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Sample records for local micrometer scale

  1. Ratiometric Organic Fibers for Localized and Reversible Ion Sensing with Micrometer-Scale Spatial Resolution.

    PubMed

    del Mercato, Loretta L; Moffa, Maria; Rinaldi, Rosaria; Pisignano, Dario

    2015-12-22

    A fundamental issue in biomedical and environmental sciences is the development of sensitive and robust sensors able to probe the analyte of interest, under physiological and pathological conditions or in environmental samples, and with very high spatial resolution. In this work, novel hybrid organic fibers that can effectively report the analyte concentration within the local microenvironment are reported. The nanostructured and flexible wires are prepared by embedding fluorescent pH sensors based on seminaphtho-rhodafluor-1-dextran conjugate. By adjusting capsule/polymer ratio and spinning conditions, the diameter of the fibers and the alignment of the reporting capsules are both tuned. The hybrid wires display excellent stability, high sensitivity, as well as reversible response, and their operation relies on effective diffusional kinetic coupling of the sensing regions and the embedding polymer matrix. These devices are believed to be a powerful new sensing platform for clinical diagnostics, bioassays and environmental monitoring. PMID:26539625

  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. 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.

  4. 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.

  5. Micrometer-scale porosity as a biosignature in carbonate crusts

    NASA Astrophysics Data System (ADS)

    Bosak, Tanja; Souza-Egipsy, Virginia; Corsetti, Frank A.; Newman, Dianne K.

    2004-09-01

    We formed calcite crusts in the presence and absence of the heterotrophic bacterium Desulfovibrio desulfuricans strain G20 to investigate microbial morphological signatures in fast-accreting carbonate precipitates. Submicrometer- to micrometer-sized pores (micropores) were present and ubiquitous in the G20 crusts but absent in abiotically precipitated crusts. Bacterial micropores resemble inclusions under transmitted light, but have distinct size, biological shapes and patterns (swirling or dendritic) and are distributed differently from common fluid inclusions. We observed similar porosity in both modern and ancient carbonate crusts of putative biotic origin. Our experiments support the microbial origin of micropores and help define specific criteria whereby to recognize these features as biosignatures in the rock record.

  6. Nanoscale Size-Selective Deposition of Nanowires by Micrometer Scale Hydrophilic Patterns

    PubMed Central

    He, Yong; Nagashima, Kazuki; Kanai, Masaki; Meng, Gang; Zhuge, Fuwei; Rahong, Sakon; Li, Xiaomin; Kawai, Tomoji; Yanagida, Takeshi

    2014-01-01

    Controlling the post-growth assembly of nanowires is an important challenge in the development of functional bottom-up devices. Although various methods have been developed for the controlled assembly of nanowires, it is still a challenging issue to align selectively heterogeneous nanowires at desired spatial positions on the substrate. Here we report a size selective deposition and sequential alignment of nanowires by utilizing micrometer scale hydrophilic/hydrophobic patterned substrate. Nanowires dispersed within oil were preferentially deposited only at a water/oil interface onto the hydrophilic patterns. The diameter size of deposited nanowires was strongly limited by the width of hydrophilic patterns, exhibiting the nanoscale size selectivity of nanowires deposited onto micrometer scale hydrophilic patterns. Such size selectivity was due to the nanoscale height variation of a water layer formed onto the micrometer scale hydrophilic patterns. We successfully demonstrated the sequential alignment of different sized nanowires on the same substrate by applying this size selective phenomenon. PMID:25087699

  7. 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.

  8. 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

  9. 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.

  10. 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

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

    PubMed

    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

    2015-07-01

    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

  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

    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

  14. 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.

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

    DOE PAGESBeta

    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; et al

    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

  16. The penetration of acoustic cavitation bubbles into micrometer-scale cavities.

    PubMed

    Vaidya, Haresh Anant; Ertunç, Özgür; Lichtenegger, Thomas; Delgado, Antonio; Skupin, Andreas

    2016-04-01

    The penetration of acoustically induced cavitation bubbles in micrometer-scale cavities is investigated experimentally by means of high-speed photography and acoustic measurements. Micrometer-scale cavities of different dimensions (width=40 μm, 80 μm, 10 mm and depth=50 μm) are designed to replicate the cross section of microvias in a PCB. The aim here is to present a method for enhancing mass transfer due to the penetration of bubbles in such narrow geometries under the action of ultrasound. The micrometer-scale cavities are placed in a test-cell filled with water and subjected to an ultrasound excitation at 75 kHz. A cavitation bubble cluster is generated at the mouth of the cavity which acts as a continuous source of bubbles that penetrate into the cavity. The radial oscillation characteristics and translation of these bubbles are investigated in detail here. It is observed that the bubbles arrange themselves into streamer-like structures inside the cavity. Parameters such as bubble population and size distribution and their correlation with the phase of the incident ultrasound radiation are investigated in detail here. This provides a valuable insight into the dynamics of bubbles in narrow confined spaces. Mass transfer investigations show that fresh liquid can be continuously introduced in the cavities under the action of ultrasound. Our findings may have important consequences in optimizing the filling processes for microvias with high aspect ratios. PMID:26763751

  17. Integrated GHz silicon photonic interconnect with micrometer-scale modulators and detectors

    NASA Astrophysics Data System (ADS)

    Chen, Long; Preston, Kyle; Manipatruni, Sasikanth; Lipson, Michal

    2009-08-01

    We report an optical link on silicon using micrometer-scale ring-resonator enhanced silicon modulators and waveguide-integrated germanium photodetectors. We show 3 Gbps operation of the link with 0.5 V modulator voltage swing and 1.0 V detector bias. The total energy consumption for such a link is estimated to be ~120 fJ/bit. Such compact and low power monolithic link is an essential step towards large-scale on-chip optical interconnects for future microprocessors.

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

    NASA Astrophysics Data System (ADS)

    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.

    2015-10-01

    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.

  19. 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.

  20. In vivo penetration mechanics and mechanical properties of mouse brain tissue at micrometer scales.

    PubMed

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

    2009-01-01

    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

  1. 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.

  2. Micrometer-scale cavities in fibrous and cloudy diamonds — A glance into diamond dissolution events

    NASA Astrophysics Data System (ADS)

    Klein-BenDavid, Ofra; Wirth, Richard; Navon, Oded

    2007-12-01

    Micrometer sized internal cavities in diamonds preserve evidence of diamond dissolution events. Combining the methods of focused ion beam (FIB) sample preparation and transmission electron microscopy (TEM) enables these features to be studied in detail. Micrometer-scale cavities are found in the inner parts of fibrous and cloudy kimberlitic diamonds. Their filling consists of amorphous matrix, secondary nano-crystals, volatiles and in some cases larger resorbed crystals. Trapped minerals include corundum, Kappa-alumina, quartz, olivine, moissanite-6H and Ca-Mg carbonates. This is the first observation of Kappa-alumina in nature. Secondary nano-minerals are observed within the amorphous matrix and include carbonates, Al-oxide, fluorite, ilmenite and secondary diamond crystals. The amorphous matrix is spongy and its composition is dominated by amorphous carbon, nitrogen, chlorine and also contains water. When no crystalline phases are observed, the matrix is also enriched in alumina, silica and in some cases calcium. We propose that micrometer scale cavities in diamonds form during dissolution events induced by the introduction of oxidizing hydrous fluids into the diamond growth area. Hydrous fluids are the main dissolving agents for most kimberlitic diamonds [Fedortchouk, Y., Canil, D., Semenets, E., 2007. Mechanisms of diamond oxidation and their bearing on the fluid composition in kimberlite magmas. Am. Mineral. 92, 1200-1212]. At diamond forming conditions silica and alumina are enriched in hydrous fluids that are in equilibrium with eclogites [Kessel, R., Ulmer, P., Pettke, T., Schmidt, M.W., Thompson, A.B., 2005. The water-basalt system at 4 to 6 GPa: Phase relations and second critical endpoint in a K-free eclogite at 700 to 1400 °C. Earth Planet. Sci. Lett. 237, 873-892]; this is consistent with the increased solubility of alumina with increased pressure and temperature in the Na-Cl bearing fluids [Manning, C.E., 2006. Mobilizing aluminum in crustal and

  3. 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.

  4. 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. PMID:26340180

  5. 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.

  6. 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.

  7. Nanometer-scale features on micrometer-scale surface texturing: a bone histological, gene expression, and nanomechanical study.

    PubMed

    Coelho, Paulo G; Takayama, Tadahiro; Yoo, Daniel; Jimbo, Ryo; Karunagaran, Sanjay; Tovar, Nick; Janal, Malvin N; Yamano, Seiichi

    2014-08-01

    Micro- and nanoscale surface modifications have been the focus of multiple studies in the pursuit of accelerating bone apposition or osseointegration at the implant surface. Here, we evaluated histological and nanomechanical properties, and gene expression, for a microblasted surface presenting nanometer-scale texture within a micrometer-scale texture (MB) (Ossean Surface, Intra-Lock International, Boca Raton, FL) versus a dual-acid etched surface presenting texture at the micrometer-scale only (AA), in a rodent femur model for 1, 2, 4, and 8weeks in vivo. Following animal sacrifice, samples were evaluated in terms of histomorphometry, biomechanical properties through nanoindentation, and gene expression by real-time quantitative reverse transcription polymerase chain reaction analysis. Although the histomorphometric, and gene expression analysis results were not significantly different between MB and AA at 4 and 8 weeks, significant differences were seen at 1 and 2 weeks. The expression of the genes encoding collagen type I (COL-1), and osteopontin (OPN) was significantly higher for MB than for AA at 1 week, indicating up-regulated osteoprogenitor and osteoblast differentiation. At 2 weeks, significantly up-regulated expression of the genes for COL-1, runt-related transcription factor 2 (RUNX-2), osterix, and osteocalcin (OCN) indicated progressive mineralization in newly formed bone. The nanomechanical properties tested by the nanoindentation presented significantly higher-rank hardness and elastic modulus for the MB compared to AA at all time points tested. In conclusion, the nanotopographical featured surfaces presented an overall higher host-to-implant response compared to the microtextured only surfaces. The statistical differences observed in some of the osteogenic gene expression between the two groups may shed some insight into the role of surface texture and its extent in the observed bone healing mechanisms. PMID:24813260

  8. Towards the hand-held mass spectrometer: design considerations, simulation, and fabrication of micrometer-scaled cylindrical ion traps

    NASA Astrophysics Data System (ADS)

    Blain, Matthew G.; Riter, Leah S.; Cruz, Dolores; Austin, Daniel E.; Wu, Guangxiang; Plass, Wolfgang R.; Cooks, R. Graham

    2004-08-01

    Breakthrough improvements in simplicity and reductions in the size of mass spectrometers are needed for high-consequence fieldable applications, including error-free detection of chemical/biological warfare agents, medical diagnoses, and explosives and contraband discovery. These improvements are most likely to be realized with the reconceptualization of the mass spectrometer, rather than by incremental steps towards miniaturization. Microfabricated arrays of mass analyzers represent such a conceptual advance. A massively parallel array of micrometer-scaled mass analyzers on a chip has the potential to set the performance standard for hand-held sensors due to the inherit selectivity, sensitivity, and universal applicability of mass spectrometry as an analytical method. While the effort to develop a complete micro-MS system must include innovations in ultra-small-scale sample introduction, ion sources, mass analyzers, detectors, and vacuum and power subsystems, the first step towards radical miniaturization lies in the design, fabrication, and characterization of the mass analyzer itself. In this paper we discuss design considerations and results from simulations of ion trapping behavior for a micrometer scale cylindrical ion trap (CIT) mass analyzer (internal radius r0 = 1 [mu]m). We also present a description of the design and microfabrication of a 0.25 cm2 array of 106 one-micrometer CITs, including integrated ion detectors, constructed in tungsten on a silicon substrate.

  9. Long-lived BLOCH oscillations with bosonic sr atoms and application to gravity measurement at the micrometer scale.

    PubMed

    Ferrari, G; Poli, N; Sorrentino, F; Tino, G M

    2006-08-11

    We report on the observation of Bloch oscillations on the unprecedented time scale of several seconds. The experiment is carried out with ultracold bosonic 88Sr atoms loaded into a vertical optical standing wave. The negligible atom-atom elastic cross section and zero angular momentum in the ground state makes 88Sr an almost ideal Bose gas, insensitive to typical mechanisms of decoherence due to thermalization and external stray fields. The small size of the system enables precision measurements of forces at micrometer scale. This is a challenge in physics for studies of surfaces, Casimir effects, and searches for deviations from Newtonian gravity predicted by theories beyond the standard model. PMID:17026151

  10. A Suite of Hybrid Simulation Schemes for Nano-to-Micrometer Scale Processes at Solid-Fluid Interfaces

    NASA Astrophysics Data System (ADS)

    Ogata, S.; Kobayashi, R.; Gotoh, T.

    Computer simulation of a variety of solid-fluid interfaces in nano-to-micrometer scales has attracted much attention in recent years. We have been developing the hybrid simulation schemes to apply them to the interfaces at realistic settings without losing physical accuracies, by concurrently coupling the electronic density-functional theory (DFT), the molecular dynamics (MD), the recursive coarse-grained particle (RCGP) method, and the lattice Boltzmann equation (LBE) method. In the hybrid DFT-MD simulation scheme, multiple DFT regions each of which is composed of a relatively small number of atoms are embedded in a system of classical MD atoms. For robust coupling of the DFT and MD regions with reasonable mechanical accuracies the buffered-cluster method is adopted, which requires no link-atoms and is applicable to a wide range of materials and settings. The sizes and number of the DFT regions change adaptively to trace the chemical reactions during the simulation run. T he hybrid DFT-MD simulation scheme is successfully applied to various interesting processes including the atomic-scale friction between nano-scale objects. Useful MD simulation requires realistic, dynamic boundary conditions to the atoms. We develop the RCGP method to coarse-grain the atomic system in the solid phase, in which each particle represents a group of the atoms and the inter-particle interaction is constructed by renormalizing the inter-atomic interaction in a recursive manner under the assumption of the local statistical equilibrium. The RCGP method has attractive features such as its natural incorporation of the atomic phonons in the thermal equilibrium and its potential suitableness to connection to the atomistic system. In the hybrid RCGP-MD simulation scheme, the overall shape of the total system calculated with the RCGP method gives the dynamics boundary conditions to the MD regions. A nano-thrusting simulation of a structured Al system that demonstrates rea sonable coupling of

  11. 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.

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

    PubMed

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

    2016-06-28

    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

  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. New versatile x-ray analyzer using capillary focusing in the micrometer scale

    NASA Astrophysics Data System (ADS)

    Burggraf, Charles; Fougeres, Paul; Burggraf, Chris; Hage-Ali, Makram; Koebel, Jean M.; Krauth, A.; Regal, R.; Baltzinger, J. L.; Siffert, Paul

    1999-10-01

    In this paper, we will give first the description of a versatile material analyzer for x-ray crystallographic and compositional analyses. We will describe how we calculate and elaborate glass capillaries; we will describe some important parameters of the total reflection of x-rays: focusing, transparency, gain and divergence. Our first results concern a compositional study of CdZnTe crystals with a n x-ray beam diameter of 10 micrometers and we will show the variation of Zn on the surface of such a crystal. Another possibility of this device is x-ray microtopography of a film or of a wafer. We show, on one hand the way to find in classical centers by Laue micropatterns on the other hand we could establish a Bragg reflection pattern like those obtained in classical x-ray surface topography. In some heat treatments we can see so-called texture effects. We have also on our device the possibility to see microtexture effects in a way which can be compared to the Seeman-Bohlin experiment. The compositional experiments were also tested by SEM in order to see how these two devices complete each other. We can notice in some studies the advantages of x-rays because photons are less destructive than electrons.

  15. Micrometer-Scale Ballistic Transport of Electron Pairs in LaAlO_{3}/SrTiO_{3} Nanowires.

    PubMed

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

    2016-08-26

    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 LaAlO_{3}/SrTiO_{3}-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 LaAlO_{3}/SrTiO_{3} 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 B_{p}, 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. PMID:27610871

  16. Generation and detection of broadband multi-channel orbital angular momentum by micrometer-scale meta-reflectarray.

    PubMed

    Liu, Jinpeng; Min, Changjun; Lei, Ting; Du, Luping; Yuan, Yangsheng; Wei, Shibiao; Wang, Yiping; Yuan, X-C

    2016-01-11

    We theoretically demonstrate the generation and detection of broadband multi-channel Orbital Angular Momentum(OAM) by a micrometer-scale meta-reflectarray. The meta-reflectarray composed of patterned silicon bars on a silver ground plane can be designed to realize phase modulation and work as chip-level OAM devices. Compared to traditional methods of OAM generation and detection, our approach shows superiorities of very compact structure size, broadband working wavelength (1250-1750 nm), high diffraction efficiency (~70%), simultaneously handling multiplex OAMs, and tunable reflection angle (0-45°). These fascinating advantages provides great potential applications in photonic integrated devices and systems for high-capacity and multi-channel OAM communication. PMID:26832252

  17. 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 .

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

    PubMed

    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

  19. 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

  20. 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.

  1. Fabrication of photonic quasicrystalline structures in the sub-micrometer scale

    NASA Astrophysics Data System (ADS)

    Wang, Shuai; Sun, XiaoHong; Li, WenYang; Liu, Wei; Jiang, Lei; Han, Juan

    2016-05-01

    Compared to periodic crystals, photonic quasicrystals (PQC) have higher point group symmetry and are more favorable in achieving complete band-gaps. In this report, a top-cut prism interferometer is designed to fabricate ten-fold photonic quasicrystalline structures in the sub-micro scale. Based on the difference of production conditions, a variety of quasicrystals have been obtained in the SU8 photoresist films. Scanning Probe Microscopy and laser diffraction are used to characterize the produced structures. The corresponding theoretical analysis is also provided to compare with the experimental results. This will provide guidance for the large-area and fast production of ten-fold quasicrystalline structures with high quality.

  2. Surface-immobilized hydrogel patterns on length scales from micrometer to nanometer

    NASA Astrophysics Data System (ADS)

    Zeira, Assaf

    The present work concentrates on the study of pattern generation and transfer processes of monolayer covered surfaces, deriving from the basic working concept of Constructive Lithography. As an advancement of constructive lithography, we developed a direct, one-step printing (contact electrochemical printing, CEP) and replication (contact electrochemical replication, CER) of hydrophilic organic monolayer patterns surrounded by a hydrophobic monolayer background. In addition, we present a process of transfer of metal between two contacting solid surfaces to predefined monolayer template pattern sites (contact electrochemical transfer, CET). This thesis shows that CEP, CER, and CET may be implemented under a variety of different experimental conditions, regardless of whether the initial "master" pattern was created by a parallel (fast) or serial (slow) patterning process. CEP and CER also posses the unique attractive property that each replica may equally function as master stamp in the fabrication of additional replicas. Moreover, due to a mechanism of selfcorrection patterned surfaces produced these process are often free of defects that the initial "master" stamp may had. We finally show that the electrochemical patterning of OTS monolayers on silicon can be further extended to flexible polymeric substrate materials as well as to a variety of chemical manipulations, allowing the fabrication of tridimensional (3D) composite structures made on the basis of readily available OTS compound. The results obtained suggest that such contact electrochemical processes could be used to rapidly generate multiple copies of surface patterns spanning variable length scales, this basic approach being applicable to rigid as well as flexible substrate materials.

  3. 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

  4. 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.

  5. 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

  6. 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

  7. High areal capacity, micrometer-scale amorphous Si film anode based on nanostructured Cu foil for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Si, Wenping; Sun, Xiaolei; Liu, Xianghong; Xi, Lixia; Jia, Yandong; Yan, Chenglin; Schmidt, Oliver G.

    2014-12-01

    We report a feasible design to fabricate micrometer-scale Si films deposited on nanostructured Cu foil as high areal capacity anodes for Li-ion batteries with excellent cycling performance. Nanostructured copper oxides are prepared by anodic oxidation of Cu foil in alkaline solution. The resultant copper oxide nanofibers function as matrix for thick Si films (1-2 μm) loading. Metallic Cu nanofibers are obtained by in-situ electrochemical reduction at low potentials, which work as electrical highways for fast electron transport and a reliable mechanical matrix to accommodate volume changes during lithium-silicon alloy/dealloy processes. The engineered thick Si film anode exhibit both high areal capacity (0.48 mAh cm-2 for 1 μm Si film and 0.6 mAh cm-2 for 2 μm Si film after 200 cycles at 0.225 mA cm-2) and excellent rate capability (0.52 mAh cm-2 at 1.05 mA cm-2 for 2 μm Si film). The 2 μm silicon film electrode is able to recover to the initial value of 1 mAh cm-2 when the current rate is set back to 0.15 mA cm-2 even after cycling at high current rates. The reported concept can be a general method for high-loading-film electrodes, which is industrial scalable and compatible with current battery manufacturing processes.

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

    NASA Astrophysics Data System (ADS)

    Manceau, Alain; Marcus, Matthew A.; Tamura, Nobumichi; Proux, Olivier; Geoffroy, Nicolas; Lanson, Bruno

    2004-06-01

    Combined use of synchrotron-based X-ray fluorescence (SXRF), diffraction (XRD), and absorption (EXAFS) with an X-ray spot size as small as five micrometers allows us to examine noninvasively heterogeneous soils and sediments. Specifically, the speciation of trace metals at low bulk concentrations and the nature of host minerals can be probed with a level of detail unattainable by other techniques. The potential of this novel analytical approach is demonstrated by determining the Zn species in the solid phases of a pristine horizon of a clayey acidic soil (pH 4.5-5.0) having a Zn concentration of 128 mg/kg. The sample presents a differentiated fabric under the optical microscope with traces of localized manganiferous, ferriferous and argillaceous accumulations. The high chemical and textural heterogeneity of this soil offers an opportunity to identify new Zn species and to confirm the existence of others proposed from published least-squares fits of bulk averaged EXAFS spectra. As many as five to six Zn species were observed: sphalerite (ZnS), zincochromite (ZnCr 2O 4), Zn-containing phyllosilicate and lithiophorite, and Zn-sorbed ferrihydrite or Zn-phosphate, the results being less definitive for these two last species. Bulk EXAFS spectroscopy applied to the powdered soil indicated that Zn is predominantly associated with phyllosilicates, all other species amounting to < ˜10 to 20% of total zinc. The role of lithiophorite in the sequestration of zinc in soils had been inferred previously, but the firm identification of lithiophorite in this study serves as an excellent demonstration of the capabilities of combined micro-SXRF/XRD/EXAFS measurements. The micro-EXAFS spectrum collected in an area containing only phyllosilicates could not be simulated assuming a single Zn structural environment. Two distinct octahedrally-coordinated crystallographic sites (i.e., two EXAFS components) were considered: one site located within the phyllosilicate structure (isomorphic

  9. Mapping fast flows over micrometer-length scales using flow-tagging velocimetry and single-molecule detection.

    PubMed

    Shelby, J Patrick; Chiu, Daniel T

    2003-03-15

    This paper describes a technique of characterizing microfluidic flow profiles from slow laminar flow to fast near-turbulent flow. Using a photo-activated fluorophore, nanosecond-duration photolysis pulses from a Nitrogen laser, and high-sensitivity single-molecule detection with Ar+ laser excitation, we report the measurement of flow speeds up to 47 m/s in a 33-microm-wide straight channel and the mapping of flow profiles in a 55-microm-wide microchamber. Sensitive single-molecule detection is necessary both because of the short time delay (submicrosecond) between laser photolysis and fluorescence detection and the fast transit times (as low as 10 ns) of the fluorescent molecules across the diffraction-limited beam waist of the Ar+ laser focus. This technique permits the high-resolution three-dimensional mapping and analysis of a wide range of velocity profiles in confined spaces that measure a few micrometers in dimension. PMID:12659200

  10. One-step large-scale synthesis of micrometer-sized silver nanosheets by a template-free electrochemical method

    PubMed Central

    2013-01-01

    We have synthesized micrometer-sized Ag nanosheets via a facile, one-step, template-free electrochemical deposition in an ultra-dilute silver nitrate aqueous electrolyte. The nanosheet growth was revealed to occur in three stages: (1) formation of polygonal Ag nuclei on a substrate, (2) growth of {112}-faceted nanowire from the nuclei, and (3) anisotropic growth of (111)-planar nanosheets, approximately 20 to 50 nm in thickness and 10 μm in width, in the <112>−direction. The vertical growth of the facet nanowire was induced by the strong interface anisotropy between the deposit and electrolyte due to the ultra-dilute concentration of electrolyte and high reduction potential. The thickness of Ag nanosheets was controllable by the adjustment of the reduction/oxidation potential and frequency of the reverse-pulse potentiodynamic mode. PMID:23692676

  11. 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.

  12. Bridging the Gap between the Nanometer-Scale Bottom-Up and Micrometer-Scale Top-Down Approaches for Site-Defined InP/InAs Nanowires.

    PubMed

    Zhang, Guoqiang; Rainville, Christophe; Salmon, Adrian; Takiguchi, Masato; Tateno, Kouta; Gotoh, Hideki

    2015-11-24

    This work presents a method that bridges the gap between the nanometer-scale bottom-up and micrometer-scale top-down approaches for site-defined nanostructures, which has long been a significant challenge for applications that require low-cost and high-throughput manufacturing processes. We realized the bridging by controlling the seed indium nanoparticle position through a self-assembly process. Site-defined InP nanowires were then grown from the indium-nanoparticle array in the vapor-liquid-solid mode through a "seed and grow" process. The nanometer-scale indium particles do not always occupy the same locations within the micrometer-scale open window of an InP exposed substrate due to the scale difference. We developed a technique for aligning the nanometer-scale indium particles on the same side of the micrometer-scale window by structuring the surface of a misoriented InP (111)B substrate. Finally, we demonstrated that the developed method can be used to grow a uniform InP/InAs axial-heterostructure nanowire array. The ability to form a heterostructure nanowire array with this method makes it possible to tune the emission wavelength over a wide range by employing the quantum confinement effect and thus expand the application of this technology to optoelectronic devices. Successfully pairing a controllable bottom-up growth technique with a top-down substrate preparation technique greatly improves the potential for the mass-production and widespread adoption of this technology. PMID:26348087

  13. 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.

  14. 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. PMID:25974500

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    Experimentally observed electrical breakdown voltages (UB) 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 UB 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 UB (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 UB curve in the high-density fluids. Calculations based on the novel model showed good agreements with the experimentally measured UB even near the critical point and it also suggested that the critical anomaly of the UB 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.

  16. Scale-locality of magnetohydrodynamic turbulence

    SciTech Connect

    Aluie, Hussein; Eyink, Gregory L

    2009-01-01

    We investigate the scale-locality of cascades of conserved invariants at high kinetic and magnetic Reynolds numbers in the 'inertial-inductive range' of magnetohydrodynamic (MHD) turbulence, where velocity and magnetic field increments exhibit suitable power-law scaling. We prove that fluxes of total energy and cross-helicity - or, equivalently, fluxes of Elsaesser energies - are dominated by the contributions of local triads. Corresponding spectral transfers are also scale-local when defined using octave wavenumber bands. Flux and transfer of magnetic helicity may be dominated by nonlocal triads. The magnetic stretching term also may be dominated by non-local triads but we prove that it can convert energy only between velocity and magnetic modes at comparable scales. We explain the disagreement with numerical studies that have claimed conversion non locally between disparate scales. We present supporting data from a 1024{sup 3} simulation of forced MHD turbulence.

  17. Micrometer-Scale Ordering of Silicon-Containing Block Copolymer Thin Films via High-Temperature Thermal Treatments.

    PubMed

    Giammaria, Tommaso Jacopo; Ferrarese Lupi, Federico; Seguini, Gabriele; Perego, Michele; Vita, Francesco; Francescangeli, Oriano; Wenning, Brandon; Ober, Christopher K; Sparnacci, Katia; Antonioli, Diego; Gianotti, Valentina; Laus, Michele

    2016-04-20

    Block copolymer (BCP) self-assembly is expected to complement conventional optical lithography for the fabrication of next-generation microelectronic devices. In this regard, silicon-containing BCPs with a high Flory-Huggins interaction parameter (χ) are extremely appealing because they form high-resolution nanostructures with characteristic dimensions below 10 nm. However, due to their slow self-assembly kinetics and low thermal stability, these silicon-containing high-χ BCPs are usually processed by solvent vapor annealing or in solvent-rich ambient at a low annealing temperature, significantly increasing the complexity of the facilities and of the procedures. In this work, the self-assembly of cylinder-forming polystyrene-block-poly(dimethylsiloxane-random-vinylmethylsiloxane) (PS-b-P(DMS-r-VMS)) BCP on flat substrates is promoted by means of a simple thermal treatment at high temperatures. Homogeneous PS-b-P(DMS-r-VMS) thin films covering the entire sample surface are obtained without any evidence of dewetting phenomena. The BCP arranges in a single layer of cylindrical P(DMS-r-VMS) nanostructures parallel-oriented with respect to the substrate. By properly adjusting the surface functionalization, the heating rate, the annealing temperature, and the processing time, one can obtain correlation length values larger than 1 μm in a time scale fully compatible with the stringent requirements of the microelectronic industry. PMID:27020526

  18. 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.…

  19. 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.

  20. Noncontact fiber optic micrometer

    NASA Astrophysics Data System (ADS)

    Betancourt Ibarra, F.; Guajardo-Gonzalez, Candelario; Castillo-Guzman, Arturo; Guzman-Ramos, Valentin; Selvas, Romeo

    2010-10-01

    A sensor instrument able to measuring the thickness of different semitransparent objects with a resolution of one micron is described. This is based on a fiber optic reflectometer and a laser autofocus system and permit to measuring the thickness of thin surfaces such as semiconductor films, plastic materials and semitransparent objects. The response time for the measuring was roughly 2 sec and the thickness results were compared with a digital mechanical micrometer and both are in good agreement.

  1. Automatic readout micrometer

    SciTech Connect

    Lauritzen, T.

    1982-03-23

    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.

  2. 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.

  3. 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.

  4. 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.

    2016-06-01

    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.

  5. Anatomy of A Local Scale Drought

    NASA Astrophysics Data System (ADS)

    Mishra, A. K.; Ines, A. V. M.; Das, N. N.; Khedun, P.

    2014-12-01

    Drought is of global concern for society but it originates as a local problem. It has a significant impact on water quantity and quality and influences food, water, and energy security. The consequences of drought vary in space and time, from the local scale (e.g. county level) to regional scale (e.g. state or country level) to global scale. This study addresses a local-scale agricultural drought anatomy in Story County in Iowa, USA. This complex problem was evaluated using assimilated AMSR-E soil moisture and MODIS-LAI data into a crop model to generate surface and sub-surface drought indices to explore the anatomy of an agricultural drought. It was found that both surface and subsurface droughts have an impact on crop yields, albeit with different magnitudes, however, the total water available in the soil profile seemed to have a greater impact on the yield. We envisaged that the results of this study will enhance our understanding of agricultural droughts in different parts of the world.

  6. 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

  7. 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

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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

  13. 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

  14. Validating Large Scale Networks Using Temporary Local Scale Networks

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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. 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.

  16. 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.

  17. 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. PMID:21750707

  18. 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. PMID:27300764

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Multi-scale edge detection with local noise estimate

    NASA Astrophysics Data System (ADS)

    Jiang, Bo; Rahman, Zia-ur

    2010-08-01

    The (unrealistic) assumption that noise can be modeled as independent, additive and uniform can lead to problems when edge detection methods are applied to real or natural images. The main reason for this is because filter scale and threshold for the gradient are difficult to determine at a regional or local scale when the noise estimate is on a global scale. A filter with one global scale might under-smooth areas of high noise, but over-smooth less noisy area. Similarly, a static, global threshold may not be appropriate for the entire image because different regions have different degrees of detail. Thus, some methods use more than one filter for detecting edges and discard the thresholding method in edge discrimination. Multi-scale description of the image mimics the receptive fields of neurons in the early visual cortex of animals. At the small scale, details can be reliably detected. At the larger scale, the contours or the frame get more attention. So, the image features can be fully represented by combining a range of scales. The proposed multi-scale edge detection algorithm utilizes this hierarchical organization to detect and localize edges. Furthermore, instead of using one default global threshold, local dynamic threshold is introduced to discriminate edge or non-edge. Based on a critical value function, the local dynamic threshold for each scale is determined using a novel local noise estimation (LNE) method. Additionally, the proposed algorithm performs connectivity analysis on edge map to ensure that small, disconnected edges are removed. Experiments where this method is applied to a sequence of images of the same scene but with different signal-noise-ratio (SNR), show the method to be robust to noise.

  4. 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

    Xia, Sijing; Cartron, Michaël; Morby, James; Bryant, Donald A; Hunter, C Neil; Leggett, Graham J

    2016-02-23

    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 Ni(2+), 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

  5. 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

  6. Photometry of 433 Eros from 0.65 to 2.2 micrometers

    NASA Technical Reports Server (NTRS)

    Veeder, G. J.; Matson, D. L.; Bergstralh, J. T.; Johnson, T. V.

    1976-01-01

    Lightcurves of 433 Eros are reported for 11 bandpasses ranging from 0.65 to 2.2 micrometer in wavelength. The relative spectral reflectance was not seen to vary during our observations. Eros has a reflectance at 1.6 micrometers of about 1.5 and at 2.2 micrometers of about 1.7, where the spectral reflectance is scaled to unity at 0.56 micrometers. This spectral reflectance is suggestive of a mixture of silicates and material with high infrared reflectance, perhaps a metallic phase such as meteoritic 'iron'.

  7. 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.

  8. 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).

  9. 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

  10. 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…

  11. 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

  12. Robust Texture Image Representation by Scale Selective Local Binary Patterns.

    PubMed

    Guo, Zhenhua; Wang, Xingzheng; Zhou, Jie; You, Jane

    2016-02-01

    Local binary pattern (LBP) has successfully been used in computer vision and pattern recognition applications, such as texture recognition. It could effectively address grayscale and rotation variation. However, it failed to get desirable performance for texture classification with scale transformation. In this paper, a new method based on dominant LBP in scale space is proposed to address scale variation for texture classification. First, a scale space of a texture image is derived by a Gaussian filter. Then, a histogram of pre-learned dominant LBPs is built for each image in the scale space. Finally, for each pattern, the maximal frequency among different scales is considered as the scale invariant feature. Extensive experiments on five public texture databases (University of Illinois at Urbana-Champaign, Columbia Utrecht Database, Kungliga Tekniska Högskolan-Textures under varying Illumination, Pose and Scale, University of Maryland, and Amsterdam Library of Textures) validate the efficiency of the proposed feature extraction scheme. Coupled with the nearest subspace classifier, the proposed method could yield competitive results, which are 99.36%, 99.51%, 99.39%, 99.46%, and 99.71% for UIUC, CUReT, KTH-TIPS, UMD, and ALOT, respectively. Meanwhile, the proposed method inherits simple and efficient merits of LBP, for example, it could extract scale-robust feature for a 200×200 image within 0.24 s, which is applicable for many real-time applications. PMID:26685235

  13. The spatial scale of local adaptation in a stochastic environment.

    PubMed

    Hadfield, Jarrod D

    2016-07-01

    The distribution of phenotypes in space will be a compromise between adaptive plasticity and local adaptation increasing the fit of phenotypes to local conditions and gene flow reducing that fit. Theoretical models on the evolution of quantitative characters on spatially explicit landscapes have only considered scenarios where optimum trait values change as deterministic functions of space. Here, these models are extended to include stochastic spatially autocorrelated aspects to the environment, and consequently the optimal phenotype. Under these conditions, the regression of phenotype on the environmental variable becomes steeper as the spatial scale on which populations are sampled becomes larger. Under certain deterministic models - such as linear clines - the regression is constant. The way in which the regression changes with spatial scale is informative about the degree of phenotypic plasticity, the relative scale of effective gene flow and the environmental dependency of selection. Connections to temporal models are discussed. PMID:27188689

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

    PubMed

    Shim, Yunsic; Amar, Jacques G

    2016-07-01

    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. PMID:27394097

  15. Improved scaling of temperature-accelerated dynamics using localization

    NASA Astrophysics Data System (ADS)

    Shim, Yunsic; Amar, Jacques G.

    2016-07-01

    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 N3 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 N1/2. Some additional possible methods to improve the scaling of TAD are also discussed.

  16. 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

  17. 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.

  18. 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. PMID:26871313

  19. The role of local scale heterogeneities in terrestrial ecosystem functioning

    NASA Astrophysics Data System (ADS)

    Pappas, C.; Fatichi, S.; Rimkus, S.; Burlando, P.; Bugmann, H.; Huber, M.

    2013-12-01

    The coarse-grained spatial representation of many terrestrial ecosystem models hampers the importance of local scale heterogeneities. To discuss this issue, we combine a range of observations (forest inventories, eddy flux tower data, remote sensing products) and modeling approaches which allow us to investigate the role of local climate, topography and initial conditions (land cover and soil properties) when simulating vegetation dynamics. Three approaches for modeling terrestrial ecosystems, with contrasting degrees of abstraction, were selected: (i) LPJ, a well-established, area-based, Dynamic Global Vegetation Model (DGVM) that incorporates plant physiological and biogeochemical processes; (ii) LPJ-GUESS, a hybrid, individual-based approach that additionally considers more detailed processes of plant population dynamics; and (iii) D-LPJ, a spatially distributed version of LPJ, operating at a fine resolution (100m x 100m), which uses an enhanced hydrological representation accounting for lateral connectivity of surface and subsurface water fluxes. By confronting model simulations with a multivariate data-set available at the catchment scale, we argue that: (i) local environmental and topographic attributes that are often ignored or at best crudely represented within DGVM applications exert a strong control on terrestrial ecosystem functioning; (ii) the assumption of steady-state vegetation and soil carbon pools at the beginning of simulation studies (e.g., under 'current conditions'), as embedded in many DGVM applications, is in contradiction with the current state of many forests that, due to natural or anthropogenic disturbances, are often out of equilibrium; (iii) model evaluation against vegetation carbon fluxes (i.e., photosynthetic activity and respiration rates) does not imply an accurate simulation of vegetation carbon stocks (i.e., biomass). In addition, having gained insights about model performance at the catchment scale, where a wealth of information

  20. Comparative endothelial cell response on topographically patterned titanium and silicon substrates with micrometer to sub-micrometer feature sizes.

    PubMed

    Vandrangi, Prashanthi; Gott, Shannon C; Kozaka, Ryan; Rodgers, Victor G J; Rao, Masaru P

    2014-01-01

    In this work, we evaluate the in vitro response of endothelial cells (EC) to variation in precisely-defined, micrometer to sub-micrometer scale topography on two different substrate materials, titanium (Ti) and silicon (Si). Both substrates possess identically-patterned surfaces composed of microfabricated, groove-based gratings with groove widths ranging from 0.5 to 50 µm, grating pitch twice the groove width, and groove depth of 1.3 µm. These specific materials are chosen due to their relevance for implantable microdevice applications, while grating-based patterns are chosen for the potential they afford for inducing elongated and aligned cellular morphologies reminiscent of the native endothelium. Using EA926 cells, a human EC variant, we show significant improvement in cellular adhesion, proliferation, morphology, and function with decreasing feature size on patterned Ti substrates. Moreover, we show similar trending on patterned Si substrates, albeit to a lesser extent than on comparably patterned Ti substrates. Collectively, these results suggest promise for sub-micrometer topographic patterning in general, and sub-micrometer patterning of Ti specifically, as a means for enhancing endothelialization and neovascularisation for novel implantable microdevice applications. PMID:25357245

  1. Comparative Endothelial Cell Response on Topographically Patterned Titanium and Silicon Substrates with Micrometer to Sub-Micrometer Feature Sizes

    PubMed Central

    Kozaka, Ryan; Rodgers, Victor G. J.; Rao, Masaru P.

    2014-01-01

    In this work, we evaluate the in vitro response of endothelial cells (EC) to variation in precisely-defined, micrometer to sub-micrometer scale topography on two different substrate materials, titanium (Ti) and silicon (Si). Both substrates possess identically-patterned surfaces composed of microfabricated, groove-based gratings with groove widths ranging from 0.5 to 50 µm, grating pitch twice the groove width, and groove depth of 1.3 µm. These specific materials are chosen due to their relevance for implantable microdevice applications, while grating-based patterns are chosen for the potential they afford for inducing elongated and aligned cellular morphologies reminiscent of the native endothelium. Using EA926 cells, a human EC variant, we show significant improvement in cellular adhesion, proliferation, morphology, and function with decreasing feature size on patterned Ti substrates. Moreover, we show similar trending on patterned Si substrates, albeit to a lesser extent than on comparably patterned Ti substrates. Collectively, these results suggest promise for sub-micrometer topographic patterning in general, and sub-micrometer patterning of Ti specifically, as a means for enhancing endothelialization and neovascularisation for novel implantable microdevice applications. PMID:25357245

  2. 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.; Titus, T. N.; Russell, C. T.; Raymond, C. A.; Mittlefehldt, D. W.; Toplis, M. J.; Forni, O.; Sykes, M. V.

    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

  3. Local versus global scales of organization in auditory cortex.

    PubMed

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

    2014-09-01

    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 40 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

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. Weathering processes in clayey sediments - on local to catchment scale

    NASA Astrophysics Data System (ADS)

    Ernstsen, Vibeke

    2013-04-01

    In Denmark, postglacial weathering processes have introduced considerable changes in the inherited properties of the young sediments of Weichselian age. Over the last 12.000 years, oxidation and acidification are the main responsible processes for the changes that have taken place in water recharge areas. The distribution of nitrate has been shown to be closely related to the geochemical environment above the interface between the oxidized and reduced sediments and present in the oxic environment only. In the present study, the formation of oxidized geochemical environments was studied at different scales, from local to catchment scale, in areas dominated by clayey till. Sediment samples were collected in the field from surface and down to below the redox interface and described by color, redoximorphic features, and sediment type and analyzed for e.g., total amount of reduced compounds and reduced compounds (pyrite, ferrous iron, and organic matter). The results were used to describe the spatial development of oxidized environments and to identify the smallest possible scale at witch nitrate reduction in the subsurface can be assessed for Danish catchments.

  9. 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.

  10. Local dynamic subgrid-scale models in channel flow

    NASA Astrophysics Data System (ADS)

    Cabot, William H.

    1994-12-01

    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.

  11. 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

  12. 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

  13. Effects of the continuous-spontaneous-localization model in the regime of large localization length scale

    NASA Astrophysics Data System (ADS)

    Bedingham, D. J.

    2014-03-01

    Working in the limit in which the localization length scale is large compared to other relevant length scales, we examine three experimental situations with the continuous-spontaneous-localization (CSL) model, a well-motivated alternative to standard quantum theory. These are the two-slit experiment, scattering from a potential barrier, and release of two noninteracting particles simultaneously from a potential trap. In each case we calculate the diagonal part of the time-evolved density matrix giving a probability density function over final measured states. The case of the two-slit experiment is already well understood and we reproduce some known conditions for observing loss of interference. The other examples have not previously been examined in the context of CSL. For scattering from a potential barrier we find that the probability of reflection is unchanged by CSL; however, the momentum state is spread in a characteristic way. For the case of two particles released simultaneously from a trap we find that it is more likely that the particles diffuse in the same direction than would happen if the particles behaved independently. We assess the possibility of observing these effects.

  14. 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

  15. Link between local scale BC emissions and large scale atmospheric solar absorption

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

    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 report observations from the first phase of Project Surya to 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 satellite and AERONET observations at the regional scale (IGP). The daily mean BC concentrations at SVI1 showed the large increase of BC during the dry season (December to February) with values reaching 35 μg m-3. Space based LIDAR data reveal how the biomass smoke is trapped within the first kilometre during the dry season and its extension to above 5 km during the pre-monsoon season. As a result during the dry season, the variance in the daily mean SSA 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), thus suggesting in-situ observations at few locations can be used to infer spatial mean forcing. The atmospheric forcing due to BC and OC exceeded 20 W m-2 during all months from November to May, leading to the deduction that elimination of cook stove smoke emissions through clean cooking technologies will likely have a major positive impact on health and the regional climate.

  16. 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.

  17. 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

  18. 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.

  19. 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. PMID:25963196

  20. Robust multi-scale superpixel classification for optic cup localization.

    PubMed

    Tan, Ngan-Meng; Xu, Yanwu; Goh, Wooi Boon; Liu, Jiang

    2015-03-01

    This paper presents an optimal model integration framework to robustly localize the optic cup in fundus images for glaucoma detection. This work is based on the existing superpixel classification approach and makes two major contributions. First, it addresses the issues of classification performance variations due to repeated random selection of training samples, and offers a better localization solution. Second, multiple superpixel resolutions are integrated and unified for better cup boundary adherence. Compared to the state-of-the-art intra-image learning approach, we demonstrate improvements in optic cup localization accuracy with full cup-to-disc ratio range, while incurring only minor increase in computing cost. PMID:25453464

  1. Micrometer-size vesicle formation triggered by UV light.

    PubMed

    Shima, Tatsuya; Muraoka, Takahiro; Hamada, Tsutomu; Morita, Masamune; Takagi, Masahiro; Fukuoka, Hajime; Inoue, Yuichi; Sagawa, Takashi; Ishijima, Akihiko; Omata, Yuki; Yamashita, Takashi; Kinbara, Kazushi

    2014-07-01

    Vesicle formation is a fundamental kinetic process related to the vesicle budding and endocytosis in a cell. In the vesicle formation by artificial means, transformation of lamellar lipid aggregates into spherical architectures is a key process and known to be prompted by e.g. heat, infrared irradiation, and alternating electric field induction. Here we report UV-light-driven formation of vesicles from particles consisting of crumpled phospholipid multilayer membranes involving a photoactive amphiphilic compound composed of 1,4-bis(4-phenylethynyl)benzene (BPEB) units. The particles can readily be prepared from a mixture of these components, which is casted on the glass surface followed by addition of water under ultrasonic radiation. Interestingly, upon irradiation with UV light, micrometer-size vesicles were generated from the particles. Neither infrared light irradiation nor heating prompted the vesicle formation. Taking advantage of the benefits of light, we successfully demonstrated micrometer-scale spatiotemporal control of single vesicle formation. It is also revealed that the BPEB units in the amphiphile are essential for this phenomenon. PMID:24898450

  2. 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.

  3. 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.

  4. Multi-Scale Locality-Constrained Spatiotemporal Coding for Local Feature Based Human Action Recognition

    PubMed Central

    Liu, Yu; Wang, Wei; Xu, Wei; Zhang, Maojun

    2013-01-01

    We propose a Multiscale Locality-Constrained Spatiotemporal Coding (MLSC) method to improve the traditional bag of features (BoF) algorithm which ignores the spatiotemporal relationship of local features for human action recognition in video. To model this spatiotemporal relationship, MLSC involves the spatiotemporal position of local feature into feature coding processing. It projects local features into a sub space-time-volume (sub-STV) and encodes them with a locality-constrained linear coding. A group of sub-STV features obtained from one video with MLSC and max-pooling are used to classify this video. In classification stage, the Locality-Constrained Group Sparse Representation (LGSR) is adopted to utilize the intrinsic group information of these sub-STV features. The experimental results on KTH, Weizmann, and UCF sports datasets show that our method achieves better performance than the competing local spatiotemporal feature-based human action recognition methods. PMID:24194681

  5. 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. PMID:26166784

  6. 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.

  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. Measles and Rubella: Scale Free Distribution of Local Infection Clusters.

    PubMed

    Yoshikura, Hiroshi; Takeuchi, Fumihiko

    2016-07-22

    This study examined the size distribution of local infection clusters (referred to as clusters hereafter) of measles and rubella from 2008-2013 in Japan. When the logarithm of the cluster sizes were plotted on the x-axis and the logarithm of their frequencies were plotted on the y-axis, the plots fell on a rightward descending straight line. The size distribution was observed to follow a power law. As the size distribution of the clusters could be equated with that of local secondary infections initiated by 1 patient, the size distribution of the clusters, in fact, represented the effective reproduction numbers at the local level. As the power law distribution has no typical sizes, it was suggested that measles or rubella epidemics in Japan had no typical reproduction number. Higher the population size and higher the total number of patients, flatter was the slope of the plots, thus larger was the proportion of larger clusters. An epidemic of measles or rubella in Japan could be represented more appropriately by the cluster size frequency distribution rather than by the reproduction number. PMID:26567836

  9. Plasmon slot waveguides: Towards chip-scale propagation with subwavelength-scale localization

    NASA Astrophysics Data System (ADS)

    Dionne, J. A.; Sweatlock, L. A.; Atwater, H. A.; Polman, A.

    2006-01-01

    We present a numerical analysis of surface plasmon waveguides exhibiting both long-range propagation and spatial confinement of light with lateral dimensions of less than 10% of the free-space wavelength. Attention is given to characterizing the dispersion relations, wavelength-dependent propagation, and energy density decay in two-dimensional Ag/SiO2/Ag structures with waveguide thicknesses ranging from 12nmto250nm . As in conventional planar insulator-metal-insulator (IMI) surface plasmon waveguides, analytic dispersion results indicate a splitting of plasmon modes—corresponding to symmetric and antisymmetric electric field distributions—as SiO2 core thickness is decreased below 100nm . However, unlike IMI structures, surface plasmon momentum of the symmetric mode does not always exceed photon momentum, with thicker films ( dtilde 50nm) achieving effective indices as low as n=0.15 . In addition, antisymmetric mode dispersion exhibits a cutoff for films thinner than d=20nm , terminating at least 0.25eV below resonance. From visible to near infrared wavelengths, plasmon propagation exceeds tens of microns with fields confined to within 20nm of the structure. As the SiO2 core thickness is increased, propagation distances also increase with localization remaining constant. Conventional waveguiding modes of the structure are not observed until the core thickness approaches 100nm . At such thicknesses, both transverse magnetic and transverse electric modes can be observed. Interestingly, for nonpropagating modes (i.e., modes where propagation does not exceed the micron scale), considerable field enhancement in the waveguide core is observed, rivaling the intensities reported in resonantly excited metallic nanoparticle waveguides.

  10. Scaling of the local quantum uncertainty at quantum phase transitions

    NASA Astrophysics Data System (ADS)

    Coulamy, I. B.; Warnes, J. H.; Sarandy, M. S.; Saguia, A.

    2016-04-01

    We investigate the local quantum uncertainty (LQU) between a block of L qubits and one single qubit in a composite system of n qubits driven through a quantum phase transition (QPT). A first-order QPT is analytically considered through a Hamiltonian implementation of the quantum search. In the case of second-order QPTs, we consider the transverse-field Ising chain via a numerical analysis through density matrix renormalization group. For both cases, we compute the LQU for finite-sizes as a function of L and of the coupling parameter, analyzing its pronounced behavior at the QPT.

  11. Local topology, multi-scale interactions and stochasticity in space plasma physics

    NASA Astrophysics Data System (ADS)

    Materassi, M.; Consolini, G.

    2014-12-01

    In space physics very important phenomena, as reconnection, are determined by the local topology of the streamlines and magnetic lines of plasma, and by multi-scale interactions. In this work, an attempt is presented to deal with dynamical variables highlighting both the local topology and the role of space scale. In order to promote local topology to the role of a dynamical variable, use is made of the gradients of the velocity and of the magnetic field, through which the description of the local topology becomes very transparent. Such a formulation, well explored in Hydrodynamics, is extended here to the MHD. The new dynamical variables evolve in a finite scale stochastic dynamics: letting the scale appear explicitly as a variable of the problem helps studying inter-scale processes, while statistical aspects of topological variable dynamics are expected to be extremely relevant in the turbulent regime, where a stochastic field scenario is, in practice, taking place.

  12. Integrating Local and Global Routing on Scale-Free Networks

    NASA Astrophysics Data System (ADS)

    Pu, Cun-Lai; Pei, Wen-Jiang

    Network navigation is one of the main problems in large communication networks. We propose a new routing strategy in which some smart nodes in networks deliver messages to next hops on the paths towards destinations according to Yan's algorithm while the other nodes just deliver messages randomly. We test our routing strategy in a large scale-free network. Simulations show that the average delivery time decreases with increase of number of smart nodes, while the maximal network capacity increases with number of smart nodes in the network. Moreover our strategy is much more efficient when employed with target selection than with random selection of the smart nodes.

  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. New methods for large scale local and global optimization

    NASA Astrophysics Data System (ADS)

    Byrd, Richard; Schnabel, Robert

    1994-07-01

    We have pursued all three topics described in the proposal during this research period. A large amount of effort has gone into the development of large scale global optimization methods for molecular configuration problems. We have developed new general purpose methods that combine efficient stochastic global optimization techniques with several new, more deterministic techniques that account for most of the computational effort, and the success, of the methods. We have applied our methods to Lennard-Jones problems with up to 75 atoms, to water clusters with up to 31, molecules, and polymers with up to 58 amino acids. The results appear to be the best so far by general purpose optimization methods, and appear to be leading to some interesting chemistry issues. Our research on the second topic, tensor methods, has addressed several areas. We have designed and implemented tensor methods for large sparse systems of nonlinear equations and nonlinear least squares, and have obtained excellent test results on a wide range of problems. We have also developed new tensor methods for nonlinearly constrained optimization problem, and have obtained promising theoretical and preliminary computational results. Finally, on the third topic, limited memory methods for large scale optimization, we have developed and implemented new, extremely efficient limited memory methods for bound constrained problems, and new limited memory trust regions methods, both using our-recently developed compact representations for quasi-Newton matrices. Computational test results for both methods are promising.

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

    PubMed

    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. PMID:25113741

  16. 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.

  17. Flattening and Cooling of Millimeter- and Micrometer-Sized Alumina Drops

    NASA Astrophysics Data System (ADS)

    Goutier, S.; Vardelle, M.; Labbe, J. C.; Fauchais, P.

    2011-01-01

    An experimental setup was developed to produce fully melted, millimeter-sized, ceramic or metallic drops with impact velocities up to 10 m/s. Such impact velocities allow achievement of impact Weber numbers, close to those of the plasma spray process ( We = 2300) with droplets in the tens of micrometer size range. A fast camera (4000 image/s) combined with a fast pyrometer (4000 Hz), allowed the flattening of the drop to be followed. To study the flattening of micrometer-sized droplets, a direct-current (dc) plasma torch was used to melt alumina particles (around 45 μm in diameter). The experimental setup was composed of a fast (50 ns) two-color pyrometer and two fast (at best an exposure time of 2 μs) charge-coupled device cameras (one orthogonal and other tangential to the substrate). The flattening behaviors of millimeter- and micrometer-sized particles were compared. First, impacts of alumina drops (millimeter-sized) with velocities up to 10 m/s were studied. Results were then compared with micrometer-sized alumina particles (about 45 μm in diameter) sprayed with the dc plasma torch. A correlation was found between both flattening scales, and, in spite of the lower impact velocity at the millimeter scale, droplet ejections were also found as obtained at the micrometer scale. This work shows that for a sound comparison of phenomena at the two different scales it is mandatory to have Weber numbers as close as possible in both cases.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 ...

  19. 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.

  20. Genetic diversity of Echinococcus multilocularis on a local scale.

    PubMed

    Knapp, J; Guislain, M-H; Bart, J M; Raoul, F; Gottstein, B; Giraudoux, P; Piarroux, R

    2008-05-01

    Echinococcusmultilocularis is the causative agent of human Alveolar Echinococcosis (AE), and it is one of the most lethal zoonotic infections in the Northern Hemisphere. In France, the eastern and central regions are endemic areas; Franche-Comté, Lorraine and Auvergne are particularly contaminated. Recently, several human cases were recorded in the French Ardennes area, a region adjacent to the western border of the E. multilocularis range in France. A previous study in this focus described a prevalence of over 50% of the parasite in red foxes. The present study investigated the genetic diversity of adult worms collected from foxes in a 900km(2) area in the Ardennes. Instead of a conventional mitochondrial target (ATP6), two microsatellite targets (EmsB and NAK1) were used. A total of 140 adult worms isolated from 25 red foxes were genotyped. After hierarchical clustering analyses, the EmsB target enabled us to distinguish two main assemblages, each divided into sub-groups, yielding the differentiation of six clusters or assemblage profiles. Thirteen foxes (52% of the foxes) each harbored worms from at least two different assemblage profiles, suggesting they had become infected by several sources. Using the NAK1 target, we identified 3 alleles, two found in association with the two EmsB assemblages. With the NAK1 target, we investigated the parasite breeding system and the possible causes of genetic diversification. Only one fox harbored hybrid worms, indicative of a possible (and rare) occurrence of recombination, although multiple infections have been observed in foxes. These results confirm the usefulness of microsatellite targets for assessing genetic polymorphism in a geographically restricted local range. PMID:18406214

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  2. Scale-dependent non-Gaussianity as a generalization of the local model

    SciTech Connect

    Becker, Adam; Huterer, Dragan; Kadota, Kenji E-mail: huterer@umich.edu

    2011-01-01

    We generalize the local model of primordial non-Gaussianity by promoting the parameter f{sub NL} to a general scale-dependent function f{sub NL}(k). We calculate the resulting bispectrum and the effect on the bias of dark matter halos, and thus the extent to which f{sub NL}(k) can be measured from the large-scale structure observations. By calculating the principal components of f{sub NL}(k), we identify scales where this form of non-Gaussianity is best constrained and estimate the overlap with previously studied local and equilateral non-Gaussian models.

  3. 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.

  4. 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

  5. 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.

  6. 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. PMID:26584368

  7. 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.

  8. Vibrational Spectroscopic Observation of Atomic-Scale Local Surface Sites Using Site-Selective Signal Enhancement.

    PubMed

    Hu, Jian; Hoshi, Nagahiro; Uosaki, Kohei; Ikeda, Katsuyoshi

    2015-12-01

    Molecule-substrate interactions are sensitively affected by atomic-scale surface structures. Unique activity in heterogeneous catalysts or electrocatalysts is often related with local surface sites with specific structures. We demonstrate that adsorption geometry of a model molecule with an isocyanide anchor is drastically varied among one-fold atop, two-fold bridge, and three-fold hollow configurations with increasing the size of atomic-scale local surface sites of Pd islands on an Au(111) model surface. The vibrational spectroscopic observation of such local information is realized by site-selective and self-assembled formation of hotspots, where Raman scattering intensity is significantly enhanced via excitation of localized surface plasmons. PMID:26551000

  9. 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. PMID:26800540

  10. Nutrient enrichment homogenizes lake benthic assemblages at local and regional scales.

    PubMed

    Donohue, Ian; Jackson, Andrew L; Pusch, Martin T; Irvine, Kenneth

    2009-12-01

    The compositional heterogeneity of biotic assemblages among sites, or beta-diversity, regulates the relationship between local and regional species diversity across scales. Recent work has suggested that increased harshness of environmental conditions tends to reduce beta-diversity by decreasing the importance of stochastic processes in structuring assemblages. We investigated the effect of nutrient enrichment on the compositional heterogeneity of lake benthic invertebrate assemblages in Ireland at both local (within-lake) and regional (among-lake) scales. At local scales, we found that the compositional heterogeneity of benthic assemblages was related inversely to the extent of nutrient enrichment (as indicated by measurements of water column total phosphorus, total nitrogen, and chlorophyll a), after effects of lake morphology (i.e., surface area, connectivity, and depth of sampling) and alkalinity were accounted for. At regional scales, we found that nutrient-rich lakes had significantly more homogenous benthic assemblages than nutrient-poor lakes, over and above the effect of alkalinity and across a similar range of lake morphologies. These findings have profound implications for global aquatic biodiversity, as the homogenization of benthic assemblages at both local and regional scales may have important and unpredictable effects on whole aquatic ecosystems, with potentially considerable ecological and evolutionary consequences. PMID:20120814

  11. 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.

  12. 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.

  13. 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. PMID:22900045

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. Pest control experiments show benefits of complexity at landscape and local scales.

    PubMed

    Chaplin-Kramer, Rebecca; Kremen, Claire

    2012-10-01

    Farms benefit from pest control services provided by nature, but management of these services requires an understanding of how habitat complexity within and around the farm impacts the relationship between agricultural pests and their enemies. Using cage experiments, this study measures the effect of habitat complexity across scales on pest suppression of the cabbage aphid Brevicoryne brassicae in broccoli. Our results reveal that proportional reduction of pest density increases with complexity both at the landscape scale (measured by natural habitat cover in the 1 km around the farm) and at the local scale (plant diversity). While high local complexity can compensate for low complexity at landscape scales and vice versa, a delay in natural enemy arrival to locally complex sites in simple landscapes may compromise the enemies' ability to provide adequate control. Local complexity in simplified landscapes may only provide adequate top-down pest control in cooler microclimates with relatively low aphid colonization rates. Even so, strong natural enemy function can be overwhelmed by high rates of pest reproduction or colonization from nearby source habitat. PMID:23210310

  19. 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. PMID:27267488

  20. 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…

  1. 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.

  2. AIR TOXICS MODELING FROM LOCAL TO REGIONAL SCALES TO SUPPORT THE 2002 MULTIPOLLUTANT ASSESSMENT

    EPA Science Inventory

    This research focuses on developing models that can describe the chemical and physical processes affecting concentrations of toxic air pollutants in the atmosphere, at spatial scales, ranging from local (< 1 km) to regional (36 km). One objective of this task is to extend the ca...

  3. 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,…

  4. Genome-scale quantitative characterization of bacterial protein localization dynamics throughout the cell cycle

    PubMed Central

    Kuwada, Nathan J; Traxler, Beth; Wiggins, Paul A

    2015-01-01

    Bacterial cells display both spatial and temporal organization, and this complex structure is known to play a central role in cellular function. Although nearly one-fifth of all proteins in Escherichia coli localize to specific subcellular locations, fundamental questions remain about how cellular-scale structure is encoded at the level of molecular-scale interactions. One significant limitation to our understanding is that the localization behavior of only a small subset of proteins has been characterized in detail. As an essential step toward a global model of protein localization in bacteria, we capture and quantitatively analyze spatial and temporal protein localization patterns throughout the cell cycle for nearly every protein in E. coli that exhibits nondiffuse localization. This genome-scale analysis reveals significant complexity in patterning, notably in the behavior of DNA-binding proteins. Complete cell-cycle imaging also facilitates analysis of protein partitioning to daughter cells at division, revealing a broad and robust assortment of asymmetric partitioning behaviors. PMID:25353361

  5. A scale- and orientation-adaptive extension of Local Binary Patterns for texture classification

    PubMed Central

    Hegenbart, Sebastian; Uhl, Andreas

    2015-01-01

    Local Binary Patterns (LBPs) have been used in a wide range of texture classification scenarios and have proven to provide a highly discriminative feature representation. A major limitation of LBP is its sensitivity to affine transformations. In this work, we present a scale- and rotation-invariant computation of LBP. Rotation-invariance is achieved by explicit alignment of features at the extraction level, using a robust estimate of global orientation. Scale-adapted features are computed in reference to the estimated scale of an image, based on the distribution of scale normalized Laplacian responses in a scale-space representation. Intrinsic-scale-adaption is performed to compute features, independent of the intrinsic texture scale, leading to a significantly increased discriminative power for a large amount of texture classes. In a final step, the rotation- and scale-invariant features are combined in a multi-resolution representation, which improves the classification accuracy in texture classification scenarios with scaling and rotation significantly. PMID:26240440

  6. LETTER: Elongation and current scalings of local and global energy transport

    NASA Astrophysics Data System (ADS)

    Becker, G.

    2002-04-01

    The scaling of local and global energy confinement with elongation κ and current in L- and H-mode plasmas is explored. It is shown that the elongation enters global confinement only through the geometrical quantities of plasma volume and surface area, while local transport does not contribute. The global scaling τEproptoκ0.8 is caused by WproptonT0V with the volume Vproptoκ and the surface area leading to T0proptoκ-0.2. Empirical scalings of the effective heat diffusivity χ with κ, the current inside a flux surface I(x), Bp and q are presented. Applying I(x) makes χ independent of κ, while a formulation with q yields strong implicit and explicit κ dependences.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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)

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. 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.

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

    NASA Astrophysics Data System (ADS)

    Delin, Geoffrey N.; Healy, Richard W.; Lorenz, David L.; Nimmo, John R.

    2007-02-01

    SummaryRegional 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 m 2. 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 km 2. 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. 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.

  19. 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.

  20. 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.

  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. 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.

  3. 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

  4. 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. PMID:21495686

  5. 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

  6. 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

  7. Absence of localized acoustic waves in a scale-free correlated random system.

    PubMed

    Costa, A E B; de Moura, F A B F

    2011-02-16

    We numerically study the propagation of acoustic waves in a one-dimensional medium with a scale-free long-range correlated elasticity distribution. The random elasticity distribution is assumed to have a power spectrum S(k) ∼ 1/k(α). By using a transfer-matrix method we solve the discrete version of the scalar wave equation and compute the localization length. In addition, we apply a second-order finite-difference method for both the time and spatial variables and study the nature of the waves that propagate in the chain. Our numerical data indicate the presence of extended acoustic waves for a high degree of correlations. In contrast with local correlations, we numerically demonstrate that scale-free correlations promote a stable phase of free acoustic waves in the thermodynamic limit. PMID:21406919

  8. 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. PMID:27536713

  9. 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. PMID:25733889

  10. Investigation of both local and global topological ingredients on transport efficiency in scale-free networks.

    PubMed

    Huang, Wei; Chow, Tommy W S

    2009-12-01

    This paper investigates the combined effect of local and global topological ingredients for routing packets on transport efficiency in scale-free networks with different degree exponents. Four different transport efficiency measurements, namely, the critical packet generation rate, the average number of overall packet loads, the relative variance of packet number on each node, and the relative variance of transport time from source to destination, are investigated in this paper. The combined effects of global and local ingredients on four measurements are presented and analyzed. We also investigate the effect of degree exponent on four measurements. Based on the results we obtained, we propose an improved routing strategy with memory information. Simulation results show that the critical packet generation rate can be efficiently improved by using the improved routing strategy with memory information, especially when packets are showing strong inclination of being forwarded to low-degree or high-degree nodes in scale-free networks with small degree exponents. PMID:20059220

  11. 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.

  12. 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.

  13. 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.

  14. Nodes Localization in 3D Wireless Sensor Networks Based on Multidimensional Scaling Algorithm

    PubMed Central

    2014-01-01

    In the recent years, there has been a huge advancement in wireless sensor computing technology. Today, wireless sensor network (WSN) has become a key technology for different types of smart environment. Nodes localization in WSN has arisen as a very challenging problem in the research community. Most of the applications for WSN are not useful without a priory known nodes positions. Adding GPS receivers to each node is an expensive solution and inapplicable for indoor environments. In this paper, we implemented and evaluated an algorithm based on multidimensional scaling (MDS) technique for three-dimensional (3D) nodes localization in WSN using improved heuristic method for distance calculation. Using extensive simulations we investigated our approach regarding various network parameters. We compared the results from the simulations with other approaches for 3D-WSN localization and showed that our approach outperforms other techniques in terms of accuracy.

  15. The Mid-Infrared Cepheid Distance Scale: A Reconnaissance Program of Cepheids in the Local Group

    NASA Astrophysics Data System (ADS)

    Madore, Barry; Freedman, Wendy; Mager, Violet; Rigby, Jane

    2008-03-01

    We request archival funding to search for serendipitous IRAC detections of known Cepheids in Local Group galaxies. This archival proposal is a parallel study in support of a Cycle 5 GO proposal (PI: Freedman) to re-calibrate the Cepheid distance scale from the ground up using new IRAC photometry of ten Galactic Cepheids having HST trigonometric parallaxes (Benedict et al. 2007), in combination with eighty LMC Cepheids (from Persson et al. 2004), to establish the slope and secure the zero point of the Cepheid Period-Luminosity Relation at 3.6 and 4.5 micron. Here we intend to characterize the mid-infrared detectability of Cepheids in Local Group galaxies, by examining upwards of 8,000 archival images containing cataloged Cepheids with known periods and predicted luminosities. The Cepheids in these images exhibit a wide range of background intensity, often have complex crowding, and have a wide range of apparent magnitudes. From this reconnaissance survey we will be able to directly assess the ability of Spitzer to obtain high signal-to-noise observations of Cepheids in individual Local Group galaxies, and we will select the least crowded and least confused of the serendipitously--obserserved Cepheids. We plan to target this sample in the Warm Mission, with the goal of putting the Local Group securely onto the mid-infrared Cepheid distance scale.

  16. Fractional dynamics of tracer transport in fractured media from local to regional scales

    NASA Astrophysics Data System (ADS)

    Zhang, Yong; Reeves, Donald M.; Pohlmann, Karl; Chapman, Jenny B.; Russell, Charles E.

    2013-06-01

    Tracer transport through fractured media exhibits concurrent direction-dependent super-diffusive spreading along high-permeability fractures and sub-diffusion caused by mass transfer between fractures and the rock matrix. The resultant complex dynamics challenge the applicability of conventional physical models based on Fick's law. This study proposes a multi-scaling tempered fractional-derivative (TFD) model to explore fractional dynamics for tracer transport in fractured media. Applications show that the TFD model can capture anomalous transport observed in small-scale single fractures, intermediate-scale fractured aquifers, and two-dimensional large-scale discrete fracture networks. Tracer transport in fractured media from local (0.255-meter long) to regional (400-meter long) scales therefore can be quantified by a general fractional-derivative model. Fractional dynamics in fractured media can be scale dependent, owning to 1) the finite length of fractures that constrains the large displacement of tracers, and 2) the increasing mass exchange capacity along the travel path that enhances sub-diffusion.

  17. An efficient linear-scaling CCSD(T) method based on local natural orbitals

    NASA Astrophysics Data System (ADS)

    Rolik, Zoltán; Szegedy, Lóránt; Ladjánszki, István; Ladóczki, Bence; Kállay, Mihály

    2013-09-01

    An improved version of our general-order local coupled-cluster (CC) approach [Z. Rolik and M. Kállay, J. Chem. Phys. 135, 104111 (2011)], 10.1063/1.3632085 and its efficient implementation at the CC singles and doubles with perturbative triples [CCSD(T)] level is presented. The method combines the cluster-in-molecule approach of Li and co-workers [J. Chem. Phys. 131, 114109 (2009)], 10.1063/1.3218842 with frozen natural orbital (NO) techniques. To break down the unfavorable fifth-power scaling of our original approach a two-level domain construction algorithm has been developed. First, an extended domain of localized molecular orbitals (LMOs) is assembled based on the spatial distance of the orbitals. The necessary integrals are evaluated and transformed in these domains invoking the density fitting approximation. In the second step, for each occupied LMO of the extended domain a local subspace of occupied and virtual orbitals is constructed including approximate second-order Møller-Plesset NOs. The CC equations are solved and the perturbative corrections are calculated in the local subspace for each occupied LMO using a highly-efficient CCSD(T) code, which was optimized for the typical sizes of the local subspaces. The total correlation energy is evaluated as the sum of the individual contributions. The computation time of our approach scales linearly with the system size, while its memory and disk space requirements are independent thereof. Test calculations demonstrate that currently our method is one of the most efficient local CCSD(T) approaches and can be routinely applied to molecules of up to 100 atoms with reasonable basis sets.

  18. 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. PMID:24167259

  19. 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

  20. Biodiversity of stream insects: variation at local, basin, and regional scales.

    PubMed

    Vinson, M R; Hawkins, C P

    1998-01-01

    We review the major conceptual developments that have occurred over the last 50 years concerning the factors that influence insect biodiversity in streams and examine how well empirical descriptions and theory match. Stream insects appear to respond to both spatial and temporal variation in physical heterogeneity. At all spatial scales, the data largely support the idea that physical complexity promotes biological richness, although exceptions to this relationship were found. These exceptions may be related to how we measure habitat complexity at finer spatial scales and to factors that influence regional richness, such as biogeographic history, at broader spatial scales. However, the degree to which local stream insect assemblages are influenced by regional processes is largely unknown. PMID:15012391

  1. 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

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

    PubMed

    Nguyen, Dinh T; Gómez-Zurita, Jesús

    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

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. Detecting Humans in Dense Crowds Using Locally-Consistent Scale Prior and Global Occlusion Reasoning.

    PubMed

    Idrees, Haroon; Soomro, Khurram; Shah, Mubarak

    2015-10-01

    Human detection in dense crowds is an important problem, as it is a prerequisite to many other visual tasks, such as tracking, counting, action recognition or anomaly detection in behaviors exhibited by individuals in a dense crowd. This problem is challenging due to the large number of individuals, small apparent size, severe occlusions and perspective distortion. However, crowded scenes also offer contextual constraints that can be used to tackle these challenges. In this paper, we explore context for human detection in dense crowds in the form of a locally-consistent scale prior which captures the similarity in scale in local neighborhoods and its smooth variation over the image. Using the scale and confidence of detections obtained from an underlying human detector, we infer scale and confidence priors using Markov Random Field. In an iterative mechanism, the confidences of detection hypotheses are modified to reflect consistency with the inferred priors, and the priors are updated based on the new detections. The final set of detections obtained are then reasoned for occlusion using Binary Integer Programming where overlaps and relations between parts of individuals are encoded as linear constraints. Both human detection and occlusion reasoning in proposed approach are solved with local neighbor-dependent constraints, thereby respecting the inter-dependence between individuals characteristic to dense crowd analysis. In addition, we propose a mechanism to detect different combinations of body parts without requiring annotations for individual combinations. We performed experiments on a new and extremely challenging dataset of dense crowd images showing marked improvement over the underlying human detector. PMID:26340254

  8. 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.

  9. 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.

  10. 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%.

  11. 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

  12. 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

  13. 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.

  14. V S Profiles from Noise Cross Correlation at Local and Small Scale

    NASA Astrophysics Data System (ADS)

    de Nisco, G.; Nunziata, C.

    2011-03-01

    Ambient noise measurements have been performed at local and small scales in the Neapolitan and surrounding areas (Campania, southern Italy) by employing two broad-band Kinemetrics Q330 stations, equipped with Episensor ES-T three component accelerometers. In both experiments frequency time analysis (FTAN method) has been performed on the vertical and radial components of noise cross correlations to retrieve the Rayleigh wave dispersion (Green's function). At local scale, over an interstation distance of about 26 km, the group velocity dispersion values have been compared with those obtained from FTAN analysis on recordings of two earthquakes with similar path. At small scale, measurements have been carried out over an interstation distance of about 440 m in the public gardens of Scampia, the northernmost quarter of Naples. The Rayleigh wave group velocity dispersion data obtained from noise cross correlation, have been combined with those from active seismic experiment along the same alignment, but shorter (120 m offset). The non linear inversion of such a dispersion curve has allowed the definition of V S models to depths of 100 m, in agreement with nearby stratigraphy. Moreover, a good agreement has resulted for the resonance frequency among the H/V ratio, the ellipticity of the fundamental mode computed for the chosen V S model, and the average two-dimensional (2D) spectral amplification computed along a cross section representative of the Scampia quarter.

  15. 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

  16. 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

  17. Loschmidt echo in many-spin systems: contrasting time scales of local and global measurements.

    PubMed

    Zangara, Pablo R; Bendersky, Denise; Levstein, Patricia R; Pastawski, Horacio M

    2016-06-13

    A local excitation in a quantum many-spin system evolves deterministically. A time-reversal procedure, involving the inversion of the signs of every energy and interaction, should produce the excitation revival. This idea, experimentally coined in nuclear magnetic resonance, embodies the concept of the Loschmidt echo (LE). While such an implementation involves a single spin autocorrelation M(1,1), i.e. a local LE, theoretical efforts have focused on the study of the recovery probability of a complete many-body state, referred to here as global or many-body LE MMB Here, we analyse the relation between these magnitudes, with regard to their characteristic time scales and their dependence on the number of spins N We show that the global LE can be understood, to some extent, as the simultaneous occurrence of N independent local LEs, i.e. MMB∼(M(1,1))(N/4) This extensive hypothesis is exact for very short times and confirmed numerically beyond such a regime. Furthermore, we discuss a general picture of the decay of M1,1 as a consequence of the interplay between the time scale that characterizes the reversible interactions (T(2)) and that of the perturbation (τ(Σ)). Our analysis suggests that the short-time decay, characterized by the time scale τ(Σ), is greatly enhanced by the complex processes that occur beyond T(2) This would ultimately lead to the experimentally observed T(3), which was found to be roughly independent of τ(Σ) but closely tied to T(2). PMID:27140970

  18. 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.

  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. PMID:21913673

  20. 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

  1. 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. PMID:26262345

  2. 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

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

    PubMed

    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

  4. 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).

  5. 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.

  6. Locally activated Monte Carlo method for long-time-scale simulations

    NASA Astrophysics Data System (ADS)

    Kaukonen, M.; Peräjoki, J.; Nieminen, R. M.; Jungnickel, G.; Frauenheim, Th.

    2000-01-01

    We present a technique for the structural optimization of atom models to study long time relaxation processes involving different time scales. The method takes advantage of the benefits of both the kinetic Monte Carlo (KMC) and the molecular dynamics simulation techniques. In contrast to ordinary KMC, our method allows for an estimation of a true lower limit for the time scale of a relaxation process. The scheme is fairly general in that neither the typical pathways nor the typical metastable states need to be known prior to the simulation. It is independent of the lattice type and the potential which describes the atomic interactions. It is adopted to study systems with structural and/or chemical inhomogeneity which makes it particularly useful for studying growth and diffusion processes in a variety of physical systems, including crystalline bulk, amorphous systems, surfaces with adsorbates, fluids, and interfaces. As a simple illustration we apply the locally activated Monte Carlo to study hydrogen diffusion in diamond.

  7. Scaling relations of moment magnitude, local magnitude, and duration magnitude for earthquakes originated in northeast India

    NASA Astrophysics Data System (ADS)

    Bora, Dipok K.

    2016-06-01

    In this study, we aim to improve the scaling between the moment magnitude ( M W), local magnitude ( M L), and the duration magnitude ( M D) for 162 earthquakes in Shillong-Mikir plateau and its adjoining region of northeast India by extending the M W estimates to lower magnitude earthquakes using spectral analysis of P-waves from vertical component seismograms. The M W- M L and M W- M D relationships are determined by linear regression analysis. It is found that, M W values can be considered consistent with M L and M D, within 0.1 and 0.2 magnitude units respectively, in 90 % of the cases. The scaling relationships investigated comply well with similar relationships in other regions in the world and in other seismogenic areas in the northeast India region.

  8. 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.

  9. Finite element simulation of a local scale air quality model over complex terrain

    NASA Astrophysics Data System (ADS)

    Oliver, A.; Montero, G.; Montenegro, R.; Rodríguez, E.; Escobar, J. M.; Perez-Foguet, A.

    2012-05-01

    In this paper we propose a finite element method approach for modelling the air quality in a local scale over complex terrain. The area of interest is up to tens of kilometres and it includes pollutant sources. The proposed methodology involves the generation of an adaptive tetrahedral mesh, the computation of an ambient wind field, the inclusion of the plume rise effect in the wind field, and the simulation of transport and reaction of pollutants. We apply our methodology to simulate a fictitious pollution episode in La Palma island (Canary Island, Spain).

  10. 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.

  11. Deep-Subwavelength-Scale Directional Sensing Based on Highly Localized Dipolar Mie Resonances

    NASA Astrophysics Data System (ADS)

    Zhu, Xuefeng; Liang, Bin; Kan, Weiwei; Peng, Yugui; Cheng, Jianchun

    2016-05-01

    This paper reports the formation of highly localized Mie resonances on a closed metasurface encapsulating a rigid core and the realization of directional sensing at deep-subwavelength scale (diameter ˜λ /8 ) with the proposed physical model. Based on modal-expansion and mode-matching methods, it is theoretically shown that the extremely anisotropic metasurface shell can support varied orders of Mie resonances around the rigid core. We further experimentally demonstrate that the Mie resonance with a dipolelike profile is strongly excited under the illumination of a plane wave at low frequencies, enabling the sensitive directional sensing due to the intensified and azimuthally dependent pressure field.

  12. A multi-scale non-local means algorithm for image de-noising

    NASA Astrophysics Data System (ADS)

    Nercessian, Shahan; Panetta, Karen A.; Agaian, Sos S.

    2012-06-01

    A highly studied problem in image processing and the field of electrical engineering in general is the recovery of a true signal from its noisy version. Images can be corrupted by noise during their acquisition or transmission stages. As noisy images are visually very poor in quality, and complicate further processing stages of computer vision systems, it is imperative to develop algorithms which effectively remove noise in images. In practice, it is a difficult task to effectively remove the noise while simultaneously retaining the edge structures within the image. Accordingly, many de-noising algorithms have been considered attempt to intelligent smooth the image while still preserving its details. Recently, a non-local means (NLM) de-noising algorithm was introduced, which exploited the redundant nature of images to achieve image de-noising. The algorithm was shown to outperform current de-noising standards, including Gaussian filtering, anisotropic diffusion, total variation minimization, and multi-scale transform coefficient thresholding. However, the NLM algorithm was developed in the spatial domain, and therefore, does not leverage the benefit that multi-scale transforms provide a framework in which signals can be better distinguished by noise. Accordingly, in this paper, a multi-scale NLM (MS-NLM) algorithm is proposed, which combines the advantage of the NLM algorithm and multi-scale image processing techniques. Experimental results via computer simulations illustrate that the MS-NLM algorithm outperforms the NLM, both visually and quantitatively.

  13. The role of local-scale heterogeneities in terrestrial ecosystem modeling

    NASA Astrophysics Data System (ADS)

    Pappas, Christoforos; Fatichi, Simone; Rimkus, Stefan; Burlando, Paolo; Huber, Markus O.

    2015-02-01

    The coarse-grained spatial representation of many terrestrial ecosystem models hampers the importance of local-scale heterogeneities. To address this issue, we combine a range of observations (forest inventories, eddy flux tower data, and remote sensing products) and modeling approaches with contrasting degrees of abstraction. The following models are selected: (i) Lund-Potsdam-Jena (LPJ), a well-established, area-based, dynamic global vegetation model (DGVM); (ii) LPJ-General Ecosystem Simulator, a hybrid, individual-based approach that additionally considers plant population dynamics in greater detail; and (iii) distributed in space-LPJ, a spatially explicit version of LPJ, operating at a fine spatial resolution (100 m × 100 m), which uses an enhanced hydrological representation accounting for lateral connectivity of surface and subsurface water fluxes. By comparing model simulations with a multivariate data set available at the catchment scale, we argue that (i) local environmental and topographic attributes that are often ignored or crudely represented in DGVM applications exert a strong control on terrestrial ecosystem response; (ii) the assumption of steady state vegetation and soil carbon pools at the beginning of simulation studies (e.g., under "current conditions"), as embedded in many DGVM applications, is in contradiction with the current state of many forests that are often out of equilibrium; and (iii) model evaluation against vegetation carbon fluxes does not imply an accurate simulation of vegetation carbon stocks. Having gained insights about the magnitude of aggregation-induced biases due to smoothing of spatial variability at the catchment scale, we discuss the implications of our findings with respect to the global-scale modeling studies of carbon cycle and we illustrate alternative ways forward.

  14. 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

  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. PMID:27003068

  16. 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

  17. Local-scale Partitioning of Functional and Phylogenetic Beta Diversity in a Tropical Tree Assemblage

    PubMed Central

    Yang, Jie; Swenson, Nathan G.; Zhang, Guocheng; Ci, Xiuqin; Cao, Min; Sha, Liqing; Li, Jie; Ferry Slik, J. W.; Lin, Luxiang

    2015-01-01

    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. PMID:26235237

  18. 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

    2015-01-01

    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. PMID:26235237

  19. Recognizing objects in 3D point clouds with multi-scale local features.

    PubMed

    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

  20. Local-scale cross-correlation of seismic noise from the Calico fault experiment

    NASA Astrophysics Data System (ADS)

    Zhang, Jian; Gerstoft, Peter

    2014-06-01

    Most studies of seismic noise cross-correlation (NCC) have focused on regional/continental scale imaging using empirical surface-wave Green's functions extracted from primary (0.05-0.08 Hz) and secondary (0.1-0.16 Hz) microseisms. In this work, we present the NCC results at higher frequencies (>0.5 Hz) from 6 months seismic noise recorded by a local array (~4 km aperture) deployed along the Calico fault in the Mojave Desert, California. Both fast and slow propagating waves are observed from the NCC record-sections. We compare the NCCs from sensor pairs that share a common sensor with the records of a borehole shot located very close to this common sensor. The result shows a good match of the slow surface-wave arrivals, indicating that the NCC method is able to recover unbiased surface-wave Green's functions at local scales. The strong body-wave NCC component is caused by the P waves generated offshore California. Along a SW-NE profile across the fault, we observe apparent P-wave arrivals and their reflections, which can be explained by a low-velocity-zone (LVZ) along the Calico fault. We calculate the LVZ width to be ~ 2.3 km, and the P-wave velocity reduction within the LVZ to be ~35 %. These estimates are consistent with other evidence for a relatively wide LVZ along the Calico fault.

  1. 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.

  2. 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

  3. Surprising Long Range Effects of Local Shoreline Stabilization in a Large-Scale Coastline Model

    NASA Astrophysics Data System (ADS)

    Slott, J.; Murray, B.; Valvo, L.; Ashton, A.

    2004-12-01

    As coastlines continue to retreat and threaten communities, roads, and other infrastructure, humans increasingly employ shoreline stabilization techniques to maintain the shoreline in its current position. Examples of shoreline stabilization techniques include beach nourishment and seawall construction. During beach nourishment, sand is typically dredged from locations offshore and placed on the beach. Seawalls or revetments, on the other hand, are hardened concrete structures which prevent the shoreline from retreating further yet do not add sand to the nearshore system. Coastal engineers and scientists have only addressed the local and relatively short-term effects of shoreline stabilization. Can beach nourishment or seawalls affect coastline behavior tens or hundreds of kilometers away in the longer term? We adapted a recently developed model of large-scale, long-term shoreline change to address such questions. On predominately sandy shorelines, waves breaking at oblique angles to the shoreline orientation drives the alongshore transport of sediment. Though traditionally believed to smooth out shoreline features, Ashton, et. al. (2001) have shown that alongshore-driven sediment transport can cause more complex shoreline evolution. Their model showed the spontaneous formation of large-scale features such as capes and cuspate forelands (e.g. the shape of the coastline of the Carolinas) using simple sediment transport relationships. This model accounts for non-local shoreline interactions, such as wave "shadowing." In this work, we have further developed the large-scale shoreline model to include the effects that shoreline stabilization techniques have on shoreline position and sediment supply. In one set of experiments, we chose an initial shoreline with cape-like features separated by approximately 100 kilometers, roughly similar to that of the coast off the Carolinas. In each individual experiment, we nourished a different 10 kilometer section of coastline. In

  4. The effect of local and large-scale environments on nuclear activity and star formation

    NASA Astrophysics Data System (ADS)

    Argudo-Fernández, M.; Shen, S.; Sabater, J.; Duarte Puertas, S.; Verley, S.; Yang, X.

    2016-07-01

    Context. Active galactic nuclei (AGN) are one of the main drivers for the transition from star-forming disk to passive spheroidal galaxies, however, the role of large-scale environment versus one-on-one interactions in triggering different types of AGN is still uncertain. We present a statistical study of the prevalence of the nuclear activity in isolated galaxies and physically bound isolated pairs. Aims: For the purpose of this study we considered optically and radio selected nuclear activity types. We aim to assess the effect of one-on-one interaction on the fraction of AGN and the role of their large-scale environment. Methods: To study the effect of one-on-one interaction on the fraction of AGN in isolated galaxy pairs, we compare these AGN with a sample of isolated galaxies homogeneously selected under the same isolation criterion. We examine the effect of the large-scale environment by comparing isolated systems with control samples of single galaxies and galaxy pairs. We use the tidal strength parameter to quantify the effects of local and large-scale environments. Results: In general we found no difference in the prevalence of optical AGN for the considered samples. For massive galaxies, the fraction of optical AGN in isolated galaxies is slightly higher than that in the control samples. Also, the fraction of passives in high mass isolated galaxies is smaller than in any other sample. Generally, there is no dependence on optical nuclear activity with local environment. On the other hand, we found evidence that radio AGN are strongly affected by the local environment. Conclusions: The optical AGN phenomenon is related to cold gas accretion, while radio AGN are related to hot gas accretion. In this context, there is more cold gas, fuelling the central optical AGN, in isolated systems. Our results are in agreement with a scenario where cold gas accretion by secular evolution is the main driver of optical AGN, while hot gas accretion and one

  5. 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

  6. A portable spectrometer for use from 5 to 15 micrometers

    NASA Technical Reports Server (NTRS)

    Hoover, G.; Kahle, A. B.

    1986-01-01

    A field portable spectrometer suitable for collecting data relevant to remote sensing applications in the 8 to 12 micrometer atmospheric window has been built at the Jet Propulsion Laboratory. The instrument employs a single cooled HgCdTe detector and a continuously variable filter wheel analyzer. The spectral range covered is 5 to 14.5 micrometers and the resolution is approximately 1.5 percent of the wavelength. A description of the hardware is followed by a discussion of the analysis of the spectral data leading to finished emissivity and radiance spectra. A section is devoted to the evaluation of the instrument performance with respect to spectral resolution, radiometric precision, and accuracy. Several examples of spectra acquired in the field are included.

  7. 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

  8. 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.

  9. 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

  10. 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.

  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. 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.

  13. X-Ray tomography with micrometer spatial resolution

    NASA Astrophysics Data System (ADS)

    Raven, Carsten; Snigirev, Anatoly A.; Koch, Andreas; Snigireva, Irina; Kohn, Victor

    1997-10-01

    3D computed tomographic images with micrometer resolution were made in phase-contrast mode with high energy x-rays at a third generation synchrotron source. The phase-contrast technique enables one to obtain information not only about the amplitude of the wave field behind the object and thus about the absorption, but also about the refractive index distribution inside the sample. Increasing the x-ray energy from the soft x-ray region up to 10-60 keV simplifies the experimental setup and opens the possibility to study organic samples at room-temperature and under normal pressure conditions. The projection data is recorded with a fast, high-resolution x-ray camera consisting of a 5 micrometers thin YAG scintillator crystal, a visible light microscope optics and a slow scan 1k X 1k CCD camera. The spatial resolution of phase-contrast microtomography is currently limited by the resolution of the x-ray detector to about 1-2 micrometers . First applications in biology and geophysics are shown.

  14. Condensation on superhydrophobic surfaces: the role of local energy barriers and structure length scale.

    PubMed

    Enright, Ryan; Miljkovic, Nenad; Al-Obeidi, Ahmed; Thompson, Carl V; Wang, Evelyn N

    2012-10-01

    Water condensation on surfaces is a ubiquitous phase-change process that plays a crucial role in nature and across a range of industrial applications, including energy production, desalination, and environmental control. Nanotechnology has created opportunities to manipulate this process through the precise control of surface structure and chemistry, thus enabling the biomimicry of natural surfaces, such as the leaves of certain plant species, to realize superhydrophobic condensation. However, this "bottom-up" wetting process is inadequately described using typical global thermodynamic analyses and remains poorly understood. In this work, we elucidate, through imaging experiments on surfaces with structure length scales ranging from 100 nm to 10 μm and wetting physics, how local energy barriers are essential to understand non-equilibrium condensed droplet morphologies and demonstrate that overcoming these barriers via nucleation-mediated droplet-droplet interactions leads to the emergence of wetting states not predicted by scale-invariant global thermodynamic analysis. This mechanistic understanding offers insight into the role of surface-structure length scale, provides a quantitative basis for designing surfaces optimized for condensation in engineered systems, and promises insight into ice formation on surfaces that initiates with the condensation of subcooled water. PMID:22931378

  15. 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.

  16. 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. PMID:25314498

  17. 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

  18. 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

  19. 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

  20. 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.

  1. Sub-micrometer precision of optical imaging to locate the free surface of a micrometer fluid shape.

    PubMed

    Montanero, J M; Vega, E J; Ferrera, C

    2009-11-01

    In this note, we explore the precision of the optical imaging method for measuring the free surface position of a micrometer fluid shape. For this purpose, images of a liquid film deposited on a rod were acquired and processed. The resulting contour was compared with the corresponding solution to the Young-Laplace equation. The average deviation was about 30nm, 25 times smaller than the pixel size, reflecting the validity of optical imaging for most applications in microfluidics. PMID:19683246

  2. Emergence of Large-Scale Cell Morphology and Movement from Local Actin Filament Growth Dynamics

    PubMed Central

    Lacayo, Catherine I; Pincus, Zachary; VanDuijn, Martijn M; Wilson, Cyrus A; Fletcher, Daniel A; Gertler, Frank B; Mogilner, Alex; Theriot, Julie A

    2007-01-01

    Variations in cell migration and morphology are consequences of changes in underlying cytoskeletal organization and dynamics. We investigated how these large-scale cellular events emerge as direct consequences of small-scale cytoskeletal molecular activities. Because the properties of the actin cytoskeleton can be modulated by actin-remodeling proteins, we quantitatively examined how one such family of proteins, enabled/vasodilator-stimulated phosphoprotein (Ena/VASP), affects the migration and morphology of epithelial fish keratocytes. Keratocytes generally migrate persistently while exhibiting a characteristic smooth-edged “canoe” shape, but may also exhibit less regular morphologies and less persistent movement. When we observed that the smooth-edged canoe keratocyte morphology correlated with enrichment of Ena/VASP at the leading edge, we mislocalized and overexpressed Ena/VASP proteins and found that this led to changes in the morphology and movement persistence of cells within a population. Thus, local changes in actin filament dynamics due to Ena/VASP activity directly caused changes in cell morphology, which is coupled to the motile behavior of keratocytes. We also characterized the range of natural cell-to-cell variation within a population by using measurable morphological and behavioral features—cell shape, leading-edge shape, filamentous actin (F-actin) distribution, cell speed, and directional persistence—that we have found to correlate with each other to describe a spectrum of coordinated phenotypes based on Ena/VASP enrichment at the leading edge. This spectrum stretched from smooth-edged, canoe-shaped keratocytes—which had VASP highly enriched at their leading edges and migrated fast with straight trajectories—to more irregular, rounder cells migrating slower with less directional persistence and low levels of VASP at their leading edges. We developed a mathematical model that accounts for these coordinated cell-shape and behavior

  3. 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

  4. 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

  5. Local convergence of collinear scaling algorithms related to direct least-change secant update methods for minimization

    NASA Astrophysics Data System (ADS)

    Ariyawansa, K. A.

    1998-01-01

    Collinear scaling algorithms related to direct fixed-scale and rescaled least-change secant update methods for unconstrained minimization are derived. Theorems on local and q-superlinear convergence of these algorithms are presented. These results are extensions of those of Dennis and Walker [14] for direct least-change secant update methods.

  6. Observation of multi-scale turbulence and non-local transport in LHD plasmas

    SciTech Connect

    Tokuzawa, T.; Inagaki, S.; Ida, K.; Itoh, K.; Ido, T.; Shimizu, A.; Takahashi, H.; Tamura, N.; Yoshinuma, M.; Tsuchiya, H.; Yamada, I.; Tanaka, K.; Akiyama, T.; Nagayama, Y.; Kawahata, K.; Watanabe, K. Y.; Yamada, H.; Kitajima, S.

    2014-05-15

    We have studied two types of spatio-temporal turbulence dynamics in plasmas in the Large Helical Device, based on turbulence measurements with high spatial and temporal resolution. Applying conditional ensemble-averaging to a plasma with Edge-Localized Modes (ELMs), fast radial inward propagation of a micro-scale turbulence front is observed just after ELM event, and the propagation speed is evaluated as ∼100 m/s. A self-organized radial electric field structure is observed in an electrode biasing experiment, and it is found to realize a multi-valued state. The curvature of the radial electric field is found to play an important role for turbulence reduction.

  7. Observation of multi-scale turbulence and non-local transport in LHD plasmasa)

    NASA Astrophysics Data System (ADS)

    Tokuzawa, T.; Inagaki, S.; Ida, K.; Itoh, K.; Ido, T.; Shimizu, A.; Takahashi, H.; Kitajima, S.; Tamura, N.; Yoshinuma, M.; Tsuchiya, H.; Yamada, I.; Tanaka, K.; Akiyama, T.; Nagayama, Y.; Kawahata, K.; Watanabe, K. Y.; Yamada, H.

    2014-05-01

    We have studied two types of spatio-temporal turbulence dynamics in plasmas in the Large Helical Device, based on turbulence measurements with high spatial and temporal resolution. Applying conditional ensemble-averaging to a plasma with Edge-Localized Modes (ELMs), fast radial inward propagation of a micro-scale turbulence front is observed just after ELM event, and the propagation speed is evaluated as ˜100 m/s. A self-organized radial electric field structure is observed in an electrode biasing experiment, and it is found to realize a multi-valued state. The curvature of the radial electric field is found to play an important role for turbulence reduction.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. Fuzzy overlapping community detection based on local random walk and multidimensional scaling

    NASA Astrophysics Data System (ADS)

    Wang, Wenjun; Liu, Dong; Liu, Xiao; Pan, Lin

    2013-12-01

    A fuzzy overlapping community is an important kind of overlapping community in which each node belongs to each community to different extents. It exists in many real networks but how to identify a fuzzy overlapping community is still a challenging task. In this work, the concept of local random walk and a new distance metric are introduced. Based on the new distance measurement, the dissimilarity index between each node of a network is calculated firstly. Then in order to keep the original node distance as much as possible, the network structure is mapped into low-dimensional space by the multidimensional scaling (MDS). Finally, the fuzzy c-means clustering is employed to find fuzzy communities in a network. The experimental results show that the proposed algorithm is effective and efficient to identify the fuzzy overlapping communities in both artificial networks and real-world networks.

  13. 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

  14. ELPIS-JP: a dataset of local-scale daily climate change scenarios for Japan.

    PubMed

    Iizumi, Toshichika; Semenov, Mikhail A; Nishimori, Motoki; Ishigooka, Yasushi; Kuwagata, Tsuneo

    2012-03-13

    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

  15. 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

  16. Applying Bayesian Maximum Entropy to extrapolating local-scale water consumption in Maricopa County, Arizona

    NASA Astrophysics Data System (ADS)

    Lee, Seung-Jae; Wentz, Elizabeth A.

    2008-01-01

    Understanding water use in the context of urban growth and climate variability requires an accurate representation of regional water use. It is challenging, however, because water use data are often unavailable, and when they are available, they are geographically aggregated to protect the identity of individuals. The present paper aims to map local-scale estimates of water use in Maricopa County, Arizona, on the basis of data aggregated to census tracts and measured only in the City of Phoenix. To complete our research goals we describe two types of data uncertainty sources (i.e., extrapolation and downscaling processes) and then generate data that account for the uncertainty sources (i.e., soft data). Our results ascertain that the Bayesian Maximum Entropy (BME) mapping method of modern geostatistics is a theoretically sound approach for assimilating the soft data into mapping processes. Our results lead to increased mapping accuracy over classical geostatistics, which does not account for the soft data. The confirmed BME maps therefore provide useful knowledge on local water use variability in the whole county that is further applied to the understanding of causal factors of urban water demand.

  17. Local-global interaction and the emergence of scale-free networks with community structures.

    PubMed

    Liu, Jing; Abbass, Hussein A; Zhong, Weicai; Green, David G

    2011-01-01

    Understanding complex networks in the real world is a nontrivial task. In the study of community structures we normally encounter several examples of these networks, which makes any statistical inferencing a challenging endeavor. Researchers resort to computer-generated networks that resemble networks encountered in the real world as a means to generate many networks with different sizes, while maintaining the real-world characteristics of interest. The generation of networks that resemble the real world turns out in itself to be a complex search problem. We present a new rewiring algorithm for the generation of networks with unique characteristics that combine the scale-free effects and community structures encountered in the real world. The algorithm is inspired by social interactions in the real world, whereby people tend to connect locally while occasionally they connect globally. This local-global coupling turns out to be a powerful characteristics that is required for our proposed rewiring algorithm to generate networks with community structures, power law distributions both in degree and in community size, positive assortative mixing by degree, and the rich-club phenomenon. PMID:21762023

  18. Source parameters and scaling relations for local earthquakes in the Pannonian basin

    NASA Astrophysics Data System (ADS)

    Süle, Bálint; Wéber, Zoltán

    2014-05-01

    Source parameters have been estimated for 74 local earthquakes (0.8 < ML < 4.5) occurred in Hungary (central part of Pannonian basin) in the period of 1995-2011. Fourier displacement spectra of P- and SH- waves were analysed with respect to the ω2 model of Brune. Observed spectra were corrected for path-dependent attenuation effects using an independent regional estimate of the quality factor QS. To correct spectra for near-surface attenuation, the κ parameter was calculated, obtaining it from waveforms recorded at short epicentral distances. The values of the κ parameter vary between 0.01 to 0.06 s with a mean of 0.03 s for P-waves and between 0.01 to 0.09 s with a mean of 0.04 s for SH-waves. After correction for attenuation effects, spectral parameters (corner frequency and low-frequency spectral level) were estimated by a grid search algorithm. The obtained seismic moments range from 1.34 × 1011 to 3.68 × 1015 Nm (1.5 ≤ Mw ≤ 4.3). The source radii are between 115 and 1343 and stress drop spans from 0.14 to 32.4 bars. From the results, a linear relationship between local and moment magnitudes has been established. The obtained scaling relations show slight evidence of self-similarity violation. However, due to the high scatter of our data, the existence of self-similarity cannot be excluded.

  19. 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. PMID:26357377

  20. 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

  1. 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

  2. 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. PMID:27102088

  3. 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

    2016-03-17

    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 governs the strength of the assembly as predicted by the shear-lag model. The intermediate critical length L 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 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. PMID:26935048

  4. Local-scale variability in regional air quality modelling: Implications on temporal distribution of emissions

    NASA Astrophysics Data System (ADS)

    Bergemann, Christoph; Meyer-Arnek, Julian

    2010-05-01

    In the field of air quality modeling, the comparison of model results with ground-based measurements is essential for validation purposes. The usefulness of these measurements for regional air quality modeling is however limited by the extremely local nature of station measurements. This is especially true for short-lived species like NO2, which is of high importance for public health. Nevertheless station observations are the only continuously available source of data on ground level air quality besides model results. Uncertainties in air quality models mainly arise from the lack of precise knowledge of the spatial and temporal distribution of pollutants. Most emission inventories provide aggregated values for long periods of time and yield no information on the temporal (diurnal) distribution of emissions. By applying ground-based measurements, our study yields optimized diurnal variations of anthropogenic emissions for different urban regions of Germany. In the course of the study the variability of air pollution on the urban scale (the model's subgrid scale) is also addressed. The study applies the newly established POLYPHEMUS/DLR model at a moderate resolution. In the framework of the GMES project "PROMOTE", this model system operationally analyzes and forecasts air quality in Bavaria, Germany. The model employs the latest version of the EMEP emission register in combination with high-resolution emission data provided by Bavarian authorities.

  5. 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

  6. 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.

  7. Floral resources and habitat affect the composition of hummingbirds at the local scale in tropical mountaintops.

    PubMed

    Rodrigues, L C; Rodrigues, M

    2015-01-01

    Hummingbird communities tend to respond to variation in resources, having a positive relationship between abundance and diversity of food resources and the abundance and/or diversity of hummingbirds. Here we examined the influence of floral resource availability, as well as seasonality and type of habitat on the composition of hummingbird species. The study was carried out in two habitats of eastern Brazilian mountaintops. A gradient representative of the structure of hummingbird community, based on species composition, was obtained by the ordination of samples using the method of non-metric multidimensional scaling. The composition of hummingbird species was influenced by the type of habitat and floral resource availability, but not by seasonality. Hummingbird communities differ between habitats mainly due to the relative abundance of hummingbird species. The variation in composition of hummingbird species with the variation in floral resource availability may be related to differences in feeding habits of hummingbirds. Hummingbird species with the longest bills visited higher proportions of ornithophilous species, while hummingbirds with shorter bills visited higher proportions of non-ornithophilous species. The results demonstrate that at local-scale the composition of hummingbird species is affected by the type of habitat and floral resources availability, but not by seasonality. PMID:25945619

  8. 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.

  9. Biogeographic affinity helps explain productivity-richness relationships at regional and local scales.

    PubMed

    Harrison, Susan; Grace, James B

    2007-08-01

    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. PMID:17874384

  10. 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.

  11. 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.

  12. 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

  13. 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).

  14. 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

  15. Local and large-scale influences on Swiss temperature trends 1959-2008

    NASA Astrophysics Data System (ADS)

    Ceppi, P.; Scherrer, S. C.; Fischer, A.; Appenzeller, C.

    2010-09-01

    Temperature is a key variable for monitoring global climate change. Here we perform a trend analysis of Swiss temperatures from 1959-2008, using a new 2x2 km gridded data set based on carefully homogenized ground observations from MeteoSwiss. The aim of this study is twofold: first, to discuss the spatial and altitudinal temperature trend characteristics in detail and second, to quantify the contribution of global, large-scale and local-scale effects to these trends. The seasonal trends are all positive and mostly significant with an annual average warming rate of 0.35°C/decade (~1.6 times the global warming rate), ranging from 0.17 in autumn to 0.48°C/decade in summer. Altitude-dependent trends are found in autumn and early winter where the trends are stronger at low altitudes (<800 m asl), and in spring where slightly stronger trends are found at altitudes close to the snow line. The corresponding seasonal trends from the ENSEMBLES project regional climate models are weaker (~0.2°C/decade for all seasons) and show somewhat different patterns of altitude dependence. A large fraction of the trends can be explained by fluctuations in atmospheric circulation patterns, but with substantial differences from season to season. In winter, the magnitude and vertical distribution of the trends are reproduced accurately using large-scale and regional circulation dynamics effects only, while ~30-45% of the trends remain unexplained in spring and summer. In autumn, the mean trend is roughly reproduced but the altitudinal differences remain unexplained. This suggests that local effects are important to explain part of recent temperature trends in spring, summer and autumn. Snow-albedo feedback effects could be responsible for the 5-10% higher spring trends at altitudes close to the snow line. In autumn, the observed decrease in fog frequency might be a key process in explaining the stronger temperature trends at low altitudes.

  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. Toward Unraveling the Nature of the Mysterious 21 and 30 Micrometer Emission Features of Evolved Stars

    NASA Astrophysics Data System (ADS)

    Mishra, Ajay; Li, A.

    2014-01-01

    The mysterious "21 micrometer" emission feature seen almost exclusively in the short-lived protoplanetary nebula (PPN) phase of stellar evolution remains unidentified since its discovery two decades ago. This feature is always accompanied by the equally mysterious, unidentified "30 micrometer" feature and the so-called “unidentified infrared” (UIR) features generally attributed to polycyclic aromatic hydrocarbon (PAH) molecules. The 30 micrometer feature is commonly observed in all stages of stellar evolution from the asymptotic giant branch (AGB) through PPN to the planetary nebula phase. We explore the interrelations among the mysterious 21 micrometer, 30 micrometer, and UIR features in the Galactic and Magellanic Cloud 21 micrometer sources. We derive the fluxes emitted in the observed UIR, 21 micrometer, and 30 micrometer features from published ISO or Spitzer/IRS spectra. To derive the stellar mass loss rates of these 21 micrometer sources, we use the 2-dust radiative transfer code for axisymmetric dusty systems to model their dust infrared emission. We found that --- (1) The 30 micrometer feature does not seem to positively correlate with the 21 micrometer feature. This argues against the hypothesis of thiourea and aliphatic chains (attached to various carbonaceous structures) as the common carriers for both the 21 and 30 micrometer features; (2) The 21 micrometer feature does not correlate with the UIR features. This argues against large PAH clusters as a possible carrier for the 21 micrometer feature. (3) The 30 micrometer feature and the UIR features appear to weakly correlate, suggesting that the UIR carriers (e.g. PAHs) may result from the decomposition or shattering of the 30 micrometer feature carrier; and (4) The 21 micrometer feature and UIR features seem to weakly correlate with the stellar mass loss rates while the 30 micrometer feature appears to weakly anti-correlate with the stellar mass loss rates, suggesting that the UIR and 21 micrometer

  18. 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

  19. 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

  20. 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

  1. 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

  2. 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

  3. 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

  4. Rounbletz: An Excel-based software to perform cost-benefit analysis at local scale

    NASA Astrophysics Data System (ADS)

    Nicolet, Pierrick; Jaboyedoff, Michel; Lévy, Sébastien

    2014-05-01

    Public financial support for natural hazard protection measure is generally attributed, in Switzerland, according to the results of cost-benefit analysis. The analysis is generally made with a very controlled procedure, where many parameters are predefined according to a few input parameters. Vulnerability is, for example, defined according to the building's type and the hazard's type and intensity (divided in 4 classes). Therefore, this procedure, although having the advantage of being reproducible, suffers from a lack of ability to describe the local specificities. This work describes an Excel-based application which allows to calculate the cost-benefit analysis at local scale, based on the usual 3 scenarios and the predefined intensities used in Switzerland. Although the risk equations are not new, this study focuses on finding the right balance between a rigid but reproducible, and a free but too much user-dependent approach. Many parameters value are therefore predefined, but are displayed and can be modified by the user if needed. If these predefined parameters are modified, the program highlights them in the output in order to be transparent for the person who will take a decision based on these results. The software is multi-hazard, but is not yet designed to account for the possible hazards interactions. A preliminary attempt to include the uncertainty in the calculation is also presented. The uncertainty analysis consists of using triangular distributions for the input parameters and performing a Monte-Carlo simulation to obtain a distribution of possible values. The triangular distribution is chosen because of its simplicity, which is a desirable characteristic since the specialist assessing the risk is most of the time more comfortable with the natural phenomenon than with probabilities. Thus, since this type of analysis always suffers from a high uncertainty, this simple procedure allows taking this uncertainty into account for the decision process.

  5. Hydroclimatic Changes in Land Water and their Drivers from Local-Regional to Global Scales

    NASA Astrophysics Data System (ADS)

    Jaramillo, F.; Destouni, G.

    2013-12-01

    Past and current climate change in the atmosphere (in temperature T and precipitation P), hydroclimatic changes in the water on land (in runoff R and evapotranspiration ET) and their links to each other and to other possible changes on land, need to be studied and understood in order to realistically assess how forthcoming changes may affect freshwater resources and to plan for relevant adaptation to these changes. Here we use openly available data for T, P and R development from the beginning of the 20th century until present time in 1750 catchments spread over all continents. The aim is to assess hydroclimatic changes, and the links among atmospheric climate change, land use and water use change (LUWUC), and water changes on land between two time periods; before the occurrence of major LUWUC (1901-1950) and during main occurrences and intensifications of LUWUC (1961-2009). In particular, we evaluate changes in ET and in the short-term, intra-annual variability (in terms of the coefficients of variation) of P and R (CV(P) and CV(R), respectively), aiming to distinguish LUWUC effects from atmospheric climate change on these hydroclimatic changes. By evaluating the change links across global, hemispheric, continental and local-regional catchment scales, we identify dominant influences of local-regional LUWUC on the hydroclimatic changes in land water. These influences include a) different types of partitioning of given P changes into ET and R changes in different regions of the world and b) changes to runoff variability, of which atmospheric climate change was not the main driver. The results of this study point to the necessity of considering and accounting for the impacts of LUWUC in assessments of present and future hydroclimatic changes on land.

  6. 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.

  7. Microfabricated High-Moment Micrometer-sized MRI Contrast Agents

    PubMed Central

    Zabow, Gary; Dodd, Stephen J.; Shapiro, Erik; Moreland, John; Koretsky, Alan P.

    2010-01-01

    While chemically synthesized superparamagnetic microparticles have enabled much new research based on MRI-tracking of magnetically labeled cells, signal-to-noise levels still limit the potential range of applications. Here it is shown how, through top-down microfabrication, contrast agent relaxivity can be increased several-fold, which should extend the sensitivity of such cell tracking studies. Microfabricated agents can benefit from both higher magnetic moments and higher uniformity than their chemically synthesized counterparts, implying increased label visibility and more quantitative image analyses. To assess the performance of microfabricated micrometer-sized contrast agent particles, analytic models and numerical simulations are developed and tested against new microfabricated agents described in this paper, as well as against results of previous imaging studies of traditional chemically synthesized microparticle agents. Experimental data showing signal effects of 500-nanometer thick, 2-micrometer diameter, gold-coated iron and gold-coated nickel disks verify the simulations. Additionally, it is suggested that measures of location better than the pixel resolution can be obtained and that these are aided using well-defined contrast agent particles achievable through microfabrication techniques. PMID:20928829

  8. Possible identifications of the 3.4 micrometer feature

    NASA Technical Reports Server (NTRS)

    Danks, Anthony C.; Lambert, D. L.

    1988-01-01

    A feature at 3.4 micrometer was first detected in Comet Halley by the IKS spectrometer on board the Vega 1 probe; and subsequently from the ground. The feature has since been reported in Comet Wilson. The presence of the feature is of considerable interest for a number of reasons. First, it may represent the detection of a new parent molecule, and when combined with data from Giotto and Vega yield new information on cometary chemistry and the early solar system composition. Secondly, it may represent a link to the interstellar medium, the feature corresponds in wavelength and shape with an interstellar feature seen in absorption in a luminous star, towards the Galactic center known as GC-IRS7. The feature in turn is thought to be related with a growing family of unidentified infrared emission features seen in stellar objects, planetary nebulae, reflection nebulae, HII regions and extra galactic sources. These features occur at wavelengths 3.3, 3.4, 3.5, 6.2, 7.7, 8.6, and 11.25 micrometers. Further identification theory is given.

  9. 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.

  10. 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

  11. Promoting Climate Literacy through Collaborative Temperature Investigations at Local, Regional, and Global Scales

    NASA Astrophysics Data System (ADS)

    Geary, E. E.; Charlevoix, D.; Hoffman, M.

    2009-12-01

    One of the fundamental challenges in promoting student and citizen climate literacy is developing awareness and understanding of the time and spatial scales on which climate changes occur. Students and citizens living in polar regions are now able to observe changes in sea ice extent, permafrost depth, and local ecosystems that have occurred in their lifetimes. In other parts of the world, environmental changes related to climate tend to be more subtle making it more challenging for students and citizens to recognize how changes in climate are affecting their communities. The GLOBE program, an international science and education program operating in 110 countries, implements field-based research and education programs that directly involve students and citizens in observations of their local environment as well as online collaboration using Web 2.0 communication tools to share and discuss how their research findings compare to other environments around the world. In fall 2009, secondary students from several GLOBE schools from around the world will use the GLOBE Minimum-Maximum Temperature protocol to determine daily and monthly average mean air temperatures. Students will collect data in a manner identical to that used by scientists who contributed to the International Panel on Climate Change reports. Students will then use historic weather and climate data from nearby global weather stations to create baseline weather and climate profiles for their communities. Students will use FieldScope, an online GIS tool created by the National Geographic Society to compare their data to temperature trends in their regions for the past 30 to 50 years. Students will share the results of their local temperature investigations with other participating schools via a live Webinar and through asynchronous Web-based conversations held in conjunction with the annual meeting of the Group on Earth Observations. Students participating in this “Great Global Investigation of

  12. The far-infrared emitting region in local galaxies and QSOs: Size and scaling relations

    NASA Astrophysics Data System (ADS)

    Lutz, D.; Berta, S.; Contursi, A.; Förster Schreiber, N. M.; Genzel, R.; Graciá-Carpio, J.; Herrera-Camus, R.; Netzer, H.; Sturm, E.; Tacconi, L. J.; Tadaki, K.; Veilleux, S.

    2016-06-01

    We use Herschel 70 to 160 μm images to study the size of the far-infrared emitting region in about 400 local galaxies and quasar (QSO) hosts. The sample includes normal "main-sequence" star-forming galaxies, as well as infrared luminous galaxies and Palomar-Green QSOs, with different levels and structures of star formation. Assuming Gaussian spatial distribution of the far-infrared (FIR) emission, the excellent stability of the Herschel point spread function (PSF) enables us to measure sizes well below the PSF width, by subtracting widths in quadrature. We derive scalings of FIR size and surface brightness of local galaxies with FIR luminosity, with distance from the star-forming main-sequence, and with FIR color. Luminosities LFIR~ 1011 L⊙ can be reached with a variety of structures spanning 2 dex in size. Ultraluminous LFIR≳ 1012 L⊙ galaxies far above the main-sequence inevitably have small Re,70~ 0.5 kpc FIR emitting regions with large surface brightness, and can be close to optically thick in the FIR on average over these regions. Compared to these local relations, first ALMA sizes for the dust emission regions in high redshift galaxies, measured at somewhat longer rest wavelengths, suggest larger sizes at the same IR luminosity. We report a remarkably tight relation with 0.15 dex scatter between FIR surface brightness and the ratio of [Cii] 158 μm emission and FIR emission - the so-called [Cii]-deficit is more tightly linked to surface brightness than to FIR luminosity or FIR color. Among 33 z ≤ 0.1 PG QSOs with typical LFIR/LBol,AGN ≈ 0.1, 19 have a measured 70 μm half light radius, with median Re,70 = 1.1 kpc. This is consistent with the FIR size for galaxies with similar LFIR but lacking a QSO, in accordance with a scenario where the rest FIR emission of these types of QSOs is, in most cases, due to host star formation.

  13. 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

  14. 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

  15. 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

  16. 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

  17. A framework for investigating large-scale patterns as an alternative to precipitation for downscaling to local drought

    NASA Astrophysics Data System (ADS)

    Towler, Erin; PaiMazumder, Debasish; Holland, Greg

    2016-04-01

    Global Climate Model (GCM) projections suggest that drought will increase across large areas of the globe, but lack skill at simulating climate variations at local-scales where adaptation decisions are made. As such, GCMs are often downscaled using statistical methods. This study develops a 3-step framework to assess the use of large-scale environmental patterns to assess local precipitation in statistically downscaling to local drought. In Step 1, two statistical downscaling models are developed: one based on temperature and precipitation and another based on temperature and a large-scale predictor that serves as a proxy for precipitation. A key component is identifying the large-scale predictor, which is customized for the location of interest. In Step 2, the statistical models are evaluated using NCEP/NCAR Reanalysis data. In Step 3, we apply a large ensemble of future GCM projections to the statistical models. The technique is demonstrated for predicting drought, as measured by the Palmer Drought Severity Index, in South-central Oklahoma, but the framework is general and applicable to other locations. Case study results using the Reanalysis show that the large-scale predictor explains slightly more variance than precipitation when predicting local drought. Applying future GCM projections to both statistical models indicates similar drying trends, but demonstrates notable internal variability. The case study demonstrates: (1) where a large-scale predictor performs comparably (or better) than precipitation directly, then it is an appealing predictor choice to use with future projections, (2) when statistically downscaling to local scales, it is critical to consider internal variability, as it may be more important than predictor selection.

  18. Interaction envelope: Local spatial representations of objects at all scales in scene-selective regions

    PubMed Central

    Bainbridge, Wilma Alice; Oliva, Aude

    2015-01-01

    While several cortical regions have been highlighted for their category selectivity (e.g., scene-selective regions like the parahippocampal place area, object selective regions like the lateral occipital complex), a growing trend in cognitive neuroscience has been to investigate what particular perceptual properties these regions calculate. Classical scene-selective regions have been particularly targeted in recent work as being sensitive to object size or other related properties. Here we test to which extent these regions are sensitive to spatial information of stimuli at any size. We introduce the spatial object property of “interaction envelope,” defined as the space through which a user trans-verses to interact with an object. In two functional magnetic resonance imaging experiments, we examined activity in a comprehensive set of perceptual regions of interest for when human participants viewed object images varying along the dimensions of interaction envelope and physical size. Importantly, we controlled for confounding perceptual and semantic object properties. We find that scene-selective regions are in fact sensitive to object interaction envelope for small, manipulable objects regardless of real-world size and task. Meanwhile, small-scale entity regions maintain selectivity to stimulus physical size. These results indicate that regions traditionally associated with scene processing may not be solely sensitive to larger object and scene information, but instead are calculating local spatial information of objects and scenes of all sizes. PMID:26236029

  19. Identifying local-scale wilderness for on-ground conservation actions within a global biodiversity hotspot

    NASA Astrophysics Data System (ADS)

    Lin, Shiwei; Wu, Ruidong; Hua, Chaolang; Ma, Jianzhong; Wang, Wenli; Yang, Feiling; Wang, Junjun

    2016-05-01

    Protecting wilderness areas (WAs) is a crucial proactive approach to sustain biodiversity. However, studies identifying local-scale WAs for on-ground conservation efforts are still very limited. This paper investigated the spatial patterns of wilderness in a global biodiversity hotspot – Three Parallel Rivers Region (TPRR) in southwest China. Wilderness was classified into levels 1 to 10 based on a cluster analysis of five indicators, namely human population density, naturalness, fragmentation, remoteness, and ruggedness. Only patches characterized by wilderness level 1 and ≥1.0 km2 were considered WAs. The wilderness levels in the northwest were significantly higher than those in the southeast, and clearly increased with the increase in elevation. The WAs covered approximately 25% of TPRR’s land, 89.3% of which was located in the >3,000 m elevation zones. WAs consisted of 20 vegetation types, among which temperate conifer forest, cold temperate shrub and alpine ecosystems covered 79.4% of WAs’ total area. Most WAs were still not protected yet by existing reserves. Topography and human activities are the primary influencing factors on the spatial patterns of wilderness. We suggest establishing strictly protected reserves for most large WAs, while some sustainable management approaches might be more optimal solutions for many highly fragmented small WAs.

  20. Performance of the chemical mass balance model with simulated local-scale aerosols

    NASA Astrophysics Data System (ADS)

    Javitz, H. S.; Watson, J. G.; Robinson, N.

    A general methodology for performing simulations of the Chemical Mass Balance (CMB) model is developed and applied to simple and complex local scale scenarios. The simple scenario consists of crustal, coal-fired power plant, motor vehicle and vegetative burning sources; the complex scenario adds oil-fired power plant, ocean, steel mill, lead smelter, municipal incinerator and background aerosol sources. Daily receptor filter concentrations of the most commonly measured elements in the primary emissions are simulated. These simulations incorporate daily fluctuations in source strengths, daily fluctuations in source profiles (as parameterized by a coefficient of variation, or CV, of temporal source profiles) and measurement error at the receptor (as parameterized by a CV of measurement error). The CMB is applied to each daily measurement using a source library containing all sources and their long-term profiles (which, though correct on average, are incorrect on any particular day). The extent of agreement of the actual and CMBestimated primary emission source strengths is measured as an average absolute error (AAE, the absolute difference between the daily actual and estimated primary emission source strengths averaged over 100 simulated days). These moderately realistic simulations provide an encouraging picture of CMB accuracy and precision. The CMB yields acceptable accuracy and precision (an AAE of 50% or less) even when the CV of temporal source profiles is 25% and the CV of measurement error is 10%.

  1. The local environment determines the assembly of root endophytic fungi at a continental scale.

    PubMed

    Glynou, Kyriaki; Ali, Tahir; Buch, Ann-Katrin; Haghi Kia, Sevda; Ploch, Sebastian; Xia, Xiaojuan; Çelik, Ali; Thines, Marco; Maciá-Vicente, Jose G

    2016-09-01

    Root endophytic fungi are found in a great variety of plants and ecosystems, but the ecological drivers of their biogeographic distribution are poorly understood. Here, we investigate the occurrence of root endophytes in the non-mycorrhizal plant genus Microthlaspi, and the effect of environmental factors and geographic distance in structuring their communities at a continental scale. We sampled 52 plant populations across the northern Mediterranean and central Europe and used a cultivation approach to study their endophytic communities. Cultivation of roots yielded 2601 isolates, which were grouped into 296 operational taxonomic units (OTUs) by internal transcribed spacer sequencing of 1998 representative colonies. Climatic and spatial factors were the best descriptors of the structure of endophytic communities, outweighing soil characteristics, host genotype and geographical distance. OTU richness was negatively affected by precipitation, and the composition of communities followed latitudinal gradients of precipitation and temperature. Only six widespread OTUs belonging to the orders Pleosporales, Hypocreales and Helotiales represented about 50% of all isolates. Assessments of their individual distribution revealed particular ecological preferences or a cosmopolitan occurrence. Our findings support a strong influence of the local environment in determining root endophytic communities, and show a different niche occupancy by individual endophytes. PMID:26530450

  2. Fruits eaten by woolly monkeys (Lagothrix lagothricha) at local and regional scales.

    PubMed

    Gonzalez, Marcos; Clavijo, Laura; Betancur, Julio; Stevenson, Pablo R

    2016-04-01

    Woolly monkeys are endangered New World Primates whose natural ecological requirements are known from few sites. This study aimed to investigate the diet of woolly monkeys (Lagothrix lagothricha, Atelidae) to examine how availability determines fruit choice at local and regional scales. We followed two groups of woolly monkeys in the Mosiro Itajura-Caparú biological station in the Colombian Amazon for 16 months, and then compared our observations with previous studies for this and other sites in the Amazon and eastern Andes. We found a high prevalence of fruits in the diet of woolly monkeys in Caparú, which was supplemented with arthropods and leaves. This pattern was observed in all age/sex classes, although juveniles ate more arthropods, and females with dependent young ate more leaves than other classes. We suggest these differences might be due to intragroup competition and particular nutritional requirements in each age/sex class. When comparing the fruit diet composition in Caparú (>190 species) with four other places, we found that Moraceae, Fabaceae, and Sapotaceae were consistently important tree families in the Amazonian sites, and that forest richness is a good predictor of the diet richness. Overall, the results support the hypothesis that woolly monkeys are opportunistic frugivores that are able to adapt their diet to the forest supply and to the temporal variation in resource availability. PMID:26910234

  3. Identifying local-scale wilderness for on-ground conservation actions within a global biodiversity hotspot

    PubMed Central

    Lin, Shiwei; Wu, Ruidong; Hua, Chaolang; Ma, Jianzhong; Wang, Wenli; Yang, Feiling; Wang, Junjun

    2016-01-01

    Protecting wilderness areas (WAs) is a crucial proactive approach to sustain biodiversity. However, studies identifying local-scale WAs for on-ground conservation efforts are still very limited. This paper investigated the spatial patterns of wilderness in a global biodiversity hotspot – Three Parallel Rivers Region (TPRR) in southwest China. Wilderness was classified into levels 1 to 10 based on a cluster analysis of five indicators, namely human population density, naturalness, fragmentation, remoteness, and ruggedness. Only patches characterized by wilderness level 1 and ≥1.0 km2 were considered WAs. The wilderness levels in the northwest were significantly higher than those in the southeast, and clearly increased with the increase in elevation. The WAs covered approximately 25% of TPRR’s land, 89.3% of which was located in the >3,000 m elevation zones. WAs consisted of 20 vegetation types, among which temperate conifer forest, cold temperate shrub and alpine ecosystems covered 79.4% of WAs’ total area. Most WAs were still not protected yet by existing reserves. Topography and human activities are the primary influencing factors on the spatial patterns of wilderness. We suggest establishing strictly protected reserves for most large WAs, while some sustainable management approaches might be more optimal solutions for many highly fragmented small WAs. PMID:27181186

  4. RRW: repeated random walks on genome-scale protein networks for local cluster discovery

    PubMed Central

    Macropol, Kathy; Can, Tolga; Singh, Ambuj K

    2009-01-01

    Background We propose an efficient and biologically sensitive algorithm based on repeated random walks (RRW) for discovering functional modules, e.g., complexes and pathways, within large-scale protein networks. Compared to existing cluster identification techniques, RRW implicitly makes use of network topology, edge weights, and long range interactions between proteins. Results We apply the proposed technique on a functional network of yeast genes and accurately identify statistically significant clusters of proteins. We validate the biological significance of the results using known complexes in the MIPS complex catalogue database and well-characterized biological processes. We find that 90% of the created clusters have the majority of their catalogued proteins belonging to the same MIPS complex, and about 80% have the majority of their proteins involved in the same biological process. We compare our method to various other clustering techniques, such as the Markov Clustering Algorithm (MCL), and find a significant improvement in the RRW clusters' precision and accuracy values. Conclusion RRW, which is a technique that exploits the topology of the network, is more precise and robust in finding local clusters. In addition, it has the added flexibility of being able to find multi-functional proteins by allowing overlapping clusters. PMID:19740439

  5. Identifying local-scale wilderness for on-ground conservation actions within a global biodiversity hotspot.

    PubMed

    Lin, Shiwei; Wu, Ruidong; Hua, Chaolang; Ma, Jianzhong; Wang, Wenli; Yang, Feiling; Wang, Junjun

    2016-01-01

    Protecting wilderness areas (WAs) is a crucial proactive approach to sustain biodiversity. However, studies identifying local-scale WAs for on-ground conservation efforts are still very limited. This paper investigated the spatial patterns of wilderness in a global biodiversity hotspot - Three Parallel Rivers Region (TPRR) in southwest China. Wilderness was classified into levels 1 to 10 based on a cluster analysis of five indicators, namely human population density, naturalness, fragmentation, remoteness, and ruggedness. Only patches characterized by wilderness level 1 and ≥1.0 km(2) were considered WAs. The wilderness levels in the northwest were significantly higher than those in the southeast, and clearly increased with the increase in elevation. The WAs covered approximately 25% of TPRR's land, 89.3% of which was located in the >3,000 m elevation zones. WAs consisted of 20 vegetation types, among which temperate conifer forest, cold temperate shrub and alpine ecosystems covered 79.4% of WAs' total area. Most WAs were still not protected yet by existing reserves. Topography and human activities are the primary influencing factors on the spatial patterns of wilderness. We suggest establishing strictly protected reserves for most large WAs, while some sustainable management approaches might be more optimal solutions for many highly fragmented small WAs. PMID:27181186

  6. Improving the textural characterization of trabecular bone structure to quantify its changes: the locally adapted scaling vector method

    NASA Astrophysics Data System (ADS)

    Raeth, Christoph W.; Mueller, Dirk; Boehm, Holger F.; Rummeny, Ernst J.; Link, Thomas M.; Monetti, Roberto

    2005-04-01

    We extend the recently introduced scaling vector method (SVM) to improve the textural characterization of oriented trabecular bone structures in the context of osteoporosis. Using the concept of scaling vectors one obtains non-linear structural information from data sets, which can account for global anisotropies. In this work we present a method which allows us to determine the local directionalities in images by using scaling vectors. Thus it becomes possible to better account for local anisotropies and to implement this knowledge in the calculation of the scaling properties of the image. By applying this adaptive technique, a refined quantification of the image structure is possible: we test and evaluate our new method using realistic two-dimensional simulations of bone structures, which model the effect of osteoblasts and osteoclasts on the local change of relative bone density. The partial differential equations involved in the model are solved numerically using cellular automata (CA). Different realizations with slightly varying control parameters are considered. Our results show that even small changes in the trabecular structures, which are induced by variation of a control parameters of the system, become discernible by applying the locally adapted scaling vector method. The results are superior to those obtained by isotropic and/or bulk measures. These findings may be especially important for monitoring the treatment of patients, where the early recognition of (drug-induced) changes in the trabecular structure is crucial.

  7. When Local Extinction and Colonization of River Fishes Can Be Predicted by Regional Occupancy: the Role of Spatial Scales

    PubMed Central

    Bergerot, Benjamin; Hugueny, Bernard; Belliard, Jérôme

    2013-01-01

    Background Predicting which species are likely to go extinct is perhaps one of the most fundamental yet challenging tasks for conservation biologists. This is particularly relevant for freshwater ecosystems which tend to have the highest proportion of species threatened with extinction. According to metapopulation theories, local extinction and colonization rates of freshwater subpopulations can depend on the degree of regional occupancy, notably due to rescue effects. However, relationships between extinction, colonization, regional occupancy and the spatial scales at which they operate are currently poorly known. Methods And Findings: We used a large dataset of freshwater fish annual censuses in 325 stream reaches to analyse how annual extinction/colonization rates of subpopulations depend on the regional occupancy of species. For this purpose, we modelled the regional occupancy of 34 fish species over the whole French river network and we tested how extinction/colonization rates could be predicted by regional occupancy described at five nested spatial scales. Results show that extinction and colonization rates depend on regional occupancy, revealing existence a rescue effect. We also find that these effects are scale dependent and their absolute contribution to colonization and extinction tends to decrease from river section to larger basin scales. Conclusions In terms of management, we show that regional occupancy quantification allows the evaluation of local species extinction/colonization dynamics and reduction of local extinction risks for freshwater fish species implies the preservation of suitable habitats at both local and drainage basin scales. PMID:24367636

  8. Elevational Gradients in β-Diversity Reflect Variation in the Strength of Local Community Assembly Mechanisms across Spatial Scales

    PubMed Central

    Tello, J. Sebastián; Myers, Jonathan A.; Macía, Manuel J.; Fuentes, Alfredo F.; Cayola, Leslie; Arellano, Gabriel; Loza, M. Isabel; Torrez, Vania; Cornejo, Maritza; Miranda, Tatiana B.; Jørgensen, Peter M.

    2015-01-01

    Despite long-standing interest in elevational-diversity gradients, little is known about the processes that cause changes in the compositional variation of communities (β-diversity) across elevations. Recent studies have suggested that β-diversity gradients are driven by variation in species pools, rather than by variation in the strength of local community assembly mechanisms such as dispersal limitation, environmental filtering, or local biotic interactions. However, tests of this hypothesis have been limited to very small spatial scales that limit inferences about how the relative importance of assembly mechanisms may change across spatial scales. Here, we test the hypothesis that scale-dependent community assembly mechanisms shape biogeographic β-diversity gradients using one of the most well-characterized elevational gradients of tropical plant diversity. Using an extensive dataset on woody plant distributions along a 4,000-m elevational gradient in the Bolivian Andes, we compared observed patterns of β-diversity to null-model expectations. β-deviations (standardized differences from null values) were used to measure the relative effects of local community assembly mechanisms after removing sampling effects caused by variation in species pools. To test for scale-dependency, we compared elevational gradients at two contrasting spatial scales that differed in the size of local assemblages and regions by at least an order of magnitude. Elevational gradients in β-diversity persisted after accounting for regional variation in species pools. Moreover, the elevational gradient in β-deviations changed with spatial scale. At small scales, local assembly mechanisms were detectable, but variation in species pools accounted for most of the elevational gradient in β-diversity. At large spatial scales, in contrast, local assembly mechanisms were a dominant force driving changes in β-diversity. In contrast to the hypothesis that variation in species pools alone

  9. The effect of locally delivered doxycycline as an adjunctive therapy to scaling and root planing in smokers

    PubMed Central

    Al Hulami, Hassan; Babay, Nadir; Awartani, Fatin; Anil, Sukumaran

    2011-01-01

    Background Locally delivered doxycycline is found to be effective in managing periodontitis as an adjunct to scaling and root planing. Aim To evaluate the effect of locally delivered doxycycline (10%) with scaling and root planing in the periodontal treatment of smokers and to compare it with scaling and root planing alone. Methods Twelve smokers with chronic periodontitis and a pocket depth (⩾5 mm) on posterior teeth that bleed on probing were selected. Patients were randomly assigned to scaling and root planing (SRP) or scaling and root planing followed by local application of doxycycline (SRP-D). Plaque, bleeding on probing, gingival recession, clinical attachment level (CAL), and probing depth (PD) were recorded at the baseline, 6 and 12 weeks. Results Both groups showed a significant reduction in Plaque, Bleeding on Probing and pocket depth at 6th and 12th week from the baseline. A statistically significant gain of attachment was observed in both groups after treatment. Even though the doxycycline group showed slightly higher attachment gain it was not statistically significant compared to the control group. Conclusion The observations of the study reveal that the additional benefit of topical application of doxycycline as an adjunct to scaling and root planing in smokers is not convincing. However, further clinical studies may be necessary to substantiate the present observations. PMID:23960508

  10. Efficient rapid microwave-assisted route to synthesize InP micrometer hollow spheres

    SciTech Connect

    Zheng Xiuwen Hu Qitu; Sun Chuansheng

    2009-01-08

    The efficiencies of two methods of synthesizing InP micro-scale hollow spheres are compared via the analogous solution-liquid-solid (ASLS) growth mechanism, either through a traditional solvothermal procedure, or via a microwave-assisted method. Scanning electronic microscopy (SEM) images show that most of the as-grown samples are micrometer hollow spheres, which indicates the efficiency of both methods. For traditional solvothermal route, long time (10 h) is necessary to obtain the desired samples, however, for the microwave-assisted route, 30 min is enough for hollow spherical products. An optimal choice of microwave irradiating time allows reducing the reaction time from hours to minutes. The proposed ASLS growth mechanism has also been discussed in detail.

  11. 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.

  12. Simultaneous estimation of local- and flowpath-scale rate-limited mass transfer parameters using electrical-resistivity tomography

    NASA Astrophysics Data System (ADS)

    Briggs, M. A.; Day-Lewis, F. D.; Ong, J. B.; Lane, J. W.; Curtis, G. P.

    2012-12-01

    In the presence of rate-limited mass transfer (RLMT), conventional chemical sampling of the subsurface preferentially pulls pore water from the mobile domain. Therefore, the characteristics of the immobile domain must be inferred from the mobile tracer signal, which is modified with transport and immobile exchange over a representative length. Because conventional chemical data are not directly sensitive to the immobile zone, this representative length must be sufficient to allow enough exchange between the two domains to inform immobile parameter estimation (e.g., optimal Damkohler range). Flowpath "averaged" RLMT parameters may not well describe the true field variability in the immobile domain size and exchange coefficient, parameters which control the retention and subsequent long-term release of contaminants. In contrast, bulk electrical conductivity is sensitive to the volume-weighted ionic tracer concentration in both the mobile and immobile domains. When co-located bulk conductivity and fluid conductivity are analyzed concurrently, estimates can be obtained for (1) effective RLMT parameters averaged along the upgradient flowpath and (2) local-scale RLMT parameters for the volume from which chemical samples and electrical measurements are taken. Here, we use electrical resistivity tomography (ERT), for the first time, to discriminate and identify effective flowpath and local-scale RLMT parameters, informing the true spatial variability in mass transfer. We apply this technique at the field scale at a uranium contamination site in Naturita, Colorado, USA. Inverse modeling was used to optimize parameter estimates to best simulate both the observed bulk and fluid conductivity, and objectively determine parameter sensitivity, correlation, and confidence. Local RLMT parameters were found to be most sensitive to changes in bulk conductivity, while effective flowpath parameters were most sensitive to changes in fluid conductivity. Observed non-linear hysteresis

  13. Separation of hydrological effects from GNSS time series on regional and local scale

    NASA Astrophysics Data System (ADS)

    Rossi, Giuliana; Zuliani, David; Fabris, Paolo

    2016-04-01

    Continuous GNSS networks provide unique information about the crustal displacements, of use for studies concerning gravity field, plate motions, tectonic processes, and earthquake cycle understanding. For these purposes, overall in the case of regions with slow deformation strain, we have to individuate and separate all the possible contributions, at the various frequencies. Among the others, hydrological loading effects can be present over a wide frequency range and have to be accurately modelled. The present work is aimed to test, whether the GNSS signal is sensitive to hydrological effects at a regional or a more local scale. The dataset we chose for the tests is ideal: it relates to a relatively small region, where the active collisional processes generate a moderate seismic activity and is characterized by high rainfall rate and significant hydrological phenomena. The data belong to the Friuli Regional Deformation Network (FReDNet) of OGS (Istituto Nazionale di Oceanografia e Geofisica Sperimentale), consisting of 16 GNSS permanent sites distributed on the northern edge of the Adria microplate (NE-Italy). The data set includes the time series from the 10 GNSS permanent sites of the Marussi network of the Friuli-Venezia Giulia Regional Council. The time-span covered by the network overcomes in many cases the twelve years, giving the possibility to study the various terms superimposed to the linear one, due to the plate motion. After a first processing of the GPS data of the longest time series, using GAMIT/GLOBK, eliminating the outliers, and filling eventual short gaps in the data through linear interpolation, we corrected them for the annual and seasonal terms and the displacements due to hydrological mass loading effects on multiyear timescales. For our test, we first addressed the regional level problem. Following the approach of Chamoli et al. (2014), we separated the annual, semiannual, and pluriannual terms of the displacements excited by the

  14. A scaling law for the local CHF on the external bottom side of a fully submerged reactor vessel

    SciTech Connect

    Cheung, F.B.; Haddad, K.H.; Liu, Y.C.

    1997-02-01

    A scaling law for estimating the local critical heat flux on the outer surface of a heated hemispherical vessel that is fully submerged in water has been developed from the results of an advanced hydrodynamic CHF model for pool boiling on a downward facing curved heating surface. The scaling law accounts for the effects of the size of the vessel, the level of liquid subcooling, the intrinsic properties of the fluid, and the spatial variation of the local critical heat flux along the heating surface. It is found that for vessels with diameters considerably larger than the characteristic size of the vapor masses, the size effect on the local critical heat flux is limited almost entirely to the effect of subcooling associated with the local liquid head. When the subcooling effect is accounted for separately, the local CHF limit is nearly independent of the vessel size. Based upon the scaling law developed in this work, it is possible to merge, within the experimental uncertainties, all the available local CHF data obtained for various vessel sizes under both saturated and subcooled boiling conditions into a single curve. Applications of the scaling law to commercial-size vessels have been made for various system pressures and water levels above the heated vessel. Over the range of conditions explored in this study, the local CHF limit is found to increase by a factor of two or more from the bottom center to the upper edge of the vessel. Meanwhile, the critical heat flux at a given angular position of the heated vessel is also found to increase appreciably with the system pressure and the water level.

  15. Diffusion of micrometer-sized soft particles in confinement

    NASA Astrophysics Data System (ADS)

    Jordan, Benjamin; Aptowicz, Kevin

    We investigate the diffusion of micrometer sized poly(N-isopropylacrylamide) (PNIPAM) gel particles in confinement. The influence of confinement on the transport of small particles is becoming increasingly important for microfluidics and bio-fluidics. Analytical solutions to this problem are limited to very unique geometries or gross approximations. Computational methods have provided more insight into the problem as well as experimental investigations. However, most research has focused on the hard-sphere problem. In this work, we will explore the diffusion of soft particles in confinement. The dynamics of the particles confined between two parallel walls is captured with video-microscopy. In addition, we use a recently developed technique to measurement confinement of particles in-situ with a precision of 1%. This poster will present some preliminary results of how confinement affects the diffusion of these soft particles. We acknowledge support from Grant DMR-1206231.

  16. Scale morphometry allows discrimination of European sardine Sardina pilchardus and round sardinella Sardinella aurita and among their local populations.

    PubMed

    Bräger, Zs; Moritz, T; Tsikliras, A C; Gonzalvo, J; Radulović, M; Staszny, Á

    2016-03-01

    Landmark-based geometric morphometric analysis revealed differences in scale shape between European sardine Sardina pilchardus and round sardinella Sardinella aurita as well as among the local populations of each species. Fish scale measurements from four different areas in the central and eastern Mediterranean Sea showed that the mean scale shape of the two species using landmark data could be differentiated with high certainty. Populations of S. aurita from the central and eastern Mediterranean Sea could be separated reliably (P < 0·001) with an average discrimination rate of 91%, whereas the average discrimination of the S. pilchardus populations was lower (80%), albeit still high. PMID:26822859

  17. OCAAT: automated analysis of star cluster colour-magnitude diagrams for gauging the local distance scale

    NASA Astrophysics Data System (ADS)

    Perren, Gabriel I.; Vázquez, Ruben A.; Piatti, Andrés E.; Moitinho, André

    2014-05-01

    Star clusters are among the fundamental astrophysical objects used in setting the local distance scale. Despite its crucial importance, the accurate determination of the distances to the Magellanic Clouds (SMC/LMC) remains a fuzzy step in the cosmological distance ladder. The exquisite astrometry of the recently launched ESA Gaia mission is expected to deliver extremely accurate statistical parallaxes, and thus distances, to the SMC/LMC. However, an independent SMC/LMC distance determination via main sequence fitting of star clusters provides an important validation check point for the Gaia distances. This has been a valuable lesson learnt from the famous Hipparcos Pleiades distance discrepancy problem. Current observations will allow hundreds of LMC/SMC clusters to be analyzed in this light. Today, the most common approach for star cluster main sequence fitting is still by eye. The process is intrinsically subjective and affected by large uncertainties, especially when applied to poorly populated clusters. It is also, clearly, not an efficient route for addressing the analysis of hundreds, or thousands, of star clusters. These concerns, together with a new attitude towards advanced statistical techniques in astronomy and the availability of powerful computers, have led to the emergence of software packages designed for analyzing star cluster photometry. With a few rare exceptions, those packages are not publicly available. Here we present OCAAT (Open Cluster Automated Analysis Tool), a suite of publicly available open source tools that fully automatises cluster isochrone fitting. The code will be applied to a large set of hundreds of open clusters observed in the Washington system, located in the Milky Way and the Magellanic Clouds. This will allow us to generate an objective and homogeneous catalog of distances up to ~ 60 kpc along with its associated reddening, ages and metallicities and uncertainty estimates.

  18. Assessing Weather-Yield Relationships in Rice at Local Scale Using Data Mining Approaches

    PubMed Central

    Delerce, Sylvain; Dorado, Hugo; Grillon, Alexandre; Rebolledo, Maria Camila; Prager, Steven D.; Patiño, Victor Hugo; Garcés Varón, Gabriel; Jiménez, Daniel

    2016-01-01

    Seasonal and inter-annual climate variability have become important issues for farmers, and climate change has been shown to increase them. Simultaneously farmers and agricultural organizations are increasingly collecting observational data about in situ crop performance. Agriculture thus needs new tools to cope with changing environmental conditions and to take advantage of these data. Data mining techniques make it possible to extract embedded knowledge associated with farmer experiences from these large observational datasets in order to identify best practices for adapting to climate variability. We introduce new approaches through a case study on irrigated and rainfed rice in Colombia. Preexisting observational datasets of commercial harvest records were combined with in situ daily weather series. Using Conditional Inference Forest and clustering techniques, we assessed the relationships between climatic factors and crop yield variability at the local scale for specific cultivars and growth stages. The analysis showed clear relationships in the various location-cultivar combinations, with climatic factors explaining 6 to 46% of spatiotemporal variability in yield, and with crop responses to weather being non-linear and cultivar-specific. Climatic factors affected cultivars differently during each stage of development. For instance, one cultivar was affected by high nighttime temperatures in the reproductive stage but responded positively to accumulated solar radiation during the ripening stage. Another was affected by high nighttime temperatures during both the vegetative and reproductive stages. Clustering of the weather patterns corresponding to individual cropping events revealed different groups of weather patterns for irrigated and rainfed systems with contrasting yield levels. Best-suited cultivars were identified for some weather patterns, making weather-site-specific recommendations possible. This study illustrates the potential of data mining for

  19. Spatial epidemiological techniques in cholera mapping and analysis towards a local scale predictive modelling

    NASA Astrophysics Data System (ADS)

    Rasam, A. R. A.; Ghazali, R.; Noor, A. M. M.; Mohd, W. M. N. W.; Hamid, J. R. A.; Bazlan, M. J.; Ahmad, N.

    2014-02-01

    Cholera spatial epidemiology is the study of the spread and control of the disease spatial pattern and epidemics. Previous studies have shown that multi-factorial causation such as human behaviour, ecology and other infectious risk factors influence the disease outbreaks. Thus, understanding spatial pattern and possible interrelationship factors of the outbreaks are crucial to be explored an in-depth study. This study focuses on the integration of geographical information system (GIS) and epidemiological techniques in exploratory analyzing the cholera spatial pattern and distribution in the selected district of Sabah. Spatial Statistic and Pattern tools in ArcGIS and Microsoft Excel software were utilized to map and analyze the reported cholera cases and other data used. Meanwhile, cohort study in epidemiological technique was applied to investigate multiple outcomes of the disease exposure. The general spatial pattern of cholera was highly clustered showed the disease spread easily at a place or person to others especially 1500 meters from the infected person and locations. Although the cholera outbreaks in the districts are not critical, it could be endemic at the crowded areas, unhygienic environment, and close to contaminated water. It was also strongly believed that the coastal water of the study areas has possible relationship with the cholera transmission and phytoplankton bloom since the areas recorded higher cases. GIS demonstrates a vital spatial epidemiological technique in determining the distribution pattern and elucidating the hypotheses generating of the disease. The next research would be applying some advanced geo-analysis methods and other disease risk factors for producing a significant a local scale predictive risk model of the disease in Malaysia.

  20. Assessing Weather-Yield Relationships in Rice at Local Scale Using Data Mining Approaches.

    PubMed

    Delerce, Sylvain; Dorado, Hugo; Grillon, Alexandre; Rebolledo, Maria Camila; Prager, Steven D; Patiño, Victor Hugo; Garcés Varón, Gabriel; Jiménez, Daniel

    2016-01-01

    Seasonal and inter-annual climate variability have become important issues for farmers, and climate change has been shown to increase them. Simultaneously farmers and agricultural organizations are increasingly collecting observational data about in situ crop performance. Agriculture thus needs new tools to cope with changing environmental conditions and to take advantage of these data. Data mining techniques make it possible to extract embedded knowledge associated with farmer experiences from these large observational datasets in order to identify best practices for adapting to climate variability. We introduce new approaches through a case study on irrigated and rainfed rice in Colombia. Preexisting observational datasets of commercial harvest records were combined with in situ daily weather series. Using Conditional Inference Forest and clustering techniques, we assessed the relationships between climatic factors and crop yield variability at the local scale for specific cultivars and growth stages. The analysis showed clear relationships in the various location-cultivar combinations, with climatic factors explaining 6 to 46% of spatiotemporal variability in yield, and with crop responses to weather being non-linear and cultivar-specific. Climatic factors affected cultivars differently during each stage of development. For instance, one cultivar was affected by high nighttime temperatures in the reproductive stage but responded positively to accumulated solar radiation during the ripening stage. Another was affected by high nighttime temperatures during both the vegetative and reproductive stages. Clustering of the weather patterns corresponding to individual cropping events revealed different groups of weather patterns for irrigated and rainfed systems with contrasting yield levels. Best-suited cultivars were identified for some weather patterns, making weather-site-specific recommendations possible. This study illustrates the potential of data mining for

  1. Sustainability of Italian Agriculture: A Methodological Approach for Assessing Crop Water Footprint at Local Scale

    NASA Astrophysics Data System (ADS)

    Altobelli, F.; Dalla Marta, A.; Cimino, O.; Orlandini, S.; Natali, F.

    2014-12-01

    In a world where population is rapidly growing and where several planetary boundaries (i.e. climate change, biodiversity loss and nitrogen cycle) have already been crossed, agriculture is called to respond to the needs of food security through a sustainable use of natural resources. In particular, water is one of the main elements of fertility so the agricultural activity, and the whole agro-food chain, is one of the productive sectors more dependent on water resource and it is able to affect, at regional level, its availability for all the other sectors. In this study, we proposed a methodology for assessing the green and blue water footprint of the main Italian crops typical of the different geographical areas (northwest, northeast, center, and south) based on data extracted from Italian Farm Accountancy Data Network (FADN). FADN is an instrument for evaluating the income of agricultural holdings and the impacts of the Common Agricultural Policy. Crops were selected based on incidence of cultivated area on the total arable land of FADN farms net. Among others, the database contains data on irrigation management (irrigated surface, length of irrigation season, volumes of water, etc.), and crop production. Meteorological data series were obtained by a combination of local weather stations and ECAD E-obs spatialized database. Crop water footprints were evaluated against water availability and risk of desertification maps of Italy. Further, we compared the crop water footprints obtained with our methodology with already existing data from similar studies in order to highlight the effects of spatial scale and level of detail of available data.

  2. Data gaps in anthropogenically driven local-scale species richness change studies across the Earth's terrestrial biomes.

    PubMed

    Murphy, Grace E P; Romanuk, Tamara N

    2016-05-01

    There have been numerous attempts to synthesize the results of local-scale biodiversity change studies, yet several geographic data gaps exist. These data gaps have hindered ecologist's ability to make strong conclusions about how local-scale species richness is changing around the globe. Research on four of the major drivers of global change is unevenly distributed across the Earth's biomes. Here, we use a dataset of 638 anthropogenically driven species richness change studies to identify where data gaps exist across the Earth's terrestrial biomes based on land area, future change in drivers, and the impact of drivers on biodiversity, and make recommendations for where future studies should focus their efforts. Across all drivers of change, the temperate broadleaf and mixed forests and the tropical moist broadleaf forests are the best studied. The biome-driver combinations we have identified as most critical in terms of where local-scale species richness change studies are lacking include the following: land-use change studies in tropical and temperate coniferous forests, species invasion and nutrient addition studies in the boreal forest, and warming studies in the boreal forest and tropics. Gaining more information on the local-scale effects of the specific human drivers of change in these biomes will allow for better predictions of how human activity impacts species richness around the globe. PMID:27069589

  3. Local Discrepancies in Continental Scale Biomass Maps: A Case Study over Forested and Non-Forested Landscapes in Maryland, USA

    NASA Astrophysics Data System (ADS)

    Huang, W.; Swatantran, A.; Johnson, K. D.; Duncanson, L.; Tang, H.; ONeil-Dunne, J.; Hurtt, G. C.; Dubayah, R.

    2015-12-01

    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-derived biomass map over Maryland, USA. We conduct detailed comparisons at pixel-, county-, and state-level. Spatial patterns of biomass are broadly consistent in all maps, but there are large differences at fine scales (RMSD 48.5 Mg·ha-1-92.7 Mg·ha-1). Discrepancies reduce with aggregation and the agreement among products improves at the county level. However, continental scale maps exhibit residual negative biases in mean (33.0 Mg·ha-1-54.6 Mg·ha-1) and total biomass (3.5-5.8 Tg) when compared to the high-resolution lidar biomass map. Three of the four continental scale maps reach near-perfect agreement at ~4 km and onward but do not converge with the high-resolution biomass map even at county scale. At the State level, these maps underestimate biomass by 30-80 Tg in forested and 40-50 Tg in non-forested areas. Local discrepancies in continental scale biomass maps are caused by factors including data inputs, modeling approaches, forest / non-forest definitions and time lags. There is a net underestimation over high biomass forests and non-forested areas that could impact carbon accounting at all levels. Local, high-resolution lidar-derived biomass maps provide a valuable bottom-up reference to improve the analysis and interpretation of large-scale maps produced in carbon monitoring systems.

  4. Response of pest control by generalist predators to local-scale plant diversity: a meta-analysis.

    PubMed

    Dassou, Anicet Gbèblonoudo; Tixier, Philippe

    2016-02-01

    Disentangling the effects of plant diversity on the control of herbivores is important for understanding agricultural sustainability. Recent studies have investigated the relationships between plant diversity and arthropod communities at the landscape scale, but few have done so at the local scale. We conducted a meta-analysis of 32 papers containing 175 independent measures of the relationship between plant diversity and arthropod communities. We found that generalist predators had a strong positive response to plant diversity, that is, their abundance increased as plant diversity increased. Herbivores, in contrast, had an overall weak and negative response to plant diversity. However, specialist and generalist herbivores differed in their response to plant diversity, that is, the response was negative for specialists and not significant for generalists. While the effects of scale remain unclear, the response to plant diversity tended to increase for specialist herbivores, but decrease for generalist herbivores as the scale increased. There was no clear effect of scale on the response of generalist predators to plant diversity. Our results suggest that the response of herbivores to plant diversity at the local scale is a balance between habitat and trophic effects that vary according to arthropod specialization and habitat type. Synthesis and applications. Positive effects of plant diversity on generalist predators confirm that, at the local scale, plant diversification of agroecosystems is a credible and promising option for increasing pest regulation. Results from our meta-analysis suggest that natural control in plant-diversified systems is more likely to occur for specialist than for generalist herbivores. In terms of pest management, our results indicate that small-scale plant diversification (via the planting of cover crops or intercrops and reduced weed management) is likely to increase the control of specialist herbivores by generalist predators. PMID

  5. Chemical Composition of Micrometer-Sized Filaments in an Aragonite Host by a Miniature Laser Ablation/Ionization Mass Spectrometer.

    PubMed

    Tulej, Marek; Neubeck, Anna; Ivarsson, Magnus; Riedo, Andreas; Neuland, Maike B; Meyer, Stefan; Wurz, Peter

    2015-08-01

    Detection of extraterrestrial life is an ongoing goal in space exploration, and there is a need for advanced instruments and methods for the detection of signatures of life based on chemical and isotopic composition. Here, we present the first investigation of chemical composition of putative microfossils in natural samples using a miniature laser ablation/ionization time-of-flight mass spectrometer (LMS). The studies were conducted with high lateral (∼15 μm) and vertical (∼20-200 nm) resolution. The primary aim of the study was to investigate the instrument performance on micrometer-sized samples both in terms of isotope abundance and element composition. The following objectives had to be achieved: (1) Consider the detection and calculation of single stable isotope ratios in natural rock samples with techniques compatible with their employment of space instrumentation for biomarker detection in future planetary missions. (2) Achieve a highly accurate chemical compositional map of rock samples with embedded structures at the micrometer scale in which the rock matrix is easily distinguished from the micrometer structures. Our results indicate that chemical mapping of strongly heterogeneous rock samples can be obtained with a high accuracy, whereas the requirements for isotope ratios need to be improved to reach sufficiently large signal-to-noise ratio (SNR). PMID:26247475

  6. The signature of fine scale local adaptation in Atlantic salmon revealed from common garden experiments in nature

    PubMed Central

    O'Toole, Ciar L; Reed, Thomas E; Bailie, Deborah; Bradley, Caroline; Cotter, Deirdre; Coughlan, Jamie; Cross, Tom; Dillane, Eileen; McEvoy, Sarah; Ó Maoiléidigh, Niall; Prodöhl, Paulo; Rogan, Ger; McGinnity, Philip

    2015-01-01

    Understanding the extent, scale and genetic basis of local adaptation (LA) is important for conservation and management. Its relevance in salmonids at microgeographic scales, where dispersal (and hence potential gene flow) can be substantial, has however been questioned. Here, we compare the fitness of communally reared offspring of local and foreign Atlantic salmon Salmo salar from adjacent Irish rivers and reciprocal F1 hybrid crosses between them, in the wild ‘home’ environment of the local population. Experimental groups did not differ in wild smolt output but a catastrophic flood event may have limited our ability to detect freshwater performance differences, which were evident in a previous study. Foreign parr exhibited higher, and hybrids intermediate, emigration rates from the natal stream relative to local parr, consistent with genetically based behavioural differences. Adult return rates were lower for the foreign compared to the local group. Overall lifetime success of foreigners and hybrids relative to locals was estimated at 31% and 40% (mean of both hybrid groups), respectively. The results imply a genetic basis to fitness differences among populations separated by only 50 km, driven largely by variation in smolt to adult return rates. Hence even if supplementary stocking programs obtain broodstock from neighbouring rivers, the risk of extrinsic outbreeding depression may be high. PMID:26495041

  7. The signature of fine scale local adaptation in Atlantic salmon revealed from common garden experiments in nature.

    PubMed

    O'Toole, Ciar L; Reed, Thomas E; Bailie, Deborah; Bradley, Caroline; Cotter, Deirdre; Coughlan, Jamie; Cross, Tom; Dillane, Eileen; McEvoy, Sarah; Ó Maoiléidigh, Niall; Prodöhl, Paulo; Rogan, Ger; McGinnity, Philip

    2015-10-01

    Understanding the extent, scale and genetic basis of local adaptation (LA) is important for conservation and management. Its relevance in salmonids at microgeographic scales, where dispersal (and hence potential gene flow) can be substantial, has however been questioned. Here, we compare the fitness of communally reared offspring of local and foreign Atlantic salmon Salmo salar from adjacent Irish rivers and reciprocal F1 hybrid crosses between them, in the wild 'home' environment of the local population. Experimental groups did not differ in wild smolt output but a catastrophic flood event may have limited our ability to detect freshwater performance differences, which were evident in a previous study. Foreign parr exhibited higher, and hybrids intermediate, emigration rates from the natal stream relative to local parr, consistent with genetically based behavioural differences. Adult return rates were lower for the foreign compared to the local group. Overall lifetime success of foreigners and hybrids relative to locals was estimated at 31% and 40% (mean of both hybrid groups), respectively. The results imply a genetic basis to fitness differences among populations separated by only 50 km, driven largely by variation in smolt to adult return rates. Hence even if supplementary stocking programs obtain broodstock from neighbouring rivers, the risk of extrinsic outbreeding depression may be high. PMID:26495041

  8. Local-scale topoclimate effects on treeline elevations: a country-wide investigation of New Zealand's southern beech treelines.

    PubMed

    Case, Bradley S; Buckley, Hannah L

    2015-01-01

    Although treeline elevations are limited globally by growing season temperature, at regional scales treelines frequently deviate below their climatic limit. The cause of these deviations relate to a host of climatic, disturbance, and geomorphic factors that operate at multiple scales. The ability to disentangle the relative effects of these factors is currently hampered by the lack of reliable topoclimatic data, which describe how regional climatic characteristics are modified by topographic effects in mountain areas. In this study we present an analysis of the combined effects of local- and regional-scale factors on southern beech treeline elevation variability at 28 study areas across New Zealand. We apply a mesoscale atmospheric model to generate local-scale (200 m) meteorological data at these treelines and, from these data, we derive a set of topoclimatic indices that reflect possible detrimental and ameliorative influences on tree physiological functioning. Principal components analysis of meteorological data revealed geographic structure in how study areas were situated in multivariate space along gradients of topoclimate. Random forest and conditional inference tree modelling enabled us to tease apart the relative effects of 17 explanatory factors on local-scale treeline elevation variability. Overall, modelling explained about 50% of the variation in treeline elevation variability across the 28 study areas, with local landform and topoclimatic effects generally outweighing those from regional-scale factors across the 28 study areas. Further, the nature of the relationships between treeline elevation variability and the explanatory variables were complex, frequently non-linear, and consistent with the treeline literature. To our knowledge, this is the first study where model-generated meteorological data, and derived topoclimatic indices, have been developed and applied to explain treeline variation. Our results demonstrate the potential of such an approach

  9. Phased Array Noise Source Localization Measurements of an F404 Nozzle Plume at Both Full and Model Scale

    NASA Technical Reports Server (NTRS)

    Podboy, Gary G.; Bridges, James E.; Henderson, Brenda S.

    2010-01-01

    A 48-microphone planar phased array system was used to acquire jet noise source localization data on both a full-scale F404-GE-F400 engine and on a 1/4th scale model of a F400 series nozzle. The full-scale engine test data show the location of the dominant noise sources in the jet plume as a function of frequency for the engine in both baseline (no chevron) and chevron configurations. Data are presented for the engine operating both with and without afterburners. Based on lessons learned during this test, a set of recommendations are provided regarding how the phased array measurement system could be modified in order to obtain more useful acoustic source localization data on high-performance military engines in the future. The data obtained on the 1/4th scale F400 series nozzle provide useful insights regarding the full-scale engine jet noise source mechanisms, and document some of the differences associated with testing at model-scale versus fullscale.

  10. The importance of local and landscape-scale processes to the occupancy of wetlands by pond-breeding amphibians

    USGS Publications Warehouse

    Scherer, Rick D.; Muths, Erin; Noon, Barry R.

    2012-01-01

    Variation in the distribution and abundance of species across landscapes has traditionally been attributed to processes operating at fine spatial scales (i.e., environmental conditions at the scale of the sampling unit), but processes that operate across larger spatial scales such as seasonal migration or dispersal are also important. To determine the relative importance of these processes, we evaluated hypothesized relationships between the probability of occupancy in wetlands by two amphibians [wood frogs (Lithobates sylvaticus) and boreal chorus frogs (Pseudacris maculata)] and attributes of the landscape measured at three spatial scales in Rocky Mountain National Park, Colorado. We used cost-based buffers and least-cost distances to derive estimates of landscape attributes that may affect occupancy patterns from the broader spatial scales. The most highly ranked models provide strong support for a positive relationship between occupancy by breeding wood frogs and the amount of streamside habitat adjacent to a wetland. The model selection results for boreal chorus frogs are highly uncertain, though several of the most highly ranked models indicate a positive association between occupancy and the number of neighboring, occupied wetlands. We found little evidence that occupancy of either species was correlated with local-scale attributes measured at the scale of individual wetlands, suggesting that processes operating at broader scales may be more important in influencing occupancy patterns in amphibian populations.

  11. Exceptional Isotopic Variability in Stream Waters of the Central Andes: Large-Scale or Local Controls?

    NASA Astrophysics Data System (ADS)

    Fiorella, R. P.; Poulsen, C. J.; Ehlers, T. A.; Jeffery, M. L.; Pillco Zola, R. S.

    2012-12-01

    insufficient to explain the distribution of isotopes in surface water on the Altiplano. Convective precipitation can effectively distill the same atmospheric water vapor repeatedly and lead to more depleted values than predicted by Rayleigh distillation. We assess what fraction of interannual variability can be explained by large-scale climatic variability, such as ENSO and the position of the Bolivian upper level high, and infer how much must therefore be a result of local processes. We infer local stochasticity in convection strongly impacts observed isotopic composition of stream water and drives the large spatial isotopic variability. Enhanced understanding of the modern hydrologic cycle in the high Andes using stable isotopes will help constrain water resource predictions under a changing climate and help hone paleoclimatic and paleoaltimetric interpretations of proxies reliant on stable isotopes of water.

  12. Improving the local relevance of large scale water demand predictions: the way forward

    NASA Astrophysics Data System (ADS)

    Bernhard, Jeroen; Reynaud, Arnaud; de Roo, Ad

    2016-04-01

    Securing adequate availability of fresh water is of vital importance for socio-economic development of present and future Europe. Due to strong heterogeneity in climate conditions, some regions receive an abundant supply of water, where other areas almost completely depend on limited river discharge from upstream catchments. Furthermore, water demand differs greatly between regions due to differences in population density and local presence of intensive water using industries and agriculture. This results in many situations all across Europe where competition between water users translates into relative scarcity and economic damage. Additionally it is expected that inter-related economic and demographic developments, as well as climate change are to only further increase the need for efficient management of our water resources in the future. Successful policy making for such complex problems requires a good understanding of the system and reliable forecasting of conditions. The extent and complexity of the water use system however, stands in high contrast with the poor state of available data and lack of reliable predictions for this multi-disciplinary topic. Although the matching of available water to its demand is a European-wide problem, the amount of data with pan-European coverage is limited and usually with a national resolution at best. This is hindering researchers and policy makers because it usually makes large scale water demand predictions little relevant due to the strong regional heterogenic nature of the problem. We present in our study a first attempt of European-wide water demand predictions based on consistent regional data and econometric methods for the household and industry sector. We gathered data on water consumption, water prices and other relevant variables at the highest spatial detail available from national statistical offices and other organizational bodies. This database provides the most detailed up to date picture of present water

  13. California Coastal Low Clouds: Variability and Influences across Climate to Weather and Continental to Local Scales

    NASA Astrophysics Data System (ADS)

    Schwartz, Rachel E.

    Low coastal stratiform clouds (stratus, stratocumulus, and fog), referred to here as coastal low cloudiness (CLC), are a persistent seasonal feature of continental west coasts, including California. The importance of CLC ranges across fields, with applications ranging from solar resource forecasting, growth of endemic species, and heat wave expression and related health impacts. This dissertation improves our understanding of California's summertime CLC by describing its variability and influences on a range of scales from multidecadal to daily and continental to local. A novel achievement is the development of a new 19-year satellite-derived low cloud record. Trained on airport observations, this high resolution record plays a critical role in the description of CLC at finer spatial and shorter timescales. Observations at coastal airports from Alaska to southern California reveal coherent interannual to interdecadal variation of CLC. The leading mode of CLC variability, accounting for nearly 40% of the total variance, and the majority of individual airports, exhibit decreasing low cloudiness from 1950 to 2012. The coherent patterns of CLC variability are organized by North Pacific Sea Surface Temperature (SST) anomalies, linked to the Pacific Decadal Oscillation (PDO). The new satellite-derived low cloud retrieval reveals, in rich spatial texture, considerable variability in CLC within May-September. The average maximum cloudiness moves northward along the coast, from northern Baja, Mexico to northern California, from May to early August. Both component parts of lower tropospheric stability (LTS), SST and free-troposphere temperature, control this seasonal movement. The peak timing of cloudiness and daytime maximum temperatures are most closely aligned in northern California. On weather timescales, daily CLC anomalies are most strongly related to stability anomalies to the north (climatologically upwind) of the CLC region. CLC is strongly linked to stability in

  14. New quantitative approaches for classifying and predicting local-scale habitats in estuaries

    NASA Astrophysics Data System (ADS)

    Valesini, Fiona J.; Hourston, Mathew; Wildsmith, Michelle D.; Coen, Natasha J.; Potter, Ian C.

    2010-03-01

    This study has developed quantitative approaches for firstly classifying local-scale nearshore habitats in an estuary and then predicting the habitat of any nearshore site in that system. Both approaches employ measurements for a suite of enduring environmental criteria that are biologically relevant and can be easily derived from readily available maps. While the approaches were developed for south-western Australian estuaries, with a focus here on the Swan and Peel-Harvey, they can easily be tailored to any system. Classification of the habitats in each of the above estuaries was achieved by subjecting to hierarchical agglomerative clustering (CLUSTER) and a Similarity Profiles test (SIMPROF), a Manhattan distance matrix constructed from measurements of a suite of enduring criteria recorded at numerous environmentally diverse sites. Groups of sites within the resultant dendogram that were shown by SIMPROF to not contain any significant internal differences, but differ significantly from all other groups in their enduring characteristics, were considered to represent habitat types. The enduring features of the 18 and 17 habitats identified among the 101 and 102 sites in the Swan and Peel-Harvey estuaries, respectively, are presented. The average measurements of the enduring characteristics at each habitat were then used in a novel application of the Linkage Tree (LINKTREE) and SIMPROF routines to produce a "decision tree" for predicting, on the basis of measurements for particular enduring variables, the habitat to which any further site in an estuary is best assigned. In both estuaries, the pattern of relative differences among habitats, as defined by their enduring characteristics, was significantly correlated with that defined by their non-enduring water physico-chemical characteristics recorded seasonally in the field. However, those correlations were substantially higher for the Swan, particularly when salinity was the only water physico-chemical variable

  15. Hydroclimatic Changes of Water on Land and their Drivers from Local-Regional to Global Scales

    NASA Astrophysics Data System (ADS)

    Jaramillo, Fernando; Destouni, Georgia

    2014-05-01

    Past and current climate change in the atmosphere (in terms of temperature T and precipitation P), hydroclimatic changes in the water system on land (in terms of runoff R and evapotranspiration ET) and their links to each other and other possible environmental changes, need to be studied and understood in order to realistically assess how forthcoming changes may affect freshwater resources and to plan for relevant adaptation to these changes. Here we use openly available data for T, P and R development from the beginning of the 20th century until present time in 1260 catchments spread over all continents. The aim is to assess hydroclimatic changes, and the links among atmospheric climate change, changes to land-use and water-use (LUWUC), and water changes on land from the first half (1901-1950) to the second half of the 20th and a bit into the 21st century (1961-2009). In particular, we evaluate changes in ET and in the short-term, intra-annual variability (in terms of the coefficients of variation) of P and R (CV(P) and CV(R), respectively), aiming to distinguish effects on these hydroclimatic changes from atmospheric climate change and from possible LUWUC and other landscape changes that may have occurred between these time periods. By evaluating the change links across global, hemispheric, continental and local-regional catchment scales, we identify dominant influences of climate and other possible change drivers, such as LUWUC, on the observed hydroclimatic changes in the system of water on land. These influences include a) different types of partitioning of given P changes into ET and R changes in different regions of the world, b) changes to runoff variability and c) changes in hydroclimate within Budyko space, of which atmospheric climate change could not be the main driver. The results of this study point to the necessity of considering and accounting for impacts of landscape and not only atmospheric changes on previous, ongoing and future changes of water

  16. Characterization of CVD micrometer-size diamond (abstract)

    NASA Astrophysics Data System (ADS)

    Ohsumi, K.; Hagiya, K.; Miyamoto, M.; Matsuda, J.; Ohmasa, M.

    1989-07-01

    In the field of material sciences, it has long been desired to develope the equipment to obtain crystallographic information of micrometer-size crystalline substances. Synchrotron radiation (SR) could be a candidate to deal with such a small specimen other than electron microscope. It seems more advantageous to utilize SR from the viewpoint that the processing of the diffraction data that has already been established for identification of the materials, structure analysis, and refinement. Even in the case of SR, special care should be taken for the measurement of very weak diffracted intensities. In the case not using SR, the size of 50 μm might be the limit for the specimen to be examined by the diffraction method. The diffracted intensity is proportional to the volume of the specimen, and that of micrometer-size crystal is estimated as 10-5 times of that of the limit mentioned above. The noise level of the experiment, therefore, should be as low as possible. If the noise level becomes negligibly small, the signal could be accumulated continually to the desired intensity level by adjusting measuring time. The experiment, for the purpose, should be carried out in vacuum with the stational crystal method and with very narrow collimated x-ray beams. The Laue method is employed by the above reason, as well as the fact that the intensity of each Bragg reflection on a reciprocal row passing through the origin of the reciprocal space is superposed with each other, which also intensifies a diffraction spot on the photographic plate. The Laue camera is set up at BL-4B of Photon Factory, sealed in vacuum and installed with a very narrow collimater. The development of the system has been performed to the level which several Bragg reflections of molybdenum single crystal with 0.8 μm in its diameter can be taken on the imaging plate for 50-min exposure with ring current from 128 to 125 mA. The origin of diamonds in meteorites has been a controversy as to whether they are

  17. Butterfly scales and their local surface drag dependence on flow orientation

    NASA Astrophysics Data System (ADS)

    Lang, Amy; Jones, Robert

    2011-11-01

    An experimental study was carried out to measure surface drag over embedded cavity models based on the geometry of butterfly wing scales. Monarch (Danaus plexippus) scales, each measuring about 0.1 mm in length, were observed using microscopy to evaluate the microgeometry. Two separate, fabricated models scaled up (300:1) the geometry for dynamically similar testing in a Couette flow oil tank facility. The drag induced over the patterned surfaces was measured using a force gauge. Flow transverse to the rows of scales resulted in a significant drag decrease (>30%), with dependence on Re. This drag reduction is attributed to the formation of embedded vortices forming between the rows of scales resulting in a ``roller bearing'' effect. Flow parallel to the rows, as expected, resulted in larger drag increases, especially at lower Re. Both effects may prove beneficial to the butterfly, during flapping and gliding flight, and will be discussed based on the observed orientation of the scales on real specimens.

  18. Local susceptibility and Kondo scaling in the presence of finite bandwidth

    NASA Astrophysics Data System (ADS)

    Hanl, Markus; Weichselbaum, Andreas

    2014-02-01

    The Kondo scale TK for impurity systems is expected to guarantee universal scaling of physical quantities. However, in practice, not every definition of TK necessarily supports this notion away from the strict scaling limit. Specifically, this paper addresses the role of finite bandwidth D in the strongly correlated Kondo regime. For this, various theoretical definitions of TK are analyzed based on the inverse magnetic impurity susceptibility at zero temperature. While conventional definitions in that respect quickly fail to ensure universal Kondo scaling for a large range of D, this paper proposes an altered definition of TKsc that allows universal scaling of dynamical or thermal quantities for a given fixed Hamiltonian. If the scaling is performed with respect to an external parameter that directly enters the Hamiltonian, such as magnetic field, the corresponding TKsc,B for universal scaling differs, yet becomes equivalent to TKsc in the scaling limit. The only requirement for universal scaling in the full Kondo parameter regime with a residual error of less than 1% is a well-defined isolated Kondo feature with TK≲0.01D irrespective of specific other impurity parameter settings. By varying D over a wide range relative to the bare energies of the impurity, for example, this allows a smooth transition from the Anderson to the Kondo model.

  19. Sensitivity of tree ring growth to local and large-scale climate variability in a region of Southeastern Brazil

    NASA Astrophysics Data System (ADS)

    Venegas-González, Alejandro; Chagas, Matheus Peres; Anholetto Júnior, Claudio Roberto; Alvares, Clayton Alcarde; Roig, Fidel Alejandro; Tomazello Filho, Mario

    2016-01-01

    We explored the relationship between tree growth in two tropical species and local and large-scale climate variability in Southeastern Brazil. Tree ring width chronologies of Tectona grandis (teak) and Pinus caribaea (Caribbean pine) trees were compared with local (Water Requirement Satisfaction Index—WRSI, Standardized Precipitation Index—SPI, and Palmer Drought Severity Index—PDSI) and large-scale climate indices that analyze the equatorial pacific sea surface temperature (Trans-Niño Index-TNI and Niño-3.4-N3.4) and atmospheric circulation variations in the Southern Hemisphere (Antarctic Oscillation-AAO). Teak trees showed positive correlation with three indices in the current summer and fall. A significant correlation between WRSI index and Caribbean pine was observed in the dry season preceding tree ring formation. The influence of large-scale climate patterns was observed only for TNI and AAO, where there was a radial growth reduction in months preceding the growing season with positive values of the TNI in teak trees and radial growth increase (decrease) during December (March) to February (May) of the previous (current) growing season with positive phase of the AAO in teak (Caribbean pine) trees. The development of a new dendroclimatological study in Southeastern Brazil sheds light to local and large-scale climate influence on tree growth in recent decades, contributing in future climate change studies.

  20. Specialization of China large-scale exchange market based on constrained co-local spatial association rule

    NASA Astrophysics Data System (ADS)

    Zhang, Xuewu; Du, Yunyan; Su, Fenzhen; Wen, Wei

    2009-10-01

    With quick development of economy, spatial distribution and specialization level of China large scale commodity exchange markets whose turnover are more than 100 million Yuan, have changed greatly. And influencing factors which distribute in the research region have attribute information and spatial information and do not satisfy statistical independence. Commodity exchange market specialization index is brought forward to measure specialization degree, based on the former research and constrained co-local spatial association rule is used to analyze symbiotic pattern between specialization level and influencing factors. Constrained predicate templates and association rule templates can improve mining efficiency greatly. As the result shown, large scale commodity exchange market specialization level on country-region spatial scale went down from 2000 to 2005 and rose at 2006. The interesting association rules extracted based on defined minimum support and confident can provide officers of region governments with rational advices on large scale commodity exchange markets planning and construction.

  1. Ultrasonic Nanocoining of Sub-micrometer Surface Features

    NASA Astrophysics Data System (ADS)

    Nowak, William John, Jr.

    The goal of this work is to develop a machining process to rapidly generate large areas of sub-micrometer surface features in industrially-feasible amounts of time. These surface features, inspired by designs found in nature, can be sized to produce desired behavior including anti-reflective (AR), superhydrophobic, or syperhydrophilic properties. Current methods of producing these features produce high-fidelity replications, but often require several steps to complete and are not economically feasible in a mass-production setting. This process uses a diamond die containing thousands of subwavelength features mounted to a high speed actuator on the axis of a diamond turning machine. The die is pressed into the workpiece with an elliptical path that matches the surface speed of the moving workpiece and minimizes distortion caused by mismatches in velocity. These die indents are tiled together to create large areas of uniform features, which can then be easily transferred to pliable coatings. Because the die is small (20x20 im), the indentations must occur rapidly (40 kHz) to make nanocoining an industrially feasible process. To produce the ultrasonic 2-D motion for indenting, an actuator was designed that resonates in two orthogonal directions at the same frequency. Analytical solutions were first used to determine the approximate geometry to achieve the desired resonant behavior. Finite element analysis (FEA) is then employed to fine-tune the geometry of the device to meet amplitude requirements. Prototypes were constructed and measured to demonstrate the utility of the proposed design method. A controller is designed and implemented to automatically track the resonant frequency and maintain the desired actuator behavior to ensure the indents are formed uniformly over large areas despite piezoelectric self-heating effects and other environmental affects that impact device resonance. Other control strategies that are required for maintaining uniform spacing of

  2. Fine-scale natal homing and localized movement as shaped by sex and spawning habitat in chinook salmon

    USGS Publications Warehouse

    Neville, Helen; Isaak, Daniel; Dunham, J.B.; Thurow, Russel; Rieman, B.

    2006-01-01

    Natal homing is a hallmark of the life history of salmonid fishes, but the spatial scale of homing within local, naturally reproducing salmon populations is still poorly understood. Accurate homing (paired with restricted movement) should lead to the existence of fine-scale genetic structuring due to the spatial clustering of related individuals on spawning grounds. Thus, we explored the spatial resolution of natal homing using genetic associations among individual Chinook salmon (Oncorhynchus tshawytscha) in an interconnected stream network. We also investigated the relationship between genetic patterns and two factors hypothesized to influence natal homing and localized movements at finer scales in this species, localized patterns in the distribution of spawning gravels and sex. Spatial autocorrelation analyses showed that spawning locations in both sub-basins of our study site were spatially clumped, but the upper sub-basin generally had a larger spatial extent and continuity of redd locations than the lower sub-basin, where the distribution of redds and associated habitat conditions were more patchy. Male genotypes were not autocorrelated at any spatial scale in either sub-basin. Female genotypes showed significant spatial autocorrelation and genetic patterns for females varied in the direction predicted between the two sub-basins, with much stronger autocorrelation in the sub-basin with less continuity in spawning gravels. The patterns observed here support predictions about differential constraints and breeding tactics between the two sexes and the potential for fine-scale habitat structure to influence the precision of natal homing and localized movements of individual Chinook salmon on their breeding grounds.

  3. Explaining Local-Scale Species Distributions: Relative Contributions of Spatial Autocorrelation and Landscape Heterogeneity for an Avian Assemblage

    PubMed Central

    Mattsson, Brady J.; Zipkin, Elise F.; Gardner, Beth; Blank, Peter J.; Sauer, John R.; Royle, J. Andrew

    2013-01-01

    Understanding interactions between mobile species distributions and landcover characteristics remains an outstanding challenge in ecology. Multiple factors could explain species distributions including endogenous evolutionary traits leading to conspecific clustering and endogenous habitat features that support life history requirements. Birds are a useful taxon for examining hypotheses about the relative importance of these factors among species in a community. We developed a hierarchical Bayes approach to model the relationships between bird species occupancy and local landcover variables accounting for spatial autocorrelation, species similarities, and partial observability. We fit alternative occupancy models to detections of 90 bird species observed during repeat visits to 316 point-counts forming a 400-m grid throughout the Patuxent Wildlife Research Refuge in Maryland, USA. Models with landcover variables performed significantly better than our autologistic and null models, supporting the hypothesis that local landcover heterogeneity is important as an exogenous driver for species distributions. Conspecific clustering alone was a comparatively poor descriptor of local community composition, but there was evidence for spatial autocorrelation in all species. Considerable uncertainty remains whether landcover combined with spatial autocorrelation is most parsimonious for describing bird species distributions at a local scale. Spatial structuring may be weaker at intermediate scales within which dispersal is less frequent, information flows are localized, and landcover types become spatially diversified and therefore exhibit little aggregation. Examining such hypotheses across species assemblages contributes to our understanding of community-level associations with conspecifics and landscape composition. PMID:23393564

  4. 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

    2015-01-01

    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. PMID:26051871

  5. Large increase in fracture resistance of stishovite with crack extension less than one micrometer

    PubMed Central

    Yoshida, Kimiko; Wakai, Fumihiro; Nishiyama, Norimasa; Sekine, Risako; Shinoda, Yutaka; Akatsu, Takashi; Nagoshi, Takashi; Sone, Masato

    2015-01-01

    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. PMID:26051871

  6. Diversity in deep-sea benthic macrofauna: the importance of local ecology, the larger scale, history and the Antarctic

    NASA Astrophysics Data System (ADS)

    Gage, John D.

    2004-07-01

    High diversity in macrobenthos in the deep sea still lacks satisfactory explanation, even if this richness may not be exceptional compared to that in coastal soft sediments. Explanations have assumed a highly ecologically interactive, saturated local community with co-existence controlled by either niche heterogeneity, or spatio-temporal heterogeneity embodying disturbance. All have failed to provide convincing support. Local/regional scale biodiversity relationships support the idea of local richness in macrobenthos being predominantly dependent on the larger, rather local scale. Local-scale ecological interactions seem unlikely to have overriding importance in co-existence of species in the deep sea, even for relatively abundant, 'core' species with wide distributions. Variety in observed larger-scale pattern and the strong inter-regional pattern, particularly in the poorly known southern hemisphere, seem to have a pluralistic causation. These include regional-scale barriers and extinctions (e.g., Arctic), and ongoing adaptive zone re-colonisation (e.g., Mediterranean), along with other historical constraints on speciation and migration of species caused by changes in ocean and ocean-basin geometry. At the global scale lack of knowledge of the Antarctic deep sea, for example, blocks coherent understanding of latitudinal species diversity gradients. We need to reconcile emerging understanding of large-scale historical variability in the deep-sea environment—with massive extinctions among microfossil indicators as recently as the Pliocene—to results from cladistic studies indicating ancient lineages, such as asellote isopods, that have evolved entirely within the deep sea. The degree to which the great age, diversity, and high degree of endemism in Antarctic shelf benthos might have enriched biodiversity in the adjacent deep seas basins remains unclear. Basin confluence with the Atlantic, Indian and Pacific Oceans may have encouraged northwards dispersion of

  7. MULTI-SCALED VULNERABILITY ANALYSES: IMPROVING DECISION-MAKING AT REGIONAL TO LOCAL LEVELS THROUGH PARTNERSHIP

    EPA Science Inventory

    Decision-makers at all scales are faced with setting priorities for both use of limited resources and for risk management. While there are all kinds of monitoring data and models to project conditions at different spatial and temporal scales, synthesized information to establish ...

  8. Localized Scale Coupling and New Educational Paradigms in Multiscale Mathematics and Science

    SciTech Connect

    Ingber, Marc; Vorobieff, Peter

    2014-03-14

    We have experimentally demonstrated how microscale phenomena affect suspended particle behavior on the mesoscale, and how particle group behavior on the mesoscale influences the macroscale suspension behavior. Semi-analytical and numerical methods to treat flows on different scales have been developed, and a framework to combine these scale-dependent treatment has been described.

  9. The MTSOCS: A Multidimensional Sense of Community Scale for Local Communities

    ERIC Educational Resources Information Center

    Prezza, Miretta; Pacilli, Maria Giuseppina; Barbaranelli, Claudio; Zampatti, Emanuela

    2009-01-01

    The aim of this study was to validate the Multidimensional Territorial Sense of Community Scale (MTSOCS), a new theory-driven sense of community scale referred to the geographical community. Starting from McMillan and Chavis' theoretical dimensions, five subscales (Membership, Shared Influence, Social Climate and Bonds, Help in Case of Need, and…

  10. Adaptation of a pattern-scaling approach for assessment of local (village/valley) scale water resources and related vulnerabilities in the Upper Indus Basin

    NASA Astrophysics Data System (ADS)

    Forsythe, Nathan; Kilsby, Chris G.; Fowler, Hayley J.; Archer, David R.

    2010-05-01

    sites for medium-scale infrastructure projects. These catchments are placed in their context within the hydrological regime classification using the spatial data and (remote sensing) observations as well as river gauging measurements. The study assesses the degree of similarity with the larger basins of the same hydrological regime. This assessment focuses on the measured response to observed climate variable anomalies. The smallest scale considered is comprised of a number of case studies at the ungauged village/valley scale. These examples are based on the delineation of areas to which specific communities (villages) have customary (riparian) water rights. These examples were suggested by non-governmental organisations working on grassroots economic development initiatives and small-scale infrastructure projects in the region. The direct observations available for these subcatchments are limited to spatial data (elevation, snow parameters). The challenge at this level is to accurately extrapolate areal values (precipitation, temperature, runoff) from point observations at the basin scale. The study assesses both the degree of similarity in the distribution of spatial parameters to the larger gauged basins and the interannual variability (spatial heterogeneity) of remotely-sensed snow cover and snow-water-equivalent at this subcatchment scale. Based upon the characterisation of spatial and interannual variability at these three spatial scales, the challenges facing local water resource managers and infrastructure operators are enumerated. Local vulnerabilities include, but are not limited to, varying thresholds in irrigation water requirements based on crop-type, minimum base flows for micro-hydropower generation during winter (high load) months and relatively small but growing demand for domestic water usage. In conclusion the study posits potential strategies for managing interannual variability and potential emerging trends. Suggested strategies are guided by the

  11. Hydrogen bonding asymmetric star-shape derivative of bile acid leads to supramolecular fibrillar aggregates that wrap into micrometer spheres.

    PubMed

    Myllymäki, Teemu T T; Nonappa; Yang, Hongjun; Liljeström, Ville; Kostiainen, Mauri A; Malho, Jani-Markus; Zhu, X X; Ikkala, Olli

    2016-09-14

    We report that star-shaped molecules with cholic acid cores asymmetrically grafted by low molecular weight polymers with hydrogen bonding end-groups undergo aggregation to nanofibers, which subsequently wrap into micrometer spherical aggregates with low density cores. Therein the facially amphiphilic cholic acid (CA) is functionalized by four flexible allyl glycidyl ether (AGE) side chains, which are terminated with hydrogen bonding 2-ureido-4[1H]pyrimidinone (UPy) end-groups as connected by hexyl spacers, denoted as CA(AGE6-C6H12-UPy)4. This wedge-shaped molecule is expected to allow the formation of a rich variety of solvent-dependent structures due to the complex interplay of interactions, enabled by its polar/nonpolar surface-active structure, the hydrophobicity of the CA in aqueous medium, and the possibility to control hydrogen bonding between UPy molecules by solvent selection. In DMSO, the surfactant-like CA(AGE6-C6H12-UPy)4 self-assembles into nanometer scale micelles, as expected due to its nonpolar CA apexes, solubilized AGE6-C6H12-UPy chains, and suppressed mutual hydrogen bonds between the UPys. Dialysis in water leads to nanofibers with lateral dimensions of 20-50 nm. This is explained by promoted aggregation as the hydrogen bonds between UPy molecules start to become activated, the reduced solvent dispersibility of the AGE-chains, and the hydrophobicity of CA. Finally, in pure water the nanofibers wrap into micrometer spheres having low density cores. In this case, strong complementary hydrogen bonds between UPy molecules of different molecules can form, thus promoting lateral interactions between the nanofibers, as allowed by the hydrophobic hexyl spacers. The wrapping is illustrated by transmission electron microscopy tomographic 3D reconstructions. More generally, we foresee hierarchically structured matter bridging the length scales from molecular to micrometer scale by sequentially triggering supramolecular interactions. PMID:27491728

  12. Local cost minimization in ant transport networks: from small-scale data to large-scale trade-offs.

    PubMed

    Bottinelli, A; van Wilgenburg, E; Sumpter, D J T; Latty, T

    2015-11-01

    Transport networks distribute resources and information in many human and biological systems. Their construction requires optimization and balance of conflicting criteria such as robustness against disruptions, transport efficiency and building cost. The colonies of the polydomous Australian meat ant Iridomyrmex purpureus are a striking example of such a decentralized network, consisting of trails that connect spatially separated nests. Here we study the rules that underlie network construction in these ants. We find that a simple model of network growth, which we call the minimum linking model (MLM), is sufficient to explain the growth of real ant colonies. For larger networks, the MLM shows a qualitative similarity with a Euclidean minimum spanning tree, prioritizing cost and efficiency over robustness. We introduce a variant of our model to show that a balance between cost, efficiency and robustness can be also reproduced at larger scales than ant colonies. Remarkably, such a balance is influenced by a parameter reflecting the specific features of the modelled transport system. The extended MLM could thus be a suitable source of inspiration for the construction of cheap and efficient transport networks with non-zero robustness, suggesting possible applications in the design of human-made networks. PMID:26490633

  13. Pneumatic System for Concentration of Micrometer-Size Lunar Soil

    NASA Technical Reports Server (NTRS)

    McKay, David; Cooper, Bonnie

    2012-01-01

    A report describes a size-sorting method to separate and concentrate micrometer- size dust from a broad size range of particles without using sieves, fluids, or other processes that may modify the composition or the surface properties of the dust. The system consists of four processing units connected in series by tubing. Samples of dry particulates such as lunar soil are introduced into the first unit, a fluidized bed. The flow of introduced nitrogen fluidizes the particulates and preferentially moves the finer grain sizes on to the next unit, a flat plate impactor, followed by a cyclone separator, followed by a Nuclepore polycarbonate filter to collect the dust. By varying the gas flow rate and the sizes of various orifices in the system, the size of the final and intermediate particles can be varied to provide the desired products. The dust can be collected from the filter. In addition, electron microscope grids can be placed on the Nuclepore filter for direct sampling followed by electron microscope characterization of the dust without further handling.

  14. Recent Developments for Sub-Quarter Micrometer Fabrication

    NASA Astrophysics Data System (ADS)

    Rousseaux, F.; Haghiri-Gosnet, A. M.; Chen, Y.; Ravets, M. F.; Launois, H.

    1992-12-01

    Resolution capability of synchrotron radiation based proximity lithography has been investigated in the sub-quarter micrometer range using an advanced X-ray stepper and high resolution SiC/W X-ray masks. High resolution tungsten gratings and single lines as small as 60 nm are now currently available. Such masks were tested by contact printing in the L2M lithography station implemented at Super-ACO synchrotron facility in Orsay-France. Also, the influence of diffraction on feature sizes was studied with 30-40 μm proximity gap using various positive and negative resists: PMMA, RAY-PF, SAL 601. It was found that 0.10 to 0.12 μm linewidths can be achieved for gratings and 0.15 to 0.20 μm for isolated lines. This resolution limit can be overpassed by a double exposure technique associated with a lateral mask-stage translation. Examples of feature size down to 80 nm were readily achieved at 40 μm gap.

  15. Experimental Study on Electrical Breakdown for Devices with Micrometer Gaps

    NASA Astrophysics Data System (ADS)

    Meng, Guodong; Cheng, Yonghong; Dong, Chengye; Wu, Kai

    2014-12-01

    The understanding of electrical breakdown in atmospheric air across micrometer gaps is critically important for the insulation design of micro & nano electronic devices. In this paper, planar aluminum electrodes with gaps ranging from 2 μm to 40 μm were fabricated by microelectromechanical system technology. The influence factors including gap width and surface dielectric states were experimentally investigated using the home-built test and measurement system. Results showed that for SiO2 layers the current sustained at 2-3 nA during most of the pre-breakdown period, and then rose rapidly to 10-30 nA just before breakdown due to field electron emission, followed by the breakdown. The breakdown voltage curves demonstrated three stages: (1) a constantly decreasing region (the gap width d < 5 μm), where the field emission effect played an important role just near breakdown, supplying enough initial electrons for the breakdown process; (2) a plateau region with a near constant breakdown potential (5 μm < d < 10 μm) (3) a region for large gaps that adhered to Paschen's curve (d > 10 μm). And the surface dielectric states including the surface resistivity and secondary electron yield were verified to be related to the propagation of discharge due to the interaction between initial electrons and dielectrics.

  16. Inhomogeneous Growth of Micrometer Thick Plasma Polymerized Films.

    PubMed

    Akhavan, Behnam; Menges, Bernhard; Förch, Renate

    2016-05-17

    Plasma polymerization is traditionally recognized as a homogeneous film-forming technique. It is nevertheless reasonable to ask whether micrometer thick plasma polymerized structures are really homogeneous across the film thickness. Studying the properties of the interfacial, near-the-substrate (NTS) region in plasma polymer films represents particular experimental challenges due to the inaccessibility of the buried layers. In this investigation, a novel non-destructive approach has been utilized to evaluate the homogeneity of plasma polymerized acrylic acid (PPAc) and 1,7-octadiene (PPOD) films in a single measurement. Studying the variations of refractive index throughout the depth of the films was facilitated by a home-built surface plasmon resonance (SPR)/optical waveguide (OWG) spectroscopy setup. It has been shown that the NTS layer of both PPAc and PPOD films exhibits a significantly lower refractive index than the bulk of the film that is believed to indicate a higher concentration of internal voids. Our results provide new insights into the growth mechanisms of plasma polymer films and challenge the traditional view that considers plasma polymers as homogeneous and continuous structures. PMID:27111265

  17. The Stickiness of Micrometer-sized Water-ice Particles

    NASA Astrophysics Data System (ADS)

    Gundlach, B.; Blum, J.

    2015-01-01

    Water ice is one of the most abundant materials in dense molecular clouds and in the outer reaches of protoplanetary disks. In contrast to other materials (e.g., silicates), water ice is assumed to be stickier due to its higher specific surface energy, leading to faster or more efficient growth in mutual collisions. However, experiments investigating the stickiness of water ice have been scarce, particularly in the astrophysically relevant micrometer-sized region and at low temperatures. In this work, we present an experimental setup to grow aggregates composed of μm-sized water-ice particles, which we used to measure the sticking and erosion thresholds of the ice particles at different temperatures between 114 K and 260 K. We show with our experiments that for low temperatures (below ~210 K), μm-sized water-ice particles stick below a threshold velocity of 9.6 m s-1, which is approximately 10 times higher than the sticking threshold of μm-sized silica particles. Furthermore, erosion of the grown ice aggregates is observed for velocities above 15.3 m s-1. A comparison of the experimentally derived sticking threshold with model predictions is performed to determine important material properties of water ice, i.e., the specific surface energy and the viscous relaxation time. Our experimental results indicate that the presence of water ice in the outer reaches of protoplanetary disks can enhance the growth of planetesimals by direct sticking of particles.

  18. INFLUENCE OF AGRICULTURAL PRACTICES ON MICROMETEOROLOGICAL SPATIAL VARIATIONS AT THE LOCAL AND REGIONAL SCALES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 sc...

  19. Local structures of high-entropy alloys (HEAs) on atomic scales: An overview

    DOE PAGESBeta

    Diao, Haoyan; Santodonato, Louis J.; Tang, Zhi; Egami, Takeshi; Liaw, Peter K.

    2015-01-01

    The high-entropy alloys, containing several elements mixed in equimolar or near-equimolar ratios, have shown exceptional engineering properties. Local structures on the atomic level are essential to understand the mechanical behaviors and related mechanisms. This article covers the local structure and stress on the atomic level are reviewed by the pair-distribution function of neutron-diffraction data, ab-initio molecular dynamics simulations, and the atomic probe microscopy.

  20. Measurements with Reticle Micrometer Performed by a New Double Stars Observing Group from Poland

    NASA Astrophysics Data System (ADS)

    Biskupski, Marcin; Banacka, Natalia; Cupryjak, Justyna; Malinowska, Malgorzata; Bujel, Kamil; Koltek, Zdzislaw; Mazur, Jaroslaw; Muskala, Marcin; Plotkowski, Lukasz; Prowans, Barlomiej; Szkaplewicz, Pawel

    2016-04-01

    Measurements of 19 double stars using a reticle micrometer eyepiece are reported. The observational program was held in spring and summer of 2015 as an extended workshop for a new double stars observing group from Szczecin, Poland. The goal of the program was to learn how to measure position angle and separation using a reticle micrometer eyepiece.

  1. Local heterogeneity and scaled dependence of eco-hydrology in mire

    NASA Astrophysics Data System (ADS)

    Nakayama, T.

    2011-12-01

    Japanese governments recently started nature conservation project to restore meandering former river channel in order to prevent invasive forest and to recover original ecosystem because various anthropogenic stressors have caused mire degradation in subarctic northern Japan such as drying and invasion of alder-dominant shrub forest. In order to predict effectiveness of this restoration, the author has so far developed the process-based National Integrated Catchment-based Eco-hydrology (NICE) model (Nakayama, 2008a, 2008b, 2010, 2011a, 2011b; Nakayama and Fujita, 2010; Nakayama and Hashimoto, 2011; Nakayama and Watanabe, 2004, 2006, 2008a, 2008b; Nakayama et al., 2006, 2007, 2010, 2011), which includes complex interactions between canopy, surface water, unsaturated water, aquifer, lake, and rivers. Because the model simulates the hydrologic cycle, elevation change, and vegetation succession processes iteratively including competition between native reed-sedge vegetation and invasive alder, it is possible to estimate nonlinear interaction between hydro-geomorphic and vegetation dynamics. In this study, the author further improved the model to evaluate positive feedback between heterogeneous drying and alder invasion in relation to stability and regime shift beyond previous researches about constant slope and its relation to regular pattern. In particular, he evaluated local heterogeneity of groundwater and surface water in both horizontal and vertical directions, and clarified relationship between microtopography about ridge-depression and hydrologic cycle about divergence-convergence in short-term period. This mechanism is also related to interaction between groundwater and inundated flow, scaled dependence of hydrologic cycle, and its effect on sediment deposition and vegetation change. These results will throw some light on two conflicting conceptualizations of peatland hydrology, so-called, shallow-flow and groundwater-flow models (Reeve et al., 2000), and bring

  2. A probabilistic model for the identification of confinement regimes and edge localized mode behavior, with implications to scaling laws

    SciTech Connect

    Verdoolaege, Geert; Van Oost, Guido

    2012-10-15

    Pattern recognition is becoming an important tool in fusion data analysis. However, fusion diagnostic measurements are often affected by considerable statistical uncertainties, rendering the extraction of useful patterns a significant challenge. Therefore, we assume a probabilistic model for the data and perform pattern recognition in the space of probability distributions. We show the considerable advantage of our method for identifying confinement regimes and edge localized mode behavior, and we discuss the potential for scaling laws.

  3. Placing Local Aggregations in a Larger-Scale Context: Hierarchical Modeling of Black-Footed Albatross Dispersion

    PubMed Central

    Jahncke, J.; Hyrenbach, K. D.

    2016-01-01

    At-sea surveys facilitate the study of the distribution and abundance of marine birds along standardized transects, in relation to changes in the local environmental conditions and large-scale oceanographic forcing. We analyzed the form and the intensity of black-footed albatross (Phoebastria nigripes: BFAL) spatial dispersion off central California, using five years (2004–2008) of vessel-based surveys of seven replicated survey lines. We related BFAL patchiness to local, regional and basin-wide oceanographic variability using two complementary approaches: a hypothesis-based model and an exploratory analysis. The former tested the strength and sign of hypothesized BFAL responses to environmental variability, within a hierarchical atmosphere—ocean context. The latter explored BFAL cross-correlations with atmospheric / oceanographic variables. While albatross dispersion was not significantly explained by the hierarchical model, the exploratory analysis revealed that aggregations were influenced by static (latitude, depth) and dynamic (wind speed, upwelling) environmental variables. Moreover, the largest BFAL patches occurred along the survey lines with the highest densities, and in association with shallow banks. In turn, the highest BFAL densities occurred during periods of negative Pacific Decadal Oscillation index values and low atmospheric pressure. The exploratory analyses suggest that BFAL dispersion is influenced by basin-wide, regional-scale and local environmental variability. Furthermore, the hypothesis-based model highlights that BFAL do not respond to oceanographic variability in a hierarchical fashion. Instead, their distributions shift more strongly in response to large-scale ocean—atmosphere forcing. Thus, interpreting local changes in BFAL abundance and dispersion requires considering diverse environmental forcing operating at multiple scales. PMID:27124491

  4. Placing Local Aggregations in a Larger-Scale Context: Hierarchical Modeling of Black-Footed Albatross Dispersion.

    PubMed

    Michael, P E; Jahncke, J; Hyrenbach, K D

    2016-01-01

    At-sea surveys facilitate the study of the distribution and abundance of marine birds along standardized transects, in relation to changes in the local environmental conditions and large-scale oceanographic forcing. We analyzed the form and the intensity of black-footed albatross (Phoebastria nigripes: BFAL) spatial dispersion off central California, using five years (2004-2008) of vessel-based surveys of seven replicated survey lines. We related BFAL patchiness to local, regional and basin-wide oceanographic variability using two complementary approaches: a hypothesis-based model and an exploratory analysis. The former tested the strength and sign of hypothesized BFAL responses to environmental variability, within a hierarchical atmosphere-ocean context. The latter explored BFAL cross-correlations with atmospheric / oceanographic variables. While albatross dispersion was not significantly explained by the hierarchical model, the exploratory analysis revealed that aggregations were influenced by static (latitude, depth) and dynamic (wind speed, upwelling) environmental variables. Moreover, the largest BFAL patches occurred along the survey lines with the highest densities, and in association with shallow banks. In turn, the highest BFAL densities occurred during periods of negative Pacific Decadal Oscillation index values and low atmospheric pressure. The exploratory analyses suggest that BFAL dispersion is influenced by basin-wide, regional-scale and local environmental variability. Furthermore, the hypothesis-based model highlights that BFAL do not respond to oceanographic variability in a hierarchical fashion. Instead, their distributions shift more strongly in response to large-scale ocean-atmosphere forcing. Thus, interpreting local changes in BFAL abundance and dispersion requires considering diverse environmental forcing operating at multiple scales. PMID:27124491

  5. Microwave conductance in random waveguides in the cross-over to Anderson localization and single-parameter scaling

    PubMed Central

    Shi, Zhou; Wang, Jing; Genack, Azriel Z.

    2014-01-01

    The nature of transport of electrons and classical waves in disordered systems depends upon the proximity to the Anderson localization transition between freely diffusing and localized waves. The suppression of average transport and the enhancement of relative fluctuations in conductance in one-dimensional samples with lengths greatly exceeding the localization length, , are related in the single-parameter scaling (SPS) theory of localization. However, the difficulty of producing an ensemble of statistically equivalent samples in which the electron wave function is temporally coherent has so-far precluded the experimental demonstration of SPS. Here we demonstrate SPS in random multichannel systems for the transmittance T of microwave radiation, which is the analog of the dimensionless conductance. We show that for , a single eigenvalue of the transmission matrix (TM) dominates transmission, and the distribution of the is Gaussian with a variance equal to the average of , as conjectured by SPS. For samples in the cross-over to localization, , we find a one-sided distribution for . This anomalous distribution is explained in terms of a charge model for the eigenvalues of the TM τ in which the Coulomb interaction between charges mimics the repulsion between the eigenvalues of TM. We show in the localization limit that the joint distribution of T and the effective number of transmission eigenvalues determines the probability distributions of intensity and total transmission for a single-incident channel. PMID:24516156

  6. Parallel, linear-scaling building-block and embedding method based on localized orbitals and orbital-specific basis sets.

    PubMed

    Seijo, Luis; Barandiarán, Zoila

    2004-10-01

    We present a linear scaling method for the energy minimization step of semiempirical and first-principles Hartree-Fock and Kohn-Sham calculations. It is based on the self-consistent calculation of the optimum localized orbitals of any localization method of choice and on the use of orbital-specific basis sets. The full set of localized orbitals of a large molecule is seen as an orbital mosaic where each tessera is made of only a few of them. The orbital tesserae are computed out of a set of embedded cluster pseudoeigenvalue coupled equations which are solved in a building-block self-consistent fashion. In each iteration, the embedded cluster equations are solved independently of each other and, as a result, the method is parallel at a high level of the calculation. In addition to full system calculations, the method enables to perform simpler, much less demanding embedded cluster calculations, where only a fraction of the localized molecular orbitals are variational while the rest is frozen, taking advantage of the transferability of the localized orbitals of a given localization method between similar molecules. Monitoring single point energy calculations of large poly(ethylene oxide) molecules and three dimensional carbon monoxide clusters using an extended Huckel Hamiltonian are presented. PMID:15473725

  7. Contrasting non-local effects of shoreline stabilization methods in a model of large-scale coastline morphodynamics

    NASA Astrophysics Data System (ADS)

    Ells, K. D.; Murray, A.

    2011-12-01

    Advances in the understanding of the wave-angle dependence of large-scale sandy coastline evolution have allowed exploratory modeling investigations into the emergence of large-scale coastline features such as sandwaves, capes, and spits; the possible responses of these complex coastline shapes to changing wave climates; and the dynamic coupling of natural coastal processes with economic decisions for shoreline stabilization. Recent numerical-model experiments found that beach nourishment on a complex-shaped coastline can significantly alter rates of shoreline change on spatial scales commensurate with the alongshore distance of adjacent features (up to 100 km). While the effect of beach nourishment is to fix a given shoreline position while maintaining a saturated sediment flux locally, hard structured stabilization methods (e.g. seawalls, revetments, or groynes) tend to reduce local alongshore fluxes of sediment. In long-term numerical experiments (decades to centuries), the effects of local stabilization propagate both progressively alongshore and through a non-local mechanism (wave shadowing). Comparing these two fundamentally different methods of shoreline stabilization on various locations along a cuspate cape coastline, we find that both the local and regional responses to hard structures greatly contrast those of beach nourishment. Sustained nourishment near the tip of a cape tends to extend the cape both seaward and in the direction of alongshore flux, increasing the effect that wave shadowing would have otherwise had on distant shorelines, leading to a negative (landward) perturbation to an adjacent cape. A hard structure at the same location, however, completely fixes the cape's original location, decreasing the shadowing effect and resulting in a positive (seaward) perturbation to the downdrift cape. Recent extensions of this work examine how different stabilization methods affect long-term coastline morphodynamics on other coastline types, starting

  8. DEVELOPMENT OF CFD SIMULATION APPLICATIONS FOR LOCAL-SCALE AREAS AND POTENTIAL INTERFACE WITH MESOSCALE MODELS

    EPA Science Inventory

    The presentation summarizes developments of ongoing applications of fine-scale (geometry specific) CFD simulations to urban areas within atmospheric boundary layers. Enabling technology today and challenges for the future are discussed. There is a challenging need to develop a ...

  9. Large Scale Chromosome Folding Is Stable against Local Changes in Chromatin Structure

    PubMed Central

    Therizols, Pierre

    2016-01-01

    Characterizing the link between small-scale chromatin structure and large-scale chromosome folding during interphase is a prerequisite for understanding transcription. Yet, this link remains poorly investigated. Here, we introduce a simple biophysical model where interphase chromosomes are described in terms of the folding of chromatin sequences composed of alternating blocks of fibers with different thicknesses and flexibilities, and we use it to study the influence of sequence disorder on chromosome behaviors in space and time. By employing extensive computer simulations, we thus demonstrate that chromosomes undergo noticeable conformational changes only on length-scales smaller than 105 basepairs and time-scales shorter than a few seconds, and we suggest there might exist effective upper bounds to the detection of chromosome reorganization in eukaryotes. We prove the relevance of our framework by modeling recent experimental FISH data on murine chromosomes. PMID:27295501

  10. Energy Decomposition Analysis Based on Absolutely Localized Molecular Orbitals for Large-Scale Density Functional Theory Calculations in Drug Design.

    PubMed

    Phipps, M J S; Fox, T; Tautermann, C S; Skylaris, C-K

    2016-07-12

    We report the development and implementation of an energy decomposition analysis (EDA) scheme in the ONETEP linear-scaling electronic structure package. Our approach is hybrid as it combines the localized molecular orbital EDA (Su, P.; Li, H. J. Chem. Phys., 2009, 131, 014102) and the absolutely localized molecular orbital EDA (Khaliullin, R. Z.; et al. J. Phys. Chem. A, 2007, 111, 8753-8765) to partition the intermolecular interaction energy into chemically distinct components (electrostatic, exchange, correlation, Pauli repulsion, polarization, and charge transfer). Limitations shared in EDA approaches such as the issue of basis set dependence in polarization and charge transfer are discussed, and a remedy to this problem is proposed that exploits the strictly localized property of the ONETEP orbitals. Our method is validated on a range of complexes with interactions relevant to drug design. We demonstrate the capabilities for large-scale calculations with our approach on complexes of thrombin with an inhibitor comprised of up to 4975 atoms. Given the capability of ONETEP for large-scale calculations, such as on entire proteins, we expect that our EDA scheme can be applied in a large range of biomolecular problems, especially in the context of drug design. PMID:27248370

  11. Extreme events in total ozone: Spatio-temporal analysis from local to global scale

    NASA Astrophysics Data System (ADS)

    Rieder, Harald E.; Staehelin, Johannes; Maeder, Jörg A.; Ribatet, Mathieu; di Rocco, Stefania; Jancso, Leonhardt M.; Peter, Thomas; Davison, Anthony C.

    2010-05-01

    dynamics (NAO, ENSO) on total ozone is a global feature in the northern mid-latitudes (Rieder et al., 2010c). In a next step frequency distributions of extreme events are analyzed on global scale (northern and southern mid-latitudes). A specific focus here is whether findings gained through analysis of long-term European ground based stations can be clearly identified as a global phenomenon. By showing results from these three types of studies an overview of extreme events in total ozone (and the dynamical and chemical features leading to those) will be presented from local to global scales. References: Coles, S.: An Introduction to Statistical Modeling of Extreme Values, Springer Series in Statistics, ISBN:1852334592, Springer, Berlin, 2001. Ribatet, M.: POT: Modelling peaks over a threshold, R News, 7, 34-36, 2007. Rieder, H.E., Staehelin, J., Maeder, J.A., Ribatet, M., Stübi, R., Weihs, P., Holawe, F., Peter, T., and A.D., Davison (2010): Extreme events in total ozone over Arosa - Part I: Application of extreme value theory, to be submitted to ACPD. Rieder, H.E., Staehelin, J., Maeder, J.A., Ribatet, M., Stübi, R., Weihs, P., Holawe, F., Peter, T., and A.D., Davison (2010): Extreme events in total ozone over Arosa - Part II: Fingerprints of atmospheric dynamics and chemistry and effects on mean values and long-term changes, to be submitted to ACPD. Rieder, H.E., Jancso, L., Staehelin, J., Maeder, J.A., Ribatet, Peter, T., and A.D., Davison (2010): Extreme events in total ozone over the northern mid-latitudes: A case study based on long-term data sets from 5 ground-based stations, in preparation. Staehelin, J., Renaud, A., Bader, J., McPeters, R., Viatte, P., Hoegger, B., Bugnion, V., Giroud, M., and Schill, H.: Total ozone series at Arosa (Switzerland): Homogenization and data comparison, J. Geophys. Res., 103(D5), 5827-5842, doi:10.1029/97JD02402, 1998a. Staehelin, J., Kegel, R., and Harris, N. R.: Trend analysis of the homogenized total ozone series of Arosa

  12. Titan's 5 micrometers spectral window: carbon monoxide and the albedo of the surface

    NASA Technical Reports Server (NTRS)

    Noll, K. S.; Geballe, T. R.; Knacke, R. F.; Pendleton, Y. J.

    1996-01-01

    We have measured the spectrum of Titan near 5 micrometers and have found it to be dominated by absorption from the carbon monoxide 1-0 vibration-rotation band. The position of the band edge allows us to constrain the abundance of CO in the atmosphere and/or the location of the reflecting layer in the atmosphere. In the most likely case, 5 micrometers radiation is reflected from the surface and the mole fraction of CO in the atmosphere is qCO=10(+10/-5) ppm, significantly lower than previous estimates for tropospheric CO. The albedo of the reflecting layer is approximately 0.07(+0.02/-0.01) in the 5 micrometers continuum outside the CO band. The 5 micrometers albedo is consistent with a surface of mixed ice and silicates similar to the icy Galilean satellites. Organic solids formed in simulated Titan conditions can also produce similar albedos at 5 micrometers.

  13. Titan's 5 micrometers spectral window: carbon monoxide and the albedo of the surface.

    PubMed

    Noll, K S; Geballe, T R; Knacke, R F; Pendleton, Y J

    1996-12-01

    We have measured the spectrum of Titan near 5 micrometers and have found it to be dominated by absorption from the carbon monoxide 1-0 vibration-rotation band. The position of the band edge allows us to constrain the abundance of CO in the atmosphere and/or the location of the reflecting layer in the atmosphere. In the most likely case, 5 micrometers radiation is reflected from the surface and the mole fraction of CO in the atmosphere is qCO=10(+10/-5) ppm, significantly lower than previous estimates for tropospheric CO. The albedo of the reflecting layer is approximately 0.07(+0.02/-0.01) in the 5 micrometers continuum outside the CO band. The 5 micrometers albedo is consistent with a surface of mixed ice and silicates similar to the icy Galilean satellites. Organic solids formed in simulated Titan conditions can also produce similar albedos at 5 micrometers. PMID:11539388

  14. Automatic computation of moment magnitudes for small earthquakes and the scaling of local to moment magnitude

    NASA Astrophysics Data System (ADS)

    Edwards, Benjamin; Allmann, Bettina; Fäh, Donat; Clinton, John

    2010-10-01

    Moment magnitudes (MW) are computed for small and moderate earthquakes using a spectral fitting method. 40 of the resulting values are compared with those from broadband moment tensor solutions and found to match with negligible offset and scatter for available MW values of between 2.8 and 5.0. Using the presented method, MW are computed for 679 earthquakes in Switzerland with a minimum ML = 1.3. A combined bootstrap and orthogonal L1 minimization is then used to produce a scaling relation between ML and MW. The scaling relation has a polynomial form and is shown to reduce the dependence of the predicted MW residual on magnitude relative to an existing linear scaling relation. The computation of MW using the presented spectral technique is fully automated at the Swiss Seismological Service, providing real-time solutions within 10 minutes of an event through a web-based XML database. The scaling between ML and MW is explored using synthetic data computed with a stochastic simulation method. It is shown that the scaling relation can be explained by the interaction of attenuation, the stress-drop and the Wood-Anderson filter. For instance, it is shown that the stress-drop controls the saturation of the ML scale, with low-stress drops (e.g. 0.1-1.0 MPa) leading to saturation at magnitudes as low as ML = 4.

  15. Travel determinants and multi-scale transferability of national activity patterns to local populations

    SciTech Connect

    Henson, Kriste M; Gou; ias, Konstadinos G

    2010-11-30

    The ability to transfer national travel patterns to a local population is of interest when attempting to model megaregions or areas that exceed metropolitan planning organization (MPO) boundaries. At the core of this research are questions about the connection between travel behavior and land use, urban form, and accessibility. As a part of this process, a group of land use variables have been identified to define activity and travel patterns for individuals and households. The 2001 National Household Travel Survey (NHTS) participants are divided into categories comprised of a set of latent cluster models representing persons, travel, and land use. These are compared to two sets of cluster models constructed for two local travel surveys. Comparison of means statistical tests are used to assess differences among sociodemographic groups residing in localities with similar land uses. The results show that the NHTS and the local surveys share mean population activity and travel characteristics. However, these similarities mask behavioral heterogeneity that are shown when distributions of activity and travel behavior are examined. Therefore, data from a national household travel survey cannot be used to model local population travel characteristics if the goal to model the actual distributions and not mean travel behavior characteristics.

  16. The role of local environment and geographical distance in determining community composition of arbuscular mycorrhizal fungi at the landscape scale

    PubMed Central

    Hazard, Christina; Gosling, Paul; van der Gast, Christopher J; Mitchell, Derek T; Doohan, Fiona M; Bending, Gary D

    2013-01-01

    Arbuscular fungi have a major role in directing the functioning of terrestrial ecosystems yet little is known about their biogeographical distribution. The Baas-Becking hypothesis (‘everything is everywhere, but, the environment selects') was tested by investigating the distribution of arbuscular mycorrhizal fungi (AMF) at the landscape scale and the influence of environmental factors and geographical distance in determining community composition. AMF communities in Trifolium repens and Lolium perenne roots were assessed in 40 geographically dispersed sites in Ireland representing different land uses and soil types. Field sampling and laboratory bioassays were used, with AMF communities characterised using 18S rRNA terminal-restriction fragment length polymorphism. Landscape-scale distribution of AMF was driven by the local environment. AMF community composition was influenced by abiotic variables (pH, rainfall and soil type), but not land use or geographical distance. Trifolium repens and L. perenne supported contrasting communities of AMF, and the communities colonising each plant species were consistent across pasture habitats and over distance. Furthermore, L. perenne AMF communities grouped by soil type within pasture habitats. This is the largest and most comprehensive study that has investigated the landscape-scale distribution of AMF. Our findings support the Baas-Becking hypothesis at the landscape scale and demonstrate the strong influence the local environment has on determining AMF community composition. PMID:23096401

  17. Linking sediment connectivity to remotely sensed, reach-scale morphology identifies correlations between network-scale sediment regimes and local river forms and processes

    NASA Astrophysics Data System (ADS)

    Schmitt, R. J. P.; Bizzi, S.; Castelletti, A.

    2015-12-01

    Connectivity describes the transport between sediment sources and sinks in fluvial networks, defining source-sink relations in the domains of sediment flux, delivery times, and supplied grain sizes. Connectivity embalms both sediment deliveries to individual reaches and sediment transport regimes on the network scale, and is a central driver behind fluvial biotic and abiotic processes, and related ecosystem services. Yet, river basin management is missing quantitative tools for studying connectivity in larger fluvial networks. With the CASCADE (Catchment Sediment Connectivity and Delivery) model we recently introduced a framework that quantifies sediment deliveries from each sediment source to all the connected sinks as individual cascading processes. This allows quantifying all domains of sediment connectivity at the reach scale as well as analyzing the resulting network-scale sediment regimes. CASCADE is applicable also for very large and poorly monitored river networks. We implement CASCADE for a large river network (7500 km) in SE Asia and quantify all domains of connectivity for all reaches in the network. We derive some relevant river morphological features for a subset of reaches in the network from high resolution satellite imagery and find significant links between observed forms and sediment connectivity information derived from CASCADE. CASCADE opens up novel opportunities to clarify the link between network scale sediment regimes and local morphologic processes and forms. This is of concrete interest for river basin management because CASCADE allows to assess impacts of anthropic disturbance on river sediment regimes and to anticipate resulting changes in local fluvial processes and related eco-system services.

  18. THE STICKINESS OF MICROMETER-SIZED WATER-ICE PARTICLES

    SciTech Connect

    Gundlach, B.; Blum, J.

    2015-01-01

    Water ice is one of the most abundant materials in dense molecular clouds and in the outer reaches of protoplanetary disks. In contrast to other materials (e.g., silicates), water ice is assumed to be stickier due to its higher specific surface energy, leading to faster or more efficient growth in mutual collisions. However, experiments investigating the stickiness of water ice have been scarce, particularly in the astrophysically relevant micrometer-sized region and at low temperatures. In this work, we present an experimental setup to grow aggregates composed of μm-sized water-ice particles, which we used to measure the sticking and erosion thresholds of the ice particles at different temperatures between 114 K and 260 K. We show with our experiments that for low temperatures (below ∼210 K), μm-sized water-ice particles stick below a threshold velocity of 9.6 m s{sup –1}, which is approximately 10 times higher than the sticking threshold of μm-sized silica particles. Furthermore, erosion of the grown ice aggregates is observed for velocities above 15.3 m s{sup –1}. A comparison of the experimentally derived sticking threshold with model predictions is performed to determine important material properties of water ice, i.e., the specific surface energy and the viscous relaxation time. Our experimental results indicate that the presence of water ice in the outer reaches of protoplanetary disks can enhance the growth of planetesimals by direct sticking of particles.

  19. Do we really need large spectral libraries for the assessment of soil organic carbon at local scale?

    NASA Astrophysics Data System (ADS)

    Guerrero, César; Wetterlind, Johanna; Stenberg, Bo; Viscarra Rossel, Raphael A.; Zornoza, Raúl; Maestre, Fernando T.; Mouazen, Abdul M.; Kuang, Boyan; Damián Ruiz-Sinoga, José; Gabarrón-Galeote, Miguel A.

    2014-05-01

    Spiking is an approach to improve the accuracy of large-scale spectroscopic models when they are used to predict at local scale. But, if models are to be spiked, do we really need large-sized spectral libraries? Different calibrations relating the SOC and NIR spectra were obtained using PLS as regression method: i) model #1: local-scale model (n=40); ii) model #2: local-scale model (n=88); iii) model #3: provincial-scale model (n=147); iv) model #4: provincial-scale model, constructed with 50% of samples used in model #3 (n=73); v) model #5: provincial-scale model, constructed with 25% of samples used in model #3 (n=36); vi) model #6: national-scale model (n=1096); vii) model #7: national-scale model, constructed with 33% of samples used in model #6 (n=362). Each of these models was used to predict the SOC contents in target site samples. In this work, nine target sites were evaluated. Each target site is a relatively small area (from several hectares to a few square kilometers), where a dense sampling was made. The coefficient of the determination (R2), root mean square error of prediction (RMSEP), bias, standard error of prediction (SEP) and the ratio of performance to deviance (RPD) were calculated pooling the predictions of the nine target sites. In overall, more than 900 local samples were predicted. The highest R2 values were obtained with the national-scale models (R2 >0.85), and the lowest R2 values were obtained with the models of small size. In general, the RMSEP tended to decrease with the increase of the models size. However, the predictions obtained with the large-sized models were clearly biased, and despite the high R2 values, the RPD values were below 1.2. We also obtained predictions when these models were spiked with eight local samples (i.e., from the target site). After spiking, the predictions obtained with the small-sized models were substantially improved. As example of the changes due to spiking, the predictions obtained with the smallest

  20. Lazy Checkpointing : Exploiting Temporal Locality in Failures to Mitigate Checkpointing Overheads on Extreme-Scale Systems

    SciTech Connect

    Tiwari, Devesh; Gupta, Saurabh; Vazhkudai, Sudharshan S

    2014-01-01

    Continuing increase in the computational power of supercomputers has enabled large-scale scientific applications in the areas of astrophysics, fusion, climate and combustion to run larger and longer-running simulations, facilitating deeper scientific insights. However, these long-running simulations are often interrupted by multiple system failures. Therefore, these applications rely on ``checkpointing'' as a resilience mechanism to store application state to permanent storage and recover from failures. \\\\ \\indent Unfortunately, checkpointing incurs excessive I/O overhead on supercomputers due to large size of checkpoints, resulting in a sub-optimal performance and resource utilization. In this paper, we devise novel mechanisms to show how checkpointing overhead can be mitigated significantly by exploiting the temporal characteristics of system failures. We provide new insights and detailed quantitative understanding of the checkpointing overheads and trade-offs on large-scale machines. Our prototype implementation shows the viability of our approach on extreme-scale machines.

  1. Scaling theory of magnetoresistance and carrier localization in Ga1-xMnxAs.

    PubMed

    Moca, C P; Sheu, B L; Samarth, N; Schiffer, P; Janko, B; Zarand, G

    2009-04-01

    We compare experimental resistivity data on Ga1-xMnxAs films with theoretical calculations using a scaling theory for strongly disordered ferromagnets. The characteristic features of the temperature dependent resistivity can be quantitatively understood through this approach as originating from the close vicinity of the metal-insulator transition. However, accounting for thermal fluctuations is crucial for a quantitative description of the magnetic field induced changes in resistance. While the noninteracting scaling theory is in reasonable agreement with the data, we find clear evidence for interaction effects at low temperatures. PMID:19392399

  2. Dynamics of Choice: Relative Rate and Amount Affect Local Preference at Three Different Time Scales

    ERIC Educational Resources Information Center

    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…

  3. Titan's Aerosol and Stratospheric Ice Opacities Between 18 and 500 Micrometers: Vertical and Spectral Characteristics from Cassini CIRS

    NASA Technical Reports Server (NTRS)

    Anderson, Carrie M.; Samuelson, Robert E.

    2011-01-01

    Vertical distributions and spectral characteristics of Titan's photochemical aerosol and stratospheric ices are determined between 20 and 560 per centimeter (500-18 micrometers) from the Cassini Composite Infrared Spectrometer (CIRS). Results are obtained for latitudes of 15 N, 15 S, and 58 S, where accurate temperature profiles can be independently determined. In addition, estimates of aerosol and ice abundances at 62 N relative to those at 15 S are derived. Aerosol abundances are comparable at the two latitudes, but stratospheric ices are approximately 3 times more abundant at 62 N than at 15 S. Generally, nitrile ice clouds (probably HCN and HC3N), as inferred from a composite emission feature at approximately 160 per centimeter, appear to be located over a narrow altitude range in the stratosphere centered at approximately 90 km. Although most abundant at high northern latitudes, these nitrile ice clouds extend down through low latitudes and into mid southern latitudes, at least as far as 58 S. There is some evidence of a second ice cloud layer at approximately 60 km altitude at 58 S associated with an emission feature at approximately 80 per centimeter. We speculate that the identify of this cloud may be due to C2H6 ice, which in the vapor phase is the most abundant hydrocarbon (next to CH4) in the stratosphere of Titan. Unlike the highly restricted range of altitudes (50-100 km) associated with organic condensate clouds, Titan's photochemical aerosol appears to be well-mixed from the surface to the top of the stratosphere near an altitude of 300 km, and the spectral shape does not appear to change between 15 N and 58 S latitude. The ratio of aerosol-to-gas scale heights range from 1.3-2.4 at about 160 km to 1.1-1.4 at 300 km, although there is considerable variability with latitude, The aerosol exhibits a very broad emission feature peaking at approximately 140 per centimeter. Due to its extreme breadth and low wavenumber, we speculate that this feature may

  4. A local scale assessment of the climate change sensitivity of snow in Pyrenean ski resorts

    NASA Astrophysics Data System (ADS)

    Pesado, Cristina; Pons, Marc; Vilella, Marc; López-Moreno, Juan Ignacio

    2016-04-01

    The Pyrenees host one of the largest ski area in Europe after the Alps that encompasses the mountain area of the south of France, the north of Spain and the small country of Andorra. In this region, winter tourism is one of the main source of income and driving force of local development on these mountain communities. However, this activity was identified as one of the most vulnerable to a future climate change due to the projected decrease of natural snow and snowmaking capacity. However, within the same ski resorts different areas showed to have a very different vulnerability within the same resort based on the geographic features of the area and the technical management of the slopes. Different areas inside a same ski resort could have very different vulnerability to future climate change based on aspect, steepness or elevation. Furthermore, the technical management of ski resorts, such as snowmaking and grooming were identified to have a significant impact on the response of the snowpack in a warmer climate. In this line, two different ski resorts were deeply analyzed taken into account both local geographical features as well as the effect of the technical management of the runs. Principal Component Analysis was used to classify the main areas of the resort based on the geographic features (elevation, aspect and steepness) and identify the main representative areas with different local features. Snow energy and mass balance was simulated in the different representative areas using the Cold Regions Hydrological Model (CRHM) assuming different magnitudes of climate warming (increases of 2°C and 4°C in the mean winter temperature) both in natural conditions and assuming technical management of the slopes. Theses first results showed the different sensitivity and vulnerability to climate changes based on the local geography of the resort and the management of the ski runs, showing the importance to include these variables when analyzing the local vulnerability

  5. Regional- and local-scale variations in benthic megafaunal composition at the Arctic deep-sea observatory HAUSGARTEN

    NASA Astrophysics Data System (ADS)

    Taylor, J.; Krumpen, T.; Soltwedel, T.; Gutt, J.; Bergmann, M.

    2016-02-01

    The Long-Term Ecological Research (LTER) observatory HAUSGARTEN, in the eastern Fram Strait, provides us the valuable ability to study the composition of benthic megafaunal communities through the analysis of seafloor photographs. This, in combination with extensive sampling campaigns, which have yielded a unique data set on faunal, bacterial, biogeochemical and geological properties, as well as on hydrography and sedimentation patterns, allows us to address the question of why variations in megafaunal community structure and species distribution exist within regional (60-110 km) and local (<4 km) scales. Here, we present first results from the latitudinal HAUSGARTEN gradient, consisting of three different stations (N3, HG-IV, S3) between 78°30‧N and 79°45‧N (2351-2788 m depth), obtained via the analysis of images acquired by a towed camera (OFOS-Ocean Floor Observation System) in 2011. We assess variability in megafaunal densities, species composition and diversity as well as biotic and biogenic habitat features, which may cause the patterns observed. While there were significant regional-scale differences in megafaunal composition and densities between the stations (N3=26.74±0.63; HG-IV=11.21±0.25; S3=18.34±0.39 individuals m-2), significant local differences were only found at HG-IV. Regional-scale variations may be due to the significant differences in ice coverage at each station as well as the different quantities of protein available, whereas local-scale differences at HG-IV may be a result of variation in bottom topography or factors not yet identified.

  6. Large and local-scale influences on physical and chemical characteristics of coastal waters of Western Europe during winter

    NASA Astrophysics Data System (ADS)

    Tréguer, Paul; Goberville, Eric; Barrier, Nicolas; L'Helguen, Stéphane; Morin, Pascal; Bozec, Yann; Rimmelin-Maury, Peggy; Czamanski, Marie; Grossteffan, Emilie; Cariou, Thierry; Répécaud, Michel; Quéméner, Loic

    2014-11-01

    There is now a strong scientific consensus that coastal marine systems of Western Europe are highly sensitive to the combined effects of natural climate variability and anthropogenic climate change. However, it still remains challenging to assess the spatial and temporal scales at which climate influence operates. While large-scale hydro-climatic indices, such as the North Atlantic Oscillation (NAO) or the East Atlantic Pattern (EAP) and the weather regimes such as the Atlantic Ridge (AR), are known to be relevant predictors of physical processes, changes in coastal waters can also be related to local hydro-meteorological and geochemical forcing. Here, we study the temporal variability of physical and chemical characteristics of coastal waters located at about 48°N over the period 1998-2013 using (1) sea surface temperature, (2) sea surface salinity and (3) nutrient concentration observations for two coastal sites located at the outlet of the Bay of Brest and off Roscoff, (4) river discharges of the major tributaries close to these two sites and (5) regional and local precipitation data over the region of interest. Focusing on the winter months, we characterize the physical and chemical variability of these coastal waters and document changes in both precipitation and river runoffs. Our study reveals that variability in coastal waters is connected to the large-scale North Atlantic atmospheric circulation but is also partly explained by local river influences. Indeed, while the NAO is strongly related to changes in sea surface temperature at the Brest and Roscoff sites, the EAP and the AR have a major influence on precipitations, which in turn modulate river discharges that impact sea surface salinity at the scale of the two coastal stations.

  7. Local Navajo Norms for the Wechsler Intelligence Scale for Children: Third Edition.

    ERIC Educational Resources Information Center

    Tempest, Phyllis

    1998-01-01

    A project developed Navajo norms for the Wechsler Intelligence Scale for Children, Third Edition (WISC-III). Urban Navajo students and those who were proficient in English had higher WISC-III verbal scores than rural Navajo students and those who were functional in English. English-language proficiency did not affect scores on nonverbal…

  8. Biotic and abiotic controls of argentine ant invasion success at local and landscape scales

    USGS Publications Warehouse

    Menke, S.B.; Fisher, R.N.; Jetz, W.; Holway, D.A.

    2007-01-01

    Although the ecological success of introduced species hinges on biotic interactions and physical conditions, few experimental studies - especially on animals - have simultaneously investigated the relative importance of both types of factors. The lack of such research may stem from the common assumption that native and introduced species exhibit similar environmental tolerances. Here we combine experimental and spatial modeling approaches (1) to determine the relative importance of biotic and abiotic controls of Argentine ant (Linepithema humile) invasion success, (2) to examine how the importance of these factors changes with spatial scale in southern California (USA), and (3) to assess how Argentine ants differ from native ants in their environmental tolerances. A factorial field experiment that combined native ant removal with irrigation revealed that Argentine ants failed to invade any dry plots (even those lacking native ants) but readily invaded all moist plots. Native ants slowed the spread of Argentine ants into irrigated plots but did not prevent invasion. In areas without Argentine ants, native ant species showed variable responses to irrigation. At the landscape scale, Argentine ant occurrence was positively correlated with minimum winter temperature (but not precipitation), whereas native ant diversity increased with precipitation and was negatively correlated with minimum winter temperature. These results are of interest for several reasons. First, they demonstrate that fine-scale differences in the physical environment can eclipse biotic resistance from native competitors in determining community susceptibility to invasion. Second, our results illustrate surprising complexities with respect to how the abiotic factors limiting invasion can change with spatial scale, and third, how native and invasive species can differ in their responses to the physical environment. Idiosyncratic and scale-dependent processes complicate attempts to forecast where

  9. The 2 micrometer plasmid stability system: analyses of the interactions among plasmid- and host-encoded components.

    PubMed

    Velmurugan, S; Ahn, Y T; Yang, X M; Wu, X L; Jayaram, M

    1998-12-01

    The stable inheritance of the 2 micrometer plasmid in a growing population of Saccharomyces cerevisiae is dependent on two plasmid-encoded proteins (Rep1p and Rep2p), together with the cis-acting locus REP3 (STB). In this study we demonstrate that short carboxy-terminal deletions of Rep1p and Rep2p severely diminish their normal capacity to localize to the yeast nucleus. The nuclear targeting, as well as their functional role in plasmid partitioning, can be restored by the addition of a nuclear localization sequence to the amino or the carboxy terminus of the shortened Rep proteins. Analyses of deletion derivatives of the Rep proteins by using the in vivo dihybrid genetic test in yeast, as well as by glutathione S-transferase fusion trapping assays in vitro demonstrate that the amino-terminal portion of Rep1p (ca. 150 amino acids long) is responsible for its interactions with Rep2p. In a monohybrid in vivo assay, we have identified Rep1p, Rep2p, and a host-encoded protein, Shf1p, as being capable of interacting with the STB locus. The Shf1 protein expressed in Escherichia coli can bind with high specificity to the STB sequence in vitro. In a yeast strain deleted for the SHF1 locus, a 2 micrometer circle-derived plasmid shows relatively poor stability. PMID:9819432

  10. Impact of land use change on hydrological processes and water resources in Benin - from local scale measurements to interdisciplinary scenario modeling on regional scale

    NASA Astrophysics Data System (ADS)

    Diekkrüger, Bernd; Giertz, Simone; Steup, Gero

    2010-05-01

    In the past 50 years, West Africa has experienced large land-use changes including deforestation, overgrazing and land reclamation. Land use change may have both immediate and long-lasting impacts on hydrological processes and the local and regional water balance. With the ongoing population growth and socio-economic problems in the region this land use change trend will continue or even aggravate in future. Therefore an assessment of the impact of future land use change on the hydrological process is of utmost importance, especially in combination with climate change impact studies. A prerequisite for this assessment is that the hydrologic processes in the region have to be understood in detail and calibrated and validated models for a scenario analyses are available. In recent years large progress in assessing land use change impacts on hydrological processes has been achieved with experimental studies and scenario analysis using hydrological models. While the bulk of investigations has been carried out in the temperate climate zones, only few field studies and very few model applications have been performed in the tropical environment. The region of the sub-humid tropical West Africa, has been rarely investigated in terms of hydrological processes and land use change impacts. In the presented study the impact of land use change on the hydrological processes and the water balance in central Benin (Upper Ouémé catchment) is analyzed using a multiscale approach. First, local scale investigations (field and laboratory investigations, physically-based modeling) were carried out intensively in a well equipped experimental catchment to get a thorough understanding of the hydrological processes in the region. Using the findings a conceptual model (UHP-HRU) was developed and applied on regional scale. The model was validated in catchments with different land use conditions in order to proof its applicably for a land use change scenario analysis. The validated model was

  11. Large-scale atmospheric circulation and local particulate matter concentrations in Bavaria - from current observations to future projections

    NASA Astrophysics Data System (ADS)

    Beck, Christoph; Weitnauer, Claudia; Brosy, Caroline; Hald, Cornelius; Lochbihler, Kai; Siegmund, Stefan; Jacobeit, Jucundus

    2016-04-01

    Particulate matter with an aerodynamic diameter of 10 μm or less (PM10) may have distinct adverse effects on human health. Spatial and temporal variations in PM10 concentrations reflect local emission rates, but are as well influenced by the local and synoptic-scale atmospheric conditions. Against this background, it can be furthermore argued that potential future climate change and associated variations in large-scale atmospheric circulation and local meteorological parameters will probably provoke corresponding changes in future PM10 concentration levels. The DFG-funded research project „Particulate matter and climate change in Bavaria" aimed at establishing quantitative relationships between daily and monthly PM10 indices at different Bavarian urban stations and the corresponding large-scale atmospheric circulation as well as local meteorological conditions. To this end, several statistical downscaling approaches have been developed for the period 1980 to 2011. PM10 data from 19 stations from the air quality monitoring network (LÜB) of the Bavarian Environmental Agency (LfU) have been utilized as predictands. Large-scale atmospheric gridded data from the NCEP/NCAR reanalysis data base and local meteorological observational data provided by the German Meteorological Service (DWD) served as predictors. The downscaling approaches encompass the synoptic downscaling of daily PM10 concentrations and several multivariate statistical models for the estimation of daily and monthly PM10, i.e.monthly mean and number of days exceeding a certain PM10 concentration threshold. Both techniques utilize objective circulation type classifications, which have been optimized with respect to their synoptic skill for the target variable PM10. All downscaling approaches have been evaluated via cross validation using varying subintervals of the 1980-2011 period as calibration and validation periods respectively. The most suitable - in terms of model skill determined from cross

  12. Prediction of SOC content at European scale by coupling Vis-NIR spectroscopy and a modified local PLSR algorithm

    NASA Astrophysics Data System (ADS)

    Nocita, M.; Stevens, A.; De Brogniez, D.; Bampa, F.; Toth, G.; Panagos, P.; van Wesemael, B.; Montanarella, L.

    2012-04-01

    The spatial variability of soils still represents an important challenge to accurately report the soil status. Visible near infrared soil spectroscopy (VNIRS) has been shown to be an efficient tool for the prediction of soil organic carbon (SOC) at fine scales. However, when applied to regional or country scales, VNIRS did not provide sufficient accuracy as an alternative to standard laboratory soil analysis for SOC monitoring. Under the framework of LUCAS project of the Joint Research Centre (JRC), about 20,000 samples were collected all over European Union. Soil samples were analyzed for several physical and chemical parameters, and scanned with a Vis-NIR spectrometer in the same laboratory. The scope of our research was to predict SOC content at European scale using LUCAS spectral library. We implemented a modified local partial least square regression (l-PLSR) including, in addition to spectral distance, other potentially useful covariates (geography, texture, etc.) to select for each unknown sample a group of k predicting neighbors. The dataset was divided into tuning (15%), training (60%), and validation (25%) subsets. The tuning subset was used to find the most performing combination of model parameters. The best model was then calibrated and validated on training and validation subsets. Although the high variability of land-use systems covered by LUCAS sampling campaign, the chosen methodology resulted in a fair prediction ability (RMSE: 5-6 g C kg-1) at continental scale, but not precise enough to be used for SOC monitoring on a point by point basis. The results indicated that a local approach might improve the ability of VNIRS in predicting SOC trends, with the increasing variability of land managements at larger scales.

  13. Size effects and strain localization in atomic-scale cleavage modeling.

    PubMed

    Elsner, B A M; Müller, S

    2015-09-01

    In this work, we study the adhesion and decohesion of Cu(1 0 0) surfaces using density functional theory (DFT) calculations. An upper stress to surface decohesion is obtained via the universal binding energy relation (UBER), but the model is limited to rigid separation of bulk-terminated surfaces. When structural relaxations are included, an unphysical size effect arises if decohesion is considered to occur as soon as the strain energy equals the energy of the newly formed surfaces. We employ the nudged elastic band (NEB) method to show that this size effect is opposed by a size-dependency of the energy barriers involved in the transition. Further, we find that the transition occurs via a localization of bond strain in the vicinity of the cleavage plane, which resembles the strain localization at the tip of a sharp crack that is predicted by linear elastic fracture mechanics. PMID:26219654

  14. Nonlinear nano-scale localized breather modes in a discrete weak ferromagnetic spin lattice

    NASA Astrophysics Data System (ADS)

    Kavitha, L.; Parasuraman, E.; Gopi, D.; Prabhu, A.; Vicencio, Rodrigo A.

    2016-03-01

    We investigate the propagation dynamics of highly localized discrete breather modes in a weak ferromagnetic spin lattice with on-site easy axis anisotropy due to crystal field effect. We derive the discrete nonlinear equation of motion by employing boson mappings and p-representation. We explore the onset of modulational instability both analytically in the framework of linear stability analysis and numerically by means of molecular dynamics (MD) simulations, and a perfect agreement was demonstrated. It is also explored that how the antisymmetric nature of the canted ferromagnetic lattice supports highly localized discrete breather (DBs) modes as shown in the stability/instability windows. The energy exchange between low amplitude discrete breathers favours the growth of higher amplitude DBs, resulting eventually in the formation of few long-lived high amplitude DBs.

  15. Combining local- and large-scale models to predict the distributions of invasive plant species.

    PubMed

    Jones, Chad C; Acker, Steven A; Halpern, Charles B

    2010-03-01

    Habitat distribution models are increasingly used to predict the potential distributions of invasive species and to inform monitoring. However, these models assume that species are in equilibrium with the environment, which is clearly not true for most invasive species. Although this assumption is frequently acknowledged, solutions have not been adequately addressed. There are several potential methods for improving habitat distribution models. Models that require only presence data may be more effective for invasive species, but this assumption has rarely been tested. In addition, combining modeling types to form "ensemble" models may improve the accuracy of predictions. However, even with these improvements, models developed for recently invaded areas are greatly influenced by the current distributions of species and thus reflect near- rather than long-term potential for invasion. Larger scale models from species' native and invaded ranges may better reflect long-term invasion potential, but they lack finer scale resolution. We compared logistic regression (which uses presence/absence data) and two presence-only methods for modeling the potential distributions of three invasive plant species on the Olympic Peninsula in Washington, USA. We then combined the three methods to create ensemble models. We also developed climate envelope models for the same species based on larger scale distributions and combined models from multiple scales to create an index of near- and long-term invasion risk to inform monitoring in Olympic National Park (ONP). Neither presence-only nor ensemble models were more accurate than logistic regression for any of the species. Larger scale models predicted much greater areas at risk of invasion. Our index of near- and long-term invasion risk indicates that < 4% of ONP is at high near-term risk of invasion while 67-99% of the Park is at moderate or high long-term risk of invasion. We demonstrate how modeling results can be used to guide the

  16. Linear-scaling explicitly correlated treatment of solids: Periodic local MP2-F12 method

    SciTech Connect

    Usvyat, Denis

    2013-11-21

    Theory and implementation of the periodic local MP2-F12 method in the 3*A fixed-amplitude ansatz is presented. The method is formulated in the direct space, employing local representation for the occupied, virtual, and auxiliary orbitals in the form of Wannier functions (WFs), projected atomic orbitals (PAOs), and atom-centered Gaussian-type orbitals, respectively. Local approximations are introduced, restricting the list of the explicitly correlated pairs, as well as occupied, virtual, and auxiliary spaces in the strong orthogonality projector to the pair-specific domains on the basis of spatial proximity of respective orbitals. The 4-index two-electron integrals appearing in the formalism are approximated via the direct-space density fitting technique. In this procedure, the fitting orbital spaces are also restricted to local fit-domains surrounding the fitted densities. The formulation of the method and its implementation exploits the translational symmetry and the site-group symmetries of the WFs. Test calculations are performed on LiH crystal. The results show that the periodic LMP2-F12 method substantially accelerates basis set convergence of the total correlation energy, and even more so the correlation energy differences. The resulting energies are quite insensitive to the resolution-of-the-identity domain sizes and the quality of the auxiliary basis sets. The convergence with the orbital domain size is somewhat slower, but still acceptable. Moreover, inclusion of slightly more diffuse functions, than those usually used in the periodic calculations, improves the convergence of the LMP2-F12 correlation energy with respect to both the size of the PAO-domains and the quality of the orbital basis set. At the same time, the essentially diffuse atomic orbitals from standard molecular basis sets, commonly utilized in molecular MP2-F12 calculations, but problematic in the periodic context, are not necessary for LMP2-F12 treatment of crystals.

  17. Scales

    MedlinePlus

    Scales are a visible peeling or flaking of outer skin layers. These layers are called the stratum ... Scales may be caused by dry skin, certain inflammatory skin conditions, or infections. Eczema , ringworm , and psoriasis ...

  18. Surging Seas Risk Finder: A Tool for Local-Scale Flood Risk Assessments in Coastal Cities

    NASA Astrophysics Data System (ADS)

    Kulp, S. A.; Strauss, B.

    2015-12-01

    Local decision makers in coastal cities require accurate, accessible, and thorough assessments of flood exposure risk within their individual municipality, in their efforts to mitigate against damage due to future sea level rise. To fill this need, we have developed Climate Central's Surging Seas Risk Finder, an interactive data toolkit which presents our sea level rise and storm surge analysis for every coastal town, city, county, and state within the USA. Using this tool, policy makers can easily zoom in on their local place of interest to receive a detailed flood risk assessment, which synthesizes a wide range of features including total population, socially vulnerable population, housing, property value, road miles, power plants, schools, hospitals, and many other critical facilities. Risk Finder can also be used to identify specific points of interest in danger of exposure at different flood levels. Additionally, this tool provides localized storm surge probabilities and sea level rise projections at tidal gauges along the coast, so that users can quickly understand the risk of flooding in their area over the coming decades.

  19. Estimating the Cumulative Ecological Effect of Local Scale Landscape Changes in South Florida

    USGS Publications Warehouse

    Hogan, Dianna M.; Labiosa, William; Pearlstine, Leonard; Hallac, David; Strong, David; Hearn, Paul; Bernknopf, Richard

    2012-01-01

    Ecosystem restoration in south Florida is a state and national priority centered on the Everglades wetlands. However, urban development pressures affect the restoration potential and remaining habitat functions of the natural undeveloped areas. Land use (LU) planning often focuses at the local level, but a better understanding of the cumulative effects of small projects at the landscape level is needed to support ecosystem restoration and preservation. The South Florida Ecosystem Portfolio Model (SFL EPM) is a regional LU planning tool developed to help stakeholders visualize LU scenario evaluation and improve communication about regional effects of LU decisions. One component of the SFL EPM is ecological value (EV), which is evaluated through modeled ecological criteria related to ecosystem services using metrics for (1) biodiversity potential, (2) threatened and endangered species, (3) rare and unique habitats, (4) landscape pattern and fragmentation, (5) water quality buffer potential, and (6) ecological restoration potential. In this article, we demonstrate the calculation of EV using two case studies: (1) assessing altered EV in the Biscayne Gateway area by comparing 2004 LU to potential LU in 2025 and 2050, and (2) the cumulative impact of adding limestone mines south of Miami. Our analyses spatially convey changing regional EV resulting from conversion of local natural and agricultural areas to urban, industrial, or extractive use. Different simulated local LU scenarios may result in different alterations in calculated regional EV. These case studies demonstrate methods that may facilitate evaluation of potential future LU patterns and incorporate EV into decision making.

  20. Acoustic Source Localization via Distributed Sensor Networks using Tera-scale Optical-Core Devices

    SciTech Connect

    Imam, Neena; Barhen, Jacob; Wardlaw, Michael

    2008-01-01

    For real-time acoustic source localization applications, one of the primary challenges is the considerable growth in computational complexity associated with the emergence of ever larger, active or passive, distributed sensor networks. The complexity of the calculations needed to achieve accurate source localization increases dramatically with the size of sensor arrays, resulting in substantial growth of computational requirements that cannot be met with standard hardware. One option to meet this challenge builds upon the emergence of digital optical-core devices. The objective of this work was to explore the implementation of key building block algorithms used in underwater source localization on an optical-core digital processing platform recently introduced by Lenslet Inc. They investigate key concepts of threat-detection algorithms such as Time Difference Of Arrival (TDOA) estimation via sensor data correlation in the time domain with the purpose of implementation on the optical-core processor. they illustrate their results with the aid of numerical simulation and actual optical hardware runs. The major accomplishments of this research, in terms of computational speedup and numerical accurcy achieved via the deployment of optical processing technology, should be of substantial interest to the acoustic signal processing community.

  1. Estimating the Cumulative Ecological Effect of Local Scale Landscape Changes in South Florida

    NASA Astrophysics Data System (ADS)

    Hogan, Dianna M.; Labiosa, William; Pearlstine, Leonard; Hallac, David; Strong, David; Hearn, Paul; Bernknopf, Richard

    2012-02-01

    Ecosystem restoration in south Florida is a state and national priority centered on the Everglades wetlands. However, urban development pressures affect the restoration potential and remaining habitat functions of the natural undeveloped areas. Land use (LU) planning often focuses at the local level, but a better understanding of the cumulative effects of small projects at the landscape level is needed to support ecosystem restoration and preservation. The South Florida Ecosystem Portfolio Model (SFL EPM) is a regional LU planning tool developed to help stakeholders visualize LU scenario evaluation and improve communication about regional effects of LU decisions. One component of the SFL EPM is ecological value (EV), which is evaluated through modeled ecological criteria related to ecosystem services using metrics for (1) biodiversity potential, (2) threatened and endangered species, (3) rare and unique habitats, (4) landscape pattern and fragmentation, (5) water quality buffer potential, and (6) ecological restoration potential. In this article, we demonstrate the calculation of EV using two case studies: (1) assessing altered EV in the Biscayne Gateway area by comparing 2004 LU to potential LU in 2025 and 2050, and (2) the cumulative impact of adding limestone mines south of Miami. Our analyses spatially convey changing regional EV resulting from conversion of local natural and agricultural areas to urban, industrial, or extractive use. Different simulated local LU scenarios may result in different alterations in calculated regional EV. These case studies demonstrate methods that may facilitate evaluation of potential future LU patterns and incorporate EV into decision making.

  2. A two-scale model for sheared fault gouge: Competition between macroscopic disorder and local viscoplasticity

    NASA Astrophysics Data System (ADS)

    Elbanna, A. E.; Carlson, J. M.

    2014-06-01

    We develop a model for sheared gouge layers that accounts for the local increase in temperature at the grain contacts during sliding. We use the shear transformation zone theory, a statistical thermodynamic theory, to describe irreversible macroscopic plastic deformations due to local rearrangements of the gouge particles. We track the temperature evolution at the grain contacts using a one-dimensional heat diffusion equation. At low temperatures, the strength of the asperities is limited by the flow strength, as predicted by dislocation creep models. At high temperatures, some of the constituents of the grains may melt leading to the degradation of the asperity strength. Our model predicts a logarithmic rate dependence of the steady state shear stress in the quasistatic regime. In the dense flow regime the frictional strength decreases rapidly with increasing slip rate due to thermal softening at the granular interfaces. The transient response following a step in strain rate includes a direct effect and a following evolution effect, both of which depend on the magnitude and direction of the velocity step. In addition to frictional heat, the energy budget includes an additional energy sink representing the fraction of external work consumed in increasing local disorder. The model links low-speed and high-speed frictional response of gouge layers and provides an essential ingredient for multiscale modeling of earthquake ruptures with enhanced coseismic weakening.

  3. Oceanic primary production: estimation by remote sensing at local and regional scales.

    PubMed

    Platt, T; Sathyendranath, S

    1988-09-23

    Satellites provide the only avenue by which marine primary production can be studied at ocean-basin scales. With maps of chlorophyll distribution derived from remotely sensed data on ocean color as input, deduction of a suitable algorithm for primary production is a problem in applied plant physiology. An algorithm is proposed that combines a spectral and angular model of submarine light with a model of the spectral response of algal photosynthesis. To apply the algorithm at large horizontal scale, a dynamic biogeography is needed for the physiological rate parameters and the biological structure of the water column. Fieldwork to obtain this type of data should be undertaken so that the use of satellite data in modern biological oceanography may be optimized. PMID:17820892

  4. Large-Scale, Complex Shaped Coastline Responses to Different Forms of Local Shoreline Stabilization and Climate Change

    NASA Astrophysics Data System (ADS)

    Ells, K.; Murray, A. B.; Slott, J. M.

    2010-12-01

    Nowhere is the importance of research addressing the dynamics of coupled human-landscape processes more pronounced than on the world’s coasts, where human shoreline stabilization alters the natural evolution of the coastline on large spatial and temporal scales. Slott et al. (2010) extended a recently developed large-scale coastline evolution model to include the effects of beach ‘nourishment’ (importing sand into the nearshore system at a long term rate sufficient to counteract shoreline erosion) on a complex-shaped coastline, finding a surprising human signal over large (100s km) distances (Figure 1); even localized shoreline stabilization efforts, when maintained over decadal time scales, can significantly affect the regional pattern of coastline morphological adjustment in response to changing storm behaviors (Slott, et al., 2010). In this work, we examine the effects of shoreline-stabilization method that involve hard structures, such as sea walls and groyne fields. These methods differ significantly from beach nourishment in terms of large-scale impacts; they hold the shoreline location fixed without adding a flux of sediment into the system. Like beach nourishment, these human manipulations have widespread, significant effects on shoreline change rates, even when the manipulations only occur locally. However, the effects on large-scale coastline morphodynamics also exhibit interesting differences when compared to the beach nourishment case. References Slott, Jordan, A. B. Murray, Andrew Ashton, 2010. Large-Scale Responses of Complex-Shaped Coastlines to Local Shoreline Stabilization and Climate Change, Journal of Geophysical Research—Earth Surface. Figure 1. Evolution of a cuspate-cape shoreline in response to ongoing beach nourishment over 200 years, for six different site selections. a. Initial model shoreline, developed in response to a wave climate approximating recent conditions off of the Carolina coast, USA. b. The influence that beach

  5. Grassland/atmosphere response to changing climate: Coupling regional and local scales. Final report

    SciTech Connect

    Coughenour, M.B.; Kittel, T.G.F.; Pielke, R.A.; Eastman, J.

    1993-10-01

    The objectives of the study were: to evaluate the response of grassland ecosystems to atmospheric change at regional and site scales, and to develop multiscaled modeling systems to relate ecological and atmospheric models with different spatial and temporal resolutions. A menu-driven shell was developed to facilitate use of models at different temporal scales and to facilitate exchange information between models at different temporal scales. A detailed ecosystem model predicted that C{sub 3} temperate grasslands wig respond more strongly to elevated CO{sub 2} than temperate C{sub 4} grasslands in the short-term while a large positive N-PP response was predicted for a C{sub 4} Kenyan grassland. Long-term climate change scenarios produced either decreases or increases in Colorado plant productivity (NPP) depending on rainfall, but uniform increases in N-PP were predicted in Kenya. Elevated CO{sub 2} is likely to have little effect on ecosystem carbon storage in Colorado while it will increase carbon storage in Kenya. A synoptic climate classification processor (SCP) was developed to evaluate results of GCM climate sensitivity experiments. Roughly 80% agreement was achieved with manual classifications. Comparison of lx and 2xCO{sub 2} GCM Simulations revealed relatively small differences.

  6. High Temperature Mechanical Behavior of Polycrystalline Alumina from Mixed Nanometer and Micrometer Powders

    NASA Technical Reports Server (NTRS)

    Goldsby, Jon C.

    2001-01-01

    Sintered aluminum oxide materials were formed using commercial methods from mechanically mixed powders of nano-and micrometer alumina. The powders were consolidated at 1500 and 1600 C with 3.2 and 7.2 ksi applied stress in argon. The conventional micrometer sized powders failed to consolidate. While 100 percent nanometer-sized alumina and its mixture with the micrometer powders achieved less than 99 percent density. Preliminary high temperature creep behavior indicates no super-plastic strains. However high strains (less than 0.65 percent) were generated in the nanometer powder, due to cracks and linked voids initiated by cavitation.

  7. On the Nature of the First Galaxies Selected at 350 Micrometers

    NASA Technical Reports Server (NTRS)

    Khan, Sophia A.; Chanial, Pierre F.; Willner, S. P.; Pearson, Chris P.; Ashby, M. L. N.; Benford, Dominic J.; Clements, David L.; Dye, Simon; Farrah, Duncan; Fazio, G. G.; Huang, J. S.; Lebouteiller, V.; Le Floc'H, Emeric; Mainetti, Gabriele; Harvey Moseley, S.; Negrello, Mattia; Serjeant, Stephen; Shafer, Richard A.; Staguhn, Johannes; Sumner, Timothy J.; Vaccari, Mattia

    2009-01-01

    We present constraints on the nature of the first galaxies selected at 350 micrometers. The sample includes galaxies discovered in the deepest blank-field survey at 350 micrometers (in the Bo6tes Deep Field) and also later serendipitous detections in the Lockman Hole. In determining multiwavelength identifications, the 350 lam position and map resolution of the second generation Submillimeter High Angular Resolution Camera are critical, especially in the cases where multiple radio sources exist and the 24 micrometer counterparts are unresolved. Spectral energy distribution templates are fitted to identified counterparts, and the sample is found to comprise IR-luminous galaxies at 1 < z < 3 predominantly powered by star formation. The first spectrum of a 350 micrometer selected galaxy provides an additional confirmation, showing prominent dust grain features typically associated with star-forming galaxies. Compared to submillimeter galaxies selected at 850 and 1100 micrometers, galaxies selected at 350 micrometers have a similar range of far-infrared color temperatures. However, no 350 micrometer selected sources are reliably detected at 850 or 1100 micrometers. Galaxies in our sample with redshifts 1 < z < 2 show a tight correlation between the far- and mid-infrared flux densities, but galaxies at higher redshifts show a large dispersion in their mid- to far-infrared colors. This implies a limit to which the mid-IR emission traces the far-IR emission in star-forming galaxies. The 350 micrometer flux densities (15 < S(sub 350) < 40 mJy) place these objects near the Herschel/SPIRE 350 micrometer confusion threshold, with the lower limit on the star formation rate density suggesting the bulk of the 350 micrometers contribution will come from less luminous infrared sources and normal galaxies. Therefore, the nature of the dominant source of the 350 micrometers background-star-forming galaxies in the epoch of peak star formation in the universe-could be more effectively

  8. Full-Scale Dynamic Analysis of an Innovative Rockfall Fence Under Impact Using the Discrete Element Method: from the Local Scale to the Structure Scale

    NASA Astrophysics Data System (ADS)

    Bertrand, D.; Trad, A.; Limam, A.; Silvani, C.

    2012-09-01

    In order to protect infrastructures against rockfalls, civil-engineered mitigation measures are widely used. Flexible metallic fences are particularly well suited to stop the propagation of blocks of rock whose kinetic energy can reach 5000 kJ before impact. This paper focuses on the design of highly flexible rockfall fences under the new European guideline ETAG027. The experimental testing and the numerical modeling using the discrete element method (DEM) of a new metallic rockfall fence are presented. Several scales of study were considered; the mesh, the net and the entire structure. The calibration of the DEM models is described and a parametrical study is proposed. The latter aims to underline the type of information that can be obtained from numerical simulations of such a system to enhance its design.

  9. Assessment of Local Biodiversity Loss in Uranium Mining-Tales And Its Projections On Global Scale

    NASA Astrophysics Data System (ADS)

    Sharshenova, D.; Zhamangulova, N.

    2015-12-01

    In Min-Kush, northern Kyrgyzstan there are 8 mining tales with an estimate of 1 961 000 tones of industrial Uranium. Local ecosystem services have declined rapidly. We analyzed a terrestrial assemblage database of Uranium mine-tale to quantify local biodiversity responses to land use and environmental changes. In the worst-affected habitats species richness reduced by 95.7%, total abundance by 60.9% and rarefaction-based richness by 72.5%. We estimate that, regional mountain ecosystem affected by this pressure reduced average within-sample richness (by 17.01%), total abundance (16.5%) and rarefaction-based richness (14.5%). Business-as-usual scenarios are the widely practiced in the region and moreover, due to economic constraints country can not afford any mitigation scenarios. We project that biodiversity loss and ecosystem service impairment will spread in the region through ground water, soil, plants, animals and microorganisms at the rate of 1km/year. Entire Tian-Shan mountain chain will be in danger within next 5-10 years. Our preliminary data shows that local people live in this area developed various forms of cancer, and the rate of premature death is as high as 40%. Strong international scientific and socio-economic partnership is needed to develop models and predictions.

  10. Comparisons of AM fungal spore communities with the same hosts but different soil chemistries over local and geographic scales.

    PubMed

    Ji, Baoming; Bentivenga, Stephen P; Casper, Brenda B

    2012-01-01

    Arbuscular mycorrhizal (AM) fungi are ubiquitous and ecologically important microbes in grasslands. Both the host plant species and soil properties have been suggested as potentially important factors structuring AM fungal communities based on studies within local field sites. However, characterizations of the communities in relation to both host plant identity and soil properties in natural plant communities across both local and broader geographic scales are rare. We examined the AM fungal spore communities associated with the same C(4) grasses in two Eastern serpentine grasslands, where soils have elevated heavy metals, and two Iowa tallgrass prairie sites. We compared AM fungal spore communities among host plants within each site, looked for correlations between fungal communities and local soil properties, and then compared communities among sites. Spore communities did not vary with host plant species or correlate with local soil chemical properties at any site. They did not differ between the two serpentine sites or between the two prairie sites, despite geographic separation, but they did differ between serpentine and prairie. Soil characteristics are suggested as a driving force because spore communities were strongly correlated with soil properties when data from all four sites are considered, but climatic differences might also play a role. PMID:21769630

  11. A new methodology for deterministic landslide risk assessment at the local scale

    NASA Astrophysics Data System (ADS)

    Cotecchia, F.; Santaloia, F.; Lollino, P.; Vitone, C.; Mitaritonna, G.; Parise, M.

    2009-04-01

    The present paper discusses the formulation of a methodology that is being developed for regional landslide risk assessment within geologically complex areas and some preliminary results of its application at the intermediate scale (i.e. between the regional and the slope scale). In particular, the methodology is the subject of an on-going multidisciplinary research project, which aims at the assessment of the landslide hazard, of the corresponding vulnerability of structures and of their exposition, involving different expertises. As such, both the landslide hazard and the structure vulnerability assessments are meant to be based upon the knowledge of the failure mechanisms and to benefit from scientific knowledge in the fields of both geotechnical engineering and structural mechanics. At the same time, the exposure of the elements at risk is to be investigated according to analyses of the socio-economical context where the risk is being evaluated. In the present paper only the work relating to landslide hazard is presented. This work aims at the further development of Quantitative Landslide Hazard Assessment, QHA, following a deterministic approach. As such, it is aimed at exporting the geo-mechanical interpretation of slope stability and landslide mechanisms from the slope scale (site-specific) to the regional scale. The results of such a methodology will be implemented in a GIS system and reported in guidelines. As concerns the landslide hazard assessment, the proposed methodology involves two interconnected working phases, the first one at regional scale and the second one at town scale. During the first phase, an analytical database of all the factors affecting the slope equilibrium is created and a geo-hydro-mechanical classification of the soil masses is defined together with the definition of the main landslide typologies present in the region. Thereafter, the connections existing among the sets of internal factors of landslides, which characterise the geo

  12. Differential plague-transmission dynamics determine Yersinia pestis population genetic structure on local, regional, and global scales

    PubMed Central

    Girard, Jessica M.; Wagner, David M.; Vogler, Amy J.; Keys, Christine; Allender, Christopher J.; Drickamer, Lee C.; Keim, Paul

    2004-01-01

    Plague, the disease caused by the bacterium Yersinia pestis, has greatly impacted human civilization. Y. pestis is a successful global pathogen, with active foci on all continents except Australia and Antarctica. Because the Y. pestis genome is highly monomorphic, previous attempts to characterize the population genetic structure within a single focus have been largely unsuccessful. Here we report that highly mutable marker loci allow determination of Y. pestis population genetic structure and tracking of transmission patterns at two spatial scales within a single focus. In addition, we found that in vitro mutation rates for these loci are similar to those observed in vivo, which allowed us to develop a mutation-rate-based model to examine transmission mechanisms. Our model suggests there are two primary components of plague ecology: a rapid expansion phase for population growth and dispersal followed by a slower persistence phase. This pattern seems consistent across local, regional, and even global scales. PMID:15173603

  13. The GEO Water Strategy: Advances in Monitoring, Modeling, and Predicting Groundwater Variations at Regional to Local Scales

    NASA Astrophysics Data System (ADS)

    Miller, N. L.; Heinrich, L.; Kukuri, N.; Plag, H.; Famiglietti, J. S.; Rodell, M.

    2012-12-01

    Groundwater remains one of the most important freshwater resources, especially during droughts and as global warming increases. For informed decisions on managing these resources sustainably, it is important to have sound assessments of the current state of groundwater resources as well as future predictions. This requires reliable groundwater quantity and quality data. However global access to this data is limited. As part of the GEOSS Water Strategy, the International Groundwater Assessment Centre (IGRAC) is therefore implementing the Global Groundwater Monitoring Network (GGMN). The GGMN facilitates periodic assessments of changes in groundwater quantity and quality by aggregating data and information from existing groundwater monitoring networks and regional hydrogeological knowledge (Fig. 1). The GGMN is a participatory process that relies upon contributions from regional and national networks of groundwater experts. Such observation data, along with local well data, surface displacements observed by and GPS data and InSAR, and local in situ gravity data, are necessary for evaluation and simulation of groundwater, leading to improved understanding and prediction of groundwater variations. In conjunction with these observations, regional scale groundwater variations are derived as a residual from land surface-groundwater models through extraction of the total mass of water using geo-rectified Gravity Recovery and Climate Experiment (GRACE) data. Such model-based studies have quantified overdraft and regions at risk of groundwater depletion in parts of Asia, US, and Africa (Fig. 2).We provide an overview of these systems, planned missions, and new model-based approaches toward local-scale methods for assimilation of well data for several regions.igure 1. Example of GGMN (Example of Botswana with fictitious data, with local precipitation map) igure 2. GRACE-derived groundwater storage in northwestern India for 2002 - 2008, relative to the mean. Deviations from

  14. Investigation of Greenhouse Gas Emissions by Surface, Airborne, and Satellite on Local to Continental-Scale

    NASA Astrophysics Data System (ADS)

    Leifer, I.; Tratt, D. M.; Egland, E. T.; Gerilowski, K.; Vigil, S. A.; Buchwitz, M.; Krings, T.; Bovensmann, H.; Krautwurst, S.; Burrows, J. P.

    2013-12-01

    In situ meteorological observations, including 10-m winds (U), in conjunction with greenhouse gas (GHG - methane, carbon dioxide, water vapor) measurements by continuous wave Cavity Enhanced Absorption Spectroscopy (CEAS) were conducted onboard two specialized platforms: MACLab (Mobile Atmospheric Composition Laboratory in a RV) and AMOG Surveyor (AutoMObile Greenhouse gas) - a converted commuter automobile. AMOG Surveyor data were collected for numerous southern California sources including megacity, geology, fossil fuel industrial, animal husbandry, and landfill operations. MACLab investigated similar sources along with wetlands on a transcontinental scale from California to Florida to Nebraska covering more than 15,000 km. Custom software allowing real-time, multi-parameter data visualization (GHGs, water vapor, temperature, U, etc.) improved plume characterization and was applied to large urban area and regional-scale sources. The capabilities demonstrated permit calculation of source emission strength, as well as enable documenting microclimate variability. GHG transect data were compared with airborne HyperSpectral Imaging data to understand temporal and spatial variability and to ground-truth emission strength derived from airborne imagery. These data also were used to validate satellite GHG products from SCIAMACHY (2003-2005) and GOSAT (2009-2013) that are currently being analyzed to identify significant decadal-scale changes in North American GHG emission patterns resulting from changes in anthropogenic and natural sources. These studies lay the foundation for the joint ESA/NASA COMEX campaign that will map GHG plumes by remote sensing and in situ measurements for a range of strong sources to derive emission strength through inverse plume modeling. COMEX is in support of the future GHG monitoring satellites, such as CarbonSat and HyspIRI. GHG transect data were compared with airborne HyperSpectral Imaging data to understand temporal and spatial variability

  15. Image retargeting using non-uniform scaling with adaptive local search window

    NASA Astrophysics Data System (ADS)

    Wang, Shanshan; Abdel-Dayem, Amr

    2011-10-01

    This paper presents a new content-aware image-retargeting scheme, based on non-uniform scaling, to adaptively adjust the image's dimensions for various screen sizes. Based on an importance map, the energy contribution for each line in the reduced dimension to the overall energy within the image is computed. Then, the image is adaptively mapped and resampled based on the energy contribution function. Experimental results showed that the performance of the proposed scheme is comparable to seam carving in visual quality. However, it is computationally less expensive.

  16. Local Scale Radiobrightness Modeling During the 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, Hao-Yu; Pham, Hanh; Boprie, David; Graf, Tobias; Koike, Toshio; Armstrong, Richard

    2005-01-01

    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 2002 and 2003 in Colorado, USA. One of the goals of the experiment was to test the capabilities of microwave emission models at different scales. Initial forward model validation work has concentrated 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. Results obtained in the case of the 3& Intensive Observing Period (IOP3) period (Feb., 2003, dry snow) suggest that a model based on Dense Medium Radiative Transfer (DMRT) theory is able to model the recorded brightness temperatures using snow parameters derived from field measurements. This paper focuses on the ability of forward DMRT modelling, combined with snowpack measurements, to reproduce the radiobrightness signatures observed by the University of Michigan s Truck-Mounted Radiometer System (TMRS) at 19 and 37 GHz during the 4th IOP (IOP4) in March, 2003. Unlike IOP3, conditions during IOP4 include both wet and dry periods, providing a valuable test of DMRT model performance. 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) and the TMRS. The plot-scale study in this paper establishes a baseline of DMRT performance for later studies at successively larger scales. And these scaling studies will help guide the choice of future snow retrieval algorithms and the design of future Cold Lands observing systems.

  17. Local coupling (LoCo) vs. large-scale coupled (LsCo) land-atmosphere interactions in idealized experiments

    NASA Astrophysics Data System (ADS)

    Gentine, P.; Lintner, B. R.; Findell, K. L.; Rochetin, N.; Sobel, A. H.; Anber, U. M.

    2014-12-01

    We will present two idealized epxeriments/methodologies to investigate local (LoCo) and large-scale (LsCo) coupling between the surface and the atmsophere: the contiental Radiative-Convective Equilibrium (RCE) and the continental Weak Temperature Gradient (WTG). The RCE defines an equilibrium state of coupling between the surafce and the atmosphere isolated from any large-scale dependence, which were investigated within the single column model of the Laboratoire de Meteorologie Dynamique (LMD) coupled to a simple bucket land model. This studies emphasizes the role of low-level cloud and the diurnal cylce of the boundary layer on the final state of the system. In the WTG we investigate the coupling between the surface and the atmosphere during the dry and wet season of the Amazon with the WRF model coupled to the NOAH land-surface model. Large-scale coupling is obtained with the WTG. The dry and wet season demonstrate very fundamental behavior: in the dry season deep convection is generated by radiative cooling in the higher troposhere and is disconnected from the surface. In the wet season the coupling between the surface and the atmosphere is much tighter. We suggest that the WTG is a powerful tool to investigate the coupling between the surface and the atmosphere, which solves two major issues: the limited resolution of convection in GCMs and the lack of large-scale coupling in CRM. Later investigation will look at the effect of deforestation, water table and distance from the ocean.

  18. Radial localization of inositol 1,4,5-trisphosphate-sensitive Ca2+ release sites in Xenopus oocytes resolved by axial confocal linescan imaging.

    PubMed

    Callamaras, N; Parker, I

    1999-02-01

    The radial localization and properties of elementary calcium release events ("puffs") were studied in Xenopus oocytes using a confocal microscope equipped with a piezoelectric focussing unit to allow rapid (>100 Hz) imaging of calcium signals along a radial line into the cell with a spatial resolution of <0.7 micrometer. Weak photorelease of caged inositol 1,4,5-trisphosphate (InsP3) evoked puffs arising predominantly within a 6-micrometer thick band located within a few micrometers of the cell surface. Approximately 25% of puffs had a restricted radial spread, consistent with calcium release from a single site. Most puffs, however, exhibited a greater radial spread (3.25 micrometer), likely involving recruitment of radially neighboring release sites. Calcium waves evoked by just suprathreshold stimuli exhibited radial calcium distributions consistent with inward diffusion of calcium liberated at puff sites, whereas stronger flashes evoked strong, short-latency signals at depths inward from puff sites, indicating deep InsP3-sensitive stores activated at higher concentrations of InsP3. Immunolocalization of InsP3 receptors showed punctate staining throughout a region corresponding to the localization of puffs and subplasmalemmal endoplasmic reticulum. The radial organization of puff sites a few micrometers inward from the plasma membrane may have important consequences for activation of calcium-dependent ion channels and "capacitative" calcium influx. However, on the macroscopic (hundreds of micrometers) scale of global calcium waves, release can be considered to occur primarily within a thin, essentially two-dimensional subplasmalemmal shell. PMID:9925819

  19. Local versus field scale soil heterogeneity characterization - a challenge for representative sampling in pollution studies

    NASA Astrophysics Data System (ADS)

    Kardanpour, Z.; Jacobsen, O. S.; Esbensen, K. H.

    2015-12-01

    This study is a contribution to development of a heterogeneity characterization facility for "next-generation" soil sampling aimed, for example, at more realistic and controllable pesticide variability in laboratory pots in experimental environmental contaminant assessment. The role of soil heterogeneity in quantification of a set of exemplar parameters is described, including a brief background on how heterogeneity affects sampling/monitoring procedures in environmental pollutant studies. The theory of sampling (TOS) and variographic analysis has been applied to develop a more general fit-for-purpose soil heterogeneity characterization approach. All parameters were assessed in large-scale transect (1-100 m) vs. small-scale (0.1-0.5 m) replication sampling point variability. Variographic profiles of experimental analytical results from a specific well-mixed soil type show that it is essential to sample at locations with less than a 2.5 m distance interval to benefit from spatial auto-correlation and thereby avoid unnecessary, inflated compositional variation in experimental pots; this range is an inherent characteristic of the soil heterogeneity and will differ among other soils types. This study has a significant carrying-over potential for related research areas, e.g. soil science, contamination studies, and environmental monitoring and environmental chemistry.

  20. Local versus field scale soil heterogeneity characterization - a challenge for representative sampling in pollution studies

    NASA Astrophysics Data System (ADS)

    Kardanpour, Z.; Jacobsen, O. S.; Esbensen, K. H.

    2015-06-01

    This study is a contribution to development of a heterogeneity characterisation facility for "next generation" sampling aimed at more realistic and controllable pesticide variability in laboratory pots in experimental environmental contaminant assessment. The role of soil heterogeneity on quantification of a set of exemplar parameters, organic matter, loss on ignition (LOI), biomass, soil microbiology, MCPA sorption and mineralization is described, including a brief background on how heterogeneity affects sampling/monitoring procedures in environmental pollutant studies. The Theory of Sampling (TOS) and variographic analysis has been applied to develop a fit-for-purpose heterogeneity characterization approach. All parameters were assessed in large-scale profile (1-100 m) vs. small-scale (0.1-1 m) replication sampling pattern. Variographic profiles of experimental analytical results concludes that it is essential to sample at locations with less than a 2.5 m distance interval to benefit from spatial auto-correlation and thereby avoid unnecessary, inflated compositional variation in experimental pots; this range is an inherent characteristic of the soil heterogeneity and will differ among soils types. This study has a significant carrying-over potential for related research areas e.g. soil science, contamination studies, and environmental monitoring and environmental chemistry.

  1. Local-scale biogeography and spatiotemporal variability in communities of mycorrhizal fungi.

    PubMed

    Bahram, Mohammad; Peay, Kabir G; Tedersoo, Leho

    2015-03-01

    Knowledge of spatiotemporal patterns in species distribution is fundamental to understanding the ecological and evolutionary processes shaping communities. The emergence of DNA-based tools has expanded the geographic and taxonomic scope of studies examining spatial and temporal distribution of mycorrhizal fungi. However, the nature of spatiotemporal patterns documented and subsequent interpretation of ecological processes can vary significantly from study to study. In order to look for general patterns we synthesize the available data across different sampling scales and mycorrhizal types. The results of this analysis shed light on the relative importance of space, time and vertical soil structure on community variability across different mycorrhizal types. Although we found no significant trend in spatiotemporal variation amongmycorrhizal types, the vertical community variation was distinctly greater than the spatial and temporal variability in mycorrhizal fungal communities. Both spatial and temporal variability of communities was greater in topsoil compared with lower horizons, suggesting that greater environmental heterogeneity drives community variation on a fine scale. This further emphasizes the importance of both niche differentiation and environmental filtering in maintaining diverse fungal communities. PMID:25767850

  2. Optimized circulation and weather type classifications relating large-scale atmospheric conditions to local PM10 concentrations in Bavaria

    NASA Astrophysics Data System (ADS)

    Weitnauer, C.; Beck, C.; Jacobeit, J.

    2013-12-01

    In the last decades the critical increase of the emission of air pollutants like nitrogen dioxide, sulfur oxides and particulate matter especially in urban areas has become a problem for the environment as well as human health. Several studies confirm a risk of high concentration episodes of particulate matter with an aerodynamic diameter < 10 μm (PM10) for the respiratory tract or cardiovascular diseases. Furthermore it is known that local meteorological and large scale atmospheric conditions are important influencing factors on local PM10 concentrations. With climate changing rapidly, these connections need to be better understood in order to provide estimates of climate change related consequences for air quality management purposes. For quantifying the link between large-scale atmospheric conditions and local PM10 concentrations circulation- and weather type classifications are used in a number of studies by using different statistical approaches. Thus far only few systematic attempts have been made to modify consisting or to develop new weather- and circulation type classifications in order to improve their ability to resolve local PM10 concentrations. In this contribution existing weather- and circulation type classifications, performed on daily 2.5 x 2.5 gridded parameters of the NCEP/NCAR reanalysis data set, are optimized with regard to their discriminative power for local PM10 concentrations at 49 Bavarian measurement sites for the period 1980 to 2011. Most of the PM10 stations are situated in urban areas covering urban background, traffic and industry related pollution regimes. The range of regimes is extended by a few rural background stations. To characterize the correspondence between the PM10 measurements of the different stations by spatial patterns, a regionalization by an s-mode principal component analysis is realized on the high-pass filtered data. The optimization of the circulation- and weather types is implemented using two representative

  3. VizieR Online Data Catalog: Micrometer measurements of double stars (Ling+, 2000)

    NASA Astrophysics Data System (ADS)

    Ling, J. F.; Prieto, C.

    2000-10-01

    We report 312 micrometer measurements of 155 visual double stars made with the 50 cm refractor at the Cote D'Azur observatory (Nice, France) and with the 152 cm telescope at Calar Alto observatory (Almeria, Spain). (2 data files).

  4. Some 5-13 micrometer airborne observations of Comet Wilson 1986l: Preliminary results

    NASA Technical Reports Server (NTRS)

    Lynch, David K.; Russell, Ray W.; Witteborn, F. C.; Bregman, Jesse D.; Rank, D. M.; Cohen, M. C; Campins, Humberto C.

    1988-01-01

    Comet Wilson was observed from the Kuiper Airborne Observatory approximately 23.6 and 25.7 Apr. 1987, UT (approx. 3 to 5 days after perihelion) using the NASA-Ames Faint Object Grating Spectrometer. Spectrophotometric data were observed with a 21 inch aperture between 5 and 13 micrometer and with a spectral resolution of 50 to 100. Spectra of the inner coma and nucleus reveal a fairly smooth continuum with little evidence of silicate emission. The 5 to 8 micrometer color temperature of the comet was 300 + or - 15 K, approx. 15 percent higher than the equilibrium blackbody temperature. All three spectra of the nucleus show a new emission feature at approx. 12.25 micrometer approx. two channels (.22 micrometer) wide. Visual and photographic observations made during the time of these observations showed a broad faint, possible two component tail. No outburst activity was observed.

  5. Local scattering property scales flow speed estimation in laser speckle contrast imaging

    NASA Astrophysics Data System (ADS)

    Miao, Peng; Chao, Zhen; Feng, Shihan; Yu, Hang; Ji, Yuanyuan; Li, Nan; Thakor, Nitish V.

    2015-07-01

    Laser speckle contrast imaging (LSCI) has been widely used in in vivo blood flow imaging. However, the effect of local scattering property (scattering coefficient µ s ) on blood flow speed estimation has not been well investigated. In this study, such an effect was quantified and involved in relation between speckle autocorrelation time τ c and flow speed v based on simulation flow experiments. For in vivo blood flow imaging, an improved estimation strategy was developed to eliminate the estimation bias due to the inhomogeneous distribution of the scattering property. Compared to traditional LSCI, a new estimation method significantly suppressed the imaging noise and improves the imaging contrast of vasculatures. Furthermore, the new method successfully captured the blood flow changes and vascular constriction patterns in rats’ cerebral cortex from normothermia to mild and moderate hypothermia.

  6. Puzzle Imaging: Using Large-Scale Dimensionality Reduction Algorithms for Localization

    PubMed Central

    Glaser, Joshua I.; Zamft, Bradley M.; Church, George M.; Kording, Konrad P.

    2015-01-01

    Current high-resolution imaging techniques require an intact sample that preserves spatial relationships. We here present a novel approach, “puzzle imaging,” that allows imaging a spatially scrambled sample. This technique takes many spatially disordered samples, and then pieces them back together using local properties embedded within the sample. We show that puzzle imaging can efficiently produce high-resolution images using dimensionality reduction algorithms. We demonstrate the theoretical capabilities of puzzle imaging in three biological scenarios, showing that (1) relatively precise 3-dimensional brain imaging is possible; (2) the physical structure of a neural network can often be recovered based only on the neural connectivity matrix; and (3) a chemical map could be reproduced using bacteria with chemosensitive DNA and conjugative transfer. The ability to reconstruct scrambled images promises to enable imaging based on DNA sequencing of homogenized tissue samples. PMID:26192446

  7. Studying wildlife at local and landscape scales: Bachman's Sparrows at the Savannah River Site

    USGS Publications Warehouse

    Dunning, J.B., Jr.; Danielson, B.J.; Watts, B.D.; Liu, L.; Krementz, D.G.

    2000-01-01

    In the late 1980s and early 1990s, mutual research interests between land managers at the Savannah River Site and biologists at the University of Georgia resulted in a landscape-ecology study of the Bachman's Sparrow (Aimophila aestivalis). This species had been declining throughout its range for several decades and was considered a species of management concern by the U.S. Forest Service. The reasons for its decline were obscure, but the distribution of suitable habitat across complex landscapes was a possible factor. Thus the species seemed well suited for a pioneer study on landscape influences on avian population dynamics. A cooperative research program developed from these mutual interests, including quantifying the landscape and local habitat patterns shown by the sparrow, spatially explicit modeling of population response to landscape change, and demographic field studies of reproductive success, survivorship and dispersal. These studies are summarized, and the value of the research to both management and research interests is discussed.

  8. Ratiometric Organic Fibers for Localized and Reversible Ion Sensing with Micrometer‐Scale Spatial Resolution

    PubMed Central

    Moffa, Maria; Rinaldi, Rosaria

    2015-01-01

    A fundamental issue in biomedical and environmental sciences is the development of sensitive and robust sensors able to probe the analyte of interest, under physiological and pathological conditions or in environmental samples, and with very high spatial resolution. In this work, novel hybrid organic fibers that can effectively report the analyte concentration within the local microenvironment are reported. The nanostructured and flexible wires are prepared by embedding fluorescent pH sensors based on seminaphtho‐rhodafluor‐1‐dextran conjugate. By adjusting capsule/polymer ratio and spinning conditions, the diameter of the fibers and the alignment of the reporting capsules are both tuned. The hybrid wires display excellent stability, high sensitivity, as well as reversible response, and their operation relies on effective diffusional kinetic coupling of the sensing regions and the embedding polymer matrix. These devices are believed to be a powerful new sensing platform for clinical diagnostics, bioassays and environmental monitoring. PMID:26539625

  9. Multi-scale multireference configuration interaction calculations for large systems using localized orbitals: partition in zones.

    PubMed

    Chang, Cristian; Calzado, Carmen J; Ben Amor, Nadia; Sanchez Marin, Jose; Maynau, Daniel

    2012-09-14

    A new multireference configuration interaction method using localised orbitals is proposed, in which a molecular system is divided into regions of unequal importance. The advantage of dealing with local orbitals, i.e., the possibility to neglect long range interaction is enhanced. Indeed, while in the zone of the molecule where the important phenomena occur, the interaction cut off may be as small as necessary to get relevant results, in the most part of the system it can be taken rather large, so that results of good quality may be obtained at a lower cost. The method is tested on several systems. In one of them, the definition of the various regions is not based on topological considerations, but on the nature, σ or π, of the localised orbitals, which puts in evidence the generality of the approach. PMID:22979845

  10. Multi-scale multireference configuration interaction calculations for large systems using localized orbitals: Partition in zones

    NASA Astrophysics Data System (ADS)

    Chang, Cristian; Calzado, Carmen J.; Amor, Nadia Ben; Marin, Jose Sanchez; Maynau, Daniel

    2012-09-01

    A new multireference configuration interaction method using localised orbitals is proposed, in which a molecular system is divided into regions of unequal importance. The advantage of dealing with local orbitals, i.e., the possibility to neglect long range interaction is enhanced. Indeed, while in the zone of the molecule where the important phenomena occur, the interaction cut off may be as small as necessary to get relevant results, in the most part of the system it can be taken rather large, so that results of good quality may be obtained at a lower cost. The method is tested on several systems. In one of them, the definition of the various regions is not based on topological considerations, but on the nature, σ or π, of the localised orbitals, which puts in evidence the generality of the approach.

  11. Localized micro- and nano-scale remodelling in the diabetic aorta

    PubMed Central

    Akhtar, R.; Cruickshank, J.K.; Zhao, X.; Walton, L.A.; Gardiner, N.J.; Barrett, S.D.; Graham, H.K.; Derby, B.; Sherratt, M.J.

    2014-01-01

    Diabetes is strongly associated with cardiovascular disease, but the mechanisms, structural and biomechanical consequences of aberrant blood vessel remodelling remain poorly defined. Using an experimental (streptozotocin, STZ) rat model of diabetes, we hypothesized that diabetes enhances extracellular protease activity in the aorta and induces morphological, compositional and localized micromechanical tissue remodelling. We found that the medial aortic layer underwent significant thickening in diabetic animals but without significant changes in collagen or elastin (abundance). Scanning acoustic microscopy demonstrated that such tissue remodelling was associated with a significant decrease in acoustic wave speed (an indicator of reduced material stiffness) in the inter-lamellar spaces of the vessel wall. This index of decreased stiffness was also linked to increased extracellular protease activity (assessed by semi-quantitative in situ gelatin zymography). Such a proteolytically active environment may affect the macromolecular structure of long-lived extracellular matrix molecules. To test this hypothesis, we also characterized the effects of diabetes on the ultrastructure of an important elastic fibre component: the fibrillin microfibril. Using size exclusion chromatography and atomic force microscopy, we isolated and imaged microfibrils from both healthy and diabetic aortas. Microfibrils derived from diabetic tissues were fragmented, morphologically disrupted and weakened (as assessed following molecular combing). These structural and functional abnormalities were not replicated by in vitro glycation. Our data suggest that proteolysis may be a key driver of localized mechanical change in the inter-lamellar space of diabetic rat aortas and that structural proteins (such as fibrillin microfbrils) may be biomarkers of diabetes induced damage. PMID:25014552

  12. The dynamics of plate tectonics and mantle flow: from local to global scales.

    PubMed

    Stadler, Georg; Gurnis, Michael; Burstedde, Carsten; Wilcox, Lucas C; Alisic, Laura; Ghattas, Omar

    2010-08-27

    Plate tectonics is regulated by driving and resisting forces concentrated at plate boundaries, but observationally constrained high-resolution models of global mantle flow remain a computational challenge. We capitalized on advances in adaptive mesh refinement algorithms on parallel computers to simulate global mantle flow by incorporating plate motions, with individual plate margins resolved down to a scale of 1 kilometer. Back-arc extension and slab rollback are emergent consequences of slab descent in the upper mantle. Cold thermal anomalies within the lower mantle couple into oceanic plates through narrow high-viscosity slabs, altering the velocity of oceanic plates. Viscous dissipation within the bending lithosphere at trenches amounts to approximately 5 to 20% of the total dissipation through the entire lithosphere and mantle. PMID:20798311

  13. Methane emissions from wetlands: biogeochemical, microbial, and modeling perspectives from local to global scales.

    PubMed

    Bridgham, Scott D; Cadillo-Quiroz, Hinsby; Keller, Jason K; Zhuang, Qianlai

    2013-05-01

    Understanding the dynamics of methane (CH4 ) emissions is of paramount importance because CH4 has 25 times the global warming potential of carbon dioxide (CO2 ) and is currently the second most important anthropogenic greenhouse gas. Wetlands are the single largest natural CH4 source with median emissions from published studies of 164 Tg yr(-1) , which is about a third of total global emissions. We provide a perspective on important new frontiers in obtaining a better understanding of CH4 dynamics in natural systems, with a focus on wetlands. One of the most exciting recent developments in this field is the attempt to integrate the different methodologies and spatial scales of biogeochemistry, molecular microbiology, and modeling, and thus this is a major focus of this review. Our specific objectives are to provide an up-to-date synthesis of estimates of global CH4 emissions from wetlands and other freshwater aquatic ecosystems, briefly summarize major biogeophysical controls over CH4 emissions from wetlands, suggest new frontiers in CH4 biogeochemistry, examine relationships between methanogen community structure and CH4 dynamics in situ, and to review the current generation of CH4 models. We highlight throughout some of the most pressing issues concerning global change and feedbacks on CH4 emissions from natural ecosystems. Major uncertainties in estimating current and future CH4 emissions from natural ecosystems include the following: (i) A number of important controls over CH4 production, consumption, and transport have not been, or are inadequately, incorporated into existing CH4 biogeochemistry models. (ii) Significant errors in regional and global emission estimates are derived from large spatial-scale extrapolations from highly heterogeneous and often poorly mapped wetland complexes. (iii) The limited number of observations of CH4 fluxes and their associated environmental variables loosely constrains the parameterization of process-based biogeochemistry

  14. Regional and Local Scale Modeling of Stream Temperatures and Spatio-Temporal Variation in Thermal Sensitivities

    NASA Astrophysics Data System (ADS)

    Hilderbrand, Robert H.; Kashiwagi, Michael T.; Prochaska, Anthony P.

    2014-07-01

    Understanding variation in stream thermal regimes becomes increasingly important as the climate changes and aquatic biota approach their thermal limits. We used data from paired air and water temperature loggers to develop region-scale and stream-specific models of average daily water temperature and to explore thermal sensitivities, the slopes of air-water temperature regressions, of mostly forested streams across Maryland, USA. The region-scale stream temperature model explained nearly 90 % of the variation (root mean square error = 0.957 °C), with the mostly flat coastal plain streams having significantly higher thermal sensitivities than the steeper highlands streams with piedmont streams intermediate. Model R 2 for stream-specific models was positively related to a stream's thermal sensitivity. Both the regional and the stream-specific air-water temperature regression models benefited from including mean daily discharge from regional gaging stations, but the degree of improvement declined as a stream's thermal sensitivity increased. Although catchment size had no relationship to thermal sensitivity, steeper streams or those with greater amounts of forest in their upstream watershed were less thermally sensitive. The subset of streams with three or more summers of temperature data exhibited a wide range of annual variation in thermal sensitivity at a site, with the variation not attributable to discharge, precipitation patterns, or physical attributes of streams or their watersheds. Our findings are a useful starting point to better understand patterns in stream thermal regimes. However, a more spatially and temporally comprehensive monitoring network should increase understanding of stream temperature variation and its controls as climatic patterns change.

  15. Spatial and topographic trends in forest expansion and biomass change, from regional to local scales.

    PubMed

    Buma, Brian; Barrett, Tara M

    2015-09-01

    Natural forest growth and expansion are important carbon sequestration processes globally. Climate change is likely to increase forest growth in some regions via CO2 fertilization, increased temperatures, and altered precipitation; however, altered disturbance regimes and climate stress (e.g. drought) will act to reduce carbon stocks in forests as well. Observations of asynchrony in forest change is useful in determining current trends in forest carbon stocks, both in terms of forest density (e.g. Mg ha(-1) ) and spatially (extent and location). Monitoring change in natural (unmanaged) areas is particularly useful, as while afforestation and recovery from historic land use are currently large carbon sinks, the long-term viability of those sinks depends on climate change and disturbance dynamics at their particular location. We utilize a large, unmanaged biome (>135 000 km(2) ) which spans a broad latitudinal gradient to explore how variation in location affects forest density and spatial patterning: the forests of the North American temperate rainforests in Alaska, which store >2.8 Pg C in biomass and soil, equivalent to >8% of the C in contiguous US forests. We demonstrate that the regional biome is shifting; gains exceed losses and are located in different spatio-topographic contexts. Forest gains are concentrated on northerly aspects, lower elevations, and higher latitudes, especially in sheltered areas, whereas loss is skewed toward southerly aspects and lower latitudes. Repeat plot-scale biomass data (n = 759) indicate that within-forest biomass gains outpace losses (live trees >12.7 cm diameter, 986 Gg yr(-1) ) on gentler slopes and in higher latitudes. This work demonstrates that while temperate rainforest dynamics occur at fine spatial scales (<1000 m(2) ), the net result of thousands of individual events is regionally patterned change. Correlations between the disturbance/establishment imbalance and biomass accumulation suggest the potential for relatively

  16. Spatial mapping of greenhouse gases using laser absorption spectrometers at local scales of interest

    NASA Astrophysics Data System (ADS)

    Dobler, Jeremy; Zaccheo, T. S.; Blume, Nathan; Braun, Michael; Botos, Chris; Pernini, Timothy G.

    2015-10-01

    Over the past two years a new system capable of measuring the 2-D spatial distribution of atmospheric CO2 over areas on the order of 1 km2 and time scales of a few minutes, has been developed and demonstrated. The Greenhouse gas Laser Imaging Tomography Experiment (GreenLITE) - developed under a cooperative agreement with the National Energy Technology Laboratory (NETL) of the U.S. Department of Energy (DOE) - attempts to improve monitoring capabilities of Ground Carbon Storage (GCS) sites. GreenLITE sensors are based on an intensity modulated continuous wave (IM-CW) approach developed at ITT (now part of Harris Corp.) in 2004. The GreenLITE system recently completed a remote deployment of nearly 4,000 hours at a GCS site in Illinois. It provided continuous, real-time spatial distribution maps of CO2 via an open web-based interface from February to August 2015. In early 2015 we began work on a new implementation of GreenLITE capable of providing similar measurements over a 25 km2 area and are planning to test the system over a 5 km range late summer 2015. If successful the system will be deployed in an urban environment late 2015, demonstrating the utility of real-time 2-D spatial mapping of CO2 concentrations at this scale. This paper will review the concept for this new measurement capability, including results from the 1 km system. Ultimately, the measurement concept can be adapted to other greenhouse gases such as CH4 and NO2.

  17. Understanding regional and local scale hydraulic processes controlling recharge through drift

    NASA Astrophysics Data System (ADS)

    Cuthbert, M. O.; Mackay, R.; Lawrence, A. R.; Peach, D.

    2003-04-01

    The estimation of groundwater recharge is a fundamental component of any water resources appraisal or aquifer vulnerability study. Although methods for evaluating the distribution of potential recharge leaving the soil zone are relatively well developed, the recharge signal to the underlying aquifer can be significantly modified in the presence of superficial drift deposits. Current mapping of the drift does not often provide representations of drift distribution and structure suitable for understanding the hydraulics of the subsurface flow system. The current research seeks to develop new understanding of the processes contributing to recharge in heterogeneous drift sequences, their characterisation in models and their parameterisation through field experiments. Surface and downhole geophysical sampling through regional to micro scales will be integrated with textural measurements and hydraulic monitoring to characterise drift deposits in parts of the Tern catchment (Shropshire, UK) and gain insight into the relationship between flow behaviour and geological structure. Fieldwork will then culminate in a series of flow and tracer tests at a well characterised site with continuous monitoring including the use of recently developed 4-D resistivity imaging methods to monitor the movement of natural and applied waters through the drift. Conceptual and numerical models will be used throughout the project to test ideas and drive the experimental designs. The study aims to assess the relative importance of hydraulic processes at a range of scales and, by back analysis, the degree of sophistication required in fieldwork to construct a useful model of flow patterns within the drift. The potential usefulness of various surface and downhole geophysical techniques within drift and unsaturated zone studies will be critically assessed.

  18. Infrared images of Jupiter at 5-micrometer wavelength during the Voyager 1 encounter

    NASA Technical Reports Server (NTRS)

    Terrile, R. J.; Capps, R. W.; Backman, D. E.; Becklin, E. E.; Cruikshank, D. P.; Beichman, C. A.; Brown, R. H.; Westphal, J. A.

    1979-01-01

    A coordinated program to observe Jupiter at high spatial resolution in the 5-micrometer wavelength region was undertaken to support Voyager 1 imaging and infrared radiation experiment targeting. Jupiter was observed over a 5-month period from Palomar and Mauna Kea observatories. The frequency of observations allowed the selection of interesting areas for closer Voyager examination and also provided good short-term monitoring of variations in cloud morphology. Significant global changes in the 5-micrometer distribution are seen over this time period.

  19. Acid dissolution experiments - Carbonates and the 6.8-micrometer bands in interplanetary dust particles

    NASA Astrophysics Data System (ADS)

    Sandford, S. A.

    1986-03-01

    A chemical dissolution experiment on an interplanetary dust particle (IDP) showed that carbonates, not acid-insoluble organic compounds, were responsible for virtually all the absorption at 6.8 micrometers seen in the infrared spectra of this particle. The IDP examined had an infrared spectrum characteristic of layer-lattice silicates and belongs to a class of IDP's whose spectra resemble those of protostellar objects like W33 A, which also exhibit a band at 6.8 micrometers.

  20. Modelling Coral Reef Futures to Inform Management: Can Reducing Local-Scale Stressors Conserve Reefs under Climate Change?

    PubMed Central

    Gurney, Georgina G.; Melbourne-Thomas, Jessica; Geronimo, Rollan C.; Aliño, Perry M.; Johnson, Craig R.

    2013-01-01

    Climate change has emerged as a principal threat to coral reefs, and is expected to exacerbate coral reef degradation caused by more localised stressors. Management of local stressors is widely advocated to bolster coral reef resilience, but the extent to which management of local stressors might affect future trajectories of reef state remains unclear. This is in part because of limited understanding of the cumulative impact of multiple stressors. Models are ideal tools to aid understanding of future reef state under alternative management and climatic scenarios, but to date few have been sufficiently developed to be useful as decision support tools for local management of coral reefs subject to multiple stressors. We used a simulation model of coral reefs to investigate the extent to which the management of local stressors (namely poor water quality and fishing) might influence future reef state under varying climatic scenarios relating to coral bleaching. We parameterised the model for Bolinao, the Philippines, and explored how simulation modelling can be used to provide decision support for local management. We found that management of water quality, and to a lesser extent fishing, can have a significant impact on future reef state, including coral recovery following bleaching-induced mortality. The stressors we examined interacted antagonistically to affect reef state, highlighting the importance of considering the combined impact of multiple stressors rather than considering them individually. Further, by providing explicit guidance for management of Bolinao's reef system, such as which course of management action will most likely to be effective over what time scales and at which sites, we demonstrated the utility of simulation models for supporting management. Aside from providing explicit guidance for management of Bolinao's reef system, our study offers insights which could inform reef management more broadly, as well as general understanding of reef

  1. Modelling coral reef futures to inform management: can reducing local-scale stressors conserve reefs under climate change?

    PubMed

    Gurney, Georgina G; Melbourne-Thomas, Jessica; Geronimo, Rollan C; Aliño, Perry M; Johnson, Craig R

    2013-01-01

    Climate change has emerged as a principal threat to coral reefs, and is expected to exacerbate coral reef degradation caused by more localised stressors. Management of local stressors is widely advocated to bolster coral reef resilience, but the extent to which management of local stressors might affect future trajectories of reef state remains unclear. This is in part because of limited understanding of the cumulative impact of multiple stressors. Models are ideal tools to aid understanding of future reef state under alternative management and climatic scenarios, but to date few have been sufficiently developed to be useful as decision support tools for local management of coral reefs subject to multiple stressors. We used a simulation model of coral reefs to investigate the extent to which the management of local stressors (namely poor water quality and fishing) might influence future reef state under varying climatic scenarios relating to coral bleaching. We parameterised the model for Bolinao, the Philippines, and explored how simulation modelling can be used to provide decision support for local management. We found that management of water quality, and to a lesser extent fishing, can have a significant impact on future reef state, including coral recovery following bleaching-induced mortality. The stressors we examined interacted antagonistically to affect reef state, highlighting the importance of considering the combined impact of multiple stressors rather than considering them individually. Further, by providing explicit guidance for management of Bolinao's reef system, such as which course of management action will most likely to be effective over what time scales and at which sites, we demonstrated the utility of simulation models for supporting management. Aside from providing explicit guidance for management of Bolinao's reef system, our study offers insights which could inform reef management more broadly, as well as general understanding of reef

  2. Prediction of protein subcellular localization by support vector machines using multi-scale energy and pseudo amino acid composition.

    PubMed

    Shi, J-Y; Zhang, S-W; Pan, Q; Cheng, Y-M; Xie, J

    2007-07-01

    As more and more genomes have been discovered in recent years, there is an urgent need to develop a reliable method to predict the subcellular localization for the explosion of newly found proteins. However, many well-known prediction methods based on amino acid composition have problems utilizing the sequence-order information. Here, based on the concept of Chou's pseudo amino acid composition (PseAA), a new feature extraction method, the multi-scale energy (MSE) approach, is introduced to incorporate the sequence-order information. First, a protein sequence was mapped to a digital signal using the amino acid index. Then, by wavelet transform, the mapped signal was broken down into several scales in which the energy factors were calculated and further formed into an MSE feature vector. Following this, combining this MSE feature vector with amino acid composition (AA), we constructed a series of MSEPseAA feature vectors to represent the protein subcellular localization sequences. Finally, according to a new kind of normalization approach, the MSEPseAA feature vectors were normalized to form the improved MSEPseAA vectors, named as IEPseAA. Using the technique of IEPseAA, C-support vector machine (C-SVM) and three multi-class SVMs strategies, quite promising results were obtained, indicating that MSE is quite effective in reflecting the sequence-order effects and might become a useful tool for predicting the other attributes of proteins as well. PMID:17235454

  3. Automated macular pathology diagnosis in retinal OCT images using multi-scale spatial pyramid with local binary patterns.

    PubMed

    Liu, Yu-Ying; Chen, Mei; Ishikawa, Hiroshi; Wollstein, Gadi; Schuman, Joel S; Rehg, James M

    2010-01-01

    We address a novel problem domain in the analysis of optical coherence tomography (OCT) images: the diagnosis of multiple macular pathologies in retinal OCT images. The goal is to identify the presence of normal macula and each of three types of macular pathologies, namely, macular hole, macular edema, and age-related macular degeneration, in the OCT slice centered at the fovea. We use a machine learning approach based on global image descriptors formed from a multi-scale spatial pyramid. Our local descriptors are dimension-reduced Local Binary Pattern histograms, which are capable of encoding texture information from OCT images of the retina. Our representation operates at multiple spatial scales and granularities, leading to robust performance. We use 2-class Support Vector Machine classifiers to identify the presence of normal macula and each of the three pathologies. We conducted extensive experiments on a large dataset consisting of 326 OCT scans from 136 patients. The results show that the proposed method is very effective. PMID:20879208

  4. Local-scale systems input-output analysis of embodied water for the Beijing economy in 2007

    NASA Astrophysics Data System (ADS)

    Han, Mengyao; Guo, Shan; Chen, Hui; Ji, Xi; Li, Jiashuo

    2014-09-01

    Using the most detailed and recent statistics available for Beijing, a local-scale embodiment analysis on water use was conducted, employing a systems input-output analysis that integrates economic systems with natural resources data. Systems analysis for water research at the local scale is a crucial part of a systems oriented water accounting framework. To our knowledge, however, related works have not been thoroughly conducted. In this paper, a set of embodied water intensity inventory data is presented, which is applicable to both intermediate input and final demand. Also, detailed analyses of Beijing's embodied water use accounting are presented. The embodied water intensity of the Water Production and Supply Industry Sector turns out to be the highest among the 42 sectors. For water embodied in final demand, the total amount is 3.48 km3, of which the water embodied in urban household consumption makes up nearly a half proportion. As a net virtual water importer, Beijing's water embodied in commodity trade totals 5.84×108 m3. As a result, in addition to improvements in technology and water use efficiency, adjustments in industrial structure and trade policies are also of significant importance to water conservation efforts.

  5. Sanitary landfill local-scale flow and transport modeling in support of alternative concentrations limit demonstrations, Savannah River Site

    SciTech Connect

    Kelly, V.A.; Beach, J.A.; Statham, W.H.; Pickens, J.F.

    1993-02-19

    The Savannah River Site (SRS) is a Department of Energy (DOE) facility located near Aiken, South Carolina which is currently operated and managed by Westinghouse Savannah River Company (WSRC). The Sanitary Landfill (Sanitary Landfill) at the SRS is located approximately 2,000 feet Northwest of Upper Three Runs Creek (UTRC) on an approximately 70 acre site located south of Road C between the SRS B-Area and UTRC. The Sanitary Landfill has been receiving wastes since 1974 and operates as an unlined trench and fill operation. The original landfill site was 32 acres. This area reached its capacity around 1987 and a Northern Expansion of 16 acres and a Southern Expansion of 22 acres were added in 1987. The Northern Expansion has not been used for waste disposal to date and the Southern Expansion is expected to reach capacity in 1992 or 1993. The waste received at the Sanitary Landfill is predominantly paper, plastics, rubber, wood, metal, cardboard, rags saturated with degreasing solvents, pesticide bags, empty cans, and asbestos in bags. The landfill is not supposed to receive any radioactive wastes. However, tritium has been detected in the groundwater at the site. Gross alpha and gross beta are also evaluated at the landfill. The objectives of this modeling study are twofold: (1) to create a local scale Sanitary Landfill flow model to study hydraulic effects resulting from capping the Sanitary Landfill; and (2) to create a Sanitary Landfill local scale transport model to support ACL Demonstrations for a RCRA Part B Permit Renewal.

  6. Calibrating the cosmic distance scale ladder: the role of the sound-horizon scale and the local expansion rate as distance anchors

    NASA Astrophysics Data System (ADS)

    Cuesta, Antonio J.; Verde, Licia; Riess, Adam; Jimenez, Raul

    2015-04-01

    We exploit cosmological model-independent measurements of the expansion history of the Universe to provide a cosmic distance ladder. These are supernovae Type Ia used as standard candles (at redshift between 0.01 and 1.3) and baryon acoustic oscillations (at redshifts between 0.1 and 0.8) as standard rulers. We calibrate (anchor) the ladder in two ways: first using the local H0 value as an anchor at z = 0 (effectively calibrating the standard candles) and secondly using the cosmic microwave background-inferred sound-horizon scale as an anchor (giving the standard ruler length) as an inverse distance ladder. Both methods are consistent, but the uncertainty in the expansion history H(z) is smaller if the sound-horizon scale is used. We present inferred values for the sound horizon at radiation drag rd which do not rely on assumptions about the early expansion history nor on cosmic microwave background measurements but on the cosmic distance ladder and baryon acoustic oscillations measurements. We also present derived values of H0 from the inverse distance ladder and we show that they are in very good agreement with the extrapolated value in a Λ cold dark matter model from Planck cosmic microwave background data.

  7. Focusing of sub-micrometer particles and bacteria enabled by two-dimensional acoustophoresis.

    PubMed

    Antfolk, M; Muller, P B; Augustsson, P; Bruus, H; Laurell, T

    2014-08-01

    Handling of sub-micrometer bioparticles such as bacteria are becoming increasingly important in the biomedical field and in environmental and food analysis. As a result, there is an increased need for less labor-intensive and time-consuming handling methods. Here, an acoustophoresis-based microfluidic chip that uses ultrasound to focus sub-micrometer particles and bacteria, is presented. The ability to focus sub-micrometer bioparticles in a standing one-dimensional acoustic wave is generally limited by the acoustic-streaming-induced drag force, which becomes increasingly significant the smaller the particles are. By using two-dimensional acoustic focusing, i.e. focusing of the sub-micrometer particles both horizontally and vertically in the cross section of a microchannel, the acoustic streaming velocity field can be altered to allow focusing. Here, the focusability of E. coli and polystyrene particles as small as 0.5 μm in diameter in microchannels of square or rectangular cross sections, is demonstrated. Numerical analysis was used to determine generic transverse particle trajectories in the channels, which revealed spiral-shaped trajectories of the sub-micrometer particles towards the center of the microchannel; this was also confirmed by experimental observations. The ability to focus and enrich bacteria and other sub-micrometer bioparticles using acoustophoresis opens the research field to new microbiological applications. PMID:24895052

  8. Use of a Local-Scale Numerical Model to Resolve Conceptual Model Issues at Lawrence Livermore National Laboratory's Site 300.

    NASA Astrophysics Data System (ADS)

    Ritcey, A. C.; Maley, M. P.; Mansoor, K.; Blake, R. G.

    2001-12-01

    A finite-element model was developed to simulate saturated-zone groundwater flow and contaminant transport within the Building 832 Canyon Operating Unit (B832) located at Lawrence Livermore National Laboratory's Site 300. Site 300 is an experimental testing facility located in the Altamont Hills near Tracy, California. The Altamont Hills are located along the easternmost flank of the California Coast Range, and are characterized by steep topography, faulting and folding. Beginning in the 1950s, experimental activities were conducted at B832 that resulted in the release of high concentrations of trichloroethene (TCE) to the subsurface. The primary objective of the numerical model was to investigate the influence of local geologic features on groundwater flow and contaminant transport. The model was designed to easily allow modifications to the conceptual model, and was limited to a single hydrostratigraphic unit (HSU) composed of a thin, (10m thick) sandstone layer within the Neroly Formation that is defined as the primary contaminant pathway. The finite-element code FEFLOW was used for the simulations. Two local-scale features, a fault and a small discharge area, were incorporated into the model, and their effects on flow and transport evaluated by comparison with observed data. The model was also used to evaluate the effects of local-boundary treatments on model results. In particular, the sensitivity of the model to boundary conditions along the western portion of the model domain was evaluated, instigating a re-evaluation of ground-water elevation data in this area. Overall, the local-scale model provided an excellent tool for understanding and refining the conceptual model. The model will also provide boundary conditions (e.g. ground water and TCE fluxes) for a larger-scale model of Site 300's regional aquifer. In addition, the single HSU model allows debugging of boundary conditions in a simpler, more computationally-efficient environment prior to development

  9. Benthic processes and coastal aquaculture: merging models and field data at a local scale

    NASA Astrophysics Data System (ADS)

    Brigolin, Daniele; Rabouille, Christophe; Bombled, Bruno; Colla, Silvia; Pastres, Roberto; Pranovi, Fabio

    2016-04-01

    Shellfish farming is regarded as an organic extractive aquaculture activity. However, the production of faeces and pseudofaeces, in fact, leads to a net transfer of organic matter from the water column to the surface sediment. This process, which is expected to locally affect the sediment biogeochemistry, may also cause relevant changes in coastal areas characterized by a high density of farms. In this paper, we present the result of a study recently carried out in the Gulf of Venice (northern Adriatic sea), combining mathematical modelling and field sampling efforts. The work aimed at using a longline mussel farm as an in-situ test-case for modelling the differences in soft sediments biogeochemical processes along a gradient of organic deposition. We used an existing integrated model, allowing to describe biogeochemical fluxes towards the mussel farm and to predict the extent of the deposition area underneath it. The model framework includes an individual-based population dynamic model of the Mediterranean mussel coupled with a Lagrangian deposition model and a 1D benthic model of early diagenesis. The work was articulated in 3 steps: 1) the integrated model allowed to simulate the downward fluxes of organic matter originated by the farm, and the extent of its deposition area; 2) based on the first model application, two stations were localized, at which sediment cores were collected during a field campaign, carried out in June 2015. Measurements included O2 and pH microprofiling, porosity and micro-porosity, Total Organic Carbon, and pore waters NH4, PO4, SO4, Alkalinity, and Dissolved Inorganic Carbon; 3) two distinct early diagenesis models were set-up, reproducing observed field data in the sampled cores. Observed oxygen microprofiles showed a different behavior underneath the farm with respect to the outside reference station. In particular, a remarkable decrease in the oxygen penetration depth, and an increase in the O2 influx calculated from the

  10. Toward integrated multi-scale pedestal simulations including edge-localized-mode dynamics, evolution of edge-localized-mode cycles, and continuous fluctuations

    NASA Astrophysics Data System (ADS)

    Xu, X. Q.; Xia, T. Y.; Yan, N.; Liu, Z. X.; Kong, D. F.; Diallo, A.; Groebner, R. J.; Hubbard, A. E.; Hughes, J. W.

    2016-05-01

    The high-fidelity BOUT++ two-fluid code suite has demonstrated significant recent progress toward integrated multi-scale simulations of tokamak pedestal, including Edge-Localized-Mode (ELM) dynamics, evolution of ELM cycles, and continuous fluctuations, as observed in experiments. Nonlinear ELM simulations show three stages of an ELM event: (1) a linear growing phase; (2) a fast crash phase; and (3) a slow inward turbulence spreading phase lasting until the core heating flux balances the ELM energy loss and the ELM is terminated. A new coupling/splitting model has been developed to perform simulations of multi-scale ELM dynamics. Simulation tracks five ELM cycles for 10 000 Alfvén times for small ELMs. The temporal evolution of the pedestal pressure is similar to that of experimental measurements for the pedestal pressure profile collapses and recovers to a steep gradient during ELM cycles. To validate BOUT++ simulations against experimental data and develop physics understanding of the fluctuation characteristics for different tokamak operation regimes, both quasi-coherent fluctuations (QCFs) in ELMy H-modes and Weakly Coherent Modes in I-modes have been simulated using three dimensional 6-field 2-fluid electromagnetic model. The H-mode simulation results show that (1) QCFs are localized in the pedestal region having a predominant frequency at f ≃300 -400 kHz and poloidal wavenumber at kθ≃0.7 cm-1 , and propagate in the electron diamagnetic direction in the laboratory frame. The overall signatures of simulation results for QCFs show good agreement with C-Mod and DIII-D measurements. (2) The pedestal profiles giving rise to QCFs are near the marginal instability threshold for ideal peeling-ballooning modes for both C-Mod and DIII-D, while the collisional electromagnetic drift-Alfvén wave appears to be dominant for DIII-D. (3) Particle diffusivity is either smaller than the heat diffusivity for DIII-D or similar to the heat diffusivity for C-Mod. Key I

  11. Local stochastic subgrid-scale modeling for a one dimensional shallow water model using stochastic mode reduction

    NASA Astrophysics Data System (ADS)

    Zacharuk, Matthias; Stamen, Dolaptchiev; Ulrich, Achatz; Ilya, Timofeyev

    2016-04-01

    Due to the finite spatial resolution in numerical atmospheric models subgrid-scale (SGS) processes are excluded. A SGS parameterization of these excluded processes might improve the model on all scales. To parameterize the SGS processes we choose the MTV stochastic mode reduction (Majda, Timofeyev, Vanden-Eijnden 2001, A mathematical framework for stochastic climate models. Commun. Pure Appl. Math., 54:891-974). For this the model is separated into fast and slow processes. Using the statistics of the fast processes, a SGS parameterization is found. To identify fast processes the state vector of the model is separated into two state vectors. One vector is the average of the full model state vector in a coarse grid cell. The other describes SGS processes which are defined as the deviation of the full state vector from the coarse cell average. If the SGS vector decorrelates faster in time than the coarse grid vector, the interactions of SGS processes in the equation of the SGS processes are replaced by a local Ornstein-Uhlenbeck process. Afterwards the MTV SGS parameterization can be derived. This method was successfully applied on the Burgers-equation (Dolaptchiev et al. 2013, Stochastic closure for local averages in the finite-difference discretization of the forced Burgers equation. Theor. Comp. Fluid Dyn., 27:297-317). In this study we consider a more atmosphere like model and choose a model of the one dimensional shallow water equations (SWe). It will be shown, that the fine state vector decorrelates faster than the coarse state vector. Due to the non-polynomial form of the SWe in flux formulation an approximation of all 1/h (h = fluid depth) terms needs to be done, except of the interactions between coarse state vector to coarse state vector. It will be shown, that this approximation has only minor impact on the model results. In the following the model with the local Ornstein-Uhlenbeck process approximation of SGS interactions is analyzed and compared to the

  12. COS-GTO: QSO Absorbers, Galaxies and Large-scale Structures in the Local Universe.

    NASA Astrophysics Data System (ADS)

    Green, James

    2009-07-01

    This is a program to probe the large scale structure of baryons in the universe, including addressing questions of baryon fraction, physical conditions and relationships between absorbers and large-scale structures of galaxies. Besides these specific goals, this proposed GTO program also probes a large enough total path length in Ly alpha and OVI to add significantly to what STIS/FUSE has already observed. Several Galactic High Velocity Cloud Complexes also are probed by these sightlines, particularly the M Complex. The total path length of this proposed program for Ly alpha large-scale structure surveys is delta_z 5.5. We have selected a variety of targets to address these questions, under the following subcategories:1. Target 8 bright BL Lac objects