer emissivity with those of the spatial coherence method which obtains fractional cloud cover assuming that the clouds are opaque at infrared wavelengths. Both methods are applied to 4-km NOAA advanced very high resolution radiometer global area coverage data for 250-km-scale regions containing single-layered marine stratocumulus off the coast of South America. The average 11 micrometer emissivity for low level clouds is found to be between 0.70 and 0.85. The low emissivity is evidently due to the thinning of clouds at their edges. Semitransparent cloud edges evidently make up a substantial portion of the area covered by such clouds. This result indicates that cloud cover obtained using the spatial coherence method is underestimated by 0.1 to 0.2, as has been claimed in a previous study. The fractional cloud cover for the ensemble of 250-km-scale regions studied here increased slightly from 0.60 for daytime observations to 0.63 for nighttime observations. The 11 micrometer emissivity also increased slightly, but about half of the increase was related to the increase in cloud cover and a decrease in the relative area covered by cloud edge material. Presumably, the other half was due to an increase in cloud liquid water. Cloud height showed no significant change. The average effective droplet radius increased from 9.3 micrometers for daytime observations to 10.2 micrometers at night.

  9. Differentiated Response of Snowpack to Climate Change at Local Scale

    NASA Astrophysics Data System (ADS)

    Pons, M.; López Moreno, J. I.; Rosas-Casals, M.; Jover, E.

    2014-12-01

    Local factors such as topography, aspect, elevation or local wind can significantly affect the spatial distribution of snow. This study intends to understand the effect of these factors and model a differentiated response of snowpack to climate change at small scale. In order to accomplish this objective, a network of wind, temperature and humidity sensors has been deployed in two different ski areas of the Pyrenees to monitor and analyze the effect of local factors on these variables. Moreover, snow depth and density, snowmaking working and time-lapse imagery of slopes will be analyzed during a winter season in order to better understand the snowpack changes and distribution due to local factors and the technical work on the ski resorts. The main aim of this study is to better understand the differentiated response of the snowpack at small scale considering local factors in order to improve and enhance the efficiency of the present daily management for example in ski resort areas and the planning of future adaptation strategies to climate change.

  10. Polymer reversal rate calculated via locally scaled diffusion map.

    PubMed

    Zheng, Wenwei; Rohrdanz, Mary A; Maggioni, Mauro; Clementi, Cecilia

    2011-04-14

    A recent study on the dynamics of polymer reversal inside a nanopore by Huang and Makarov [J. Chem. Phys. 128, 114903 (2008)] demonstrated that the reaction rate cannot be reproduced by projecting the dynamics onto a single empirical reaction coordinate, a result suggesting the dynamics of this system cannot be correctly described by using a single collective coordinate. To further investigate this possibility we have applied our recently developed multiscale framework, locally scaled diffusion map (LSDMap), to obtain collective reaction coordinates for this system. Using a single diffusion coordinate, we obtain a reversal rate via Kramers expression that is in good agreement with the exact rate obtained from the simulations. Our mathematically rigorous approach accounts for the local heterogeneity of molecular configuration space in constructing a diffusion map, from which collective coordinates emerge. We believe this approach can be applied in general to characterize complex macromolecular dynamics by providing an accurate definition of the collective coordinates associated with processes at different time scales.

  11. Is local best? Examining the evidence for local adaptation in trees and its scale

    Treesearch

    David Boshier; Linda Broadhurst; Jonathan Cornelius; Leonardo Gallo; Jarkko Koskela; Judy Loo; Gillian Petrokofsky; Brad St. Clair

    2015-01-01

    Background: Although the importance of using local provenance planting stock for woodland production, habitat conservation and restoration remains contentious, the concept is easy to understand, attractive and easy to ‘sell’. With limited information about the extent and scale of adaptive variation in native trees, discussion about suitable...

  12. Local Scale Transformations on the Lattice with Tensor Network Renormalization

    NASA Astrophysics Data System (ADS)

    Evenbly, G.; Vidal, G.

    2016-01-01

    Consider the partition function of a classical system in two spatial dimensions, or the Euclidean path integral of a quantum system in two space-time dimensions, both on a lattice. We show that the tensor network renormalization algorithm [G. Evenbly and G. Vidal Phys. Rev. Lett. 115, 180405 (2015)] can be used to implement local scale transformations on these objects, namely, a lattice version of conformal maps. Specifically, we explain how to implement the lattice equivalent of the logarithmic conformal map that transforms the Euclidean plane into a cylinder. As an application, and with the 2D critical Ising model as a concrete example, we use this map to build a lattice version of the scaling operators of the underlying conformal field theory, from which one can extract their scaling dimensions and operator product expansion coefficients.

  13. Local Scale Transformations on the Lattice with Tensor Network Renormalization.

    PubMed

    Evenbly, G; Vidal, G

    2016-01-29

    Consider the partition function of a classical system in two spatial dimensions, or the Euclidean path integral of a quantum system in two space-time dimensions, both on a lattice. We show that the tensor network renormalization algorithm [G. Evenbly and G. Vidal Phys. Rev. Lett. 115, 180405 (2015)] can be used to implement local scale transformations on these objects, namely, a lattice version of conformal maps. Specifically, we explain how to implement the lattice equivalent of the logarithmic conformal map that transforms the Euclidean plane into a cylinder. As an application, and with the 2D critical Ising model as a concrete example, we use this map to build a lattice version of the scaling operators of the underlying conformal field theory, from which one can extract their scaling dimensions and operator product expansion coefficients.

  14. Thermal Behaviour of Unusual Local-Scale Surface Features on Vesta

    NASA Technical Reports Server (NTRS)

    Tosi, F.; Capria, M. T.; De Sanctis, M. C.; Palomba, E.; Grassi, D.; Capaccioni, F.; Ammannito, E.; Combe, J.-Ph.; Sunshine, J. M.; McCord, T. B.; hide

    2012-01-01

    On Vesta, the region of the infrared spectrum beyond approximately 3.5 micrometers is dominated by the thermal emission of the asteroid's surface, which can be used to determine surface temperature by means of temperature-retrieval algorithms. The thermal behavior of areas of unusual albedo seen at the local scale can be related to physical properties that can provide information about the origin of those materials. Dawn's Visible and Infrared Mapping Spectrometer (VIR) hyperspectral cubes are used to retrieve surface temperatures, with high accuracy as long as temperatures are greater than 180 K. Data acquired in the Survey phase (23 July through 29 August 2011) show several unusual surface features: 1) high-albedo (bright) and low-albedo (dark) material deposits, 2) spectrally distinct ejecta, 3) regions suggesting finer-grained materials. Some of the unusual dark and bright features were re-observed by VIR in the subsequent High-Altitude Mapping Orbit (HAMO) and Low-Altitude Mapping Orbit (LAMO) phases at increased pixel resolution. To calculate surface temperatures, we applied a Bayesian approach to nonlinear inversion based on the Kirchhoff law and the Planck function. These results were cross-checked through application of alternative methods. Here we present temperature maps of several local-scale features that were observed by Dawn under different illumination conditions and different local solar times. Some bright terrains have an overall albedo in the visible as much as 40% brighter than surrounding areas. Data from the IR channel of VIR show that bright regions generally correspond to regions with lower thermal emission, i.e. lower temperature, while dark regions correspond to areas with higher thermal emission, i.e. higher temperature. This behavior confirms that many of the dark appearances in the VIS mainly reflect albedo variations. In particular, it is shown that during maximum daily insolation, dark features in the equatorial region may rise to

  15. Photon counting micrometer and video CCD.

    NASA Astrophysics Data System (ADS)

    Tie, Qiongxian; Li, Chennfei

    The structure and observational method of the photon counting slotted micrometer are proposed. The micrometer is made up of a piece of slotted plate and a photomultiplier. The photon counting micrometer is replaced by a video CCD for regular trial observation and as a test for the equipment of one scientific CCD, because the micrometer transmission in the instrumental vertical angle transmission mechanism is dull, and the telescope is not able to observe regularly since the optical axis changes greatly as the telescope points to different vertical distance. The video CCD is fixed in the course of observation, recording a picture every forty milliseconds, or one hundred pictures within four seconds, resulting in simultaneously after smoothing treatment the moment and stellar zenith distance when a star passes through the meridian or prime vertical.

  16. Local versus global scales of organization in auditory cortex

    PubMed Central

    Kanold, Patrick O.; Nelken, Israel; Polley, Daniel B.

    2014-01-01

    Topographic organization is a hallmark of sensory cortical organization. Topography is robust at spatial scales ranging from hundreds of microns to centimeters, but can dissolve at the level of neighboring neurons or subcellular compartments within a neuron. This dichotomous spatial organization is especially pronounced in the mouse auditory cortex, where an orderly tonotopic map can arise from heterogeneous frequency tuning between local neurons. Here, we address a debate surrounding the robustness of tonotopic organization in the auditory cortex that has persisted in some form for over forty years. Drawing from various cortical areas, cortical layers, recording methodologies, and species, we describe how auditory cortical circuitry can simultaneously support a globally systematic, yet locally heterogeneous representation of this fundamental sound property. PMID:25002236

  17. Determination of reaction coordinates via locally scaled diffusion map

    NASA Astrophysics Data System (ADS)

    Rohrdanz, Mary A.; Zheng, Wenwei; Maggioni, Mauro; Clementi, Cecilia

    2011-03-01

    We present a multiscale method for the determination of collective reaction coordinates for macromolecular dynamics based on two recently developed mathematical techniques: diffusion map and the determination of local intrinsic dimensionality of large datasets. Our method accounts for the local variation of molecular configuration space, and the resulting global coordinates are correlated with the time scales of the molecular motion. To illustrate the approach, we present results for two model systems: all-atom alanine dipeptide and coarse-grained src homology 3 protein domain. We provide clear physical interpretation for the emerging coordinates and use them to calculate transition rates. The technique is general enough to be applied to any system for which a Boltzmann-sampled set of molecular configurations is available.

  18. Conductance of finite systems and scaling in localization theory

    SciTech Connect

    Suslov, I. M.

    2012-11-15

    The conductance of finite systems plays a central role in the scaling theory of localization (Abrahams et al., Phys. Rev. Lett. 42, 673 (1979)). Usually it is defined by the Landauer-type formulas, which remain open the following questions: (a) exclusion of the contact resistance in the many-channel case; (b) correspondence of the Landauer conductance with internal properties of the system; (c) relation with the diffusion coefficient D({omega}, q) of an infinite system. The answers to these questions are obtained below in the framework of two approaches: (1) self-consistent theory of localization by Vollhardt and Woelfle, and (2) quantum mechanical analysis based on the shell model. Both approaches lead to the same definition for the conductance of a finite system, closely related to the Thouless definition. In the framework of the self-consistent theory, the relations of finite-size scaling are derived and the Gell-Mann-Low functions {beta}(g) for space dimensions d = 1, 2, 3 are calculated. In contrast to the previous attempt by Vollhardt and Woelfle (1982), the metallic and localized phase are considered from the same standpoint, and the conductance of a finite system has no singularity at the critical point. In the 2D case, the expansion of {beta}(g) in 1/g coincides with results of the {sigma}-model approach on the two-loop level and depends on the renormalization scheme in higher loops; the use of dimensional regularization for transition to dimension d = 2 + {epsilon} looks incompatible with the physical essence of the problem. The results are compared with numerical and physical experiments. A situation in higher dimensions and the conditions for observation of the localization law {sigma}({omega}) {proportional_to} -i{omega} for conductivity are discussed.

  19. Thermal Properties of Unusual Local-Scale Features on Vesta

    NASA Technical Reports Server (NTRS)

    Capria, M.; DeSanctis, M.; Palomba, E.; Grassi, D.; Capaccioni, F.; Ammannito, E.; Combe, J.; Sunshine, J. M.; Titus, T. N.; Mittlefehldt, D. W.; Li, J.; Russell, C. T.; Raymond, C. A.

    2012-01-01

    On Vesta, the thermal behavior of areas of unusual albedo seen at the local scale can be related to physical properties that can provide information about the origin of those materials. We used Dawn s Visible and Infrared Mapping Spectrometer (VIR) hyperspectral cubes to retrieve surface temperatures and emissivities, with high accuracy as long as temperatures are greater than 180 K. Data acquired in the Survey phase (23 July through 29 August 2011) show several unusual surface features: 1) high-albedo (bright) and low-albedo (dark) material deposits, 2) spectrally distinct ejecta and pitted materials, 3) regions suggesting finer-grained materials. Some of the unusual dark and bright features were reobserved by VIR in the subsequent High-Altitude Mapping Orbit (HAMO) and Low- Altitude Mapping Orbit (LAMO) phases at increased pixel resolution. In this work we present temperature maps and emissivities of several local-scale features that were observed by Dawn under different illumination conditions and different local solar times. Data from VIR's IR channel show that bright regions generally correspond to regions with lower thermal emission, i.e. lower temperature, while dark regions correspond to areas with higher thermal emission, i.e. higher temperature. This behavior confirms that many of the dark appearances in the VIS mainly reflect albedo variations, and not, for example, shadowing. During maximum daily insolation, dark features in the equatorial region may rise to temperatures greater than 270 K, while brightest features stop at roughly 258 K, local solar time being similar. However, pitted materials, showing relatively low reflectance, have significantly lower temperatures, as a result of differences in composition and/or structure (e.g, average grain size of the surface regolith, porosity, etc.). To complement this work, we provide preliminary values of thermal inertia for some bright and dark features.

  20. Micrometer- and Nanometer-Sized Polymeric Light-Emitting Diodes

    NASA Astrophysics Data System (ADS)

    Granstrom, Magnus; Berggren, Magnus; Inganas, Olle

    1995-03-01

    A method for the fabrication of micrometer- and submicrometer-sized polymeric light-emitting diodes is presented. Such diodes have a variety of applications. Light sources of dimensions around 100 nanometers are required for subwavelength, near-field optical microscopy. Another possible application is patterning on the micrometer and nanometer scale. The diodes have been made in the form of a sandwich structure, with the conductive polymer poly(3,4-ethylene-dioxythiophene) polymerized in the pores of commercially available microfiltration membranes defining the hole-injecting contacts, poly[3-(4-octylphenyl)-2,2'-bithiophene] as the light-emitting layer, and a thin film of calcium-aluminum as the electron injector.

  1. Climate Controls AM Fungal Distributions from Global to Local Scales

    NASA Astrophysics Data System (ADS)

    Kivlin, S. N.; Hawkes, C.; Muscarella, R.; Treseder, K. K.; Kazenel, M.; Lynn, J.; Rudgers, J.

    2016-12-01

    Arbuscular mycorrhizal (AM) fungi have key functions in terrestrial biogeochemical processes; thus, determining the relative importance of climate, edaphic factors, and plant community composition on their geographic distributions can improve predictions of their sensitivity to global change. Local adaptation by AM fungi to plant hosts, soil nutrients, and climate suggests that all of these factors may control fungal geographic distributions, but their relative importance is unknown. We created species distribution models for 142 AM fungal taxa at the global scale with data from GenBank. We compared climate variables (BioClim and soil moisture), edaphic variables (phosphorus, carbon, pH, and clay content), and plant variables using model selection on models with (1) all variables, (2) climatic variables only (including soil moisture) and (3) resource-related variables only (all other soil parameters and NPP) using the MaxEnt algorithm evaluated with ENMEval. We also evaluated whether drivers of AM fungal distributions were phylogenetically conserved. To test whether global correlates of AM fungal distributions were reflected at local scales, we then surveyed AM fungi in nine plant hosts along three elevation gradients in the Upper Gunnison Basin, Colorado, USA. At the global scale, the distributions of 55% of AM fungal taxa were affected by both climate and soil resources, whereas 16% were only affected by climate and 29% were only affected by soil resources. Even for AM fungi that were affected by both climate and resources, the effects of climatic variables nearly always outweighed those of resources. Soil moisture and isothermality were the main climatic and NPP and soil carbon the main resource related factors influencing AM fungal distributions. Distributions of closely related AM fungal taxa were similarly affected by climate, but not by resources. Local scale surveys of AM fungi across elevations confirmed that climate was a key driver of AM fungal

  2. Soil moisture at local scale: Measurements and simulations

    NASA Astrophysics Data System (ADS)

    Romano, Nunzio

    2014-08-01

    Soil moisture refers to the water present in the uppermost part of a field soil and is a state variable controlling a wide array of ecological, hydrological, geotechnical, and meteorological processes. The literature on soil moisture is very extensive and is developing so rapidly that it might be considered ambitious to seek to present the state of the art concerning research into this key variable. Even when covering investigations about only one aspect of the problem, there is a risk of some inevitable omission. A specific feature of the present essay, which may make this overview if not comprehensive at least of particular interest, is that the reader is guided through the various traditional and more up-to-date methods by the central thread of techniques developed to measure soil moisture interwoven with applications of modeling tools that exploit the observed datasets. This paper restricts its analysis to the evolution of soil moisture at the local (spatial) scale. Though a somewhat loosely defined term, it is linked here to a characteristic length of the soil volume investigated by the soil moisture sensing probe. After presenting the most common concepts and definitions about the amount of water stored in a certain volume of soil close to the land surface, this paper proceeds to review ground-based methods for monitoring soil moisture and evaluates modeling tools for the analysis of the gathered information in various applications. Concluding remarks address questions of monitoring and modeling of soil moisture at scales larger than the local scale with the related issue of data aggregation. An extensive, but not exhaustive, list of references is provided, enabling the reader to gain further insights into this subject.

  3. Large-scale quantization from local correlations in space plasmas

    NASA Astrophysics Data System (ADS)

    Livadiotis, George; McComas, David J.

    2014-05-01

    This study examines the large-scale quantization that can characterize the phase space of certain physical systems. Plasmas are such systems where large-scale quantization, ħ*, is caused by Debye shielding that structures correlations between particles. The value of ħ* is constant—some 12 orders of magnitude larger than the Planck constant—across a wide range of space plasmas, from the solar wind in the inner heliosphere to the distant plasma in the inner heliosheath and the local interstellar medium. This paper develops the foundation and advances the understanding of the concept of plasma quantization; in particular, we (i) show the analogy of plasma to Planck quantization, (ii) show the key points of plasma quantization, (iii) construct some basic quantum mechanical concepts for the large-scale plasma quantization, (iv) investigate the correlation between plasma parameters that implies plasma quantization, when it is approximated by a relation between the magnetosonic energy and the plasma frequency, (v) analyze typical space plasmas throughout the heliosphere and show the constancy of plasma quantization over many orders of magnitude in plasma parameters, (vi) analyze Advanced Composition Explorer (ACE) solar wind measurements to develop another measurement of the value of ħ*, and (vii) apply plasma quantization to derive unknown plasma parameters when some key observable is missing.

  4. Local dynamic subgrid-scale models in channel flow

    NASA Technical Reports Server (NTRS)

    Cabot, William H.

    1994-01-01

    The dynamic subgrid-scale (SGS) model has given good results in the large-eddy simulation (LES) of homogeneous isotropic or shear flow, and in the LES of channel flow, using averaging in two or three homogeneous directions (the DA model). In order to simulate flows in general, complex geometries (with few or no homogeneous directions), the dynamic SGS model needs to be applied at a local level in a numerically stable way. Channel flow, which is inhomogeneous and wall-bounded flow in only one direction, provides a good initial test for local SGS models. Tests of the dynamic localization model were performed previously in channel flow using a pseudospectral code and good results were obtained. Numerical instability due to persistently negative eddy viscosity was avoided by either constraining the eddy viscosity to be positive or by limiting the time that eddy viscosities could remain negative by co-evolving the SGS kinetic energy (the DLk model). The DLk model, however, was too expensive to run in the pseudospectral code due to a large near-wall term in the auxiliary SGS kinetic energy (k) equation. One objective was then to implement the DLk model in a second-order central finite difference channel code, in which the auxiliary k equation could be integrated implicitly in time at great reduction in cost, and to assess its performance in comparison with the plane-averaged dynamic model or with no model at all, and with direct numerical simulation (DNS) and/or experimental data. Other local dynamic SGS models have been proposed recently, e.g., constrained dynamic models with random backscatter, and with eddy viscosity terms that are averaged in time over material path lines rather than in space. Another objective was to incorporate and test these models in channel flow.

  5. Novel Sample Preparation Technique To Improve Spectromicroscopic Analyses of Micrometer-Sized Particles.

    PubMed

    Höschen, Carmen; Höschen, Till; Mueller, Carsten W; Lugmeier, Johann; Elgeti, Stefan; Rennert, Thilo; Kögel-Knabner, Ingrid

    2015-08-18

    Microscale processes occurring at biogeochemical interfaces in soils and sediments have fundamental impacts on phenomena at larger scales. To obtain the organo-mineral associations necessary for the study of biogeochemical interfaces, bulk samples are usually fractionated into microaggregates or micrometer-sized single particles. Such fine-grained mineral particles are often prepared for nanoscale secondary ion mass spectroscopy (NanoSIMS) investigations by depositing them on a carrier. This introduces topographic differences, which can strongly affect local sputtering efficiencies. Embedding in resin causes undesired C impurities. We present a novel method for preparing polished cross-sections of micrometer-sized primary soil particles that overcomes the problems of topography and C contamination. The particles are coated with a marker layer, embedded, and well-polished. The interpretation of NanoSIMS data is assisted by energy-dispersive X-ray spectroscopy on cross-sections prepared by a focused ion beam. In the cross-sections, organic assemblages on the primary soil particles become visible. This novel method significantly improves the quality of NanoSIMS measurements on grainy mineral samples, enabling better characterization of soil biogeochemical interfaces. In addition, this sample preparation technique may also improve results from other (spectro-) microscopic techniques.

  6. Thermal Behavior of Unusual Local-Scale Features on Vesta

    NASA Technical Reports Server (NTRS)

    Tosi, Federico; Capria, Maria Teresa; DeSanctis, Maria Cristina; Palomba, Ernesto; Capaccioni, Fabrizio; Combe, Jean-Philippe; Titus, Timothy; Mittlefehldt, David W.; Li, Jian-Yang; Russell, Christopher T.

    2012-01-01

    On Vesta, the thermal behavior of areas of unusual albedo seen at the local scale can be related to physical properties that can provide information about the origin of those materials. Dawn's Visible and Infrared Mapping Spectrometer (VIR) hyperspectral cubes are used to retrieve surface temperatures and emissivities, with high accuracy as long as temperatures are greater than 180 K. Data acquired in the Survey phase (23 July through 29 August 2011) show several unusual surface features: 1) high-albedo (bright) and low-albedo (dark) material deposits, 2) spectrally distinct ejecta and pitted materials, 3) regions suggesting finer-grained materials. Some of the unusual dark and bright features were re-observed by VIR in the subsequent High-Altitude Mapping Orbit (HAMO) and Low-Altitude Mapping Orbit (LAMO) phases at increased pixel resolution. In particular, bright and dark surface materials on Vesta, and pitted materials, are currently being investigated by the Dawn team. In this work we present temperature maps and emissivities of several local-scale features that were observed by Dawn under different illumination conditions and different local solar times. To calculate surface temperatures, we applied a Bayesian approach to nonlinear inversion based on the Kirchhoff law and the Planck function, and whose results were compared with those provided by the application of alternative methods. Data from the IR channel of VIR show that bright regions generally correspond to regions with lower thermal emission, i.e. lower temperature, while dark regions correspond to areas with higher thermal emission, i.e. higher temperature. This behavior confirms that many of the dark appearances in the VIS mainly reflect albedo variations, and not, for example, shadowing. During maximum daily insolation, dark features in the equatorial region may rise to temperatures greater than 270 K, while brightest features stop at roughly 258 K for similar local solar times. However, pitted

  7. Thermal Behavior of Unusual Local-Scale Features on Vesta

    NASA Technical Reports Server (NTRS)

    Tosi, Federico; Capria, Maria Teresa; DeSanctis, Maria Cristina; Palomba, Ernesto; Capaccioni, Fabrizio; Combe, Jean-Philippe; Titus, Timothy; Mittlefehldt, David W.; Li, Jian-Yang; Russell, Christopher T.

    2012-01-01

    On Vesta, the thermal behavior of areas of unusual albedo seen at the local scale can be related to physical properties that can provide information about the origin of those materials. Dawn's Visible and Infrared Mapping Spectrometer (VIR) hyperspectral cubes are used to retrieve surface temperatures and emissivities, with high accuracy as long as temperatures are greater than 180 K. Data acquired in the Survey phase (23 July through 29 August 2011) show several unusual surface features: 1) high-albedo (bright) and low-albedo (dark) material deposits, 2) spectrally distinct ejecta and pitted materials, 3) regions suggesting finer-grained materials. Some of the unusual dark and bright features were re-observed by VIR in the subsequent High-Altitude Mapping Orbit (HAMO) and Low-Altitude Mapping Orbit (LAMO) phases at increased pixel resolution. In particular, bright and dark surface materials on Vesta, and pitted materials, are currently being investigated by the Dawn team. In this work we present temperature maps and emissivities of several local-scale features that were observed by Dawn under different illumination conditions and different local solar times. To calculate surface temperatures, we applied a Bayesian approach to nonlinear inversion based on the Kirchhoff law and the Planck function, and whose results were compared with those provided by the application of alternative methods. Data from the IR channel of VIR show that bright regions generally correspond to regions with lower thermal emission, i.e. lower temperature, while dark regions correspond to areas with higher thermal emission, i.e. higher temperature. This behavior confirms that many of the dark appearances in the VIS mainly reflect albedo variations, and not, for example, shadowing. During maximum daily insolation, dark features in the equatorial region may rise to temperatures greater than 270 K, while brightest features stop at roughly 258 K for similar local solar times. However, pitted

  8. Associations between urbanicity and malaria at local scales in Uganda.

    PubMed

    Kigozi, Simon P; Pindolia, Deepa K; Smith, David L; Arinaitwe, Emmanuel; Katureebe, Agaba; Kilama, Maxwell; Nankabirwa, Joaniter; Lindsay, Steve W; Staedke, Sarah G; Dorsey, Grant; Kamya, Moses R; Tatem, Andrew J

    2015-09-29

    Sub-Saharan Africa is expected to show the greatest rates of urbanization over the next 50 years. Urbanization has shown a substantial impact in reducing malaria transmission due to multiple factors, including unfavourable habitats for Anopheles mosquitoes, generally healthier human populations, better access to healthcare, and higher housing standards. Statistical relationships have been explored at global and local scales, but generally only examining the effects of urbanization on single malaria metrics. In this study, associations between multiple measures of urbanization and a variety of malaria metrics were estimated at local scales. Cohorts of children and adults from 100 households across each of three contrasting sub-counties of Uganda (Walukuba, Nagongera and Kihihi) were followed for 24 months. Measures of urbanicity included density of surrounding households, vegetation index, satellite-derived night-time lights, land cover, and a composite urbanicity score. Malaria metrics included the household density of mosquitoes (number of female Anopheles mosquitoes captured), parasite prevalence and malaria incidence. Associations between measures of urbanicity and malaria metrics were made using negative binomial and logistic regression models. One site (Walukuba) had significantly higher urbanicity measures compared to the two rural sites. In Walukuba, all individual measures of higher urbanicity were significantly associated with a lower household density of mosquitoes. The higher composite urbanicity score in Walukuba was also associated with a lower household density of mosquitoes (incidence rate ratio = 0.28, 95 % CI 0.17-0.48, p < 0.001) and a lower parasite prevalence (odds ratio, OR = 0.44, CI 0.20-0.97, p = 0.04). In one rural site (Kihihi), only a higher density of surrounding households was associated with a lower parasite prevalence (OR = 0.15, CI 0.07-0.34, p < 0.001). And, in only one rural site (Nagongera) was living where NDVI

  9. Scaling of membrane-type locally resonant acoustic metamaterial arrays.

    PubMed

    Naify, Christina J; Chang, Chia-Ming; McKnight, Geoffrey; Nutt, Steven R

    2012-10-01

    Metamaterials have emerged as promising solutions for manipulation of sound waves in a variety of applications. Locally resonant acoustic materials (LRAM) decrease sound transmission by 500% over acoustic mass law predictions at peak transmission loss (TL) frequencies with minimal added mass, making them appealing for weight-critical applications such as aerospace structures. In this study, potential issues associated with scale-up of the structure are addressed. TL of single-celled and multi-celled LRAM was measured using an impedance tube setup with systematic variation in geometric parameters to understand the effects of each parameter on acoustic response. Finite element analysis was performed to predict TL as a function of frequency for structures with varying complexity, including stacked structures and multi-celled arrays. Dynamic response of the array structures under discrete frequency excitation was investigated using laser vibrometry to verify negative dynamic mass behavior.

  10. Calibration of the local magnitude scale ( M L ) for Peru

    NASA Astrophysics Data System (ADS)

    Condori, Cristobal; Tavera, Hernando; Marotta, Giuliano Sant'Anna; Rocha, Marcelo Peres; França, George Sand

    2017-07-01

    We propose a local magnitude scale ( M L ) for Peru, based on the original Richter definition, using 210 seismic events between 2011 and 2014, recorded by 35 broadband stations of the National Seismic Network operated by the Geophysical Institute of Peru. In the solution model, we considered 1057 traces of maximum amplitude records on the vertical channel from simulated Wood-Anderson seismograms of shallow events (depths between 0 and 60 km) and hypocentral distances less than 600 km. The attenuation factor has been evaluated in terms of geometrical spreading and anelastic attenuation coefficients. The magnitude M L was defined as M L = L o g 10 A W A +1.5855 L o g 10( R/100)+0.0008( R-100)+3± S, where, A W A is the displacement amplitude in millimeters (Wood-Anderson), R is the hypocentral distance (km), and S is the station correction. The results obtained for M L have good correlation with the m b , M s and M w values reported the ISC and NEIC. The anelastic attenuation curve obtained has a similar behavior to that other highly seismic regions. Station corrections were determined for all stations during the regression analysis resulting in values ranging between -0.97 and +0.73, suggesting a strong influence of local site effects on amplitude.

  11. Calibration of the local magnitude scale (M L ) for Peru

    NASA Astrophysics Data System (ADS)

    Condori, Cristobal; Tavera, Hernando; Marotta, Giuliano Sant'Anna; Rocha, Marcelo Peres; França, George Sand

    2017-02-01

    We propose a local magnitude scale (M L ) for Peru, based on the original Richter definition, using 210 seismic events between 2011 and 2014, recorded by 35 broadband stations of the National Seismic Network operated by the Geophysical Institute of Peru. In the solution model, we considered 1057 traces of maximum amplitude records on the vertical channel from simulated Wood-Anderson seismograms of shallow events (depths between 0 and 60 km) and hypocentral distances less than 600 km. The attenuation factor has been evaluated in terms of geometrical spreading and anelastic attenuation coefficients. The magnitude M L was defined as M L = L o g 10 A W A +1.5855L o g 10(R/100)+0.0008(R-100)+3±S, where, A W A is the displacement amplitude in millimeters (Wood-Anderson), R is the hypocentral distance (km), and S is the station correction. The results obtained for M L have good correlation with the m b , M s and M w values reported the ISC and NEIC. The anelastic attenuation curve obtained has a similar behavior to that other highly seismic regions. Station corrections were determined for all stations during the regression analysis resulting in values ranging between -0.97 and +0.73, suggesting a strong influence of local site effects on amplitude.

  12. Spatial and temporal variation of atmospheric particle in local scale

    NASA Astrophysics Data System (ADS)

    Mukai, S.; Nakata, M.; Sano, I.; Nakano, T.; Okuhara, T.

    2011-12-01

    This work intends to demonstrate the spatial and temporal variation of atmospheric particles around AERONET/Osaka site. Osaka is the second big city in Japan and a typical Asian urban area. It is well known that the aerosol distribution in Asia is complicated due to the increasing emissions of anthropogenic aerosols in association with economic growth and in addition behavior of natural dusts significantly varies with the seasons. Therefore local spatially and temporally resolved measurements of atmospheric particles in Asian urban city are meaningful. The sampling of PM2.5, PM10 and OBC have been undertaken using an Kimoto/SPM sampler at the AERONET/Osaka site since 2004. It is noted that a portable multi-spectral sun-photometer (Solar-Light Company Microtops-II) has been employed since 2010. It is found from the simultaneous measurements of AOT (aerosol optical thickness) at AERONET/Osaka site and several locations in the neighborhood and PM sampling that the local scale spatial and temporal factors influence the characterization of atmospheric particles for sure and vice versa.

  13. Local clustering in scale-free networks with hidden variables

    NASA Astrophysics Data System (ADS)

    van der Hofstad, Remco; Janssen, A. J. E. M.; van Leeuwaarden, Johan S. H.; Stegehuis, Clara

    2017-02-01

    We investigate the presence of triangles in a class of correlated random graphs in which hidden variables determine the pairwise connections between vertices. The class rules out self-loops and multiple edges. We focus on the regime where the hidden variables follow a power law with exponent τ ∈(2 ,3 ) , so that the degrees have infinite variance. The natural cutoff hc characterizes the largest degrees in the hidden variable models, and a structural cutoff hs introduces negative degree correlations (disassortative mixing) due to the infinite-variance degrees. We show that local clustering decreases with the hidden variable (or degree). We also determine how the average clustering coefficient C scales with the network size N , as a function of hs and hc. For scale-free networks with exponent 2 <τ <3 and the default choices hs˜N1 /2 and hc˜N1 /(τ -1 ) this gives C ˜N2 -τlnN for the universality class at hand. We characterize the extremely slow decay of C when τ ≈2 and show that for τ =2.1 , say, clustering starts to vanish only for networks as large as N =109 .

  14. Local versus basin-scale limitation of marine nitrogen fixation

    PubMed Central

    Weber, Thomas; Deutsch, Curtis

    2014-01-01

    Nitrogen (N) fixation by diazotrophic plankton is the primary source of this crucial nutrient to the ocean, but the factors limiting its rate and distribution are controversial. According to one view, the ecological niche of diazotrophs is primarily controlled by the ocean through internally generated N deficits that suppress the growth of their competitors. A second view posits an overriding limit from the atmosphere, which restricts diazotrophs to regions where dust deposition satisfies their high iron (Fe) requirement, thus separating N sources from sinks at a global scale. Here we use multiple geochemical signatures of N2 fixation to show that the Fe limitation of diazotrophs is strong enough to modulate the regional distribution of N2 fixation within ocean basins—particularly the Fe-poor Pacific—but not strong enough to influence its partition between basins, which is instead governed by rates of N loss. This scale-dependent limitation of N2 fixation reconciles local observations of Fe stress in diazotroph communities with an inferred spatial coupling of N sources and sinks. Within this regime of intermediate Fe control, the oceanic N reservoir would respond only weakly to enhanced dust fluxes during glacial climates, but strongly to the reduced fluxes hypothesized under anthropogenic climate warming. PMID:24889607

  15. Local versus basin-scale limitation of marine nitrogen fixation.

    PubMed

    Weber, Thomas; Deutsch, Curtis

    2014-06-17

    Nitrogen (N) fixation by diazotrophic plankton is the primary source of this crucial nutrient to the ocean, but the factors limiting its rate and distribution are controversial. According to one view, the ecological niche of diazotrophs is primarily controlled by the ocean through internally generated N deficits that suppress the growth of their competitors. A second view posits an overriding limit from the atmosphere, which restricts diazotrophs to regions where dust deposition satisfies their high iron (Fe) requirement, thus separating N sources from sinks at a global scale. Here we use multiple geochemical signatures of N2 fixation to show that the Fe limitation of diazotrophs is strong enough to modulate the regional distribution of N2 fixation within ocean basins--particularly the Fe-poor Pacific--but not strong enough to influence its partition between basins, which is instead governed by rates of N loss. This scale-dependent limitation of N2 fixation reconciles local observations of Fe stress in diazotroph communities with an inferred spatial coupling of N sources and sinks. Within this regime of intermediate Fe control, the oceanic N reservoir would respond only weakly to enhanced dust fluxes during glacial climates, but strongly to the reduced fluxes hypothesized under anthropogenic climate warming.

  16. Local field potentials reflect multiple spatial scales in V4

    PubMed Central

    Mineault, Patrick J.; Zanos, Theodoros P.; Pack, Christopher C.

    2013-01-01

    Local field potentials (LFP) reflect the properties of neuronal circuits or columns recorded in a volume around a microelectrode (Buzsáki et al., 2012). The extent of this integration volume has been a subject of some debate, with estimates ranging from a few hundred microns (Katzner et al., 2009; Xing et al., 2009) to several millimeters (Kreiman et al., 2006). We estimated receptive fields (RFs) of multi-unit activity (MUA) and LFPs at an intermediate level of visual processing, in area V4 of two macaques. The spatial structure of LFP receptive fields varied greatly as a function of time lag following stimulus onset, with the retinotopy of LFPs matching that of MUAs at a restricted set of time lags. A model-based analysis of the LFPs allowed us to recover two distinct stimulus-triggered components: an MUA-like retinotopic component that originated in a small volume around the microelectrodes (~350 μm), and a second component that was shared across the entire V4 region; this second component had tuning properties unrelated to those of the MUAs. Our results suggest that the LFP reflects neural activity across multiple spatial scales, which both complicates its interpretation and offers new opportunities for investigating the large-scale structure of network processing. PMID:23533106

  17. Reading a Micrometer. Fordson Bilingual Demonstration Project.

    ERIC Educational Resources Information Center

    Field, Susan; And Others

    This vocational instructional module on reading a micrometer is one of eight such modules designed to assist recently arrived Arab students, limited in English proficiency (LEP), in critical instructional areas in a comprehensive high school. Goal stated for this module is for the student to demonstrate ability to measure using a one-inch…

  18. Local spectral properties of Luttinger liquids: scaling versus nonuniversal energy scales

    NASA Astrophysics Data System (ADS)

    Schuricht, D.; Andergassen, S.; Meden, V.

    2013-01-01

    Motivated by recent scanning tunneling and photoemission spectroscopy measurements on self-organized gold chains on a germanium surface, we reinvestigate the local single-particle spectral properties of Luttinger liquids. In the first part we use the bosonization approach to exactly compute the local spectral function of a simplified field theoretical low-energy model and take a closer look at scaling properties as a function of the ratio of energy and temperature. Translational-invariant Luttinger liquids as well as those with an open boundary (cut chain geometry) are considered. We explicitly show that the scaling functions of both set-ups have the same analytical form. The scaling behavior suggests a variety of consistency checks which can be performed on measured data to experimentally verify Luttinger liquid behavior. In the second part we approximately compute the local spectral function of a microscopic lattice model—the extended Hubbard model—close to an open boundary using the functional renormalization group. We show that it follows the field theoretical prediction in the low-energy regime as a function of energy and temperature, and point out the importance of nonuniversal energy scales inherent to any microscopic model. The spatial dependence of this spectral function is characterized by oscillatory behavior and an envelope function which follows a power law in accordance with the field theoretical continuum model. Interestingly, for the lattice model we find a phase shift which is proportional to the two-particle interaction and not accounted for in the standard bosonization approach to Luttinger liquids with an open boundary. We briefly comment on the effects of several one-dimensional branches cutting the Fermi energy and Rashba spin-orbit interaction.

  19. Near-infrared continuum and 3.3 micrometer(s) polycyclic aromatic hydrocarbon imaging of the starburst ring in the type 1 Seyfert galaxy NGC 7469

    NASA Technical Reports Server (NTRS)

    Mazzarella, J. M.; Voit, G. M.; Soifer, B. T.; Matthews, K.; Graham, J. R.; Armus, L.; Shupe, D.

    1994-01-01

    High resolution near-infrared images of the type 1 Seyfert galaxy NGC 7469 have been obtained to probe its dusty nuclear environment. Direct J, H, and K images are relatively featureless, but residual images created by subtracting a smooth model based on best-fitting elliptical isophotes reveal a tight inner spiral whose high surface-brightness portions correspond to a previously detected 3 sec (1 kpc) diameter ring of radio continuum emission. The inner infrared spiral arms extended approximately equal to 4 sec NW and SE from the nucleus, and the NW arm joins up with large-scale spiral structure visible in the R band. The residual images also show a bar-like structure aligned with the brightest infrared/radio hotspots at PA approximately equal to 50 deg. Three infrared hotspots are detected which align remarkably well with 6 cm radio continuum sources. The near-infrared ring and the hotspots are visible in the residual images, and in a high-resolution direct K-band image restored to an effective resolution of 0.65 sec (FWHM) using the Richardson-Lucy algorithm. The infrared hotspots have luminosities of nuL(sub nu) (2.2 micrometer(s)) approximately equal to 10(exp 8) solar luminosity (M(sub k) approximately equal to -16 mag), suggesting they are either giant H II regions or individual supernovae. The two brightest regions may be associated with enhanced star formation triggered by orbit crowding of gas where spiral arms emerge from an inner bar. Narrowband (delta lambda/lambda approximately 1.5%) imaging in the 3.28 micrometer(s) dust emission feature and surrounding continuum confirms the 3 sec diameter 3.28 micrometer(s) emission region detected previously using multiaperture photometry. The extended polycyclic aromatic hydrocarbon (PAH) emission is slightly elongated and aligned with published 1O III1 line emission and 12.5 micrometer(s) continuum emission, apparently tracing the starburst. The presence of approximately equal to 25% of the total 3.28 micrometer(s

  20. Near-infrared continuum and 3.3 micrometer(s) polycyclic aromatic hydrocarbon imaging of the starburst ring in the type 1 Seyfert galaxy NGC 7469

    NASA Technical Reports Server (NTRS)

    Mazzarella, J. M.; Voit, G. M.; Soifer, B. T.; Matthews, K.; Graham, J. R.; Armus, L.; Shupe, D.

    1994-01-01

    High resolution near-infrared images of the type 1 Seyfert galaxy NGC 7469 have been obtained to probe its dusty nuclear environment. Direct J, H, and K images are relatively featureless, but residual images created by subtracting a smooth model based on best-fitting elliptical isophotes reveal a tight inner spiral whose high surface-brightness portions correspond to a previously detected 3 sec (1 kpc) diameter ring of radio continuum emission. The inner infrared spiral arms extended approximately equal to 4 sec NW and SE from the nucleus, and the NW arm joins up with large-scale spiral structure visible in the R band. The residual images also show a bar-like structure aligned with the brightest infrared/radio hotspots at PA approximately equal to 50 deg. Three infrared hotspots are detected which align remarkably well with 6 cm radio continuum sources. The near-infrared ring and the hotspots are visible in the residual images, and in a high-resolution direct K-band image restored to an effective resolution of 0.65 sec (FWHM) using the Richardson-Lucy algorithm. The infrared hotspots have luminosities of nuL(sub nu) (2.2 micrometer(s)) approximately equal to 10(exp 8) solar luminosity (M(sub k) approximately equal to -16 mag), suggesting they are either giant H II regions or individual supernovae. The two brightest regions may be associated with enhanced star formation triggered by orbit crowding of gas where spiral arms emerge from an inner bar. Narrowband (delta lambda/lambda approximately 1.5%) imaging in the 3.28 micrometer(s) dust emission feature and surrounding continuum confirms the 3 sec diameter 3.28 micrometer(s) emission region detected previously using multiaperture photometry. The extended polycyclic aromatic hydrocarbon (PAH) emission is slightly elongated and aligned with published 1O III1 line emission and 12.5 micrometer(s) continuum emission, apparently tracing the starburst. The presence of approximately equal to 25% of the total 3.28 micrometer(s

  1. The Cold Land Process Experiment's (CLPX) Local Scale Observation Site

    NASA Astrophysics Data System (ADS)

    Hardy, J. P.; Cline, D.; Elder, K.; Davis, R. E.; Pomeroy, J.; Koh, Y.; Armstrong, R.; Koike, T.; McDonald, K.

    2002-12-01

    The Local Scale Observation Site (LSOS) is the smallest study site of the Cold Land Processes Experiment (CLPX) and is located within the Fraser Meso-cell Study Area (MSA), near the Fraser Experimental Forest Headquarters Facility, in Fraser, Colorado USA. The 100- x 100-m site consists of a small, open field, a managed dense canopy, and an open, mixed age canopy. Unlike the other components of the experiment, which focus on spatial distributions at relatively brief "snapshots" in time, measurements at the local-scale site focused on the temporal domain. Measurements made at the LSOS were designed to produce a comprehensive assessment of the snow, soil, and vegetation characteristics viewed by the ground-based remote sensing instruments. The objective of ground-based microwave remote sensing was to collect time series of active and passive microwave spectral signatures over snow, soil, and forest, coincident with intensive physical characterization of these features. Ground-based remote sensing instruments included Frequency Modulated Continuous Wave (FMCW) radars operating over multiple microwave bandwidths, the Ground-Based Microwave Radiometer (GBMR-7) (Advanced Microwave Scanning Radiometer (AMSR) Simulator; channels 18.7, 23.8, 36.5, and 89.0-GHz), and in 2003, an L/C/X/Ku-band scatterometer radar system. Snow and soil measurements included standard snow physical properties, snow surface roughness, snow depth transects, and soil moisture. The stem and canopy temperature, and xylem flux of several trees within the area, were monitored continuously. Two micrometeorological towers, one located in the open snow area and the other in the forested area, monitored ambient conditions and provided forcing data sets for 1-D snow/soil models. Arrays of radiometers (0.3-3 μm) and a scanning thermal radiometer (8-12 μm) characterized the variability of radiative receipt in the forests. These measurements, together with the ground-based remote sensing, provide the

  2. Nuclear β-catenin localization supports homology of feathers, avian scutate scales, and alligator scales in early development.

    PubMed

    Musser, Jacob M; Wagner, Günter P; Prum, Richard O

    2015-01-01

    Feathers are an evolutionary novelty found in all extant birds. Despite recent progress investigating feather development and a revolution in dinosaur paleontology, the relationship of feathers to other amniote skin appendages, particularly reptile scales, remains unclear. Disagreement arises primarily from the observation that feathers and avian scutate scales exhibit an anatomical placode-defined as an epidermal thickening-in early development, whereas alligator and other avian scales do not. To investigate the homology of feathers and archosaur scales we examined patterns of nuclear β-catenin localization during early development of feathers and different bird and alligator scales. In birds, nuclear β-catenin is first localized to the feather placode, and then exhibits a dynamic pattern of localization in both epidermis and dermis of the feather bud. We found that asymmetric avian scutate scales and alligator scales share similar patterns of nuclear β-catenin localization with feathers. This supports the hypothesis that feathers, scutate scales, and alligator scales are homologous during early developmental stages, and are derived from early developmental stages of an asymmetric scale present in the archosaur ancestor. Furthermore, given that the earliest stage of β-catenin localization in feathers and archosaur scales is also found in placodes of several mammalian skin appendages, including hair and mammary glands, we hypothesize that a common skin appendage placode originated in the common ancestor of all amniotes. We suggest a skin placode should not be defined by anatomical features, but as a local, organized molecular signaling center from which an epidermal appendage develops.

  3. ISM and dynamical scaling relations in the local Universe

    NASA Astrophysics Data System (ADS)

    Cortese, L.

    2016-06-01

    In the last decade we have seen a tremendous progress in our understanding of the life cycle of galaxies. Particularly powerful has been the synergy between representative surveys of cold gas, dust and metals and improved theoretical models able to follow the evolution of the different phases of the ISM in a self-consistent way. At the same time, the advent of optical integral field spectroscopic surveys is finally allowing us to quantify how the kinematical properties of gas and stars vary across the Hubble sequence. In this talk, I will review recent observational work aimed at providing a local benchmark for the study of the star formation cycle in galaxies and dynamical scaling relations in galaxies. By combining observations obtained as part the Herschel Reference Survey, the GALEX Arecibo SDSS survey, the ALFALFA survey and the SAMI Galaxy Survey, I will discuss what nearby galaxies can teach us about the interplay between kinematics, star formation, chemical enrichment and environmental effects in our neighbourhoods.

  4. Contributions to urban heat island on the local neighborhood scale

    NASA Astrophysics Data System (ADS)

    Hertel, Daniel; Schlink, Uwe

    2017-04-01

    Already today around half of the global population is living in urban regions and recent studies expect a further increase until mid-21st century. Therefore, especially in the context of climate change, an increasing amount of urban inhabitants are affected by urban climate and air quality. One special characteristic of urban climate is the urban heat island (UHI) effect, where urbanized regions are warmer than the rural surroundings. With respect to climate change and the growing urbanization it is obvious that the UHI effect will tend to be intensified. To keep our cities worth living, it is necessary to think about adaptation and mitigation strategies which refer to both, climate protection as well as utilization of chances resulting from climate changes. One step to a more precisely adaptation, particularly on the neighborhood scale, is an improved understanding of the magnitude of bio geophysical processes (e.g.: radiation balance, convection efficiency, evapotranspiration, storage heat, anthropogenic heat etc.), which contribute to the urban warming. Considering that UHI can be expressed as temperature difference ΔT between urban and rural areas, we can interpret these processes as how they would change temperature, because of energy redistribution, from a rural area to an urbanized region. Up to now on the local scale there is a knowledge gap about these processes. The mentioned processes are parts of a surface energy balance (based on the work of Zhao et al., 2014). That means they refer to the surface UHI effect and not to the canopy layer UHI effect. Assuming that the urban region is a volume with the top at the height of the canopy layer, we can approximately identify the surface UHI effect as the canopy layer UHI effect since the information comes from both the surface and the atmosphere inside. This assumption is not valid for Zhao's approach because they analyzed whole cities and could neglect such processes within the volume. This contribution

  5. Wideband 1.064 micrometer detector evaluation

    NASA Technical Reports Server (NTRS)

    Green, S. I.

    1975-01-01

    The performance of several candidate detectors for use as communications detectors in a 400 Mbps 1.064 micrometers laser communication system was evaluated. The results of communication system Bit Error Rate (BER) testing for the best detector of each type are summarized. Complete testing data of each type detector is presented. The 400 Mbps 1.064 micrometers communication system receiver test bed is described. The best communication system results for each detector type are included. Performance comparisons are made at 0.000001 BER, the specification level chosen for satellite laser communication links. The data is presented in two groups. The first indicates the best performance levels that can be expected on normal space laser communication system operation. The second cites the best performance levels which can be achieved by focusing the signal to diffraction limited spots on the photosensitive area.

  6. Sixteen micrometer Infrared Hot Electron Transistor

    NASA Technical Reports Server (NTRS)

    Gunapala, S. D.; Liu, J. K.; Park, J. S.; Lin, T. L.

    1994-01-01

    ABSTRACT. We have demonstrated a bound to continuum state GaAs/Al(x)Ga(1-x)As infrared hot electron transistor which has a peak response at lambda(sub p) = 16.3 micrometers. An excellent photo-current transfer ratio of alpha(sub p) = 0.12 and very low dark current transfer ratio of alpha(sub d) = 7.2 x 10(exp 5) is achieved at a temperature of T = 60 K.

  7. 16 Micrometer Infrared Hot Electron Transistor

    NASA Technical Reports Server (NTRS)

    Gunapala, S. D.; Liu, J. K.; Park, J. S.; Lin, T. L.

    1993-01-01

    We have demonstrated a bound to continuum state GaAs/Al_xGa_(1-x)As infrared hot electron transistor which has a peak response at theta_p = 16.3 micrometers. An excellent photo-current transfer ratio of alpha_p = 0.12 and very low dark current transfer ratio of alpha_d = 7.2x10^(-5) is achieved at a temperature of T = 60 K.

  8. Estimation of local scale dispersion from local breakthrough curves during a tracer test in a heterogeneous aquifer: the Lagrangian approach.

    PubMed

    Vanderborght, Jan; Vereecken, Harry

    2002-01-01

    The local scale dispersion tensor, Dd, is a controlling parameter for the dilution of concentrations in a solute plume that is displaced by groundwater flow in a heterogeneous aquifer. In this paper, we estimate the local scale dispersion from time series or breakthrough curves, BTCs, of Br concentrations that were measured at several points in a fluvial aquifer during a natural gradient tracer test at Krauthausen. Locally measured BTCs were characterized by equivalent convection dispersion parameters: equivalent velocity, v(eq)(x) and expected equivalent dispersivity, [lambda(eq)(x)]. A Lagrangian framework was used to approximately predict these equivalent parameters in terms of the spatial covariance of log(e) transformed conductivity and the local scale dispersion coefficient. The approximate Lagrangian theory illustrates that [lambda(eq)(x)] increases with increasing travel distance and is much larger than the local scale dispersivity, lambda(d). A sensitivity analysis indicates that [lambda(eq)(x)] is predominantly determined by the transverse component of the local scale dispersion and by the correlation scale of the hydraulic conductivity in the transverse to flow direction whereas it is relatively insensitive to the longitudinal component of the local scale dispersion. By comparing predicted [lambda(eq)(x)] for a range of Dd values with [lambda(eq)(x)] obtained from locally measured BTCs, the transverse component of Dd, DdT, was estimated. The estimated transverse local scale dispersivity, lambda(dT) = DdT/U1 (U1 = mean advection velocity) is in the order of 10(1)-10(2) mm, which is relatively large but realistic for the fluvial gravel sediments at Krauthausen.

  9. Area volume properties of fluid interfaces in turbulence: scale-local self-similarity and cumulative scale dependence

    NASA Astrophysics Data System (ADS)

    Catrakis, Haris J.; Aguirre, Roberto C.; Ruiz-Plancarte, Jesus

    2002-07-01

    Area volume properties of fluid interfaces are investigated to quantify the scale-local and cumulative structure. An area volume density g3([lambda]) and ratio [Omega]3([lambda]) are introduced to examine the interfacial behaviour as a function of scale [lambda] or across a range of scales, respectively. These measures are demonstrated on mixed-fluid interfaces from whole-field [similar]10003 three-dimensional space time concentration measurements in turbulent jets above the mixing transition, at Re [similar] 20000 and Sc [similar] 2000, recorded by laser-induced-fluorescence and digital-imaging techniques, with Taylor's hypothesis applied. The cumulative structure is scale dependent in [Omega]3([lambda]), with a dimension D3([lambda]) that increases with increasing scale. In contrast, the scale-local structure exhibits self-similarity in g3([lambda]) with an exponent [alpha]g [approximate]1.3 for these interfaces. The scale dependence in the cumulative structure arises from the large scales, while the self-similarity corresponds to the small-scale area volume contributions. The small scales exhibit the largest area volume density and provide the dominant contributions to the total area volume ratio, which corresponds to [similar]10 times the area of a purely large-scale interface for the present flow conditions. The self-similarity in the scale-local structure at small scales provides the key ingredient to extrapolate the area volume behaviour to higher Reynolds numbers.

  10. Testing general relativity: from local to cosmological scales.

    PubMed

    Uzan, Jean-Philippe

    2011-12-28

    I summarize various tests of general relativity on astrophysical scales, based on the large-scale structure of the universe but also on other systems, in particular the constants of physics. I emphasize the importance of hypotheses on the geometric structures of our universe while performing such tests and discuss their complementarity as well as their possible extensions.

  11. Low-cost system for micrometer-resolution solar cell characterization by light beam-induced current mapping

    NASA Astrophysics Data System (ADS)

    Cossutta, H.; Taretto, K.; Troviano, M.

    2014-10-01

    Light-beam induced current (LBIC) mapping is an increasingly utilized characterization technique for laboratory-scale as well as industrial-scale solar cells, which measures the local solar cell photocurrent by point illumination. This contribution demonstrates the design and testing of an LBIC mapping device capable of measuring LBIC maps of solar cells using inexpensive materials. With a spatial resolution of 4 µm and an auto-focused beam spot size of about 2 µm, obtained from a standard CD/DVD pickup, high-resolution LBIC maps of thin-film solar cells are obtained. The system was demonstrated by measuring LBIC maps on thin-film solar cells, revealing significant, micrometer-sized photocurrent heterogeneities that are otherwise unseen when using typical commercial LBIC systems with lower resolution.

  12. Habitat selection behaviour links local and regional scales in aquatic systems.

    PubMed

    Resetarits, William J

    2005-05-01

    The role of habitat selection behaviour in the assembly of natural communities is an increasingly important theme in ecology. At the same time, ecologists and conservation biologists are keenly interested in scale and how processes at scales from local to regional interact to determine species distributions and patterns of biodiversity. How important is habitat selection in generating observed patterns of distribution and diversity at multiple spatial scales? In theory, habitat selection in response to interacting species can generate both positive and negative covariances among species distributions and create the potential to link processes of community assembly across multiple scales. Here I demonstrate that habitat selection by treefrogs in response to the distribution of fish predators functions at both the regional scale among localities and the local scale among patches within localities, implicating habitat selection as a critical link between local communities and the regional dynamics of metacommunities in complex landscapes.

  13. The ecology of dust: local- to global-scale perspectives

    SciTech Connect

    Whicker, Jeffrey J; Field, Jason P; Belnap, Jayne; Breshears, David D; Neff, Jason; Okin, Gregory S; Painter, Thomas H; Ravi, Sujith; Reheis, Marith C; Reynolds, Richard L

    2009-01-01

    Emission and redistribution of dust due to wind erosion in drylands drives major biogeochemical dynamics and provides important aeolian environmental connectivity at scales from individual plants up to the global scale. Yet, perhaps because most relevant research on aeolian processes has been presented in a geosciences rather than ecological context, most ecological studies do not explicitly consider dust-driven processes. To bridge this disciplinary gap, we provide a general overview of the ecological importance of dust, examine complex interactions between wind erosion and ecosystem dynamics from the plant-interspace scale to regional and global scales, and highlight specific examples of how disturbance affects these interactions and their consequences. Changes in climate and intensification of land use will both likely lead to increased dust production. To address these challenges, environmental scientists, land managers and policy makers need to more explicitly consider dust in resource management decisions.

  14. Single parameter scaling in one-dimensional localization revisited

    PubMed

    Deych; Lisyansky; Altshuler

    2000-03-20

    The variance of the Lyapunov exponent is calculated exactly in the one-dimensional Anderson model with random site energies distributed according to the Cauchy distribution. We find a new significant scaling parameter in the system, and derive an exact analytical criterion for single parameter scaling which differs from the commonly used condition of phase randomization. The results obtained are applied to the Kronig-Penney model with the potential in the form of periodically positioned delta functions with random strength.

  15. Incorporating layer- and local-scale heterogeneities in numerical simulation of unsaturated flow and tracer transport.

    PubMed

    Pan, Feng; Ye, Ming; Zhu, Jianting; Wu, Yu-Shu; Hu, Bill X; Yu, Zhongbo

    2009-01-26

    This study characterizes layer- and local-scale heterogeneities in hydraulic parameters (i.e., matrix permeability and porosity) and investigates the relative effect of layer- and local-scale heterogeneities on the uncertainty assessment of unsaturated flow and tracer transport in the unsaturated zone of Yucca Mountain, USA. The layer-scale heterogeneity is specific to hydrogeologic layers with layerwise properties, while the local-scale heterogeneity refers to the spatial variation of hydraulic properties within a layer. A Monte Carlo method is used to estimate mean, variance, and 5th, and 95th percentiles for the quantities of interest (e.g., matrix saturation and normalized cumulative mass arrival). Model simulations of unsaturated flow are evaluated by comparing the simulated and observed matrix saturations. Local-scale heterogeneity is examined by comparing the results of this study with those of the previous study that only considers layer-scale heterogeneity. We find that local-scale heterogeneity significantly increases predictive uncertainty in the percolation fluxes and tracer plumes, whereas the mean predictions are only slightly affected by the local-scale heterogeneity. The mean travel time of the conservative and reactive tracers to the water table in the early stage increases significantly due to the local-scale heterogeneity, while the influence of local-scale heterogeneity on travel time gradually decreases over time. Layer-scale heterogeneity is more important than local-scale heterogeneity for simulating overall tracer travel time, suggesting that it would be more cost-effective to reduce the layer-scale parameter uncertainty in order to reduce predictive uncertainty in tracer transport.

  16. Incorporating layer- and local-scale heterogeneities in numerical simulation of unsaturated flow and tracer transport

    NASA Astrophysics Data System (ADS)

    Pan, Feng; Ye, Ming; Zhu, Jianting; Wu, Yu-Shu; Hu, Bill X.; Yu, Zhongbo

    2009-01-01

    This study characterizes layer- and local-scale heterogeneities in hydraulic parameters (i.e., matrix permeability and porosity) and investigates the relative effect of layer- and local-scale heterogeneities on the uncertainty assessment of unsaturated flow and tracer transport in the unsaturated zone of Yucca Mountain, USA. The layer-scale heterogeneity is specific to hydrogeologic layers with layerwise properties, while the local-scale heterogeneity refers to the spatial variation of hydraulic properties within a layer. A Monte Carlo method is used to estimate mean, variance, and 5th, and 95th percentiles for the quantities of interest (e.g., matrix saturation and normalized cumulative mass arrival). Model simulations of unsaturated flow are evaluated by comparing the simulated and observed matrix saturations. Local-scale heterogeneity is examined by comparing the results of this study with those of the previous study that only considers layer-scale heterogeneity. We find that local-scale heterogeneity significantly increases predictive uncertainty in the percolation fluxes and tracer plumes, whereas the mean predictions are only slightly affected by the local-scale heterogeneity. The mean travel time of the conservative and reactive tracers to the water table in the early stage increases significantly due to the local-scale heterogeneity, while the influence of local-scale heterogeneity on travel time gradually decreases over time. Layer-scale heterogeneity is more important than local-scale heterogeneity for simulating overall tracer travel time, suggesting that it would be more cost-effective to reduce the layer-scale parameter uncertainty in order to reduce predictive uncertainty in tracer transport.

  17. The Herschel ATLAS: Evolution of the 250 Micrometer Luminosity Function Out to z = 0.5

    NASA Technical Reports Server (NTRS)

    Dye, S.; Dunne, L.; Eales, S.; Smith, D. J. B.; Amblard, A.; Auld, R.; Baes, M.; Baldry, I. K.; Bamford, S.; Blain, A. W.; Bonfield, D. G.; Bremer, M.; Burgarella, D.; Buttiglione, S.; Cameron, E.; Cava, A.; Clements, D. L.; Cooray, A.; Croom, S.; Dariush, A.; de Zotti, G.; Driver, S.; Dunlop, J. S.; Frayer, D.; Leeuw, L.

    2010-01-01

    We have determined the luminosity function of 250 micrometer-selected galaxies detected in the approximately equal to 14 deg(sup 2) science demonstration region of the Herschel-ATLAS project out to a redshift of z = 0.5. Our findings very clearly show that the luminosity function evolves steadily out to this redshift. By selecting a sub-group of sources within a fixed luminosity interval where incompleteness effects are minimal, we have measured a smooth increase in the comoving 250 micrometer luminosity density out to z = 0.2 where it is 3.6(sup +1.4) (sub -0.9) times higher than the local value.

  18. Localized density matrix minimization and linear-scaling algorithms

    NASA Astrophysics Data System (ADS)

    Lai, Rongjie; Lu, Jianfeng

    2016-06-01

    We propose a convex variational approach to compute localized density matrices for both zero temperature and finite temperature cases, by adding an entry-wise ℓ1 regularization to the free energy of the quantum system. Based on the fact that the density matrix decays exponentially away from the diagonal for insulating systems or systems at finite temperature, the proposed ℓ1 regularized variational method provides an effective way to approximate the original quantum system. We provide theoretical analysis of the approximation behavior and also design convergence guaranteed numerical algorithms based on Bregman iteration. More importantly, the ℓ1 regularized system naturally leads to localized density matrices with banded structure, which enables us to develop approximating algorithms to find the localized density matrices with computation cost linearly dependent on the problem size.

  19. On-tip sub-micrometer Hall probes for magnetic microscopy prepared by AFM lithography.

    PubMed

    Gregusová, D; Martaus, J; Fedor, J; Kúdela, R; Kostic, I; Cambel, V

    2009-07-01

    We developed a technology of sub-micrometer Hall probes for future application in scanning hall probe microscopy (SHPM) and magnetic force microscopy (MFM). First, the Hall probes of approximately 9-mum dimensions are prepared on the top of high-aspect-ratio GaAs pyramids with an InGaP/AlGaAs/GaAs active layer using wet-chemical etching and non-planar lithography. Then we show that the active area of planar Hall probes can be downsized to sub-micrometer dimensions by local anodic oxidation technique using an atomic force microscope. Such planar probes are tested and their noise and magnetic field sensitivity are evaluated. Finally, the two technologies are combined to fabricate sub-micrometer Hall probes on the top of high-aspect ratio mesa for future SHPM and MFM techniques.

  20. Scale Factor Study for 1:30 Local Scour Model

    DTIC Science & Technology

    2016-08-01

    18 2012; Melville and Chiew 1999; Lee and Sturm 2009; Mia and Nago 2003; Mueller and Wagner 2005). Multiple predictive equations have been...local scour at circular bridge pier. J. Hydraul. Eng. 129:420–427. Mueller, D. S., and C. R. Wagner . 2005. Field observations and evaluations of

  1. Science for action at the local landscape scale

    Treesearch

    Paul Opddam; Joan Iverson Nassauer; Zhifang Wang; Christian Albert; Gary Bentrup; Jean-Christophe Castella; Clive McAlpine; Jianguo Liu; Stephen Sheppard; Simon Swaffield

    2013-01-01

    For landscape ecology to produce knowledge relevant to society, it must include considerations of human culture and behavior, extending beyond the natural sciences to synthesize with many other disciplines. Furthermore, it needs to be able to support landscape change processes which increasingly take the shape of deliberative and collaborative decision making by local...

  2. Scaling Performance Assessments: Strategies for Managing Local Item Dependence.

    ERIC Educational Resources Information Center

    Yen, Wendy M.

    1993-01-01

    Results from the Maryland School Performance Assessment Program for 5,392 elementary school students and from the Comprehensive Tests of Basic Skills (multiple choice) for a national sample are used to explore local item independence (LID) of test items. Some strategies are suggested for measuring LID in performance assessments. (SLD)

  3. Scaling theory of Anderson localization: A renormalization-group approach

    NASA Astrophysics Data System (ADS)

    Sarker, Sanjoy; Domany, Eytan

    1981-06-01

    A position-space renormalization-group method, suitable for studying the localization properties of electrons in a disordered system, was developed. Two different approximations to a well-defined exact procedure were used. The first method is a perturbative treatment to lowest order in the intercell couplings. This yields a localization edge in three dimensions, with a fixed point at the band center (E=0) at a critical disorder σc~=7.0. In the neighborhood of the fixed point the localization length L is predicted to diverge as L~(σ-σc+βE2)-ν. In two dimensions no fixed point is found, indicating localization even for small randomness, in agreement with Abrahams, Anderson, Licciardello, and Ramakrishnan. The second method is an application of the finite-lattice approximation, in which the intercell hopping between two (or more) cells is treated to infinite order in perturbation theory. To our knowledge, this method has not been previously used for quantum systems. Calculations based on this approximation were carried out in two dimensions only, yielding results that are in agreement with those of the lowest-order approximation.

  4. Local viscosity and environment on the nanometer scale

    NASA Astrophysics Data System (ADS)

    Jeon, Sangmin

    2002-01-01

    Local viscosity and environment of various systems were studied by electrical, mechanical and optical methods. Dielectric loss peaks of both normal-mode relaxation and of segmental motion of cis-polyisoprene with various molecular weights were measured at different film thickness. While the normal mode relaxation was retarded as film thickness decreases, segemental mode was not. This contrasting thickness and temperature dependence of the normal-mode and segmental relaxtion modes indicates strong breakdown of time-temperature superposition. Furthermore, the normal mode relaxation of the lower molecular weight polyisoprene showed more retardation than that of higher one. Both large shear with low frequency and small shear with high frequency were applied to molecularly confined OMCTS (Octamethylcyclotetrasiloxane) inside SFA to observe its stick to slip transition. Large shear caused the structural changes of the film and small shear probed the rheological properties of the confined liquid during the slow large shear process. Shear probe also detected dynamic lateral alignment of OMCTS near mica surface during the repeated approaches and separations. When triangular normal force was applied, force distance profile and viscoelastic components were measured at the same time by capacitance and shear device respectively. Although each OMCTS layer always appears at the same distance from the solid wall, its viscoelastic measurement showed additional sub changes even at the same film thickness. New optical setup for two photon excitation time-resolved fluorescence anisotropy and lifetime measurements was built and used to understand the local environment and viscosity. The rotational correlation time constants by the fluorescence anisotropy provide the information on the hydrodynamic volume and local viscosity near the probe. Instead, the fluorescence lifetime does the local environment near the probe such as pH, temperature and polarity of the medium. Based on these

  5. An algorithm for recognition and localization of rotated and scaled objects

    NASA Technical Reports Server (NTRS)

    Peli, T.

    1981-01-01

    An algorithm for recognition and localization of objects, which is invariant to displacement and rotation, is extended to the recognition and localization of differently scaled, rotated, and displaced objects. The proposed algorithm provides an optimum way to find if a match exists between two objects that are scaled, rotated, and displaced, while the number of computations is of the same order as for equally scaled objects.

  6. Stability of Large-Scale Oceanic Flows and the Importance of Non-Local Effects

    DTIC Science & Technology

    2009-06-01

    2009-09 DOCTORAL DISSERTATION by Hristina G. Hristova June 2009 Stability of Large -Scale Oceanic Flows and the Importance of Non-Local Effects MIT...MITIWHOI 2009-09 Stability of Large -Scale Oceanic Flows and the Importance of Non-Local Effects by Hristina G. Hristova Massachusetts Institute of...part is permitted for any purpose of the United States Government. This thesis should be cited as: Hristina G. Hristova, 2009. Stability of Large -Scale

  7. Large scale clear-water local pier scour experiments

    USGS Publications Warehouse

    Sheppard, D.M.; Odeh, M.; Glasser, T.

    2004-01-01

    Local clear-water scour tests were performed with three different diameter circular piles (0. 114, 0.305, and 0.914 m), three different uniform cohesionless sediment diameters (0.22, 0.80, and 2.90 mm) and a range of water depths and flow velocities. The tests were performed in the 6.1 m wide, 6.4 m deep, and 38.4 m long flume at the United States Geological Survey Conte Research Center in Turners Falls, Mass. These tests extend local scour data obtained in controlled experiments to prototype size piles and ratios of pile diameter to sediment diameter to 4,155. Supply water for this flow through flume was supplied by a hydroelectric power plant reservoir and the concentration of suspended fine sediment (wash load) could not be controlled. Equilibrium scour depths were found to depend on the wash load concentration. ?? ASCE.

  8. Recent Trends in Local-Scale Marine Biodiversity Reflect Community Structure and Human Impacts.

    PubMed

    Elahi, Robin; O'Connor, Mary I; Byrnes, Jarrett E K; Dunic, Jillian; Eriksson, Britas Klemens; Hensel, Marc J S; Kearns, Patrick J

    2015-07-20

    The modern biodiversity crisis reflects global extinctions and local introductions. Human activities have dramatically altered rates and scales of processes that regulate biodiversity at local scales. Reconciling the threat of global biodiversity loss with recent evidence of stability at fine spatial scales is a major challenge and requires a nuanced approach to biodiversity change that integrates ecological understanding. With a new dataset of 471 diversity time series spanning from 1962 to 2015 from marine coastal ecosystems, we tested (1) whether biodiversity changed at local scales in recent decades, and (2) whether we can ignore ecological context (e.g., proximate human impacts, trophic level, spatial scale) and still make informative inferences regarding local change. We detected a predominant signal of increasing species richness in coastal systems since 1962 in our dataset, though net species loss was associated with localized effects of anthropogenic impacts. Our geographically extensive dataset is unlikely to be a random sample of marine coastal habitats; impacted sites (3% of our time series) were underrepresented relative to their global presence. These local-scale patterns do not contradict the prospect of accelerating global extinctions but are consistent with local species loss in areas with direct human impacts and increases in diversity due to invasions and range expansions in lower impact areas. Attempts to detect and understand local biodiversity trends are incomplete without information on local human activities and ecological context. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Copper-micrometer-sized diamond nanostructured composites

    NASA Astrophysics Data System (ADS)

    Nunes, D.; Livramento, V.; Shohoji, N.; Fernandes, H.; Silva, C.; Correia, J. B.; Carvalho, P. A.

    2011-12-01

    Reinforcement of a copper matrix with diamond enables tailoring the properties demanded for thermal management applications at high temperature, such as the ones required for heat sink materials in low activated nuclear fusion reactors. For an optimum compromise between thermal conductivity and mechanical properties, a novel approach based on multiscale diamond dispersions is proposed: a Cu-nanodiamond composite produced by milling is used as a nanostructured matrix for further dispersion of micrometer-sized diamond (μDiamond). A series of Cu-nanodiamond mixtures have been milled to establish a suitable nanodiamond fraction. A refined matrix with homogeneously dispersed nanoparticles was obtained with 4 at.% μDiamond for posterior mixture with microdiamond and subsequent consolidation. Preliminary consolidation by hot extrusion of a mixture of pure copper and μDiamond has been carried out to define optimal processing parameters. The materials produced were characterized by x-ray diffraction, scanning and transmission electron microscopy and microhardness measurements.

  10. Local and Regional Scale Simulation of River Aquifer Interactions.

    NASA Astrophysics Data System (ADS)

    Niswonger, R.; Fleckenstein, J. H.; Fogg, G. E.

    2003-12-01

    Overdraft of groundwater in Sacramento County, California has severely depressed regional groundwater levels and depleted base flows along the Cosumnes River. These developments continue to negatively impact riparian vegetation and threaten the fall migration of endangered Chinook salmon. In this study river aquifer interactions are investigated along a 200m reach of the Cosumnes River using continuous field measurements of riverbed temperature, water content and matric potential to a depth of 10m below the riverbed. These data demonstrate complex seepage patterns including fracture flow and the formation of perched aquifers due to geologic heterogeneity. Riverbed sediment heterogeneity was characterized using geostatistical indicator simulations based on continuous core data. A 3-dimensional reach-scale model was developed using the TOUGH2 simulator. Modeling results suggest that the success of riparian vegetation may depend on the presence of perched aquifers. The reach-scale model will also provide better estimates of riverbed hydraulic properties for use in a larger regional-scale groundwater flow model. The regional model was developed based on detailed geostatistical simulations of the Cosumnes alluvial fan hydrostratigraphy using a version of MODFLOW that includes the ability to simulate unsaturated flow between the river and the aquifer. The regional model is used to assess management scenarios that are developed to improve fall flows and to enhance overall river ecology.

  11. Local mechanical spectroscopy with nanometer-scale lateral resolution

    NASA Astrophysics Data System (ADS)

    Oulevey, F.; Gremaud, G.; Sémoroz, A.; Kulik, A. J.; Burnham, N. A.; Dupas, E.; Gourdon, D.

    1998-05-01

    A new technique has been developed to probe the viscoelastic and anelastic properties of submicron phases of inhomogeneous materials. The measurement gives information related to the internal friction and to the variations of the dynamic modulus of nanometer-sized volumes. It is then the nanoscale equivalent to mechanical spectroscopy, a well-known macroscopic technique for materials studies, also sometimes called dynamic mechanical (thermal) analysis. The technique is based on a scanning force microscope, using the principle of scanning local-acceleration microscopy (SLAM), and allows the sample temperature to be changed. It is called variable-temperature SLAM, abbreviated T-SLAM. According to a recent proposition to systematize names of scanning probe microscope based methods, this technique should be included in the family of "mechanothermal analysis with scanning microscopy." It is suited for studying defect dynamics in nanomaterials and composites by locating the dissipative mechanisms in submicron phases. The primary and secondary relaxations, as well as the viscoplasticity, were observed in bulk PVC. The wide range of phenomena demonstrate the versatility of the technique. A still unexplained increase of the stiffness with increasing temperature was observed just below the glass transition. All of these observations, although their interpretation in terms of physical events is still tentative, are in agreement with global studies. This technique also permits one to image the variations of the local elasticity or of the local damping at a fixed temperature. This enables the study of, for instance, the homogeneity of phase transitions in multiphased materials, or of the interface morphologies and properties. As an illustration, the homogeneity of the glass transition temperature of PVC in a 50/50 wt % PVC/PB polymer blend has been demonstrated. Due to the small size of the probed volume, T-SLAM gives information on the mechanical properties of the near

  12. Scaling Behavior of Turbulent Oscillators with Non-Local Interaction

    NASA Astrophysics Data System (ADS)

    Kuramoto, Y.

    1995-09-01

    A general class of models is proposed for populations of biologically oscillating cells secreting substance whose rapid diffusion mediates the cell-cell interaction. Under certain conditions, such models are reduced to a system of non-locally coupled oscillators of the Ginzburg-Landau type. The last model in space dimension one is analyzed numerically, and some remarkable features of the turbulence generated are revealed. In particular, the correlations and fluctuations obey a power law similar to the one in the fully-devleoped Navier-Stokes turbulence except that our exponents change continuously with the coupling strength.

  13. Tropical deforestation: Modeling local- to regional-scale climate change

    SciTech Connect

    Henderson-Sellers, A.; Durbidge, T.B.; Pitman, A.J. ); Dickinson, R.E. ); Kennedy, P.J. ); McGuffie, K. )

    1993-04-20

    The authors report results from a model study using the National Center for Atmospheric Research Community Climate Model (Version 1) general circulation model to assess the impact of regional scale deforestation on climate change. In the model a large parcel in the Amazon basin is changed from tropical rain forest to scrub grassland. Impacts can include adding CO[sub 2] to the atmosphere by biomass burning, increasing surface albedo, changing precipitation and evaporation rates, impacting soil moisture, and general weather patterns. They compare their model results with earlier work which has looked at this same problem.

  14. Linear scaling calculation of maximally localized Wannier functions with atomic basis set.

    PubMed

    Xiang, H J; Li, Zhenyu; Liang, W Z; Yang, Jinlong; Hou, J G; Zhu, Qingshi

    2006-06-21

    We have developed a linear scaling algorithm for calculating maximally localized Wannier functions (MLWFs) using atomic orbital basis. An O(N) ground state calculation is carried out to get the density matrix (DM). Through a projection of the DM onto atomic orbitals and a subsequent O(N) orthogonalization, we obtain initial orthogonal localized orbitals. These orbitals can be maximally localized in linear scaling by simple Jacobi sweeps. Our O(N) method is validated by applying it to water molecule and wurtzite ZnO. The linear scaling behavior of the new method is demonstrated by computing the MLWFs of boron nitride nanotubes.

  15. Does bird species diversity vary among forest types? A local-scale test in Southern Chile

    NASA Astrophysics Data System (ADS)

    Fontúrbel, Francisco E.; Jiménez, Jaime E.

    2014-10-01

    Birds are the most diverse vertebrate group in Chile, characterized by low species turnover at the country-size scale (high alpha but low beta diversities), resembling an island biota. We tested whether this low differentiation is valid at a local scale, among six forest habitat types. We detected 25 bird species; avifauna composition was significantly different among habitat types, with five species accounting for 60 % of the dissimilarity. We found a higher level of bird assemblage differentiation across habitats at the local scale than has been found at the country-size scale. Such differentiation might be attributed to structural differences among habitats.

  16. Lateral length scales and local character of exchange bias.

    NASA Astrophysics Data System (ADS)

    Schuller, Ivan K.

    2005-03-01

    Exchange bias (EB) is a ferromagnet (F) -- antiferromagnet (AF) proximity effect. EB manifests itself as a horizontal shift of a single hysteresis loop. In our studies, an untwinned 38--100 nm-thick layer of (110) FeF2 is epitaxially grown on (110) MgF2, followed by a 4--70 nm-thick layer of Co, Ni or Fe. Easy axis magnetization curves (SQUID and spatially resolved MOKE) for different cooling fields and remanent magnetizations for zero-field cooled samples exhibit negatively or positively shifted single or tunable double hysteresis loops (DHL). In the untwinned epitaxial FeF2, the AF domains can be much larger than the grains, and, hence, as large as the F domains. When each F domain is in contact with only one AF domain, it does not average the direction and the magnitude of EB. In this regime, inhomogeneity of an AF-F sample, either structural or magnetic, can result in two subsystems formed upon cooling through the AF transition temperature. Each subsystem exhibits EB of the same magnitude but of the opposite sign, which gives rise to DHL. We conclude that when the domain size in the AF is larger than or comparable to that in the F, the local, non-averaging character of EB can be observed. Work supported by DOE and AFOSR.

  17. Understanding food-web persistence from local to global scales.

    PubMed

    Stouffer, Daniel B; Bascompte, Jordi

    2010-02-01

    Understanding food-web persistence is an important long-term objective of ecology because of its relevance in maintaining biodiversity. To date, many dynamic studies of food-web behaviour--both empirical and theoretical--have focused on smaller sub-webs, called trophic modules, because these modules are more tractable experimentally and analytically than whole food webs. The question remains to what degree studies of trophic modules are relevant to infer the persistence of entire food webs. Four trophic modules have received particular attention in the literature: tri-trophic food chains, omnivory, exploitative competition, and apparent competition. Here, we integrate analysis of these modules' dynamics in isolation with those of whole food webs to directly assess the appropriateness of scaling from modules to food webs. We find that there is not a direct, one-to-one, relationship between the relative persistence of modules in isolation and their effect on persistence of an entire food web. Nevertheless, we observe that those modules which are most commonly found in empirical food webs are those that confer the greatest community persistence. As a consequence, we demonstrate that there may be significant dynamic justifications for empirically-observed food-web structure.

  18. Rapid Adjustment across scales: From global to local.

    NASA Astrophysics Data System (ADS)

    Nam, Christine; Quaas, Johannes

    2017-04-01

    An important, yet uncertain, component of the climate's total response to an increase in CO2 concentrations are rapid adjustments. Rapid adjustments to CO2 forcings vary considerably amongst general circulation models due to the fact clouds, turbulence, their coupling, and the resulting dynamical response are not calculated reliably by general circulation models [Gregory and Webb, 2008 & Sherwood et al., 2015]. This motivates the use of a cloud resolving model, which resolves clouds and turbulence, to better understand rapid adjustments. Cloud resolving models, however, can only be run over a limited area and so one must select an area which has the same magnitude of variability found in rapid adjustments globally. In this work, we ask "Are rapid adjustment to CO2 forcings over Central Europe in the ICON-GCM and ICON-LEM representative of global adjustment variability?" Using the newly developed ICON (Icosahedral non-hydrostatic) general circulation model (GCM) and large-eddy model (LEM) developed by the Max-Planck Institute for Meteorology (MPI) and Deutsche Wetterdienst (DWD), a study of rapid adjustments is performed across scales.

  19. Influence of Agricultural Practices on Micrometerological Spatial Variations at Local and Regional Scales

    USDA-ARS?s Scientific Manuscript database

    Soil-vegetation-atmosphere transfers significantly influence interactions and feedbacks between vegetation and boundary layer in relation with plant phenology and water status. The current study focused on linking micrometeorological conditions to cultural practices at the local and regional scales ...

  20. Technical note: Multiple wavelet coherence for untangling scale-specific and localized multivariate relationships in geosciences

    NASA Astrophysics Data System (ADS)

    Hu, Wei; Si, Bing Cheng

    2016-08-01

    The scale-specific and localized bivariate relationships in geosciences can be revealed using bivariate wavelet coherence. The objective of this study was to develop a multiple wavelet coherence method for examining scale-specific and localized multivariate relationships. Stationary and non-stationary artificial data sets, generated with the response variable as the summation of five predictor variables (cosine waves) with different scales, were used to test the new method. Comparisons were also conducted using existing multivariate methods, including multiple spectral coherence and multivariate empirical mode decomposition (MEMD). Results show that multiple spectral coherence is unable to identify localized multivariate relationships, and underestimates the scale-specific multivariate relationships for non-stationary processes. The MEMD method was able to separate all variables into components at the same set of scales, revealing scale-specific relationships when combined with multiple correlation coefficients, but has the same weakness as multiple spectral coherence. However, multiple wavelet coherences are able to identify scale-specific and localized multivariate relationships, as they are close to 1 at multiple scales and locations corresponding to those of predictor variables. Therefore, multiple wavelet coherence outperforms other common multivariate methods. Multiple wavelet coherence was applied to a real data set and revealed the optimal combination of factors for explaining temporal variation of free water evaporation at the Changwu site in China at multiple scale-location domains. Matlab codes for multiple wavelet coherence were developed and are provided in the Supplement.

  1. Reading Outside Micrometers. Courseware Evaluation for Vocational and Technical Education.

    ERIC Educational Resources Information Center

    Sommer, Sandra; And Others

    This courseware evaluation rates the Reading Outside Micrometers program developed by EMC Publishing Company. (The program--not contained in this document--uses high resolution graphics to illustrate the micrometer's components, functions, and practical applications.) Part A describes the program in terms of subject area and equipment requirements…

  2. Cell migration under ultrasound irradiations in micrometer scale

    NASA Astrophysics Data System (ADS)

    Murakami, Shinya; Otsuka, Yo; Oshima, Yusuke; Hikita, Atsuhiko; Mitsui, Toshiyuki

    2013-03-01

    Cell movements, migration play an important role in many physiological processes including cell proliferation and differentiation. C2C12, a line of mouse myoblasts is known to differentiate into osteoblast under appropriate conditions. Therefore, C2C12 cells can be chosen for the differentiation studies. However, the movement of the C2C12's has not been fully investigated although the movements may provide a better understanding of the healing processes of bone repair, regeneration and differentiation. In addition, low intensity ultrasound has been thought and used to promote bone fracture healing although the microscopic mechanism of this healing is not well understood. As a first step, we have investigated single cell migration of C2C12 under optical microscopy with and without ultrasound irradiations. The ultrasound is irradiated from an apex of a sharp needle. The frequency is 1.5 MHz and the power intensity is near 24 mW/cm2. These values were similar to the ultrasound treatment values. In this conference, we will show the influence of the ultrasound irradiation on the cell movement by plotting the mean squared displacement and the velocity autocorrelation function as a function of time.

  3. Two-measure theory with third-rank antisymmetric tensor for local scale symmetry breaking

    NASA Astrophysics Data System (ADS)

    Guendelman, Eduardo; Nishino, Hitoshi; Rajpoot, Subhash

    2017-03-01

    We present a new mechanism of local scale symmetry breaking based on the scalar density Φ ≡(1 /3 !)ɛμ ν ρ σ∂μAν ρ σ≡(1 /4 !)ɛμ ν ρ σFμν ρ σ (0 ) with an independent third-rank tensor Aμ ν ρ , which replaces the scalar density Φ ≡ɛμ ν ρ σɛa b c d(∂μφa)(∂νφb)(∂ρφc)(∂σφd) used in "two-measure theory." We apply this function both to globally and locally scale-invariant systems. For local scale invariance, we modify Fμν ρ σ (0 ) by a certain Chern-Simons term, based on the recently developed tensor-hierarchy formulation. For a locally scale-invariant system with multiple scalars, the minimum value of the potential is realized at exactly zero value, while local scale invariance is broken by some nonzero vacuum expectation values: ∃⟨σi⟩≠0 , ∃⟨Fm n r s⟩=f0ɛm n r s≠0 . For these values, the cosmological constant is maintained to be zero, despite the broken local scale invariance.

  4. Responses to climate change in hot desert ecosystems: connecting local to global scales

    USDA-ARS?s Scientific Manuscript database

    The consequences of connectivity in resources, propagules, and information to the interplay between drivers and responses across scales can result in ecological dynamics that are not easily predicted based on local drivers. Three major classes of connectivity events link local ecological dynamics wi...

  5. Local maladaptation in the soft scale insect Saissetia coffeae (Hemiptera: Coccidae).

    PubMed

    Spitzer, Brian

    2006-09-01

    Local adaptation has often been documented in herbivorous insects. The potential for local maladaptation in phytophagous insects, however, has not been widely considered. I performed a two-generation reciprocal cross-transplant experiment with the generalist soft scale insect Saissetia coffeae (Hemiptera: Coccidae) on two common species of host plants in rain forest habitat in Costa Rica. In this system, S. coffeae showed significant local maladaptation at the level of the host species. Lineages originally collected from Witheringia enjoyed a strong advantage over those collected from Lomariopsis when both sets of lineages were placed on Lomariopsis; however, when both sets of lineages were raised on Witheringia, their fitnesses were statistically indistinguishable. While some aspects of the biology of S. coffeae may impair its ability to adapt to local selection pressures, scale insects are often locally adapted on fine spatial scales, and local maladaptation is therefore especially surprising. Other documented cases of local maladaptation in parasites appear to be due to evolution on the part of the host. The possibility that hosts or natural enemies may place local genotypes at a disadvantage, producing a pattern of local maladaptation, is one that deserves more consideration in the context of plant-insect interactions.

  6. Autonomous buckling of micrometer-sized lipid-protein membrane patches constructed by Dictyostelium discoideum.

    PubMed

    Takahashi, Kei; Toyota, Taro

    2015-01-01

    The cytosol of amoeba cells controls the membrane deformation during their motion in vivo. To investigate such ability of the cytosol of amoeba cell, Dictyostelium discoideum (Dictyostelium), in vitro, we used lipids extracted from Dictyostelium and commercially available phospholipids, and prepared substrate-supported lipid membrane patches on the micrometer scale by spin coating. We found that the spin coater holder, which has pores (pore size = 3.1 mm) of negative pressure to hold the cover glass induced the concave surface of the cover glass. The membrane lipid patches were formed at each position in the vicinity of the holder pores and their sizes were in the range of 2.7 to 3.2 × 10(4) μm(2). After addition of the cytosol extracted from Dictyostelium to the lipid membrane patches, through time-lapse observation with a confocal laser scanning fluorescence microscope, we observed an autonomous buckling of the Dictyostelium lipid patches and localized behaviours of proteins found within. The current method serves as the novel technique for the preparation of film patches in which the positions of patches are controlled by the holder pores without fabricating, modifying, and arranging the chemical properties of the solution components of lipids. The findings imply that lipid-binding proteins in the cytosol were adsorbed and accumulated within the Dictyostelium lipid patches, inducing the transformation of the cell-sized patch.

  7. Localization Algorithm Based on a Spring Model (LASM) for Large Scale Wireless Sensor Networks

    PubMed Central

    Chen, Wanming; Mei, Tao; Meng, Max Q.-H.; Liang, Huawei; Liu, Yumei; Li, Yangming; Li, Shuai

    2008-01-01

    A navigation method for a lunar rover based on large scale wireless sensor networks is proposed. To obtain high navigation accuracy and large exploration area, high node localization accuracy and large network scale are required. However, the computational and communication complexity and time consumption are greatly increased with the increase of the network scales. A localization algorithm based on a spring model (LASM) method is proposed to reduce the computational complexity, while maintaining the localization accuracy in large scale sensor networks. The algorithm simulates the dynamics of physical spring system to estimate the positions of nodes. The sensor nodes are set as particles with masses and connected with neighbor nodes by virtual springs. The virtual springs will force the particles move to the original positions, the node positions correspondingly, from the randomly set positions. Therefore, a blind node position can be determined from the LASM algorithm by calculating the related forces with the neighbor nodes. The computational and communication complexity are O(1) for each node, since the number of the neighbor nodes does not increase proportionally with the network scale size. Three patches are proposed to avoid local optimization, kick out bad nodes and deal with node variation. Simulation results show that the computational and communication complexity are almost constant despite of the increase of the network scale size. The time consumption has also been proven to remain almost constant since the calculation steps are almost unrelated with the network scale size. PMID:27879793

  8. Localization Algorithm Based on a Spring Model (LASM) for Large Scale Wireless Sensor Networks.

    PubMed

    Chen, Wanming; Mei, Tao; Meng, Max Q-H; Liang, Huawei; Liu, Yumei; Li, Yangming; Li, Shuai

    2008-03-15

    A navigation method for a lunar rover based on large scale wireless sensornetworks is proposed. To obtain high navigation accuracy and large exploration area, highnode localization accuracy and large network scale are required. However, thecomputational and communication complexity and time consumption are greatly increasedwith the increase of the network scales. A localization algorithm based on a spring model(LASM) method is proposed to reduce the computational complexity, while maintainingthe localization accuracy in large scale sensor networks. The algorithm simulates thedynamics of physical spring system to estimate the positions of nodes. The sensor nodesare set as particles with masses and connected with neighbor nodes by virtual springs. Thevirtual springs will force the particles move to the original positions, the node positionscorrespondingly, from the randomly set positions. Therefore, a blind node position can bedetermined from the LASM algorithm by calculating the related forces with the neighbornodes. The computational and communication complexity are O(1) for each node, since thenumber of the neighbor nodes does not increase proportionally with the network scale size.Three patches are proposed to avoid local optimization, kick out bad nodes and deal withnode variation. Simulation results show that the computational and communicationcomplexity are almost constant despite of the increase of the network scale size. The time consumption has also been proven to remain almost constant since the calculation steps arealmost unrelated with the network scale size.

  9. Non-local and nonlinear background suppression method controlled by multi-scale clutter metric

    NASA Astrophysics Data System (ADS)

    Gong, Jinnan; Hou, Qingyu; Zhang, Wei; Zhi, Xiyang

    2015-07-01

    To improve the detection performance for non-morphological multi-scale target in IR image containing complex cloud clutter, on basis of cloud scenario self-similarity feature, a non-local and nonlinear background suppression algorithm controlled by multi-scale clutter metric is presented. According to the classical achievements on cloud structure, self-similarity and relativity of cloud clutter on image for target detection is deeply analyzed by classical indicators firstly. Then we establish multi-scale clutter metric method based on LoG operator to describe scenes feature for controlled suppression method. After that, non-local means based on optimal strength similarity metric as non-local processing, and multi-scale median filter and on minimum gradient direction as local processing are set up. Finally linear fusing principle adopting clutter metric for local and non-local processing is put forward. Experimental results by two kinds of infrared imageries show that compared with classical and similar methods, the proposed method solves the existing problems of targets energy attenuation and suppression degradation in strongly evolving regions in previous methods. By evaluating indicators, the proposed method has a superior background suppression performance by increasing the BSF and ISCR 2 times at least.

  10. Developing an Integrated Approach for Local Urban Climate Models in London from Neighbourhood to Street Scale

    NASA Astrophysics Data System (ADS)

    Bakkali, M.; Davies, M.; Steadman, J. P.

    2012-04-01

    We currently have an incomplete understanding of how weather varies across London and how the city's microclimate will intensify levels of heat, cold and air pollution in the future. There is a need to target priority areas of the city and to promote design guidance on climate change mitigation strategies. As a result of improvements in the accuracy of local weather data in London, an opportunity is emerging for designers and planners of the built environment to measure the impact of their designs on local urban climate and to enhance the designer's role in creating more informed design choices at an urban micro-scale. However, modelling the different components of the urban environment separately and then collating and comparing the results invariably leads to discrepancies in the output of local urban climate modelling tools designed to work at different scales. Of particular interest is why marked differences appear between the data extracted from local urban climate models when we change the scale of modelling from city to building scale. An example of such differences is those that have been observed in relation to the London Unified Model and London Site Specific Air Temperature model. In order to avoid these discrepancies we need a method for understanding and assessing how the urban environment impacts on local urban climate as a whole. A step to achieving this is by developing inter-linkages between assessment tools. Accurate information on the net impact of the urban environment on the local urban climate will in turn facilitate more accurate predictions of future energy demand and realistic scenarios for comfort and health. This paper will present two key topographies of London's urban environment that influence local urban climate: land use and street canyons. It will look at the possibilities for developing an integrated approach to modelling London's local urban climate from the neighbourhood to the street scale.

  11. How does local weather predict red deer home range size at different temporal scales?

    PubMed

    Rivrud, Inger Maren; Loe, Leif Egil; Mysterud, Atle

    2010-11-01

    1. There is a rapidly growing literature on how climate affects populations of vertebrates. For large herbivorous mammals, most attention has been paid to demographic responses to climate variation. Much less information is available regarding how climate affects animal behaviour, i.e. the climate mechanisms. Further, the appropriate measurement scale of climate variables remains debated. Here, we investigate how local climate variables determine home range sizes at four temporal scales using the Börger-method on GPS telemetry data from 47 female red deer Cervus elaphus L. in Norway. 2. If local climate operates directly on the immediate activity level of the animal, we predict home range sizes to show season-specific variation on short temporal scale (weekly-daily) related to temperature and precipitation. If local climate operate indirectly through plant growth, we rather predict variation in home range sizes to be apparent on longer time scales (biweekly-monthly), and during summer only. 3. At all time scales home range size was positively correlated with temperature during winter and negatively during summer, while the effect of precipitation was season- and scale-specific, except when accumulating as snow. Extensive snow cover decreased home range size, indicating direct effects of climate. 4. The effects of local climate was weaker at the shortest time scales (weekly-daily) compared to the longest time scales (monthly-biweekly), while the effects of day length on home range size was only apparent on the monthly and daily scale. At the longest time scales variation in local climate had a large effect on home range size. This is consistent with climatic variables operating indirectly through plant growth, but we cannot exclude a certain direct effect even at longer time scales. 5. We show how local climate-home range size correlations measured over different temporal scales can be used to infer direct and indirect climate mechanisms. Insight on the behavioural

  12. State Enabling Legislation for Commercial-Scale Wind Power Siting and the Local Government Role

    SciTech Connect

    McElfish, J.M.; Gersen, S.

    2011-05-31

    Siting of commercial-scale wind facilities (>5MW) is determined primarily by state laws. State laws either leave siting regulation to local governments, prescribe and constrain the role for local governments, establish state standards, or preempt local governance by having state institutions govern siting. Siting regulation is extremely important to the advancement of wind generation in the United States. Major siting decisions lie ahead for state and local governments as the nation diversifies its energy portfolio. An increase in the number of new wind facilities, siting in more locations and in more heavily populated areas, will require attention to the laws and regulations that govern siting. Local governments exercise some authority over commercial-scale wind facility siting in 48 of the 50 states. In 34 states, local governments have substantial autonomy to regulate the siting of most or all commercial-scale wind facilities. A few states authorize local governments to regulate wind facility siting, but make the scope of local regulation subject to limitations defined by state law. Eleven states set size thresholds for state regulatory involvement with local governments in these states regulating smaller facilities and state boards regulating larger ones (either exclusively or concurrently with local governments). In just under a third of the states, siting of most or all commercial-scale wind facilities requires approval by both state and local government bodies. Only a few states reserve the regulation of siting of all or virtually all commercial-scale wind facilities to state boards and commissions. The content of the applicable regulations is more important, in general, than the level of government responsible for the decision. Several states that assign siting responsibilities to local governments have specified some of the content and the limits of local regulation. About 1/5 of the states have directed boards and commissions to develop statewide

  13. Spatial scale of local breeding habitat quality and adjustment of breeding decisions.

    PubMed

    Doligez, Blandine; Berthouly, Anne; Doligez, Damien; Tanner, Marion; Saladin, Verena; Bonfils, Danielle; Richner, Heinz

    2008-05-01

    Experimental studies provide evidence that, in spatially and temporally heterogeneous environments, individuals track variation in breeding habitat quality to adjust breeding decisions to local conditions. However, most experiments consider environmental variation at one spatial scale only, while the ability to detect the influence of a factor depends on the scale of analysis. We show that different breeding decisions by adults are based on information about habitat quality at different spatial scales. We manipulated (increased or decreased) local breeding habitat quality through food availability and parasite prevalence at a small (territory) and a large (patch) scale simultaneously in a wild population of Great Tits (Parus major). Females laid earlier in high-quality large-scale patches, but laying date did not depend on small-scale territory quality. Conversely, offspring sex ratio was higher (i.e., biased toward males) in high-quality, small-scale territories but did not depend on large-scale patch quality. Clutch size and territory occupancy probability did not depend on our experimental manipulation of habitat quality, but territories located at the edge of patches were more likely to be occupied than central territories. These results suggest that integrating different decisions taken by breeders according to environmental variation at different spatial scales is required to understand patterns of breeding strategy adjustment.

  14. Efficient Calculations with Multisite Local Orbitals in a Large-Scale DFT Code CONQUEST.

    PubMed

    Nakata, Ayako; Bowler, David R; Miyazaki, Tsuyoshi

    2014-11-11

    Multisite local orbitals, which are formed from linear combinations of pseudoatomic orbitals from a target atom and its neighbor atoms, have been introduced in the large-scale density functional theory calculation code CONQUEST. Multisite local orbitals correspond to local molecular orbitals so that the number of required local orbitals can be minimal. The multisite support functions are determined by using the localized filter diagonalization (LFD) method [ Phys. Rev. B 2009 , 80 , 205104 ]. Two new methods, the double cutoff method and the smoothing method, are introduced to the LFD method to improve efficiency and stability. The Hamiltonian and overlap matrices with multisite local orbitals are constructed by efficient sparse-matrix multiplications in CONQUEST. The investigation of the calculated energetic and geometrical properties and band structures of bulk Si, Al, and DNA systems demonstrate the accuracy and the computational efficiency of the present method. The representability of both occupied and unoccupied band structures with the present method has been also confirmed.

  15. Scale-invariant hidden local symmetry, topology change, and dense baryonic matter

    NASA Astrophysics Data System (ADS)

    Paeng, Won-Gi; Kuo, Thomas T. S.; Lee, Hyun Kyu; Rho, Mannque

    2016-05-01

    When scale symmetry is implemented into hidden local symmetry in low-energy strong interactions to arrive at a scale-invariant hidden local symmetric (HLS) theory, the scalar f0(500 ) may be interpreted as pseudo-Nambu-Goldstone (pNG) boson, i.e., dilaton, of spontaneously broken scale invariance, joining the pseudoscalar pNG bosons π and the matter fields V =(ρ ,ω ) as relevant degrees of freedom. Implementing the skyrmion-half-skyrmion transition predicted at large Nc in QCD at a density roughly twice the nuclear matter density found in the crystal simulation of dense skyrmion matter, we determine the intrinsically density-dependent "bare parameters" of the scale-invariant HLS Lagrangian matched to QCD at a matching scale ΛM. The resulting effective Lagrangian, with the parameters scaling with the density of the system, is applied to nuclear matter and dense baryonic matter relevant to massive compact stars by means of the double-decimation renormalization-group Vlow k formalism. We satisfactorily postdict the properties of normal nuclear matter and more significantly predict the equation of state of dense compact-star matter that quantitatively accounts for the presently available data coming from both the terrestrial and space laboratories. We interpret the resulting structure of compact-star matter as revealing how the combination of hidden-scale symmetry and hidden local symmetry manifests itself in compressed baryonic matter.

  16. 3D active stabilization system with sub-micrometer resolution.

    PubMed

    Kursu, Olli; Tuukkanen, Tuomas; Rahkonen, Timo; Vähäsöyrinki, Mikko

    2012-01-01

    Stable positioning between a measurement probe and its target from sub- to few micrometer scales has become a prerequisite in precision metrology and in cellular level measurements from biological tissues. Here we present a 3D stabilization system based on an optoelectronic displacement sensor and custom piezo-actuators driven by a feedback control loop that constantly aims to zero the relative movement between the sensor and the target. We used simulations and prototyping to characterize the developed system. Our results show that 95% attenuation of movement artifacts is achieved at 1 Hz with stabilization performance declining to ca. 70% attenuation at 10 Hz. Stabilization bandwidth is limited by mechanical resonances within the displacement sensor that occur at relatively low frequencies, and are attributable to the sensor's high force sensitivity. We successfully used brain derived micromotion trajectories as a demonstration of complex movement stabilization. The micromotion was reduced to a level of ∼1 µm with nearly 100 fold attenuation at the lower frequencies that are typically associated with physiological processes. These results, and possible improvements of the system, are discussed with a focus on possible ways to increase the sensor's force sensitivity without compromising overall system bandwidth.

  17. 3D Active Stabilization System with Sub-Micrometer Resolution

    PubMed Central

    Rahkonen, Timo; Vähäsöyrinki, Mikko

    2012-01-01

    Stable positioning between a measurement probe and its target from sub- to few micrometer scales has become a prerequisite in precision metrology and in cellular level measurements from biological tissues. Here we present a 3D stabilization system based on an optoelectronic displacement sensor and custom piezo-actuators driven by a feedback control loop that constantly aims to zero the relative movement between the sensor and the target. We used simulations and prototyping to characterize the developed system. Our results show that 95 % attenuation of movement artifacts is achieved at 1 Hz with stabilization performance declining to ca. 70 % attenuation at 10 Hz. Stabilization bandwidth is limited by mechanical resonances within the displacement sensor that occur at relatively low frequencies, and are attributable to the sensor's high force sensitivity. We successfully used brain derived micromotion trajectories as a demonstration of complex movement stabilization. The micromotion was reduced to a level of ∼1 µm with nearly 100 fold attenuation at the lower frequencies that are typically associated with physiological processes. These results, and possible improvements of the system, are discussed with a focus on possible ways to increase the sensor's force sensitivity without compromising overall system bandwidth. PMID:22900045

  18. Adhesion hysteresis and friction at nanometer and micrometer lengths

    SciTech Connect

    Szoszkiewicz, Robert; Bhushan, Bharat; Huey, Bryan D.; Kulik, Andrzej J.; Gremaud, Gerard

    2006-01-01

    Comparisons between adhesion hysteresis and friction at nanometer and micrometer length scales were investigated experimentally and theoretically. Nanoscale adhesion hysteresis was measured using the ultrasonic force microscopy (UFM) on mica, calcite, and a few metallic samples (Pt, Au, Cu, Zn, Ti, and Fe). Obtained adhesion hysteresis ranged between 4x10{sup -19} and 4x10{sup -18} J. At the microscale a similar setup with a nanoindenter was used and the same samples were investigated. Adhesion hysteresis measured at the microscale ranged between 8x10{sup -17} and 14x10{sup -17} J. Friction was investigated via lateral force microscopy, as well as by scratch tests done with the nanoindenter. Numerical simulations based on the UFM model as well as established theories of contact mechanics studied qualitative dependencies of adhesion hysteresis on experimental parameters. Quantitative relations between adhesion hysteresis and friction were obtained through an analytic model relying on elastic and adhesive properties of the contact. The model agreed with measurements and simulations.

  19. Thermal Analysis of Unusual Local-scale Features on the Surface of Vesta

    NASA Technical Reports Server (NTRS)

    Tosi, F.; Capria, M. T.; DeSanctis, M. C.; Capaccioni, F.; Palomba, E.; Zambon, F.; Ammannito, E.; Blewett, D. T.; Combe, J.-Ph.; Denevi, B. W.; Li, J.-Y.; Mittlefehldt, D. W.; Palmer, E.; Sunshine, J. M.; Titus, T. N.; Raymond, C. A.; Russell, C. T.

    2013-01-01

    At 525 km in mean diameter, Vesta is the second-most massive object in the main asteroid belt of our Solar System. At all scales, pyroxene absorptions are the most prominent spectral features on Vesta and overall, Vesta mineralogy indicates a complex magmatic evolution that led to a differentiated crust and mantle [1]. The thermal behavior of areas of unusual albedo seen on the surface at the local scale can be related to physical properties that can provide information about the origin of those materials. Dawn's Visible and Infrared Mapping Spectrometer (VIR) [2] hyperspectral images are routinely used, by means of temperature-retrieval algorithms, to compute surface temperatures along with spectral emissivities. Here we present temperature maps of several local-scale features of Vesta that were observed by Dawn under different illumination conditions and different local solar times.

  20. Dry Sliding Behavior of Sub-Micrometer-Sized Suspension Plasma Sprayed Ceramic Oxide Coatings

    NASA Astrophysics Data System (ADS)

    Darut, Geoffrey; Ben-Ettouil, Fadhel; Denoirjean, Alain; Montavon, Ghislain; Ageorges, Hélène; Fauchais, Pierre

    2010-01-01

    Almost half of the energy produced by an automotive engine is dissipated by friction in the cylinders, the clutch, etc. In the context of reduction of the emissions of greenhouse gases (GHGs) to mitigate climate global warming (CGW), reduction of energy losses due to friction is a critical issue. Surface treatments appear in such a context, as never than before, to be able to provide pertinent solutions to improve sliding behavior of mechanical parts. Numerous studies have clearly shown that decreasing the scale of coating structure below the micrometer scale was leading to an improvement of its tribological behavior in terms of friction coefficient and wear rate thanks to improved mechanical properties, the toughness in particular. Suspension Plasma Spraying (SPS) appears as a thermal spray process to be able to manufacture thick (i.e., a few tens of micrometers) coatings exhibiting a sub-micrometer-sized or even a nanometer-sized architecture, while keeping the versatility and flexibility of the thermal spray routes: i.e., the ability to process a wide range of material natures onto a wide range of substrate materials of various geometries. This article aims at studying the tribological behavior of several ceramic oxide composite coatings under dry conditions. The structural scale and the effect of composition are considered in particular.

  1. Multi-Scale Fusion for Improved Localization of Malicious Tampering in Digital Images.

    PubMed

    Korus, Paweł; Huang, Jiwu

    2016-03-01

    A sliding window-based analysis is a prevailing mechanism for tampering localization in passive image authentication. It uses existing forensic detectors, originally designed for a full-frame analysis, to obtain the detection scores for individual image regions. One of the main problems with a window-based analysis is its impractically low localization resolution stemming from the need to use relatively large analysis windows. While decreasing the window size can improve the localization resolution, the classification results tend to become unreliable due to insufficient statistics about the relevant forensic features. In this paper, we investigate a multi-scale analysis approach that fuses multiple candidate tampering maps, resulting from the analysis with different windows, to obtain a single, more reliable tampering map with better localization resolution. We propose three different techniques for multi-scale fusion, and verify their feasibility against various reference strategies. We consider a popular tampering scenario with mode-based first digit features to distinguish between singly and doubly compressed regions. Our results clearly indicate that the proposed fusion strategies can successfully combine the benefits of small-scale and large-scale analyses and improve the tampering localization performance.

  2. Semi-local scaling exponent estimation with box-penalty constraints and total-variation regularisation.

    PubMed

    Nelson, James; Nafornita, Corina; Isar, Alexandru

    2016-04-06

    We here establish and exploit the result that 2-D isotropic self-similar fields beget quasi-decorrelated wavelet coefficients and that the resulting localised log sample second moment statistic is asymptotically normal. This leads to the development of a semi-local scaling exponent estimation framework with optimally modified weights. Furthermore, recent interest in penalty methods for least squares problems and generalised Lasso for scaling exponent estimation inspires the simultaneous incorporation of both bounding box constraints and total variation smoothing into an iteratively reweighted leastsquares estimator framework. Numerical results on fractional Brownian fields with global and piecewise constant, semi-local Hurst parameters illustrate the benefits of the new estimators.

  3. The cold land processes experiment (CLPX) local scale observatin site (LSOS)

    NASA Technical Reports Server (NTRS)

    McDonald, K. C.; Hardy, J. P.; Cline, D.; Elder, K.; Davis, R.; Pomeroy, J.; Koh, G.; Armstrong, R.; Koike, T.

    2002-01-01

    The Local Scale Observation Site (LSOS) is the smallest study site of the Cold LandProcesses Experiment (CLPX) and is located within the Fraser Meso-cell Study Area (MSA), near the Fraser Experimental Forest Headquarters Facility, in Fraser, CO USA.The 100-m x 100-m site consists of a small open field, a managed dense canopy and an open, mixed age canopy. Unlike the other components of the experiment, which focus on spatial distributions at relatively brief snapshots in time, measurements at the local scale site focused on the temporal domain.

  4. The cold land processes experiment (CLPX) local scale observatin site (LSOS)

    NASA Technical Reports Server (NTRS)

    McDonald, K. C.; Hardy, J. P.; Cline, D.; Elder, K.; Davis, R.; Pomeroy, J.; Koh, G.; Armstrong, R.; Koike, T.

    2002-01-01

    The Local Scale Observation Site (LSOS) is the smallest study site of the Cold LandProcesses Experiment (CLPX) and is located within the Fraser Meso-cell Study Area (MSA), near the Fraser Experimental Forest Headquarters Facility, in Fraser, CO USA.The 100-m x 100-m site consists of a small open field, a managed dense canopy and an open, mixed age canopy. Unlike the other components of the experiment, which focus on spatial distributions at relatively brief snapshots in time, measurements at the local scale site focused on the temporal domain.

  5. Local- to Basin-scale Snow Distributions for the Cold Land Processes Experiment (CLPX)

    NASA Astrophysics Data System (ADS)

    Liston, G. E.; Hiemstra, C. A.; Elder, K.; Cline, D.

    2006-12-01

    A snow evolution modeling system (SnowModel) was used to simulate seasonal snow evolution across three, 30-km by 30-km, simulation domains that included the Cold Land Processes Field Experiment (CLPX) meso- cell study areas (MSAs) in Colorado, U.S.A. The three MSAs have distinctly different topography, vegetation, meteorological, and snow-related characteristics. Simulations were performed using a 30-m grid increment and a 3-hour time step, and spanned the snow accumulation season for this region (1 October 2002 through 1 April 2003). Meteorological forcing was provided by 27 meteorological stations and 75 atmospheric analyses grid-points distributed across the model simulation domains using a micrometeorological distribution model (MicroMet). The simulations included a data assimilation sub-model (SnowAssim) that adjusted the simulated snow water equivalent (SWE) toward a collection of ground-based and airborne SWE observations. The observations consisted of area-averaged SWE over three, 1-km by 1-km intensive study areas (ISAs) for each MSA, and a collection of airborne observations that each integrated an area covering a length of approximately 10 km and a width of 300 m. Simulated SWE distributions displayed considerably more spatial variability than possible from observations, and general distribution patterns simulated by the model were considerably more realistic. This is the result of SnowModel's relatively fine-scale representations of orographic precipitation, low- elevation melt, wind redistribution (snow drifts above treeline), and snow-vegetation interactions. The combined modeling and data assimilation system produced high-resolution SWE distributions that closely fit our understanding of snow evolution processes and observed snow depths.

  6. Comparative Study of Local Magnitude Scales for Central U.S. and Western India

    NASA Astrophysics Data System (ADS)

    Miao, Q.; Langston, C. A.

    2004-12-01

    Seismic waveform data from 816 aftershocks of 2001 Bhuj Mw 7.7 earthquake, recorded by CERI/STAR aftershock deployment, including eight K2 6-channel dataloggers with 3-component episensor accelerometers and 3-component L-28 geophones, were used to develop a local magnitude scale for Kachchh basin of western India. Results show that the distance correction curve can be expressed as -logA0=1.8286*(r/100.0)-0.0052*(r-100.0)+3.0, displaying weak distance attenuation. This result is much like that of the local magnitude scale for the Central U.S. Both scales show weak distance attenuation, compared with the local magnitude scales for southern California or Tanzania, East Africa, and display a negative K parameter, implying similar patterns of seismic wave spreading in these two regions. These results for local magnitude scales give support to the assertion that the Kachchh basin and New Madrid Seismic Zone are geological analogs inasmuch that ground motion and other seismological results from one area can shed light on similar problems in the other area.

  7. Plant species coexistence at local scale in temperate swamp forest: test of habitat heterogeneity hypothesis.

    PubMed

    Douda, Jan; Doudová-Kochánková, Jana; Boublík, Karel; Drašnarová, Alena

    2012-06-01

    It has been suggested that a heterogeneous environment enhances species richness and allows for the coexistence of species. However, there is increasing evidence that environmental heterogeneity can have no effect or even a negative effect on plant species richness and plant coexistence at a local scale. We examined whether plant species richness increases with local heterogeneity in the water table depth, microtopography, pH and light availability in a swamp forest community at three local spatial scales (grain: 0.6, 1.2 and 11.4 m). We also used the variance partitioning approach to assess the relative contributions of niche-based and other spatial processes to species occurrence. We found that heterogeneity in microtopography and light availability positively correlated with species richness, in accordance with the habitat heterogeneity hypothesis. However, we recorded different heterogeneity-diversity relationships for particular functional species groups. An increase in the richness of bryophytes and woody plant species was generally related to habitat heterogeneity at all measured spatial scales, whereas a low impact on herbaceous species richness was recorded only at the 11.4 m scale. The distribution of herbaceous plants was primarily explained by other spatial processes, such as dispersal, in contrast to the occurrence of bryophytes, which was better explained by environmental factors. Our results suggest that both niche-based and other spatial processes are important determinants of the plant composition and species turnover at local spatial scales in swamp forests.

  8. WaterWorld, a spatial hydrological model applied at scales from local to global: key challenges to local application

    NASA Astrophysics Data System (ADS)

    Burke, Sophia; Mulligan, Mark

    2017-04-01

    WaterWorld is a widely used spatial hydrological policy support system. The last user census indicates regular use by 1029 institutions across 141 countries. A key feature of WaterWorld since 2001 is that it comes pre-loaded with all of the required data for simulation anywhere in the world at a 1km or 1 ha resolution. This means that it can be easily used, without specialist technical ability, to examine baseline hydrology and the impacts of scenarios for change or management interventions to support policy formulation, hence its labelling as a policy support system. WaterWorld is parameterised by an extensive global gridded database of more than 600 variables, developed from many sources, since 1998, the so-called simTerra database. All of these data are available globally at 1km resolution and some variables (terrain, land cover, urban areas, water bodies) are available globally at 1ha resolution. If users have access to better data than is pre-loaded, they can upload their own data. WaterWorld is generally applied at the national or basin scale at 1km resolution, or locally (for areas of <10,000km2) at 1ha resolution, though continental (1km resolution) and global (10km resolution) applications are possible so it is a model with local to global applications. WaterWorld requires some 140 maps to run including monthly climate data, land cover and use, terrain, population, water bodies and more. Whilst publically-available terrain and land cover data are now well developed for local scale application, climate and land use data remain a challenge, with most global products being available at 1km or 10km resolution or worse, which is rather coarse for local application. As part of the EartH2Observe project we have used WFDEI (WATCH Forcing Data methodology applied to ERA-Interim data) at 1km resolution to provide an alternative input to WaterWorld's preloaded climate data. Here we examine the impacts of that on key hydrological outputs: water balance, water quality

  9. Comparison of 8 to 12 Micrometer and 3 to 5 Micrometer CVF Transmissometer Data with LOWTRAN Calculations.

    DTIC Science & Technology

    1984-06-26

    STANDARS -963-A " .:- A 9 ..A . . . . . . ". . _’.". ". . . - - ’. - . . - . - . - " ,, . - . , .,,-’ . . - . ,.X...Micrometer and 3 to 5 Micrometer CVF Transmissometer Data With LOWTRAN Calculations F. X. KNEIZYS W. 0. GALLERY R. R. GRUENZEL S. A. CLOUGH W. C. MARTIN J. H...Facility, Wright-Patterson Air Force Base, Ohio with a circular variable filter ((’VI) transmissometer. The data cover the spectral regions from 8- to

  10. Accessible, interactive visualizations of climate change data from local to national scale

    NASA Astrophysics Data System (ADS)

    Battaile, B.; Rao, M.

    2016-12-01

    Weather information has wide appeal across a range of scales, from the local scale (e.g., historical highs and lows for a city) to the national or global (e.g., national weather maps). The public discussion of climate change can benefit from building on this appeal, through presentation of the abundantly available historical weather records. Visualizations of temporal patterns in these records at large scales can show climate trends already in progress; the appeal and relevance of these visualizations can be enhanced by linking them to detailed information on local weather history. We are developing a web site with interactive maps of weather trends for the contiguous US, based on GHCN (Global Historical Climatology Network) data. There are over 6000 GHCN stations in the contiguous US with records spanning at least 40 years, and 2000 with records over a century. With this rich data set we enable users to visualize large scale trends and also to explore the underlying local data and its connection to the larger context. We provide visualizations for a wide variety of trends, using metrics such as days above 95F, annual number of record-setting days, peak temperatures, and number of days annually above historical mean. Users can query points on the map to get a graphical analysis of the trend at local stations, thus linking local observations with national trends. We hope that interactive maps such as these, which allow exploration of local trends within the context of national or global trends, and which are based on local observations, will encourage informed engagement with climate change issues.

  11. Local scale structures in Earth's thermospheric winds and their consequences for wind driven transport

    NASA Astrophysics Data System (ADS)

    Dhadly, Manbharat Singh

    In the traditional picture of Earth's upper thermosphere (~190--300 km), it is widely presumed that its convective stability and enormous kinematic viscosity attenuate wind gradients, and hence smooth out any structure present in the wind over scale size of several hundreds of kilometers. However, several independent experimental studies have shown that observed upper thermospheric wind fields at high latitudes contain stronger than expected local-scale spatial structures. The motivation of this dissertation is to investigate how the resulting local-scale gradients would distort neutral air masses and complicate thermospheric wind transport. To achieve this goal, we examined the behavior of a simple parameter that we refer to as the "distortion gradient". It incorporates all of the wind field's departures from uniformity, and is thus capable of representing all resulting contributions to the distortion or mixing of air masses. Climatological analysis of the distortion gradient using 2010, 2011, and 2012 wind data from the All-sky Scanning Doppler Imager (SDI) located at Poker Flat (65.12N, 147.47W) revealed the diurnal and seasonal trends in distortion of thermospheric masses. Distortion was observed to be dependent on geomagnetic activity and orientation of the interplanetary magnetic field. To understand the time-cumulative influence of these local-scale non-uniformities on thermospheric wind driven transport, time-resolved two-dimensional maps of the thermospheric vector wind fields were used to infer forward and backward air parcel trajectories. Tracing air parcel trajectories through a given geographic location indicates where they came from previously, and where they will go in the future. Results show that wind driven transport is very sensitive to small-scale details of the wind field. Any local-scale spatial wind gradients can significantly complicate air parcel trajectories. Transport of thermospheric neutral species in the presence of the local-scale

  12. Radially dependent large-scale dynamos in global cylindrical shear flows and the local cartesian limit

    NASA Astrophysics Data System (ADS)

    Ebrahimi, F.; Blackman, E. G.

    2016-06-01

    For cylindrical differentially rotating plasmas, we study large-scale magnetic field generation from finite amplitude non-axisymmetric perturbations by comparing numerical simulations with quasi-linear analytic theory. When initiated with a vertical magnetic field of either zero or finite net flux, our global cylindrical simulations exhibit the magnetorotational instability (MRI) and large-scale dynamo growth of radially alternating mean fields, averaged over height and azimuth. This dynamo growth is explained by our analytic calculations of a non-axisymmetric fluctuation-induced electromotive force that is sustained by azimuthal shear of the fluctuating fields. The standard `Ω effect' (shear of the mean field by differential rotation) is unimportant. For the MRI case, we express the large-scale dynamo field as a function of differential rotation. The resulting radially alternating large-scale fields may have implications for angular momentum transport in discs and corona. To connect with previous work on large-scale dynamos with local linear shear and identify the minimum conditions needed for large-scale field growth, we also solve our equations in local Cartesian coordinates. We find that large-scale dynamo growth in a linear shear flow without rotation can be sustained by shear plus non-axisymmetric fluctuations - even if not helical, a seemingly previously unidentified distinction. The linear shear flow dynamo emerges as a more restricted version of our more general new global cylindrical calculations.

  13. Examples of scale interactions in local, urban, and regional air quality modelling

    NASA Astrophysics Data System (ADS)

    Mensink, C.; De Ridder, K.; Deutsch, F.; Lefebre, F.; Van de Vel, K.

    2008-09-01

    Air quality modeling can help to improve understanding of scale interactions related to meteorology, transport, emissions, formation, removal, and other processes taking place at local, urban, and regional scales. For the local scale, we used the coupling of a street canyon model with a Gaussian dispersion model to study the interactions of emissions and concentrations in urban streets and surrounding urban neighborhoods. The model combination was applied to a city quarter in Ghent, Belgium, and showed that up to 40% of the PM 2.5 concentrations inside street canyons were caused by emissions from the surrounding streets. For the urban scale, the AURORA model has been used successfully in assessments of urban air quality for entire cities or urbanized areas. It has been applied to the Ruhr area in Germany to evaluate the impact of compact or polycentric cities versus the impact of urban sprawl developments. Results for ozone and PM 10 showed that compact city structures may have more adverse effects in terms of air pollution exposure. For the regional scale, the EUROS model was used to study the urban and regional-scale interactions that are important in simulating concentrations of ozone, PM 2.5, and PM 10. It has been applied to study seasonal changes in aerosol concentrations in Flanders. High secondary aerosol concentrations were found during summer. This contribution was related to large contributions from outside the region, showing the importance of the continental scale when studying regional air quality problems.

  14. Scaling local species-habitat relations to the larger landscape with a hierarchical spatial count model

    USGS Publications Warehouse

    Thogmartin, W.E.; Knutson, M.G.

    2007-01-01

    Much of what is known about avian species-habitat relations has been derived from studies of birds at local scales. It is entirely unclear whether the relations observed at these scales translate to the larger landscape in a predictable linear fashion. We derived habitat models and mapped predicted abundances for three forest bird species of eastern North America using bird counts, environmental variables, and hierarchical models applied at three spatial scales. Our purpose was to understand habitat associations at multiple spatial scales and create predictive abundance maps for purposes of conservation planning at a landscape scale given the constraint that the variables used in this exercise were derived from local-level studies. Our models indicated a substantial influence of landscape context for all species, many of which were counter to reported associations at finer spatial extents. We found land cover composition provided the greatest contribution to the relative explained variance in counts for all three species; spatial structure was second in importance. No single spatial scale dominated any model, indicating that these species are responding to factors at multiple spatial scales. For purposes of conservation planning, areas of predicted high abundance should be investigated to evaluate the conservation potential of the landscape in their general vicinity. In addition, the models and spatial patterns of abundance among species suggest locations where conservation actions may benefit more than one species. ?? 2006 Springer Science+Business Media B.V.

  15. Classification of local- and landscape-scale ecological types in the Southern Appalachian mountains

    SciTech Connect

    McNab, W.H.

    1996-12-31

    Five local ecological types based on vegetative communities and two landscape types based on groups of communities, were identified by integrating landform, soil, and vegetation components using multivariate techniques. Evaluation and several topographic and soil variables were highly correlated with types of both scales. Landscape ecological types based only on landform and soil variables without vegetation did not correspond with types developed using vegetation.

  16. Influence of Global Shapes on Children's Coding of Local Geometric Information in Small-Scale Spaces

    ERIC Educational Resources Information Center

    Chiang, Noelle C.

    2013-01-01

    This research uses enclosed whole shapes, rather than visual form fragments, to demonstrate that children's use of local geometric information is influenced by global shapes in small-scale spaces. Three- to six-year-old children and adults participated in two experiments with a table-top task. In Experiment 1, participants were presented with a…

  17. Influence of Global Shapes on Children's Coding of Local Geometric Information in Small-Scale Spaces

    ERIC Educational Resources Information Center

    Chiang, Noelle C.

    2013-01-01

    This research uses enclosed whole shapes, rather than visual form fragments, to demonstrate that children's use of local geometric information is influenced by global shapes in small-scale spaces. Three- to six-year-old children and adults participated in two experiments with a table-top task. In Experiment 1, participants were presented with a…

  18. Education Hubs: International, Regional and Local Dimensions of Scale and Scope

    ERIC Educational Resources Information Center

    Knight, Jane

    2013-01-01

    Education hubs are important new developments. They represent a new generation of cross-border education activities where critical mass, co-location and connection between international, regional and local universities, students, research institutes and private industry are key. Different scales (city, zone and country) and types (student, talent,…

  19. Local adaptation in Trinidadian guppies alters stream ecosystem structure at landscape scales despite high environmental variability

    USGS Publications Warehouse

    Simon, Troy N.; Bassar, Ronald D.; Binderup, Andrew J.; Flecker, Alex S.; Freeman, Mary C.; Gilliam, James F.; Marshall, Michael C.; Thomas, Steve A.; Travis, Joseph; Reznick, David N.; Pringle, Catherine M.

    2017-01-01

    While previous studies have shown that evolutionary divergence alters ecological processes in small-scale experiments, a major challenge is to assess whether such evolutionary effects are important in natural ecosystems at larger spatial scales. At the landscape scale, across eight streams in the Caroni drainage, we found that the presence of locally adapted populations of guppies (Poecilia reticulata) is associated with reduced algal biomass and increased invertebrate biomass, while the opposite trends were true in streams with experimentally introduced populations of non-locally adapted guppies. Exclusion experiments conducted in two separate reaches of a single stream showed that guppies with locally adapted phenotypes significantly reduced algae with no effect on invertebrates, while non-adapted guppies had no effect on algae but significantly reduced invertebrates. These divergent effects of phenotype on stream ecosystems are comparable in strength to the effects of abiotic factors (e.g., light) known to be important drivers of ecosystem condition. They also corroborate the results of previous experiments conducted in artificial streams. Our results demonstrate that local adaptation can produce phenotypes with significantly different effects in natural ecosystems at a landscape scale, within a tropical watershed, despite high variability in abiotic factors: five of the seven physical and chemical parameters measured across the eight study streams varied by more than one order of magnitude. Our findings suggest that ecosystem structure is, in part, an evolutionary product and not simply an ecological pattern.

  20. Parallel and Low-Order Scaling Implementation of Hartree-Fock Exchange Using Local Density Fitting.

    PubMed

    Köppl, Christoph; Werner, Hans-Joachim

    2016-07-12

    Calculations using modern linear-scaling electron-correlation methods are often much faster than the necessary reference Hartree-Fock (HF) calculations. We report a newly implemented HF program that speeds up the most time-consuming step, namely, the evaluation of the exchange contributions to the Fock matrix. Using localized orbitals and their sparsity, local density fitting (LDF), and atomic orbital domains, we demonstrate that the calculation of the exchange matrix scales asymptotically linearly with molecular size. The remaining parts of the HF calculation scale cubically but become dominant only for very large molecular sizes or with many processing cores. The method is well parallelized, and the speedup scales well with up to about 100 CPU cores on multiple compute nodes. The effect of the local approximations on the accuracy of computed HF and local second-order Møller-Plesset perturbation theory energies is systematically investigated, and default values are established for the parameters that determine the domain sizes. Using these values, calculations for molecules with hundreds of atoms in combination with triple-ζ basis sets can be carried out in less than 1 h, with just a few compute nodes. The method can also be used to speed up density functional theory calculations with hybrid functionals that contain HF exchange.

  1. Frequency-Dependent Local Magnitude Scales for the Central U.S.

    NASA Astrophysics Data System (ADS)

    Miao, Q.; Langston, C. A.

    2005-12-01

    Frequency-dependent local magnitude scales were developed for the study of seismic wave propagation and attenuation with frequency in the central U.S. within 600 km distance from the source. This is done by empirically modeling narrow frequency band filtered ground motion data from the CERI Cooperative Network and the United States National Seismograph Network (USNSN) to derive source size (local magnitude) and distance attenuation relationships for seismic wave propagation. The frequencies selected for this study are between 0.1 and 10.0 Hz. The obtained distance-correction functions show that the propagation of seismic waves at frequencies below 1.0 Hz do not attenuation with distance. Results show that the currently used MD scale may measure a narrow frequency band of seismic waves, while ML scale measures a relatively wide frequency band, which explained the differences between the MD and ML values in the central U.S.

  2. On the Locality and Scaling of Overlap Fermions at Coarse Lattice Spacings

    SciTech Connect

    Terrence Draper; Nilmani Mathur; Jianbo Zhang; Andrei Alexandru; Ying Chen; Shao-Jing Dong; Ivan Horvath; Frank X. Lee; Keh-Fei Liu; Sonali Tamhankar

    2006-11-07

    The overlap fermion offers the considerable advantage of exact chiral symmetry on the lattice, but is numerically intensive. This can be made affordable while still providing large lattice volumes, by using coarse lattice spacing, given that good scaling and localization properties are established. Here, using overlap fermions on quenched Iwasaki gauge configurations, we demonstrate directly that, with appropriate choice of negative Wilson's mass, the overlap Dirac operator's range is comfortably small in lattice units for each of the lattice spacings 0.20 fm, 0.17 fm, and 0.13 fm (and scales to zero in physical units in the continuum limit). In particular, our direct results contradict recent speculation that an inverse lattice spacing of 1 GeV is too low to have satisfactory localization. Furthermore, hadronic masses (available on the two coarser lattices) scale very well.

  3. Linear-scaling evaluation of the local energy in quantum MonteCarlo

    SciTech Connect

    Austin, Brian; Aspuru-Guzik, Alan; Salomon-Ferrer, Romelia; Lester Jr., William A.

    2006-02-11

    For atomic and molecular quantum Monte Carlo calculations, most of the computational effort is spent in the evaluation of the local energy. We describe a scheme for reducing the computational cost of the evaluation of the Slater determinants and correlation function for the correlated molecular orbital (CMO) ansatz. A sparse representation of the Slater determinants makes possible efficient evaluation of molecular orbitals. A modification to the scaled distance function facilitates a linear scaling implementation of the Schmidt-Moskowitz-Boys-Handy (SMBH) correlation function that preserves the efficient matrix multiplication structure of the SMBH function. For the evaluation of the local energy, these two methods lead to asymptotic linear scaling with respect to the molecule size.

  4. Does remote sensing help translating local SGD investigation to large spatial scales?

    NASA Astrophysics Data System (ADS)

    Moosdorf, N.; Mallast, U.; Hennig, H.; Schubert, M.; Knoeller, K.; Neehaul, Y.

    2016-02-01

    Within the last 20 years, studies on submarine groundwater discharge (SGD) have revealed numerous processes, temporal behavior and quantitative estimations as well as best-practice and localization methods. This plethora on information is valuable regarding the understanding of magnitude and effects of SGD for the respective location. Yet, since given local conditions vary, the translation of local understanding, magnitudes and effects to a regional or global scale is not trivial. In contrast, modeling approaches (e.g. 228Ra budget) tackling SGD on a global scale do provide quantitative global estimates but have not been related to local investigations. This gap between the two approaches, local and global, and the combination and/or translation of either one to the other represents one of the mayor challenges the SGD community currently faces. But what if remote sensing can provide certain information that may be used as translation between the two, similar to transfer functions in many other disciplines allowing an extrapolation from in-situ investigated and quantified SGD (discrete information) to regional scales or beyond? Admittedly, the sketched future is ambitious and we will certainly not be able to present a solution to the raised question. Nonetheless, we will show a remote sensing based approach that is already able to identify potential SGD sites independent on location or hydrogeological conditions. Based on multi-temporal thermal information of the water surface as core of the approach, SGD influenced sites display a smaller thermal variation (thermal anomalies) than surrounding uninfluenced areas. Despite the apparent simplicity, the automatized approach has helped to localize several sites that could be validated with proven in-situ methods. At the same time it embodies the risk to identify false positives that can only be avoided if we can `calibrate' the so obtained thermal anomalies to in-situ data. We will present all pros and cons of our

  5. Quantifying local heterogeneity via morphologic scale: Distinguishing tumoral from stromal regions

    PubMed Central

    Janowczyk, Andrew; Chandran, Sharat; Madabhushi, Anant

    2013-01-01

    Introduction: The notion of local scale was introduced to characterize varying levels of image detail so that localized image processing tasks could be performed while simultaneously yielding a globally optimal result. In this paper, we have presented the methodological framework for a novel locally adaptive scale definition, morphologic scale (MS), which is different from extant local scale definitions in that it attempts to characterize local heterogeneity as opposed to local homogeneity. Methods: At every point of interest, the MS is determined as a series of radial paths extending outward in the direction of least resistance, navigating around obstructions. Each pixel can then be directly compared to other points of interest via a rotationally invariant quantitative feature descriptor, determined by the application of Fourier descriptors to the collection of these paths. Results: Our goal is to distinguish tumor and stromal tissue classes in the context of four different digitized pathology datasets: prostate tissue microarrays (TMAs) stained with hematoxylin and eosin (HE) (44 images) and TMAs stained with only hematoxylin (H) (44 images), slide mounts of ovarian H (60 images), and HE breast cancer (51 images) histology images. Classification performance over 50 cross-validation runs using a Bayesian classifier produced mean areas under the curve of 0.88 ± 0.01 (prostate HE), 0.87 ± 0.02 (prostate H), 0.88 ± 0.01 (ovarian H), and 0.80 ± 0.01 (breast HE). Conclusion: For each dataset listed in Table 3, we randomly selected 100 points per image, and using the procedure described in Experiment 1, we attempted to separate them as belonging to stroma or epithelium. PMID:23766944

  6. Link between local scale BC emissions in the Indo-Gangetic Plains and large scale atmospheric solar absorption

    NASA Astrophysics Data System (ADS)

    Praveen, P. S.; Ahmed, T.; Kar, A.; Rehman, I. H.; Ramanathan, V.

    2012-01-01

    Project Surya has documented indoor and outdoor concentrations of black carbon (BC) from traditional biomass burning cook stoves in a rural village located in the Indo-Gangetic Plains (IGP) region of N. India from November 2009-September 2010. In this paper, we systematically document the link between local scale aerosol properties and column averaged regional aerosol optical properties and atmospheric radiative forcing. We document observations from the first phase of Project Surya and estimate the source dependent (biomass and fossil fuels) aerosol optical properties from local to regional scale. Data were collected using surface based observations of BC, organic carbon (OC), aerosol light absorption, scattering coefficient at the Surya village (SVI_1) located in IGP region and integrated with satellite and AERONET observations at the regional scale (IGP). The daily mean BC concentrations at SVI1 showed a large increase of BC during the dry season (December to February) with values reaching 35 μg m-3. Space based LIDAR data revealed how the biomass smoke was trapped within the first kilometer during the dry season and extended to above 5 km during the pre-monsoon season. As a result, during the dry season, the variance in the daily mean single scattering albedo (SSA), the ratio of scattering to extinction coefficient, and column aerosol optical properties at the local IGP site correlated (with slopes in the range of 0.85 to 1.06 and R2>0.4) well with the "IGP_AERONET" (mean of six AERONET sites). The statistically significant correlation suggested that in-situ observations can be used to derive spatial mean forcing, at least for the dry season. The atmospheric forcing due to BC and OC exceeded 20 Wm-2 during all months from November to May, supporting the deduction that elimination of cook stove smoke emissions through clean cooking technologies will likely have a major positive impact not only on human health but also on regional climate.

  7. Zooplankton and forage fish species off Peru: Large-scale bottom-up forcing and local-scale depletion

    NASA Astrophysics Data System (ADS)

    Ayón, Patricia; Swartzman, Gordon; Bertrand, Arnaud; Gutiérrez, Mariano; Bertrand, Sophie

    2008-10-01

    The Humboldt Current System, like all upwelling systems, has dramatic quantities of plankton-feeding fish, which suggested that their population dynamics may ‘drive’ or ‘control’ ecosystem dynamics. With this in mind we analysed the relationship between forage fish populations and their main prey, zooplankton populations. Our study combined a zooplankton sampling program (1961-2005) with simultaneous acoustic observations on fish from 40 pelagic surveys (1983-2005) conducted by the Peruvian Marine Research Institute (IMARPE) and landing statistics for anchoveta ( Engraulis ringens) and sardine ( Sardinops sagax) along the Peruvian coast from 1961 to 2005. The multi-year trend of anchoveta population abundance varied consistently with zooplankton biovolume trend, suggesting bottom-up control on anchovy at the population scale (since oceanographic conditions and phytoplankton production support the changes in zooplankton abundance). For a finer-scale analysis (km) we statistically modelled zooplankton biovolume as a function of geographical (latitude and distance from the 200-m isobath), environmental (sea surface temperature), temporal (year, month and time-of-day) and biological (acoustic anchovy and sardine biomass within 5 km of each zooplankton sample) covariates over all survey using both classification and regression trees (CART) and generalized additive models (GAM). CART showed local anchoveta density to have the strongest effect on zooplankton biovolume, with significantly reduced levels of biovolume for higher neighbourhood anchoveta biomass. Additionally, zooplankton biovolume was higher offshore than on the shelf. GAM results corroborated the CART findings, also showing a clear diel effect on zooplankton biovolume, probably due to diel migration or daytime net avoidance. Apparently, the observed multi-year population scale bottom-up control is not inconsistent with local depletion of zooplankton when anchoveta are locally abundant, since the

  8. Localized structure of Euglena bioconvection

    NASA Astrophysics Data System (ADS)

    Iima, Makoto; Shoji, Erika; Awazu, Akinori; Nishimori, Hiraku; Izumi, Shunsuke; Hiroshima University Collaboration

    2013-11-01

    Bioconvection of a suspension of Euglena gracilis, a photosensitive flagellate whose body length is approximately 50 micrometers, was experimentally studied. Under strong light intensity, Euglena has a negative phototaxis; they tend to go away from the light source. When the bright illumination is given from the bottom, a large scale spatio-temporal pattern is generated as a result of interaction between Euglena and surrounding flow. Recently, localized convection pattern had been reported, however, the generation process and interaction of the localized convection cells has not been analyzed. We performed experimental study to understand the localization mechanism, in particular, the onset of bioconvection and lateral localization behavior due to phototaxis. Experiments started from different initial condition suggests a bistability near the onset of the convection as binary fluid convection that also shows localized convection cells. Dynamics of localized convections cells, which is similar to the binary fluid convection case although the basic equations are not the same, is also reported.

  9. Optimized Non-Orthogonal Localized Orbitals for Linear Scaling Quantum Monte Carlo calculations

    NASA Astrophysics Data System (ADS)

    Williamson, Andrew; Reboredo, Fernando; Galli, Giulia

    2004-03-01

    It has been shown [1] that Quantum Monte Carlo calculations of total energies of interacting systems can be made to scale nearly linearly with the number of electrons (N), by using localized single particle orbitals to construct Slater determinants. Here we propose a new way of defining the localized orbitals required for O(N)-QMC calculation, by minimizing an appropriate cost function yielding a set of N non-orthogonal (NO) localized orbitals considerably smoother in real space than Maximally localized Wannier functions (MLWF). These NO orbitals have better localization properties than MLWFs. We show that for semiconducting systems NO orbitals can be localized in a much smaller region of space than orthogonal orbitals (typically, one eighth of the volume) and give total energies with the same accuracy, thus yielding a linear scaling QMC algorithm which is 5 times faster than the one originally proposed [1]. We also discuss the extension of O(N)-QMC with NO orbitals to the calculations of total energies of metallic systems. This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48. [1] A. J. Williamson, R.Q. Hood and J.C. Grossman, Phys. Rev. Lett. 87, 246406 (2001)

  10. Urbanization drives community shifts towards thermophilic and dispersive species at local and landscape scales.

    PubMed

    Piano, Elena; De Wolf, Katrien; Bona, Francesca; Bonte, Dries; Bowler, Diana E; Isaia, Marco; Lens, Luc; Merckx, Thomas; Mertens, Daan; van Kerckvoorde, Marc; De Meester, Luc; Hendrickx, Frederik

    2017-07-01

    The increasing conversion of agricultural and natural areas to human-dominated urban landscapes is predicted to lead to a major decline in biodiversity worldwide. Two conditions that typically differ between urban environments and the surrounding landscape are increased temperature, and high patch isolation and habitat turnover rates. However, the extent and spatial scale at which these altered conditions shape biotic communities through selection and/or filtering on species traits are currently poorly understood. We sampled carabid beetles at 81 sites in Belgium using a hierarchically nested sampling design wherein three local-scale (200 × 200 m) urbanization levels were repeatedly sampled across three landscape-scale (3 × 3 km) urbanization levels. First, we showed that communities sampled in the most urbanized locations and landscapes displayed a distinct species composition at both local and landscape scale. Second, we related community means of species-specific thermal preferences and dispersal capacity (based on European distribution and wing morphology, respectively) to the urbanization gradients. We showed that urban communities consisted on average of species with a preference for higher temperatures and with better dispersal capacities compared to rural communities. These shifts were caused by an increased number of species tolerating higher temperatures, a decreased richness of species with low thermal preference, and an almost complete depletion of species with very low-dispersal capacity in the most urbanized localities. Effects of urbanization were most clearly detected at the local scale, although more subtle effects could also be found at the scale of entire landscapes. Our results demonstrate that urbanization may fundamentally and consistently alter species composition by exerting a strong filtering effect on species dispersal characteristics and favouring replacement by warm-dwelling species. © 2017 John Wiley & Sons Ltd.

  11. Simultaneous estimation of local-scale and flow path-scale dual-domain mass transfer parameters using geoelectrical monitoring

    USGS Publications Warehouse

    Briggs, Martin A.; Day-Lewis, Frederick D.; Ong, John B.; Curtis, Gary P.; Lane, Jr., John W.

    2013-01-01

    Anomalous solute transport, modeled as rate-limited mass transfer, has an observable geoelectrical signature that can be exploited to infer the controlling parameters. Previous experiments indicate the combination of time-lapse geoelectrical and fluid conductivity measurements collected during ionic tracer experiments provides valuable insight into the exchange of solute between mobile and immobile porosity. Here, we use geoelectrical measurements to monitor tracer experiments at a former uranium mill tailings site in Naturita, Colorado. We use nonlinear regression to calibrate dual-domain mass transfer solute-transport models to field data. This method differs from previous approaches by calibrating the model simultaneously to observed fluid conductivity and geoelectrical tracer signals using two parameter scales: effective parameters for the flow path upgradient of the monitoring point and the parameters local to the monitoring point. We use regression statistics to rigorously evaluate the information content and sensitivity of fluid conductivity and geophysical data, demonstrating multiple scales of mass transfer parameters can simultaneously be estimated. Our results show, for the first time, field-scale spatial variability of mass transfer parameters (i.e., exchange-rate coefficient, porosity) between local and upgradient effective parameters; hence our approach provides insight into spatial variability and scaling behavior. Additional synthetic modeling is used to evaluate the scope of applicability of our approach, indicating greater range than earlier work using temporal moments and a Lagrangian-based Damköhler number. The introduced Eulerian-based Damköhler is useful for estimating tracer injection duration needed to evaluate mass transfer exchange rates that range over several orders of magnitude.

  12. Simultaneous estimation of local-scale and flow path-scale dual-domain mass transfer parameters using geoelectrical monitoring

    NASA Astrophysics Data System (ADS)

    Briggs, Martin A.; Day-Lewis, Frederick D.; Ong, John B. T.; Curtis, Gary P.; Lane, John W.

    2013-09-01

    Anomalous solute transport, modeled as rate-limited mass transfer, has an observable geoelectrical signature that can be exploited to infer the controlling parameters. Previous experiments indicate the combination of time-lapse geoelectrical and fluid conductivity measurements collected during ionic tracer experiments provides valuable insight into the exchange of solute between mobile and immobile porosity. Here, we use geoelectrical measurements to monitor tracer experiments at a former uranium mill tailings site in Naturita, Colorado. We use nonlinear regression to calibrate dual-domain mass transfer solute-transport models to field data. This method differs from previous approaches by calibrating the model simultaneously to observed fluid conductivity and geoelectrical tracer signals using two parameter scales: effective parameters for the flow path upgradient of the monitoring point and the parameters local to the monitoring point. We use regression statistics to rigorously evaluate the information content and sensitivity of fluid conductivity and geophysical data, demonstrating multiple scales of mass transfer parameters can simultaneously be estimated. Our results show, for the first time, field-scale spatial variability of mass transfer parameters (i.e., exchange-rate coefficient, porosity) between local and upgradient effective parameters; hence our approach provides insight into spatial variability and scaling behavior. Additional synthetic modeling is used to evaluate the scope of applicability of our approach, indicating greater range than earlier work using temporal moments and a Lagrangian-based Damköhler number. The introduced Eulerian-based Damköhler is useful for estimating tracer injection duration needed to evaluate mass transfer exchange rates that range over several orders of magnitude.

  13. Global-, local-, and intermediate-scale structures in prototype spiral galaxies

    NASA Technical Reports Server (NTRS)

    Roberts, William W., Jr.

    1993-01-01

    The relationship between galactic spiral structure and the matter in the underlying disk constitutes one of the central problems in galactic dynamics. In Bertin et al. (1989), disk matter characterized by a low-dispersive speed is shown to be capable of playing a key role in the generation of large-scale spiral structure. In Roberts et al. (1992), this self-gravitating, low-dispersion disk matter is shown to be capable of playing an essential role in the formation of structure on local and intermediate scales. Both in computed cases where large-scale spiral structure is present and in those where it is not, the same dominant physical processes and fundamental dynamical mechanisms are active on local scales. The new perception, in which large-scale and small-scale phenomena operate somewhat independently as evidenced in the computational studies, permits a range of flocculent, multiarmed, and grand design spiral types to be simulated. In particular, grand design galaxies with ragged appearances exhibiting spurs, arm branchings, and interarm bridges in addition to the major spiral arms, similar to those often observed, can be generated.

  14. Parameters driving strain localization in the lithosphere are highly scale-dependent

    NASA Astrophysics Data System (ADS)

    Jolivet, Laurent

    2016-04-01

    Modelling lithospheric deformation requires specifying mechanisms that promote strain localization. This can be done in different ways, such as the inclusion of weaker zones in the model setup (to initiate subduction or slab tearing, for instance) or using various sorts of weakening processes depending upon temperature, grain-size, fluid content or metamorphic reactions, among others. In most cases, this choice is ad hoc because the relevant parameters are largely unknown, especially at the scale of geodynamic models. Two lines of research have been developed, a traditional one which seeks to determine the rheological parameters of natural or synthetic rocks experimentally, and a more recent one, promoted by the development of fast computing, which aims at reproducing a natural tectonic or rheological evolution through time, not only geometries. The latter requires that the parameters allowing this reproduction are significant at the scale of the model, and which may be different from those obtained in the experimental lab, thus questioning the extrapolation through a wide range of scales of experimental parameters. This apparent discrepancy is due to the intrinsic complexity of the lithosphere, and even more so for the continental lithosphere with its highly heterogeneous crust and its long tectonic history, which implies the co-existence of many different parameters active in nature. In this presentation, we review the main localizing factors and look to the range of scales in which they are significant. Small-scale processes such as grain-size reduction, coexistence of several mineralogical phases with different strength and rheological behaviour, fluid-rock interactions and/or metamorphic reactions, often cannot initiate strain localization in nature but are all efficient to locally reduce the strength of rock material once localization has started. Some exceptions to this rule, however, exist, such as the mixing of ductile and brittle behaviour in the same

  15. Impact of aquifer heterogeneity structure and local-scale dispersion on solute concentration uncertainty

    NASA Astrophysics Data System (ADS)

    Srzic, Veljko; Cvetkovic, Vladimir; Andricevic, Roko; Gotovac, Hrvoje

    2013-06-01

    In this paper, we study the influence of high log-conductivity variance (σY2) and local-scale dispersion on the first two concentration moments as well as on higher-order moments, skewness, and kurtosis, in a 2-D heterogeneous aquifer. Three different heterogeneity structures are considered, defined with one and the same global isotropic Gaussian variogram. The three structures differ in terms of spatial connectivity patterns at extreme log-conductivity values. Our numerical approach to simulate contaminant transport through heterogeneous porous media is based on the Lagrangian framework with a reverse tracking formulation. Advection and local-scale dispersion are two competing and controlling mechanisms, with a relative ratio defined by the Peclet number (Pe); hydraulic log-conductivity variance σY2 in the simulations is assumed to be one or eight. The term local-scale dispersion is used as a combined effect of molecular diffusion and mechanical dispersion. Uncertainty of the concentration field is quantified by the second-order moment, or the coefficient of variation (CVC) as a function of the sampling position along a centerline, Peclet number, and σY2, as well as by higher-order moments, i.e., skewness and kurtosis. The parameter σY2 shows a strong influence on the concentration statistics, while the three different structures have a minor impact in the case of low heterogeneity. The results also indicate that for σY2=8, the influence of local-scale dispersion is significant after five integral scales (IY) from the source for the connected (CN) field, while in case of a disconnected field, the local-scale dispersion effect is observed after 20IY from the source. In the case of unit σY2, local-scale dispersion acts very slowly affecting concentration uncertainty at distances higher than 20IY from the source. Our inspection of Monte Carlo concentration skewness and kurtosis with the ones obtained from the Beta distribution show the discrepancies for high

  16. Photodiodes for ten micrometer laser communication systems

    NASA Technical Reports Server (NTRS)

    Cohen, S. C.

    1972-01-01

    The performance is discussed of 10-micron mercury-cadmiumtelluride and lead-tin-telluride photodiodes in laser heterodyne communication systems. The dependence of detector quantum efficiency, resistance, frequency response, and signal-to-noise ratio on temperature, bias, and local oscillator power are examined. Included in the discussion is an analysis of the feasibility of high temperature operation, and ability of the detector to dissipate power to a heat sink is explored. Some aspects of direct detection response are considered and figures showing flux levels from a blackbody presented.

  17. Comparison of local- to regional-scale estimates of ground-water recharge in Minnesota, USA

    USGS Publications Warehouse

    Delin, G.N.; Healy, R.W.; Lorenz, D.L.; Nimmo, J.R.

    2007-01-01

    Regional ground-water recharge estimates for Minnesota were compared to estimates made on the basis of four local- and basin-scale methods. Three local-scale methods (unsaturated-zone water balance, water-table fluctuations (WTF) using three approaches, and age dating of ground water) yielded point estimates of recharge that represent spatial scales from about 1 to about 1000 m2. A fourth method (RORA, a basin-scale analysis of streamflow records using a recession-curve-displacement technique) yielded recharge estimates at a scale of 10–1000s of km2. The RORA basin-scale recharge estimates were regionalized to estimate recharge for the entire State of Minnesota on the basis of a regional regression recharge (RRR) model that also incorporated soil and climate data. Recharge rates estimated by the RRR model compared favorably to the local and basin-scale recharge estimates. RRR estimates at study locations were about 41% less on average than the unsaturated-zone water-balance estimates, ranged from 44% greater to 12% less than estimates that were based on the three WTF approaches, were about 4% less than the age dating of ground-water estimates, and were about 5% greater than the RORA estimates. Of the methods used in this study, the WTF method is the simplest and easiest to apply. Recharge estimates made on the basis of the UZWB method were inconsistent with the results from the other methods. Recharge estimates using the RRR model could be a good source of input for regional ground-water flow models; RRR model results currently are being applied for this purpose in USGS studies elsewhere.

  18. Relative importance of local- and large-scale drivers of alpine soil microarthropod communities.

    PubMed

    Mitchell, Ruth J; Urpeth, Hannah M; Britton, Andrea J; Black, Helaina; Taylor, Astrid R

    2016-11-01

    Nitrogen (N) deposition and climate are acknowledged drivers of change in biodiversity and ecosystem function at large scales. However, at a local scale, their impact on functions and community structure of organisms is filtered by drivers like habitat quality and food quality/availability. This study assesses the relative impact of large-scale factors, N deposition and climate (rainfall and temperature), versus local-scale factors of habitat quality and food quality/availability on soil fauna communities at 15 alpine moss-sedge heaths along an N deposition gradient in the UK. Habitat quality and food quality/availability were the primary drivers of microarthropod communities. No direct impacts of N deposition on the microarthropod community were observed, but induced changes in habitat quality (decline in moss cover and depth) and food quality (decreased vegetation C:N) associated with increased N deposition strongly suggest an indirect impact of N. Habitat quality and climate explained variation in the composition of the Oribatida, Mesostigmata, and Collembola communities, while only habitat quality significantly impacted the Prostigmata. Food quality and prey availability were important in explaining the composition of the oribatid and mesostigmatid mite communities, respectively. This study shows that, in alpine habitats, soil microarthropod community structure responds most strongly to local-scale variation in habitat quality and food availability rather than large-scale variation in climate and pollution. However, given the strong links between N deposition and the key habitat quality parameters, we conclude that N deposition indirectly drives changes in the soil microarthropod community, suggesting a mechanism by which large-scale drivers indirectly impacts these functionally important groups.

  19. Quantifying spatial scaling patterns and their local and regional correlates in headwater streams: Implications for resilience

    USGS Publications Warehouse

    Gothe, Emma; Sandin, Leonard; Allen, Craig R.; Angeler, David G.

    2014-01-01

    The distribution of functional traits within and across spatiotemporal scales has been used to quantify and infer the relative resilience across ecosystems. We use explicit spatial modeling to evaluate within- and cross-scale redundancy in headwater streams, an ecosystem type with a hierarchical and dendritic network structure. We assessed the cross-scale distribution of functional feeding groups of benthic invertebrates in Swedish headwater streams during two seasons. We evaluated functional metrics, i.e., Shannon diversity, richness, and evenness, and the degree of redundancy within and across modeled spatial scales for individual feeding groups. We also estimated the correlates of environmental versus spatial factors of both functional composition and the taxonomic composition of functional groups for each spatial scale identified. Measures of functional diversity and within-scale redundancy of functions were similar during both seasons, but both within- and cross-scale redundancy were low. This apparent low redundancy was partly attributable to a few dominant taxa explaining the spatial models. However, rare taxa with stochastic spatial distributions might provide additional information and should therefore be considered explicitly for complementing future resilience assessments. Otherwise, resilience may be underestimated. Finally, both environmental and spatial factors correlated with the scale-specific functional and taxonomic composition. This finding suggests that resilience in stream networks emerges as a function of not only local conditions but also regional factors such as habitat connectivity and invertebrate dispersal.

  20. An Evaluation of Local Similarity Scaling Over a Steep Alpine Slope

    NASA Astrophysics Data System (ADS)

    Nadeau, D. F.; Oldroyd, H. J.; Pardyjak, E. R.; Higgins, C. W.; Parlange, M. B.

    2012-04-01

    In this work, we investigate the applicability of similarity scaling over a steep mountain slope (30°- 41°). The results are based on eddy correlation measurements collected in Val Ferret, a narrow valley of the Swiss Alps, in summer 2010. The turbulent fluxes of heat and momentum are found to vary significantly with height in the first few meters above the inclined surface. These variations exceed by an order of magnitude the well-accepted maximum 10% required for the validity of Monin-Obukhov similarity in the surface-layer, possibly as a result of advective fluxes. In these cases when surface-layer theory breaks down, we show that local scaling can be a useful tool. Under convective conditions and after removing the effects of self-correlation, the normalized standard deviations of vertical velocity, temperature and humidity scale relatively well with z/L, where z is the measurement height and L the local Obukhov length. However, the horizontal velocity fluctuations are not correlated with z/L, and that under all stability conditions. The non-dimensional gradients of temperature and wind velocity are also investigated. For those the local scaling appear inappropriate, particularly at night when shallow drainage flows are found and lead to negative wind speed gradients near the surface.

  1. Local soil fertility management on small-scale farming systems for sustainable agriculture

    NASA Astrophysics Data System (ADS)

    Namriah, Kilowasid, Laode Muhammad Harjoni

    2015-09-01

    The sustainability of small-scale farming systems on marginal lands is still being a topic of debate in scientific and institutional communities. To address this, a study was conducted to find a method of sustaining the productivity of marginal lands for food crop production. Agricultural practices (fallow and traditional cultivation) used by the local small-scale farmers in managing soil fertility to meet the natural biological processes above and below the ground were studied in Muna Island Southeast Sulawesi, Indonesia. Participatory approach was used to gather data and information on soil and land as well as to collect soil macrofauna. The results showed that the practices of local small-scale farmers are based on local soil and land suitability. Organic materials are the source of nutrient inputs to sustain the productivity of their lands by fallowing, burning natural vegetation, putting back the crop residues, doing minimum tillage and mix- and inter-crops. In conclusion, the sustainability of local small-scale farming systems will be established by knowing and understanding local soil and land classification systems and preferred crops being planted. Following the nature of fallow and monitoring soil macrofauna diversity and abundance, all preferred crops should be planted during rainy season with different time of harvest until the next rainy season. Therefore, soils are still covered with crops during dry season. It was suggested that planting time should be done in the rainy season. Doing more researches in other locations with different socio-cultural, economical, and ecological conditions is suggested to validate and refine the method.

  2. Spanning From Atoms to Micrometers in Simulations of Contact, Adhesion and Friction

    NASA Astrophysics Data System (ADS)

    Robbins, Mark

    Improved understanding of the forces between realistic solid surfaces is needed to optimize adhesion and friction. Modeling these forces is challenging because they arise from interactions between atoms separated by less than a nanometer, but the number and spatial distribution of these contacting atoms depends on surface roughness and deformation on micrometer and larger scales. There are also strong scale effects in the role of elastic deformations along the surface. The talk will first describe a seamless Greens function (GF) method that allows a full treatment of elastic deformations and atomic contact for micrometer scale surfaces and multibody potentials. Next applications of the method to calculations of the contact area, contact stiffness, adhesion and friction for a range of geometries and interactions will be described. The results can be captured with simple analytic expressions and explain why most contacting surfaces do not adhere. Theoretical and experimental studies of single nanometer-scale asperities show that the frictional shear stress depends strongly on whether surfaces are commensurate. A large constant stress is obtained for identical, aligned crystalline surfaces, but the stress averages to zero in the more common case of incommensurate surfaces. The resulting ultralow friction is called superlubricity and is found in experiments and simulations of small contacts. Our simulations reveal dramatic changes in this behavior because different parts of the surface are able to advance independently as the contact radius increases towards micrometer scales. The friction between identical surfaces drops with increasing radius and then saturates at a low value. The force between incommensurate surfaces saturates at a similar value that can be related to the Peierls stress for dislocation motion at the interface. Studies of multiasperity contacts also show that incoherent motion along the interface can lead to pronounced changes in the macroscopic

  3. Evolving uses of passive seismic arrays from continental to local scales

    NASA Astrophysics Data System (ADS)

    Schmandt, B.

    2014-12-01

    Portable passive seismic surveys are generally used to sample scales and locations that are not practical with long-term observatories, but are fundamental to studying Earth systems. The breadth of uses and designs of portable passive surveys is expanding rapidly as result of advances in instrumentation and analysis. Examples from recent passive surveys will be used illustrate how they are bringing new constraint to systems spanning continental to local scales. At continental scale EarthScope's USArray is providing a view of the transition zone between the upper and lower mantle that facilitates integration of seismology, geodynamics, and mineral physics. Recently recognized correlations between mantle flow and abrupt velocity decreases in the top of the lower mantle are consistent with laboratory constraints on the consequences of volatile cycling in the deep Earth. Arrays with similar numbers of seismometers (~103) are also being used in a passive mode on much smaller scales. The Long Beach 3D survey conducted by NodalSeismic in 2011 covered only 7x10 km in southern California with about 5,000 seismometers. The instruments were optimized for recording high frequencies (>10 Hz), but they also successfully recorded local and teleseismic earthquakes. Delay time and amplitude maps for earthquake body-waves revealed coherent structural variations at scales as small as about 400 m. Such dense sampling of teleseismic earthquake wave fields yielded new constraint on localized deep crustal deformation underlying the tectonic boundary between mainland California and the rifted Inner Continental Borderland. The utility of passive data from the Long Beach 3D survey partly motivated a recent deployment of more than 900 exploration industry seismometers to record continuously for 2 weeks at Mt. St. Helens volcano in Washington in 2014. New observations of the >50 local earthquakes recorded within the Mt. St. Helens array will also be presented.

  4. High sensitivity infrared 10.6 micrometer heterodyne receiver development

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The results are presented for a study on the design of an infrared 10.6-micrometer quantum-noise-limited optical receiver subsystem. Performance measurements of the HgCdTe photomixer preamplifier combination were carried out for photomixer temperatures up to 152 K and a photomixer frequency response of up to 420 MHz was obtained. Results of temperature and bias cycling of HgCdTe photomixers are reported. Design considerations for an operational 10.6 micrometer heterodyne receiver are presented. These consist of design data on required laser LO illumination, heat load levels for photomixer cooler, photomixer uniformity and the effects of photomixer impedance match on receiver sensitivity. Analysis and measurements of 10.6 micrometer heterodyne detection in an extrinsic photoconductive (p-type) HgCdTe photomixer are also presented.

  5. Local-scale analysis of cardiovascular signals by detrended fluctuations analysis: effects of posture and exercise.

    PubMed

    Castiglioni, Paolo; Quintin, Luc; Civijian, Andrei; Parati, Gianfranco; Di Rienzo, Marco

    2007-01-01

    The fractal structure of heart rate is usually quantified by estimating a short-term (alpha(1)) and a long-term (alpha(2)) scaling exponent by Detrended Fluctuations Analysis (DFA). Evidence, however, has been provided that heart rate is a multifractal signal, better characterized by a large number of scaling exponents. Aim of this study is to verify whether two scaling exponents only from DFA provide a sufficiently accurate description of the possibly multifractal nature of cardiovascular signals. We measured ECG and finger arterial pressure in 33 volunteers for 10 minutes during each of 3 conditions: supine rest (SUP); sitting at rest (SIT); light physical exercise (EXE). DFA was applied on the beat-by-beat series of R-R interval (RRI) and mean arterial pressure (MAP). We then computed the local scaling exponent alpha(n), defined as the slope of the detrended fluctuation function F(n) around the beat scale n, in a log-log plot. If alpha(1) and alpha(2) correctly model the multiscale structure of blood pressure and heart rate, we should find that alpha(n) is constant over a short-term and a longterm range of beat scales. Results show that only the long-term alpha2 exponent provides a relatively good approximation of the multiscale structure of RRI and MAP. Moreover, posture and physical activity have important effects on local scaling exponents, and on the range of beat scales n where alpha(n) can be approximated by a constant alpha2 coefficient.

  6. Multi-scale strain localization within orthogneiss during subduction and exhumation (Tenda unit, Alpine Corsica)

    NASA Astrophysics Data System (ADS)

    Beaudoin, Alexandre; Augier, Romain; Jolivet, Laurent; Raimbourg, Hugues; Jourdon, Anthony; Scaillet, Stéphane; Cardello, Giovanni Luca

    2016-04-01

    Strain localization depends upon scale-related factors resulting in a gap between small-scale studies of deformation mechanisms and large-scale numerical and tectonic models. The former often ignore the variations in composition and water content across tectonic units, while the latter oversimplify the role of the deformation mechanisms. This study aims to heal this gap, by considering microstructures and strain localization not only at a single shear zone-scale but across a 40km-wide tectonic unit and throughout its complex polyphased evolution. The Tenda unit (Alpine Corsica) is an external continental unit mainly composed of granites, bounded by the East Tenda Shear Zone (ETSZ) that separates it from the overlying oceanic-derived HP tectonic units. Previous studies substantially agreed on (1) the burial of the Tenda unit down to blueschist-facies conditions associated with top-to-the-west shearing (D1) and (2) subsequent exhumation accommodated by a localized top-to-the-east shear zone (D2). Reaction-softening is the main localizing mechanism proposed in the literature, being associated with the transformation of K-feldspar into white-mica. In this work, the Tenda unit is reviewed through (1) the construction of a new field-based strain map accompanied by cross-sections representing volumes of rock deformed at different grades related to large-scale factors of strain localization and (2) the structural study of hand-specimens and thin-sections coupled with EBSD analysis in order to target the deformation processes. We aim to find how softening and localization are in relation to the map-scale distribution of strain. The large-scale study shows that the whole Tenda unit is affected by the two successive stages of deformation. However, a more intense deformation is observed along the eastern margin, which originally led to the definition of the ETSZ, with a present-day anastomosed geometry of deformation. Strain localization is clearly linked to rheological

  7. Implications for clinical treatment from the micrometer site dosimetric calculations in boron neutron capture therapy.

    PubMed

    Nichols, Trent L; Kabalka, George W; Miller, Laurence F; McCormack, Michael T; Johnson, Andrew

    2009-07-01

    Boron neutron capture therapy has now been used for several malignancies. Most clinical trials have addressed its use for the treatment of glioblastoma multiforme. A few trials have focused on the treatment of malignant melanoma with brain metastases. Trial results for the treatment of glioblastoma multiforme have been encouraging, but have not achieved the success anticipated. Results of trials for the treatment of malignant melanoma have been very promising, though with too few patients for conclusions to be drawn. Subsequent to these trials, regimens for undifferentiated thyroid carcinoma, hepatic metastases from adenocarcinoma of the colon, and head and neck malignancies have been developed. These tumors have also responded well to boron neutron capture therapy. Glioblastoma is an infiltrative tumor with distant individual tumor cells that might create a mechanism for therapeutic failure though recurrences are often local. The microdosimetry of boron neutron capture therapy can provide an explanation for this observation. Codes written to examine the micrometer scale energy deposition in boron neutron capture therapy have been used to explore the effects of near neighbor cells. Near neighbor cells can contribute a significantly increased dose depending on the geometric relationships. Different geometries demonstrate that tumors which grow by direct extension have a greater near neighbor effect, whereas infiltrative tumors lose this near neighbor dose which can be a significant decrease in dose to the cells that do not achieve optimal boron loading. This understanding helps to explain prior trial results and implies that tumors with small, closely packed cells that grow by direct extension will be the most amenable to boron neutron capture therapy.

  8. Locally auxetic behavior of elastomeric polypropylene on the 100 nm length scale.

    PubMed

    Franke, Mechthild; Magerle, Robert

    2011-06-28

    We observe unexpected locally auxetic behavior in elastomeric polypropylene, a semicrystalline polymer with a natural microstructure and a low degree of crystallinity. Our series of scanning force microscopy images show the nanomechanical deformation processes that occur upon stretching a thin film of elastomeric polypropylene. Upon uniaxial stretching, the angle between epitaxially grown lamella branches remains constant and the lamellae elongate, resulting in locally auxetic behavior (negative Poisson's ratio) on the 100-nanometer scale. This mechanism causing auxetic behavior, which was previously proposed on the basis of geometric arguments, appears to be an intrinsic property of certain semicrystalline polymers.

  9. Localization and length-scale doubling in disordered films on soft substrates

    NASA Astrophysics Data System (ADS)

    Semler, Matthew R.; Harris, John M.; Croll, Andrew B.; Hobbie, Erik K.

    2013-09-01

    Wrinkling and folding are examined experimentally for three distinct types of disordered films on polydimethylsiloxane (PDMS) substrates; diblock copolymers, glassy polymers, and single-wall carbon nanotubes. All three of these systems exhibit localization and length-scale doubling at small strains, and we qualitatively account for these observations with a simple physical argument related to the width of the stress correlation function and the interaction of localization sites. Our results have relevance to wrinkling and folding in a diverse array of disordered films on soft substrates, and the insights offered here should help guide the development of theoretical models for the influence of structural disorder on thin-film wrinkling instabilities.

  10. Incorporating a measure of local scale in voxel-based 3-D image registration.

    PubMed

    Nyúl, László G; Udupa, Jayaram K; Saha, Punam K

    2003-02-01

    We present a new class of approaches for rigid-body registration and their evaluation in studying multiple sclerosis (MS) via multiprotocol magnetic resonance imaging (MRI). Three pairs of rigid-body registration algorithms were implemented, using cross-correlation and mutual information (MI), operating on original gray-level images, and utilizing the intermediate images resulting from our new scale-based method. In the scale image, every voxel has the local "scale" value assigned to it, defined as the radius of the largest ball centered at the voxel with homogeneous intensities. Three-dimensional image data of the head were acquired from ten MS patients for each of six MRI protocols. Images in some of the protocols were acquired in registration. The registered pairs were used as ground truth. Accuracy and consistency of the six registration methods were measured within and between protocols for known amounts of misregistrations. Our analysis indicates that there is no "best" method. For medium misregistration, the method using MI, for small add large misregistration the method using normalized cross-correlation performs best. For high-resolution data the correlation method and for low-resolution data the MI method, both using the original gray-level images, are the most consistent. We have previously demonstrated the use of local scale information in fuzzy connectedness segmentation and image filtering. Scale may also have potential for image registration as suggested by this work.

  11. Exploring Macroinvertebrate Species Distributions at Regional and Local Scales across a Sandy Beach Geographic Continuum

    PubMed Central

    Rodil, Iván F.; Compton, Tanya J.; Lastra, Mariano

    2012-01-01

    Exposed sandy beaches are highly dynamic ecosystems where macroinvertebrate species cope with extremely variable environmental conditions. The majority of the beach ecology studies present exposed beaches as physically dominated ecosystems where abiotic factors largely determine the structure and distribution of macrobenthic communities. However, beach species patterns at different scales can be modified by the interaction between different environmental variables, including biotic interactions. In this study, we examined the role of different environmental variables for describing the regional and local scale distributions of common macrobenthic species across 39 beaches along the North coast of Spain. The analyses were carried out using boosted regression trees, a relatively new technique from the field of machine learning. Our study showed that the macroinvertebrate community on exposed beaches is not structured by a single physical factor, but instead by a complex set of drivers including the biotic compound. Thus, at a regional scale the macrobenthic community, in terms of number of species and abundance, was mainly explained by surrogates of food availability, such as chlorophyll a. The results also revealed that the local scale is a feasible way to construct general predictive species-environmental models, since relationships derived from different beaches showed similar responses for most of the species. However, additional information on aspects of beach species distribution can be obtained with large scale models. This study showed that species-environmental models should be validated against changes in spatial extent, and also illustrates the utility of BRTs as a powerful analysis tool for ecology data insight. PMID:22761841

  12. Decoupling local mechanics from large-scale structure in modular metamaterials

    NASA Astrophysics Data System (ADS)

    Yang, Nan; Silverberg, Jesse L.

    2017-04-01

    A defining feature of mechanical metamaterials is that their properties are determined by the organization of internal structure instead of the raw fabrication materials. This shift of attention to engineering internal degrees of freedom has coaxed relatively simple materials into exhibiting a wide range of remarkable mechanical properties. For practical applications to be realized, however, this nascent understanding of metamaterial design must be translated into a capacity for engineering large-scale structures with prescribed mechanical functionality. Thus, the challenge is to systematically map desired functionality of large-scale structures backward into a design scheme while using finite parameter domains. Such “inverse design” is often complicated by the deep coupling between large-scale structure and local mechanical function, which limits the available design space. Here, we introduce a design strategy for constructing 1D, 2D, and 3D mechanical metamaterials inspired by modular origami and kirigami. Our approach is to assemble a number of modules into a voxelized large-scale structure, where the module’s design has a greater number of mechanical design parameters than the number of constraints imposed by bulk assembly. This inequality allows each voxel in the bulk structure to be uniquely assigned mechanical properties independent from its ability to connect and deform with its neighbors. In studying specific examples of large-scale metamaterial structures we show that a decoupling of global structure from local mechanical function allows for a variety of mechanically and topologically complex designs.

  13. Decoupling local mechanics from large-scale structure in modular metamaterials.

    PubMed

    Yang, Nan; Silverberg, Jesse L

    2017-04-04

    A defining feature of mechanical metamaterials is that their properties are determined by the organization of internal structure instead of the raw fabrication materials. This shift of attention to engineering internal degrees of freedom has coaxed relatively simple materials into exhibiting a wide range of remarkable mechanical properties. For practical applications to be realized, however, this nascent understanding of metamaterial design must be translated into a capacity for engineering large-scale structures with prescribed mechanical functionality. Thus, the challenge is to systematically map desired functionality of large-scale structures backward into a design scheme while using finite parameter domains. Such "inverse design" is often complicated by the deep coupling between large-scale structure and local mechanical function, which limits the available design space. Here, we introduce a design strategy for constructing 1D, 2D, and 3D mechanical metamaterials inspired by modular origami and kirigami. Our approach is to assemble a number of modules into a voxelized large-scale structure, where the module's design has a greater number of mechanical design parameters than the number of constraints imposed by bulk assembly. This inequality allows each voxel in the bulk structure to be uniquely assigned mechanical properties independent from its ability to connect and deform with its neighbors. In studying specific examples of large-scale metamaterial structures we show that a decoupling of global structure from local mechanical function allows for a variety of mechanically and topologically complex designs.

  14. 0.4-3.5-micrometer Observations of 4179 Toutatis

    NASA Astrophysics Data System (ADS)

    Howell, E. S.; Britt, D. T.; Bell, J. F.; Binzel, R. P.; Lebofsky, L. A.

    1993-07-01

    We obtained nearly simultaneous observations of 4179 Toutatis over a 0.3-3.5 micrometer wavelength range on 4 January 1993 UT. Howell obtained a 1.2-2.5 micrometer spectrophotometry using the Multiple Mirror Telescope in Arizona. Britt and Bell obtained narrowband photometry in the 3-micrometer region as well as broadband JHK photometry from the Infrared Telescope Facility in Hawaii. Binzel measured the visible spectrum using a CCD spectrograph at the McGraw-Hill Observatory in Arizona. Using V photometry reported by Pravec in the Czech Republic on adjacent nights [1], we were able to combine all these spectral regions. The rotation period of this object is approximately 10 days, so the time differences between the measurements of different spectral regions are negligible. Tholen has classified 4179 Toutatis as an S-type asteroid based on visible photometry. We measure a pyroxene absorption band near 2 micrometers, present in most S-type asteroid spectra. Unfortunately, a gap in spectral coverage prevents us from determining the characteristics of the 1-micrometer absorption band accurately. The spectral slope as measured from 1.25 to 2.2 micrometers is 6-10%, which is modest compared to other S-type asteroids. The spectrum of this asteroid is similar to other near-Earth S-type asteroids that have been observed in the near-infrared wavelength region. On 4 January 1993, 4179 Toutatis was 0.182 AU from the Earth, and 1.158 AU from the Sun. At this solar distance, the thermal emission contributes substantially to the flux at 3 micrometers. The determination of thermal emission is complicated by the slow rotation rate and the irregular shape of this object that was revealed by radar observations [2]. Preliminary results suggest that no 3-micrometer absorption feature is present, indicating that this object is anhydrous. Using these spectral data, we will compare 4179 Toutatis to other S-type asteroids, both in the main belt and the near-Earth environment. References

  15. Effects of large-scale deforestation on precipitation in the monsoon regions: remote versus local effects.

    PubMed

    Devaraju, N; Bala, Govindasamy; Modak, Angshuman

    2015-03-17

    In this paper, using idealized climate model simulations, we investigate the biogeophysical effects of large-scale deforestation on monsoon regions. We find that the remote forcing from large-scale deforestation in the northern middle and high latitudes shifts the Intertropical Convergence Zone southward. This results in a significant decrease in precipitation in the Northern Hemisphere monsoon regions (East Asia, North America, North Africa, and South Asia) and moderate precipitation increases in the Southern Hemisphere monsoon regions (South Africa, South America, and Australia). The magnitude of the monsoonal precipitation changes depends on the location of deforestation, with remote effects showing a larger influence than local effects. The South Asian Monsoon region is affected the most, with 18% decline in precipitation over India. Our results indicate that any comprehensive assessment of afforestation/reforestation as climate change mitigation strategies should carefully evaluate the remote effects on monsoonal precipitation alongside the large local impacts on temperatures.

  16. Spatially continuous dataset at local scale of Taita Hills in Kenya and Mount Kilimanjaro in Tanzania.

    PubMed

    Mwalusepo, Sizah; Massawe, Estomih S; Johansson, Tino

    2016-09-01

    Climate change is a global concern, requiring local scale spatially continuous dataset and modeling of meteorological variables. This dataset article provided the interpolated temperature, rainfall and relative humidity dataset at local scale along Taita Hills and Mount Kilimanjaro altitudinal gradients in Kenya and Tanzania, respectively. The temperature and relative humidity were recorded hourly using automatic onset (TH)HOBO data loggers and rainfall was recorded daily using GENERAL(R) wireless rain gauges. Thin plate spline (TPS) was used to interpolate, with the degree of data smoothing determined by minimizing the generalized cross validation. The dataset provide information on the status of the current climatic conditions along the two mountainous altitudinal gradients in Kenya and Tanzania. The dataset will, thus, enhance future research.

  17. Effects of large-scale deforestation on precipitation in the monsoon regions: Remote versus local effects

    PubMed Central

    Devaraju, N.; Bala, Govindasamy; Modak, Angshuman

    2015-01-01

    In this paper, using idealized climate model simulations, we investigate the biogeophysical effects of large-scale deforestation on monsoon regions. We find that the remote forcing from large-scale deforestation in the northern middle and high latitudes shifts the Intertropical Convergence Zone southward. This results in a significant decrease in precipitation in the Northern Hemisphere monsoon regions (East Asia, North America, North Africa, and South Asia) and moderate precipitation increases in the Southern Hemisphere monsoon regions (South Africa, South America, and Australia). The magnitude of the monsoonal precipitation changes depends on the location of deforestation, with remote effects showing a larger influence than local effects. The South Asian Monsoon region is affected the most, with 18% decline in precipitation over India. Our results indicate that any comprehensive assessment of afforestation/reforestation as climate change mitigation strategies should carefully evaluate the remote effects on monsoonal precipitation alongside the large local impacts on temperatures. PMID:25733889

  18. Predicting habitat suitability for rare plants at local spatial scales using a species distribution model.

    PubMed

    Gogol-Prokurat, Melanie

    2011-01-01

    If species distribution models (SDMs) can rank habitat suitability at a local scale, they may be a valuable conservation planning tool for rare, patchily distributed species. This study assessed the ability of Maxent, an SDM reported to be appropriate for modeling rare species, to rank habitat suitability at a local scale for four edaphic endemic rare plants of gabbroic soils in El Dorado County, California, and examined the effects of grain size, spatial extent, and fine-grain environmental predictors on local-scale model accuracy. Models were developed using species occurrence data mapped on public lands and were evaluated using an independent data set of presence and absence locations on surrounding lands, mimicking a typical conservation-planning scenario that prioritizes potential habitat on unsurveyed lands surrounding known occurrences. Maxent produced models that were successful at discriminating between suitable and unsuitable habitat at the local scale for all four species, and predicted habitat suitability values were proportional to likelihood of occurrence or population abundance for three of four species. Unfortunately, models with the best discrimination (i.e., AUC) were not always the most useful for ranking habitat suitability. The use of independent test data showed metrics that were valuable for evaluating which variables and model choices (e.g., grain, extent) to use in guiding habitat prioritization for conservation of these species. A goodness-of-fit test was used to determine whether habitat suitability values ranked habitat suitability on a continuous scale. If they did not, a minimum acceptable error predicted area criterion was used to determine the threshold for classifying habitat as suitable or unsuitable. I found a trade-off between model extent and the use of fine-grain environmental variables: goodness of fit was improved at larger extents, and fine-grain environmental variables improved local-scale accuracy, but fine-grain variables

  19. NASA Cold Land Processes Experiment (CLPX 2002/03): Local scale observation site

    Treesearch

    Janet Hardy; Robert Davis; Yeohoon Koh; Don Cline; Kelly Elder; Richard Armstrong; Hans-Peter Marshall; Thomas Painter; Gilles Castres Saint-Martin; Roger DeRoo; Kamal Sarabandi; Tobias Graf; Toshio Koike; Kyle McDonald

    2008-01-01

    The local scale observation site (LSOS) is the smallest study site (0.8 ha) of the 2002/03 Cold Land Processes Experiment (CLPX) and is located within the Fraser mesocell study area. It was the most intensively measured site of the CLPX, and measurements here had the greatest temporal component of all CLPX sites. Measurements made at the LSOS were designed to produce a...

  20. Nearshore Costal Dynamics during Intense Winds: Local and Synoptic Scale Events

    NASA Astrophysics Data System (ADS)

    Torres-Freyermuth, A.; Puleo, J. A.; DiCosmo, N. R.; de la Roza, J.; Figueroa, B.; Ruiz de Alegría-Arzaburu, A.; López-González, J.; Allende-Arandía, M. E.

    2016-02-01

    Nearshore coastal dynamics during intense winds events are investigated in the Northern Yucatan Peninsula. Understanding the hydrodynamics under local and synoptic scale events in this region is essential to predict sediment and pollution transport. The study area is characterized by a very wide continental shelf, a micro-tidal range, and the influence of easterly winds. Moreover, intense onshore winds associated with either local sea-breezes or synoptic scale cold-front passages are ubiquitous in this region. The wind speed during these events can exceed 15 m/s and play an important role in the coastal circulation. A field experiment was conducted during Spring 2014 (April 1stto 12th) in order to investigate coastal dynamics from the inner shelf to swash, during local and synoptic scale events. Waves and currents were measured concurrently at different cross-shore locations (inner shelf, surf zone, swash zone) and are correlated with the different forcing mechanisms (i.e., wind, waves, and tides). A westward current is observed extending from the shelf to the swash zone during strong sea breeze events (>10 m/s from the northeast). The current magnitude increases towards shore, but can be related to different forcing mechanism depending on the cross-shore location. On the other hand, during the cold-front passage (storm event) circulation changes drastically with onshore current in the inner shelf, whereas strong undertow currents are observed inside the surf zone. Understanding the hydrodynamics under local and synoptic scale events is essential to predict sediment and pollution transport in the study area. This work was funded by the Instituto de Ingenieria UNAM, through the International Collaborative Research project with the University of Delaware, and the DGAPA UNAM (PAPIIT IN107315).

  1. Challenges in Upscaling Geomorphic Transport Laws: Scale-dependence of Local vs. Non-local Formalisms and Derivation of Closures (Invited)

    NASA Astrophysics Data System (ADS)

    Foufoula-Georgiou, E.; Ganti, V. K.; Passalacqua, P.

    2010-12-01

    Nonlinear geomorphic transport laws are often derived from mechanistic considerations at a point, and yet they are implemented on 90m or 30 m DEMs, presenting a mismatch in the scales of derivation and application of the flux laws. Since estimates of local slopes and curvatures are known to depend on the scale of the DEM used in their computation, two questions arise: (1) how to meaningfully compensate for the scale dependence, if any, of local transport laws? and (2) how to formally derive, via upscaling, constitutive laws that are applicable at larger scales? Recently, non-local geomorphic transport laws for sediment transport on hillslopes have been introduced using the concept of an integral flux that depends on topographic attributes in the vicinity of a point of interest. In this paper, we demonstrate the scale dependence of local nonlinear hillslope sediment transport laws and derive a closure term via upscaling (Reynolds averaging). We also show that the non-local hillslope transport laws are inherently scale independent owing to their non-local, scale-free nature. These concepts are demonstrated via an application to a small subbasin of the Oregon Coast Range using 2m LiDAR topographic data.

  2. Improving scale invariant feature transform with local color contrastive descriptor for image classification

    NASA Astrophysics Data System (ADS)

    Guo, Sheng; Huang, Weilin; Qiao, Yu

    2017-01-01

    Image representation and classification are two fundamental tasks toward version understanding. Shape and texture provide two key features for visual representation and have been widely exploited in a number of successful local descriptors, e.g., scale invariant feature transform (SIFT), local binary pattern descriptor, and histogram of oriented gradient. Unlike these gradient-based descriptors, this paper presents a simple yet efficient local descriptor, named local color contrastive descriptor (LCCD), which captures the contrastive aspects among local regions or color channels for image representation. LCCD is partly inspired by the neural science facts that color contrast plays important roles in visual perception and there exist strong linkages between color and shape. We leverage f-divergence as a robust measure to estimate the contrastive features between different spatial locations and multiple channels. Our descriptor enriches local image representation with both color and contrast information. Due to that LCCD does not explore any gradient information, individual LCCD does not yield strong performance. But we verified experimentally that LCCD can compensate strongly SIFT. Extensive experimental results on image classification show that our descriptor improves the performance of SIFT substantially by combination on three challenging benchmarks, including MIT Indoor-67 database, SUN397, and PASCAL VOC 2007.

  3. Impact of horizontal and vertical localization scales on microwave sounder SAPHIR radiance assimilation

    NASA Astrophysics Data System (ADS)

    Krishnamoorthy, C.; Balaji, C.

    2016-05-01

    In the present study, the effect of horizontal and vertical localization scales on the assimilation of direct SAPHIR radiances is studied. An Artificial Neural Network (ANN) has been used as a surrogate for the forward radiative calculations. The training input dataset for ANN consists of vertical layers of atmospheric pressure, temperature, relative humidity and other hydrometeor profiles with 6 channel Brightness Temperatures (BTs) as output. The best neural network architecture has been arrived at, by a neuron independence study. Since vertical localization of radiance data requires weighting functions, a ANN has been trained for this purpose. The radiances were ingested into the NWP using the Ensemble Kalman Filter (EnKF) technique. The horizontal localization has been taken care of, by using a Gaussian localization function centered around the observed coordinates. Similarly, the vertical localization is accomplished by assuming a function which depends on the weighting function of the channel to be assimilated. The effect of both horizontal and vertical localizations has been studied in terms of ensemble spread in the precipitation. Aditionally, improvements in 24 hr forecast from assimilation are also reported.

  4. Accelerating multi-scale sheet forming simulations by exploiting local macroscopic quasi-homogeneities

    NASA Astrophysics Data System (ADS)

    Gawad, J.; Khairullah, Md; Roose, D.; Van Bael, A.

    2016-08-01

    Multi-scale simulations are computationally expensive if a two-way coupling is employed. In the context of sheet metal forming simulations, a fine-scale representative volume element (RVE) crystal plasticity (CP) model would supply the Finite Element analysis with plastic properties, taking into account the evolution of crystallographic texture and other microstructural features. The main bottleneck is that the fine-scale model must be evaluated at virtually every integration point in the macroscopic FE mesh. We propose to address this issue by exploiting a verifiable assumption that fine-scale state variables of similar RVEs, as well as the derived properties, subjected to similar macroscopic boundary conditions evolve along nearly identical trajectories. Furthermore, the macroscopic field variables primarily responsible for the evolution of fine-scale state variables often feature local quasi-homogeneities. Adjacent integration points in the FE mesh can be then clustered together in the regions where the field responsible for the evolution shows low variance. This way the fine-scale evolution is tracked only at a limited number of material points and the derived plastic properties are propagated to the surrounding integration points subjected to similar deformation. Optimal configurations of the clusters vary in time as the local deformation conditions may change during the forming process, so the clusters must be periodically adapted. We consider two operations on the clusters of integration points: splitting (refinement) and merging (unrefinement). The concept is tested in the Hierarchical Multi-Scale (HMS) framework [1] that computes macroscopic deformations by means of the FEM, whereas the micro-structural evolution at the individual FE integration points is predicted by a CP model. The HMS locally and adaptively approximates homogenized stress responses of the CP model by means of analytical plastic potential or yield criterion function. Our earlier work

  5. Multi-scale finite element modeling of strain localization in geomaterials with strong discontinuity

    NASA Astrophysics Data System (ADS)

    Lai, Timothy Yu

    2002-01-01

    Geomaterials such as soils and rocks undergo strain localization during various loading conditions. Strain localization manifests itself in the form of a shear band, a narrow zone of intense straining. It is now generally recognized that these localized deformations lead to an accelerated softening response and influence the response of structures at or near failure. In order to accurately predict the behavior of geotechnical structures, the effects of strain localization must be included in any model developed. In this thesis, a multi-scale Finite Element (FE) model has been developed that captures the macro- and micro-field deformation patterns present during strain localization. The FE model uses a strong discontinuity approach where a jump in the displacement field is assumed. The onset of strain localization is detected using bifurcation theory that checks when the governing equations lose ellipticity. Two types of bifurcation, continuous and discontinuous are considered. Precise conditions for plane strain loading conditions are reported for each type of bifurcation. Post-localization behavior is governed by the traction relations on the band. Different plasticity models such as Mohr-Coulomb, Drucker-Prager and a Modified Mohr-Coulomb yield were implemented together with cohesion softening and cutoff for the post-localization behavior. The FE model is implemented into a FORTRAN code SPIN2D-LOC using enhanced constant strain triangular (CST) elements. The model is formulated using standard Galerkin finite element method, applicable to problems under undrained conditions and small deformation theory. A band-tracing algorithm is implemented to track the propagation of the shear band. To validate the model, several simulations are performed from simple compression test of soft rock to simulation of a full-scale geosynthetic reinforced soil wall model undergoing strain localization. Results from both standard and enhanced FE method are included for comparison. The

  6. Golden Eagle fatalities and the continental-scale consequences of local wind-energy generation.

    PubMed

    Katzner, Todd E; Nelson, David M; Braham, Melissa A; Doyle, Jacqueline M; Fernandez, Nadia B; Duerr, Adam E; Bloom, Peter H; Fitzpatrick, Matthew C; Miller, Tricia A; Culver, Renee C E; Braswell, Loan; DeWoody, J Andrew

    2017-04-01

    Renewable energy production is expanding rapidly despite mostly unknown environmental effects on wildlife and habitats. We used genetic and stable isotope data collected from Golden Eagles (Aquila chrysaetos) killed at the Altamont Pass Wind Resource Area (APWRA) in California in demographic models to test hypotheses about the geographic extent and demographic consequences of fatalities caused by renewable energy facilities. Geospatial analyses of δ(2) H values obtained from feathers showed that ≥25% of these APWRA-killed eagles were recent immigrants to the population, most from long distances away (>100 km). Data from nuclear genes indicated this subset of immigrant eagles was genetically similar to birds identified as locals from the δ(2) H data. Demographic models implied that in the face of this mortality, the apparent stability of the local Golden Eagle population was maintained by continental-scale immigration. These analyses demonstrate that ecosystem management decisions concerning the effects of local-scale renewable energy can have continental-scale consequences.

  7. Golden Eagle fatalities and the continental-scale consequences of local wind-energy generation

    USGS Publications Warehouse

    Katzner, Todd E.; Nelson, David M.; Braham, Melissa; Doyle, Jacqueline M.; Fernandez, Nadia B.; Duerr, Adam E.; Bloom, Peter H.; Fitzpatrick, Matthew C.; Miller, Tricia A.; Culver, Renee C. E.; Braswell, Loan; DeWoody, J. Andrew

    2017-01-01

    Renewable energy production is expanding rapidly despite mostly unknown environmental effects on wildlife and habitats. We used genetic and stable isotope data collected from Golden Eagles (Aquila chrysaetos) killed at the Altamont Pass Wind Resource Area (APWRA) in California in demographic models to test hypotheses about the geographic extent and demographic consequences of fatalities caused by renewable energy facilities. Geospatial analyses of δ2H values obtained from feathers showed that ≥25% of these APWRA-killed eagles were recent immigrants to the population, most from long distances away (>100 km). Data from nuclear genes indicated this subset of immigrant eagles was genetically similar to birds identified as locals from the δ2H data. Demographic models implied that in the face of this mortality, the apparent stability of the local Golden Eagle population was maintained by continental-scale immigration. These analyses demonstrate that ecosystem management decisions concerning the effects of local-scale renewable energy can have continental-scale consequences.

  8. Experimental insights into the scaling and variability of local tsunamis triggered by giant subduction megathrust earthquakes

    NASA Astrophysics Data System (ADS)

    Rosenau, Matthias; Nerlich, Rainer; Brune, Sascha; Oncken, Onno

    2010-09-01

    Giant subduction megathrust earthquakes of magnitude 9 and larger pose a significant tsunami hazard in coastal regions. In order to test and improve empirical tsunami forecast models and to explore the susceptibility of different subduction settings we here analyze the scaling of subduction earthquake-triggered tsunamis in the near field and their variability related to source heterogeneities. We base our analysis on a sequence of 50 experimentally simulated great to giant (Mw = 8.3-9.4) subduction megathrust earthquakes generated using an elastoplastic analog model. Experimentally observed surface deformation is translated to local tsunami runup using linear wave theory. We find that the intrinsic scaling of local tsunami runup is characterized by a linear relationship to peak earthquake slip, an exponential relationship to moment magnitude, and an inverse power law relationship to fore-arc slope. Tsunami variability is controlled by coseismic slip heterogeneity and strain localization within the fore-arc wedge and is characterized by a coefficient of variation Cv ˜ 0.5. Wave breaking modifies the scaling behavior of tsunamis triggered by the largest (Mw > 8.5) events in subduction settings with shallow dipping (<1-2°) fore-arc slopes, limits tsunami runup to <30 m, and reduces its variability to Cv ˜ 0.2. The resulting effective scaling relationships are validated against historical events and numerical simulations and reproduce empirical scaling relationships. The latter appear as robust and liberal estimates of runup up to magnitude Mw = 9.5. A global assessment of tsunami susceptibility suggests that accretionary plate margins are more prone to tsunami hazard than erosive margins.

  9. Insight on invasions and resilience derived from spatiotemporal discontinuities of biomass at local and regional scales

    USGS Publications Warehouse

    Angeler, David G.; Allen, Criag R.; Johnson, Richard K.

    2012-01-01

    Understanding the social and ecological consequences of species invasions is complicated by nonlinearities in processes, and differences in process and structure as scale is changed. Here we use discontinuity analyses to investigate nonlinear patterns in the distribution of biomass of an invasive nuisance species that could indicate scale-specific organization. We analyze biomass patterns in the flagellate Gonyostomum semen (Raphidophyta) in 75 boreal lakes during an 11-year period (1997-2007). With simulations using a unimodal null model and cluster analysis, we identified regional groupings of lakes based on their biomass patterns. We evaluated the variability of membership of individual lakes in regional biomass groups. Temporal trends in local and regional discontinuity patterns were analyzed using regressions and correlations with environmental variables that characterize nutrient conditions, acidity status, temperature variability, and water clarity. Regionally, there was a significant increase in the number of biomass groups over time, indicative of an increased number of scales at which algal biomass organizes across lakes. This increased complexity correlated with the invasion history of G. semen and broad-scale environmental change (recovery from acidification). Locally, no consistent patterns of lake membership to regional biomass groups were observed, and correlations with environmental variables were lake specific. The increased complexity of regional biomass patterns suggests that processes that act within or between scales reinforce the presence of G. semen and its potential to develop high-biomass blooms in boreal lakes. Emergent regional patterns combined with locally stochastic dynamics suggest a bleak future for managing G. semen, and more generally why invasive species can be ecologically successful.

  10. A Data-Driven Point Cloud Simplification Framework for City-Scale Image-Based Localization.

    PubMed

    Cheng, Wentao; Lin, Weisi; Zhang, Xinfeng; Goesele, Michael; Sun, Ming-Ting

    2017-01-01

    City-scale 3D point clouds reconstructed via structure-from-motion from a large collection of Internet images are widely used in the image-based localization task to estimate a 6-DOF camera pose of a query image. Due to prohibitive memory footprint of city-scale point clouds, image-based localization is difficult to be implemented on devices with limited memory resources. Point cloud simplification aims to select a subset of points to achieve a comparable localization performance using the original point cloud. In this paper, we propose a data-driven point cloud simplification framework by taking it as a weighted K-Cover problem, which mainly includes two complementary parts. First, a utility-based parameter determination method is proposed to select a reasonable parameter K for K-Cover-based approaches by evaluating the potential of a point cloud for establishing sufficient 2D-3D feature correspondences. Second, we formulate the 3D point cloud simplification problem as a weighted K-Cover problem, and propose an adaptive exponential weight function based on the visibility probability of 3D points. The experimental results on three popular datasets demonstrate that the proposed point cloud simplification framework outperforms the state-of-the-art methods for the image-based localization application with a well predicted parameter in the K-Cover problem.

  11. Global meta-analysis reveals no net change in local-scale plant biodiversity over time

    PubMed Central

    Vellend, Mark; Baeten, Lander; Myers-Smith, Isla H.; Elmendorf, Sarah C.; Beauséjour, Robin; Brown, Carissa D.; De Frenne, Pieter; Verheyen, Kris; Wipf, Sonja

    2013-01-01

    Global biodiversity is in decline. This is of concern for aesthetic and ethical reasons, but possibly also for practical reasons, as suggested by experimental studies, mostly with plants, showing that biodiversity reductions in small study plots can lead to compromised ecosystem function. However, inferring that ecosystem functions will decline due to biodiversity loss in the real world rests on the untested assumption that such loss is actually occurring at these small scales in nature. Using a global database of 168 published studies and >16,000 nonexperimental, local-scale vegetation plots, we show that mean temporal change in species diversity over periods of 5–261 y is not different from zero, with increases at least as likely as declines over time. Sites influenced primarily by plant species’ invasions showed a tendency for declines in species richness, whereas sites undergoing postdisturbance succession showed increases in richness over time. Other distinctions among studies had little influence on temporal richness trends. Although maximizing diversity is likely important for maintaining ecosystem function in intensely managed systems such as restored grasslands or tree plantations, the clear lack of any general tendency for plant biodiversity to decline at small scales in nature directly contradicts the key assumption linking experimental results to ecosystem function as a motivation for biodiversity conservation in nature. How often real world changes in the diversity and composition of plant communities at the local scale cause ecosystem function to deteriorate, or actually to improve, remains unknown and is in critical need of further study. PMID:24167259

  12. Global meta-analysis reveals no net change in local-scale plant biodiversity over time.

    PubMed

    Vellend, Mark; Baeten, Lander; Myers-Smith, Isla H; Elmendorf, Sarah C; Beauséjour, Robin; Brown, Carissa D; De Frenne, Pieter; Verheyen, Kris; Wipf, Sonja

    2013-11-26

    Global biodiversity is in decline. This is of concern for aesthetic and ethical reasons, but possibly also for practical reasons, as suggested by experimental studies, mostly with plants, showing that biodiversity reductions in small study plots can lead to compromised ecosystem function. However, inferring that ecosystem functions will decline due to biodiversity loss in the real world rests on the untested assumption that such loss is actually occurring at these small scales in nature. Using a global database of 168 published studies and >16,000 nonexperimental, local-scale vegetation plots, we show that mean temporal change in species diversity over periods of 5-261 y is not different from zero, with increases at least as likely as declines over time. Sites influenced primarily by plant species' invasions showed a tendency for declines in species richness, whereas sites undergoing postdisturbance succession showed increases in richness over time. Other distinctions among studies had little influence on temporal richness trends. Although maximizing diversity is likely important for maintaining ecosystem function in intensely managed systems such as restored grasslands or tree plantations, the clear lack of any general tendency for plant biodiversity to decline at small scales in nature directly contradicts the key assumption linking experimental results to ecosystem function as a motivation for biodiversity conservation in nature. How often real world changes in the diversity and composition of plant communities at the local scale cause ecosystem function to deteriorate, or actually to improve, remains unknown and is in critical need of further study.

  13. FEM × DEM: a new efficient multi-scale approach for geotechnical problems with strain localization

    NASA Astrophysics Data System (ADS)

    Nguyen, Trung Kien; Claramunt, Albert Argilaga; Caillerie, Denis; Combe, Gaël; Dal Pont, Stefano; Desrues, Jacques; Richefeu, Vincent

    2017-06-01

    The paper presents a multi-scale modeling of Boundary Value Problem (BVP) approach involving cohesive-frictional granular materials in the FEM × DEM multi-scale framework. On the DEM side, a 3D model is defined based on the interactions of spherical particles. This DEM model is built through a numerical homogenization process applied to a Volume Element (VE). It is then paired with a Finite Element code. Using this numerical tool that combines two scales within the same framework, we conducted simulations of biaxial and pressuremeter tests on a cohesive-frictional granular medium. In these cases, it is known that strain localization does occur at the macroscopic level, but since FEMs suffer from severe mesh dependency as soon as shear band starts to develop, the second gradient regularization technique has been used. As a consequence, the objectivity of the computation with respect to mesh dependency is restored.

  14. The Mountain Invasion Research Network (MIREN): Linking Local and Global Scales for Addressing an Ecological Consequence of Global Change

    Treesearch

    Christoph Kueffer; Curtis Daehler; Hansjörg Dietz; Keith McDougall; Catherine Parks; Aníbal Pauchard; Lisa Rew

    2014-01-01

    Many modern environmental problems span vastly different spatial scales, from the management of local ecosystems to understanding globally interconnected processes, and addressing them through international policy. MIREN tackles one such “glocal” (global/local) environmental problem – plant invasions in mountains – through a transdisciplinary, multi-scale learning...

  15. 2 Micrometers InAsSb Quantum-dot Lasers

    NASA Technical Reports Server (NTRS)

    Qiu, Yueming; Uhl, David; Keo, Sam

    2004-01-01

    InAsSb quantum-dot lasers near 2 micrometers were demonstrated in cw operation at room temperature with a threshold current density of 733 A,/cm(sup 2), output power of 3 mW/facet and a differential quantum efficiency of 13%.

  16. High-Energy 2-Micrometers Doppler Lidar for Wind Measurements

    NASA Technical Reports Server (NTRS)

    Koch, Grady J.; Beyon, Jeffrey Y.; Barnes, Bruce W.; Petros, Mulugeta; Yu, Jirong; Amzajerdian, Farzin; Kavaya, Michael J.; Singh, Upendra N.

    2006-01-01

    High-energy 2-micrometer wavelength lasers have been incorporated in a prototype coherent Doppler lidar to test component technologies and explore applications for remote sensing of the atmosphere. Design of the lidar is presented including aspects in the laser transmitter, receiver, photodetector, and signal processing. Calibration tests and sample atmospheric data are presented on wind and aerosol profiling.

  17. 2 Micrometers InAsSb Quantum-dot Lasers

    NASA Technical Reports Server (NTRS)

    Qiu, Yueming; Uhl, David; Keo, Sam

    2004-01-01

    InAsSb quantum-dot lasers near 2 micrometers were demonstrated in cw operation at room temperature with a threshold current density of 733 A,/cm(sup 2), output power of 3 mW/facet and a differential quantum efficiency of 13%.

  18. Subtle Ecological Gradient in the Tropics Triggers High Species-Turnover in a Local Geographical Scale

    PubMed Central

    Nguyen, Dinh T.

    2016-01-01

    Our perception of diversity, including both alpha- and beta-diversity components, depends on spatial scale. Studies of spatial variation of the latter are just starting, with a paucity of research on beta-diversity patterns at smaller scales. Understanding these patterns and the processes shaping the distribution of diversity is critical to describe this diversity, but it is paramount in conservation too. Here, we investigate the diversity and structure of a tropical community of herbivorous beetles at a reduced local scale of some 10 km2, evaluating the effect of a small, gradual ecological change on this structure. We sampled leaf beetles in the Núi Chúa National Park (S Vietnam), studying changes in alpha- and beta-diversity across an elevation gradient up to 500 m, encompassing the ecotone between critically endangered lowland dry deciduous forest and mixed evergreen forest at higher elevations. Leaf beetle diversity was assessed using several molecular tree-based species delimitation approaches (with mtDNA cox1 data), species richness using rarefaction and incidence-based diversity indexes, and beta-diversity was investigated decomposing the contribution of species turnover and nestedness. We documented 155 species in the area explored and species-richness estimates 1.5–2.0x higher. Species diversity was similar in both forest types and changes in alpha-diversity along the elevation gradient showed an expected local increase of diversity in the ecotone. Beta-diversity was high among forest paths (average Sørensen's dissimilarity = 0.694) and, tentatively fixing at 300 m the boundary between otherwise continuous biomes, demonstrated similarly high beta-diversity (Sørensen's dissimilarity = 0.581), with samples clustering according to biome/elevation. Highly relevant considering the local scale of the study, beta-diversity had a high contribution of species replacement among locales (54.8%) and between biomes (79.6%), suggesting environmental heterogeneity

  19. Local versus landscape-scale effects of savanna trees on grasses

    USGS Publications Warehouse

    Riginos, C.; Grace, J.B.; Augustine, D.J.; Young, T.P.

    2009-01-01

    1. Savanna ecosystems - defined by the coexistence of trees and grasses - cover more than one-fifth the world's land surface and harbour most of the world's rangelands, livestock and large mammal diversity. Savanna trees can have a variety of effects on grasses, with consequences for the wild and domestic herbivores that depend on them. 2.Studies of these effects have focused on two different spatial scales. At the scale of individual trees, many studies have shown net positive effects of trees on sub-canopy grass nutrient concentrations and biomass. At the landscape scale, other studies have shown negative effects of high tree densities on grass productivity. These disparate results have led to different conclusions about the effects of trees on forage quality and ungulate nutrition in savannas. 3.We integrate these approaches by examining the effects of trees on grasses at both spatial scales and across a range of landscape-scale tree densities. 4.We quantified grass biomass, species composition and nutrient concentrations in these different contexts in an Acacia drepanolobium savanna in Laikipia, Kenya. Individual trees had positive effects on grass biomass, most likely because trees enrich soil nitrogen. Grass leaf phosphorus in sub-canopy areas, however, was depressed. The effects of individual trees could explain the effects of increasing landscape-scale tree cover for the biomass of only two of the four dominant grass species. 5.The negative effects of trees on grass and soil phosphorus, combined with depressed grass productivity in areas of high tree cover, suggest that ungulate nutrition may be compromised in areas with many trees. 6.Synthesis. We conclude that few, isolated trees may have positive local effects on savanna grasses and forage, but in areas of high tree density the negative landscape-scale effects of trees are likely to outweigh these positive effects. In savannas and other patchy landscapes, attempts to predict the consequences of changes

  20. Length Scales of Local Glass Transition Temperature Gradients Near Soft and Hard Polymer-Polymer Interfaces

    NASA Astrophysics Data System (ADS)

    Baglay, Roman; Roth, Connie

    Polymer-polymer interfaces are ubiquitous in polymer blends and block copolymers, while opening up another avenue for the study of interfacial perturbations to the local glass transition temperature Tg(z). We have previously reported the full local Tg(z) profile across a glassy-rubbery polymer interface between polystyrene (PS) and poly(n-butyl methacrylate) (PnBMA), an 80 K difference in bulk Tg [Baglay & Roth, J Chem Phys 2015, 143, 111101]. By using local fluorescence measurements, we revealed how the Tg(z) profile extends hundreds of nanometers away from the interface showing an asymmetric behavior penetrating deeper into the glassy PS side relative to the composition profile. Here, we extend these measurements to investigate how the local Tg profile in PS varies when in contact with a variety of immiscible polymers whose Tgs vary between +90 K and -80 K relative to the bulk Tg of PS, so-called hard vs. soft confinement. The data reveal that the onset of local Tg deviation from bulk in PS occurs at two distinct length scales, which depend on whether PS is the low Tg component (hard confinement) or the high Tg component (soft confinement). In addition, we explore the influence of finite system size on the range of dynamics by the introduction of periodic boundary conditions, as is commonly encountered in computer simulations or block copolymer systems.

  1. Base line for determining local, small-scale vertical movements in Louisiana

    SciTech Connect

    Trahan, D.B.

    1983-01-01

    Subsidence in Louisiana is a result of many factors ranging from local, man-induced to regional, large-scale processes. The measurement of local, man-induced subsidence is especially critical in areas with high rates of land loss. In order to measure local vertical movement, absolute historical geodetic movements have been estimated by adjusting all movements along the first-order vertical control network from northeast to southwest Louisiana as related to the Monroe Uplift. The adjustment will serve as a base line by which local subsidence or uplift can be measured. A generalized trend of increasing subsidence to the south in Louisiana is probably a reflection of increasing sediment thickness and weight toward the AXIS of the Gulf Coast Basin. Anomalous values as low as -17.6 mm/y occur superjacent to the position of Pleistocene and Holocene fluvial elements. Positive movement, up to +4.1 mm/y, has been found associated with the Iberian structural axis in south-central Louisiana. Land subsidence due to natural causes may far outweigh subsidence resulting from fluid withdrawal or depressurization of geopressured aquifers. The effects of regional and local natural processes should not be underestimated in any systematic approach to measuring subsidence. 13 references, 7 figures.

  2. Energy Dependence and Scaling Property of Localization Length near a Gapped Flat Band

    NASA Astrophysics Data System (ADS)

    Ge, Li; Tureci, Hakan

    Using a tight-binding model for a one-dimensional Lieb lattice, we show that the localization length near a gapped flat band behaves differently from the typical Urbach tail in a band gap: instead of reducing monotonically as the energy E moves away from the flat band energy Ef, the presence of the flat band causes a nonmonotonic energy dependence of the localization length. This energy dependence follows a scaling property when the energy is within the spread (W) of uniformly distributed diagonal disorder, i.e. the localization length is only a function of (E-Ef)/W. Several other lattices are compared to distinguish the effect of the flat band on the localization length, where we eliminate, shift, or duplicate the flat band, without changing the dispersion relations of other bands. Using the top right element of the Green's matrix, we derive an analytical relation between the density of states and the localization length, which shines light on these properties of the latter, including a summation rule for its inverse. This work is partially supported by NSF under Grant No. DMR-1506987.

  3. Estimating local scaling properties for the classification of interstitial lung disease patterns

    NASA Astrophysics Data System (ADS)

    Huber, Markus B.; Nagarajan, Mahesh B.; Leinsinger, Gerda; Ray, Lawrence A.; Wismueller, Axel

    2011-03-01

    Local scaling properties of texture regions were compared in their ability to classify morphological patterns known as 'honeycombing' that are considered indicative for the presence of fibrotic interstitial lung diseases in high-resolution computed tomography (HRCT) images. For 14 patients with known occurrence of honeycombing, a stack of 70 axial, lung kernel reconstructed images were acquired from HRCT chest exams. 241 regions of interest of both healthy and pathological (89) lung tissue were identified by an experienced radiologist. Texture features were extracted using six properties calculated from gray-level co-occurrence matrices (GLCM), Minkowski Dimensions (MDs), and the estimation of local scaling properties with Scaling Index Method (SIM). A k-nearest-neighbor (k-NN) classifier and a Multilayer Radial Basis Functions Network (RBFN) were optimized in a 10-fold cross-validation for each texture vector, and the classification accuracy was calculated on independent test sets as a quantitative measure of automated tissue characterization. A Wilcoxon signed-rank test was used to compare two accuracy distributions including the Bonferroni correction. The best classification results were obtained by the set of SIM features, which performed significantly better than all the standard GLCM and MD features (p < 0.005) for both classifiers with the highest accuracy (94.1%, 93.7%; for the k-NN and RBFN classifier, respectively). The best standard texture features were the GLCM features 'homogeneity' (91.8%, 87.2%) and 'absolute value' (90.2%, 88.5%). The results indicate that advanced texture features using local scaling properties can provide superior classification performance in computer-assisted diagnosis of interstitial lung diseases when compared to standard texture analysis methods.

  4. Observation impact in a convective-scale localized ensemble transform Kalman filter

    NASA Astrophysics Data System (ADS)

    Sommer, Matthias; Weissmann, Martin

    2014-05-01

    In operational weather forecasting, knowledge about observation impact, i.e. the contribution of specific observations to forecast error reduction, is crucial to refine the observing and data assimilation system. However, assessing this quantity by direct computation (data denial experiments) is usually not feasible because of the high computational cost. This has motivated the derivation of approximated forms of observation impact. If an adjoint model is available, established methods exist that give a reliable estimate. On the other hand, in an ensemble-based environment, a recently developed algorithm [1] uses the analysis and forecast deviations to approximate observation impact. This has now for the first time been implemented in the convective-scale limited-area model COSMO and has been thoroughly verified with data-denial experiments [2]. It has been found that the difference to data denial is not significant (less than 10%) and accuracy can be expected to improve further when considering longer test periods. The peculiarities for an application on this scale include a strongly non-linear behavior and a typically small localization length. While the former can be expected to be reasonably addressed by the ensemble algorithm, the latter imposes constraints for an appropriate choice of lead time. It could also be shown that valuable information, such as the detection of disadvantageous observations can be gained. This presentation shows the feasibility and distinctive features of the method for a convective-scale setup, gives examples from a pre-operational application at Deutscher Wetterdienst, and discusses the sensitivity to lead time, localization and verification norm. References: [1] E. Kalnay, Y. Ota, T. Miyoshi, and J. Liu. A simpler formulation of forecast sensitivity to observations: application to ensemble Kalman filters. Tellus A 64, 2012. [2] M. Sommer and M. Weissmann. Observation impact in a convective-scale localized ensemble transform Kalman

  5. Local and Catchment-Scale Water Storage Changes in Northern Benin Deduced from Gravity Monitoring at Various Time-Scales

    NASA Astrophysics Data System (ADS)

    Hinderer, J.; Hector, B.; Séguis, L.; Descloitres, M.; Cohard, J.; Boy, J.; Calvo, M.; Rosat, S.; Riccardi, U.; Galle, S.

    2013-12-01

    Water storage changes (WSC) are investigated by the mean of gravity monitoring in Djougou, northern Benin, in the frame of the GHYRAF (Gravity and Hydrology in Africa) project. In this area, WSC are 1) part of the control system for evapotranspiration (ET) processes, a key variable of the West-African monsoon cycle and 2) the state variable for resource management, a critical issue in storage-poor hard rock basement contexts such as in northern Benin. We show the advantages of gravity monitoring for analyzing different processes in the water cycle involved at various time and space scales, using the main gravity sensors available today (FG5 absolute gravimeter, superconducting gravimeter -SG- and CG5 micro-gravimeter). The study area is also part of the long-term observing system AMMA-Catch, and thus under intense hydro-meteorological monitoring (rain, soil moisture, water table level, ET ...). Gravity-derived WSC are compared at all frequencies to hydrological data and to hydrological models calibrated on these data. Discrepancies are analyzed to discuss the pros and cons of each approach. Fast gravity changes (a few hours) are significant when rain events occur, and involve different contributions: rainfall itself, runoff, fast subsurface water redistribution, screening effect of the gravimeter building and local topography. We investigate these effects and present the statistical results of a set of rain events recorded with the SG installed in Djougou since July 2010. The intermediate time scale of gravity changes (a few days) is caused by ET and both vertical and horizontal water redistribution. The integrative nature of gravity measurements does not allow to separate these different contributions, and the screening from the shelter reduces our ability to retrieve ET values. Also, atmospheric corrections are critical at such frequencies, and deserve some specific attention. However, a quick analysis of gravity changes following rain events shows that the

  6. Variability of bed mobility in natural, gravel-bed channels and adjustments to sediment load at local and reach scales

    Treesearch

    Thomas E. Lisle; Jonathan M. Nelson; John Pitlick; Mary Ann Madej; Brent L. Barkett

    2000-01-01

    Abstract - Local variations in boundary shear stress acting on bed-surface particles control patterns of bed load transport and channel evolution during varying stream discharges. At the reach scale a channel adjusts to imposed water and sediment supply through mutual interactions among channel form, local grain size, and local flow dynamics that govern bed mobility...

  7. Global mental health and its discontents: an inquiry into the making of global and local scale.

    PubMed

    Bemme, Doerte; D'souza, Nicole A

    2014-12-01

    Global Mental Health's (GMH) proposition to "scale up" evidence-based mental health care worldwide has sparked a heated debate among transcultural psychiatrists, anthropologists, and GMH proponents; a debate characterized by the polarization of "global" and "local" approaches to the treatment of mental health problems. This article highlights the institutional infrastructures and underlying conceptual assumptions that are invested in the production of the "global" and the "local" as distinct, and seemingly incommensurable, scales. It traces how the conception of mental health as a "global" problem became possible through the emergence of Global Health, the population health metric DALY, and the rise of evidence-based medicine. GMH also advanced a moral argument to act globally emphasizing the notion of humanity grounded in a shared biology and the universality of human rights. However, despite the frequent criticism of GMH promoting the "bio"-medical model, we argue that novel logics have emerged which may be more important for establishing global applicability than arguments made in the name of "nature": the procedural standardization of evidence and the simplification of psychiatric expertise. Critical scholars, on the other hand, argue against GMH in the name of the "local"; a trope that underlines specificity, alterity, and resistance against global claims. These critics draw on the notions of "culture," "colonialism," the "social," and "community" to argue that mental health knowledge is locally contingent. Yet, paying attention to the divergent ways in which both sides conceptualize the "social" and "community" may point to productive spaces for an analysis of GMH beyond the "global/local" divide.

  8. Estimating riverine nutrient concentrations in agricultural catchments - Do we reduce uncertainty by using local scale data?

    NASA Astrophysics Data System (ADS)

    Capell, Rene; Hankin, Barry; Strömqvist, Johan; Lamb, Rob; Arheimer, Berit

    2017-04-01

    Nutrient transport models are important tools for large scale assessments of macro-nutrient fluxes (nitrate, phosphate) and thus can serve as support tool for environmental assessment and management. Results from model applications over large areas, i.e. on major river basin to continental scales can fill a gap where monitoring data is not available. However, both phosphate and nitrate transport are highly complex processes, and nutrient models must balance data requirements and process simplification. Data typically become increasingly sparse and less detailed with increasing spatial scale. Here, we compare model estimates of riverine nitrate concentrations in the Weaver-Dane basin (UK) and to evaluate the role of available environmental data sources for model performance by using (a) open environmental data sources available at European scale and (b) closed data sources which are more localised and typically not openly available. In particular, we aim to evaluate, how model structure, spatial model resolution, climate forcing products, and land use and management information impact on model-estimated nitrate concentrations. We use the European rainfall-runoff and nutrient model E-HYPE (http://hypeweb.smhi.se/europehype/about/) as a baseline large-scale model built on open data sources, and compare with more detailed model set-ups in different configurations using local data. Nitrate estimates are compared using a GLUE uncertainty framework.

  9. Local morphologic scale: application to segmenting tumor infiltrating lymphocytes in ovarian cancer TMAs

    NASA Astrophysics Data System (ADS)

    Janowczyk, Andrew; Chandran, Sharat; Feldman, Michael; Madabhushi, Anant

    2011-03-01

    In this paper we present the concept and associated methodological framework for a novel locally adaptive scale notion called local morphological scale (LMS). Broadly speaking, the LMS at every spatial location is defined as the set of spatial locations, with associated morphological descriptors, which characterize the local structure or heterogeneity for the location under consideration. More specifically, the LMS is obtained as the union of all pixels in the polygon obtained by linking the final location of trajectories of particles emanating from the location under consideration, where the path traveled by originating particles is a function of the local gradients and heterogeneity that they encounter along the way. As these particles proceed on their trajectory away from the location under consideration, the velocity of each particle (i.e. do the particles stop, slow down, or simply continue around the object) is modeled using a physics based system. At some time point the particle velocity goes to zero (potentially on account of encountering (a) repeated obstructions, (b) an insurmountable image gradient, or (c) timing out) and comes to a halt. By using a Monte-Carlo sampling technique, LMS is efficiently determined through parallelized computations. LMS is different from previous local scale related formulations in that it is (a) not a locally connected sets of pixels satisfying some pre-defined intensity homogeneity criterion (generalized-scale), nor is it (b) constrained by any prior shape criterion (ball-scale, tensor-scale). Shape descriptors quantifying the morphology of the particle paths are used to define a tensor LMS signature associated with every spatial image location. These features include the number of object collisions per particle, average velocity of a particle, and the length of the individual particle paths. These features can be used in conjunction with a supervised classifier to correctly differentiate between two different object

  10. Dispersive mixing dynamics of dense miscible plumes: natural perturbation initiation by local-scale heterogeneities

    NASA Astrophysics Data System (ADS)

    Schincariol, Robert A.

    1998-10-01

    Two-dimensional, coupled variable-density flow and transport simulations with heterogeneous media advance understanding of how local-scale non-idealities create and control instabilities. Dense plumes (5000 mg l -1 NaCl) are introduced into a domain (1.50×0.56 m) with synthetically generated permeability fields. Simulations with the first set of realizations [mean permeability ( k)=5.7×10 -11 m 2, ln( k) variance=0.25, longitudinal correlation length ( τx)=0.10 m, transverse correlation length ( τz)=0.02 m] illustrate how the lower plume boundary is naturally perturbed by local-scale heterogeneities. Some of these perturbations are stable, some are highly bounded or pseudostable in certain portions of the field, while others rapidly destabilize the lower plume boundary. Even with similar macroscopic field statistics, widely varying degrees of density-induced mixing occur among different realizations. Unstable perturbations result in complex mixing features, such as coalescing of instability lobes as different portions of the plume sample various regions of the permeability field. Such mixing greatly enhances and controls the dispersion process. Based on the control that local field characteristics exhibit on instability growth and decay, the applicability of stability criteria to plume-type displacements in natural heterogeneous media is likely inappropriate. Additional simulations employing fields of lower variance and lower densities illustrate the delicate balance between these variables and the ability of the field to propagate unstable perturbations.

  11. Performance of Extended Local Clustering Organization (LCO) for Large Scale Job-Shop Scheduling Problem (JSP)

    NASA Astrophysics Data System (ADS)

    Konno, Yohko; Suzuki, Keiji

    This paper describes an approach to development of a solution algorithm of a general-purpose for large scale problems using “Local Clustering Organization (LCO)” as a new solution for Job-shop scheduling problem (JSP). Using a performance effective large scale scheduling in the study of usual LCO, a solving JSP keep stability induced better solution is examined. In this study for an improvement of a performance of a solution for JSP, processes to a optimization by LCO is examined, and a scheduling solution-structure is extended to a new solution-structure based on machine-division. A solving method introduced into effective local clustering for the solution-structure is proposed as an extended LCO. An extended LCO has an algorithm which improves scheduling evaluation efficiently by clustering of parallel search which extends over plural machines. A result verified by an application of extended LCO on various scale of problems proved to conduce to minimizing make-span and improving on the stable performance.

  12. Hi-fidelity multi-scale local processing for visually optimized far-infrared Herschel images

    NASA Astrophysics Data System (ADS)

    Li Causi, G.; Schisano, E.; Liu, S. J.; Molinari, S.; Di Giorgio, A.

    2016-07-01

    In the context of the "Hi-Gal" multi-band full-plane mapping program for the Galactic Plane, as imaged by the Herschel far-infrared satellite, we have developed a semi-automatic tool which produces high definition, high quality color maps optimized for visual perception of extended features, like bubbles and filaments, against the high background variations. We project the map tiles of three selected bands onto a 3-channel panorama, which spans the central 130 degrees of galactic longitude times 2.8 degrees of galactic latitude, at the pixel scale of 3.2", in cartesian galactic coordinates. Then we process this image piecewise, applying a custom multi-scale local stretching algorithm, enforced by a local multi-scale color balance. Finally, we apply an edge-preserving contrast enhancement to perform an artifact-free details sharpening. Thanks to this tool, we have thus produced a stunning giga-pixel color image of the far-infrared Galactic Plane that we made publicly available with the recent release of the Hi-Gal mosaics and compact source catalog.

  13. On the dominant uncertainty source of climate change projections at the local scale

    NASA Astrophysics Data System (ADS)

    Fatichi, Simone; Ivanov, Valeriy; Paschalis, Athanasios; Molnar, Peter; Rimkus, Stefan; Kim, Jongho; Peleg, Nadav; Burlando, Paolo; Caporali, Enrica

    2016-04-01

    Decision makers and stakeholders are usually concerned about climate change projections at local spatial scales and fine temporal resolutions. This contrasts with the reliability of climate models, which is typically higher at the global and regional scales, Therefore, there is a demand for advanced methodologies that offer the capability of transferring predictions of climate models and relative uncertainty to scales commensurate with practical applications and for higher order statistics (e.g., few square kilometres and sub-daily scale). A stochastic downscaling technique that makes use of an hourly weather generator (AWE-GEN) and of a Bayesian methodology to weight realizations from different climate models is used to generate local scale meteorological time series of plausible "futures". We computed factors of change from realizations of 32 climate models used in the Coupled Model Intercomparison Project Phase 5 (CMIP5) and for different emission scenarios (RCP 4.5 and RCP 8.5). Future climate projections for several meteorological variables (precipitation, air temperature, relative humidity, shortwave radiation) are simulated at three locations characterized by remarkably different climates, Zurich (Switzlerand), Miami and San Francisco (USA). The methodology is designed to partition three main sources of uncertainty: uncertainty due to climate models (model epistemic uncertainty), anthropogenic forcings (scenario uncertainty), and internal climate variability (stochastic uncertainty). The three types of uncertainty sources are considered as dependent, implicitly accounting for possible co-variances among the sources. For air temperature, the magnitude of the different uncertainty sources is comparable for mid-of-the-century projections, while scenario uncertainty dominates at large lead-times. The dominant source of uncertainty for changes in precipitation mean and extremes is internal climate variability, which is accounting for more than 80% of the total

  14. Downscaling large-scale circulation to local winter climate using neural network techniques

    NASA Astrophysics Data System (ADS)

    Cavazos Perez, Maria Tereza

    1998-12-01

    The severe impacts of climate variability on society reveal the increasing need for improving regional-scale climate diagnosis. A new downscaling approach for climate diagnosis is developed here. It is based on neural network techniques that derive transfer functions from the large-scale atmospheric controls to the local winter climate in northeastern Mexico and southeastern Texas during the 1985-93 period. A first neural network (NN) model employs time-lagged component scores from a rotated principal component analysis of SLP, 500-hPa heights, and 1000-500 hPa thickness as predictors of daily precipitation. The model is able to reproduce the phase and, to some decree, the amplitude of large rainfall events, reflecting the influence of the large-scale circulation. Large errors are found over the Sierra Madre, over the Gulf of Mexico, and during El Nino events, suggesting an increase in the importance of meso-scale rainfall processes. However, errors are also due to the lack of randomization of the input data and the absence of local atmospheric predictors such as moisture. Thus, a second NN model uses time-lagged specific humidity at the Earth's surface and at the 700 hPa level, SLP tendency, and 700-500 hPa thickness as input to a self-organizing map (SOM) that pre-classifies the atmospheric fields into different patterns. The results from the SOM classification document that negative (positive) anomalies of winter precipitation over the region are associated with: (1) weaker (stronger) Aleutian low; (2) stronger (weaker) North Pacific high; (3) negative (positive) phase of the Pacific North American pattern; and (4) La Nina (El Nino) events. The SOM atmospheric patterns are then used as input to a feed-forward NN that captures over 60% of the daily rainfall variance and 94% of the daily minimum temperature variance over the region. This demonstrates the ability of artificial neural network models to simulate realistic relationships on daily time scales. The

  15. Geographic variation in opinions on climate change at state and local scales in the USA

    NASA Astrophysics Data System (ADS)

    Howe, Peter D.; Mildenberger, Matto; Marlon, Jennifer R.; Leiserowitz, Anthony

    2015-06-01

    Addressing climate change in the United States requires enactment of national, state and local mitigation and adaptation policies. The success of these initiatives depends on public opinion, policy support and behaviours at appropriate scales. Public opinion, however, is typically measured with national surveys that obscure geographic variability across regions, states and localities. Here we present independently validated high-resolution opinion estimates using a multilevel regression and poststratification model. The model accurately predicts climate change beliefs, risk perceptions and policy preferences at the state, congressional district, metropolitan and county levels, using a concise set of demographic and geographic predictors. The analysis finds substantial variation in public opinion across the nation. Nationally, 63% of Americans believe global warming is happening, but county-level estimates range from 43 to 80%, leading to a diversity of political environments for climate policy. These estimates provide an important new source of information for policymakers, educators and scientists to more effectively address the challenges of climate change.

  16. MapReduce Based Personalized Locality Sensitive Hashing for Similarity Joins on Large Scale Data

    PubMed Central

    Wang, Jingjing; Lin, Chen

    2015-01-01

    Locality Sensitive Hashing (LSH) has been proposed as an efficient technique for similarity joins for high dimensional data. The efficiency and approximation rate of LSH depend on the number of generated false positive instances and false negative instances. In many domains, reducing the number of false positives is crucial. Furthermore, in some application scenarios, balancing false positives and false negatives is favored. To address these problems, in this paper we propose Personalized Locality Sensitive Hashing (PLSH), where a new banding scheme is embedded to tailor the number of false positives, false negatives, and the sum of both. PLSH is implemented in parallel using MapReduce framework to deal with similarity joins on large scale data. Experimental studies on real and simulated data verify the efficiency and effectiveness of our proposed PLSH technique, compared with state-of-the-art methods. PMID:26089861

  17. Identification and localization of fovea on colour fundus images using blur scales.

    PubMed

    Ganesan, Karthikeyan; Acharya, Rajendra U; Chua, Chua Kuang; Laude, Augustinus

    2014-09-01

    Identification of retinal landmarks is an important step in the extraction of anomalies in retinal fundus images. In the current study, we propose a technique to identify and localize the position of macula and hence the fovea avascular zone, in colour fundus images. The proposed method, based on varying blur scales in images, is independent of the location of other anatomical landmarks present in the fundus images. Experimental results have been provided using the open database MESSIDOR by validating our segmented regions using the dice coefficient, with ground truth segmentation provided by a human expert. Apart from testing the images on the entire MESSIDOR database, the proposed technique was also validated using 50 normal and 50 diabetic retinopathy chosen digital fundus images from the same database. A maximum overlap accuracy of 89.6%-93.8% and locational accuracy of 94.7%-98.9% was obtained for identification and localization of the fovea.

  18. Integral scale histogram local binary patterns for classification of narrow-band gastroenterology images.

    PubMed

    Riaz, Farhan; Ribeiro, Mario-Dinis; Pimentel-Nunes, Pedro; Coimbra, Miguel Tavares

    2013-01-01

    The introduction of various novel imaging technologies such as narrow-band imaging have posed novel image processing challenges to the design of computer assisted decision systems. In this paper, we propose an image descriptor referred to as integrated scale histogram local binary patterns. We propagate an aggregated histogram of local binary patterns of an image at various resolutions. This results in low dimensional feature vectors for the images while incorporating their multiresolution analysis. The descriptor was used to classify gastroenterology images into four distinct groups. Results produced by the proposed descriptor exhibit around 92% accuracy for classification of gastroenteroloy images outperforming other state-of-the-art methods, endorsing the effectiveness of the proposed descriptor.

  19. Scaling of high-field transport and localized heating in graphene transistors.

    PubMed

    Bae, Myung-Ho; Islam, Sharnali; Dorgan, Vincent E; Pop, Eric

    2011-10-25

    We use infrared thermal imaging and electrothermal simulations to find that localized Joule heating in graphene field-effect transistors on SiO(2) is primarily governed by device electrostatics. Hot spots become more localized (i.e., sharper) as the underlying oxide thickness is reduced, such that the average and peak device temperatures scale differently, with significant long-term reliability implications. The average temperature is proportional to oxide thickness, but the peak temperature is minimized at an oxide thickness of ∼90 nm due to competing electrostatic and thermal effects. We also find that careful comparison of high-field transport models with thermal imaging can be used to shed light on velocity saturation effects. The results shed light on optimizing heat dissipation and reliability of graphene devices and interconnects.

  20. An improved local immunization strategy for scale-free networks with a high degree of clustering

    NASA Astrophysics Data System (ADS)

    Xia, Lingling; Jiang, Guoping; Song, Yurong; Song, Bo

    2017-01-01

    The design of immunization strategies is an extremely important issue for disease or computer virus control and prevention. In this paper, we propose an improved local immunization strategy based on node's clustering which was seldom considered in the existing immunization strategies. The main aim of the proposed strategy is to iteratively immunize the node which has a high connectivity and a low clustering coefficient. To validate the effectiveness of our strategy, we compare it with two typical local immunization strategies on both real and artificial networks with a high degree of clustering. Simulations on these networks demonstrate that the performance of our strategy is superior to that of two typical strategies. The proposed strategy can be regarded as a compromise between computational complexity and immune effect, which can be widely applied in scale-free networks of high clustering, such as social network, technological networks and so on. In addition, this study provides useful hints for designing optimal immunization strategy for specific network.

  1. MapReduce Based Personalized Locality Sensitive Hashing for Similarity Joins on Large Scale Data.

    PubMed

    Wang, Jingjing; Lin, Chen

    2015-01-01

    Locality Sensitive Hashing (LSH) has been proposed as an efficient technique for similarity joins for high dimensional data. The efficiency and approximation rate of LSH depend on the number of generated false positive instances and false negative instances. In many domains, reducing the number of false positives is crucial. Furthermore, in some application scenarios, balancing false positives and false negatives is favored. To address these problems, in this paper we propose Personalized Locality Sensitive Hashing (PLSH), where a new banding scheme is embedded to tailor the number of false positives, false negatives, and the sum of both. PLSH is implemented in parallel using MapReduce framework to deal with similarity joins on large scale data. Experimental studies on real and simulated data verify the efficiency and effectiveness of our proposed PLSH technique, compared with state-of-the-art methods.

  2. Automated Image Retrieval of Chest CT Images Based on Local Grey Scale Invariant Features.

    PubMed

    Arrais Porto, Marcelo; Cordeiro d'Ornellas, Marcos

    2015-01-01

    Textual-based tools are regularly employed to retrieve medical images for reading and interpretation using current retrieval Picture Archiving and Communication Systems (PACS) but pose some drawbacks. All-purpose content-based image retrieval (CBIR) systems are limited when dealing with medical images and do not fit well into PACS workflow and clinical practice. This paper presents an automated image retrieval approach for chest CT images based local grey scale invariant features from a local database. Performance was measured in terms of precision and recall, average retrieval precision (ARP), and average retrieval rate (ARR). Preliminary results have shown the effectiveness of the proposed approach. The prototype is also a useful tool for radiology research and education, providing valuable information to the medical and broader healthcare community.

  3. Fine-scale local adaptation in an invasive freshwater fish has evolved in contemporary time

    PubMed Central

    Westley, Peter A. H.; Ward, Eric J.; Fleming, Ian A.

    2013-01-01

    Adaptive evolutionary change in only a few generations can increase the ability of non-native invasive species to spread, and yet adaptive divergence is rarely assessed in recently established populations. In this study, we experimentally test for evidence of fine-scale local adaptation in juvenile survival and growth among three populations of an invasive freshwater fish with reciprocal transplants and common-garden experiments. Despite intrinsic differences in habitat quality, in two of three populations we detected evidence of increased survival in ‘home’ versus ‘away’ environments with a Bayesian occupancy model fitted to mark–recapture data. We found support for the ‘local’ versus ‘foreign’ criterion of local adaptation as 14 of 15 pairwise comparisons of performance were consistent with local adaptation (p < 0.001). Patterns in growth were less clear, though we detected evidence of location- and population-level effects. Although the agents of divergent ecological selection are not known in this system, our results combine to indicate that adaptive divergence—reflected by higher relative survival of local individuals—can occur in a small number of generations and only a few kilometres apart on the landscape. PMID:23193126

  4. Quantum chaos of a particle in a square well: competing length scales and dynamical localization.

    PubMed

    Sankaranarayanan, R; Lakshminarayan, A; Sheorey, V B

    2001-10-01

    The classical and quantum dynamics of a particle trapped in a one-dimensional infinite square well with a time-periodic pulsed field is investigated. This is a two-parameter non-KAM (Kolmogorov-Arnold-Moser) generalization of the kicked rotor, which can be seen as the standard map of particles subjected to both smooth and hard potentials. The virtue of the generalization lies in the introduction of an extra parameter R, which is the ratio of two length scales, namely, the well width and the field wavelength. If R is a noninteger the dynamics is discontinuous and non-KAM. We have explored the role of R in controlling the localization properties of the eigenstates. In particular, the connection between classical diffusion and localization is found to generalize reasonably well. In unbounded chaotic systems such as these, while the nearest neighbor spacing distribution of the eigenvalues is less sensitive to the nature of the classical dynamics, the distribution of participation ratios of the eigenstates proves to be a sensitive measure; in the chaotic regimes the latter is log-normal. We find that the tails of the well converged localized states are exponentially localized despite the discontinuous dynamics while the bulk part shows fluctuations that tend to be closer to random matrix theory predictions. Time evolving states show considerable R dependence, and tuning R to enhance classical diffusion can lead to significantly larger quantum diffusion for the same field strengths, an effect that is potentially observable in present day experiments.

  5. Scale-adaptive tensor algebra for local many-body methods of electronic structure theory

    SciTech Connect

    Liakh, Dmitry I

    2014-01-01

    While the formalism of multiresolution analysis (MRA), based on wavelets and adaptive integral representations of operators, is actively progressing in electronic structure theory (mostly on the independent-particle level and, recently, second-order perturbation theory), the concepts of multiresolution and adaptivity can also be utilized within the traditional formulation of correlated (many-particle) theory which is based on second quantization and the corresponding (generally nonorthogonal) tensor algebra. In this paper, we present a formalism called scale-adaptive tensor algebra (SATA) which exploits an adaptive representation of tensors of many-body operators via the local adjustment of the basis set quality. Given a series of locally supported fragment bases of a progressively lower quality, we formulate the explicit rules for tensor algebra operations dealing with adaptively resolved tensor operands. The formalism suggested is expected to enhance the applicability and reliability of local correlated many-body methods of electronic structure theory, especially those directly based on atomic orbitals (or any other localized basis functions).

  6. Gene expression clines reveal local adaptation and associated trade-offs at a continental scale

    PubMed Central

    Porcelli, Damiano; Westram, Anja M.; Pascual, Marta; Gaston, Kevin J.; Butlin, Roger K.; Snook, Rhonda R.

    2016-01-01

    Local adaptation, where fitness in one environment comes at a cost in another, should lead to spatial variation in trade-offs between life history traits and may be critical for population persistence. Recent studies have sought genomic signals of local adaptation, but often have been limited to laboratory populations representing two environmentally different locations of a species’ distribution. We measured gene expression, as a proxy for fitness, in males of Drosophila subobscura, occupying a 20° latitudinal and 11 °C thermal range. Uniquely, we sampled six populations and studied both common garden and semi-natural responses to identify signals of local adaptation. We found contrasting patterns of investment: transcripts with expression positively correlated to latitude were enriched for metabolic processes, expressed across all tissues whereas negatively correlated transcripts were enriched for reproductive processes, expressed primarily in testes. When using only the end populations, to compare our results to previous studies, we found that locally adaptive patterns were obscured. While phenotypic trade-offs between metabolic and reproductive functions across widespread species are well-known, our results identify underlying genetic and tissue responses at a continental scale that may be responsible for this. This may contribute to understanding population persistence under environmental change. PMID:27599812

  7. Entanglement scaling of excited states in large one-dimensional many-body localized systems

    NASA Astrophysics Data System (ADS)

    Kennes, D. M.; Karrasch, C.

    2016-06-01

    We study the properties of excited states in one-dimensional many-body localized (MBL) systems using a matrix product state algorithm. First, the method is tested for a large disordered noninteracting system, where for comparison we compute a quasiexact reference solution via a Monte Carlo sampling of the single-particle levels. Thereafter, we present extensive data obtained for large interacting systems of L ˜100 sites and large bond dimensions χ ˜1700 , which allows us to quantitatively analyze the scaling behavior of the entanglement S in the system. The MBL phase is characterized by a logarithmic growth S (L )˜log(L ) over a large scale separating the regimes where volume and area laws hold. We check the validity of the eigenstate thermalization hypothesis. Our results are consistent with the existence of a mobility edge.

  8. Scaling Theory of Entanglement at the Many-Body Localization Transition

    NASA Astrophysics Data System (ADS)

    Dumitrescu, Philipp T.; Vasseur, Romain; Potter, Andrew C.

    2017-09-01

    We study the universal properties of eigenstate entanglement entropy across the transition between many-body localized (MBL) and thermal phases. We develop an improved real space renormalization group approach that enables numerical simulation of large system sizes and systematic extrapolation to the infinite system size limit. For systems smaller than the correlation length, the average entanglement follows a subthermal volume law, whose coefficient is a universal scaling function. The full distribution of entanglement follows a universal scaling form, and exhibits a bimodal structure that produces universal subleading power-law corrections to the leading volume law. For systems larger than the correlation length, the short interval entanglement exhibits a discontinuous jump at the transition from fully thermal volume law on the thermal side, to pure area law on the MBL side.

  9. Scale-invariant hidden local symmetry, topology change, and dense baryonic matter. II.

    NASA Astrophysics Data System (ADS)

    Paeng, Won-Gi; Kuo, Thomas T. S.; Lee, Hyun Kyu; Ma, Yong-Liang; Rho, Mannque

    2017-07-01

    Exploiting certain robust topological inputs from the skyrmion description of compressed baryonic matter with a scale-chiral symmetric Lagrangian, we predict the equation of state that is consistent with the properties of nuclear matter at the equilibrium density, supports the maximum mass of massive compact star ˜2 M⊙ and surprisingly gives the sound velocity close to the "conformal velocity" 1 /√{3 } at densities ≳3 n0 . At the core of this result is the observation that parity-doubling occurs in the nucleon structure as density goes above ˜2 n0 with a chiral-singlet mass m0˜(0.6 - 0.9 )mN , hinting at a possible up-to-date unsuspected source of proton mass and an emergence at high density of scale symmetry and flavor local symmetry, both hidden in the QCD vacuum.

  10. Traffic dynamics based on local routing protocol on a scale-free network.

    PubMed

    Wang, Wen-Xu; Wang, Bing-Hong; Yin, Chuan-Yang; Xie, Yan-Bo; Zhou, Tao

    2006-02-01

    We propose a packet routing strategy with a tunable parameter based on the local structural information of a scale-free network. As free traffic flow on the communication networks is key to their normal and efficient functioning, we focus on the network capacity that can be measured by the critical point of phase transition from free flow to congestion. Simulations show that the maximal capacity corresponds to alpha= -1 in the case of identical nodes' delivering ability. To explain this, we investigate the number of packets of each node depending on its degree in the free flow state and observe the power law behavior. Other dynamic properties including average packets traveling time and traffic load are also studied. Inspiringly, our results indicate that some fundamental relationships exist between the dynamics of synchronization and traffic on the scale-free networks.

  11. Multi-scale optimal interpolation: application to DINEOF analysis spiced with a local optimal interpolation

    NASA Astrophysics Data System (ADS)

    Beckers, J.-M.; Barth, A.; Tomazic, I.; Alvera-Azcárate, A.

    2014-03-01

    We present a method in which the optimal interpolation of multi-scale processes can be untangled into a succession of simpler interpolations. First, we prove how the optimal analysis of a superposition of two processes can be obtained by different mathematical formulations involving iterations and analysis focusing on a single process. From the different mathematical equivalent formulations we then select the most efficient ones by analyzing the behavior of the different possibilities in a simple and well controlled test case. The clear guidelines deduced from this experiment are then applied in a real situation in which we combine large-scale analysis of hourly SEVIRI satellite images using DINEOF with a local optimal interpolation using a Gaussian covariance. It is shown that the optimal combination indeed provides the best reconstruction and can therefore be exploited to extract the maximum amount of useful information from the original data.

  12. Emergence of scale-free networks from local connectivity and communication trade-offs.

    PubMed

    Barbosa, Valmir C; Donangelo, Raul; Souza, Sergio R

    2006-07-01

    We suggest a mechanism of connectivity evolution in networks to account for the emergence of scale-free behavior. The mechanism works on a fixed set of nodes and promotes growth from a minimally connected initial topology by the addition of edges. A new edge is added between two nodes depending on the trade-off between a gain and a cost function of local connectivity and communication properties. We report on simulation results that indicate the appearance of power-law distributions of node degrees for selected parameter combinations.

  13. Emergence of scale-free networks from local connectivity and communication trade-offs

    NASA Astrophysics Data System (ADS)

    Barbosa, Valmir C.; Donangelo, Raul; Souza, Sergio R.

    2006-07-01

    We suggest a mechanism of connectivity evolution in networks to account for the emergence of scale-free behavior. The mechanism works on a fixed set of nodes and promotes growth from a minimally connected initial topology by the addition of edges. A new edge is added between two nodes depending on the trade-off between a gain and a cost function of local connectivity and communication properties. We report on simulation results that indicate the appearance of power-law distributions of node degrees for selected parameter combinations.

  14. Large-scale atmospheric controls on local precipitation in tropical Mexico

    NASA Technical Reports Server (NTRS)

    Hewitson, Bruce C.; Crane, Robert G.

    1992-01-01

    Sixty-five percent of the short term variability in southern Mexican precipitation is accounted for by the large-scale circulation. Empirical relationships between sea level and 500 mb circulation fields, and the local precipitation in Chiapas, Mexico, are derived using a neural net. Although much of the rainfall is a result of convective processes, the neural net captures the onset of the precipitation season, and the phase of individual precipitation events. The analysis indicates that both of these aspects of the precipitation regime are controlled to a large extent by the atmospheric circulation.

  15. Local Scaling Properties of Fractals Observed in Ni-Zr Alloy Films

    NASA Astrophysics Data System (ADS)

    Ding, J. R.; Wang, F.; Liu, B. X.

    Wavelet transform was performed based on the fractals observed in Ni-Zr alloy films during ion irradiation. The mass distribution measure and the Laplacian potential gradient measure were used to study the local scaling properties of the ion-induced fractals. The strength of singularities at each point was calculated according to the wavelet transform. The densities of the strength of singularities were also deduced and compared with the f-α spectra yielded by multifractal analysis. The results showed that the ion-induced fractals had a wide range of strength of singularities.

  16. Measuring natural pest suppression at different spatial scales affects the importance of local variables.

    PubMed

    Bennett, A B; Gratton, C

    2012-10-01

    The role biodiversity plays in the provision of ecosystem services is widely recognized, yet few ecological studies have identified characteristics of natural systems that support and maintain ecosystem services. The purpose of this study was to identify landscape variables correlated with natural pest suppression carried out by arthropod natural enemies, predators and parasitoids. We conducted two field experiments, one observational and one experimental, where landscape variables at broad and local scales were measured and related to natural pest suppression. The first experiment measured natural pest suppression at 16 sites across an urban to rural landscape gradient in south central Wisconsin. We found natural enemy diversity positively affected natural pest suppression, whereas flower diversity negatively affected pest suppression. No relationship was found between natural pest suppression and broad scale variables, which measured the percentage of different land cover classes in the surrounding landscape. In the second experiment, we established small (2- by 3-m) replicated plots that experimentally varied flower diversity (0, 1, or 7 species) within a plot. We found no significant relationship between natural pest suppression and the different levels of flower diversity. The fact that we only found differences in natural pest suppression in our first experiment, which measured natural pest suppression at sites separated by larger distances than our second experiment, suggests the more appropriate scale for measuring ecosystem services performed by mobile organisms like insects, is across broad spatial scales where variation in natural enemies communities and the factors that affect them become more apparent.

  17. On The Evidence For Large-Scale Galactic Conformity In The Local Universe

    NASA Astrophysics Data System (ADS)

    Sin, Larry P. T.; Lilly, Simon J.; Henriques, Bruno M. B.

    2017-10-01

    We re-examine the observational evidence for large-scale (4 Mpc) galactic conformity in the local Universe, as presented in Kauffmann et al. We show that a number of methodological features of their analysis act to produce a misleadingly high amplitude of the conformity signal. These include a weighting in favour of central galaxies in very high density regions, the likely misclassification of satellite galaxies as centrals in the same high-density regions and the use of medians to characterize bimodal distributions. We show that the large-scale conformity signal in Kauffmann et al. clearly originates from a very small number of central galaxies in the vicinity of just a few very massive clusters, whose effect is strongly amplified by the methodological issues that we have identified. Some of these 'centrals' are likely misclassified satellites, but some may be genuine centrals showing a real conformity effect. Regardless, this analysis suggests that conformity on 4 Mpc scales is best viewed as a relatively short-range effect (at the virial radius) associated with these very large neighbouring haloes, rather than a very long-range effect (at tens of virial radii) associated with the relatively low-mass haloes that host the nominal central galaxies in the analysis. A mock catalogue constructed from a recent semi-analytic model shows very similar conformity effects to the data when analysed in the same way, suggesting that there is no need to introduce new physical processes to explain galactic conformity on 4 Mpc scales.

  18. Mineral and water content of A. gigas scales determine local micromechanical properties and energy dissipation mechanisms

    NASA Astrophysics Data System (ADS)

    Troncoso, Omar P.; Gigos, Florian; Torres, Fernando G.

    2017-03-01

    Arapaima gigas scales are natural laminated composite materials made of individual layers with different degrees of mineralization, accompanied of varying mechanical properties. This natural design provides scales with hardness and flexibility, and can serve as a source of inspiration for the development of new layered composites with a hard surface and flexible base. In this paper, we have carried out cyclic micro-indentation tests on both; the internal and the highly mineralized external surface of air dried and wet scales, in order to assess the variation of their local micromechanical properties with regard to the mineral and water content. The load-penetration (P-h) curves showed that creep takes place throughout the application of a constant force during the micro-indentation tests, confirming the time dependent response of A. gigas scales. A model that accounted for the elastic, plastic and viscous responses of the samples was used to fit the experimental results. The penetration depth during loading and creep, as well as the energy dissipated are dependent on the water content. The used model suggests that the viscous response of the internal layer increases with the water content.

  19. Seasonal prediction of lightning activity in North Western Venezuela: Large-scale versus local drivers

    NASA Astrophysics Data System (ADS)

    Muñoz, Á. G.; Díaz-Lobatón, J.; Chourio, X.; Stock, M. J.

    2016-05-01

    The Lake Maracaibo Basin in North Western Venezuela has the highest annual lightning rate of any place in the world (~ 200 fl km- 2 yr- 1), whose electrical discharges occasionally impact human and animal lives (e.g., cattle) and frequently affect economic activities like oil and natural gas exploitation. Lightning activity is so common in this region that it has a proper name: Catatumbo Lightning (plural). Although short-term lightning forecasts are now common in different parts of the world, to the best of the authors' knowledge, seasonal prediction of lightning activity is still non-existent. This research discusses the relative role of both large-scale and local climate drivers as modulators of lightning activity in the region, and presents a formal predictability study at seasonal scale. Analysis of the Catatumbo Lightning Regional Mode, defined in terms of the second Empirical Orthogonal Function of monthly Lightning Imaging Sensor (LIS-TRMM) and Optical Transient Detector (OTD) satellite data for North Western South America, permits the identification of potential predictors at seasonal scale via a Canonical Correlation Analysis. Lightning activity in North Western Venezuela responds to well defined sea-surface temperature patterns (e.g., El Niño-Southern Oscillation, Atlantic Meridional Mode) and changes in the low-level meridional wind field that are associated with the Inter-Tropical Convergence Zone migrations, the Caribbean Low Level Jet and tropical cyclone activity, but it is also linked to local drivers like convection triggered by the topographic configuration and the effect of the Maracaibo Basin Nocturnal Low Level Jet. The analysis indicates that at seasonal scale the relative contribution of the large-scale drivers is more important than the local (basin-wide) ones, due to the synoptic control imposed by the former. Furthermore, meridional CAPE transport at 925 mb is identified as the best potential predictor for lightning activity in the Lake

  20. Mt. Wilson Meets the Lyot Double Image Micrometer

    NASA Astrophysics Data System (ADS)

    Weise, Eric; Genet, Russell; Buchheim, Bob; Gelston, Ryan; Brewer, Mark; Genet, Cheryl; Gerhart, Christine; Wallen, Vera

    2015-07-01

    As part of the Mt. Wilson Double Star Workshop, the authors used a double image micrometer to observe two double stars, STF2383CD and STF2583AB, on the night of July 19, 2013 (B2013.547). The instrument was designed in 1949 by Bernard Lyot and built by Meca-Precis. We found separations of 2.53±0.29'' for STF2383CD and 1.58±0.40'' for STF2583AB, and positions angles of 77.8±2.3° for STF 2383CD and 103.4±1.6° for STF2583AB. The scarcity of double image micrometers and the opportunity to use the historic 60 inch telescope at Mt Wilson made this workshop a very unique experience.

  1. Large increase in fracture resistance of stishovite with crack extension less than one micrometer.

    PubMed

    Yoshida, Kimiko; Wakai, Fumihiro; Nishiyama, Norimasa; Sekine, Risako; Shinoda, Yutaka; Akatsu, Takashi; Nagoshi, Takashi; Sone, Masato

    2015-06-08

    The development of strong, tough, and damage-tolerant ceramics requires nano/microstructure design to utilize toughening mechanisms operating at different length scales. The toughening mechanisms so far known are effective in micro-scale, then, they require the crack extension of more than a few micrometers to increase the fracture resistance. Here, we developed a micro-mechanical test method using micro-cantilever beam specimens to determine the very early part of resistance-curve of nanocrystalline SiO2 stishovite, which exhibited fracture-induced amorphization. We revealed that this novel toughening mechanism was effective even at length scale of nanometer due to narrow transformation zone width of a few tens of nanometers and large dilatational strain (from 60 to 95%) associated with the transition of crystal to amorphous state. This testing method will be a powerful tool to search for toughening mechanisms that may operate at nanoscale for attaining both reliability and strength of structural materials.

  2. Large increase in fracture resistance of stishovite with crack extension less than one micrometer

    NASA Astrophysics Data System (ADS)

    Yoshida, Kimiko; Wakai, Fumihiro; Nishiyama, Norimasa; Sekine, Risako; Shinoda, Yutaka; Akatsu, Takashi; Nagoshi, Takashi; Sone, Masato

    2015-06-01

    The development of strong, tough, and damage-tolerant ceramics requires nano/microstructure design to utilize toughening mechanisms operating at different length scales. The toughening mechanisms so far known are effective in micro-scale, then, they require the crack extension of more than a few micrometers to increase the fracture resistance. Here, we developed a micro-mechanical test method using micro-cantilever beam specimens to determine the very early part of resistance-curve of nanocrystalline SiO2 stishovite, which exhibited fracture-induced amorphization. We revealed that this novel toughening mechanism was effective even at length scale of nanometer due to narrow transformation zone width of a few tens of nanometers and large dilatational strain (from 60 to 95%) associated with the transition of crystal to amorphous state. This testing method will be a powerful tool to search for toughening mechanisms that may operate at nanoscale for attaining both reliability and strength of structural materials.

  3. Synthesis and characterization of micrometer Cu/PVP architectures

    SciTech Connect

    Luo, Huajuan; Zhao, Yanbao; Sun, Lei

    2011-08-15

    Graphical abstract: A simple method for the synthesis of novel micrometer flower-like Cu/PVP architectures was introduced. Highlights: {yields} Micrometer flower-like copper/polyvinylpyrrolidone architectures were obtained by a simple chemical route. {yields} The amount of N{sub 2}H{sub 4}{center_dot}H{sub 2}O, the reaction temperature, the molar ratio of CuCl{sub 2} to PVP and different molecular weights of PVP play an important role in the controlling the morphology of the Cu/PVP architectures. {yields} A possible mechanism of the formation of Cu/PVP architectures was discussed. -- Abstract: Micrometer-sized flower-like Cu/polyvinylpyrrolidone (PVP) architectures are synthesized by the reduction of copper (II) salt with hydrazine hydrate in aqueous solution in the presence of PVP capping agent. The resulting Cu/PVP architectures are investigated by UV-vis spectroscopy, transmission electron microscopy (TEM), X-ray powder diffraction (XRD), and scanning electron microscopy (SEM). The Cu/PVP flowers have uniform morphologies with an average diameter of 10 {mu}m, made of several intercrossing plates. The formation of Cu/PVP flowers is a new kinetic control process, and the factors such as the amount of N{sub 2}H{sub 4}{center_dot}H{sub 2}O, reaction temperature, molar ratio of CuCl{sub 2} to PVP and molecular weight of PVP have significant effect on the morphology of Cu/PVP architectures. A possible mechanism of the formation of micrometer Cu/PVP architectures was discussed.

  4. Color lensless digital holographic microscopy with micrometer resolution.

    PubMed

    Garcia-Sucerquia, Jorge

    2012-05-15

    Color digital lensless holographic microscopy with micrometer resolution is presented. Multiwavelength illumination of a biological sample and a posteriori color composition of the amplitude images individually reconstructed are used to obtain full-color representation of the microscopic specimen. To match the sizes of the reconstructed holograms for each wavelength, a reconstruction algorithm that allows for choosing the pixel size at the reconstruction plane independently of the wavelength and the reconstruction distance is used. The method is illustrated with experimental results.

  5. 10.6 Micrometer Gradient Index Optical Component Design

    DTIC Science & Technology

    1983-11-01

    meters. If the wavelength of the instant radiation is 0.05 micrometers, then 40 interference fringes will be seen in a Mach-Zehnder interferometer ...80 will be observed in a Twyman -Green configuration). Thus, 40 fringes will be seen over a distance of 5 millimeters (the depth of the gradient) or 8...techniques but to introduce a modulation with two frequencies. The system, called a harmonic interferometer , has been described elsewhere [1]. The

  6. New Capabilities in the Analysis of Sub-micrometer Regions in Geological Materials with the Field Emission Electron Microprobe

    NASA Astrophysics Data System (ADS)

    Armstrong, J. T.; McSwiggen, P.; Nielsen, C.

    2013-12-01

    Quantitative electron microprobe analysis has revolutionized two-dimensional elemental analysis of Earth materials at the micrometer-scale. Newly available commercial field emission (FE-) source instruments represent significant technological advances in quantitative measurement with high spatial resolution at sub-micrometer scale - helping to bridge the gap between conventional microprobe and AEM analyses. Their performance specifications suggest the ability to extend routine quantitative analyses from ~3-5 micrometer diameter areas down to 1-2 micrometer diameter at beam energies of 15 keV; and, with care, down to 200-500 nm diameter at reduced beam energies. . In order to determine whether the level of performance suggested by the specifications is realistic, we spent a week doing analyses at the newly installed JEOL JXA-8530F field emission microprobe at Arizona State University, using a series of samples that are currently being studied in various projects at CIW. These samples included: 1) high-pressure experiment run product containing intergrowths of sub-micrometer grains of metal, sulfide, Fe-Mg-perovskite, and ferropericlase; 2) a thin section of the Ivankinsky basalt, part of the Siberian flood basalt sequence containing complex sub-micrometer intergrowths of magnetite, titanomagnetite, ilmenite, titanite and rutile; 3) a polished section of the Giroux pallasite, being studied for element partitioning, that we used as an analogue to test the capabilities for zonation and diffusion determination; and 4) a polished section of the Semarkona ordinary chondrite containing chondules comprised of highly zoned and rimmed olivines and pyroxenes in a complex mesostasis of sub-micrometer pyroxenes and glass. The results of these analyses that we will present confirmed our optimism regarding the new analytical capabilities of a field emission microprobe. We were able, at reduced voltages, to accurately analyze the major and minor element composition of intergrowth

  7. Sensitivities Affecting Heat and Urban Heat Island Effect on Local Scale Projected to Neighborhood Scale in Baltimore, Maryland

    NASA Astrophysics Data System (ADS)

    Sze, C.; Zaitchik, B. F.; Scott, A.

    2015-12-01

    Urban regions are often impacted more by heat than adjacent rural areas, which is a phenomenon known as the urban heat island (UHI) effect. Urban areas are also highly heterogeneous and notoriously difficult to monitor using standard meteorological protocols—the hottest microclimates within a city often occur in locations that lack open, representative installation sites that are an adequate distance from buildings and direct heat sources. To investigate the challenges of monitoring urban heat, this study examines the sensitivity of temperature and humidity sensors currently used in a Baltimore UHI monitoring network to differences in sun exposure, material on which the data collecting instrument is attached, and land cover class of the vicinity. Sensitivity to sun exposure and attachment site can be interpreted as sources of uncertainty for urban heat monitoring, while sensitivity to land cover may reflect a true source of local temperature and humidity variability. In this study, we present results from a test deployment designed to assess the sensitivity of heat measurements to each of these three factors. We then apply these results to interpret measurements taken across the entire Baltimore UHI monitoring network. These results can then be used to improve heat measurements and more accurately represent and quantify the UHI effect on a broader scale, such as in neighborhoods or urban centers.

  8. Multifunctional assembly of micrometer-sized colloids for cell sorting.

    PubMed

    Nie, Chenyao; Wang, Bing; Zhang, Jiangyan; Cheng, Yongqiang; Lv, Fengting; Liu, Libing; Wang, Shu

    2015-06-03

    Compared to the extensively studied nanometer-sized colloids, less attention has been paid to the assembly of micrometer-sized colloids with multifunctional characteristics. To address this need, a bottom-up approach is developed for constructing self-assemblies of micrometer-sized magnetic colloids possessing multifunctionality, including magnetic, optical, and biological activities. Biotinylated oligo (p-phenylene vinylene) (OPV) derivatives are designed to mediate the self-assembly of streptavidin-modified magnetic beads. The optical element OPV derivatives provide a fluorescence imaging ability for tracing the assembly process. Target cells can be recognized and assembled by the colloidal assembly with bioactive element antibodies. The colloidal assembly reveals better cell isolation performance by its amplified magnetic response in comparison to monodisperse colloids. The self-assembly of micrometer-sized magnetic colloids through a combination of different functional ingredients to realize multifunction is conceptually simple and easy to achieve. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Localization of Plastic Deformation in Aluminum Single Crystals at Different Scale Levels

    NASA Astrophysics Data System (ADS)

    Bespalova, I. V.; Teplyakova, L. A.; Kunitsyna, T. S.

    2017-07-01

    The paper generalizes results of investigating the localization and fragmentation of plastic deformation in aluminum single crystals having a different orientation of the compression axis and lateral faces. The surface topography of the samples induced by plastic deformation includes such elements as deformation bands, folds and shear markings observed at different scale levels (macro, meso and micro). The morphological uniformity is identified for these elements in the aluminum single crystals. Depending on the resolution required, the quantification of the shear deformation markings is provided by the optical microscope and the scanning and transmission electron microscopes using the replication technique. The following parameters are obtained: the distance between the nearest shear deformation markings, width of shear markings, local shear; shear γ; the single-crystal volume fraction in which the shear deformation occurs at macro, meso, and micro-levels. The statistical examination of the shear deformation markings in aluminum single crystals with different geometry is performed at these three levels and allows us to conclude that the micro-scale level makes the main contribution to the shear deformation.

  10. Local properties of the large-scale peaks of the CMB temperature

    NASA Astrophysics Data System (ADS)

    Marcos-Caballero, A.; Martínez-González, E.; Vielva, P.

    2017-05-01

    In the present work, we study the largest structures of the CMB temperature measured by Planck in terms of the most prominent peaks on the sky, which, in particular, are located in the southern galactic hemisphere. Besides these large-scale features, the well-known Cold Spot anomaly is included in the analysis. All these peaks would contribute significantly to some of the CMB large-scale anomalies, as the parity and hemispherical asymmetries, the dipole modulation, the alignment between the quadrupole and the octopole, or in the case of the Cold Spot, to the non-Gaussianity of the field. The analysis of the peaks is performed by using their multipolar profiles, which characterize the local shape of the peaks in terms of the discrete Fourier transform of the azimuthal angle. In order to quantify the local anisotropy of the peaks, the distribution of the phases of the multipolar profiles is studied by using the Rayleigh random walk methodology. Finally, a direct analysis of the 2-dimensional field around the peaks is performed in order to take into account the effect of the galactic mask. The results of the analysis conclude that, once the peak amplitude and its first and second order derivatives at the centre are conditioned, the rest of the field is compatible with the standard model. In particular, it is observed that the Cold Spot anomaly is caused by the large value of curvature at the centre.

  11. Recognizing objects in 3D point clouds with multi-scale local features.

    PubMed

    Lu, Min; Guo, Yulan; Zhang, Jun; Ma, Yanxin; Lei, Yinjie

    2014-12-15

    Recognizing 3D objects from point clouds in the presence of significant clutter and occlusion is a highly challenging task. In this paper, we present a coarse-to-fine 3D object recognition algorithm. During the phase of offline training, each model is represented with a set of multi-scale local surface features. During the phase of online recognition, a set of keypoints are first detected from each scene. The local surfaces around these keypoints are further encoded with multi-scale feature descriptors. These scene features are then matched against all model features to generate recognition hypotheses, which include model hypotheses and pose hypotheses. Finally, these hypotheses are verified to produce recognition results. The proposed algorithm was tested on two standard datasets, with rigorous comparisons to the state-of-the-art algorithms. Experimental results show that our algorithm was fully automatic and highly effective. It was also very robust to occlusion and clutter. It achieved the best recognition performance on all of these datasets, showing its superiority compared to existing algorithms.

  12. Local-scale Partitioning of Functional and Phylogenetic Beta Diversity in a Tropical Tree Assemblage.

    PubMed

    Yang, Jie; Swenson, Nathan G; Zhang, Guocheng; Ci, Xiuqin; Cao, Min; Sha, Liqing; Li, Jie; Ferry Slik, J W; Lin, Luxiang

    2015-08-03

    The relative degree to which stochastic and deterministic processes underpin community assembly is a central problem in ecology. Quantifying local-scale phylogenetic and functional beta diversity may shed new light on this problem. We used species distribution, soil, trait and phylogenetic data to quantify whether environmental distance, geographic distance or their combination are the strongest predictors of phylogenetic and functional beta diversity on local scales in a 20-ha tropical seasonal rainforest dynamics plot in southwest China. The patterns of phylogenetic and functional beta diversity were generally consistent. The phylogenetic and functional dissimilarity between subplots (10 × 10 m, 20 × 20 m, 50 × 50 m and 100 × 100 m) was often higher than that expected by chance. The turnover of lineages and species function within habitats was generally slower than that across habitats. Partitioning the variation in phylogenetic and functional beta diversity showed that environmental distance was generally a better predictor of beta diversity than geographic distance thereby lending relatively more support for deterministic environmental filtering over stochastic processes. Overall, our results highlight that deterministic processes play a stronger role than stochastic processes in structuring community composition in this diverse assemblage of tropical trees.

  13. Recognizing Objects in 3D Point Clouds with Multi-Scale Local Features

    PubMed Central

    Lu, Min; Guo, Yulan; Zhang, Jun; Ma, Yanxin; Lei, Yinjie

    2014-01-01

    Recognizing 3D objects from point clouds in the presence of significant clutter and occlusion is a highly challenging task. In this paper, we present a coarse-to-fine 3D object recognition algorithm. During the phase of offline training, each model is represented with a set of multi-scale local surface features. During the phase of online recognition, a set of keypoints are first detected from each scene. The local surfaces around these keypoints are further encoded with multi-scale feature descriptors. These scene features are then matched against all model features to generate recognition hypotheses, which include model hypotheses and pose hypotheses. Finally, these hypotheses are verified to produce recognition results. The proposed algorithm was tested on two standard datasets, with rigorous comparisons to the state-of-the-art algorithms. Experimental results show that our algorithm was fully automatic and highly effective. It was also very robust to occlusion and clutter. It achieved the best recognition performance on all of these datasets, showing its superiority compared to existing algorithms. PMID:25517694

  14. Predicting phosphorus losses with the PLEASE model on a local scale in Denmark and the Netherlands.

    PubMed

    van der Salm, Caroline; Dupas, Remi; Grant, Ruth; Heckrath, Goswin; lversen, Bo V; Kronvang, Brian; Levi, Clémentine; Rubaek, Gitte; Schoumans, Oscar F

    2011-01-01

    To reduce losses from agricultural soils to surface water, mitigation options have to be implemented as a local scale. For a cost-effective implementation of these measures, an instrument to identify critical areas for P leaching is indispensable. In many countries, P-index methods are used to identify areas as risk for P losses to surface water. In flat areas, where losses by leaching are dominant, these methods have their limitations because leaching is often not described in detail, PLEASE, is a simple mechanistic model designed to stimulate P Losses by leaching at the field scale using a limited amount of local field data. In this study, PLEASE, was applied to 17 lowland sites in Denmark and 14 lowland sites in the Netherlands. Results show that the simple model simulated measured fluxes and concentrations in water from pipe drains, suction cups, and groundwater quite well. The modeling efficiency ranged from 0.92 for modeling total-P fluxes to 0.36 fr modeling concentrations in groundwater. Poor results were obtained for heavy clay soils and eutrophic peat soils, where fluxes and concentration were strongly underestimated by the model. The poot performance for the heavy clay soil can be explained by the transport of P through macropores to the drain pipes and the underestimation of overland flow on this heavy-textured soil. In the eutrophic peat soils, fluxes were underestimated due to the release of P from deep soil layers.

  15. Local-scale recovery of wastewater nitrogen for edible plant growth.

    PubMed

    Smith, Daniel P; Smith, Nathaniel T

    2016-01-01

    An anaerobic/ion exchange (AN-IX) system was developed for recovery and reuse of wastewater nitrogen at point-of-origin. AN-IX combines upflow solids blanket anaerobic treatment with ammonium ion adsorption onto granular natural zeolite. AN-IX operates passively and without energy input. A 57 L empty-bed prototype was operated for 355 days on wastewater primary effluent. Total nitrogen removal exceeded 95% over the first 214 days of operation and ammonia reduction exceeded 99%; accumulation of oxidized nitrogen species (NO3(-) + NO2(-)) was not observed. The wastewater flowrate was increased during the last 35 days of operation to deliberately exhaust the ion exchange media. Spent granular media was removed from the AN-IX prototype and deployed in plant chamber experiments for cultivation of Solanum lycopersicum (cherry tomato). Wastewater nitrogen captured on zeolite was capable of supplying the total growth requirement for nitrogen. Canopy volume and plant flowering and fruiting were higher for wastewater nitrogen than for artificial fertilizer. The AN-IX process is a passive, mechanically simple and reliable system for local-scale nitrogen recovery. AN-IX is modular, scalable, adaptable and can be applied in diverse treatment contexts and recycling scenarios. AN-IX benefits include appropriate technology for local-scale nitrogen recovery, low capital and energy costs, and protection of health and the environment.

  16. Handbook for Small-Scale Densified Biomass Fuel (Pellets) Manufacturing for Local Markets.

    SciTech Connect

    Folk, Richard L.; Govett, Robert L.

    1992-07-01

    Wood pellet manufacturing in the Intermountain West is a recently founded and rapidly expanding energy industry for small-scale producers. Within a three-year period, the total number of manufacturers in the region has increased from seven to twelve (Folk et al., 1988). Small-scale industry development is evolving because a supply of raw materials from small and some medium-sized primary and secondary wood processors that has been largely unused. For the residue producer considering pellet fuel manufacturing, the wastewood generated from primary products often carries a cost associated with residue disposal when methods at-e stockpiling, landfilling or incinerating. Regional processors use these methods for a variety of reasons, including the relatively small amounts of residue produced, residue form, mixed residue types, high transportation costs and lack of a local market, convenience and absence of regulation. Direct costs associated with residue disposal include the expenses required to own and operate residue handling equipment, costs for operating and maintaining a combustor and tipping fees charged to accept wood waste at public landfills. Economic and social costs related to environmental concerns may also be incurred to include local air and water quality degradation from open-air combustion and leachate movement into streams and drinking water.

  17. User and stakeholder involvement for relevant, reliable and robust local-scale climate projections in Norway

    NASA Astrophysics Data System (ADS)

    Neby, Simon; Sobolowski, Stefan

    2017-04-01

    How can users and stakeholders be actively involved with providing input to and using output from local-scale climate projections? How can the scientific community better understand the needs of local actors? And how should communication and cooperation efforts be organized? These are critical questions we aim to answer in a climate services project funded by the Norwegian Research Council (R3: Relevant, Reliable and Robust local-scale climate projections for Norway). The project takes into consideration not only the scientific issues in establishing useful local-scale climate projections, but also addresses the "usability gap" between climate information and decision-making. The lack of effective communication between scientists and user communities often result in outputs and products that are not matched with decision-relevant climate information. In the R3 project, the scientific participants actively engage with a range of users that have quite different information needs: municipalities, infrastructure developers, agriculture, energy producers, insurance companies, and more. In this particular presentation, we present our experiences concerning three specific issues that relate to the stakeholder-science interface: 1) Preferences are not clear-cut and pre-defined. In practice, this means that stakeholders often do not have precise information about their needs, nor precise information about how, where and whether their needs can be voiced. Similarly, science communities tend to presuppose that stakeholders are interested and have well-articulated needs, which is hardly the case. Collectively, that means that there is a need for an approach that guides the articulation and prioritization of preferences in a manner that integrates both scientific and stakeholder perspectives and takes the integrity of both perspectives seriously. 2) Technologies are unclear. Although information may be produced and used, past experiences, trial and error processes and pragmatic

  18. Food Self-Sufficiency across scales: How local can we go?

    NASA Astrophysics Data System (ADS)

    Pradhan, Prajal; Lüdeke, Matthias K. B.; Reusser, Dominik E.; Kropp, Jürgen P.

    2013-04-01

    "Think global, act local" is a phrase often used in sustainability debates. Here, we explore the potential of regions to go for local supply in context of sustainable food consumption considering both the present state and the plausible future scenarios. We analyze data on the gridded crop calories production, the gridded livestock calories production, the gridded feed calories use and the gridded food calories consumption in 5' resolution. We derived these gridded data from various sources: Global Agro-ecological Zone (GAEZ v3.0), Gridded Livestock of the World (GLW), FAOSTAT, and Global Rural-Urban Mapping Project (GRUMP). For scenarios analysis, we considered changes in population, dietary patterns and possibility of obtaining the maximum potential yield. We investigate the food self-sufficiency multiple spatial scales. We start from the 5' resolution (i.e. around 10 km x 10 km in the equator) and look at 8 levels of aggregation ranging from the plausible lowest administrative level to the continental level. Results for the different spatial scales show that about 1.9 billion people live in the area of 5' resolution where enough calories can be produced to sustain their food consumption and the feed used. On the country level, about 4.4 billion population can be sustained without international food trade. For about 1 billion population from Asia and Africa, there is a need for cross-continental food trade. However, if we were able to achieve the maximum potential crop yield, about 2.6 billion population can be sustained within their living area of 5' resolution. Furthermore, Africa and Asia could be food self-sufficient by achieving their maximum potential crop yield and only round 630 million populations would be dependent on the international food trade. However, the food self-sufficiency status might differ under consideration of the future change in population, dietary patterns and climatic conditions. We provide an initial approach for investigating the

  19. Evaluation of Local and Regional Phenomena in Regional Scale Climate Simulations (Invited)

    NASA Astrophysics Data System (ADS)

    Kotamarthi, V. R.; Wang, J.; Stein, M.; Ramachandran, S.

    2013-12-01

    Evaluation of regional scale climate models is aimed at capturing the ability of the model for capturing regional and local phenomena on climate scales. Climate variability on smaller spatial and temporal scales is a primary target, followed by extreme event climatology in space and time. We are exploring several new ways for evaluating the models at these scales and with a focus on capturing the spatio-temporal correlations in measurements and model results. Model simulations from 1980 to 2010 over a domain that covers much of North America (600 × 516 grid cells over longitude and latitude) at 12 km resolution using the Nested Regional Climate Model (WRF V3.3.1) were used as the model data set and observational data included PRISM, UDEL, CRU, TRMM and observations from individual stations. Some of these data sets were gridded to the model domain using an application developed by JPL. We have conducted a comparative evaluation of some of these data sets for precipitation and temperature to generate an estimate of the bias introduced by different evaluation data sets for model evaluation. The metrics used for model evaluation range from correlations between observations and model output over specified regions to novel space-time correlations in observations and model output. The space-time correlations were designed to test the model performance in producing correlated phenomena at scales ranging from half degree (50 km) to five degree (more than 500 km). The procedure used for generating these correlations and results from these tests will be presented.

  20. Natural Carbonation, In-situ Brecciation and Local-scale Transportation of Ocean Floor Peridotites

    NASA Astrophysics Data System (ADS)

    Hellebrand, E.; Snow, J. E.

    2010-12-01

    Serpentinized mantle peridotites that are exposed on the ocean floor along (ultra-)slow spreading ridges commonly contain variable amounts CaCO3. This carbonate may be finely disseminated and partly related to diffuse and pervasive replacement of the serpentinite matrix. Visually, however, carbonate dominantly occurs in 0.01 - >30 mm wide fractures, which locally form an irregular network and give the rock a brecciated appearance. Peridotite-carbonate breccias, similar to 'ophicalcite' exposures on land (e.g. Oman, Ligurian and W-Alps), are commonly collected in dredge hauls that sample magma-starved ridges, and likely associated with Lost City-type low-T hydrothermal circulation. We studied 33 carbonate-peridotite breccias from six dredge hauls from the ultraslow spreading Gakkel Ridge (Arctic Ocean). Texturally, the breccias can be divided into two main groups (1) in-situ breccias with jigsaw-like peridotite fragments, and (2) matrix-supported breccias, which are apparently more heterogeneous and commonly contain more fine-grained peridotite clasts. However, more than half of the studied samples contain textural evidence of both groups. To first order, the serpentinized peridotites are residual of partial melting in the mantle. Recent isotopic studies revealed that abyssal peridotites in general, and the Gakkel Ridge peridotites in particular, have a far more complex history than previously thought. A significant fraction of the uppermost mantle may have inherited depletion from an old (>1Ga) partial melting event(s). As a result of incomplete rehomogenization during mantle convection, local (dredge) scale heterogeneity is the rule rather the exception. The primary goal of this study was therefore to obtain additional information on the extent and distribution of local-scale heterogeneity in the oceanic mantle. For this reason, chromian spinels were extracted from the fine-grained carbonate-rich matrix of the breccias. These alteration-resistant oxides are

  1. Developing partnerships for implementing continental-scale citizen science programs at the local-level

    NASA Astrophysics Data System (ADS)

    Newman, S. J.; Henderson, S.; Ward, D.

    2012-12-01

    Project BudBurst is a citizen science project focused on monitoring plant phenology that resides at the National Ecological Observatory Network (NEON, Inc). A central question for Project BudBurst and other national outreach programs is: what are the most effective means of engaging and connecting with diverse communities throughout the country? How can continental scale programs like NEON's Project BudBurst engage audiences in such a way as to be relevant at both the local and continental scales? Staff with Project BudBurst pursued partnerships with several continental scale organizations: the National Wildlife Refuge System, the National Park Service, and botanic gardens to address these questions. The distributed nature of wildlife refuges, national parks, and botanic gardens around the country provided the opportunity to connect with participants locally while working with leadership at multiple scales. Project BudBurst staff talked with hundreds of staff and volunteers prior to setting a goal of obtaining and developing resources for several Refuge Partners, a pilot National Park partner, and an existing botanic garden partner during 2011. We were especially interested in learning best practices for future partnerships. The partnership efforts resulted in resource development for 12 Refuge partners, a pilot National Park partner, and 2 botanic garden partners. Early on, the importance of working with national level leaders to develop ownership of the partner program and input about resource needs became apparent. Once a framework for the partnership program was laid out, it became critical to work closely with staff and volunteers on the ground to ensure needs were met. In 2012 we began to develop an online assessment to allow our current and potential partners to provide feedback about whether or not the partnership program was meeting their needs and how the program could be improved. As the year progressed, the timeline for resource development became more

  2. EVIDENCE FOR A ∼300 MEGAPARSEC SCALE UNDER-DENSITY IN THE LOCAL GALAXY DISTRIBUTION

    SciTech Connect

    Keenan, R. C.; Barger, A. J.; Cowie, L. L.

    2013-09-20

    Galaxy counts and recent measurements of the luminosity density in the near-infrared have indicated the possibility that the local universe may be under-dense on scales of several hundred megaparsecs. The presence of a large-scale under-density in the local universe could introduce significant biases into the interpretation of cosmological observables, and, in particular, into the inferred effects of dark energy on the expansion rate. Here we measure the K-band luminosity density as a function of redshift to test for such a local under-density. For our primary sample in this study, we select galaxies from the UKIDSS Large Area Survey and use spectroscopy from the Sloan Digital Sky Survey (SDSS), the Two-degree Field Galaxy Redshift Survey, the Galaxy And Mass Assembly Survey (GAMA), and other redshift surveys to generate a K-selected catalog of ∼35, 000 galaxies that is ∼95% spectroscopically complete at K{sub AB} < 16.3 (K{sub AB} < 17 in the GAMA fields). To complement this sample at low redshifts, we also analyze a K-selected sample from the 2M++ catalog, which combines Two Micron All Sky Survey (2MASS) photometry with redshifts from the 2MASS redshift survey, the Six-degree Field Galaxy Redshift Survey, and the SDSS. The combination of these samples allows for a detailed measurement of the K-band luminosity density as a function of distance over the redshift range 0.01 < z < 0.2 (radial distances D ∼ 50-800 h{sub 70}{sup -1} Mpc). We find that the overall shape of the z = 0 rest-frame K-band luminosity function (M*-5log (h{sub 70}) = –22.15 ± 0.04 and α = –1.02 ± 0.03) appears to be relatively constant as a function of environment and distance from us. We find a local (z < 0.07, D < 300 h{sub 70}{sup -1} Mpc) luminosity density that is in good agreement with previous studies. Beyond z ∼ 0.07, we detect a rising luminosity density that reaches a value of roughly ∼1.5 times higher than that measured locally at z > 0.1. This suggests that the

  3. Flashlamp Pumped, Room Temperature, Nd:YAG Laser Operating at 0.946 Micrometers

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.; Murray, Keith E.; Walsh, Brian M.

    1998-01-01

    Room temperature operation of flashlamp pumped Nd:YAG at 0.946 micrometers was achieved with a laser rod having undoped ends. Performance was characterized and compared with 1.064 micrometer operation and other quasi four level lasers.

  4. A cloud based tool for knowledge exchange on local scale flood risk.

    PubMed

    Wilkinson, M E; Mackay, E; Quinn, P F; Stutter, M; Beven, K J; MacLeod, C J A; Macklin, M G; Elkhatib, Y; Percy, B; Vitolo, C; Haygarth, P M

    2015-09-15

    There is an emerging and urgent need for new approaches for the management of environmental challenges such as flood hazard in the broad context of sustainability. This requires a new way of working which bridges disciplines and organisations, and that breaks down science-culture boundaries. With this, there is growing recognition that the appropriate involvement of local communities in catchment management decisions can result in multiple benefits. However, new tools are required to connect organisations and communities. The growth of cloud based technologies offers a novel way to facilitate this process of exchange of information in environmental science and management; however, stakeholders need to be engaged with as part of the development process from the beginning rather than being presented with a final product at the end. Here we present the development of a pilot Local Environmental Virtual Observatory Flooding Tool. The aim was to develop a cloud based learning platform for stakeholders, bringing together fragmented data, models and visualisation tools that will enable these stakeholders to make scientifically informed environmental management decisions at the local scale. It has been developed by engaging with different stakeholder groups in three catchment case studies in the UK and a panel of national experts in relevant topic areas. However, these case study catchments are typical of many northern latitude catchments. The tool was designed to communicate flood risk in locally impacted communities whilst engaging with landowners/farmers about the risk of runoff from the farmed landscape. It has been developed iteratively to reflect the needs, interests and capabilities of a wide range of stakeholders. The pilot tool combines cloud based services, local catchment datasets, a hydrological model and bespoke visualisation tools to explore real time hydrometric data and the impact of flood risk caused by future land use changes. The novel aspects of the

  5. Local- and landscape-scale land cover affects microclimate and water use in urban gardens.

    PubMed

    Lin, Brenda B; Egerer, Monika H; Liere, Heidi; Jha, Shalene; Bichier, Peter; Philpott, Stacy M

    2018-01-01

    Urban gardens in Central California are highly vulnerable to the effects of climate change, experiencing both extended high heat periods as well as water restrictions because of severe drought conditions. This puts these critical community-based food production systems at risk as California is expected to experience increasing weather extremes. In agricultural systems, increased vegetation complexity, such as greater structure or biodiversity, can increase the resilience of food production systems from climate fluctuations. We test this theory in 15 urban gardens across California's Central Coast. Local- and landscape-scale measures of ground, vegetation, and land cover were collected in and around each garden, while climate loggers recorded temperatures in each garden in 30min increments. Multivariate analyses, using county as a random factor, show that both local- and landscape-scale factors were important. All factors were significant predictors of mean temperature. Tallest vegetation, tree/shrub species richness, grass cover, mulch cover, and landscape level agricultural cover were cooling factors; in contrast, garden size, garden age, rock cover, herbaceous species richness, and landscape level urban cover were warming factors. Results were similar for the maximum temperature analysis except that agriculture land cover and herbaceous species richness were not significant predictors of maximum temperature. Analysis of gardener watering behavior to observed temperatures shows that garden microclimate was significantly related to the number of minutes watered as well as the number of liters of water used per watering event. Thus gardeners seem to respond to garden microclimate in their watering behavior even though this behavior is most probably motivated by a range of other factors such as water regulations and time availability. This research shows that local management of ground cover and vegetation can reduce mean and maximum temperatures in gardens, and the

  6. Improving large-scale image retrieval through robust aggregation of local descriptors.

    PubMed

    Husain, Syed Sameed; Bober, Miroslaw

    2016-09-27

    Visual search and image retrieval underpin numerous applications, however the task is still challenging predominantly due to the variability of object appearance and ever increasing size of the databases, often exceeding billions of images. Prior art methods rely on aggregation of local scale-invariant descriptors, such as SIFT, via mechanisms including Bag of Visual Words (BoW), Vector of Locally Aggregated Descriptors (VLAD) and Fisher Vectors (FV). However, their performance is still short of what is required. This paper presents a novel method for deriving a compact and distinctive representation of image content called Robust Visual Descriptor with Whitening (RVD-W). It significantly advances the state of the art and delivers world-class performance. In our approach local descriptors are rank-assigned to multiple clusters. Residual vectors are then computed in each cluster, normalized using a direction-preserving normalization function and aggregated based on the neighborhood rank. Importantly, the residual vectors are de-correlated and whitened in each cluster before aggregation, leading to a balanced energy distribution in each dimension and significantly improved performance. We also propose a new post-PCA normalization approach which improves separability between the matching and non-matching global descriptors. This new normalization benefits not only our RVD-W descriptor but also improves existing approaches based on FV and VLAD aggregation. Furthermore, we show that the aggregation framework developed using hand-crafted SIFT features also performs exceptionally well with Convolutional Neural Network (CNN) based features. The RVD-W pipeline outperforms state-of-the-art global descriptors on both the Holidays and Oxford datasets. On the large scale datasets, Holidays1M and Oxford1M, SIFT-based RVD-W representation obtains a mAP of 45.1% and 35.1%, while CNN-based RVD-W achieve a mAP of 63.5% and 44.8%, all yielding superior performance to the state-of-the-art.

  7. Wrinkle ridges on Venusian plains: Indicators of shallow crustal stress orientations at local and regional scales

    NASA Technical Reports Server (NTRS)

    Mcgill, George E.

    1992-01-01

    The plains regions of Venus exhibit a complex array of structural features, including deformation belts of various types, wrinkle ridges, grabens, and enigmatic radar-bright linears. Probably the most pervasive of these structures are the wrinkle ridges, which appear to be morphologically identical to their counterparts on the Moon and Mars. Almost all workers agree that wrinkle ridges result from horizontal compressive stresses in the crust; they either are explained as flexural fold structures, or alternatively as scarps or folds related to reverse faults. Wrinkle ridges generally are narrow, have small amplitudes, and commonly are closely spaced as well, characteristics that imply a shallow crustal origin. If wrinkle ridges are due to horizontally directed compressive stresses in the shallow crust, as generally has been inferred, then the trends of these features provide a means to map both local and regional orientations of principal stresses in the uppermost part of the venusian crust: maximum compressive stress is normal to the ridges, minimum compressive stress is normal to the topographic surface, and thus the wrinkle ridge trends trace the orientation of the intermediate principal stress. Because there are few plains areas on Venus totally devoid of wrinkle ridges, it should be possible to establish a number of interesting relationships on a near-global scale by mapping the trends of wrinkle ridges wherever they occur. The present study is addressing three questions: (1) Do the trends of wrinkle ridges define domains that are large relative to the sizes of individual plains regions? If so, can these domains be related to large-scale topographic or geologic features? (2) Are regional trends of wrinkle ridges affected by local features such as coronae? If so, is it possible to determine the relative ages of the far-field and local stresses from detailed study of trend inheritance or superposition relationships? (3) What is the relationship between wrinkle

  8. A monitoring protocol to assess tidal restoration of salt marshes on local and regional scales

    USGS Publications Warehouse

    Neckles, H.A.; Dionne, M.D.; Burdick, D.M.; Roman, C.T.; Buchsbaum, R.; Hutchins, E.

    2002-01-01

    Assessing the response of salt marshes to tidal restoration relies on comparisons of ecosystem attributes between restored and reference marshes. Although this approach provides an objective basis for judging project success, inferences can be constrained if the high variability of natural marshes masks differences in sampled attributes between restored and reference sites. Furthermore, such assessments are usually focused on a small number of restoration projects in a local area, limiting the ability to address questions regarding the effectiveness of restoration within a broad region. We developed a hierarchical approach to evaluate the performance of tidal restorations at local and regional scales throughout the Gulf of Maine. The cornerstone of the approach is a standard protocol for monitoring restored and reference salt marshes throughout the region. The monitoring protocol was developed by consensus among nearly 50 restoration scientists and practitioners. The protocol is based on a suite of core structural measures that can be applied to any tidal restoration project. The protocol also includes additional functional measures for application to specific projects. Consistent use of the standard protocol to monitor local projects will enable pooling information for regional assessments. Ultimately, it will be possible to establish a range of reference conditions characterizing natural tidal wetlands in the region and to compare performance curves between populations of restored and reference marshes for assessing regional restoration effectiveness.

  9. Speciation on a local geographic scale: the evolution of a rare rock outcrop specialist in Mimulus

    PubMed Central

    Ferris, Kathleen G.; Sexton, Jason P.; Willis, John H.

    2014-01-01

    Speciation can occur on both large and small geographical scales. In plants, local speciation, where small populations split off from a large-ranged progenitor species, is thought to be the dominant mode, yet there are still few examples to verify speciation has occurred in this manner. A recently described morphological species in the yellow monkey flowers, Mimulus filicifolius, is an excellent candidate for local speciation because of its highly restricted geographical range. Mimulus filicifolius was formerly identified as a population of M. laciniatus due to similar lobed leaf morphology and rocky outcrop habitat. To investigate whether M. filicifolius is genetically divergent and reproductively isolated from M. laciniatus, we examined patterns of genetic diversity in ten nuclear and eight microsatellite loci, and hybrid fertility in M. filicifolius and its purported close relatives: M. laciniatus, M. guttatus and M. nasutus. We found that M. filicifolius is genetically divergent from the other species and strongly reproductively isolated from M. laciniatus. We conclude that M. filicifolius is an independent rock outcrop specialist despite being morphologically and ecologically similar to M. laciniatus, and that its small geographical range nested within other wide-ranging members of the M. guttatus species complex is consistent with local speciation. PMID:24958929

  10. Speciation on a local geographic scale: the evolution of a rare rock outcrop specialist in Mimulus.

    PubMed

    Ferris, Kathleen G; Sexton, Jason P; Willis, John H

    2014-08-05

    Speciation can occur on both large and small geographical scales. In plants, local speciation, where small populations split off from a large-ranged progenitor species, is thought to be the dominant mode, yet there are still few examples to verify speciation has occurred in this manner. A recently described morphological species in the yellow monkey flowers, Mimulus filicifolius, is an excellent candidate for local speciation because of its highly restricted geographical range. Mimulus filicifolius was formerly identified as a population of M. laciniatus due to similar lobed leaf morphology and rocky outcrop habitat. To investigate whether M. filicifolius is genetically divergent and reproductively isolated from M. laciniatus, we examined patterns of genetic diversity in ten nuclear and eight microsatellite loci, and hybrid fertility in M. filicifolius and its purported close relatives: M. laciniatus, M. guttatus and M. nasutus. We found that M. filicifolius is genetically divergent from the other species and strongly reproductively isolated from M. laciniatus. We conclude that M. filicifolius is an independent rock outcrop specialist despite being morphologically and ecologically similar to M. laciniatus, and that its small geographical range nested within other wide-ranging members of the M. guttatus species complex is consistent with local speciation. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  11. Toward electroweak scale cold dark matter with local dark gauge symmetry and beyond the DM EFT

    NASA Astrophysics Data System (ADS)

    Ko, Pyungwon

    2016-06-01

    In this talk, I describe a class of electroweak (EW) scale dark matter (DM) models where its stability or longevity are the results of underlying dark gauge symmetries: stable due to unbroken local dark gauge symmetry or topology, or long-lived due to the accidental global symmetry of dark gauge theories. Compared with the usual phenomenological dark matter models (including DM EFT or simplified DM models), DM models with local dark gauge symmetries include dark gauge bosons, dark Higgs bosons and sometimes excited dark matter. And dynamics among these fields are completely fixed by local gauge principle. The idea of singlet portals including the Higgs portal can thermalize these hidden sector dark matter very efficiently, so that these DM could be easily thermal DM. I also discuss the limitation of the usual DM effective field theory or simplified DM models without the full SM gauge symmetry, and emphasize the importance of the full SM gauge symmetry and renormalizability especially for collider searches for DM.

  12. Toward electroweak scale cold dark matter with local dark gauge symmetry and beyond the DM EFT

    SciTech Connect

    Ko, Pyungwon

    2016-06-21

    In this talk, I describe a class of electroweak (EW) scale dark matter (DM) models where its stability or longevity are the results of underlying dark gauge symmetries: stable due to unbroken local dark gauge symmetry or topology, or long-lived due to the accidental global symmetry of dark gauge theories. Compared with the usual phenomenological dark matter models (including DM EFT or simplified DM models), DM models with local dark gauge symmetries include dark gauge bosons, dark Higgs bosons and sometimes excited dark matter. And dynamics among these fields are completely fixed by local gauge principle. The idea of singlet portals including the Higgs portal can thermalize these hidden sector dark matter very efficiently, so that these DM could be easily thermal DM. I also discuss the limitation of the usual DM effective field theory or simplified DM models without the full SM gauge symmetry, and emphasize the importance of the full SM gauge symmetry and renormalizability especially for collider searches for DM.

  13. What determines large scale galaxy clustering: halo mass or local density?

    NASA Astrophysics Data System (ADS)

    Pujol, Arnau; Hoffmann, Kai; Jiménez, Noelia; Gaztañaga, Enrique

    2017-02-01

    Using a dark matter simulation we show how halo bias is determined by local density and not by halo mass. This is not totally surprising as, according to the peak-background split model, local matter density (bar δ) is the property that constrains bias at large scales. Massive haloes have a high clustering because they reside in high density regions. Small haloes can be found in a wide range of environments which differentially determine their clustering amplitudes. This contradicts the assumption made by standard halo occupation distribution (HOD) models that bias and occupation of haloes is determined solely by their mass. We show that the bias of central galaxies from semi-analytic models of galaxy formation as a function of luminosity and colour is therefore not correctly predicted by the standard HOD model. Using bar δ (of matter or galaxies) instead of halo mass, the HOD model correctly predicts galaxy bias. These results indicate the need to include information about local density and not only mass in order to correctly apply HOD analysis in these galaxy samples. This new model can be readily applied to observations and has the advantage that, in contrast with the dark matter halo mass, the galaxy density can be directly observed.

  14. Experimental damage localization in a full-scale 7 story benchmark building under seismic excitation

    NASA Astrophysics Data System (ADS)

    Iacovino, C.; Ditommaso, R.; Limongelli, M. P.; Ponzo, F. C.

    2017-04-01

    In this paper two methods of damage localization previously proposed by the authors are combined to smooth the possible drawbacks and boost the advantages each of them. The Modal Interpolation Method (IM), recently proposed, is based on a damage feature defined in terms of the loss of smoothness (that is local increases of curvature) of the modal shapes induced by a local reduction of stiffness. Herein the combination of the IM with the Curvature Evolution Methods (CEM) is proposed. The CEM is based on the use of a Band-Variable Filter able to extract from recorded responses the nonlinear response of one mode of vibration enabling the detection of possible changes of a properly defined damage feature, during a single earthquake. In the CEM the modal curvature is assumed as damage feature. The combination of the two methods CEM and IM is carried out using the Band-Variable Filter to extract the nonlinear response of the structure and assuming as a damage feature the variation of the interpolation error computed at different times during the strong motion. The validation of the combined approach, named Interpolation Evolution Method (IEM), is carried out on a full scale experimental benchmark tested on the UCSD-NEES shake table.

  15. Scaling relations and the fundamental line of the local group dwarf galaxies

    NASA Astrophysics Data System (ADS)

    Woo, Joanna; Courteau, Stéphane; Dekel, Avishai

    2008-11-01

    We study the scaling relations between global properties of dwarf galaxies in the local group. In addition to quantifying the correlations between pairs of variables, we explore the `shape' of the distribution of galaxies in log parameter space using standardized principal component analysis, the analysis is performed first in the 3D structural parameter space of stellar mass M*, internal velocity V and characteristic radius R* (or surface brightness μ*). It is then extended to a 4D space that includes a stellar population parameter such as metallicity Z or star formation rate . We find that the local group dwarfs basically define a one-parameter `fundamental line' (FL), primarily driven by stellar mass, M*. A more detailed inspection reveals differences between the star formation properties of dwarf irregulars (dI's) and dwarf ellipticals (dE's), beyond the tendency of the latter to be more massive. In particular, the metallicities of dI's are typically lower by a factor of 3 at a given M* and they grow faster with increasing M*, showing a tighter FL in the 4D space for the dE's. The structural scaling relations of dI's resemble those of the more massive spirals, but the dI's have lower star formation rates for a given M* which also grow faster with increasing M*. On the other hand, the FL of the dE's departs from the fundamental plane of bigger ellipticals. While the one-parameter nature of the FL and the associated slopes of the scaling relations are consistent with the general predictions of supernova feedback from Dekel & Woo, the differences between the FL's of the dE's and the dI's remain a challenge and should serve as a guide for the secondary physical processes responsible for these two types.

  16. Self-similar patterns of nature: insect diversity at local to global scales

    PubMed Central

    Finlay, Bland J; Thomas, Jeremy A; McGavin, George C; Fenchel, Tom; Clarke, Ralph T

    2006-01-01

    The insects are probably the most hyperdiverse and economically important metazoans on the planet, but there is no consensus on the best way to model the dimensions of their diversity at multiple spatial scales, and the huge amount of information involved hinders data synthesis and the revelation of ‘patterns of nature’. Using a sample of more than 600k insect species in the size range 1–100 mm, we analysed insect body sizes and revealed self-similar patterns persisting across spatial scales from several hectares to the World. The same patterns were found in both Northern and Southern Hemispheres. The patterns include: parallel rank-abundance distributions; flatter species–area curves in smaller insects—indicating their wider geographical distribution; the recurrence of the same species-rich family in the same body-size class at all spatial scales—which generates self-similar size-frequency distributions (SFDs)—and the discovery that with decreasing mean body size, local species richness represents an increasing fraction of global species richness. We describe how these ‘rationalizing’ patterns can be translated into methods for monitoring and predicting species diversity and community structure at all spatial scales. PMID:16822755

  17. A new method of automatic landmark tagging for shape model construction via local curvature scale

    NASA Astrophysics Data System (ADS)

    Rueda, Sylvia; Udupa, Jayaram K.; Bai, Li

    2008-03-01

    Segmentation of organs in medical images is a difficult task requiring very often the use of model-based approaches. To build the model, we need an annotated training set of shape examples with correspondences indicated among shapes. Manual positioning of landmarks is a tedious, time-consuming, and error prone task, and almost impossible in the 3D space. To overcome some of these drawbacks, we devised an automatic method based on the notion of c-scale, a new local scale concept. For each boundary element b, the arc length of the largest homogeneous curvature region connected to b is estimated as well as the orientation of the tangent at b. With this shape description method, we can automatically locate mathematical landmarks selected at different levels of detail. The method avoids the use of landmarks for the generation of the mean shape. The selection of landmarks on the mean shape is done automatically using the c-scale method. Then, these landmarks are propagated to each shape in the training set, defining this way the correspondences among the shapes. Altogether 12 strategies are described along these lines. The methods are evaluated on 40 MRI foot data sets, the object of interest being the talus bone. The results show that, for the same number of landmarks, the proposed methods are more compact than manual and equally spaced annotations. The approach is applicable to spaces of any dimensionality, although we have focused in this paper on 2D shapes.

  18. Scaling of the structural characteristics of nanoholes created by local droplet etching

    NASA Astrophysics Data System (ADS)

    Heyn, Ch.; Schnüll, S.; Hansen, W.

    2014-01-01

    We study the tuneability of nanoholes created by local droplet etching of AlGaAs surfaces with Al droplets at varied coverage θ of the deposited droplet material and process temperature T. For the contact angle of the as-grown droplets a mean value of 66° is determined, which depends neither on θ nor on T. The experimental results on the hole structural characteristics are interpreted in terms of scaling models yielding a general form f(θ ,T)∝θqexp(E /[kBT]), with constants q and E and Boltzmann's constant kB. In detail, the hole density varies from N = 4.0 × 106 up to 1.5 × 108 cm-2, and the scaling parameters are q = 0 and E = EN = 2.46 eV. The hole diameter varies from 50 up to 190 nm with scaling parameters q = 1/3 and E = -EN/3. Moreover, the hole depth varies from 9 up to 125 nm with q = 2/3 and E = -1.73 eV. Furthermore, a threshold coverage of at least 0.2 monolayers (ML) must be deposited before hole formation takes place. In situ electron diffraction indicates that these 0.2 ML are consumed for a surface reconstruction change from (3 × 1) to (2 × 1). For coverages above 2.0 ML holes with a bimodal depth distribution are observed.

  19. Phosphorus storage and mobilization in coastal Phragmites wetlands: Influence of local-scale hydrodynamics

    NASA Astrophysics Data System (ADS)

    Karstens, Svenja; Buczko, Uwe; Glatzel, Stephan

    2016-04-01

    Coastal Phragmites wetlands are at the interface between terrestrial and aquatic ecosystems and are of paramount importance for nutrient regulation. They can act both as sinks and sources for phosphorus, depending on environmental conditions, sediment properties as well as on antecedent nutrient loading and sorption capacity of the sediments. The Darss-Zingst Bodden Chain is a shallow lagoon system at the German Baltic Sea coast with a long eutrophication history. It is lined almost at its entire length by reed wetlands. In order to elucidate under which conditions these wetlands act as sources or sinks for phosphorus, in-situ data of chemo-physical characteristics of water and sediment samples were combined with hydrodynamic measurements and laboratory experiments. Small-scale basin structures within the wetland serve as sinks for fine-grained particles rich in phosphorus, iron, manganese and organic matter. Without turbulent mixing the bottom water and the sediment surface lack replenishment of oxygen. During stagnant periods with low water level, low turbulence and thus low-oxygen conditions phosphorus from the sediments is released. But the sediments are capable of becoming sinks again once oxygen is resupplied. A thin oxic sediment surface layer rich in iron and manganese adsorbs phosphorus quickly. We demonstrate that sediments in coastal Phragmites wetlands can serve both as sources and sinks of soluble reactive phosphorus on a very short time-scale, depending on local-scale hydrodynamics and the state of the oxic-anoxic sediment interface.

  20. Predictable nonwandering localization of covariant Lyapunov vectors and cluster synchronization in scale-free networks of chaotic maps.

    PubMed

    Kuptsov, Pavel V; Kuptsova, Anna V

    2014-09-01

    Covariant Lyapunov vectors for scale-free networks of Hénon maps are highly localized. We revealed two mechanisms of the localization related to full and phase cluster synchronization of network nodes. In both cases the localization nodes remain unaltered in the course of the dynamics, i.e., the localization is nonwandering. Moreover, this is predictable: The localization nodes are found to have specific dynamical and topological properties and they can be found without computing of the covariant vectors. This is an example of explicit relations between the system topology, its phase-space dynamics, and the associated tangent-space dynamics of covariant Lyapunov vectors.

  1. Fast Localization in Large-Scale Environments Using Supervised Indexing of Binary Features.

    PubMed

    Youji Feng; Lixin Fan; Yihong Wu

    2016-01-01

    The essence of image-based localization lies in matching 2D key points in the query image and 3D points in the database. State-of-the-art methods mostly employ sophisticated key point detectors and feature descriptors, e.g., Difference of Gaussian (DoG) and Scale Invariant Feature Transform (SIFT), to ensure robust matching. While a high registration rate is attained, the registration speed is impeded by the expensive key point detection and the descriptor extraction. In this paper, we propose to use efficient key point detectors along with binary feature descriptors, since the extraction of such binary features is extremely fast. The naive usage of binary features, however, does not lend itself to significant speedup of localization, since existing indexing approaches, such as hierarchical clustering trees and locality sensitive hashing, are not efficient enough in indexing binary features and matching binary features turns out to be much slower than matching SIFT features. To overcome this, we propose a much more efficient indexing approach for approximate nearest neighbor search of binary features. This approach resorts to randomized trees that are constructed in a supervised training process by exploiting the label information derived from that multiple features correspond to a common 3D point. In the tree construction process, node tests are selected in a way such that trees have uniform leaf sizes and low error rates, which are two desired properties for efficient approximate nearest neighbor search. To further improve the search efficiency, a probabilistic priority search strategy is adopted. Apart from the label information, this strategy also uses non-binary pixel intensity differences available in descriptor extraction. By using the proposed indexing approach, matching binary features is no longer much slower but slightly faster than matching SIFT features. Consequently, the overall localization speed is significantly improved due to the much faster key

  2. Field-Scale Modeling of Local Capillary Trapping During CO2 Injection into a Saline Aquifer

    NASA Astrophysics Data System (ADS)

    Ren, B.; Lake, L. W.; Bryant, S. L.

    2015-12-01

    Local capillary trapping is the small-scale (10-2 to 10+1 m) CO2 trapping that is caused by the capillary pressure heterogeneity. The benefit of LCT, applied specially to CO2 sequestration, is that saturation of stored CO2 is larger than the residual gas, yet these CO2 are not susceptible to leakage through failed seals. Thus quantifying the extent of local capillary trapping is valuable in design and risk assessment of geologic storage projects. Modeling local capillary trapping is computationally expensive and may even be intractable using a conventional reservoir simulator. In this paper, we propose a novel method to model local capillary trapping by combining geologic criteria and connectivity analysis. The connectivity analysis originally developed for characterizing well-to-reservoir connectivity is adapted to this problem by means of a newly defined edge weight property between neighboring grid blocks, which accounts for the multiphase flow properties, injection rate, and gravity effect. Then the connectivity is estimated from shortest path algorithm to predict the CO2 migration behavior and plume shape during injection. A geologic criteria algorithm is developed to estimate the potential local capillary traps based only on the entry capillary pressure field. The latter is correlated to a geostatistical realization of permeability field. The extended connectivity analysis shows a good match of CO2 plume computed by the full-physics simulation. We then incorporate it into the geologic algorithm to quantify the amount of LCT structures identified within the entry capillary pressure field that can be filled during CO2 injection. Several simulations are conducted in the reservoirs with different level of heterogeneity (measured by the Dykstra-Parsons coefficient) under various injection scenarios. We find that there exists a threshold Dykstra-Parsons coefficient, below which low injection rate gives rise to more LCT; whereas higher injection rate increases LCT

  3. Validation of soil hydraulic pedotransfer functions at the local and catchment scale for an Indonesian basin

    NASA Astrophysics Data System (ADS)

    Booij, Martijn J.; Oldhoff, Ruben J. J.; Rustanto, Andry

    2016-04-01

    In order to accurately model the hydrological processes in a catchment, information on the soil hydraulic properties is of great importance. These data can be obtained by conducting field work, which is costly and time consuming, or by using pedotransfer functions (PTFs). A PTF is an empirical relationship between easily obtainable soil characteristics and a soil hydraulic parameter. In this study, PTFs for the saturated hydraulic conductivity (Ks) and the available water content (AWC) are investigated. PTFs are area-specific, since for instance tropical soils often have a different composition and hydraulic behaviour compared to temperate soils. Application of temperate soil PTFs on tropical soils might result in poor performance, which is a problem as few tropical soil PTFs are available. The objective of this study is to determine whether Ks and AWC can be accurately approximated using PTFs, by analysing their performance at both the local scale and the catchment scale. Four published PTFs for Ks and AWC are validated on a data set of 91 soil samples collected in the Upper Bengawan Solo catchment on Java, Indonesia. The AWC is predicted very poorly, with Nash-Sutcliffe Efficiency (NSE) values below zero for all selected PTFs. For Ks PTFs better results were found. The Wösten and Rosetta-3 PTFs predict the Ks moderately accurate, with NSE values of 0.28 and 0.39, respectively. New PTFs for both AWC and Ks were developed using multiple linear regression and NSE values of 0.37 (AWC) and 0.55 (Ks) were obtained. Although these values are not very high, they are significantly higher than for the published PTFs. The hydrological SWAT model was set up for the Keduang, a sub-catchment of the Upper Bengawan Solo River, to simulate monthly catchment streamflow. Eleven cases were defined to validate the PTFs at the catchment scale. For the Ks-PTF cases NSE values of around 0.84 were obtained for the validation period. The use of AWC PTFs resulted in slightly lower NSE

  4. Sub-seasonal predictability of water scarcity at global and local scale

    NASA Astrophysics Data System (ADS)

    Wanders, N.; Wada, Y.; Wood, E. F.

    2016-12-01

    Forecasting the water demand and availability for agriculture and energy production has been neglected in previous research, partly due to the fact that most large-scale hydrological models lack the skill to forecast human water demands at sub-seasonal time scale. We study the potential of a sub-seasonal water scarcity forecasting system for improved water management decision making and improved estimates of water demand and availability. We have generated 32 years of global sub-seasonal multi-model water availability, demand and scarcity forecasts. The quality of the forecasts is compared to a reference forecast derived from resampling historic weather observations. The newly developed system has been evaluated for both the global scale and in a real-time local application in the Sacramento valley for the Trinity, Shasta and Oroville reservoirs, where the water demand for agriculture and hydropower is high. On the global scale we find that the reference forecast shows high initial forecast skill (up to 8 months) for water scarcity in the eastern US, Central Asia and Sub-Saharan Africa. Adding dynamical sub-seasonal forecasts results in a clear improvement for most regions in the world, increasing the forecasts' lead time by 2 or more months on average. The strongest improvements are found in the US, Brazil, Central Asia and Australia. For the Sacramento valley we can accurately predict anomalies in the reservoir inflow, hydropower potential and the downstream irrigation water demand 6 months in advance. This allow us to forecast potential water scarcity in the Sacramento valley and adjust the reservoir management to prevent deficits in energy or irrigation water availability. The newly developed forecast system shows that it is possible to reduce the vulnerability to upcoming water scarcity events and allows optimization of the distribution of the available water between the agricultural and energy sector half a year in advance.

  5. Interface localization transition in Ising films with competing walls: Ginzburg criterion and crossover scaling

    NASA Astrophysics Data System (ADS)

    Binder, K.; Evans, R.; Landau, D. P.; Ferrenberg, A. M.

    1996-05-01

    In a simple fluid or Ising magnet in a thin film geometry confined between walls a distance D apart that exert opposing surface fields, an interface parallel to the walls is stabilized below the bulk critical temperature Tcb. While this interface is ``delocalized'' (i.e., freely fluctuating in the center of the film) for Tcb>~T>~Tc(D), below the ``interface localization transition'' temperature Tc(D) the interface is bound to one of the walls. Using the mean field description of Parry and Evans [Physica A 181, 250 (1992)], we develop a Ginzburg criterion to show that the Ginzburg number scales exponentially with thickness, Gi~exp(-κD/2), κ-1 being the appropriate transverse length scale associated with the interface. Therefore, mean field theory is self-consistent for large D, thus explaining why recent Monte Carlo simulations observed Ising criticality only in a very close neighborhood of Tc(D). A crossover scaling description is used to work out the thickness dependence of the critical amplitudes in the Ising critical regime. Extending these concepts to consider finite size effects associated with the lateral linear dimension L, we reanalyze the Monte Carlo results of Binder, Landau, and Ferrenberg [Phys. Rev. B 51, 2823 (1995)]. The data are in reasonable agreement with the theory, provided one accepts the suggestion of Parry et al. [Physica A 218, 77 (1995); 218, 109 (1995)] that the length scale κ-1=ξb(1+ω/2), where ξb is the true correlation range in the bulk, and ω is the universal amplitude associated with the interfacial stiffness.

  6. Effects of large scale deforestation on precipitation in the monsoon regions: Remote versus local effects

    NASA Astrophysics Data System (ADS)

    Bala, G.; N, D.; Modak, A.

    2015-12-01

    In this study, we investigate the bio-geophysical effects of large-scale deforestation on monsoon regions using idealized deforestation simulations. The simulations are performed using the NCAR CAM5 atmospheric model coupled to a mixed layer ocean model. The four deforestation experiments are named Global, Boreal, Temperate and Tropical, respectively. In these deforestation experiments, trees are replaced by grasses around the globe, between 20oS and 20oN, between 20oN and 50oN and poleward of 50oN, respectively. We find that the remote forcing from large-scale deforestation in the Temperate and Boreal cases shift the Inter-tropical Convergence Zone (ITCZ) southward. This results in a significant decrease in precipitation in the Northern Hemisphere monsoon regions (East Asia, North America, North Africa, South Asia) and moderate precipitation increases in the Southern Hemisphere monsoon regions (South Africa, South America and Australia). The magnitude of the monsoonal precipitation changes depend on the location of deforestation with remote effects showing a larger influence than local effects. The South Asian Monsoon region is affected the most with 18% decline in precipitation over India in the Global deforestation case. Our results indicate that any comprehensive assessment of afforestation/reforestation as climate change mitigation strategies should carefully evaluate the remote effects on monsoonal precipitation besides the large local impacts on temperatures and carbon sequestration benefits. Our results also demonstrate the linkages between any large scale forcing that causes large warming/cooling in the high latitudes and rainfall changes in tropical monsoonal regions via ITCZ shifts. Figure Caption: Changes in annual mean precipitation (mm/day) between the deforestation experiments and the control simulation. Hatched areas are regions where changes are statistically significant at the 95% confidence level. Shading in line plots represents the ±1 standard

  7. Semi-local scaling and turbulence modulation in variable property turbulent channel flows

    NASA Astrophysics Data System (ADS)

    Patel, Ashish; Peeters, Jurriaan W. R.; Boersma, Bendiks J.; Pecnik, Rene

    2015-09-01

    We theoretically and numerically investigate the effect of temperature dependent density and viscosity on turbulence in channel flows. First, a mathematical framework is developed to support the validity of the semi-local scaling as proposed based on heuristic arguments by Huang, Coleman, and Bradshaw ["Compressible turbulent channel flows: DNS results and modelling," J. Fluid Mech. 305, 185-218 (1995)]. Second, direct numerical simulations (DNS) of turbulent channel flows with different constitutive relations for density and viscosity are performed to assess and validate the semi-local scaling for turbulent statistics. The DNS database is obtained by solving the low-Mach number approximation of the Navier-Stokes equation. Finally, we quantify the modulation of turbulence due to changes in fluid properties. In the simulations, the fluid is internally heated and the temperature at both channel walls is fixed, such that the friction Reynolds number based on wall quantities is Reτ = 395 for all cases investigated. We show that for a case with variable density ρ and viscosity μ, but constant semi-local Reynolds number R eτ ∗ ≡ √{ ( ρ ¯ / ρ w ) } / ( μ ¯ / μ w ) R e τ (where bar and subscript w, denote Reynolds averaging and averaged wall quantity, respectively), across the whole channel height, the turbulent statistics exhibit quasi-similarity with constant property turbulent flows. For cases where R eτ ∗ ≠ R e τ across the channel, we found that quasi-similarity is maintained for cases with similar R eτ ∗ distributions, even if their individual mean density and viscosity profiles substantially differ. With a decrease of R eτ ∗ towards the channel center ( R eτ ∗ < R e τ ), we show that the anisotropy increases and the pre-multiplied stream-wise spectra reveal that this increase is associated with strengthening of the large scale streaks in the buffer layer. The opposite effect is observed when R eτ ∗ increases towards the channel

  8. Dynamics of choice: relative rate and amount affect local preference at three different time scales.

    PubMed

    Aparicio, Carlos F; Baum, William M

    2009-05-01

    To examine extended control over local choice, the present study investigated preference in transition as food-rate ratio provided by two levers changed across seven components within daily sessions, and food-amount ratio changed across phases. Phase 1 arranged a food-amount ratio of 4:1 (i.e., the left lever delivered four pellets and the right lever one pellet); Phase 2 reversed the food-amount ratio to 1:4, and in Phase 3 the food-amount ratio was 3:2. At a relatively extended time scale, preference was described well by a linear relation between log response ratio and log rate ratio (the generalized matching law). A small amount of carryover occurred from one rate ratio to the next but disappeared after four food deliveries. Estimates of sensitivity to food-amount ratio were around 1.0 and were independent of rate ratio. Analysis across food deliveries within rate-ratio components showed that the effect of a small amount was diminished by the presence of a large amount-that is, when a larger amount was present in the situation (three or four pellets), the value of a small amount (one or two pellets) became paltry. More local analysis of visits to the levers between food deliveries showed that postfood visits following a large amount were disproportionately longer than following a small amount. Continuing food deliveries from the same source tended to make visits less dependent on relative amount, but a discontinuation (i.e., food from the other lever) reinstated dependence on relative amount. Analysis at a still smaller time scale revealed preference pulses following food deliveries that confirmed the tendency toward dependence on absolute amount with continuing deliveries, and toward dependence on relative amount following discontinuations. A mathematical model based on a linear-operator equation accounts for many of the results. The larger and longer preference following a switch to a larger amount is consistent with the idea that local preference depends on

  9. DYNAMICS OF CHOICE: RELATIVE RATE AND AMOUNT AFFECT LOCAL PREFERENCE AT THREE DIFFERENT TIME SCALES

    PubMed Central

    Aparicio, Carlos F; Baum, William M

    2009-01-01

    To examine extended control over local choice, the present study investigated preference in transition as food-rate ratio provided by two levers changed across seven components within daily sessions, and food-amount ratio changed across phases. Phase 1 arranged a food-amount ratio of 4∶1 (i.e., the left lever delivered four pellets and the right lever one pellet); Phase 2 reversed the food-amount ratio to 1∶4, and in Phase 3 the food-amount ratio was 3∶2. At a relatively extended time scale, preference was described well by a linear relation between log response ratio and log rate ratio (the generalized matching law). A small amount of carryover occurred from one rate ratio to the next but disappeared after four food deliveries. Estimates of sensitivity to food-amount ratio were around 1.0 and were independent of rate ratio. Analysis across food deliveries within rate-ratio components showed that the effect of a small amount was diminished by the presence of a large amount—that is, when a larger amount was present in the situation (three or four pellets), the value of a small amount (one or two pellets) became paltry. More local analysis of visits to the levers between food deliveries showed that postfood visits following a large amount were disproportionately longer than following a small amount. Continuing food deliveries from the same source tended to make visits less dependent on relative amount, but a discontinuation (i.e., food from the other lever) reinstated dependence on relative amount. Analysis at a still smaller time scale revealed preference pulses following food deliveries that confirmed the tendency toward dependence on absolute amount with continuing deliveries, and toward dependence on relative amount following discontinuations. A mathematical model based on a linear-operator equation accounts for many of the results. The larger and longer preference following a switch to a larger amount is consistent with the idea that local preference

  10. Contextual Explanations of Local Dependence in Item Clusters in a Large Scale Hands-On Science Performance Assessment.

    ERIC Educational Resources Information Center

    Ferrara, Steven; Huynh, Huynh; Michaels, Hillary

    1999-01-01

    Provides hypothesized explanations for local item dependence (LID) in a large-scale hands-on science performance assessment involving approximately 55,000 students each at grades 3, 5, and 8. Items that appear to elicit locally dependent responses require examinees to answer and explain their answers or to use given or generalized information to…

  11. Critical length scales and strain localization govern the mechanical performance of multi-layer graphene assemblies

    NASA Astrophysics Data System (ADS)

    Xia, Wenjie; Ruiz, Luis; Pugno, Nicola M.; Keten, Sinan

    2016-03-01

    Multi-layer graphene assemblies (MLGs) or fibers with a staggered architecture exhibit high toughness and failure strain that surpass those of the constituent single sheets. However, how the architectural parameters such as the sheet overlap length affect these mechanical properties remains unknown due in part to the limitations of mechanical continuum models. By exploring the mechanics of MLG assemblies under tensile deformation using our established coarse-grained molecular modeling framework, we have identified three different critical interlayer overlap lengths controlling the strength, plastic stress, and toughness of MLGs, respectively. The shortest critical length scale Lsc governs the strength of the assembly as predicted by the shear-lag model. The intermediate critical length Lpc is associated with a dynamic frictional process that governs the strain localization propensity of the assembly, and hence the failure strain. The largest critical length scale LTc corresponds to the overlap length necessary to achieve 90% of the maximum theoretical toughness of the material. Our analyses provide the general guidelines for tuning the constitutive properties and toughness of multilayer 2D nanomaterials using elasticity, interlayer adhesion energy and geometry as molecular design parameters.Multi-layer graphene assemblies (MLGs) or fibers with a staggered architecture exhibit high toughness and failure strain that surpass those of the constituent single sheets. However, how the architectural parameters such as the sheet overlap length affect these mechanical properties remains unknown due in part to the limitations of mechanical continuum models. By exploring the mechanics of MLG assemblies under tensile deformation using our established coarse-grained molecular modeling framework, we have identified three different critical interlayer overlap lengths controlling the strength, plastic stress, and toughness of MLGs, respectively. The shortest critical length scale

  12. Local-Scale Air Quality Modeling in Support of Human Health and Exposure Research (Invited)

    NASA Astrophysics Data System (ADS)

    Isakov, V.

    2010-12-01

    Spatially- and temporally-sparse information on air quality is a key concern for air-pollution-related environmental health studies. Monitor networks are sparse in both space and time, are costly to maintain, and are often designed purposely to avoid detecting highly localized sources. Recent studies have shown that more narrowly defining the geographic domain of the study populations and improvements in the measured/estimated ambient concentrations can lead to stronger associations between air pollution and hospital admissions and mortality records. Traditionally, ambient air quality measurements have been used as a primary input to support human health and exposure research. However, there is increasing evidence that the current ambient monitoring network is not capturing sharp gradients in exposure due to the presence of high concentration levels near, for example, major roadways. Many air pollutants exhibit large concentration gradients near large emitters such as major roadways, factories, ports, etc. To overcome these limitations, researchers are now beginning to use air quality models to support air pollution exposure and health studies. There are many advantages to using air quality models over traditional approaches based on existing ambient measurements alone. First, models can provide spatially- and temporally-resolved concentrations as direct input to exposure and health studies and thus better defining the concentration levels for the population in the geographic domain. Air quality models have a long history of use in air pollution regulations, and supported by regulatory agencies and a large user community. Also, models can provide bidirectional linkages between sources of emissions and ambient concentrations, thus allowing exploration of various mitigation strategies to reduce risk to exposure. In order to provide best estimates of air concentrations to support human health and exposure studies, model estimates should consider local-scale features

  13. Local discrepancies in continental scale biomass maps: a case study over forested and non-forested landscapes in Maryland, USA

    Treesearch

    Wenli Huang; Anu Swatantran; Kristofer Johnson; Laura Duncanson; Hao Tang; Jarlath O' Neil Dunne; George Hurtt; Ralph. Dubayah

    2015-01-01

    Continental-scale aboveground biomass maps are increasingly available, but their estimates vary widely, particularly at high resolution. A comprehensive understanding of map discrepancies is required to improve their effectiveness in carbon accounting and local decision-making. To this end, we compare four continental-scale maps with a recent high-resolution lidar-...

  14. On the doublet/triplet splitting and intermediate mass scales in locally supersymmetric SO(10)

    NASA Astrophysics Data System (ADS)

    Pulido, João

    1985-01-01

    In the light of the doublet/triplet splitting, the possibilities for an intermediate mass scale in locally supersymmetric SO(10) are analysed. It is found that the subgroup SU(4)c × SU(2)L × SU(2)R and more generally left-right symmetric models are unlikely to survive as intermediate symmetries since they imply too large values of the weak mixing angle. An alternative model using the subgroup SU(3)c × U(1)L × U(1)R is discussed. Requirements from global SUSY preservation impose an extra constraint and predictions for the grand unification and the intermediate masses are obtained at MX ~ 6 × 1015 GeV and MI ~ 1012 GeV. Address after March 1984: Centro de Fisica da Materia Condensada, Av. Prof. Gama Pinto, 2, 1699 Lisbon Codex, Portugal.

  15. Local versus global knowledge in the Barabási-Albert scale-free network model.

    PubMed

    Gómez-Gardeñes, Jesús; Moreno, Yamir

    2004-03-01

    The scale-free model of Barabási and Albert (BA) gave rise to a burst of activity in the field of complex networks. In this paper, we revisit one of the main assumptions of the model, the preferential attachment (PA) rule. We study a model in which the PA rule is applied to a neighborhood of newly created nodes and thus no global knowledge of the network is assumed. We numerically show that global properties of the BA model such as the connectivity distribution and the average shortest path length are quite robust when there is some degree of local knowledge. In contrast, other properties such as the clustering coefficient and degree-degree correlations differ and approach the values measured for real-world networks.

  16. Local Transport Measurements at Mesoscopic Length Scales Using Scanning Tunneling Potentiometry

    NASA Astrophysics Data System (ADS)

    Wang, Weigang; Munakata, Ko; Rozler, Michael; Beasley, Malcolm R.

    2013-06-01

    Under mesoscopic conditions, the transport potential on a thin film carrying a current is theoretically expected to bear spatial variation due to quantum interference. Scanning tunneling potentiometry is the ideal tool to investigate such variation, by virtue of its high spatial resolution. We report in this Letter the first detailed measurement of transport potential under mesoscopic conditions. Epitaxial graphene at a temperature of 17 K was chosen as the initial system for study because the characteristic transport length scales in this material are relatively large. Tip jumping artifacts are a major possible contribution to systematic errors; and we mitigate such problems by using custom-made slender and sharp tips manufactured by focused ion beam. In our data, we observe residual resistivity dipoles associated with topographical defects, and local peaks and dips in the potential that are not associated with topographical defects.

  17. Local-scale variation in malaria infection amongst rural Gambian children estimated by satellite remote sensing.

    PubMed

    Thomas, C J; Lindsay, S W

    2000-01-01

    We investigated local-scale variation in malaria transmission and infection in children within a continuous landscape by retrospective spatial analysis of entomological and clinical data collected during 1988 and 1989 in The Gambia, West Africa. Parasite prevalence was negatively correlated with vector abundance and exposure to malaria parasites in 10 villages where entomological surveillance had been carried out. Variation in bednet use did not explain this finding. Mosquito-breeding habitat was retrospectively mapped using 20-m spatial resolution multispectral SPOT satellite imagery from 1988. From these data we estimated by linear regression the risk of exposure to malaria parasites in 26 villages where clinical surveys of children had been made. As exposure increased, so did parasite prevalence; but at higher levels of exposure, parasite prevalence declined. Our findings demonstrate marked differences in exposure to malaria in villages over distances of less than 2 km from mosquito breeding sites and suggest that there are also large differences in immunity between neighbouring settlements.

  18. Review of energy confinement and local transport scaling results in neutral-beam-heated tokamaks

    SciTech Connect

    Kaye, S.M.

    1985-05-01

    Over the past several years, tokamak neutral beam injection experiments have evolved from the brute force study of the effects of global discharge characteristics (I/sub p/, anti n/sub e/, P/sub heat/, etc.) on energy confinement to the appreciation that there are effects more subtle, yet controllable, that may influence confinement dramatically. While this evolution from first to second generation experiments is derived from an empirical understanding of low and high energy confinement modes and how to achieve them operationally, the underlying physics is still unknown. Several theories with different physical bases appear to describe the global scaling of the low confinement mode discharges quite well. On the other hand, little agreement has been found between theoretical and experimentally deduced values of local transport coefficients. While it is known operationally how to achieve any one of several types of high confinement mode discharges, here too, the underlying physics of the transport associated with these modes is poorly understood.

  19. Tracking global change at local scales: Phenology for science, outreach, conservation

    NASA Astrophysics Data System (ADS)

    Sharron, Ed; Mitchell, Brian

    2011-06-01

    A Workshop Exploring the Use of Phenology Studies for Public Engagement; New Orleans, Louisiana, 14 March 2011 ; During a George Wright Society Conference session that was led by the USA National Phenology Network (USANPN; http://www.usanpn.org) and the National Park Service (NPS), professionals from government organizations, nonprofits, and higher-education institutions came together to explore the possibilities of using phenology monitoring to engage the public. One of the most visible effects of global change on ecosystems is shifts in phenology: the timing of biological events such as leafing and flowering, maturation of agricultural plants, emergence of insects, and migration of birds. These shifts are already occurring and reflect biological responses to climate change at local to regional scales. Changes in phenology have important implications for species ecology and resource management and, because they are place-based and tangible, serve as an ideal platform for education, outreach, and citizen science.

  20. Large-scale drivers of local precipitation extremes in convection-permitting climate simulations

    NASA Astrophysics Data System (ADS)

    Chan, Steven C.; Kendon, Elizabeth J.; Roberts, Nigel M.; Fowler, Hayley J.; Blenkinsop, Stephen

    2016-04-01

    The Met Office 1.5-km UKV convective-permitting models (CPM) is used to downscale present-climate and RCP8.5 60-km HadGEM3 GCM simulations. Extreme UK hourly precipitation intensities increase with local near-surface temperatures and humidity; for temperature, the simulated increase rate for the present-climate simulation is about 6.5% K**-1, which is consistent with observations and theoretical expectations. While extreme intensities are higher in the RCP8.5 simulation as higher temperatures are sampled, there is a decline at the highest temperatures due to circulation and relative humidity changes. Extending the analysis to the broader synoptic scale, it is found that circulation patterns, as diagnosed by MSLP or circulation type, play an increased role in the probability of extreme precipitation in the RCP8.5 simulation. Nevertheless for both CPM simulations, vertical instability is the principal driver for extreme precipitation.

  1. The HI Content of Galaxies as a Function of Local Density and Large-Scale Environment

    NASA Astrophysics Data System (ADS)

    Thoreen, Henry; Cantwell, Kelly; Maloney, Erin; Cane, Thomas; Brough Morris, Theodore; Flory, Oscar; Raskin, Mark; Crone-Odekon, Mary; ALFALFA Team

    2017-01-01

    We examine the HI content of galaxies as a function of environment, based on a catalogue of 41527 galaxies that are part of the 70% complete Arecibo Legacy Fast-ALFA (ALFALFA) survey. We use nearest-neighbor methods to characterize local environment, and a modified version of the algorithm developed for the Galaxy and Mass Assembly (GAMA) survey to classify large-scale environment as group, filament, tendril, or void. We compare the HI content in these environments using statistics that include both HI detections and the upper limits on detections from ALFALFA. The large size of the sample allows to statistically compare the HI content in different environments for early-type galaxies as well as late-type galaxies. This work is supported by NSF grants AST-1211005 and AST-1637339, the Skidmore Faculty-Student Summer Research program, and the Schupf Scholars program.

  2. Spatio-temporal surface-subsurface water exchanges: from the local to the watershed scale

    NASA Astrophysics Data System (ADS)

    Rivière, Agnès; Flipo, Nicolas; Mouhri, Amer; Ansart, Patrick; Baudin, Aurélien; Berrhouma, Asma; Bodet, Ludovic; Cocher, Emmanuel; Cucchi, Karina; Durand, Véronique; Flageul, Sébastien; de Fouquet, Chantal; Goblet, Patrick; Hovhannissian, Gaghik; Jost, Anne; Pasquet, Sylvain; Rejiba, Fayçal; Rubin, Yoram; Tallec, Gaëlle; Mouchel, Jean-Marie

    2016-04-01

    Understanding the temporal and spatial variations of the surface-subsurface water exchanges is a prerequisite to achieve sustainable water use in basin. The concept of nested stream-aquifer interfaces (Flipo et al., 2014) is used to simulate the variation of the spatio-temporal surface-subsurface exchanges at the watershed scale from LOcal MOnitoring Stations (LOMOSs) measurements of the stream-aquifer exchanges. This method is applied along the stream network of the Avenelles basin. The Avenelles basin (46 km2) is located 70 km east from Paris. The basin is composed of a multi-layer aquifer system which consists of two limestone aquifers: the Brie aquifer (Oligocene) and the Champigny aquifer (Eocene) separated by a clayey aquitard. The meandering river is shallow, connected with the Brie aquifer in its upstream part and the Champigny aquifer in its downstream part. A high-frequency hydrologic monitoring network was deployed on the basin from 1960. The network measures water levels and water temperatures in the aquifers, and in-stream discharge rates. Five LOMOSs have been operating since 2012 along the stream-network (two upstream, two intermediate, and one downstream site) to monitor spatio-temporal stream-aquifer exchanges over years. LOMOSs are composed of one or two shallow piezometers to monitor the temperature and the hydraulic head variations in the aquifers, two hyporheic zone (HZ) temperature profiles located close to each river bank and one water level and temperature monitoring system in the river. A local 2D thermo-hydro model is used to determine hydrogeological and thermal properties of the aquifer and the HZ by inversion and to quantify the stream-aquifer exchanges at the local scale. We performed a pseudo 3D hydro(geo)logical simulation, over 23 years, at the Avenelles basin scale by the used of CAWAQS modelling platform. The CAWAQS platform is composed of four spatially distributed modules (Surface, Sub-surface, River and Groundwater

  3. ELPIS-JP: a dataset of local-scale daily climate change scenarios for Japan

    PubMed Central

    Iizumi, Toshichika; Semenov, Mikhail A.; Nishimori, Motoki; Ishigooka, Yasushi; Kuwagata, Tsuneo

    2012-01-01

    We developed a dataset of local-scale daily climate change scenarios for Japan (called ELPIS-JP) using the stochastic weather generators (WGs) LARS-WG and, in part, WXGEN. The ELPIS-JP dataset is based on the observed (or estimated) daily weather data for seven climatic variables (daily mean, maximum and minimum temperatures; precipitation; solar radiation; relative humidity; and wind speed) at 938 sites in Japan and climate projections from the multi-model ensemble of global climate models (GCMs) used in the coupled model intercomparison project (CMIP3) and multi-model ensemble of regional climate models form the Japanese downscaling project (called S-5-3). The capability of the WGs to reproduce the statistical features of the observed data for the period 1981–2000 is assessed using several statistical tests and quantile–quantile plots. Overall performance of the WGs was good. The ELPIS-JP dataset consists of two types of daily data: (i) the transient scenarios throughout the twenty-first century using projections from 10 CMIP3 GCMs under three emission scenarios (A1B, A2 and B1) and (ii) the time-slice scenarios for the period 2081–2100 using projections from three S-5-3 regional climate models. The ELPIS-JP dataset is designed to be used in conjunction with process-based impact models (e.g. crop models) for assessment, not only the impacts of mean climate change but also the impacts of changes in climate variability, wet/dry spells and extreme events, as well as the uncertainty of future impacts associated with climate models and emission scenarios. The ELPIS-JP offers an excellent platform for probabilistic assessment of climate change impacts and potential adaptation at a local scale in Japan. PMID:22291226

  4. Methodology for locale-scale monitoring for the PROTHEGO project: the Choirokoitia case study

    NASA Astrophysics Data System (ADS)

    Themistocleous, Kyriacos; Agapiou, Athos; Cuca, Branka; Danezis, Chris; Cigna, Francesca; Margottini, Claudio; Spizzichino, Daniele

    2016-10-01

    PROTHEGO (PROTection of European Cultural HEritage from GeO-hazards) is a collaborative research project funded in the framework of the Joint Programming Initiative on Cultural Heritage and Global Change (JPICH) - Heritage Plus in 2015-2018 (www.prothego.eu). PROTHEGO aims to make an innovative contribution towards the analysis of geohazards in areas of cultural heritage, and uses novel space technology based on radar interferometry (InSAR) to retrieve information on ground stability and motion in the 400+ UNESCO's World Heritage List monuments and sites of Europe. InSAR can be used to measure micro-movements to identify geo-hazards. In order to verify the InSAR image data, field and close range measurements are necessary. This paper presents the methodology for local-scale monitoring of the Choirokoitia study site in Cyprus, inscribed in the UNESCO World Heritage List, and part of the demonstration sites of PROTHEGO. Various field and remote sensing methods will be exploited for the local-scale monitoring, static GNSS, total station, leveling, laser scanning and UAV and compared with the Persistent Scatterer Interferometry results. The in-situ measurements will be taken systematically in order to document any changes and geo-hazards that affect standing archaeological remains. In addition, ground truth from in-situ visits will provide feedback related to the classification results of urban expansion and land use change maps. Available archival and current optical satellite images will be used to calibrate and identify the level of risk at the Cyprus case study site. The ground based geotechnical monitoring will be compared and validated with InSAR data to evaluate cultural heritage sites deformation trend and to understand its behaviour over the last two decades.

  5. From local to national scale DInSAR analysis for the comprehension of Earth's surface dynamics.

    NASA Astrophysics Data System (ADS)

    De Luca, Claudio; Casu, Francesco; Manunta, Michele; Zinno, Ivana; lanari, Riccardo

    2017-04-01

    Earth Observation techniques can be very helpful for the estimation of several sources of ground deformation due to their characteristics of large spatial coverage, high resolution and cost effectiveness. In this scenario, Differential Synthetic Aperture Radar Interferometry (DInSAR) is one of the most effective methodologies for its capability to generate spatially dense deformation maps with centimeter to millimeter accuracy. DInSAR exploits the phase difference (interferogram) between SAR image pairs relevant to acquisitions gathered at different times, but with the same illumination geometry and from sufficiently close flight tracks, whose separation is typically referred to as baseline. Among several, the SBAS algorithm is one of the most used DInSAR approaches and it is aimed at generating displacement time series at a multi-scale level by exploiting a set of small baseline interferograms. SBAS, and generally DInSAR, has taken benefit from the large availability of spaceborne SAR data collected along years by several satellite systems, with particular regard to the European ERS and ENVISAT sensors, which have acquired SAR images worldwide during approximately 20 years. While the application of SBAS to ERS and ENVISAT data at local scale is widely testified, very few examples involving those archives for analysis at huge spatial scale are available in literature. This is mainly due to the required processing power (in terms of CPUs, memory and storage) and the limited availability of automatic processing procedures (unsupervised tools), which are mandatory requirements for obtaining displacement results in a time effective way. Accordingly, in this work we present a methodology for generating the Vertical and Horizontal (East-West) components of Earth's surface deformation at very large (national/continental) spatial scale. In particular, it relies on the availability of a set of SAR data collected over an Area of Interest (AoI), which could be some hundreds

  6. Distinguishing globally-driven changes from regional- and local-scale impacts: The case for long-term and broad-scale studies of recovery from pollution.

    PubMed

    Hawkins, S J; Evans, A J; Mieszkowska, N; Adams, L C; Bray, S; Burrows, M T; Firth, L B; Genner, M J; Leung, K M Y; Moore, P J; Pack, K; Schuster, H; Sims, D W; Whittington, M; Southward, E C

    2017-03-14

    Marine ecosystems are subject to anthropogenic change at global, regional and local scales. Global drivers interact with regional- and local-scale impacts of both a chronic and acute nature. Natural fluctuations and those driven by climate change need to be understood to diagnose local- and regional-scale impacts, and to inform assessments of recovery. Three case studies are used to illustrate the need for long-term studies: (i) separation of the influence of fishing pressure from climate change on bottom fish in the English Channel; (ii) recovery of rocky shore assemblages from the Torrey Canyon oil spill in the southwest of England; (iii) interaction of climate change and chronic Tributyltin pollution affecting recovery of rocky shore populations following the Torrey Canyon oil spill. We emphasize that "baselines" or "reference states" are better viewed as envelopes that are dependent on the time window of observation. Recommendations are made for adaptive management in a rapidly changing world.

  7. Probing Local Ionic Dynamics in Functional Oxides: From Nanometer to Atomic Scale

    NASA Astrophysics Data System (ADS)

    Kalinin, Sergei

    2014-03-01

    Vacancy-mediated electrochemical reactions in oxides underpin multiple applications ranging from electroresistive memories, to chemical sensors to energy conversion systems such as fuel cells. Understanding the functionality in these systems requires probing reversible (oxygen reduction/evolution reaction) and irreversible (cathode degradation and activation, formation of conductive filaments) electrochemical processes. In this talk, I summarize recent advances in probing and controlling these transformations locally on nanometer level using scanning probe microscopy. The localized tip concentrates the electric field in the nanometer scale volume of material, inducing local transition. Measured simultaneously electromechanical response (piezoresponse) or current (conductive AFM) provides the information on the bias-induced changes in material. Here, I illustrate how these methods can be extended to study local electrochemical transformations, including vacancy dynamics in oxides such as titanates, LaxSr1-xCoO3, BiFeO3, and YxZr1-xO2. The formation of electromechanical hysteresis loops and their bias-, temperature- and environment dependences provide insight into local electrochemical mechanisms. In materials such as lanthanum-strontium cobaltite, mapping both reversible vacancy motion and vacancy ordering and static deformation is possible, and can be corroborated by post mortem STEM/EELS studies. In ceria, a broad gamut of electrochemical behaviors is observed as a function of temperature and humidity. The possible strategies for elucidation ionic motion at the electroactive interfaces in oxides using high-resolution electron microscopy and combined ex-situ and in-situ STEM-SPM studies are discussed. In the second part of the talk, probing electrochemical phenomena on in-situ grown surfaces with atomic resolution is illustrated. I present an approach based on the multivariate statistical analysis of the coordination spheres of individual atoms to reveal

  8. Understanding local-scale drivers of biodiversity outcomes in terrestrial protected areas.

    PubMed

    Barnes, Megan D; Craigie, Ian D; Dudley, Nigel; Hockings, Marc

    2017-07-01

    Conservation relies heavily on protected areas (PAs) maintaining their key biodiversity features to meet global biodiversity conservation goals. However, PAs have had variable success, with many failing to fully maintain their biodiversity features. The current literature concerning what drives variability in PA performance is rapidly expanding but unclear, sometimes contradictory, and spread across multiple disciplines. A clear understanding of the drivers of successful biodiversity conservation in PAs is necessary to make them fully effective. Here, we conduct a comprehensive assessment of the current state of knowledge concerning the drivers of biological outcomes within PAs, focusing on those that can be addressed at local scales. We evaluate evidence in support of potential drivers to identify those that enable more successful outcomes and those that impede success and provide a synthetic review. Interactions are discussed where they are known, and we highlight gaps in understanding. We find that elements of PA design, management, and local and national governance challenges, species and system ecology, and sociopolitical context can all influence outcomes. Adjusting PA management to focus on actions and policies that influence the key drivers identified here could improve global biodiversity outcomes. © 2016 New York Academy of Sciences.

  9. Large-Scale Point-Cloud Visualization through Localized Textured Surface Reconstruction.

    PubMed

    Arikan, Murat; Preiner, Reinhold; Scheiblauer, Claus; Jeschke, Stefan; Wimmer, Michael

    2014-09-01

    In this paper, we introduce a novel scene representation for the visualization of large-scale point clouds accompanied by a set of high-resolution photographs. Many real-world applications deal with very densely sampled point-cloud data, which are augmented with photographs that often reveal lighting variations and inaccuracies in registration. Consequently, the high-quality representation of the captured data, i.e., both point clouds and photographs together, is a challenging and time-consuming task. We propose a two-phase approach, in which the first (preprocessing) phase generates multiple overlapping surface patches and handles the problem of seamless texture generation locally for each patch. The second phase stitches these patches at render-time to produce a high-quality visualization of the data. As a result of the proposed localization of the global texturing problem, our algorithm is more than an order of magnitude faster than equivalent mesh-based texturing techniques. Furthermore, since our preprocessing phase requires only a minor fraction of the whole data set at once, we provide maximum flexibility when dealing with growing data sets.

  10. The Local And Large Scale Environment Of Different Types Of Agn

    NASA Astrophysics Data System (ADS)

    Efthymiadou, Anastasia

    2017-06-01

    We study the local and large scale environment of different types of AGN defining the overdensity distribution of optical galaxies within different distances. Moreover, we investigate the activity of their close companions in order to test different models of the triggering mechanism of AGN. According to the Unification Scheme, the AGN phenomenology can be explained by a single type of AGN having different inclinations of their dust torus with respect to the observer's line of sight. However, an evolutionary scenario, which starts with a circumnuclear starburst phase, with the nucleus subsequently being obscured by dust (Type II AGN) and eventually ending as a Type I AGN, suggests that the appearance of an AGN depends also on its current evolutionary stage. Possible indications of different types of AGN residing in denser local environment, compared to other types, would support the merger scenario, and therefore, the obscuration of the central region and the possible activation of the central black hole. With our current study we wish to investigate whether the environment of different types of AGN is similar, since this is the expectation of the Unification paradigm or whether it is different, a fact that could support the evolutionary scenario. We find differences in the environment of different AGN types and therefore, conclude that the environment indeed affects the spectral type of galaxies.

  11. The Local And Large Scale Environment Of Different Types Of Agn

    NASA Astrophysics Data System (ADS)

    Efthymiadou, Anastasia

    2017-06-01

    We study the local and large scale environment of different types of AGN defining the overdensity distribution of optical galaxies within different distances. Moreover, we investigate the activity of their close companions in order to test different models of the triggering mechanism of AGN. According to the Unification Scheme, the AGN phenomenology can be explained by a single type of AGN having different inclinations of their dust torus with respect to the observer's line of sight. However, an evolutionary scenario, which starts with a circumnuclear starburst phase, with the nucleus subsequently being obscured by dust (Type II AGN) and eventually ending as a type I AGN, suggests that the appearance of an AGN depends also on its current evolutionary stage. Possible indications of different types of AGN residing in denser local environment, compared to other types, would support the merger scenario, and therefore, the obscuration of the central region and the possible activation of the central black hole. With our current study we wish to investigate whether the environment of different types of AGN is similar, since this is the expectation of the Unification paradigm or whether it is different, a fact that could support the evolutionary scenario. We find differences in the environment of different AGN types and therefore, conclude that the environment indeed affects the spectral type of galaxies.

  12. Local scale-invariance of the 2  +  1 dimensional Kardar–Parisi–Zhang model

    NASA Astrophysics Data System (ADS)

    Kelling, Jeffrey; Ódor, Géza; Gemming, Sibylle

    2017-03-01

    Local scale-invariance theory is tested by extensive dynamical simulations of the driven dimer lattice gas model, describing the surface growth of the 2  +  1 dimensional Kardar–Parisi–Zhang surfaces. Very precise measurements of the universal autoresponse function enabled us to perform nonlinear fitting with the scaling forms, suggested by local scale-invariance (LSI). While the simple LSI ansatz does not seem to work, forms based on logarithmic extension of LSI provide satisfactory description of the full (measured) time evolution of the autoresponse function.

  13. Integration of remote sensing datasets for local scale assessment and prediction of drought.

    PubMed

    Nichol, Janet E; Abbas, Sawaid

    2015-02-01

    Recent attempts to integrate remote sensing-based drought indices with precipitation data seem promising, and can compensate for potential uncertainties from image-based parameters alone, which may be unrelated to meteorological drought. However most remote sensing-based studies have been at regional or global scale and have not considered differences between different land cover types. This study examines a drought-prone region in Central Yunnan Province of China over a four-year period including a notable severe drought event in 2010. The study investigates the phase relationships between meteorological drought from image-based rainfall estimates from the Tropical Rainfall Measurement Mission (TRMM), and imaged drought from a remote sensing drought index, the Normalised Vegetation Supply Water Index (NVSWI) for different land cover types at local scale. The land cover types derived from MODIS and Landsat images were resampled to 250 m to match all datasets used. Significant differences between cover types are observed, with cropland and shrubland most highly correlated with 64 days' earlier rainfall and evergreen forest most responsive to rainfall 90 days earlier, indicating a need to consider detailed land cover information for accurate integrated drought indices. The finding that concurrent rainfall is only weakly correlated with observed drought, suggests that existing drought indices, which compute lowest weightings for the most distant lag period would be unrepresentative.

  14. Magnetic local time variation and scaling of poleward auroral boundary dynamics

    NASA Astrophysics Data System (ADS)

    Longden, N.; Chisham, G.; Freeman, M. P.

    2014-12-01

    The balance of dayside and nightside reconnection processes within the Earth's magnetosphere and its effect on the amount of open magnetic flux threading the ionosphere is well understood in terms of the expanding-contracting polar cap model. However, the nature and character of the consequential fluctuations in the polar cap boundary are poorly understood. By using the poleward auroral luminosity boundary (PALB), as measured by the FUV instrument of the IMAGE spacecraft, as a proxy for the polar cap boundary, we have studied the motion of this boundary for more than 2 years across the complete range of magnetic local time. Our results show that the dayside PALB dynamics are broadly self-similar on timescales of 12 min to 6 h and appear to be monofractal. Similarity with the characteristics of solar wind and interplanetary magnetic field variability suggests that this dayside monofractal behavior is predominantly inherited from the solar wind via the reconnection process. The nightside PALB dynamics exhibit scale-free behavior at intermediate time scales (12-90 min) and appear to be multifractal. We propose that this character is a result of the intermittent multifractal structure of magnetotail reconnection.

  15. Fine-scale genetic differentiation of a temperate herb: relevance of local environments and demographic change

    PubMed Central

    Sato, Yasuhiro; Kudoh, Hiroshi

    2014-01-01

    The genetic structure of a plant species is shaped by environmental adaptation and demographic factors, but their relative contributions are still unknown. To examine the environment- or geography-related differentiation, we quantified genetic variation among 41 populations of a temperate herb, Arabidopsis halleri subsp. gemmifera (Brassicaceae). We analysed 19 microsatellite loci, which showed a significant population differentiation and a moderate within-population genetic diversity (global Gst = 0.42 and Hs = 0.19). Our structure analysis and phylogenetic network did not detect more than two genetic groups across the Japanese mainland but found fine-scale genetic differentiations and admixed patterns around the central area. Across the Japanese mainland, we found significant evidence for isolation-by-distance but not for isolation-by-environments. However, at least within the central area, the magnitude of genetic differentiation tended to increase with microhabitat dissimilarity under light conditions and water availability. Furthermore, most populations have been estimated to experience a recent decline in the effective population size, indicating a possibility of bottleneck effects on the pattern of genetic variation. These findings highlight a potential influence of the microhabitat conditions and demographic changes on the local-scale genetic differentiation among natural plant populations. PMID:25387749

  16. Making continental-scale environmental programs relevant locally for educators with Project BudBurst

    NASA Astrophysics Data System (ADS)

    Goehring, L.; Henderson, S.; Wasser, L.; Newman, S. J.; Ward, D.

    2012-12-01

    Project BudBurst is a national citizen science initiative designed to engage non professionals in observations of phenological (plant life cycle) events that raise awareness of climate change, and create a cadre of informed citizen scientists. Citizen science programs such as Project BudBurst provide excellent opportunities for educators and their students to actively participate in scientific research. Such programs are important not only from an educational perspective, but because they also enable scientists to broaden the geographic and temporal scale of their observations. The goals of Project BudBurst are to 1) increase awareness of phenology as an area of scientific study; 2) increase awareness of the impacts of changing climates on plants at a continental-scale; and 3) increase science literacy by engaging participants in the scientific process. From its 2008 launch, this on-line program has engaged participants of all ages and walks of life in recording the timing of the leafing and flowering of wild and cultivated species found across the continent, and in contemplating the meaning of such data in their local environments. Thus far, thousands of participants from all 50 states have submitted data. This presentation will provide an overview of Project BudBurst educational resources and share lessons learned from educators in implementing the program in formal and informal education settings. Lesson plans and tips from educators will be highlighted. Project BudBurst is co-managed by the National Ecological Observatory Network and the Chicago Botanic Garden.

  17. Martensitic transformation of NiTi studied at the nanometer scale by local mechanical spectroscopy

    SciTech Connect

    Oulevey, F.; Gremaud, G.; Mari, D.; Kulik, A.J.; Burnham, N.A.; Benoit, W.

    1999-12-17

    Near-stoichiometric NiTi alloys exhibit a martensitic phase transformation between a low-temperature monoclinic phase, called martensite, and a high temperature cubic phase with B2 structure, called austenite. This transformation is responsible for the shape memory and pseudo-elastic effects in deformed NiTi alloys. Optical microscopy observation suggests that the transformation occurs very suddenly inside an austenite grain. This has led to the concept of military transformation. The width of the globally measured transformation would then be a sum of different narrow contributions coming from different places inside the sample. this image is, however, not universally accepted. A measurement inside one single grain of a polycrystal would be a way to address these questions. Both the special scale of the R phase distribution and the military character of the transformation will have an effect on the result of such a measurement. The martensitic transformation of such alloys has already been observed on bulk samples by mechanical spectroscopy, i.e., measurement of the inelastic part of the deformation induced by a cyclic stress. Such measurements, also called Internal Friction measurements, give access to the mechanical energy dissipation during the phase transition. However, they give an average behavior of all parts of the sample. This paper reports the first local (i.e., at a submicron scale) mechanical spectroscopy measurement of the martensitic transformation in thermally cycled NiTi alloys.

  18. Biogeographic affinity helps explain productivity-richness relationships at regional and local scales

    USGS Publications Warehouse

    Harrison, S.; Grace, J.B.

    2007-01-01

    The unresolved question of what causes the observed positive relationship between large-scale productivity and species richness has long interested ecologists and evolutionists. Here we examine a potential explanation that we call the biogeographic affinity hypothesis, which proposes that the productivity-richness relationship is a function of species' climatic tolerances that in turn are shaped by the earth's climatic history combined with evolutionary niche conservatism. Using botanical data from regions and sites across California, we find support for a key prediction of this hypothesis, namely, that the productivity-species richness relationship differs strongly and predictably among groups of higher taxa on the basis of their biogeographic affinities (i.e., between families or genera primarily associated with north-temperate, semiarid, or desert zones). We also show that a consideration of biogeographic affinity can yield new insights on how productivity-richness patterns at large geographic scales filter down to affect patterns of species richness and composition within local communities. ?? 2007 by The University of Chicago. All rights reserved.

  19. Anaerobic-ion exchange (AN-IX) process for local-scale nitrogen recovery from wastewater.

    PubMed

    Smith, Daniel P; Smith, Nathaniel T

    2015-11-01

    An anaerobic-ion exchange (AN-IX) process was developed for point-of-origin recovery of nitrogen from household wastewater. The process features upflow solids-blanket anaerobic treatment (ammonification) followed by ammonium ion exchange onto natural zeolite. The AN-IX system is configured as a series of linked upflow chambers that operate passively without energy input, and is amenable to intermittent and seasonal operation. A 57L prototype was operated for over 1.8 years treating actual wastewater under field conditions. Total nitrogen removal exceeded 96% through the first 160 days of operation and effluent ammonium nitrogen remained below detection for 300 days. Ion exchange chambers exhibited sequential NH4(+)-N breakthrough over extended operation and complete media exhaustion was approached at Day 355. The ammonium capacity of zeolite was estimated as 13.5mg NH4(+)-N per gram dry weight. AN-IX is a resilient and cost effective process for local-scale nitrogen recovery and reuse, suitable for small scale and larger systems.

  20. The scale of local adaptation in Mimulus guttatus: comparing life history races, ecotypes, and populations.

    PubMed

    Peterson, Megan L; Kay, Kathleen M; Angert, Amy L

    2016-07-01

    Fitness trade-offs between environments are central to the evolution of biodiversity. Although transplant studies often document fitness trade-offs consistent with local adaptation (LA), many have also found an advantage of foreign genotypes (foreign advantage (FA)). Understanding the mechanisms driving the magnitude and distribution of fitness variation requires comparative approaches that test the ecological scales at which these different patterns emerge. We used a common garden transplant experiment to compare the relative fitnesses of native vs foreign genotypes at three nested ecological scales within Mimulus guttatus: annual vs perennial life history races, perennial ecotypes across an elevational range, and populations within perennial elevational ecotypes. We integrated fitness across the life-cycle and decomposed LA vs FA into contributions from different fitness components. We found LA, measured as home-site advantage, between annual and perennial races and a trend towards LA among populations within montane habitats. Conversely, we found strong FA of low-elevation perennials in a montane environment. LA between life history races reflects the fitness advantages of adult survival and vegetative growth in a mesic environment. Within the perennial race, recent climate conditions or nonselective processes, such as dispersal limitation or mutational load, could explain FA of low-elevation perennials in a montane environment. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

  1. Critical length scales and strain localization govern the mechanical performance of multi-layer graphene assemblies.

    PubMed

    Xia, Wenjie; Ruiz, Luis; Pugno, Nicola M; Keten, Sinan

    2016-03-28

    Multi-layer graphene assemblies (MLGs) or fibers with a staggered architecture exhibit high toughness and failure strain that surpass those of the constituent single sheets. However, how the architectural parameters such as the sheet overlap length affect these mechanical properties remains unknown due in part to the limitations of mechanical continuum models. By exploring the mechanics of MLG assemblies under tensile deformation using our established coarse-grained molecular modeling framework, we have identified three different critical interlayer overlap lengths controlling the strength, plastic stress, and toughness of MLGs, respectively. The shortest critical length scale L(C)(S) governs the strength of the assembly as predicted by the shear-lag model. The intermediate critical length L(C)(P) is associated with a dynamic frictional process that governs the strain localization propensity of the assembly, and hence the failure strain. The largest critical length scale L(C)(T) corresponds to the overlap length necessary to achieve 90% of the maximum theoretical toughness of the material. Our analyses provide the general guidelines for tuning the constitutive properties and toughness of multilayer 2D nanomaterials using elasticity, interlayer adhesion energy and geometry as molecular design parameters.

  2. Local Scale Radiobrightness Modelling during Intensive Observing Period-4 of the Cold Land Processes Experiment-1

    NASA Technical Reports Server (NTRS)

    Kim, Edward J.; Tedesco, Marco; deRoo, Roger; England, Anthony W.; Gu, Haoyu; Pham, Hanh; Boprie, David; Graf, Tobias; Koike, Toshio; Armstrong, Richard

    2004-01-01

    The NASA Cold Land Processes Field Experiment (CLPX-1) was designed to provide microwave remote sensing observations and ground truth for studies of snow and frozen ground remote sensing, particularly issues related to scaling. CLPX-1 was conducted in the spring of 2003 in Colorado, USA. Initial forward model validation work is concentrating on the Local-Scale Observation Site (LSOS), a 0.8 ha study site consisting of open meadows separated by trees where the most detailed measurements were made of snow depth and temperature, density, and grain size profiles. This paper will focus on the ability of forward Dense Medium Radiative Transfer (DMRT) modelling, combined with snowpack measurements to reproduce the radiobrightness signatures observed by the University of Michigan s Truck-Mounted Radiometer System at 19 and 37 GHz during the 4th Intensive Observing Period (IOP4) in March, 2003. Unlike the earlier IOP3, conditions during IOP4 include both wet and dry periods, providing a valuable test of DMRT model performance. Observations of upwelling and downwelling tree radiobrightness will be used to formulate a simple model for the effect of trees within the field of view. In addition, a comparison will be made for the one day of coincident observations by the University of Tokyo s Ground- Based Microwave Radiometer-7 (GBMR-7). These analyses will help guide the choice of future snow retrieval algorithms and the design of future Cold Lands observing systems.

  3. Verifying the consistency relation for the scale-dependent bias from local primordial non-Gaussianity

    NASA Astrophysics Data System (ADS)

    Biagetti, Matteo; Lazeyras, Titouan; Baldauf, Tobias; Desjacques, Vincent; Schmidt, Fabian

    2017-07-01

    We measure the large-scale bias of dark matter haloes in simulations with non-Gaussian initial conditions of the local type, and compare this bias to the response of the mass function to a change in the primordial amplitude of fluctuations. The two are found to be consistent, as expected from physical arguments, for the three halo-finder algorithms which use different spherical overdensity (SO) and friends-of-friends methods. On the other hand, we find that the commonly used prediction for universal mass functions, that the scale-dependent bias is proportional to the first-order Gaussian Lagrangian bias, does not yield a good agreement with the measurements. For all halo finders, high-mass haloes show a non-Gaussian bias suppressed by 10-15 per cent relative to the universal mass function prediction. For SO haloes, this deviation changes sign at low masses, where the non-Gaussian bias becomes larger than the universal prediction.

  4. Local-scale variability of seepage and hydraulic conductivity in a shallow gravel-bed river

    USGS Publications Warehouse

    Rosenberry, D.O.; Pitlick, J.

    2009-01-01

    Seepage rate and direction measured with a seepage metre modified for use in flowing water were greatly variable along a 300-m reach of a shallow, gravel-bed river and depended primarily on the local-scale bed topography. The median value of seepage measured at 24 locations was 24 cm/day, but seepage measured at specific sites ranged from -340 to +237 cm/day. Seepage also varied substantially over periods of hours to days and occasionally reversed direction in response to evolution of the sediment bed. Vertical hydraulic conductivity was related to seepage direction and was larger during upward seepage than during downward seepage; with differences ranging from 4 to 40% in areas of active sediment transport to more than an order of magnitude in areas where current was too slow to mobilize bed sediment. Seepage was poorly related to hydraulic gradient measured over vertical distances of 0.3 m and appeared to be opposite the hydraulic gradient at 18% of the locations where both parameters were measured. Results demonstrate the scale dependence of these measurements in coarse-grained hyporheic settings and indicate that hydraulic gradients should be determined over a much shorter vertical increment if used to indicate exchange across the sediment-water interface. Published in 2009 by John Wiley & Sons, Ltd.

  5. Local Reanalysis on the convective scale with a fully coupled model (TerrSysMP)

    NASA Astrophysics Data System (ADS)

    Figura, Clarissa; Bick, Theresa; Keller, Jan; Thiele-Eich, Insa; Simmer, Clemens

    2016-04-01

    Reanalyses provide temporally and spatially consistent fields of weather and climate parameters by combining model physics and assimilation of measurements. The generated fields can be used to quantify water and energy budgets and intercompartmental fluxes within the earth system. Reanalyses usually are performed for longer time periods and globally, therefore using a coarsely meshed spatial grid is necessary to delimitate the computational effort. Due to the coarse spatial resolution, local and small scale processes, e.g. within meso scale river catchments, are not well represented, as well as the resulting water and energy budgets. The latter is one of the main research topics of the Transregional Collaborative Research Centre 32 (TR32). Hence, a regional high resolution reanalysis will be performed with a strong limitation of the model area using lateral boundary conditions resulting of an reanalysis with a coarser spatial grid. A new Terrestrial Systems Modeling Platform (TerrSysMP) will be used in the regional reanalysis, which is able to reproduce processes within the atmosphere, surface and groundwater. TerrSysMP is a scale consistent fully coupled modeling system, which is composed of the atmospheric model COSMO, the surface model CLM3.5 (Community Land Model) and the 3-dimensional hydrological model ParFlow. The different models are connected by an external coupler (OASIS3) for the exchange of relevant state vectors. The reanalysis setup uses a spatial resolution of 1 km in the atmosphere and a finer resolution in the ground (~500 m), within an area of approx. 150x150km in central Europe (Rur-catchment and surrounding). This area was chosen, because it includes the study area of TR32 and therefore a lot of different measurements from atmosphere to ground are available for comparison with the modeled parameters. Hence, results of the regional reanalysis will be validated with comprehensive measurements of the terrestrial system, expecting an improved

  6. Local adaptation and population structure at a micro-geographical scale of a fungal parasite on its host plant.

    PubMed

    Capelle, J; Neema, C

    2005-11-01

    Local adaptation, which has been detected for several wild pathosystems is influenced by gene flow and recombination. In this study, we investigate local adaptation and population structure at a fine scale in wild populations of a plant-pathogen fungus. We sampled hierarchically strains of Colletotrichum lindemuthianum in a wild population of its host. The analysis of AFLP patterns obtained for 86 strains indicated that: (i) many different haplotypes can be discriminated, although occurrence of recombination could not be shown; (ii) migration between adjacent plants seemed rare during the season; and (iii) neutral diversity is structured according to groups of plants and individual host plants. Furthermore, we tested for the occurrence of local adaptation using a cross-inoculation experiment. Our results showed local adaptation at the scale of the individual host plant. These results indicate that fine-scale dynamics has evolutionary consequences in this pathosystem.

  7. Spontaneous formation of micrometer-size inorganic peapods.

    PubMed

    Roy, Soumyajit; Rijneveld-Ockers, Maria T; Groenewold, Jan; Kuipers, Bonny W M; Meeldijk, Hans; Kegel, Willem K

    2007-05-08

    We show that polyoxometalate (ammonium phosphomolybdate) Keggin in aqueous dispersions upon sonication spontaneously transforms into micrometer-sized, peapod-shaped structures. The formation of these peapods is preceded by the generation of spherical aggregates. The particles have been characterized experimentally by time-resolved dynamic light scattering (DLS), transmission electron microscopy (TEM), and scanning TEM with a high-angle annular dark field detector (STEM-HAADF) for energy-dispersive X-ray (STEM/EDX) elemental analyses. A pathway for the phenomenon is proposed.

  8. What Shapes the Phylogenetic Structure of Anuran Communities in a Seasonal Environment? The Influence of Determinism at Regional Scale to Stochasticity or Antagonistic Forces at Local Scale

    PubMed Central

    Ferreira, Vanda Lúcia; Strüssmann, Christine; Tomas, Walfrido Moraes

    2015-01-01

    Ecological communities are structured by both deterministic and stochastic processes. We investigated phylogenetic patterns at regional and local scales to understand the influences of seasonal processes in shaping the structure of anuran communities in the southern Pantanal wetland, Brazil. We assessed the phylogenetic structure at different scales, using the Net Relatedness Index (NRI), the Nearest Taxon Index (NTI), and phylobetadiversity indexes, as well as a permutation test, to evaluate the effect of seasonality. The anuran community was represented by a non-random set of species with a high degree of phylogenetic relatedness at the regional scale. However, at the local scale the phylogenetic structure of the community was weakly related with the seasonality of the system, indicating that oriented stochastic processes (e.g. colonization, extinction and ecological drift) and/or antagonist forces drive the structure of such communities in the southern Pantanal. PMID:26102202

  9. Global- and local-scale characterisation of bed surface structure in coarse-grained alluvial rivers

    NASA Astrophysics Data System (ADS)

    Powell, Mark; Ockelford, Annie; Nguyen, Thao; Wood, Jo; Rice, Steve; Reid, Ian; Tate, Nick

    2013-04-01

    It is widely recognised that adjustments in bed surface grain size (texture) and grain arrangement (structure) exert significant controls on the stability of coarse-grained alluvial rivers. Modifications to bed surface texture and structure occur during active sediment transport and are mediated by the process of mobile armouring which concentrates coarser-than-average particles on the surface and organises them into a variety of grain- and bedform-scale configurations. Textural aspects of surface armouring are well understood to the extent that sediment transport models can be used to predict the size distribution of armours that develop under different sediment supply regimes and shear stresses. Research has also found that the adjustment of bed surface grain size is often patchy and that the development of finer-grained and coarser-grained areas of the bed has important implications for both the rate and grain size of transported sediment. The structural aspects of stream-bed armouring, however, are less well understood, largely because of the difficulty of recognising and characterising bedforms and bed-structures that have dimensions similar to their constituent particles. Moreover, bed structure is generally parameterised using global scale descriptors of the bed surface such that information on the spatial heterogeneity of the structure is lost. The aim of this poster is to characterise the structural characteristics of water-worked river gravels, paying particular attention to quantifying the spatial heterogeneity of those characteristics using local scale descriptors. Results reported from a number of flume experiments designed to simulate the spatio-temporal evolution of bed configurations (surface texture and structure) as the system adjusts to a condition of equilibrium transport are used to evaluate the spatial variability of bed surface structure and explore its significance for modelling sediment transport rates in gravel-bed rivers. Keywords: bed

  10. Towards a New Assessment of Urban Areas from Local to Global Scales

    NASA Astrophysics Data System (ADS)

    Bhaduri, B. L.; Roy Chowdhury, P. K.; McKee, J.; Weaver, J.; Bright, E.; Weber, E.

    2015-12-01

    Since early 2000s, starting with NASA MODIS, satellite based remote sensing has facilitated collection of imagery with medium spatial resolution but high temporal resolution (daily). This trend continues with an increasing number of sensors and data products. Increasing spatial and temporal resolutions of remotely sensed data archives, from both public and commercial sources, have significantly enhanced the quality of mapping and change data products. However, even with automation of such analysis on evolving computing platforms, rates of data processing have been suboptimal largely because of the ever-increasing pixel to processor ratio coupled with limitations of the computing architectures. Novel approaches utilizing spatiotemporal data mining techniques and computational architectures have emerged that demonstrates the potential for sustained and geographically scalable landscape monitoring to be operational. We exemplify this challenge with two broad research initiatives on High Performance Geocomputation at Oak Ridge National Laboratory: (a) mapping global settlement distribution; (b) developing national critical infrastructure databases. Our present effort, on large GPU based architectures, to exploit high resolution (1m or less) satellite and airborne imagery for extracting settlements at global scale is yielding understanding of human settlement patterns and urban areas at unprecedented resolution. Comparison of such urban land cover database, with existing national and global land cover products, at various geographic scales in selected parts of the world is revealing intriguing patterns and insights for urban assessment. Early results, from the USA, Taiwan, and Egypt, indicate closer agreements (5-10%) in urban area assessments among databases at larger, aggregated geographic extents. However, spatial variability at local scales could be significantly different (over 50% disagreement).

  11. Local and landscape scale factors influencing edge effects on woodland salamanders.

    PubMed

    Moseley, Kurtis R; Ford, W Mark; Edwards, John W

    2009-04-01

    We examined local and landscape-scale variable influence on the depth and magnitude of edge effects on woodland salamanders in mature mixed mesophytic and northern hardwood forest adjacent to natural gas well sites maintained as wildlife openings. We surveyed woodland salamander occurrence from June-August 2006 at 33 gas well sites in the Monongahela National Forest, West Virginia. We used an information-theoretic approach to test nine a priori models explaining landscape-scale effects on woodland salamander capture proportion within 20 m of field edge. Salamander capture proportion was greater within 0-60 m than 61-100 m of field edges. Similarly, available coarse woody debris proportion was greater within 0-60 m than 61-100 m of field edge. Our ASPECT model, that incorporated the single variable aspect, received the strongest support for explaining landscape-scale effects on salamander capture proportion within 20 m of opening edge. The ASPECT model indicated that fewer salamanders occurred within 20 m of opening edges on drier, hotter southwestern aspects than in moister, cooler northeastern aspects. Our results suggest that forest habitat adjacent to maintained edges and with sufficient cover still can provide suitable habitat for woodland salamander species in central Appalachian mixed mesophytic and northern hardwood forests. Additionally, our modeling results support the contention that edge effects are more severe on southwesterly aspects. These results underscore the importance of distinguishing among different edge types as well as placing survey locations within a landscape context when investigating edge impacts on woodland salamanders.

  12. Multi-scale computational method for elastic bodies with global and local heterogeneity

    NASA Astrophysics Data System (ADS)

    Takano, Naoki; Zako, Masaru; Ishizono, Manabu

    2000-05-01

    A multi-scale computational method using the homogenization theory and the finite element mesh superposition technique is presented for the stress analysis of composite materials and structures from both micro- and macroscopic standpoints. The proposed method is based on the continuum mechanics, and the micro-macro coupling effects are considered for a variety of composites with very complex microstructures. To bridge the gap of the length scale between the microscale and the macroscale, the homogenized material model is basically used. The classical homogenized model can be applied to the case that the microstructures are periodically arrayed in the structure and that the macroscopic strain field is uniform within the microscopic unit cell domain. When these two conditions are satisfied, the homogenization theory provides the most reliable homogenized properties rigorously to the continuum mechanics. This theory can also calculate the microscopic stresses as well as the macroscopic stresses, which is the most attractive advantage of this theory over other homogenizing techniques such as the rule of mixture. The most notable feature of this paper is to utilize the finite element mesh superposition technique along with the homogenization theory in order to analyze cases where non-periodic local heterogeneity exists and the macroscopic field is non-uniform. The accuracy of the analysis using the finite element mesh superposition technique is verified through a simple example. Then, two numerical examples of knitted fabric composite materials and particulate reinforced composite material are shown. In the latter example, a shell-solid connection is also adopted for the cost-effective multi-scale modeling and analysis.

  13. Phylogenetic Analysis of Local-Scale Tree Soil Associations in a Lowland Moist Tropical Forest

    PubMed Central

    Schreeg, Laura A.; Kress, W. John; Erickson, David L.; Swenson, Nathan G.

    2010-01-01

    Background Local plant-soil associations are commonly studied at the species-level, while associations at the level of nodes within a phylogeny have been less well explored. Understanding associations within a phylogenetic context, however, can improve our ability to make predictions across systems and can advance our understanding of the role of evolutionary history in structuring communities. Methodology/Principal Findings Here we quantified evolutionary signal in plant-soil associations using a DNA sequence-based community phylogeny and several soil variables (e.g., extractable phosphorus, aluminum and manganese, pH, and slope as a proxy for soil water). We used published plant distributional data from the 50-ha plot on Barro Colorado Island (BCI), Republic of Panamá. Our results suggest some groups of closely related species do share similar soil associations. Most notably, the node shared by Myrtaceae and Vochysiaceae was associated with high levels of aluminum, a potentially toxic element. The node shared by Apocynaceae was associated with high extractable phosphorus, a nutrient that could be limiting on a taxon specific level. The node shared by the large group of Laurales and Magnoliales was associated with both low extractable phosphorus and with steeper slope. Despite significant node-specific associations, this study detected little to no phylogeny-wide signal. We consider the majority of the ‘traits’ (i.e., soil variables) evaluated to fall within the category of ecological traits. We suggest that, given this category of traits, phylogeny-wide signal might not be expected while node-specific signals can still indicate phylogenetic structure with respect to the variable of interest. Conclusions Within the BCI forest dynamics plot, distributions of some plant taxa are associated with local-scale differences in soil variables when evaluated at individual nodes within the phylogenetic tree, but they are not detectable by phylogeny-wide signal. Trends

  14. Overdispersion of body size in Australian desert lizard communities at local scales only: no evidence for the Narcissus effect.

    PubMed

    Rabosky, Daniel L; Reid, Julian; Cowan, Mark A; Foulkes, Jeff

    2007-12-01

    Both local and regional processes may contribute to community diversity and structure at local scales. Although many studies have investigated patterns of local or regional community structure, few have addressed the extent to which local community structure influences patterns within regional species pools. Here we investigate the role of body size in community assembly at local and regional scales in Ctenotus lizards from arid Australia. Ctenotus has long been noted for its exceptional species diversity in the Australian arid-zone, and previous studies have attempted to elucidate the processes underlying species coexistence within communities of these lizards. However, no consensus has emerged on the role of interspecific competition in the assembly and maintenance of Ctenotus communities. We studied Ctenotus communities at several hundred sites in the arid interior of Australia to test the hypothesis that body sizes within local and regional Ctenotus assemblages should be overdispersed relative to null models of community assembly, and we explored the relationship between body size dispersion at local and regional scales. Results indicate a striking pattern of community-wide overdispersion of body size at local scales, as measured by the variance in size ratios among co-occurring species. However, we find no evidence for body size overdispersion within regional species pools, suggesting a lack of correspondence between processes influencing the distribution of species phenotypes at local and regional scales. We suggest that size ratio constancy in Ctenotus communities may have resulted from contemporary ecological interactions among species or ecological character displacement, and we discuss alternative explanations for the observed patterns.

  15. Combining local scaling and global methods to detect soil pore space

    NASA Astrophysics Data System (ADS)

    Martin-Sotoca, Juan Jose; Saa-Requejo, Antonio; Grau, Juan B.; Tarquis, Ana M.

    2017-04-01

    The characterization of the spatial distribution of soil pore structures is essential to obtain different parameters that will influence in several models related to water flow and/or microbial growth processes. The first step in pore structure characterization is obtaining soil images that best approximate reality. Over the last decade, major technological advances in X-ray computed tomography (CT) have allowed for the investigation and reconstruction of natural porous media architectures at very fine scales. The subsequent step is delimiting the pore structure (pore space) from the CT soil images applying a thresholding. Many times we could find CT-scan images that show low contrast at the solid-void interface that difficult this step. Different delimitation methods can result in different spatial distributions of pores influencing the parameters used in the models. Recently, new local segmentation method using local greyscale value (GV) concentration variabilities, based on fractal concepts, has been presented. This method creates singularity maps to measure the GV concentration at each point. The C-A method was combined with the singularity map approach (Singularity-CA method) to define local thresholds that can be applied to binarize CT images. Comparing this method with classical methods, such as Otsu and Maximum Entropy, we observed that more pores can be detected mainly due to its ability to amplify anomalous concentrations. However, it delineated many small pores that were incorrect. In this work, we present an improve version of Singularity-CA method that avoid this problem basically combining it with the global classical methods. References Martín-Sotoca, J.J., A. Saa-Requejo, J.B. Grau, A.M. Tarquis. New segmentation method based on fractal properties using singularity maps. Geoderma, 287, 40-53, 2017. Martín-Sotoca, J.J, A. Saa-Requejo, J.B. Grau, A.M. Tarquis. Local 3D segmentation of soil pore space based on fractal properties using singularity

  16. Local dark matter and dark energy as estimated on a scale of ~1 Mpc in a self-consistent way

    NASA Astrophysics Data System (ADS)

    Chernin, A. D.; Teerikorpi, P.; Valtonen, M. J.; Dolgachev, V. P.; Domozhilova, L. M.; Byrd, G. G.

    2009-12-01

    Context: Dark energy was first detected from large distances on gigaparsec scales. If it is vacuum energy (or Einstein's Λ), it should also exist in very local space. Here we discuss its measurement on megaparsec scales of the Local Group. Aims: We combine the modified Kahn-Woltjer method for the Milky Way-M 31 binary and the HST observations of the expansion flow around the Local Group in order to study in a self-consistent way and simultaneously the local density of dark energy and the dark matter mass contained within the Local Group. Methods: A theoretical model is used that accounts for the dynamical effects of dark energy on a scale of ~1 Mpc. Results: The local dark energy density is put into the range 0.8-3.7ρv (ρv is the globally measured density), and the Local Group mass lies within 3.1-5.8×1012 M⊙. The lower limit of the local dark energy density, about 4/5× the global value, is determined by the natural binding condition for the group binary and the maximal zero-gravity radius. The near coincidence of two values measured with independent methods on scales differing by ~1000 times is remarkable. The mass ~4×1012 M⊙ and the local dark energy density ~ρv are also consistent with the expansion flow close to the Local Group, within the standard cosmological model. Conclusions: One should take into account the dark energy in dynamical mass estimation methods for galaxy groups, including the virial theorem. Our analysis gives new strong evidence in favor of Einstein's idea of the universal antigravity described by the cosmological constant.

  17. Breed locally, disperse globally: Fine-scale genetic structure despite landscape-scale panmixia in a fire-specialist

    Treesearch

    Jennifer C. Pierson; Fred W. Allendorf; Pierre Drapeau; Michael K. Schwartz

    2013-01-01

    An exciting advance in the understanding of metapopulation dynamics has been the investigation of how populations respond to ephemeral patches that go 'extinct' during the lifetime of an individual. Previous research has shown that this scenario leads to genetic homogenization across large spatial scales. However, little is known about fine-scale genetic...

  18. Breed locally, disperse globally: fine-scale genetic structure despite landscape-scale panmixia in a fire-specialist.

    PubMed

    Pierson, Jennifer C; Allendorf, Fred W; Drapeau, Pierre; Schwartz, Michael K

    2013-01-01

    An exciting advance in the understanding of metapopulation dynamics has been the investigation of how populations respond to ephemeral patches that go 'extinct' during the lifetime of an individual. Previous research has shown that this scenario leads to genetic homogenization across large spatial scales. However, little is known about fine-scale genetic structuring or how this changes over time in ephemeral patches. We predicted that species that specialize on ephemeral habitats will delay dispersal to exploit natal habitat patches while resources are plentiful and thus display fine-scale structure. To investigate this idea, we evaluated the effect of frequent colonization of ephemeral habitats on the fine-scale genetic structure of a fire specialist, the black-backed woodpecker (Picoides arcticus) and found a pattern of fine-scale genetic structure. We then tested for differences in spatial structure between sexes and detected a pattern consistent with male-biased dispersal. We also detected a temporal increase in relatedness among individuals within newly burned forest patches. Our results indicate that specialist species that outlive their ephemeral patches can accrue significant fine-scale spatial structure that does not necessarily affect spatial structure at larger scales. This highlights the importance of both spatial and temporal scale considerations in both sampling and data interpretation of molecular genetic results.

  19. Breed Locally, Disperse Globally: Fine-Scale Genetic Structure Despite Landscape-Scale Panmixia in a Fire-Specialist

    PubMed Central

    Pierson, Jennifer C.; Allendorf, Fred W.; Drapeau, Pierre; Schwartz, Michael K.

    2013-01-01

    An exciting advance in the understanding of metapopulation dynamics has been the investigation of how populations respond to ephemeral patches that go ‘extinct’ during the lifetime of an individual. Previous research has shown that this scenario leads to genetic homogenization across large spatial scales. However, little is known about fine-scale genetic structuring or how this changes over time in ephemeral patches. We predicted that species that specialize on ephemeral habitats will delay dispersal to exploit natal habitat patches while resources are plentiful and thus display fine-scale structure. To investigate this idea, we evaluated the effect of frequent colonization of ephemeral habitats on the fine-scale genetic structure of a fire specialist, the black-backed woodpecker (Picoides arcticus) and found a pattern of fine-scale genetic structure. We then tested for differences in spatial structure between sexes and detected a pattern consistent with male-biased dispersal. We also detected a temporal increase in relatedness among individuals within newly burned forest patches. Our results indicate that specialist species that outlive their ephemeral patches can accrue significant fine-scale spatial structure that does not necessarily affect spatial structure at larger scales. This highlights the importance of both spatial and temporal scale considerations in both sampling and data interpretation of molecular genetic results. PMID:23825646

  20. Localized Scale Coupling and New Educational Paradigms in Multiscale Mathematics and Science

    SciTech Connect

    LEAL, L. GARY

    2013-06-30

    One of the most challenging multi-scale simulation problems in the area of multi-phase materials is to develop effective computational techniques for the prediction of coalescence and related phenomena involving rupture of a thin liquid film due to the onset of instability driven by van der Waals or other micro-scale attractive forces. Accurate modeling of this process is critical to prediction of the outcome of milling processes for immiscible polymer blends, one of the most important routes to new advanced polymeric materials. In typical situations, the blend evolves into an ?emulsion? of dispersed phase drops in a continuous matrix fluid. Coalescence is then a critical factor in determining the size distribution of the dispersed phase, but is extremely difficult to predict from first principles. The thin film separating two drops may only achieve rupture at dimensions of approximately 10 nm while the drop sizes are 0(10 ?m). It is essential to achieve very accurate solutions for the flow and for the interface shape at both the macroscale of the full drops, and within the thin film (where the destabilizing disjoining pressure due to van der Waals forces is proportional approximately to the inverse third power of the local film thickness, h-3). Furthermore, the fluids of interest are polymeric (through Newtonian) and the classical continuum description begins to fail as the film thins ? requiring incorporation of molecular effects, such as a hybrid code that incorporates a version of coarse grain molecular dynamics within the thin film coupled with a classical continuum description elsewhere in the flow domain. Finally, the presence of surface active additions, either surfactants (in the form of di-block copolymers) or surface-functionalized micro- or nano-scale particles, adds an additional level of complexity, requiring development of a distinct numerical method to predict the nonuniform concentration gradients of these additives that are responsible for

  1. Surface forces of colloidal particles from micrometer to nanometer

    NASA Astrophysics Data System (ADS)

    Cho, Jeong-Min

    2003-10-01

    Surface forces of colloidal particles play critical roles in the macroscopic behavior of particulate systems such as dispersion and coagulation, adhesion and coating, and the rheological behavior of ceramic slurries. As particle size is decreased from micrometer to nanometer range, surface forces are increasingly important. Polyelectrolytes are the chemical additives commonly used to efficiently control the stabilization of the colloidal system. Their conformations on the solid surfaces as well as the interactions between the adsorbed polyelectrolytes are important issues in colloidal processing. Most experimental and theoretical approaches to the surface forces are based on particle sizes in the micrometer range. However, nanoparticles at close proximity or high solids loading are expected to show different behavior than what can be estimated from conventional theories such as continuum or mean field theories. My study examined the effect of pH, ionic strength, and molecular weight of the polyelectrolytes on the surface forces of colloidal particles by the interplay with the adsorption, turbidity, and direct surface force measurement in terms of the conformation on the solid surfaces. The colloid probe technique based on atomic force microscopy (AFM) is well established for micron size particles; and could be extended for nanosize particles by using carbon nanotubes as proximal probes. Nanotubes with their high aspect ratio avoid the contribution from cone shapes that happens with AFM tips. The difference in particle size significantly influences surface forces for sterically dispersed colloidal systems.

  2. An efficient and near linear scaling pair natural orbital based local coupled cluster method

    NASA Astrophysics Data System (ADS)

    Riplinger, Christoph; Neese, Frank

    2013-01-01

    In previous publications, it was shown that an efficient local coupled cluster method with single- and double excitations can be based on the concept of pair natural orbitals (PNOs) [F. Neese, A. Hansen, and D. G. Liakos, J. Chem. Phys. 131, 064103 (2009), 10.1063/1.3173827]. The resulting local pair natural orbital-coupled-cluster single double (LPNO-CCSD) method has since been proven to be highly reliable and efficient. For large molecules, the number of amplitudes to be determined is reduced by a factor of 105-106 relative to a canonical CCSD calculation on the same system with the same basis set. In the original method, the PNOs were expanded in the set of canonical virtual orbitals and single excitations were not truncated. This led to a number of fifth order scaling steps that eventually rendered the method computationally expensive for large molecules (e.g., >100 atoms). In the present work, these limitations are overcome by a complete redesign of the LPNO-CCSD method. The new method is based on the combination of the concepts of PNOs and projected atomic orbitals (PAOs). Thus, each PNO is expanded in a set of PAOs that in turn belong to a given electron pair specific domain. In this way, it is possible to fully exploit locality while maintaining the extremely high compactness of the original LPNO-CCSD wavefunction. No terms are dropped from the CCSD equations and domains are chosen conservatively. The correlation energy loss due to the domains remains below <0.05%, which implies typically 15-20 but occasionally up to 30 atoms per domain on average. The new method has been given the acronym DLPNO-CCSD ("domain based LPNO-CCSD"). The method is nearly linear scaling with respect to system size. The original LPNO-CCSD method had three adjustable truncation thresholds that were chosen conservatively and do not need to be changed for actual applications. In the present treatment, no additional truncation parameters have been introduced. Any additional truncation

  3. A Modeling and Observational Framework for Diagnosing Local Land-Atmosphere Coupling on Diurnal Time Scales

    NASA Astrophysics Data System (ADS)

    Santanello, J. A.; Peters-Lidard, C. D.; Kumar, S.

    2009-12-01

    Land-atmosphere interactions play a critical role in determining the diurnal evolution of both planetary boundary layer (PBL) and land surface temperature and moisture states. The degree of coupling between the land surface and PBL in numerical weather prediction and climate models remains largely unexplored and undiagnosed due to the complex interactions and feedbacks present across a range of scales. Further, uncoupled systems or experiments (e.g., the Project for Intercomparison of Land Parameterization Schemes, PILPS) may lead to inaccurate water and energy cycle process understanding by neglecting feedback processes such as PBL-top entrainment. In this study, a framework for diagnosing local land-atmosphere coupling is presented using a coupled mesoscale model with a suite of PBL and land surface model (LSM) options along with observations during the summer of 2006 and 2007 in the Southern Great Plains. Specifically, the Weather Research and Forecasting (WRF) model has been coupled to the Land Information System (LIS), which provides a flexible and high-resolution representation and initialization of land surface physics and states. Mixing diagram diagnostics based on the evolution of 2m temperature and humidity are examined for the dry/wet extremes of this region, along with the sensitivity of PBL-LSM coupling to perturbations in soil moisture. As such, this methodology provides a potential pathway to study factors controlling local land-atmosphere coupling (LoCo) using the LIS-WRF system, which will serve as a testbed for future experiments to evaluate coupling diagnostics within the community.

  4. Modeling and Observational Framework for Diagnosing Local Land-Atmosphere Coupling on Diurnal Time Scales

    NASA Technical Reports Server (NTRS)

    Santanello, Joseph A., Jr.; Peters-Lidard, Christa D.; Kumar, Sujay V.; Alonge, Charles; Tao, Wei-Kuo

    2009-01-01

    Land-atmosphere interactions play a critical role in determining the diurnal evolution of both planetary boundary layer (PBL) and land surface temperature and moisture states. The degree of coupling between the land surface and PBL in numerical weather prediction and climate models remains largely unexplored and undiagnosed due to the complex interactions and feedbacks present across a range of scales. Further, uncoupled systems or experiments (e.g., the Project for Intercomparison of Land Parameterization Schemes, PILPS) may lead to inaccurate water and energy cycle process understanding by neglecting feedback processes such as PBL-top entrainment. In this study, a framework for diagnosing local land-atmosphere coupling is presented using a coupled mesoscale model with a suite of PBL and land surface model (LSM) options along with observations during field experiments in the U. S. Southern Great Plains. Specifically, the Weather Research and Forecasting (WRF) model has been coupled to the Land Information System (LIS), which provides a flexible and high-resolution representation and initialization of land surface physics and states. Within this framework, the coupling established by each pairing of the available PBL schemes in WRF with the LSMs in LIS is evaluated in terms of the diurnal temperature and humidity evolution in the mixed layer. The co-evolution of these variables and the convective PBL is sensitive to and, in fact, integrative of the dominant processes that govern the PBL budget, which are synthesized through the use of mixing diagrams. Results show how the sensitivity of land-atmosphere interactions to the specific choice of PBL scheme and LSM varies across surface moisture regimes and can be quantified and evaluated against observations. As such, this methodology provides a potential pathway to study factors controlling local land-atmosphere coupling (LoCo) using the LIS-WRF system, which will serve as a testbed for future experiments to evaluate

  5. Bedform migration in steep channels: from local avalanches to large scale changes

    NASA Astrophysics Data System (ADS)

    Mettra, F.; Heyman, J.; Ancey, C.

    2013-12-01

    Many studies have emphasized the strength of bedload transport fluctuations in steep streams, especially at low and intermediate transport conditions (relative to the threshold of incipient motion). The origins of these fluctuations, which appear on a wide range of time scales, are still not well understood. In this study, we present the data obtained from a 2D idealized laboratory experiment with the objective of simultaneously recording the channel bed evolution and bedload transport rate at a high temporal resolution. A 3-m long by 8-cm wide transparent flume filled with well-sorted natural gravel (d50=6.5 mm) was used. An efficient technique using accelerometers has been developed to record the arrival time of every particle at the outlet of the flume for long experimental durations (up to a few days). In addition, bed elevation was monitored using cameras filming from the side of the channel, allowing the observation of global aggradation/degradation as well as bedform migration. The experimental parameters were the water discharge, the flume inclination (from 2° to 5°) and the constant feeding rate of sediments. Large-scale bed evolution showed successive aggradation and rapid degradation periods. Indeed, the measured global channel slope, i.e. mean slope over the flume length, fluctuated continuously within a range sometimes wider than 1° (experimental parameters were constant over the entire run). The analysis of these fluctuations provides evidence that steep channels behave like metastable systems, similarly to grain piles. The metastable effects increased for steeper channels and lower transport conditions. In this measurement campaign, we mainly observed upstream-migrating antidunes. For each run, various antidune heights and celerities were measured. On average, the mean antidune migration rate increased with decreasing channel slope and increasing sediment feeding rate. Relatively rare tall and fast-moving antidunes appeared more frequently at high

  6. A test of Gaia Data Release 1 parallaxes: implications for the local distance scale

    NASA Astrophysics Data System (ADS)

    Casertano, Stefano; Riess, Adam G.; Bucciarelli, Beatrice; Lattanzi, Mario G.

    2017-03-01

    Aims: We present a comparison of Gaia Data Release 1 (DR1) parallaxes with photometric parallaxes for a sample of 212 Galactic Cepheids at a median distance of 2 kpc, and explore their implications on the distance scale and the local value of the Hubble constant H0. Methods: The Cepheid distances are estimated from a recent calibration of the near-infrared period-luminosity (P-L) relation. The comparison is carried out in parallax space, where the DR1 parallax errors, with a median value of half the median parallax, are expected to be well-behaved. Results: With the exception of one outlier, the DR1 parallaxes are in very good global agreement with the predictions from a well-established P-L relation, with a possible indication that the published errors may be conservatively overestimated by about 20%. This confirms that the quality of DR1 parallaxes for the Cepheids in our sample is well within their stated errors. We find that the parallaxes of 9 Cepheids brighter than G = 6 may be systematically underestimated. If interpreted as an independent calibration of the Cepheid luminosities and assumed to be otherwise free of systematic uncertainties, DR1 parallaxes are in very good agreement (within 0.3%) with the current estimate of the local Hubble constant, and in conflict at the level of 2.5σ (3.5σ if the errors are scaled) with the value inferred from Planck cosmic microwave background data used in conjunction with ΛCDM. We also test for a zeropoint error in Gaia parallaxes and find none to a precision of 20 μas. We caution however that with this early release, the complete systematic properties of the measurements may not be fully understood at the statistical level of the Cepheid sample mean, a level an order of magnitude below the individual uncertainties. The early results from DR1 demonstrate again the enormous impact that the full mission will likely have on fundamental questions in astrophysics and cosmology.

  7. Estimation of climate change impact on dead fuel moisture at local scale by using weather generators

    NASA Astrophysics Data System (ADS)

    Pellizzaro, Grazia; Bortolu, Sara; Dubrovsky, Martin; Arca, Bachisio; Ventura, Andrea; Duce, Pierpaolo

    2015-04-01

    The moisture content of dead fuel is an important variable in fire ignition and fire propagation. Moisture exchange in dead materials is controlled by physical processes, and is clearly dependent on atmospheric changes. According to projections of future climate in Southern Europe, changes in temperature, precipitation and extreme events are expected. More prolonged drought seasons could influence fuel moisture content and, consequently, the number of days characterized by high ignition danger in Mediterranean ecosystems. The low resolution of the climate data provided by the general circulation models (GCMs) represents a limitation for evaluating climate change impacts at local scale. For this reason, the climate research community has called to develop appropriate downscaling techniques. One of the downscaling approaches, which transform the raw outputs from the climate models (GCMs or RCMs) into data with more realistic structure, is based on linking a stochastic weather generator with the climate model outputs. Weather generators linked to climate change scenarios can therefore be used to create synthetic weather series (air temperature and relative humidity, wind speed and precipitation) representing present and future climates at local scale. The main aims of this work are to identify useful tools to determine potential impacts of expected climate change on dead fuel status in Mediterranean shrubland and, in particular, to estimate the effect of climate changes on the number of days characterized by critical values of dead fuel moisture. Measurements of dead fuel moisture content (FMC) in Mediterranean shrubland were performed by using humidity sensors in North Western Sardinia (Italy) for six years. Meteorological variables were also recorded. Data were used to determine the accuracy of the Canadian Fine Fuels Moisture Code (FFM code) in modelling moisture dynamics of dead fuel in Mediterranean vegetation. Critical threshold values of FFM code for

  8. Synthesis and review: Tackling the nitrogen management challenge: from global to local scales

    NASA Astrophysics Data System (ADS)

    Reis, Stefan; Bekunda, Mateete; Howard, Clare M.; Karanja, Nancy; Winiwarter, Wilfried; Yan, Xiaoyuan; Bleeker, Albert; Sutton, Mark A.

    2016-12-01

    One of the ‘grand challenges’ of this age is the anthropogenic impact exerted on the nitrogen cycle. Issues of concern range from an excess of fixed nitrogen resulting in environmental pressures for some regions, while for other regions insufficient fixed nitrogen affects food security and may lead to health risks. To address these issues, nitrogen needs to be managed in an integrated fashion, at a variety of scales (from global to local). Such management has to be based on a thorough understanding of the sources of reactive nitrogen released into the environment, its deposition and effects. This requires a comprehensive assessment of the key drivers of changes in the nitrogen cycle both spatially, at the field, regional and global scale and over time. In this focus issue, we address the challenges of managing reactive nitrogen in the context of food production and its impacts on human and ecosystem health. In addition, we discuss the scope for and design of management approaches in regions with too much and too little nitrogen. This focus issue includes several contributions from authors who participated at the N2013 conference in Kampala in November 2013, where delegates compiled and agreed upon the ‘Kampala Statement-for-Action on Reactive Nitrogen in Africa and Globally’. These contributions further underline scientifically the claims of the ‘Kampala Statement’, that simultaneously reducing pollution and increasing nitrogen available in the food system, by improved nitrogen management offers win-wins for environment, health and food security in both developing and developed economies. The specific messages conveyed in the Kampala Statement focus on improving nitrogen management (I), including the reduction of nitrogen losses from agriculture, industry, transport and energy sectors, as well as improving waste treatment and informing individuals and institutions (II). Highlighting the need for innovation and increased awareness among stakeholders (III

  9. Local and Regional Scale Genetic Variation in the Cape Dune Mole-Rat, Bathyergus suillus

    PubMed Central

    Visser, Jacobus H.; Bennett, Nigel C.; Jansen van Vuuren, Bettine

    2014-01-01

    The distribution of genetic variation is determined through the interaction of life history, morphology and habitat specificity of a species in conjunction with landscape structure. While numerous studies have investigated this interplay of factors in species inhabiting aquatic, riverine, terrestrial, arboreal and saxicolous systems, the fossorial system has remained largely unexplored. In this study we attempt to elucidate the impacts of a subterranean lifestyle coupled with a heterogeneous landscape on genetic partitioning by using a subterranean mammal species, the Cape dune mole-rat (Bathyergus suillus), as our model. Bathyergus suillus is one of a few mammal species endemic to the Cape Floristic Region (CFR) of the Western Cape of South Africa. Its distribution is fragmented by rivers and mountains; both geographic phenomena that may act as geographical barriers to gene-flow. Using two mitochondrial fragments (cytochrome b and control region) as well as nine microsatellite loci, we determined the phylogeographic structure and gene-flow patterns at two different spatial scales (local and regional). Furthermore, we investigated genetic differentiation between populations and applied Bayesian clustering and assignment approaches to our data. Nearly every population formed a genetically unique entity with significant genetic structure evident across geographic barriers such as rivers (Berg, Verlorenvlei, Breede and Gourits Rivers), mountains (Piketberg and Hottentots Holland Mountains) and with geographic distance at both spatial scales. Surprisingly, B. suillus was found to be paraphyletic with respect to its sister species, B. janetta–a result largely overlooked by previous studies on these taxa. A systematic revision of the genus Bathyergus is therefore necessary. This study provides a valuable insight into how the biology, life-history and habitat specificity of animals inhabiting a fossorial system may act in concert with the structure of the surrounding

  10. Distinguishing regional- and local-scale metasomatic systems at the Prairie Downs Zn-Pb deposit

    NASA Astrophysics Data System (ADS)

    White, Alistair J. R.; Pearce, Mark A.; Meadows, Holly R.

    2016-10-01

    Geochemical alteration in mafic rocks of the Fortescue Group around the Prairie Downs Zn-Pb-(Cu-Ag) deposit, Western Australia, is the result of two overprinting metasomatic systems. The first, a regional-scale event, well documented across the Fortescue Basin to the north, resulted in extensive depletion in alkalis, Mg, and heavier first transition series metals (Mn-Zn), and formation of mineral assemblages progressing towards pure epidote/pumpellyite-quartz end-members. The second, more localised event, was associated with Zn-Pb-(Cu-Ag) mineralisation and resulted in Ca-loss accompanied by enrichment in a broad transition metal and metalloid suite (Zn-Pb-Sn-Ag-K-Ba-Tl-Sb-Ge-U-Th-Cd-Hg-Se-REE) that is comparable to many sedimentary exhalative (SEDEX) systems, and possibly represents modification or remobilisation of an earlier ore system. The mineralisation-related alteration was superimposed on the earlier regional-scale metasomatism: previously unaltered basalts underwent Zn-bearing chlorite and biotite growth, with loss of amphibole and epidote; regionally metasomatised rocks now comprise assemblages dominated by quartz, muscovite and baileychlore (Zn chlorite). These altered basalts do not contain any sulphide minerals and all Zn is hosted within chlorite in a broad halo around the main sulphide zones, thereby providing a larger exploration target. Geochemical modelling with HCh indicates that the observed alteration assemblages can be generated through interaction of rocks with large volumes of a saline, Zn-K-bearing fluid (fluid/rock 1000). This study highlights the importance of understanding the regional geochemical background when investigating local metasomatic systems in order to correctly characterise them, determine their origin and position in a regional tectonic framework, and to correctly identify vectors towards mineralisation to aid future exploration.

  11. Local and Regional Scale Impacts of Arctic Shipping Emissions Off the Coast of Northern Norway

    NASA Astrophysics Data System (ADS)

    Marelle, L.; Thomas, J. L.; Law, K.; Raut, J. C.; Jalkanen, J. P.; Johansson, L.; Roiger, A.; Schlager, H.; Kim, J.; Reiter, A.; Weinzierl, B.; Rose, M.

    2014-12-01

    Decreased sea ice extent due to warming has already resulted in the use of new shipping routes through the Arctic. Marine traffic is a source of air pollutants, including NOx, SO2, and aerosols, and is predicted to be an increasingly significant source of Arctic pollution in the future. Currently there are large uncertainties in both global and Arctic shipping emissions, leading to uncertainties in diagnosing current and future impacts of marine traffic on Arctic air quality and climate. This study focuses on the local scale, examining chemical/aerosol transformations occurring in individual ship plumes. Measurements of ship pollution in the Arctic taken during the EU ACCESS aircraft campaign (Arctic Climate Change, Economy and Society) in July 2012 are used to quantify the amount of pollution emitted from different ship types. This is combined with regional model (WRF-Chem) simulations to evaluate the impacts of shipping in northern Norway in summer 2012. The model is run at high resolution (2x2 km) combined with STEAMv2 (Ship Traffic Emission Assessment Model version 2) emissions (1x1 km, 15 minute resolution) produced for shipping activity during the measurement period. WRF-Chem model results are compared with 3 ship plumes sampled during ACCESS. The model shows that both the location and total amount of pollution in individual ship plumes are correctly represented. Given this, the model is used to investigate the regional influence of ship pollution off the coast of Norway on a weekly time scale during July 2012, focusing on ozone photochemistry in ship plumes, the evolution of aerosols, and investigating the fate of black carbon emitted from ships. We compare regional modeling results obtained using 15 minute resolution STEAMv2 emissions with results using weekly averaged emissions, which are more representative of emissions typically used by global models to study the impacts of shipping on air quality and climate.

  12. Local and regional scale genetic variation in the Cape dune mole-rat, Bathyergus suillus.

    PubMed

    Visser, Jacobus H; Bennett, Nigel C; Jansen van Vuuren, Bettine

    2014-01-01

    The distribution of genetic variation is determined through the interaction of life history, morphology and habitat specificity of a species in conjunction with landscape structure. While numerous studies have investigated this interplay of factors in species inhabiting aquatic, riverine, terrestrial, arboreal and saxicolous systems, the fossorial system has remained largely unexplored. In this study we attempt to elucidate the impacts of a subterranean lifestyle coupled with a heterogeneous landscape on genetic partitioning by using a subterranean mammal species, the Cape dune mole-rat (Bathyergus suillus), as our model. Bathyergus suillus is one of a few mammal species endemic to the Cape Floristic Region (CFR) of the Western Cape of South Africa. Its distribution is fragmented by rivers and mountains; both geographic phenomena that may act as geographical barriers to gene-flow. Using two mitochondrial fragments (cytochrome b and control region) as well as nine microsatellite loci, we determined the phylogeographic structure and gene-flow patterns at two different spatial scales (local and regional). Furthermore, we investigated genetic differentiation between populations and applied Bayesian clustering and assignment approaches to our data. Nearly every population formed a genetically unique entity with significant genetic structure evident across geographic barriers such as rivers (Berg, Verlorenvlei, Breede and Gourits Rivers), mountains (Piketberg and Hottentots Holland Mountains) and with geographic distance at both spatial scales. Surprisingly, B. suillus was found to be paraphyletic with respect to its sister species, B. janetta-a result largely overlooked by previous studies on these taxa. A systematic revision of the genus Bathyergus is therefore necessary. This study provides a valuable insight into how the biology, life-history and habitat specificity of animals inhabiting a fossorial system may act in concert with the structure of the surrounding

  13. Microscope objective production: on the way from the micrometer scale to the nanometer scale

    NASA Astrophysics Data System (ADS)

    Sure, Thomas; Heil, Joachim; Wesner, Joachim

    2004-01-01

    Cemented doublets and triplets, which are the principle parts in high quality, high numerical aperture (NA) objectives, can not be used for objectives working at wavelengths of 248 nm and shorter, because the optical cement can not withstand the high photon energies. We will show that high NA deep UV objectives can be designed and built successfully with the help of air spaced doublets. Assuring Strehl ratios above 95% enforces very tight tolerances. For example the distance error of the lens vertex to its mount has to be <1 μm. This calls for a new manufacturing precision never realized before in series production. We show how a white light Mirau interferometer can be used to measure lens vertex positions with an accuracy of +/-200 nm. We also demonstrate how the fine-tuning process can be optimized by using a "simulated star test," where the point-spread function is calculated in real time with a FFT-algorithm from the optical path difference data, acquired by a Twyman-Green interferometer.

  14. Tidal marsh susceptibility to sea-level rise: importance of local-scale models

    USGS Publications Warehouse

    Thorne, Karen M.; Buffington, Kevin J.; Elliott-Fisk, Deborah L.; Takekawa, John Y.

    2015-01-01

    Increasing concern over sea-level rise impacts to coastal tidal marsh ecosystems has led to modeling efforts to anticipate outcomes for resource management decision making. Few studies on the Pacific coast of North America have modeled sea-level rise marsh susceptibility at a scale relevant to local wildlife populations and plant communities. Here, we use a novel approach in developing an empirical sea-level rise ecological response model that can be applied to key management questions. Calculated elevation change over 13 y for a 324-ha portion of San Pablo Bay National Wildlife Refuge, California, USA, was used to represent local accretion and subsidence processes. Next, we coupled detailed plant community and elevation surveys with measured rates of inundation frequency to model marsh state changes to 2100. By grouping plant communities into low, mid, and high marsh habitats, we were able to assess wildlife species vulnerability and to better understand outcomes for habitat resiliency. Starting study-site conditions were comprised of 78% (253-ha) high marsh, 7% (30-ha) mid marsh, and 4% (18-ha) low marsh habitats, dominated by pickleweed Sarcocornia pacifica and cordgrass Spartina spp. Only under the low sea-level rise scenario (44 cm by 2100) did our models show persistence of some marsh habitats to 2100, with the area dominated by low marsh habitats. Under mid (93 cm by 2100) and high sea-level rise scenarios (166 cm by 2100), most mid and high marsh habitat was lost by 2070, with only 15% (65 ha) remaining, and a complete loss of these habitats by 2080. Low marsh habitat increased temporarily under all three sea-level rise scenarios, with the peak (286 ha) in 2070, adding habitat for the endemic endangered California Ridgway’s rail Rallus obsoletus obsoletus. Under mid and high sea-level rise scenarios, an almost complete conversion to mudflat occurred, with most of the area below mean sea level. Our modeling assumed no marsh migration upslope due to human

  15. A hybrid downscaling procedure for estimating the vertical distribution of ambient temperature in local scale

    NASA Astrophysics Data System (ADS)

    Yiannikopoulou, I.; Philippopoulos, K.; Deligiorgi, D.

    2012-04-01

    The vertical thermal structure of the atmosphere is defined by a combination of dynamic and radiation transfer processes and plays an important role in describing the meteorological conditions at local scales. The scope of this work is to develop and quantify the predictive ability of a hybrid dynamic-statistical downscaling procedure to estimate the vertical profile of ambient temperature at finer spatial scales. The study focuses on the warm period of the year (June - August) and the method is applied to an urban coastal site (Hellinikon), located in eastern Mediterranean. The two-step methodology initially involves the dynamic downscaling of coarse resolution climate data via the RegCM4.0 regional climate model and subsequently the statistical downscaling of the modeled outputs by developing and training site-specific artificial neural networks (ANN). The 2.5ox2.5o gridded NCEP-DOE Reanalysis 2 dataset is used as initial and boundary conditions for the dynamic downscaling element of the methodology, which enhances the regional representivity of the dataset to 20km and provides modeled fields in 18 vertical levels. The regional climate modeling results are compared versus the upper-air Hellinikon radiosonde observations and the mean absolute error (MAE) is calculated between the four grid point values nearest to the station and the ambient temperature at the standard and significant pressure levels. The statistical downscaling element of the methodology consists of an ensemble of ANN models, one for each pressure level, which are trained separately and employ the regional scale RegCM4.0 output. The ANN models are theoretically capable of estimating any measurable input-output function to any desired degree of accuracy. In this study they are used as non-linear function approximators for identifying the relationship between a number of predictor variables and the ambient temperature at the various vertical levels. An insight of the statistically derived input

  16. Monitoring Coastal Processes at Local and Regional Geographic Scales with UAS

    NASA Astrophysics Data System (ADS)

    Starek, M. J.; Bridges, D.; Prouty, D.; Berryhill, J.; Williams, D.; Jeffress, G.

    2014-12-01

    Unmanned Aerial Systems (UAS) provide a powerful tool for coastal mapping due to attractive features such as low cost data acquisition, flexibility in data capture and resolution, rapid response, and autonomous flight. We investigate two different scales of UAS platforms for monitoring coastal processes along the central Texas Gulf coast. Firstly, the eBee is a small-scale UAS weighing ~0.7 kg designed for localized mapping. The imaging payload consists of a hand held RGB digital camera and NIR digital camera, both with 16.1 megapixel resolutions. The system can map up to 10 square kilometers on a single flight and is capable of acquiring imagery down to 1.5 cm ground sample distance. The eBee is configured with a GPS receiver, altitude sensor, gyroscope and a radio transmitter enabling autonomous flight. The system has a certificate of authorization (COA) from the FAA to fly over the Ward Island campus of Texas A&M University-Corpus Christi (TAMUCC). The campus has an engineered beach, called University Beach, located along Corpus Christi Bay. A set of groins and detached breakwaters were built in an effort to protect the beach from erosive wave action. The eBee is being applied to periodically survey the beach (Figure 1A). Through Structure from Motion (SfM) techniques, eBee-derived image sequences are post-processed to extract 3D topography and measure volumetric change. Additionally, when water clarity suffices, this approach enables the extraction of shallow-water bathymetry. Results on the utilization of the eBee to monitor beach morphodynamics will be presented including a comparison of derived estimates to RTK GPS and airborne lidar. Secondly, the RS-16 UAS has a 4 m wingspan and 11 kg sensor payload. The system is remotely piloted and has a flight endurance of 12 to 16 hours making it suitable for regional scale coastal mapping. The imaging payload consists of a multispectral sensor suite measuring in the visible, thermal IR, and ultraviolet ranges of the

  17. Local to Global Scale Time Series Analysis of US Dryland Degradation Using Landsat, AVHRR, and MODIS

    NASA Astrophysics Data System (ADS)

    Washington-Allen, R. A.; Ramsey, R. D.; West, N. E.; Kulawardhana, W.; Reeves, M. C.; Mitchell, J. E.; Van Niel, T. G.

    2011-12-01

    Drylands cover 41% of the terrestrial land surface and annually generate $1 trillion in ecosystem goods and services for 38% of the global population, yet estimates of the global extent of Dryland degradation is uncertain with a range of 10 - 80%. It is currently understood that Drylands exhibit topological complexity including self-organization of parameters of different levels-of-organization, e.g., ecosystem and landscape parameters such as soil and vegetation pattern and structure, that gradually or discontinuously shift to multiple basins of attraction in response to herbivory, fire, and climatic drivers at multiple spatial and temporal scales. Our research has shown that at large geographic scales, contemporaneous time series of 10 to 20 years for response and driving variables across two or more spatial scales is required to replicate and differentiate between the impact of climate and land use activities such as commercial grazing. For example, the Pacific Decadal Oscillation (PDO) is a major driver of Dryland net primary productivity (NPP), biodiversity, and ecological resilience with a 10-year return interval, thus 20 years of data are required to replicate its impact. Degradation is defined here as a change in physiognomic composition contrary to management goals, a persistent reduction in vegetation response, e.g., NPP, accelerated soil erosion, a decline in soil quality, and changes in landscape configuration and structure that lead to a loss of ecosystem function. Freely available Landsat, Advanced Very High Resolution Radiometer (AVHRR) and Moderate Resolution Imaging Spectroradimeter (MODIS) archives of satellite imagery exist that provide local to global spatial coverage and time series between 1972 to the present from which proxies of land degradation can be derived. This paper presents time series assessments between 1972 and 2011 of US Dryland degradation including early detection of dynamic regime shifts in the Mojave and landscape pattern and

  18. Galaxy cluster X-ray luminosity scaling relations from a representative local sample (REXCESS)

    NASA Astrophysics Data System (ADS)

    Pratt, G. W.; Croston, J. H.; Arnaud, M.; Böhringer, H.

    2009-05-01

    We examine the X-ray luminosity scaling relations of 31 nearby galaxy clusters from the Representative XMM-Newton Cluster Structure Survey (REXCESS). The objects are selected only in X-ray luminosity, optimally sampling the cluster luminosity function. Temperatures range from 2 to 9 keV, and there is no bias toward any particular morphological type. To reduce measurement scatter we extract pertinent values in an aperture corresponding to R500, estimated using the tight correlation between YX (the product of gas mass and temperature) and total mass. The data exhibit power law relations between bolometric X-ray luminosity and temperature, YX and total mass, all with slopes that are significantly steeper than self-similar expectations. We examine the possible causes for the steepening, finding that structural variations have little effect and that the primary driver appears to be a systematic variation of the gas content with mass. Scatter about the relations is dominated in all cases by the presence of cool cores. The natural logarithmic scatter about the raw X-ray luminosity-temperature relation is about 70 per cent, and about the X-ray luminosity-YX relation it is 40 per cent. Systems with more morphological substructure show similar scatter about scaling relations than clusters with less substructure, due to the preponderance of cool core systems in the regular cluster subsample. Cool core and morphologically disturbed systems occupy distinct regions in the residual space with respect to the best fitting mean relation, the former lying systematically at the high luminosity side, the latter lying systematically at the low luminosity side. Simple exclusion of the central regions serves to reduce the scatter about the scaling relations by more than a factor of two. The scatter reduces by a similar amount with the use of the central gas density as a third parameter. Using YX as a total mass proxy, we derive a Malmquist bias-corrected local luminosity-mass relation and

  19. Risk prediction of Critical Infrastructures against extreme natural hazards: local and regional scale analysis

    NASA Astrophysics Data System (ADS)

    Rosato, Vittorio; Hounjet, Micheline; Burzel, Andreas; Di Pietro, Antonio; Tofani, Alberto; Pollino, Maurizio; Giovinazzi, Sonia

    2016-04-01

    Natural hazard events can induce severe impacts on the built environment; they can hit wide and densely populated areas, where there is a large number of (inter)dependent technological systems whose damages could cause the failure or malfunctioning of further different services, spreading the impacts on wider geographical areas. The EU project CIPRNet (Critical Infrastructures Preparedness and Resilience Research Network) is realizing an unprecedented Decision Support System (DSS) which enables to operationally perform risk prediction on Critical Infrastructures (CI) by predicting the occurrence of natural events (from long term weather to short nowcast predictions, correlating intrinsic vulnerabilities of CI elements with the different events' manifestation strengths, and analysing the resulting Damage Scenario. The Damage Scenario is then transformed into an Impact Scenario, where punctual CI element damages are transformed into micro (local area) or meso (regional) scale Services Outages. At the smaller scale, the DSS simulates detailed city models (where CI dependencies are explicitly accounted for) that are of important input for crisis management organizations whereas, at the regional scale by using approximate System-of-Systems model describing systemic interactions, the focus is on raising awareness. The DSS has allowed to develop a novel simulation framework for predicting earthquakes shake maps originating from a given seismic event, considering the shock wave propagation in inhomogeneous media and the subsequent produced damages by estimating building vulnerabilities on the basis of a phenomenological model [1, 2]. Moreover, in presence of areas containing river basins, when abundant precipitations are expected, the DSS solves the hydrodynamic 1D/2D models of the river basins for predicting the flux runoff and the corresponding flood dynamics. This calculation allows the estimation of the Damage Scenario and triggers the evaluation of the Impact Scenario

  20. Two Examples of Integrated Aquifer Characterization at Local and Regional Scales

    NASA Astrophysics Data System (ADS)

    Lefebvre, R.; Gloaguen, E.; Rivard, C.; Parent, M.; Morin, R. H.; Pugin, A.; Pullan, S.; Crow, H.; Paradis, D.; Tremblay, L.; Blouin, M.; Laurencelle, M.

    2012-12-01

    An integrated aquifer characterization approach was developed with the aim of efficiently providing detailed data that could be used to develop conceptual hydrogeological models and quantitatively describe the spatial continuity and heterogeneity of unconsolidated sediments. The approach involves the integration of geological, hydraulic, geophysical and geochemical data. The emphasis of the approach is placed on the acquisition of detailed and continuous indirect data and selective soil sampling and direct measurements of hydraulic properties covering the full range of materials present in the system. Direct data are used to establish relations between indirect hydrogeophysical measurements and hydrofacies (HF), which are material types with distinct hydraulic conductivity (K). Surface geophysical surveys are used to provide 1D or 2D definitions of sediment structures and material types. Hydraulic tests are used to define HF and estimate their ranges of K. Groundwater (GW) geochemistry (major, minor, isotopes, GW age) is used to support the definition of conceptual models and to provide constraints on numerical models of GW flow and transport (mass and GW age). The approach relies on the geostatistical integration of multi-source data to define aquifer boundaries, on the recognition of HF and estimation of K from CPT/SMR data using fuzzy clustering and relevant vector machines for HF classification and K regression, on the geostatistical simulation of HF and K to provide the spatial distribution of hydraulic parameters in GW flow and transport models, and on the validation of these models using geochemical data. The integrated characterization approach was first developed and tested at local scale for the study of a shallow granular aquifer within a 12 km2 sub-watershed where a former unlined landfill is located. Results are being applied to the assessment of the efficiency of natural attenuation as a site management approach. The integrated characterization

  1. Using large area imaging to integrate biogeochemical data across spatial scales

    NASA Astrophysics Data System (ADS)

    Sapers, H. M.; Laquerre, A.; Phaneuf, M. W.; Osinski, G. R.

    2014-12-01

    Large Area Imaging (LAI) systems such as the Carl Zeiss "Atlas" module allow acquisition of SEM images on the scale of millimeters to centimeters with an image resolution ranging from nanometers to micrometers. This provides researchers with the powerful capability to investigate large areas of up to tens of millimeters in scale and expand anywhere within these areas to see details on the micrometer to nanometer scale while retaining full contextual information regarding the areas under investigation. Biogeochemical processes operate on multiple scales and evidence of these phenomena can be difficult to observe across scales. For example, microbial etching of glass occurs on a nanometer scale as organic acids locally lower pH and destabilize Si-O bonds. However, interpreting a pattern of glass etching as abiotic or biogenic depends on observations at the micrometer to centimeter scale to assess evidence for microbial populations and/or biological behavior, assess fluid flow, changes in elemental composition and mineralogy. LAI is particularly suited to the investigation of multi-scale, interdisciplinary biogeochemical datasets. Using LAI we have generated contiguous image data at resolutions as high as 100 nm (pixel size) for areas approaching 25 cm2, using backscattered and secondary electrons in both traditional high vacuum and variable pressure SEM modes. Image stitching produces seamless mosaics composed of multiple image tiles; mosaic acquisition times can be as little as a few hours of fully automated operation. Using this primary information, additional micrometer-scale data sets such as EDX spectroscopy, millimeter-scale datasets such as transmitted light photomicrographs, and nanometer-scale information such as synchrotron-based spectroscopy, can be registered and fused with the LAI SEM images. LAI and data fusion facilitates critical connections across spatial scales to test hypotheses that cross the threshold of traditional microscopy methods.

  2. Dissociable effects of local inhibitory and excitatory theta-burst stimulation on large-scale brain dynamics

    PubMed Central

    Sale, Martin V.; Lord, Anton; Zalesky, Andrew; Breakspear, Michael; Mattingley, Jason B.

    2015-01-01

    Normal brain function depends on a dynamic balance between local specialization and large-scale integration. It remains unclear, however, how local changes in functionally specialized areas can influence integrated activity across larger brain networks. By combining transcranial magnetic stimulation with resting-state functional magnetic resonance imaging, we tested for changes in large-scale integration following the application of excitatory or inhibitory stimulation on the human motor cortex. After local inhibitory stimulation, regions encompassing the sensorimotor module concurrently increased their internal integration and decreased their communication with other modules of the brain. There were no such changes in modular dynamics following excitatory stimulation of the same area of motor cortex nor were there changes in the configuration and interactions between core brain hubs after excitatory or inhibitory stimulation of the same area. These results suggest the existence of selective mechanisms that integrate local changes in neural activity, while preserving ongoing communication between brain hubs. PMID:25717162

  3. Band gaps and localization of surface water waves over large-scale sand waves with random fluctuations.

    PubMed

    Zhang, Yu; Li, Yan; Shao, Hao; Zhong, Yaozhao; Zhang, Sai; Zhao, Zongxi

    2012-06-01

    Band structure and wave localization are investigated for sea surface water waves over large-scale sand wave topography. Sand wave height, sand wave width, water depth, and water width between adjacent sand waves have significant impact on band gaps. Random fluctuations of sand wave height, sand wave width, and water depth induce water wave localization. However, random water width produces a perfect transmission tunnel of water waves at a certain frequency so that localization does not occur no matter how large a disorder level is applied. Together with theoretical results, the field experimental observations in the Taiwan Bank suggest band gap and wave localization as the physical mechanism of sea surface water wave propagating over natural large-scale sand waves.

  4. Local-scale projections of coral reef futures and implications of the Paris Agreement.

    PubMed

    van Hooidonk, Ruben; Maynard, Jeffrey; Tamelander, Jerker; Gove, Jamison; Ahmadia, Gabby; Raymundo, Laurie; Williams, Gareth; Heron, Scott F; Planes, Serge

    2016-12-21

    Increasingly frequent severe coral bleaching is among the greatest threats to coral reefs posed by climate change. Global climate models (GCMs) project great spatial variation in the timing of annual severe bleaching (ASB) conditions; a point at which reefs are certain to change and recovery will be limited. However, previous model-resolution projections (~1 × 1°) are too coarse to inform conservation planning. To meet the need for higher-resolution projections, we generated statistically downscaled projections (4-km resolution) for all coral reefs; these projections reveal high local-scale variation in ASB. Timing of ASB varies >10 years in 71 of the 87 countries and territories with >500 km(2) of reef area. Emissions scenario RCP4.5 represents lower emissions mid-century than will eventuate if pledges made following the 2015 Paris Climate Change Conference (COP21) become reality. These pledges do little to provide reefs with more time to adapt and acclimate prior to severe bleaching conditions occurring annually. RCP4.5 adds 11 years to the global average ASB timing when compared to RCP8.5; however, >75% of reefs still experience ASB before 2070 under RCP4.5. Coral reef futures clearly vary greatly among and within countries, indicating the projections warrant consideration in most reef areas during conservation and management planning.

  5. Local-scale fluxes of carbon dioxide in urban environments: methodological challenges and results from Chicago.

    PubMed

    Grimmond, C S B; King, T S; Cropley, F D; Nowak, D J; Souch, C

    2002-01-01

    Much attention is being directed to the measurement and modeling of surface-atmosphere exchanges of CO2 for different surface types. However, as yet, few measurements have been conducted in cities, even though these environments are widely acknowledged to be major sources of anthropogenic CO2. This paper highlights some of the challenges facing micrometeorologists attempting to use eddy covariance techniques to directly monitor CO2 fluxes in urban environments, focusing on the inherent variability within and between urban areas, and the importance of scale and the appropriate height of measurements. Results from a very short-term study of CO2 fluxes, undertaken in Chicago, Illinois in the summer of 1995, are presented. Mid-afternoon minimum CO2 concentrations and negative fluxes are attributed to the strength of biospheric photosynthesis and strong mixing of local anthropogenic sources in a deep mixed layer. Poor night-time atmospheric mixing, lower mixed layer depths, biospheric respiration, and continued missions from mobile and fixed anthropogenic sources, account for the night-time maxima in CO2 concentrations. The need for more, longer-term, continuous eddy covariance measurements is stressed.