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Sample records for subseafloor volume heterogeneity

  1. Subseafloor Biosphere Linked to Hydrothermal Systems: TAIGA Concept

    National Research Council Canada - National Science Library

    Ishibashi, Jun-ichiro; Okino, Kyoko; Sunamura, Michinari

    2015-01-01

    This book is the comprehensive volume of the TAIGA (“a great river ” in Japanese) project. Supported by the Japanese government, the project examined the hypothesis that the subseafloor fluid advection system...

  2. Radiolytic hydrogen production in the subseafloor basaltic aquifer

    Directory of Open Access Journals (Sweden)

    Mary E Dzaugis

    2016-02-01

    Full Text Available Hydrogen (H2 is produced in geological settings by dissociation of water due to radiation from radioactive decay of naturally occurring uranium (238U, 235U, thorium (232Th and potassium (40K. To quantify the potential significance of radiolytic H2 as an electron donor for microbes within the South Pacific subseafloor basaltic aquifer, we use radionuclide concentrations of 43 basalt samples from IODP Expedition 329 to calculate radiolytic H2 production rates in basement fractures. The samples are from three sites with very different basement ages and a wide range of alteration types. U, Th and K concentrations vary by up to an order of magnitude from sample to sample at each site. Comparison of our samples to each other and to the results of previous studies of unaltered East Pacific Rise basalt suggests that significant variations in radionuclide concentrations are due to differences in initial (unaltered basalt concentrations (which can vary between eruptive events and post-emplacement alteration. In our samples, there is no clear relationship between alteration type and calculated radiolytic yields. Local maxima in U, Th, and K produce hotspots of H2 production, causing calculated radiolytic rates to differ by up to a factor of 80 from sample to sample. Fracture width also greatly influences H2 production, where microfractures are hotspots for radiolytic H2 production. For example, H2 production rates normalized to water volume are 190 times higher in 1 μm wide fractures than in fractures that are 10 cm wide. To assess the importance of water radiolysis for microbial communities in subseafloor basaltic aquifers, we compare electron transfer rates from radiolysis to rates from iron oxidation in subseafloor basalt. Radiolysis appears likely to be a more important electron donor source than iron oxidation in old (>10 Ma basement basalt. Radiolytic H2 production in the volume of water adjacent to a square cm of the most radioactive SPG basalt may

  3. Biogenic Mn-Oxides in Subseafloor Basalts.

    Science.gov (United States)

    Ivarsson, Magnus; Broman, Curt; Gustafsson, Håkan; Holm, Nils G

    2015-01-01

    The deep biosphere of the subseafloor basalts is recognized as a major scientific frontier in disciplines like biology, geology, and oceanography. Recently, the presence of fungi in these environments has involved a change of view regarding diversity and ecology. Here, we describe fossilized fungal communities in vugs in subseafloor basalts from a depth of 936.65 metres below seafloor at the Detroit Seamount, Pacific Ocean. These fungal communities are closely associated with botryoidal Mn oxides composed of todorokite. Analyses of the Mn oxides by Electron Paramagnetic Resonance spectroscopy (EPR) indicate a biogenic signature. We suggest, based on mineralogical, morphological and EPR data, a biological origin of the botryoidal Mn oxides. Our results show that fungi are involved in Mn cycling at great depths in the seafloor and we introduce EPR as a means to easily identify biogenic Mn oxides in these environments.

  4. Intralesional and metastatic heterogeneity in malignant melanomas demonstrated by stereologic estimates of nuclear volume

    DEFF Research Database (Denmark)

    Sørensen, Flemming Brandt; Erlandsen, M

    1990-01-01

    Regional variability of nuclear 3-dimensional size can be estimated objectively using point-sampled intercepts obtained from different, defined zones within individual neoplasms. In the present study, stereologic estimates of the volume-weighted mean nuclear volume, nuclear vv, within peripheral...... melanomas showed large interindividual variation. This finding emphasizes that unbiased estimates of nuclear vv are robust to regional heterogeneity of nuclear volume and thus suitable for purposes of objective, quantitative malignancy grading of melanomas....

  5. Nitrogen isotopes in bulk marine sediment: linking seafloor observations with subseafloor records

    Directory of Open Access Journals (Sweden)

    J.-E. Tesdal

    2013-01-01

    Full Text Available The stable isotopes of nitrogen offer a unique perspective on changes in the nitrogen cycle, past and present. However, the presence of multiple forms of nitrogen in marine sediments can complicate the interpretation of bulk nitrogen isotope measurements. Although the large-scale global patterns of seafloor δ15N have been shown to match process-based expectations, small-scale heterogeneity on the seafloor, or alterations of isotopic signals during translation into the subseafloor record, could obscure the primary signals. Here, a public database of nitrogen isotope measurements is described, including both seafloor and subseafloor sediment samples ranging in age from modern to the Pliocene, and used to assess these uncertainties. In general, good agreement is observed between neighbouring seafloor sites within a 100 km radius, with 85% showing differences of < 1‰. There is also a good correlation between the δ15N of the shallowest (< 5 ka subseafloor sediments and neighbouring seafloor sites within a 100 km radius (R2 = 0.83, which suggests a reliable translation of sediments into the buried sediment record. Meanwhile, gradual δ15N decreases over multiple glacial–interglacial cycles appear to reflect post-depositional alteration in records from the deep sea (below 2000 m. We suggest a simple conceptual model to explain these 100-kyr-timescale changes in well-oxygenated, slowly accumulating sediments, which calls on differential loss rates for pools of organic N with different δ15N. We conclude that bulk sedimentary nitrogen isotope records are reliable monitors of past changes in the marine nitrogen cycle at most locations, and could be further improved with a better understanding of systematic post-depositional alteration. Furthermore, geochemical or environmental criteria should be developed in order to effectively identify problematic locations and to account for

  6. Effects of pore-scale dispersion, degree of heterogeneity, sampling size, and source volume on the concentration moments of conservative solutes in heterogeneous formations

    Science.gov (United States)

    Daniele Tonina; Alberto Bellin

    2008-01-01

    Pore-scale dispersion (PSD), aquifer heterogeneity, sampling volume, and source size influence solute concentrations of conservative tracers transported in heterogeneous porous formations. In this work, we developed a new set of analytical solutions for the concentration ensemble mean, variance, and coefficient of variation (CV), which consider the effects of all these...

  7. IODP: Facilitating Multidisciplinary Collaboration in Subseafloor Investigations

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    Meth, C. E.; Koppers, A. A.; Screaton, E.

    2012-12-01

    The Integrated Ocean Drilling Program (IODP) is an international marine research program that brings to the surface new insights into climate and environmental change, tectonics and earthquake genesis, and the nature of life in extreme environments. The program crosses disciplines, international boundaries, and generations in a collaborative effort to collect subseafloor cores and data for studying the planet. A recent survey of the U.S. scientific ocean drilling community defines the breadth and research diversity of the scientists involved in this innovative program. In total, 433 scientists responded, representing 117 universities, institutions, businesses, and government agencies located in 39 states and Washington, DC. A particularly striking statistic is that 44% of the respondents are students or early career researchers who finished their Ph.D. within the past 10 years. Respondents were asked to identify with which of the main IODP research themes they most closely identified. With 31% selecting more than one theme, it is clear that many are taking a truly interdisciplinary approach to their research. More than half (51%) of the respondents have never sailed on an expedition, showing that the use and impact of scientific ocean drilling data reaches far beyond the confines of one expedition and the scientists directly involved therein. These data paint a picture of a broad community that is engaged and ready to embrace future research challenges. By understanding the demographics and interests of a research community - especially diverse communities focused on large research programs - program managers can better develop mechanisms to facilitate collaborations and use resources efficiently.

  8. Information and Heterogeneous Beliefs: Cost of Capital, Trading Volume, and Investor Welfare

    DEFF Research Database (Denmark)

    Christensen, Peter Ove; Qin, Zhenjiang

    In an incomplete market setting with heterogeneous prior beliefs, we show that public information can have a substantial impact on the ex ante cost of capital, trading volume, and investor welfare. In a model with exponential utility investors and an asset with a normally distributed dividend......, the Pareto efficient public information system is the system which enjoys the maximum ex ante cost of capital, and the maximum expected abnormal trading volume. The public information system facilitates improved dynamic trading opportunities based on heterogeneously updated posterior beliefs in order to take...... information system. In an effectively complete market setting, in which investors do not need to trade dynamically in order to take full advantage of their differences in beliefs, the ex ante cost of capital and the investor welfare are both higher than in the incomplete market setting...

  9. A discontinuous control volume finite element method for multi-phase flow in heterogeneous porous media

    Science.gov (United States)

    Salinas, P.; Pavlidis, D.; Xie, Z.; Osman, H.; Pain, C. C.; Jackson, M. D.

    2018-01-01

    We present a new, high-order, control-volume-finite-element (CVFE) method for multiphase porous media flow with discontinuous 1st-order representation for pressure and discontinuous 2nd-order representation for velocity. The method has been implemented using unstructured tetrahedral meshes to discretize space. The method locally and globally conserves mass. However, unlike conventional CVFE formulations, the method presented here does not require the use of control volumes (CVs) that span the boundaries between domains with differing material properties. We demonstrate that the approach accurately preserves discontinuous saturation changes caused by permeability variations across such boundaries, allowing efficient simulation of flow in highly heterogeneous models. Moreover, accurate solutions are obtained at significantly lower computational cost than using conventional CVFE methods. We resolve a long-standing problem associated with the use of classical CVFE methods to model flow in highly heterogeneous porous media.

  10. Using Crustal Fluids to Peer Into the Subseafloor Microbial Habitat

    Science.gov (United States)

    Huber, J. A.

    2008-12-01

    In hard rock seafloor environments, fluids emanating from the basement are one of the best windows into the subseafloor and its resident microbial community. These low-temperature crustal fluids are ubiquitous at both active hydrothermal systems and ridge flank environments. Over the last 15 years, studies of the microbial communities in crustal fluids from eruptive events, drill holes, ridge flanks, and hydrothermal seamounts have revealed a phylogenetically and physiologically diverse microbial community, representing a wide spectrum of thermal tolerances and metabolic strategies from both the subseafloor and the deep sea. In addition, emerging technologies in seafloor sampling capacity and microbial ecology are rapidly increasing our ability to study this difficult habitat. This presentation will provide an overview of what we have learned about the population structure, genomic repertoire, and physiological function of microbes in crustal fluids and what the future holds for subseafloor biosphere research. Data will be integrated with geochemical measurements in crustal environments to better define the subseafloor habitat and its resident microbial community.

  11. Potential implications of the bystander effect on TCP and EUD when considering target volume dose heterogeneity.

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    Balderson, Michael J; Kirkby, Charles

    2015-01-01

    In light of in vitro evidence suggesting that radiation-induced bystander effects may enhance non-local cell killing, there is potential for impact on radiotherapy treatment planning paradigms such as the goal of delivering a uniform dose throughout the clinical target volume (CTV). This work applies a bystander effect model to calculate equivalent uniform dose (EUD) and tumor control probability (TCP) for external beam prostate treatment and compares the results with a more common model where local response is dictated exclusively by local absorbed dose. The broad assumptions applied in the bystander effect model are intended to place an upper limit on the extent of the results in a clinical context. EUD and TCP of a prostate cancer target volume under conditions of increasing dose heterogeneity were calculated using two models: One incorporating bystander effects derived from previously published in vitro bystander data ( McMahon et al. 2012 , 2013a); and one using a common linear-quadratic (LQ) response that relies exclusively on local absorbed dose. Dose through the CTV was modelled as a normal distribution, where the degree of heterogeneity was then dictated by changing the standard deviation (SD). Also, a representative clinical dose distribution was examined as cold (low dose) sub-volumes were systematically introduced. The bystander model suggests a moderate degree of dose heterogeneity throughout a target volume will yield as good or better outcome compared to a uniform dose in terms of EUD and TCP. For a typical intermediate risk prostate prescription of 78 Gy over 39 fractions maxima in EUD and TCP as a function of increasing SD occurred at SD ∼ 5 Gy. The plots only dropped below the uniform dose values for SD ∼ 10 Gy, almost 13% of the prescribed dose. Small, but potentially significant differences in the outcome metrics between the models were identified in the clinically-derived dose distribution as cold sub-volumes were introduced. In terms of

  12. Size and Carbon Content of Sub-seafloor Microbial Cells at Landsort Deep, Baltic Sea

    DEFF Research Database (Denmark)

    Braun, Stefan; Morono, Yuki; Littmann, Sten

    2016-01-01

    The discovery of a microbial ecosystem in ocean sediments has evoked interest in life under extreme energy limitation and its role in global element cycling. However, fundamental parameters such as the size and the amount of biomass of sub-seafloor microbial cells are poorly constrained. Here we...... determined the volume and the carbon content of microbial cells from a marine sediment drill core retrieved by the Integrated Ocean Drilling Program (IODP), Expedition 347, at Landsort Deep, Baltic Sea. To determine their shape and volume, cells were separated from the sediment matrix by multi-layer density...... centrifugation and visualized via epifluorescence microscopy (FM) and scanning electron microscopy (SEM). Total cell-carbon was calculated from amino acid-carbon, which was analyzed by high-performance liquid chromatography (HPLC) after cells had been purified by fluorescence-activated cell sorting (FACS...

  13. Lateral heterogeneity of lunar volcanic activity according to volumes of mare basalts in the farside basins

    Science.gov (United States)

    Taguchi, Masako; Morota, Tomokatsu; Kato, Shinsuke

    2017-07-01

    Estimates for volumes of mare basalts are essential to understand the thermal conditions of the lunar mantle and its lateral heterogeneity. In this study, we estimated the thicknesses and volumes of mare basalts within five farside basins, Apollo, Ingenii, Poincare, Freundlich-Sharonov, and Mendel-Rydberg, using premare craters buried by mare basalts and postmare craters that penetrated/nonpenetrated mare basalts employing topographic and multiband image data obtained by SELENE (Kaguya). Furthermore, using the Gravity Recovery and Interior Laboratory crustal thickness model and the mare volumes estimated by this and previous studies, we investigated the relationship between the volumes of the mare basalts and the crustal thicknesses. The results suggest that the minimum crustal thicknesses within the basins were a dominant factor determining whether magma erupted at the surface and that the critical crustal thicknesses for magma eruption were 10 km on the farside and >20 km on the nearside. The total areas of the regions in which magmas could erupt at the surface are 10 times larger on the nearside than on the farside. A comparison between the mare volumes within the mare basins on the nearside and the farside shows that magma production in the farside mantle might have been 20 times smaller than that in the nearside mantle, implying a stronger dichotomy than previously estimated. These results suggest that the mare hemispherical asymmetry should be attributed to both the difference in the crustal thickness distribution and the difference in the quantity of magma production between the nearside and farside mantles.

  14. Cortical Thickness, Surface Area and Subcortical Volume Differentially Contribute to Cognitive Heterogeneity in Parkinson's Disease.

    Directory of Open Access Journals (Sweden)

    Niels J H M Gerrits

    Full Text Available Parkinson's disease (PD is often associated with cognitive deficits, although their severity varies considerably between patients. Recently, we used voxel-based morphometry (VBM to show that individual differences in gray matter (GM volume relate to cognitive heterogeneity in PD. VBM does, however, not differentiate between cortical thickness (CTh and surface area (SA, which might be independently affected in PD. We therefore re-analyzed our cohort using the surface-based method FreeSurfer, and investigated (i CTh, SA, and (subcortical GM volume differences between 93 PD patients and 45 matched controls, and (ii the relation between these structural measures and cognitive performance on six neuropsychological tasks within the PD group. We found cortical thinning in PD patients in the left pericalcarine gyrus, extending to cuneus, precuneus and lingual areas and left inferior parietal cortex, bilateral rostral middle frontal cortex, and right cuneus, and increased cortical surface area in the left pars triangularis. Within the PD group, we found negative correlations between (i CTh of occipital areas and performance on a verbal memory task, (ii SA and volume of the frontal cortex and visuospatial memory performance, and, (iii volume of the right thalamus and scores on two verbal fluency tasks. Our primary findings illustrate that i CTh and SA are differentially affected in PD, and ii VBM and FreeSurfer yield non-overlapping results in an identical dataset. We argue that this discrepancy is due to technical differences and the subtlety of the PD-related structural changes.

  15. Vivaldi: A Domain-Specific Language for Volume Processing and Visualization on Distributed Heterogeneous Systems.

    Science.gov (United States)

    Choi, Hyungsuk; Choi, Woohyuk; Quan, Tran Minh; Hildebrand, David G C; Pfister, Hanspeter; Jeong, Won-Ki

    2014-12-01

    As the size of image data from microscopes and telescopes increases, the need for high-throughput processing and visualization of large volumetric data has become more pressing. At the same time, many-core processors and GPU accelerators are commonplace, making high-performance distributed heterogeneous computing systems affordable. However, effectively utilizing GPU clusters is difficult for novice programmers, and even experienced programmers often fail to fully leverage the computing power of new parallel architectures due to their steep learning curve and programming complexity. In this paper, we propose Vivaldi, a new domain-specific language for volume processing and visualization on distributed heterogeneous computing systems. Vivaldi's Python-like grammar and parallel processing abstractions provide flexible programming tools for non-experts to easily write high-performance parallel computing code. Vivaldi provides commonly used functions and numerical operators for customized visualization and high-throughput image processing applications. We demonstrate the performance and usability of Vivaldi on several examples ranging from volume rendering to image segmentation.

  16. Bacterial dominance in subseafloor sediments characterized by methane hydrates

    Science.gov (United States)

    Briggs, Brandon R.; Inagaki, Fumio; Morono, Yuki; Futagami, Taiki; Huguet, Carme; Rosell-Mele, Antoni; Lorenson, T.D.; Colwell, Frederick S.

    2015-01-01

    The degradation of organic carbon in subseafloor sediments on continental margins contributes to the largest reservoir of methane on Earth. Sediments in the Andaman Sea are composed of ~ 1% marine-derived organic carbon and biogenic methane is present. Our objective was to determine microbial abundance and diversity in sediments that transition the gas hydrate occurrence zone (GHOZ) in the Andaman Sea. Microscopic cell enumeration revealed that most sediment layers harbored relatively low microbial abundance (103–105 cells cm−3). Archaea were never detected despite the use of both DNA- and lipid-based methods. Statistical analysis of terminal restriction fragment length polymorphisms revealed distinct microbial communities from above, within, and below the GHOZ, and GHOZ samples were correlated with a decrease in organic carbon. Primer-tagged pyrosequences of bacterial 16S rRNA genes showed that members of the phylum Firmicutes are predominant in all zones. Compared with other seafloor settings that contain biogenic methane, this deep subseafloor habitat has a unique microbial community and the low cell abundance detected can help to refine global subseafloor microbial abundance.

  17. Fungal colonies in open fractures of subseafloor basalt

    Science.gov (United States)

    Ivarsson, Magnus; Bengtson, Stefan; Skogby, Henrik; Belivanova, Veneta; Marone, Federica

    2013-08-01

    The deep subseafloor crust is one of the few great frontiers of unknown biology on Earth and, still today, the notion of the deep biosphere is commonly based on the fossil record. Interpretation of palaeobiological information is thus central in the exploration of this hidden biosphere and, for each new discovery, criteria used to establish biogenicity are challenged and need careful consideration. In this paper networks of fossilized filamentous structures are for the first time described in open fractures of subseafloor basalts collected at the Emperor Seamounts, Pacific Ocean. These structures have been investigated with optical microscopy, environmental scanning electron microscope, energy dispersive spectrometer, X-ray powder diffraction as well as synchrotron-radiation X-ray tomographic microscopy, and interpreted as fossilized fungal mycelia. Morphological features such as hyphae, yeast-like growth and sclerotia were observed. The fossilized fungi are mineralized by montmorillonite, a process that probably began while the fungi were alive. It seems plausible that the fungi produced mucilaginous polysaccharides and/or extracellular polymeric substances that attracted minerals or clay particles, resulting in complete fossilization by montmorillonite. The findings are in agreement with previous observations of fossilized fungi in subseafloor basalts and establish fungi as regular inhabitants of such settings. They further show that fossilized microorganisms are not restricted to pore spaces filled by secondary mineralizations but can be found in open pore spaces as well. This challenges standard protocols for establishing biogenicity and calls for extra care in data interpretation.

  18. Monte Carlo Investigation on the Effect of Heterogeneities on Strut Adjusted Volume Implant (SAVI) Dosimetry

    Science.gov (United States)

    Koontz, Craig

    Breast cancer is the most prevalent cancer for women with more than 225,000 new cases diagnosed in the United States in 2012 (ACS, 2012). With the high prevalence, comes an increased emphasis on researching new techniques to treat this disease. Accelerated partial breast irradiation (APBI) has been used as an alternative to whole breast irradiation (WBI) in order to treat occult disease after lumpectomy. Similar recurrence rates have been found using ABPI after lumpectomy as with mastectomy alone, but with the added benefit of improved cosmetic and psychological results. Intracavitary brachytherapy devices have been used to deliver the APBI prescription. However, inability to produce asymmetric dose distributions in order to avoid overdosing skin and chest wall has been an issue with these devices. Multi-lumen devices were introduced to overcome this problem. Of these, the Strut-Adjusted Volume Implant (SAVI) has demonstrated the greatest ability to produce an asymmetric dose distribution, which would have greater ability to avoid skin and chest wall dose, and thus allow more women to receive this type of treatment. However, SAVI treatments come with inherent heterogeneities including variable backscatter due to the proximity to the tissue-air and tissue-lung interfaces and variable contents within the cavity created by the SAVI. The dose calculation protocol based on TG-43 does not account for heterogeneities and thus will not produce accurate dosimetry; however Acuros, a model-based dose calculation algorithm manufactured by Varian Medical Systems, claims to accurately account for heterogeneities. Monte Carlo simulation can calculate the dosimetry with high accuracy. In this thesis, a model of the SAVI will be created for Monte Carlo, specifically using MCNP code, in order to explore the affects of heterogeneities on the dose distribution. This data will be compared to TG-43 and Acuros calculated dosimetry to explore their accuracy.

  19. Characterization of Soil Heterogeneity Across Scales in an Intensively Investigated Soil Volume

    Science.gov (United States)

    Patterson, Matthew; Gimenez, Daniel; Nemes, Attila; Dathe, Annette; French, Helen; Bloem, Esther; Koestel, John; Jarvis, Nick

    2016-04-01

    Heterogeneous water flow in undisturbed soils is a natural occurrence that is complex to model due to potential changes in hydraulic properties in soils over changes in space. The use of geophysical methods, such as Electrical Resistivity Tomography (ERT), can provide a minimally-invasive approximation of the spatial heterogeneity of the soil. This spatial distribution can then be combined with measured hydraulic properties to inform a model. An experiment was conducted on an Intensively Investigated Soil Volume (IISV), with dimensions of 2m x 1m x 0.8m, located in an agricultural field that is part of the Gryteland catchment in Ås, Norway. The location of the IISV was determined through surface ERT runs at two sequential resolutions. The first run was used to find an area of higher apparent electrical resistivity in a 23.5 x 11.5 m area with 0.5 m spacing. The second run measured apparent electrical resistivity in a 4.7 x 1 m area with 0.1 m spacing, from which the final IISV volume was derived. Distinct features found in the higher resolution run of the IISV, including a recent tire track from a harvester, were used as a spatial reference point for the installation of 20 pairs of TDR probes and tensiometers. The instruments measured water content, temperature and pressure potential at 10 minute intervals and ran continuously for a period of two weeks. After completion of the data collection the IISV was intensively sampled, with 30 samples taken for bulk density, 62 for hydraulic property measurements, and 20 to be used for both CT scanning and hydraulic property measurements. The measurement of hydraulic properties is ongoing and retention will be measured in the 0 - 100 cm range on a sand table, and from 100 - approx. 900 cm with an automated evaporation method. The formation of spatial clusters to represent the soil heterogeneity as relatively homogeneous units based on mesoscale properties like apparent electrical resistivity, bulk density, texture, in

  20. Simulation of DNAPL migration in heterogeneous translucent porous media based on estimation of representative elementary volume

    Science.gov (United States)

    Wu, Ming; Wu, Jianfeng; Wu, Jichun

    2017-10-01

    When the dense nonaqueous phase liquid (DNAPL) comes into the subsurface environment, its migration behavior is crucially affected by the permeability and entry pressure of subsurface porous media. A prerequisite for accurately simulating DNAPL migration in aquifers is then the determination of the permeability, entry pressure and corresponding representative elementary volumes (REV) of porous media. However, the permeability, entry pressure and corresponding representative elementary volumes (REV) are hard to determine clearly. This study utilizes the light transmission micro-tomography (LTM) method to determine the permeability and entry pressure of two dimensional (2D) translucent porous media and integrates the LTM with a criterion of relative gradient error to quantify the corresponding REV of porous media. As a result, the DNAPL migration in porous media might be accurately simulated by discretizing the model at the REV dimension. To validate the quantification methods, an experiment of perchloroethylene (PCE) migration is conducted in a two-dimensional heterogeneous bench-scale aquifer cell. Based on the quantifications of permeability, entry pressure and REV scales of 2D porous media determined by the LTM and relative gradient error, different models with different sizes of discretization grid are used to simulate the PCE migration. It is shown that the model based on REV size agrees well with the experimental results over the entire migration period including calibration, verification and validation processes. This helps to better understand the microstructures of porous media and achieve accurately simulating DNAPL migration in aquifers based on the REV estimation.

  1. Human-associated fungi in deep subseafloor sediment?

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    Fulfer, V. M.; Kirkpatrick, J. B.; D'Hondt, S.

    2015-12-01

    Recent studies have reported fungi in marine sediment samples from depths as great as 1740 meters below seafloor (mbsf) (Rédou et al., 2014). Such studies have utilized a variety of techniques to identify fungi, including cultivation of isolates, amplicon sequencing, and metagenomics. Six recent studies of marine sediment collectively identify nearly 100 fungal taxa at the genus and species levels (Damare et al., 2006; Lai et al., 2007; Edgcomb et al., 2010; Singh et al., 2010; Orsi et al., 2013; Rédou et al., 2014). Known marine taxa are rarely identified by these studies. For individual studies with more than two taxa, between 16% and 57% of the fungal taxa are human microflora or associated with human environments (e.g., human skin or indoor air). For example, three of the six studies identified Malassezia species that are common skin inhabitants of humans and dogs. Although human-associated taxa have been identified in both shallow and deep sediment, they pose a particularly acute problem for deep subseafloor samples, where claims of a eukaryotic deep biosphere are most striking; depending on the study, 25% to 38% of species identified in sediment taken at depths greater than 40 meters are human-associated. Only one to three species have been reported from each of the four samples taken at depths greater than one km (eight species total; Rédou et al., 2014). Of these eight species, three are human-associated. This ubiquity of human-associated microflora is very problematic for interpretations of an indigenous deep subseafloor fungal community; either human-associated taxa comprise a large fraction of marine sedimentary fungi, or sample and analytical contamination is so widespread that the extent and ubiquity of a deep subseafloor fungal community remains uncertain. This highlights the need for stringent quality control measures throughout coring, sampling, and recovery of marine sediment, and when cultivating, extracting, and/or sequencing fungi from

  2. Metabolic Potential of the Deep Subseafloor at Selected Convergent Margins

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    Cardace, D.; Amend, J. P.; Morris, J. D.

    2005-12-01

    The cold subseafloor is an extreme environment in which microbial metabolism appears to operate slowly but persistently over space and time. At convergent margins, subseafloor microbial communities experience diffuse flow of aqueous fluids through sediment interstices and variable flow of deeply sourced, advecting fluids. When these fluids mix, geochemical disequilibria are established, and may serve as energy sources in microbial metabolism. This study contrasts the metabolic potential of four near trench sedimentary environments associated with the Costa Rica, Cascadia, Nankai, and Izu-Bonin-Marianas subduction zones, which span much of the global range of water depths (~ 2500 to ~ 5800 m) and thermal structure (heat flow at seafloor ~ 15 to ~ 140 mW/m2) outboard of subduction zones. Geochemical data (pH, NH4+, Na+, K+, Fe2+, Ca2+, Mg2+, HCO3-, Cl-, SO42-, SiO2 (aq), CH4 (aq), H2 (aq), PO43-, HS-, and CH3COO-) collected during Ocean Drilling Program Legs 146, 170, 185, 190, and 201 are used in Gibbs free energy minimization calculations to model the bioenergetic potential of key metabolic reactions. At the four sites, pH values are 7.3-8.2, alkalinity values are 1 to 24 mM, and sulfate values are 0 to 30 mM. Notable site-specific differences exist in NH4+ (ranging two orders of magnitude in concentration) and salinity (with reported values up to 40 psu at Izu). The specific reactions considered are: (1) CO2 driven methanogenesis, (2) acetate driven methanogenesis, (3) methanotrophy coupled to sulfate reduction, (4) acetate oxidation coupled to sulfate reduction, (5) acetate oxidation coupled with nitrate reduction, (6) acetate oxidation coupled with ferric iron reduction. The standard Gibbs free energies are combined with the in situ geochemical parameters to calculate overall Gibbs free energies in deep subseafloor environments. In all cases, ferric iron reduction coupled with acetate oxidation yields the greatest energy (~-1600 kJ/mol), followed by nitrate

  3. Intravascular Volume Profiles in Patients with Class I and II Systolic Heart Failure: Heterogeneity and Volume Overload are Common Even in Mild Heart Failure.

    Science.gov (United States)

    Miller, Wayne L; Albers, Diana P; Gansen, Denise N; Mullan, Brian P

    2017-10-02

    While volume overload is a commonly described clinical feature of advanced heart failure (HF), less is known regarding volume profiles of patients with less severe Class I and II HF. Intravascular volume was quantitated by radiolabeled-albumin indicator-dilution technique in clinic out-patients. Forty-six patients [age 61±13 yrs., LVEF 30±8%] were prospectively evaluated with 28 undergoing repeat evaluations at one year. There was no difference in averaged total blood volume (TBV) at baseline between Class I (N=26) and II (N=20) patients (5.6±1.6 vs 6.0±1.3 L, p=0.368) and at one year of follow-up. However, there was marked heterogeneity in plasma volume (-13% to +69% of normal) and red cell mass (RBCM -31% to +50%) profiles with TBV expansion identified in 46% of the cohort while only 48% had a normal TBV. RBCM deficit (true anemia) was common (39%), but a low hemoglobin concentration was accurate in identifying anemia in only 11% of the cohort. RBCM excess (polycythemia) also was identified in 20% of the cohort. Marked heterogeneity in PV and RBCM volume profiles is present even in mild HF and identifying volume overload which was common in early HF has the potential to help guide therapy in the reduction of HF progression. Intravascular volume as a modifiable risk factor in early HF warrants further study. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. 3D highly heterogeneous thermal model of pineal gland in-vitro study for electromagnetic exposure using finite volume method

    Science.gov (United States)

    Cen, Wei; Hoppe, Ralph; Lu, Rongbo; Cai, Zhaoquan; Gu, Ning

    2017-08-01

    In this paper, the relationship between electromagnetic power absorption and temperature distributions inside highly heterogeneous biological samples was accurately determinated using finite volume method. An in-vitro study on pineal gland that is responsible for physiological activities was for the first time simulated to illustrate effectiveness of the proposed method.

  5. Metabolic activity of subseafloor microbes in the South Pacific Gyre

    Science.gov (United States)

    Morono, Y.; Ito, M.; Terada, T.; Inagaki, F.

    2013-12-01

    The South Pacific Gyre (SPG) is characterized as the most oligotrophic open ocean environment. The sediment is rich in oxygen but poor in energy-sources such as reduced organic matter, and hence harbors very low numbers of microbial cells in relatively shallow subseafloor sediment (D'Hondt et al., 2009; Kallmeyer et al., 2012). In such an energy-limited sedimentary habitat, a small size of microbial community persists living functions with extraordinary low oxygen-consumption rate (Røy et al., 2012). During IODP Expedition 329, a series of sediment samples were successfully recovered from 7 drill sites (U1365-1371) from the seafloor to basement in the SPG, providing an unprecedented opportunity to study metabolic activity of the aerobic subseafloor microbial communities. We initiated incubation onboard by adding stable isotope-labeled substrates to the freshly collected sediment sample, such as 13C and/or 15N-labeled bicarbonate, glucose, amino acids, acetate, and ammonium under the (micro-) aerobic condition. One of the technological challenges in this study is to harvest microbial cells from very low-biomass sediment samples for the analysis using nano-scale secondary ion mass spectrometry (NanoSIMS). To address the technical issue, we improved existing cell separation technique for the SPG sediment samples with small inorganic zeolitic grains. By monitoring cell recovery rates through an image-based cell enumeration technique (Morono et al., 2009), we found that cell recovery rates in the SPG sediment samples are generally lower than those in other oceanographic settings (i.e., organic-rich ocean margin sediments). To gain higher cell recovery ratio, we applied multiple density gradient layers, resulting in the cell recovery ratio up to around 80-95% (Morono et al., in press). Then, using the newly developed cell separation technique, we successfully sorted enough number of microbial cells in small spots on the membrane (i.e., 103 to 105 cells per spot). Nano

  6. Relationship of Bacterial Richness to Organic Degradation Rate and Sediment Age in Subseafloor Sediment.

    Science.gov (United States)

    Walsh, Emily A; Kirkpatrick, John B; Pockalny, Robert; Sauvage, Justine; Spivack, Arthur J; Murray, Richard W; Sogin, Mitchell L; D'Hondt, Steven

    2016-08-15

    Subseafloor sediment hosts a large, taxonomically rich, and metabolically diverse microbial ecosystem. However, the factors that control microbial diversity in subseafloor sediment have rarely been explored. Here, we show that bacterial richness varies with organic degradation rate and sediment age. At three open-ocean sites (in the Bering Sea and equatorial Pacific) and one continental margin site (Indian Ocean), richness decreases exponentially with increasing sediment depth. The rate of decrease in richness with increasing depth varies from site to site. The vertical succession of predominant terminal electron acceptors correlates with abundance-weighted community composition but does not drive the vertical decrease in richness. Vertical patterns of richness at the open-ocean sites closely match organic degradation rates; both properties are highest near the seafloor and decline together as sediment depth increases. This relationship suggests that (i) total catabolic activity and/or electron donor diversity exerts a primary influence on bacterial richness in marine sediment and (ii) many bacterial taxa that are poorly adapted for subseafloor sedimentary conditions are degraded in the geologically young sediment, where respiration rates are high. Richness consistently takes a few hundred thousand years to decline from near-seafloor values to much lower values in deep anoxic subseafloor sediment, regardless of sedimentation rate, predominant terminal electron acceptor, or oceanographic context. Subseafloor sediment provides a wonderful opportunity to investigate the drivers of microbial diversity in communities that may have been isolated for millions of years. Our paper shows the impact of in situ conditions on bacterial community structure in subseafloor sediment. Specifically, it shows that bacterial richness in subseafloor sediment declines exponentially with sediment age, and in parallel with organic-fueled oxidation rate. This result suggests that

  7. Hybrid finite volume scheme for a two-phase flow in heterogeneous porous media*

    Directory of Open Access Journals (Sweden)

    Brenner Konstantin

    2012-04-01

    Full Text Available We propose a finite volume method on general meshes for the numerical simulation of an incompressible and immiscible two-phase flow in porous media. We consider the case that can be written as a coupled system involving a degenerate parabolic convection-diffusion equation for the saturation together with a uniformly elliptic equation for the global pressure. The numerical scheme, which is implicit in time, allows computations in the case of a heterogeneous and anisotropic permeability tensor. The convective fluxes, which are non monotone with respect to the unknown saturation and discontinuous with respect to the space variables, are discretized by means of a special Godunov scheme. We prove the existence of a discrete solution which converges, along a subsequence, to a solution of the continuous problem. We present a number of numerical results in space dimension two, which confirm the efficiency of the numerical method. Nous proposons un schéma de volumes finis hybrides pour la discrétisation d’un problème d’écoulement diphasique incompressible et immiscible en milieu poreux. On suppose que ce problème a la forme d’une équation parabolique dégénérée de convection-diffusion en saturation couplée à une équation uniformément elliptique en pression. On considère un schéma implicite en temps, où les flux diffusifs sont discrétisés par la méthode des volumes finis hybride, ce qui permet de pouvoir traiter le cas d’un tenseur de perméabilité anisotrope et hétérogène sur un maillage très général, et l’on s’appuie sur un schéma de Godunov pour la discrétisation des flux convectifs, qui peuvent être non monotones et discontinus par rapport aux variables spatiales. On démontre l’existence d’une solution discrète, dont une sous-suite converge vers une solution faible du problème continu. On présente finalement des cas test bidimensionnels.

  8. Partial volume correction of PET-imaged tumor heterogeneity using expectation maximization with a spatially varying point spread function

    Science.gov (United States)

    Barbee, David L; Flynn, Ryan T; Holden, James E; Nickles, Robert J; Jeraj, Robert

    2010-01-01

    Tumor heterogeneities observed in positron emission tomography (PET) imaging are frequently compromised of partial volume effects which may affect treatment prognosis, assessment, or future implementations such as biologically optimized treatment planning (dose painting). This paper presents a method for partial volume correction of PET-imaged heterogeneous tumors. A point source was scanned on a GE Discover LS at positions of increasing radii from the scanner’s center to obtain the spatially varying point spread function (PSF). PSF images were fit in three dimensions to Gaussian distributions using least squares optimization. Continuous expressions were devised for each Gaussian width as a function of radial distance, allowing for generation of the system PSF at any position in space. A spatially varying partial volume correction (SV-PVC) technique was developed using expectation maximization (EM) and a stopping criterion based on the method’s correction matrix generated for each iteration. The SV-PVC was validated using a standard tumor phantom and a tumor heterogeneity phantom, and was applied to a heterogeneous patient tumor. SV-PVC results were compared to results obtained from spatially invariant partial volume correction (SINV-PVC), which used directionally uniform three dimensional kernels. SV-PVC of the standard tumor phantom increased the maximum observed sphere activity by 55 and 40% for 10 and 13 mm diameter spheres, respectively. Tumor heterogeneity phantom results demonstrated that as net changes in the EM correction matrix decreased below 35%, further iterations improved overall quantitative accuracy by less than 1%. SV-PVC of clinically observed tumors frequently exhibited changes of ±30% in regions of heterogeneity. The SV-PVC method implemented spatially varying kernel widths and automatically determined the number of iterations for optimal restoration, parameters which are arbitrarily chosen in SINV-PVC. Comparing SV-PVC to SINV

  9. A Novel Microbial Habitat in the Mid-Ocean Ridge Subseafloor

    National Research Council Canada - National Science Library

    Melanie Summit; John A. Baross

    2001-01-01

    The subseafloor at the mid-ocean ridge is predicted to be an excellent microbial habitat, because there is abundant space, fluid flow, and geochemical energy in the porous, hydrothermally influenced oceanic crust...

  10. Cellular content of biomolecules in sub-seafloor microbial communities

    DEFF Research Database (Denmark)

    Braun, Stefan; Morono, Yuki; Becker, Kevin W.

    2016-01-01

    Microbial biomolecules, typically from the cell envelope, can provide crucial information about distribution, activity, and adaptations of sub-seafloor microbial communities. However, when cells die these molecules can be preserved in the sediment on timescales that are likely longer than...... the lifetime of their microbial sources. Here we provide for the first time measurements of the cellular content of biomolecules in sedimentary microbial cells. We separated intact cells from sediment matrices in samples from surficial, deeply buried, organic-rich, and organic-lean marine sediments by density...... and mass spectrometry for biomolecule analyses. Because cell extracts from density centrifugation still contained considerable amounts of detrital particles and non-cellular biomolecules, we further purified cells from two samples by fluorescence-activated cell sorting (FACS). Cells from these highly...

  11. Comparison of distinctive models for calculating an interlobar emphysema heterogeneity index in patients prior to endoscopic lung volume reduction

    Directory of Open Access Journals (Sweden)

    Theilig D

    2017-06-01

    Full Text Available Dorothea Theilig,1 Felix Doellinger,1 Alexander Poellinger,1 Vera Schreiter,1 Konrad Neumann,2 Ralf-Harto Hubner31Department of Radiology, Charité Campus Virchow Klinikum, Charité, Universitätsmedizin Berlin, Berlin, Germany; 2Institute of Biometrics and Clinical Epidemiology, Charité Campus Benjamin Franklin, Charité, Universitätsmedizin Berlin, Berlin, Germany; 3Department of Pneumology, Charité Campus Virchow Klinikum, Charité, Universitätsmedizin Berlin, Berlin, GermanyBackground: The degree of interlobar emphysema heterogeneity is thought to play an important role in the outcome of endoscopic lung volume reduction (ELVR therapy of patients with advanced COPD. There are multiple ways one could possibly define interlobar emphysema heterogeneity, and there is no standardized definition.Purpose: The aim of this study was to derive a formula for calculating an interlobar emphysema heterogeneity index (HI when evaluating a patient for ELVR. Furthermore, an attempt was made to identify a threshold for relevant interlobar emphysema heterogeneity with regard to ELVR.Patients and methods: We retrospectively analyzed 50 patients who had undergone technically successful ELVR with placement of one-way valves at our institution and had received lung function tests and computed tomography scans before and after treatment. Predictive accuracy of the different methods for HI calculation was assessed with receiver-operating characteristic curve analysis, assuming a minimum difference in forced expiratory volume in 1 second of 100 mL to indicate a clinically important change.Results: The HI defined as emphysema score of the targeted lobe (TL minus emphysema score of the ipsilateral nontargeted lobe disregarding the middle lobe yielded the best predicative accuracy (AUC =0.73, P=0.008. The HI defined as emphysema score of the TL minus emphysema score of the lung without the TL showed a similarly good predictive accuracy (AUC =0.72, P=0.009. Subgroup

  12. Metagenomic Assessment of a Dynamic Microbial Population from Subseafloor Aquifer Fluids in the Cold, Oxygenated Crust

    Science.gov (United States)

    Tully, B. J.; Heidelberg, J. F.; Kraft, B.; Girguis, P. R.; Huber, J. A.

    2016-12-01

    The oceanic crust contains the largest aquifer on Earth with a volume approximately 2% of the global ocean. Ongoing research at the North Pond (NP) site, west of the Mid-Atlantic Ridge, provides an environment representative of oxygenated crustal aquifers beneath oligotrophic surface waters. Using subseafloor CORK observatories for multiple sampling depths beneath the seafloor, crustal fluids were sampled along the predicted aquifer fluid flow path over a two-year period. DNA was extracted and sequenced for metagenomic analysis from 22 crustal fluid samples, along with the overlying bottom. At broad taxonomic groupings, the aquifer system is highly dynamic over time and space, with shifts in dominant taxa and "blooms" of transient groups that appear at discreet time points and sample depths. We were able to reconstruct 194 high-quality, low-contamination bacterial and archaeal metagenomic-assembled genomes (MAGs) with estimated completeness >50% (429 MAGs >20% complete). Environmental genomes were assigned to phylogenies from the major bacterial phyla, putative novel groups, and poorly sampled phylogenetic groups, including the Marinimicrobia, Candidate Phyla Radiation, and Planctomycetes. Biogeochemically relevant processes were assigned to MAGs, including denitrification, dissimilatory sulfur and hydrogen cycling, and carbon fixation. Collectively, the oxic NP aquifer system represents a diverse, dynamic microbial habitat with the metabolic potential to impact multiple globally relevant biogeochemical cycles, including nitrogen, sulfur, and carbon.

  13. Evaluated kinetic and photochemical data for atmospheric chemistry: Volume V – heterogeneous reactions on solid substrates

    Directory of Open Access Journals (Sweden)

    J. N. Crowley

    2010-09-01

    Full Text Available This article, the fifth in the ACP journal series, presents data evaluated by the IUPAC Subcommittee on Gas Kinetic Data Evaluation for Atmospheric Chemistry. It covers the heterogeneous processes on surfaces of solid particles present in the atmosphere, for which uptake coefficients and adsorption parameters have been presented on the IUPAC website in 2010. The article consists of an introduction and guide to the evaluation, giving a unifying framework for parameterisation of atmospheric heterogeneous processes. We provide summary sheets containing the recommended uptake parameters for the evaluated processes. Four substantial appendices contain detailed data sheets for each process considered for ice, mineral dust, sulfuric acid hydrate and nitric acid hydrate surfaces, which provide information upon which the recommendations are made.

  14. Evaluated kinetic and photochemical data for atmospheric chemistry: Volume VI – heterogeneous reactions with liquid substrates

    Directory of Open Access Journals (Sweden)

    M. Ammann

    2013-08-01

    Full Text Available This article, the sixth in the ACP journal series, presents data evaluated by the IUPAC Task Group on Atmospheric Chemical Kinetic Data Evaluation. It covers the heterogeneous processes involving liquid particles present in the atmosphere with an emphasis on those relevant for the upper troposphere/lower stratosphere and the marine boundary layer, for which uptake coefficients and adsorption parameters have been presented on the IUPAC website since 2009. The article consists of an introduction and guide to the evaluation, giving a unifying framework for parameterisation of atmospheric heterogeneous processes. We provide summary sheets containing the recommended uptake parameters for the evaluated processes. The experimental data on which the recommendations are based are provided in data sheets in separate appendices for the four surfaces considered: liquid water, deliquesced halide salts, other aqueous electrolytes and sulfuric acid.

  15. The Effects of Sand Sediment Volume Heterogeneities on Sound Propagation and Scattering

    Science.gov (United States)

    2013-08-19

    OF RESPONSIBLE PERSON 19b. TELEPHONE NUMBER (Include area code) 3 Attenuation in Sand Sediments Due to Scattering from Porosity Fluctuations. Brian T...sediment with porosity heterogeneities modeled using perturbation theory. The statistics of the het- erogeneities are described by exponential correlation...packing of the sand sediment, the presence of force chains should lead to het- erogeneities in the bulk moduli of the sediment. The local density

  16. Size and carbon content of sub-seafloor microbial cells at Landsort Deep, Baltic Sea

    Directory of Open Access Journals (Sweden)

    Stefan Braun

    2016-08-01

    Full Text Available The discovery of a microbial ecosystem in ocean sediments has evoked interest in life under extreme energy limitation and its role in global element cycling. However, fundamental parameters such as the size and the amount of biomass of sub-seafloor microbial cells are poorly constrained. Here we determined the volume and the carbon content of microbial cells from a marine sediment drill core retrieved by the Integrated Ocean Drilling Program (IODP, Expedition 347, at Landsort Deep, Baltic Sea. To determine their shape and volume, cells were separated from the sediment matrix by multi-layer density centrifugation and visualized via epifluorescence microscopy (FM and scanning electron microscopy (SEM. Total cell-carbon was calculated from amino acid-carbon, which was analyzed by high-performance liquid chromatography (HPLC after cells had been purified by fluorescence-activated cell sorting (FACS. The majority of microbial cells in the sediment have coccoid or slightly elongated morphology. From the sediment surface to the deepest investigated sample (~60 meters below the seafloor, the cell volume of both coccoid and elongated cells decreased by an order of magnitude from approximately 0.05 to 0.005 µm3. The cell-specific carbon content was 19-31 fg C cell-1, which is at the lower end of previous estimates that were used for global estimates of microbial biomass. The cell-specific carbon density increased with sediment depth from about 200 to 1000 fg C µm-3, suggesting that cells decrease their water content and grow small cell sizes as adaptation to the long-term subsistence at very low energy availability in the deep biosphere. We present for the first time depth-related data on the cell volume and carbon content of sedimentary microbial cells buried down to 60 meters below the seafloor. Our data enable estimates of volume- and biomass-specific cellular rates of energy metabolism in the deep biosphere and will improve global estimates of

  17. Cellular content of biomolecules in sub-seafloor microbial communities

    Science.gov (United States)

    Braun, Stefan; Morono, Yuki; Becker, Kevin W.; Hinrichs, Kai-Uwe; Kjeldsen, Kasper U.; Jørgensen, Bo B.; Lomstein, Bente Aa.

    2016-09-01

    Microbial biomolecules, typically from the cell envelope, can provide crucial information about distribution, activity, and adaptations of sub-seafloor microbial communities. However, when cells die these molecules can be preserved in the sediment on timescales that are likely longer than the lifetime of their microbial sources. Here we provide for the first time measurements of the cellular content of biomolecules in sedimentary microbial cells. We separated intact cells from sediment matrices in samples from surficial, deeply buried, organic-rich, and organic-lean marine sediments by density centrifugation. Amino acids, amino sugars, muramic acid, and intact polar lipids were analyzed in both whole sediment and cell extract, and cell separation was optimized and evaluated in terms of purity, separation efficiency, taxonomic resemblance, and compatibility to high-performance liquid chromatography and mass spectrometry for biomolecule analyses. Because cell extracts from density centrifugation still contained considerable amounts of detrital particles and non-cellular biomolecules, we further purified cells from two samples by fluorescence-activated cell sorting (FACS). Cells from these highly purified cell extracts had an average content of amino acids and lipids of 23-28 fg cell-1 and 2.3 fg cell-1, respectively, with an estimated carbon content of 19-24 fg cell-1. In the sediment, the amount of biomolecules associated with vegetative cells was up to 70-fold lower than the total biomolecule content. We find that the cellular content of biomolecules in the marine subsurface is up to four times lower than previous estimates. Our approach will facilitate and improve the use of biomolecules as proxies for microbial abundance in environmental samples and ultimately provide better global estimates of microbial biomass.

  18. Monotone Multiscale Finite Volume Method for Flow in Heterogeneous Porous Media

    NARCIS (Netherlands)

    Wang, Y.; Hajibeygi, H.; Tchelepi, H.A.

    2014-01-01

    The MultiScale Finite-Volume (MSFV) method is known to produce non-monotone solutions. The causes of the non-monotone solutions are identified and connected to the local flux across the boundaries of primal coarse cells induced by the basis functions. We propose a monotone MSFV (m-MSFV) method based

  19. Non-invasive assessment of distribution volume ratios and binding potential: tissue heterogeneity and interindividually averaged time-activity curves

    Energy Technology Data Exchange (ETDEWEB)

    Reimold, M.; Mueller-Schauenburg, W.; Dohmen, B.M.; Bares, R. [Department of Nuclear Medicine, University of Tuebingen, Otfried-Mueller-Strasse 14, 72076, Tuebingen (Germany); Becker, G.A. [Nuclear Medicine, University of Leipzig, Leipzig (Germany); Reischl, G. [Radiopharmacy, University of Tuebingen, Tuebingen (Germany)

    2004-04-01

    Due to the stochastic nature of radioactive decay, any measurement of radioactivity concentration requires spatial averaging. In pharmacokinetic analysis of time-activity curves (TAC), such averaging over heterogeneous tissues may introduce a systematic error (heterogeneity error) but may also improve the accuracy and precision of parameter estimation. In addition to spatial averaging (inevitable due to limited scanner resolution and intended in ROI analysis), interindividual averaging may theoretically be beneficial, too. The aim of this study was to investigate the effect of such averaging on the binding potential (BP) calculated with Logan's non-invasive graphical analysis and the ''simplified reference tissue method'' (SRTM) proposed by Lammertsma and Hume, on the basis of simulated and measured positron emission tomography data [{sup 11}C]d-threo-methylphenidate (dMP) and [{sup 11}C]raclopride (RAC) PET. dMP was not quantified with SRTM since the low k {sub 2} (washout rate constant from the first tissue compartment) introduced a high noise sensitivity. Even for considerably different shapes of TAC (dMP PET in parkinsonian patients and healthy controls, [{sup 11}C]raclopride in patients with and without haloperidol medication) and a high variance in the rate constants (e.g. simulated standard deviation of K {sub 1}=25%), the BP obtained from average TAC was close to the mean BP (<5%). However, unfavourably distributed parameters, especially a correlated large variance in two or more parameters, may lead to larger errors. In Monte Carlo simulations, interindividual averaging before quantification reduced the variance from the SRTM (beyond a critical signal to noise ratio) and the bias in Logan's method. Interindividual averaging may further increase accuracy when there is an error term in the reference tissue assumption E=DV {sub 2}-DV ' (DV {sub 2} = distribution volume of the first tissue compartment, DV &apos

  20. A two-step finite volume method to discretize heterogeneous and anisotropic pressure equation on general grids

    Science.gov (United States)

    Zhang, Wenjuan; Al Kobaisi, Mohammed

    2017-10-01

    A novel Two-Step cell-centered Finite Volume Method (TSFVM) is developed in this work to discretize the heterogeneous and anisotropic pressure equation on triangular and quadrilateral grids in 2D and hexahedral and tetrahedral grids in 3D. Physical properties such as permeability and porosity are piece-wise constant on each grid cell. In the first step, the Galerkin Finite Element Method (FEM) is utilized to compute pressure solutions at all cell vertices. In the second step, pressure values at cell vertices are used to derive continuous two-point flux stencils for cell faces. Mass conservation equations are then written for each cell to obtain a system of linear equations that can be solved for pressure at cell centers. Extensive numerical experiments are carried out to test the performance of our TSFVM. In particular, we compare TSFVM with the classical Multipoint Flux Approximation (MPFA-O) method as well as a more recently developed MPFA method with full pressure support called enhanced MPFA (eMPFA). The results show that the TSFVM compares well with eMPFA for challenging test cases for which MPFA-O breaks down. Specifically, and as a significant step forward, our TSFVM is quite robust for challenging problems involving heterogeneous and highly anisotropic permeability tensors when both MPFA-O and eMPFA suffer from unphysical oscillations. Finally, the numerical convergence study demonstrates that TSFVM has comparable convergence behavior to MPFA-O method for both homogeneous and discontinuous permeability fields.

  1. Mathematical model equation of the volume flows through polymeric membrane of heterogeneous non-ionic solutions.

    Science.gov (United States)

    Slezak, Andrzej; Slezak, Izabella; Zyska, Aleksandra; Jasik-Slezak, Jolanta; Bryll, Arkadiusz

    2005-01-01

    Formalism leading to more general form of the Kedem-Katchalsky equation describing osmotic membrane transport, considering local unhomogenity of solutions called concentration boundary layers and influence of gravitational factor on membrane transport kinetics was presented. In order to test this formalism, osmotic volume flux was calculated, on the basis of experimental membrane transport parameters and aqueous glucose solutions in isothermal conditions. Obtained calculation's results are conformable to adequate experimental results presented in previous paper for flat polymeric membrane used in medicine (Biophys. Chem. 1986, 24, 173).

  2. Distribution of anaerobic carbon monoxide dehydrogenase genes in deep subseafloor sediments.

    Science.gov (United States)

    Hoshino, T; Inagaki, F

    2017-05-01

    Carbon monoxide (CO) is the simplest oxocarbon generated by the decomposition of organic compounds, and it is expected to be in marine sediments in substantial amounts. However, the availability of CO in the deep subseafloor sedimentary biosphere is largely unknown even though anaerobic oxidation of CO is a thermodynamically favourable reaction that possibly occurs with sulphate reduction, methanogenesis, acetogenesis and hydrogenesis. In this study, we surveyed for the first time the distribution of the CO dehydrogenase gene (cooS), which encodes the catalytic beta subunit of anaerobic CO dehydrogenase (CODH), in subseafloor sediment-core samples from the eastern flank of the Juan de Fuca Ridge, Mars-Ursa Basin, Kumano Basin, and off the Shimokita Peninsula, Japan, during Integrated Ocean Drilling Program (IODP) Expeditions 301, 308 and 315 and the D/V Chikyu shakedown cruise CK06-06, respectively. Our results show the occurrence of diverse cooS genes from the seafloor down to about 390 m below the seafloor, suggesting that microbial communities have metabolic functions to utilize CO in anoxic microbial ecosystems beneath the ocean floor, and that the microbial community potentially responsible for anaerobic CO oxidation differs in accordance with possible energy-yielding metabolic reactions in the deep subseafloor sedimentary biosphere. Little is known about the microbial community associated with carbon monoxide (CO) in the deep subseafloor. This study is the first survey of a functional gene encoding anaerobic carbon monoxide dehydrogenase (CODH). The widespread occurrence of previously undiscovered CO dehydrogenase genes (cooS) suggests that diverse micro-organisms are capable of anaerobic oxidation of CO in the deep subseafloor sedimentary biosphere. © 2017 The Society for Applied Microbiology.

  3. Adaptive Mesh Refinement for a Finite Volume Method for Flow and Transport of Radionuclides in Heterogeneous Porous Media

    Directory of Open Access Journals (Sweden)

    Amaziane Brahim

    2014-07-01

    Full Text Available In this paper, we consider adaptive numerical simulation of miscible displacement problems in porous media, which are modeled by single phase flow equations. A vertex-centred finite volume method is employed to discretize the coupled system: the Darcy flow equation and the diffusion-convection concentration equation. The convection term is approximated with a Godunov scheme over the dual finite volume mesh, whereas the diffusion-dispersion term is discretized by piecewise linear conforming finite elements. We introduce two kinds of indicators, both of them of residual type. The first one is related to time discretization and is local with respect to the time discretization: thus, at each time, it provides an appropriate information for the choice of the next time step. The second is related to space discretization and is local with respect to both the time and space variable and the idea is that at each time it is an efficient tool for mesh adaptivity. An error estimation procedure evaluates where additional refinement is needed and grid generation procedures dynamically create or remove fine-grid patches as resolution requirements change. The method was implemented in the software MELODIE, developed by the French Institute for Radiological Protection and Nuclear Safety (IRSN, Institut de Radioprotection et de Sûreté Nucléaire. The algorithm is then used to simulate the evolution of radionuclide migration from the waste packages through a heterogeneous disposal, demonstrating its capability to capture complex behavior of the resulting flow.

  4. Efficacy of bronchoscopic lung volume reduction by endobronchial valves in patients with heterogeneous emphysema: report on the first Asian cases.

    Science.gov (United States)

    Park, Tai Sun; Hong, Yoonki; Lee, Jae Seung; Lee, Sang Min; Seo, Joon Beom; Oh, Yeon-Mok; Lee, Sang-Do; Lee, Sei Won

    2014-10-01

    Although many patients with severe emphysema have benefited from bronchoscopic lung volume reduction (BLVR) worldwide, experience of BLVR in Asian emphysema patients is scarce. Between July 2012 and March 2013, seven patients with advanced heterogeneous emphysema underwent BLVR in the Asan Medical Center. They had severe dyspnea and poor lung function (Modified Medical Research Council dyspnea scale 3-4; median forced expiratory volume in 1 sec [FEV1], 0.59 L [19.0 % predicted]; median 6-min walk distance [6MWD], 195 m). Endobronchial valves were inserted into the target lobe which was most hyperinflated and least perfused, and had no collateral ventilation with other lobes. Six patients showed clinical improvement after 1 month. Of them, 2 patients improved to dyspnea scale 1 and 4 patients did to scale 2 (P = 0.026). The median FEV1 increased from 0.59 to 0.89 L (51%; P = 0.028) and the median 6MWD increased from 195 to 252 m (29.2%; P = 0.028). Two patients developed a pneumothorax (one requiring drainage) and one patient experienced slight hemoptysis; however, there were no other serious adverse events. BLVR is effective in Asian advanced emphysema patients, with noted clinical improvements in lung function and exercise capacity.

  5. Finite volume approximation of the three-dimensional flow equation in axisymmetric, heterogeneous porous media based on local analytical solution

    KAUST Repository

    Salama, Amgad

    2013-09-01

    In this work the problem of flow in three-dimensional, axisymmetric, heterogeneous porous medium domain is investigated numerically. For this system, it is natural to use cylindrical coordinate system, which is useful in describing phenomena that have some rotational symmetry about the longitudinal axis. This can happen in porous media, for example, in the vicinity of production/injection wells. The basic feature of this system is the fact that the flux component (volume flow rate per unit area) in the radial direction is changing because of the continuous change of the area. In this case, variables change rapidly closer to the axis of symmetry and this requires the mesh to be denser. In this work, we generalize a methodology that allows coarser mesh to be used and yet yields accurate results. This method is based on constructing local analytical solution in each cell in the radial direction and moves the derivatives in the other directions to the source term. A new expression for the harmonic mean of the hydraulic conductivity in the radial direction is developed. Apparently, this approach conforms to the analytical solution for uni-directional flows in radial direction in homogeneous porous media. For the case when the porous medium is heterogeneous or the boundary conditions is more complex, comparing with the mesh-independent solution, this approach requires only coarser mesh to arrive at this solution while the traditional methods require more denser mesh. Comparisons for different hydraulic conductivity scenarios and boundary conditions have also been introduced. © 2013 Elsevier B.V.

  6. Assessment of research needs for advanced heterogeneous catalysts for energy applications. Final report: Volume 2, Topic reports

    Energy Technology Data Exchange (ETDEWEB)

    Mills, G.A.

    1994-04-01

    This report assesses the direction, technical content, and priority of research needs judged to provide the best chance of yielding new and improved heterogeneous catalysts for energy-related applications over the period of 5-20 years. It addresses issues of energy conservation, alternate fuels and feedstocks, and the economics and applications that could alleviate pollution from energy processes. Recommended goals are defined in 3 research thrusts: catalytic science, environmental protection by catalysis, and industrial catalytic applications. This study was conducted by an 11-member panel of experts from industry and academia, including one each from Japan and Europe. This volume first presents an in-depth overview of the role of catalysis in future energy technology in chapter 1; then current catalytic research is critically reviewed and research recommended in 8 topic chapters: catalyst preparation (design and synthesis), catalyst characterization (structure/function), catalyst performance testing, reaction kinetics/reactor design, catalysis for industrial chemicals, catalysis for electrical applications (clean fuels, pollution remediation), catalysis for control of exhaust emissions, and catalysts for liquid transportation fuels from petroleum, coal, residual oil, and biomass.

  7. Hot-alkaline DNA extraction method for deep-subseafloor archaeal communities.

    Science.gov (United States)

    Morono, Yuki; Terada, Takeshi; Hoshino, Tatsuhiko; Inagaki, Fumio

    2014-03-01

    A prerequisite for DNA-based microbial community analysis is even and effective cell disruption for DNA extraction. With a commonly used DNA extraction kit, roughly two-thirds of subseafloor sediment microbial cells remain intact on average (i.e., the cells are not disrupted), indicating that microbial community analyses may be biased at the DNA extraction step, prior to subsequent molecular analyses. To address this issue, we standardized a new DNA extraction method using alkaline treatment and heating. Upon treatment with 1 M NaOH at 98°C for 20 min, over 98% of microbial cells in subseafloor sediment samples collected at different depths were disrupted. However, DNA integrity tests showed that such strong alkaline and heat treatment also cleaved DNA molecules into short fragments that could not be amplified by PCR. Subsequently, we optimized the alkaline and temperature conditions to minimize DNA fragmentation and retain high cell disruption efficiency. The best conditions produced a cell disruption rate of 50 to 80% in subseafloor sediment samples from various depths and retained sufficient DNA integrity for amplification of the complete 16S rRNA gene (i.e., ∼1,500 bp). The optimized method also yielded higher DNA concentrations in all samples tested compared with extractions using a conventional kit-based approach. Comparative molecular analysis using real-time PCR and pyrosequencing of bacterial and archaeal 16S rRNA genes showed that the new method produced an increase in archaeal DNA and its diversity, suggesting that it provides better analytical coverage of subseafloor microbial communities than conventional methods.

  8. Atribacteria from the Subseafloor Sedimentary Biosphere Disperse to the Hydrosphere through Submarine Mud Volcanoes

    Science.gov (United States)

    Hoshino, Tatsuhiko; Toki, Tomohiro; Ijiri, Akira; Morono, Yuki; Machiyama, Hideaki; Ashi, Juichiro; Okamura, Kei; Inagaki, Fumio

    2017-01-01

    Submarine mud volcanoes (SMVs) are formed by muddy sediments and breccias extruded to the seafloor from a source in the deep subseafloor and are characterized by the discharge of methane and other hydrocarbon gasses and deep-sourced fluids into the overlying seawater. Although SMVs act as a natural pipeline connecting the Earth’s surface and subsurface biospheres, the dispersal of deep-biosphere microorganisms and their ecological roles remain largely unknown. In this study, we investigated the microbial communities in sediment and overlying seawater at two SMVs located on the Ryukyu Trench off Tanegashima Island, southern Japan. The microbial communities in mud volcano sediments were generally distinct from those in the overlying seawaters and in the well-stratified Pacific margin sediments collected at the Peru Margin, the Juan de Fuca Ridge flank off Oregon, and offshore of Shimokita Peninsula, northeastern Japan. Nevertheless, in-depth analysis of different taxonomic groups at the sub-species level revealed that the taxon affiliated with Atribacteria, heterotrophic anaerobic bacteria that typically occur in organic-rich anoxic subseafloor sediments, were commonly found not only in SMV sediments but also in the overlying seawater. We designed a new oligonucleotide probe for detecting Atribacteria using the catalyzed reporter deposition-fluorescence in situ hybridization (CARD-FISH). CARD-FISH, digital PCR and sequencing analysis of 16S rRNA genes consistently showed that Atribacteria are abundant in the methane plumes of the two SMVs (0.58 and 1.5 × 104 cells/mL, respectively) but not in surrounding waters, suggesting that microbial cells in subseafloor sediments are dispersed as “deep-biosphere seeds” into the ocean. These findings may have important implications for the microbial transmigration between the deep subseafloor biosphere and the hydrosphere. PMID:28676800

  9. Distribution of dehalogenation activity in subseafloor sediments of the Nankai Trough subduction zone.

    Science.gov (United States)

    Futagami, Taiki; Morono, Yuki; Terada, Takeshi; Kaksonen, Anna H; Inagaki, Fumio

    2013-04-19

    Halogenated organic matter buried in marine subsurface sediment may serve as a source of electron acceptors for anaerobic respiration of subseafloor microbes. Detection of a diverse array of reductive dehalogenase-homologous (rdhA) genes suggests that subseafloor organohalide-respiring microbial communities may play significant ecological roles in the biogeochemical carbon and halogen cycle in the subseafloor biosphere. We report here the spatial distribution of dehalogenation activity in the Nankai Trough plate-subduction zone of the northwest Pacific off the Kii Peninsula of Japan. Incubation experiments with slurries of sediment collected at various depths and locations showed that degradation of several organohalides tested only occurred in the shallow sedimentary basin, down to 4.7 metres below the seafloor, despite detection of rdhA in the deeper sediments. We studied the phylogenetic diversity of the metabolically active microbes in positive enrichment cultures by extracting RNA, and found that Desulfuromonadales bacteria predominate. In addition, for the isolation of genes involved in the dehalogenation reaction, we performed a substrate-induced gene expression screening on DNA extracted from the enrichment cultures. Diverse DNA fragments were obtained and some of them showed best BLAST hit to known organohalide respirers such as Dehalococcoides, whereas no functionally known dehalogenation-related genes such as rdhA were found, indicating the need to improve the molecular approach to assess functional genes for organohalide respiration.

  10. A method for partial volume correction of PET-imaged tumor heterogeneity using expectation maximization with a spatially varying point spread function.

    Science.gov (United States)

    Barbee, David L; Flynn, Ryan T; Holden, James E; Nickles, Robert J; Jeraj, Robert

    2010-01-07

    Tumor heterogeneities observed in positron emission tomography (PET) imaging are frequently compromised by partial volume effects which may affect treatment prognosis, assessment or future implementations such as biologically optimized treatment planning (dose painting). This paper presents a method for partial volume correction of PET-imaged heterogeneous tumors. A point source was scanned on a GE Discovery LS at positions of increasing radii from the scanner's center to obtain the spatially varying point spread function (PSF). PSF images were fit in three dimensions to Gaussian distributions using least squares optimization. Continuous expressions were devised for each Gaussian width as a function of radial distance, allowing for generation of the system PSF at any position in space. A spatially varying partial volume correction (SV-PVC) technique was developed using expectation maximization (EM) and a stopping criterion based on the method's correction matrix generated for each iteration. The SV-PVC was validated using a standard tumor phantom and a tumor heterogeneity phantom and was applied to a heterogeneous patient tumor. SV-PVC results were compared to results obtained from spatially invariant partial volume correction (SINV-PVC), which used directionally uniform three-dimensional kernels. SV-PVC of the standard tumor phantom increased the maximum observed sphere activity by 55 and 40% for 10 and 13 mm diameter spheres, respectively. Tumor heterogeneity phantom results demonstrated that as net changes in the EM correction matrix decreased below 35%, further iterations improved overall quantitative accuracy by less than 1%. SV-PVC of clinically observed tumors frequently exhibited changes of +/-30% in regions of heterogeneity. The SV-PVC method implemented spatially varying kernel widths and automatically determined the number of iterations for optimal restoration, parameters which are arbitrarily chosen in SINV-PVC. Comparing SV-PVC to SINV-PVC demonstrated

  11. Life in the Anoxic Sub-Seafloor Environment: Linking Microbial Metabolism and Mega Reserves of Methane Hydrate.

    Science.gov (United States)

    Honkalas, Varsha; Dabir, Ashwini; Dhakephalkar, Prashant K

    Sub-seafloor methane hydrate deposits have attracted attention in recent times as an enormous and yet untapped source of alternate energy. It is interesting to note that methane in sub-seafloor methane hydrate deposits is of biogenic origin. The sub-seafloor environment is mostly anoxic and characterized by high pressure and the presence of complex organic matter. Microorganisms adapted to such extreme sub-seafloor environmental conditions may serve as source of novel taxa and industrially valuable biomolecules. Microbial metabolism is responsible for the degradation of complex organic matter and subsequent formation of methane. Various ecophysiological and nutrient conditions have a significant influence on the rate of methane formation and on the conversion of methane into methane hydrate deposits. Understanding the kinetics of methanogenesis is of utmost importance in predicting the rate and extent of methane hydrate deposits in sub-seafloor environments. This review illustrates the diversity of anaerobes in deep-sea sediments associated with methane hydrates and their metabolism leading to methane generation.

  12. A dynamic microbial community with high functional redundancy inhabits the cold, oxic subseafloor aquifer.

    Science.gov (United States)

    Tully, Benjamin J; Wheat, C Geoff; Glazer, Brain T; Huber, Julie A

    2017-11-03

    The rock-hosted subseafloor crustal aquifer harbors a reservoir of microbial life that may influence global marine biogeochemical cycles. Here we utilized metagenomic libraries of crustal fluid samples from North Pond, located on the flanks of the Mid-Atlantic Ridge, a site with cold, oxic subseafloor fluid circulation within the upper basement to query microbial diversity. Twenty-one samples were collected during a 2-year period to examine potential microbial metabolism and community dynamics. We observed minor changes in the geochemical signatures over the 2 years, yet the microbial community present in the crustal fluids underwent large shifts in the dominant taxonomic groups. An analysis of 195 metagenome-assembled genomes (MAGs) were generated from the data set and revealed a connection between litho- and autotrophic processes, linking carbon fixation to the oxidation of sulfide, sulfur, thiosulfate, hydrogen, and ferrous iron in members of the Proteobacteria, specifically the Alpha-, Gamma- and Zetaproteobacteria, the Epsilonbacteraeota and the Planctomycetes. Despite oxic conditions, analysis of the MAGs indicated that members of the microbial community were poised to exploit hypoxic or anoxic conditions through the use of microaerobic cytochromes, such as cbb3- and bd-type cytochromes, and alternative electron acceptors, like nitrate and sulfate. Temporal and spatial trends from the MAGs revealed a high degree of functional redundancy that did not correlate with the shifting microbial community membership, suggesting functional stability in mediating subseafloor biogeochemical cycles. Collectively, the repeated sampling at multiple sites, together with the successful binning of hundreds of genomes, provides an unprecedented data set for investigation of microbial communities in the cold, oxic crustal aquifer.The ISME Journal advance online publication, 3 November 2017; doi:10.1038/ismej.2017.187.

  13. A Fungal-Prokaryotic Consortium at the Basalt-Zeolite Interface in Subseafloor Igneous Crust

    Science.gov (United States)

    Ivarsson, Magnus; Bengtson, Stefan; Skogby, Henrik; Lazor, Peter; Broman, Curt; Belivanova, Veneta; Marone, Federica

    2015-01-01

    We have after half a century of coordinated scientific drilling gained insight into Earth´s largest microbial habitat, the subseafloor igneous crust, but still lack substantial understanding regarding its abundance, diversity and ecology. Here we describe a fossilized microbial consortium of prokaryotes and fungi at the basalt-zeolite interface of fractured subseafloor basalts from a depth of 240 m below seafloor (mbsf). The microbial consortium and its relationship with the surrounding physical environment are revealed by synchrotron-based X-ray tomographic microscopy (SRXTM), environmental scanning electron microscopy (ESEM), and Raman spectroscopy. The base of the consortium is represented by microstromatolites—remains of bacterial communities that oxidized reduced iron directly from the basalt. The microstromatolites and the surrounding basalt were overlaid by fungal cells and hyphae. The consortium was overgrown by hydrothermally formed zeolites but remained alive and active during this event. After its formation, fungal hyphae bored in the zeolite, producing millimetre-long tunnels through the mineral substrate. The dissolution could either serve to extract metals like Ca, Na and K essential for fungal growth and metabolism, or be a response to environmental stress owing to the mineral overgrowth. Our results show how microbial life may be maintained in a nutrient-poor and extreme environment by close ecological interplay and reveal an effective strategy for nutrient extraction from minerals. The prokaryotic portion of the consortium served as a carbon source for the eukaryotic portion. Such an approach may be a prerequisite for prokaryotic-eukaryotic colonisation of, and persistence in, subseafloor igneous crust. PMID:26488482

  14. Phylogenetic Diversity of aprA Genes in Subseafloor Sediments on the Northwestern Pacific Margin off Japan.

    Science.gov (United States)

    Aoki, Masataka; Kakiuchi, Ryota; Yamaguchi, Takashi; Takai, Ken; Inagaki, Fumio; Imachi, Hiroyuki

    2015-01-01

    Markedly diverse sequences of the adenosine-5'-phosphosulfate reductase alpha subunit gene (aprA), which encodes a key enzyme in microbial sulfate reduction and sulfur oxidation, were detected in subseafloor sediments on the northwestern Pacific off Japan. The aprA gene sequences were grouped into 135 operational taxonomic units (90% sequence identity), including genes related to putative sulfur-oxidizing bacteria predominantly detected in sulfate-depleted deep sediments. Our results suggest that microbial ecosystems in the subseafloor biosphere have phylogenetically diverse genetic potentials to mediate cryptic sulfur cycles in sediments, even where sulfate is rarely present.

  15. Draft genome sequence of Clostridium celerecrescens 152B isolated from sub-seafloor methane hydrate deposits.

    Science.gov (United States)

    Honkalas, Varsha S; Dabir, Ashwini P; Arora, Preeti; Ranade, Dilip R; Dhakephalkar, Prashant K

    2015-06-01

    Clostridium celerecrescens 152B is an obligate anaerobic, Gram positive rod shaped bacterium isolated from sub-seafloor methane hydrate sediments of Krishna Godavari basin, India. Here, we report the first draft genome sequence of C. celerecrescens 152B, which comprises 5,050,495bp in 92 contigs with the G+C content of 43.5%. The whole genome of C. celerecrescens 152B was sequenced for further biotechnological exploitation of its genome features especially regarding the production of secondary metabolites as well as for environmental bioremediation and production of industrially valuable enzymes. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Microbial population, activity, and phylogenetic diversity in the subseafloor core sediment from the Sea of Okhotsk

    Science.gov (United States)

    Inagaki, F.; Suzuki, M.; Takai, K.; Nealson, K. H.; Horikoshi, K.

    2002-12-01

    Subseafloor environments has already been recognized as the largest biosphere on the planet Earth, however, the microbial diversity and activity has been still poorly understood, even in their impacts on biogeochemical processes, tectonic settings, and paleoenvironmental events. We demonstrate here the evaluation of microbial community structure and active habitats in deeply buried cold marine sediments collected from the Sea of Okhotsk by a combined use of molecular ecological surveys and culturing assays. The piston core sediment (MD01-2412) was collected by IMAGES (International Marine Global Change Study) Project from the southeastern Okhotsk Sea, June 2001. The total recovered length was about 58m. The lithology of the core sediment was mainly constructed from pelagic clay (PC) and volcanic ash layers (Ash). We collected aseptically the most inside core parts from 16 sections at different depths for microbiological study. The direct count of DAPI-stained cells revealed that the cells in Ash samples were present 1.2 to 2.2 times higher than in PC samples. The quantitative-PCR of 16S rDNA between bacterial and archaeal rDNA suggested that the increased population density in Ash layers was caused by the bacterial components. We studied approximately 650 and 550 sequences from bacterial and archaeal rDNA clone libraries, respectively. The similarity and phylogenetic analyses revealed that the microbial community structures were apparently different between in Ash layers and PC samples. From bacterial rDNA clone libraries, the members within gamma-Proteobacteria such as genera Halomonas, Shewanella, Psychromonas and Methylosinus were predominantly detected in Ash layers whereas the Dehalococcoides group and delta-Proteobacteria were major bacterial components in PC samples. From archaeal libraries, the sequences from Ash and PC samples were affiliated into the clusters represented by the environmental sequences obtained from terrestrial and deep-sea environments

  17. Simultaneous assessment of cerebral blood volume and diffusion heterogeneity using hybrid IVIM and DK MR imaging: initial experience with brain tumors

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Wen-Chau [National Taiwan University, Graduate Institute of Oncology, Taipei (China); National Taiwan University, Graduate Institute of Clinical Medicine, Taipei (China); National Taiwan University, Graduate Institute of Biomedical Electronics and Bioinformatics, Taipei (China); National Taiwan University Hospital, Department of Medical Imaging, Taipei (China); Yang, Shun-Chung; Chen, Ya-Fang; My, Pei-Chi [National Taiwan University Hospital, Department of Medical Imaging, Taipei (China); Tseng, Han-Min [National Taiwan University Hospital, Department of Neurology, Taipei (China)

    2017-01-15

    To investigate the feasibility of simultaneously assessing cerebral blood volume and diffusion heterogeneity using hybrid diffusion-kurtosis (DK) and intravoxel-incoherent-motion (IVIM) MR imaging. Fifteen healthy volunteers and 30 patients with histologically proven brain tumours (25 WHO grade II-IV gliomas and five metastases) were recruited. On a 3-T system, diffusion-weighted imaging was performed with six b-values ranging from 0 to 1,700 s/mm{sup 2}. Nonlinear least-squares fitting was employed to extract diffusion coefficient (D), diffusion kurtosis coefficient (K, a measure of the degree of non-Gaussian and heterogeneous diffusion) and intravascular volume fraction (f, a measure proportional to cerebral blood volume). Repeated-measures multivariate analysis of variance and receiver operating characteristic analysis were performed to assess the ability of D/K/f in differentiating contrast-enhanced tumour from peritumoral oedema and normal-appearing white matter. Based on our imaging setting (baseline signal-to-noise ratio = 32-128), coefficient of variation was 14-20 % for K, ∝6 % for D and 26-44 % for f. The indexes were able to differentiate contrast-enhanced tumour (Wilks' λ = 0.026, p < 10{sup -3}), and performance was greatest with K, followed by f and D. Hybrid DK IVIM imaging is capable of simultaneously measuring cerebral perfusion and diffusion indexes that together may improve brain tumour diagnosis. (orig.)

  18. IODP Expedition 331: Strong and Expansive Subseafloor Hydrothermal Activities in the Okinawa Trough

    Directory of Open Access Journals (Sweden)

    the IODP Expedition 331 Scientists

    2012-04-01

    Full Text Available Integrated Ocean Drilling Program (IODP Expedition 331 drilled into the Iheya North hydrothermal system in the middle Okinawa Trough in order to investigate active subseafloor microbial ecosystems and their physical and chemical settings. We drilled five sites during Expedition 331 using special guide bases at three holes for reentry, casing, and capping, including installation of a steel mesh platformwith valve controls for postcruise sampling of fluids. At Site C0016, drilling at the base of the North Big Chimney (NBCmound yielded low recovery, but core included the first Kuroko-type black ore ever recovered from the modern subseafloor. The other four sites yielded interbedded hemipelagic and strongly pumiceous volcaniclastic sediment, along with volcanogenic breccias that are variably hydrothermally altered and mineralized. At most sites, analyses of interstitial water and headspace gas yielded complex patterns withdepth and lateral distance of only a few meters. Documented processes included formation of brines and vapor-rich fluids by phase separation and segregation, uptake of Mg and Na by alteration minerals in exchange for Ca, leaching of K at high temperature and uptake at low temperature, anhydrite precipitation, potential microbial oxidation of organic matter and anaerobic oxidation of methane utilizing sulfate, and methanogenesis. Shipboard analyses have found evidence for microbial activity in sediments within the upper 10–30 m below seafloor (mbsf where temperatures were relativelylow, but little evidence in the deeper hydrothermally altered zones and hydrothermal fluid regime.

  19. Where the Wild Microbes Are: Education and Outreach on Sub-Seafloor Microbes

    Science.gov (United States)

    Cooper, S. K.; Kurtz, K.; Orcutt, B.; Strong, L.; Collins, J.; Feagan, A.

    2014-12-01

    Sub-seafloor microbiology has the power to spark the imaginations of children, students and the general public with its mysterious nature, cutting-edge research, and connections to the search for extraterrestrial life. These factors have been utilized to create a number of educational and outreach products to bring subsurface microbes to non-scientist audiences in creative and innovative ways. The Adopt a Microbe curriculum for middle school students provides hands-on activities and investigations for students to learn about microbes and the on-going research about them, and provides opportunities to connect with active expeditions. A new series of videos engages non-scientists with stories about research expeditions and the scientists themselves. A poster and associated activities explore the nature of science using a microbiologist and her research as examples. A new e-book for young children will engage them with age-appropriate text and illustrations. These projects are multidisciplinary, involve science and engineering practices, are available to all audiences and provide examples of high level and meaningful partnerships between scientists and educators and the kinds of products that can result. Subseafloor microbiology projects such as these, aimed at K-12 students and the general public, have the potential to entice the interest of the next generation of microbe scientists and increase general awareness of this important science.

  20. Using Interactive eBooks To Educate Children About Sub-seafloor Science

    Science.gov (United States)

    Kurtz, K.

    2016-02-01

    Sub-seafloor scientific research has the power to spark the imaginations of elementary age children with its mysterious nature, cutting-edge research, and its connections to kid friendly science topics, such as volcanoes, the extinction of dinosaurs and the search for extraterrestrial life. These factors have been utilized to create two interactive eBooks for elementary students and teachers, integrating high quality science information, highly engaging and age-appropriate illustrations, and rhyming text. The first eBook introduces children to the research and discoveries of the JOIDES Resolution research vessel. The creators were able to build-on the knowledge gained in creating the first eBook to create a second eBook that focuses on the discoveries of microbial life in the sub-seafloor. The eBooks present information as traditional, linear, illustrated children's books, but the eBook format allows the book to be available online for free to anyone and allows teachers to project the book on a classroom screen so all students can easily see the illustrations. The iPad versions also provide an interactive, learner-led educational experience, where cognitively appropriate videos, photos and other forms of information can be accessed with the tap of a finger to answer reader questions and enrich their learning experience. These projects provide an example and model of the products that can result from high level and meaningful partnerships between scientists, educators, artists and writers.

  1. Ship space to database: emerging infrastructures for studies of the deep subseafloor biosphere

    Directory of Open Access Journals (Sweden)

    Peter T. Darch

    2016-11-01

    Full Text Available Background An increasing array of scientific fields face a “data deluge.” However, in many fields data are scarce, with implications for their epistemic status and ability to command funding. Consequently, they often attempt to develop infrastructure for data production, management, curation, and circulation. A component of a knowledge infrastructure may serve one or more scientific domains. Further, a single domain may rely upon multiple infrastructures simultaneously. Studying how domains negotiate building and accessing scarce infrastructural resources that they share with other domains will shed light on how knowledge infrastructures shape science. Methods We conducted an eighteen-month, qualitative study of scientists studying the deep subseafloor biosphere, focusing on the Center for Dark Energy Biosphere Investigations (C-DEBI and the Integrated Ocean Drilling Program (IODP and its successor, the International Ocean Discovery Program (IODP2. Our methods comprised ethnographic observation, including eight months embedded in a laboratory, interviews (n = 49, and document analysis. Results Deep subseafloor biosphere research is an emergent domain. We identified two reasons for the domain’s concern with data scarcity: limited ability to pursue their research objectives, and the epistemic status of their research. Domain researchers adopted complementary strategies to acquire more data. One was to establish C-DEBI as an infrastructure solely for their domain. The second was to use C-DEBI as a means to gain greater access to, and reconfigure, IODP/IODP2 to their advantage. IODP/IODP2 functions as infrastructure for multiple scientific domains, which creates competition for resources. C-DEBI is building its own data management infrastructure, both to acquire more data from IODP and to make better use of data, once acquired. Discussion Two themes emerge. One is data scarcity, which can be understood only in relation to a domain

  2. High-resolution temporal analysis of deep subseafloor microbial communities inhabiting basement fluids

    Science.gov (United States)

    Jungbluth, S.; Lin, H. T.; Hsieh, C. C.; Rappe, M. S.

    2014-12-01

    The temporal variation in microbial communities inhabiting the anoxic, sediment-covered basaltic ocean basement is largely uncharacterized due to the inaccessible nature of the environment and difficulties associated with collection of samples from low-biomass microbial habitats. Here, a deep sea instrumented platform was employed on the Juan de Fuca Ridge in the summer of 2013 to collect 46 samples of basement fluids from the most recent generation of borehole observatories (U1362A and B), which feature multiple sampling horizons at a single location and fluid delivery lines manufactured using stainless steel or inert polytetrafluoroethylene (PTFE) parts. Included were three time-series deployments of the GEOmicrobe sled meant to resolve the fine-scale (i.e. hourly) temporal variation within in situ crustal microbial communities. Illumina technology was used to sequence small subunit ribosomal RNA (SSU rRNA) gene fragments from sediment, seawater, and subseafloor fluids. Similar to has been reported previously, basic differences in the three environments was observed. Fluid samples from depth horizons extending 30, 70, and ~200 meters sub-basement revealed differences in the observed microbial communities, indicating potential depth-specific zonation of microorganisms in the basaltic basement fluids. Extensive overlap between microorganisms collected from a single depth horizon but using two fluid delivery lines manufactured with different materials was observed, though some differences were also noted. Several archaeal (e.g. THSCG, MCG, MBGE, Archaeoglobus) and bacterial (e.g. Nitrospiraceae, OP8, KB1) lineages detected in previous years of basement fluid sampling nearby were found here, which further supports the notion that these microorganisms are stable residents of anoxic basaltic subseafloor fluids. Direct cell enumeration of samples collected from U1362A and U1362B revealed an elevated biomass compared to samples at these locations from previous years

  3. Preliminary Insights Into the Interplay Among Oxygen, Organic Carbon, and Microbial Metabolism in North Atlantic Subseafloor Sediment Communities

    Science.gov (United States)

    Amenabar, M. J.; Dore, J. E.; Spivack, A. J.; Murray, R. W.; D'Hondt, S.; Boyd, E. S.

    2015-12-01

    Deep marine sediments harbor abundant microbial cells that, if active, are likely to exert a strong influence on element biogeochemical cycling. However, our understanding of the fraction of cells that are active in situ and the metabolic processes that sustain them remain underexplored. Here we describe recent results of our studies aimed at unraveling the links between geochemical heterogeneity, cellular viability and synthesis, and metabolism along a vertical depth profile in sediment from four deep sites (>5 km beneath ocean surface) cored by R/V KNORR Expedition KN-223 in the North Atlantic (2014). These sediment columns exhibit varying levels of organic carbon and different vertical extents of oxygen (O2) penetration, which we hypothesize is due to variation in the extent of heterotrophic metabolism. We prepared most probable number (MPN) assays with acetate or peptone as electron donor and carbon source, and five different terminal electron acceptors (O2, NO3, SO4, MnO2, and ferrihydrite) with sediments from 4 to 5 depths in each of the four cores MPNs were similar for acetate- and peptone-amended cultures, regardless of electron acceptor, and generally decreased with depth in the sediment column. MPNs amended with O2 as electron acceptor were greater than MPNs amended with NO3, SO4, MnO2, and ferrihydrite in samples from all depths. Moreover, MPNs were higher for assays amended with O2 from cores where the depth of O2 penetration was shallow when compared to cores where O2 is predicted to penetrate to basement rock. These results are consistent with aerobic heterotrophs limiting the penetration of O2 in deep marine sediments, and thereby provide a mechanism to explain the relationship between low O2 penetrations in sediment cores with elevated organic carbon contents. We will also present results of our ongoing isotopic labeling experiments aimed at determining rates of DNA and protein synthesis as proxies for cell replication and productivity, respectively

  4. Simultaneous assessment of cerebral blood volume and diffusion heterogeneity using hybrid IVIM and DK MR imaging: initial experience with brain tumors.

    Science.gov (United States)

    Wu, Wen-Chau; Yang, Shun-Chung; Chen, Ya-Fang; Tseng, Han-Min; My, Pei-Chi

    2017-01-01

    To investigate the feasibility of simultaneously assessing cerebral blood volume and diffusion heterogeneity using hybrid diffusion-kurtosis (DK) and intravoxel-incoherent-motion (IVIM) MR imaging. Fifteen healthy volunteers and 30 patients with histologically proven brain tumours (25 WHO grade II-IV gliomas and five metastases) were recruited. On a 3-T system, diffusion-weighted imaging was performed with six b-values ranging from 0 to 1,700 s/mm(2). Nonlinear least-squares fitting was employed to extract diffusion coefficient (D), diffusion kurtosis coefficient (K, a measure of the degree of non-Gaussian and heterogeneous diffusion) and intravascular volume fraction (f, a measure proportional to cerebral blood volume). Repeated-measures multivariate analysis of variance and receiver operating characteristic analysis were performed to assess the ability of D/K/f in differentiating contrast-enhanced tumour from peritumoral oedema and normal-appearing white matter. Based on our imaging setting (baseline signal-to-noise ratio = 32-128), coefficient of variation was 14-20 % for K, ~6 % for D and 26-44 % for f. The indexes were able to differentiate contrast-enhanced tumour (Wilks' λ = 0.026, p cerebral perfusion and diffusion indexes that together may improve brain tumour diagnosis. • Hybrid DK-IVIM imaging allows simultaneous measurement of K, D and f. • Combined K/D/f better demarcates contrast-enhanced tumour than they do separately. • f correlates better with contrast-leakage-corrected CBV DSC than with uncorrected CBV DSC.

  5. Measurement of extracellular volume and transit time heterogeneity using contrast-enhanced myocardial perfusion MRI in patients after acute myocardial infarction.

    Science.gov (United States)

    Kunze, Karl P; Rischpler, Christoph; Hayes, Carmel; Ibrahim, Tareq; Laugwitz, Karl-Ludwig; Haase, Axel; Schwaiger, Markus; Nekolla, Stephan G

    2017-06-01

    To assess the ability of dynamic contrast-enhanced myocardial perfusion MRI to measure extracellular volume (ECV) and to investigate the possibility of estimating capillary transit time heterogeneity (CTH) in patients after myocardial infarction and successful revascularization. Twenty-four perfusion data sets were acquired on a 3 Tesla positron emission tomography (PET)/MRI scanner. Three perfusion models of different complexity were implemented in a hierarchical fashion with an Akaike information criterion being used to determine the number of fit parameters supported by the data. Results were compared sector-wise to ECV from an equilibrium T1 mapping method (modified look-locker inversion recovery (MOLLI)). ECV derived from the perfusion analysis correlated well with equilibrium measurements (R² = 0.76). Estimation of CTH was supported in 16% of sectors (mostly remote). Inclusion of a nonzero CTH parameter usually led to lower estimates of first-pass extraction and slightly higher estimates of blood volume and flow. Estimation of the capillary permeability-surface area product was feasible in 81% of sectors. Transit time heterogeneity has a measurable effect on the kinetic analysis of myocardial perfusion MRI data, and Gd-DTPA extravasation in the myocardium is usually not flow-limited in infarct-related pathology. Measurement of myocardial ECV using perfusion imaging could provide a scan-time efficient alternative to methods based on T1 mapping. Magn Reson Med 77:2320-2330, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  6. Whole-genome sequence of Sunxiuqinia dokdonensis DH1(T), isolated from deep sub-seafloor sediment in Dokdo Island.

    Science.gov (United States)

    Lim, Sooyeon; Chang, Dong-Ho; Kim, Byoung-Chan

    2016-09-01

    Sunxiuqinia dokdonensis DH1(T) was isolated from deep sub-seafloor sediment at a depth of 900 m below the seafloor off Seo-do (the west part of Dokdo Island) in the East Sea of the Republic of Korea and subjected to whole genome sequencing on HiSeq platform and annotated on RAST. The nucleotide sequence of this genome was deposited into DDBJ/EMBL/GenBank under the accession LGIA00000000.

  7. Composite hydrogels with temperature sensitive heterogeneities: influence of gel matrix on the volume phase transition of embedded poly-(N-isopropylacrylamide) microgels.

    Science.gov (United States)

    Meid, Judith; Friedrich, Tatjana; Tieke, Bernd; Lindner, Peter; Richtering, Walter

    2011-02-28

    The thermo-responsive behaviour of poly-(N-isopropylacrylamide) (PNiPAM) microgels embedded in covalently cross-linked non-temperature-sensitive polyacrylamide (PAam) hydrogel matrixes with different compositions was investigated by using small angle neutron scattering (SANS). The composition of the composite hydrogel was varied by (a) increasing the cross-linker and acrylamide concentration leading to strong hydrogel matrixes and (b) by increasing the microgel concentration to obtain composite gels with an internal structure. Additionally we synthesized composite hydrogels by using γ-irradiation as initiation for the polymerisation. This leads to the formation of chemical bonds between the PNiPAM microgels and the surrounding polyacrylamide matrix. Thus it is possible to synthesize hydrogels without an additional cross-linker, as well as pure particle networks. Some samples were prepared at two different temperatures, below and above the volume phase transition temperature of PNiPAM, resulting in highly swollen or totally collapsed microgels during the incorporation step. The volume phase transition of microgels is not influenced by a hydrogel matrix with high acrylamide concentration independent of the preparation temperature. However, an increased cross-linker concentration leads to a corset like constraint on microgel swelling. Microgels, which are embedded in the collapsed state (at 50 °C), are not able to swell upon cooling, whereas microgels embedded in the swollen state can collapse upon heating. For samples with an increased microgel concentration, the close microgel packing was disturbed by the formation of the polyacrylamide matrix. The hydrogel matrix squeezes the microgels together and leads to partial aggregation. The experiments demonstrate how composite hydrogels with stimuli-sensitive heterogeneities can be prepared such that the full responsiveness of the embedded microgels is retained while the macroscopic dimensions of the gel are not affected

  8. Robust Multiscale Modelling Of Two-Phase Steels On Heterogeneous Hardware Infrastructures By Using Statistically Similar Representative Volume Element

    Directory of Open Access Journals (Sweden)

    Rauch Ł.

    2015-09-01

    Full Text Available The coupled finite element multiscale simulations (FE2 require costly numerical procedures in both macro and micro scales. Attempts to improve numerical efficiency are focused mainly on two areas of development, i.e. parallelization/distribution of numerical procedures and simplification of virtual material representation. One of the representatives of both mentioned areas is the idea of Statistically Similar Representative Volume Element (SSRVE. It aims at the reduction of the number of finite elements in micro scale as well as at parallelization of the calculations in micro scale which can be performed without barriers. The simplification of computational domain is realized by transformation of sophisticated images of material microstructure into artificially created simple objects being characterized by similar features as their original equivalents. In existing solutions for two-phase steels SSRVE is created on the basis of the analysis of shape coefficients of hard phase in real microstructure and searching for a representative simple structure with similar shape coefficients. Optimization techniques were used to solve this task. In the present paper local strains and stresses are added to the cost function in optimization. Various forms of the objective function composed of different elements were investigated and used in the optimization procedure for the creation of the final SSRVE. The results are compared as far as the efficiency of the procedure and uniqueness of the solution are considered. The best objective function composed of shape coefficients, as well as of strains and stresses, was proposed. Examples of SSRVEs determined for the investigated two-phase steel using that objective function are demonstrated in the paper. Each step of SSRVE creation is investigated from computational efficiency point of view. The proposition of implementation of the whole computational procedure on modern High Performance Computing (HPC

  9. Deep sequencing of subseafloor eukaryotic rRNA reveals active Fungi across marine subsurface provinces.

    Directory of Open Access Journals (Sweden)

    William Orsi

    Full Text Available The deep marine subsurface is a vast habitat for microbial life where cells may live on geologic timescales. Because DNA in sediments may be preserved on long timescales, ribosomal RNA (rRNA is suggested to be a proxy for the active fraction of a microbial community in the subsurface. During an investigation of eukaryotic 18S rRNA by amplicon pyrosequencing, unique profiles of Fungi were found across a range of marine subsurface provinces including ridge flanks, continental margins, and abyssal plains. Subseafloor fungal populations exhibit statistically significant correlations with total organic carbon (TOC, nitrate, sulfide, and dissolved inorganic carbon (DIC. These correlations are supported by terminal restriction length polymorphism (TRFLP analyses of fungal rRNA. Geochemical correlations with fungal pyrosequencing and TRFLP data from this geographically broad sample set suggests environmental selection of active Fungi in the marine subsurface. Within the same dataset, ancient rRNA signatures were recovered from plants and diatoms in marine sediments ranging from 0.03 to 2.7 million years old, suggesting that rRNA from some eukaryotic taxa may be much more stable than previously considered in the marine subsurface.

  10. Deep Subseafloor Fungi as an Untapped Reservoir of Amphipathic Antimicrobial Compounds.

    Science.gov (United States)

    Navarri, Marion; Jégou, Camille; Meslet-Cladière, Laurence; Brillet, Benjamin; Barbier, Georges; Burgaud, Gaëtan; Fleury, Yannick

    2016-03-10

    The evolving global threat of antimicrobial resistance requires a deep renewal of the antibiotic arsenal including the isolation and characterization of new drugs. Underexplored marine ecosystems may represent an untapped reservoir of novel bioactive molecules. Deep-sea fungi isolated from a record-depth sediment core of almost 2000 m below the seafloor were investigated for antimicrobial activities. This antimicrobial screening, using 16 microbial targets, revealed 33% of filamentous fungi synthesizing bioactive compounds with activities against pathogenic bacteria and fungi. Interestingly, occurrence of antimicrobial producing isolates was well correlated with the complexity of the habitat (in term of microbial richness), as higher antimicrobial activities were obtained at specific layers of the sediment core. It clearly highlights complex deep-sea habitats as chemical battlefields where synthesis of numerous bioactive compounds appears critical for microbial competition. The six most promising deep subseafloor fungal isolates were selected for the production and extraction of bioactive compounds. Depending on the fungal isolates, antimicrobial compounds were only biosynthesized in semi-liquid or solid-state conditions as no antimicrobial activities were ever detected using liquid fermentation. An exception was made for one fungal isolate, and the extraction procedure designed to extract amphipathic compounds was successful and highlighted the amphiphilic profile of the bioactive metabolites.

  11. Metagenomic signatures of the Peru Margin subseafloor biosphere show a genetically distinct environment.

    Science.gov (United States)

    Biddle, Jennifer F; Fitz-Gibbon, Sorel; Schuster, Stephan C; Brenchley, Jean E; House, Christopher H

    2008-07-29

    The subseafloor marine biosphere may be one of the largest reservoirs of microbial biomass on Earth and has recently been the subject of debate in terms of the composition of its microbial inhabitants, particularly on sediments from the Peru Margin. A metagenomic analysis was made by using whole-genome amplification and pyrosequencing of sediments from Ocean Drilling Program Site 1229 on the Peru Margin to further explore the microbial diversity and overall community composition within this environment. A total of 61.9 Mb of genetic material was sequenced from sediments at horizons 1, 16, 32, and 50 m below the seafloor. These depths include sediments from both primarily sulfate-reducing methane-generating regions of the sediment column. Many genes of the annotated genes, including those encoding ribosomal proteins, corresponded to those from the Chloroflexi and Euryarchaeota. However, analysis of the 16S small-subunit ribosomal genes suggests that Crenarchaeota are the abundant microbial member. Quantitative PCR confirms that uncultivated Crenarchaeota are indeed a major microbial group in these subsurface samples. These findings show that the marine subsurface is a distinct microbial habitat and is different from environments studied by metagenomics, especially because of the predominance of uncultivated archaeal groups.

  12. Reactive transport model of growth and methane production by high-temperature methanogens in hydrothermal regions of the subseafloor

    Science.gov (United States)

    Stewart, L. C.; Algar, C. K.; Topçuoğlu, B. D.; Fortunato, C. S.; Larson, B. I.; Proskurowski, G. K.; Butterfield, D. A.; Vallino, J. J.; Huber, J. A.; Holden, J. F.

    2014-12-01

    Hydrogenotrophic methanogens are keystone high-temperature autotrophs in deep-sea hydrothermal vents and tracers of habitability and biogeochemical activity in the hydrothermally active subseafloor. At Axial Seamount, nearly all thermophilic methanogens are Methanothermococcus and Methanocaldococcus species, making this site amenable to modeling through pure culture laboratory experiments coupled with field studies. Based on field microcosm incubations with 1.2 mM, 20 μM, or no hydrogen, the growth of methanogens at 55°C and 80°C is limited primarily by temperature and hydrogen availability, with ammonium amendment showing no consistent effect on total methane output. The Arrhenius constants for methane production by Methanocaldococcus jannaschii (optimum 82°C) and Methanothermococcus thermolithotrophicus (optimum 65°C) were determined in pure culture bottle experiments. The Monod constants for hydrogen concentration were measured by growing both organisms in a 2-liter chemostat at two dilution rates; 55°C, 65°C and 82°C; and variable hydrogen concentrations. M. jannaschii showed higher ks and Vmax constants than M. thermolithotrophicus. In the field, hydrogen and methane concentrations in hydrothermal end-member and low-temperature diffuse fluids were measured, and the concentrations of methanogens that grow at 55°C and 80°C in diffuse fluids were determined using most-probable-number estimates. Methane concentration anomalies in diffuse fluids relative to end-member hydrothermal concentrations and methanogen cell concentrations are being used to constrain a 1-D reactive transport model using the laboratory-determined Arrhenius and Monod constants for methane production by these organisms. By varying flow path length and subseafloor cell concentrations in the model, our goal is to determine solutions for the potential depth of the subseafloor biosphere coupled with the amount of methanogenic biomass it contains.

  13. Draft genome sequence of Clostridium sulfidigenes 113A isolated from sub-seafloor sediments associated with methane hydrate deposits.

    Science.gov (United States)

    Honkalas, Varsha S; Dabir, Ashwini P; Arora, Preeti; Ranade, Dilip R; Dhakephalkar, Prashant K

    2015-08-01

    Clostridium sulfidigenes 113A is a strictly anaerobic, rod shaped, gram positive bacterium isolated from sub-seafloor sediments associated with methane hydrates. Here, we report the first draft genome of C. sulfidigenes strain 113A, which comprises 3,717,420 bp in 96 contigs with the G+C content of 30.1%. A total of 3148 protein coding sequences were predicted. The genome annotation revealed that 113A could play an important role in biogeochemical cycles and have potential biotechnological applications such as production of organic acids and butanol. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Subseafloor microbial communities in hydrogen-rich vent fluids from hydrothermal systems along the Mid-Cayman Rise.

    Science.gov (United States)

    Reveillaud, Julie; Reddington, Emily; McDermott, Jill; Algar, Christopher; Meyer, Julie L; Sylva, Sean; Seewald, Jeffrey; German, Christopher R; Huber, Julie A

    2016-06-01

    Warm fluids emanating from hydrothermal vents can be used as windows into the rocky subseafloor habitat and its resident microbial community. Two new vent systems on the Mid-Cayman Rise each exhibits novel geologic settings and distinctively hydrogen-rich vent fluid compositions. We have determined and compared the chemistry, potential energy yielding reactions, abundance, community composition, diversity, and function of microbes in venting fluids from both sites: Piccard, the world's deepest vent site, hosted in mafic rocks; and Von Damm, an adjacent, ultramafic-influenced system. Von Damm hosted a wider diversity of lineages and metabolisms in comparison to Piccard, consistent with thermodynamic models that predict more numerous energy sources at ultramafic systems. There was little overlap in the phylotypes found at each site, although similar and dominant hydrogen-utilizing genera were present at both. Despite the differences in community structure, depth, geology, and fluid chemistry, energetic modelling and metagenomic analysis indicate near functional equivalence between Von Damm and Piccard, likely driven by the high hydrogen concentrations and elevated temperatures at both sites. Results are compared with hydrothermal sites worldwide to provide a global perspective on the distinctiveness of these newly discovered sites and the interplay among rocks, fluid composition and life in the subseafloor. © 2015 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.

  15. Where The Wild Seafloor Scientists Are: Using Interactive Picture Books To Educate Children About Sub-seafloor Science

    Science.gov (United States)

    Kurtz, K.

    2015-12-01

    Sub-seafloor scientific research has the power to spark the imaginations of elementary age children with its mysterious nature, cutting-edge research, and its connections to kid friendly science topics, such as volcanoes, the extinction of dinosaurs and the search for extraterrestrial life. These factors have been utilized to create two interactive eBooks for elementary students and teachers, integrating high quality science information, highly engaging and age-appropriate illustrations, and rhyming text. One book introduces children to the research and discoveries of the JOIDES Resolution research vessel. The second focuses on the discoveries of microbial life in the sub-seafloor. The eBooks present information as traditional, linear, illustrated children's books, but the eBook format allows the book to be available online for free to anyone and allows teachers to project the book on a classroom screen so all students can easily see the illustrations. The iPad versions also provide an interactive, learner-led educational experience, where cognitively appropriate videos, photos and other forms of information can be accessed with the tap of a finger to answer reader questions and enrich their learning experience. These projects provide an example and model of the products that can result from high level and meaningful partnerships between scientists, educators, artists and writers.

  16. Sedimentological imprint on subseafloor microbial communities in Western Mediterranean Sea Quaternary sediments

    Directory of Open Access Journals (Sweden)

    M.-C. Ciobanu

    2012-09-01

    Full Text Available An interdisciplinary study was conducted to evaluate the relationship between geological and paleoenvironmental parameters and the bacterial and archaeal community structure of two contrasting subseafloor sites in the Western Mediterranean Sea (Ligurian Sea and Gulf of Lion. Both depositional environments in this area are well-documented from paleoclimatic and paleooceanographic point of views. Available data sets allowed us to calibrate the investigated cores with reference and dated cores previously collected in the same area, and notably correlated to Quaternary climate variations. DNA-based fingerprints showed that the archaeal diversity was composed by one group, Miscellaneous Crenarchaeotic Group (MCG, within the Gulf of Lion sediments and of nine different lineages (dominated by MCG, South African Gold Mine Euryarchaeotal Group (SAGMEG and Halobacteria within the Ligurian Sea sediments. Bacterial molecular diversity at both sites revealed mostly the presence of the classes Alphaproteobacteria, Betaproteobacteria and Gammaproteobacteria within Proteobacteria phylum, and also members of Bacteroidetes phylum. The second most abundant lineages were Actinobacteria and Firmicutes at the Gulf of Lion site and Chloroflexi at the Ligurian Sea site. Various substrates and cultivation conditions allowed us to isolate 75 strains belonging to four lineages: Alpha-, Gammaproteobacteria, Firmicutes and Actinobacteria. In molecular surveys, the Betaproteobacteria group was consistently detected in the Ligurian Sea sediments, characterized by a heterolithic facies with numerous turbidites from a deep-sea levee. Analysis of relative betaproteobacterial abundances and turbidite frequency suggested that the microbial diversity was a result of main climatic changes occurring during the last 20 ka. Statistical direct multivariate canonical correspondence

  17. Buried deep: How data about subseafloor life becomes dark and why

    Science.gov (United States)

    Darch, P. T.; Cummings, R.

    2013-12-01

    Earth scientists increasingly work in distributed, multidisciplinary projects. To promote the sharing of data across such a project, it is vital to improve long-term preservation of data in formats accessible to scientists in multiple disciplines with diverse needs, tools and scientific practices. When developing data management plans and infrastructure, it is important to ask: - What data are generated? - Where are these data preserved and shared? - What are the processes by which these data become 'dark'? - What are the infrastructural and social factors that shape these processes? In response to these questions, we present findings from the first year of a case study of the Center for Dark Energy Biosphere Investigations (C-DEBI), an NSF Science and Technology Center studying microbial life in the deep subseafloor biosphere. Our case study is funded by the Sloan Foundation and the NSF. It involves observation in laboratories, interviews, attendance of scientific meetings, and document analysis. At the laboratory level, we observed scientists mainly working on individual projects, or in a team of two or three. There is infrequent sharing of laboratory-generated data across C-DEBI. Where it does happen, it often takes place following discovery of the data through informal networks or serendipitous encounters with the data's creator. Instead, most of the laboratory-generated data become dark data. These data are typically preserved on a scientist's personal computer in ways particular to the individual, frequently not in a form meaningful to others. Other scientists are often not even aware that these data exist. Furthermore, the scientist tends to take care to preserve these data only as long as they require them: data loss can occur over time. Some data - those which support findings in a paper - may be deposited in a disciplinary database. However, these data are the end result of extensive processing: earlier versions of datasets can be lost. Also, in some

  18. Isotopes in heterogeneous catalysis

    CERN Document Server

    Hargreaves, Justin SJ

    2006-01-01

    The purpose of this book is to review the current, state-of-the-art application of isotopic methods to the field of heterogeneous catalysis. Isotopic studies are arguably the ultimate technique in in situ methods for heterogeneous catalysis. In this review volume, chapters have been contributed by experts in the field and the coverage includes both the application of specific isotopes - Deuterium, Tritium, Carbon-14, Sulfur-35 and Oxygen-18 - as well as isotopic techniques - determination of surface mobility, steady state transient isotope kinetic analysis, and positron emission profiling.

  19. Molecular Mechanism of Heterogeneous Catalysis

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 13; Issue 6. Molecular Mechanism of Heterogeneous Catalysis - The 2007 Nobel Prize in Chemistry. R S Swathi K L Sebastian. General Article Volume 13 Issue 6 June 2008 pp 548-560 ...

  20. Applications of tissue heterogeneity corrections and biologically effective dose volume histograms in assessing the doses for accelerated partial breast irradiation using an electronic brachytherapy source

    Energy Technology Data Exchange (ETDEWEB)

    Shi Chengyu; Guo Bingqi; Eng, Tony; Papanikolaou, Nikos [Cancer Therapy and Research Center, University of Texas Health Science Center at San Antonio, TX 78229 (United States); Cheng, Chih-Yao, E-mail: shic@uthscsa.ed [Radiation Oncology Department, Oklahoma University Health Science Center, Oklahoma, OK 73104 (United States)

    2010-09-21

    A low-energy electronic brachytherapy source (EBS), the model S700 Axxent(TM) x-ray device developed by Xoft Inc., has been used in high dose rate (HDR) intracavitary accelerated partial breast irradiation (APBI) as an alternative to an Ir-192 source. The prescription dose and delivery schema of the electronic brachytherapy APBI plan are the same as the Ir-192 plan. However, due to its lower mean energy than the Ir-192 source, an EBS plan has dosimetric and biological features different from an Ir-192 source plan. Current brachytherapy treatment planning methods may have large errors in treatment outcome prediction for an EBS plan. Two main factors contribute to the errors: the dosimetric influence of tissue heterogeneities and the enhancement of relative biological effectiveness (RBE) of electronic brachytherapy. This study quantified the effects of these two factors and revisited the plan quality of electronic brachytherapy APBI. The influence of tissue heterogeneities is studied by a Monte Carlo method and heterogeneous 'virtual patient' phantoms created from CT images and structure contours; the effect of RBE enhancement in the treatment outcome was estimated by biologically effective dose (BED) distribution. Ten electronic brachytherapy APBI cases were studied. The results showed that, for electronic brachytherapy cases, tissue heterogeneities and patient boundary effect decreased dose to the target and skin but increased dose to the bones. On average, the target dose coverage PTV V{sub 100} reduced from 95.0% in water phantoms (planned) to only 66.7% in virtual patient phantoms (actual). The actual maximum dose to the ribs is 3.3 times higher than the planned dose; the actual mean dose to the ipsilateral breast and maximum dose to the skin were reduced by 22% and 17%, respectively. Combining the effect of tissue heterogeneities and RBE enhancement, BED coverage of the target was 89.9% in virtual patient phantoms with RBE enhancement (actual BED) as

  1. Applications of tissue heterogeneity corrections and biologically effective dose volume histograms in assessing the doses for accelerated partial breast irradiation using an electronic brachytherapy source

    Science.gov (United States)

    Shi, Chengyu; Guo, Bingqi; Cheng, Chih-Yao; Eng, Tony; Papanikolaou, Nikos

    2010-09-01

    A low-energy electronic brachytherapy source (EBS), the model S700 Axxent™ x-ray device developed by Xoft Inc., has been used in high dose rate (HDR) intracavitary accelerated partial breast irradiation (APBI) as an alternative to an Ir-192 source. The prescription dose and delivery schema of the electronic brachytherapy APBI plan are the same as the Ir-192 plan. However, due to its lower mean energy than the Ir-192 source, an EBS plan has dosimetric and biological features different from an Ir-192 source plan. Current brachytherapy treatment planning methods may have large errors in treatment outcome prediction for an EBS plan. Two main factors contribute to the errors: the dosimetric influence of tissue heterogeneities and the enhancement of relative biological effectiveness (RBE) of electronic brachytherapy. This study quantified the effects of these two factors and revisited the plan quality of electronic brachytherapy APBI. The influence of tissue heterogeneities is studied by a Monte Carlo method and heterogeneous 'virtual patient' phantoms created from CT images and structure contours; the effect of RBE enhancement in the treatment outcome was estimated by biologically effective dose (BED) distribution. Ten electronic brachytherapy APBI cases were studied. The results showed that, for electronic brachytherapy cases, tissue heterogeneities and patient boundary effect decreased dose to the target and skin but increased dose to the bones. On average, the target dose coverage PTV V100 reduced from 95.0% in water phantoms (planned) to only 66.7% in virtual patient phantoms (actual). The actual maximum dose to the ribs is 3.3 times higher than the planned dose; the actual mean dose to the ipsilateral breast and maximum dose to the skin were reduced by 22% and 17%, respectively. Combining the effect of tissue heterogeneities and RBE enhancement, BED coverage of the target was 89.9% in virtual patient phantoms with RBE enhancement (actual BED) as compared to 95

  2. Characterization of metabolically active bacterial populations in subseafloor Nankai Trough sediments above, within and below the sulfate-methane transition zone

    Directory of Open Access Journals (Sweden)

    Heath J. Mills

    2012-04-01

    Full Text Available A remarkable number of microbial cells have been enumerated within subseafloor sediments, suggesting a biological impact on geochemical processes in the subseafloor habitat. However, the metabolically active fraction of these populations is largely uncharacterized. In this study, an RNA-based molecular approach was used to determine the diversity and community structure of metabolically active bacterial populations in the upper sedimentary formation of the Nankai Trough seismogenic zone. Samples used in this study were collected from the slope apron sediment overlying the accretionary prism at Site C0004 during the Integrated Ocean Drilling Program (IODP Expedition 316. The sediments represented microbial habitats above, within, and below the sulfate-methane transition zone (SMTZ, which was observed approximately 20 meters below the seafloor (mbsf. Small subunit ribosomal RNA (SSU rRNA were extracted, quantified, amplified and sequenced using high-throughput 454-pyrosequencing, indicating the occurrence of metabolically active bacterial populations to a depth of 57 mbsf. Transcript abundance and bacterial diversity decreased with increasing depth. The two communities below the SMTZ were similar at the phylum level, however only a 24% overlap was observed at the genus level. Active bacterial community composition was not confined to geochemically predicted redox stratification despite the deepest sample being more than 50 meters below the oxic/anoxic interface. Genus-level classification suggested that the metabolically active subseafloor bacterial populations had similarities to previously cultured organisms. This allowed predictions of physiological potential, expanding understanding of the subseafloor microbial ecosystem. Unique community structures suggest very diverse active populations compared to previous DNA-based diversity estimates, providing more support for enhancing community characterizations using more advanced sequencing

  3. Heterogeneous Catalysis.

    Science.gov (United States)

    Miranda, R.

    1989-01-01

    Described is a heterogeneous catalysis course which has elements of materials processing embedded in the classical format of catalytic mechanisms and surface chemistry. A course outline and list of examples of recent review papers written by students are provided. (MVL)

  4. Information and Heterogeneous Beliefs

    DEFF Research Database (Denmark)

    Christensen, Peter Ove; Qin, Zhenjiang

    2014-01-01

    In an incomplete market with heterogeneous prior beliefs, we show public information can have a substantial impact on the ex ante cost of capital, trading volume, and investor welfare. The Pareto effcient public information system is the system enjoying the maximum ex ante cost of capital...... ante risk premium is unaffected by the informativeness of the public information system. Similar results are obtained in a production economy, but the impact on the ex ante cost of capital is dampened compared to the exchange economy due to welfare improving reductions in real investments to smooth...... and the maximum expected abnormal trading volume. Imperfect public information increases the gains-to-trade based on heterogeneously updated posterior beliefs. In an exchange economy, this leads to higher growth in the investors' certainty equivalents and, thus, a higher equilibrium interest rate, whereas the ex...

  5. Computation of order and volume fill rates for a base stock inventory control system with heterogeneous demand to investigate which customer class gets the best service

    DEFF Research Database (Denmark)

    Larsen, Christian

    We consider a base stock inventory control system serving two customer classes whose demands are generated by two independent compound renewal processes. We show how to derive order and volume fill rates of each class. Based on assumptions about first order stochastic dominance we prove when one...

  6. Resolving Heterogeneity

    DEFF Research Database (Denmark)

    Hölzenspies, Jurriaan; Dela Cruz, Gelo Victoriano; M Brickman, Joshua

    2016-01-01

    sets of pluripotency and differentiation markers. It has become increasingly apparent that this transcriptional heterogeneity is an important characteristic of ESC culture. By sorting for specific populations of ESCs it is possible to enrich for cells with a capacity to colonize the embryo proper...

  7. Heterogeneous Gossip

    Science.gov (United States)

    Frey, Davide; Guerraoui, Rachid; Kermarrec, Anne-Marie; Koldehofe, Boris; Mogensen, Martin; Monod, Maxime; Quéma, Vivien

    Gossip-based information dissemination protocols are considered easy to deploy, scalable and resilient to network dynamics. Load-balancing is inherent in these protocols as the dissemination work is evenly spread among all nodes. Yet, large-scale distributed systems are usually heterogeneous with respect to network capabilities such as bandwidth. In practice, a blind load-balancing strategy might significantly hamper the performance of the gossip dissemination.

  8. Comparative study of subseafloor microbial community structures in deeply buried coral fossils and sediment matrices from the Challenger Mound in the Porcupine Seabight

    Directory of Open Access Journals (Sweden)

    Tatsuhiko eHoshino

    2011-11-01

    Full Text Available Subseafloor sedimentary environments harbor remarkably diverse microbial communities. However, it remains unknown if the deeply buried fossils in these sediments play ecological roles in deep microbial habitats, or whether the microbial communities inhabiting such fossils differ from those in the surrounding sediment matrix. Here we compare the community structures of subseafloor microbes in coldwater coral carbonates (Madrepora oculata and Lophelia pertusa and the clay matrix. Samples were obtained from the Challenger Mound in the Porcupine Seabight at Site U1317 Hole A during the Integrated Ocean Drilling Program Expedition 307. DNA was extracted from coral fossils and the surrounding sedimentary matrix at 4, 20 and 105 meters below the seafloor. 16S rRNA genes of Bacteria and Archaea were amplified by PCR, and a total of 213,792 16S rRNA gene-tagged sequences were analyzed. At the phylum level, dominant microbial components in both habitats consisted of Proteobacteria, Firmicutes, Nitrospirae, Chloroflexi and Miscellaneous Crenarchaeota Group (MCG at all three of the depths examined. However, at the genus and/or species level (similarity threshold 97.0%, the community compositions were found to be very different, with 69-75% and 46-57% of bacterial and archaeal phylotypes not overlapping in coral fossils and the clay matrix, respectively. Species richness analysis revealed that bacterial communities were generally more diverse than archaea, and that the diversity scores of coral fossils were lower than those in sediment matrix. However, the evenness of microbial communities was not significantly different in all the samples examined. No eukaryotic DNA sequences, such as 18S rRNA genes, were obtained from the corals. The findings suggested that, even at the same or similar depths, the sedimentological characteristics of a habitat are important factors affecting microbial diversity and community structure in deep subseafloor sedimentary

  9. Draft genome sequence of Methanoculleus sp. MH98A, a novel methanogen isolated from sub-seafloor methane hydrate deposits in Krishna Godavari basin.

    Science.gov (United States)

    Dabir, Ashwini; Honkalas, Varsha; Arora, Preeti; Pore, Soham; Ranade, D R; Dhakephalkar, Prashant K

    2014-10-22

    Members of the genus Methanoculleus are among the most prevalent methanogens in biomethanation processes especially in marine and brackish environments. A methanogen, identified as a novel species of the genus Methanoculleus, was isolated from deep sub-seafloor sediment obtained from the Krishna Godavari Basin off the eastern coast of India. This methanogen is thought to be the supplier of the methane in the submarine methane hydrate deposits. Further study of this microorganism could possibly help to revolutionize the energy industry. The draft genome of Methanoculleus sp. MH98A is presented. Copyright © 2014. Published by Elsevier B.V.

  10. Phylogenetic diversity of microorganisms in subseafloor crustal fluids from boreholes 1025C and 1026B along the Juan de Fuca Ridge flank

    Directory of Open Access Journals (Sweden)

    Sean eJungbluth

    2014-03-01

    Full Text Available To expand investigations into the phylogenetic diversity of microorganisms inhabiting the subseafloor biosphere, basalt-hosted crustal fluids were sampled from Circulation Obviation Retrofit Kits affixed to Holes 1025C and 1026B along the Juan de Fuca Ridge flank using a clean fluid pumping system. These boreholes penetrate the crustal aquifer of young ocean crust (1.24 and 3.51 million years old, respectively, but differ with respect to borehole depth and temperature at the sediment-basement interface (147 meters and 39 ºC vs. 295 meters and 64 ºC, respectively. Cloning and sequencing of PCR-amplified small subunit ribosomal RNA genes revealed that fluids retrieved from Hole 1025C were dominated by relatives of the genus Desulfobulbus of the Deltaproteobacteria (56% of clones and Candidatus Desulforudis of the Firmicutes (17%. Fluids sampled from Hole 1026B also contained plausible deep subseafloor inhabitants amongst the most abundant clone lineages; however, both geochemical analysis and microbial community structure reveal the borehole to be compromised by bottom seawater intrusion. Regardless, this study provides independent support for previous observations seeking to identify phylogenetic groups of microorganisms common to the deep ocean crustal biosphere, and extends previous observations by identifying additional lineages that may be prevalent in this unique environment.

  11. Spatial distribution, diversity and composition of bacterial communities in sub-seafloor fluids at a deep-sea hydrothermal field of the Suiyo Seamount

    Science.gov (United States)

    Kato, Shingo; Hara, Kurt; Kasai, Hiroko; Teramura, Takashi; Sunamura, Michinari; Ishibashi, Jun-ichiro; Kakegawa, Takeshi; Yamanaka, Toshiro; Kimura, Hiroyuki; Marumo, Katsumi; Urabe, Tetsuro; Yamagishi, Akihiko

    2009-10-01

    Spatial distribution, diversity, and composition of bacterial communities within the shallow sub-seafloor at the deep-sea hydrothermal field of the Suiyo Seamount, Izu-Bonin Arc, Western Pacific Ocean, were investigated. Fluids were sampled from four boreholes in this area. Each borehole was located near or away from active vents, the distance ranging 2-40 m from active vents. In addition, fluids discharging from a natural vent and ambient seawater were sampled in this area. We extracted DNA from each sample, amplified bacterial 16S rRNA genes by PCR, cloned the PCR products and sequenced. The total number of clones analyzed was 348. Most of the detected phylotypes were affiliated with the phylum Proteobacteria, of which the detection frequency in each clone library ranged from 84.6% to 100%. The bacterial community diversity and composition were different between hydrothermal fluids and seawater, between fluids from the boreholes and the vent, and even among fluids from each borehole. The relative abundances of the phylotypes related to Thiomicrospira, Methylobacterium and Sphingomonas were significantly different among fluids from each borehole. The phylotypes related to Thiomicrospira and Alcanivorax were detected in all of the boreholes and vent samples. Our findings provide insights into bacterial communities in the shallow sub-seafloor environments at active deep-sea hydrothermal vent fields.

  12. Micro- to nano-scale mapping and characterization of low-temperature metamorphism in Archean subseafloor metabasalts with implications for early life

    Science.gov (United States)

    Grosch, Eugene; McLoughlin, Nicola

    2015-04-01

    In modern oceanic environments, the low-temperature alteration of subseafloor basaltic glass provides potential chemical energy argued to sustain deep microbial ecosystems. By analogy, it has been argued that early Archean subseafloor pillow lava sequences may provide an environment in which to seek evidence for the earliest traces of microbial life on Earth, and possibly on Mars. Microtextures in metavolcanic pillow lavas from the ca. 3.55 - 3.10 billion-year-old Barberton greenstone belt of South Africa have been argued to represent the remains of microbes that tunneled into Archean subseafloor volcanic glass [1]. The filamentous titanite microtextures occurring in a quartz-chlorite-epidote matrix have been argued to represent Earth's oldest trace fossil. However, distinguishing abiotic hydrothermal processes from candidate geochemical and micro-textural biosignatures preserved in early Archean rocks has proven to be a major scientific challenge. Also, very few PT-constraints on ocean-floor metamorphism are available in this greenstone belt. This quest for the earliest traces of life relies upon the ongoing development of in-situ analytical techniques in terms of instrument sensitivity and spatial resolution. Here we employ a wide-range of novel petrological tools and metamorphic thermodynamic modelling techniques to test the biogenicity of microtextures, provide the first constraints on metamorphic conditions on the host metabasalts, and contribute to the search for robust traces of life in the early Archean. This includes in-situ mapping of the microtextures by laser Raman confocal spectroscopy, high-spatial-resolution elemental (C, N, P) mapping and in-situ isotopic measurements by NanoSIMS (nanoscale secondary ion microprobe) to evaluate the candidate biosignatures [2]. We have also developed and applied a new quantitative microscale mapping technique combined with thermodynamic modelling to map out metamorphic conditions surrounding the candidate

  13. Seafloor and sub-seafloor landslide evidences. GIS data model focused on geohazards

    Science.gov (United States)

    Leon, Ricardo; Gimenez, Julia; Medialdea, Teresa; Somoza, Luis; Gonzalez, Francisco Javier

    2016-04-01

    The wealth of landslide-information preserved over seafloor and inside stratigraphic horizons should be appropriately structured and modeled so that its storage in GIS format can be directly applied in the geohazard analysis. The main aim of risk analysis is to answer the "where, when and how" questions. In this sense, parameters related to: (i) geographical location, (ii) shape and magnitude of the event, (iii) age of event/s - period of recurrence; shall be carefully analyzed to be stored in an interoperable and accessible GIS structure that can be directly applied in the risk analysis. It is important that the above parameters will be stored separately of the trigger information (sedimentation rate, earthquakes, faults locations, seabed geology, etc...) but with a strong related link. The appropriate geographical representation of the landslide event inherits problems of the geomorphological maps and the standardized submarine geomorphological legend. This gives rise to considerations on how to represent-and store a landslide-event. We present a GIS submarine landslides catalogue of the Spanish continental margin and adjacent areas. It comprises the Atlantic and Mediterranean continental margins as well as hot-spot type volcanic islands and seamounts (Canary Archipelago). The catalogue, implemented in a geographic information system, stores a total of 317 submarine landslides and compiles information such as name, location, typology, age, volume, source, and lithology and published references. It is conceived as a first step in the submarine risk analysis, although other applications such as sedimentology, tectonic or volcanic studies or basin evolution are also taken into account.

  14. Risk taking under heterogenous risk sharing

    OpenAIRE

    Belhaj, Mohamed; Deroïan, Frédéric

    2009-01-01

    We revisit the common view that risk sharing enhances risk taking in the context of heterogenous risk sharing in a small economy. Under low volumes of transfers, we express individual risk level in terms of Bonacich measure. We find that heterogeneity combined to strategic interaction imply that risk sharing enhances risk taking only in average. However, under high transfer volumes, risk sharing may reduce risk taking. We also provide conditions under which agents under or over invest with re...

  15. Numerical Characterization of Concrete Heterogeneity

    Directory of Open Access Journals (Sweden)

    Roque Luiz Pitangueira

    2002-09-01

    Full Text Available In this paper, a finite element model including both material heterogeneity and size effects is presented. The concrete is considered as a statistical combination of constituent phase with different properties (aggregate, mortar and interface material. The material point response is based on a combination of the random occurrence of the solid phases in the structural volume as well as on the differences of structural response due to the size effect. Such combination allows for higher or lower heterogeneity corresponding to smaller or larger structural size. Simulations of the material heterogeneity and associated size effect in a computationally efficient and simple manner show good qualitative agreement with available experimental results for the three-point bending and Brazilian split tests.

  16. Numerical Characterization of Concrete Heterogeneity

    OpenAIRE

    Pitangueira, Roque Luiz; Silva, Raul Rosas e

    2002-01-01

    In this paper, a finite element model including both material heterogeneity and size effects is presented. The concrete is considered as a statistical combination of constituent phase with different properties (aggregate, mortar and interface material). The material point response is based on a combination of the random occurrence of the solid phases in the structural volume as well as on the differences of structural response due to the size effect. Such combination allows for higher or lowe...

  17. Microbial community stratification controlled by the subseafloor fluid flow and geothermal gradient at the Iheya North hydrothermal field in the Mid-Okinawa Trough (Integrated Ocean Drilling Program Expedition 331).

    Science.gov (United States)

    Yanagawa, Katsunori; Breuker, Anja; Schippers, Axel; Nishizawa, Manabu; Ijiri, Akira; Hirai, Miho; Takaki, Yoshihiro; Sunamura, Michinari; Urabe, Tetsuro; Nunoura, Takuro; Takai, Ken

    2014-10-01

    The impacts of lithologic structure and geothermal gradient on subseafloor microbial communities were investigated at a marginal site of the Iheya North hydrothermal field in the Mid-Okinawa Trough. Subsurface marine sediments composed of hemipelagic muds and volcaniclastic deposits were recovered through a depth of 151 m below the seafloor at site C0017 during Integrated Ocean Drilling Program Expedition 331. Microbial communities inferred from 16S rRNA gene clone sequencing in low-temperature hemipelagic sediments were mainly composed of members of the Chloroflexi and deep-sea archaeal group. In contrast, 16S rRNA gene sequences of marine group I Thaumarchaeota dominated the microbial phylotype communities in the coarse-grained pumiceous gravels interbedded between the hemipelagic sediments. Based on the physical properties of sediments such as temperature and permeability, the porewater chemistry, and the microbial phylotype compositions, the shift in the physical properties of the sediments is suggested to induce a potential subseafloor recharging flow of oxygenated seawater in the permeable zone, leading to the generation of variable chemical environments and microbial communities in the subseafloor habitats. In addition, the deepest section of sediments under high-temperature conditions (∼90°C) harbored the sequences of an uncultivated archaeal lineage of hot water crenarchaeotic group IV that may be associated with the high-temperature hydrothermal fluid flow. These results indicate that the subseafloor microbial community compositions and functions at the marginal site of the hydrothermal field are highly affected by the complex fluid flow structure, such as recharging seawater and underlying hydrothermal fluids, coupled with the lithologic transition of sediments. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  18. [Review on landscape heterogeneity].

    Science.gov (United States)

    Zhao, Yutao; Yu, Xinxiao; Guang, Wenbin

    2002-04-01

    On the base of precedent studies, the occurring mechanism, classification, measurement methods, and the important role of landscape heterogeneity in landscape ecology were reviewed. The inner and outer uncertain factors result in landscape heterogeneity. Landscape heterogeneity has close relations with landscape stability, landscape design, architecture, management and disturbance, scale and ecological diversity in ecology. Complexity of landscape heterogeneity research, non-system of measurement indices and methods, difficulties and limitations of landscape heterogeneity modelling were all discussed respectively. In addition, it is suggested that the theory and methods of ecological complexity should be used to improve landscape heterogeneity research.

  19. Flows and chemical reactions in heterogeneous mixtures

    CERN Document Server

    Prud'homme, Roger

    2014-01-01

    This book - a sequel of previous publications 'Flows and Chemical Reactions' and 'Chemical Reactions in Flows and Homogeneous Mixtures' - is devoted to flows with chemical reactions in heterogeneous environments.  Heterogeneous media in this volume include interfaces and lines. They may be the site of radiation. Each type of flow is the subject of a chapter in this volume. We consider first, in Chapter 1, the question of the generation of environments biphasic individuals: dusty gas, mist, bubble flow.  Chapter 2 is devoted to the study at the mesoscopic scale: particle-fluid exchange of mom

  20. Mineralizing Filamentous Bacteria from the Prony Bay Hydrothermal Field Give New Insights into the Functioning of Serpentinization-Based Subseafloor Ecosystems.

    Science.gov (United States)

    Pisapia, Céline; Gérard, Emmanuelle; Gérard, Martine; Lecourt, Léna; Lang, Susan Q; Pelletier, Bernard; Payri, Claude E; Monnin, Christophe; Guentas, Linda; Postec, Anne; Quéméneur, Marianne; Erauso, Gaël; Ménez, Bénédicte

    2017-01-01

    Despite their potential importance as analogs of primitive microbial metabolisms, the knowledge of the structure and functioning of the deep ecosystems associated with serpentinizing environments is hampered by the lack of accessibility to relevant systems. These hyperalkaline environments are depleted in dissolved inorganic carbon (DIC), making the carbon sources and assimilation pathways in the associated ecosystems highly enigmatic. The Prony Bay Hydrothermal Field (PHF) is an active serpentinization site where, similar to Lost City (Mid-Atlantic Ridge), high-pH fluids rich in H2 and CH4 are discharged from carbonate chimneys at the seafloor, but in a shallower lagoonal environment. This study aimed to characterize the subsurface microbial ecology of this environment by focusing on the earliest stages of chimney construction, dominated by the discharge of hydrothermal fluids of subseafloor origin. By jointly examining the mineralogy and the microbial diversity of the conduits of juvenile edifices at the micrometric scale, we find a central role of uncultivated bacteria belonging to the Firmicutes in the ecology of the PHF. These bacteria, along with members of the phyla Acetothermia and Omnitrophica, are identified as the first chimneys inhabitants before archaeal Methanosarcinales. They are involved in the construction and early consolidation of the carbonate structures via organomineralization processes. Their predominance in the most juvenile and nascent hydrothermal chimneys, and their affiliation with environmental subsurface microorganisms, indicate that they are likely discharged with hydrothermal fluids from the subseafloor. They may thus be representative of endolithic serpentinization-based ecosystems, in an environment where DIC is limited. In contrast, heterotrophic and fermentative microorganisms may consume organic compounds from the abiotic by-products of serpentinization processes and/or from life in the deeper subsurface. We thus propose that

  1. Genomic analysis of Luteimonas abyssi XH031(T): insights into its adaption to the subseafloor environment of South Pacific Gyre and ecological role in biogeochemical cycle.

    Science.gov (United States)

    Zhang, Li; Wang, Xiaolei; Yu, Min; Qiao, Yanlu; Zhang, Xiao-Hua

    2015-12-21

    Luteimonas abyssi XH031(T), which was previously isolated from subseafloor environment of the South Pacific Gyre (SPG), was an aerobic, gram-negative bacterium, and was identified to be a novel species of the genus Luteimonas in the family of Xanthomonadaceae. The nutrients utilization and metabolic mechanisms of XH031(T) indicate its plasticity. In view of the above characteristics, its genome was sequenced, and an in-depth analysis of the XH031(T) genome was performed to elucidate its adaption to extreme ecological environment. Various macromolecules including polysaccharide, protein, lipid and DNA could be degraded at low temperature by XH031(T) under laboratory conditions, and its degradation abilities to starch, gelatin and casein were considerably strong. Genome sequence analysis indicated that XH031(T) possesses extensive enzyme-encoding genes compared with four other Luteimonas strains. In addition, intricate systems (such as two-component regulatory systems, secretion systems, etc.), which are often used by bacteria to modulate the interactions of bacteria with their environments, were predicted in the genome of XH031(T). Genes encoding a choline-glycine betaine transporter and 99 extracellular peptidases featured with halophilicity were predicted in the genome, which might help the bacterium to adapt to the salty marine environment. Moreover, there were many gene clusters in the genome encoding ATP-binding cassette superfamily transporters, major facilitator superfamily transporters and cytochrome P450s that might function in the process of various substrate transportation and metabolisms. Furthermore, drug resistance genes harbored in the genome might signify that XH031(T) has evolved hereditary adaptation to toxic environment. Finally, the annotation of metabolic pathways of the elements (such as carbon, nitrogen, sulfur, phosphor and iron) in the genome elucidated the degradation of organic matter in the deep sediment of the SPG. The genome analysis

  2. Link-Heterogeneity vs. Node-Heterogeneity in Clusters

    OpenAIRE

    Beaumont, Olivier; Rosenberg, Arnold

    2010-01-01

    International audience; Heterogeneity in resources pervades all modern computing platforms. How do the effects of heterogeneity depend on which resources differ among computers in a platform? Some answers are derived within a formal framework, by comparing heterogeneity in computing power (node-heterogeneity) with heterogeneity in communication speed (link-heterogeneity). The former genre of heterogeneity seems much easier to understand than the latter.

  3. Transfers in heterogeneous environments; Transferts en milieux heterogenes

    Energy Technology Data Exchange (ETDEWEB)

    Flesselles, J.M. [Saint-Gobain Recherche, 93 - Aubervilliers (France); Gouesbet, G.; Mees, L.; Roze, C.; Girasole, Th.; Grehan, G. [Laboratoire d' Electromagnetisme et Systemes Particulaires (LESP), UMR CNRS 6614, CORIA. Universite de Rouen et INSA de Rouen, 76 - Saint-Etienne du Rouvray (France); Goyheneche, J.M.; Vignoles, G.; Coindreau, O. [Laboratoire des Composites Thermostructuraux (LCTS), UMR 5801, 33 - Pessac (France); Moyne, Ch. [LEMTA (UMR 7563) CNRS-INPL-UHP, 54 - Vandoeuvre les Nancy (France); Coussy, O. [Institut Navier - ENPC, 77 - Marne-la-Vallee (France); Lassabatere, Th. [Electricite de France Les Renardieres, Dept. Materiaux Mecanique des Composants, 77 - Moret sur Loing (France); Tadrist, L. [IUSTI - UMR 6595, 13 - Marseille (France)

    2004-07-01

    This document gathers the articles and transparencies of the invited talks given at the 2004 French congress of thermal engineering about transfers in heterogeneous environment. Content: transfer phenomena in industrial glass furnaces; simple and multiple scattering diagnosis by femto-second pulsed laser: application to particulate diagnoses; thermal modeling of thermo-structural composites; hybrid mixtures theory, average volumic measurement, periodical or stochastic homogenization: advance in scale change processes; thermo-hydro-chemical-mechanical coupling in porous medium: application to young concrete structures and to clay barriers of disposal facilities; transfers and flows in fluidization: recent advances and future challenges. (J.S.)

  4. Heterogeneous network architectures

    DEFF Research Database (Denmark)

    Christiansen, Henrik Lehrmann

    2006-01-01

    Future networks will be heterogeneous! Due to the sheer size of networks (e.g., the Internet) upgrades cannot be instantaneous and thus heterogeneity appears. This means that instead of trying to find the olution, networks hould be designed as being heterogeneous. One of the key equirements here...

  5. Sci—Fri PM: Topics — 04: What if bystander effects influence cell kill within a target volume? Potential consequences of dose heterogeneity on TCP and EUD on intermediate risk prostate patients

    Energy Technology Data Exchange (ETDEWEB)

    Balderson, M.J.; Kirkby, C. [Department of Physics and Astronomy, University of Calgary, Calgary, Alberta (Canada); Department of Medical Physics, Tom Baker Cancer Centre, Calgary, Alberta (Canada); Department of Medical Physics, Jack Ady Cancer Centre, Lethbridge, Alberta (Canada)

    2014-08-15

    In vitro evidence has suggested that radiation induced bystander effects may enhance non-local cell killing which may influence radiotherapy treatment planning paradigms. This work applies a bystander effect model, which has been derived from published in vitro data, to calculate equivalent uniform dose (EUD) and tumour control probability (TCP) and compare them with predictions from standard linear quadratic (LQ) models that assume a response due only to local absorbed dose. Comparisons between the models were made under increasing dose heterogeneity scenarios. Dose throughout the CTV was modeled with normal distributions, where the degree of heterogeneity was then dictated by changing the standard deviation (SD). The broad assumptions applied in the bystander effect model are intended to place an upper limit on the extent of the results in a clinical context. The bystander model suggests a moderate degree of dose heterogeneity yields as good or better outcome compared to a uniform dose in terms of EUD and TCP. Intermediate risk prostate prescriptions of 78 Gy over 39 fractions had maximum EUD and TCP values at SD of around 5Gy. The plots only dropped below the uniform dose values for SD ∼ 10 Gy, almost 13% of the prescribed dose. The bystander model demonstrates the potential to deviate from the common local LQ model predictions as dose heterogeneity through a prostate CTV is varies. The results suggest the potential for allowing some degree of dose heterogeneity within a CTV, although further investigations of the assumptions of the bystander model are warranted.

  6. Heterogeneity and Microeconometrics Modelling

    DEFF Research Database (Denmark)

    Browning, Martin; Carro, Jesus

    Presented at the 2005 Econometric Society World Congress Plenary Session on "Modelling Heterogeneity". We survey the treatment of heterogeneity in applied microeconometrics analyses. There are three themes. First, there is usually much more heterogeneity than empirical researchers allow for. Second......, the inappropriate treatment of heterogeneity can lead to serious error when estimating outcomes of interest. Finally, once we move away from the traditional linear model with a single 'fixed effect', it is very difficult to account for heterogeneity and fit the data and maintain coherence with theory structures....... The latter task is one for economists: "heterogeneity is too important to be left to the statisticians". The paper concludes with a report of our own research on dynamic discrete choice models that allow for maximal heterogeneity...

  7. Activation volume in heterogeneous deformation of Mg{sub 65}Cu{sub 12.5}Ni{sub 12.5}(Ce{sub 75}La{sub 25}){sub 10} metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Thurieau, Nicolas; Perrière, Loïc; Laurent-Brocq, Mathilde [ICMPE, CNRS-UPEC, 2 rue Henri Dunant 94320 Thiais, Cedex (France); Champion, Yannick, E-mail: yannick.champion@simap.grenoble-inp.fr [Univ. Grenoble Alpes, SIMAP, F-38000 Grenoble (France); CNRS, SIMAP, F-38000 Grenoble (France)

    2015-11-28

    Depth variation at constant load in instrumented nano-indentation was used to measure activation volume controlling shear band formation in the Mg{sub 65}Cu{sub 12.5}Ni{sub 12.5}(Ce{sub 75}La{sub 25}){sub 10} metallic glass. A series of measurements revealed a large scattering of the data spanning from 100 Å{sup 3} to 800 Å{sup 3}. The distribution of values, which is not following a normal one, may be attributed to the atomic structure of metallic glasses with the absence of long range order, leading to different volume fraction of shear bands for independent experiments. Activation volume is analyzed considering the variation of shear band volume fraction leading to a unique value of a true activation volume. An interpretation for the distribution of values is proposed.

  8. Heterogeneity of myocardial fatty acid tracer uptake in the porcine heart wall

    Science.gov (United States)

    Ritman, Erik L.; Beighley, Patricia E.

    1997-05-01

    Spatial heterogeneity of myocardial perfusion has been recognized for many years. We have previously shown that whole-body CT is a method for providing the simultaneous measurements of heterogeneity of myocardial perfusion and myocardial blood volume. In the present study we found that the spatial distribution of myocardial metabolism, as indicated by the local accumulation of iodinated phenyl pentadecanoic acid, is slightly more heterogeneous than, but not statistically different from, the heterogeneity of perfusion and blood volume. These findings are consistent with the notion that a common factor is likely to play a major role in determining the spatial heterogeneity of myocardial intravascular blood volume, of myocardial perfusion and of myocardial metabolism.

  9. Application-specific mesh-based heterogeneous FPGA architectures

    CERN Document Server

    Parvez, Husain

    2011-01-01

    This volume presents a new exploration environment for mesh-based, heterogeneous FPGA architectures. Readers will find a description of state-of-the-art techniques for reducing area requirements, which both increase performance and enable power reduction.

  10. Numerical studies of geomagnetically induced electric field on seafloor and near coastal zones incorporated with heterogeneous conductivity distributions

    Science.gov (United States)

    Goto, Tada-nori

    2015-12-01

    Abrupt changes of geomagnetic field can make large induced electric field and resultant electric current on the earth, which is called as geomagnetically induced current (GIC). It can yield damages to pipelines, cables, and other architectures. For understanding the phenomena and future risks of GIC, it is necessary to evaluate how the sub-surface electrical conductivity structure is important for the GIC because the heterogeneous conductivity structure in the crust and mantle affects the induced electrical current locally. The hazard prediction based on the homogeneous earth may result in the underestimation. Here, I introduce possible cases of geomagnetically induced electric field (GIE) on seafloor and near coastal areas, based on numerical forward simulations on one-, two-, and three-dimensional (1-D, 2-D, and 3-D) earth's structure including the sea layer. On the 1-D case, I show the possible amplitude of GIE on the seafloor, far from the coastal area. The second case study comes from 2-D forward simulation, in which the straightly elongated coastal line is assumed, and various sub-surface and sub-seafloor conductivity structures are imposed. The numerical results suggest that the amplitude of GIE on land becomes more than two times larger than that of the homogeneous earth without the sea layer. The width of land zone with larger GIE is about 20 km from the coast. In forward modeling with a simplified 3-D bathymetry, land electric field near the bay area increases with about ten times larger than that of the inland one. The seafloor GIE near the peninsula area also indicates about four times larger value than that of the other area at the same water depth. These phenomena can be explained by the boundary charge along the coastal area. I conclude that 3-D earth's conductivity structure including the realistic bathymetry and sub-surface and sub-seafloor structures should be essential and focused for the hazard assessment of GIC.

  11. [Tumor genetic heterogeneity].

    Science.gov (United States)

    Yang, Yi-Ling; Chu, Jia-You; Wang, Ming-Rong

    2013-01-01

    Although the majority of spontaneous tumors derive from a single cell, people have come to realize intra-tumor heterogeneity of individual tumors. Human cancers frequently display substantial difference in phenotypic features, such as the degree of differentiation, cell proliferation rate, invasion and metastatic potential, response to therapy and many other aspects. Molecular biology studies have confirmed the occurrence of new mutations during the process of tumor progression, which provide more powerful evidences to show the existence of intra-tumor genetic heterogeneity. This re-view will focus on recent major advances in the study of tumor genetic heterogeneity. Considering that genetic heterogene-ity analysis can provide important information to indicate how long normal cells transform into tumor cells and how to spread and migrate, we firstly describe experimental evidences of intra-tumor genetic heterogeneity. Then we discuss the research value of genetic diversity in the evolutionary history of human individual tumor, introduce the two modes of the genetic heterogeneity - cancer stem cell model and the clonal evolution model, and summarize the implications of in-tra-tumor heterogeneity studies in metastasis and therapy. In addition, the article presents the research methods of genetic heterogeneity, including specific gene and genome-wide level, pointing out their strengths and limitations.

  12. Latest Permian carbonate carbon isotope variability traces heterogeneous organic carbon accumulation and authigenic carbonate formation

    Directory of Open Access Journals (Sweden)

    M. Schobben

    2017-11-01

    Full Text Available Bulk-carbonate carbon isotope ratios are a widely applied proxy for investigating the ancient biogeochemical carbon cycle. Temporal carbon isotope trends serve as a prime stratigraphic tool, with the inherent assumption that bulk micritic carbonate rock is a faithful geochemical recorder of the isotopic composition of seawater dissolved inorganic carbon. However, bulk-carbonate rock is also prone to incorporate diagenetic signals. The aim of the present study is to disentangle primary trends from diagenetic signals in carbon isotope records which traverse the Permian–Triassic boundary in the marine carbonate-bearing sequences of Iran and South China. By pooling newly produced and published carbon isotope data, we confirm that a global first-order trend towards depleted values exists. However, a large amount of scatter is superimposed on this geochemical record. In addition, we observe a temporal trend in the amplitude of this residual δ13C variability, which is reproducible for the two studied regions. We suggest that (sub-sea-floor microbial communities and their control on calcite nucleation and ambient porewater dissolved inorganic carbon δ13C pose a viable mechanism to induce bulk-rock δ13C variability. Numerical model calculations highlight that early diagenetic carbonate rock stabilization and linked carbon isotope alteration can be controlled by organic matter supply and subsequent microbial remineralization. A major biotic decline among Late Permian bottom-dwelling organisms facilitated a spatial increase in heterogeneous organic carbon accumulation. Combined with low marine sulfate, this resulted in varying degrees of carbon isotope overprinting. A simulated time series suggests that a 50 % increase in the spatial scatter of organic carbon relative to the average, in addition to an imposed increase in the likelihood of sampling cements formed by microbial calcite nucleation to 1 out of 10 samples, is sufficient to induce the

  13. Latest Permian carbonate carbon isotope variability traces heterogeneous organic carbon accumulation and authigenic carbonate formation

    Science.gov (United States)

    Schobben, Martin; van de Velde, Sebastiaan; Gliwa, Jana; Leda, Lucyna; Korn, Dieter; Struck, Ulrich; Vinzenz Ullmann, Clemens; Hairapetian, Vachik; Ghaderi, Abbas; Korte, Christoph; Newton, Robert J.; Poulton, Simon W.; Wignall, Paul B.

    2017-11-01

    Bulk-carbonate carbon isotope ratios are a widely applied proxy for investigating the ancient biogeochemical carbon cycle. Temporal carbon isotope trends serve as a prime stratigraphic tool, with the inherent assumption that bulk micritic carbonate rock is a faithful geochemical recorder of the isotopic composition of seawater dissolved inorganic carbon. However, bulk-carbonate rock is also prone to incorporate diagenetic signals. The aim of the present study is to disentangle primary trends from diagenetic signals in carbon isotope records which traverse the Permian-Triassic boundary in the marine carbonate-bearing sequences of Iran and South China. By pooling newly produced and published carbon isotope data, we confirm that a global first-order trend towards depleted values exists. However, a large amount of scatter is superimposed on this geochemical record. In addition, we observe a temporal trend in the amplitude of this residual δ13C variability, which is reproducible for the two studied regions. We suggest that (sub-)sea-floor microbial communities and their control on calcite nucleation and ambient porewater dissolved inorganic carbon δ13C pose a viable mechanism to induce bulk-rock δ13C variability. Numerical model calculations highlight that early diagenetic carbonate rock stabilization and linked carbon isotope alteration can be controlled by organic matter supply and subsequent microbial remineralization. A major biotic decline among Late Permian bottom-dwelling organisms facilitated a spatial increase in heterogeneous organic carbon accumulation. Combined with low marine sulfate, this resulted in varying degrees of carbon isotope overprinting. A simulated time series suggests that a 50 % increase in the spatial scatter of organic carbon relative to the average, in addition to an imposed increase in the likelihood of sampling cements formed by microbial calcite nucleation to 1 out of 10 samples, is sufficient to induce the observed signal of carbon

  14. Exploring tumor heterogeneity

    NARCIS (Netherlands)

    Fessler, E.

    2016-01-01

    Cancer is a heterogeneous disease, which is reflected both on the cellular and the population level. Advances in detection, diagnosis, and treatment of malignancies have increased survival time of cancer patients; yet, the heterogeneity observed within and between tumors complicates accurate

  15. Is dynamic heterogeneity of water in presence of a protein ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 128; Issue 12. Is dynamic heterogeneity of water in presence of a protein denaturing agent different from that in presence of a protein stabilizer? A molecular dynamics simulation study. SANDIPA INDRA RANJIT BISWAS BISWAS. Regular Article Volume 128 Issue 12 ...

  16. Extreme heterogeneity in Sr isotope systematic in the Himalayan ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 110; Issue 2. Extreme heterogeneity in Sr isotope systematic in the Himalayan leucogranites: A possible mechanism of partial melting based on thermal modeling. Dilip K Mukhopadhyay. Volume 110 Issue 2 June 2001 pp 161-169 ...

  17. Heterogeneous cellular networks

    CERN Document Server

    Hu, Rose Qingyang

    2013-01-01

    A timely publication providing coverage of radio resource management, mobility management and standardization in heterogeneous cellular networks The topic of heterogeneous cellular networks has gained momentum in industry and the research community, attracting the attention of standardization bodies such as 3GPP LTE and IEEE 802.16j, whose objectives are looking into increasing the capacity and coverage of the cellular networks. This book focuses on recent progresses,  covering the related topics including scenarios of heterogeneous network deployment, interference management i

  18. Improved Heterogeneous Distance Functions

    OpenAIRE

    Wilson, D. R.; Martinez, T. R.

    1996-01-01

    Instance-based learning techniques typically handle continuous and linear input values well, but often do not handle nominal input attributes appropriately. The Value Difference Metric (VDM) was designed to find reasonable distance values between nominal attribute values, but it largely ignores continuous attributes, requiring discretization to map continuous values into nominal values. This paper proposes three new heterogeneous distance functions, called the Heterogeneous Value Difference M...

  19. Barite in hydrothermal environments as a recorder of subseafloor processes: a multiple-isotope study from the Loki's Castle vent field.

    Science.gov (United States)

    Eickmann, B; Thorseth, I H; Peters, M; Strauss, H; Bröcker, M; Pedersen, R B

    2014-07-01

    Barite chimneys are known to form in hydrothermal systems where barium-enriched fluids generated by leaching of the oceanic basement are discharged and react with seawater sulfate. They also form at cold seeps along continental margins, where marine (or pelagic) barite in the sediments is remobilized because of subseafloor microbial sulfate reduction. We test the possibility of using multiple sulfur isotopes (δ34S, Δ33S, ∆36S) of barite to identify microbial sulfate reduction in a hydrothermal system. In addition to multiple sulfur isotopes, we present oxygen (δ18O) and strontium (87Sr/86Sr) isotopes for one of numerous barite chimneys in a low-temperature (~20 °C) venting area of the Loki's Castle black smoker field at the ultraslow-spreading Arctic Mid-Ocean Ridge (AMOR). The chemistry of the venting fluids in the barite field identifies a contribution of at least 10% of high-temperature black smoker fluid, which is corroborated by 87Sr/86 Sr ratios in the barite chimney that are less radiogenic than in seawater. In contrast, oxygen and multiple sulfur isotopes indicate that the fluid from which the barite precipitated contained residual sulfate that was affected by microbial sulfate reduction. A sulfate reduction zone at this site is further supported by the multiple sulfur isotopic composition of framboidal pyrite in the flow channel of the barite chimney and in the hydrothermal sediments in the barite field, as well as by low SO4 and elevated H2S concentrations in the venting fluids compared with conservative mixing values. We suggest that the mixing of ascending H2- and CH4-rich high-temperature fluids with percolating seawater fuels microbial sulfate reduction, which is subsequently recorded by barite formed at the seafloor in areas where the flow rate is sufficient. Thus, low-temperature precipitates in hydrothermal systems are promising sites to explore the interactions between the geosphere and biosphere in order to evaluate the microbial impact on

  20. The stable carbon isotope biogeochemistry of acetate and other dissolved carbon species in deep subseafloor sediments at the northern Cascadia Margin

    Science.gov (United States)

    Heuer, Verena B.; Pohlman, John W.; Torres, Marta E.; Elvert, Marcus; Hinrichs, Kai-Uwe

    2009-06-01

    Ocean drilling has revealed the existence of vast microbial populations in the deep subseafloor, but to date little is known about their metabolic activities. To better understand the biogeochemical processes in the deep biosphere, we investigate the stable carbon isotope chemistry of acetate and other carbon-bearing metabolites in sediment pore-waters. Acetate is a key metabolite in the cycling of carbon in anoxic sediments. Its stable carbon isotopic composition provides information on the metabolic processes dominating acetate turnover in situ. This study reports our findings for a methane-rich site at the northern Cascadia Margin (NE Pacific) where Expedition 311 of the Integrated Ocean Drilling Program (IODP) sampled the upper 190 m of sediment. At Site U1329, δ13C values of acetate span a wide range from -46.0‰ to -11.0‰ vs. VPDB and change systematically with sediment depth. In contrast, δ13C values of both the bulk dissolved organic carbon (DOC) (-21.6 ± 1.3‰ vs. VPDB) and the low-molecular-weight compound lactate (-20.9 ± 1.8‰ vs. VPDB) show little variability. These species are interpreted to represent the carbon isotopic composition of fermentation products. Relative to DOC, acetate is up to 23.1‰ depleted and up to 9.1‰ enriched in 13C. Broadly, 13C-depletions of acetate relative to DOC indicate flux of carbon from acetogenesis into the acetate pool while 13C-enrichments of pore-water acetate relative to DOC suggest consumption of acetate by acetoclastic methanogenesis. Isotopic relationships between acetate and lactate or DOC provide new information on the carbon flow and the presence and activity of specific functional microbial communities in distinct biogeochemical horizons of the sediment. In particular, they suggest that acetogenic CO 2-reduction can coexist with methanogenic CO 2-reduction, a notion contrary to the hypothesis that hydrogen levels are controlled by the thermodynamically most favorable electron-accepting process

  1. Bronchoscopic Lung Volume Reduction

    Directory of Open Access Journals (Sweden)

    Armin Ernst

    2011-01-01

    Full Text Available The application of lung volume reduction surgery in clinical practice is limited by high postoperative morbidity and stringent selection criteria. This has been the impetus for the development of bronchoscopic approaches to lung volume reduction. A range of different techniques such as endobronchial blockers, airway bypass, endobronchial valves, thermal vapor ablation, biological sealants, and airway implants have been employed on both homogeneous as well as heterogeneous emphysema. The currently available data on efficacy of bronchoscopic lung volume reduction are not conclusive and subjective benefit in dyspnoea scores is a more frequent finding than improvements on spirometry or exercise tolerance. Safety data are more promising with rare procedure-related mortality, few serious complications, and short hospital length of stay. The field of bronchoscopic lung volume reduction continues to evolve as ongoing prospective randomized trials build on earlier feasibility data to clarify the true efficacy of such techniques.

  2. Green heterogeneous wireless networks

    CERN Document Server

    Ismail, Muhammad; Nee, Hans-Peter; Qaraqe, Khalid A; Serpedin, Erchin

    2016-01-01

    This book focuses on the emerging research topic "green (energy efficient) wireless networks" which has drawn huge attention recently from both academia and industry. This topic is highly motivated due to important environmental, financial, and quality-of-experience (QoE) considerations. Specifically, the high energy consumption of the wireless networks manifests in approximately 2% of all CO2 emissions worldwide. This book presents the authors’ visions and solutions for deployment of energy efficient (green) heterogeneous wireless communication networks. The book consists of three major parts. The first part provides an introduction to the "green networks" concept, the second part targets the green multi-homing resource allocation problem, and the third chapter presents a novel deployment of device-to-device (D2D) communications and its successful integration in Heterogeneous Networks (HetNets). The book is novel in that it specifically targets green networking in a heterogeneous wireless medium, which re...

  3. Heterogeneity and option pricing

    NARCIS (Netherlands)

    Benninga, Simon; Mayshar, Joram

    2000-01-01

    An economy with agents having constant yet heterogeneous degrees of relative risk aversion prices assets as though there were a single decreasing relative risk aversion pricing representative agent. The pricing kernel has fat tails and option prices do not conform to the Black-Scholes formula.

  4. Why does heterogeneity matter?

    Science.gov (United States)

    K.B. Pierce

    2007-01-01

    This is a review of the book "Ecosystem function in heterogeneous landscapes" published in 2005. The authors are G. Lovett, C. Jones, M.G. Turner, and K.C. Weathers. It was published by Springer, New York. The book is a synthesis of the 10th Gary conference held at the Institute of Ecosystem Studies in Millbrook, New York, in 2003.

  5. Heterogeneous chromium catalysts

    NARCIS (Netherlands)

    2005-01-01

    The present invention relates to a heterogeneous chromium catalyst system for the polymerisation of ethylene and/or alpha olefins prepared by the steps of: (a) providing a silica-containing support, (b) treating the silica-containing support with a chromium compound to form a chromium-based

  6. Receiver Heterogeneity Helps

    DEFF Research Database (Denmark)

    Kovács, Erika R.; Pedersen, Morten Videbæk; Roetter, Daniel Enrique Lucani

    2014-01-01

    Heterogeneity amongst devices and desired service are commonly seen as a source of additional challenges for setting up an efficient multi-layer multicast service. In particular, devices requiring only the base layer can become a key bottleneck to the performance for other devices. This paper...

  7. Heterogeneity of Intellectual Assets

    DEFF Research Database (Denmark)

    Dahlgren, Johan Henrich; Lund Jensen, Rasmus; Valentin, Finn

    2004-01-01

    This paper deals with methodological issues of assessing the composition and level ofheterogeneity of firms' intellectual assets. It develops an original metric - referred to asthe H-index - for measuring heterogeneity using data extracted from patent documents.The main purpose is to improve...

  8. Quantifying hidden individual heterogeneity

    DEFF Research Database (Denmark)

    Steiner, Ulrich; Lenart, Adam; Vaupel, James W.

    Aging is assumed to be driven by the accumulation of damage or some other aging factor which shapes demographic patterns, including the classical late age mortality plateaus. However to date, heterogeneity in these damage stages is not observed. Here, we estimate underlying stage distributions...

  9. Heterogeneity of Dutch rainfall

    NARCIS (Netherlands)

    Witter, J.V.

    1984-01-01

    Rainfall data for the Netherlands have been used in this study to investigate aspects of heterogeneity of rainfall, in particular local differences in rainfall levels, time trends in rainfall, and local differences in rainfall trend. The possible effect of urbanization and industrialization on the

  10. Heterogeneous computing in economics

    DEFF Research Database (Denmark)

    Dziubinski, Matt P.; Grassi, Stefano

    2014-01-01

    This paper shows the potential of heterogeneous computing in solving dynamic equilibrium models in economics. We illustrate the power and simplicity of C++ Accelerated Massive Parallelism (C++ AMP) recently introduced by Microsoft. Starting from the same exercise as Aldrich et al. (J Econ Dyn...

  11. Scales of mantle heterogeneity

    Science.gov (United States)

    Moore, J. C.; Akber-Knutson, S.; Konter, J.; Kellogg, J.; Hart, S.; Kellogg, L. H.; Romanowicz, B.

    2004-12-01

    A long-standing question in mantle dynamics concerns the scale of heterogeneity in the mantle. Mantle convection tends to both destroy (through stirring) and create (through melt extraction and subduction) heterogeneity in bulk and trace element composition. Over time, these competing processes create variations in geochemical composition along mid-oceanic ridges and among oceanic islands, spanning a range of scales from extremely long wavelength (for example, the DUPAL anomaly) to very small scale (for example, variations amongst melt inclusions). While geochemical data and seismic observations can be used to constrain the length scales of mantle heterogeneity, dynamical mixing calculations can illustrate the processes and timescales involved in stirring and mixing. At the Summer 2004 CIDER workshop on Relating Geochemical and Seismological Heterogeneity in the Earth's Mantle, an interdisciplinary group evaluated scales of heterogeneity in the Earth's mantle using a combined analysis of geochemical data, seismological data and results of numerical models of mixing. We mined the PetDB database for isotopic data from glass and whole rock analyses for the Mid-Atlantic Ridge (MAR) and the East Pacific Rise (EPR), projecting them along the ridge length. We examined Sr isotope variability along the East Pacific rise by looking at the difference in Sr ratio between adjacent samples as a function of distance between the samples. The East Pacific Rise exhibits an overall bowl shape of normal MORB characteristics, with higher values in the higher latitudes (there is, however, an unfortunate gap in sampling, roughly 2000 km long). These background characteristics are punctuated with spikes in values at various locations, some, but not all of which are associated with off-axis volcanism. A Lomb-Scargle periodogram for unevenly spaced data was utilized to construct a power spectrum of the scale lengths of heterogeneity along both ridges. Using the same isotopic systems (Sr, Nd

  12. Deformation of Heterogeneous Nanocrystalline Lamella with a Preexisting Crack

    Science.gov (United States)

    Huang, Sixie; Wang, Jian; Zhou, Caizhi

    2017-10-01

    Molecular dynamics simulations were performed on heterogeneous nanocrystalline Al lamellae composed of nanocrystalline (NC) and single-crystalline (SC) layers to study the effect of the heterogeneous microstructures on the propagation of preexisting cracks. Under tensile loading, the heterogeneous NC Al lamella exhibited higher crack growth resistance than the pure NC Al. In addition, a lower volume fraction of the NC layer provided better crack growth resistance in heterogeneous lamellae (HL) samples, which agrees well with previous experiment results. After analyzing the distribution of the atom-level virial stress and microstructure evolution during the deformation, we found that the average stress on grain boundary atoms was much lower in HL samples than that in pure NC sample. When the crack approaches the interface, the heterogeneous microstructure can reduce the stress concentration by emitting dislocations from the interface into the SC layer.

  13. HETEROGENEOUS INTEGRATION TECHNOLOGY

    Science.gov (United States)

    2017-08-24

    the “product component” is a result of technology push only, it struggles to fit into a conservative system environment . If the “product component...makes the categorization difficult. In a technology push environment , the evolution of technology is easier to track since it starts evolving from a... environmental information. The role of the heterogeneous integration technology for reducing the size and the power consumption of small sensors was studied

  14. Micromechanics of heterogeneous materials

    CERN Document Server

    Buryachenko, Valeriy

    2007-01-01

    Here is an accurate and timely account of micromechanics, which spans materials science, mechanical engineering, applied mathematics, technical physics, geophysics, and biology. The book features rigorous and unified theoretical methods of applied mathematics and statistical physics in the material science of microheterogeneous media. Uniquely, it offers a useful demonstration of the systematic and fundamental research of the microstructure of the wide class of heterogeneous materials of natural and synthetic nature.

  15. Heterogeneous chromium catalysts

    OpenAIRE

    2005-01-01

    The present invention relates to a heterogeneous chromium catalyst system for the polymerisation of ethylene and/or alpha olefins prepared by the steps of: (a) providing a silica-containing support, (b) treating the silica-containing support with a chromium compound to form a chromium-based silica-containing support, (c) activating the chromium-based silica-containing support, (d) chemically reducing the activated chromium-based silica-containing support to produce a precursor catalyst, (e) r...

  16. Dynamic heterogeneity in life histories

    DEFF Research Database (Denmark)

    Tuljapurkar, Shripad; Steiner, Uli; Orzack, Steven Hecht

    2009-01-01

    generate dynamic heterogeneity: life-history differences produced by stochastic stratum dynamics. We characterize dynamic heterogeneity in a range of species across taxa by properties of the Markov chain: the entropy, which describes the extent of heterogeneity, and the subdominant eigenvalue, which...... distributions of lifetime reproductive success. Dynamic heterogeneity contrasts with fixed heterogeneity: unobserved differences that generate variation between life histories. We show by an example that observed distributions of lifetime reproductive success are often consistent with the claim that little...... or no fixed heterogeneity influences this trait. We propose that dynamic heterogeneity provides a 'neutral' model for assessing the possible role of unobserved 'quality' differences between individuals. We discuss fitness for dynamic life histories, and the implications of dynamic heterogeneity...

  17. Modeling Approaches for Describing Microbial Population Heterogeneity

    DEFF Research Database (Denmark)

    Lencastre Fernandes, Rita

    population consists of cells in different states, and it implies a heterogeneous distribution of activities (e.g. respiration, product yield), including different responses to extracellular stimuli. The existence of a heterogeneous cell population may explain the lower productivities obtained......) to predict distributions of certain population properties including particle size, mass or volume, and molecular weight. Similarly, PBM allow for a mathematical description of distributed cell properties within microbial populations. Cell total protein content distributions (a measure of cell mass) have been...... population dynamics, in response to the substrate consumption observed during batch cultivation. Cell size and cell cycle position distributions were used to describe the cell population. A two-stage PBM was developed and coupled to an unstructured model describing the extracellular environment. The good...

  18. Genetic heterogeneity of retinitis pigmentosa

    OpenAIRE

    Hartono, Hartono

    2015-01-01

    Genetic heterogeneity is a phenomenon in which a genetic disease can be transmitted by several modes of inheritance. The understanding of genetic heterogeneity is important in giving genetic counselling.The presence of genetic heterogeneity can be explained by the existence of:1.different mutant alleles at a single locus, and2.mutant alleles at different loci affecting the same enzyme or protein, or affecting different enzymes or proteins.To have an overall understanding of genetic heterogene...

  19. Tumor Heterogeneity in Breast Cancer

    Science.gov (United States)

    Turashvili, Gulisa; Brogi, Edi

    2017-01-01

    Breast cancer is a heterogeneous disease and differs greatly among different patients (intertumor heterogeneity) and even within each individual tumor (intratumor heterogeneity). Clinical and morphologic intertumor heterogeneity is reflected by staging systems and histopathologic classification of breast cancer. Heterogeneity in the expression of established prognostic and predictive biomarkers, hormone receptors, and human epidermal growth factor receptor 2 oncoprotein is the basis for targeted treatment. Molecular classifications are indicators of genetic tumor heterogeneity, which is probed with multigene assays and can lead to improved stratification into low- and high-risk groups for personalized therapy. Intratumor heterogeneity occurs at the morphologic, genomic, transcriptomic, and proteomic levels, creating diagnostic and therapeutic challenges. Understanding the molecular and cellular mechanisms of tumor heterogeneity that are relevant to the development of treatment resistance is a major area of research. Despite the improved knowledge of the complex genetic and phenotypic features underpinning tumor heterogeneity, there has been only limited advancement in diagnostic, prognostic, or predictive strategies for breast cancer. The current guidelines for reporting of biomarkers aim to maximize patient eligibility for targeted therapy, but do not take into account intratumor heterogeneity. The molecular classification of breast cancer is not implemented in routine clinical practice. Additional studies and in-depth analysis are required to understand the clinical significance of rapidly accumulating data. This review highlights inter- and intratumor heterogeneity of breast carcinoma with special emphasis on pathologic findings, and provides insights into the clinical significance of molecular and cellular mechanisms of heterogeneity. PMID:29276709

  20. Modeling Endovascular Coils as Heterogeneous Porous Media

    Science.gov (United States)

    Yadollahi Farsani, H.; Herrmann, M.; Chong, B.; Frakes, D.

    2016-12-01

    Minimally invasive surgeries are the stat-of-the-art treatments for many pathologies. Treating brain aneurysms is no exception; invasive neurovascular clipping is no longer the only option and endovascular coiling has introduced itself as the most common treatment. Coiling isolates the aneurysm from blood circulation by promoting thrombosis within the aneurysm. One approach to studying intra-aneurysmal hemodynamics consists of virtually deploying finite element coil models and then performing computational fluid dynamics. However, this approach is often computationally expensive and requires extensive resources to perform. The porous medium approach has been considered as an alternative to the conventional coil modeling approach because it lessens the complexities of computational fluid dynamics simulations by reducing the number of mesh elements needed to discretize the domain. There have been a limited number of attempts at treating the endovascular coils as homogeneous porous media. However, the heterogeneity associated with coil configurations requires a more accurately defined porous medium in which the porosity and permeability change throughout the domain. We implemented this approach by introducing a lattice of sample volumes and utilizing techniques available in the field of interactive computer graphics. We observed that the introduction of the heterogeneity assumption was associated with significant changes in simulated aneurysmal flow velocities as compared to the homogeneous assumption case. Moreover, as the sample volume size was decreased, the flow velocities approached an asymptotical value, showing the importance of the sample volume size selection. These results demonstrate that the homogeneous assumption for porous media that are inherently heterogeneous can lead to considerable errors. Additionally, this modeling approach allowed us to simulate post-treatment flows without considering the explicit geometry of a deployed endovascular coil mass

  1. Flow heterogeneity in reservoir rocks

    Energy Technology Data Exchange (ETDEWEB)

    Rosman, A.; Simon, R.

    1975-01-01

    A study by Chevron Oil Field Research Co. shows that microscopic flow heterogeneity values are essential for interpreting laboratory displacement data and properly evaluating field displacement projects. Chevron discusses microscopic flow heterogeneity in reservoir rocks: a measuring method, results of some measurements, and several applications to reservoir engineering problems. Heterogeneity is expressed in terms of both breakthrough recovery and the Dykstra-Parsons permeability variation. Microscopic flow heterogeneity in a reservoir rock is related to pore size, pore shape, and location of the different pore sizes that determine flow paths of various permeabilities. This flow heterogeneity affects secondary recovery displacement efficiency, residual oil and water saturations, and capillary pressure measurements.

  2. Heterogeneously integrated microsystem-on-a-chip

    Science.gov (United States)

    Chanchani, Rajen [Albuquerque, NM

    2008-02-26

    A microsystem-on-a-chip comprises a bottom wafer of normal thickness and a series of thinned wafers can be stacked on the bottom wafer, glued and electrically interconnected. The interconnection layer comprises a compliant dielectric material, an interconnect structure, and can include embedded passives. The stacked wafer technology provides a heterogeneously integrated, ultra-miniaturized, higher performing, robust and cost-effective microsystem package. The highly integrated microsystem package, comprising electronics, sensors, optics, and MEMS, can be miniaturized both in volume and footprint to the size of a bottle-cap or less.

  3. Recent developments in anisotropic heterogeneous shell theory

    CERN Document Server

    Grigorenko, Alexander Ya; Grigorenko, Yaroslav M; Vlaikov, Georgii G

    2016-01-01

    This volume focuses on the relevant general theory and presents some first applications, namely those based on classical shell theory. After a brief introduction, during which the history and state-of-the-art are discussed, the first chapter presents the mechanics of anisotropic heterogeneous shells, covering all relevant assumptions and the basic relations of 3D elasticity, classical and refined shell models. The second chapter examines the numerical techniques that are used, namely discrete orthogonalization, spline-collocation and Fourier series, while the third highlights applications based on classical theory, in particular, the stress-strain state of shallow shells, non-circular shells, shells of revolution, and free vibrations of conical shells. The book concludes with a summary and an outlook bridging the gap to the second volume.

  4. Melting of heterogeneous vortex matter: The vortex 'nanoliquid'

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 66; Issue 1. Melting of heterogeneous vortex matter: The vortex ... By sweeping the applied magnetic field, the number of vortices in the nanodroplets is varied continuously from a few to several hundred. Upon cooling, the caged nanodroplets freeze into ordered ...

  5. On Howard's conjecture in heterogeneous shear flow problem

    Indian Academy of Sciences (India)

    Home; Journals; Proceedings – Mathematical Sciences; Volume 113; Issue 4. On Howard's ... 10 (1961) 496–508), where is the basic heterogeneity distribution function). Author Affiliations. R G Shandil1 Jagjit Singh1 2. Department of Mathematics, H.P. University, Shimla 171 005, India; Sidharth Govt. Degree College ...

  6. Large epidemic thresholds emerge in heterogeneous networks of heterogeneous nodes

    OpenAIRE

    Hui Yang; Ming Tang; Thilo Gross

    2015-01-01

    One of the famous results of network science states that networks with heterogeneous connectivity are more susceptible to epidemic spreading than their more homogeneous counterparts. In particular, in networks of identical nodes it has been shown that network heterogeneity, i.e. a broad degree distribution, can lower the epidemic threshold at which epidemics can invade the system. Network heterogeneity can thus allow diseases with lower transmission probabilities to persist and spread. Howeve...

  7. Large epidemic thresholds emerge in heterogeneous networks of heterogeneous nodes.

    Science.gov (United States)

    Yang, Hui; Tang, Ming; Gross, Thilo

    2015-08-21

    One of the famous results of network science states that networks with heterogeneous connectivity are more susceptible to epidemic spreading than their more homogeneous counterparts. In particular, in networks of identical nodes it has been shown that network heterogeneity, i.e. a broad degree distribution, can lower the epidemic threshold at which epidemics can invade the system. Network heterogeneity can thus allow diseases with lower transmission probabilities to persist and spread. However, it has been pointed out that networks in which the properties of nodes are intrinsically heterogeneous can be very resilient to disease spreading. Heterogeneity in structure can enhance or diminish the resilience of networks with heterogeneous nodes, depending on the correlations between the topological and intrinsic properties. Here, we consider a plausible scenario where people have intrinsic differences in susceptibility and adapt their social network structure to the presence of the disease. We show that the resilience of networks with heterogeneous connectivity can surpass those of networks with homogeneous connectivity. For epidemiology, this implies that network heterogeneity should not be studied in isolation, it is instead the heterogeneity of infection risk that determines the likelihood of outbreaks.

  8. Heterogeneous logics of competition

    DEFF Research Database (Denmark)

    Mossin, Christiane

    2015-01-01

    The purpose of the article is to demonstrate that in order to understand competition as a socially organizing phenomenon, we should not examine competition in isolation, but as constellations of heterogeneous logics. More precisely, the article is based on two main theoretical points: (1) Logics...... of competition are only realized as particular forms of social organization by virtue of interplaying with other kinds of logics, like legal logics. (2) Competition logics enjoy a peculiar status in-between constructedness and givenness; although competition depends on laws and mechanisms of socialization, we...... still experience competition as an expression of spontaneous human activities. On the basis of these perspectives, a study of fundamental rights of EU law, springing from the principle of ‘free movement of people’, is conducted. The first part of the empirical analysis seeks to detect the presence...

  9. Heterogenous networks and services

    DEFF Research Database (Denmark)

    Tan, Su-En

    2006-01-01

    of the market. If mainstream technology firms do not address the disruption, it is likely they will fail and the new disruptive firm will grow in size and importance in the industry. As we move to 3G (3rd Generation Mobile Services) and beyond 3G, one of the biggest challenges is to bridge network heterogeneity...... representations of strategy, will then help to determine the success or failure of the technology. This is shown typically in the case of WiFi. WiFi is a wireless technology that addressed a new market, but was soon adopted as a complement by mobile operators into their suite of services. However, the future......This thesis considers the development of the mobile industry from a techno-economic perspective. Theory of disruptive technologies and related theories are examined and further developed. While much of technology change has been analysed on either a technical level or a market level, another plane...

  10. Heterogeneous dynamics in the bacterial cytoplasm

    Science.gov (United States)

    Parry, Brad

    The bacterial cytoplasm is a highly crowded environment, with estimates of excluded volume reaching 40 - 60%. A diverse array of highly polydisperse components is responsible for crowding and ranges from metabolites to compact proteins to large nucleic acid polymers and macromolecular assemblies. In contrast to eukaryotic cells, bacterial cells lack membrane delimited intracellular components. To measure the material properties of the Eschericia coli cytoplasm, I tracked foreign particles of different sizes in various cellular states. I found particle motion to be dependent on cellular metabolism at physiological pH and exhibited dynamical properties associated with glass-like materials, including particle caging and un-caging and heterogeneous dynamics in single cells. When particle mobility was compared across populations of cells, an enormous amount of heterogeneity was measured that increased over time. This inter-cellular heterogeneity could be separated into contributions from cellular components and differences in effective cytoplasmic viscosity between cells. These findings have implications for bacterial physiology and motivate experiments and simulations in colloid-polymer mixtures with high polydispersity.

  11. Biogenic Iron-Rich Filaments in the Quartz Veins in the Uppermost Ediacaran Qigebulake Formation, Aksu Area, Northwestern Tarim Basin, China: Implications for Iron Oxidizers in Subseafloor Hydrothermal Systems.

    Science.gov (United States)

    Zhou, Xiqiang; Chen, Daizhao; Tang, Dongjie; Dong, Shaofeng; Guo, Chuan; Guo, Zenghui; Zhang, Yanqiu

    2015-07-01

    Fe-(oxyhydr)oxide-encrusted filamentous microstructures produced by microorganisms have been widely reported in various modern and ancient extreme environments; however, the iron-dependent microorganisms preserved in hydrothermal quartz veins have not been explored in detail because of limited materials available. In this study, abundant well-preserved filamentous microstructures were observed in the hydrothermal quartz veins of the uppermost dolostones of the terminal-Ediacaran Qigebulake Formation in the Aksu area, northwestern Tarim Basin, China. These filamentous microstructures were permineralized by goethite and hematite as revealed by Raman spectroscopy and completely entombed in chalcedony and quartz cements. Microscopically, they are characterized by biogenic filamentous morphologies (commonly 20-200 μm in length and 1-5 μm in diameter) and structures (curved, tubular sheath-like, segmented, and mat-like filaments), similar to the Fe-oxidizing bacteria (FeOB) living in modern and ancient hydrothermal vent fields. A previous study revealed that quartz-barite vein swarms were subseafloor channels of low-temperature, silica-rich, diffusive hydrothermal vents in the earliest Cambrian, which contributed silica to the deposition of the overlying bedded chert of the Yurtus Formation. In this context, this study suggests that the putative filamentous FeOB preserved in the quartz veins might have thrived in the low-temperature, silica- and Fe(II)-rich hydrothermal vent channels in subseafloor mixing zones and were rapidly fossilized by subsequent higher-temperature, silica-rich hydrothermal fluids in response to waning and waxing fluctuations of diffuse hydrothermal venting. In view of the occurrence in a relatively stable passive continental margin shelf environment in Tarim Block, the silica-rich submarine hydrothermal vent system may represent a new and important geological niche favorable for FeOB colonization, which is different from their traditional

  12. Heterogeneity in recombinant protein production

    DEFF Research Database (Denmark)

    Schalén, Martin; Johanson, Ted; Lundin, Luisa

    2012-01-01

    contribute to make a population in a fermenter heterogeneous, resulting in cell-to-cell variation in physiological parameters of the microbial culture. Our study aims at investigating how population heterogeneity and recombinant protein production is affected by environmental gradients in bioreactors...... are simulated in small bioreactors and the population heterogeneity can be visualised by analysing single cells with flow cytometry. This can give new insights to cell physiology and recombinant protein production at the industrial scale....

  13. Space Qualified Heterogeneous Processing Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Space Micro proposes to develop a radiation hardened, monolithic, heterogeneous processor for space imaging and radar systems. High performance processors are needed...

  14. Heterogeneity of an earth

    Science.gov (United States)

    Litvinova, T.; Petrova, A.

    2009-04-01

    The study of magnetic anomaly field structure of the Barents Sea water area along seismic and extended profiles intersecting known fields is carried out. Geomagnetic and density sections down to 40 km depth are constructed. This allowed the estimation of heterogeneities of the Barents Sea water area deep structure. The analysis of geomagnetic and density sections along extended profiles showed the confinedness of oil-and-gas bearing provinces to deep permeable zones characterized by reduced magnetic and density features. Based on the analysis of permeable zones, regional diagnostic features similar to those obtained earlier in oil-and-gas bearing provinces in other regions, for example, in Timan-Pechora, Volga-Urals and Siberian, as well as in the Northern and Norwegian seas water areas, are revealed. The analysis of magnetic and gravity fields over the region area allowed the delineation of weakened zones as intersection areas of weakly magnetic areals with reduced density. Within the Barents Sea water area, permeable areas with lenticular-laminated structure of the upper and lower Earth's crust containing weakly magnetic areals with reduced rock density within the depth range of 8-12 and 15-20 km are revealed. Such ratio of magnetic and density heterogeneities in the Earth's crust is characteristic for zones with proved oil-and-gas content in the European part of the Atlantic Ocean water area. North Kildin field on 1 AR profile is confined to a trough with thick weakly magnetic stratum discontinuously traced to a depth of 6-10 km. At a depth of approximately 15 km, a lens of weakly magnetic and porous formations is observed. Ludlov field in the North Barents trough is confined to a zone of weakly magnetic rocks with reduced density traced to a depth of 8-9 km. Deeper, at Н=15 km, a lenticular areal of weakly magnetic formations with reduced density is observed. The profile transecting the Stockman field shows that it is located in the central part of a permeable

  15. Heterogeneity: multilingualism and democracy

    Directory of Open Access Journals (Sweden)

    Hans-Jürgen Krumm

    2004-01-01

    Full Text Available Linguistic diversity and multilingualism on the part of individuals are aprerequisite and a constitutive condition of enabling people to live togetherin a world of growing heterogeneity. Foreign language teaching plays animportant part in democratic education because it can be seen as a trainingin respecting otherness and developing an intercultural, non-ethnocentricperception and attitude. This is all the more important because of the neces-sity of integrating children from migrant families into school life.My article argues that language education policy has to take this per-spective into account, i.e., of establishing a planned diversification so thatpupils (and their parents will not feel satisfied with learning English only,but also become motivated to learn languages of their own neighbourhood,such as migrant and minority languages. However, in order to make use ofthe linguistic resources in the classroom, relating it to the democratic impetusof foreign language education, it is necessary to revise existing languagepolicies and to develop a multilingual perspective for all educational institutions.

  16. Theory of heterogeneous viscoelasticity

    Science.gov (United States)

    Schirmacher, Walter; Ruocco, Giancarlo; Mazzone, Valerio

    2016-03-01

    We review a new theory of viscoelasticity of a glass-forming viscous liquid near and below the glass transition. In our model, we assume that each point in the material has a specific viscosity, which varies randomly in space according to a fluctuating activation free energy. We include a Maxwellian elastic term, and assume that the corresponding shear modulus fluctuates as well with the same distribution as that of the activation barriers. The model is solved in coherent potential approximation, for which a derivation is given. The theory predicts an Arrhenius-type temperature dependence of the viscosity in the vanishing frequency limit, independent of the distribution of the activation barriers. The theory implies that this activation energy is generally different from that of a diffusing particle with the same barrier height distribution. If the distribution of activation barriers is assumed to have the Gaussian form, the finite-frequency version of the theory describes well the typical low-temperature alpha relaxation peak of glasses. Beta relaxation can be included by adding another Gaussian with centre at much lower energies than that is responsible for the alpha relaxation. At high frequencies, our theory reduces to the description of an elastic medium with spatially fluctuating elastic moduli (heterogeneous elasticity theory), which explains the occurrence of the boson peak-related vibrational anomalies of glasses.

  17. Parsing Heterogeneous Striatal Activity

    Directory of Open Access Journals (Sweden)

    Kae Nakamura

    2017-05-01

    Full Text Available The striatum is an input channel of the basal ganglia and is well known to be involved in reward-based decision making and learning. At the macroscopic level, the striatum has been postulated to contain parallel functional modules, each of which includes neurons that perform similar computations to support selection of appropriate actions for different task contexts. At the single-neuron level, however, recent studies in monkeys and rodents have revealed heterogeneity in neuronal activity even within restricted modules of the striatum. Looking for generality in the complex striatal activity patterns, here we briefly survey several types of striatal activity, focusing on their usefulness for mediating behaviors. In particular, we focus on two types of behavioral tasks: reward-based tasks that use salient sensory cues and manipulate outcomes associated with the cues; and perceptual decision tasks that manipulate the quality of noisy sensory cues and associate all correct decisions with the same outcome. Guided by previous insights on the modular organization and general selection-related functions of the basal ganglia, we relate striatal activity patterns on these tasks to two types of computations: implementation of selection and evaluation. We suggest that a parsing with the selection/evaluation categories encourages a focus on the functional commonalities revealed by studies with different animal models and behavioral tasks, instead of a focus on aspects of striatal activity that may be specific to a particular task setting. We then highlight several questions in the selection-evaluation framework for future explorations.

  18. Fiscal Consolidations and Heterogeneous Expectations

    NARCIS (Netherlands)

    Hommes, C.; Lustenhouwer, J.; Mavromatis, K.

    2015-01-01

    We analyze fiscal consolidations using a New Keynesian model where agents have heterogeneous expectations and are uncertain about the composition of consoidations. Heterogeneity in expectations may amplify expansions, stabilizing thus the debt-to-GDP ratio faster under tax based consolidations, in

  19. Query Expansion Using Heterogeneous Thesauri.

    Science.gov (United States)

    Mandala, Rila; Tokunaga, Takenobu; Tanaka, Hozumi

    2000-01-01

    Proposes a method to improve the performance of information retrieval systems by expanding queries using heterogeneous thesauri. Experiments show that using heterogeneous thesauri with an appropriate weighting method results in better retrieval performance than using only one type of thesaurus. (Author/LRW)

  20. Dynamic heterogeneity in life histories.

    Science.gov (United States)

    Tuljapurkar, Shripad; Steiner, Ulrich K; Orzack, Steven Hecht

    2009-01-01

    Longitudinal data on natural populations have been analysed using multistage models in which survival depends on reproductive stage, and individuals change stages according to a Markov chain. These models are special cases of stage-structured population models. We show that stage-structured models generate dynamic heterogeneity: life-history differences produced by stochastic stratum dynamics. We characterize dynamic heterogeneity in a range of species across taxa by properties of the Markov chain: the entropy, which describes the extent of heterogeneity, and the subdominant eigenvalue, which describes the persistence of reproductive success during the life of an individual. Trajectories of reproductive stage determine survivorship, and we analyse the variance in lifespan within and between trajectories of reproductive stage. We show how stage-structured models can be used to predict realized distributions of lifetime reproductive success. Dynamic heterogeneity contrasts with fixed heterogeneity: unobserved differences that generate variation between life histories. We show by an example that observed distributions of lifetime reproductive success are often consistent with the claim that little or no fixed heterogeneity influences this trait. We propose that dynamic heterogeneity provides a 'neutral' model for assessing the possible role of unobserved 'quality' differences between individuals. We discuss fitness for dynamic life histories, and the implications of dynamic heterogeneity for the evolution of life histories and senescence.

  1. Heterogeneous noise enhances spatial reciprocity

    CERN Document Server

    Yao, Y

    2014-01-01

    Recent research has identified the heterogeneity as crucial for the evolution of cooperation in spatial population. However, the influence of heterogeneous noise is still lack. Inspired by this interesting question, in this work, we try to incorporate heterogeneous noise into the evaluation of utility, where only a proportion of population possesses noise, whose range can also be tuned. We find that increasing heterogeneous noise monotonously promotes cooperation and even translates the full defection phase (of the homogeneous version) into the complete cooperation phase. Moreover, the promotion effect of this mechanism can be attributed to the leading role of cooperators who have the heterogeneous noise. These type of cooperators can attract more agents penetrating into the robust cooperator clusters, which is beyond the text of traditional spatial reciprocity. We hope that our work may shed light on the understanding of the cooperative behavior in the society.

  2. Field heterogeneity: some basic issues

    Energy Technology Data Exchange (ETDEWEB)

    Philip, J.R.

    1980-04-01

    Present-day soil-water physics enables useful quantitative predictions in the laboratory and in simple field situations. However, difficulties frequently arise for areas of appreciable size in the field. Two types of heterogeneity are distinguished: deterministic and stochastic. The first often demands an extension of established analyses and may involve important phenomena absent from the analogous homogeneous problem. Stochastic heterogeneity may involve many scales and is imperfectly known. The statistical properties may be stationary, but in more complicated cases, randomness may be embedded in (either known or unknown) systematic trends. Some aspects of unsaturated and generally unsteady flow in heterogeneous systems are reviewed: the mathematical nature of the flow equation; the concept of scale-heterogeneity; analytical and quasianalytical solutions. The enormity of the total problem of unsaturated unsteady flow in stochastic heterogeneous systems is illustrated through a dialectic of 8 successive stages of simplification. 37 references.

  3. Homogeneous, Heterogeneous, and Enzymatic Catalysis.

    Science.gov (United States)

    Oyama, S. Ted; Somorjai, Gabor A.

    1988-01-01

    Discusses three areas of catalysis: homegeneous, heterogeneous, and enzymatic. Explains fundamentals and economic impact of catalysis. Lists and discusses common industrial catalysts. Provides a list of 107 references. (MVL)

  4. Formation of Rationally Heterogeneous Expectations

    NARCIS (Netherlands)

    Pfajfar, D.

    2012-01-01

    Abstract: This paper models expectation formation by taking into account that agents produce heterogeneous expectations due to model uncertainty, informational frictions and different capacities for processing information. We show that there are two general classes of steady states within this

  5. Electrocardiographic assessment of repolarization heterogeneity

    NARCIS (Netherlands)

    Hooft van Huysduynen, Bart

    2006-01-01

    Repolarization heterogeneity refers to differences in repolarization instants in the heart. Normally, repolarization in the human heart is a relatively smooth, continuous process, during which adjacent areas repolarize almost simultaneously. Several drugs or cardiac diseases may disturb the

  6. Optimizations in Heterogeneous Mobile Networks

    DEFF Research Database (Denmark)

    Popovska Avramova, Andrijana

    Heterogeneous Mobile Networks bring advantages over homogeneous deployments in achieving the demand for mobile network capacity and coverage not just outdoor rural and urban areas, but also to homes and enterprises where the large portion of the mobile traffic is generated. However......, the heterogeneity in the mobile networks bring many challenges that are discusses with this dissertation. More focus is placed on specific issues with indifferent areas of heterogeneity by proposing optimizations in order to overcome the considered problems.The heterogeneity of mobile networks, together...... with the densification of the base stations, bring into a very complex network management and operation control for the mobile operators. Furthermore, the need to provide always best connection and service with high quality demands for a joint overall network resource management. This thesis addresses this challenge...

  7. Job Scheduling in a Heterogeneous Grid Environment

    Science.gov (United States)

    Shan, Hong-Zhang; Smith, Warren; Oliker, Leonid; Biswas, Rupak

    2004-01-01

    Computational grids have the potential for solving large-scale scientific problems using heterogeneous and geographically distributed resources. However, a number of major technical hurdles must be overcome before this potential can be realized. One problem that is critical to effective utilization of computational grids is the efficient scheduling of jobs. This work addresses this problem by describing and evaluating a grid scheduling architecture and three job migration algorithms. The architecture is scalable and does not assume control of local site resources. The job migration policies use the availability and performance of computer systems, the network bandwidth available between systems, and the volume of input and output data associated with each job. An extensive performance comparison is presented using real workloads from leading computational centers. The results, based on several key metrics, demonstrate that the performance of our distributed migration algorithms is significantly greater than that of a local scheduling framework and comparable to a non-scalable global scheduling approach.

  8. Heterogeneous Thermochemical Decomposition Under Direct Irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Lipinski, W.; Steinfeld, A. [PSI and ETH Zuerich(Switzerland)

    2005-03-01

    Radiative heat transfer in a chemical reacting system directly exposed to an external source of high-flux radiation is considered. The endothermic decomposition of CaCO{sub 3}(s) into CaO(s) and CO{sub 2}(g) is selected as the model heterogeneous reaction. Experimentation using an Ar arc as the radiation source was carried out in which powder samples were subjected to radiative power fluxes in the range 400-930 kW/m{sup 2}. A 3D transient heat transfer model that links conduction-convection-radiation heat transfer to the chemical kinetics is formulated using wavelength and chemical composition dependent material properties. Monte-Carlo ray tracing and the Rosseland diffusion approximation are employed to obtain the radiative transport. The unsteady energy equation is solved by finite volume technique. The model is validated by com-paring the computed reaction extent variation with time to the values experimentally measured. (author)

  9. DYNAMIC HETEROGENEITY IN LIFE HISTORIES

    OpenAIRE

    Tuljapurkar, Shripad; Steiner, Ulrich K.; Orzack, Steven Hecht

    2008-01-01

    Longitudinal data on natural populations have been analyzed using multi-stage models in which survival depends on reproductive stage, and individuals change stages according to a Markov chain. These models are special cases of stage-structured population models. We show that stage-structured models generate dynamic heterogeneity: life history differences produced by stochastic stratum dynamics. We characterize dynamic heterogeneity in a range of species across taxa by properties of the Markov...

  10. Impact of mineralogical heterogeneity on reactive transport modelling

    Science.gov (United States)

    Liu, Min; Shabaninejad, Mehdi; Mostaghimi, Peyman

    2017-07-01

    Impact of mineralogical heterogeneity of rocks in reactive modelling is investigated by applying a pore scale model based on the Lattice Boltzmann and Finite Volume Methods. Mass transport, chemical reaction and solid structure modification are included in the model. A two-dimensional mineral map of a sandstone rock is acquired using the imaging technique of QEMSCAN SEM with Energy-Dispersive X-ray Spectroscopy (EDS). The mineralogical heterogeneity is explored by conducting multi-mineral reaction simulations on images containing various minerals. The results are then compared with the prediction of single mineral dissolution modelling. Dissolution patterns and permeability variations of multi-mineral and single mineral reactions are presented. The errors of single mineral reaction modelling are also estimated. Numerical results show that mineralogical heterogeneity can cause significant errors in permeability prediction, if a uniform mineral distribution is assumed. The errors are smaller in high Péclet regimes than in low Péclet regimes in this sample.

  11. Bio-inspired heterogeneous composites for broadband vibration mitigation

    Science.gov (United States)

    Chen, Yanyu; Wang, Lifeng

    2015-12-01

    Structural biological materials have developed heterogeneous and hierarchical architectures that are responsible for the outstanding performance to provide protection against environmental threats including static and dynamic loading. Inspired by this observation, this research aims to develop new material and structural concepts for broadband vibration mitigation. The proposed composite materials possess a two-layered heterogeneous architecture where both layers consist of high-volume platelet-shape reinforcements and low-volume matrix, similar to the well-known “brick and mortar” microstructure of biological composites. Using finite element method, we numerically demonstrated that broadband wave attenuation zones can be achieved by tailoring the geometric features of the heterogeneous architecture. We reveal that the resulting broadband attenuation zones are gained by directly superimposing the attenuation zones in each constituent layer. This mechanism is further confirmed by the investigation into the phonon dispersion relation of each layer. Importantly, the broadband wave attenuation capability will be maintained when the mineral platelet orientation is locally manipulated, yet a contrast between the mineral platelet concentrations of the two constituent layers is essential. The findings of this work will provide new opportunities to design heterogeneous composites for broadband vibration mitigation and impact resistance under mechanically challenging environmental conditions.

  12. Heterogeneous effect at FRM-II

    Energy Technology Data Exchange (ETDEWEB)

    Petrov, Yu.V.; Onegin, M.S. [Petersburg Nuclear Physics Inst., Gatchina (Russian Federation). Theoretical Dept.; Boening, K.; Nuding, M. [ZBE FRM-II-Bau, Technische Univ. Muenchen, Garching (Germany)

    2001-07-01

    The cores of modern research reactors (RR) are characterized by a relatively small volume and a high neutron leakage in order to yield an efficient production of thermal neutrons in the outside moderator. Many RR have fuel elements with aluminum-clad fuel plates cooled by light water. Due to a large difference of the mean free paths of the neutrons in H{sub 2}O and Al a relatively large so called ''heterogeneous effect'' (HE) arises in such cores. By definition the HE is the difference between the results for the reactivity obtained from a detailed calculation considering the realistic ''heterogeneous'' geometry of the core and from a simplified calculation using a ''homogeneous'' core model in which the fuel plate lattice is homogenized: {delta}{rho}{sub HE} = {rho}{sup het} - {rho}{sup hom}. For the first time this negative HE has been found for an aluminum-clad core in the course of calculations performed for the research reactor WWR-M at Gatchina. In the work as described in this paper the HE was calculated for the FRM-II. The ''heterogeneous'' calculation has been performed using two different Monte Carlo codes: MCU-RFFI and MCNP-4B with the ENDF/B-VI library. The fuel element of the FRM-II was modeled in detail: the involute shape of all 113 fuel plates, the cladding, the coolant channels etc. were exactly reproduced. The involute shape of each 1.36 mm thick fuel plate was modeled with an accuracy better than 3 {mu}m. Very important is the adequate reproduction of the energy dependence of the Al cross section. The ''homogeneous'' calculations used for reference were older Monte Carlo code calculations in which the core structure was homogenized from the beginning (i.e. without a special cell calculation). In the calculations performed with the code MCNP the HE is equal to {delta}{rho}{sub HE} = -0.5(1)% to -0.9(1)% depending on the position of the central

  13. Seismic signal processing on heterogeneous supercomputers

    Science.gov (United States)

    Gokhberg, Alexey; Ermert, Laura; Fichtner, Andreas

    2015-04-01

    The processing of seismic signals - including the correlation of massive ambient noise data sets - represents an important part of a wide range of seismological applications. It is characterized by large data volumes as well as high computational input/output intensity. Development of efficient approaches towards seismic signal processing on emerging high performance computing systems is therefore essential. Heterogeneous supercomputing systems introduced in the recent years provide numerous computing nodes interconnected via high throughput networks, every node containing a mix of processing elements of different architectures, like several sequential processor cores and one or a few graphical processing units (GPU) serving as accelerators. A typical representative of such computing systems is "Piz Daint", a supercomputer of the Cray XC 30 family operated by the Swiss National Supercomputing Center (CSCS), which we used in this research. Heterogeneous supercomputers provide an opportunity for manifold application performance increase and are more energy-efficient, however they have much higher hardware complexity and are therefore much more difficult to program. The programming effort may be substantially reduced by the introduction of modular libraries of software components that can be reused for a wide class of seismology applications. The ultimate goal of this research is design of a prototype for such library suitable for implementing various seismic signal processing applications on heterogeneous systems. As a representative use case we have chosen an ambient noise correlation application. Ambient noise interferometry has developed into one of the most powerful tools to image and monitor the Earth's interior. Future applications will require the extraction of increasingly small details from noise recordings. To meet this demand, more advanced correlation techniques combined with very large data volumes are needed. This poses new computational problems that

  14. Organizational heterogeneity of vertebrate genomes.

    Directory of Open Access Journals (Sweden)

    Svetlana Frenkel

    Full Text Available Genomes of higher eukaryotes are mosaics of segments with various structural, functional, and evolutionary properties. The availability of whole-genome sequences allows the investigation of their structure as "texts" using different statistical and computational methods. One such method, referred to as Compositional Spectra (CS analysis, is based on scoring the occurrences of fixed-length oligonucleotides (k-mers in the target DNA sequence. CS analysis allows generating species- or region-specific characteristics of the genome, regardless of their length and the presence of coding DNA. In this study, we consider the heterogeneity of vertebrate genomes as a joint effect of regional variation in sequence organization superimposed on the differences in nucleotide composition. We estimated compositional and organizational heterogeneity of genome and chromosome sequences separately and found that both heterogeneity types vary widely among genomes as well as among chromosomes in all investigated taxonomic groups. The high correspondence of heterogeneity scores obtained on three genome fractions, coding, repetitive, and the remaining part of the noncoding DNA (the genome dark matter--GDM allows the assumption that CS-heterogeneity may have functional relevance to genome regulation. Of special interest for such interpretation is the fact that natural GDM sequences display the highest deviation from the corresponding reshuffled sequences.

  15. Reaction Selectivity in Heterogeneous Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Somorjai, Gabor A.; Kliewer, Christopher J.

    2009-02-02

    The understanding of selectivity in heterogeneous catalysis is of paramount importance to our society today. In this review we outline the current state of the art in research on selectivity in heterogeneous catalysis. Current in-situ surface science techniques have revealed several important features of catalytic selectivity. Sum frequency generation vibrational spectroscopy has shown us the importance of understanding the reaction intermediates and mechanism of a heterogeneous reaction, and can readily yield information as to the effect of temperature, pressure, catalyst geometry, surface promoters, and catalyst composition on the reaction mechanism. DFT calculations are quickly approaching the ability to assist in the interpretation of observed surface spectra, thereby making surface spectroscopy an even more powerful tool. HP-STM has revealed three vitally important parameters in heterogeneous selectivity: adsorbate mobility, catalyst mobility, and selective site-blocking. The development of size controlled nanoparticles from 0.8 to 10 nm, of controlled shape, and of controlled bimetallic composition has revealed several important variables for catalytic selectivity. Lastly, DFT calculations may be paving the way to guiding the composition choice for multi-metallic heterogeneous catalysis for the intelligent design of catalysts incorporating the many factors of selectivity we have learned.

  16. Effect of tissue heterogeneity on quantification in positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Blomqvist, G. [Dept. of Clinical Neuroscience, Experimental Alcohol and Drug Addiction Research Section, Karolinska Hospital, Stockholm (Sweden); Lammertsma, A.A. [PET Methodology Group, Cyclotron Unit, MRC Clinical Sciences Centre, Royal Postgraduate Medical School, Hammersmith Hospital, London (United Kingdom); Mazoyer, B. [Service Hospitalier Frederic Joliot CEA/Dept. de Biologie, Hopital d`Orsay and Antenne d`Informatique Medicale, Hopital Robert Debre, Paris (France); Wienhard, K. [Max-Planck-Inst. fuer Neurologische Forschung, Koeln (Germany)

    1995-07-01

    As a result of the limited spatial resolution of positron emission tomographic scanners, the measurements of physiological parameters are compromised by tissue heterogeneity. The effect of tissue heterogeneity on a number of parameters was studied by simulation and an analytical method. Five common tracer models were assessed. The input and tissue response functions were assumed to be free from noise and systematic errors. The kinetic model was assumed to be perfect. Two components with different kinetics were mixed in different proportions and contrast with respect to the model parameters. Different experimental protocols were investigated. Of three methods investigated for the measurement of cerebral blood flow (CBF) (steady state, dynamic, integral), the second one was least sensitive to errors caused by tissue heterogeneity and the main effect was an underestimation of the distribution volume. With the steady state method, errors in oxygen extraction fraction caused by tissue heterogeneity were always found to be less than the corresponding errors in CBF. For myocardial blood flow the steady state method was found to perform better than the bolus method. The net accumulation of substrate (i.e. rCMR{sub glc} in the case of glucose analogs) was found to be comparatively insensitive to tissue heterogeneity. Individual rate constans such as k{sub 2} and k{sub 3} for efflux and metabolism of the substrate in the pool of unmetabolized substrate in the tissue, respectively, were found to be more sensitive. In studies of radioligand binding, using only tracer doses, the effect of tissue heterogeneity on the parameter k{sub on}.B{sub max} could be considerable. In studies of radioligand binding using a protocol with two experiments, one with high and one with low specific activity, B{sub max} was found to be insensitive while K{sub d} was very sensitive to tissue heterogeneity. (orig.)

  17. Heterogeneity in Preferences and Productivity

    DEFF Research Database (Denmark)

    Gørtz, Mette

    This paper discusses the determinants of the retirement decision and the implications of retirement on economic well-being. The main contribution of the paper is to formulate the role of individual heterogeneity explicitly. We argue that individual heterogeneity in 1) productivity of market work...... choices of expenditure, household production and leisure for people in and around retirement. The unobserved individual heterogeneity factor is isolated by comparing cross-sectional evidence and panel data estimates of the effects of retirement on consumption and time allocation. Based on cross......-section data, we can identify a difference in consumption due to retirement status, but when the panel nature of the data is exploited, the effect of retirement on consumption is small and insignificant. Moreover, the analyses point at a large positive effect of retirement on household production. Our results...

  18. Coordination Frictions and Job Heterogeneity

    DEFF Research Database (Denmark)

    Kennes, John; le Maire, Christian Daniel

    This paper develops and extends a dynamic, discrete time, job to worker matching model in which jobs are heterogeneous in equilibrium. The key assumptions of this economic environment are (i) matching is directed and (ii) coordination frictions lead to heterogeneous local labor markets. We de- rive...... a number of new theoretical results, which are essential for the empirical application of this type of model to matched employer-employee microdata. First, we o¤er a robust equilibrium concept in which there is a continu- ous dispersion of job productivities and wages. Second, we show that our model can...... be readily solved with continuous exogenous worker heterogene- ity, where high type workers (high outside options and productivity) earn higher wages in high type jobs and are hired at least as frequently to the better job types as low type workers (low outside options and productivity). Third, we...

  19. How to measure genetic heterogeneity

    Science.gov (United States)

    Yamada, Ryo

    2009-12-01

    Genetic information of organisms is coded as a string of four letters, A, T, G and C, a sequence in macromolecules called deoxyribonucleic acid (DNA). DNA sequence offers blueprint of organisms and its heterogeneity determines identity and variation of species. The quantitation of this genetic heterogeneity is fundamental to understand biology. We compared previously-reported three measures, covariance matrix expression of list of loci (pair-wise r2), the most popular index in genetics, and its multi-dimensional form, Ψ, and entropy-based index, epsilon. Thereafter we proposed two methods so that we could handle the diplotypic heterogeneity and quantitate the conditions where the number of DNA sequence samples is much smaller than the number of possible variants.

  20. How to measure genetic heterogeneity

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Ryo, E-mail: ryamada@genome.med.kyoto-u.ac.j [Unit of Statistical Genetics, Center for Genomic Medicine, Graduate School of Medicine, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-0815 (Japan)

    2009-12-01

    Genetic information of organisms is coded as a string of four letters, A, T, G and C, a sequence in macromolecules called deoxyribonucleic acid (DNA). DNA sequence offers blueprint of organisms and its heterogeneity determines identity and variation of species. The quantitation of this genetic heterogeneity is fundamental to understand biology. We compared previously-reported three measures, covariance matrix expression of list of loci (pair-wise r{sup 2}), the most popular index in genetics, and its multi-dimensional form, {Psi}, and entropy-based index, {epsilon}. Thereafter we proposed two methods so that we could handle the diplotypic heterogeneity and quantitate the conditions where the number of DNA sequence samples is much smaller than the number of possible variants.

  1. Heterogeneity and Collective Action for Forest Management

    OpenAIRE

    Harini Nagendra

    2011-01-01

    Heterogeneity influences the likelihood of collective action for forest management. Theoretical examinations, focusing largely on economic heterogeneity, suggest that heterogeneity increases the likelihood of collective action. Field research however indicates that heterogeneity, whether in economic, social, or other dimensions, presents a challenge for collective action with variations in perceptions of costs and benefits amongst different groups, high transaction costs faced by the disadvan...

  2. Dynamic fracture of heterogeneous materials

    Energy Technology Data Exchange (ETDEWEB)

    Stout, M.G.; Liu, C.; Addessio, F.L.; Williams, T.O.; Bennett, J.G.; Haberman, K.S.; Asay, B.W.

    1998-12-31

    This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of this project was to investigate the fundamental aspects of the process of dynamic fracture propagation in heterogeneous materials. The work focused on three important, but poorly understood, aspects of dynamic fracture for materials with a heterogeneous microstructure. These were: the appropriateness of using a single-parameter asymptotic analysis to describe dynamic crack-tip deformation fields, the temperature rises at the tip and on the flanks of a running crack, and the constitutive modeling of damage initiation and accumulation.

  3. Source-Related Chemical and Isotopic Heterogeneities in Granitoids

    Science.gov (United States)

    Helps, P. A.; Clemens, J. D.; Petford, N.

    2004-05-01

    A survey of a large number of post-orogenic plutons, shows that regional-scale, intraplutonic isotope heterogeneities (initial 87Sr/86Sr and/or eNd) are common in crustally derived granitic rocks. This is to be expected since the source materials, from which the granitic magmas were created by partial melting, are themselves heterogeneous. If we accept that granitic magmas can ascend rapidly along dykes then there must be potential for the preservation of source-inherited isotopic heterogeneities. However, their preservation will depend on the extent of subsequent homogenisation processes, such as diffusion and convective mixing, occurring in the magma chambers. Two granitic intrusions from the UK are selected to show examples of isotopically and chemically heterogeneous granitoids. We are obtaining high-precision geochemical and isotopic (Sr, Nd, and O) data for spatially well constrained samples, to study the scales over which isotope heterogeneities are preserved, and the maximum volumes of magma over which isotope and elemental homogenisation may have been achieved. This information will provide important constraints on the physical and chemical characteristics of processes that occur during magma genesis, ascent, and emplacement. The Criffell pluton in the Southern Uplands of Scotland has previously been shown to be isotopically heterogeneous on the regional scale, with initial 87Sr/86Sr varying from 0.70521 to 0.70728, generally increasing inwards towards the centre of the pluton. This was interpreted as preservation of heterogeneity inherited from the magma source. Isotope data from our study reveal 87Sr/86Sr and eNd homogeneity on the decametre to the 100 m scale, suggesting a minimum scale over which homogenisation (mixing) was achieved. Alternatively, this scale represents the size of a single isotopically distinct batch of magma, within a pluton composed of many such batches. In contrast, the Dartmoor granite (SW Britain) shows marked variation in

  4. Renormalized Volume

    Science.gov (United States)

    Gover, A. Rod; Waldron, Andrew

    2017-09-01

    We develop a universal distributional calculus for regulated volumes of metrics that are suitably singular along hypersurfaces. When the hypersurface is a conformal infinity we give simple integrated distribution expressions for the divergences and anomaly of the regulated volume functional valid for any choice of regulator. For closed hypersurfaces or conformally compact geometries, methods from a previously developed boundary calculus for conformally compact manifolds can be applied to give explicit holographic formulæ for the divergences and anomaly expressed as hypersurface integrals over local quantities (the method also extends to non-closed hypersurfaces). The resulting anomaly does not depend on any particular choice of regulator, while the regulator dependence of the divergences is precisely captured by these formulæ. Conformal hypersurface invariants can be studied by demanding that the singular metric obey, smoothly and formally to a suitable order, a Yamabe type problem with boundary data along the conformal infinity. We prove that the volume anomaly for these singular Yamabe solutions is a conformally invariant integral of a local Q-curvature that generalizes the Branson Q-curvature by including data of the embedding. In each dimension this canonically defines a higher dimensional generalization of the Willmore energy/rigid string action. Recently, Graham proved that the first variation of the volume anomaly recovers the density obstructing smooth solutions to this singular Yamabe problem; we give a new proof of this result employing our boundary calculus. Physical applications of our results include studies of quantum corrections to entanglement entropies.

  5. Languages as semiotically heterogenous systems.

    Science.gov (United States)

    Kendon, Adam

    2017-01-01

    The target article is consistent with seeing languages as semiotically heterogenous, using categorial, depictive, and analogic semiotic signs. "Gesture," used in the target article, is shown to be vague and not useful. Kendon's view, criticised in the target, is restated. His proposal for comparative semiotic analyses of how visible bodily action is used in utterance production is reexplained.

  6. Communicating to heterogeneous target groups

    DEFF Research Database (Denmark)

    Pedersen, Karsten

    very often have to communicate to rather heterogeneous target groups that have little more in common than a certain geographical habitat. That goes against most schoolbook teaching in the field of communication, but is none the less the terms with which that kind of communication has to live...

  7. Genetic heterogeneity within the chondroitinsulphaturias.

    Science.gov (United States)

    Danes, B S; Rottell, B K; Eviatar, L; Stolzenberg, J

    1977-01-01

    The approach, identification of clinical phenotype followed by lysosomal enzyme assays in cell culture, used in the classification of the genetic mucopolysaccharidoses I-VI has been applied to the chondroitinsulphaturias. There was evidence of heterogeneity in the first 9 patients reported. Images PMID:404409

  8. Dynamic heterogeneity and life histories

    DEFF Research Database (Denmark)

    Tuljapurkar, Shripad; Steiner, Uli

    2010-01-01

    of the variation among individual characteristics that is generated by dynamic heterogeneity. We conclude by discussing our ongoing and planned work on animals and humans. We also discuss the connections between our work and recent work on human mortality, disability and health, and life course theory....

  9. A Heterogeneous Quantum Computer Architecture

    NARCIS (Netherlands)

    Fu, X.; Riesebos, L.; Lao, L.; Garcia Almudever, C.; Sebastiano, F.; Versluis, R.; Charbon, E.; Bertels, K.

    2016-01-01

    In this paper, we present a high level view of the heterogeneous quantum computer architecture as any future quantum computer will consist of both a classical and quantum computing part. The classical part is needed for error correction as well as for the execution of algorithms that contain both

  10. Social Capital and Community Heterogeneity

    Science.gov (United States)

    Coffe, Hilde

    2009-01-01

    Recent findings indicate that more pronounced community heterogeneity is associated with lower levels of social capital. These studies, however, concentrate on specific aspects in which people differ (such as income inequality or ethnic diversity). In the present paper, we introduce the number of parties in the local party system as a more…

  11. Social capital and community heterogeneity

    NARCIS (Netherlands)

    Coffé, Hilde R.

    2009-01-01

    Abstract Recent findings indicate that more pronounced community heterogeneity is associated with lower levels of social capital. These studies, however, concentrate on specific aspects in which people differ (such as income inequality or ethnic diversity). In the present paper, we introduce the

  12. Prices and heterogeneous search costs

    NARCIS (Netherlands)

    Moraga Gonzalez, J.L.; Sandor, Z.; Wildenbeest, M.R.

    2017-01-01

    We study price formation in a model of consumer search for differentiated products in which consumers have heterogeneous search costs. We provide conditions under which a pure-strategy symmetric Nash equilibrium exists and is unique. Search costs affect two margins—the intensive search margin (or

  13. Heterogeneous Beliefs and Climate Catastrophes

    NARCIS (Netherlands)

    Kiseleva, T.

    2016-01-01

    We study how heterogeneous beliefs about the causes and extent of global warming affect local mitigation and adaptation strategies and therefore global climate dynamics. Local policies are determined by expectations of policy makers about future climate. There are three types of expectations: strong

  14. The permeability of heterogeneous rocks

    Science.gov (United States)

    Selvadurai, Patrick

    2017-04-01

    Darcy's original concept of permeability is largely associated with estimation of the hydraulic conductivity characteristics of isotropic and homogeneous porous media where the fluid flow characteristics can be estimated by appeal to a single scalar measure. Naturally occurring geomaterials are heterogeneous and the estimation of the effective permeability characteristics of such geomaterials presents a challenge not only in terms of the experimental procedures that should be used to ensure flow through the porous medium but also in the correct use of the theoretical concepts needed to accurately interpret the data. Relatively widely referred to rocks such as Indiana Limestone can exhibit spatial heterogeneity in the permeability characteristics even though the visual appearance can suggest the absence of such spatial and directional attributes (Selvadurai and Selvadurai, 2010). Argillaceous rocks such as the Cobourg Limestone found in southern Ontario, Canada can display hydraulic heterogeneity that is attributed to the presence of dolomitic and calcite nodular regions separated by calcite rock partings that contain an argillaceous component (Figure 1). Also, these rocks have extremely low permeability that requires the use of transient hydraulic pulse tests for the estimation of permeability. The performance of such pulse tests will be influenced by the bulk compressibility and bulk porosity of the porous skeleton consisting of the identifiable phases and their spatial distributions. The concepts of effective compressibilities and porosities therefore needs to be introduced if convenient procedures are to be developed for the accurate interpretation of even bench scale experiments (Selvadurai and Gɫowacki, 2017). The paper will describe both experimental and theoretical approaches for interpreting the effective Darcy permeability of the heterogeneous rocks using both experimental and computational approaches. In particular, the applicability of the "Geometric

  15. Heterogeneous Viscoelasticity: A Combined Theory of Dynamic and Elastic Heterogeneity.

    Science.gov (United States)

    Schirmacher, Walter; Ruocco, Giancarlo; Mazzone, Valerio

    2015-07-03

    We present a heterogeneous version of Maxwell's theory of viscoelasticity based on the assumption of spatially fluctuating local viscoelastic coefficients. The model is solved in coherent-potential approximation. The theory predicts an Arrhenius-type temperature dependence of the viscosity in the vanishing-frequency limit, independent of the distribution of the activation energies. It is shown that this activation energy is generally different from that of a diffusing particle with the same barrier-height distribution, which explains the violation of the Stokes-Einstein relation observed frequently in glasses. At finite but low frequencies, the theory describes low-temperature asymmetric alpha relaxation. As examples, we report the good agreement obtained for selected inorganic, metallic, and organic glasses. At high frequencies, the theory reduces to heterogeneous elasticity theory, which explains the occurrence of the boson peak and related vibrational anomalies.

  16. Dielectric analysis of heterogeneous biological tissues based on mixing rule.

    Science.gov (United States)

    Zhang, Liang; Liu, Peiguo; Dong, Xiuzhen; Zhou, Dongming; Shi, Xuetao

    2015-01-01

    Thus far, the measurement of dielectric properties of biological tissues has been achieved on the assumption that the biological tissues are homogeneous. In fact, most tissues should be heterogeneous because there are many small structures included in these tissues, such as blood vessel, nerve fiber and so on. When the dielectric properties of these tissues are measured by conventional sensor, the results are not the dielectric properties of tissues but the effective dielectric properties of the mixture. In this paper, the influence of the inclusion in tissues on the measurement of dielectric properties of heterogeneous biological tissues is studied and the analysis of the effective dielectric properties of heterogeneous tissues based on the mixing rule is proposed. When the coaxial probe is used to measure the dielectric properties of tissue, the results are relative to the dielectric properties of inclusion, dielectric properties of background tissue and the effective volume fraction of inclusion. Therefore, the dielectric properties of inclusion could be calculated according to mixing rule, after the effective dielectric properties are measured and the effective volume fraction of inclusion is estimated.

  17. Biotic Drivers of Spatial Heterogeneity and Implications for River Ecosystems

    Science.gov (United States)

    Wohl, Ellen

    2017-04-01

    Rivers throughout the northern hemisphere have been simplified and homogenized by the removal of beavers and instream wood, along with numerous forms of channel engineering and flow regulation. Loss of spatial heterogeneity in river corridors - channels and floodplains - affects downstream fluxes of water, sediment, organic matter, and nutrients, as well as stream metabolism, biomass, and biodiversity. Recent work in streams of the Colorado Rocky Mountains illustrates how the presence of beavers and instream wood can facilitate spatial heterogeneity by creating stable, persistent, multithread channel planform and high channel-floodplain and channel-hyporheic zone connectivity. This spatial heterogeneity facilitates retention of water in pools, floodplain wetlands, and hyporheic storage. Suspended sediment, particulate organic matter (POM), and solutes are also more likely to be retained in these stream segments than in more uniform stream segments with greater downstream conveyance. Retention of POM and solutes equates to greater volumes of organic carbon storage per unit valley length and greater rates of nitrogen uptake. Spatially heterogeneous stream segments also exhibit greater biomass and biodiversity of aquatic macroinvertebrates, salmonid fish, and riparian spiders than do more uniform stream segments. These significant differences in stream form and function are unlikely to be unique to this field area and can provide a conceptual model for understanding and restoring ecosystem functions in other rivers.

  18. Replikasi Unidirectional pada Heterogen Database

    Directory of Open Access Journals (Sweden)

    Hendro Nindito

    2013-12-01

    Full Text Available The use of diverse database technology in enterprise today can not be avoided. Thus, technology is needed to generate information in real time. The purpose of this research is to discuss a database replication technology that can be applied in heterogeneous database environments. In this study we use Windows-based MS SQL Server database to Linux-based Oracle database as the goal. The research method used is prototyping where development can be done quickly and testing of working models of the interaction process is done through repeated. From this research it is obtained that the database replication technolgy using Oracle Golden Gate can be applied in heterogeneous environments in real time as well.

  19. Heterogenization of alkene epoxidation catalysts

    Directory of Open Access Journals (Sweden)

    Buffon Regina

    2003-01-01

    Full Text Available This account describes our efforts to heterogenize epoxidation catalysts. Anchored and sol-gel entrapped molybdenum were shown to be very selective, but had a strongly reduced activity. On the other hand, molybdenum silicates were very active and stable as long as no diols were present in the reaction mixture. Heterogenized rhenium catalysts were less active but allowed the use of anhydrous hydrogen peroxide as oxidant. However, the high cost and difficult regeneration prevents the industrial use of these catalysts. During these investigations, we found that alumina alone is active in the epoxidation with anhydrous hydrogen peroxide, giving good conversions to epoxides with high selectivity. More research is needed in order to clarify the nature of the hydroxyl groups responsible for its catalytic activity and thus to produce an appropriate material which would allow the obtention of epoxides with high selectivity under industrial conditions.

  20. Clinical heterogeneity in Fabry disease

    Directory of Open Access Journals (Sweden)

    G. N. Salogub

    2015-01-01

    Full Text Available Fabry disease is an X-linked, lysosomal storage disease (OMIM: 301500, caused by α-galactosidase A deficiency, resulting in accumulation of its substrates, glycosphingolipids, primarily – globotriaosylceramide, in the lysosomes of multiple cell types with multi-system clinical manifestations, even within the same family, including abnormalities of the central and peripheral nervous system, kidneys, heart, gastrointestinal tract, lungs, organ of vision. Clinical heterogeneity is often the reason of the delayed diagnosis. Nowadays enzyme replacement therapy has proved its efficiency in the treatment of Fabry disease. Including Fabry disease in the differential diagnosis of a large range of disorders is important because of its wide clinical heterogeneity and the possibility of an earlier intervention with a beneficial treatment.

  1. Heterogeneous Workers, Trade, and Migration

    OpenAIRE

    Heiland, Inga; Kohler, Wilhelm

    2013-01-01

    We argue that the narrative of variety-induced gains from trade in differentiated goods needs revision. If producing differentiated varieties of a good requires differentiated skills and if the work force is heterogeneous in these skills, then firms are likely to have monopsony power. We show that trade then has adverse labor market effects: It increases the monopsony power of firms and worsens the average quality of matches between firms and workers. We also show that international migration...

  2. Genetic heterogeneity of Meckel syndrome.

    OpenAIRE

    Roume, J; Ma, H W; Le Merrer, M; Cormier-Daire, V; Girlich, D; Genin, E.; Munnich, A

    1997-01-01

    Meckel syndrome (MKS) is a lethal, autosomal recessive condition characterised by an occipital meningoencephalocele, enlarged kidneys with multicystic dysplasia, fibrotic changes of the liver in the portal area with ductal proliferation, and postaxial polydactyly. Recently, a MKS gene has been mapped to chromosome 17q21-q24 in Finnish families, with no evidence of locus heterogeneity in this population. Here, we report the exclusion of chromosome 17q21-q24 in eight typical MKS families of Nor...

  3. Surface fluxes in heterogeneous landscape

    Energy Technology Data Exchange (ETDEWEB)

    Bay Hasager, C.

    1997-01-01

    The surface fluxes in homogeneous landscapes are calculated by similarity scaling principles. The methodology is well establish. In heterogeneous landscapes with spatial changes in the micro scale range, i e from 100 m to 10 km, advective effects are significant. The present work focus on these effects in an agricultural countryside typical for the midlatitudes. Meteorological and satellite data from a highly heterogeneous landscape in the Rhine Valley, Germany was collected in the large-scale field experiment TRACT (Transport of pollutants over complex terrain) in 1992. Classified satellite images, Landsat TM and ERS SAR, are used as basis for roughness maps. The roughnesses were measured at meteorological masts in the various cover classes and assigned pixel by pixel to the images. The roughness maps are aggregated, i e spatially averaged, into so-called effective roughness lengths. This calculation is performed by a micro scale aggregation model. The model solves the linearized atmospheric flow equations by a numerical (Fast Fourier Transform) method. This model also calculate maps of friction velocity and momentum flux pixel wise in heterogeneous landscapes. It is indicated how the aggregation methodology can be used to calculate the heat fluxes based on the relevant satellite data i e temperature and soil moisture information. (au) 10 tabs., 49 ills., 223 refs.

  4. NASA GSFC Perspective on Heterogeneous Processing

    Science.gov (United States)

    Powell, Wesley A.

    2016-01-01

    This presentation provides an overview of NASA GSFC, our onboard processing applications, the applicability heterogeneous processing to these applications, and necessary developments to enable heterogeneous processing to be infused into our missions.

  5. Heterogeneity in the multiple myeloma tumor clone

    NARCIS (Netherlands)

    Guikema, Jeroen E. J.; Hovenga, Sjoerd; Vellenga, Edo; Bos, Nicolaas A.

    2004-01-01

    Multiple Myeloma (MM) is a plasma cell malignancy which is characterized by a very heterogeneous disease outcome. Heterogeneity in plasma cell characteristics, including morphology, maturation status, immunophenotype and genetic abnormalities partly account for the variable disease outcome. Although

  6. Heterogeneous fragmentation of metallic liquid microsheet with high velocity gradient

    Science.gov (United States)

    An-Min, He; Pei, Wang; Jian-Li, Shao

    2016-01-01

    Large-scale molecular dynamics simulations are performed to study the fragmentation of metallic liquid sheets with high velocity gradient. Dynamic fragmentation of the system involves the formation of a network of fragments due to the growth and coalescence of holes, decomposition of the network into filaments, and further breakup of the filaments into spherical clusters. The final size distribution of the fragmented clusters in the large volume limit is found to obey a bilinear exponential form, which is resulted from the heterogeneous breakup of quasi-cylindrical filaments. The main factors contributing to fragmentation heterogeneity are introduced, including strain rate inhomogeneity and matter distribution nonuniformity of fragments produced during decomposition of the network structure. Project supported by the Science and Technology Development Foundation of China Academy of Engineering Physics (Grant Nos. 2013A0201010 and 2015B0201039) and the National Natural Science Foundation of China (Grant No. 11402032).

  7. Heterogeneous phase fibrinolysis rates by damped oscillation rheometry.

    Science.gov (United States)

    Lee, Jae-Suk; Kaibara, Makoto; O'Rear, Edgar A

    2016-07-29

    Devices gauging viscoelastic properties of blood during coagulation like the thromboelastograph support fundamental research as well as point of care needs. Associated fibrinolysis data are based on endogenous species or plasminogen activator added to a homogeneous sample prior to clot formation. Digestion in a monolithic structure differs from the physical situation of thrombolytic therapy where surface reactions dominate. This study aims to develop rheological testing for heterogeneous phase fibrinolysis. Fibrinolysis rates were determined by phase change of a solid clot induced by autologous plasma/streptokinase (SK) in a rheometer sensitive to viscous damping. Initial slope or overall change in the logarithmic damping factor indicated fibrinolytic rates. Rates depended on clot geometry, phase volumes, clot composition and SK concentration. The damped oscillation rheometer can be adapted to determine relative rates of heterogeneous fibrinolysis in vitro.

  8. Implications of heterogeneous distributions of organisms on ballast water sampling.

    Science.gov (United States)

    Costa, Eliardo G; Lopes, Rubens M; Singer, Julio M

    2015-02-15

    Ballast water sampling is one of the problems still needing investigation in order to enforce the D-2 Regulation of the International Convention for the Control and Management of Ship Ballast Water and Sediments. Although statistical "representativeness" of the sample is an issue usually discussed in the literature, neither a definition nor a clear description of its implications are presented. In this context, we relate it to the heterogeneity of the distribution of organisms in ballast water and show how to specify compliance tests under different models based on the Poisson and negative binomial distributions. We provide algorithms to obtain minimum sample volumes required to satisfy fixed limits on the probabilities of Type I and II errors. We show that when the sample consists of a large number of aliquots, the Poisson model may be employed even under moderate heterogeneity of the distribution of the organisms in the ballast water tank. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Rapid heterogeneous oxidation of organic coatings on submicron aerosols

    Science.gov (United States)

    Lim, C. Y.; Browne, E. C.; Sugrue, R. A.; Kroll, J. H.

    2017-03-01

    Laboratory studies have found that heterogeneous oxidation can affect the composition and loading of atmospheric organic aerosol particles over time scales of several days, but most studies have examined pure organic particles only. In this study, in order to probe the reactivity of organic species confined near the particle surface, the rates and products of the OH-initiated oxidation of pure squalane particles are compared to oxidation of thin coatings of squalane on ammonium sulfate particles. The squalane reaction rate constant shows a linear dependence on the organic surface area-to-volume ratio, with rate constants for coated particles up to 10 times larger than for pure particles. Changes in the carbon oxidation state and fraction of particulate carbon remaining show similar enhancements, implying that heterogeneous oxidation may exhibit a stronger effect on the loadings and properties of organic aerosol than previously estimated from laboratory studies.

  10. A method for comparing intra-tumoural radioactivity uptake heterogeneity in preclinical positron emission tomography studies

    Energy Technology Data Exchange (ETDEWEB)

    Grafström, Jonas; Ahlzén, Hanna-Stina [Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-17177 Stockholm (Sweden); Stone-Elander, Sharon [Department of Clinical Neuroscience, Karolinska Institutet, SE-17176 Stockholm (Sweden); PET Radiochemistry, Neuroradiology Department, Karolinska University Hospital, SE-17176 Stockholm (Sweden)

    2015-09-08

    Non-uniformity influences the interpretation of nuclear medicine based images and consequently their use in treatment planning and monitoring. However, no standardised method for evaluating and ranking heterogeneity exists. Here, we have developed a general algorithm that provides a ranking and a visualisation of the heterogeneity in small animal positron emission tomography (PET) images. The code of the algorithm was written using the Matrix Laboratory software (MATLAB). Parameters known to influence the heterogeneity (distances between deviating peaks, gradients and size compensations) were incorporated into the algorithm. All data matrices were mathematically constructed in the same format with the aim of maintaining overview and control. Histograms visualising the spread and frequency of contributions to the heterogeneity were also generated. The construction of the algorithm was tested using mathematically generated matrices and by varying post-processing parameters. It was subsequently applied in comparisons of radiotracer uptake in preclinical images in human head and neck carcinoma and endothelial and ovarian carcinoma xenografts. Using the developed algorithm, entire tissue volumes could be assessed and gradients could be handled in an indirect manner. Similar-sized volumes could be compared without modifying the algorithm. Analyses of the distribution of different tracers gave results that were generally in accordance with single plane preclinical images, indicating that it could appropriately handle comparisons of targeting vs. non-targeting tracers and also for different target levels. Altering the reconstruction algorithm, pixel size, tumour ROI volumes and lower cut-off limits affected the calculated heterogeneity factors in expected directions but did not reverse conclusions about which tumour was more or less heterogeneous. The algorithm constructed is an objective and potentially user-friendly tool for one-to-one comparisons of heterogeneity in

  11. Decomposition of ethnic heterogeneity on growth

    OpenAIRE

    Yamamura, Eiji

    2012-01-01

    Ethnic heterogeneity influences economic growth through various channels such as efficiency improvement, capital accumulation, and technological progress. However, it is open to discussion exactly how ethnic heterogeneity affects these channels. Hence, this paper attempts to examine the effects of heterogeneity on economic growth using data envelopment analysis. The empirical results of the estimations show that heterogeneity has a negative effect on efficiency improvements. However, heteroge...

  12. Specialization and Bet Hedging in Heterogeneous Populations

    Science.gov (United States)

    Rulands, Steffen; Jahn, David; Frey, Erwin

    2014-09-01

    Phenotypic heterogeneity is a strategy commonly used by bacteria to rapidly adapt to changing environmental conditions. Here, we study the interplay between phenotypic heterogeneity and genetic diversity in spatially extended populations. By analyzing the spatiotemporal dynamics, we show that the level of mobility and the type of competition qualitatively influence the persistence of phenotypic heterogeneity. While direct competition generally promotes persistence of phenotypic heterogeneity, specialization dominates in models with indirect competition irrespective of the degree of mobility.

  13. Forecasting the brittle failure of heterogeneous, porous geomaterials

    Science.gov (United States)

    Vasseur, Jérémie; Wadsworth, Fabian; Heap, Michael; Main, Ian; Lavallée, Yan; Dingwell, Donald

    2017-04-01

    Heterogeneity develops in magmas during ascent and is dominated by the development of crystal and importantly, bubble populations or pore-network clusters which grow, interact, localize, coalesce, outgas and resorb. Pore-scale heterogeneity is also ubiquitous in sedimentary basin fill during diagenesis. As a first step, we construct numerical simulations in 3D in which randomly generated heterogeneous and polydisperse spheres are placed in volumes and which are permitted to overlap with one another, designed to represent the random growth and interaction of bubbles in a liquid volume. We use these simulated geometries to show that statistical predictions of the inter-bubble lengthscales and evolving bubble surface area or cluster densities can be made based on fundamental percolation theory. As a second step, we take a range of well constrained random heterogeneous rock samples including sandstones, andesites, synthetic partially sintered glass bead samples, and intact glass samples and subject them to a variety of stress loading conditions at a range of temperatures until failure. We record in real time the evolution of the number of acoustic events that precede failure and show that in all scenarios, the acoustic event rate accelerates toward failure, consistent with previous findings. Applying tools designed to forecast the failure time based on these precursory signals, we constrain the absolute error on the forecast time. We find that for all sample types, the error associated with an accurate forecast of failure scales non-linearly with the lengthscale between the pore clusters in the material. Moreover, using a simple micromechanical model for the deformation of porous elastic bodies, we show that the ratio between the equilibrium sub-critical crack length emanating from the pore clusters relative to the inter-pore lengthscale, provides a scaling for the error on forecast accuracy. Thus for the first time we provide a potential quantitative correction for

  14. Heterogeneous Causal Effects and Sample Selection Bias

    DEFF Research Database (Denmark)

    Breen, Richard; Choi, Seongsoo; Holm, Anders

    2015-01-01

    causal effects might vary over individuals or groups. In this paper we point out one of the under-appreciated hazards of seeking to estimate heterogeneous causal effects: conventional selection bias (that is, selection on baseline differences) can easily be mistaken for heterogeneity of causal effects....... This might lead us to find heterogeneous effects when the true effect is homogenous, or to wrongly estimate not only the magnitude but also the sign of heterogeneous effects. We apply a test for the robustness of heterogeneous causal effects in the face of varying degrees and patterns of selection bias...

  15. Kinetics of heterogeneous catalytic reactions

    CERN Document Server

    Boudart, Michel

    2014-01-01

    This book is a critical account of the principles of the kinetics of heterogeneous catalytic reactions in the light of recent developments in surface science and catalysis science. Originally published in 1984. The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These paperback editions preserve the original texts of these important books while presenting them in durable paperback editions. The goal of the Princeton Legacy Library is to vastly increase acc

  16. Fundamental concepts in heterogeneous catalysis

    CERN Document Server

    Norskov, Jens K; Abild-Pedersen, Frank; Bligaard, Thomas

    2014-01-01

    This book is based on a graduate course and suitable as a primer for any newcomer to the field, this book is a detailed introduction to the experimental and computational methods that are used to study how solid surfaces act as catalysts.   Features include:First comprehensive description of modern theory of heterogeneous catalysisBasis for understanding and designing experiments in the field   Allows reader to understand catalyst design principlesIntroduction to important elements of energy transformation technologyTest driven at Stanford University over several semesters

  17. A Heterogeneous Medium Analytical Benchmark

    Energy Technology Data Exchange (ETDEWEB)

    Ganapol, B.D.

    1999-09-27

    A benchmark, called benchmark BLUE, has been developed for one-group neutral particle (neutron or photon) transport in a one-dimensional sub-critical heterogeneous plane parallel medium with surface illumination. General anisotropic scattering is accommodated through the Green's Function Method (GFM). Numerical Fourier transform inversion is used to generate the required Green's functions which are kernels to coupled integral equations that give the exiting angular fluxes. The interior scalar flux is then obtained through quadrature. A compound iterative procedure for quadrature order and slab surface source convergence provides highly accurate benchmark qualities (4- to 5- places of accuracy) results.

  18. Heterogeneity in magnetic complex oxides

    Science.gov (United States)

    Arenholz, Elke

    Heterogeneity of quantum materials on the nanoscale can result from the spontaneous formation of regions with distinct atomic, electronic and/or magnetic order, and indicates coexistence of competing quantum phases. In complex oxides, the subtle interplay of lattice, charge, orbital, and spin degrees of freedom gives rise to especially rich phase diagrams. For example, coexisting conducting and insulating phases can occur near metal-insulator transitions, colossal magnetoresistance can emerge where ferromagnetic and antiferromagnetic domains compete, and charge-ordered and superconducting regions are present simultaneously in materials exhibiting high-temperature superconductivity. Additionally, externally applied fields (electric, magnetic, or strain) or other external excitations (light or heat) can tip the energy balance towards one phase, or support heterogeneity and phase coexistence and provide the means to perturb and tailor quantum heterogeneity at the nanoscale. Engineering nanomaterials, with structural, electronic and magnetic characteristics beyond what is found in bulk materials, is possible today through the technique of thin film epitaxy, effectively a method of `spray painting' atoms on single crystalline substrates to create precisely customized layered structures with atomic arrangements defined by the underlying substrate. Charge transfer and spin polarization across interfaces as well as imprinting nanoscale heterogeneity between adjacent layers lead to intriguing and important new phenomena testing our understanding of basic physics and creating new functionalities. Moreover, the abrupt change of orientation of an order parameter between nanoscale domains can lead to unique phases that are localized at domain walls, including conducting domain walls in insulating ferroelectrics, and ferromagnetic domain walls in antiferromagnets. Here we present our recent results on tailoring the electronic anisotropy of multiferroic heterostructures by

  19. Vorticity and upscaled dispersion in 3D heterogeneous porous media

    Science.gov (United States)

    Di Dato, Mariaines; Chiogna, Gabriele; de Barros, Felipe; Bellin, Alberto; Fiori, Aldo

    2015-04-01

    Modeling flow in porous media is relevant for many environmental, energy and industrial applications. From an environmental perspective, the relevance of porous media flow becomes evident in subsurface hydrology. In general, flow in natural porous media is creeping, yet the large variability in the hydraulic conductivity values encountered in natural aquifers leads to highly heterogeneous flow fields. This natural variability in the conductivity field will affect both dilution rates of chemical species and reactive mixing. A physical consequence of this heterogeneity is also the presence of a various localized kinematical features such as straining, shearing and vorticity in aquifers, which will influence the shape of solute clouds and its fate and transport. This work aims in fundamentally characterizing the vorticity field in spatially heterogeneous flow fields as a function of their statistical properties in order to analyze the impact on transport processes. In our study, three-dimensional porous formations are constructed with an ensemble of N independent, non-overlapping spheroidal inclusions submerged into an homogeneous matrix, of conductivity K0. The inclusions are randomly located in a domain of volume W and are fully characterized by the geometry of spheroid (oblate or prolate), their conductivity K (random and drawn from a given probability density function fκ), the centroid location ¯x, the axes ratio e, the orientation of the rotational axis (α1,α2) and the volume w. Under the assumption of diluted medium, the flow problem is solved analitically by means of only two parameters: the conductivity contrast κ = K/K0 and the volume fraction n = Nw/W . Through the variation of these parameters of the problem, it is possible to approximate the structure of natural heterogeneous porous media. Using a random distribution of the orientation of the inclusions, we create media defined by the same global anisotropy f = Iz/Ix but different micro

  20. Immunophenotype Heterogeneity in Nasal Glomangiopericytoma

    Directory of Open Access Journals (Sweden)

    Adriana Handra-Luca

    2015-01-01

    Full Text Available Nasal glomangiopericytoma is rare. The immunophenotype is heterogeneous, more frequently smooth-muscle-actin and CD34-positive. We report expression patterns for several vascular-related proteins such as CD99, CD146, Bcl2, and WT1 as well as for treatment-related proteins such as mTOR and EGFR in a nasal glomangiopericytoma. The patient (woman, 86 years presented with a left nasal tumefaction. The resected specimen (1.5-cm showed a glomangiopericytoma. Tumor cells expressed smooth-muscle-actin, CD31, CD34, and progesterone receptor. They also expressed the vascular-cell-related proteins Bcl2, CD99, CD146, and WT1, as well as mTOR and EGFR. Nasal glomangiopericytomas show immunohistochemical heterogeneity for vascular-related markers, suggesting a possible extensive pericytic differentiation. The expression of potential targets for drug treatments such as mTOR and EGFR may impact on the clinical follow-up of these tumors occurring at advanced ages, which may require complex surgery.

  1. Sequence heterogeneity in Parkinsonian speech.

    Science.gov (United States)

    Ho, A K; Bradshaw, J L; Cunnington, R; Phillips, J G; Iansek, R

    1998-08-01

    Parkinson's disease (PD) is a neurodegenerative movement disorder primarily due to basal ganglia dysfunction. While much research has been conducted on Parkinsonian deficits in the traditional arena of musculoskeletal limb movement, research in other functional motor tasks is lacking. The present study examined articulation in PD with increasingly complex sequences of articulatory movement. Of interest was whether dysfunction would affect articulation in the same manner as in limb-movement impairment. In particular, since very similar (homogeneous) articulatory sequences (the tongue twister effect) are more difficult for healthy individuals to achieve than dissimilar (heterogeneous) gestures, while the reverse may apply for skeletal movements in PD, we asked which factor would dominate when PD patients articulated various grades of artificial tongue twisters: the influence of disease or a possible difference between the two motor systems. Execution was especially impaired when articulation involved a sequence of motor program heterogeneous in terms of place of articulation. The results are suggestive of a hypokinesic tendency in complex sequential articulatory movement as in limb movement. It appears that PD patients do show abnormalities in articulatory movement which are similar to those of the musculoskeletal system. The present study suggests that an underlying disease effect modulates movement impairment across different functional motor systems. Copyright 1998 Academic Press.

  2. Heterogeneous Glasses and Sustainable Cement

    Science.gov (United States)

    Del Gado, Emanuela

    2015-03-01

    Calcium-silicate hydrate (C-S-H) is the main binding agent in cement and concrete. It forms at the beginning of cement hydration, it progressively densifies as cement hardens and is ultimately responsible for the performances of concrete. This hydration product is a cohesive nano-scale heterogeneous glass, whose structure and mechanics are still poorly understood, in spite of its practical importance. I will review some of the open questions for this fascinating material and discuss a statistical physics approach recently developed, which allows us to investigate the structural arrest and solidification under the out-of-equilibrium conditions typical of cement hydration and the role of the nano-scale structure in C-S-H mechanics upon hardening. Our approach unveils how some distinctive features of the kinetics of cement hydration can be related to changes in the morphology of this glassy material and elucidates the role of nano-scale mechanical heterogeneities in the hardened C-S-H.

  3. Socially Aware Heterogeneous Wireless Networks.

    Science.gov (United States)

    Kosmides, Pavlos; Adamopoulou, Evgenia; Demestichas, Konstantinos; Theologou, Michael; Anagnostou, Miltiades; Rouskas, Angelos

    2015-06-11

    The development of smart cities has been the epicentre of many researchers' efforts during the past decade. One of the key requirements for smart city networks is mobility and this is the reason stable, reliable and high-quality wireless communications are needed in order to connect people and devices. Most research efforts so far, have used different kinds of wireless and sensor networks, making interoperability rather difficult to accomplish in smart cities. One common solution proposed in the recent literature is the use of software defined networks (SDNs), in order to enhance interoperability among the various heterogeneous wireless networks. In addition, SDNs can take advantage of the data retrieved from available sensors and use them as part of the intelligent decision making process contacted during the resource allocation procedure. In this paper, we propose an architecture combining heterogeneous wireless networks with social networks using SDNs. Specifically, we exploit the information retrieved from location based social networks regarding users' locations and we attempt to predict areas that will be crowded by using specially-designed machine learning techniques. By recognizing possible crowded areas, we can provide mobile operators with recommendations about areas requiring datacell activation or deactivation.

  4. Dynamic heterogeneity and life histories.

    Science.gov (United States)

    Tuljapurkar, Shripad; Steiner, Ulrich K

    2010-08-01

    Biodemography is increasingly focused on the large and persistent differences between individuals within populations in fitness components (age at death, reproductive success) and fitness-related components (health, biomarkers) in humans and other species. To study such variation we propose the use of dynamic models of observable phenotypes of individuals. Phenotypic change in turn determines variation among individuals in their fitness components over the life course. We refer to this dynamic accumulation of fitness differences as dynamic heterogeneity and illustrate it for an animal population in which longitudinal data are studied using multistate capture-mark-recapture models. Although our approach can be applied to any characteristic, for our empirical example we use reproduction as the phenotypic character to define stages. We indicate how our stage-structured model describes the nature of the variation among individual characteristics that is generated by dynamic heterogeneity. We conclude by discussing our ongoing and planned work on animals and humans. We also discuss the connections between our work and recent work on human mortality, disability and health, and life course theory.

  5. Modeling and simulation of diffusion-convection-reaction in heterogeneous nanochannels using OpenFOAM

    NARCIS (Netherlands)

    Pimpalgaonkar, H.G.; van Steijn, V.; Kreutzer, M.T.; Kleijn, C.R.; Simos, Theodore; Tsitouras, Charalambos

    2016-01-01

    We present a finite volume implementation of a phase field method in OpenFOAM as a tool to simulate reactive multiphase flows on heterogeneous surfaces. Using this tool, we simulate the formation and growth of a droplet due to a chemical reaction on a hydrophilic catalytic patch surrounded by a

  6. A heterogeneous catalyst, SiO₂-ZnBr₂: An efficient neat access for ...

    Indian Academy of Sciences (India)

    ... Volume 128; Issue 8. A heterogeneous catalyst, SiO₂-ZnBr₂: An efficient neat access for α-aminophosphonates and antimicrobial activity evaluation ... The catalyst, SiO₂-ZnBr₂ afforded good yields of products in all the methods in the range of 85–97% but variation was observed in reaction time. Microwave irradiation ...

  7. Heterogeneous trade agreements, WTO membership and international trade : an analysis using matching econometrics

    NARCIS (Netherlands)

    Kohl, Tristan; Trojanowska, Sofia

    2015-01-01

    This article explores the heterogeneous effects of trade agreements (TAs) and World Trade Organization (WTO) membership on the volume of international trade. We extend Baier and Bergstrand’s (2009a) application of matching econometrics by distinguishing between different types of TAs and WTO

  8. Leakage of CO2 from sub-seafloor CO2 storage sites to the seabed; Impacts on sediment microorganisms and geochemical parameters during in situ and laboratory leakage experiments

    Science.gov (United States)

    Reigstad, L. J.; Hannisdal, B.; Hoffmann, F. U.; Sweetman, A. K.; Baumberger, T.; Eickmann, B.; Røy, H.; Thorseth, I. H.; Pedersen, R. B.

    2013-12-01

    detected on all three levels in all depths investigated, but the response to acidification appeared among less-abundant prokaryotic groups in the sediment, rather than the numerically dominant groups. Quantification of the 16S rRNA genes (DNA level) indicated no increase in cell numbers in response to the treatment. However, an increase in the in situ microbial sulfate reduction rates and/or expression of marker genes for sulfate reduction (RNA level) was discovered. Analyses of marker gene expression for other prokaryotic metabolisms will be presented as well as correlations between specific organisms and geochemical parameters. Within the limitations of the experimental set up, our studies indicate that a leakage of CO2 from a sub-seafloor storage site may not dramatically change the composition of the active microbial community in the seabed sediment though we did register activity changes in some metabolisms.

  9. Effect of methacholine on peripheral lung mechanics and ventilation heterogeneity in asthma.

    Science.gov (United States)

    Downie, Sue R; Salome, Cheryl M; Verbanck, Sylvia; Thompson, Bruce R; Berend, Norbert; King, Gregory G

    2013-03-15

    The forced oscillation technique (FOT) and multiple-breath nitrogen washout (MBNW) are noninvasive tests that are potentially sensitive to peripheral airways, with MBNW indexes being especially sensitive to heterogeneous changes in ventilation. The objective was to study methacholine-induced changes in the lung periphery of asthmatic patients and determine how changes in FOT variables of respiratory system reactance (Xrs) and resistance (Rrs) and frequency dependence of resistance (Rrs5-Rrs19) can be linked to changes in ventilation heterogeneity. The contributions of air trapping and airway closure, as extreme forms of heterogeneity, were also investigated. Xrs5, Rrs5, Rrs19, Rrs5-Rrs19, and inspiratory capacity (IC) were calculated from the FOT. Ventilation heterogeneity in acinar and conducting airways, and trapped gas (percent volume of trapped gas at functional residual capacity/vital capacity), were calculated from the MBNW. Measurements were repeated following methacholine. Methacholine-induced airway closure (percent change in forced vital capacity) and hyperinflation (change in IC) were also recorded. In 40 mild to moderate asthmatic patients, increase in Xrs5 after methacholine was predicted by increases in ventilation heterogeneity in acinar airways and forced vital capacity (r(2) = 0.37, P ventilation heterogeneity in conducting airway increase or IC decrease. Increases in Rrs5 and Rrs5-Rrs19 after methacholine were not correlated with increases in ventilation heterogeneity, trapped gas, hyperinflation, or airway closure. Increased reactance in asthmatic patients after methacholine was indicative of heterogeneous changes in the lung periphery and airway closure. By contrast, increases in resistance and frequency dependence of resistance were not related to ventilation heterogeneity or airway closure and were more indicative of changes in central airway caliber than of heterogeneity.

  10. Intertumoral Heterogeneity within Medulloblastoma Subgroups.

    Science.gov (United States)

    Cavalli, Florence M G; Remke, Marc; Rampasek, Ladislav; Peacock, John; Shih, David J H; Luu, Betty; Garzia, Livia; Torchia, Jonathon; Nor, Carolina; Morrissy, A Sorana; Agnihotri, Sameer; Thompson, Yuan Yao; Kuzan-Fischer, Claudia M; Farooq, Hamza; Isaev, Keren; Daniels, Craig; Cho, Byung-Kyu; Kim, Seung-Ki; Wang, Kyu-Chang; Lee, Ji Yeoun; Grajkowska, Wieslawa A; Perek-Polnik, Marta; Vasiljevic, Alexandre; Faure-Conter, Cecile; Jouvet, Anne; Giannini, Caterina; Nageswara Rao, Amulya A; Li, Kay Ka Wai; Ng, Ho-Keung; Eberhart, Charles G; Pollack, Ian F; Hamilton, Ronald L; Gillespie, G Yancey; Olson, James M; Leary, Sarah; Weiss, William A; Lach, Boleslaw; Chambless, Lola B; Thompson, Reid C; Cooper, Michael K; Vibhakar, Rajeev; Hauser, Peter; van Veelen, Marie-Lise C; Kros, Johan M; French, Pim J; Ra, Young Shin; Kumabe, Toshihiro; López-Aguilar, Enrique; Zitterbart, Karel; Sterba, Jaroslav; Finocchiaro, Gaetano; Massimino, Maura; Van Meir, Erwin G; Osuka, Satoru; Shofuda, Tomoko; Klekner, Almos; Zollo, Massimo; Leonard, Jeffrey R; Rubin, Joshua B; Jabado, Nada; Albrecht, Steffen; Mora, Jaume; Van Meter, Timothy E; Jung, Shin; Moore, Andrew S; Hallahan, Andrew R; Chan, Jennifer A; Tirapelli, Daniela P C; Carlotti, Carlos G; Fouladi, Maryam; Pimentel, José; Faria, Claudia C; Saad, Ali G; Massimi, Luca; Liau, Linda M; Wheeler, Helen; Nakamura, Hideo; Elbabaa, Samer K; Perezpeña-Diazconti, Mario; Chico Ponce de León, Fernando; Robinson, Shenandoah; Zapotocky, Michal; Lassaletta, Alvaro; Huang, Annie; Hawkins, Cynthia E; Tabori, Uri; Bouffet, Eric; Bartels, Ute; Dirks, Peter B; Rutka, James T; Bader, Gary D; Reimand, Jüri; Goldenberg, Anna; Ramaswamy, Vijay; Taylor, Michael D

    2017-06-12

    While molecular subgrouping has revolutionized medulloblastoma classification, the extent of heterogeneity within subgroups is unknown. Similarity network fusion (SNF) applied to genome-wide DNA methylation and gene expression data across 763 primary samples identifies very homogeneous clusters of patients, supporting the presence of medulloblastoma subtypes. After integration of somatic copy-number alterations, and clinical features specific to each cluster, we identify 12 different subtypes of medulloblastoma. Integrative analysis using SNF further delineates group 3 from group 4 medulloblastoma, which is not as readily apparent through analyses of individual data types. Two clear subtypes of infants with Sonic Hedgehog medulloblastoma with disparate outcomes and biology are identified. Medulloblastoma subtypes identified through integrative clustering have important implications for stratification of future clinical trials. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Operando research in heterogeneous catalysis

    CERN Document Server

    Groot, Irene

    2017-01-01

    This book is devoted to the emerging field of techniques for visualizing atomic-scale properties of active catalysts under actual working conditions, i.e. high gas pressures and high temperatures. It explains how to understand these observations in terms of the surface structures and dynamics and their detailed interplay with the gas phase. This provides an important new link between fundamental surface physics and chemistry, and applied catalysis. The book explains the motivation and the necessity of operando studies, and positions these with respect to the more traditional low-pressure investigations on the one hand and the reality of industrial catalysis on the other. The last decade has witnessed a rapid development of new experimental and theoretical tools for operando studies of heterogeneous catalysis. The book has a strong emphasis on the new techniques and illustrates how the challenges introduced by the harsh, operando conditions are faced for each of these new tools. Therefore, one can also read th...

  12. Genetic heterogeneity of multiple exostoses

    Energy Technology Data Exchange (ETDEWEB)

    Legeai-Mallet, L.; Munnich, A.; Le Merrer, M. [Inserm U393 Hopital des Enfants-Malades, Paris (France)] [and others

    1994-09-01

    Hereditary multiple exostoses (EXT, MIM 133700) is an autosomal dominant bony disorder characterized by the formation of cartilage-capped juxta-epiphyseal prominences on the long bones. Three disease genes, mapping to chromosomes 8q24 and 11 have been recently localized, supporting genetic heterogeneity of this condition. We have refined the genetic mapping of the chromosome 19p locus using a series of six families unlinked to chromosomes 8 or 11. Several genes expressed during cartilage growth and located in this region have been tested as candidate genes, namely zinc finger proteins, protein kinases, JunD and JunB. Hitherto no major rearrangement of these genes has been detected in EXT families linked to chromosome 19p.

  13. Genetic heterogeneity of hepatocellular carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Unsal, H.; Isselbacher, K.J. (Massachusetts General Hospital Cancer Center, Charlestown, MA (United States)); Yakicier, C.; Marcais, C.; Ozturk, M. (Institut National de la Sante et de la Recherche Medicale, Lyon (France)); Kew, M. (Univ. of Witwatersrand, Johannesburg (South Africa)); Volkmann, M. (Univ. of Heidelberg (Germany)); Zentgraf, H. (Deutsches Krebsforschungszentrum, Heidelberg (Germany))

    1994-01-18

    The authors studied 80 hepatocellular carcinomas from three continents for p53 gene (TP53) mutations and hepatitis B virus (HBV) sequences. p53 mutations were frequent in tumors from Mozambique but not in tumors from South Africa, China, and Germany. Independent of geographic origin, most tumors were positive for HBV sequences. X gene coding sequences of HBV were detected in 78% of tumors, whereas viral sequences in the surface antigen- and core antigen-encoding regions were present in less than 35% of tumors. These observations indicate that hepatocellular carcinomas are genetically heterogeneous. Mozambican-types of hepatocellular carcinomas are characterized by a high incidence of p53 mutations related to aflatoxins. In other tumors, the rarity of p53 mutations combined with the frequent presence of viral X gene coding sequences suggests a possible interference of HBV with the wild-type p53 function.

  14. Magnetically assisted slip casting of bioinspired heterogeneous composites

    Science.gov (United States)

    Le Ferrand, Hortense; Bouville, Florian; Niebel, Tobias P.; Studart, André R.

    2015-11-01

    Natural composites are often heterogeneous to fulfil functional demands. Manufacturing analogous materials remains difficult, however, owing to the lack of adequate and easily accessible processing tools. Here, we report an additive manufacturing platform able to fabricate complex-shaped parts exhibiting bioinspired heterogeneous microstructures with locally tunable texture, composition and properties, as well as unprecedentedly high volume fractions of inorganic phase (up to 100%). The technology combines an aqueous-based slip-casting process with magnetically directed particle assembly to create programmed microstructural designs using anisotropic stiff platelets in a ceramic, metal or polymer functional matrix. Using quantitative tools to control the casting kinetics and the temporal pattern of the applied magnetic fields, we demonstrate that this approach is robust and can be exploited to design and fabricate heterogeneous composites with thus far inaccessible microstructures. Proof-of-concept examples include bulk composites with periodic patterns of microreinforcement orientation, and tooth-like bilayer parts with intricate shapes exhibiting site-specific composition and texture.

  15. Cohesive fracture of elastically heterogeneous materials: An integrative modeling and experimental study

    Science.gov (United States)

    Wang, Neng; Xia, Shuman

    2017-01-01

    A combined modeling and experimental effort is made in this work to examine the cohesive fracture mechanisms of heterogeneous elastic solids. A two-phase laminated composite, which mimics the key microstructural features of many tough engineering and biological materials, is selected as a model material system. Theoretical and finite element analyses with cohesive zone modeling are performed to study the effective fracture resistance of the heterogeneous material associated with unstable crack propagation and arrest. A crack-tip-position controlled algorithm is implemented in the finite element analysis to overcome the inherent instability issues resulting from crack pinning and depinning at local heterogeneities. Systematic parametric studies are carried out to investigate the effects of various material and geometrical parameters, including the modulus mismatch ratio, phase volume fraction, cohesive zone size, and cohesive law shape. Concurrently, a novel stereolithography-based three-dimensional (3D) printing system is developed and used for fabricating heterogeneous test specimens with well-controlled structural and material properties. Fracture testing of the specimens is performed using the tapered double-cantilever beam (TDCB) test method. With optimal material and geometrical parameters, heterogeneous TDCB specimens are shown to exhibit enhanced effective fracture energy and effective fracture toughness than their homogeneous counterparts, which is in good agreement with the modeling predictions. The integrative computational and experimental study presented here provides a fundamental mechanistic understanding of the fracture mechanisms in brittle heterogeneous materials and sheds light on the rational design of tough materials through patterned heterogeneities.

  16. Peripheral ventilation heterogeneity determines the extent of bronchoconstriction in asthma.

    Science.gov (United States)

    Farrow, Catherine E; Salome, Cheryl M; Harris, Benjamin E; Bailey, Dale L; Berend, Norbert; King, Gregory G

    2017-11-01

    In asthma, bronchoconstriction causes topographically heterogeneous airway narrowing, as measured by three-dimensional ventilation imaging. Computation modeling suggests that peripheral airway dysfunction is a potential determinant of acute airway narrowing measured by imaging. We hypothesized that the development of low-ventilation regions measured topographically by three-dimensional imaging after bronchoconstriction is predicted by peripheral airway function. Fourteen asthmatic subjects underwent ventilation single-photon-emission computed tomography/computed tomography scan imaging before and after methacholine challenge. One-liter breaths of Technegas were inhaled from functional residual capacity in upright posture before supine scanning. The lung regions with the lowest ventilation (Ventlow) were calculated using a thresholding method and expressed as a percentage of total ventilation (Venttotal). Multiple-breath nitrogen washout was used to measure diffusion-dependent and convection-dependent ventilation heterogeneity (Sacin and Scond, respectively) and lung clearance index (LCI), before and after challenge. Forced expiratory volume in 1 s (FEV1) was 87.6 ± 15.8% predicted, and seven subjects had airway hyperresponsiveness. Ventlow at baseline was unrelated to spirometry or multiple-breath nitrogen washout indices. Methacholine challenge decreased FEV1 by 23 ± 5% of baseline while Ventlow increased from 21.5 ± 2.3%Venttotal to 26.3 ± 6.7%Venttotal (P = 0.03). The change in Ventlow was predicted by baseline Sacin (rs  = 0.60, P = 0.03) and by LCI (rs  = 0.70, P = 0.006) but not by Scond (rs  = 0.30, P = 0.30). The development of low-ventilation lung units in three-dimensional ventilation imaging is predicted by ventilation heterogeneity in diffusion-dependent airways. This relationship suggests that acinar ventilation heterogeneity in asthma may be of mechanistic importance in terms of bronchoconstriction and airway narrowing

  17. In-situ characterization of heterogeneous catalysts

    CERN Document Server

    Rodriguez, Jose A; Chupas, Peter J

    2013-01-01

    Helps researchers develop new catalysts for sustainable fuel and chemical production Reviewing the latest developments in the field, this book explores the in-situ characterization of heterogeneous catalysts, enabling readers to take full advantage of the sophisticated techniques used to study heterogeneous catalysts and reaction mechanisms. In using these techniques, readers can learn to improve the selectivity and the performance of catalysts and how to prepare catalysts as efficiently as possible, with minimum waste. In-situ Characterization of Heterogeneous Catalysts feat

  18. Phenotypic heterogeneity in fungi: importance and methodology

    OpenAIRE

    Hewitt, Sarah K.; Foster, David S.; Dyer, Paul S.; Avery, Simon V.

    2016-01-01

    Phenotypic heterogeneity describes the variation that exists between individual cells, spores or other biological entities within genetically-uniform populations of fungi or other organisms. Studies over the last 10–-15 years have successfully used laboratory- and modelling-based approaches to demonstrate the prevalence of phenotypic heterogeneity and characterise the molecular bases of the phenomenon (primarily centred around heterogeneous gene expression). In contrast to progress in these a...

  19. Quantifying Heterogeneity in Emphysema from High Resolution Computed Tomography: A Lung Tissue Research Consortium Study

    Science.gov (United States)

    Yilmaz, Cuneyt; Dane, Dan M.; Patel, Nova C.; Hsia, Connie C.W.

    2012-01-01

    Rationale and Objective To quantify spatial distribution of emphysema using high-resolution computed tomography (HRCT), we applied semi-automated analysis with internal attenuation calibration to measure regional air volume, tissue volume, and fractional tissue volume (FTV=tissue/[air+tissue] volume) in well-characterized patients studied by the Lung Tissue Research Consortium (LTRC). Methods HRCT was obtained at supine end-inspiration and end-expiration, and prone end-inspiration from 31 patients with mild, moderate, severe, or very severe emphysema (stages II–V, FEV1>75%, 51–75%, 21–50% and ≤20% predicted, respectively). Control data were from 20 healthy non-smokers (stage I). Each lobe was analyzed separately. Heterogeneity of FTV was assessed from coefficients of variation (CV) within and among lobes, and the kurtosis and skewness of FTV histograms. Results In emphysema, lobar air volume increased up to 177% except in the right middle lobe. Lobar tissue volume increased up to 107% in mild-moderate stages then normalized in advanced stages. Normally, FTV was up to 82% higher in lower than upper lobes. In mild-moderate emphysema, lobar FTV increased by up to 74% above normal at supine inspiration. In severe emphysema FTV declined below normal in all lobes and positions in correlation with pulmonary function (pemphysema distribution and heterogeneity from that in ILD. Early emphysema is associated with elevated tissue volume and FTV, consistent with hyperemia, inflammation or atelectasis. PMID:23122057

  20. Fixed export cost heterogeneity, trade and welfare

    DEFF Research Database (Denmark)

    Jørgensen, Jan Guldager; Schröder, Philipp J.H.

    2008-01-01

    Recent literature on the workhorse model of intra-industry trade has explored heterogeneous cost structures at the firm level. These approaches have proven to add realism and predictive power. This paper presents a new and simple heterogeneous-firms specification. We develop a symmetric two......-country intra-industry trade model where firms are of two different marginal costs types and where fixed export costs are heterogeneous across firms. This model traces many of the stylized facts of international trade. However, we find that with heterogeneous fixed export costs there exists a positive bilateral...

  1. Source-Related Chemical And Isotopic Heterogeneities In Granitoid Magmas

    Science.gov (United States)

    Helps, P. A.; Clemens, J. D.; Petford, N.

    2004-12-01

    A survey of a large number of post-orogenic plutons, shows that regional-scale, intraplutonic isotope heterogeneities (initial 87Sr/86Sr and/or eNd) are common in crustally derived granitic rocks. This is expected since the source materials, from which the granitic magmas were created by partial melting, are themselves heterogeneous, especially from metasedimentary sources. If we accept models of granite emplacement involving the rapid ascent of magma along dykes, there must be potential for the preservation of source-inherited chemical and isotopic heterogeneities. However, their preservation will depend on the extent of post-emplacement homogenisation processes, such as diffusion and convective mixing, in the magma chambers. Micro-sampling of feldspar crystals in granites has revealed complex internal Sr and Nd isotope variations thought to reveal subtle variations in the isotopic composition of the melt from which particular zones crystallised. We therefore have evidence of both macro-scale (regional) and micro-scale isotopic variation within granitic magmas. What is unknown is the extent of chemical and isotopic variation on the meso-scale. We have obtained high-precision geochemical and isotopic (Sr, Nd, and O) analyses for spatially well constrained samples, from two granitic intrusions from the UK, to study the scales over which isotope heterogeneities are preserved, and the maximum volumes of magma over which isotope and elemental homogenisation may have been achieved. These data provide important constraints on the physical and chemical characteristics of processes that occur during magma genesis, ascent, and emplacement. The Criffell pluton (SW Scotland) has previously been shown to be isotopically heterogeneous on the regional scale, with initial 87Sr/86Sr varying from 0.70521 to 0.70728, generally increasing inward, towards the centre of the pluton. This was interpreted as representing isotopic heterogeneity within the source region. Our study has

  2. Quantifying heterogeneity in emphysema from high-resolution computed tomography: a lung tissue research consortium study.

    Science.gov (United States)

    Yilmaz, Cuneyt; Dane, Dan M; Patel, Nova C; Hsia, Connie C W

    2013-02-01

    To quantify spatial distribution of emphysema using high-resolution computed tomography (HRCT), we applied semiautomated analysis with internal attenuation calibration to measure regional air volume, tissue volume, and fractional tissue volume (FTV = tissue/[air + tissue] volume) in well-characterized patients studied by the Lung Tissue Research Consortium (LTRC). HRCT was obtained at supine end-inspiration and end-expiration, and prone end-inspiration from 31 patients with mild, moderate, severe, or very severe emphysema (stages II-V, forced expiratory volume at 1 second >75%, 51%-75%, 21%-50% and ≤20% predicted, respectively). Control data were from 20 healthy non-smokers (stage I). Each lobe was analyzed separately. Heterogeneity of FTV was assessed from coefficients of variation (CV) within and among lobes, and the kurtosis and skewness of FTV histograms. In emphysema, lobar air volume increased up to 177% above normal except in the right middle lobe. Lobar tissue volume increased up to 107% in mild-moderate stages then normalized in advanced stages. Normally, FTV was up to 82% higher in lower than upper lobes. In mild-moderate emphysema, lobar FTV increased by up to 74% above normal at supine inspiration. In severe emphysema, FTV declined below normal in all lobes and positions in correlation with pulmonary function (P < .05). Markers of FTV heterogeneity increased steadily with disease stage in correlation with pulmonary function (P < .05); the pattern is distinct from that seen in interstitial lung disease (ILD). CT-derived biomarkers differentiate the spatial patterns of emphysema distribution and heterogeneity from that in ILD. Early emphysema is associated with elevated tissue volume and FTV, consistent with hyperemia, inflammation or atelectasis. Published by Elsevier Inc.

  3. Microstructure and mechanical properties of hyperuniform heterogeneous materials

    Science.gov (United States)

    Xu, Yaopengxiao; Chen, Shaohua; Chen, Pei-En; Xu, Wenxiang; Jiao, Yang

    2017-10-01

    A hyperuniform random heterogeneous material is one in which the local volume fraction fluctuations in an observation window decay faster than the reciprocal window volume as the window size increases. Recent studies show that this class of materials are endowed with superior physical properties such as large isotropic photonic band gaps and optimal transport properties. Here we employ a stochastic optimization procedure to systematically generate realizations of hyperuniform heterogeneous materials with controllable short-range order, which is partially quantified using the two-point correlation function S2(r ) associated with the phase of interest. Specifically, our procedure generalizes the widely used Yeong-Torquato reconstruction procedure by including an additional constraint for hyperuniformity, i.e., the volume integral of the autocovariance function χ (r ) =S2(r ) -ϕ2 over the whole space is zero. In addition, we only require the reconstructed S2 to match the target function up to a certain cutoff distance γ , in order to give the system sufficient degrees of freedom to satisfy the hyperuniform condition. By systematically increasing the γ value for a given S2, one can produce a spectrum of hyperuniform heterogeneous materials with varying degrees of partial short-range order compatible with the specified S2. The mechanical performance including both elastic and brittle fracture behaviors of the generated hyperuniform materials is analyzed using a volume-compensated lattice-particle method. For the purpose of comparison, the corresponding nonhyperuniform materials with the same short-range order (i.e., with S2 constrained up to the same γ value) are also constructed and their mechanical performance is analyzed. Here we consider two specific S2 including the positive exponential decay function and the correlation function associated with an equilibrium hard-sphere system. For the constructed systems associated with these two specific functions, we find

  4. Heterogeneous Nucleation and Growth of Nanoparticles at Environmental Interfaces.

    Science.gov (United States)

    Jun, Young-Shin; Kim, Doyoon; Neil, Chelsea W

    2016-09-20

    water chemistry and substrate identity on heterogeneously and homogeneously formed nanoscale precipitate size dimensions and total particle volume. Using this technique, we also provided a new platform for quantitatively comparing between heterogeneous and homogeneous nucleation and growth of nanoparticles and obtaining undiscovered interfacial energies between nuclei and surfaces. In addition, nanoscale surface characterization tools, such as in situ atomic force microscopy (AFM), were utilized to support and complement our findings. With these powerful nanoscale tools, we systematically evaluated the influences of environmentally abundant (oxy)anions and cations and the properties of environmental surfaces, such as surface charge and hydrophobicity. The findings, significantly enhanced by in situ observations, can lead to a more accurate prediction of the behaviors of nanoparticles in the environment and enable better control of the physicochemical properties of nanoparticles in engineered systems, such as catalytic reactions and energy storage.

  5. Finite volume hydromechanical simulation in porous media.

    Science.gov (United States)

    Nordbotten, Jan Martin

    2014-05-01

    Cell-centered finite volume methods are prevailing in numerical simulation of flow in porous media. However, due to the lack of cell-centered finite volume methods for mechanics, coupled flow and deformation is usually treated either by coupled finite-volume-finite element discretizations, or within a finite element setting. The former approach is unfavorable as it introduces two separate grid structures, while the latter approach loses the advantages of finite volume methods for the flow equation. Recently, we proposed a cell-centered finite volume method for elasticity. Herein, we explore the applicability of this novel method to provide a compatible finite volume discretization for coupled hydromechanic flows in porous media. We detail in particular the issue of coupling terms, and show how this is naturally handled. Furthermore, we observe how the cell-centered finite volume framework naturally allows for modeling fractured and fracturing porous media through internal boundary conditions. We support the discussion with a set of numerical examples: the convergence properties of the coupled scheme are first investigated; second, we illustrate the practical applicability of the method both for fractured and heterogeneous media.

  6. HER2 genetic heterogeneity in breast carcinoma.

    Science.gov (United States)

    Ohlschlegel, Christian; Zahel, Katharina; Kradolfer, Doris; Hell, Margreth; Jochum, Wolfram

    2011-12-01

    To determine the frequency of HER2 genetic heterogeneity according to the recent American Society of Clinical Oncology (ASCO) and College of American Pathologists (CAP) definition (2009) in invasive breast carcinoma, and to identify clinicopathological features that characterise breast carcinomas with HER2 genetic heterogeneity. 530 invasive breast carcinomas were retrospectively analysed for HER2 genetic heterogeneity, and investigated for a potential association of HER2 genetic heterogeneity with other HER2 FISH findings, clinicopathological parameters, oestrogen/progesterone receptor expression and DNA cytometric parameters in breast carcinomas with an equivocal (2+) HER2 immunohistochemical score. The overall frequency of HER2 genetic heterogeneity was 14.7% in a cohort of 218 consecutive breast carcinomas. HER2 genetic heterogeneity was most frequent in invasive breast carcinomas with an equivocal (2+) HER2 immunohistochemical score. Among the 151 carcinomas lacking HER2 amplification, 16.1% showed HER2 genetic heterogeneity. In an extended cohort of 345 carcinomas with a (2+) HER2 score, the frequency of HER2 genetic heterogeneity was 41%, and was associated with the absence of HER2 gene clusters, chromosome 17 polysomy, histological tumour grade, DNA ploidy category and 5c exceeding rate. HER2 genetic heterogeneity according to the ASCO/CAP definition is frequent in breast carcinoma, and is most often present in carcinomas with an equivocal (2+) HER2 score. Many carcinomas with HER2 genetic heterogeneity have a negative HER2 amplification status, although they contain a significant number of tumour cells with HER2 gene amplification. Single cell scoring of the HER2/17 centromeric probe (CEP17) ratio is necessary to identify carcinomas with HER2 genetic heterogeneity, because they lack specific clinicopathological characteristics.

  7. Genetic heterogeneity in juvenile NCL

    Energy Technology Data Exchange (ETDEWEB)

    Hart, Y.M.; Andermann, E.; Mitchison, H.M. [Montreal Neurological Institute and Hospital, Quebec (Canada)] [and others

    1994-09-01

    The neuronal ceroid lipofuscinoses (NCL) are a group of related lysosomal storage diseases classified according to the age of onset, clinical syndrome, and pathology. The clinical syndromes include myoclonus, visual failure, progressive dementia, ataxia and generalized tonic clonic seizures in varying combinations depending on the age of onset and pathology. The mode of inheritance is autosomal recessive in most cases, except for several families with the adult form (Kufs` disease) which have autosomal dominant inheritance. Linkage for the infantile (Halatia-Santavuori) form (CLN1), characterized ultrastructurally by lysosomal granular osmiophilic deposits (GROD), has been demonstrated with markers on chromosome lp, while the gene for the typical juvenile (Spielmeyer-Vogt) form (CLN3), characterized by fingerprint-profile inclusions, has been linked to chromosome 16p. The gene locations of the late infantile (Jansky-Bielschowsky) and adult (Kufs` disease) forms are unknown, although it has recently been shown that the late infantile form does not link to chromosome 16p. We describe three siblings, including a pair of monozygotic twins, with juvenile onset NCL with GROD in whom linkage to the CLN3 region of chromsome 16p has been excluded. This would suggest that there is genetic heterogeneity not only among the different clinical syndromes, but also among identical clinical syndromes with different ultrastructural characteristics. Preliminary studies of linkage to chromosome 1p employing the microsatellite marker HY-TM1 have been uninformative. Further studies with other chromosome 1 markers are underway.

  8. An estimating function approach to linkage heterogeneity

    Indian Academy of Sciences (India)

    Testing linkage heterogeneity between two loci is an important issue in genetics. Currently, there are four methods (K-test, A-test, B-test and D-test) for testing linkage heterogeneity in linkage analysis, which are based on the likelihood-ratio test. Among them, the commonly used methods are the K-test and A-test.

  9. Monetary policy, banking and heterogeneous agents

    NARCIS (Netherlands)

    Wolski, M.

    2012-01-01

    The influence of heterogeneous expectations on monetary policy performance has gained a lot of attention in the recent years. It proved to be an important factor that, under some circumstances, may even destabilize the economy (Massaro, 2012). This paper investigates the phenomenon of heterogeneous

  10. Hybrid Interconnect Design for Heterogeneous Hardware Accelerators

    NARCIS (Netherlands)

    Pham-Quoc Cuong, P.

    2015-01-01

    Heterogeneous multicore systems are becoming increasingly important as the need for computation power grows, especially when we are entering into the big data era. As one of the main trends in heterogeneous multicore, hardware accelerator systems provide application specific hardware circuits and

  11. Heterogeneity of Human Capital and the Return

    DEFF Research Database (Denmark)

    Madsen, Erik Strøjer

    2014-01-01

    . However, the quality of education varies a lot across universities and business schools as well as across student within an education institution. The high variations in grades among students reflect the heterogeneity in human capital among students and this study verify how this heterogeneity...

  12. Functional Heterogeneity and Senior Management Team Effectiveness

    Science.gov (United States)

    Benoliel, Pascale; Somech, Anit

    2016-01-01

    Purpose: There has been an increasing trend toward the creation of senior management teams (SMTs) which are characterized by a high degree of functional heterogeneity. Although such teams may create better linkages to information, along with the benefits of functional heterogeneity comes the potential for conflicts that stem from the value…

  13. Understanding the Executive Functioning Heterogeneity in Schizophrenia

    Science.gov (United States)

    Raffard, Stephane; Bayard, Sophie

    2012-01-01

    Schizophrenia is characterized by heterogeneous brain abnormalities involving cerebral regions implied in the executive functioning. The dysexecutive syndrome is one of the most prominent and functionally cognitive features of schizophrenia. Nevertheless, it is not clear to what extend executive deficits are heterogeneous in schizophrenia…

  14. Styles in Heterogeneous Modelling With UML

    NARCIS (Netherlands)

    Bujorianu, M.C.; Bujorianu, L.M.

    2008-01-01

    Software development is becoming increasingly heterogeneous, and therefore the formal approaches to heterogeneity are geting very important but, unacceptable extremely complex. We propose a type theoretic approach based on the concept of style, as an attempt to simplify the complex interaction of

  15. Surface temperature excess in heterogeneous catalysis

    NARCIS (Netherlands)

    Zhu, L.

    2005-01-01

    In this dissertation we study the surface temperature excess in heterogeneous catalysis. For heterogeneous reactions, such as gas-solid catalytic reactions, the reactions take place at the interfaces between the two phases: the gas and the solid catalyst. Large amount of reaction heats are released

  16. Towards an Organizational Economics of Heterogeneous Capabilities

    DEFF Research Database (Denmark)

    Foss, Nicolai Juul

    The notion of “capability” has long been influential in management research as an approach to address firm-level heterogeneity and heterogeneity in competitive outcomes. I discuss how recent advances in economics may allow for a more rigorous understanding and measurement of capability that take...

  17. Analysis of phosphorescence in heterogeneous systems using distributions of quencher concentration.

    Science.gov (United States)

    Golub, A S; Popel, A S; Zheng, L; Pittman, R N

    1997-07-01

    A continuous distribution approach, instead of the traditional mono- and multiexponential analysis, for determining quencher concentration in a heterogeneous system has been developed. A mathematical model of phosphorescence decay inside a volume with homogeneous concentration of phosphor and heterogeneous concentration of quencher was formulated to obtain pulse-response fitting functions for four different distributions of quencher concentration: rectangular, normal (Gaussian), gamma, and multimodal. The analysis was applied to parameter estimates of a heterogeneous distribution of oxygen tension (PO2) within a volume. Simulated phosphorescence decay data were randomly generated for different distributions and heterogeneity of PO2 inside the excitation/emission volume, consisting of 200 domains, and then fit with equations developed for the four models. Analysis using a monoexponential fit yielded a systematic error (underestimate) in mean PO2 that increased with the degree of heterogeneity. The fitting procedures based on the continuous distribution approach returned more accurate values for parameters of the generated PO2 distribution than did the monoexponential fit. The parameters of the fit (M = mean; sigma = standard deviation) were investigated as a function of signal-to-noise ratio (SNR = maximum signal amplitude/peak-to-peak noise). The best-fit parameter values were stable when SNR > or = 20. All four fitting models returned accurate values of M and sigma for different PO2 distributions. The ability of our procedures to resolve two different heterogeneous compartments was also demonstrated using a bimodal fitting model. An approximate scheme was formulated to allow calculation of the first moments of a spatial distribution of quencher without specifying the distribution. In addition, a procedure for the recovery of a histogram, representing the quencher concentration distribution, was developed and successfully tested.

  18. Design Technology for Heterogeneous Embedded Systems

    CERN Document Server

    O'Connor, Ian; Piguet, Christian

    2012-01-01

    Designing technology to address the problem of heterogeneous embedded systems, while remaining compatible with standard “More Moore” flows, i.e. capable of handling simultaneously both silicon complexity and system complexity, represents one of the most important challenges facing the semiconductor industry today. While the micro-electronics industry has built its own specific design methods to focus mainly on the management of complexity through the establishment of abstraction levels, the emergence of device heterogeneity requires new approaches enabling the satisfactory design of physically heterogeneous embedded systems for the widespread deployment of such systems. This book, compiled largely from a set of contributions from participants of past editions of the Winter School on Heterogeneous Embedded Systems Design Technology (FETCH), proposes a broad and holistic overview of design techniques used to tackle the various facets of heterogeneity in terms of technology and opportunities at the physical ...

  19. Assessment of tissue heterogeneity using diffusion tensor and diffusion kurtosis imaging for grading gliomas

    Energy Technology Data Exchange (ETDEWEB)

    Raja, Rajikha; Sinha, Neelam [International Institute of Information Technology-Bangalore, Bangalore (India); Saini, Jitender; Mahadevan, Anita; Rao, K.V.L. Narasinga; Swaminathan, Aarthi [National Institute of Mental Health and Neurosciences, Bangalore (India)

    2016-12-15

    In this work, we aim to assess the significance of diffusion tensor imaging (DTI) and diffusion kurtosis imaging (DKI) parameters in grading gliomas. Retrospective studies were performed on 53 subjects with gliomas belonging to WHO grade II (n = 19), grade III (n = 20) and grade IV (n = 14). Expert marked regions of interest (ROIs) covering the tumour on T2-weighted images. Statistical texture measures such as entropy and busyness calculated over ROIs on diffusion parametric maps were used to assess the tumour heterogeneity. Additionally, we propose a volume heterogeneity index derived from cross correlation (CC) analysis as a tool for grading gliomas. The texture measures were compared between grades by performing the Mann-Whitney test followed by receiver operating characteristic (ROC) analysis for evaluating diagnostic accuracy. Entropy, busyness and volume heterogeneity index for all diffusion parameters except fractional anisotropy and anisotropy of kurtosis showed significant differences between grades. The Mann-Whitney test on mean diffusivity (MD), among DTI parameters, resulted in the highest discriminability with values of P = 0.029 (0.0421) for grade II vs. III and P = 0.0312 (0.0415) for III vs. IV for entropy (busyness). In DKI, mean kurtosis (MK) showed the highest discriminability, P = 0.018 (0.038) for grade II vs. III and P = 0.022 (0.04) for III vs. IV for entropy (busyness). Results of CC analysis illustrate the existence of homogeneity in volume (uniformity across slices) for lower grades, as compared to higher grades. Hypothesis testing performed on volume heterogeneity index showed P values of 0.0002 (0.0001) and 0.0003 (0.0003) between grades II vs. III and III vs. IV, respectively, for MD (MK). In summary, the studies demonstrated great potential towards automating grading gliomas by employing tumour heterogeneity measures on DTI and DKI parameters. (orig.)

  20. Graphene-Si heterogeneous nanotechnology

    Science.gov (United States)

    Akinwande, Deji; Tao, Li

    2013-05-01

    It is widely envisioned that graphene, an atomic sheet of carbon that has generated very broad interest has the largest prospects for flexible smart systems and for integrated graphene-silicon (G-Si) heterogeneous very large-scale integrated (VLSI) nanoelectronics. In this work, we focus on the latter and elucidate the research progress that has been achieved for integration of graphene with Si-CMOS including: wafer-scale graphene growth by chemical vapor deposition on Cu/SiO2/Si substrates, wafer-scale graphene transfer that afforded the fabrication of over 10,000 devices, wafer-scalable mitigation strategies to restore graphene's device characteristics via fluoropolymer interaction, and demonstrations of graphene integrated with commercial Si- CMOS chips for hybrid nanoelectronics and sensors. Metrology at the wafer-scale has led to the development of custom Raman processing software (GRISP) now available on the nanohub portal. The metrology reveals that graphene grown on 4-in substrates have monolayer quality comparable to exfoliated flakes. At room temperature, the high-performance passivated graphene devices on SiO2/Si can afford average mobilities 3000cm2/V-s and gate modulation that exceeds an order of magnitude. The latest growth research has yielded graphene with high mobilities greater than 10,000cm2/V-s on oxidized silicon. Further progress requires track compatible graphene-Si integration via wafer bonding in order to translate graphene research from basic to applied research in commercial R and D laboratories to ultimately yield a viable nanotechnology.

  1. Quantifying the heterogeneity of the tectonic stress field using borehole data

    Science.gov (United States)

    Schoenball, Martin; Davatzes, Nicholas C.

    2017-01-01

    The heterogeneity of the tectonic stress field is a fundamental property which influences earthquake dynamics and subsurface engineering. Self-similar scaling of stress heterogeneities is frequently assumed to explain characteristics of earthquakes such as the magnitude-frequency relation. However, observational evidence for such scaling of the stress field heterogeneity is scarce.We analyze the local stress orientations using image logs of two closely spaced boreholes in the Coso Geothermal Field with sub-vertical and deviated trajectories, respectively, each spanning about 2 km in depth. Both the mean and the standard deviation of stress orientation indicators (borehole breakouts, drilling-induced fractures and petal-centerline fractures) determined from each borehole agree to the limit of the resolution of our method although measurements at specific depths may not. We find that the standard deviation in these boreholes strongly depends on the interval length analyzed, generally increasing up to a wellbore log length of about 600 m and constant for longer intervals. We find the same behavior in global data from the World Stress Map. This suggests that the standard deviation of stress indicators characterizes the heterogeneity of the tectonic stress field rather than the quality of the stress measurement. A large standard deviation of a stress measurement might be an expression of strong crustal heterogeneity rather than of an unreliable stress determination. Robust characterization of stress heterogeneity requires logs that sample stress indicators along a representative sample volume of at least 1 km.

  2. Breast cancer intra-tumor heterogeneity

    Science.gov (United States)

    2014-01-01

    In recent years it has become clear that cancer cells within a single tumor can display striking morphological, genetic and behavioral variability. Burgeoning genetic, epigenetic and phenomenological data support the existence of intra-tumor genetic heterogeneity in breast cancers; however, its basis is yet to be fully defined. Two of the most widely evoked concepts to explain the origin of heterogeneity within tumors are the cancer stem cell hypothesis and the clonal evolution model. Although the cancer stem cell model appeared to provide an explanation for the variability among the neoplastic cells within a given cancer, advances in massively parallel sequencing have provided several lines of evidence to suggest that intra-tumor genetic heterogeneity likely plays a fundamental role in the phenotypic heterogeneity observed in cancers. Many challenges remain, however, in the interpretation of the next generation sequencing results obtained so far. Here we review the models that explain tumor heterogeneity, the causes of intra-tumor genetic diversity and their impact on our understanding and management of breast cancer, methods to study intra-tumor heterogeneity and the assessment of intra-tumor genetic heterogeneity in the clinic. PMID:25928070

  3. Modelling income processes with lots of heterogeneity

    DEFF Research Database (Denmark)

    Browning, Martin; Ejrnæs, Mette; Alvarez, Javier

    2010-01-01

    We model earnings processes allowing for lots of heterogeneity across agents. We also introduce an extension to the linear ARMA model which allows the initial convergence in the long run to be different from that implied by the conventional ARMA model. This is particularly important for unit root...... this observable homogeneity, we find more latent heterogeneity than previous investigators. We show that allowance for heterogeneity makes substantial differences to estimates of model parameters and to outcomes of interest. Additionally, we find strong evidence against the hypothesis that any worker has a unit...

  4. Heterogeneity in the WTP for recreational access

    DEFF Research Database (Denmark)

    Campbell, Danny; Vedel, Suzanne Elizabeth; Thorsen, Bo Jellesmark

    2014-01-01

    In this study we have addressed appropriate modelling of heterogeneity in willingness to pay (WTP) for environmental goods, and have demonstrated its importance using a case of forest access in Denmark. We compared WTP distributions for four models: (1) a multinomial logit model, (2) a mixed logit...... was negative. However, models accounting for preference heterogeneity found a positive mean WTP, but a large sub-group with negative WTP. Accounting for preference heterogeneity can alter overall conclusions, which highlights the importance of this for policy recommendations....

  5. Shocks in homogeneous and heterogeneous populations

    Energy Technology Data Exchange (ETDEWEB)

    Finkelstein, Maxim [Department of Mathematical Statistics, University of the Free State, PO Box 339, 9300 Bloemfontein (South Africa) and Max Planck Institute for Demographic Research, Rostock (Germany)]. E-mail: FinkelM.SCI@mail.uovs.ac.za

    2007-05-15

    A system subject to a point process of shocks is considered. Shocks occur in accordance with a non-homogeneous Poisson process. Different criterions of system failures are discussed in a homogeneous case. Two natural settings are analyzed. Heterogeneity is modeled by an unobserved univariate random variable (frailty). It is shown that reliability (safety) analysis for a heterogeneous case can differ dramatically from that for a homogeneous setting. A shock burn-in procedure for a heterogeneous population is described. The corresponding bounds for the failure rates are obtained.

  6. Adsorption of gases on heterogeneous surfaces

    CERN Document Server

    Rudzinski, W

    1991-01-01

    All real solid surfaces are heterogeneous to a greater or lesser extent and this book provides a broad yet detailed survey of the present state of gas adsorption. Coverage is comprehensive and extends from basic principles to computer simulation of adsorption. Underlying concepts are clarified and the strengths and weaknesses of the various methods described are discussed.Key Features* Adsorption isotherm equations for various types of heterogeneous solid surfaces* Methods of determining the nature of surface heterogeneity and porosity from experimental data* Studies of pha

  7. Computational Mechanics for Heterogeneous Materials

    Energy Technology Data Exchange (ETDEWEB)

    Lechman, Jeremy B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Baczewski, Andrew David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bond, Stephen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Erikson, William W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lehoucq, Richard B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mondy, Lisa Ann [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Noble, David R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Pierce, Flint [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Roberts, Christine [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); van Swol, Frank B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Yarrington, Cole [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2013-11-01

    The subject of this work is the development of models for the numerical simulation of matter, momentum, and energy balance in heterogeneous materials. These are materials that consist of multiple phases or species or that are structured on some (perhaps many) scale(s). By computational mechanics we mean to refer generally to the standard type of modeling that is done at the level of macroscopic balance laws (mass, momentum, energy). We will refer to the flow or flux of these quantities in a generalized sense as transport. At issue here are the forms of the governing equations in these complex materials which are potentially strongly inhomogeneous below some correlation length scale and are yet homogeneous on larger length scales. The question then becomes one of how to model this behavior and what are the proper multi-scale equations to capture the transport mechanisms across scales. To address this we look to the area of generalized stochastic process that underlie the transport processes in homogeneous materials. The archetypal example being the relationship between a random walk or Brownian motion stochastic processes and the associated Fokker-Planck or diffusion equation. Here we are interested in how this classical setting changes when inhomogeneities or correlations in structure are introduced into the problem. Aspects of non-classical behavior need to be addressed, such as non-Fickian behavior of the mean-squared-displacement (MSD) and non-Gaussian behavior of the underlying probability distribution of jumps. We present an experimental technique and apparatus built to investigate some of these issues. We also discuss diffusive processes in inhomogeneous systems, and the role of the chemical potential in diffusion of hard spheres is considered. Also, the relevance to liquid metal solutions is considered. Finally we present an example of how inhomogeneities in material microstructure introduce fluctuations at the meso-scale for a thermal conduction problem

  8. Thermodynamic equilibrium at heterogeneous pressure

    Science.gov (United States)

    Vrijmoed, Johannes C.; Podladchikov, Yuri Y.

    2014-05-01

    Recent advances in metamorphic petrology point out the importance of grain-scale pressure variations in high-temperature metamorphic rocks. Pressures derived from chemical zonation using unconventional geobarometry based on equal chemical potentials fit mechanically feasible pressure variations. Here a thermodynamic equilibrium method is presented that predicts chemical zoning as a result of pressure variations by Gibbs energy minimization. Equilibrium thermodynamic prediction of the chemical zoning in the case of pressure heterogeneity is done by constraint Gibbs minimization using linear programming techniques. Compositions of phases considered in the calculation are discretized into 'pseudo-compounds' spanning the entire compositional space. Gibbs energies of these discrete compounds are generated for a given range and resolution of pressures for example derived by barometry or from mechanical model predictions. Gibbs energy minimization is subsequently performed considering all compounds of different composition and pressure. In addition to constraining the system composition a certain proportion of the system is constraint at a specified pressure. Input pressure variations need to be discretized and each discrete pressure defines an additional constraint for the minimization. The proportion of the system at each different pressure is equally distributed over the number of input pressures. For example if two input pressures P1 and P2 are specified, two constraints are added: 50 percent of the system is constraint at P1 while the remaining 50 percent is constraint at P2. The method has been tested for a set of 10 input pressures obtained by Tajčmanová et al. (2014) using their unconventional geobarometry method in a plagioclase rim around kyanite. Each input pressure is added as constraint to the minimization (1/10 percent of the system for each discrete pressure). Constraining the system composition to the average composition of the plagioclase rim

  9. Genetic heterogeneity in familial hyperinsulinism.

    Science.gov (United States)

    Nestorowicz, A; Glaser, B; Wilson, B A; Shyng, S L; Nichols, C G; Stanley, C A; Thornton, P S; Permutt, M A

    1998-07-01

    Familial hyperinsulinism (HI) is a disorder characterized by dysregulation of insulin secretion and profound hypoglycemia. Mutations in both the Kir6.2 and sulfonylurea receptor (SUR1) genes have been associated with the autosomal recessive form of this disorder. In this study, the spectrum and frequency of SUR1 mutations in HI and their significance to clinical manifestations of the disease were investigated by screening 45 HI probands of various ethnic origins for mutations in the SUR1 gene. Single-strand conformation polymorphism (SSCP) and nucleotide sequence analyses of genomic DNA revealed a total of 17 novel and three previously described mutations in SUR1 . The novel mutations comprised one nonsense and 10 missense mutations, two deletions, three mutations in consensus splice-site sequences and an in-frame insertion of six nucleotides. One mutation occurred in the first nucleotide binding domain (NBF-1) of the SUR1 molecule and another eight mutations were located in the second nucleotide binding domain (NBF-2), including two at highly conserved amino acid residues within the Walker A sequence motif. The majority of the remaining mutations was distributed throughout the three putative transmembrane domains of the SUR1 protein. With the exception of the 3993-9G-->A mutation, which was detected on 4.5% (4/88) disease chromosomes, allelic frequencies for the identified mutations varied between 1.1 and 2.3% for HI chromosomes, indicating that each mutation was rare within the patient cohort. The clinical manifestations of HI in those patients homozygous for mutations in the SUR1 gene are described. In contrast with the allelic homogeneity of HI previously described in Ashkenazi Jewish patients, these findings suggest that a large degree of allelic heterogeneity at the SUR1 locus exists in non-Ashkenazi HI patients. These data have important implications for genetic counseling and prenatal diagnosis of HI, and also provide a basis to further elucidate the

  10. Heterogeneous Multicore Processor Technologies for Embedded Systems

    CERN Document Server

    Uchiyama, Kunio; Kasahara, Hironori; Nojiri, Tohru; Noda, Hideyuki; Tawara, Yasuhiro; Idehara, Akio; Iwata, Kenichi; Shikano, Hiroaki

    2012-01-01

    To satisfy the higher requirements of digitally converged embedded systems, this book describes heterogeneous multicore technology that uses various kinds of low-power embedded processor cores on a single chip. With this technology, heterogeneous parallelism can be implemented on an SoC, and greater flexibility and superior performance per watt can then be achieved. This book defines the heterogeneous multicore architecture and explains in detail several embedded processor cores including CPU cores and special-purpose processor cores that achieve highly arithmetic-level parallelism. The authors developed three multicore chips (called RP-1, RP-2, and RP-X) according to the defined architecture with the introduced processor cores. The chip implementations, software environments, and applications running on the chips are also explained in the book. Provides readers an overview and practical discussion of heterogeneous multicore technologies from both a hardware and software point of view; Discusses a new, high-p...

  11. Selective Oxidations using Nanostructured Heterogeneous Catalysts

    DEFF Research Database (Denmark)

    Mielby, Jerrik Jørgen

    and because they produce H2O as the only by-product. Chapter 1 gives a short introduction to basic concepts in heterogeneous catalysis and green chemistry. Furthermore, the chapter gives an overview of the most important strategies to synthesise functional nanostructured materials and highlights how detailed......The aim of this thesis is to investigate and develop new efficient methods to oxidise alcohols and amines using heterogeneous catalysts and either O2 or H2O2 as oxidants. From an economic and environmental point of view, these oxidants are ideal, because they are cheap and readily available...... understanding of size, shape and structure can help in the development of new and more efficient heterogeneous catalysts. The chapter is not intended to give a complete survey, but rather to introduce some of the recent developments in the synthesis of nanostructured heterogeneous catalysts. Finally...

  12. Heterogeneous continuous-time random walks

    Science.gov (United States)

    Grebenkov, Denis S.; Tupikina, Liubov

    2018-01-01

    We introduce a heterogeneous continuous-time random walk (HCTRW) model as a versatile analytical formalism for studying and modeling diffusion processes in heterogeneous structures, such as porous or disordered media, multiscale or crowded environments, weighted graphs or networks. We derive the exact form of the propagator and investigate the effects of spatiotemporal heterogeneities onto the diffusive dynamics via the spectral properties of the generalized transition matrix. In particular, we show how the distribution of first-passage times changes due to local and global heterogeneities of the medium. The HCTRW formalism offers a unified mathematical language to address various diffusion-reaction problems, with numerous applications in material sciences, physics, chemistry, biology, and social sciences.

  13. Eradication of infectious diseases in heterogeneous populations

    Energy Technology Data Exchange (ETDEWEB)

    Travis, C.C.; Lenhart, S.M.

    1987-04-01

    A model is presented of infectious disease in heterogeneous populations, which allows for variable intra- to intergroup contact ratios. The authors give necessary and sufficient conditions for disease eradication by means of vaccination. Smallpox is used as an illustrative example.

  14. Detection of structural heterogeneity of glass melts

    DEFF Research Database (Denmark)

    Yue, Yuanzheng

    2004-01-01

    The structural heterogeneity of both supercooled liquid and molten states of silicate has been studied using calorimetric method. The objects of this study are basaltic glasses and liquids. Two experimental approaches are taken to detect the structural heterogeneity of the liquids. One is the hyp......The structural heterogeneity of both supercooled liquid and molten states of silicate has been studied using calorimetric method. The objects of this study are basaltic glasses and liquids. Two experimental approaches are taken to detect the structural heterogeneity of the liquids. One...... is discussed. The ordered structure of glass melts above the liquidus temperature is indirectly characterized by use of X-ray diffraction method. The new approaches are of importance for monitoring the glass melting and forming process and for improving the physical properties of glasses and glass fibers....

  15. NMR analysis of compositional heterogeneity in polysaccharides

    Science.gov (United States)

    Many copolysaccharides are compositionally heterogeneous, and the composition determined by the usual analytical or spectroscopic methods provides only an average value. For some polysaccharides, the NMR data contain copolymer sequence information, such as diad, triad, and tetrad sequence intensiti...

  16. Heterogeneous agents and decison making within firms

    NARCIS (Netherlands)

    Hung, Chung-yu

    2015-01-01

    This dissertation explores the implications of agents’ heterogeneity in decision making within situations where information is not completely contractible. Specifically, the study applies empirical methods across three chapters to examine the role of employees’ traits and their mutual relationships

  17. Flavivirus structural heterogeneity: implications for cell entry.

    Science.gov (United States)

    Rey, Félix A; Stiasny, Karin; Heinz, Franz X

    2017-06-01

    The explosive spread of Zika virus is the most recent example of the threat imposed to human health by flaviviruses. High-resolution structures are available for several of these arthropod-borne viruses, revealing alternative icosahedral organizations of immature and mature virions. Incomplete proteolytic maturation, however, results in a cloud of highly heterogeneous mosaic particles. This heterogeneity is further expanded by a dynamic behavior of the viral envelope glycoproteins. The ensemble of heterogeneous and dynamic infectious particles circulating in infected hosts offers a range of alternative possible receptor interaction sites at their surfaces, potentially contributing to the broad flavivirus host-range and variation in tissue tropism. The potential synergy between heterogeneous particles in the circulating cloud thus provides an additional dimension to understand the unanticipated properties of Zika virus in its recent outbreaks. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Exploring heterogeneous market hypothesis using realized volatility

    Science.gov (United States)

    Chin, Wen Cheong; Isa, Zaidi; Mohd Nor, Abu Hassan Shaari

    2013-04-01

    This study investigates the heterogeneous market hypothesis using high frequency data. The cascaded heterogeneous trading activities with different time durations are modelled by the heterogeneous autoregressive framework. The empirical study indicated the presence of long memory behaviour and predictability elements in the financial time series which supported heterogeneous market hypothesis. Besides the common sum-of-square intraday realized volatility, we also advocated two power variation realized volatilities in forecast evaluation and risk measurement in order to overcome the possible abrupt jumps during the credit crisis. Finally, the empirical results are used in determining the market risk using the value-at-risk approach. The findings of this study have implications for informationally market efficiency analysis, portfolio strategies and risk managements.

  19. Targeting population heterogeneity for optimal cell factories

    DEFF Research Database (Denmark)

    Heins, Anna-Lena; Carlqvist, Magnus; Helmark, S.

    To achieve an efficient production process, it is essential to optimize both the strain and the cultivation conditions. Traditionally, a microbial population has been considered homogeneous in optimization studies of fermentation processes. However, research has shown that a typical microbial...... population in a fermentor is heterogeneous. There are indications that such heterogeneity may be both beneficial (facilitates quick adaptation to new conditions) and harmful (reduces yields and productivities) for the robustness of the fermentation process. Significant gradients of e.g. dissolved oxygen...... the heterogeneity level of the population. To further investigate these phenomena and gain a deeper understanding of population heterogeneity, Saccharomyces cerevisiae growth reporter strains based on the expression of green fluorescent protein (GFP) were constructed which enabled us to perform single cell level...

  20. Changing Emulsion Dynamics with Heterogeneous Surface Wettability

    Science.gov (United States)

    Tsai, Peichun Amy; Meng, Qiang; Zhang, Yali; Li, Jiang; Lammertink, Rob; Chen, Haosheng

    2015-11-01

    We elucidate the effect of heterogeneous surface wettability on the morphology and dynamics of microfluidic emulsions, generated by a co-flowing device. We first design a useful methodology of modifying a micro-capillary with desired heterogeneous wettability, such as alternating hydrophilic and hydrophobic regions. Subsequently, the effects of flow rates and heterogeneous wettability on the emulsion morphology and motion in the micro-capillary are investigated. Our experimental data reveal a universal critical time scale of advective emulsions, above which the microfluidic emulsions remain intact, whereas below this time-scale emulsions become adhesive or inverse. A simple model based on a force balance can be used to explain this critical transition. These results show a control of emulsion dynamics by tuning the droplet size and the Capillary number, the ratio of viscous to surface effects, with heterogeneous surface wettability.

  1. Polygenic dissection of major depression clinical heterogeneity

    NARCIS (Netherlands)

    Milaneschi, Y.; Winkelman, F.; Peyrot, W.; Abdellaoui, A.; Willemsen, G.; Hottenga, J.J.; Jansen, R.; Mbarek, H.; Dehghan, A.; Lu, C.; Boomsma, D.I.; Penninx, B.W.J.H.

    2016-01-01

    The molecular mechanisms underlying major depressive disorder (MDD) are largely unknown. Limited success of previous genetics studies may be attributable to heterogeneity of MDD, aggregating biologically different subtypes. We examined the polygenic features of MDD and two common clinical subtypes

  2. Genetic Heterogeneity in Algerian Human Populations

    National Research Council Canada - National Science Library

    Bekada, Asmahan; Arauna, Lara R; Deba, Tahria; Calafell, Francesc; Benhamamouch, Soraya; Comas, David

    2015-01-01

    ...) and genetic heterogeneity in the region have been described. In this complex genetic landscape, Algeria, the largest country in Africa, has been poorly covered, with most of the studies using a single Algerian sample...

  3. Heterogeneity and Risk Sharing in Village Economies*

    Science.gov (United States)

    Chiappori, Pierre-André; Samphantharak, Krislert; Schulhofer-Wohl, Sam; Townsend, Robert M.

    2013-01-01

    We show how to use panel data on household consumption to directly estimate households’ risk preferences. Specifically, we measure heterogeneity in risk aversion among households in Thai villages using a full risk-sharing model, which we then test allowing for this heterogeneity. There is substantial, statistically significant heterogeneity in estimated risk preferences. Full insurance cannot be rejected. As the risk sharing, as-if-complete-markets theory might predict, estimated risk preferences are unrelated to wealth or other characteristics. The heterogeneity matters for policy: Although the average household would benefit from eliminating village-level risk, less-risk-averse households who are paid to absorb that risk would be worse off by several percent of household consumption. PMID:24932226

  4. Heterogeneity and Risk Sharing in Village Economies.

    Science.gov (United States)

    Chiappori, Pierre-André; Samphantharak, Krislert; Schulhofer-Wohl, Sam; Townsend, Robert M

    2014-03-01

    We show how to use panel data on household consumption to directly estimate households' risk preferences. Specifically, we measure heterogeneity in risk aversion among households in Thai villages using a full risk-sharing model, which we then test allowing for this heterogeneity. There is substantial, statistically significant heterogeneity in estimated risk preferences. Full insurance cannot be rejected. As the risk sharing, as-if-complete-markets theory might predict, estimated risk preferences are unrelated to wealth or other characteristics. The heterogeneity matters for policy: Although the average household would benefit from eliminating village-level risk, less-risk-averse households who are paid to absorb that risk would be worse off by several percent of household consumption.

  5. Fast, Just-in-Time Queries on Heterogeneous Raw Data

    CERN Multimedia

    CERN. Geneva

    2017-01-01

    Today’s scientific and business processes heavily depend on fast and accurate data analysis. Data scientists are routinely overwhelmed by the effort needed to manage the volumes of data produced. As general-purpose data management software is often inefficient, hard to manage, or too generic to serve today's applications, businesses increasingly turn to specialised data management software, which can only handle one data format, and then resort to data integration solutions. With the exponential growth of dataset size and complexity, however, data format-specific solutions no longer scale for efficient analysis, thereby slowing down the cycle of analysing and understanding the data, and making decisions. I will illustrate the different nature of problems we face when managing heterogeneous datasets, and how these translate to fundamental challenges for the data management community. Then I will introduce new technologies inspired by these challenges, which overturn long-stangding assumptions, enable meaning...

  6. Styles in Heterogeneous Modelling With UML

    OpenAIRE

    Bujorianu, M.C.; Bujorianu, L.M.

    2008-01-01

    Software development is becoming increasingly heterogeneous, and therefore the formal approaches to heterogeneity are geting very important but, unacceptable extremely complex. We propose a type theoretic approach based on the concept of style, as an attempt to simplify the complex interaction of different formal aspects of system specification. We use category theory to investigate three major semantic styles - algebraic, coalgebraic and relational - and specification methodologies like view...

  7. Specification and estimation of heterogeneous risk preference

    OpenAIRE

    Guan, Zhengfei; Wu, Feng

    2009-01-01

    In this paper we specify and estimate producers’ risk preference using farm data. We allow heterogeneous risk preference across individuals and propose a specification to model the heterogeneity. We base farmers’ decision making on a utility maximization framework and incorporate both market and production risk in farmers’ decision making. We do not assume any specific utility function or distribution of risk. The empirical application to farm level production data shows that risk preference ...

  8. Snapshot wavefield decomposition for heterogeneous velocity media

    OpenAIRE

    Holicki, M.E.; Wapenaar, C.P.A.

    2017-01-01

    We propose a novel directional decomposition operator for wavefield snapshots in heterogeneous-velocity media. The proposed operator demonstrates the link between the amplitude of pressure and particlevelocity plane waves in the wavenumber domain. The proposed operator requires two spatial Fourier transforms (one forward and one backward) per spatial dimension and time slice. To illustrate the operator we demonstrate its applicability to heterogeneous velocity models using a simple velocity-b...

  9. Labour market dynamics in a heterogeneous market

    OpenAIRE

    Gorter, C.; de Larquier, G.

    1999-01-01

    This paper develops a flow model in a dual labour market with heterogeneous workers and heterogeneous jobs that allows for upward mobility or promotion flows via the internal market and demotion or deskilling flows through the state of unemployment. Dynamic impulse-responses analyses are used to examine the effects of labour market policies that aim to generate institutional changes in the wage bargaining process, make job creation less costly or job matching more efficiently to reduce unempl...

  10. A study on the relationship between electrical transmural heterogeneity and ventricular energetics.

    Science.gov (United States)

    Hasegawa, Yuki; Mishima, Mitsuharu; Shimayoshi, Takao; Amano, Akira; Matsuda, Tetsuya

    2013-01-01

    In this study, we use cardiovascular simulation to gain new insights on the correlation between electrical heterogeneity and ventricular energetics. Although there are numerous in vivo and in vitro studies on the electrical heterogeneity within the ventricular myocardium, not much attention has been directed to its correlation to cardiovascular mechanics, because of difficulties in simultaneously observing and analyzing multiple spatial scales (the cell, the organ, and the system). We performed simulations with two cardiovascular simulation models, one which uses different myocardial cell models for the epicardial, endocardial, and mid-myocardial cells, and another which uses a homogeneous model throughout the entire myocardium. The epicardial, endocardial, and midmyocardial cell models were created by parametrically tuning a homogenous cell model. From the cardiovascular simulation we obtained pressure-volume loops which were used to calculate cardiovascular energetic efficiency and myocardial contractility. We found that energetic efficiency is higher in the electrically heterogeneous model.

  11. Ice nucleation in solutions and freeze-avoiding insects-homogeneous or heterogeneous?

    Science.gov (United States)

    Zachariassen, Karl Erik; Kristiansen, Erlend; Pedersen, Sindre Andre; Hammel, Harold T

    2004-06-01

    This article challenges the common view that solutions and cold-hardy freeze-avoiding insects always freeze by heterogeneous nucleation. Data are presented to show that the nucleation temperatures of a variety of solutions and freeze-avoiding insects are a function of the water volume as described by the data previously published by Bigg in 1953. The article also points out that the relationships between melting point depression and depression of nucleation temperature are different for samples undergoing homogeneous nucleation and those undergoing heterogeneous nucleation. Aqueous solutions and freeze-avoiding insects display a relationship like that of homogeneously nucleated samples. It is also argued that the identity of the "impurities" assumed to cause heterogeneous nucleation in aqueous solutions and insects is obscure and that the "impurities" have features which make their existence rather unlikely.

  12. Estimating flow using tracers and hydraulics in synthetic heterogeneous aquifers.

    Science.gov (United States)

    Larocque, Marie; Cook, Peter G; Haaken, Klaus; Simmons, Craig T

    2009-01-01

    Regional ground water flow is most usually estimated using Darcy's law, with hydraulic conductivities estimated from pumping tests, but can also be estimated using ground water residence times derived from radioactive tracers. The two methods agree reasonably well in relatively homogeneous aquifers but it is not clear which is likely to produce more reliable estimates of ground water flow rates in heterogeneous systems. The aim of this paper is to compare bias and uncertainty of tracer and hydraulic approaches to assess ground water flow in heterogeneous aquifers. Synthetic two-dimensional aquifers with different levels of heterogeneity (correlation lengths, variances) are used to simulate ground water flow, pumping tests, and transport of radioactive tracers. Results show that bias and uncertainty of flow rates increase with the variance of the hydraulic conductivity for both methods. The bias resulting from the nonlinearity of the concentration-time relationship can be reduced by choosing a tracer with a decay rate similar to the mean ground water residence time. The bias on flow rates estimated from pumping tests is reduced when performing long duration tests. The uncertainty on ground water flow is minimized when the sampling volume is large compared to the correlation length. For tracers, the uncertainty is related to the ratio of correlation length to the distance between sampling wells. For pumping tests, it is related to the ratio of correlation length to the pumping test's radius of influence. In regional systems, it may be easier to minimize this ratio for tracers than for pumping tests. Copyright © 2009 The Author(s). Journal Compilation © 2009 National Ground Water Association.

  13. MRI of Heterogeneous Hydrogenation Reactions Using Parahydrogen Polarization

    Energy Technology Data Exchange (ETDEWEB)

    Burt, Scott Russell [Univ. of California, Berkeley, CA (United States)

    2008-01-01

    The power of magnetic resonance imaging (MRI) is its ability to image the internal structure of optically opaque samples and provide detailed maps of a variety of important parameters, such as density, diffusion, velocity and temperature. However, one of the fundamental limitations of this technique is its inherent low sensitivity. For example, the low signal to noise ratio (SNR) is particularly problematic for imaging gases in porous materials due to the low density of the gas and the large volume occluded by the porous material. This is unfortunate, as many industrially relevant chemical reactions take place at gas-surface interfaces in porous media, such as packed catalyst beds. Because of this severe SNR problem, many techniques have been developed to directly increase the signal strength. These techniques work by manipulating the nuclear spin populations to produce polarized} (i.e., non-equilibrium) states with resulting signal strengths that are orders of magnitude larger than those available at thermal equilibrium. This dissertation is concerned with an extension of a polarization technique based on the properties of parahydrogen. Specifically, I report on the novel use of heterogeneous catalysis to produce parahydrogen induced polarization and applications of this new technique to gas phase MRI and the characterization of micro-reactors. First, I provide an overview of nuclear magnetic resonance (NMR) and how parahydrogen is used to improve the SNR of the NMR signal. I then present experimental results demonstrating that it is possible to use heterogeneous catalysis to produce parahydrogen-induced polarization. These results are extended to imaging void spaces using a parahydrogen polarized gas. In the second half of this dissertation, I demonstrate the use of parahydrogen-polarized gas-phase MRI for characterizing catalytic microreactors. Specifically, I show how the improved SNR allows one to map parameters important for characterizing the heat and mass

  14. Engineering Microbial Metabolite Dynamics and Heterogeneity.

    Science.gov (United States)

    Schmitz, Alexander C; Hartline, Christopher J; Zhang, Fuzhong

    2017-10-01

    As yields for biological chemical production in microorganisms approach their theoretical maximum, metabolic engineering requires new tools, and approaches for improvements beyond what traditional strategies can achieve. Engineering metabolite dynamics and metabolite heterogeneity is necessary to achieve further improvements in product titers, productivities, and yields. Metabolite dynamics, the ensemble change in metabolite concentration over time, arise from the need for microbes to adapt their metabolism in response to the extracellular environment and are important for controlling growth and productivity in industrial fermentations. Metabolite heterogeneity, the cell-to-cell variation in a metabolite concentration in an isoclonal population, has a significant impact on ensemble productivity. Recent advances in single cell analysis enable a more complete understanding of the processes driving metabolite heterogeneity and reveal metabolic engineering targets. The authors present an overview of the mechanistic origins of metabolite dynamics and heterogeneity, why they are important, their potential effects in chemical production processes, and tools and strategies for engineering metabolite dynamics and heterogeneity. The authors emphasize that the ability to control metabolite dynamics and heterogeneity will bring new avenues of engineering to increase productivity of microbial strains. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Heterogeneous mobile phone ownership and usage patterns in Kenya.

    Directory of Open Access Journals (Sweden)

    Amy Wesolowski

    Full Text Available The rapid adoption of mobile phone technologies in Africa is offering exciting opportunities for engaging with high-risk populations through mHealth programs, and the vast volumes of behavioral data being generated as people use their phones provide valuable data about human behavioral dynamics in these regions. Taking advantage of these opportunities requires an understanding of the penetration of mobile phones and phone usage patterns across the continent, but very little is known about the social and geographical heterogeneities in mobile phone ownership among African populations. Here, we analyze a survey of mobile phone ownership and usage across Kenya in 2009 and show that distinct regional, gender-related, and socioeconomic variations exist, with particularly low ownership among rural communities and poor people. We also examine patterns of phone sharing and highlight the contrasting relationships between ownership and sharing in different parts of the country. This heterogeneous penetration of mobile phones has important implications for the use of mobile technologies as a source of population data and as a public health tool in sub-Saharan Africa.

  16. Heterogeneous mobile phone ownership and usage patterns in Kenya.

    Science.gov (United States)

    Wesolowski, Amy; Eagle, Nathan; Noor, Abdisalan M; Snow, Robert W; Buckee, Caroline O

    2012-01-01

    The rapid adoption of mobile phone technologies in Africa is offering exciting opportunities for engaging with high-risk populations through mHealth programs, and the vast volumes of behavioral data being generated as people use their phones provide valuable data about human behavioral dynamics in these regions. Taking advantage of these opportunities requires an understanding of the penetration of mobile phones and phone usage patterns across the continent, but very little is known about the social and geographical heterogeneities in mobile phone ownership among African populations. Here, we analyze a survey of mobile phone ownership and usage across Kenya in 2009 and show that distinct regional, gender-related, and socioeconomic variations exist, with particularly low ownership among rural communities and poor people. We also examine patterns of phone sharing and highlight the contrasting relationships between ownership and sharing in different parts of the country. This heterogeneous penetration of mobile phones has important implications for the use of mobile technologies as a source of population data and as a public health tool in sub-Saharan Africa.

  17. Morphological effects on sensitivity of heterogeneous energetic materials

    Science.gov (United States)

    Roy, Sidhartha; Rai, Nirmal; Sen, Oishik; Udaykumar, H. S.

    2017-06-01

    The mesoscale physical response under shock loading in heterogeneous energetics is inherently linked to the microstructural characteristics. The current work demonstrates the connection between the microstructural features of porous energetic material and its sensitivity. A unified levelset based framework is developed to characterize the microstructures of a given sample. Several morphological metrics describing the mesoscale geometry of the materials are extracted using the current tool including anisotropy, tortuosity, surface to volume, nearest neighbors, size and curvature distributions. The relevant metrics among the ones extracted are identified and correlated to the mesoscale response of the energetic materials under shock loading. Two classes of problems are considered here: (a) field of idealized voids embedded in the HMX material and (b) real samples of pressed HMX. The effects of stochasticity associated with void arrangements on the sensitivity of the energetic material samples are shown. In summary, this work demonstrates the relationship between the mesoscale morphology and shock response of heterogeneous energetic materials using a levelset based framework.

  18. Stress path dependent hydromechanical behaviour of heterogeneous carbonate rock

    Directory of Open Access Journals (Sweden)

    Dimanov A.

    2010-06-01

    Full Text Available The influence of stress paths, representative of reservoir conditions, on the hydromechanical behavior of a moderately heterogeneous carbonate has been investigated. Multiscale structural heterogeneities, common for instance in carbonate rocks, can strongly alter the mechanical response and significantly influence the evolution of flow properties with stress. Using a triaxial cell, the permeability evolutions during compression and the effects of brittle (fracture and plastic (pore collapse deformations at yield, were measured. A strong scattering was observed on the mechanical response both in term of compressibility and failure threshold. Using the porosity scaling predicted by an adapted effective medium theory (based on crack growth under Hertzian contact, we have rescaled the critical pressures by the normalized porosity deviation. This procedure reduces efficiently the scattering, revealing in the framework of proportional stress path loading, a linear relation between the critical pressures and the stress path parameter through all the deformation regimes. It leads to a new formulation for the critical state envelope in the 'mean stress, deviatoric stress' diagram. The attractive feature of this new yield envelope formulation relies on the fact that only the two most common different mechanical tests 'Uniaxial Compression' and 'Hydrostatic Compression', are needed to define entirely the yield envelope. Volumic strains and normalized permeabilities are finally mapped in the stresses diagram and correlated.

  19. Multivariate volume rendering

    Energy Technology Data Exchange (ETDEWEB)

    Crawfis, R.A.

    1996-03-01

    This paper presents a new technique for representing multivalued data sets defined on an integer lattice. It extends the state-of-the-art in volume rendering to include nonhomogeneous volume representations. That is, volume rendering of materials with very fine detail (e.g. translucent granite) within a voxel. Multivariate volume rendering is achieved by introducing controlled amounts of noise within the volume representation. Varying the local amount of noise within the volume is used to represent a separate scalar variable. The technique can also be used in image synthesis to create more realistic clouds and fog.

  20. Developing a shale heterogeneity index to predict fracture response in the Mancos Shale

    Science.gov (United States)

    DeReuil, Aubry; Birgenheier, Lauren; McLennan, John

    2017-04-01

    approximately equivalent proportions of Al-Ca-Si compositions, while Al-rich samples have consistently low strength. Moisture preserved samples fail on average at approximately 5 MPa lower than dry samples of similar facies. Additionally, moisture preserved samples fail in a step-like pattern when tested perpendicular to bedding. Tensile fractures are halted at heterogeneities and propagate parallel to bedding planes before developing a through-going failure plane, as opposed to the discrete, continuous fractures that crosscut dry samples. This result suggests that sedimentary heterogeneity plays a greater role in fracture propagation in moisture preserved samples, which are more indicative of in-situ reservoir conditions. Stress-strain curves will be further analyzed, including estimation of an energy released term based on post-failure response, and an estimation of volume of cracking measure on the physical fracture surface.

  1. Dynamical links between small- and large-scale mantle heterogeneity: Seismological evidence

    Science.gov (United States)

    Frost, Daniel A.; Garnero, Edward J.; Rost, Sebastian

    2018-01-01

    We identify PKP • PKP scattered waves (also known as P‧ •P‧) from earthquakes recorded at small-aperture seismic arrays at distances less than 65°. P‧ •P‧ energy travels as a PKP wave through the core, up into the mantle, then scatters back down through the core to the receiver as a second PKP. P‧ •P‧ waves are unique in that they allow scattering heterogeneities throughout the mantle to be imaged. We use array-processing methods to amplify low amplitude, coherent scattered energy signals and resolve their incoming direction. We deterministically map scattering heterogeneity locations from the core-mantle boundary to the surface. We use an extensive dataset with sensitivity to a large volume of the mantle and a location method allowing us to resolve and map more heterogeneities than have previously been possible, representing a significant increase in our understanding of small-scale structure within the mantle. Our results demonstrate that the distribution of scattering heterogeneities varies both radially and laterally. Scattering is most abundant in the uppermost and lowermost mantle, and a minimum in the mid-mantle, resembling the radial distribution of tomographically derived whole-mantle velocity heterogeneity. We investigate the spatial correlation of scattering heterogeneities with large-scale tomographic velocities, lateral velocity gradients, the locations of deep-seated hotspots and subducted slabs. In the lowermost 1500 km of the mantle, small-scale heterogeneities correlate with regions of low seismic velocity, high lateral seismic gradient, and proximity to hotspots. In the upper 1000 km of the mantle there is no significant correlation between scattering heterogeneity location and subducted slabs. Between 600 and 900 km depth, scattering heterogeneities are more common in the regions most remote from slabs, and close to hotspots. Scattering heterogeneities show an affinity for regions close to slabs within the upper 200 km of the

  2. Business models for open innovation: Matching heterogeneous open innovation strategies with business model dimensions

    OpenAIRE

    Saebi, Tina; Foss, Nicolai Juul

    2015-01-01

    -This is the author's version of the article:"Business models for open innovation: Matching heterogeneous open innovation strategies with business model dimensions", European Management Journal, Volume 33, Issue 3, June 2015, Pages 201–213 Research on open innovation suggests that companies benefit differentially from adopting open innovation strategies; however, it is unclear why this is so. One possible explanation is that companies' business models are not attuned to open strategies. Ac...

  3. Mean nuclear volume

    DEFF Research Database (Denmark)

    Mogensen, O.; Sørensen, Flemming Brandt; Bichel, P.

    1999-01-01

    We evaluated the following nine parameters with respect to their prognostic value in females with endometrial cancer: four stereologic parameters [mean nuclear volume (MNV), nuclear volume fraction, nuclear index and mitotic index], the immunohistochemical expression of cancer antigen (CA125...

  4. Lung Volume Reduction Coil Treatment in Chronic Obstructive Pulmonary Disease Patients with Homogeneous Emphysema : A Prospective Feasibility Trial

    NARCIS (Netherlands)

    Klooster, Karin; ten Hacken, Nick H. T.; Franz, Ina; Kerstjens, Huib A. M.; van Rikxoort, Eva M.; Slebos, Dirk-Jan

    2014-01-01

    Background: In patients with heterogeneous emphysema, surgical and bronchoscopic lung volume reduction (LVR) treatments are available. However, for patients with homogeneous emphysema these treatments are hardly investigated and seem less effective. Bronchoscopic LVR coil treatment has been shown to

  5. Lung Volume Reduction Coil Treatment in Chronic Obstructive Pulmonary Disease Patients with Homogeneous Emphysema: A Prospective Feasibility Trial

    NARCIS (Netherlands)

    Klooster, K.; Hacken, N. Ten; Franz, I.; Kerstjens, H.; Rikxoort, E.M. van; Slebos, D.J.

    2014-01-01

    Background: In patients with heterogeneous emphysema, surgical and bronchoscopic lung volume reduction ({LVR}) treatments are available. However, for patients with homogeneous emphysema these treatments are hardly investigated and seem less effective. Bronchoscopic {LVR} coil treatment has been

  6. A quantitative measure for protein conformational heterogeneity.

    Science.gov (United States)

    Lyle, Nicholas; Das, Rahul K; Pappu, Rohit V

    2013-09-28

    Conformational heterogeneity is a defining characteristic of proteins. Intrinsically disordered proteins (IDPs) and denatured state ensembles are extreme manifestations of this heterogeneity. Inferences regarding globule versus coil formation can be drawn from analysis of polymeric properties such as average size, shape, and density fluctuations. Here we introduce a new parameter to quantify the degree of conformational heterogeneity within an ensemble to complement polymeric descriptors. The design of this parameter is guided by the need to distinguish between systems that couple their unfolding-folding transitions with coil-to-globule transitions and those systems that undergo coil-to-globule transitions with no evidence of acquiring a homogeneous ensemble of conformations upon collapse. The approach is as follows: Each conformation in an ensemble is converted into a conformational vector where the elements are inter-residue distances. Similarity between pairs of conformations is quantified using the projection between the corresponding conformational vectors. An ensemble of conformations yields a distribution of pairwise projections, which is converted into a distribution of pairwise conformational dissimilarities. The first moment of this dissimilarity distribution is normalized against the first moment of the distribution obtained by comparing conformations from the ensemble of interest to conformations drawn from a Flory random coil model. The latter sets an upper bound on conformational heterogeneity thus ensuring that the proposed measure for intra-ensemble heterogeneity is properly calibrated and can be used to compare ensembles for different sequences and across different temperatures. The new measure of conformational heterogeneity will be useful in quantitative studies of coupled folding and binding of IDPs and in de novo sequence design efforts that are geared toward controlling the degree of heterogeneity in unbound forms of IDPs.

  7. Parenchymal Strain Heterogeneity During Oscillatory Ventilation: Why Two Frequencies are Better than One.

    Science.gov (United States)

    Herrmann, Jacob; Tawhai, Merryn H; Kaczka, David W

    2017-10-19

    High frequency oscillatory ventilation (HFOV) relies on low tidal volumes cycled at supraphysiologic rates, producing fundamentally different mechanisms for gas transport and exchange compared with conventional mechanical ventilation. Despite the appeal of using low tidal volumes to mitigate the risks of ventilator-induced lung injury (VILI), HFOV has not improved mortality for most clinical indications. This may be due to non-uniform and frequency-dependent distribution of flow throughout the lung. The goal of this study was to compare parenchymal strain heterogeneity during eucapnic HFOV when using oscillatory waveforms that consisted of either a single discrete frequency or two simultaneous frequencies. We utilized on a three-dimensional, anatomically-structured canine lung model for simulating frequency-dependent ventilation distribution. Gas transport was simulated via direct alveolar ventilation, advective mixing at bifurcations, turbulent and oscillatory dispersion, and molecular diffusion. Volume amplitudes at each oscillatory frequency were iteratively optimized to attain eucapnia. Ventilation using single-frequency HFOV demonstrated increasing heterogeneity of acinar flow and CO2 elimination with frequency, for frequencies greater than the resonant frequency. For certain pairs of frequencies, a linear combination of the two corresponding ventilation distributions yielded reduced acinar strain heterogeneity compared to either frequency alone. Our model demonstrates that superposition of two simultaneous oscillatory frequencies can achieve more uniform ventilation distribution, and therefore lessen the potential for ventilator-induced lung injury, compared to traditional single-frequency HFOV. Copyright © 2017, Journal of Applied Physiology.

  8. Acinar ventilation heterogeneity in COPD relates to diffusion capacity, resistance and reactance.

    Science.gov (United States)

    Jarenbäck, Linnea; Ankerst, Jaro; Bjermer, Leif; Tufvesson, Ellen

    2016-01-01

    The aim of this study was to investigate heterogenic ventilation in the acinar (Sacin) and conductive (Scond) airways of patients with varying chronic obstructive pulmonary disease (COPD) severity and how these relates to advanced lung function parameters, primarily measured by impulse oscillometry (IOS). A secondary aim was to investigate the effects of a short acting beta2-agonist and a muscarinic antagonist on the heterogenic ventilation. Eleven never smoking controls, 12 smoking controls, and 57 COPD patients (7 GOLD 1, 25 GOLD 2, 14 GOLD 3 and 11 GOLD 4) performed flow-volume spirometry, IOS, body plethysmography, single breath carbon monoxide diffusion, and N2-multiple breath washout. Six smoking controls and 13 of the COPD patients also performed double reversibility test by using salbutamol and its combination with ipratropium. Sacin was significantly higher in GOLD 2-4 compared to never smoking controls and smoking controls, but showed similar levels in GOLD 3 and 4. A factor analysis identified 4 components consisting of; 1) IOS parameters, 2) volume parameters, 3) diffusion parameters, Sacin and some IOS parameters and 4) Scond with central obstruction/air trapping. Salbutamol and its combination with ipratropium had no effect on Sacin and Scond. Increased Sacin in COPD was strongly related to diffusion capacity and lung volumes, but also weakly to resistance and reactance, showing a link between ventilation heterogeneity in the acinar airways and parameters measured by IOS. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Dynamics and heterogeneity of brain damage in multiple sclerosis

    KAUST Repository

    Kotelnikova, Ekaterina

    2017-10-26

    Multiple Sclerosis (MS) is an autoimmune disease driving inflammatory and degenerative processes that damage the central nervous system (CNS). However, it is not well understood how these events interact and evolve to evoke such a highly dynamic and heterogeneous disease. We established a hypothesis whereby the variability in the course of MS is driven by the very same pathogenic mechanisms responsible for the disease, the autoimmune attack on the CNS that leads to chronic inflammation, neuroaxonal degeneration and remyelination. We propose that each of these processes acts more or less severely and at different times in each of the clinical subgroups. To test this hypothesis, we developed a mathematical model that was constrained by experimental data (the expanded disability status scale [EDSS] time series) obtained from a retrospective longitudinal cohort of 66 MS patients with a long-term follow-up (up to 20 years). Moreover, we validated this model in a second prospective cohort of 120 MS patients with a three-year follow-up, for which EDSS data and brain volume time series were available. The clinical heterogeneity in the datasets was reduced by grouping the EDSS time series using an unsupervised clustering analysis. We found that by adjusting certain parameters, albeit within their biological range, the mathematical model reproduced the different disease courses, supporting the dynamic CNS damage hypothesis to explain MS heterogeneity. Our analysis suggests that the irreversible axon degeneration produced in the early stages of progressive MS is mainly due to the higher rate of myelinated axon degeneration, coupled to the lower capacity for remyelination. However, and in agreement with recent pathological studies, degeneration of chronically demyelinated axons is not a key feature that distinguishes this phenotype. Moreover, the model reveals that lower rates of axon degeneration and more rapid remyelination make relapsing MS more resilient than the

  10. Implications of Heterogeneity in Multiple Myeloma

    Directory of Open Access Journals (Sweden)

    Sanjay de Mel

    2014-01-01

    Full Text Available Multiple myeloma is the second most common hematologic malignancy in the world. Despite improvement in outcome, the disease is still incurable for most patients. However, not all myeloma are the same. With the same treatment, some patients can have very long survival whereas others can have very short survival. This suggests that there is underlying heterogeneity in myeloma. Studies over the years have revealed multiple layers of heterogeneity. First, clinical parameters such as age and tumor burden could significantly affect outcome. At the genetic level, there are also significant heterogeneity ranging for chromosome numbers, genetic translocations, and genetic mutations. At the clonal level, there appears to be significant clonal heterogeneity with multiple clones coexisting in the same patient. At the cell differentiation level, there appears to be a hierarchy of clonally related cells that have different clonogenic potential and sensitivity to therapies. These levels of complexities present challenges in terms of treatment and prognostication as well as monitoring of treatment. However, if we can clearly delineate and dissect this heterogeneity, we may also be presented with unique opportunities for precision and personalized treatment of myeloma. Some proof of concepts of such approaches has been demonstrated.

  11. Computational model of heterogeneous heating in melanin

    Science.gov (United States)

    Kellicker, Jason; DiMarzio, Charles A.; Kowalski, Gregory J.

    2015-03-01

    Melanin particles often present as an aggregate of smaller melanin pigment granules and have a heterogeneous surface morphology. When irradiated with light within the absorption spectrum of melanin, these heterogeneities produce measurable concentrations of the electric field that result in temperature gradients from thermal effects that are not seen with spherical or ellipsoidal modeling of melanin. Modeling melanin without taking into consideration the heterogeneous surface morphology yields results that underestimate the strongest signals or over{estimate their spatial extent. We present a new technique to image phase changes induced by heating using a computational model of melanin that exhibits these surface heterogeneities. From this analysis, we demonstrate the heterogeneous energy absorption and resulting heating that occurs at the surface of the melanin granule that is consistent with three{photon absorption. Using the three{photon dluorescence as a beacon, we propose a method for detecting the extents of the melanin granule using photothermal microscopy to measure the phase changes resulting from the heating of the melanin.

  12. The effect of reservoir heterogeneity on gas production from hydrate accumulations in the permafrost

    Energy Technology Data Exchange (ETDEWEB)

    Reagan, M. T.; Kowalsky, M B.; Moridis, G. J.; Silpngarmlert, S.

    2010-05-01

    The quantity of hydrocarbon gases trapped in natural hydrate accumulations is enormous, leading to significant interest in the evaluation of their potential as an energy source. Large volumes of gas can be readily produced at high rates for long times from methane hydrate accumulations in the permafrost by means of depressurization-induced dissociation combined with conventional technologies and horizontal or vertical well configurations. Initial studies on the possibility of natural gas production from permafrost hydrates assumed homogeneity in intrinsic reservoir properties and in the initial condition of the hydrate-bearing layers (either due to the coarseness of the model or due to simplifications in the definition of the system). These results showed great promise for gas recovery from Class 1, 2, and 3 systems in the permafrost. This work examines the consequences of inevitable heterogeneity in intrinsic properties, such as in the porosity of the hydrate-bearing formation, or heterogeneity in the initial state of hydrate saturation. Heterogeneous configurations are generated through multiple methods: (1) through defining heterogeneous layers via existing well-log data, (2) through randomized initialization of reservoir properties and initial conditions, and (3) through the use of geostatistical methods to create heterogeneous fields that extrapolate from the limited data available from cores and well-log data. These extrapolations use available information and established geophysical methods to capture a range of deposit properties and hydrate configurations. The results show that some forms of heterogeneity, such as horizontal stratification, can assist in production of hydrate-derived gas. However, more heterogeneous structures can lead to complex physical behavior within the deposit and near the wellbore that may obstruct the flow of fluids to the well, necessitating revised production strategies. The need for fine discretization is crucial in all cases to

  13. Correlation of intra-tumor 18F-FDG uptake heterogeneity indices with perfusion CT derived parameters in colorectal cancer.

    Directory of Open Access Journals (Sweden)

    Florent Tixier

    Full Text Available Thirty patients with proven colorectal cancer prospectively underwent integrated 18F-FDG PET/DCE-CT to assess the metabolic-flow phenotype. Both CT blood flow parametric maps and PET images were analyzed. Correlations between PET heterogeneity and perfusion CT were assessed by Spearman's rank correlation analysis.Blood flow visualization provided by DCE-CT images was significantly correlated with 18F-FDG PET metabolically active tumor volume as well as with uptake heterogeneity for patients with stage III/IV tumors (|ρ|:0.66 to 0.78; p-value<0.02.The positive correlation found with tumor blood flow indicates that intra-tumor heterogeneity of 18F-FDG PET accumulation reflects to some extent tracer distribution and consequently indicates that 18F-FDG PET intra-tumor heterogeneity may be associated with physiological processes such as tumor vascularization.

  14. Heterogeneity in pineapple fruit quality results from plant heterogeneity at flower induction

    NARCIS (Netherlands)

    Fassinou Hotegni, V.N.; Lommen, W.J.M.; Agbossou, E.K.; Struik, P.C.

    2014-01-01

    Heterogeneity in fruit quality constitutes a major constraint in agri-food chains. In this paper the sources of the heterogeneity in pineapple in the field were studied in four experiments in commercial pineapple fields. The aims were to determine (a) whether differences in pineapple fruit quality

  15. Intratumoral morphological heterogeneity can be an indicator of genetic heterogeneity in colorectal cancer.

    Science.gov (United States)

    Büttner, Juliane; Jöhrens, Korinna; Klauschen, Frederick; Hummel, Michael; Lenze, Dido; Saeger, Wolfgang; Lehmann, Annika

    2018-02-01

    Anti-EGFR-targeted therapy is used to treat metastatic colorectal cancers with RAS wild-type. However, resistance to targeted therapy is often observed and can be primary or acquired. One reason for primary resistance is the presence of mutations that are undetected due to genetic heterogeneity, which can be expressed by differences present in primary tumor and distant metastasis or recurrence or by an intratumoral heterogeneity (presence of different subclones in the investigated tumor sample). The aim of our study was to investigate if morphological heterogeneity can be an indicator of intratumoral heterogeneity. We analysed 13 samples with homogeneous and six samples with heterogeneous morphology with NGS. We were able to demonstrate that intratumoral genetic heterogeneity is present in all studied tumor samples, independent of homogeneous or heterogeneous morphology. Moreover, one sample of our cohort with morphological and genetic heterogeneity had a genetic wild-type profile in one tumor component. Therefore, we recommend to include each morphologically identifiable tumor component in the mutational analysis to not overlook resistance-inducing or potentially targetable mutations. Copyright © 2018 Elsevier Inc. All rights reserved.

  16. Effect of edema, relative biological effectiveness, and dose heterogeneity on prostate brachytherapy.

    Science.gov (United States)

    Wang, Jian Z; Mayr, Nina A; Nag, Subir; Montebello, Joseph; Gupta, Nilendu; Samsami, Nina; Kanellitsas, Christos

    2006-04-01

    Many factors influence response in low-dose-rate (LDR) brachytherapy of prostate cancer. Among them, edema, relative biological effectiveness (RBE), and dose heterogeneity have not been fully modeled previously. In this work, the generalized linear-quadratic (LQ) model, extended to account for the effects of edema, RBE, and dose heterogeneity, was used to assess these factors and their combination effect. Published clinical data have shown that prostate edema after seed implant has a magnitude (ratio of post- to preimplant volume) of 1.3-2.0 and resolves exponentially with a half-life of 4-25 days over the duration of the implant dose delivery. Based on these parameters and a representative dose-volume histogram (DVH), we investigated the influence of edema on the implant dose distribution. The LQ parameters (alpha=0.15 Gy(-1) and alpha/beta=3.1 Gy) determined in earlier studies were used to calculate the equivalent uniform dose in 2 Gy fractions (EUD2) with respect to three effects: edema, RBE, and dose heterogeneity for 125I and 103Pd implants. The EUD2 analysis shows a negative effect of edema and dose heterogeneity on tumor cell killing because the prostate edema degrades the dose coverage to tumor target. For the representative DVH, the V100 (volume covered by 100% of prescription dose) decreases from 93% to 91% and 86%, and the D90 (dose covering 90% of target volume) decrease from 107% to 102% and 94% of prescription dose for 125I and 103Pd implants, respectively. Conversely, the RBE effect of LDR brachytherapy [versus external-beam radiotherapy (EBRT) and high-dose-rate (HDR) brachytherapy] enhances dose effect on tumor cell kill. In order to balance the negative effects of edema and dose heterogeneity, the RBE of prostate brachytherapy was determined to be approximately 1.2-1.4 for 125I and 1.3-1.6 for 103Pd implants. These RBE values are consistent with the RBE data published in the literature. These results may explain why in earlier modeling studies

  17. STRUCTURAL DEGRADATION OF HETEROGENEOUS WELDED JOINTS

    Directory of Open Access Journals (Sweden)

    Eva Schmidová

    2012-10-01

    Full Text Available Developing the techniques of welding materials with higher dynamic strength onto the rolling surfaces of rails is one of the options for increasing their operational endurance. The subject of this paper is an analysis of heterogeneous weld joints experimentally manufactured by welding medium-carbon austenitic steels onto high-carbon unalloyed pearlitic steels. The analyses focus on examinations of the marginal mixing of the materials at the fusion line and the circumstances under which intercrystalline cracks form in the weld deposit layers. Structural analyses, chemical microanalyses and a hardness assessment were performed in order to identify the corresponding structural changes. The proportion of zonal vs. interdendritic segregation of the alloying elements in the degradation of the welded joint was distinguished. We described the nature of the structural heterogeneities produced, locally connected with the martensitic transformation. The chemical heterogeneity leading to the formation of martensite at grain boundaries was identified as the limiting effect.

  18. Structural degradation of heterogeneous welded joints

    Directory of Open Access Journals (Sweden)

    Eva Schmidová

    2012-09-01

    Full Text Available Developing the techniques of welding materials with higher dynamic strength onto the rolling surfaces of rails is one of the options for increasing their operational endurance. The subject of this paper is an analyses of heterogeneous weld interfaces experimentally manufactured by welding medium-carbon austenitic steels onto high-carbon unalloyed pearlitic steels. The analyses focus on examinations of the marginal mixing of the materials at the weld interface and the circumstances under which intercrystalline cracks form in the weld deposit layers. Structural analyses, chemical microanalyses and a hardness assessment were performed in order to identify the corresponding structural changes. The proportion of zonal vs. interdendritic segregation of the alloying elements in the degradation of the welded joint was distinguished. We described the nature of the structural heterogeneities produced, locally connected with the martensitic transformation. The chemical heterogeneity leading to the formation of martensite at grain boundaries was identified as the limiting effect.

  19. Heterogeneous Metal Catalysts for Oxidation Reactions

    Directory of Open Access Journals (Sweden)

    Md. Eaqub Ali

    2014-01-01

    Full Text Available Oxidation reactions may be considered as the heart of chemical synthesis. However, the indiscriminate uses of harsh and corrosive chemicals in this endeavor are threating to the ecosystems, public health, and terrestrial, aquatic, and aerial flora and fauna. Heterogeneous catalysts with various supports are brought to the spotlight because of their excellent capabilities to accelerate the rate of chemical reactions with low cost. They also minimize the use of chemicals in industries and thus are friendly and green to the environment. However, heterogeneous oxidation catalysis are not comprehensively presented in literature. In this short review, we clearly depicted the current state of catalytic oxidation reactions in chemical industries with specific emphasis on heterogeneous catalysts. We outlined here both the synthesis and applications of important oxidation catalysts. We believe it would serve as a reference guide for the selection of oxidation catalysts for both industries and academics.

  20. Multiple roles of graphene in heterogeneous catalysis.

    Science.gov (United States)

    Fan, Xiaobin; Zhang, Guoliang; Zhang, Fengbao

    2015-05-21

    Scientific interest in graphene as a catalyst and as a catalyst support in heterogeneous catalytic reactions has grown dramatically over the past several years. The present critical review summarizes the multiple roles of graphene in heterogeneous catalysis and highlights the influence of defects, heteroatom-containing functionalities, and graphene's two-dimensional structure on catalytic performance. We first discuss the role and advantages of graphene as a catalyst support, with emphasis on its interactions with the catalytic phases and the influence of mass transfer processes. We then clarify the origin of the intrinsic catalytic activity of graphene in heterogeneous catalytic reactions. Finally we suggest challenges and potential practical applications for graphene in industrial processes.

  1. A stochastic model for tumor heterogeneity

    CERN Document Server

    Simone, Giuseppina

    2015-01-01

    Phenotype variations define heterogeneity of biological and molecular systems, which play a crucial role in several mechanisms. Heterogeneity has been demonstrated in tumor cells. Here, samples from blood of patients affected from colon tumor were analyzed and fished with a microfluidic assay based on galactose active moieties, and incubated, for culturing, in SCID mice. Following the experimental investigation, a model based on Markov theory was implemented and discussed to explain the equilibrium existing between phenotypes of subpopulations of cells sorted using the microfluidic assay. The model in combination with the experimental results had many implications for tumor heterogeneity. It displayed interconversion of phenotypes, as observed after experiments. The interconversion generates of metastatic cells and implies that targeting the CTCs will be not an efficient method to prevent tumor recurrence. Most importantly, understanding the transitions between cell phenotypes in cell population can boost the...

  2. Voice over IP in Wireless Heterogeneous Networks

    DEFF Research Database (Denmark)

    Fathi, Hanane; Chakraborty, Shyam; Prasad, Ramjee

    with the deployment of wireless heterogeneous systems, both speech and data traffic are carrried over wireless links by the same IP-based packet-switched infrastructure. However, this combination faces some challenges due to the inherent properties of the wireless network. The requirements for good quality VoIP...... communications are difficult to achieve in a time-varying environment due to channel errors and traffic congestion and across different systems. The provision of VoIP in wireless heterogeneous networks requires a set of time-efficient control mechanisms to support a VoIP session with acceptable quality....... The focus of Voice over IP in Wierless Heterogeneous Networks is on mechanisms that affect the VoIP user satisfaction  while not explicitly involved in the media session. This relates to the extra delays introduced by the security and the signaling protocols used to set up an authorized VoIP session...

  3. Nonclassical Kinetics of Clonal yet Heterogeneous Enzymes.

    Science.gov (United States)

    Park, Seong Jun; Song, Sanggeun; Jeong, In-Chun; Koh, Hye Ran; Kim, Ji-Hyun; Sung, Jaeyoung

    2017-07-06

    Enzyme-to-enzyme variation in the catalytic rate is ubiquitous among single enzymes created from the same genetic information, which persists over the lifetimes of living cells. Despite advances in single-enzyme technologies, the lack of an enzyme reaction model accounting for the heterogeneous activity of single enzymes has hindered a quantitative understanding of the nonclassical stochastic outcome of single enzyme systems. Here we present a new statistical kinetics and exactly solvable models for clonal yet heterogeneous enzymes with possibly nonergodic state dynamics and state-dependent reactivity, which enable a quantitative understanding of modern single-enzyme experimental results for the mean and fluctuation in the number of product molecules created by single enzymes. We also propose a new experimental measure of the heterogeneity and nonergodicity for a system of enzymes.

  4. Information flow in heterogeneously interacting systems.

    Science.gov (United States)

    Yamaguti, Yutaka; Tsuda, Ichiro; Takahashi, Yoichiro

    2014-02-01

    Motivated by studies on the dynamics of heterogeneously interacting systems in neocortical neural networks, we studied heterogeneously-coupled chaotic systems. We used information-theoretic measures to investigate directions of information flow in heterogeneously coupled Rössler systems, which we selected as a typical chaotic system. In bi-directionally coupled systems, spontaneous and irregular switchings of the phase difference between two chaotic oscillators were observed. The direction of information transmission spontaneously switched in an intermittent manner, depending on the phase difference between the two systems. When two further oscillatory inputs are added to the coupled systems, this system dynamically selects one of the two inputs by synchronizing, selection depending on the internal phase differences between the two systems. These results indicate that the effective direction of information transmission dynamically changes, induced by a switching of phase differences between the two systems.

  5. Spatial Measures of Genetic Heterogeneity During Carcinogenesis.

    Science.gov (United States)

    Storey, K; Ryser, M D; Leder, K; Foo, J

    2017-02-01

    In this work we explore the temporal dynamics of spatial heterogeneity during the process of tumorigenesis from healthy tissue. We utilize a spatial stochastic model of mutation accumulation and clonal expansion in a structured tissue to describe this process. Under a two-step tumorigenesis model, we first derive estimates of a non-spatial measure of diversity: Simpson's Index, which is the probability that two individuals sampled at random from the population are identical, in the premalignant population. We next analyze two new measures of spatial population heterogeneity. In particular we study the typical length scale of genetic heterogeneity during the carcinogenesis process and estimate the extent of a surrounding premalignant clone given a clinical observation of a premalignant point biopsy. This evolutionary framework contributes to a growing literature focused on developing a better understanding of the spatial population dynamics of cancer initiation and progression.

  6. Genetic heterogeneity and cancer drug resistance.

    Science.gov (United States)

    Turner, Nicholas C; Reis-Filho, Jorge S

    2012-04-01

    Despite the success of targeted therapies in the treatment of cancer, the development of resistance limits the ability to translate this method into a curative treatment. The mechanisms of resistance have traditionally been thought of as intrinsic (ie, present at baseline) or acquired (ie, developed after initial response). Recent evidence has challenged the notion of acquired resistance. Although cancers are traditionally thought to be clonal, there is now evidence of intra-tumour genetic heterogeneity in most cancers. The clinical pattern of acquired resistance in many circumstances represents outgrowth of resistant clones that might have originally been present in the primary cancer at low frequency but that have expanded under the selective pressure imposed by targeted therapies. Here, we describe the potential role of clonal heterogeneity in resistance to targeted therapy, discuss genetic instability as one of its causes, and detail approaches to tackle intra-tumour heterogeneity in the clinic. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. Quantifying tissue heterogeneity using quadtree decomposition.

    Science.gov (United States)

    Subramaniam, K; Hoffman, E A; Tawhai, M H

    2012-01-01

    Volumetric computed tomography (CT) imaging provides a three-dimensional map of image intensities from which lung soft tissue density distribution can be estimated. The information gained from analyzing these images can prove valuable in diagnosis of conditions where lung tissue is damaged or has degenerated, and it is also necessary for modeling lung tissue mechanics. This paper presents a new technique for quantifying heterogeneity based on individual CT images, and investigates the heterogeneity of lung tissue in a group of healthy young subjects. It is intended that development of this technique leads to a standard model of classifying heterogeneity in lung tissue, while taking into account variables such as different imaging platforms and resolutions, and the position of the patient during imaging.

  8. Intra-tumor heterogeneity from a cancer stem cell perspective

    NARCIS (Netherlands)

    Prasetyanti, Pramudita R.; Medema, Jan Paul

    2017-01-01

    Tumor heterogeneity represents an ongoing challenge in the field of cancer therapy. Heterogeneity is evident between cancers from different patients (inter-tumor heterogeneity) and within a single tumor (intra-tumor heterogeneity). The latter includes phenotypic diversity such as cell surface

  9. Comparison between field measurements and numerical simulation of steady-state solute transport in a heterogeneous soil profile

    Directory of Open Access Journals (Sweden)

    J. Vanderborght

    1997-01-01

    Full Text Available Abstract: Field-scale solute dispersion is determined by water flow heterogeneity which results from spatial variability of soil hydraulic properties and soil moisture state. Measured variabilities of soil hydraulic properties are highly sensitive to the experimental method. Field-scale dispersion derived from leaching experiments in a macroporous loam soil was compared with field-scale dispersion obtained with numerical simulations in heterogeneous random fields. Four types of random fields of hydraulic properties having statistical properties derived from four different types of laboratory measurements were considered. Based on this comparison, the measurement method depicting heterogeneities of hydraulic properties most relevant to field-scale solute transport was identified. For unsaturated flow, the variability of the hydraulic conductivity characteristic measured on a small soil volume was the most relevant parameter. For saturated flow, simulated dispersion underestimated the measured dispersion and it was concluded that heterogeneity of macroscopic hydraulic properties could not represent solute flow heterogeneity under these flow conditions. Field-scale averaged solute concentrations depend both on the detection method and the averaging procedure. Flux-averaged concentrations (relevant to practical applications differ from volume-averaged or resident concentrations (easy to measure, especially when water flow is more heterogeneous. Simulated flux and resident concentrations were subsequently used to test two simple one-dimensional transport models in predicting flux concentrations when they are calibrated on resident concentrations. In the first procedure, solute transport in a heterogeneous soil is represented by a 1-D convection dispersion process. The second procedure was based on the relation between flux and resident concentrations for a stochastic convective process. Better predictions of flux concentrations were obtained using

  10. Electrochemistry in Colloids and Dispersions. Volume 3. Colloidal Semiconductors

    Science.gov (United States)

    1992-02-04

    Technique’ Generation electrochemically RuO2 /polybrene rapid mixing 1-12 11 colloid & stopped flow I r electrochemically RuO./ TiO2 rapid mixing 1-12 11...8217OOOO1 92-06924 9 2i~ 1111 -1,llNi(ilI~l 11 Best Available Copy ~ REDOX MECHANISMS IN HETEROGENEOUS PHOTOCATALYSIS . THE CASE OF HOLES vs. OH*RADICAL...CONTENTS ABSTRACT p.i Volume III 21. Redox mechanisms in heterogeneous photocatalysis . The case of holes vs OH radical oxidation and free vs. surface-bound

  11. Static multiplicities in heterogeneous azeotropic distillation sequences

    DEFF Research Database (Denmark)

    Esbjerg, Klavs; Andersen, Torben Ravn; Jørgensen, Sten Bay

    1998-01-01

    In this paper the results of a bifurcation analysis on heterogeneous azeotropic distillation sequences are given. Two sequences suitable for ethanol dehydration are compared: The 'direct' and the 'indirect' sequence. It is shown, that the two sequences, despite their similarities, exhibit very...... different static behavior. The method of Petlyuk and Avet'yan (1971), Bekiaris et al. (1993), which assumes infinite reflux and infinite number of stages, is extended to and applied on heterogeneous azeotropic distillation sequences. The predictions are substantiated through simulations. The static sequence...

  12. Micro- and nanorobots swimming in heterogeneous liquids.

    Science.gov (United States)

    Nelson, Bradley J; Peyer, Kathrin E

    2014-09-23

    Essentially all experimental investigations of swimming micro- and nanorobots have focused on swimming in homogeneous Newtonian liquids. In this issue of ACS Nano, Schamel et al. investigate the actuation of "nanopropellers" in a viscoelastic biological gel that illustrates the importance of the size of the nanostructure relative to the gel mesh size. In this Perspective, we shed further light on the swimming performance of larger microrobots swimming in heterogeneous liquids. One of the interesting results of our work is that earlier findings on the swimming performance of motile bacteria in heterogeneous liquids agree, in principle, with our results. We also discuss future research directions that should be pursued in this fascinating interdisciplinary field.

  13. A molecular view of heterogeneous catalysis

    DEFF Research Database (Denmark)

    Christensen, Claus H.; Nørskov, Jens Kehlet

    2008-01-01

    The establishment of a molecular view of heterogeneous catalysis has been hampered for a number of reasons. There are, however, recent developments, which show that we are now on the way towards reaching a molecular-scale picture of the way solids work as catalysts. By a combination of new...... by enabling a rational design of new catalysts. We illustrate this important development in heterogeneous catalysis by highlighting recent examples of catalyst systems for which it has been possible to achieve such a detailed understanding. In particular, we emphasize examples where this progress has made...

  14. Heterogeneous Computing with OpenCL

    CERN Document Server

    Gaster, Benedict; Kaeli, David R; Mistry, Perhaad; Schaa, Dana

    2011-01-01

    Heterogeneous Computing with OpenCL teaches OpenCL and parallel programming for complex systems that may include a variety of device architectures: multi-core CPUs, GPUs, and fully-integrated Accelerated Processing Units (APUs) such as AMD Fusion technology. Designed to work on multiple platforms and with wide industry support, OpenCL will help you more effectively program for a heterogeneous future. Written by leaders in the parallel computing and OpenCL communities, this book will give you hands-on OpenCL experience to address a range of fundamental parallel algorithms. The authors explore m

  15. Heterogeneity and Scaling in Geologic Media

    Energy Technology Data Exchange (ETDEWEB)

    Gregory N. Boitnott; Gilles Y. Bussod; Paul N. Hagin; Stephen R. Brown

    2005-04-18

    The accurate characterization and remediation of contaminated subsurface environments requires the detailed knowledge of subsurface structures and flow paths. Enormous resources are invested in scoping and characterizing sites using core sampling, 3-D geophysical surveys, well tests, etc.... Unfortunately, much of the information acquired is lost to compromises and simplifications made in constructing numerical grids for the simulators used to predict flow and transport from the contaminated area to the accessible environment. In rocks and soils, the bulk geophysical and transport properties of the matrix and of fracture systems are determined by the juxtaposition of geometric features at many length scales. In the interest of computational efficiency, recognized heterogeneities are simplified, averaged out, or entirely ignored in spite of recent studies that recognize that: (1) Structural and lithologic heterogeneities exist on all scales in rocks. (2) Small heterogeneities influence, and can control the physical and chemical properties of rocks. In this work we propose a physically based approach for the description and treatment of heterogeneities, that highlights the use of laboratory equipment designed to measure the effect on physical properties of fine scale heterogeneities observed in rocks and soils. We then discuss the development of an integration methodology that uses these measurements to develop and upscale flow and transport models. Predictive simulations are 'calibrated' to the measured heterogeneity data, and subsequently upscaled in a way that is consistent with the transport physics and the efficient use of environmental geophysics. This methodology provides a more accurate interpretation and representation of the subsurface for both environmental engineering and remediation. We show through examples, (i) the important influence of even subtle heterogeneity in the interpreting of geophysical data, and (ii) how physically based upscaling

  16. Heterogeneous flow during high-pressure torsion

    Directory of Open Access Journals (Sweden)

    Roberto B. Figueiredo

    2013-06-01

    Full Text Available High-Pressure Torsion (HPT has attracted significant attention in recent years as an effective technique to process ultrafine and nanostructured materials. The hydrostatic pressure developed during processing prevents the occurrence of cracks and the low thickness to diameter ratio provides the opportunity for developing high strains at low numbers of rotations. The present work analyses the plastic flow during HPT. Experimental results and computer modeling are used to describe heterogeneous plastic flow. It is shown that variations in structure, hardness and in the distribution of strain are observed along the disc thickness. The sources of these heterogeneities are discussed.

  17. Heterogeneous catalysis at nanoscale for energy applications

    CERN Document Server

    Tao, Franklin (Feng); Kamat, Prashant V

    2015-01-01

    This book presents both the fundamentals concepts and latest achievements of a field that is growing in importance since it represents a possible solution for global energy problems.  It focuses on an atomic-level understanding of heterogeneous catalysis involved in important energy conversion processes. It presents a concise picture for the entire area of heterogeneous catalysis with vision at the atomic- and nano- scales, from synthesis, ex-situ and in-situ characterization, catalytic activity and selectivity, to mechanistic understanding based on experimental exploration and theoretical si

  18. Foreign Entry and Heterogeneous Growth of Firms

    DEFF Research Database (Denmark)

    Deng, Paul Duo; Jefferson, Gary H.

    We adopt the framework of Schumpeterian creative destruction formalized by Aghion et al. (2009) to analyze the impact of foreign entry on the productivity growth of domestic firms. In the face of foreign entry, domestic firms exhibit heterogeneous patterns of growth depending on their technological...... distance from foreign firms. Domestic firms with smaller technological distance from their foreign counterparts tend to experience faster productivity growth, while firms with larger technological distance tend to lag further behind. We test this hypothesis using a unique firm-level data of Chinese...... manufacturing. Our empirical results confirm that foreign entry indeed generates strong heterogeneous growth patterns among domestic firms....

  19. Genetic heterogeneity in hereditary haemorrhagic telangiectasia.

    Science.gov (United States)

    Porteous, M E; Curtis, A; Williams, O; Marchuk, D; Bhattacharya, S S; Burn, J

    1994-01-01

    A locus causing hereditary haemorrhagic telangiectasia (HHT) has recently been mapped to 9q34 in four families and designated HHT1. In this paper, the results of a linkage study showing genetic heterogeneity in four families in whom HHT is segregating are reported. All the previously reported 9q34 linked families contain at least one affected member with a symptomatic pulmonary arteriovenous malformation. We postulate that clinical heterogeneity may also be a feature of HHT with a significantly higher predisposition to symptomatic PAVMs associated with the HHT1 linked families. PMID:7891373

  20. Clinical Significance of Accounting for Tissue Heterogeneity in Permanent Breast Seed Implant Brachytherapy Planning.

    Science.gov (United States)

    Mashouf, Shahram; Fleury, Emmanuelle; Lai, Priscilla; Merino, Tomas; Lechtman, Eli; Kiss, Alex; McCann, Claire; Pignol, Jean-Philippe

    2016-03-15

    The inhomogeneity correction factor (ICF) method provides heterogeneity correction for the fast calculation TG43 formalism in seed brachytherapy. This study compared ICF-corrected plans to their standard TG43 counterparts, looking at their capacity to assess inadequate coverage and/or risk of any skin toxicities for patients who received permanent breast seed implant (PBSI). Two-month postimplant computed tomography scans and plans of 140 PBSI patients were used to calculate dose distributions by using the TG43 and the ICF methods. Multiple dose-volume histogram (DVH) parameters of clinical target volume (CTV) and skin were extracted and compared for both ICF and TG43 dose distributions. Short-term (desquamation and erythema) and long-term (telangiectasia) skin toxicity data were available on 125 and 110 of the patients, respectively, at the time of the study. The predictive value of each DVH parameter of skin was evaluated using the area under the receiver operating characteristic (ROC) curve for each toxicity endpoint. Dose-volume histogram parameters of CTV, calculated using the ICF method, showed an overall decrease compared to TG43, whereas those of skin showed an increase, confirming previously reported findings of the impact of heterogeneity with low-energy sources. The ICF methodology enabled us to distinguish patients for whom the CTV V100 and V90 are up to 19% lower compared to TG43, which could present a risk of recurrence not detected when heterogeneity are not accounted for. The ICF method also led to an increase in the prediction of desquamation, erythema, and telangiectasia for 91% of skin DVH parameters studied. The ICF methodology has the advantage of distinguishing any inadequate dose coverage of CTV due to breast heterogeneity, which can be missed by TG43. Use of ICF correction also led to an increase in prediction accuracy of skin toxicities in most cases. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Exploring the dynamic integration of heterogeneous services

    CSIR Research Space (South Africa)

    Makamba, M

    2016-08-01

    Full Text Available The increase need for services to handle a plethora of business needs within the enterprise landscape has yielded to an increase in the development of heterogeneous services across the digital world. In today’s digital economy, services are the key...

  2. µ-reactors for Heterogeneous Catalysis

    DEFF Research Database (Denmark)

    Jensen, Robert

    is described in detail. Since heating and temperature measurement is an extremely important point in heterogeneous catalysis an entire chapter is dedicated to this subject. Three different types of heaters have been implemented and tested both for repeatability and homogeneity of the heating as well...

  3. Conjugated Microporous Polymers for Heterogeneous Catalysis.

    Science.gov (United States)

    Zhou, Yun-Bing; Zhan, Zhuang-Ping

    2018-01-04

    Conjugated microporous polymers (CMPs) are a class of crosslinked polymers that combine permanent micropores with π-conjugated skeletons and possess three-dimensional (3D) networks. Compared with conventional materials such as metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), CMPs usually have superior chemical and thermal stability. CMPs have made significant progress in heterogeneous catalysis in the past seven years. With a bottom-up strategy, catalytic moieties can be directly introduced into in the framework to produce heterogeneous CMP catalysts. Higher activity, stability, and selectivity can be obtained with heterogeneous CMP catalysts in comparison with their homogeneous analogs. In addition, CMP catalysts can be easily isolated and recycled. In this review, we focus on CMPs as an intriguing platform for developing various highly efficient and recyclable heterogeneous catalysts in organic reactions. The design, synthesis, and structure of these CMP catalysts are also discussed in this focus review. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Diffusion and Surface Reaction in Heterogeneous Catalysis

    Science.gov (United States)

    Baiker, A.; Richarz, W.

    1978-01-01

    Ethylene hydrogenation on a platinum catalyst, electrolytically applied to a tube wall, is a good system for the study of the interactions between diffusion and surface reaction in heterogeneous catalysis. Theoretical background, apparatus, procedure, and student performance of this experiment are discussed. (BB)

  5. Scheduling Driven Partitioning of Heterogeneous Embedded Systems

    DEFF Research Database (Denmark)

    Pop, Paul; Eles, Petru; Peng, Zebo

    1998-01-01

    In this paper we present an algorithm for system level hardware/software partitioning of heterogeneous embedded systems. The system is represented as an abstract graph which captures both data-flow and the flow of control. Given an architecture consisting of several processors, ASICs and shared b...

  6. Testing spatial heterogeneity with stock assessment models

    DEFF Research Database (Denmark)

    Jardim, Ernesto; Eero, Margit; Silva, Alexandra

    2018-01-01

    This paper describes a methodology that combines meta-population theory and stock assessment models to gain insights about spatial heterogeneity of the meta-population in an operational time frame. The methodology was tested with stochastic simulations for different degrees of connectivity betwee...

  7. Cell Load Balancing in Heterogeneous Scenarios

    DEFF Research Database (Denmark)

    Eduardo, Simao; Rodrigues, Antonio; Mihovska, Albena D.

    2013-01-01

    Cell load imbalances in wireless networks degrade performance. Macro and small cell collocated deployments (heterogeneous scenario) constitutes a new problem for load balancing. This paper proposes a novel admission control algorithm for an optimal solution to the assignment of traffic flows...

  8. An estimating function approach to linkage heterogeneity

    Indian Academy of Sciences (India)

    1985). However, in the pedigrees with fragile X syndrome, there is linkage heterogeneity between the two loci. We randomly sampled eight pedigrees and their 70 off- spring from the pedigree data provided in Oberlé et al. (1986) and Brown et al. (1987), where five pedigrees (no. 1, 2, 5,. 9 and 13) came from Oberlé et al.

  9. Degree heterogeneity and stability of ecological networks.

    Science.gov (United States)

    Yan, Gang; Martinez, Neo D; Liu, Yang-Yu

    2017-06-01

    A classic measure of ecological stability describes the tendency of a community to return to equilibrium after small perturbations. While many advances show how the network architecture of these communities severely constrains such tendencies, one of the most fundamental properties of network structure, i.e. degree heterogeneity-the variability of the number of links associated with each species, deserves further study. Here we show that the effects of degree heterogeneity on stability vary with different types of interspecific interactions. Degree heterogeneity consistently destabilizes ecological networks with both competitive and mutualistic interactions, while its effects on networks of predator-prey interactions such as food webs depend on prey contiguity, i.e. the extent to which the species consume an unbroken sequence of prey in community niche space. Increasing degree heterogeneity tends to stabilize food webs except those with the highest prey contiguity. These findings help explain why food webs are highly but not completely interval and, more broadly, deepen our understanding of the stability of complex ecological networks. © 2017 The Author(s).

  10. Interpretable Categorization of Heterogeneous Time Series Data

    Science.gov (United States)

    Lee, Ritchie; Kochenderfer, Mykel J.; Mengshoel, Ole J.; Silbermann, Joshua

    2017-01-01

    We analyze data from simulated aircraft encounters to validate and inform the development of a prototype aircraft collision avoidance system. The high-dimensional and heterogeneous time series dataset is analyzed to discover properties of near mid-air collisions (NMACs) and categorize the NMAC encounters. Domain experts use these properties to better organize and understand NMAC occurrences. Existing solutions either are not capable of handling high-dimensional and heterogeneous time series datasets or do not provide explanations that are interpretable by a domain expert. The latter is critical to the acceptance and deployment of safety-critical systems. To address this gap, we propose grammar-based decision trees along with a learning algorithm. Our approach extends decision trees with a grammar framework for classifying heterogeneous time series data. A context-free grammar is used to derive decision expressions that are interpretable, application-specific, and support heterogeneous data types. In addition to classification, we show how grammar-based decision trees can also be used for categorization, which is a combination of clustering and generating interpretable explanations for each cluster. We apply grammar-based decision trees to a simulated aircraft encounter dataset and evaluate the performance of four variants of our learning algorithm. The best algorithm is used to analyze and categorize near mid-air collisions in the aircraft encounter dataset. We describe each discovered category in detail and discuss its relevance to aircraft collision avoidance.

  11. Heterogeneity in consumers' income and pension expectations

    NARCIS (Netherlands)

    Bissonnette, L.; van Soest, Arthur

    2015-01-01

    The expectations of economic agents play a crucial role in almost any inter-temporal economic model. Using 2009–12 panel data for a representative sample of the Dutch population, we analyze consumers’ income and pension expectations. We focus on heterogeneity across socioeconomic groups and

  12. Indoor Location Fingerprinting with Heterogeneous Clients

    DEFF Research Database (Denmark)

    Kjærgaard, Mikkel Baun

    2011-01-01

    Heterogeneous wireless clients measure signal strength differently. This is a fundamental problem for indoor location fingerprinting, and it has a high impact on the positioning accuracy. Mapping-based solutions have been presented that require manual and error-prone calibration for each new clie...

  13. A Note on the Heterogeneous Choice Model

    Science.gov (United States)

    Rohwer, Goetz

    2015-01-01

    The heterogeneous choice model (HCM) has been proposed as an extension of the standard logit and probit models, which allows taking into account different error variances of explanatory variables. In this note, I show that in an important special case, this model is just another way to specify an interaction effect.

  14. Cobalt-chitosan: Magnetic and biodegradable heterogeneous ...

    Indian Academy of Sciences (India)

    A novel and biodegradable cobalt-chitosan as a magnetic heterogeneous catalyst was synthesized and characterized by XPS, FT-IR, EDX and TEM. Catalytic performance of cobalt- chitosan was tested by aerobic oxidation of alkyl arenes and alcohols. The results show that the catalyst exhibits excellent conversion for ...

  15. EFFECT OF TOPOGRAPHIC AND GEOLOGIC HETEROGENEITIES ...

    African Journals Online (AJOL)

    Geologic heterogeneities and topographic variations in relation to aquifer distribution ad occurrence in Akwa Ibom State have been assessed based on geologic and geophysical studies sixty-six sounding points together with electric log responses of representative wells together with surface geologic data have been ...

  16. Physical Heterogeneity and Aquatic Community Function in ...

    Science.gov (United States)

    The geomorphological character of a river network provides the template upon which evolution acts to create unique biological communities. Deciphering commonly observed patterns and processes within riverine landscapes resulting from the interplay between physical and biological components is a central tenet for the interdisciplinary field of river science. Relationships between the physical heterogeneity and food web character of functional process zones (FPZs) – large tracts of river with a similar geomorphic character - in the Kanawha River (West Virginia, USA) are examined in this study. Food web character was measured as food chain length (FCL), which reflects ecological community structure and ecosystem function. Our results show the same basal resources were present throughout the Kanawha River but their assimilation into the aquatic food web by primary consumers differed between FPZs. Differences in the trophic position of secondary consumers – fish - were also recorded between FPZs. Overall, both the morphological heterogeneity and heterogeneity of the river bed sediment of FPZs were significantly correlated with FCL. Specifically, FCL increases with greater FPZ physical heterogeneity, supporting tenet 8 of the river ecosystem synthesis. In previous research efforts, we delineated the functional process zones (FPZs) of the Kanawha River. In this study, we examined the relationship between the hydrogeomorphically-derived zones with food webs.

  17. Scale Reliability Evaluation with Heterogeneous Populations

    Science.gov (United States)

    Raykov, Tenko; Marcoulides, George A.

    2015-01-01

    A latent variable modeling approach for scale reliability evaluation in heterogeneous populations is discussed. The method can be used for point and interval estimation of reliability of multicomponent measuring instruments in populations representing mixtures of an unknown number of latent classes or subpopulations. The procedure is helpful also…

  18. Heterogeneous Computing in Economics: A Simplified Approach

    DEFF Research Database (Denmark)

    Dziubinski, Matt P.; Grassi, Stefano

    This paper shows the potential of heterogeneous computing in solving dynamic equilibrium models in economics. We illustrate the power and simplicity of the C++ Accelerated Massive Parallelism recently introduced by Microsoft. Starting from the same exercise as Aldrich et al. (2011) we document...... a speed gain together with a simplified programming style that naturally enables parallelization....

  19. Modelling Preference Heterogeneity for Theatre Tickets

    DEFF Research Database (Denmark)

    Baldin, Andrea; Bille, Trine

    ) and latent class are proposed in order to model ticket purchase behaviour. These models allow us explicitly to take into account consumers' preference heterogeneity with respect to the attributes associated to each ticket alternative In addition, the distribution of the willingness-to-pay (WTP) of choice...

  20. Lattice stretching bistability and dynamic heterogeneity

    DEFF Research Database (Denmark)

    Christiansen, Peter Leth; Savin, A. V.; Zolotaryuk, A. V.

    2012-01-01

    between the bistable ground states. However, the key point of the model is the appearance of a heterogenous structure, when the second-neighbor coupling is sufficiently weak. In this case, a part of the chain has short bonds with a single-well potential, whereas the complementary part admits strongly...

  1. Masking through averages - intraprovincial heterogeneity in HIV ...

    African Journals Online (AJOL)

    Objective: To measure HIV prevalence at health-district level in the Western Cape (WC) and to compare these findings with those of the National HIV Antenatal Surveys (NHASs). This investigation aimed to estimate the degree of heterogeneity of HIV prevalence within the province in order to inform the design of appropriate ...

  2. resource allocation methodology for internet heterogeneous traffic

    African Journals Online (AJOL)

    Dr Obe

    RESOURCE ALLOCATION METHODOLOGY FOR INTERNET. HETEROGENEOUS TRAFFIC. Cosmas I Ani. Department of Electronic Engineering. University of Nigeria Nsukka, Nigeria. ABSTRACT. The mode of operation of internet can lead to congestion which, in turn, leads to degradation in the quality of service. (QoS).

  3. Heterogeneous multidimensional scaling for complex networks

    Science.gov (United States)

    Xuan, Qi; Ma, Xiaodi; Fu, Chenbo; Dong, Hui; Zhang, Guijun; Yu, Li

    2015-07-01

    Many real-world networks are essentially heterogeneous, where the nodes have different abilities to gain connections. Such networks are difficult to be embedded into low-dimensional Euclidean space if we ignore the heterogeneity and treat all the nodes equally. In this paper, based on a newly defined heterogeneous distance and a generalized network distance under the constraints of network and triangle inequalities, respectively, we propose a new heterogeneous multidimensional scaling method (HMDS) to embed different networks into proper Euclidean spaces. We find that HMDS behaves much better than the traditional multidimensional scaling method (MDS) in embedding different artificial and real-world networks into Euclidean spaces. Besides, we also propose a method to estimate the appropriate dimensions of Euclidean spaces for different networks, and find that the estimated dimensions are quite close to the real dimensions for those geometrical networks under study. These methods thus can help to better understand the evolution of real-world networks, and have practical importance in network visualization, community detection, link prediction and localization of wireless sensors.

  4. Service discovery in heterogeneous wireless networks

    NARCIS (Netherlands)

    Blangé, M.J.; Karkowski, I.P.; Vermeulen, B.C.B.

    2005-01-01

    In this paper we describe a possible solution to the problem of service discovery in heterogeneous wireless networks. This solution involves introduction of a network independent service discovery layer, with as main goal the improved robustness of applications running on top of it. A possible

  5. On Aggregating Human Capital Across Heterogeneous Cohorts

    DEFF Research Database (Denmark)

    Growiec, Jakub; Groth, Christian

    Based on a general framework for computing the aggregate human capital stock under heterogeneity across population cohorts, the paper derives aggregate human capital stocks in the whole population and in the labor force, and relates these variables to average years of schooling and average work...

  6. Effects of heterogeneity on bank efficiency scores

    NARCIS (Netherlands)

    Bos, J. W. B.; Koetter, M.; Kolari, J. W.; Kool, C. J. M.

    2009-01-01

    Bank efficiency estimates often serve as a proxy of managerial skill since they quantify sub-optimal production choices. But such deviations can also be due to omitted systematic differences among banks. In this study, we examine the effects of heterogeneity on bank efficiency scores. We compare

  7. Cobalt-chitosan: Magnetic and biodegradable heterogeneous ...

    Indian Academy of Sciences (India)

    Cobalt; chitosan; heterogeneous catalyst; magnetism; aerobic oxidation; alkyl arene. 1. Introduction. The selective oxidation of alkyl arenes and alcohols into the corresponding carbonyl compounds is an impor- tant goal in synthesis of fine chemicals.1 From green chemistry point of view, improving methods for oxida-.

  8. Heterogeneous formation of HONO on carbonaceous aerosol

    Energy Technology Data Exchange (ETDEWEB)

    Ammann, M.; Kalberer, M.; Tabor, K. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)] [and others

    1997-09-01

    Based on an on-line and in situ experimental approach, for the first time heterogeneous production of nitrous acid (HONO) on carbon aerosol at ambient pressure and low NO{sub 2} concentration has been quantified by use of a {sup 13}N tracer technique. (author) 1 fig., 4 refs.

  9. Pricing Liquidity Risk with Heterogeneous Investment Horizons

    NARCIS (Netherlands)

    Beber, A.; Driessen, J.; Tuijp, P.F.A.

    2012-01-01

    We develop a new asset pricing model with stochastic transaction costs and investors with heterogenous horizons. Short-term investors hold only liquid assets in equilibrium. This generates segmentation effects in the pricing of liquid versus illiquid assets. Specifically, the liquidity (risk) premia

  10. Snapshot wavefield decomposition for heterogeneous velocity media

    NARCIS (Netherlands)

    Holicki, M.E.; Wapenaar, C.P.A.

    2017-01-01

    We propose a novel directional decomposition operator for wavefield snapshots in heterogeneous-velocity media. The proposed operator demonstrates the link between the amplitude of pressure and particlevelocity plane waves in the wavenumber domain. The proposed operator requires two spatial Fourier

  11. Phenotypic heterogeneity of Streptococcus mutans in dentin.

    Science.gov (United States)

    Rupf, S; Hannig, M; Breitung, K; Schellenberger, W; Eschrich, K; Remmerbach, T; Kneist, S

    2008-12-01

    Information concerning phenotypic heterogeneity of Streptococcus mutans in carious dentin is sparse. Matrix-assisted laser-desorption/ionization-time-of-flight mass-spectrometry (MALDI-TOF-MS) facilitates the phenotypic differentiation of bacteria to the subspecies level. To verify a supposed influence of restorative treatment on the phenotypic heterogeneity of S. mutans, we isolated and compared a total of 222 S. mutans strains from dentin samples of 21 human deciduous molars during caries excavation (T(1)) and 8 wks (T(2)) after removal of the temporary restoration. Phenotypic heterogeneity was determined by MALDI-TOF-MS and hierarchical clustering. Thirty-six distinct S. mutans phenotypes could be identified. Although indistinguishable phenotypes were found in the same teeth at T(1) and T(2), as well as in different teeth of individual participants, the phenotypic heterogeneity increased significantly, from 1.4 phenotypes per S. mutans-positive dentin sample at T(1) to 2.2 phenotypes at T(2). We attribute this to an adaptation of S. mutans to the modified environment under the restoration following caries excavation.

  12. Dealing with spatial heterogeneity in entrepreneurship research

    NARCIS (Netherlands)

    Breitenecker, Robert J.; Harms, Rainer

    2010-01-01

    In quantitative research, analyses are generally made using a geographically defined population as the study area. In this context, the relationships between predictor and response variables can differ within the study area, a feature that is known as spatial heterogeneity. Without analyzing spatial

  13. Efficient High Performance Computing on Heterogeneous Platforms

    NARCIS (Netherlands)

    Shen, J.

    2015-01-01

    Heterogeneous platforms are mixes of different processing units in a compute node (e.g., CPUs+GPUs, CPU+MICs) or a chip package (e.g., APUs). This type of platforms keeps gaining popularity in various computer systems ranging from supercomputers to mobile devices. In this context, improving their

  14. Estimating the Cost of Heterogeneous Solutions

    OpenAIRE

    Poort, Eltjo; Vliet, Eric van der

    2014-01-01

    Existing estimation methods have severe limitations when it comes to estimating the delivery cost of heterogeneous IT-based solutions. In this experience report we present Solution-Based Estimation, a new approach that explicitly links a solution's architecture to its delivery cost model.

  15. Genetic heterogeneity of Oguchi′s disease

    Directory of Open Access Journals (Sweden)

    Singh Jai

    1990-01-01

    Full Text Available An analysis of the cases reported in Punjab, India, indicates the presence of genetic heterogeneity of Oguchi′s disease, for which autosomal recessive inheritance has been documented earlier. The autosomal dominant inheritance pattern of this disease is associated with incomplete penetrance and a distinct sex bias towards females. This recognition is important for genetic counselling.

  16. Genomic heterogeneity within cowpea bradyrhizobia isolated from ...

    African Journals Online (AJOL)

    Genomic heterogeneity within cowpea bradyrhizobia isolated from Ghanaian soils. JO Fening, A Sessitsch, SK Offei, SKA Danso. Abstract. No Abstract. Full Text: EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT · http://dx.doi.org/10.4314/wajae.v6i1.45605.

  17. Heterogeneous OH oxidation of organic aerosols

    Science.gov (United States)

    Smith, J.; Kroll, J.; Cappa, C.; Che, D.; Ahmed, M.; Leone, S.; Worsnop, D.; Wilson, K.

    2008-12-01

    The hydroxyl radical (OH) is the most important reactive species in both clean and polluted atmospheres, and therefore gas-phase OH chemistry has been extensively studied for decades. Due to this enormous effort the rates and mechanism of OH reactions with gas phase organics are relatively well understood. However, it unclear whether these well established gas-phase chemical mechanisms apply to the more complex heterogeneous reactions of OH radicals with organic aerosols (OA). Although recent studies have begun to examine OH oxidation of OA, numerous outstanding questions still remain regarding both the rate and chemical mechanism of these reactions. Here we present an in depth investigation of the heterogeneous oxidation of organic squalane particles by OH radicals. By combining a photochemical aerosol flow reactor with a high-resolution aerosol mass spectrometer (AMS), with both electron impact and vacuum ultraviolet photoionization, we investigate OH heterogeneous chemistry in unprecedented detail. Employing elemental composition measurements with detailed kinetics we have arrived at a simple oxidation model which accurately accounts for the evolution of squalane and its" oxidation products. In addition, by exploring a large range of OH concentrations we are able to directly measure the role of secondary particle-phase chain chemistry which can significantly accelerate the oxidation of OA in the atmosphere. Based on these measurements we have arrived at an explicit chemical mechanism for heterogeneous OH oxidation of OA which accurately accounts for our observations over a wide range of reaction conditions.

  18. Characterization of oil and gas reservoir heterogeneity

    Energy Technology Data Exchange (ETDEWEB)

    Tyler, N.; Barton, M.D.; Bebout, D.G.; Fisher, R.S.; Grigsby, J.D.; Guevara, E.; Holtz, M.; Kerans, C.; Nance, H.S.; Levey, R.A.

    1992-10-01

    Research described In this report addresses the internal architecture of two specific reservoir types: restricted-platform carbonates and fluvial-deltaic sandstones. Together, these two reservoir types contain more than two-thirds of the unrecovered mobile oil remaining ill Texas. The approach followed in this study was to develop a strong understanding of the styles of heterogeneity of these reservoir types based on a detailed outcrop description and a translation of these findings into optimized recovery strategies in select subsurface analogs. Research targeted Grayburg Formation restricted-platform carbonate outcrops along the Algerita Escarpment and In Stone Canyon In southeastern New Mexico and Ferron deltaic sandstones in central Utah as analogs for the North Foster (Grayburg) and Lake Creek (Wilcox) units, respectively. In both settings, sequence-stratigraphic style profoundly influenced between-well architectural fabric and permeability structure. It is concluded that reservoirs of different depositional origins can therefore be categorized Into a heterogeneity matrix'' based on varying intensity of vertical and lateral heterogeneity. The utility of the matrix is that it allows prediction of the nature and location of remaining mobile oil. Highly stratified reservoirs such as the Grayburg, for example, will contain a large proportion of vertically bypassed oil; thus, an appropriate recovery strategy will be waterflood optimization and profile modification. Laterally heterogeneous reservoirs such as deltaic distributary systems would benefit from targeted infill drilling (possibly with horizontal wells) and improved areal sweep efficiency. Potential for advanced recovery of remaining mobile oil through heterogeneity-based advanced secondary recovery strategies In Texas is projected to be an Incremental 16 Bbbl. In the Lower 48 States this target may be as much as 45 Bbbl at low to moderate oil prices over the near- to mid-term.

  19. Front matter: Volume 10385

    Science.gov (United States)

    Assoufid, Lahsen; Ohashi, Haruhiko; Asundi, Anand K.

    2017-09-01

    This PDF file contains the front matter associated with SPIE Proceedings Volume 10385, including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

  20. Reliability of air displacement plethysmography in a large, heterogeneous sample.

    Science.gov (United States)

    Noreen, Eric E; Lemon, Peter W R

    2006-08-01

    Several studies have assessed the validity of air displacement plethysmography (ADP), but few have assessed the reliability of ADP using a large, heterogeneous sample. This study was conducted to determine the reliability of ADP using the Bod Pod in a large, heterogeneous sample. A total of 980 healthy men and women (30 +/- 15 yr, mean +/- SD) completed two body composition assessments separated by 15-30 min. All testing was done in accordance with the manufacturer's instructions. A significant correlation (r = 0.992, P = 0.001) was found between body density (BD) 1 (1.046 +/- 0.001 kg.L(-1); mean +/- SEM) and BD 2 (1.046 +/- 0.001 kg.L(-1). A paired t-test revealed no significant difference between BD 1 and 2 (P = 0.935). The coefficient of variation (CV) for BD was 0.15%. A significant intraclass correlation coefficient (ICC) was found for BD (ICC = 0.996, P = 0.001), and the standard error of measurement (SEM) was 0.001 kg.L(-1). Body mass (BM) 1 and 2 were correlated significantly (r = 0.999, P = 0.001); however, a significant (P = 0.001) decrease was seen from BM 1 (75.510 +/- 0.461 kg) to BM 2 (75.497 +/- 0.461 kg). Body volume (BV) tended to decrease (P = 0.08) from BV 1 (69.900 +/- 0.449 L) to BV 2 (69.884 +/- 0.449 L). ADP using the Bod Pod appears to assess BD reliably; however, the observed CV suggests that multiple trials are necessary to detect small treatment effects.

  1. Robustness of intratumour {sup 18}F-FDG PET uptake heterogeneity quantification for therapy response prediction in oesophageal carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Hatt, Mathieu; Tixier, Florent; Visvikis, Dimitris [CHRU Morvan, INSERM, UMR 1101, LaTIM, Brest (France); Cheze Le Rest, Catherine [CHU Miletrie, Nuclear Medicine, Poitiers (France); Pradier, Olivier [CHRU Morvan, Radiotherapy, Brest (France)

    2013-10-15

    Intratumour uptake heterogeneity in PET quantified in terms of textural features for response to therapy has been investigated in several studies, including assessment of their robustness for reconstruction and physiological reproducibility. However, there has been no thorough assessment of the potential impact of preprocessing steps on the resulting quantification and its predictive value. The goal of this work was to assess the robustness of PET heterogeneity in textural features for delineation of functional volumes and partial volume correction (PVC). This retrospective analysis included 50 patients with oesophageal cancer. PVC of each PET image was performed. Tumour volumes were determined using fixed and adaptive thresholding, and the fuzzy locally adaptive Bayesian algorithm, and heterogeneity was quantified using local and regional textural features. Differences in the absolute values of the image-derived parameters considered were assessed using Bland-Altman analysis. The impact on their predictive value for the identification of patient nonresponders was assessed by comparing areas under the receiver operating characteristic curves. Heterogeneity parameters were more dependent on delineation than on PVC. The parameters most sensitive to delineation and PVC were regional ones (intensity variability and size zone variability), whereas local parameters such as entropy and homogeneity were the most robust. Despite the large differences in absolute values obtained from different delineation methods or after PVC, these differences did not necessarily translate into a significant impact on their predictive value. Parameters such as entropy, homogeneity, dissimilarity (for local heterogeneity characterization) and zone percentage (for regional characterization) should be preferred. This selection is based on a demonstrated high differentiation power in terms of predicting response, as well as a significant robustness with respect to the delineation method used

  2. Modeling mechanical response of heterogeneous materials

    Science.gov (United States)

    Pal, Siladitya

    Heterogeneous materials are ubiquitous in nature and as synthetic materials. These materials provide unique combination of desirable mechanical properties emerging from its heterogeneities at different length scales. Future structural and technological applications will require the development of advanced light weight materials with superior strength and toughness. Cost effective design of the advanced high performance synthetic materials by tailoring their microstructure is the challenge facing the materials design community. Prior knowledge of structure-property relationships for these materials is imperative for optimal design. Thus, understanding such relationships for heterogeneous materials is of primary interest. Furthermore, computational burden is becoming critical concern in several areas of heterogeneous materials design. Therefore, computationally efficient and accurate predictive tools are highly essential. In the present study, we mainly focus on mechanical behavior of soft cellular materials and tough biological material such as mussel byssus thread. Cellular materials exhibit microstructural heterogeneity by interconnected network of same material phase. However, mussel byssus thread comprises of two distinct material phases. A robust numerical framework is developed to investigate the micromechanisms behind the macroscopic response of both of these materials. Using this framework, effect of microstuctural parameters has been addressed on the stress state of cellular specimens during split Hopkinson pressure bar test. A voronoi tessellation based algorithm has been developed to simulate the cellular microstructure. Micromechanisms (microinertia, microbuckling and microbending) governing macroscopic behavior of cellular solids are investigated thoroughly with respect to various microstructural and loading parameters. To understand the origin of high toughness of mussel byssus thread, a Genetic Algorithm (GA) based optimization framework has been

  3. Defining, distinguishing and detecting the contribution of heterogeneous methylation to cancer heterogeneity.

    Science.gov (United States)

    Pisanic, Thomas R; Athamanolap, Pornpat; Wang, Tza-Huei

    2017-04-01

    DNA methylation is a fundamental means of epigenetic gene regulation that occurs in virtually all cell types. In many higher organisms, including humans, it plays vital roles in cell differentiation and homeostatic maintenance of cell phenotype. The control of DNA methylation has traditionally been attributed to a highly coordinated, linear process, whose dysregulation has been associated with numerous pathologies including cancer, where it occurs early in, and even prior to, the development of neoplastic tissues. Recent experimental evidence has demonstrated that, contrary to prevailing paradigms, methylation patterns are actually maintained through inexact, dynamic processes. These processes normally result in minor stochastic differences between cells that accumulate with age. However, various factors, including cancer itself, can lead to substantial differences in intercellular methylation patterns, viz. methylation heterogeneity. Advancements in molecular biology techniques are just now beginning to allow insight into how this heterogeneity contributes to clonal evolution and overall cancer heterogeneity. In the current review, we begin by presenting a didactic overview of how the basal bimodal methylome is established and maintained. We then provide a synopsis of some of the factors that lead to the accrual of heterogeneous methylation and how this heterogeneity may lead to gene silencing and impact the development of cancerous phenotypes. Lastly, we highlight currently available methylation assessment techniques and discuss their suitability to the study of heterogeneous methylation. Copyright © 2016. Published by Elsevier Ltd.

  4. BEGINNING INDONESIAN, VOLUME 3.

    Science.gov (United States)

    DYEN, ISIDORE

    VOLUME 3 OF A 4 VOLUME WORK ON BEGINNING INDONESIAN CONTAINS LESSONS 13-18 OF A TOTAL OF 24. THESE SIX LESSONS PROVIDE DRILLS IN BASIC INDONESIAN SENTENCE PATTERNS INVOLVING THE USE OF THE PASSIVE VOICE, PRONUNCIATION TECHNIQUES, ORTHOGRAPHY, FINAL VOWELS, AND FINAL SYLLABLES. LANGUAGE DRILLS ARE ALSO PROVIDED CONCERNING THE MONTHS OF THE YEAR AND…

  5. BEGINNING INDONESIAN. VOLUME 1.

    Science.gov (United States)

    DYEN, ISIDORE

    VOLUME 1 OF A 4-VOLUME WORK ON BEGINNING INDONESIAN CONTAINS THE FIRST 6 LESSONS OF A TOTAL OF 24. THESE SIX LESSONS PROVIDE DRILLS IN BASIC INDONESIAN SENTENCE PATTERNS INVOLVING THE USE OF TERMS OF ADDRESS, POLITE FORMULAS AND RESPONSES, AUXILIARIES, COMMANDS, AND ABSOLUTE EXPRESSIONS. RELATED REPORTS ARE ED 010 456 THROUGH ED 010 459. (GD)…

  6. BEGINNING INDONESIAN. VOLUME 2.

    Science.gov (United States)

    DYEN, ISIDORE

    VOLUME 2 OF A 4-VOLUME WORK ON BEGINNING INDONESIAN CONTAINS LESSONS 7-12 OF A TOTAL OF 24. THESE SIX LESSONS PROVIDE DRILLS IN BASIC INDONESIAN SENTENCE PATTERNS INVOLVING THE USE OF DIFFICULT VERBS, THE ACTIVE VOICE, INVERTED NARRATIVE CLAUSES, INTERROGATIVE WORDS, AND COUNTING METHODS. RELATED REPORTS ARE ED 010 456 THROUGH ED 010 459. (GD)

  7. Ovarian volume throughout life

    DEFF Research Database (Denmark)

    Kelsey, Thomas W; Dodwell, Sarah K; Wilkinson, A Graham

    2013-01-01

    to about 2.8 mL (95% CI 2.7-2.9 mL) at the menopause and smaller volumes thereafter. Our model allows us to generate normal values and ranges for ovarian volume throughout life. This is the first validated normative model of ovarian volume from conception to old age; it will be of use in the diagnosis...... cancer. To date there is no normative model of ovarian volume throughout life. By searching the published literature for ovarian volume in healthy females, and using our own data from multiple sources (combined n=59,994) we have generated and robustly validated the first model of ovarian volume from...... conception to 82 years of age. This model shows that 69% of the variation in ovarian volume is due to age alone. We have shown that in the average case ovarian volume rises from 0.7 mL (95% CI 0.4-1.1 mL) at 2 years of age to a peak of 7.7 mL (95% CI 6.5-9.2 mL) at 20 years of age with a subsequent decline...

  8. Variable volume combustor

    Science.gov (United States)

    Ostebee, Heath Michael; Ziminsky, Willy Steve; Johnson, Thomas Edward; Keener, Christopher Paul

    2017-01-17

    The present application provides a variable volume combustor for use with a gas turbine engine. The variable volume combustor may include a liner, a number of micro-mixer fuel nozzles positioned within the liner, and a linear actuator so as to maneuver the micro-mixer fuel nozzles axially along the liner.

  9. Volume Regulated Channels

    DEFF Research Database (Denmark)

    Klausen, Thomas Kjær

    of volume perturbations evolution have developed system of channels and transporters to tightly control volume homeostasis. In the past decades evidence has been mounting, that the importance of these volume regulated channels and transporters are not restricted to the defense of cellular volume......- serves a multitude of functions in the mammalian cell, regulating the membrane potential (Em), cell volume, protein activity and the driving force for facilitated transporters giving Cl- and Cl- channels a major potential of regulating cellular function. These functions include control of the cell cycle....... Understanding the structure/function relationship of TRPV4 is essential for future development of specific TRPV4 agonist for treatment of diseases causes by dysfunctional TRPV4. E.g. two inherited bone dysplasias have recently been demonstrated in humans to originate from TRPV4 mutations....

  10. Volume regulation in epithelia

    DEFF Research Database (Denmark)

    Larsen, Erik Hviid; Hoffmann, Else Kay

    2016-01-01

    We review studies on regulatory volume decrease (RVD) and regulatory volume increase (RVI) of major ion and water transporting vertebrate epithelia. The rate of RVD and RVI is faster in cells of high osmotic permeability like amphibian gallbladder and mammalian proximal tubule as compared...... function of iso-osmotic fluid transport that depends on Na+ recirculation. The causative relationship is discussed for a fluid-absorbing and a fluid-secreting epithelium of which the Na+ recirculation mechanisms have been identified. A large number of transporters and ion channels involved in cell volume...... regulation are cloned. The volume-regulated anion channel (VRAC) exhibiting specific electrophysiological characteristics seems exclusive to serve cell volume regulation. This is contrary to K+ channels as well as cotransporters and exchange mechanisms that may serve both transepithelial transport and cell...

  11. Linking Ventilation Heterogeneity Quantified via Hyperpolarized 3He MRI to Dynamic Lung Mechanics and Airway Hyperresponsiveness.

    Science.gov (United States)

    Lui, Justin K; Parameswaran, Harikrishnan; Albert, Mitchell S; Lutchen, Kenneth R

    2015-01-01

    Advancements in hyperpolarized helium-3 MRI (HP 3He-MRI) have introduced the ability to render and quantify ventilation patterns throughout the anatomic regions of the lung. The goal of this study was to establish how ventilation heterogeneity relates to the dynamic changes in mechanical lung function and airway hyperresponsiveness in asthmatic subjects. In four healthy and nine mild-to-moderate asthmatic subjects, we measured dynamic lung resistance and lung elastance from 0.1 to 8 Hz via a broadband ventilation waveform technique. We quantified ventilation heterogeneity using a recently developed coefficient of variation method from HP 3He-MRI imaging. Dynamic lung mechanics and imaging were performed at baseline, post-challenge, and after a series of five deep inspirations. AHR was measured via the concentration of agonist that elicits a 20% decrease in the subject's forced expiratory volume in one second compared to baseline (PC20) dose. The ventilation coefficient of variation was correlated to low-frequency lung resistance (R = 0.647, P ventilation heterogeneity. Also, the degree of AHR appears to be dependent on the degree to which baseline airway constriction creates baseline ventilation heterogeneity. HP 3He-MRI imaging may be a powerful predictor of the degree of AHR and in tracking the efficacy of therapy.

  12. Evaluation of the heterogeneity corrections impact in lung stereotactic body radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Nascimento, Jose Eduardo V.; Chiara, Ana Claudia M. de; Casagrande, Thais M.; Alves, Tatiana M.M.T.; Neves-Junior, Wellington F.P.; Mancini, Anselmo; Capella, Eliana; Pelosi, Edilson; Haddad, Cecilia K., E-mail: eduvan_rmm@hotmail.com [Hospital Sirio Libanes, Sao Paulo, SP (Brazil)

    2011-07-01

    Stereotactic body radiation therapy refers to an emerging radiotherapy that is highly effective in controlling early primary and oligometastic cancers at locations throughout the abdominopelvic and thoracic cavities, and at spinal and paraspinal sites. Some protocols have been developed for this procedure. In the special cases of lung, there are protocols in use that consider heterogeneity corrections and others that do not make use of heterogeneity correction. In this work, we recalculated, considering the different tissue densities plans initially optimized without heterogeneity corrections to evaluate the dosimetric changes that occurs, for example, PTV (planning target volume) coverage, dose to isocenter and dose to critical structures, and we calculated gamma function between the dose plans originated in the two conditions. We also performed the superposition between the calculated gamma function with the respective CT slice in order to evaluate in what conditions occur the major differences between the conditions of calculus considered. The results showed that relevant variations occur between the two situations of calculus. With the superposition of the image relative to {gamma} index and its respective CT slice, we could visualize where the greatest discrepancies occur. These data allow us to evaluate with more accuracy the doses delivered to the target and organs at risk and compare different protocols, independently of the use or non-use of heterogeneity corrections. (author)

  13. Heterogeneous Organo-Catalysis: Sustainable Pathways to ...

    Science.gov (United States)

    Glucose and fructose are among the most abundant plant-derived materials1 and have been converted into useful building units often used in the drug discovery and polymer architecture.2 Unfortunately, most of these conversions require mineral acids and complex heterogeneous catalysis systems which suffer from the diminished activity and recyclability issues.3 Herein, we report a highly reactive and inexpensive heterogeneous sulfonated graphitic carbon nitride (Sg-CN), endowed with strong acidity that readily transforms carbohydrates to furanics. The ready availability and benign nature of the material and its stability over the several reaction cycles renders this catalyst very useful in organic synthesis, polymer industry and in the preparation of drug precursors. Poster presentation at the 253rd American Chemical Society (ACS) National meeting in San Francisco, CA

  14. Heterogeneous Catalyst Deactivation and Regeneration: A Review

    Directory of Open Access Journals (Sweden)

    Morris D. Argyle

    2015-02-01

    Full Text Available Deactivation of heterogeneous catalysts is a ubiquitous problem that causes loss of catalytic rate with time. This review on deactivation and regeneration of heterogeneous catalysts classifies deactivation by type (chemical, thermal, and mechanical and by mechanism (poisoning, fouling, thermal degradation, vapor formation, vapor-solid and solid-solid reactions, and attrition/crushing. The key features and considerations for each of these deactivation types is reviewed in detail with reference to the latest literature reports in these areas. Two case studies on the deactivation mechanisms of catalysts used for cobalt Fischer-Tropsch and selective catalytic reduction are considered to provide additional depth in the topics of sintering, coking, poisoning, and fouling. Regeneration considerations and options are also briefly discussed for each deactivation mechanism.

  15. Equity Trading under Heterogeneity in Ambiguity

    DEFF Research Database (Denmark)

    Alonso, Irasema; Prado, Mauricio

    We examine the potential importance of heterogeneity in consumers' ambiguity aversion for asset pricing, portfolio allocation, and the wealth distribution. A main focus is to explore a situation in which ambiguity aversion is \\above normal", such as when there has been a sudden inflow of market...... of analyzing such occurrences theoretically, especially when one allows the possibility that different consumers/traders have different amounts of ambiguity aversion. By considering a model with heterogeneity on ambiguity, we explain differences in portfolio allocation, which lead to non......-relevant, but hard-to-interpret information: a situation like that during the onset of the recent crisis in financial markets. During this episode, market participants appeared unsure of the values of a variety of assets, trading all but stopped. Ambiguity aversion, it appears to us, offers a tractable way...

  16. Blind and myopic ants in heterogeneous networks

    Science.gov (United States)

    Hwang, S.; Lee, D.-S.; Kahng, B.

    2014-11-01

    The diffusion processes on complex networks may be described by different Laplacian matrices due to heterogeneous connectivity. Here we investigate the random walks of blind ants and myopic ants on heterogeneous networks: While a myopic ant hops to a neighbor node every step, a blind ant may stay or hop with probabilities that depend on node connectivity. By analyzing the trajectories of blind ants, we show that the asymptotic behaviors of both random walks are related by rescaling time and probability with node connectivity. Using this result, we show how the small eigenvalues of the Laplacian matrices generating the two random walks are related. As an application, we show how the return-to-origin probability of a myopic ant can be used to compute the scaling behaviors of the Edwards-Wilkinson model, a representative model of load balancing on networks.

  17. Heterogeneously Catalyzed Oxidation Reactions Using Molecular Oxygen

    DEFF Research Database (Denmark)

    Beier, Matthias Josef

    with a carboxylic acid resulting in TONs of up to 2000. In the absence of the carboxylic acid, ceria inhibited the reaction exhibiting radical scavenger properties. Contrary to p-xylene, neither ethylbenzene nor cumene conversion was promoted by ceria even in the presence of a carboxylic acid. Substantial leaching......Heterogeneously catalyzed selective oxidation reactions have attracted a lot of attention in recent time. The first part of the present thesis provides an overview over heterogeneous copper and silver catalysts for selective oxidations in the liquid phase and compared the performance and catalytic...... that both copper and silver can function as complementary catalyst materials to gold showing different catalytic properties and being more suitable for hydrocarbon oxidation reactions. Potential opportunities for future research were outlined. In an experimental study, the potential of silver as a catalyst...

  18. Dynamics of adaptation in spatially heterogeneous metapopulations.

    Directory of Open Access Journals (Sweden)

    Julien Papaïx

    Full Text Available The selection pressure experienced by organisms often varies across the species range. It is hence crucial to characterise the link between environmental spatial heterogeneity and the adaptive dynamics of species or populations. We address this issue by studying the phenotypic evolution of a spatial metapopulation using an adaptive dynamics approach. The singular strategy is found to be the mean of the optimal phenotypes in each habitat with larger weights for habitats present in large and well connected patches. The presence of spatial clusters of habitats in the metapopulation is found to facilitate specialisation and to increase both the level of adaptation and the evolutionary speed of the population when dispersal is limited. By showing that spatial structures are crucial in determining the specialisation level and the evolutionary speed of a population, our results give insight into the influence of spatial heterogeneity on the niche breadth of species.

  19. Modeling vaccination in a heterogeneous metapopulation system

    Science.gov (United States)

    Lachiany, Menachem

    2016-09-01

    We present here a multicity SIS epidemic model with vaccination. The model describes the dynamics of heterogeneous metapopulations that contain imperfectly vaccinated individuals. The effect of vaccination on heterogeneous multicity models has not been previously studied. We show that under very generic conditions, the epidemic threshold does not depend on the diffusion coefficient of the vaccinated individuals, but it does depend on the diffusion coefficient of the infected population. We then show, using a novel methodology, that the reproduction number is determined by the homogeneous model parameters and by the maximal number of neighbors a city can have, when the diffusion coefficient of the infected population is low. Finally, we present numerical simulations to support the analytical results.

  20. Heterogeneous physicochemistry of the polar ozone hole

    Science.gov (United States)

    Turco, Richard P.; Toon, Owen B.; Hamill, Patrick

    1989-01-01

    Processes occurring in the polar winter stratosphere, which involve polar stratospheric clouds (PSCs), are investigated using observations from the Airborne Antarctic Ozone Experiment. In particular, data on the properties of PSCs and their physical chemistry, the microphysical processes and time constants for cloud processes, the heterogeneous chemical processes and their time constants, and nonlinearities in the long-term ozone trend associated with physical and chemical processes are examined. The chemical reactions leading to the depletion of the inert chlorine reservoir in a presence of type I PSCs are established, and it is shown that type II PSCs contribute to chemical processing that sustains the chemical imbalance of the polar stratosphere. It is shown that, using a simple model, the decadal evolution of the Antarctic ozone hole may be understood through nonlinearities in the heterogeneous chemistry, with possible contributing effects of variations in stratospheric temperatures and water vapor concentrations.

  1. Modelling heterogeneous interfaces for solar water splitting

    Science.gov (United States)

    Pham, Tuan Anh; Ping, Yuan; Galli, Giulia

    2017-04-01

    The generation of hydrogen from water and sunlight offers a promising approach for producing scalable and sustainable carbon-free energy. The key of a successful solar-to-fuel technology is the design of efficient, long-lasting and low-cost photoelectrochemical cells, which are responsible for absorbing sunlight and driving water splitting reactions. To this end, a detailed understanding and control of heterogeneous interfaces between photoabsorbers, electrolytes and catalysts present in photoelectrochemical cells is essential. Here we review recent progress and open challenges in predicting physicochemical properties of heterogeneous interfaces for solar water splitting applications using first-principles-based approaches, and highlights the key role of these calculations in interpreting increasingly complex experiments.

  2. Dynamical heterogeneity of star-polymers

    Science.gov (United States)

    Emamy, Hamed; Chremos, Alexandros; Douglas, Jack; Starr, Francis

    The formation of a glass is one of the most vital features of amorphous polymers. While this subject has been exhaustively studied for linear chain polymers, comparatively little is known about the glass formation of star polymers, one of the most important classes of branched polymers. Using molecular dynamics simulation methods, we study the dynamical heterogeneity of star-polymers. We characterize the cooperative nature of the dynamic properties melts via the non-Gaussian nature of displacements, four-point correlations, clusters of highly mobile monomers, and subsets of string-like monomer motion. We contrast the behavior to that of ordinary linear chains, considering the role of both number of arms and molecular weight. In doing so, we quantify the degree to which the topology of star polymer plays a role in dynamical heterogeneity.

  3. Tengi Interfaces for Tracing between Heterogeneous Components

    DEFF Research Database (Denmark)

    Pfeiffer, Rolf-Helge; Wasowski, Andrzej

    2012-01-01

    , typically general programming languages, provide an interface description mechanism able to specify software com- ponent boundaries. Unfortunately, these interface mechanisms can not express relations for components containing heterogeneous artifacts. We introduce Tengi, a tool that allows......Contemporary software systems comprise many heteroge- neous artifacts; some expressed in general programming languages, some in visual and textual domain-specific languages and some in ad hoc textual formats. During construction of a system diverse artifacts are interrelated. Only few formats...... for the definition of software components containing heterogeneous artifacts. Tengi interfaces link components containing different textual and visual software development artifacts ranging from high-level specification documents to low-level implementation documents. We formally define and implement Tengi...

  4. Heterogeneous propellant internal ballistics: criticism and regeneration

    Science.gov (United States)

    Glick, R. L.

    2011-10-01

    Although heterogeneous propellant and its innately nondeterministic, chemically discrete morphology dominates applications, ballisticcharacterization deterministic time-mean burning rate and acoustic admittance measures' absence of explicit, nondeterministic information requires homogeneous propellant with a smooth, uniformly regressing burning surface: inadequate boundary conditions for heterogeneous propellant grained applications. The past age overcame this dichotomy with one-dimensional (1D) models and empirical knowledge from numerous, adequately supported motor developments and supplementary experiments. However, current cost and risk constraints inhibit this approach. Moreover, its fundamental science approach is more sensitive to incomplete boundary condition information (garbage-in still equals garbage-out) and more is expected. This work critiques this situation and sketches a path forward based on enhanced ballistic and motor characterizations in the workplace and approximate model and apparatus developments mentored by CSAR DNS capabilities (or equivalent).

  5. Heterogeneously-Catalyzed Conversion of Carbohydrates

    Science.gov (United States)

    Vigier, Karine De Oliveira; Jérôme, François

    Polyfunctionality of carbohydrates and their low solubility in conventional organic solvents make rather complex their conversion to higher value added chemicals. Therefore, innovative processes are now strongly needed in order to increase the selectivity of these reactions. Here, we report an overview of the different heterogeneously-catalyzed processes described in the literature. In particular, hydrolysis, dehydration, oxidation, esterification, and etherification of carbohydrates are presented. We shall discuss the main structural parameters that need to be controlled and that permit the conversion of carbohydrates to bioproducts with good selectivity. The conversion of monosaccharides and disaccharides over solid catalysts, as well as recent advances in the heterogeneously-catalyzed conversion of cellulose, will be presented.

  6. Heterogeneity in isogenic populations of microorganisms

    DEFF Research Database (Denmark)

    Pedersen, Anne Egholm

    . Chemically defined medium used for propagation of L. lactis resulted in a population profile which was problematic to analyze in relation to cell-to-cell growth rate variability. To investigate population heterogeneity in different types of microorganisms a Saccharomyces cerevisiae GFP reporter strain...... division changed unsynchronized when a population of Salmonella typhimurium was shifted to a different medium supporting another growth rate, hereby setting focus on the importance of balanced growth. In a balanced growing culture every component of the cell increases exponentially by the same constant...... heterogeneity was detected when the culture had been propagated according to the guidelines of the Copenhagen School of Bacterial Growth Physiology. The L. lactis GFP reporter strain was more challenging to analyze. The population profile for this reporter strain was shown to be dependent on the type of medium...

  7. Optimization of Hierarchically Scheduled Heterogeneous Embedded Systems

    DEFF Research Database (Denmark)

    Pop, Traian; Pop, Paul; Eles, Petru

    2005-01-01

    We present an approach to the analysis and optimization of heterogeneous distributed embedded systems. The systems are heterogeneous not only in terms of hardware components, but also in terms of communication protocols and scheduling policies. When several scheduling policies share a resource......, they are organized in a hierarchy. In this paper, we address design problems that are characteristic to such hierarchically scheduled systems: assignment of scheduling policies to tasks, mapping of tasks to hardware components, and the scheduling of the activities. We present algorithms for solving these problems....... Our heuristics are able to find schedulable implementations under limited resources, achieving an efficient utilization of the system. The developed algorithms are evaluated using extensive experiments and a real-life example....

  8. Microgrids and Heterogeneous Power Quality and Reliability

    Energy Technology Data Exchange (ETDEWEB)

    LaCommare, Kristina; Marnay, Chris

    2007-10-01

    This paper describes two stylized alternative visions of how the power system might evolve to meet future requirements for the high quality electricity service that modern digital economies demand, a supergrids paradigm and a dispersed paradigm. Some of the economics of the dispersed vision are explored, and perspectives are presented on both the choice of homogeneous universal power quality upstream in the electricity supply chain and on the extremely heterogeneous requirements of end-use loads. It is argued that meeting the demanding requirements of sensitive loads by local provision of high quality power may be more cost effective than increasing the quality of universal homogeneous supply upstream in the legacy grid. Finally, the potential role of microgrids in delivering heterogeneous power quality is demonstrated by reference to two ongoing microgrid tests in the U.S. and Japan.

  9. Heterogeneous data fusion for brain tumor classification.

    Science.gov (United States)

    Metsis, Vangelis; Huang, Heng; Andronesi, Ovidiu C; Makedon, Fillia; Tzika, Aria

    2012-10-01

    Current research in biomedical informatics involves analysis of multiple heterogeneous data sets. This includes patient demographics, clinical and pathology data, treatment history, patient outcomes as well as gene expression, DNA sequences and other information sources such as gene ontology. Analysis of these data sets could lead to better disease diagnosis, prognosis, treatment and drug discovery. In this report, we present a novel machine learning framework for brain tumor classification based on heterogeneous data fusion of metabolic and molecular datasets, including state-of-the-art high-resolution magic angle spinning (HRMAS) proton (1H) magnetic resonance spectroscopy and gene transcriptome profiling, obtained from intact brain tumor biopsies. Our experimental results show that our novel framework outperforms any analysis using individual dataset.

  10. Spatial Heterogeneity of Carbonates: genetic approach

    Science.gov (United States)

    Violette, Sophie; Gonçalvès, Julio; de Marsily, Ghislain

    2010-05-01

    Homogeneous equivalent property is a classical concept used in hydrogeology to define heterogeneity of hydraulic properties. Known as averaging, it tries to describe the spatial variability of the rock properties from geologic observations and local measurements. The techniques available for these descriptions are mostly continuous Geostatistical models, or discontinuous facies models such as the Boolean, Indicator or Gaussian-Threshold models and the Markow chain model. These facies models are better suited to treating issues of rock strata connectivity, e.g. buried high permeability channels or low permeability barriers, which greatly affect flow and, above all, transport in aquifers. Genetic models provide new ways to incorporate more geology into the facies description, an approach that has been well developed in the oil industry, but not enough in hydrogeology. Here we present how a 3Dbasin model, based on a detailed stratigraphic data base, has been used in a genetic way to reproduce the permeability and storage coefficient heterogeneities at the regional scale.

  11. Implications of intratumour heterogeneity for treatment stratification.

    Science.gov (United States)

    Crockford, Andrew; Jamal-Hanjani, Mariam; Hicks, James; Swanton, Charles

    2014-01-01

    Despite advances in the diagnosis and treatment of cancer, the majority of advanced metastatic solid tumours remain incurable. Differential gene expression, somatic mutational status, tumour-specific genetic signatures and micro-environmental selection pressures within individual tumours have implications for the success of predictive assays to guide therapeutic intervention. In this review we discuss the evidence for genetic and phenotypic heterogeneity and its potential implications for clinical decision making. We highlight areas of research that could be improved in order to better stratify patient treatment. We also discuss the predictive potential of patient-derived models of tumour response, including xenograft and cell line-based systems within the context of intratumour heterogeneity. Copyright © 2013 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

  12. Dynamics of adaptation in spatially heterogeneous metapopulations.

    Science.gov (United States)

    Papaïx, Julien; David, Olivier; Lannou, Christian; Monod, Hervé

    2013-01-01

    The selection pressure experienced by organisms often varies across the species range. It is hence crucial to characterise the link between environmental spatial heterogeneity and the adaptive dynamics of species or populations. We address this issue by studying the phenotypic evolution of a spatial metapopulation using an adaptive dynamics approach. The singular strategy is found to be the mean of the optimal phenotypes in each habitat with larger weights for habitats present in large and well connected patches. The presence of spatial clusters of habitats in the metapopulation is found to facilitate specialisation and to increase both the level of adaptation and the evolutionary speed of the population when dispersal is limited. By showing that spatial structures are crucial in determining the specialisation level and the evolutionary speed of a population, our results give insight into the influence of spatial heterogeneity on the niche breadth of species.

  13. Heterogeneous processes: Laboratory, field, and modeling studies

    Science.gov (United States)

    Poole, Lamont R.; Kurylo, Michael J.; Jones, Rod L.; Wahner, Andreas; Calvert, Jack G.; Leu, M.-T.; Fried, A.; Molina, Mario J.; Hampson, Robert F.; Pitts, M. C.

    1991-01-01

    The efficiencies of chemical families such as ClO(x) and NO(x) for altering the total abundance and distribution of stratospheric ozone are controlled by a partitioning between reactive (active) and nonreactive (reservoir) compounds within each family. Gas phase thermodynamics, photochemistry, and kinetics would dictate, for example, that only about 1 percent of the chlorine resident in the lower stratosphere would be in the form of active Cl or ClO, the remainder existing in the reservoir compounds HCl and ClONO2. The consistency of this picture was recently challenged by the recognition that important chemical transformations take place on polar regions: the Airborne Antarctic Ozone Experiment (AAOE) and the Airborne Arctic Stratospheric Expedition (AASA). Following the discovery of the Antarctic ozone hole, Solomon et al. suggested that the heterogeneous chemical reaction: ClONO2(g)+HCl(s) yields Cl2(g)+HNO3(s) could play a key role in converting chlorine from inactive forms into a species (Cl2) that would rapidly dissociate in sunlight to liberate atomic chlorine and initiate ozone depletion. The symbols (s) and (g) denote solid phase, or adsorbed onto a solid surface, and gas phase, respectively, and represent the approach by which such a reaction is modeled rather than the microscopic details of the reaction. The reaction was expected to be most important at altitudes where PSC's were most prevalent (10 to 25 km), thereby extending the altitude range over which chlorine compounds can efficiently destroy ozone from the 35 to 45 km region (where concentrations of active chlorine are usually highest) to lower altitudes where the ozone concentration is at its peak. This chapter will briefly review the current state of knowledge of heterogeneous processes in the stratosphere, emphasizing those results obtained since the World Meteorological Organization (WMO) conference. Sections are included on laboratory investigations of heterogeneous reactions, the

  14. Heterogeneous car buyers: a stylized fact

    OpenAIRE

    Ana M. Aizcorbe; Benjamin Bridgman; Jeremy J. Nalewaik

    2009-01-01

    Using a new dataset, we document a systematic pattern in the demographic characteristics of car buyers over the model year: as vehicle prices fall over the model year, so do buyer incomes. This pattern is consistent with price-insensitive buyers purchasing early in the year, while others wait until prices decline, and suggests price skimming (i.e. intertemporal price discrimination). Such consumer heterogeneity over the model year raises questions for measuring quality improvements in new goods.

  15. Cognitive resource management for heterogeneous cellular networks

    CERN Document Server

    Liu, Yongkang

    2014-01-01

    This Springer Brief focuses on cognitive resource management in heterogeneous cellular networks (Het Net) with small cell deployment for the LTE-Advanced system. It introduces the Het Net features, presents practical approaches using cognitive radio technology in accommodating small cell data relay and optimizing resource allocation and examines the effectiveness of resource management among small cells given limited coordination bandwidth and wireless channel uncertainty. The authors introduce different network characteristics of small cell, investigate the mesh of small cell access points in

  16. Heterogeneity, and the secret of the sea

    OpenAIRE

    Fraundorf, P

    2004-01-01

    This paper explores tools for modeling and measuring the compositional heterogeneity of a rock, or other solid specimen. Intuitive ``variation per decade'' plots, simple expressions for containment probability, generalization for familiar error-in-the-mean expressions, and a useful dimensionless sample bias coefficient all emerge from the analysis. These calculations have also inspired subsequent work on log-log roughness spectroscopy (with applications to scanning probe microscope data), and...

  17. [Heterogeneity of parasitic contamination of megalopolis soils].

    Science.gov (United States)

    Aliautdinova, L V; Semenova, T A; Zavoĭkin, V D

    2011-01-01

    A morphological group ofwhipworm (Trichuris trichiura) eggs, which is detectable in the soil samples from the city's different control lands, shows that their origin is heterogeneous and it is possible to differentiate them by morphometric signs. At the same time is necessary to consider the specific biological factors contributing to soil contamination. Priority in parasitic soil contamination should be given to animals, dogs in particular, which is supported by the fact that the dog walking grounds exhibit the highest contamination rates.

  18. Cooperative and heterogeneous indoor localization experiments

    OpenAIRE

    Denis, Benoit; Raulefs, Ronald; Fleury, Bernard; Uguen, Bernard; Amiot, Nicolas; Celis, L.; Dominguez,, J; Koldsgaard,, M.B; Laaraiedh, Mohamed; Noureddine,, H; Staudinger,, E; Steinboeck, Gerhard

    2013-01-01

    International audience; In this paper we present the results of real-life localization experiments performed in an unprecedented cooperative and heterogeneous wireless context. These measurements are based on ZigBee and orthogonal frequency division multiplexing (OFDM) devices, respectively endowed with received signal strength indicator (RSSI) and round trip delay (RTD) estimation capabilities. More particularly we emulate a multi-standard terminal, moving in a typical indoor environment, wh...

  19. Engineering aspects of heterogeneous and homogeneous reactors

    Energy Technology Data Exchange (ETDEWEB)

    Dickson, Jr, P W

    1977-01-01

    The core arrangement in an LMFBR can potentially affect the lower internals, upper internals, radial shielding, vessel, hot leg transients, head access area and control systems as well as breeding ratio, doubling time and core inventory. This paper describes the results of a study of the impact on these components and parameters that would result if the Clinch River Breeder Reactor were to incorporate a heterogeneous core.

  20. Heterogeneous Multitask Metric Learning Across Multiple Domains.

    Science.gov (United States)

    Luo, Yong; Wen, Yonggang; Tao, Dacheng

    2017-10-04

    Distance metric learning plays a crucial role in diverse machine learning algorithms and applications. When the labeled information in a target domain is limited, transfer metric learning (TML) helps to learn the metric by leveraging the sufficient information from other related domains. Multitask metric learning (MTML), which can be regarded as a special case of TML, performs transfer across all related domains. Current TML tools usually assume that the same feature representation is exploited for different domains. However, in real-world applications, data may be drawn from heterogeneous domains. Heterogeneous transfer learning approaches can be adopted to remedy this drawback by deriving a metric from the learned transformation across different domains. However, they are often limited in that only two domains can be handled. To appropriately handle multiple domains, we develop a novel heterogeneous MTML (HMTML) framework. In HMTML, the metrics of all different domains are learned together. The transformations derived from the metrics are utilized to induce a common subspace, and the high-order covariance among the predictive structures of these domains is maximized in this subspace. There do exist a few heterogeneous transfer learning approaches that deal with multiple domains, but the high-order statistics (correlation information), which can only be exploited by simultaneously examining all domains, is ignored in these approaches. Compared with them, the proposed HMTML can effectively explore such high-order information, thus obtaining more reliable feature transformations and metrics. Effectiveness of our method is validated by the extensive and intensive experiments on text categorization, scene classification, and social image annotation.

  1. Phenotype heterogeneity in cancer cell populations

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, Luis [CNRS UMR 7598, LJLL, & INRIA MAMBA team, Sorbonne Universités, UPMC Univ Paris 06, Boîte courrier 187, 4 Pl. Jussieu, 75252 Paris cedex 05, France, luis@ann.jussieu.fr (France); Chisholm, Rebecca [School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia, rebecca.chisholm@gmail.com (Australia); Clairambault, Jean [INRIA MAMBA team & LJLL, UMR 7598, Sorbonne Universités, UPMC Univ Paris 06, Boîte courrier 187, 4 Pl. Jussieu, 75252 Paris cedex 05, France, jean.clairambault@inria.fr, Corresponding author (France); Escargueil, Alexandre [INSERM “Cancer Biology and Therapeutics”, Sorbonne Universités, UPMC Univ Paris 06, UMR-S 938, CDR St Antoine, Hôpital St Antoine, 184 Fbg. St Antoine, 75571 Paris cedex 12, France, alexandre.escargueil@upmc.fr (France); Lorenzi, Tommaso [CMLA, ENS Cachan, 61, Av. du Président Wilson, 94230 Cachan cedex & INRIA MAMBA team, & LJLL, UMR 7598, UPMC Univ Paris 06, Boîte courrier 187, 4 Pl. Jussieu, 75252 Paris cedex 05, France, tommaso.lorenzi@gmail.com (France); Lorz, Alexander [Sorbonne Universités, UPMC Univ Paris 06, LJLL, UMR 7598 & INRIA Boîte courrier 187, 4 Pl. Jussieu, 75252 Paris cedex 05, France, alex.lorz@ann.jussieu.fr (France); Trélat, Emmanuel [Institut Universitaire de France, Sorbonne Universités, UPMC Univ Paris 06, LJLL, UMR 7598, Boîte courrier 187, UPMC Univ Paris 06, 4 Pl. Jussieu, 75252 Paris cedex 05, France, emmanuel.trelat@upmc.fr (France)

    2016-06-08

    Phenotype heterogeneity in cancer cell populations, be it of genetic, epigenetic or stochastic origin, has been identified as a main source of resistance to drug treatments and a major source of therapeutic failures in cancers. The molecular mechanisms of drug resistance are partly understood at the single cell level (e.g., overexpression of ABC transporters or of detoxication enzymes), but poorly predictable in tumours, where they are hypothesised to rely on heterogeneity at the cell population scale, which is thus the right level to describe cancer growth and optimise its control by therapeutic strategies in the clinic. We review a few results from the biological literature on the subject, and from mathematical models that have been published to predict and control evolution towards drug resistance in cancer cell populations. We propose, based on the latter, optimisation strategies of combined treatments to limit emergence of drug resistance to cytotoxic drugs in cancer cell populations, in the monoclonal situation, which limited as it is still retains consistent features of cell population heterogeneity. The polyclonal situation, that may be understood as “bet hedging” of the tumour, thus protecting itself from different sources of drug insults, may lie beyond such strategies and will need further developments. In the monoclonal situation, we have designed an optimised therapeutic strategy relying on a scheduled combination of cytotoxic and cytostatic treatments that can be adapted to different situations of cancer treatments. Finally, we review arguments for biological theoretical frameworks proposed at different time and development scales, the so-called atavistic model (diachronic view relying on Darwinian genotype selection in the coursof billions of years) and the Waddington-like epigenetic landscape endowed with evolutionary quasi-potential (synchronic view relying on Lamarckian phenotype instruction of a given genome by reversible mechanisms), to

  2. Evolution of altruistic punishment in heterogeneous populations.

    Science.gov (United States)

    de Weerd, Harmen; Verbrugge, Rineke

    2011-12-07

    Evolutionary models for altruistic behavior typically make the assumption of homogeneity: each individual has the same costs and benefits associated with cooperating with each other and punishing for selfish behavior. In this paper, we relax this assumption by separating the population into heterogeneous classes, such that individuals from different classes differ in their ability to punish for selfishness. We compare the effects of introducing heterogeneity this way across two population models, that each represents a different type of population: the infinite and well-mixed population describes the way workers of social insects such as ants are organized, while a spatially structured population is more related to the way social norms evolve and are maintained in a social network. We find that heterogeneity in the effectiveness of punishment by itself has little to no effect on whether or not altruistic behavior will stabilize in a population. In contrast, heterogeneity in the cost that individuals pay to punish for selfish behavior allows altruistic behavior to be maintained more easily. Fewer punishers are needed to deter selfish behavior, and the individuals that punish will mostly belong to the class that pays a lower cost to do so. This effect is amplified when individuals that pay a lower cost for punishing inflict a higher punishment. The two population models differ when individuals that pay a low cost for punishing also inflict a lower punishment. In this situation, altruistic behavior becomes harder to maintain in an infinite and well-mixed population. However, this effect does not occur when the population is spatially structured. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. Hierarchical unilamellar vesicles of controlled compositional heterogeneity.

    Directory of Open Access Journals (Sweden)

    Maik Hadorn

    Full Text Available Eukaryotic life contains hierarchical vesicular architectures (i.e. organelles that are crucial for material production and trafficking, information storage and access, as well as energy production. In order to perform specific tasks, these compartments differ among each other in their membrane composition and their internal cargo and also differ from the cell membrane and the cytosol. Man-made structures that reproduce this nested architecture not only offer a deeper understanding of the functionalities and evolution of organelle-bearing eukaryotic life but also allow the engineering of novel biomimetic technologies. Here, we show the newly developed vesicle-in-water-in-oil emulsion transfer preparation technique to result in giant unilamellar vesicles internally compartmentalized by unilamellar vesicles of different membrane composition and internal cargo, i.e. hierarchical unilamellar vesicles of controlled compositional heterogeneity. The compartmentalized giant unilamellar vesicles were subsequently isolated by a separation step exploiting the heterogeneity of the membrane composition and the encapsulated cargo. Due to the controlled, efficient, and technically straightforward character of the new preparation technique, this study allows the hierarchical fabrication of compartmentalized giant unilamellar vesicles of controlled compositional heterogeneity and will ease the development of eukaryotic cell mimics that resemble their natural templates as well as the fabrication of novel multi-agent drug delivery systems for combination therapies and complex artificial microreactors.

  4. Temperature Dependence in Homogeneous and Heterogeneous Nucleation

    Energy Technology Data Exchange (ETDEWEB)

    McGraw R. L.; Winkler, P. M.; Wagner, P. E.

    2017-08-01

    Heterogeneous nucleation on stable (sub-2 nm) nuclei aids the formation of atmospheric cloud condensation nuclei (CCN) by circumventing or reducing vapor pressure barriers that would otherwise limit condensation and new particle growth. Aerosol and cloud formation depend largely on the interaction between a condensing liquid and the nucleating site. A new paper published this year reports the first direct experimental determination of contact angles as well as contact line curvature and other geometric properties of a spherical cap nucleus at nanometer scale using measurements from the Vienna Size Analyzing Nucleus Counter (SANC) (Winkler et al., 2016). For water nucleating heterogeneously on silver oxide nanoparticles we find contact angles around 15 degrees compared to around 90 degrees for the macroscopically measured equilibrium angle for water on bulk silver. The small microscopic contact angles can be attributed via the generalized Young equation to a negative line tension that becomes increasingly dominant with increasing curvature of the contact line. These results enable a consistent theoretical description of heterogeneous nucleation and provide firm insight to the wetting of nanosized objects.

  5. Genetic Heterogeneity in Algerian Human Populations.

    Science.gov (United States)

    Bekada, Asmahan; Arauna, Lara R; Deba, Tahria; Calafell, Francesc; Benhamamouch, Soraya; Comas, David

    2015-01-01

    The demographic history of human populations in North Africa has been characterized by complex processes of admixture and isolation that have modeled its current gene pool. Diverse genetic ancestral components with different origins (autochthonous, European, Middle Eastern, and sub-Saharan) and genetic heterogeneity in the region have been described. In this complex genetic landscape, Algeria, the largest country in Africa, has been poorly covered, with most of the studies using a single Algerian sample. In order to evaluate the genetic heterogeneity of Algeria, Y-chromosome, mtDNA and autosomal genome-wide makers have been analyzed in several Berber- and Arab-speaking groups. Our results show that the genetic heterogeneity found in Algeria is not correlated with geography or linguistics, challenging the idea of Berber groups being genetically isolated and Arab groups open to gene flow. In addition, we have found that external sources of gene flow into North Africa have been carried more often by females than males, while the North African autochthonous component is more frequent in paternally transmitted genome regions. Our results highlight the different demographic history revealed by different markers and urge to be cautious when deriving general conclusions from partial genomic information or from single samples as representatives of the total population of a region.

  6. Genetic heterogeneity of familial hemiplegic migraine

    Energy Technology Data Exchange (ETDEWEB)

    Joutel, A.; Ducros, A.; Delrieu, O.; Maziaceck, J.; Tournier-Lasserve, E. [INSERUM U25, Paris (France); Vahedi, K. [INSERUM U25, Paris (France)]|[Hopital St. Antoine (France); Bousser, M.G. [Hopital St. Antoine, Paris (France); Ponsot, G. [Hopital St. Vincent de Paul, Paris (France); Gouttiere, F. [Hopital Necker-Enfants Malades, Paris (France); Labauge, P. [Clinique Neurologique du C.H. et U. Montpellier-Nimes (France); Mancini, J. [Hopital de la Timone, Marseille (France)] [and others

    1994-12-01

    Familial hemiplegic migraine (FHM) is an autosomal dominant variety of migraine with aura. We previously mapped a gene for this disorder to the short arm of chromosome 19, within a 30-cM interval bracketed by D19S216 and D19S215. Linkage analysis conducted on two large pedigrees did not show any evidence of heterogeneity, despite their clinical differences due to the presence, in one family, of cerebellar ataxia and nystagmus. Herein we report linkage data on seven additional FHM families including another one with cerebellar ataxia. Analysis was conducted with a set of seven markers spanning the D19S216-D19S215 interval. Two-point and multipoint strong evidence for genetic heterogeneity. Strong evidence of linkage was obtained in two families and of absence of linkage in four families. The posterior probability of being of the linked type was >.95 in the first two families and <.01 in four other ones. It was not possible to draw any firm conclusion for the last family. Thus, within the nine families so far tested, four were linked, including those with associated cerebellar ataxia. We could not find any clinical difference between the pure FHM families regardless of whether they were linked. In addition to the demonstration of genetic heterogeneity of FHM, this study also allowed us to establish that the most likely location of the gene was within an interval of 12 cM between D19S413 and D19S226.

  7. Coordinated Energy Management in Heterogeneous Processors

    Directory of Open Access Journals (Sweden)

    Indrani Paul

    2014-01-01

    Full Text Available This paper examines energy management in a heterogeneous processor consisting of an integrated CPU–GPU for high-performance computing (HPC applications. Energy management for HPC applications is challenged by their uncompromising performance requirements and complicated by the need for coordinating energy management across distinct core types – a new and less understood problem. We examine the intra-node CPU–GPU frequency sensitivity of HPC applications on tightly coupled CPU–GPU architectures as the first step in understanding power and performance optimization for a heterogeneous multi-node HPC system. The insights from this analysis form the basis of a coordinated energy management scheme, called DynaCo, for integrated CPU–GPU architectures. We implement DynaCo on a modern heterogeneous processor and compare its performance to a state-of-the-art power- and performance-management algorithm. DynaCo improves measured average energy-delay squared (ED2 product by up to 30% with less than 2% average performance loss across several exascale and other HPC workloads.

  8. Genetic Heterogeneity in Algerian Human Populations.

    Directory of Open Access Journals (Sweden)

    Asmahan Bekada

    Full Text Available The demographic history of human populations in North Africa has been characterized by complex processes of admixture and isolation that have modeled its current gene pool. Diverse genetic ancestral components with different origins (autochthonous, European, Middle Eastern, and sub-Saharan and genetic heterogeneity in the region have been described. In this complex genetic landscape, Algeria, the largest country in Africa, has been poorly covered, with most of the studies using a single Algerian sample. In order to evaluate the genetic heterogeneity of Algeria, Y-chromosome, mtDNA and autosomal genome-wide makers have been analyzed in several Berber- and Arab-speaking groups. Our results show that the genetic heterogeneity found in Algeria is not correlated with geography or linguistics, challenging the idea of Berber groups being genetically isolated and Arab groups open to gene flow. In addition, we have found that external sources of gene flow into North Africa have been carried more often by females than males, while the North African autochthonous component is more frequent in paternally transmitted genome regions. Our results highlight the different demographic history revealed by different markers and urge to be cautious when deriving general conclusions from partial genomic information or from single samples as representatives of the total population of a region.

  9. Postural Tachycardia Syndrome: A Heterogeneous and Multifactorial Disorder

    Science.gov (United States)

    Benarroch, Eduardo E.

    2012-01-01

    Postural tachycardia syndrome (POTS) is defined by a heart rate increment of 30 beats/min or more within 10 minutes of standing or head-up tilt in the absence of orthostatic hypotension; the standing heart rate is often 120 beats/min or higher. POTS manifests with symptoms of cerebral hypoperfusion and excessive sympathoexcitation. The pathophysiology of POTS is heterogeneous and includes impaired sympathetically mediated vasoconstriction, excessive sympathetic drive, volume dysregulation, and deconditioning. POTS is frequently included in the differential diagnosis of chronic unexplained symptoms, such as inappropriate sinus tachycardia, chronic fatigue, chronic dizziness, or unexplained spells in otherwise healthy young individuals. Many patients with POTS also report symptoms not attributable to orthostatic intolerance, including those of functional gastrointestinal or bladder disorders, chronic headache, fibromyalgia, and sleep disturbances. In many of these cases, cognitive and behavioral factors, somatic hypervigilance associated with anxiety, depression, and behavioral amplification contribute to symptom chronicity. The aims of evaluation in patients with POTS are to exclude cardiac causes of inappropriate tachycardia; elucidate, if possible, the most likely pathophysiologic basis of postural intolerance; assess for the presence of treatable autonomic neuropathies; exclude endocrine causes of a hyperadrenergic state; evaluate for cardiovascular deconditioning; and determine the contribution of emotional and behavioral factors to the patient's symptoms. Management of POTS includes avoidance of precipitating factors, volume expansion, physical countermaneuvers, exercise training, pharmacotherapy (fludrocortisone, midodrine, β-blockers, and/or pyridostigmine), and behavioral-cognitive therapy. A literature search of PubMed for articles published from January 1, 1990, to June 15, 2012, was performed using the following terms (or combination of terms): POTS

  10. Information and Heterogeneous Beliefs: Cost of Capital, Trading Volume, and Investor Welfare

    DEFF Research Database (Denmark)

    Christensen, Peter Ove; Qin, Zhenjiang

    advantage of the disagreements and the differences in confidence among investors. This leads to a higher growth in the investors' certainty equivalents and, thus, a higher equilibrium interest rate, whereas the ex ante risk premium on the risky asset is unaffected by the informativeness of the public...

  11. Heterogeneous Concurrent Modeling and Design in Java (Volume 2: Ptolemy II Software Architecture)

    Science.gov (United States)

    2008-04-01

    associated helper. An actor may have multiple helpers to sup- port multiple target languages (C, VHDL , etc.). To achieve readability and...A. Lee, “Gabriel: A Design Envi- ronment for DSP ,” IEEE Micro Magazine, October 1990, vol. 10, no. 5, pp. 28-45. [20] C. H. Brooks and E. A. Lee...United States, pp. 552 - 555, 2000. [64] IEEE DASC 1076.1 Working Group, “ VHDL -A Design Objective Document, version 2.3,” http:/ /www.vhdl.org/analog

  12. Heterogeneous Concurrent Modeling and Design in Java (Volume 3: Ptolemy II Domains)

    Science.gov (United States)

    2008-04-15

    for DSP ,” IEEE Micro Magazine, October 1990, vol. 10, no. 5, pp. 28-45. [19] C. H. Brooks and E. A. Lee, “Ptolemy II Coding Style,” Technical...DASC 1076.1 Working Group, “ VHDL -A Design Objective Document, version 2.3,” http:/ /www.vhdl.org/analog/ftp_files/requirements/DOD_v2.3.txt [64] D...Cambridge, MA, 1966. [138]J. Teich, E. Zitzler, and S. Bhattacharyya, “3D exploration of software schedules for DSP algo- rithms,” In Proceedings of

  13. Heterogeneous traders, price-volume signals, and complex asset price dynamics

    Directory of Open Access Journals (Sweden)

    Frank H. Westerhoff

    2005-01-01

    model reveal that interactions between fundamentalists and chartists may cause intricate endogenous price fluctuations. Contrary to the intuition, we find that chart trading may increase market stability.

  14. Heterogeneous Concurrent Modeling and Design in Java (Volume 1: Introduction to Ptolemy II)

    Science.gov (United States)

    2008-04-01

    domain to be atomic, but internally is composed of an inter- connection of other actors. This was called a wormhole in Ptolemy Classic. package... wormhole ...........................The Ptolemy Classic name for an opaque composite actor. 278 Ptolemy II Index Symbols - in UML 42 # in UML 42...Start 47 welcome window 54 When actor 165 width of a port 170, 277 width of a relation 226, 235, 277 Workspace class 254 wormhole 38, 277 Wright 12 X XML

  15. Intratumor Heterogeneity and Branched Evolution Revealed by Multiregion Sequencing

    DEFF Research Database (Denmark)

    Gerlinger, Marco; Rowan, Andrew J.; Horswell, Stuart

    2012-01-01

    BACKGROUND: Intratumor heterogeneity may foster tumor evolution and adaptation and hinder personalized-medicine strategies that depend on results from single tumor-biopsy samples.METHODSTo examine intratumor heterogeneity, we performed exome sequencing, chromosome aberration analysis, and ploidy ...

  16. Density dependence of clutch size: habitat heterogeneity or individual adjustment?

    NARCIS (Netherlands)

    Both, C.

    1998-01-01

    1. Two hypotheses have been proposed to explain density- dependent patterns in reproduction. The habitat heterogeneity hypothesis (HHH) explains density-dependent reproduction at the population level from poorer quality territories in heterogeneous environments only being occupied at high densities.

  17. Media Distribution in Heterogeneous Environments using IP-Multicast

    OpenAIRE

    Parnes, Peter

    1998-01-01

    This document discusses problems and solutions around distribution of media in heterogeneous environments when using IP-multicast. This document discusses problems and solutions around distribution of media in heterogeneous environments when using IP-multicast.

  18. Meso-design of heterogeneous dielectric material systems: Structure property relationships

    Directory of Open Access Journals (Sweden)

    Jeffrey Baker

    2014-04-01

    Full Text Available Heterogeneous materials are inherently dielectric, and charge distribution and transport in such materials involves complex local fields and polarizations that are remarkably sensitive to morphology and the interaction of conduction and permittivity. Trial and error design of such material systems is time consuming and expensive, and often ineffectual. However, heterogeneous materials are essential for energy conversion and storage, and they have become the foundation for major advances in the performance of devices such as batteries, fuel cells, separation membranes, and solar cells. The present paper presents some relationships in support of rational design based on an extensive experimental validation of the concepts and analysis that form a foundation for that design. Salient results include the prediction and confirmation of volume fraction effects (including nondilute mixtures, and the prediction and direct measurement of surface charge effects at internal interfaces as a function of constituent morphology and orientation.

  19. Bronchoscopic lung volume reduction

    Directory of Open Access Journals (Sweden)

    M. I. Polkey

    2006-12-01

    Full Text Available Surgical lung volume reduction can improve exercise performance and forced expiratory volume in one second in patients with emphysema. However, the procedure is associated with a 5% mortality rate and a nonresponse rate of 25%. Accordingly, interest has focused on alternative ways of reducing lung volume. Two principle approaches are used: collapse of the diseased area using blockers placed endobronchially and the creation of extrapulmonary pathways. Preliminary data from the former approach suggest that it can be successful and that the magnitude of success is related to reduction in dynamic hyperinflation.

  20. Nota Editorial Volume X

    OpenAIRE

    Galinha,Iolanda Costa

    2014-01-01

    Neste momento de fecho do volume X da Psique, esta nota editorial tem como primeira finalidade agradecer aos especialistas em Psicologia, envolvidos no processo de revisão, selecção, e reformulação dos artigos publicados neste volume da Psique. Referimo-nos, naturalmente, ao Conselho Editorial da Psique, que foi o responsável por nos apoiar de perto neste processo ambicioso de promover, em simultâneo, a celeridade e a qualidade dos artigos a publicar neste volume da Psique. ...

  1. Evaluation of PET texture features with heterogeneous phantoms: complementarity and effect of motion and segmentation method

    Science.gov (United States)

    Carles, M.; Torres-Espallardo, I.; Alberich-Bayarri, A.; Olivas, C.; Bello, P.; Nestle, U.; Martí-Bonmatí, L.

    2017-01-01

    A major source of error in quantitative PET/CT scans of lung cancer tumors is respiratory motion. Regarding the variability of PET texture features (TF), the impact of respiratory motion has not been properly studied with experimental phantoms. The primary aim of this work was to evaluate the current use of PET texture analysis for heterogeneity characterization in lesions affected by respiratory motion. Twenty-eight heterogeneous lesions were simulated by a mixture of alginate and 18 F-fluoro-2-deoxy-D-glucose (FDG). Sixteen respiratory patterns were applied. Firstly, the TF response for different heterogeneous phantoms and its robustness with respect to the segmentation method were calculated. Secondly, the variability for TF derived from PET image with (gated, G-) and without (ungated, U-) motion compensation was analyzed. Finally, TF complementarity was assessed. In the comparison of TF derived from the ideal contour with respect to TF derived from 40%-threshold and adaptive-threshold PET contours, 7/8 TF showed strong linear correlation (LC) (p    0.75), despite a significant volume underestimation. Independence of lesion movement (LC in 100% of the combined pairs of movements, p    0.9, p  PET/CT images. Despite inaccurate volume delineation, TF derived from 40% and COA contours could be reliable for their prognostic use. The TF that exhibited simultaneous added value and independence of lesion movement were ENG and ENT computed from the G-image. Their use is therefore recommended for heterogeneity quantification of lesions affected by respiratory motion.

  2. Dosimetric verification of a high dose rate brachytherapy treatment planning system in homogeneous and heterogeneous media.

    Science.gov (United States)

    Uniyal, S C; Sharma, S D; Naithani, U C

    2013-03-01

    To verify the dosimetric accuracy of treatment plans in high dose rate (HDR) brachytherapy by using Gafchromic EBT2 film and to demonstrate the adequacy of dose calculations of a commercial treatment planning system (TPS) in a heterogeneous medium. Absorbed doses at chosen points in anatomically different tissue equivalent phantoms were measured using Gafchromic EBT2 film. In one case, tandem ovoid brachytherapy was performed in a homogeneous cervix phantom, whereas in the other, organ heterogeneities were introduced in a phantom to replicate the upper thorax for esophageal brachytherapy treatment. A commercially available TPS was used to perform treatment planning in each case and the EBT2 films were irradiated with the HDR Ir-192 brachytherapy source. Film measurements in the cervix phantom were found to agree with the TPS calculated values within 3% in the clinically relevant volume. In the thorax phantom, the presence of surrounding heterogeneities was not seen to affect the dose distribution in the volume being treated, whereas, a little dose perturbation was observed at the lung surface. Doses to the spinal cord and to the sternum bone were overestimated and underestimated by 14.6% and 16.5% respectively by the TPS relative to the film measurements. At the trachea wall facing the esophagus, a dose reduction of 10% was noticed in the measurements. The dose calculation accuracy of the TPS was confirmed in homogeneous medium, whereas, it was proved inadequate to produce correct dosimetric results in conditions of tissue heterogeneity. Copyright © 2012 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  3. Combinatoric and mean field analysis of heterogeneous self assembly

    Science.gov (United States)

    2013-08-01

    REPORT Combinatoric and mean-field analysis of heterogeneous self-assembly 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: We present a stochastic analysis... Combinatoric and mean-field analysis of heterogeneous self-assembly Report Title ABSTRACT We present a stochastic analysis of heterogeneous

  4. Heterogeneous Catalysis: A Central Science for a Sustainable Future.

    Science.gov (United States)

    Friend, Cynthia M; Xu, Bingjun

    2017-03-21

    Developing active, selective, and energy efficient heterogeneous catalytic processes is key to a sustainable future because heterogeneous catalysis is at the center of the chemicals and energy industries. The design, testing, and implementation of robust and selective heterogeneous catalytic processes based on insights from fundamental studies could have a tremendous positive impact on the world.

  5. Effects of Population Heterogeneity on Accuracy of DIF Detection

    Science.gov (United States)

    Oliveri, María Elena; Ercikan, Kadriye; Zumbo, Bruno D.

    2014-01-01

    Heterogeneity within English language learners (ELLs) groups has been documented. Previous research on differential item functioning (DIF) analyses suggests that accurate DIF detection rates are reduced greatly when groups are heterogeneous. In this simulation study, we investigated the effects of heterogeneity within linguistic (ELL) groups on…

  6. Heterogeneity in Social Dilemmas: The Case of Social Support

    NARCIS (Netherlands)

    Vogt, S.B.

    2007-01-01

    Heterogeneous Social Dilemmas: The Case of Social Support” studies the level of social support between heterogeneous actors. We consider heterogeneity with respect to several individual properties: the likelihood of needing support, the costs of providing support, and the benefits from receiving

  7. Heterogeneity of DNA Distribution Pattern in Renal Tumours

    Directory of Open Access Journals (Sweden)

    Hans Nenning

    1997-01-01

    Full Text Available The presence of intratumoural heterogeneity in DNA distribution patterns has been accepted. However, most previous studies have not taken this fact into consideration. The value of DNA cytometry depends on its reproducibility. This could be influenced by heterogeneity failure. The aim of the present study is to evaluate intratumoural heterogeneity in renal cell cancer.

  8. Size effects on free vibration of heterogeneous beams

    Directory of Open Access Journals (Sweden)

    Hassanati Bahman

    2018-01-01

    Full Text Available In this paper the influence of microstructure on the free vibration of geometrically similar heterogeneous beams with free-free boundary conditions was numerically investigated by detailed finite element analysis (FEA to identify and quantify any effect of beam size on transverse modal frequencies when the microstructural scale is comparable to the overall size. ANSYS Mechanical APDL was used to generate specific unit cells at the microstructural scale comprised of two isotropic materials with different material properties. Unit cell variants containing voids and inclusions were considered. At the macroscopic scale, four beam sizes consisting of one, two, three or four layers of defined unit cells were represented by repeatedly regenerating the unit cell as necessary. In all four beam sizes the aspect ratio was kept constant. Changes to the volume fractions of each material were introduced while keeping the homogenized properties of the beam fixed. The influence of the beam surface morphology on the results was also investigated. The ANSYS results were compared with the analytical results from solution to Timoshenko beam and nonlocal Timoshenko beam as well as numerical results for a Micropolar beam. In nonlocal Timoshenko beams the Eringen’s small length scale coefficients were estimated for some of the studied models. Numerical analyses based on Micropolar theory were carried out to study the modal frequencies and a method was suggested to estimate characteristic length in bending and coupling number via transverse vibration which verifies the use of Micropolar elasticity theory in dynamic analysis.

  9. Spatial heterogeneity of tungsten transmutation in a fusion device

    Science.gov (United States)

    Gilbert, M. R.; Sublet, J.-Ch.; Dudarev, S. L.

    2017-04-01

    Accurately quantifying the transmutation rate of tungsten (W) under neutron irradiation is a necessary requirement in the assessment of its performance as an armour material in a fusion power plant. The usual approach of calculating average responses, assuming large, homogenised material volumes, is insufficient to capture the full complexity of the transmutation picture in the context of a realistic fusion power plant design, particularly for rhenium (Re) production from W. Combined neutron transport and inventory simulations for representative spatially heterogeneous high-resolution models of a fusion power plant show that the production rate of Re is strongly influenced by the surrounding local spatial environment. Localised variation in neutron moderation (slowing down) due to structural steel and coolant, particularly water, can dramatically increase Re production because of the huge cross sections of giant resolved resonances in the neutron-capture reaction of 186W at low neutron energies. Calculations using cross section data corrected for temperature (Doppler) effects suggest that temperature may have a relatively lesser influence on transmutation rates.

  10. Unveiling CO2 heterogeneous freezing plumes during champagne cork popping.

    Science.gov (United States)

    Liger-Belair, Gérard; Cordier, Daniel; Honvault, Jacques; Cilindre, Clara

    2017-09-14

    Cork popping from clear transparent bottles of champagne stored at different temperatures (namely, 6, 12, and 20 °C) was filmed through high-speed video imaging in the visible light spectrum. During the cork popping process, a plume mainly composed of gaseous CO2 with traces of water vapour freely expands out of the bottleneck through ambient air. Most interestingly, for the bottles stored at 20 °C, the characteristic grey-white cloud of fog classically observed above the bottlenecks of champagne stored at lower temperatures simply disappeared. It is replaced by a more evanescent plume, surprisingly blue, starting from the bottleneck. We suggest that heterogeneous freezing of CO2 occurs on ice water clusters homogeneously nucleated in the bottlenecks, depending on the saturation ratio experienced by gas-phase CO2 after adiabatic expansion (indeed highly bottle temperature dependent). Moreover, and as observed for the bottles stored at 20 °C, we show that the freezing of only a small portion of all the available CO2 is able to pump the energy released through adiabatic expansion, thus completely inhibiting the condensation of water vapour found in air packages adjacent to the gas volume gushing out of the bottleneck.

  11. Identifying and Quantifying Heterogeneity in High Content Analysis: Application of Heterogeneity Indices to Drug Discovery

    Science.gov (United States)

    Gough, Albert H.; Chen, Ning; Shun, Tong Ying; Lezon, Timothy R.; Boltz, Robert C.; Reese, Celeste E.; Wagner, Jacob; Vernetti, Lawrence A.; Grandis, Jennifer R.; Lee, Adrian V.; Stern, Andrew M.; Schurdak, Mark E.; Taylor, D. Lansing

    2014-01-01

    One of the greatest challenges in biomedical research, drug discovery and diagnostics is understanding how seemingly identical cells can respond differently to perturbagens including drugs for disease treatment. Although heterogeneity has become an accepted characteristic of a population of cells, in drug discovery it is not routinely evaluated or reported. The standard practice for cell-based, high content assays has been to assume a normal distribution and to report a well-to-well average value with a standard deviation. To address this important issue we sought to define a method that could be readily implemented to identify, quantify and characterize heterogeneity in cellular and small organism assays to guide decisions during drug discovery and experimental cell/tissue profiling. Our study revealed that heterogeneity can be effectively identified and quantified with three indices that indicate diversity, non-normality and percent outliers. The indices were evaluated using the induction and inhibition of STAT3 activation in five cell lines where the systems response including sample preparation and instrument performance were well characterized and controlled. These heterogeneity indices provide a standardized method that can easily be integrated into small and large scale screening or profiling projects to guide interpretation of the biology, as well as the development of therapeutics and diagnostics. Understanding the heterogeneity in the response to perturbagens will become a critical factor in designing strategies for the development of therapeutics including targeted polypharmacology. PMID:25036749

  12. Environmental chemistry: Volume A

    Energy Technology Data Exchange (ETDEWEB)

    Yen, T.F.

    1999-08-01

    This is an extensive introduction to environmental chemistry for engineering and chemical professionals. The contents of Volume A include a brief review of basic chemistry prior to coverage of litho, atmo, hydro, pedo, and biospheres.

  13. Integers annual volume 2013

    CERN Document Server

    Landman, Bruce

    2014-01-01

    ""Integers"" is a refereed online journal devoted to research in the area of combinatorial number theory. It publishes original research articles in combinatorics and number theory. This work presents all papers of the 2013 volume in book form.

  14. Reachable volume RRT

    KAUST Repository

    McMahon, Troy

    2015-05-01

    © 2015 IEEE. Reachable volumes are a new technique that allows one to efficiently restrict sampling to feasible/reachable regions of the planning space even for high degree of freedom and highly constrained problems. However, they have so far only been applied to graph-based sampling-based planners. In this paper we develop the methodology to apply reachable volumes to tree-based planners such as Rapidly-Exploring Random Trees (RRTs). In particular, we propose a reachable volume RRT called RVRRT that can solve high degree of freedom problems and problems with constraints. To do so, we develop a reachable volume stepping function, a reachable volume expand function, and a distance metric based on these operations. We also present a reachable volume local planner to ensure that local paths satisfy constraints for methods such as PRMs. We show experimentally that RVRRTs can solve constrained problems with as many as 64 degrees of freedom and unconstrained problems with as many as 134 degrees of freedom. RVRRTs can solve problems more efficiently than existing methods, requiring fewer nodes and collision detection calls. We also show that it is capable of solving difficult problems that existing methods cannot.

  15. Bird diversity and environmental heterogeneity in North America: A test of the area-heterogeneity trade-off

    Science.gov (United States)

    Rachel Chocron; Curtis H. Flather; Ronen Kadmon

    2015-01-01

    Aim: Deterministic niche theory predicts that increasing environmental heterogeneity increases species richness. In contrast, a recent stochastic model suggests that heterogeneity has a unimodal effect on species richness since high levels of heterogeneity reduce the effective area available per species, thereby increasing the likelihood of stochastic...

  16. Emerging heterogeneous integrated photonic platforms on silicon

    Directory of Open Access Journals (Sweden)

    Fathpour Sasan

    2015-05-01

    Full Text Available Silicon photonics has been established as a mature and promising technology for optoelectronic integrated circuits, mostly based on the silicon-on-insulator (SOI waveguide platform. However, not all optical functionalities can be satisfactorily achieved merely based on silicon, in general, and on the SOI platform, in particular. Long-known shortcomings of silicon-based integrated photonics are optical absorption (in the telecommunication wavelengths and feasibility of electrically-injected lasers (at least at room temperature. More recently, high two-photon and free-carrier absorptions required at high optical intensities for third-order optical nonlinear effects, inherent lack of second-order optical nonlinearity, low extinction ratio of modulators based on the free-carrier plasma effect, and the loss of the buried oxide layer of the SOI waveguides at mid-infrared wavelengths have been recognized as other shortcomings. Accordingly, several novel waveguide platforms have been developing to address these shortcomings of the SOI platform. Most of these emerging platforms are based on heterogeneous integration of other material systems on silicon substrates, and in some cases silicon is integrated on other substrates. Germanium and its binary alloys with silicon, III–V compound semiconductors, silicon nitride, tantalum pentoxide and other high-index dielectric or glass materials, as well as lithium niobate are some of the materials heterogeneously integrated on silicon substrates. The materials are typically integrated by a variety of epitaxial growth, bonding, ion implantation and slicing, etch back, spin-on-glass or other techniques. These wide range of efforts are reviewed here holistically to stress that there is no pure silicon or even group IV photonics per se. Rather, the future of the field of integrated photonics appears to be one of heterogenization, where a variety of different materials and waveguide platforms will be used for

  17. Brachytherapy dose measurements in heterogeneous tissues

    Energy Technology Data Exchange (ETDEWEB)

    Paiva F, G.; Luvizotto, J.; Salles C, T.; Guimaraes A, P. C.; Dalledone S, P. de T.; Yoriyaz, H. [Instituto de Pesquisas Energeticas e Nucleares / CNEN, Av. Lineu Prestes 2242, Cidade Universitaria, 05508-000 Sao Paulo (Brazil); Rubo, R., E-mail: gabrielpaivafonseca@gmail.com [Hospital das Clinicas da Faculdade de Medicina da Universidade de Sao Paulo, 05403-900 Sao Paulo (Brazil)

    2014-08-15

    Recently, Beau lieu et al. published an article providing guidance for Model-Based Dose Calculation Algorithms (MBDCAs), where tissue heterogeneity considerations are addressed. It is well-known that T G-43 formalism which considers only water medium is limited and significant dose differences have been found comparing both methodologies. The aim of the present work is to experimentally quantify dose values in heterogeneous medium using different dose measurement methods and techniques and compare them with those obtained with Monte Carlo simulations. Experiments have been performed using a Nucletron micro Selectron-Hdr Ir-192 brachytherapy source and a heterogeneous phantom composed by PMMA and different tissue equivalent cylinders like bone, lungs and muscle. Several dose measurements were obtained using tissue equivalent materials with height 1.8 cm and 4.3 cm positioned between the radiation source and the detectors. Radiochromic films, TLDs and MOSFET S have been used for the dose measurements. Film dosimetry has been performed using two methodologies: a) linearization for dose-response curve based on calibration curves to create a functional form that linearize s the dose response and b) 177 multichannel analysis dosimetry where the multiple color channels are analyzed allowing to address not only disturbances in the measurements caused by thickness variation in the film layer, but also, separate other external influences in the film response. All experiments have been simulated using the MCNP5 Monte Carlo radiation transport code. Comparison of experimental results are in good agreement with calculated dose values with differences less than 6% for almost all cases. (Author)

  18. Subunit heterogeneity in the lima bean lectin.

    Science.gov (United States)

    Roberts, D D; Etzler, M E; Goldstein, I J

    1982-08-10

    Three forms of lectin (components I, II, and III) from lima beans (Phaseolus lunatus) have been purified on an affinity support containing the synthetic type A blood group trisaccharide alpha-D-GalNAc-(1 leads to 3)-[alpha-L-Fuc-(1 leads to 2)]-beta-D-Gal-(1 leads to). Conversion of components I and II to component III has been achieved by reduction in 10(-2) M dithiothreitol. Isoelectric focusing of lima bean lectin in the presence of 8 M urea and beta-mercaptoethanol revealed charge heterogeneity of the lectin subunits. Three major subunit classes of apparent pI 7.05, 6.65, and 6.45, designated alpha, beta, and alpha', respectively, were identified; they occur in a relative abundance of 2:5:3. Green lima beans harvested before maturity lacked the alpha' subunit (pI 6.45) which appears to accumulate during seed maturation. The three subunits are glycoproteins of identical size and immunochemical reactivity. Identical NH2-terminal sequences were found for the three subunits. Amino acid analysis and tryptic peptide mapping indicated that the observed charge heterogeneity is probably due to differences in the primary structure of the subunits. Studies of subunit composition of charge isolectins provided evidence of nonrandom subunit assembly. A model is proposed involving pairing of a pI 6.65 subunit with either a pI 7.06 or 6.45 subunit to form dimeric units. Possible roles for subunit heterogeneity and ordered subunit assembly in determining the metal and sugar binding properties of lima bean lectin are discussed.

  19. Mathematical analysis of epidemiological models with heterogeneity

    Energy Technology Data Exchange (ETDEWEB)

    Van Ark, J.W.

    1992-01-01

    For many diseases in human populations the disease shows dissimilar characteristics in separate subgroups of the population; for example, the probability of disease transmission for gonorrhea or AIDS is much higher from male to female than from female to male. There is reason to construct and analyze epidemiological models which allow this heterogeneity of population, and to use these models to run computer simulations of the disease to predict the incidence and prevalence of the disease. In the models considered here the heterogeneous population is separated into subpopulations whose internal and external interactions are homogeneous in the sense that each person in the population can be assumed to have all average actions for the people of that subpopulation. The first model considered is an SIRS models; i.e., the Susceptible can become Infected, and if so he eventually Recovers with temporary immunity, and after a period of time becomes Susceptible again. Special cases allow for permanent immunity or other variations. This model is analyzed and threshold conditions are given which determine whether the disease dies out or persists. A deterministic model is presented; this model is constructed using difference equations, and it has been used in computer simulations for the AIDS epidemic in the homosexual population in San Francisco. The homogeneous version and the heterogeneous version of the differential-equations and difference-equations versions of the deterministic model are analyzed mathematically. In the analysis, equilibria are identified and threshold conditions are set forth for the disease to die out if the disease is below the threshold so that the disease-free equilibrium is globally asymptotically stable. Above the threshold the disease persists so that the disease-free equilibrium is unstable and there is a unique endemic equilibrium.

  20. Mantle heterogeneity and the D" discontinuity

    Science.gov (United States)

    Grocholski, B.; Catalli, K.; Shim, S.

    2011-12-01

    The observation of the D'' discontinuity, especially in regions of high shear-wave velocity, has been attributed to the thermal response of the perovskite (Pv) to post-perovskite (PPv) transition. This interpretation requires a large and positive Clapeyron slope in addition to a narrow two-phase region to be seismically detectable. Mineral physics experiments of this system have been evolving to investigate both chemical and mineralogical variations possible for the D'' region of the mantle. This has come with some surprises, including two-phase regions that would span hundreds of km depth in aluminum (Tateno et al., 2005), iron (Catalli et al., 2009), and mantle-relevant aluminum-iron bearing systems (Catalli et al., 2009, Andrault et al., 2010). Our most recent experimental results suggest that other minerals play an important role in partitioning iron and aluminum to decrease the thickness of the mixed phase region such that the transition will be seismically detectable. In particular, aluminum stabilizing Pv makes it challenging for the PPv transition to be detectable in a homogeneous (pyrolitic) mantle. However, subduction of oceanic lithosphere injects heterogeneous rock types (basaltic, harzburgitic) that are more likely to have seismically detectable transitions. Therefore, the mantle heterogeneities originated from recycled oceanic lithosphere may be responsible for the D'' discontinuity. Enriched, basalt-like compositions would be expected to have a discontinuity ˜400 km above the core-mantle boundary (CMB) possibly controlled by the appearance of a PbO2-like structured silica capable of dissolving large amounts of aluminum. Depleted, harzburgite-like mantle compositions are likely to have a transition ˜100 km above the CMB, which is sharp due to iron partitioning into ferropericlase combined with a low aluminum content. This picture of heterogeneity in the lowermost mantle not only helps explains the seismic results on the D'' discontinuity itself, but

  1. Quantum Heterogeneous Computing for Satellite Positioning Optimization

    Science.gov (United States)

    Bass, G.; Kumar, V.; Dulny, J., III

    2016-12-01

    Hard optimization problems occur in many fields of academic study and practical situations. We present results in which quantum heterogeneous computing is used to solve a real-world optimization problem: satellite positioning. Optimization problems like this can scale very rapidly with problem size, and become unsolvable with traditional brute-force methods. Typically, such problems have been approximately solved with heuristic approaches; however, these methods can take a long time to calculate and are not guaranteed to find optimal solutions. Quantum computing offers the possibility of producing significant speed-up and improved solution quality. There are now commercially available quantum annealing (QA) devices that are designed to solve difficult optimization problems. These devices have 1000+ quantum bits, but they have significant hardware size and connectivity limitations. We present a novel heterogeneous computing stack that combines QA and classical machine learning and allows the use of QA on problems larger than the quantum hardware could solve in isolation. We begin by analyzing the satellite positioning problem with a heuristic solver, the genetic algorithm. The classical computer's comparatively large available memory can explore the full problem space and converge to a solution relatively close to the true optimum. The QA device can then evolve directly to the optimal solution within this more limited space. Preliminary experiments, using the Quantum Monte Carlo (QMC) algorithm to simulate QA hardware, have produced promising results. Working with problem instances with known global minima, we find a solution within 8% in a matter of seconds, and within 5% in a few minutes. Future studies include replacing QMC with commercially available quantum hardware and exploring more problem sets and model parameters. Our results have important implications for how heterogeneous quantum computing can be used to solve difficult optimization problems in any

  2. Emerging heterogeneous integrated photonic platforms on silicon

    Science.gov (United States)

    Fathpour, Sasan

    2015-05-01

    Silicon photonics has been established as a mature and promising technology for optoelectronic integrated circuits, mostly based on the silicon-on-insulator (SOI) waveguide platform. However, not all optical functionalities can be satisfactorily achieved merely based on silicon, in general, and on the SOI platform, in particular. Long-known shortcomings of silicon-based integrated photonics are optical absorption (in the telecommunication wavelengths) and feasibility of electrically-injected lasers (at least at room temperature). More recently, high two-photon and free-carrier absorptions required at high optical intensities for third-order optical nonlinear effects, inherent lack of second-order optical nonlinearity, low extinction ratio of modulators based on the free-carrier plasma effect, and the loss of the buried oxide layer of the SOI waveguides at mid-infrared wavelengths have been recognized as other shortcomings. Accordingly, several novel waveguide platforms have been developing to address these shortcomings of the SOI platform. Most of these emerging platforms are based on heterogeneous integration of other material systems on silicon substrates, and in some cases silicon is integrated on other substrates. Germanium and its binary alloys with silicon, III-V compound semiconductors, silicon nitride, tantalum pentoxide and other high-index dielectric or glass materials, as well as lithium niobate are some of the materials heterogeneously integrated on silicon substrates. The materials are typically integrated by a variety of epitaxial growth, bonding, ion implantation and slicing, etch back, spin-on-glass or other techniques. These wide range of efforts are reviewed here holistically to stress that there is no pure silicon or even group IV photonics per se. Rather, the future of the field of integrated photonics appears to be one of heterogenization, where a variety of different materials and waveguide platforms will be used for different purposes with

  3. Reporting tumor molecular heterogeneity in histopathological diagnosis.

    Directory of Open Access Journals (Sweden)

    Andrea Mafficini

    Full Text Available Detection of molecular tumor heterogeneity has become of paramount importance with the advent of targeted therapies. Analysis for detection should be comprehensive, timely and based on routinely available tumor samples.To evaluate the diagnostic potential of targeted multigene next-generation sequencing (TM-NGS in characterizing gastrointestinal cancer molecular heterogeneity.35 gastrointestinal tract tumors, five of each intestinal type gastric carcinomas, pancreatic ductal adenocarcinomas, pancreatic intraductal papillary mucinous neoplasms, ampulla of Vater carcinomas, hepatocellular carcinomas, cholangiocarcinomas, pancreatic solid pseudopapillary tumors were assessed for mutations in 46 cancer-associated genes, using Ion Torrent semiconductor-based TM-NGS. One ampulla of Vater carcinoma cell line and one hepatic carcinosarcoma served to assess assay sensitivity. TP53, PIK3CA, KRAS, and BRAF mutations were validated by conventional Sanger sequencing.TM-NGS yielded overlapping results on matched fresh-frozen and formalin-fixed paraffin-embedded (FFPE tissues, with a mutation detection limit of 1% for fresh-frozen high molecular weight DNA and 2% for FFPE partially degraded DNA. At least one somatic mutation was observed in all tumors tested; multiple alterations were detected in 20/35 (57% tumors. Seven cancers displayed significant differences in allelic frequencies for distinct mutations, indicating the presence of intratumor molecular heterogeneity; this was confirmed on selected samples by immunohistochemistry of p53 and Smad4, showing concordance with mutational analysis.TM-NGS is able to detect and quantitate multiple gene alterations from limited amounts of DNA, moving one step closer to a next-generation histopathologic diagnosis that integrates morphologic, immunophenotypic, and multigene mutational analysis on routinely processed tissues, essential for personalized cancer therapy.

  4. The Influence of Human Heterogeneity to Information Spreading

    Science.gov (United States)

    Zhu, Zhi-Qiang; Liu, Chuan-Jian; Wu, Jian-Liang; Xu, Jin; Liu, Bin

    2014-03-01

    Humans are an integral part of the wide world and material areas, and morphological difference is widespread. In this paper, we propose a model to emphasize the influence of human heterogeneity to information spreading on social networks, and the properties including memory effects, social reinforcement, non-redundancy and human heterogeneity are taken into account. Simulation results indicate that the small-world networks generate the most effective spreading for the stronger human heterogeneity; however, for the weaker human heterogeneity, the regular networks will be more effective. In addition, for a given BA scale-free network, the stronger human heterogeneity will be more conducive to information spreading.

  5. Homogeneous and non-local heterogeneous transport phenomena with VAT application analysis

    Energy Technology Data Exchange (ETDEWEB)

    Catton, I.; Travkin, V.S. [Univ. of California, Los Angeles, CA (United States)

    1997-12-31

    Some fundamental questions about the mathematical description of transport phenomena in heterogeneous media are addressed to highlight the importance of the smallest scale, of using the correct equations and of choosing a consistent set of scaling parameters. Micro-pore flow is treated using a viscosity correlation that properly treats the near wall region in a capillary. Equations resulting from use of volume averaging theory (VAT) are compared with exact solutions and it shown that certain terms normally ignored must be retained. A consistent set of scaling parameters are derived and shown to yield consistent results over a wide range of different media morphologies.

  6. Comparison of fMRI analysis methods for heterogeneous BOLD responses in block design studies.

    Science.gov (United States)

    Liu, Jia; Duffy, Ben A; Bernal-Casas, David; Fang, Zhongnan; Lee, Jin Hyung

    2017-02-15

    A large number of fMRI studies have shown that the temporal dynamics of evoked BOLD responses can be highly heterogeneous. Failing to model heterogeneous responses in statistical analysis can lead to significant errors in signal detection and characterization and alter the neurobiological interpretation. However, to date it is not clear that, out of a large number of options, which methods are robust against variability in the temporal dynamics of BOLD responses in block-design studies. Here, we used rodent optogenetic fMRI data with heterogeneous BOLD responses and simulations guided by experimental data as a means to investigate different analysis methods' performance against heterogeneous BOLD responses. Evaluations are carried out within the general linear model (GLM) framework and consist of standard basis sets as well as independent component analysis (ICA). Analyses show that, in the presence of heterogeneous BOLD responses, conventionally used GLM with a canonical basis set leads to considerable errors in the detection and characterization of BOLD responses. Our results suggest that the 3rd and 4th order gamma basis sets, the 7th to 9th order finite impulse response (FIR) basis sets, the 5th to 9th order B-spline basis sets, and the 2nd to 5th order Fourier basis sets are optimal for good balance between detection and characterization, while the 1st order Fourier basis set (coherence analysis) used in our earlier studies show good detection capability. ICA has mostly good detection and characterization capabilities, but detects a large volume of spurious activation with the control fMRI data. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. Heterogeneous Beliefs, Public Information, and Option Markets

    DEFF Research Database (Denmark)

    Qin, Zhenjiang

    rate in the investors’ certainty equivalents and, thus, a higher equilibrium interest rate. The public infor- mation system facilitates improved dynamic trading opportunities in option markets based on the heterogeneously updated posterior beliefs. With an intermediate signal precision and the option...... with intermediate strike price, the highest efficiency of side-betting is achieved, re‡ected by a unique maximum point of the ex ante equilibrium interest rate. The public signal precision affects ex ante equilibrium risk premium only via its relationship with option....

  8. Multiscale modelling in computational heterogeneous catalysis.

    Science.gov (United States)

    Keil, F J

    2012-01-01

    The goal of multiscale modelling of heterogeneous catalytic reactors is the prediction of all steps, starting from the reaction mechanism at the active centre, the rates of reaction, adsorption and diffusion processes inside the porous system of the catalyst support, based on first principles, quantum chemistry, force field simulations and macroscopic differential equations. The progress in these fields of research will be presented, including linking models between the various levels of description. Alkylation of benzene will be used as an example to demonstrate the various approaches from the active centre to the reactor.

  9. HIGH TEMPERATURE, HIGH POWER HETEROGENEOUS NUCLEAR REACTOR

    Science.gov (United States)

    Hammond, R.P.; Wykoff, W.R.; Busey, H.M.

    1960-06-14

    A heterogeneous nuclear reactor is designed comprising a stationary housing and a rotatable annular core being supported for rotation about a vertical axis in the housing, the core containing a plurality of radial fuel- element supporting channels, the cylindrical empty space along the axis of the core providing a central plenum for the disposal of spent fuel elements, the core cross section outer periphery being vertically gradated in radius one end from the other to provide a coolant duct between the core and the housing, and means for inserting fresh fuel elements in the supporting channels under pressure and while the reactor is in operation.

  10. Cooperative Radio Resource Management for Heterogeneous Networks

    DEFF Research Database (Denmark)

    Mihovska, Albena D.; Tragos, Elias; Luo, Jijun

    2009-01-01

    that an interworking model is flexible and generic enough to include any new type of network that might be designed in the future and that will require inclusion in the heterogeneous domain. Finally, ubiquitous communication systems and the challenge to deploy them successfully bring also the problem of how to manage...... of the network’s resources. This is also the reason why researchers look for systems that are adaptive and flexible and provide coverage in various deployment modes (wide area, metropolitan area and local area). Cooperation and coexistence then extends from interworking between different PHY layer modes...

  11. Heterogeneity of demand and product innovation

    Directory of Open Access Journals (Sweden)

    Thiago Caliari

    Full Text Available Abstract This paper discusses the relationship between heterogeneity of demand regarding choice procedures and product innovation. We propose an evolutionary model showing how consumers with imperfect information chose and select differentiated goods. The model shows the role of information and choice procedures and its relation with the innovative process. The price plays an important role, but the quality of information, error tolerance and criteria for preference ordering are important determinants of the performance of firms in an industry with product innovation.

  12. Understanding as Integration of Heterogeneous Representations

    Science.gov (United States)

    Martínez, Sergio F.

    2014-03-01

    The search for understanding is a major aim of science. Traditionally, understanding has been undervalued in the philosophy of science because of its psychological underpinnings; nowadays, however, it is widely recognized that epistemology cannot be divorced from psychology as sharp as traditional epistemology required. This eliminates the main obstacle to give scientific understanding due attention in philosophy of science. My aim in this paper is to describe an account of scientific understanding as an emergent feature of our mastering of different (causal) explanatory frameworks that takes place through the mastering of scientific practices. Different practices lead to different kinds of representations. Such representations are often heterogeneous. The integration of such representations constitute understanding.

  13. Genetic heterogeneity in Pakistani microcephaly families

    DEFF Research Database (Denmark)

    Sajid Hussain, M; Bakhtiar, Syeda Marriam; Farooq, Muhammad

    2013-01-01

    Autosomal recessive primary microcephaly (MCPH) is caused by mutations in at least eight different genes involved either in cell division or DNA repair. Most mutations are identified in consanguine families from Pakistan, Iran and India. To further assess their genetic heterogeneity and mutational...... spectra, we have analyzed 57 consanguine Pakistani MCPH families. In 34 MCPH families, we detected linkage to five out of the eight well-characterized disease loci and identified mutations in 27 families, leaving seven families without mutations in the coding exons of the presumably underlying MCPH genes...

  14. Cooperative networking in a heterogeneous wireless medium

    CERN Document Server

    Ismail, Muhammad

    2013-01-01

    This brief focuses on radio resource allocation in a heterogeneous wireless medium. It presents radio resource allocation algorithms with decentralized implementation, which support both single-network and multi-homing services. The brief provides a set of cooperative networking algorithms, which rely on the concepts of short-term call traffic load prediction, network cooperation, convex optimization, and decomposition theory. In the proposed solutions, mobile terminals play an active role in the resource allocation operation, instead of their traditional role as passive service recipients in the networking environment.

  15. HETEROGENIC SERUM, AGE, AND MULTIPLICATION OF FIBROBLASTS.

    Science.gov (United States)

    Carrel, A; Ebeling, A H

    1922-01-01

    The presence in a culture medium of heterogenic serum of various concentrations exerts a definite influence on the rate of multiplication of fibroblasts. Dog serum does not inhibit the growth of See PDF for Structure chicken fibroblasts markedly until its concentration reaches 15 per cent. Beyond this figure, each increase of the concentration brings about a rapid decrease in the rate of cell multiplication. When the concentration reaches from 30 to 45 per cent, no growth takes place. The inhibiting action of cat serum begins to manifest itself at a concentration of 25 per cent and prevents cell proliferation completely at a concentration of 55 and 60 per cent. The ratio, See PDF for Equation can be taken as expressing the action of the serum on fibroblast multiplication; that is, as the growth index of the serum. See PDF for Structure The inhibiting influence of heterogenic serum was found to vary in direct ratio to the age of the animal from which it was obtained. The rate of proliferation of chicken fibroblasts was studied comparatively in media containing varied concentrations of serum from young and old animals. For each concentration of serum, the rate of growth in the serum of the old animal was expressed in relation to the rate of growth in the serum of the young animal. When cat serum was used, the curve obtained in plotting this ratio in ordinates and the serum concentration in abscissae showed a rapid increase in the inhibiting action of the old serum as soon as the concentration reached 30 per cent. The same tests were repeated with the serum from young and old dogs. The general results were identical, although See PDF for Structure the quantitative inhibiting action of both sera was greater than that of cat serum. It may be concluded that under the conditions of the experiments: 1. Heterogenicsera inhibit and prevent the growth of chicken fibroblasts when their concentration is made to vary within certain limits. 2. A relation exists between the rate

  16. Organizational Economics of Capability and Heterogeneity

    DEFF Research Database (Denmark)

    Argyres, Nicholas S.; Felin, Teppo; Foss, Nicolai Juul

    2012-01-01

    economics, and we point to the dominance of a “capabilities first” logic in this relationship. We argue that capabilities considerations are inherently intertwined with questions about organizational boundaries and internal organization, and we use this point to respond to the prevalent capabilities first......For decades, the literatures on firm capabilities and organizational economics have been at odds with each other, specifically relative to explaining organizational boundaries and heterogeneity. We briefly trace the history of the relationship between the capabilities literature and organizational...

  17. Altitude Acclimatization and Blood Volume: Effects of Exogenous Erythrocyte Volume Expansion

    National Research Council Canada - National Science Library

    Sawka, M

    1996-01-01

    ...: (a) altitude acclimatization effects on erythrocyte volume and plasma volume; (b) if exogenous erythrocyte volume expansion alters subsequent erythrocyte volume and plasma volume adaptations; (c...

  18. 8th International Conference on Solid State Physics (SSP 2004), Workshop “Mössbauer Spectroscopy of Locally Heterogeneous Systems”

    CERN Document Server

    Kadyrzhanov, K. K; SSP 2004

    2006-01-01

    This volume contains papers presented at the 8th International Conference on Solid State Physics (SSP 2004), Workshop "Mössbauer Spectroscopy of Locally Heterogeneous Systems", held in Almaty, Kazakhstan, 23–26 August 2004. It should be of interest to researchers and PhD students working or interested in recent results in the locally inhomogeneous system investigations by Mössbauer Spectroscopy and the new concepts of data evaluation of complex Mössbauer spectra.

  19. Technical Note: A new zeolite PET phantom to test segmentation algorithms on heterogeneous activity distributions featured with ground-truth contours.

    Science.gov (United States)

    Soffientini, Chiara D; De Bernardi, Elisabetta; Casati, Rosangela; Baselli, Giuseppe; Zito, Felicia

    2017-01-01

    Design, realization, scan, and characterization of a phantom for PET Automatic Segmentation (PET-AS) assessment are presented. Radioactive zeolites immersed in a radioactive heterogeneous background simulate realistic wall-less lesions with known irregular shape and known homogeneous or heterogeneous internal activity. Three different zeolite families were evaluated in terms of radioactive uptake homogeneity, necessary to define activity and contour ground truth. Heterogeneous lesions were simulated by the perfect matching of two portions of a broken zeolite, soaked in two different 18 F-FDG radioactive solutions. Heterogeneous backgrounds were obtained with tissue paper balls and sponge pieces immersed into radioactive solutions. Natural clinoptilolite proved to be the most suitable zeolite for the construction of artificial objects mimicking homogeneous and heterogeneous uptakes in 18 F-FDG PET lesions. Heterogeneous backgrounds showed a coefficient of variation equal to 269% and 443% of a uniform radioactive solution. Assembled phantom included eight lesions with volumes ranging from 1.86 to 7.24 ml and lesion to background contrasts ranging from 4.8:1 to 21.7:1. A novel phantom for the evaluation of PET-AS algorithms was developed. It is provided with both reference contours and activity ground truth, and it covers a wide range of volumes and lesion to background contrasts. The dataset is open to the community of PET-AS developers and utilizers. © 2016 American Association of Physicists in Medicine.

  20. Deformation field heterogeneity in punch indentation

    Science.gov (United States)

    Murthy, Tejas G.; Saldana, Christopher; Hudspeth, Matthew; M'Saoubi, Rachid

    2014-01-01

    Plastic heterogeneity in indentation is fundamental for understanding mechanics of hardness testing and impression-based deformation processing methods. The heterogeneous deformation underlying plane-strain indentation was investigated in plastic loading of copper by a flat punch. Deformation parameters were measured, in situ, by tracking the motion of asperities in high-speed optical imaging. These measurements were coupled with multi-scale analyses of strength, microstructure and crystallographic texture in the vicinity of the indentation. Self-consistency is demonstrated in description of the deformation field using the in situ mechanics-based measurements and post-mortem materials characterization. Salient features of the punch indentation process elucidated include, among others, the presence of a dead-metal zone underneath the indenter, regions of intense strain rate (e.g. slip lines) and extent of the plastic flow field. Perhaps more intriguing are the transitions between shear-type and compression-type deformation modes over the indentation region that were quantified by the high-resolution crystallographic texture measurements. The evolution of the field concomitant to the progress of indentation is discussed and primary differences between the mechanics of indentation for a rigid perfectly plastic material and a strain-hardening material are described. PMID:24910521

  1. PDF-based heterogeneous multiscale filtration model.

    Science.gov (United States)

    Gong, Jian; Rutland, Christopher J

    2015-04-21

    Motivated by modeling of gasoline particulate filters (GPFs), a probability density function (PDF) based heterogeneous multiscale filtration (HMF) model is developed to calculate filtration efficiency of clean particulate filters. A new methodology based on statistical theory and classic filtration theory is developed in the HMF model. Based on the analysis of experimental porosimetry data, a pore size probability density function is introduced to represent heterogeneity and multiscale characteristics of the porous wall. The filtration efficiency of a filter can be calculated as the sum of the contributions of individual collectors. The resulting HMF model overcomes the limitations of classic mean filtration models which rely on tuning of the mean collector size. Sensitivity analysis shows that the HMF model recovers the classical mean model when the pore size variance is very small. The HMF model is validated by fundamental filtration experimental data from different scales of filter samples. The model shows a good agreement with experimental data at various operating conditions. The effects of the microstructure of filters on filtration efficiency as well as the most penetrating particle size are correctly predicted by the model.

  2. Genetic heterogeneity of familial hemiplegic migraine

    Energy Technology Data Exchange (ETDEWEB)

    Joutel, A.; Ducros, A.; Vahedi, K. [Faculte de Medecine Necker-Enfants Malades, Paris (France)] [and others

    1994-09-01

    Familial hemiplegic migraine (FHM) is an autosomal dominant subtype of migraine with aura, characterized by the occurrence of a transient hemiplegia during the aura. We previously mapped the affected gene to the short arm of chromosome 19, within a 30 cM interval bracketed by D19S216 and D19S215. Linkage analysis conducted on 2 large FHM pedigrees did not show evidence of heterogeneity, despite their clinical differences due to the presence in one family of a cerebellar ataxia and a nystagmus. Herein we report linkage data on 9 additional FHM families including 2 other ones with cerebellar ataxia. Analysis was conducted with a set of 7 markers spanning the D19S216-D19S215 interval. Two point and multipoint lodscores analysis as well as HOMOG testing provided significant evidence for genetic heterogenity. Strong evidence of linkage was obtained in 3 families and absence of linkage in 6 families. Thus within the 11 families so far tested, 5 were linked, including those with an associated cerebellar ataxia. We could not find any clinical difference between the {open_quotes}pure{close_quotes} FHM families whether or not they were linked. This study also allowed us to establish that the most likely location of the gene is a 12 cM interval bracketed by D19S413 and D19S226. One of the unlinked family was large enough to conduct genetic mapping of the affected gene. Data will be presented at the meeting.

  3. Heterogeneous Photocatalysis: Recent Advances and Applications

    Directory of Open Access Journals (Sweden)

    Alex Omo Ibhadon

    2013-03-01

    Full Text Available Semiconductor heterogeneous photocatalysis, the subject of this review, is a versatile, low-cost and environmentally benign treatment technology for a host of pollutants. These may be of biological, organic and inorganic in origin within water and air. The efficient and successful application of photocatalysis demands that the pollutant, the catalyst and source of illumination are in close proximity or contact with each other. The ability of advanced oxidation technology to remove low levels of persistent organic pollutants as well as microorganisms in water has been widely demonstrated and, progressively, the technology is now being commercialized in many areas of the world including developing nations. This review considers recent developments in the research and application of heterogeneous semiconductor photocatalysis for the treatment of low-level concentrations of pollutants in water and air using titanium dioxide as a “model” semiconductor. The review considers charge transport characteristics on the semiconductor surface, photocatalyst reactor design and organic degradation mechanistic pathways. The effects of photoreactor operating parameters on the photocatalytic process are discussed in addition to mineralization and disinfection kinetics.

  4. Phenotypic Heterogeneity of Monogenic Frontotemporal Dementia.

    Science.gov (United States)

    Benussi, Alberto; Padovani, Alessandro; Borroni, Barbara

    2015-01-01

    Frontotemporal dementia (FTD) is a genetically and pathologically heterogeneous disorder characterized by personality changes, language impairment, and deficits of executive functions associated with frontal and temporal lobe degeneration. Different phenotypes have been defined on the basis of presenting clinical symptoms, i.e., the behavioral variant of FTD, the agrammatic variant of primary progressive aphasia, and the semantic variant of PPA. Some patients have an associated movement disorder, either parkinsonism, as in progressive supranuclear palsy and corticobasal syndrome, or motor neuron disease (FTD-MND). A family history of dementia is found in 40% of cases of FTD and about 10% have a clear autosomal-dominant inheritance. Genetic studies have identified several genes associated with monogenic FTD: microtubule-associated protein tau, progranulin, TAR DNA-binding protein 43, valosin-containing protein, charged multivesicular body protein 2B, fused in sarcoma, and the hexanucleotide repeat expansion in intron 1 of the chromosome 9 open reading frame 72. Patients often present with an extensive phenotypic variability, even among different members of the same kindred carrying an identical disease mutation. The objective of the present work is to review and evaluate available literature data in order to highlight recent advances in clinical, biological, and neuroimaging features of monogenic frontotemporal lobar degeneration and try to identify different mechanisms underlying the extreme phenotypic heterogeneity that characterizes this disease.

  5. Phenotypic heterogeneity of monogenic frontotemporal dementia

    Directory of Open Access Journals (Sweden)

    Alberto eBenussi

    2015-09-01

    Full Text Available Frontotemporal dementia (FTD is a genetically and pathologically heterogeneous disorder characterized by personality changes, language impairment and deficits of executive functions associated with frontal and temporal lobe degeneration. Different phenotypes have been defined on the basis of presenting clinical symptoms, i.e. the behavioral variant of FTD (bvFTD, the agrammatic variant of Primary Progressive Aphasia (avPPA and the semantic variant of PPA (svPPA. Some patients have an associated movement disorder, either parkinsonism, as in Progressive Supranuclear Palsy (PSP and Corticobasal Syndrome (CBS, or motor neuron disease (FTD-MND. A family history of dementia is found in 40% of cases of FTD and about 10% have a clear autosomal dominant inheritance. Genetic studies have identified several genes associated to monogenic FTD: microtubule-associated protein tau (MAPT, progranulin (GRN, TAR DNA-binding protein 43 (TARBDP, valosin-containing protein (VCP, charged multivesicular body protein 2B (CHMP2B, fused in sarcoma (FUS and the hexanucleotide repeat expansion in intron 1 of the chromosome 9 open reading frame 72 (C9orf72. Patients often present with an extensive phenotypic variability, even among different members of the same kindred carrying an identical disease mutation. The objective of the present work is to review and evaluate available literature data in order to highlight recent advances in clinical, biological and neuroimaging features of monogenic frontotemporal lobar degeneration and try to identify different mechanisms underlying the extreme phenotypic heterogeneity that characterizes this disease.

  6. Heterogeneous Parking Market Subject to Parking Rationing

    Directory of Open Access Journals (Sweden)

    Saeed Asadi Bagloee

    2015-01-01

    Full Text Available Different types of drivers and parking spaces delineate a heterogeneous parking market for which the literature has yet to provide a model applicable to the real world. The main obstacle is computational complexities of considering various parking restrictions along with traffic congestion on the road network. In this study, the heterogeneity aspects are considered within a Logit parking choice model. A mathematical programming problem was introduced to explicitly consider parking capacities and parking rationing constraints. The parking rationing is defined as any arrangement to reserve parking space for some specific demand such as parking permit, private parking, VIP parking, and different parking durations. Introduction of parking rationing in the presence of other constraints is a unique factor in this study which makes the model more realistic. The algorithm was tested on a central business district case study. The results prove that the algorithm is able to converge rapidly. Among the algorithm’s output are shadow prices of the parking capacity and parking rationing constraints. The shadow prices contain important information which is key to addressing a variety of parking issues, such as the location of parking shortages, identification of fair parking charges, viability of parking permits, and the size of reserved parking.

  7. Reducing the Diagnostic Heterogeneity of Schizoaffective Disorder.

    Science.gov (United States)

    Seldin, Katherine; Armstrong, Kristan; Schiff, Max L; Heckers, Stephan

    2017-01-01

    Clinical outcome studies of schizoaffective disorder patients have yielded conflicting results. One reason is the heterogeneity of samples drawn from the schizoaffective disorder population. Here, we studied schizoaffective disorder patients who showed marked functional impairment and continuous signs of illness for at least 6 months (i.e., DSM criteria B and C for schizophrenia). We assessed 176 chronic psychosis patients with a structured interview (SCID-IV-TR) and the Diagnostic Interview for Genetic Studies schizoaffective disorder module. We diagnosed 114 patients with schizophrenia and 62 with schizoaffective disorder. The two groups were similar with regard to age, gender, and race. We tested for group differences in antecedent risk factors, clinical features, and functional outcome. The schizoaffective disorder group differed from the schizophrenia group on two measures only: they showed higher rates of suicidality (more suicide attempts, p  disorder comorbidity ( p  schizoaffective disorder patients meet DSM criteria B and C for schizophrenia, they resemble schizophrenia patients on several measures used to assess validity. The increased rate of anxiety disorders and suicidality warrants clinical attention. Our data suggest that a more explicit definition of schizoaffective disorder reduces heterogeneity and may increase validity.

  8. Genetic heterogeneity of familial hemiplegic migraine

    Energy Technology Data Exchange (ETDEWEB)

    Ophoff, R.A.; Van Eijk, R.; Sandkuijl, L.A. [Leiden Univ. (Netherlands)] [and others

    1994-07-01

    Familial hemiplegic migraine (FHM) is a distinctive form of migraine with an autosomal dominant mode of inheritance. The migraine-like attacks are associated with transient hemiparesis. A locus for FHM has recently been assigned to chromosome 19 by linkage mapping. In the present study, five unrelated pedigrees with multiple members suffering from hemiplegic migraine were investigated. In two of the pedigrees additional symptoms, cerebellar ataxia and benign neonatal convulsions, respectively, were observed in affected members. Three pedigrees showed linkage to loci D19S391, D19S221, and D19S226 at chromosome 19p13. Haplotyping suggested a location of a FHM gene between D19S391 and D19S221. In the two remaining families, evidence against linkage was found. These results confirm the localization of a gene for familial hemiplegic migraine to the short arm of chromosome 19, but locus heterogeneity not corresponding to the observed clinical heterogeneity is likely to exist. 19 refs., 3 figs., 3 tabs.

  9. Visual EKF-SLAM from Heterogeneous Landmarks.

    Science.gov (United States)

    Esparza-Jiménez, Jorge Othón; Devy, Michel; Gordillo, José L

    2016-04-07

    Many applications require the localization of a moving object, e.g., a robot, using sensory data acquired from embedded devices. Simultaneous localization and mapping from vision performs both the spatial and temporal fusion of these data on a map when a camera moves in an unknown environment. Such a SLAM process executes two interleaved functions: the front-end detects and tracks features from images, while the back-end interprets features as landmark observations and estimates both the landmarks and the robot positions with respect to a selected reference frame. This paper describes a complete visual SLAM solution, combining both point and line landmarks on a single map. The proposed method has an impact on both the back-end and the front-end. The contributions comprehend the use of heterogeneous landmark-based EKF-SLAM (the management of a map composed of both point and line landmarks); from this perspective, the comparison between landmark parametrizations and the evaluation of how the heterogeneity improves the accuracy on the camera localization, the development of a front-end active-search process for linear landmarks integrated into SLAM and the experimentation methodology.

  10. Genetic heterogeneity in Pakistani microcephaly families revisited.

    Science.gov (United States)

    Ahmad, I; Baig, S M; Abdulkareem, A R; Hussain, M S; Sur, I; Toliat, M R; Nürnberg, G; Dalibor, N; Moawia, A; Waseem, S S; Asif, M; Nagra, H; Sher, M; Khan, M M A; Hassan, I; Rehman, S Ur; Thiele, H; Altmüller, J; Noegel, A A; Nürnberg, P

    2017-07-01

    Autosomal recessive primary microcephaly (MCPH) is a rare and heterogeneous genetic disorder characterized by reduced head circumference, low cognitive prowess and, in general, architecturally normal brains. As many as 14 different loci have already been mapped. We recruited 35 MCPH families in Pakistan and could identify the genetic cause of the disease in 31 of them. Using homozygosity mapping complemented with whole-exome, gene panel or Sanger sequencing, we identified 12 novel mutations in 3 known MCPH-associated genes - 9 in ASPM, 2 in MCPH1 and 1 in CDK5RAP2. The 2 MCPH1 mutations were homozygous microdeletions of 164,250 and 577,594 bp, respectively, for which we were able to map the exact breakpoints. We also identified four known mutations - three in ASPM and one in WDR62. The latter was initially deemed to be a missense mutation but we demonstrate here that it affects splicing. As to ASPM, as many as 17 out of 27 MCPH5 families that we ascertained in our sample were found to carry the previously reported founder mutation p.Trp1326*. This study adds to the mutational spectra of four known MCPH-associated genes and updates our knowledge about the genetic heterogeneity of MCPH in the Pakistani population considering its ethnic diversity. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  11. SIS Epidemic Spreading with Heterogeneous Infection Rates

    CERN Document Server

    Qu, Bo

    2015-01-01

    In this work, we aim to understand the influence of the heterogeneity of infection rates on the Susceptible-Infected-Susceptible (SIS) epidemic spreading. Specifically, we keep the recovery rates the same for all nodes and study the influence of the moments of the independently identically distributed (i.i.d.) infection rates on the average fraction $y_\\infty$ of infected nodes in the meta-stable state, which indicates the severity of the overall infection. Motivated by real-world datasets, we consider the log-normal and gamma distributions for the infection rates and we design as well a symmetric distribution so that we have a systematic view of the influence of various distributions. By continuous-time simulations on several types of networks, theoretical proofs and physical interpretations, we conclude that: 1) the heterogeneity of infection rates on average retards the virus spread, and 2) a larger even-order moment of the infection rates leads to a smaller average fraction of infected nodes, but the odd-...

  12. Spreading of persistent infections in heterogeneous populations

    Science.gov (United States)

    Sanz, J.; Floría, L. M.; Moreno, Y.

    2010-05-01

    Up to now, the effects of having heterogeneous networks of contacts have been studied mostly for diseases which are not persistent in time, i.e., for diseases where the infectious period can be considered very small compared to the lifetime of an individual. Moreover, all these previous results have been obtained for closed populations, where the number of individuals does not change during the whole duration of the epidemics. Here, we go one step further and analyze, both analytically and numerically, a radically different kind of diseases: those that are persistent and can last for an individual’s lifetime. To be more specific, we particularize to the case of tuberculosis’ (TB) infection dynamics, where the infection remains latent for a period of time before showing up and spreading to other individuals. We introduce an epidemiological model for TB-like persistent infections taking into account the heterogeneity inherent to the population structure. This sort of dynamics introduces new analytical and numerical challenges that we are able to sort out. Our results show that also for persistent diseases the epidemic threshold depends on the ratio of the first two moments of the degree distribution so that it goes to zero in a class of scale-free networks when the system approaches the thermodynamic limit.

  13. Heterogeneous photocatalytic reactions of sulfur aromatic compounds.

    Science.gov (United States)

    Samokhvalov, Alexander

    2011-11-18

    Sulfur aromatic compounds, such as mono-, di-, tri-, and tetraalkyl-substituted thiophene, benzothiophenes, dibenzothiophenes, are the molecular components of many fossils (petroleum, oil shale, tar sands, bitumen). Structural units of natural, cross-linked heteroaromatic polymers present in brown coals, turf, and soil are similar to those of sulfur aromatic compounds. Many sulfur aromatic compounds are found in the streams of petroleum refining and upgrading (naphthas, gas oils) and in the consumer products (gasoline, diesel, jet fuels, heating fuels). Besides fossils, the structural fragments of sulfur aromatic compounds are present in molecules of certain organic semiconductors, pesticides, small molecule drugs, and in certain biomolecules present in human body (pheomelanin pigments). Photocatalysis is the frontier area of physical chemistry that studies chemical reactions initiated by absorption of photons by photocatalysts, that is, upon electronic rather than thermal activation, under "green" ambient conditions. This review provides systematization and critical review of the fundamental chemical and physicochemical information on heterogeneous photocatalysis of sulfur aromatic compounds accumulated in the last 20-30 years. Specifically, the following topics are covered: physicochemical properties of sulfur aromatic compounds, major classes of heterogeneous photocatalysts, mechanisms and reactive intermediates of photocatalytic reactions of sulfur aromatic compounds, and the selectivity of these reactions. Quantum chemical calculations of properties and structures of sulfur aromatic compounds, their reactive intermediates, and the structure of adsorption complexes formed on the surface of the photocatalysts are also discussed. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Heterogeneous nucleation in solutions: generalized Gibbs' approach.

    Science.gov (United States)

    Abyzov, Alexander S; Schmelzer, Jürn W P

    2014-06-28

    Heterogeneous nucleation in solutions on planar solid surfaces is modeled taking into account changes of the state parameters of the critical clusters in dependence on supersaturation. The account of the variation of the state parameters of the cluster phase on nucleation is performed in the framework of the generalized Gibbs' approach. A regular solution is chosen as a model for the analysis of the basic qualitative characteristics of the process. It is shown that, employing the generalized Gibbs approach, contact angle and catalytic activity factor for heterogeneous nucleation become dependent on the degree of metastability (supersaturation) of the solution. For the case of formation of a cluster in supersaturated solutions on a surface of low wettability (the macroscopic equilibrium contact angles being larger than 90°), the solid surface has only a minor influence on nucleation. In the alternative case of high wettability (for macroscopic equilibrium contact angles being less than 90°), nucleation is significantly enhanced by the solid surface. Effectively, the existence of the solid surface results in a significant shift of the spinodal to lower supersaturations as compared with homogeneous nucleation. Qualitatively, the same behavior is observed now near the new (solid surface induced) limits of instability of the solution as compared with the behavior near to the spinodal curve in the case of homogeneous nucleation.

  15. Heterogeneous architecture to process swarm optimization algorithms

    Directory of Open Access Journals (Sweden)

    Maria A. Dávila-Guzmán

    2014-01-01

    Full Text Available Since few years ago, the parallel processing has been embedded in personal computers by including co-processing units as the graphics processing units resulting in a heterogeneous platform. This paper presents the implementation of swarm algorithms on this platform to solve several functions from optimization problems, where they highlight their inherent parallel processing and distributed control features. In the swarm algorithms, each individual and dimension problem are parallelized by the granularity of the processing system which also offer low communication latency between individuals through the embedded processing. To evaluate the potential of swarm algorithms on graphics processing units we have implemented two of them: the particle swarm optimization algorithm and the bacterial foraging optimization algorithm. The algorithms’ performance is measured using the acceleration where they are contrasted between a typical sequential processing platform and the NVIDIA GeForce GTX480 heterogeneous platform; the results show that the particle swarm algorithm obtained up to 36.82x and the bacterial foraging swarm algorithm obtained up to 9.26x. Finally, the effect to increase the size of the population is evaluated where we show both the dispersion and the quality of the solutions are decreased despite of high acceleration performance since the initial distribution of the individuals can converge to local optimal solution.

  16. Capturing Structural Heterogeneity in Chromatin Fibers.

    Science.gov (United States)

    Ekundayo, Babatunde; Richmond, Timothy J; Schalch, Thomas

    2017-10-13

    Chromatin fiber organization is implicated in processes such as transcription, DNA repair and chromosome segregation, but how nucleosomes interact to form higher-order structure remains poorly understood. We solved two crystal structures of tetranucleosomes with approximately 11-bp DNA linker length at 5.8 and 6.7 Å resolution. Minimal intramolecular nucleosome-nucleosome interactions result in a fiber model resembling a flat ribbon that is compatible with a two-start helical architecture, and that exposes histone and DNA surfaces to the environment. The differences in the two structures combined with electron microscopy reveal heterogeneous structural states, and we used site-specific chemical crosslinking to assess the diversity of nucleosome-nucleosome interactions through identification of structure-sensitive crosslink sites that provide a means to characterize fibers in solution. The chromatin fiber architectures observed here provide a basis for understanding heterogeneous chromatin higher-order structures as they occur in a genomic context. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Genetic heterogeneity of Usher syndrome type II.

    Science.gov (United States)

    Pieke Dahl, S; Kimberling, W J; Gorin, M B; Weston, M D; Furman, J M; Pikus, A; Möller, C

    1993-01-01

    Usher syndrome is an autosomal recessive disorder characterised by retinitis pigmentosa and congenital sensorineural hearing loss. A gene for Usher syndrome type II (USH2) has been localised to chromosome 1q32-q41. DNA from a family with four of seven sibs affected with clinical characteristics of Usher syndrome type II was genotyped using markers spanning the 1q32-1q41 region. These included D1S70 and D1S81, which are believed to flank USH2. Genotypic results and subsequent linkage analysis indicated non-linkage of this family to these markers. The A test analysis for heterogeneity with this family and 32 other Usher type II families was statistically significant at p < 0.05. Further clinical evaluation of this family was done in light of the linkage results to determine if any phenotypic characteristics would allow for clinical identification of the unlinked type. No clear phenotypic differences were observed; however, this unlinked family may represent a previously unreported subtype of Usher type II characterised by a milder form of retinitis pigmentosa and mild vestibular abnormalities. Heterogeneity of Usher syndrome type II complicates efforts to isolate and clone Usher syndrome genes using linkage analysis and limits the use of DNA markers in early detection of Usher type II. Images PMID:7901420

  18. Functional heterogeneity at dopamine release sites.

    Science.gov (United States)

    Daniel, James A; Galbraith, Sally; Iacovitti, Lorraine; Abdipranoto, Andrea; Vissel, Bryce

    2009-11-18

    Although drugs used to treat several neurological diseases are presumed to target synapses that secrete dopamine (DA), relatively little is known about synaptic vesicle (SV) release mechanisms at single DA synapses. We found that the relative probability of release (Pr) varied between individual DA synapses. Furthermore, DA terminals generally exhibited lower Pr than glutamatergic hippocampal (Hpc) terminals, suggesting that DA release is less reliable than the release of glutamate. Our mathematical model of fluorescence loss shows that Pr is regulated by two independent and heterogeneous elements. First, the size of the recycling SV pool regulates Pr. Second, Pr is also independently regulated by additional factors, which are reflected in the time constant of FM 1-43 destaining, tau. We found that the observed difference in Pr between Hpc and DA neurons results because the recycling SV pool is smaller in DA neurons than in Hpc neurons. However, tau does not vary between these two neuron populations. We also identified a population of functional nonsynaptic boutons in DA axons, which are not associated with a postsynaptic element and which are not functionally different from boutons that formed conventional synapses. Our work provides a new approach to the study of SV exocytosis in DA neurons and shows that synaptic terminals of DA neurons are functionally heterogeneous and differ from excitatory terminals in terms of Pr.

  19. A Dynamical Context for Small-scale Heterogeneity Throughout the Mantle Beneath Subduction

    Science.gov (United States)

    Frost, D. A.; Rost, S.; Garnero, E.

    2014-12-01

    Subduction zones are a source for mantle heterogeneity within the convection system and there is mounting evidence that seismic signatures can be used to track slabs down from the surface throughout the mantle. Seismic studies of the mantle beneath Central America demonstrate that subducted slab material reaches the Core-Mantle Boundary (CMB). The lowermost mantle beneath this convergent margin shows strong seismic evidence for heterogeneity. Tomographic models characterise subduction zones to be underlain by increased seismic velocities over 100s-1000s km laterally, in association with D'´ discontinuities 100-300 km above the CMB, consistent with phase transitions in the Bridgmanite system. Recent analyses have found evidence for isolated Ultra Low Velocity Zones in addition to prevalent fine-scale heterogeneity, on the order of 1-10 km, scattering high frequency waves. These techniques indicate thermal and/or chemical anomalies within the mantle on a range of scales. Numerical geodynamical simulations suggest small-scale mechanical mixing of initially coherent compositionally anomalous subducted material separating into entities of various sizes consistent with the range of heterogeneity sizes observed in the lower mantle.Investigating seismic scattering, the re-radiation of a wavefront due to interaction with a sharply contrasting volumetric anomaly, is an effective method for studying small-scale elastic heterogeneities in the Earth's mantle. Studies commonly record structure with scale lengths of about 10 km. Here we analyse scattered energy related to PKPPKP — PKP•PKP (the • indicates the scattering location along the raypath) — sampling a large volume of the mantle beneath Central America. We reveal the character of heterogeneity in various frequency bands within the whole mantle using both broadband and short-period data. These observations will be placed in context with other studies in this region illustrating the large-scale background structure

  20. Microbial population heterogeneity versus bioreactor heterogeneity: evaluation of Redox Sensor Green as an exogenous metabolic biosensor

    DEFF Research Database (Denmark)

    Baert, Jonathan; Delepierre, Anissa; Telek, Samuel

    2016-01-01

    performances (i.e. microbial population heterogeneity). In this work, we have evaluated the relevance of Redox Sensor Green (RSG) as an exogenous biosensor of metabolic activity at the single cell level. RSG signal is proportional to the activity of the electron transport chain and its signal is strongly...