Sample records for chain reaction-denaturing gradient

  1. Analysis of interspecies adherence of oral bacteria using a membrane binding assay coupled with polymerase chain reaction-denaturing gradient gel electrophoresis profiling

    PubMed Central

    Wang, Ren-ke; He, Xue-song; Hu, Wei; Lux, Renate; Li, Ji-yao; Zhou, Xue-dong; Shi, Wen-yuan

    2011-01-01

    Information on co-adherence of different oral bacterial species is important for understanding interspecies interactions within oral microbial community. Current knowledge on this topic is heavily based on pariwise coaggregation of known, cultivable species. In this study, we employed a membrane binding assay coupled with polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) to systematically analyze the co-adherence profiles of oral bacterial species, and achieved a more profound knowledge beyond pairwise coaggregation. Two oral bacterial species were selected to serve as “bait”: Fusobacterium nucleatum (F. nucleatum) whose ability to adhere to a multitude of oral bacterial species has been extensively studied for pairwise interactions and Streptococcus mutans(S. mutans) whose interacting partners are largely unknown. To enable screening of interacting partner species within bacterial mixtures, cells of the “bait” oral bacterium were immobilized on nitrocellulose membranes which were washed and blocked to prevent unspecific binding. The “prey” bacterial mixtures (including known species or natural saliva samples) were added, unbound cells were washed off after the incubation period and the remaining cells were eluted using 0.2 mol·L?1 glycine. Genomic DNA was extracted, subjected to 16S rRNAPCR amplification and separation of the resulting PCR products by DGGE. Selected bands were recovered from the gel, sequenced and identified via Nucleotide BLAST searches against different databases. While few bacterial species bound to S. mutans, consistent with previous findings F.nucleatum adhered to a variety of bacterial species including uncultivable and uncharacterized ones. This new approach can more effectively analyze the co-adherence profiles of oral bacteria, and could facilitate the systematic study of interbacterial binding of oral microbial species. PMID:21485313

  2. Appropriate Chicken Sample Size for Identifying the Composition of Broiler Intestinal Microbiota Affected by Dietary Antibiotics, Using the Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis Technique

    Microsoft Academic Search

    H. Zhou; J. Gong; J. T. Brisbin; H. Yu; B. Sanei; P. Sabour; S. Sharif

    2007-01-01

    The bacterial microbiota in the broiler gas- trointestinal tract are crucial for chicken health and growth. Their composition can vary among individual birds. To evaluate the composition of chicken microbiota in response to environmental disruption accurately, 4 dif- ferent pools made up of 2, 5, 10, and 15 individuals were used to determine how many individuals in each pool were

  3. Tracking the composition and dominant components of the microbial community via polymerase chain reaction-denaturing gradient gel electrophoresis and fluorescence in situ hybridization during vermiconversion for liquid-state excess sludge stabilization.

    PubMed

    Xu, Ting; Xing, Meiyan; Yang, Jian; Lv, Baoyi; Duan, Ting; Nie, Jing

    2014-09-01

    To quantitatively explore the microbial community modified by earthworms, a vermifilter (VF, with earthworms) and a conventional biofilter (BF, without earthworms) were continuously operated to stabilize excess sludge. The results demonstrated a positive role imposed by earthworms on compositions and dominant components of microbial community in the VF. For one thing, the phyla Actinobacteria and Acidobacteria were only detected in the VF, which might explain for the higher Shannon index of bacteria in the VF (H = 2.58) than that in the BF (H = 1.99). For another, the total proportion of dominant bacteria in the VF increased by 23% compared to the BF. Moreover, quantification analysis explicitly noted that the dominant bacteria in VF were ?-proteobacteria (27 ± 2%) and ?-proteobacteria (24 ± 1%) while that in BF was Bacteroidetes (21 ± 1%). In conclusion, stimulated by earthworms, a unique microbial community developed in the VF, thus improving the stabilization of excess sludge. PMID:24971951

  4. Mathematical Modeling and Simulation of Denaturation Temperature Gradient Polymerase Chain Reaction

    E-print Network

    Yoo, SukIn

    Mathematical Modeling and Simulation of Denaturation Temperature Gradient Polymerase Chain Reaction@bi.snu.ac.kr, thpark@plaza.snu.ac.kr Polymerase chain reaction (PCR) is a biochemical process for in vitro. In a previous study, we introduced denaturation temperature gradient polymerase chain reaction (DTG- PCR

  5. Carotenoids in a food chain along a pollution gradient.

    PubMed

    Sillanpää, Saila; Salminen, Juha-Pekka; Lehikoinen, Esa; Toivonen, Eija; Eeva, Tapio

    2008-11-15

    Carotenoids are synthesized by plants, therefore insects and birds must obtain them from their diet. They function in pigmentation and as antioxidants. We studied the carotenoid profiles in a model food chain (plant-insect-bird) in an air pollution gradient to find out whether heavy metal pollution affects the transfer of carotenoids across the trophic levels. Birch leaves showed higher beta-carotene and, one of the birch species (Betula pendula), higher total carotenoids levels in the polluted area. There was no difference in the lutein concentration of caterpillars' food source, birch leaves, between the study areas. Autumnal moth larvae accumulated lutein more efficiently than beta-carotene while sawfly larvae accumulated beta-carotene over lutein. Because of different antioxidant profiles in different leaf chewing insects their sensitivity to pollution stress may differ. The lutein concentration of plasma and feathers of Great tit nestlings did not differ along the pollution gradient. The lack of difference in lutein concentration of autumnal moth larvae along pollution gradient may partly explain the lutein concentrations of Great tit nestlings, since the abundance of autumnal moth larvae peak during the nestling phase of Great tit. The lutein concentration of autumnal moth larvae was positively associated to circulating plasma lutein level of Great tit indicating the importance of carotenoid rich diet during the nestling phase. In addition, the higher the plasma lutein concentration the more lutein was deposited to feathers, irrespective of the other possible functions of lutein in nestlings. We found that carotenoid levels differed between the polluted and the unpolluted area especially at lower levels of food chain: in birches and in caterpillars. PMID:18789813

  6. Calculated electrostatic gradients in recombinant human H-chain ferritin.

    PubMed Central

    Douglas, T.; Ripoll, D. R.

    1998-01-01

    Calculations to determine the electrostatic potential of the iron storage protein ferritin, using the human H-chain homopolymer (HuHF), reveal novel aspects of the protein. Some of the charge density correlates well with regions previously identified as active sites in the protein. The three-fold channels, the putative ferroxidase sites, and the nucleation sites all show expectedly negative values of the electrostatic potential. However, the outer entrance to the three-fold channels are surrounded by regions of positive potential, creating an electrostatic field directed toward the interior cavity. This electrostatic gradient provides a guidance mechanism for cations entering the protein cavity, indicating the three-fold channel as the major entrance to the protein. Pathways from the three-fold channels, indicated by electrostatic gradients on the inner surface, lead to the ferroxidase center, the nucleation center and to the interior entrance to the four-fold channel. Six glutamic acid residues at the nucleation site give rise to a region of very negative potential, surrounding a small positively charged center due to the presence of two conserved arginine residues, R63, in close proximity (4.9 A), suggesting that electrostatic fields could also play a role in the nucleation process. A large gradient in the electrostatic potential at the 4-fold channel gives rise to a field directed outward from the internal cavity, indicating the possibility that this channel functions to expel cations from inside the protein. The 4-fold channel could therefore provide an exit pathway for protons during mineralization, or iron leaving the protein cavity during de-mineralization. PMID:9605313

  7. The solution to the 4-phonon Boltzmann equation for a 1D chain in a thermal gradient

    Microsoft Academic Search

    Bernie Nickel

    2007-01-01

    The phonon distribution function in a weakly anharmonic one-dimensional chain in a thermal gradient is determined in the high temperature or, equivalently, classical regime. Thermal relaxation is dominated by 4-phonon scattering processes in this limit and these are treated using Peierls' Boltzmann equation approach. An analytical analysis of the Boltzmann equation for small wave vector k shows that the distribution

  8. The Coupling Between Grazing and Detritus Food Chains and the Strength of Trophic Cascades Across a Gradient of Nutrient Enrichment

    Microsoft Academic Search

    José Luiz Attayde; Jörgen Ripa

    2008-01-01

    A minimal food web model was constructed comprising one grazing and one detritus food chain coupled by nutrient cycling and\\u000a generalist carnivores to investigate how prey preference by carnivores may affect the strength of trophic cascades across\\u000a a gradient of nutrient enrichment. The equilibrium or mean abundance of each food web component and the magnitude of the carnivore\\u000a effect on

  9. Extraordinarily low density of hepatitis C virus estimated by sucrose density gradient centrifugation and the polymerase chain reaction

    Microsoft Academic Search

    Hideaki Miyamoto; Hiroaki Okamoto; Koei Sato; Takeshi Tanaka; Shunji Mishiro

    1992-01-01

    The genomic RNA of hepatitis C virus (HCV) in the plasma of volunteer blood donors was detected by using the polymerase chain reaction in a fraction of density 1-08 g\\/ml from sucrose density gradient equilibrium centrifugation. When the fraction was treated with the detergent NP40 and recentrifuged in sucrose, the HCV RNA banded at 1.25g\\/ml. Assuming that NP40 removed a

  10. Parallel DNA amplification by convective polymerase chain reaction with various annealing temperatures on a thermal gradient device.

    PubMed

    Zhang, Chunsun; Xing, Da

    2009-04-01

    We present a thermal gradient convective polymerase chain reaction (PCR) for parallel DNA amplification with different annealing temperatures. The thermal gradient for microfluidic gradient PCR is produced by an innovative fin design whose formation principle is given. Without the need for a pump, the buoyancy forces continuously circulate reagents in a closed loop through different thermal zones, which brings self-actuated convective-flow PCR. In our prototype, we measured a temperature difference of about 45 degrees C along the gradient direction on the copper flake (45 x 40 x 4 mm). When the temperature of the hot zone is 90-97 degrees C and the temperature of the cold zone is 60-70 degrees C, the convection triggered two-temperature amplification of 112-bp fragment of Escherichia coli DNA. The time for amplification is less than 45 min. Interestingly, parallel DNA amplification with different annealing temperatures ranging from 60 to 70 degrees C was performed by this method. The PCR thermocycler demonstrated herein can be further scaled down and the loop length can be further reduced, and therefore the PCR times can be further reduced. These devices are suited as a platform for a new generation of low-power, portable DNA analysis systems. PMID:19454245

  11. Thermal denaturation of double-stranded nucleic acids: prediction of temperatures critical for gradient gel electrophoresis and polymerase chain reaction.

    PubMed Central

    Steger, G

    1994-01-01

    A program is described which calculates the thermal stability and the denaturation behaviour of double-stranded DNAs and RNAs up to a length of 1000 base pairs. The algorithm is based on recursive generation of conditional and a priori probabilities for base stacking. Output of the program may be compared directly to experimental results; thus the program may be used to optimize the nucleic acid fragments, the primers and the experimental conditions prior to experiments like polymerase chain reactions, temperature-gradient gel electrophoresis, denaturing-gradient gel electrophoresis and hybridizations. The program is available in three versions; the first version runs interactively on VAXstations producing graphics output directly, the second is implemented as part of the HUSAR package at GENIUSnet, the third runs on any computer producing text output which serves as input to available graphics programs. Images PMID:8052531

  12. Bulk Properties of Anharmonic Chains in Strong Thermal Gradients: Non-Equilibrium $?^4$ Theory

    E-print Network

    Kenichiro Aoki; Dimitri Kusnezov

    1999-10-09

    We study nonequilibrium properties of a one-dimensional lattice Hamiltonian with quartic interactions in strong thermal gradients. Nonequilibrium temperature profiles, T(x), are found to develop significant curvature and boundary jumps. From the determination of the bulk thermal conductivity, we develop a quantitative description of T(x) including the jumps.

  13. Molecular dynamics studies on the influences of a gradient electric field on the water chain in a peptide nanotube.

    PubMed

    Li, Hui; Fan, Jianfen F; Li, Rui; Yu, Yi; Yan, Xiliang L

    2014-08-01

    The structure and transportation characteristics of the water chain inside a 8×cyclo-(WL)4 peptide nanotube (PNT) were simulated under a gradient electric (GE) field. The gradient was defined by the ratio of a constant (Ea) and the z-directional length (Lz) of the simulation box. Ea varies from 0.0 to 0.9 V nm(-1). As the gradient increases, the probabilities of finding two water molecules in an ?-plane zone and three in a midplane region increase. To accommodate more water molecules, the axial array of channel water molecules becomes more compact. Meanwhile, the H-bonded network between the channel water is greatly intensified when Ea increases from 0.3 to 0.9 V nm(-1). Nevertheless, the proportion of strong H-bonds does not increase significantly following the formation of a more compact axial array of water molecules. When Ea reaches 0.9 V nm(-1), the water molecule in an ?-plane zone may be dragged by its neighboring water molecules into the midplane region, resulting in a significant deviation from the channel axis. With the augment of the gradient, the dipoles of channel water are gradually oriented along the tube axis in the sequence from gap 1 to 7, namely along the direction of the electric field. Nevertheless, even when E a reaches 0.9 V nm(-1), the dipole orientation of the channel water is not complete, and dipole flips still occur in gap 7. Under a GE field, the rightward and leftward hopping rates of channel water are no longer equal to each other, i.e., channel water performs an asymmetric transportation. PMID:25081606

  14. Assessment of bacterial community structure in soil by polymerase chain reaction and denaturing gradient gel electrophoresis.

    PubMed

    Gelsomino, A; Keijzer-Wolters, A C; Cacco, G; van Elsas, J D

    1999-10-01

    Bacterial community structure was studied in a Flevo silt loam (FSL) soil microplot, as well as in 15 other soils, by using DNA extraction followed by molecular fingerprinting. Total community DNA was extracted and purified by a direct method, which yielded amplifiable DNA of high molecular weight for all soils. A variable region of the 16S rRNA gene was then amplified by PCR with bacterial primers, resulting in a mixture of amplicons separable via denaturing gradient gel electrophoresis (DGGE). The DGGE profiles of FSL soil were indicative of dominant soil bacterial types, as evidenced by assessing the amplification of Enterobacter cloacae and Arthrobacter sp. targets in a soil DNA background. These targets produced barely detectable bands when present in soil DNA at roughly 5 x 10(6) genome equivalents per g dry soil, and strong bands at 27-fold higher levels. The PCR-DGGE analysis of the FSL soil was highly reproducible. Furthermore, different single versus composite topsoil samples yielded similar DGGE profiles with respect to major bands. In addition, samples taken along vertical soil cores (0-45 cm depth) revealed relative stability of the DGGE profiles. The profiles produced with DNA obtained from different aggregate size fractions of this soil were also similar with respect to the main bands. Moreover, FSL topsoil samples taken over a 1-year period (fallow soil) yielded stable profiles. These data suggested that the soil bacterial communities thus determined were dominated by a limited number of stable and ubiquitous types. The 16 soils, representing varying types and geographical locations, were assessed for differences in their bacterial DGGE profiles. There were striking differences between the profiles obtained for these soils. Evidence was found for the hypothesis that similar soil types tend to contain similar structures of the dominating bacterial types as revealed by the DGGE profiles. PMID:10520580

  15. Polymerase Chain Reaction and Denaturing Gradient Gel Electrophoresis Monitoring of Fecal Bifidobacterium Populations in a Prebiotic and Probiotic Feeding Trial

    Microsoft Academic Search

    Reetta M. Satokari; Elaine E. Vaughan; Antoon D. L. Akkermans; Maria Saarela; Willem M. de Vos

    2001-01-01

    A culture-independent approach based on genus-specific PCR and denaturing gradient gel electrophoresis (DGGE) was used to monitor qualitative changes in fecal bifidobacterial communities in a human feeding trial. DNA was extracted directly from feces and bifidobacterial 16S rDNA sequences were amplified using genus-specific PCR. The PCR fragments were subsequently separated in a sequence-specific manner by DGGE in order to obtain

  16. Application of PCR-Denaturing-Gradient Gel Electrophoresis (DGGE) Method to Examine Microbial Community Structure in Asparagus Fields with Growth Inhibition due to Continuous Cropping

    PubMed Central

    Urashima, Yasufumi; Sonoda, Takahiro; Fujita, Yuko; Uragami, Atsuko

    2012-01-01

    Growth inhibition due to continuous cropping of asparagus is a major problem; the yield of asparagus in replanted fields is low compared to that in new fields, and missing plants occur among young seedlings. Although soil-borne disease and allelochemicals are considered to be involved in this effect, this is still controversial. We aimed to develop a technique for the biological field diagnosis of growth inhibition due to continuous cropping. Therefore, in this study, fungal community structure and Fusarium community structure in continuously cropped fields of asparagus were analyzed by polymerase chain reaction/denaturing-gradient gel electrophoresis (PCR-DGGE). Soil samples were collected from the Aizu region of Fukushima Prefecture, Japan. Soil samples were taken from both continuously cropped fields of asparagus with growth inhibition and healthy neighboring fields of asparagus. The soil samples were collected from the fields of 5 sets in 2008 and 4 sets in 2009. We were able to distinguish between pathogenic and non-pathogenic Fusarium by using Alfie1 and Alfie2GC as the second PCR primers and PCR-DGGE. Fungal community structure was not greatly involved in the growth inhibition of asparagus due to continuous cropping. By contrast, the band ratios of Fusarium oxysporum f. sp. asparagi in growth-inhibited fields were higher than those in neighboring healthy fields. In addition, there was a positive correlation between the band ratios of Fusarium oxysporum f. sp. asparagi and the ratios of missing asparagus plants. We showed the potential of biological field diagnosis of growth inhibition due to continuous cropping of asparagus using PCR-DGGE. PMID:22200640

  17. Detection of Clonal T-Cell Receptor ? Gene Rearrangements in Early Mycosis Fungoides\\/Sezary Syndrome by Polymerase Chain Reaction and Denaturing Gradient Gel Electrophoresis (PCR\\/DGGE)

    Microsoft Academic Search

    Gary S. Wood; Rosnn M. Tung; Andreas C. Heaffner; Carol F. Crooks; Shaoyi Liao; Rachaci Orozco; Hendrik Veelken; Marshall E. Kadin; Howard Koh; Peter Heald; Raymond L. Barnhill; Jeffrey Sklar

    1994-01-01

    We used a gene amplification strategy to analyze T-cell receptor (TCR) gene rearrangements in 185 specimens, including mycosis fungoides\\/Sezary syndrome (MF\\/SS), other cutaneous neoplasms, inflammatory dermatoses, reactive lymphoid tissues,and normal skin. Genomic DNA was extracted from lesional tissues and rearrangements of the TCR-? chain gene were amplified using the polymerase chain reaction (PCR) with primers specific for rearrangements involving V?1-8

  18. The ecological distribution and comparative photobiology of symbiotic dinoflagellates from reef corals in Belize: Potential implications for coral bleaching

    Microsoft Academic Search

    Mark E. Warner; Todd C. LaJeunesse; Jennifer D. Robison; Rebecca M. Thur

    2006-01-01

    The photobiology and distribution of dinoflagellates in the genus Symbiodinium was investigated for eight common reef coral species over a depth range of 1-25 m on a coral reef in Belize. The genetic identification of symbionts using polymerase chain reaction-denaturing gradient electrophoresis of the internal transcribed spacer 2 region revealed marked differences in host specificity and depth zonation for certain

  19. Molecular fingerprinting of bacterial populations in groundwater and bottled mineral water

    Microsoft Academic Search

    T. Dewettinck; W. Hulsbosch; K. Van Hege; E. Top; W. Verstraete

    2001-01-01

    Monitoring the hygienic quality of drinking waters by determining the concentration of fecal indicators with traditional plate count techniques suffers from important drawbacks. In this work, the potential of PCR-DGGE (polymerase chain reaction - denaturing gradient gel electrophoresis) analysis of 16S rDNA genes to fingerprint the bacterial populations of mineral water and groundwater was investigated. A rapid and simple pretreatment

  20. Geothermal Gradients

    NSDL National Science Digital Library

    Cameron Davidson

    In this problem set the students use two different equations to calculate a conductive geothermal gradient using a spreadsheet program like Excel. Once they have the geothermal gradient plotted, they are asked to experiment with and comment on the model by changing parameters (e.g. mantle heat flow, thermal conductivity). There is a mix of specific, fill in the blank questions and open-ended questions. This problem set helps develop quantitative problem solving skills using a spreadsheet as a tool, and forces students to think about thermal constraints during igneous and metamorphic processes.

  1. PCR-DGGE fingerprinting: novel strategies for detection of microbes in food

    Microsoft Academic Search

    Danilo Ercolini

    2004-01-01

    Polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) fingerprinting was recently introduced into food microbiology. This paper describes the technique and reports on the state-of-the-art application of this technique to food and food-related ecosystems. Applications of PCR-DGGE in several fields of food microbiology are reviewed: the identification of microorganisms isolated from food, the evaluation of microbial diversity during food fermentation,

  2. Improved bacterial community diversity and cucumber yields in a rotation with kidney bean–celery–cucumber

    Microsoft Academic Search

    Fengzhi Wu; Huiying Yu; Gaobo Yu; Kai Pan; Jing Bao

    2011-01-01

    Using polymerase chain reaction–denaturing gradient gel electrophoresis (PCR–DGGE) methods, we investigated the effects of seven different crop rotation modes on cucumber rhizosphere soil bacterial communities. The bacterial diversity indexes in three growth periods showed that the diversity and evenness indexes of the kidney bean–celery–cucumber rotation were higher than those of the following rotations: tomato–kidney bean–cucumber, tomato–celery–cucumber, kidney bean–tomato–cucumber, cucumber–kidney bean–cucumber,

  3. In Vivo PCR-DGGE Analysis of Lactobacillus plantarum and Oenococcus oeni Populations in Red Wine

    Microsoft Academic Search

    G. Spano; A. Lonvaud-Funel; O. Claisse; S. Massa

    2007-01-01

    In order to monitor Lactobacillus plantarum and Oenococcus oeni in red wine produced with Italian grape (variety “Primitivo di Puglia”), a polymerase chain reaction– denaturing gradient\\u000a gel electrophoresis (PCR-DGGE) approach using the rpoB as gene target was established. Wine was treated or not with potassium metabisulphite and supplemented with a commercial\\u000a bacterial starter of O. oeni to encourage malolactic fermentation.

  4. Effect of different salt adaptation strategies on the microbial diversity, activity, and settling of nitrifying sludge in sequencing batch reactors

    Microsoft Academic Search

    João Paulo Bassin; Robbert Kleerebezem; Gerard Muyzer; Alexandre Soares Rosado; Mark C. M. van Loosdrecht; Marcia Dezotti

    2011-01-01

    The effect of salinity on the activity of nitrifying bacteria, floc characteristics, and microbial community structure accessed\\u000a by fluorescent in situ hybridization and polymerase chain reaction–denaturing gradient gel electrophoresis techniques was\\u000a investigated. Two sequencing batch reactors (SRB1 and SBR2) treating synthetic wastewater were subjected to increasing salt concentrations. In SBR1, four salt concentrations (5, 10, 15, and 20 g NaCl\\/L) were

  5. Community analysis of arbuscular mycorrhizal fungi associated with Ammophila arenaria in Dutch coastal sand dunes

    Microsoft Academic Search

    George A. Kowalchuk; Francisco A. de Souza; Johannes A. van Veen

    2002-01-01

    A polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) approach for the detection and characterization of arbuscular mycorrhizal fungi (AMF) 18S ribosomal DNA (rDNA) was developed and applied to the study of AMF communities associated with the main sand-stabilizing plant species of the Dutch sand dunes, marram. grass (Ammophila arenaria, L.). DNA was extracted directly from plant roots, soil or isolated

  6. Microbiological study of lactic acid bacteria in kefir grains by culture-dependent and culture-independent methods

    Microsoft Academic Search

    Hsi-Chia Chen; Sheng-Yao Wang; Ming-Ju Chen

    2008-01-01

    Lactic acid bacteria (LAB) in different original kefir grains were first assessed using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) by a culture-dependent way, and were further confirmed by DNA sequencing techniques. Results indicated that a combined method of cultivation with PCR-DGGE and subsequent DNA sequencing could successfully identify four LAB strains from three kefir grains from Taiwan (named Hsinchu,

  7. Microbial succession in the rhizosphere of live and decomposing barley roots as affected by the antagonistic strain Pseudomonas fluorescens DR54BN14 or the fungicide imazalil

    Microsoft Academic Search

    Laila Thirup; Anders Johansen; Anne Winding

    2003-01-01

    The protocol used in the present study was a long-term mesocosm experiment where the microbial succession around live barley roots and subsequent decomposing roots was assessed after seed coating with either the antagonistic strain Pseudomonas fluorescens DR54-BN14 or the fungicide imazalil. Four diversity measures were used: community level physiological profiles (CLPP), Bacteria-specific polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE), actinomycete-specific

  8. Bacterial communities in manganese nodules in rice field subsoils: Estimation using PCR-DGGE and sequencing analyses

    Microsoft Academic Search

    Vita Ratri Cahyani; Jun Murase; Eiji Ishibashi; Susumu Asakawa; Makoto Kimura

    2007-01-01

    The phylogenetic positions of bacterial communities in manganese (Mn) nodules from subsoils of two Japanese rice fields were estimated using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis followed by sequencing of 16S rDNA. The DGGE band patterns and sequencing analysis of characteristic DGGE bands revealed that the bacterial communities in Mn nodules were markedly different from those in the

  9. Food Chain

    NSDL National Science Digital Library

    Idaho PTV

    2011-09-04

    This video segment from IdahoPTV's D4K describes how energy moves through nature. You will learn about the food chain, and its members: producers, consumers, scavengers. It shows where humans fit into the food chain.

  10. Food Chains

    NSDL National Science Digital Library

    Ms. Hammond

    2009-10-21

    In this project, you will discover the way food chains function by viewing four different types of food chains and designing your favorite one. How is the flow of energy traced through a food chain? Use your cluster organizer to record information for four different food chains and what the consumers, 1st level consumers, 2nd level consumers, and 3rd level consumers are and what they eat. Begin by viewing ecosystems: Introduction to Ecosystems Now that you know what an ...

  11. Falling chains

    Microsoft Academic Search

    Chun Wa Wong; Kosuke Yasui

    2005-01-01

    The one-dimensional fall of a folded chain with one end suspended from a rigid support and a chain falling from a resting heap on a table is studied. Because their Lagrangians contain no explicit time dependence, the falling chains are conservative systems. Their equations of motion are shown to contain a term that enforces energy conservation when masses are transferred

  12. DENSITY GRADIENT TECHNIQUES

    Microsoft Academic Search

    Gerald Oster; Masahide Yamamoto

    1963-01-01

    The most sensitive and simplest method for determining minute changes in ; density is the density gradient column technique, which is capable of detecting ; density differences as small as 10⁻⁷ g\\/cc. A review is presented of the ; theory and formation of the gradient, the movement of the test object in the ; gradient, and the applications of the

  13. Gradient coils and reciprocity

    Microsoft Academic Search

    J. C. Mallinson

    1991-01-01

    It is observed that the problem of optimizing the design of gradient coils is identical to the problem of optimizing the design of vibrating sample magnetometer (VSM) pick-up coils. The problem of optimizing the design of the gradient coils is that of maximizing the appropriate field gradient at the position of the magnetic sample depending on the design of the

  14. Computerized Simulation and Experimental Analysis for Efficient Polymerase Chain Reaction*

    E-print Network

    Computerized Simulation and Experimental Analysis for Efficient Polymerase Chain Reaction* Hee@plaza.snu.ac.kr Polymerase chain reaction (PCR) is a useful biochemical operation not only in biological application but also, Effectiveness of Denaturation Temperature Gradient-Polymerase Chain Reaction for Biased DNAAlgorithms

  15. Lipopolymer gradient diffusion in supported bilayer membranes

    PubMed Central

    Zhang, Huai-Ying; Hill, Reghan J.

    2011-01-01

    We measure the gradient diffusion coefficient of a model lipopolymer in supported lipid bilayer membranes from Fourier-transform post-electrophoresis relaxation. The experiments and accompanying quantitative interpretation furnish the concentration dependence of the gradient diffusion coefficient. In striking contrast to the recent measurements of the self-diffusion coefficient from fluorescence recovery after photobleaching, the lipopolymer gradient diffusion coefficient increases with concentration. We interpret the enhancement at small but finite concentrations using the Scalettar–Abney–Owicki (SAO) statistical mechanical theory (1988) and the Bussell–Koch–Hammer (BKH) hydrodynamic theory (1995), which are customarily adopted to model membrane protein dynamics. The SAO theory furnishes an effective disc radius and soft repulsive interaction radius that are comparable to the Flory radius of the unperturbed polyethylene glycol chains. On the other hand, the BKH theory predicts a gradient diffusion coefficient that decreases with disc/membrane protein concentration. Thus, in contrast to membrane proteins, we conclude that lipopolymer hydrodynamic interactions are weak because the principal disturbances are in the low-viscosity aqueous phase. Accordingly, lipopolymer interactions are dominated by thermodynamic interactions among polymer chains. Interestingly, our experiments suggest that increasing (decreasing) the polymer molecular weight should increase (decrease) the relaxation rate of lipopolymer concentration fluctuations. PMID:20702448

  16. Quantum computational gradient estimation

    E-print Network

    David Bulger

    2005-07-12

    Classically, determining the gradient of a black-box function f:R^p->R requires p+1 evaluations. Using the quantum Fourier transform, two evaluations suffice. This is based on the approximate local periodicity of exp(2*pi*i*f(x)). It is shown that sufficiently precise machine arithmetic results in gradient estimates of any required accuracy.

  17. Learning the Coordinate Gradients

    Microsoft Academic Search

    Yiming Ying; Qiang Wu; Colin Campbell

    In this paper we study the problem of learning the gradient function with application to variable selection and determining variable covariation. Firstly, we pro- pose a novel unifying framework for coordinate gradient learning from the perspective of multi-task learning. Various variable selection algorithms can be regarded as spe- cial instances of this framework. Secondly, we formulate the dual problems of

  18. Multilayer Gradient Coil Design

    Microsoft Academic Search

    R. Bowtell; P. Robyr

    1998-01-01

    In standard cylindrical gradient coils consisting of wires wound in a single layer, the rapid increase in coil resistance with efficiency is the limiting factor in achieving very large magnetic field gradients. This behavior results from the decrease in the maximum usable wire diameter as the number of turns is increased. By adopting a multilayer design in which the coil

  19. Gradient index metamaterials

    Microsoft Academic Search

    D. R. Smith; J. J. Mock; A. F. Starr; D. Schurig

    2005-01-01

    Metamaterials---artificially structured materials with tailored electromagnetic response---can be designed to have properties difficult or impossible to achieve with traditional materials fabrication methods. Here we present a structured metamaterial, based on conducting split ring resonators (SRRs), which has an effective index of refraction with a constant spatial gradient. We experimentally confirm the gradient by measuring the deflection of a microwave beam

  20. Very high gradient quadrupoles

    Microsoft Academic Search

    J. Strait

    2001-01-01

    High gradient superconducting quadrupoles are an essential component of high energy hadron colliders, both in the arcs and in the insertions. The highest performance quadrupoles today are those for the Large Hadron Collider (LHC) at CERN. These 56 to 70 mm aperture magnets, developed in Europe, the United States, and Japan, reach gradients on the order of 250 T\\/m, which

  1. Optical regulation of cell chain

    PubMed Central

    Liu, Xiaoshuai; Huang, Jianbin; Zhang, Yao; Li, Baojun

    2015-01-01

    Formation of cell chains is a straightforward and efficient method to study the cell interaction. By regulating the contact sequence and interaction distance, the influence of different extracellular cues on the cell interaction can be investigated. However, it faces great challenges in stable retaining and precise regulation of cell chain, especially in cell culture with relatively low cell concentration. Here we demonstrated an optical method to realize the precise regulation of cell chain, including removing or adding a single cell, adjusting interaction distance, and changing cell contact sequence. After injecting a 980-nm wavelength laser beam into a tapered optical fiber probe (FP), a cell chain of Escherichia colis (E. colis) is formed under the optical gradient force. By manipulating another FP close to the cell chain, a targeted E. coli cell can be trapped by the FP and removed from the chain. Further, the targeted cell can be added back to the chain at different positions to change the cell contact sequence. The experiments were interpreted by numerical simulations and the impact of cell sizes and shapes on this method was analyzed. PMID:26098707

  2. Optical regulation of cell chain.

    PubMed

    Liu, Xiaoshuai; Huang, Jianbin; Zhang, Yao; Li, Baojun

    2015-01-01

    Formation of cell chains is a straightforward and efficient method to study the cell interaction. By regulating the contact sequence and interaction distance, the influence of different extracellular cues on the cell interaction can be investigated. However, it faces great challenges in stable retaining and precise regulation of cell chain, especially in cell culture with relatively low cell concentration. Here we demonstrated an optical method to realize the precise regulation of cell chain, including removing or adding a single cell, adjusting interaction distance, and changing cell contact sequence. After injecting a 980-nm wavelength laser beam into a tapered optical fiber probe (FP), a cell chain of Escherichia colis (E. colis) is formed under the optical gradient force. By manipulating another FP close to the cell chain, a targeted E. coli cell can be trapped by the FP and removed from the chain. Further, the targeted cell can be added back to the chain at different positions to change the cell contact sequence. The experiments were interpreted by numerical simulations and the impact of cell sizes and shapes on this method was analyzed. PMID:26098707

  3. Falling chains

    Microsoft Academic Search

    Chun Wa Wong; Kosuke Yasui

    2006-01-01

    The one-dimensional fall of a folded chain with one end suspended from a\\u000arigid support and a chain falling from a resting heap on a table is studied.\\u000aBecause their Lagrangians contain no explicit time dependence, the falling\\u000achains are conservative systems. Their equations of motion are shown to contain\\u000aa term that enforces energy conservation when masses are transferred

  4. Fast Self-Healing Gradients

    E-print Network

    Beal, Jacob

    We present CRF-Gradient, a self-healing gradient algorithm that provably reconfigures in O(diameter) time. Self-healing gradients are a frequently used building block for distributed self-healing systems, but previous ...

  5. Type of automatic gradienter

    NASA Astrophysics Data System (ADS)

    Li, Shaohui; He, Liang; Zhang, Gang; Zhang, Zhipeng

    2000-05-01

    Aiming at the requirement that some kinds of big dynamo- electric equipments such as a dam gate of hydro-power plant or a elevator have to keep their balance in the process of being lifted and dropped, a novel and precise gradienter with high resolution and short response time is presented in this article. In this gradienter, the respective hydraulic pressure method is adopted.

  6. High Gradient Induction Cell

    SciTech Connect

    Caporaso, G J

    2004-11-29

    A concept being developed for high current electron beams may have application to HEDP and is described here. It involves the use of planar Blumlein stacks placed inside an induction cell. The output end of the Blumlein stack is applied across a high gradient insulator (HGI). These insulators have been used successfully in the presence of kilo Ampere-level electron beam currents for tens of nanoseconds at gradients of 20 MV/meter.

  7. Control over wettability via surface modification of porous gradients

    NASA Astrophysics Data System (ADS)

    Khung, Y. L.; Cole, M. A.; McInnes, S. J. P.; Voelcker, N. H.

    2007-12-01

    The control over surface wettability is of concern for a number of important applications including chromatography, microfluidics, biomaterials, low-fouling coatings and sensing devices. Here, we report the ability to tailor wettability across a surface using lateral porous silicon (pSi) gradients. Lateral gradients made by anodisation of silicon using an asymmetric electrode configuration showed a lateral distribution of pore sizes, which decreased with increasing distance from the electrode. Pore sizes were characterised using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Pore diameters ranged from micrometres down to less than 10 nanometres. Chemical surface modification of the pSi gradients was employed in order to produce gradients with different wetting or non-wetting properties. Surface modifications were achieved via silanisation of oxidised pSi surfaces introducing functionalities including polyethylene glycol, terminal amine and fluorinated hydrocarbon chains. Surface modifications were characterised using infrared spectroscopy. Sessile drop water contact angle measurements were used to probe the wettability in regions of different pore size across the gradient. For the fluorinated gradients, a comparison of equilibrium and dynamic contact angle measurement was undertaken. The fluorinated surface chemistry produced gradients with wettabilities ranging from hydrophobic to near super-hydrophobic whereas pSi gradients functionalised with polyethylene glycol showed graded hydrophilicity. In all cases investigated here, changes in pore size across the gradient had a significant effect on wettability.

  8. Thermophoresis of linear polymer chains

    NASA Astrophysics Data System (ADS)

    Bringuier, Eric

    2011-05-01

    The thermophoresis of a linear polymer chain in a solvent is examined theoretically and is shown to be due to the action of two forces. The first one is Waldmann's thermophoretic force (stemming from the departure of the molecular-velocity distribution from Maxwell's equilibrium distribution), which here is extrapolated to a dense medium by using scaling considerations. The second force is due to the fact that the viscous friction varies with position owing to the temperature gradient, which brings a zeroth-order correction to the Stokes law of friction. The present scaling theory is compared with recent experiments and is found to account for: (i) the existence of both signs of the thermodiffusion coefficient; (ii) the absolute magnitude of the coefficient; (iii) the fact that it is independent of the chain length in the high-polymer limit; and (iv) the dependence on solvent viscosity. The variation of the coefficient for short chains is also examined.

  9. Markov Chains

    NSDL National Science Digital Library

    David Smith

    Using Mathcad, Maple, Mathmatica, or MatLab, learner should be able to introduce the concepts of transition matrices and Markov chains; to provide motivation for the definition of matrix multiplication in the context of an interesting application; and to lay the groundwork for applied problems that can be solved later with eigenvalues and eigenvectors.

  10. High gradient superconducting quadrupoles

    SciTech Connect

    Lundy, R.A.; Brown, B.C.; Carson, J.A.; Fisk, H.E.; Hanft, R.H.; Mantsch, P.M.; McInturff, A.D.; Remsbottom, R.H.

    1987-07-01

    Prototype superconducting quadrupoles with a 5 cm aperture and gradient of 16 kG/cm have been built and tested as candidate magnets for the final focus at SLC. The magnets are made from NbTi Tevatron style cable with 10 inner and 14 outer turns per quadrant. Quench performance and multipole data are presented. Design and data for a low current, high gradient quadrupole, similar in cross section but wound with a cable consisting of five insulated conductors are also discussed.

  11. Uniform gradient expansions

    NASA Astrophysics Data System (ADS)

    Giovannini, Massimo

    2015-06-01

    Cosmological singularities are often discussed by means of a gradient expansion that can also describe, during a quasi-de Sitter phase, the progressive suppression of curvature inhomogeneities. While the inflationary event horizon is being formed the two mentioned regimes coexist and a uniform expansion can be conceived and applied to the evolution of spatial gradients across the protoinflationary boundary. It is argued that conventional arguments addressing the preinflationary initial conditions are necessary but generally not sufficient to guarantee a homogeneous onset of the conventional inflationary stage.

  12. HIGH GRADIENT INDUCTION ACCELERATOR

    SciTech Connect

    Caporaso, G J; Sampayan, S; Chen, Y; Blackfield, D; Harris, J; Hawkins, S; Holmes, C; Krogh, M; Nelson, S; Nunnally, W; Paul, A; Poole, B; Rhodes, M; Sanders, D; Selenes, K; Sullivan, J; Wang, L; Watson, J

    2007-06-21

    A new type of compact induction accelerator is under development at the Lawrence Livermore National Laboratory that promises to increase the average accelerating gradient by at least an order of magnitude over that of existing induction machines. The machine is based on the use of high gradient vacuum insulators, advanced dielectric materials and switches and is stimulated by the desire for compact flash x-ray radiography sources. Research describing an extreme variant of this technology aimed at proton therapy for cancer will be described. Progress in applying this technology to several applications will be reviewed.

  13. Length Scale Heterogeneity in Lateral Gradients of Poly(N-isopropylacrylamide) Polymer Brushes Prepared by

    E-print Network

    Braun, Paul

    Length Scale Heterogeneity in Lateral Gradients of Poly(N-isopropylacrylamide) Polymer BrushesATRPhavebeenusedtoprobe the effects of graft density10,13 and molecular weight14,15 on polymer brush surfaces. In our laboratory(N-isopropylacrylamide)(PNIPAAm)polymerbrushesexhibiting controlled lateral variations in the patchiness of polymer chains. These gradients were achieved through

  14. Chain Gang

    NASA Technical Reports Server (NTRS)

    2006-01-01

    6 August 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a chain of clustered and battered craters. These were formed by secondary impact. That is, somewhere to the south (beyond the bottom of this image), a large impact crater formed. When this occurred, material ejected from the crater was thrown tens to hundreds of kilometers away. This material then impacted the martian surface, forming clusters and chains of smaller craters.

    Location near: 15.8oN, 35.6oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Northern Spring

  15. Markov Chains

    NSDL National Science Digital Library

    Blake, Lewis

    Created by Lewis Blake for the Connected Curriculum Project, the purposes of this module are to introduce the concepts of transition matrices and Markov chains; to provide motivation for the definition of matrix multiplication in the context of an interesting application; and to lay the groundwork for applied problems that can be solved later with eigenvalues and eigenvectors. This is part of a larger collection of learning modules hosted by Duke University.

  16. Quantum Mechanical Heat Transport in Disordered Harmonic Chains

    E-print Network

    Christopher Gaul; Helmut Büttner

    2007-07-06

    We investigate the mechanism of heat conduction in ordered and disordered harmonic onedimensional chains within the quantum mechanical Langevin method. In the case of the disordered chains we find indications for normal heat conduction which means that there is a finite temperature gradient but we cannot clearly decide whether the heat resistance increases linearly with the chain length. Furthermore we observe characteristic quantum mechanical features like Bose-Einstein statistics of the occupation numbers of the normal modes, freezing of the heat conductivity and the influence of the entanglement within the chain on the current. For the ordered chain we recover some classical results like a vanishing temperature gradient and a heat flux independent of the length of the chain.

  17. Gradient Refractive Index Lenses.

    ERIC Educational Resources Information Center

    Morton, N.

    1984-01-01

    Describes the nature of gradient refractive index (GRIN) lenses, focusing on refraction in these materials, focal length of a thin Wood lens, and on manufacturing of such lenses. Indicates that GRIN lenses of small cross section are in limited production with applications suggested for optical communication and photocopying fields. (JN)

  18. Markov Chains

    NSDL National Science Digital Library

    Siegrist, Kyle

    Created by Kyle Siegrist of the University of Alabama-Huntsville, this is an online, interactive lesson on Markov chains. The author provides examples, exercises, and applets to introduce the subject. More specifically, the lesson covers: recurrence, transience, periodicity, time reversal, as well as invariant and limiting distributions. In addition, the author has provided links to external resources for further research. Overall, this is a great resource for those interested in this statistical process. It provides basic examples to introduce the topic, but also provides a more in-depth study to further challenge students.

  19. Food Chains and Webs

    NSDL National Science Digital Library

    Ms. Thompson

    2007-02-21

    Learn more about food chains, food webs, and how the organisms in them affect each other. In class, you have learned what food webs and food chains are. Today, you will explore how the organisms in these systems interact. Step One: Food Chains What happens when you take something out of a food chain? Go to the Chain Reaction website: Chain Reaction--Food Chains This internet site will help you ...

  20. Food Chain & Food Web

    NSDL National Science Digital Library

    Ms. B

    2011-10-27

    What are the differences and similarities between food chain and food web? Print (2) Garden Gate Print (1) Venn Diagram Garden Gate Venn Diagram Let's learn about the food chain and food web.Read the notes.Food Chain 4 Also, view more notes on food chain and food web. Go to the 7th title Food Chain which is before the Habitats and food chain title of the webpage.Food Chain Power Point Presentation Record what you learn ...

  1. Logistic chain modelling

    Microsoft Academic Search

    Piet A. Slats; Bis Bhola; Joseph J. M. Evers; Gert Dijkhuizen

    1995-01-01

    Logistic chain modelling is very important in improving the overall performance of the total logistic chain. Logistic models provide support for a large range of applications, such as analysing bottlenecks, improving customer service, configuring new logistic chains and adapting existing chains to new products and markets. Modelling the logistic chain is the main topic dealt with in this article. Recent

  2. The Food Chain

    NSDL National Science Digital Library

    Miss Jodi

    2009-07-07

    In this project you will learn about the food chain. In your notebook, write everything you know about the food chain and what you think goes at the top and bottom of the chain. After you write what you know go here to learn more about the food chain Food Chain Video. Click on "Play Movie." Now after watching the movie you should have ...

  3. Energy in density gradient

    NASA Astrophysics Data System (ADS)

    Vranjes, J.; Kono, M.

    2015-01-01

    Inhomogeneous plasmas and fluids contain energy stored in inhomogeneity and they naturally tend to relax into lower energy states by developing instabilities or by diffusion. But the actual amount of energy in such inhomogeneities has remained unknown. In the present work, the amount of energy stored in a density gradient is calculated for several specific density profiles in a cylindrical configuration. This is of practical importance for drift wave instability in various plasmas, and, in particular, in its application in models dealing with the heating of solar corona because the instability is accompanied with stochastic heating, so the energy contained in inhomogeneity is effectively transformed into heat. It is shown that even for a rather moderate increase of the density at the axis in magnetic structures in the corona by a factor 1.5 or 3, the amount of excess energy per unit volume stored in such a density gradient becomes several orders of magnitude greater than the amount of total energy losses per unit volume (per second) in quiet regions in the corona. Consequently, within the life-time of a magnetic structure such energy losses can easily be compensated by the stochastic drift wave heating.

  4. Pharmaceutical Supply Chain

    E-print Network

    Nagurney, Anna

    Engineering University of Hartford, West Hartford, CT 06117 #12;Pharmaceutical Supply Chain NetworksPharmaceutical Supply Chain Networks with Outsourcing Nagurney, Li, and Nagurney Pharmaceutical Supply Chain Networks with Outsourcing Under Price and Quality Competition Anna Nagurney1, Dong (Michelle

  5. Acquisition chain elements Conditioner

    E-print Network

    Ravelet, Florent

    Acquisition chain elements Sensor Conditioner Data acquisition and transfer Applications Signal: an introduction #12;Acquisition chain elements Sensor Conditioner Data acquisition and transfer Applications Outline 1 Acquisition chain elements 2 Sensor Different signals and sensors Characteristics of sensors 3

  6. Orbiting chains and rings

    NASA Technical Reports Server (NTRS)

    Breakwell, J. V.

    1983-01-01

    Two very different, highly flexible, space structures proposed during the last decade which involve analytical solution of certain partial differential equations are discussed. The first structure is an array, or hanging chain of aluminum beads which would serve as a convenient communicator if, under the influence of the Earth's gravity gradient, it assumes a local vertical orientation as it circles the Earth. Two passive schemes have been proposed for damping the rigid modes: twist the wire at the ends to provide non-zero moment of inertia about the vertical, thereby inducing relative motion of the two tips during rigid pitch or roll, and thus exercising a damper; and introduce weak lossy springs between the end sections and the main section; thereby providing linear coupling between the springs and all the in-plane (pitch) modes. The second structure is a complete ring of satellites cabled together at synchronous altitude. By a slight increase in altitude, the cable is in tension. This configuration is, however, unstable, and an active feedback control scheme is required to stabilize it. A possible scheme involves local cable length adjustment based on measurement of local altitude and shape variations and their rates.

  7. Single polymer gating of channels under a solvent gradient

    NASA Astrophysics Data System (ADS)

    Nath, S.; Foster, D. P.; Giri, D.; Kumar, S.

    2013-11-01

    We study the effect of a gradient of solvent quality on the coil-globule transition for a polymer in a narrow pore. A simple self-attracting, self-avoiding walk model of a polymer in solution shows that the variation in the strength of the interaction across the pore leads the system to go from one regime (good solvent) to the other (poor solvent) across the channel. This may be thought to be analogous to thermophoresis, where the polymer goes from the hot region to the cold region under the temperature gradient. The behavior of short chains is studied using exact enumeration while the behavior of long chains is studied using transfer matrix techniques. The distribution of the monomer density across the layer suggests that a gatelike effect can be created, with potential applications as a sensor.

  8. Crater Chains

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    The large crater at the top of this THEMIS visible image has several other craters inside of it. Most noticeable are the craters that form a 'chain' on the southern wall of the large crater. These craters are a wonderful example of secondary impacts. They were formed when large blocks of ejecta from an impact crashed back down onto the surface of Mars. Secondaries often form radial patterns around the impact crater that generated them, allowing researchers to trace them back to their origin.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

    Image information: VIS instrument. Latitude 19.3, Longitude 347.5 East (12.5 West). 19 meter/pixel resolution.

  9. Controlled E -field gradient coils

    Microsoft Academic Search

    P. Mansfield; R. M. Bowley; B. Haywood

    2003-01-01

    Peripheral neural stimulation is a major problem in current gradient coil designs. Induced current problems in patients relate\\u000a directly to gradient strength and modulation frequency. Current designs of gradient coil tend to limit ultra-high-speed imaging\\u000a methods such as echo-planar imaging through the effect of induced currents which produce tingling sensations and involuntary\\u000a muscle twitch. Neural stimulation could also trigger epileptic

  10. Safe Chain Saw Operation. 

    E-print Network

    Nelson, Gary S.

    1982-01-01

    action and prolong chain life. Follow your owner's manual instructions to adjust chain tension. A chain stretches with use. Most of this stretch will occur during the first half hour of operation. A cold chain should be tightened so the chain tie.... If it does not, remove the guide bar and check the chain oil discharge slot. During cold weather, you can dilute the oil with kerosene to insure even lubrication. You will need to lubricate the chain twice as often when using this mixture. When the chain...

  11. Charge gradient microscopy.

    PubMed

    Hong, Seungbum; Tong, Sheng; Park, Woon Ik; Hiranaga, Yoshiomi; Cho, Yasuo; Roelofs, Andreas

    2014-05-01

    Here we present a simple and fast method to reliably image polarization charges using charge gradient microscopy (CGM). We collected the current from the grounded CGM probe while scanning a periodically poled lithium niobate single crystal and single-crystal LiTaO3 thin film on the Cr electrode. We observed current signals at the domains and domain walls originating from the displacement current and the relocation or removal of surface charges, which enabled us to visualize the ferroelectric domains at a scan frequency above 78 Hz over 10 ?m. We envision that CGM can be used in high-speed ferroelectric domain imaging and piezoelectric energy-harvesting devices. PMID:24760831

  12. Empirical equation estimates geothermal gradients

    SciTech Connect

    Kutasov, I.M. (MultiSpectrum Technologies, Santa Monica, CA (United States))

    1995-01-02

    An empirical equation can estimate geothermal (natural) temperature profiles in new exploration areas. These gradients are useful for cement slurry and mud design and for improving electrical and temperature log interpretation. Downhole circulating temperature logs and surface outlet temperatures are used for predicting the geothermal gradients.

  13. Subspace gradient domain mesh deformation

    Microsoft Academic Search

    Jin Huang; Xiaohan Shi; Xinguo Liu; Kun Zhou; Li-yi Wei; Shang-hua Teng; Hujun Bao; Baining Guo; Heung-yeung Shum

    2006-01-01

    In this paper we present a general framework for performing con- strained mesh deformation tasks with gradient domain techniques. We present a gradient domain technique that works well with a wide variety of linear and nonlinear constraints. The constraints we introduce include the nonlinear volume constraint for volume preservation, the nonlinear skeleton constraint for maintaining the rigidity of limb segments

  14. Multilayer transverse gradient coil design

    Microsoft Academic Search

    J. Leggett; S. Crozier; S. Blackband; B. Beck; R. W. Bowtell

    2003-01-01

    In small, cylindrical gradient coils consisting of a single layer of wires, the limiting factor in achieving large magnetic field gradients is the rapid increase in coil resistance with efficiency. This behavior results from the decrease in the maximum usable wire diameter as the number of turns is increased. By adopting a multilayer design in which the coil wires are

  15. Height and gradient from shading

    Microsoft Academic Search

    Berthold K. P. Horn

    1990-01-01

    The method described here for recovering the shape of a surface from a shaded image can deal with complex, wrinkled surfaces. Integrability can be enforced easily because both surface height and gradient are represented (A gra- dient field is integrable if it is the gradient of some surface height function). The robustness of the method stems in part from linearization

  16. Rapid Gradient-Echo Imaging

    PubMed Central

    Hargreaves, Brian

    2012-01-01

    Gradient echo sequences are widely used in magnetic resonance imaging (MRI) for numerous applications ranging from angiography to perfusion to functional MRI. Compared with spin-echo techniques, the very short repetition times of gradient-echo methods enable very rapid 2D and 3D imaging, but also lead to complicated “steady states.” Signal and contrast behavior can be described graphically and mathematically, and depends strongly on the type of spoiling: fully balanced (no spoiling), gradient spoiling, or RF-spoiling. These spoiling options trade off between high signal and pure T1 contrast while the flip angle also affects image contrast in all cases, both of which can be demonstrated theoretically and in image examples. As with spin-echo sequences, magnetization preparation can be added to gradient-echo sequences to alter image contrast. Gradient echo sequences are widely used for numerous applications such as 3D perfusion imaging, functional MRI, cardiac imaging and MR angiography. PMID:23097185

  17. Gradient elution in capillary electrochromatography

    SciTech Connect

    Anex, D.; Rakestraw, D.J. [Sandia National Labs., Livermore, CA (United States); Yan, Chao; Dadoo, R.; Zare, R.N. [Stanford Univ., CA (United States). Dept. of Chemistry

    1997-08-01

    In analogy to pressure-driven gradient techniques in high-performance liquid chromatography, a system has been developed for delivering electroosmotically-driven solvent gradients for capillary electrochromatography (CEC). Dynamic gradients with sub-mL/min flow rates are generated by merging two electroosmotic flows that are regulated by computer-controlled voltages. These flows are delivered by two fused-silica capillary arms attached to a T-connector, where they mix and then flow into a capillary column that has been electrokinetically packed with 3-mm reversed-phase particles. The inlet of one capillary arm is placed in a solution reservoir containing one mobile phase and the inlet of the other is placed in a second reservoir containing a second mobile phase. Two independent computer-controlled programmable high-voltage power supplies (0-50 kV)--one providing an increasing ramp and the other providing a decreasing ramp--are used to apply variable high-voltage potentials to the mobile phase reservoirs to regulate the electroosmotic flow in each arm. The ratio of the electroosmotic flow rates between the two arms is changed with time according to the computer-controlled voltages to deliver the required gradient profile to the separation column. Experiments were performed to confirm the composition of the mobile phase during a gradient run and to determine the change of the composition in response to the programmed voltage profile. To demonstrate the performance of electroosmotically-driven gradient elution in CEC, a mixture of 16 polycyclic aromatic hydrocarbons (PAHs) was separated in less than 90 minutes. This gradient technique is expected to be well-suited for generating not only solvent gradients in CEC, but also other types of gradients such as pH- and ionic-strength gradients in capillary electrokinetic separations and analyses.

  18. Application of a food chain model to polychlorinated biphenyl contamination of the lobster and winter flounder food chains in New Bedford Harbor

    Microsoft Academic Search

    John P. Connolly

    1991-01-01

    As part of a Remedial Investigation\\/Feasibility Study for the New Bedford Harbor Superfund site a model of polychlorinated biphenyls (PCBs) in the lobster and winter flounder food chains was developed. This model successfully reproduces tri-, tetra-, penta-, and hexachlorobiphenyl concentrations observed at all levels of the food chain and across the 2 order of magnitude concentration gradient in the system.

  19. 680 Jones, Felderhof, Deutch Macromolecules If polymer chains are ruptured to a constant hydrody-

    E-print Network

    Deutch, John

    velocity gradient and under such conditions the Gaussian coil model is no longer possi- ble. On the other polymer chains might affect the shape of the coils. The authors suppose that polymer mole- cules velocity gradient. In any event, the authors suspect from the results that, even under a large velocity

  20. High field gradient particle accelerator

    DOEpatents

    Nation, J.A.; Greenwald, S.

    1989-05-30

    A high electric field gradient electron accelerator utilizing short duration, microwave radiation, and capable of operating at high field gradients for high energy physics applications or at reduced electric field gradients for high average current intermediate energy accelerator applications is disclosed. Particles are accelerated in a smooth bore, periodic undulating waveguide, wherein the period is so selected that the particles slip an integral number of cycles of the r.f. wave every period of the structure. This phase step of the particles produces substantially continuous acceleration in a traveling wave without transverse magnetic or other guide means for the particle. 10 figs.

  1. Gradient characterization in magnetic resonance imaging

    E-print Network

    Cheng, Joseph Yitan

    2007-01-01

    Special magnetic resonance (MR) scans, such as spiral imaging and echo-planar imaging, require speed and gradient accuracy while putting high demands on the MR gradient system that may cause gradient distortion. Additionally, ...

  2. SPECIAL FEATURE Latitudinal Gradients1

    E-print Network

    Agrawal, Anurag

    2261 SPECIAL FEATURE Latitudinal Gradients1 In 1772, J. R. Forster sailed with Captain Cook, and Forster sampled the flora throughout the Pacific. On his return, he published his account of the voyage

  3. Correlated Knowledge Gradients: Example alternatives

    E-print Network

    Keinan, Alon

    Correlated Knowledge Gradients: Example -4 -2 0 2 4 alternatives value 0 10 20 30 -10 -8 -6 -4 -2 0;Correlated Knowledge Gradients: Example -4 -2 0 2 4 alternatives value 0 10 20 30 -10 -8 -6 -4 -2 0 num measurements log(KGfactor) 0 10 20 30 0 0.5 1 1.5 2 num measurements opportunitycost #12;Correlated Knowledge

  4. Fabrication of a material assembly of silver nanoparticles using the phase gradients of optical tweezers.

    PubMed

    Yan, Zijie; Sajjan, Manas; Scherer, Norbert F

    2015-04-10

    Optical matter can be created using the intensity gradient and electrodynamic (e.g., optical binding) forces that nano- and microparticles experience in focused optical beams. Here we show that the force associated with phase gradient is also important. In fact, in optical line traps the phase gradient force is crucial in determining the structure and stability of optical matter arrays consisting of Ag nanoparticles (NPs). NP lattices can be repeatedly assembled and disassembled simply by changing the sign of the phase gradient. The phase gradient creates a compressive force (and thus a stress) in the optically bound Ag NP lattices, causing structural transitions (a stress response) from 1D "chains" to 2D lattices, and even to amorphous structures. The structural transitions and dynamics of driven transport are well described by electrodynamics simulations and modeling using a drift-diffusion Langevin equation. PMID:25910124

  5. Investigacin Supply chain collaboration

    E-print Network

    Boucherie, Richard J.

    Centro de Investigación Operativa I-2007-31 Supply chain collaboration Ana Meca and Judith Timmer number of retailers. In particular, we focus on two important aspects of supply chain collaboration Hernández de Elche Avda. de la Universidad s/n 03202 Elche (Alicante) #12;Chapter Number Supply Chain

  6. Polymer supply chain management

    Microsoft Academic Search

    Sukran Kadipasaoglu; Jennifer Captain; Mark James

    2008-01-01

    A typical polymer supply chain network includes multiple plants, large number of storage terminals, customers and consignment locations, and complex distribution requirements. Here, we describe the complexity of polymer supply chain from 'logical positivist\\/empiricist' viewpoint based on in-depth interviews with supply chain managers of four major polymer manufacturers and on our experience in the industry. We begin by defining marketplace

  7. Estimation of coastal density gradients

    NASA Astrophysics Data System (ADS)

    Howarth, M. J.; Palmer, M. R.; Polton, J. A.; O'Neill, C. K.

    2012-04-01

    Density gradients in coastal regions with significant freshwater input are large and variable and are a major control of nearshore circulation. However their measurement is difficult, especially where the gradients are largest close to the coast, with significant uncertainties because of a variety of factors - spatial and time scales are small, tidal currents are strong and water depths shallow. Whilst temperature measurements are relatively straightforward, measurements of salinity (the dominant control of spatial variability) can be less reliable in turbid coastal waters. Liverpool Bay has strong tidal mixing and receives fresh water principally from the Dee, Mersey, Ribble and Conwy estuaries, each with different catchment influences. Horizontal and vertical density gradients are variable both in space and time. The water column stratifies intermittently. A Coastal Observatory has been operational since 2002 with regular (quasi monthly) CTD surveys on a 9 km grid, an situ station, an instrumented ferry travelling between Birkenhead and Dublin and a shore-based HF radar system measuring surface currents and waves. These measurements are complementary, each having different space-time characteristics. For coastal gradients the ferry is particularly useful since measurements are made right from the mouth of Mersey. From measurements at the in situ site alone density gradients can only be estimated from the tidal excursion. A suite of coupled physical, wave and ecological models are run in association with these measurements. The models, here on a 1.8 km grid, enable detailed estimation of nearshore density gradients, provided appropriate river run-off data are available. Examples are presented of the density gradients estimated from the different measurements and models, together with accuracies and uncertainties, showing that systematic time series measurements within a few kilometres of the coast are a high priority. (Here gliders are an exciting prospect for detailed regular measurements to fill this gap.) The consequences for and sensitivity of circulation estimates are presented using both numerical and analytic models.

  8. Analysis and Improvement of Policy Gradient Estimation

    E-print Network

    Sugiyama, Masashi

    Analysis and Improvement of Policy Gradient Estimation Tingting Zhao, Hirotaka Hachiya, Gang Niu gradient methods. We first prove that the vari- ance of gradient estimates in the PGPE (policy gradients with parameter-based exploration) method is smaller than that of the classical REINFORCE method under a mild

  9. Dielectric gradient metasurface optical elements.

    PubMed

    Lin, Dianmin; Fan, Pengyu; Hasman, Erez; Brongersma, Mark L

    2014-07-18

    Gradient metasurfaces are two-dimensional optical elements capable of manipulating light by imparting local, space-variant phase changes on an incident electromagnetic wave. These surfaces have thus far been constructed from nanometallic optical antennas, and high diffraction efficiencies have been limited to operation in reflection mode. We describe the experimental realization and operation of dielectric gradient metasurface optical elements capable of also achieving high efficiencies in transmission mode in the visible spectrum. Ultrathin gratings, lenses, and axicons have been realized by patterning a 100-nanometer-thick Si layer into a dense arrangement of Si nanobeam antennas. The use of semiconductors can broaden the general applicability of gradient metasurfaces, as they offer facile integration with electronics and can be realized by mature semiconductor fabrication technologies. PMID:25035488

  10. Swarm equatorial electric field chain: First results

    NASA Astrophysics Data System (ADS)

    Alken, P.; Maus, S.; Chulliat, A.; Vigneron, P.; Sirol, O.; Hulot, G.

    2015-02-01

    The eastward equatorial electric field (EEF) in the E region ionosphere drives many important phenomena at low latitudes. We developed a method of estimating the EEF from magnetometer measurements of near-polar orbiting satellites as they cross the magnetic equator, by recovering a clean signal of the equatorial electrojet current and modeling the observed current to determine the electric field present during the satellite pass. This algorithm is now implemented as an official Level-2 Swarm product. Here we present first results of EEF estimates from nearly a year of Swarm data. We find excellent agreement with independent measurements from the ground-based coherent scatter radar at Jicamarca, Peru, as well as horizontal field measurements from the West African Magnetometer Network magnetic observatory chain. We also calculate longitudinal gradients of EEF measurements made by the A and C lower satellite pair and find gradients up to about 0.05 mV/m/deg with significant longitudinal variability.

  11. Gradient waveform synthesis for magnetic propulsion using MRI gradient coils

    Microsoft Academic Search

    B H Han; S Y Lee

    2008-01-01

    Navigating an untethered micro device in a living subject is of great interest for both diagnostic and therapeutic applications. Magnetic propulsion of an untethered device carrying a magnetic core in it is one of the promising methods to navigate the device. MRI gradients coils are thought to be suitable for navigating the device since they are capable of magnetic propulsion

  12. Space-time gradient metasurfaces

    E-print Network

    Hadad, Y; Alu, A

    2015-01-01

    Metasurfaces characterized by a transverse gradient of local impedance have recently opened exciting directions for light manipulation at the nanoscale. Here we add a temporal gradient to the picture, showing that spatio-temporal variations over a surface may largely extend the degree of light manipulation in metasurfaces, and break several of their constraints associated to symmetries. As an example, we synthesize a non-reciprocal classical analogue to electromagnetic induced transparency, opening a narrow window of one-way transmission in an otherwise opaque surface. These properties pave the way to magnetic free, planarized non-reciprocal ultrathin surfaces for free-space isolation.

  13. HIGH GRADIENT MAGNETIC PARTICULATE COLLECTION

    EPA Science Inventory

    This paper describes the initial phases of an evaluation of high gradient magnetic separation (HGMS) as a potential method of fine particle collection from industrial stack gases. HGMS is a relatively new separation technique that has been shown to be capable of removing small, w...

  14. Salt-gradient solar ponds

    SciTech Connect

    Neeper, D.A.

    1984-01-01

    A description of salt-gradient solar ponds is presented. Guidelines concerning the construction and maintenance of the pond are discussed. A computer model was used to study layer migration in laboratory tanks and in an outdoor pond. The status of solar ponds is briefly discussed. An equation relating heat flux and salt flux at a boundary is included. (BCS)

  15. COMPUTATIONAL COMPLEXITY OF INEXACT GRADIENT ...

    E-print Network

    2012-11-02

    AUGMENTED LAGRANGIAN METHODS: APPLICATION TO ... analysis relies on the Lipschitz property of the dual function and on inexact dual gradients. ... ery sampling instant at which new state information becomes available. ...... Thus, we conclude from Theorems 3.2, 3.3 and 3.4 that for these choices of kout and.

  16. Elevational Gradients in Species Richness

    E-print Network

    McCain, Christy M.

    Elevational Gradients in Species Richness Christy M McCain, University of Colorado, Boulder and fauna respond to these changes and how elevational species richness patterns have been stud- ied to uncover drivers of biodiversity. There are four main trends in elevational species richness: decreasing

  17. Gradient Tempering Of Bearing Races

    NASA Technical Reports Server (NTRS)

    Parr, Richardson A.

    1991-01-01

    Gradient-tempering process increases fracture toughness and resistance to stress-corrosion cracking of ball-bearing races made of hard, strong steels and subject to high installation stresses and operation in corrosive media. Also used in other applications in which local toughening of high-strength/low-toughness materials required.

  18. Wavefront reconstruction from its gradients

    Microsoft Academic Search

    Amos Talmi; Erez N. Ribak

    2006-01-01

    Wavefronts reconstructed from measured gradients are composed of a straightforward integration of the measured data, plus a correction term that disappears when there are no measurement errors. For regions of any shape, this term is a solution of Poisson's equation with Dirichlet conditions (V=0 on the boundaries). We show that for rectangular regions, the correct solution is not a periodic

  19. GENERALIZED STOCHASTIC GRADIENT LEARNING &ast

    Microsoft Academic Search

    George W. Evans; Seppo Honkapohja; Noah Williams

    2010-01-01

    We study the properties of the generalized stochastic gradient (GSG) learning in forward-looking models. GSG algorithms are a natural and convenient way to model learning when agents allow for parameter drift or robustness to parameter uncertainty in their beliefs. The conditions for convergence of GSG learning to a rational expectations equilibrium are distinct from but related to the well-known stability

  20. Magnetic Resonance Imaging with Composite (Dual) Gradients

    PubMed Central

    Parker, Dennis L.; Goodrich, K. Craig; Hadley, J. Rock; Kim, Seong-Eun; Moon, Sung M.; Chronik, Blaine A.; Fontius, Ulrich; Schmitt, Franz

    2009-01-01

    The tradeoff between gradient performance factors, size of the imaging region, and physiological factors such as nerve stimulation typically leads to compromises in gradient design and ultimately suboptimal imaging performance. Local gradient systems can add some performance flexibility, but are cumbersome to set up and remove. In nearly all conventional MRI systems, the use of local gradients precludes the use of the more homogeneous whole body gradients. This paper presents the concept of dynamically selectable composite gradient systems where local gradients and whole body gradients can be selected independently and simultaneously. The relative performance of whole body, insert, and composite gradients is predicted for echoplanar (EPI), turbo spin echo (TSE), and steady state free precession (SSFP). A realization of the concept is presented. PMID:20160925

  1. Temperature Gradient Capillary Electrophoresis (TGCE) Related Protocols 1 TEMPERATURE GRADIENT CAPILLARY

    E-print Network

    Wurtele, Eve Syrkin

    Temperature Gradient Capillary Electrophoresis (TGCE) Related Protocols 1 TEMPERATURE GRADIENT CAPILLARY ELECTROPHORESIS (TGCE) RELATED PROTOCOLS (Last Revised: April, 2007) These protocols were Gradient Capillary Electrophoresis (TGCE) Related Protocols 2 PCR program used to denature/re-anneal mixed

  2. Corrosion in a temperature gradient

    SciTech Connect

    Covino, Bernard S., Jr.; Holcomb, Gordon R.; Cramer, Stephen D.; Bullard, Sophie J.; Ziomek-Moroz, Margaret; White, M.L. (Convanta)

    2003-01-01

    High temperature corrosion limits the operation of equipment used in the Power Generation Industry. Some of the more destructive corrosive attack occurs on the surfaces of heat exchangers, boilers, and turbines where the alloys are subjected to large temperature gradients that cause a high heat flux through the accumulated ash, the corrosion product, and the alloy. Most current and past corrosion research has, however, been conducted under isothermal conditions. Research on the thermal-gradient-affected corrosion of various metals and alloys is currently being studied at the Albany Research Center’s SECERF (Severe Environment Corrosion and Erosion Research Facility) laboratory. The purpose of this research is to verify theoretical models of heat flux effects on corrosion and to quantify the differences between isothermal and thermal gradient corrosion effects. The effect of a temperature gradient and the resulting heat flux on corrosion of alloys with protective oxide scales is being examined by studying point defect diffusion and corrosion rates. Fick’s first law of diffusion was expanded, using irreversible thermodynamics, to include a heat flux term – a Soret effect. Oxide growth rates are being measured for the high temperature corrosion of cobalt at a metal surface temperature of 900ºC. Corrosion rates are also being determined for the high temperature corrosion of carbon steel boiler tubes in a simulated waste combustion environment consisting of O2, CO2, N2, and water vapor. Tests are being conducted both isothermally and in the presence of a temperature gradient to verify the effects of a heat flux and to compare to isothermal oxidation.

  3. Supply chain planning classification

    NASA Astrophysics Data System (ADS)

    Hvolby, Hans-Henrik; Trienekens, Jacques; Bonde, Hans

    2001-10-01

    Industry experience a need to shift in focus from internal production planning towards planning in the supply network. In this respect customer oriented thinking becomes almost a common good amongst companies in the supply network. An increase in the use of information technology is needed to enable companies to better tune their production planning with customers and suppliers. Information technology opportunities and supply chain planning systems facilitate companies to monitor and control their supplier network. In spite if these developments, most links in today's supply chains make individual plans, because the real demand information is not available throughout the chain. The current systems and processes of the supply chains are not designed to meet the requirements now placed upon them. For long term relationships with suppliers and customers, an integrated decision-making process is needed in order to obtain a satisfactory result for all parties. Especially when customized production and short lead-time is in focus. An effective value chain makes inventory available and visible among the value chain members, minimizes response time and optimizes total inventory value held throughout the chain. In this paper a supply chain planning classification grid is presented based current manufacturing classifications and supply chain planning initiatives.

  4. Excellent supply chain management

    Microsoft Academic Search

    Yahia Zare Mehrjerdi

    2009-01-01

    Purpose – The purpose of this paper is to review the fundamental concept of supply chain management (SCM) and discusses the facts that a road to success in the process of design, development, implementation and operation of a supply chain (SC) is the identification of superior strategies and clear objectives. To understand important SC strategies for a complete success, main

  5. Critical Chain Exercises

    ERIC Educational Resources Information Center

    Doyle, John Kevin

    2010-01-01

    Critical Chains project management focuses on holding buffers at the project level vs. task level, and managing buffers as a project resource. A number of studies have shown that Critical Chain project management can significantly improve organizational schedule fidelity (i.e., improve the proportion of projects delivered on time) and reduce…

  6. The liquefied energy chain

    Microsoft Academic Search

    Audun Aspelund; Truls Gundersen

    2009-01-01

    The Liquefied Energy Chain (LEC) is a novel energy and cost effective transport chain for stranded natural gas utilized for power production with CO2 capture and storage. The LEC has better efficiency and lower investment costs than existing technology, and shows potential for utilization of stranded natural gas with CO2 sequestration on a commercially sound basis.

  7. Approximating Markov Chains

    Microsoft Academic Search

    Steven M. Pincus

    1992-01-01

    A common framework of finite state approximating Markov chains is developed for discrete time deterministic and stochastic processes. Two types of approximating chains are introduced: (i) those based on stationary conditional probabilities (time averaging) and (ii) transient, based on the percentage of the Lebesgue measure of the image of cells intersecting any given cell. For general dynamical systems, stationary measures

  8. High gradient directional solidification furnace

    NASA Technical Reports Server (NTRS)

    Aldrich, B. R.; Whitt, W. D. (inventor)

    1985-01-01

    A high gradient directional solidification furnace is disclosed which includes eight thermal zones throughout the length of the furnace. In the hot end of the furnace, furnace elements provide desired temperatures. These elements include Nichrome wire received in a grooved tube which is encapsulated y an outer alumina core. A booster heater is provided in the hot end of the furnace which includes toroidal tungsten/rhenium wire which has a capacity to put heat quickly into the furnace. An adiabatic zone is provided by an insulation barrier to separate the hot end of the furnace from the cold end. The old end of the furnace is defined by additional heating elements. A heat transfer plate provides a means by which heat may be extracted from the furnace and conducted away through liquid cooled jackets. By varying the input of heat via the booster heater and output of heat via the heat transfer plate, a desired thermal gradient profile may be provided.

  9. Exploring quality in gradient copolymers.

    PubMed

    Elsen, Andrea M; Li, Yuanchao; Li, Qiaoxi; Sheiko, Sergei S; Matyjaszewski, Krzysztof

    2014-01-01

    Quality of gradient copolymers is evaluated by atomic force microscopy (AFM) and correlated with molecular weight distribution (MWD) values. ARGET ATRP is employed with decreasing levels of catalyst concentrations to generate copolymers with increasing M¯w/M¯n values. The copolymers are transformed into molecular bottlebrushes to enable imaging and analysis of individual molecules by AFM. The average height (cross-sectional) profile of all bottlebrushes agrees with the instantaneous composition (ICHEMA-TMS ) of the analogous copolymer backbone, as determined by (1) H NMR. The copolymer synthesized with 500 ppm of catalyst exhibits more narrow distributions of both brush height and backbone length when analyzed as a bottlebrush by AFM. Correspondingly, the copolymers synthesized with lower catalyst concentrations yield bottlebrushes with broader height and length distribution. These results establish MWD values as an excellent trait to assess quality within gradient copolymers. PMID:24150838

  10. Abundance gradients and galaxy formation

    NASA Astrophysics Data System (ADS)

    Stiavelli, M.; Matteucci, F.

    1991-08-01

    A three-dimensional collisionless code is used to simulate the formation of elliptical galaxies with a time scale for star formation comparable to the collapse time. A one-zone chemical evolution scheme is used to compute the evolution of the abundances of several chemical elements. The initial 'clumpy' system is made of gas and, in some cases, of warm dark matter. In the latter case, it is shown that abundance gradients are produced. For a galaxy of 10 to the 11th solar mass of gas and 3 x 10 to the 11th solar mass of warm dark matter, the predicted gradients of Fe and Mg are d(Fe/H)/d log r = -0.11 and d(Mg/H)/d log r = -0.05, respectively. In the absence of dark matter a greater amount of dissipation is required to produce abundance gradients. The mechanism proposed here should be relevant for bright and extended objects where there is evidence for the presence of dark matter.

  11. Pulsed-Field Gradient Nuclear Magnetic

    E-print Network

    Duncan, James S.

    Pulsed-Field Gradient Nuclear Magnetic Resonance as a Tool for Studying Translational Diffusion and biochemical systems. Pulsed-field gradient nuclear magnetic resonance pro- vides a convenient and noninvasive spin-echo pulse sequence contain- ing a magnetic field gradient pulse in each period is used to measure

  12. Gradient domain high dynamic range compression

    Microsoft Academic Search

    Raanan Fattal; Dani Lischinski; Michael Werman

    2002-01-01

    We present a new method for rendering high dynamic range images on conventional displays. Our method is conceptually simple, computationally efficient, robust, and easy to use. We manipulate the gradient field of the luminance image by attenuating the magnitudes of large gradients. A new, low dynamic range image is then obtained by solving a Poisson equation on the modified gradient

  13. Determining frac gradients while drilling. [Oil well

    Microsoft Academic Search

    R. Cesaroni; D. Giacca; A. Schenato; B. Thierree

    1981-01-01

    The method proposed in this study uses the following format: (1) starting from Sigmalog computations, drilling porosities in sand and shale formations are estimated with proper formulas, (2) these porosities are transformed into bulk densities, and (3) bulk densities are converted into overburden gradients. The pore pressure gradient calculated from the Sigmalog analysis makes evaluation of fracture gradients possible while

  14. Structural analysis of gradient elastic components

    Microsoft Academic Search

    A. E. Giannakopoulos; K. Stamoulis

    2007-01-01

    The present study investigates the size effects in the problems of cantilever beam bending and cracked bar tension within the gradient elasticity framework. Analytical solutions for metrics that characterize both the normalized stiffness and toughness are derived. It is found that the gradient elastic beam exhibits a significantly stiffer but also more brittle response, while the gradient cracked bar exhibits

  15. Real-time gradient-domain painting

    Microsoft Academic Search

    James Mccann; Nancy S. Pollard

    2008-01-01

    We present an image editing program which allows artists to paint in the gradient domain with real-time feedback on megapixel- sized images. Along with a pedestrian, though powerful, gradient- painting brush and gradient-clone tool, we introduce an edge brush designed for edge selection and replay. These brushes, coupled with special blending modes, allow users to accomplish global lighting and contrast

  16. Pulsed-Field Gradient Nuclear Magnetic

    E-print Network

    Duncan, James S.

    , under software control, which can send current pulses to a gradient coil placed around Z .the sample FigGradient Nuclear Magnetic Resonance as a Tool for Studying Translational Diffusion the theoretical basis behind the pulsed-field gradient nuclear magnetic resonance method for measuring diffusion

  17. 3D Gradient coil design – Toroidal surfaces

    Microsoft Academic Search

    Peter T. While; Larry K. Forbes; Stuart Crozier

    2009-01-01

    Gradient coil design typically involves optimisation of current densities or coil windings on familiar cylindrical, planar, spherical or conical surfaces. In this paper, an analytic inverse method is presented for the theoretical design of toroidal transverse gradient coils. This novel geometry is based on previous work involving a 3D current density solution, in which the precise geometry of the gradient

  18. 3D Gradient coil design - Toroidal surfaces

    Microsoft Academic Search

    Peter T. While; Larry K. Forbes; Stuart Crozier

    2009-01-01

    Gradient coil design typically involves optimisation of current densities or coil windings on familiar cylindrical, planar, spherical or conical surfaces. In this paper, an analytic inverse method is presented for the theoretical design of toroidal transverse gradient coils. This novel geometry is based on previous work involving a 3D current density solution, in which the precise geometry of the gradient

  19. Introduction Quantifying high-gradient behavior

    E-print Network

    Kuhn, Matthew R.

    Introduction Quantifying high-gradient behavior Summary Continuum Models of Discrete Particle-Discrete Granular Models with Bending #12;Introduction Quantifying high-gradient behavior Summary Outline 1 Introduction 2 Quantifying high-gradient behavior DEM "bending" experiments Questions about granular behavior

  20. Evaluation of gradient inhomogeneity in the optimal design of gradient coils

    Microsoft Academic Search

    Y. Peter Du; Dennis L. Parker

    1996-01-01

    The image distortion caused by gradient inhomogeneity was derived from the image equation of Fourier MR imaging. A measurement of gradient inhomogeneity was proposed based on the amount of image distortion. Using the proposed measurement of gradient inhomogeneity in the optimal design of a z-gradient coil reduced image distortion by 39–45% compared to a previously used figure of merit in

  1. Self-assembling gradient copolymers of vinylimidazol and (acrylic)ibuprofen with anti-inflammatory and zinc chelating properties.

    PubMed

    Suárez, Patricia; Rojo, Luis; González-Gómez, Álvaro; Román, Julio San

    2013-09-01

    Novel gradient copolymers of hydrophilic 1-vinylimidazol and hydrophobic methacrylic derivative of ibuprofen prepared by free radical polymerization are described. The heterogeneous distribution of monomeric units along the polymeric chains leads to a gradient distribution of the hydrophobic and hydrophilic sequences responsible of nanoparticles formation through a self-assembling mechanism, capable of tune the water permeation due to the ionizable imidazole moieties and their gradient profile along the macromolecules, exhibiting pH and composition dependent effect in terms of diameter, zeta potential, acid-base buffering, ibuprofen release and chelating capacities, responsible of matrix metalloproteinase dysfunction showing anti-inflammatory activity in a nitric oxide inhibition assay. PMID:23836487

  2. Quasiperiodic hubbard chains.

    PubMed

    Hida, K

    2001-02-12

    Low-energy properties of half-filled Fibonacci Hubbard models are studied by weak-coupling renormalization group and density matrix renormalization group methods. In the case of diagonal modulation, weak Coulomb repulsion is irrelevant and the system behaves as a free Fibonacci chain, while for strong Coulomb repulsion the charge sector becomes a Mott insulator and the spin sector behaves as a uniform Heisenberg antiferromagnetic chain. The off-diagonal modulation always drives the charge sector to a Mott insulator and the spin sector to a Fibonacci antiferromagnetic Heisenberg chain. PMID:11178076

  3. Biomolecular gradients in cell culture systems

    PubMed Central

    Keenan, Thomas M.

    2013-01-01

    Biomolecule gradients have been shown to play roles in a wide range of biological processes including development, inflammation, wound healing, and cancer metastasis. Elucidation of these phenomena requires the ability to expose cells to biomolecule gradients that are quantifiable, controllable, and mimic those that are present in vivo. Here we review the major biological phenomena in which biomolecule gradients are employed, traditional in vitro gradient-generating methods developed over the past 50 years, and new microfluidic devices for generating gradients. Microfluidic gradient generators offer greater levels of precision, quantitation, and spatiotemporal gradient control than traditional methods, and may greatly enhance our understanding of many biological phenomena. For each method, we outline the salient features, capabilities, and applications. PMID:18094760

  4. Improving supply chain resilience

    E-print Network

    Leung, Elsa Hiu Man

    2009-01-01

    Due to the global expansion of Company A's supply chain network, it is becoming more vulnerable to many disruptions. These disruptions often incur additional costs; and require time to respond to and recover from these ...

  5. Immunoglobulin light chain amyloidosis.

    PubMed

    Merlini, Giampaolo; Comenzo, Raymond L; Seldin, David C; Wechalekar, Ashutosh; Gertz, Morie A

    2014-02-01

    Primary light chain amyloidosis is the most common form of systemic amyloidosis and is caused by misfolded light chains that cause proteotoxicity and rapid decline of vital organ function. Early diagnosis is essential in order to deliver effective therapy and prevent irreversible organ damage. Accurate diagnosis requires clinical skills and advanced technologies. The disease can be halted and the function of target organs preserved by the prompt reduction and elimination of the plasma cell clone producing the toxic light chains in the bone marrow. Heart damage is the major determinant of survival, and staging with cardiac biomarkers guides treatment. Two-thirds of patients can benefit from treatment with improved quality of life and extended survival. Future efforts should be directed at early diagnosis, improving the tolerability and efficacy of anti-plasma cell therapy, accelerating recovery of organ function via promoting resorption of amyloid deposits, and developing novel approaches to counter light chain proteotoxicity. PMID:24350907

  6. SCIENCE MATTERS KEY CHAIN

    NSDL National Science Digital Library

    1900-01-01

    Brushed nickel key chain commemorating the launch of the new Science Matters initiative. Limited edition. All proceeds from the sale of this item go to fund the John Glenn Center for Science Education.

  7. Polymerase Chain Reaction

    NSDL National Science Digital Library

    2009-09-08

    This interactive activity adapted from the University of Nebraska's Library of Crop Technologies depicts steps in the polymerase chain reaction (PCR) technique and explains how it is used to efficiently copy sections of DNA for analysis.

  8. Chain or Web?

    NSDL National Science Digital Library

    This reference provides a brief description of marine food webs. It presents food web terminology, explains the relationship between food chains and food webs, and introduces the concept of microbial loops.

  9. Food Chains: Nature's Restaurant

    NSDL National Science Digital Library

    Jane Schaffran

    In these life science activities, students will participate in field observations of living things & do research of animals they observe to create a food chain & present it to the class. Students will participate in a food web simulation game.

  10. Food Chains and Webs

    NSDL National Science Digital Library

    2012-06-26

    In this activity, learners investigate feeding relationships. Learners complete a food web and then make a mobile to represent a food chain. Use this activity to talk about predator/prey relationships and ecosystems.

  11. THE GRADIENT OF VASCULAR PERMEABILITY

    PubMed Central

    Rous, Peyton; Gilding, H. P.; Smith, Frederick

    1930-01-01

    The permeability of the capillaries in the skeletal muscles of mammals increases progressively along their course and is greatest where they pass into the least venules. The gradient of permeability is so largely independent of functional states as to give grounds for the view that it is determined by inherent local differences. Through the gradient opportunity is equalized along the capillary. In the liver lobule this object is accomplished by an artifice of arrangement whereby the blood flow past the cells is increased with their distance from the source of supply. In the urinary bladder the interlacing of capillaries, their progressive widening, and a consequent gradual slowing of the blood flow act to achieve the same end. Here a gradient of permeability has not been demonstrable. Where cells of different sorts are served by a slender capillary, their differing requirements may render unnecessary any provision to equalize their opportunities; but where shortcomings in local maintenance will reduce the efficiency of an entire fabric, as the muscle fibre, and where cells of like character live competitively along the same channel, as in the liver, some arrangement must exist to ensure an even distribution of the services rendered by the blood. In situations of the kind last mentioned the immediate environment of the individual cell, the "milieu interne" of Bernard, is not only kept as constant as possible but it must be the same, by and large, for all of the cells. The task of serving voluntary muscle is not strictly limited to the capillaries. The intrafascicular arterioles and venules act so effectively to sustain the tissue about them that where they run no capillaries are supplied. PMID:19869729

  12. Ideal chain (entropic elasticity)

    NSDL National Science Digital Library

    2013-06-21

    In the first video segment, we present a cartoon model of a weighted chain, which can be regarded as an approximation for a polymer under tension (e.g. a strand of DNA being stretched out using optical tweezers). The Hamiltonian and partition function for this system are described in the second segment. Finally, in the third segment, we calculate the average energy and elongation of the chain.

  13. Ligase Chain Reaction

    Microsoft Academic Search

    Carla Osiowy

    \\u000a Nucleic acid amplification technologies have greatly facilitated medical diagnostics for genetic and infectious diseases through\\u000a the exquisite sensitivity and specificity associated with these methods. Polymerase chain reaction (PCR) (see\\u000a Chapter 6) ushered in these technologies and was soon accompanied by numerous newly developed amplification techniques, including\\u000a ligase chain reaction (LCR). These nucleic acid amplification techniques result in the exponential increase

  14. Temperature Gradient in Hall Thrusters

    SciTech Connect

    D. Staack; Y. Raitses; N.J. Fisch

    2003-11-24

    Plasma potentials and electron temperatures were deduced from emissive and cold floating probe measurements in a 2 kW Hall thruster, operated in the discharge voltage range of 200-400 V. An almost linear dependence of the electron temperature on the plasma potential was observed in the acceleration region of the thruster both inside and outside the thruster. This result calls into question whether secondary electron emission from the ceramic channel walls plays a significant role in electron energy balance. The proportionality factor between the axial electron temperature gradient and the electric field is significantly smaller than might be expected by models employing Ohmic heating of electrons.

  15. Generalized Gradient Approximation Made Simple

    SciTech Connect

    Perdew, J.P.; Burke, K.; Ernzerhof, M. [Department of Physics and Quantum Theory Group, Tulane University, New Orleans, Louisiana 70118 (United States)] [Department of Physics and Quantum Theory Group, Tulane University, New Orleans, Louisiana 70118 (United States)

    1996-10-01

    Generalized gradient approximations (GGA{close_quote}s) for the exchange-correlation energy improve upon the local spin density (LSD) description of atoms, molecules, and solids. We present a simple derivation of a simple GGA, in which all parameters (other than those in LSD) are fundamental constants. Only general features of the detailed construction underlying the Perdew-Wang 1991 (PW91) GGA are invoked. Improvements over PW91 include an accurate description of the linear response of the uniform electron gas, correct behavior under uniform scaling, and a smoother potential. {copyright} {ital 1996 The American Physical Society.}

  16. Image segmentation and analysis via multiscale gradient watershed hierarchies

    E-print Network

    Gauch, John M.

    1999-01-01

    , intensity ridges, and grey-level blobs. In this paper, we investigate the multiscale behavior of gradient watershed regions. These regions are defined in terms of the gradient properties of the gradient magnitude of the original image. Boundaries of gradient...

  17. New mooring chain designs

    SciTech Connect

    Canada, L.; Vicinay, J.; Sanz, A.; Lopez, E.

    1996-12-31

    The present work introduces the readers to the developments the high technology offshore chain industry has carried out in recent years, in an effort to offer products that meet the needs of petroleum exploration and production. In this manner the industry can continue to regard chain as a fundamental element in its moorings system, whether for projects with a 25 year life, or projects at depths of over 1,000 meters, or in such severe environments as those faced in the Sub-Arctic. Data are presented on Studless Chain and VGW or Variable Geometry and Weight chain. These will allow engineers designers to forget the needs for chains to be circumscribed to rigid guidelines of geometry or dimensions. Instead they can design mooring systems specific for the particular situations they face. No longer shall chain have to meet geometric standardization derived from the middle of the 19th century while meeting the requirements of the 2nd half of the 20th century.

  18. Supply chain forecasting – Collaborative forecasting supports supply chain management

    Microsoft Academic Search

    Marilyn M. Helms; Lawrence P. Ettkin; Sharon Chapman

    2000-01-01

    Supply chain management is built on the principles of partnerships and the development and use of the connections that exist between the links of the chain to provide information that will increase the efficiency of all members in the chain. Success stories abound describing lower costs, shorter lead times and increased customer service. Collaborative forecasting applies supply chain management concepts

  19. Lexical Chains Segmentation in Summarization

    Microsoft Academic Search

    Doina Tatar; Andreea Diana Mihis; Gabriela Serban Czibula

    2008-01-01

    In this paper we propose a new method of linear text segmentation based on lexical cohesion of a text. The usual steps (to compute the lexical chains according to relatedness criteria, to score the chains after different parameters,to select the strong chains, to obtain the segments) are replaced by a single procedure. Namely, a single chain of disambiguated words in

  20. Pictish chains and Welsh forgeries

    Microsoft Academic Search

    Andrew Breeze

    The Pictish silver chains can be shown to be 12 in number, and not 10 as often stated. The evidence of a Welsh chronicle that the chains were royal insignia is worthless, because the chronicle is an 18th- century forgery. PICTISH CHAINS A striking feature of Pictish art is the series of massive silver chains found at locations from Inverness

  1. The Global Supply Chain Institute

    E-print Network

    Tennessee, University of

    organization: collaboration with customers and suppliers areas to ensure that both customer and supply chainThe Global Supply Chain Institute World Class. Worldwide. Looking for ways to expand your supply chain knowledge and professional network? The University of Tennessee's Global Supply Chain Institute

  2. Detonation Initiation by a Temperature Gradient for a Detailed Chemical Reaction Models

    NASA Astrophysics Data System (ADS)

    Liberman, Michael; Kiverin, Alexey; Chukalovsky, Alexander; Ivanov, Mikhail

    2011-04-01

    The evolution from a temperature gradient to a detonation is investigated using high resolution numerical simulations for combustion mixture whose chemistry is governed by a detailed chemical kinetics. We employ a model representing an initial linear temperature gradient in the fuel. Emphasis is on comparing the results with previous studies that used simple one-step kinetics. It is shown that the evolution to detonation from temperature nonuniformities is considerably different for one-step kinetics models than for chain-branching kinetic models and it is different in different fuels for the same initial conditions. A detailed chemical model has a profound effect on the validity of Zel'dovich's spontaneous wave concept for detonation initiation by a gradient of reactivity. The evolution to detonation from a temperature gradient is considered for hydrogen-air and methane-air mixtures at different initial pressures. The analysis shows that for a detailed chemical kinetics the temperature gradients, which was thought to appear in the form of hot spots and the like, are not satisfy the criteria to initiate detonation, and the gradient mechanism can not be origin of the deflagration-to-detonation transition.

  3. A micromechanical damage and fracture model for polymers based on fractional strain-gradient elasticity

    NASA Astrophysics Data System (ADS)

    Heyden, S.; Li, B.; Weinberg, K.; Conti, S.; Ortiz, M.

    2015-01-01

    We formulate a simple one-parameter macroscopic model of distributed damage and fracture of polymers that is amenable to a straightforward and efficient numerical implementation. We show that the macroscopic model can be rigorously derived, in the sense of optimal scaling, from a micromechanical model of chain elasticity and failure regularized by means of fractional strain-gradient elasticity. In particular, we derive optimal scaling laws that supply a link between the single parameter of the macroscopic model, namely, the critical energy-release rate of the material, and micromechanical parameters pertaining to the elasticity and strength of the polymer chains and to the strain-gradient elasticity regularization. We show how the critical energy-release rate of specific materials can be determined from test data. Finally, we demonstrate the scope and fidelity of the model by means of an example of application, namely, Taylor-impact experiments of polyurea 1000 rods.

  4. Crystalline-gradient polycarbonates prepared from enantioselective terpolymerization of meso-epoxides with CO2

    NASA Astrophysics Data System (ADS)

    Liu, Ye; Ren, Wei-Min; He, Ke-Ke; Lu, Xiao-Bing

    2014-12-01

    The development of efficient processes for CO2 transformation into useful products is a long-standing goal for chemists, since CO2 is an abundant, inexpensive and non-toxic renewable C1 resource. Here we describe the enantioselective copolymerization of 3,4-epoxytetrahydrofuran with CO2 mediated by biphenol-linked dinuclear cobalt complex, affording the corresponding polycarbonate with >99% carbonate linkages and excellent enantioselectivity (up to 99% enantiomeric excess). Notably, the resultant isotactic polycarbonate is a typical semicrystalline polymer, possessing a melting point of 271?°C. Furthermore, the enantioselective terpolymerization of 3,4-epoxytetrahydrofuran, cyclopentene oxide and CO2 mediated by this dinuclear cobalt complex gives novel gradient polycarbonates, in which the decrement of one component and the increment of the other component occur sequentially from one chain end to the other end. The resultant terpolymers show perfectly isotactic structure and have unique crystalline-gradient nature, in which the crystallinity continuously varies along the main chain.

  5. Denaturing Gradient Gel Electrophoresis Can Rapidly Display the Bacterial Diversity Contained in 16S rDNA Clone Libraries

    Microsoft Academic Search

    M. D. Burr; S. J. Clark; C. R. Spear; A. K. Camper

    2006-01-01

    Two different strategies for molecular analysis of bacterial diversity, 16S rDNA cloning and denaturing gradient gel electrophoresis (DGGE), were combined into a single protocol that took advantage of the best attributes of each: the ability of cloning to package DNA sequence information and the ability of DGGE to display a community profile. In this combined protocol, polymerase chain reaction products

  6. Color and population gradients in globular clusters

    NASA Technical Reports Server (NTRS)

    Djorgovski, S.; Piotto, G.; Mallen-Ornelas, G.

    1991-01-01

    We present preliminary results from a survey for color and population gradients in globular cluster cores. Color gradients, in the sense of becoming bluer inwards, are always found in post-core-collapse clusters. They seem to be caused by the demise of red giants, and possibly an increased number of blue stragglers. This may be a consequence of stellar interactions during and after the core collapse. No gradients are seen in clusters with King-model morphology.

  7. Real-time gradient-domain painting

    Microsoft Academic Search

    James McCann; Nancy S. Pollard

    2008-01-01

    We present an image editing program which allows artists to paint in the gradient domain with real-time feedback on megapixel-sized images. Along with a pedestrian, though powerful, gradient-painting brush and gradient-clone tool, we introduce an edge brush designed for edge selection and replay. These brushes, coupled with special blending modes, allow users to accomplish global lighting and contrast adjustments using

  8. Gradient Coil Design Method for Handy MRI

    Microsoft Academic Search

    T. Hirasawa; Y. Ishihara

    \\u000a Our goal is to develop a handy MRI system which enables us to image an inner body distribution near a body surface region\\u000a noninvasively. This system consists of several permanent magnets, small gradient coils, and radio-frequency coils to generate\\u000a a static magnetic field, gradient magnetic field, and RF field distributions, respectively. In order to obtain an appropriate\\u000a image, the gradient

  9. The Jet Stream and Horizontal Temperature Gradients

    NSDL National Science Digital Library

    Dramatic temperature shifts, in which warm, autumn days turn unbearably cold in what seems like minutes, are almost always ushered in by powerful winds. These temperature differences (or temperature gradients) between air masses are what actually causes the wind. This set of interactive graphs, adapted from the University of Wisconsin-Madison, allows users to control the temperature gradient between two air masses and view the effects that changes in the temperature gradient have on wind speed.

  10. Temperature gradient sensor based on CNT composite

    NASA Astrophysics Data System (ADS)

    Karimov, Khasan S.; Abid, ?uhammad; Saleem, Muhammad; Akhmedov, Khakim M.; Bashir, Muhammad M.; Shafique, Umar; Ali, Muhammad M.

    2014-08-01

    This work describes fabrication and investigation of thin film temperature gradient sensor based on the composite of carbon nano-tubes (CNT) and polymer adhesive. The dependences of the voltage, current and Seebeck coefficient of the sensor upon gradient of temperature were measured. It was observed that with increase of temperature gradient, the voltage and current of the sensor increase while the Seebeck coefficient decreases.

  11. Heat conduction in one-dimensional aperiodic quantum Ising chains

    NASA Astrophysics Data System (ADS)

    Li, Wenjuan; Tong, Peiqing

    2011-03-01

    The heat conductivity of nonperiodic quantum Ising chains whose ends are connected with heat baths at different temperatures are studied numerically by solving the Lindblad master equation. The chains are subjected to a uniform transverse field h, while the exchange coupling Jm between the nearest-neighbor spins takes the two values JA and JB arranged in Fibonacci, generalized Fibonacci, Thue-Morse, and period-doubling sequences. We calculate the energy-density profile and energy current of the resulting nonequilibrium steady states to study the heat-conducting behavior of finite but large systems. Although these nonperiodic quantum Ising chains are integrable, it is clearly found that energy gradients exist in all chains and the energy currents appear to scale as the system size ~N?. By increasing the ratio of couplings, the exponent ? can be modulated from ?>-1 to ?<-1 corresponding to the nontrivial transition from the abnormal heat transport to the heat insulator. The influences of the temperature gradient and the magnetic field to heat conduction have also been discussed.

  12. Heat conduction in one-dimensional aperiodic quantum Ising chains.

    PubMed

    Li, Wenjuan; Tong, Peiqing

    2011-03-01

    The heat conductivity of nonperiodic quantum Ising chains whose ends are connected with heat baths at different temperatures are studied numerically by solving the Lindblad master equation. The chains are subjected to a uniform transverse field h, while the exchange coupling J{m} between the nearest-neighbor spins takes the two values J{A} and J{B} arranged in Fibonacci, generalized Fibonacci, Thue-Morse, and period-doubling sequences. We calculate the energy-density profile and energy current of the resulting nonequilibrium steady states to study the heat-conducting behavior of finite but large systems. Although these nonperiodic quantum Ising chains are integrable, it is clearly found that energy gradients exist in all chains and the energy currents appear to scale as the system size ~N{?}. By increasing the ratio of couplings, the exponent ? can be modulated from ? > -1 to ? < -1 corresponding to the nontrivial transition from the abnormal heat transport to the heat insulator. The influences of the temperature gradient and the magnetic field to heat conduction have also been discussed. PMID:21517475

  13. Gradient scaling for nonuniform meshes

    SciTech Connect

    Margolin, L.G.; Ruppel, H.M.; Demuth, R.B.

    1985-01-01

    This paper is concerned with the effect of nonuniform meshes on the accuracy of finite-difference calculations of fluid flow. In particular, when a simple shock propagates through a nonuniform mesh, one may fail to model the jump conditions across the shock even when the equations are differenced in manifestly conservative fashion. We develop an approximate dispersion analysis of the numerical equations and identify the source of the mesh dependency with the form of the artificial viscosity. We then derive an algebraic correction to the numerical equations - a scaling factor for the pressure gradient - to essentially eliminate the mesh dependency. We present several calculations to illustrate our theory. We conclude with an alternate interpretation of our results. 14 refs., 5 figs.

  14. Decision mechanism for chain to chain collaboration in cluster supply chains

    Microsoft Academic Search

    Haibo Zhu

    2012-01-01

    In order to improve the performance of chain to chain horizontal collaboration in cluster supply chains, this paper addresses remain\\/leave (R\\/L) decision mechanism for cluster supply chains when an enterprise or a set of enterprises needs to evaluate the anticipated reward of enterprise collaboration. In this research, a set of enterprises forms a collaborative network (CN) for the purpose of

  15. Zonation: Position on Gradient Barnacles: Dessication

    E-print Network

    Caraco, Thomas

    Zonation: Position on Gradient Barnacles: Dessication Many Organisms: Elevation, Depth h: Position Barnacles: Strong Zonation Little Overlap Coexist? Scale #12;Spatial Mosaic Local Disturbance Colonization

  16. Time changes in gradient and observed winds 

    E-print Network

    Carlson, Ronald Dale

    1972-01-01

    . ANALYTICAL APPROACH. 13 a. The grid system. b. Data interpolation to the grid. . 13 c. Evaluation of the gradient wind and its components. 14 1) Height gradient 2) Trajectory curvature. 14 15 d. Evaluation of time changes. 17 e. Output 17 vii... & / d) 1200 GKC )10 v) 20 0 ~ /// 40 ~ & / / I l / I / I 4d , 4 40 4 e) 500 GNT Fig. 6. Observed and gradient wind speeds at the 500-mb level on 19 February 1964. (Ticked lines outline areas of non-gradient balance. ) 35 / / i 30 20...

  17. Spatial Data Supply Chains

    NASA Astrophysics Data System (ADS)

    Varadharajulu, P.; Azeem Saqiq, M.; Yu, F.; McMeekin, D. A.; West, G.; Arnold, L.; Moncrieff, S.

    2015-06-01

    This paper describes current research into the supply of spatial data to the end user in as close to real time as possible via the World Wide Web. The Spatial Data Infrastructure paradigm has been discussed since the early 1990s. The concept has evolved significantly since then but has almost always examined data from the perspective of the supplier. It has been a supplier driven focus rather than a user driven focus. The current research being conducted is making a paradigm shift and looking at the supply of spatial data as a supply chain, similar to a manufacturing supply chain in which users play a significant part. A comprehensive consultation process took place within Australia and New Zealand incorporating a large number of stakeholders. Three research projects that have arisen from this consultation process are examining Spatial Data Supply Chains within Australia and New Zealand and are discussed within this paper.

  18. The impact of gradient strength on in vivo diffusion MRI estimates of axon diameter.

    PubMed

    Huang, Susie Y; Nummenmaa, Aapo; Witzel, Thomas; Duval, Tanguy; Cohen-Adad, Julien; Wald, Lawrence L; McNab, Jennifer A

    2015-02-01

    Diffusion magnetic resonance imaging (MRI) methods for axon diameter mapping benefit from higher maximum gradient strengths than are currently available on commercial human scanners. Using a dedicated high-gradient 3T human MRI scanner with a maximum gradient strength of 300 mT/m, we systematically studied the effect of gradient strength on in vivo axon diameter and density estimates in the human corpus callosum. Pulsed gradient spin echo experiments were performed in a single scan session lasting approximately 2h on each of three human subjects. The data were then divided into subsets with maximum gradient strengths of 77, 145, 212, and 293 mT/m and diffusion times encompassing short (16 and 25 ms) and long (60 and 94 ms) diffusion time regimes. A three-compartment model of intra-axonal diffusion, extra-axonal diffusion, and free diffusion in cerebrospinal fluid was fitted to the data using a Markov chain Monte Carlo approach. For the acquisition parameters, model, and fitting routine used in our study, it was found that higher maximum gradient strengths decreased the mean axon diameter estimates by two to three fold and decreased the uncertainty in axon diameter estimates by more than half across the corpus callosum. The exclusive use of longer diffusion times resulted in axon diameter estimates that were up to two times larger than those obtained with shorter diffusion times. Axon diameter and density maps appeared less noisy and showed improved contrast between different regions of the corpus callosum with higher maximum gradient strength. Known differences in axon diameter and density between the genu, body, and splenium of the corpus callosum were preserved and became more reproducible at higher maximum gradient strengths. Our results suggest that an optimal q-space sampling scheme for estimating in vivo axon diameters should incorporate the highest possible gradient strength. The improvement in axon diameter and density estimates that we demonstrate from increasing maximum gradient strength will inform protocol development and encourage the adoption of higher maximum gradient strengths for use in commercial human scanners. PMID:25498429

  19. Quantum estimation of magnetic-field gradient using W-state

    NASA Astrophysics Data System (ADS)

    Ng, H. T.; Kim, K.

    2014-11-01

    We study the precision limits of detecting a linear magnetic-field gradient by using W-states in the presence of different types of noises. We consider to use an atomic spin chain for probing the magnetic-field gradient, where a W-state is prepared. We compare this method with the measurement of using two uncorrelated atoms. For pure states, W-states can provide an improvement over uncorrelated states in determining the magnetic-field gradient up to four particles. We examine the effects of local dephasing and dissipations on the performances of detections. In the presence of dephasing, the uncorrelated atoms can give a higher precision than using W-states. But W-states provide a better performance in the presence of dissipation for a few particles. We briefly discuss the implementation of the detection methods with cold atoms and trapped ions.

  20. Infiltration of chitin by protein coacervates defines the squid beak mechanical gradient.

    PubMed

    Tan, YerPeng; Hoon, Shawn; Guerette, Paul A; Wei, Wei; Ghadban, Ali; Hao, Cai; Miserez, Ali; Waite, J Herbert

    2015-07-01

    The beak of the jumbo squid Dosidicus gigas is a fascinating example of how seamlessly nature builds with mechanically mismatched materials. A 200-fold stiffness gradient begins in the hydrated chitin of the soft beak base and gradually increases to maximum stiffness in the dehydrated distal rostrum. Here, we combined RNA-Seq and proteomics to show that the beak contains two protein families. One family consists of chitin-binding proteins (DgCBPs) that physically join chitin chains, whereas the other family comprises highly modular histidine-rich proteins (DgHBPs). We propose that DgHBPs play multiple key roles during beak bioprocessing, first by forming concentrated coacervate solutions that diffuse into the DgCBP-chitin scaffold, and second by inducing crosslinking via an abundant GHG sequence motif. These processes generate spatially controlled desolvation, resulting in the impressive biomechanical gradient. Our findings provide novel molecular-scale strategies for designing functional gradient materials. PMID:26053298

  1. Solitons in Granular Chains

    SciTech Connect

    Manciu, M.; Sen, S.; Hurd, A.J.

    1999-04-12

    The authors consider a chain of elastic (Hertzian) grains that repel upon contact according to the potential V = a{delta}{sup u}, u > 2, where {delta} is the overlap between the grains. They present numerical and analytical results to show that an impulse initiated at an end of a chain of Hertzian grains in contact eventually propagates as a soliton for all n > 2 and that no solitons are possible for n {le} 2. Unlike continuous, they find that colliding solitons in discrete media initiative multiple weak solitons at the point of crossing.

  2. Volcanoes, Plates, and Chains

    NSDL National Science Digital Library

    In this lesson students will discover how seamounts in the Axial-Cobb-Eikelberg-Patton chain were formed. They will learn about the processes that form seamounts, describe the movement of tectonic plates in the Gulf of Alaska region and explain the types of volcanic activity that might be associated with these movements, and describe how a combination of hotspot activity and tectonic plate movement could produce the arrangement of seamounts observed in this chain. This hands-on activity uses online data resources and includes: focus questions, learning objectives, teaching time, audio/visual materials needed, background information, learning procedures, evaluations, extensions, as well as resources and student handouts.

  3. Factor-multiple Chains

    NSDL National Science Digital Library

    This problem offers opportunities for students to reinforce their understanding of factors and multiples and provides them the chance to justify their solutions. The goal is for the students to create number chains of four whole numbers that can range from 2 to 100 and each consecutive number is a multiple of the previous number. The Teachers' Notes page offers suggestions for implementation, key discussion questions, ideas for extension and support, and a link to a spreadsheet for students to experiment with placing numbers in specific boxes in the chain.

  4. Journal of Machine Learning Research 7 (2006) 413427 Submitted 5/05; Revised 1/06; Published 2/06 Geometric Variance Reduction in Markov Chains

    E-print Network

    Paris-Sud XI, Université de

    2006-01-01

    /06 Geometric Variance Reduction in Markov Chains: Application to Value Function and Gradient Estimation Rémi, France Editor: Shie Mannor Abstract We study a variance reduction technique for Monte Carlo estimation Decision Processes. Another important domain, for which variance reduction is highly needed, is gradient

  5. The adiabatic gradient and the melting point gradient in the core of the earth

    Microsoft Academic Search

    G. Higgins; G. C. Kennedy

    1971-01-01

    The melting gradient and the adiabatic gradient throughout the core of the earth are compared. The temperature of melting of iron at pressures equivalent to the inner core-outer core boundary is estimated to be circa 4250øC with a melting point gradient of approximately 500 ø through the outer core. The adiabatic gradient through the outer core is estimated to be

  6. Skeletal Muscle VEGF Gradients in PAD Skeletal Muscle VEGF Gradients in Peripheral Arterial Disease: Simulations

    E-print Network

    Popel, Aleksander S.

    Skeletal Muscle VEGF Gradients in PAD 1 Skeletal Muscle VEGF Gradients in Peripheral Arterial.2007 Copyright © 2007 by the American Physiological Society. #12;Skeletal Muscle VEGF Gradients in PAD 2 ABSTRACT Vascular endothelial growth factor (VEGF) is a key promoter of angiogenesis and a major target of pro

  7. Simplified Chain Inflation

    E-print Network

    Qing-Guo Huang

    2007-04-25

    We propose a simplified chain inflation model and calculate the primordial power spectra of the scalar and tensor fluctuations. The spectral index and the tensor-scalar ratio are respectively 0.972 and 0.089 which are consistent with present cosmological observations.

  8. Open source supply chains

    Microsoft Academic Search

    Andreas L. Symeonidis; Dionisis Kehagias; Adamantios Koumpis; Apostolos Vontas

    2003-01-01

    Enterprise Resource Planning (ERP) systems tend to deploy Supply Chains, in order to successfully integrate customers, suppliers, manufacturers and warehouses, and therefore minimize system-wide costs, while satisfying service level requirements. Although efficient, these systems are neither versatile nor adaptive, since newly discovered customer trends cannot be easily integrated. Furthermore, the development of such systems is subject to strict licensing, since

  9. Polymerase chain reaction system

    DOEpatents

    Benett, William J.; Richards, James B.; Stratton, Paul L.; Hadley, Dean R.; Milanovich, Fred P.; Belgrader, Phil; Meyer, Peter L.

    2004-03-02

    A portable polymerase chain reaction DNA amplification and detection system includes one or more chamber modules. Each module supports a duplex assay of a biological sample. Each module has two parallel interrogation ports with a linear optical system. The system is capable of being handheld.

  10. Supply chain management.

    PubMed

    Palevich, R F

    1999-02-01

    This article describes how Do It Best Corp. has used technology to improve its supply chain management. Among other topics it discusses the company's use of electronic data interchange, the Internet, electronic forecasting, and warehouse management systems to gain substantial savings and increase its competitiveness. PMID:10345634

  11. Supply chain quality.

    PubMed

    Feary, Simon

    2009-01-01

    As the development of complex manufacturing models and virtual companies become more prevalent in today's growing global markets, it is increasingly important to support the relationships between manufacturer and supplier. Utilising these relationships will ensure that supply chains operate more effectively and reduce costs, risks and time-to-market time frames, whilst maintaining product quality. PMID:20058652

  12. Breaking the Chains

    ERIC Educational Resources Information Center

    Stanistreet, Paul

    2007-01-01

    In 1792 more than 350,000 people in Britain signed a petition calling for an end to the slave trade. It was, writes historian Adam Hochschild in his book "Bury the Chains," "the first time in history that a large number of people became outraged, and stayed outraged for many years, over someone else's rights". In 1807--after 15 years of…

  13. Heavy Chain Diseases

    MedlinePLUS

    ... cells often prevents proper absorption of nutrients from food (malabsorption), resulting in severe diarrhea and weight loss. A rare form that affects the respiratory tract also exists. Blood tests are done when alpha heavy chain disease is suspected. Serum protein electrophoresis, measurement of ...

  14. Atwood's Heavy Chain

    ERIC Educational Resources Information Center

    Beeken, Paul

    2011-01-01

    While perusing various websites in search of a more challenging lab for my students, I came across a number of ideas where replacing the string in an Atwood's machine with a simple ball chain like the kind found in lamp pulls created an interesting system to investigate. The replacement of the string produced a nice nonuniform acceleration, but…

  15. Electrostatic instabilities driven by velocity gradients

    Microsoft Academic Search

    A. Hirose; I. Alexeff

    1973-01-01

    It is shown that cross-field gradients of guiding-center drift velocities can excite several high-frequency (? > ?ci ) electrostatic instabilities. The instabilities can enhance effective interelectron and\\/or electron-ion collisions which in turn destory the velocity gradients. In pulsed, turbulent heating experiments, this effect is expected to appear as anomalously rapid current penetration (anomalous skin effect).

  16. Strain gradient plasticity: Theory and experiment

    Microsoft Academic Search

    N. A. FLECK; G. M. MULLER; M. F. ASHBY; J. W. HUTCHINSON

    1994-01-01

    Dislocation theory is used to invoke a strain gradient theory of rate independent plasticity. Hardening is assumed to result from the accumulation of both randomly stored and geometrically necessary dislocations. The density of the geometrically necessary dislocations scales with the gradient of plastic strain. A deformation theory of plasticity is introduced to represent in a phenomenological manner the relative roles

  17. An Inexpensive Digital Gradient Controller for HPLC.

    ERIC Educational Resources Information Center

    Brady, James E.; Carr, Peter W.

    1983-01-01

    Use of gradient elution techniques in high performance liquid chromatography (HPLC) is often essential for direct separation of complex mixtures. Since most commercial controllers have features that are of marginal value for instructional purposes, a low-cost controller capable of illustrating essential features of gradient elution was developed.…

  18. Gradient lenses for compact optical data processors

    Microsoft Academic Search

    Iu. V. Gurov; V. G. Ilin; G. O. Karapetian; A. E. Kanaev; A. N. Kosharnovskii

    1985-01-01

    It is shown that gradient lenses can be used in small holographic storage devices to collimate beams from semiconductor lasers. The beam divergence angle after passage through the lens is measured, and the collimation efficiency is studied as a function of the distance from the lens to the center of the active region of the laser. When a gradient lens

  19. Systematic modeling of microfluidic concentration gradient generators

    Microsoft Academic Search

    Yi Wang; Tamal Mukherjee; Qiao Lin

    2006-01-01

    This paper presents a systematic modeling methodology for microfluidic concentration gradient generators. The generator is decomposed into a system of microfluidic elements with relatively simple geometries. Parameterized models for such elements are analytically developed and hold for general sample concentration profiles and arbitrary flow ratios at the element inlet; hence, they are valid for concentration gradient generators that rely on

  20. Shaping a Morphogen Gradient for Positional Precision

    Microsoft Academic Search

    Feng He; Timothy E. Saunders; Ying Wen; David Cheung; Renjie Jiao; Pieter Rein ten Wolde; Martin Howard; Jun Ma

    2010-01-01

    Morphogen gradients, which provide positional information to cells in a developing tissue, could in principle adopt any nonuniform profile. To our knowledge, how the profile of a morphogen gradient affects positional precision has not been well studied experimentally. Here, we compare the positional precision provided by the Drosophila morphogenetic protein Bicoid (Bcd) in wild-type (wt) embryos with embryos lacking an

  1. Magic-Angle Gradient-Coil Design

    Microsoft Academic Search

    R. Bowtell; A. Peters

    1995-01-01

    The target-field approach to gradient-coil design has been applied to the production of coils which will produce a linear gradient in the z component of the magnetic field, in a direction oriented at the magic angle to the z axis. The resulting coils, which consist of wires wound on the surface of a cylinder whose axis is parallel to the

  2. Gradient Coil Design in Permanent Magnet MRI

    Microsoft Academic Search

    Guo-jun HU; Yu-hua PENG; Wei ZHAO; Xiao-ying TANG

    2006-01-01

    Based on target field method, the article designs gradient coils for a permanent MRI magnet model. By simulating, winding and testing, the result verifies the validity and feasibility of target field method used in gradient coils design of permanent magnet MRI; moreover, shielded coils can restrain eddy current and can be designed based on target field method easily. The simulated

  3. Histograms of Oriented Gradients for Human Detection

    E-print Network

    vote orientation cellscolour Normalize gamma & Input image over detection window Collect HOG's SVM of Oriented Gradients for Human Detection ­ p. 5/1 #12;HOG Descriptors Parameters Schemes Gradient scale/ v 2 2 + 2 or L1-norm, v v/( v 1 + ) R-HOG/SIFT C-HOG Block Cell Block Center Bin Radial Bins

  4. Gradient Vector Flow Fast Geometric Active Contours

    E-print Network

    Paragios, Nikos

    Gradient Vector Flow Fast Geometric Active Contours Nikos Paragios, Olivier Mellina-Gottardo, and Visvanathan Ramesh Abstract--In this paper, we propose an edge-driven bidirectional geometric flow for boundary extraction. To this end, we combine the geodesic active contour flow [3] and the gradient vector

  5. Calculation of exit gradients at drainage ditches

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seepage gradients play an important role in the detachment of soil particles from the side walls of stream channels and drainage ditches. Most seepage studies have focused on water losses. Relatively few have addressed the determination of these gradients as causes of soil loss and incipient gully d...

  6. Microbatch macromolecular crystallization on a thermal gradient

    Microsoft Academic Search

    Joseph R. Luft; Dawn M. Rak; George T. DeTitta

    1999-01-01

    We can exploit the temperature dependence of protein solubility in a blind search for optimal crystallization conditions by conducting experiments on thermal gradients. A microbatch technique coupled with a specially constructed thermal gradient allows us to conduct polythermal experiments over the range 6–30°C using as little as 7?l of solution. The crystallization vessel is a micropipette commonly used in blood

  7. Microinstabilities in weak density gradient tokamak systems

    SciTech Connect

    Tang, W.M.; Rewoldt, G.; Chen, L.

    1986-04-01

    A prominent characteristic of auxiliary-heated tokamak discharges which exhibit improved (''H-mode type'') confinement properties is that their density profiles tend to be much flatter over most of the plasma radius. Depsite this favorable trend, it is emphasized here that, even in the limit of zero density gradient, low-frequency microinstabilities can persist due to the nonzero temperature gradient.

  8. Approximate error conjugation gradient minimization methods

    DOEpatents

    Kallman, Jeffrey S

    2013-05-21

    In one embodiment, a method includes selecting a subset of rays from a set of all rays to use in an error calculation for a constrained conjugate gradient minimization problem, calculating an approximate error using the subset of rays, and calculating a minimum in a conjugate gradient direction based on the approximate error. In another embodiment, a system includes a processor for executing logic, logic for selecting a subset of rays from a set of all rays to use in an error calculation for a constrained conjugate gradient minimization problem, logic for calculating an approximate error using the subset of rays, and logic for calculating a minimum in a conjugate gradient direction based on the approximate error. In other embodiments, computer program products, methods, and systems are described capable of using approximate error in constrained conjugate gradient minimization problems.

  9. Stellar Metallicity Gradients in SDSS galaxies

    E-print Network

    Roig, Benjamin; Yan, Renbin

    2015-01-01

    We infer stellar metallicity and abundance ratio gradients for a sample of red galaxies in the Sloan Digital Sky Survey (SDSS) Main galaxy sample. Because this sample does not have multiple spectra at various radii in a single galaxy, we measure these gradients statistically. We separate galaxies into stellar mass bins, stack their spectra in redshift bins, and calculate the measured absorption line indices in projected annuli by differencing spectra in neighboring redshift bins. After determining the line indices, we use stellar population modeling from the EZ\\_Ages software to calculate ages, metallicities, and abundance ratios within each annulus. Our data covers the central regions of these galaxies, out to slightly higher than $1 R_{e}$. We find detectable gradients in metallicity and relatively shallow gradients in abundance ratios, similar to results found for direct measurements of individual galaxies. The gradients are only weakly dependent on stellar mass, and this dependence is well-correlated with...

  10. Microbial diversity of benthic mats along a tidal desiccation gradient.

    PubMed

    Rothrock, Michael J; Garcia-Pichel, Ferran

    2005-04-01

    We investigated the influence of desiccation frequency, indicated by tidal position, on microbial community structure, diversity and richness of microbial mats. We independently characterized cyanobacterial, bacterial and archaeal communities, and their spatial variability for two distinct microbial mat systems: subtidal hypersaline mats and intertidal sand flat mats. Community fingerprints based on 16S rDNA were obtained via denaturing gradient gel electrophoresis using polymerase chain reaction primers specific for each group. Fingerprints for all three groups were consistently similar [> or =85% according to Weighted Pair Group with Arithmetic Mean (WPGMA) analysis] along a 1-km-long transect in subtidal mats. Here, pair-wise comparison analysis yielded minimal variation in diversity and richness for all groups. Fingerprints of three sites along an intertidal transect were heterogenous (> or =32% similarity according to WPGMA analysis) with clear shifts in community structure in all three microbial groups. Here, all groups exhibited statistically significant decreases in richness and diversity with tidal height (as desiccation frequency increases). Regression analysis yielded a strong correlation between diversity or richness estimates and position along the tidal gradient, for both Archaea and Bacteria, with Cyanobacteria exhibiting a weaker correlation. These results suggest that desiccation frequency can shape the structure of microbial mat communities, with Archea being least tolerant and Cyanobacteria most tolerant. PMID:15816936

  11. Decentralized Supply Chain Planning for Two Classified Supply Chains

    Microsoft Academic Search

    Hosang Jung; F. Frank Chen

    In this chapter, we introduce two types of supply chains that consist of an independent manufacturer and an independent distributor\\u000a and decentralized supply chain planning models for them. Those supply chains are based on a decentralized planning environment\\u000a where the manufacturer and the distributor collaborate with each other without disclosing their private information. Although\\u000a collaboration with other supply chain participants

  12. Induced population gradients in galaxy merger remnants

    NASA Technical Reports Server (NTRS)

    Mihos, J. Christopher; Hernquist, Lars

    1994-01-01

    We use numerical models to investigate the nature of induced population gradients in merger remnants. As noted by White, we find that the population mixing in stellar-dynamical mergers is rather moderate, leading to metallicity gradients in the remnant that are closely tied to gradients in the progenitor galaxies. Furthermore, the resultant metallicity gradients are poorly fitted by power laws, showing significant nonlinearities within an effective radius. If constant metallicity bulges are added to the progenitor disks, the strong relation between final and initial metallicity gradients is diluted, but the final gradients are still not well fitted by power laws. Detailed studies of the shape of the metallicity gradients in elliptical galaxies should help determine the degree to which stellar-dynamical mergers have contributed to the population of present-day ellipticals. We also consider the effects of centrally concentrated starbursts on metallicity gradients. Using simple models for metallicity enhancement, we find that addition of a metal-rich starburst population can reproduce the magnitude and shape of metallicity gradients observed in elliptical galaxies. However, even in such cases the metallicity gradients in the merger remnant should steepen significantly beyond an effective radius. Modelling such merger-induced starbursts with population synthesis techniques, we find that if the starburst is characterized by solar metallicity, it should be detectable as a bluing of the nuclear regions for several Gyr. However, if the starburst is metal-rich, the reddening effects of higher metallicity makes the broad-band signature of the starburst much more difficult to detect.

  13. Supply Chain Networks: Challenges and Opportunities

    E-print Network

    Nagurney, Anna

    #12;A General Supply Chain Anna Nagurney Supply Chain Networks #12;Examples of Supply Chains food humanitarian relief healthcare supply chains. Anna Nagurney Supply Chain Networks #12;Food Supply Chains AnnaSupply Chain Networks: Challenges and Opportunities from Analysis to Design Anna Nagurney Isenberg

  14. Supply Chain Networks: Challenges and Opportunities

    E-print Network

    Nagurney, Anna

    Chain Networks #12;Examples of Supply Chains food and food products high tech products automotive energy chains in nature. Anna Nagurney Supply Chain Networks #12;Food Supply Chains Anna Nagurney Supply ChainSupply Chain Networks: Challenges and Opportunities from Analysis to Design Anna Nagurney Isenberg

  15. Comparing grids of observed GOCE gravitational gradients with modeled GOCE gravitational gradients

    NASA Astrophysics Data System (ADS)

    Šprlák, Michal; Novák, Pavel; Va?ko, Milos; Sebera, Josef

    2013-04-01

    The satellite gravitational gradiometry mission GOCE provides, among other data products, gravitational gradients that are used for estimation of global gravity field models. For several geo-scientific applications, however, gravitational gradients in a form of regular grids are much more convenient. These may be computed either by interpolating observed gravitational gradients or by spherical harmonic synthesis of geopotential coefficients within global gravity field models. In this study, differences between values of observed gravitational gradients interpolated to regular grids and gravitational gradients synthesized from the latest geopotential coefficients are analyzed. Different signal contents may be involved in regular grids of gravitational gradients evaluated by the two approaches. This is because part of a valuable signal may be lost either in the interpolation procedure or in spherical harmonic analysis of observed gravitational gradients. The analysis of the differences is performed over several geographic areas and at different altitudes above the Earth's surface.

  16. Cross-contact chain

    NASA Technical Reports Server (NTRS)

    Lieneweg, Udo (Inventor)

    1988-01-01

    A system is provided for use with wafers that include multiple integrated circuits that include two conductive layers in contact at multiple interfaces. Contact chains are formed beside the integrated circuits, each contact chain formed of the same two layers as the circuits, in the form of conductive segments alternating between the upper and lower layers and with the ends of the segments connected in series through interfaces. A current source passes a current through the series-connected segments, by way of a pair of current tabs connected to opposite ends of the series of segments. While the current flows, voltage measurements are taken between each of a plurality of pairs of voltage tabs, the two tabs of each pair connected to opposite ends of an interface that lies along the series-connected segments. A plot of interface conductances on a normal probability chart, enables prediction of the yield of good integrated circuits from the wafer.

  17. Cross-contact chain

    NASA Technical Reports Server (NTRS)

    Lieneweg, U. (inventor)

    1986-01-01

    A system is provided for use with wafers that include multiple integrated circuits that include two conductive layers in contact at multiple interfaces. Contact chains are formed beside the integrated circuits, each contact chain formed of the same two layers as the circuits, in the form of conductive segments alternating between the upper and lower layers and with the ends of the segments connected in series through interfaces. A current source passes a current through the series-connected segments, by way of a pair of current tabs connected to opposite ends of the series of segments. While the current flows, voltage measurements are taken between each of a plurality of pairs of voltage tabs, the two tabs of each pair connected to opposite ends of an interface that lies along the series-connected segments. A plot of interface conductances on normal probability chart enables prediction of the yield of good integrated circuits from the wafer.

  18. Design for supply chain collaboration

    Microsoft Academic Search

    Togar M. Simatupang; Ramaswami Sridharan

    2008-01-01

    Purpose – The purpose of this paper is to clarify the architecture of supply chain collaboration and to propose a design for supply chain collaboration (DfC), which enables participating members to create and develop key elements of the proposed architecture. Design\\/methodology\\/approach – The paper offers a concept for designing the five elements of the architecture of supply chain collaboration, namely

  19. Supply chain collaboration: what's happening?

    Microsoft Academic Search

    Soonhong Min; Anthony S. Roath; Patricia J. Daugherty; Stefan E. Genchev; Haozhe Chen; Aaron D. Arndt; R. Glenn Richey

    2005-01-01

    Purpose – Collaboration has been referred to as the driving force behind effective supply chain management and may be the ultimate core capability. However, there is a fairly widespread belief that few firms have truly capitalized on its potential. A study was undertaken to assess the current level of supply chain collaboration and identify best practice. Design\\/methodology\\/approach – Supply chain

  20. TQM is suppy chain management

    Microsoft Academic Search

    Angappa Gunasekaran; Ronald E. McGaughey

    2003-01-01

    Outlines the principles of total quality management (TQM) and theorizes whether they apply in supply chain management (SCM). Associates SCM with materials management, but observes that SCM, in assocation with other initiatives such as enterprise resource planning and electronic commerce, has been driving towards fully integrated supply chain management across organizational value chains, with cross-boundary focus on transaction cost reduction.

  1. Virtual supply-chain management

    Microsoft Academic Search

    A. Gunasekaran; E. W. T. Ngai

    2004-01-01

    In global business competition, companies believe greater transparency in supply-chain operations and collaboration is very important for success. Transparency brings accountability and responsibility. This openness in the supply-chain allows companies to see how their suppliers are performing, from their sourcing of raw materials to their delivery to the retail outlet. Achieving greater transparency in the supply chain requires the development

  2. Advances in Supply Chain Simulation

    Microsoft Academic Search

    Agostino G. Bruzzone; Yuri Merkuryev

    2009-01-01

    The lecture aims to provide an insight into modern approaches to simulation-based analysis of supply chains. It gives an overview of using modeling and simulation (M&S) for facing different types of activities in supply chain management. In particular, different issues are considered, starting with new criticality such as: green logistics; supply chain resilience; sustainable logistics; logistics security; logistics safety; logistics

  3. Supply Chain Dynamics in Asia

    Microsoft Academic Search

    Ruth Banomyong

    2010-01-01

    Supply chain management in Asia is a relatively new topic but is a key challenge for all Asia based manufacturers and traders trying to integrate into the global market. The purpose of this paper is to describe key supply chain issues faced in Asia. Many of these issues are related to the importance of a properly managed supply chain in

  4. The Tourism Global Value Chain

    E-print Network

    Richardson, David

    The Tourism Global Value Chain ECONOMIC UPGRADING AND WORKFORCE DEVELOPMENT Michelle Christian 2011 CENTER on GLOBALIZATION, GOVERNANCE & COMPETITIVENESS #12;The Tourism Global Value Chain: Economic: November 17, 2011 #12;The Tourism Global Value Chain: Economic Upgrading and Workforce Development i Table

  5. Brain Pop Movies - Food Chains

    NSDL National Science Digital Library

    This representation depicts a food chain and a food web and illustrates both with specific examples of organisms in an animated cartoon video. The video illustrates the food chain in a pyramid structure with plants at the bottom and explains the role of each layer in the food chain.

  6. Granular chain between asymmetric boundaries and the quasiequilibrium state

    NASA Astrophysics Data System (ADS)

    Ávalos, Edgar; Sen, Surajit

    2014-05-01

    Some 30 years have passed since we learned that any velocity perturbation develops into a propagating solitary wave in a granular chain, and over a decade has passed since we learned that these solitary waves break and reform upon collision, leaving behind small secondary solitary waves. The production of the latter eventually precipitates the quasiequilibrium state characterized by large energy fluctuations in dissipation-free granular systems. Here we present dynamical simulations on the effects of soft boundaries on solitary wave interaction in granular chains held between fixed walls. We show that at short time scales, a gradient in the distribution of kinetic energy between the boundaries is indeed sustained. At long times, however, such a gradient gets obliterated and there is no measurable difference between the average kinetic energies of the particles adjacent to walls. Our findings suggest that (i) the quasiequilibrium state can effectively erase small gradients of the average kinetic energies of the particles adjacent to walls in a system, (ii) Boltzmann distribution of grain speeds is realized in the system of interest, and (iii) time and space averages yield the same result, thus suggesting that the system is ergodic.

  7. Extraordinary strain hardening by gradient structure

    PubMed Central

    Wu, XiaoLei; Jiang, Ping; Chen, Liu; Yuan, Fuping; Zhu, Yuntian T.

    2014-01-01

    Gradient structures have evolved over millions of years through natural selection and optimization in many biological systems such as bones and plant stems, where the structures change gradually from the surface to interior. The advantage of gradient structures is their maximization of physical and mechanical performance while minimizing material cost. Here we report that the gradient structure in engineering materials such as metals renders a unique extra strain hardening, which leads to high ductility. The grain-size gradient under uniaxial tension induces a macroscopic strain gradient and converts the applied uniaxial stress to multiaxial stresses due to the evolution of incompatible deformation along the gradient depth. Thereby the accumulation and interaction of dislocations are promoted, resulting in an extra strain hardening and an obvious strain hardening rate up-turn. Such extraordinary strain hardening, which is inherent to gradient structures and does not exist in homogeneous materials, provides a hitherto unknown strategy to develop strong and ductile materials by architecting heterogeneous nanostructures. PMID:24799688

  8. Regulation of the photosynthetic electron transport chain.

    PubMed

    Ott; Clarke; Birks; Johnson

    1999-08-12

    The regulation of electron transport between photosystems II and I was investigated in the plant Silene dioica L. by means of measurement of the kinetics of reduction of P(700) following a light-to-dark transition. It was found that, in this species, the rate constant for P(700) reduction is sensitive to light intensity and to the availability of CO(2). The results indicated that at 25 degrees C the rate of electron transport is down-regulated by approximately 40-50% relative to the maximum rate achievable in saturating CO(2) and that this down-regulation can be explained by regulation of the electron transport chain itself. Measurements of the temperature sensitivity of this rate constant indicated that there is a switch in the rate-limiting step that controls electron transport at around 20 degrees C: at higher temperatures, CO(2) availability is limiting; at lower temperatures some other process regulates electron transport, possibly a diffusion step within the electron transport chain itself. Regulation of electron transport also occurred in response to drought stress and sucrose feeding. Measurements of non-photochemical quenching of chlorophyll fluorescence did not support the idea that electron transport is regulated by the pH gradient across the thylakoid membrane, and the possibility is discussed that the redox potential of a stromal component may regulate electron transport.Keywords: DeltapH. Electron transport. Photosynthesis. Photosynthetic control. Redox regulation. Silene (photosynthesis) PMID:10436228

  9. Swarm SCARF Dedicated Lithospheric Field Inversion chain

    NASA Astrophysics Data System (ADS)

    Thébault, E.; Vigneron, P.; Maus, S.; Chulliat, A.; Sirol, O.; Hulot, G.

    2013-11-01

    The forthcoming Swarm satellite mission is a constellation of three satellites dedicated to the study of the geomagnetic field. The orbital characteristics of the mission, which includes a pair of satellites flying side by side, has prompted new efforts in data processing and modeling. A consortium of several research institutions has been selected by the European Space Agency (ESA) to provide a number of Level-2 data products which will be made available to the scientific community. Within this framework, specific tools have been tailor-made to better recover the lithospheric magnetic field contribution. These tools take advantage of gradient properties measured by the lower pair of Swarm satellites and rely on a regional modeling scheme designed to better detect signatures of small spatial scales. We report on a processing chain specifically designed for the Swarm mission. Using an End-to-End simulation, we show that the tools developed are operational. The chain generates a model that meets the primary scientific objectives of the Swarm mission. We also discuss refinements that could also be implemented during the Swarm operational phase to further improve lithospheric field models and reach unprecedented spatial resolution.

  10. Callisto Crater Chain Mosaic

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This mosaic of three images shows an area within the Valhalla region on Jupiter's moon, Callisto. North is to the top of the mosaic and the Sun illuminates the surface from the left. The smallest details that can be discerned in this picture are knobs and small impact craters about 160 meters (175 yards) across. The mosaic covers an area approximately 45 kilometers (28 miles) across. It shows part of a prominent crater chain located on the northern part of the Valhalla ring structure.

    Crater chains can form from the impact of material ejected from large impacts (forming secondary chains) or by the impact of a fragmented projectile, perhaps similar to the Shoemaker-Levy 9 cometary impacts into Jupiter in July 1994. It is believed this crater chain was formed by the impact of a fragmented projectile. The images which form this mosaic were obtained by the solid state imaging system aboard NASA's Galileo spacecraft on Nov. 4, 1996 (Universal Time).

    Launched in October 1989, Galileo entered orbit around Jupiter on December 7, 1995. The spacecraft's mission is to conduct detailed studies of the giant planet, its largest moons and the Jovian magnetic environment. The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

    This image and other images and data received from Galileo are posted on the World Wide Web Galileo mission home page at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http:// www.jpl.nasa.gov/galileo/sepo.

  11. Streamlining the supply chain.

    PubMed

    Neumann, Lydon

    2003-07-01

    Effective management of the supply chain requires attention to: Product management--formulary development and maintenance, compliance, clinical involvement, standardization, and demand-matching. Sourcing and contracting--vendor consolidation, GPO portfolio management, price leveling, content management, and direct contracting Purchasing and payment-cycle--automatic placement, web enablement, centralization, evaluated receipts settlement, and invoice matching Inventory and distribution management--"unofficial" and "official" locations, vendor-managed inventory, automatic replenishment, and freight management. PMID:12866156

  12. The Antarctic Food Chain

    NSDL National Science Digital Library

    This lesson plan introduces students to the animals of Antarctica and to the Antarctic food chain. Students will draw pictures of a variety of animals and attach the pictures to a wall collage. They will then listen to or read statements about the diet of each animal and draw arrows to show which animals eat which other animals. Students will end up with a food web that illustrates the importance of krill to the Antarctic ecosystem.

  13. Translocation of a Polymer Chain across a Nanopore: A Brownian Dynamics Simulation Study

    NASA Technical Reports Server (NTRS)

    Tian, Pu; Smith, Grant D.

    2003-01-01

    We carried out Brownian dynamics simulation studies of the translocation of single polymer chains across a nanosized pore under the driving of an applied field (chemical potential gradient). The translocation process can be either dominated by the entropic barrier resulted from restricted motion of flexible polymer chains or by applied forces (or chemical gradient across the wall), we focused on the latter case in our studies. Calculation of radius of gyrations at the two opposite sides of the wall shows that the polymer chains are not in equilibrium during the translocation process. Despite this fact, our results show that the one-dimensional diffusion and the nucleation model provide an excellent description of the dependence of average translocation time on the chemical potential gradients, the polymer chain length and the solvent viscosity. In good agreement with experimental results and theoretical predictions, the translocation time distribution of our simple model shows strong non-Gaussian characteristics. It is observed that even for this simple tubelike pore geometry, more than one peak of translocation time distribution can be generated for proper pore diameter and applied field strengths. Both repulsive Weeks-Chandler-Anderson and attractive Lennard-Jones polymer-nanopore interaction were studied, attraction facilitates the translocation process by shortening the total translocation time and dramatically improve the capturing of polymer chain. The width of the translocation time distribution was found to decrease with increasing temperature, increasing field strength, and decreasing pore diameter.

  14. Extracellular pH Regulation in Microdomains of Colonic Crypts: Effects of Short-Chain Fatty Acids

    Microsoft Academic Search

    Shaoyou Chu; Marshall H. Montrose

    1995-01-01

    It has been suggested that transepithelial gradients of short-chain fatty acids (SCFAs; the major anions in the colonic lumen) generate pH gradients across the colonic epithelium. Quantitative confocal microscopy was used to study extracellular pH in mouse distal colon with intact epithelial architecture, by superfusing tissue with carboxy SNARF-1 (a pH-sensitive fluorescent dye). Results demonstrate extracellular pH regulation in two

  15. A fast distributed proximal-gradient method

    E-print Network

    Chen, Annie I.

    We present a distributed proximal-gradient method for optimizing the average of convex functions, each of which is the private local objective of an agent in a network with time-varying topology. The local objectives have ...

  16. The generalized regression model for utilization gradients 

    E-print Network

    Derry, Julian F

    2006-07-21

    This document contains a table which is a reworking of Table 1.3 in Derry (2004). The table has been corrected and extended to include further examples of applying the generalized piosphere model to utilization gradients ...

  17. Gradients for SL(q)-foliations

    NASA Astrophysics Data System (ADS)

    Bartoszek, Adam; Kalina, Jerzy; Pierzchalski, Antoni

    2011-12-01

    Gradients, i.e., irreducible (with respect to the orthogonal group) components of the covariant derivative on a foliation, are considered under the assumption that the foliation has holonomy invariant transversal volume form.

  18. Continuous spray forming of functionally gradient materials

    SciTech Connect

    McKechnie, T.N.; Richardson, E.H.

    1995-12-01

    Researchers at Plasma Processes Inc. have produced a Functional Gradient Material (FGM) through advanced vacuum plasma spray processing for high heat flux applications. Outlined in this paper are the manufacturing methods used to develop a four component functional gradient material of copper, tungsten, boron, and boron nitride. The FGM was formed with continuous gradients and integral cooling channels eliminating bondlines and providing direct heat transfer from the high temperature exposed surface to a cooling medium. Metallurgical and x-ray diffraction analyses of the materials formed through innovative VPS (vacuum plasma spray) processing are also presented. Applications for this functional gradient structural material range from fusion reactor plasma facing components to missile nose cones to boilers.

  19. Advanced High Gradient RF Structure Development

    SciTech Connect

    Kuzikov, S. V. [Institute of Applied Physics, Russian Academy of Sciences, 46 Ulyanov St., Nizhny Novgorod, 603950 (Russian Federation); Omega-P, Inc., 258 Bradley St., New Haven, CT 06510 (United States); Kazakov, S. Yu. [Omega-P, Inc., 258 Bradley St., New Haven, CT 06510 (United States); Fermi National Accelerator Laboratory, Batavia, IL (United States); Jiang, Y. [Yale University, New Haven, CT (United States); Plotkin, M. E.; Vikharev, A. A. [Institute of Applied Physics, Russian Academy of Sciences, 46 Ulyanov St., Nizhny Novgorod, 603950 (Russian Federation); Hirshfield, J. L. [Omega-P, Inc., 258 Bradley St., New Haven, CT 06510 (United States); Yale University, New Haven, CT (United States)

    2010-11-04

    Multi-mode accelerating structures aimed at increasing accelerating gradient are described. Such structures operating in several resonant, equidistantly-spaced, axisymmetric, TM-like eigenmodes allow reduction of exposure time to surface fields, reduction of high-field areas and reduction of those fields which are responsible for electron emission. These effects are planned for use in studying the physics of RF breakdown phenomenon with the goal of designing new high-gradient accelerating structures.

  20. Policy Gradient Semi-markov Decision Process

    Microsoft Academic Search

    Ngo Anh Vien; Taechoong Chung

    2008-01-01

    This paper proposes a simulation-based algorithm for optimizing the average reward in a parameterized continuous-time, finite-state semi-Markov decision process (SMDP). Our contributions are twofold: First, we compute the approximate gradient of the average reward with respect to the parameters in SMDP controlled by parameterized stochastic policies. Then stochastic gradient ascent method is used to adjust the parameters in order to

  1. Spherical gradient coil for ultrafast imaging

    Microsoft Academic Search

    Haiying Liu; Labros S. Petropoulos

    1997-01-01

    High performance magnetic field gradient coils have always been desirable in today’s ultrafast magnetic resonance imaging (MRI) applications, such as single-shot echo-planar imaging and fast spin echo imaging, as well as MR diffusion imaging and microscopy. We present a Lagrange multiplier technique of a minimum inductance gradient coil with spherical geometry. Based on this minimization approach, we construct a functional

  2. Topics in Dynamic Meteorology: Pressure Gradient Force

    NSDL National Science Digital Library

    COMET

    2013-03-12

    This module is a learning object on a foundational aspect of dynamic meteorology, the pressure gradient force. As a learning object, it is meant to supplement other teaching material in a course by elucidating a specific concept. The horizontal pressure gradient force is presented through an interactive tool which allows a student to adjust pressures on an idealized surface map and examine the horizontal accelerations produced in response. Three short exercises are provided to reinforce the concepts.

  3. Nucleation modes in sharp concentration gradients

    SciTech Connect

    Hodaj, F.; Desre, P.J. [LTPCM-UMR CNRS/INPG/UJF, Saint Martin d`Heres (France); Gusak, A.M.; Kovalchuk, A.O. [Cherkassy State Univ. (Ukraine). Dept. of Theoretical Physics

    1998-12-31

    Reaction kinetics in bimetallic multilayers have demonstrated that sharp unidirectional concentration gradient, which develop as interdiffusion proceeds at the interface are able to delay or to suppress nucleation of intermetallics. It has been found that the existence of a critical gradient beyond which nucleation is inhibited is strongly dependent on the mechanism of formation of the embryo. A mechanism of nucleation under concentration gradient ({gradient}c) is proposed and treated on the basis of the Fokker-Planck equation for the distribution in the size space. The influence of the aspect ratio of the embryo on the critical concentration gradient is also studied. Due to the fluctuations of the embryo shape, it is shown that the minimization of the thermodynamic potential leading to the aspect ratio of the embryo is only significant beyond a certain value of the concentration gradient. Application is presented to the nucleation of the compound Ni{sub 10}Zr{sub 7} in an amorphous layer Ni-Zr.

  4. Magnetoelectrets prepared by using temperature gradient method

    NASA Astrophysics Data System (ADS)

    Ojha, Pragya; Qureshi, M. S.; Malik, M. M.

    2015-05-01

    A novel Temperature Gradient method for preparation of magnetoelectret is proposed. Non uniform magnetic field and temperature gradient are expected to be the main cause for the formation of magnetoelectrets (MEs). Being bad conductors of heat, during their formation, there is a possibility for the existence of a temperature gradient along the dielectric electrode interface. In this condition, the motion of, molecules and charge carriers are dependent on Temperature Gradient in a preferred direction. To increase this temperature gradient on both sides of the sample novel method for the preparation of MEs is developed for the first time. For this method the special sample holders are designed in our laboratory. MEs are prepared in such a way that one surface is cooled and the other is heated, during the process. With the help of XRD analysis using Type-E orientation pattern and surface charge studies on magnetoelectrets, the two main causes Non uniform magnetic field and temperature gradient for the formation of magnetoelectrets (MEs), are authenticated experimentally.

  5. Radiology's value chain.

    PubMed

    Enzmann, Dieter R

    2012-04-01

    A diagnostic radiology value chain is constructed to define its main components, all of which are vulnerable to change, because digitization has caused disaggregation of the chain. Some components afford opportunities to improve productivity, some add value, while some face outsourcing to lower labor cost and to information technology substitutes, raising commoditization risks. Digital image information, because it can be competitive at smaller economies of scale, allows faster, differential rates of technological innovation of components, initiating a centralization-to-decentralization technology trend. Digitization, having triggered disaggregation of radiology's professional service model, may soon usher in an information business model. This means moving from a mind-set of "reading images" to an orientation of creating and organizing information for greater accuracy, faster speed, and lower cost in medical decision making. Information businesses view value chain investments differently than do small professional services. In the former model, producing a better business product will extend image interpretation beyond a radiologist's personal fund of knowledge to encompass expanding external imaging databases. A follow-on expansion with integration of image and molecular information into a report will offer new value in medical decision making. Improved interpretation plus new integration will enrich and diversify radiology's key service products, the report and consultation. A more robust, information-rich report derived from a "systems" and "computational" radiology approach will be facilitated by a transition from a professional service to an information business. Under health care reform, radiology will transition its emphasis from volume to greater value. Radiology's future brightens with the adoption of a philosophy of offering information rather than "reads" for decision making. Staunchly defending the status quo via turf wars is unlikely to constitute a forward-looking, competitive strategy. PMID:22438447

  6. Supply Chain Quality Management: A Simulation Study

    Microsoft Academic Search

    Janice K. Winch

    2008-01-01

    This paper demonstrates the application of a sequential experimentation and simulation metamodeling to supply chain quality modeling. The supply chain simulation model exam- ines the effectiveness of supply chain operations, demand uncertainty, supply chain speed, and quality and distribution issues. The effects of critical supply chain factors on quality and speed of a supply chain network are investigated. Our results

  7. Supply Chain Network Design Under Profit Maximization

    E-print Network

    Nagurney, Anna

    Chain Anna Nagurney Supply Chain Network Design Under Competition #12;Examples of Supply Chains food;Food Supply Chains Anna Nagurney Supply Chain Network Design Under Competition #12;High Tech ProductsSupply Chain Network Design Under Profit Maximization and Oligopolistic Competition Anna Nagurney

  8. Musical Markov Chains

    NASA Astrophysics Data System (ADS)

    Volchenkov, Dima; Dawin, Jean René

    A system for using dice to compose music randomly is known as the musical dice game. The discrete time MIDI models of 804 pieces of classical music written by 29 composers have been encoded into the transition matrices and studied by Markov chains. Contrary to human languages, entropy dominates over redundancy, in the musical dice games based on the compositions of classical music. The maximum complexity is achieved on the blocks consisting of just a few notes (8 notes, for the musical dice games generated over Bach's compositions). First passage times to notes can be used to resolve tonality and feature a composer.

  9. Effect of COD level and HRT on microbial community in a yeast-predominant activated sludge system.

    PubMed

    Han, Hui; Zhang, Yanyan; Cui, Cancan; Zheng, Shaokui

    2010-05-01

    This study was conducted to compare the effect of influent chemical oxygen demand (COD(in)) level and hydraulic retention time (HRT), two primary components of influent COD loading rate (COD(LR)), on the structure and function of sludge microbial community in a yeast-predominant activated sludge system (1m Hx0.2m D) for synthetic industrial wastewater. A combination of polymerase chain reaction-denaturing gradient gel electrophoresis with BIOLOG community-level physiological profiles was used. At higher COD(LR) and higher COD(in) and identical HRTs, more microbial species were supported and could metabolise a greater variety of carbon sources in the aerated column. Conversely, a shorter HRT at identical COD(in) supported fewer microbial species, which resulted in the metabolism of fewer carbon sources. PMID:20096563

  10. Bacterial and archaeal communities in Lake Nyos (Cameroon, Central Africa)

    NASA Astrophysics Data System (ADS)

    Tiodjio, Rosine E.; Sakatoku, Akihiro; Nakamura, Akihiro; Tanaka, Daisuke; Fantong, Wilson Y.; Tchakam, Kamtchueng B.; Tanyileke, Gregory; Ohba, Takeshi; Hell, Victor J.; Kusakabe, Minoru; Nakamura, Shogo; Ueda, Akira

    2014-08-01

    The aim of this study was to assess the microbial diversity associated with Lake Nyos, a lake with an unusual chemistry in Cameroon. Water samples were collected during the dry season on March 2013. Bacterial and archaeal communities were profiled using Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE) approach of the 16S rRNA gene. The results indicate a stratification of both communities along the water column. Altogether, the physico-chemical data and microbial sequences suggest a close correspondence of the potential microbial functions to the physico-chemical pattern of the lake. We also obtained evidence of a rich microbial diversity likely to include several novel microorganisms of environmental importance in the large unexplored microbial reservoir of Lake Nyos.

  11. Concurrent tandem living radical polymerization: gradient copolymers via in situ monomer transformation with alcohols.

    PubMed

    Nakatani, Kazuhiro; Terashima, Takaya; Sawamoto, Mitsuo

    2009-09-30

    We developed concurrent tandem living radical polymerization as a novel methodology to efficiently, conveniently, and in one-pot produce gradient copolymers via in situ monomer transformation. The key is to employ a metal alkoxide [Al(Oi-Pr)(3), Ti(Oi-Pr)(4)] and an alcohol solvent (ROH) in ruthenium-catalyzed polymerization of conventional ester-based methyl (meth)acrylate [M(M)A], where the monomer was directly transformed into R(M)A via in situ transesterification to gradually vary the monomer composition during the copolymerization. Typically, methyl methacrylate (MMA) was polymerized with a ruthenium catalyst in the presence of excess ethanol (EtOH) and Al(Oi-Pr)(3) cocatalyst to give well-controlled gradient copolymers from MMA to EMA along the polymer chain, in which the original MMA was gradually converted into ethyl methacrylate (EMA) by the cocatalyst. This concurrent tandem polymerization, in conjunction with a wide variety of alcohols, efficiently and conveniently produced various gradient copolymers including long alkyl chain and PEG pendent groups. The obtained copolymers further exhibited unique physical properties different from the corresponding random and block counterparts. PMID:19725500

  12. Homogeneous chains, heterogeneous chains, and delay of reinforcement

    PubMed Central

    Lattal, Kennon A.; Crawford-Godbey, Cynthia L.

    1985-01-01

    Three pigeons responded on two-component chain schedules in which the required response topography in the initial and terminal links was similar (a homogeneous chain) or dissimilar (a heterogeneous chain). Key-peck responding in the initial link under a variable-interval 60-second (VI 60) schedule produced a terminal link in which, in different conditions, either key pecking or foot treadling was reinforced according to a VI 60 schedule. Multiple VI 60 VI 60 schedules, in which the responses required in the chain schedules were maintained by primary reinforcement in the two components, preceded and followed each type of chain. These multiple schedules were used to ensure that both responses occurred reliably prior to introducing the chain schedule. Key-peck response rates in the initial link of the chain consistently were higher during the homogeneous chain than during the heterogeneous chain. These results illustrate that intervening events during a period separating an operant response from primary reinforcement influence that operant, independently of the delay between the response and reinforcement. PMID:16812436

  13. Global phase diagram of one-dimensional graded diatomic elastic chains: a diagrammatic approach to identifying vibrational normal modes

    Microsoft Academic Search

    J. J. Xiao; K. Yakubo; K. W. Yu

    2007-01-01

    We study vibrational normal modes in graded diatomic chains wherein the masses m1 of one type of atom vary linearly with the gradient c while those of the other type m2 remain constant, in order to examine the diatomic effect on one-dimensional graded elastic chains. By means of a band overlapping picture---a convenient diagrammatic approach---we found six distinct kinds of

  14. Statistical Methods in Markov Chains

    Microsoft Academic Search

    Patrick Billingsley

    1961-01-01

    This paper is an expository survey of the mathematical aspects of statistical inference as it applies to finite Markov chains, the problem being to draw inferences about the transition probabilities from one long, unbroken observation $\\\\{x_1, x_2, \\\\cdots, x_n\\\\}$ on the chain. The topics covered include Whittle's formula, chi-square and maximum-likelihood methods, estimation of parameters, and multiple Markov chains. At

  15. Effect of the Dzyaloshinskii-Moriya interaction on heat conductivity in one-dimensional quantum Ising chains

    NASA Astrophysics Data System (ADS)

    Li, W.; Zhang, Z.; Tong, P.

    2012-02-01

    The effect of the Dzyaloshinskii-Moriya (DM) interaction on the heat conduction in the quantum Ising chain has been studied by solving the Lindblad master equation. The chain is subject to a uniform transverse field h, while the exchange couplings { J m } between the nearest-neighbor spins are either uniform, random or quasi-periodic. The average energy-density profile and the average energy current in the non-equilibrium steady state have been numerically calculated. The ballistic transport is observed in the uniform Ising chain with DM interaction. For the random Ising chain with DM interaction, the energy gradient is observed in the bulk of the spin chain whose energy current appears to scale as the system size ? Q? ˜ exp( ?N) with ? < 0. For the quasi-periodic Ising chain with DM interaction, the J m takes the two values J A and J B arranged in the Fibonacci sequence. The energy gradient also exists in the spin chain and the energy current behaves as ? Q? ˜ N ? with ? < 0. By increasing the strength of the DM interaction D, a non-trivial transition from the thermal insulator heat transport to anomalous heat conduction is found in the Fibonacci Ising chain with large ratio of couplings ? = J A / J B . A rough phase diagram of ? vs. D is given in this paper as well.

  16. Chains with Fractal Dispersion Law

    E-print Network

    Vasily E. Tarasov

    2008-04-03

    Chains with long-range interactions are considered. The interactions are defined such that each nth particle interacts only with chain particles with the numbers n+a(m) and n-a(m), where m=1,2,3,... and a(m) is an integer-valued function. Exponential type functions a(m)=b^m, where b=2,3,.., are discussed. The correspondent pseudodifferential equations of chain oscillations are obtained. Dispersion laws of the suggested chains are described by the Weierstrass and Weierstrass-Mandelbrot functions.

  17. Differentiation Rules: The Chain Rule

    NSDL National Science Digital Library

    Michael Freeze

    Recognize composite functions, including their inner and outer components; decompose composite functions into compositions of elementary functions;differentiate compositions of functions using the chain rule

  18. Supply Chain Coordination in Hospitals

    NASA Astrophysics Data System (ADS)

    Rego, Nazaré; de Sousa, Jorge Pinho

    This paper presents an innovative approach to support the definition of strategies for the design of alternative configurations of hospital supply chains. This approach was developed around a hybrid Tabu Search / Variable Neighbourhood Search metaheuristic, that uses several neighbourhood structures. The flexibility of the procedure allows its application to supply chains with different topologies and atypical cost characteristics. A preliminary computational experience shows the approach potential in solving large scale supply chain configuration problems. The future incorporation of this approach in a broader Decision Support System (DSS) will provide a tool that can significantly contribute to an increase of healthcare supply chains efficiency and encourage the establishment of collaborative partnerships between their members.

  19. Dynamics of Polymer Chains.

    NASA Astrophysics Data System (ADS)

    Hong, Tzay-Ming

    A major objective of this research is to establish at a more fundamental level some of the qualitative or semi-quantitative treatments in use at the present time, such as the Doi-Edwards tube picture, the switch from non -ideal to ideal behavior, and dynamical aspects of the reptation model. The main topics are: (I) An attempt was made to determine the order of magnitude of the elastic time interval of a viscoelastic polymer melt, defining it as the reciprocal of the average rate at which the total entanglement (clockwise plus anticlockwise) passes through zero due to thermal agitation. We calculated the case of a free chain winding about a straight rod both in friction-independent regime and in high friction regime. (II) By successively coarse -graining and rescaling the monomer-monomer interaction (using a modified Wilson recursion formula) we found that the interaction is driven to a very strong but short-ranged one. This verifies the observation that polymers in dilute solutions tend to curl up and behave like hard spheres. (III) We studied the case of chemical equilibrium of i-mers with their nucleating monomers and on the basis of a Flory-Huggins -type mean field theory find that in the dilute limit the swelling of the i-mers takes on the traditional N ^{3over5} law only for sufficiently small monomer chemical potential. When that potential is large enough, then, assuming a Flory law of chain propagation, the law seems to become N^{1over3 }. This is distinct from the problem of changeover from dilute to semidilute polymer system, which we also studied by imposing total polymer density as a constraint equation. (IV) Another item examined concerns the form of the space curve that a very long polymer must assume in order to minimize its free energy (we found that a family of helices with a definite functional relation between pitch and radius renders the free energy stationary). Because a chain is a one-dimensional object, this does not mean that helical shapes have any kind of permanence; presumably the usual entropic considerations concerning one-dimensional disorder mean that they have only finite lifetime and very limited coherence length. Nonetheless this helical tendency could very well play a role in processes involving short time and/or distance scales.

  20. Image super-resolution using gradient profile prior

    Microsoft Academic Search

    Jian Sun; Zongben Xu; Heung-yeung Shum

    2008-01-01

    In this paper, we propose an image super-resolution ap- proach using a novel generic image prior - gradient profile prior, which is a parametric prior describing the shape and the sharpness of the image gradients. Using the gradient profile prior learned from a large number of natural im- ages, we can provide a constraint on image gradients when we estimate

  1. Finite range decomposition for families of gradient Gaussian Stefan Adamsa

    E-print Network

    Burton, Geoffrey R.

    that the discrete Greens function CA of the (elliptic) translation invariant difference operator A = A can into gradient Gaus- sian fields such that the gradient-gradient correlation E ir (x) js (y) = i j E r (x)s (y|-d with the critical exponent -d). In the language of quantum field theory gradient Gaussian fields are thus often

  2. Importance of Ionospheric Gradients for error Correction

    NASA Astrophysics Data System (ADS)

    Ravula, Ramprasad

    Importance of Ionospheric Gradients for error Correction R. Ram Prasad1, P.Nagasekhar2 1Sai Spurthi Institute of Technology-JNTU Hyderabad,2Sai Spurthi Institute of Technology-JNTU Hyderabad Email ID:rams.ravula@gmail.com In India, Indian Space Research Organization (ISRO) has established with an objective to develop space technology and its application to various national tasks. To cater to the needs of civil aviation applications, GPS Aided Geo Augmented Navigation (GAGAN) system is being jointly implemented along with Airports Authority of India (AAI) over the Indian region. The most predominant parameter affecting the navigation accuracy of GAGAN is ionospheric delay which is a function of total number of electrons present in one square meter cylindrical cross sectional area in the line of site direction between the satellite and the user on the earth i.e. Total Electron Content (TEC).The irregular distribution of electron densities i.e. rate of TEC variation, causes Ionospheric gradients such as spatial gradients (Expressed in TECu/km) and temporal gradients (Expressed in TECu /minute). Among the satellite signals arriving to the earth in multiple directions, the signals which suffer from severe ionospheric gradients can be estimated i.e. Rate of TEC Index (ROTI) and Rate of TEC (ROT). These aspects which contribute to errors can be treated for improving GAGAN positional accuracy.

  3. Population Gradients in Stellar Halos from GHOSTS

    NASA Astrophysics Data System (ADS)

    Bailin, Jeremy; Monachesi, Antonela; Bell, Eric F.; de Jong, Roelof S.; Ghosts Survey

    2015-01-01

    We report on recent results from the Galaxy Halos, Outer disks, Substructure, Thick disks, and Star clusters (GHOSTS) survey, an HST ACS+WFC3 imaging survey to study stellar populations in and around 16 nearby spiral galaxies. By using HST resolution to resolve the stellar halos into individual red giant branch (RGB) stars, we are able to detect distinct stellar populations at several points throughout the halo of the half dozen massive highly-inclined galaxies in the sample. In approximately half of these galaxies, we detect a gradient in the color of the RGB; which we interpret as a metallicity gradient. Stellar halo formation models predict a wide variety of metallicity gradients: those in which the halos are dominated by stars formed in situ predict stronger gradients than we observe, while accretion-dominated halo models predict weaker or nonexistent gradients. Our measurements therefore provide a useful discriminator between stellar halo models, and at first look appear most consistent with the accretion-based model of Cooper et al. (2010).

  4. Gradient algorithm applied to laboratory quantum control

    SciTech Connect

    Roslund, Jonathan; Rabitz, Herschel [Department of Chemistry, Princeton University, Princeton, New Jersey 08544 (United States)

    2009-05-15

    The exploration of a quantum control landscape, which is the physical observable as a function of the control variables, is fundamental for understanding the ability to perform observable optimization in the laboratory. For high control variable dimensions, trajectory-based methods provide a means for performing such systematic explorations by exploiting the measured gradient of the observable with respect to the control variables. This paper presents a practical, robust, easily implemented statistical method for obtaining the gradient on a general quantum control landscape in the presence of noise. In order to demonstrate the method's utility, the experimentally measured gradient is utilized as input in steepest-ascent trajectories on the landscapes of three model quantum control problems: spectrally filtered and integrated second harmonic generation as well as excitation of atomic rubidium. The gradient algorithm achieves efficiency gains of up to approximately three times that of the standard genetic algorithm and, as such, is a promising tool for meeting quantum control optimization goals as well as landscape analyses. The landscape trajectories directed by the gradient should aid in the continued investigation and understanding of controlled quantum phenomena.

  5. Critical gradient formula for toroidal electron temperature gradient modes F. Jenko, W. Dorland,a)

    E-print Network

    Hammett, Greg

    Critical gradient formula for toroidal electron temperature gradient modes F. Jenko, W. Dorland,a) and G. W. Hammettb) Max-Planck-Institut fu¨r Plasmaphysik, EURATOM Association, 85748 Garching, Germany Received 9 March 2001; accepted 18 June 2001 Under certain conditions, the electron heat transport induced

  6. Model of separation performance of bilinear gradients in scanning format counter-flow gradient electrofocusing techniques.

    PubMed

    Shameli, Seyed Mostafa; Glawdel, Tomasz; Ren, Carolyn L

    2015-03-01

    Counter-flow gradient electrofocusing allows the simultaneous concentration and separation of analytes by generating a gradient in the total velocity of each analyte that is the sum of its electrophoretic velocity and the bulk counter-flow velocity. In the scanning format, the bulk counter-flow velocity is varying with time so that a number of analytes with large differences in electrophoretic mobility can be sequentially focused and passed by a single detection point. Studies have shown that nonlinear (such as a bilinear) velocity gradients along the separation channel can improve both peak capacity and separation resolution simultaneously, which cannot be realized by using a single linear gradient. Developing an effective separation system based on the scanning counter-flow nonlinear gradient electrofocusing technique usually requires extensive experimental and numerical efforts, which can be reduced significantly with the help of analytical models for design optimization and guiding experimental studies. Therefore, this study focuses on developing an analytical model to evaluate the separation performance of scanning counter-flow bilinear gradient electrofocusing methods. In particular, this model allows a bilinear gradient and a scanning rate to be optimized for the desired separation performance. The results based on this model indicate that any bilinear gradient provides a higher separation resolution (up to 100%) compared to the linear case. This model is validated by numerical studies. PMID:25308774

  7. Quiet gradient coils: active acoustically and magnetically screened distributed transverse gradient designs

    Microsoft Academic Search

    B L W Chapman

    The principle of active acoustic screening, recently introduced by Mansfield, Glover and Bowtell into the design of gradient coils for MRI, utilizes Lorentz force balancing to reduce acoustic noise. In this paper, the active acoustic screening principle is used to design cylindrical transverse gradients with distributed conductor or fingerprint designs for the primary. A second distributed conductor on a second

  8. NNSA TRITIUM SUPPLY CHAIN

    SciTech Connect

    Wyrick, Steven [Savannah River National Laboratory, Aiken, SC, USA; Cordaro, Joseph [Savannah River National Laboratory, Aiken, SC, USA; Founds, Nanette [National Nuclear Security Administration, Albuquerque, NM, USA; Chambellan, Curtis [National Nuclear Security Administration, Albuquerque, NM, USA

    2013-08-21

    Savannah River Site plays a critical role in the Tritium Production Supply Chain for the National Nuclear Security Administration (NNSA). The entire process includes: • Production of Tritium Producing Burnable Absorber Rods (TPBARs) at the Westinghouse WesDyne Nuclear Fuels Plant in Columbia, South Carolina • Production of unobligated Low Enriched Uranium (LEU) at the United States Enrichment Corporation (USEC) in Portsmouth, Ohio • Irradiation of TPBARs with the LEU at the Tennessee Valley Authority (TVA) Watts Bar Reactor • Extraction of tritium from the irradiated TPBARs at the Tritium Extraction Facility (TEF) at Savannah River Site • Processing the tritium at the Savannah River Site, which includes removal of nonhydrogen species and separation of the hydrogen isotopes of protium, deuterium and tritium.

  9. Chain Dynamics in Magnetorheological Suspensions

    NASA Technical Reports Server (NTRS)

    Gast, A. P.; Furst, E. M.

    1999-01-01

    Magnetorheological (MR) suspensions are composed of colloidal particles which acquire dipole moments when subjected to an external magnetic field. At sufficient field strengths and concentrations, the dipolar particles rapidly aggregate to form long chains. Subsequent lateral cross-linking of the dipolar chains is responsible for a rapid liquid-to-solid-like rheological transition. The unique, magnetically-activated rheological properties of MR suspensions make them ideal for interfacing mechanical systems to electronic controls. Additionally, the ability to experimentally probe colloidal suspensions interacting through tunable anisotropic potentials is of fundamental interest. Our current experimental work has focused on understanding the fluctuations of dipolar chains. It has been proposed by Halsey and Toor (HT) that the strong Landau-Peierls thermal fluctuations of dipolar chains could be responsible for long-range attractions between chains. Such interactions will govern the long-time relaxation of MR suspensions. We have synthesized monodisperse neutrally buoyant MR suspensions by density matching stabilized ferrofluid emulsion droplets with D2O. This allows us to probe the dynamics of the dipolar chains using light scattering without gravitational, interfacial, and polydispersity effects to resolve the short-wavelength dynamics of the dipolar chains. We used diffusing wave spectroscopy to measure these dynamics. The particle displacements at short times that show an independence to the field strength, but at long times exhibit a constrained, sub-diffusive motion that slows as the dipole strength is increased. The experiments are in good qualitative agreement with Brownian dynamics simulations of dipolar chains. Although there have been several important and detailed studies of the structure and interactions in MR suspensions, there has not been conclusive evidence that supports or contradicts the HT model prediction that long-range interactions exist between fluctuating chains of dipolar particles. Resolving this issue would contribute greatly to the understanding of these interesting and important materials. We have begun to test the predictions of the HT model by both examining the dynamics of individual chains and by measuring the forces between dipolar chains directly to accurately and quantitatively assess the interactions that they experience. To do so, we employ optical trapping techniques and video-microscopy to manipulate and observe our samples on the microscopic level. With these techniques, it is possible to observe chains that are fluctuating freely in three-dimensions, independent of interfacial effects. More importantly, we are able to controllably observe the interactions of two chains at various separations to measure the force-distance profile. The techniques also allow us to study the mechanical properties of individual chains and chain clusters. Our work to this point has focused on reversibly-formed dipolar chains due to field induced dipoles where the combination of this chaining, the dipolar forces, and the hydrodynamic interactions that dictate the rheology of the suspensions. One can envision, however, many situations where optical, electronic, or rheological behavior may be optimized with magneto-responsive anisotropic particles. Chains of polarizable particles may have the best properties as they can coil and flex in the absence of a field and stiffen and orient when a field is applied. We have recently demonstrated a synthesis of stable, permanent paramagnetic chains by both covalently and physically linking paramagnetic colloidal particles. The method employed allows us to create monodisperse chains of controlled length. We observed the stability, field-alignment, and rigidity of this new class of materials. The chains may exhibit unique rheological properties in an applied magnetic field over isotropic suspensions of paramagnetic particles. They are also useful rheological models as bead-spring systems. These chains form the basis for our current experiments with optical traps.

  10. Detection of point mutations by capillary electrophoresis with temporal temperature gradients.

    PubMed

    Schell, J; Wulfert, M; Riesner, D

    1999-10-01

    By combining the advantages of capillary electrophoresis and temperature gradient gel electrophoresis, a method was developed to detect point mutations in polymerase chain reaction (PCR) fragments. Increasing and decreasing temporal temperature gradients were established by means of a computer-controlled Peltier module. Native and denaturing conditions were achieved by cooling to 25 degrees C and heating to 70 degrees C, respectively, a thermostating liquid surrounding the capillary. To separate nucleic acid fragments, a sieving media, containing 4% linear polyacrylamide, 1 x Tris borate EDTA buffer (TBE) and 6 M urea, was found appropriate. Renewal of the sieving matrix before each run significantly improved the reproducibility of fragment separation. The ability of this capillary electrophoresis system to detect point mutations is demonstrated with the human prion-protein gene. PMID:10546821

  11. Adaptive Thermostats for Noisy Gradient Systems

    E-print Network

    Leimkuhler, Benedict

    2015-01-01

    We study numerical methods for sampling probability measures in high dimensions where the underlying model is only approximately identified with a gradient system. Extended stochastic dynamical methods are discussed which have application to multiscale models, nonequilibrium molecular dynamics and Bayesian sampling techniques arising in emerging machine learning applications. In addition to providing a more comprehensive discussion of the foundations of these methods, we propose a new numerical method for the Adaptive Langevin/stochastic gradient Nos\\'e-Hoover thermostat that achieves a dramatic improvement in numerical efficiency over the most popular stochastic gradient methods reported in the literature. We also demonstrate that the newly-established method inherits a superconvergence property (fourth order convergence to the invariant measure for configurational quantities) recently demonstrated in the setting of Langevin dynamics. Our findings are verified by numerical experiments.

  12. Shadowgraph Study of Gradient Driven Fluctuations

    NASA Technical Reports Server (NTRS)

    Cannell, David; Nikolaenko, Gennady; Giglio, Marzio; Vailati, Alberto; Croccolo, Fabrizio; Meyer, William

    2002-01-01

    A fluid or fluid mixture, subjected to a vertical temperature and/or concentration gradient in a gravitational field, exhibits greatly enhanced light scattering at small angles. This effect is caused by coupling between the vertical velocity fluctuations due to thermal energy and the vertically varying refractive index. Physically, small upward or downward moving regions will be displaced into fluid having a refractive index different from that of the moving region, thus giving rise to the enhanced scattering. The scattered intensity is predicted to vary with scattering wave vector q, as q(sup -4), for sufficiently large q, but the divergence is quenched by gravity at small q. In the absence of gravity, the long wavelength fluctuations responsible for the enhanced scattering are predicted to grow until limited by the sample dimensions. It is thus of interest to measure the mean-squared amplitude of such fluctuations in the microgravity environment for comparison with existing theory and ground based measurements. The relevant wave vectors are extremely small, making traditional low-angle light scattering difficult or impossible because of stray elastically scattered light generated by optical surfaces. An alternative technique is offered by the shadowgraph method, which is normally used to visualize fluid flows, but which can also serve as a quantitative tool to measure fluctuations. A somewhat novel shadowgraph apparatus and the necessary data analysis methods will be described. The apparatus uses a spatially coherent, but temporally incoherent, light source consisting of a super-luminescent diode coupled to a single-mode optical fiber in order to achieve extremely high spatial resolution, while avoiding effects caused by interference of light reflected from the various optical surfaces that are present when using laser sources. Results obtained for a critical mixture of aniline and cyclohexane subjected to a vertical temperature gradient will be presented. The sample was confined between two horizontal parallel sapphire plates with a vertical spacing of 1 mm. The temperatures of the sapphire plates were controlled by independent circulating water loops that used Peltier devices to add or remove heat from the room air as required. For a mixture with a temperature gradient, two effects are involved in generating the vertical refractive index gradient, namely thermal expansion and the Soret effect, which generates a concentration gradient in response to the applied temperature gradient. For the aniline/cyclohexane system, the denser component (aniline) migrates toward the colder surface. Consequently, when heating from above, both effects result in the sample density decreasing with altitude and are stabilizing in the sense that no convective motion occurs regardless of the magnitude of the applied temperature gradient. The Soret effect is strong near a binary liquid critical point, and thus the dominant effect is due to the induced concentration gradient. The results clearly show the divergence at low q and the predicted gravitational quenching. Results obtained for different applied temperature gradients at varying temperature differences from the critical temperature, clearly demonstrate the predicted divergence of the thermal diffusion ratio. Thus, the more closely the critical point is approached, the smaller becomes the temperature gradient required to generate the same signal. Two different methods have been used to generate pure concentration gradients. In the first, a sample cell was filled with a single fluid, ethylene glycol, and a denser miscible fluid, water, was added from below thus establishing a sharp interface to begin the experiment. As time went on the two fluids diffused into each other, and large amplitude fluctuations were clearly observed at low q. The effects of gravitational quenching were also evident. In the second method, the aniline/cyclohexane sample was used, and after applying a vertical temperature gradient for several hours, the top and bottom temperatures were set equal and the thermal

  13. How receptor diffusion influences gradient sensing.

    PubMed

    Nguyen, H; Dayan, P; Goodhill, G J

    2015-01-01

    Chemotaxis, or directed motion in chemical gradients, is critical for various biological processes. Many eukaryotic cells perform spatial sensing, i.e. they detect gradients by comparing spatial differences in binding occupancy of chemosensory receptors across their membrane. In many theoretical models of spatial sensing, it is assumed, for the sake of simplicity, that the receptors concerned do not move. However, in reality, receptors undergo diverse modes of diffusion, and can traverse considerable distances in the time it takes such cells to turn in an external gradient. This sets a physical limit on the accuracy of spatial sensing, which we explore using a model in which receptors diffuse freely over the membrane. We find that the Fisher information carried in binding and unbinding events decreases monotonically with the diffusion constant of the receptors. PMID:25551145

  14. Stereo transparency and the disparity gradient limit

    NASA Technical Reports Server (NTRS)

    McKee, Suzanne P.; Verghese, Preeti

    2002-01-01

    Several studies (Vision Research 15 (1975) 583; Perception 9 (1980) 671) have shown that binocular fusion is limited by the disparity gradient (disparity/distance) separating image points, rather than by their absolute disparity values. Points separated by a gradient >1 appear diplopic. These results are sometimes interpreted as a constraint on human stereo matching, rather than a constraint on fusion. Here we have used psychophysical measurements on stereo transparency to show that human stereo matching is not constrained by a gradient of 1. We created transparent surfaces composed of many pairs of dots, in which each member of a pair was assigned a disparity equal and opposite to the disparity of the other member. For example, each pair could be composed of one dot with a crossed disparity of 6' and the other with uncrossed disparity of 6', vertically separated by a parametrically varied distance. When the vertical separation between the paired dots was small, the disparity gradient for each pair was very steep. Nevertheless, these opponent-disparity dot pairs produced a striking appearance of two transparent surfaces for disparity gradients ranging between 0.5 and 3. The apparent depth separating the two transparent planes was correctly matched to an equivalent disparity defined by two opaque surfaces. A test target presented between the two transparent planes was easily detected, indicating robust segregation of the disparities associated with the paired dots into two transparent surfaces with few mismatches in the target plane. Our simulations using the Tsai-Victor model show that the response profiles produced by scaled disparity-energy mechanisms can account for many of our results on the transparency generated by steep gradients.

  15. Gradient Learning Algorithms for Ontology Computing

    PubMed Central

    Gao, Wei; Zhu, Linli

    2014-01-01

    The gradient learning model has been raising great attention in view of its promising perspectives for applications in statistics, data dimensionality reducing, and other specific fields. In this paper, we raise a new gradient learning model for ontology similarity measuring and ontology mapping in multidividing setting. The sample error in this setting is given by virtue of the hypothesis space and the trick of ontology dividing operator. Finally, two experiments presented on plant and humanoid robotics field verify the efficiency of the new computation model for ontology similarity measure and ontology mapping applications in multidividing setting. PMID:25530752

  16. Gravity gradient determination with tethered systems

    NASA Technical Reports Server (NTRS)

    Kalaghan, P. M.; Colombo, G.

    1978-01-01

    A detailed investigation of the Earth's gravity field is needed for application to modern solid earth and oceanic investigations. The use of gravity gradiometers presents a technique to measure the intermediate wavelength components of the gravity field. One configuration of a gradiometer involves a tethered pair of masses orbiting the Earth and stabilized by vertical gravity gradient of the earth. A mesurement of the tension in such a system, called the DUMBBELL system is described. It allows the determination of the vertical gradient of the anomalous component of the Earth's gravtiy field. Preliminary analysis of the dynamics, mechanization, expected signal levels and noise environment indicates that the Dumbbell system is feasible.

  17. The effect of density gradients on hydrometers

    NASA Astrophysics Data System (ADS)

    Heinonen, Martti; Sillanpää, Sampo

    2003-05-01

    Hydrometers are simple but effective instruments for measuring the density of liquids. In this work, we studied the effect of non-uniform density of liquid on a hydrometer reading. The effect induced by vertical temperature gradients was investigated theoretically and experimentally. A method for compensating for the effect mathematically was developed and tested with experimental data obtained with the MIKES hydrometer calibration system. In the tests, the method was found reliable. However, the reliability depends on the available information on the hydrometer dimensions and density gradients.

  18. Relativistic klystron research for high gradient accelerators

    SciTech Connect

    Allen, M.A.; Callin, R.S.; Deruyter, H.; Eppley, K.R.; Fowkes, W.R.; Herrmannsfeldt, W.B.; Higo, T.; Hoag, H.A.; Lavine, T.L.; Lee, T.G.

    1988-06-01

    Relativistic klystrons are being developed as a power source for high gradient accelerator applications which include large linear electron--positron colliders, compact accelerators, and FEL sources. We have attained 200MW peak power at 11.4 GHz from a relativistic klystron, and 140 MV/m longitudinal gradient in a short 11.4 GHz accelerator section. We report here on the design of our first klystrons, the results of our experiments so far, and some of our plans for the near future. 5 refs., 7 figs.

  19. Monitoring the vaccine cold chain

    Microsoft Academic Search

    E Cheriyan

    1993-01-01

    Maintaining the vaccine cold chain is an essential part of a successful immunisation programme. A continuous electronic temperature monitor helped to identify breaks in the cold chain in the community and the study led to the issue of proper guidelines and replacement of faulty equipment.

  20. Building an efficient supply chain.

    PubMed

    Scalise, Dagmara

    2005-08-01

    Realizing at last that supply chain management can produce efficiencies and save costs, hospitals are beginning to adopt practices from other industries, such as the concept of extended supply chains, to improve product flow. They're also investing in enterprise planning resource software, radio frequency identification and other technologies, using quality data to drive standardization and streamlining processes. PMID:16225319

  1. IMPROVING SUPPLY CHAIN PERFORMANCE THROUGH

    E-print Network

    Keskinocak, Pinar

    Chapter 1 IMPROVING SUPPLY CHAIN PERFORMANCE THROUGH BUYER COLLABORATION Paul M. Griffin Pinar, as more companies strive to streamline their interactions with their supply chain partners. PTXs have with different levels of collaboration, namely, (i) no collabora- tion among buyers or buyer divisions, (ii

  2. Polymerase Chain Reaction Assay and

    E-print Network

    Paris-Sud XI, Université de

    , warm, and windy season, between January and May, localized epidemics of meningococcal meningitis occurPolymerase Chain Reaction Assay and Bacterial Meningitis Surveillance in Remote Areas, Niger Fati reference laboratory for meningitis in Niger used polymerase chain reaction (PCR) to enhance

  3. Chain Migration of Neuronal Precursors

    Microsoft Academic Search

    Carlos Lois; Jose-Manuel Garcia-Verdugo; Arturo Alvarez-Buylla

    1996-01-01

    In the brain of adult mice, cells that divide in the subventricular zone of the lateral ventricle migrate up to 5 millimeters to the olfactory bulb where they differentiate into neurons. These migrating cells were found to move as chains through a well-defined pathway, the rostral migratory stream. Electron microscopic analysis of serial sections showed that these chains contained only

  4. Practical Markov Chain Monte Carlo

    Microsoft Academic Search

    Charles J. Geyer

    1992-01-01

    Markov chain Monte Carlo using the Metropolis-Hastings algorithm is a general method for the simulation of stochastic processes having probability densities known up to a constant of proportionality. Despite recent advances in its theory, the practice has remained controversial. This article makes the case for basing all inference on one long run of the Markov chain and estimating the Monte

  5. THE SMARTER SUPPLY CHAIN OF THE FUTURE

    E-print Network

    . Interconnected ­ Integrating the entire supply chain to share information, make decisions collaborativelyTHE SMARTER SUPPLY CHAIN OF THE FUTURE GLOBAL CHIEF SUPPLY CHAIN OFFICER STUDY LIFE SCIENCES Chain Officer Study, we conducted face-to-face interviews with nearly 400 senior supply chain executives

  6. Managing supply chain at high technology companies

    Microsoft Academic Search

    S. Soin; L. Al-Hakim

    2004-01-01

    There is an expectation that high technology companies use unique and leading edge technology, and invest heavily in supply chain management. This research uses multiple case study methodology to determine factors affecting the supply chain management at high technology companies. The research benchmarks the supply chain performance of these high technology companies with supply chain of other supply chains at

  7. Gradient-Domain Processing of Large Images

    E-print Network

    Kazhdan, Michael

    Gradient-Domain Processing of Large Images Misha Kazhdan and Hugues Hoppe Johns Hopkins University to represent images, it is not how our eyes process visual information. 1 1 #12;Motivation We tend to think way to represent images, it is not how our eyes process visual information. So it might

  8. Gradient-Domain Processing of Large Images

    E-print Network

    Kazhdan, Michael

    Gradient-Domain Processing of Large Images Misha Kazhdan and Hugues Hoppe Johns Hopkins University to represent images, it is not how our eyes process visual information. 1 W 1 H #12;Motivation We tend to think way to represent images, it is not how our eyes process visual information. So it might

  9. Implementation of Deflated Preconditioned Conjugate Gradient

    E-print Network

    Vuik, Kees

    -by-Step Optimizations ·Profiler for Advice ·Modularity and Readability Methodology #12;·DIA Format is best ·Spm% of bandwidth ·Clubbing Kernels ­ Reducing Memory Traffic Deflated Preconditioned Conjugate Gradient bE 1 #12;·Density Contrast 1000:1 · ·False Stop Two Phase Matrix 1 2 2 10 |||| |||| 0 k kexact X XX #12

  10. Image Restoration by Matching Gradient Distributions

    Microsoft Academic Search

    Taeg Sang Cho; C. Lawrence Zitnick; Neel Joshi; Sing Bing Kang; Richard Szeliski; William T. Freeman

    2012-01-01

    The restoration of a blurry or noisy image is commonly performed with a MAP estimator, which maximizes a posterior probability to reconstruct a clean image from a degraded image. A MAP estimator, when used with a sparse gradient image prior, reconstructs piecewise smooth images and typically removes textures that are important for visual realism. We present an alternative deconvolution method

  11. Electron Transport and the Critical Gradient

    NASA Astrophysics Data System (ADS)

    Horton, W.; Hoang, T.

    2005-10-01

    New experiments on Tore Supra with upgraded, higher power radio frequency heating systems with total powers up to 10 MW give new data points on the core temperature and temperature profiles versus injected power. The talk will review the evidence for the two space scales on which electron transport occurs: from (i) the large scale trapped electron modes (TEM-ITG) and (ii) the small scale electron temperature gradient (ETG) turbulence. Joint IFS - Tore Supra transport analysis for electron power balance gives a database for discharges driven by Fast Wave Electron Heating in for ?E<=100 ms. The wide range of RF heating powers from near Ohmic 1 MW to above 10 MW produce an order of magnitude increase in the radial thermal flux. High resolution electron temperature data and true steady state conditions in TS allow give well defined electron thermal diffusivities for the classical circular cross section, large aspect ratio (R/a = 2.2 m/ 0.7 m) tokamak. The heat flux versus the temperature gradient relationship is presented and compared with standard theoretical models for the thermal flux qe(Te). The extrapolation to zero heat flux of the flux-versus-gradient data yields a well-defined critical electron temperature gradient. Histograms of the anomalous thermal diffusivities before and after being normalized to the theoretical models are constructed to evaluate the quantitatively the prediction. Work supported by Dept. of Energy and the CEA-Cadarache

  12. Prospects for a Gradient Magnetometer Atom Interferometer

    NASA Astrophysics Data System (ADS)

    Narducci, Frank A.; Davis, Jon P.

    2008-03-01

    Atom interferometers form the basis for state-of-the-art sensors, including gravimeters, gravity gradiometers, gyroscopes and atomic clocks. Notably absent from this list are magnetometers, which can have a wide range of applications ranging from military to medical applications. We propose a scheme to realize an atom interferometer gradient magnetometer. We begin by demonstrating a light-pulse magnetic beam-splitter. The analysis is based on a full multi-level 2-laser field Maxwell-Bloch model including state selection rules, polarization selectivity, laser detuning, and Doppler averaging. We then consider an ensemble of atoms subject to a ?/2-?-?/2 pulse sequence. The phase of the interference pattern depends on the phase of the action along the classical path and on the phase of the combined laser fields imprinted on the atoms during the pulse sequence. From this analysis, we conclude that, to first order, the phase of the interferometer output is insensitive to the field across the interferometer, but is sensitive to the gradient of the field. Using realizable numbers from existing interferometers, we show that a gradient magnetometer of this type has can have a greater gradient sensitivity than many current magnetic sensors. We discuss the status of our current experiments using ultra-cold atoms.

  13. Escalation of polymerization in a thermal gradient

    PubMed Central

    Mast, Christof B.; Schink, Severin; Gerland, Ulrich; Braun, Dieter

    2013-01-01

    For the emergence of early life, the formation of biopolymers such as RNA is essential. However, the addition of nucleotide monomers to existing oligonucleotides requires millimolar concentrations. Even in such optimistic settings, no polymerization of RNA longer than about 20 bases could be demonstrated. How then could self-replicating ribozymes appear, for which recent experiments suggest a minimal length of 200 nt? Here, we demonstrate a mechanism to bridge this gap: the escalated polymerization of nucleotides by a spatially confined thermal gradient. The gradient accumulates monomers by thermophoresis and convection while retaining longer polymers exponentially better. Polymerization and accumulation become mutually self-enhancing and result in a hyperexponential escalation of polymer length. We describe this escalation theoretically under the conservative assumption of reversible polymerization. Taking into account the separately measured thermophoretic properties of RNA, we extrapolate the results for primordial RNA polymerization inside a temperature gradient in pores or fissures of rocks. With a dilute, nanomolar concentration of monomers the model predicts that a pore length of 5 cm and a temperature difference of 10 K suffice to polymerize 200-mers of RNA in micromolar concentrations. The probability to generate these long RNAs is raised by a factor of >10600 compared with polymerization in a physical equilibrium. We experimentally validate the theory with the reversible polymerization of DNA blocks in a laser-driven thermal trap. The results confirm that a thermal gradient can significantly enlarge the available sequence space for the emergence of catalytically active polymers. PMID:23630280

  14. A WASSERSTEIN GRADIENT FLOW APPROACH TO POISSON ...

    E-print Network

    2015-01-20

    as the gradient flow of a free energy consisting of the Boltzmann entropy with a potential ?,. F(?) = ?. R d .... both to the specific Poisson kernel and to the nonscalar setting. First, as neither the ..... (2) If 1 Cp,d such that. ??

  15. Snakes, shapes, and gradient vector flow

    Microsoft Academic Search

    Chenyang Xu; Jerry L. Prince

    1998-01-01

    Snakes, or active contours, are used extensively in computer vision and image processing applications, particularly to locate object boundaries. Problems associated with initializa- tion and poor convergence to boundary concavities, however, have limited their utility. This paper presents a new external force for active contours, largely solving both problems. This external force, which we call gradient vector flow (GVF), is

  16. Biplanar gradient coil design by simulated annealing

    Microsoft Academic Search

    A. M. Peters; R. W. Bowtell

    1994-01-01

    Simulated annealing has been applied to the design of biplanar gradient coils for use in NMR microscopy. This method allows a variety of coil parameters to be considered, such as homogeneity over a specified region of interest (ROI), power dissipation, and efficiency. Chosen parameters are represented in an overall figure of merit which is then minimized by the simulated annealing

  17. Minimum maximum temperature gradient coil design.

    PubMed

    While, Peter T; Poole, Michael S; Forbes, Larry K; Crozier, Stuart

    2013-08-01

    Ohmic heating is a serious problem in gradient coil operation. A method is presented for redesigning cylindrical gradient coils to operate at minimum peak temperature, while maintaining field homogeneity and coil performance. To generate these minimaxT coil windings, an existing analytic method for simulating the spatial temperature distribution of single layer gradient coils is combined with a minimax optimization routine based on sequential quadratic programming. Simulations are provided for symmetric and asymmetric gradient coils that show considerable improvements in reducing maximum temperature over existing methods. The winding patterns of the minimaxT coils were found to be heavily dependent on the assumed thermal material properties and generally display an interesting "fish-eye" spreading of windings in the dense regions of the coil. Small prototype coils were constructed and tested for experimental validation and these demonstrate that with a reasonable estimate of material properties, thermal performance can be improved considerably with negligible change to the field error or standard figures of merit. PMID:23042696

  18. Magnetic Control of Concentration Gradient in Microgravity

    NASA Technical Reports Server (NTRS)

    Leslie, Fred; Ramachandran, Narayanan

    2005-01-01

    A report describes a technique for rapidly establishing a fluid-concentration gradient that can serve as an initial condition for an experiment on solutal instabilities associated with crystal growth in microgravity. The technique involves exploitation of the slight attractive or repulsive forces exerted on most fluids by a magnetic-field gradient. Although small, these forces can dominate in microgravity and therefore can be used to hold fluids in position in preparation for an experiment. The magnetic field is applied to a test cell, while a fluid mixture containing a concentration gradient is prepared by introducing an undiluted solution into a diluting solution in a mixing chamber. The test cell is then filled with the fluid mixture. Given the magnetic susceptibilities of the undiluted and diluting solutions, the magnetic-field gradient must be large enough that the magnetic force exceeds both (1) forces associated with the flow of the fluid mixture during filling of the test cell and (2) forces imposed by any residual gravitation and fluctuations thereof. Once the test cell has been filled with the fluid mixture, the magnetic field is switched off so that the experiment can proceed, starting from the proper initial conditions.

  19. Wingless gradient formation in the Drosophila wing

    Microsoft Academic Search

    Maura Strigini; Stephen M. Cohen

    2000-01-01

    Background: Secreted signaling proteins of the Wingless (Wg)\\/Wnt, Hedgehog and bone morphogenetic protein (BMP)\\/Decapentaplegic (Dpp) families function as morphogens to control growth and pattern formation during development. Although these proteins have been shown to act directly on distant cells in the developing limbs of the fruit fly Drosophila, little is known about how ligand gradients form in vivo. Wg protein

  20. Visual tracking, active vision, and gradient flows

    Microsoft Academic Search

    Allen Tannenbaum; Anthony Yezzi

    In this note, we discuss the minimization of certain functionals and the resulting gradient flows for problems in active vision.\\u000a In particular, we consider how these techniques may be applied to deformable contours, and L\\u000a 1-based methods for optical flow. Such techniques are becoming essential tools in the emerging field of controlled active vision.

  1. Multi-gradient drilling method and system

    DOEpatents

    Maurer, William C. (Houston, TX); Medley, Jr., George H. (Spring, TX); McDonald, William J. (Houston, TX)

    2003-01-01

    A multi-gradient system for drilling a well bore from a surface location into a seabed includes an injector for injecting buoyant substantially incompressible articles into a column of drilling fluid associated with the well bore. Preferably, the substantially incompressible articles comprises hollow substantially spherical bodies.

  2. Gradient Clock Synchronization in Wireless Sensor Networks

    E-print Network

    Gradient Clock Synchronization in Wireless Sensor Networks Philipp Sommer Computer Engineering clocks are crucial for many ap- plications in sensor networks. Existing time synchro- nization algorithms Francisco, California, USA. Copyright 2009 ACM 978-1-60558-371-6/09/04 ...$5.00. 1. INTRODUCTION A wireless

  3. Fourier Accelerated Conjugate Gradient Lattice Gauge Fixing

    E-print Network

    R. J. Hudspith

    2014-05-22

    We provide details of the first implementation of a non-linear conjugate gradient method for Landau and Coulomb gauge fixing with Fourier acceleration. We find clear improvement over the Fourier accelerated steepest descent method, with the average time taken for the algorithm to converge to a fixed, high accuracy, being reduced by a factor of 2 to 4.

  4. TEMPERATURE AND PRESSURE GRADIENTS IN GAS WELLS

    Microsoft Academic Search

    M. R. Teck; Donald Katz; Jack Elenbaas; Michael Whims; Joseph Roberts

    1978-01-01

    A stepwise procedure has been developed for successsive calculation of pressure and temperature gradients in gas wells during production or injection. The method, based on a thermodynamic energy balance in the well bore and the usual equations for the flow of natural gas in vertical pipe, is shown to give reasonably accurate predictions when evaluated on the basis of actual

  5. Sparse Online Learning via Truncated Gradient

    Microsoft Academic Search

    John Langford; Lihong Li; Tong Zhang

    2008-01-01

    We propose a general method called truncated gradient to induce sparsity in the weights of online-learning algorithms with convex loss. This method has several essential properties. First, the degree of sparsity is continuous—a parameter con- trols the rate of sparsification from no sparsification to total sparsification. Second, the approach is theoretically motivated, and an instance of it can be regarded

  6. Natural equivalents of thermal gradient experiments

    NASA Astrophysics Data System (ADS)

    Rodríguez, Carmen; Geyer, Adelina; Castro, Antonio; Villaseñor, Antonio

    2015-06-01

    Crystallization experiments using the intrinsic thermal gradient in 10 mm length capsules loaded in piston-cylinder assemblies were used to investigate silicic magma crystallization. The application of experimental results to natural environments requires the scaling of physical parameters of petrological interest. Therefore, we propose here a comparative study between thermal gradients and numerical simulations of natural magma chambers. We use the Finite Element method to calculate thermal profiles across a cooling silicic magma chamber. These numerical profiles are compared with the intrinsic thermal structure of half-inch, piston-cylinder assemblies at 500 MPa. It is concluded that a set of varied magma chamber geometries and/or distinct stages of their cooling history can approach the intrinsic thermal structure of laboratory experiments. Once the thermal properties for magma and its host rock are fixed, the experimental-numerical approach is mostly dependent on the volume and aspect ratio of the magma chamber. Our results indicate, for instance, that a 10 mm length capsule with a thermal gradient of 40 °C/mm (from 1100 to 700 °C) may represent a 150-1100 m wide portion of a cooling magma chamber of 10-20 km diameter and 2-10 km height, emplaced at a depth of 18 km. Additional possible scenarios are represented by larger magma chambers, up to 30 km diameter, in which the experimental thermal gradient can represent a 150-3700 m-thin-section of the large igneous bodies.

  7. The effect of density gradients on hydrometers

    Microsoft Academic Search

    Martti Heinonen; Sampo Sillanpää

    2003-01-01

    Hydrometers are simple but effective instruments for measuring the density of liquids. In this work, we studied the effect of non-uniform density of liquid on a hydrometer reading. The effect induced by vertical temperature gradients was investigated theoretically and experimentally. A method for compensating for the effect mathematically was developed and tested with experimental data obtained with the MIKES hydrometer

  8. Histograms of Oriented Gradients for Human Detection

    Microsoft Academic Search

    Navneet Dalal; Bill Triggs

    2005-01-01

    We study the question of feature sets for robust visual ob- ject recognition, adopting linear SVM based human detec- tion as a test case. After reviewing existing edge and gra- dient based descriptors, we show experimentally that grids of Histograms of Oriented Gradient (HOG) descriptors sig- nicantly outperform existing feature sets for human detec- tion. We study the inuence of

  9. DISCONTINUOUS GRADIENT CONSTRAINTS AND THE INFINITY LAPLACIAN

    E-print Network

    Rossi, Julio D.

    DISCONTINUOUS GRADIENT CONSTRAINTS AND THE INFINITY LAPLACIAN PETRI JUUTINEN, MIKKO PARVIAINEN on , where is the infinity Laplace operator. We prove that this problem always has a solution that is unique -approximation need not coincide. 1. Introduction The infinity Laplacian, introduced by Aronsson [1] in 1960's

  10. Variance Reduction for Stochastic Gradient Optimization

    E-print Network

    Xing, Eric P.

    Variance Reduction for Stochastic Gradient Optimization Chong Wang Xi Chen Alex Smola Eric P. Xing models. Our approach builds on a variance reduction technique, which makes use of control variates [3 the general formulation and the theoretical property of variance reduction via control variates in stochastic

  11. On the Convergence of Decentralized Gradient Descent

    E-print Network

    Kun Yuan, Qing Ling, Wotao Yin

    2014-02-07

    We study the decentralized gradient descent method in which each agent i ... †W. Yin is with Department of Mathematics, University of California, Los .... The recent research interest in big data processing also motivates ...... these noise-polluted case to design either centralized [13] or decentralized basis pursuit algorithms.

  12. Controlling Thermal Gradients During Silicon Web Growth

    NASA Technical Reports Server (NTRS)

    Duncan, C. S.; Mchugh, J. P.; Skutch, M. E.; Piotrowski, P. A.

    1983-01-01

    Strategically placed slot helps to control critical thermal gradients in crucible for silicon web growth. Slot thermally isolates feed region of crucible from growth region; region where pellets are added stays hot. Heat absorbed by pellets during melting causes thermal unbalance than upsets growth conditions.

  13. Gradient domain editing of deforming mesh sequences

    Microsoft Academic Search

    Weiwei Xu; Kun Zhou; Yizhou Yu; Qifeng Tan; Qunsheng Peng; Baining Guo

    2007-01-01

    Many graphics applications, including computer games and 3D ani- mated films, make heavy use of deforming mesh sequences. In this paper, we generalize gradient domain editing to deforming mesh sequences. Our framework is keyframe based. Given sparse and ir- regularly distributed constraints at unevenly spaced keyframes, our solution first adjusts the meshes at the keyframes to satisfy these constraints, and

  14. Ballistic dispersion in temperature gradient focusing

    E-print Network

    Santiago, Juan G.

    Ballistic dispersion in temperature gradient focusing BY DAVID E. HUBER* AND JUAN G. SANTIAGO kinematic (or ballistic) dispersion. In most microfluidic systems, this dispersion regime is transient­Aris; ballistic; electroosmotic flow 1. Introduction Dispersion, the natural tendency for ordered molecules

  15. Carbon isotope gradients on early Paleozoic platforms

    NASA Astrophysics Data System (ADS)

    Holmden, C.

    2008-12-01

    Large positive ?13C excursions occur during sea level lowstands in the Ordovician and Silurian. In some cases, the sedimentary units hosting these excursions are stratigraphically equivalent to known glacial deposits. There has been considerable speculation on the significance of this linkage. Some workers view the inferred carbon cycle perturbations as evidence for a biotic response to the deteriorating climate, which may have invigorated thermohaline circulation and nutrient upwelling, thus increasing ocean productivity and organic carbon burial. Others believe that the excursions were driven by a positive shift in the isotope value of the global carbon weathering flux, reflecting increased weathering of calcareous sediments exposed by eustatic regressions. A closer examination of one of the excursion intervals, the Hirnantian, with examples from three basins on two paleocontinents, reveals a recurrent pattern: excursions in shallower nearshore settings are larger than deeper offshore ones. This implies shore-to-basin gradients in sedimentary ?13C, with values higher in nearshore settings. What gradients signify is a question that bears importantly on interpretations of carbon isotope records in ancient marine settings. If shelf sedimentary gradients reflect original seawater gradients in ?13C values, then local scale carbon cycling is implied, which profoundly affects the way that we 'read' carbon isotope signals in epeiric carbonate successions. In this talk, the evidence for carbon isotope gradients is reviewed, with particular emphasis on the Hirnantian sea level lowstand. A sea level driven, local scale, carbonate weathering model is presented that is consistent with shelf gradients. The main feature of the model is that sea level fluctuations, globally, cause adjustments in the isotope value of the carbonate weathering flux, locally, which in turn causes seawater ?13C values to increase in restricted nearshore settings of epeiric seas. If this interpretation of shelf gradients is correct, the model predicts that: (1) ocean ?13C changes are smaller than the largest excursions recorded in epeiric sea deposits, (2) ?13C excursions may behave like chemostratigraphic sea level curves, and (3) the global secular ?13C curve of seawater is overprinted by local scale carbon cycling processes in epeiric seas, and is unlikely to be a true representation of the ocean's secular evolution during the Paleozoic.

  16. Effects of predation risk across a latitudinal temperature gradient.

    PubMed

    Matassa, Catherine M; Trussell, Geoffrey C

    2015-03-01

    The nonconsumptive effects (NCEs) of predators on prey behavior and physiology can influence the structure and function of ecological communities. However, the strength of NCEs should depend on the physiological and environmental contexts in which prey must choose between food and safety. For ectotherms, temperature effects on metabolism and foraging rates may shape these choices, thereby altering NCE strength. We examined NCEs in a rocky intertidal food chain across a latitudinal sea surface temperature gradient within the Gulf of Maine. The NCEs of green crabs (Carcinus maenas) on the foraging, growth, and growth efficiency of prey snails (Nucella lapillus) were consistent across a broad (~8.5 °C) temperature range, even though snails that were transplanted south consumed twice as many mussels (Mytilus edulis) and grew twice as much as snails that were transplanted north. The positive effects of warmer temperatures in the south allowed snails under high risk to perform similarly to or better than snails under low risk at cooler temperatures. Our results suggest that for prey populations residing at temperatures below their thermal optimum, the positive effects of future warming may offset the negative effects of predation risk. Such effects may be favorable to prey populations facing increased predation rates due to warmer temperatures associated with climate change. Attention to the direct and indirect effects of temperature on species interactions should improve our ability to predict the effects of climate change on ecological communities. PMID:25433694

  17. A gradient field defeats the inherent repulsion between magnetic nanorods

    PubMed Central

    Gu, Yu; Burtovyy, Ruslan; Custer, John; Luzinov, Igor; Kornev, Konstantin G.

    2014-01-01

    When controlling the assembly of magnetic nanorods and chains of magnetic nanoparticles, it is extremely challenging to bring them together side by side while keeping a desired spacing between their axes. We show that this challenge can be successfully resolved by using a non-uniform magnetic field that defeats an inherent repulsion between nanorods. Nickel nanorods were suspended in a viscous film and a non-uniform field was used to control their placement. The in-plane movement of nanorods was tracked with a high-speed camera and a detailed image analysis was conducted to quantitatively characterize the behaviour of the nanorods. The analysis focused on the behaviour of a pair of neighbour nanorods, and a corresponding dynamic model was formulated and investigated. The complex two-dimensional dynamics of a nanorod pair was analysed analytically and numerically, and a phase portrait was constructed. Using this phase portrait, we classified the nanorod behaviour and revealed the experimental conditions in which nanorods could be placed side by side. Dependence of the distance between a pair of neighbour nanorods on physical parameters was analysed. With the aid of the proposed theory, one can build different lattices and control their spacing by applying different field gradients.

  18. Controlled mobility of unmanned aircraft chains to optimize network capacity in realistic communication environments

    NASA Astrophysics Data System (ADS)

    Dixon, Cory

    This dissertation presents a decentralized gradient-based mobility control algorithm for the formation and maintenance of an optimal end-to-end communication chain using a team of unmanned aircraft acting as communication relays. With the use of unmanned aircraft (UA) as communication relays, a common mode of operation is to form a communication relay chain between a lead exploring node (which may be ground based or another UA) and a control station. In this type of operation the lead node is typically deployed to explore (sense) a remote region of interest that is beyond direct radio frequency (RF) communication range, or out of line-of-sight, to the control station. To provide non-line-of-sight service, and extend the communication range of the lead node, unmanned aircraft acting as communication relays are deployed in a convoy fashion behind the lead vehicle to form a cascaded relay chain. The focus of this work is the use of the mobility of a fixed number of relay aircraft to maximize the capacity of a directed communication chain from a source node to a destination node. Local objective functions are presented that use the signal-to-noise-and-interference ratio (SNIR) of neighbor communication links as inputs to maximize the end-to-end capacity of packet-based and repeater-type network chains. An adaptive gradient-based SNIR controller using the local objective function can show significant improvement in the capacity of the communication chain that is not possible with range-based controllers, or static deployment strategies, in RF environments containing unknown localized noise sources and terrain effects. Since the SNIR field is unknown, an online estimate of the SNIR field gradient is formed using methods of Stochastic Approximation from the orbital motion of the aircraft tracking a control point. Flight demonstrations using the Networked Unmanned Aircraft System Command, Control and Communications testbed were conducted to validate the controller presented herein. Results from flight experiments show that mobility of unmanned aircraft, following locally estimated SNIR gradients, can be used to form a locally optimized communication chain by driving the aircraft to locations that improve the end-to-end capacity of the chain over that of a range-based controller or a static deployment algorithm.

  19. Pharmaceutical Supply Chain Networks with Outsourcing

    E-print Network

    Nagurney, Anna

    Pharmaceutical Supply Chain Networks with Outsourcing Under Price and Quality Competition Anna Amherst Pharmaceutical Supply Chain Networks with Outsourcing #12;Acknowledgments This research Supply Chain Networks with Outsourcing #12;This presentation is based on the paper: Nagurney, A., Li, D

  20. Thermocapillary migration of a small chain of bubbles

    NASA Technical Reports Server (NTRS)

    Wei, Huailiang; Subramanian, R. S.

    1993-01-01

    The quasistatic thermocapillary migration of a chain of two or three spherical bubbles in an unbounded fluid possessing a uniform temperature gradient is investigated in the limit of vanishing Reynolds and Peclet numbers. The line of bubble centers is permitted to be either parallel or perpendicular to the direction of the undisturbed temperature gradient. The governing equations are solved by a truncated-series, boundary-collocation technique. Results are presented which demonstrate the impact of the presence of other bubbles on a test bubble. In the three-bubble case, a simple pairwise-additive approximation is constructed from the reflections solution, and found to perform well except when the bubbles are close to each other. Also, features of the flow topology in the fluid are explored. Separated reverse flow wakes are found in the axisymmetric problem, and other interesting structures are noted for the case in which the line of centers is perpendicular to the applied temperature gradient. The observed flow structure is shown to be the result of superposition of simpler basic flows.

  1. Improve supply chain resilience by multi-stage supply chain

    E-print Network

    Xu, Jie, M. Eng. Massachusetts Institute of Technology

    2009-01-01

    Due to the global expansion of Company A's supply chain network, it is becoming more vulnerable to many disruptions. These disruptions often incur additional costs; and require time to respond to and recover from these ...

  2. Improving supply chain resilience by multi-stage supply chain

    E-print Network

    Yang, Jingxia, M. Eng, Massachusetts Institute of Technology

    2009-01-01

    Due to the global expansion of Company A's supply chain network, it is becoming more vulnerable to many disruptions. These disruptions often incur additional costs; and require time to respond to and recover from these ...

  3. Internet-Enabled Supply ChainsInternet-Enabled Supply Chains Quan Z. Sheng, University of Adelaide

    E-print Network

    Sheng, Michael

    89 Internet-Enabled Supply ChainsInternet-Enabled Supply Chains Quan Z. Sheng, University of the Internet-enabled Supply Chain 89 Key Supply Chain Processes and the Internet 89 Impacts of Internet-Enabled Supply Chains 92 Enabling Technologies for Internet-Enabled Supply Chain Management 92 Internet-based EDI

  4. Food Chain Security and Vulnerability

    NASA Astrophysics Data System (ADS)

    Brunet, Sébastien; Delvenne, Pierre; Claisse, Frédéric

    In our contemporary societies, the food chain could be defined as a macro-technical system, which depends on a wide variety of actors and risks analysis methods. In this contribution, risks related to the food chain are defined in terms of "modern risks" (Beck 1992). The whole national economic sector of food production/distribution is vulnerable to a local accident, which can affect the functioning of food chain, the export programs and even the political system. Such a complex socio-technical environment is undoubtedly vulnerable to intentional act such as terrorism.

  5. Tuning Surface Microstructure and Gradient Property of Polymer by Photopolymerizable Polysiloxane-modified Nanogels

    PubMed Central

    Chen, Cong; Liu, JianCheng; Sun, Fang; Stansbury, Jeffrey W.

    2014-01-01

    This paper reports a series of photopolymerizable polysiloxane-modified nanogels for regulating surface microstructure and gradient property of polymers, which were synthesized by solution polymerization under different feed ratios of a methacrylate-modified polysiloxane, urethane dimethacrylate (UDMA) and isobornyl methacrylate (IBMA) in the presence of a thiol chain transfer agent. The nanogel structure and composition were characterized by proton nuclear magnetic resonance (1H-NMR), Fourier transform-infrared spectroscopy (FT-IR), transmission electron microscope (TEM), gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). The dispersion of these nanogels in triethylene glycol dimethacrylate (TEGDMA) can reduce the onset and magnitude of shrinkage stress during polymerization without compromise to mechanical properties of the resulting polymers. Most importantly, as demonstrated by elemental analysis and X-ray photoelectron spectroscopy (XPS), the nanogels exhibit good self-floating ability in the monomer/polymer matrix and the increase of polysiloxane content in the nanogel can enhance the self-floating capability due to the lower surface tension and energy associated with the polysiloxane component. As a result, the polysiloxane-modified nanogels can spontaneously form a concentration gradient that can be locked in upon photopolymerization leading to a well-controlled heterogeneous polymer that presents a gradient change in thermal stability. With the increase of polysiloxane content, the thermal stability of the polymer was improved significantly. Furthermore, the enrichment of the nanogel on the surface resulting from the good self-floating ability can reduce the dispersion surface energy of gradient polymer film and generate a more hydrophobic surface with altered surface microstructure. These photopolymerizable polysiloxane-modified nanogels are demonstrated to have potential broad application in the preparation of gradient polymer with controlled surface properties. PMID:25045518

  6. Neurofilament light chain

    PubMed Central

    Lu, Ching-Hua; Macdonald-Wallis, Corrie; Gray, Elizabeth; Pearce, Neil; Petzold, Axel; Norgren, Niklas; Giovannoni, Gavin; Fratta, Pietro; Sidle, Katie; Fish, Mark; Orrell, Richard; Howard, Robin; Talbot, Kevin; Greensmith, Linda; Kuhle, Jens

    2015-01-01

    Objective: To test blood and CSF neurofilament light chain (NfL) levels in relation to disease progression and survival in amyotrophic lateral sclerosis (ALS). Methods: Using an electrochemiluminescence immunoassay, NfL levels were measured in samples from 2 cohorts of patients with sporadic ALS and healthy controls, recruited in London (ALS/control, plasma: n = 103/42) and Oxford (ALS/control, serum: n = 64/36; paired CSF: n = 38/20). NfL levels in patients were measured at regular intervals for up to 3 years. Change in ALS Functional Rating Scale–Revised score was used to assess disease progression. Survival was evaluated using Cox regression and Kaplan–Meier analysis. Results: CSF, serum, and plasma NfL discriminated patients with ALS from healthy controls with high sensitivity (97%, 89%, 90%, respectively) and specificity (95%, 75%, 71%, respectively). CSF NfL was highly correlated with serum levels (r = 0.78, p < 0.0001). Blood NfL levels were approximately 4 times as high in patients with ALS compared with controls in both cohorts, and maintained a relatively constant expression during follow-up. Blood NfL levels at recruitment were strong, independent predictors of survival. The highest tertile of blood NfL at baseline had a mortality hazard ratio of 3.91 (95% confidence interval 1.98–7.94, p < 0.001). Conclusion: Blood-derived NfL level is an easily accessible biomarker with prognostic value in ALS. The individually relatively stable levels longitudinally offer potential for NfL as a pharmacodynamic biomarker in future therapeutic trials. Classification of evidence: This report provides Class III evidence that the NfL electrochemiluminescence immunoassay accurately distinguishes patients with sporadic ALS from healthy controls. PMID:25934855

  7. Cross-term-compensated pulsed-gradient stimulated echo MR with asymmetric gradient pulse lengths

    NASA Astrophysics Data System (ADS)

    Finsterbusch, Jürgen

    2008-07-01

    The magic asymmetric gradient stimulated echo (MAGSTE) sequence developed to compensate background-gradient cross-terms in the preparation and readout interval independently, assumes identical lengths for the two gradient pulses applied in each interval. However, this approach is rather inefficient if some extra delay time is present in one half of an interval, e.g. as required for special RF excitations or spatial encoding prior to the stimulated echo in MR imaging. Therefore, a generalized version of the sequence is presented that considers different gradient pulse lengths within an interval. It is shown theoretically that (i) for any pulse lengths a "magic" amplitude ratio exists which ensures the desired cross-term compensation in each interval and that (ii) prolonging one of the gradients can deliver a considerably higher diffusion weighting efficiency. These results are confirmed in MR imaging experiments on phantoms and in vivo in the human brain at 3 T using an echo-planar trajectory. In the examples shown, typically 10 times higher b values can be achieved or an echo time reduction with a 40% signal gain in brain white matter. Thus, in case of asymmetric timing requirements, the generalized MAGSTE sequence with different gradient pulse lengths may help to overcome signal-to-noise limitations in diffusion weighted MR.

  8. Food Chains and Food Webs

    NSDL National Science Digital Library

    2012-06-14

    This lesson explains how energy travels through an ecosystem. This flow can be diagrammed in food chains and food webs as shown in the lesson's illustrations. Key terms are hyperlinked so students can easily view definitions of new concepts.

  9. Bibliometric Application of Markov Chains.

    ERIC Educational Resources Information Center

    Pao, Miranda Lee; McCreery, Laurie

    1986-01-01

    A rudimentary description of Markov Chains is presented in order to introduce its use to describe and to predict authors' movements among subareas of the discipline of ethnomusicology. Other possible applications are suggested. (Author)

  10. Effective contracts in supply chains

    E-print Network

    Shum, Wanhang

    2007-01-01

    In the past decade, we have seen significant increase in the level of outsourcing in many industries. This increase in the level of outsourcing increases the importance of implementing effective contracts in supply chains. ...

  11. Application of Foundation Fieldbus Technology in Chain Grate Boiler Automation Control System

    Microsoft Academic Search

    Liang Geng; Bai Yan

    2007-01-01

    Full and thorough distributed automation control sited in fields is implemented for a large enterprise of heat-supply by grate chain boilers with Foundation Fieldbus technology. The main content for the design of the system includes the control plan for the key parameters of the system etc..The control of water level and combustion sub-system are realized. Gradient method is adopted in

  12. Bioenergy supply chains and stakeholders

    Microsoft Academic Search

    Stefan Gold

    2011-01-01

    What are the management challenges and opportunities of bio-energy chains for both running their business efficiently and\\u000a effectively and fostering the relationships with most relevant external stakeholders? This question is approached by systematically\\u000a reviewing papers at the interface of bio-energy and supply chain or logistics issues. The review conducted as content analysis\\u000a is based on an analytic framework that conceives

  13. Able image chain analysis. Revision

    NASA Astrophysics Data System (ADS)

    Zelenka, J.

    1980-08-01

    This report seeks to help in establishing Advanced Building Block for Large Area Exploitation system image chain elements, the ABLE data flow, and ABLE interface and test requirements. The document also reviews critical ABLE image chain problem areas, including image sampling requirements, radar image quantization, radar image compression techniques (DPCM, MAPS, etc.), and radar image data display requirements for both hard and soft copy devices.

  14. LifeSaving Supply Chains

    Microsoft Academic Search

    Anisya Thomas; Laura Rock Kopczak

    There is a great need to improve the world’s supply chains for disaster relief. This paper provides background on the current\\u000a state of logistics in the humanitarian environment and the factors that have limited the evolution of knowledge and the performance\\u000a of humanitariansupply chains. We consider the external pressures thet aid agencies (AA) are feeling from donors, local aid\\u000a agencies,

  15. Supply Chain Engineering and Automation

    Microsoft Academic Search

    Nukala Viswanadham

    2000-01-01

    Integrated supply chains are networks of companies in alliance sharing the same destiny for mutual business advantage. In such networks, end-to-end material and information flows-from raw material production to retailer sales-are optimally and collaboratively managed to create value to the customers and other stakeholders. We first introduce the configuration and physics of integrated supply chain networks (ISNs) and identify the

  16. Elastic properties of magnetosome chains

    NASA Astrophysics Data System (ADS)

    Kiani, Bahareh; Faivre, Damien; Klumpp, Stefan

    2015-04-01

    Magnetotactic bacteria swim and orient in the direction of a magnetic field thanks to the magnetosome chain, a cellular ‘compass needle’ that consists of a string of vesicle-enclosed magnetic nanoparticles aligned on a cytoskeletal filament. Here we investigate the mechanical properties of such a chain, in particular the bending stiffness. We determine the contribution of magnetic interactions to the bending stiffness and the persistence length of the chain. This contribution is comparable to, but typically smaller than the contribution of the semiflexible filament. For a chain of magnetic nanoparticles without a semiflexible filament, the linear configuration is typically metastable and the lowest energy structures are closed chains (flux closure rings) without a net magnetic moment that are thus not functional as a cellular compass. Our calculations show that the presence of the cytoskeletal filament stabilizes the chain against ring closure, either thermodynamically or kinetically, depending on the stiffness of the filament, confirming that such stabilization is one of the roles of this structure in these bacterial cells.

  17. Gradient Modification of Fingerprint Images using Fingerpint Area and Contour

    Microsoft Academic Search

    Hideyo Takeuchi; Masahiro Hoguro; Noriyuki Matsumoto; Taizo Umezaki

    2007-01-01

    In this paper, we propose the way to modify gradient of fingerprint images. We modify the gradient using fingerprint area and contour, without extracting end points or bifurcation points called ``minutia\\

  18. Weighted Graph Based Ordering Techniques for Preconditioned Conjugate Gradient Methods

    E-print Network

    Waterloo, University of

    Weighted Graph Based Ordering Techniques for Preconditioned Conjugate Gradient Methods Simon S: Preconditioned conjugate gradient, preconditioner, matrixordering, weighted graph Running Title: Weighted Graph's University, Kingston, Ontario. 1 #12;2 Weighted Graph Ordering for PCG Methods 1 Introduction Preconditioned

  19. Non-singular dislocation loops in gradient elasticity

    NASA Astrophysics Data System (ADS)

    Lazar, Markus

    2012-04-01

    Using gradient elasticity, we give in this Letter the non-singular fields produced by arbitrary dislocation loops in isotropic media. We present the ‘modified’ Mura, Peach-Koehler and Burgers formulae in the framework of gradient elasticity theory.

  20. Vertebrate metacommunity structure along an extensive elevational gradient

    E-print Network

    Willig, Michael

    RESEARCH PAPER Vertebrate metacommunity structure along an extensive elevational gradient of three vertebrate orders (Chiroptera, Rodentia and Passeriformes) along an extensive elevational gradient. Using elevation as a proxy for variation in abiotic characteristics and the known elevational

  1. Novel geometry gradient coils for MRI designed by genetic algorithm

    E-print Network

    Williams, Guy Barnett

    2001-06-19

    This thesis concerns the design of gradient coils for magnetic resonance imaging systems. The method of design by genetic algorithm optimisation is applied to novel gradient geometries both by use of conventional computer facilities, and...

  2. Accelerating Stochastic Gradient Descent using Predictive Variance Reduction

    E-print Network

    Johnson, Rie

    Accelerating Stochastic Gradient Descent using Predictive Variance Reduction Rie Johnson RJ variance reduction method for stochastic gradient descent which we call stochastic variance reduced convergence asymptotically due to the inherent variance. To remedy this prob- lem, we introduce an explicit

  3. Slow neutron distribution in a temperature gradient

    SciTech Connect

    Molinari, V.G.; Pollachini, L.

    1985-12-01

    A set of equations that describes the diffusion of thermal neutrons is obtained from the energy-dependent Boltzmann equation. These equations are analogous to the phenomenological laws of the thermodynamic theory of irreversible processes and show, for instance, that as a temperatur gradient produces a neutron current (Soret effect), a density gradient yields an energy flow (Dufour effect). The method is applied to the ''two-temperature problem'' in order to gain better insight into the thermal diffusion phenomenon. The thermal diffusion of neutrons is shown to strongly depend on the scattering law of the two media where neutrons diffuse, and it is determined that some of the conclusions previously obtained are valid only for the case of a heavy gas moderator with the scat tering cross section independent of the energy.

  4. Anisotropic gradients in the upper mantle

    SciTech Connect

    Garmany, J.

    1981-09-01

    Pn amplitudes in some widely spaced sets of orthogonal marine refraction lines on young oceanic crust are greater in the fast direction than in the slow direction. This is inconsistent with the predicted amplitude behavior for simple head waves, but can be explained by an increase in anisotropy with depth. It appears that these gradients are due to increasing olivine crystal orientation, although changes in the relative abundance of two anisotropic minerals without variable tectonization could also account for the observations. Depth variation of tectonization most probably indicates very high temperature gradients at the Moho. This would imply a substantial amount of convective heat transport in the whole oceanic crust near mid-ocean rises.

  5. Enhanced gradient for training restricted Boltzmann machines.

    PubMed

    Cho, Kyunghyun; Raiko, Tapani; Ilin, Alexander

    2013-03-01

    Restricted Boltzmann machines (RBMs) are often used as building blocks in greedy learning of deep networks. However, training this simple model can be laborious. Traditional learning algorithms often converge only with the right choice of metaparameters that specify, for example, learning rate scheduling and the scale of the initial weights. They are also sensitive to specific data representation. An equivalent RBM can be obtained by flipping some bits and changing the weights and biases accordingly, but traditional learning rules are not invariant to such transformations. Without careful tuning of these training settings, traditional algorithms can easily get stuck or even diverge. In this letter, we present an enhanced gradient that is derived to be invariant to bit-flipping transformations. We experimentally show that the enhanced gradient yields more stable training of RBMs both when used with a fixed learning rate and an adaptive one. PMID:23148412

  6. Gradient Moment Compensated Magnetic Resonance Spectroscopic Imaging

    PubMed Central

    Kim, Dong-Hyun; Gu, Meng; Spielman, Daniel M.

    2010-01-01

    Spectroscopic imaging applications outside of the brain can suffer from artifacts due to inherent long scan times and susceptibility to motion. A fast spectroscopic imaging sequence has been devised with reduced sensitivity to motion. The sequence uses oscillating readout gradients and acquires k-space data in a spiral out–in fashion, which allows fast k-space coverage. We show that a spiral out–in readout acquisition is characterized by small gradient moments, reducing sensitivity to motion-induced artifacts. Data are acquired comparing the sequence to normal phase encoded spectroscopic imaging and conventional spiral spectroscopic imaging protocols. In addition, in vivo data are acquired from the liver, demonstrating potential usage as a multivoxel fat/water spectroscopic imaging tool. Results indicate that in the presence of motion, ghosting effects are reduced while metabolite signal increases of approximately 10% can be achieved. PMID:19161164

  7. The latitudinal biodiversity gradient through deep time.

    PubMed

    Mannion, Philip D; Upchurch, Paul; Benson, Roger B J; Goswami, Anjali

    2014-01-01

    Today, biodiversity decreases from equatorial to polar regions. This is a fundamental pattern governing the distribution of extant organisms, the understanding of which is critical to predicting climatically driven biodiversity loss. However, its causes remain unresolved. The fossil record offers a unique perspective on the evolution of this latitudinal biodiversity gradient (LBG), providing a dynamic system in which to explore spatiotemporal diversity fluctuations. Deep-time studies indicate that a tropical peak and poleward decline in species diversity has not been a persistent pattern throughout the Phanerozoic, but is restricted to intervals of the Palaeozoic and the past 30 million years. A tropical peak might characterise cold icehouse climatic regimes, whereas warmer greenhouse regimes display temperate diversity peaks or flattened gradients. PMID:24139126

  8. Program predicts reservoir temperature and geothermal gradient

    SciTech Connect

    Kutasov, I.M.

    1992-06-01

    This paper reports that a Fortran computer program has been developed to determine static formation temperatures (SFT) and geothermal gradient (GG). A minimum of input data (only two shut-in temperature logs) is required to obtain the values of SFT and GG. Modeling of primary oil production and designing enhanced oil recovery (EOR) projects requires knowing the undisturbed (static) reservoir temperature. Furthermore, the bottom hole circulating temperature (BHCT) is an important factor affecting a cement's thickening time, rheological properties, compressive strength, development, and set time. To estimate the values of BHCT, the geothermal gradient should be determined with accuracy. Recently we obtained an approximate analytical solution which describes the shut-in temperature behavior.

  9. Dynamic directional gradient vector flow for snakes.

    PubMed

    Cheng, Jierong; Foo, Say Wei

    2006-06-01

    Snakes, or active contour models, have been widely used in image segmentation. However, most present snake models do not discern between positive and negative step edges. In this paper, a new type of dynamic external force for snakes named dynamic directional gradient vector flow (DDGVF) is proposed that uses this information for better performance. It makes use of the gradients in both x and y directions and deals with the external force field for the two directions separately. In snake deformation, the DDGVF field is utilized dynamically according to the orientation of snake in each iteration. Experimental results demonstrate that the DDGVF snake provides a much better segmentation than GVF snake in situations when edges of different directions are present which pose confusion for segmentation. PMID:16764281

  10. Combining search directions using gradient flows

    Microsoft Academic Search

    Javier M. Moguerza; Francisco J. Prieto

    2003-01-01

    .  ?The efficient combination of directions is a significant problem in line search methods that either use negative curvature,\\u000a or wish to include additional information such as the gradient or different approximations to the Newton direction. \\u000a \\u000a In this paper we describe a new procedure to combine several of these directions within an interior-point primal-dual algorithm.\\u000a Basically, we combine in an efficient

  11. Cosmic ray gradients in the outer heliosphere

    NASA Technical Reports Server (NTRS)

    Fillius, W.; Wake, B.; Ip, W.-H.; Axford, I.

    1983-01-01

    Launched in 1972 and 1973 respectively, the Pioneer 10 and 11 spacecraft are now probing the outer heliosphere on their final escape from the sun. The data in this paper extend for almost an entire solar cycle from launch to early 1983, when Pioneer 10 was at a heliocentric distance of 29 AU and Pioneer 11, 13 AU. The UCSD instruments on board were used to study the gradient, and to look at the time and spatial variations of the cosmic ray intensities.

  12. Quantized Concentration Gradient in Picoliter Scale

    NASA Astrophysics Data System (ADS)

    Hong, Jong Wook

    2010-10-01

    Generation of concentration gradient is of paramount importance in the success of reactions for cell biology, molecular biology, biochemistry, drug-discovery, chemotaxis, cell culture, biomaterials synthesis, and tissue engineering. In conventional method of conducting reactions, the concentration gradients is achieved by using pipettes, test tubes, 96-well assay plates, and robotic systems. Conventional methods require milliliter or microliter volumes of samples for typical experiments with multiple and sequential reactions. It is a challenge to carry out experiments with precious samples that have strict limitations with the amount of samples or the price to pay for the amount. In order to overcome this challenge faced by the conventional methods, fluidic devices with micrometer scale channels have been developed. These devices, however, cause restrictions on changing the concentration due to the fixed gradient set based on fixed fluidic channels.ootnotetextJambovane, S.; Duin, E. C.; Kim, S-K.; Hong, J. W., Determination of Kinetic Parameters, KM and kcat, with a Single Experiment on a Chip. textitAnalytical Chemistry, 81, (9), 3239-3245, 2009.^,ootnotetextJambovane, S.; Hong, J. W., Lorenz-like Chatotic System on a Chip In The 14th International Conference on Miniaturized Systems for Chemistry and Life Sciences (MicroTAS), The Netherlands, October, 2010. Here, we present a unique microfluidic system that can generate quantized concentration gradient by using series of droplets generated by a mechanical valve based injection method.ootnotetextJambovane, S.; Rho, H.; Hong, J., Fluidic Circuit based Predictive Model of Microdroplet Generation through Mechanical Cutting. In ASME International Mechanical Engineering Congress & Exposition, Lake Buena Vista, Florida, USA, October, 2009.^,ootnotetextLee, W.; Jambovane, S.; Kim, D.; Hong, J., Predictive Model on Micro Droplet Generation through Mechanical Cutting. Microfluidics and Nanofluidics, 7, (3), 431-438, 2009. Acknowledgement: All this work has been done by Sachin Jambovane, Kirn Cramer, Woon Seob Lee, and Hoon Suk Rho. The presenter would like to thank them.

  13. Parametric study of salt gradient solar ponds

    SciTech Connect

    Beniwal, R.S.; Saxena, N.S.; Bhandari, R.C.

    1986-02-01

    A mathematical model for efficiency of a salt gradient solar pond is described. Heat losses from the bottom of the pond have been calculated, and the results for the effective thermal conductivity with the thicknesses of various insulating materials have been presented. The effect of the ground thermal resistance on the efficiency of the pond for different values of ..delta..T/S/sup 0/ are also shown.

  14. M-step preconditioned conjugate gradient methods

    NASA Technical Reports Server (NTRS)

    Adams, L.

    1983-01-01

    Preconditioned conjugate gradient methods for solving sparse symmetric and positive finite systems of linear equations are described. Necessary and sufficient conditions are given for when these preconditioners can be used and an analysis of their effectiveness is given. Efficient computer implementations of these methods are discussed and results on the CYBER 203 and the Finite Element Machine under construction at NASA Langley Research Center are included.

  15. Predicting global overturning from meridional density gradients

    NASA Astrophysics Data System (ADS)

    Butler, Edward; Oliver, Kevin; Hirschi, Joel

    2015-04-01

    Numerous attempts have been made to scale the strength of the meridional overturning circulation (MOC), principally in the North Atlantic, with large-scale, basin-wide hydrographic properties. In particular, various approaches to scaling the MOC with meridional density gradients have been proposed, but the success of these has only been demonstrated under limited conditions. Here we present a scaling relationship linking overturning to twice vertically-integrated meridional density gradients via the hydrostatic equation and a "rotated" form of the geostrophic equation. This provides a meridional overturning streamfunction as a function of depth for each basin. Using a series of periodically forced experiments in a global, coarse resolution configuration of the general circulation model NEMO, we explore the timescales over which this scaling is temporally valid. We find that the scaling holds well in the upper Atlantic cell (at 1000m) on decadal and longer timescales, explaining at least 94% of overturning variance for timescales of 128 to 2048 years and accurately predicting the relative magnitude of the response for different frequencies. Despite the highly nonlinear response of the Antarctic cell in the abyssal Atlantic, over 77% of the observed variability at 4000m is predicted on timescales of 32 years and longer. The scaling law is also successful in the Indo-Pacific, thus demonstrating its generality. This analysis is extended to a higher resolution, stochastically forced simulation for which correlations of at least 0.79 are obtained with upper Atlantic MOC variance on all timescales greater than 25 years. These results demonstrate that meridional density gradients and overturning are linked via meridional pressure gradients, and that both the strength and structure of the MOC can be predicted from hydrography on multi-decadal and longer timescales provided that the link is made in this way.

  16. Gradient Descent and Radial Basis Functions

    Microsoft Academic Search

    Mercedes Fernández-redondo; Joaquín Torres-sospedra; Carlos Hernández-espinosa

    2006-01-01

    \\u000a In this paper, we present experiments comparing different training algorithms for Radial Basis Functions (RBF) neural networks.\\u000a In particular we compare the classical training which consists of an unsupervised training of centers followed by a supervised\\u000a training of the weights at the output, with the full supervised training by gradient descent proposed recently in same papers.\\u000a We conclude that a

  17. High gradient accelerators for linear light sources

    SciTech Connect

    Barletta, W.A.

    1988-09-26

    Ultra-high gradient radio frequency linacs powered by relativistic klystrons appear to be able to provide compact sources of radiation at XUV and soft x-ray wavelengths with a duration of 1 picosecond or less. This paper provides a tutorial review of the physics applicable to scaling the present experience of the accelerator community to the regime applicable to compact linear light sources. 22 refs., 11 figs., 21 tabs.

  18. Measuring the vertical gradient of gravity

    NSDL National Science Digital Library

    Rob Sternberg

    The free-air effect tells us that as elevation above sea level increases, gravitational acceleration g decreases at the rate of about 0.3086 mgal/meter. This effect is routinely corrected for when making gravity surveys. We will use the LaCoste & Romberg gravimeter to measure the free-air effect in a tall building on campus, and compare with the theoretical value. keywords: gravity; vertical gradient; gravimeter

  19. Crystalline-gradient polycarbonates prepared from enantioselective terpolymerization of meso-epoxides with CO2.

    PubMed

    Liu, Ye; Ren, Wei-Min; He, Ke-Ke; Lu, Xiao-Bing

    2014-01-01

    The development of efficient processes for CO2 transformation into useful products is a long-standing goal for chemists, since CO2 is an abundant, inexpensive and non-toxic renewable C1 resource. Here we describe the enantioselective copolymerization of 3,4-epoxytetrahydrofuran with CO2 mediated by biphenol-linked dinuclear cobalt complex, affording the corresponding polycarbonate with >99% carbonate linkages and excellent enantioselectivity (up to 99% enantiomeric excess). Notably, the resultant isotactic polycarbonate is a typical semicrystalline polymer, possessing a melting point of 271?°C. Furthermore, the enantioselective terpolymerization of 3,4-epoxytetrahydrofuran, cyclopentene oxide and CO2 mediated by this dinuclear cobalt complex gives novel gradient polycarbonates, in which the decrement of one component and the increment of the other component occur sequentially from one chain end to the other end. The resultant terpolymers show perfectly isotactic structure and have unique crystalline-gradient nature, in which the crystallinity continuously varies along the main chain. PMID:25477252

  20. Supply chain integration, information sharing and supply chain visibility-the remedy for supply chain uncertainty in australian organisations

    Microsoft Academic Search

    Kumaraguru Mahadevan; Premaratne Samaranayake; Kenan Matawie

    2010-01-01

    The aim of this paper is to examine the current practices in supply chain management (SCM), in terms of supply chain integration (SCI), supply chain visibility (SCV) and information sharing (IS) among supply chain (SC) partners. The paper presents key areas of interests, in particular some of the SC uncertainties and risks faced by organizations; and state of play of

  1. Cationic triple-chain amphiphiles facilitate vesicle fusion compared to double-chain or single-chain analogues

    E-print Network

    Smith, Bradley D.

    Cationic triple-chain amphiphiles facilitate vesicle fusion compared to double-chain or single, triple-chain amphiphiles promote vesicle fusion more than structurally related double-chain or single and acid-triggered self-fusion of vesicles composed of cationic amphiphile and anionic cholesteryl

  2. Color and population gradients in globular cluster cores

    NASA Technical Reports Server (NTRS)

    Djorgovski, S.; Piotto, Giampaolo; King, Ivan R.

    1989-01-01

    New observational results on color and population gradients in the cores of several highly concentrated globular clusters are reported. The gradients are in the sense of blueing toward the cluster center, and appear to be caused mostly or entirely by population gradients in the number of blue horizontal branch and red giant branch stars. Taken at face value, such gradients would imply an inverse mass segregation, but this interpretation is not fully secure. In any case, their dynamical understanding remains a problem.

  3. Metal artifacts caused by gradient switching.

    PubMed

    Graf, Hansjörg; Steidle, Günter; Martirosian, Petros; Lauer, Ulrike A; Schick, Fritz

    2005-07-01

    In metal parts, e.g., implants or instruments, eddy currents can be induced from gradient switching if positioned off-center inside the MR scanner. For the first time, a systematic analysis of related artifacts was performed. Current strength increases in conjunction with increasing size of the part, increasing electrical conductivity, distance from isocenter, and increasing gradient strengths. A xy-plane oriented copper ring (d(o) = 20 mm, d(i) = 15 mm, 2 mm thick) was examined at isocenter and at x = 15 cm, y = z = 0. Comparisons of xy-, xz-, and yz-slices, recorded for both possibilities to select encoding directions, revealed effects from ramp-down of the slice-selection and ramp-up of the read-out gradient. Near the metal part, temporary inhomogeneities were superimposed to the static field and spin-dephasing signal loss resulted, despite using spin-echo technique. Artifacts depended on excitation and read-out bandwidth. For an equivalent titanium ring, conductivity related effects could not be ascertained but distinct susceptibility effects occurred. MR compatibility of implants/instruments therefore requires both low susceptibility and low conductivity. PMID:15968663

  4. Crosswind Shear Gradient Affect on Wake Vortices

    NASA Technical Reports Server (NTRS)

    Proctor, Fred H.; Ahmad, Nashat N.

    2011-01-01

    Parametric simulations with a Large Eddy Simulation (LES) model are used to explore the influence of crosswind shear on aircraft wake vortices. Previous studies based on field measurements, laboratory experiments, as well as LES, have shown that the vertical gradient of crosswind shear, i.e. the second vertical derivative of the environmental crosswind, can influence wake vortex transport. The presence of nonlinear vertical shear of the crosswind velocity can reduce the descent rate, causing a wake vortex pair to tilt and change in its lateral separation. The LES parametric studies confirm that the vertical gradient of crosswind shear does influence vortex trajectories. The parametric results also show that vortex decay from the effects of shear are complex since the crosswind shear, along with the vertical gradient of crosswind shear, can affect whether the lateral separation between wake vortices is increased or decreased. If the separation is decreased, the vortex linking time is decreased, and a more rapid decay of wake vortex circulation occurs. If the separation is increased, the time to link is increased, and at least one of the vortices of the vortex pair may have a longer life time than in the case without shear. In some cases, the wake vortices may never link.

  5. Integrated calibration of magnetic gradient tensor system

    NASA Astrophysics Data System (ADS)

    Gang, Yin; Yingtang, Zhang; Hongbo, Fan; GuoQuan, Ren; Zhining, Li

    2015-01-01

    Measurement precision of a magnetic gradient tensor system is not only connected with the imperfect performance of magnetometers such as bias, scale factor, non-orthogonality and misalignment errors, but also connected with the external soft-iron and hard-iron magnetic distortion fields when the system is used as a strapdown device. So an integrated scalar calibration method is proposed in this paper. In the first step, a mathematical model for scalar calibration of a single three-axis magnetometer is established, and a least squares ellipsoid fitting algorithm is proposed to estimate the detailed error parameters. For the misalignment errors existing at different magnetometers caused by the installation process and misalignment errors aroused by ellipsoid fitting estimation, a calibration method for combined misalignment errors is proposed in the second step to switch outputs of different magnetometers into the ideal reference orthogonal coordinate system. In order to verify effectiveness of the proposed method, simulation and experiment with a cross-magnetic gradient tensor system are performed, and the results show that the proposed method estimates error parameters and improves the measurement accuracy of magnetic gradient tensor greatly.

  6. Pedestrian Detection Using Gradient Local Binary Patterns

    NASA Astrophysics Data System (ADS)

    Jiang, Ning; Xu, Jiu; Goto, Satoshi

    In recent years, local pattern based features have attracted increasing interest in object detection and recognition systems. Local Binary Pattern (LBP) feature is widely used in texture classification and face detection. But the original definition of LBP is not suitable for human detection. In this paper, we propose a novel feature named gradient local binary patterns (GLBP) for human detection. In this feature, original 256 local binary patterns are reduced to 56 patterns. These 56 patterns named uniform patterns are used for generating a 56-bin histogram. And gradient value of each pixel is set as the weight which is always same in LBP based features in histogram calculation to computing the values in 56 bins for histogram. Experiments are performed on INRIA dataset, which shows the proposal GLBP feature is discriminative than histogram of orientated gradient (HOG), Semantic Local Binary Patterns (S-LBP) and histogram of template (HOT). In our experiments, the window size is fixed. That means the performance can be improved by boosting methods. And the computation of GLBP feature is parallel, which make it easy for hardware acceleration. These factors make GLBP feature possible for real-time pedestrian detection.

  7. Efficient gradient computation for dynamical models.

    PubMed

    Sengupta, B; Friston, K J; Penny, W D

    2014-09-01

    Data assimilation is a fundamental issue that arises across many scales in neuroscience - ranging from the study of single neurons using single electrode recordings to the interaction of thousands of neurons using fMRI. Data assimilation involves inverting a generative model that can not only explain observed data but also generate predictions. Typically, the model is inverted or fitted using conventional tools of (convex) optimization that invariably extremise some functional - norms, minimum descriptive length, variational free energy, etc. Generally, optimisation rests on evaluating the local gradients of the functional to be optimized. In this paper, we compare three different gradient estimation techniques that could be used for extremising any functional in time - (i) finite differences, (ii) forward sensitivities and a method based on (iii) the adjoint of the dynamical system. We demonstrate that the first-order gradients of a dynamical system, linear or non-linear, can be computed most efficiently using the adjoint method. This is particularly true for systems where the number of parameters is greater than the number of states. For such systems, integrating several sensitivity equations - as required with forward sensitivities - proves to be most expensive, while finite-difference approximations have an intermediate efficiency. In the context of neuroimaging, adjoint based inversion of dynamical causal models (DCMs) can, in principle, enable the study of models with large numbers of nodes and parameters. PMID:24769182

  8. High-thermal-gradient Superalloy Crystal Growth

    NASA Technical Reports Server (NTRS)

    Pearson, D. D.; Anton, D. L.; Giamei, A. F.

    1985-01-01

    Single, (001)-oriented crystals of PWA 1480 were processed in alumina/silica shell molds in a laboratory high gradient furnace. The furnace employs a graphite resistance heated element, a radiation baffle, and a water cooled radiation trap below the baffle. All crystals were grown in vacuum (10 torr) and all heat transfer was radiative. The element is constructed with a variable cross section that is tapered just above the baffle to maximize heat input and therefore thermal gradient. A maximum alloy temperature of 1600 C was used. A thermal gradient of 130 deg C/cm was recorded at 1370 C just above the solidus of the PWA 1480 alloys. Crystal bars with 14.4 and 17.5 mm diameters were grown in alumina/silica shell molds. Each crystal was started from a 1.6 mm pencil seed at a rate of 76 mm/hr and slowly accelerated to a rate of 200 mm/hr under computer control. Volume percent porosity and average pore size were measured as functions of distance in representative bars. Low cycle fatigue behavior and stress rupture properties were determined.

  9. Gradient based image completion by solving the Poisson equation

    Microsoft Academic Search

    Jianbing Shen; Xiaogang Jin; Chuan Zhou; Charlie C. L. Wang

    2007-01-01

    This paper presents a novel gradient-based image completion algorithm for re- moving signiflcant objects from natural images or photographs. Our method re- constructs the region of removal in two phases. Firstly, the gradient maps in the removed area are completed through a patch based fllling algorithm. After that, the image is reconstructed from the gradient maps by solving a Poisson

  10. Simple linear formulation for magnetostimulation specific to MRI gradient coils

    Microsoft Academic Search

    Blaine A. Chronik; Brian K. Rutt

    2001-01-01

    A simple linear formulation for magnetostimulation thresholds specific to MRI gradient coils is derived based on established hyperbolic electrostimulation strength vs. duration relations. Thresholds are derived in terms of the gradient excursion re- quired to cause stimulation, and it is demonstrated that the threshold curve is a linear function of the gradient switching time. A parameter b is introduced as

  11. Insertable biplanar gradient coils for magnetic resonance imaging

    Microsoft Academic Search

    M. A. Martens; L. S. Petropoulos; R. W. Brown; J. H. Andrews; M. A. Morich; J. L. Patrick

    1991-01-01

    Insertable planar gradient coils offer the potential for significant performance increases in magnetic resonance imaging through higher gradient strength and shorter rise times. Using variational methods to minimize inductance, and thereby to optimize switching speeds, we have analyzed and constructed a biplanar y-gradient coil for insertion into a solenoidal magnet system where z is the magnet axis. We have also

  12. Minimizing Hot Spot Temperature in Asymmetric Gradient Coil Design

    Microsoft Academic Search

    Peter T. While; Larry K. Forbes; Stuart Crozier

    2011-01-01

    Heating caused by gradient coils is a considerable concern in the operation of MRI scanners. Hot spots can occur in regions where the gradient coil windings are closely spaced. These problem areas are particularly common in the design of gradient coils with asymmetrically located target regions. In this paper, an extension of an existing coil design method is described, to

  13. 3D gradient coil design for open MRI systems

    Microsoft Academic Search

    Peter T. While; Larry K. Forbes; Stuart Crozier

    2010-01-01

    Existing gradient coil design methods typically require some predetermined surface to be specified upon which the precise locations of coil windings are optimised with respect to gradient homogeneity and other measures of coil performance. In contrast, in this paper an analytic inverse method is presented for the theoretical design of 3D gradient coils in which the precise 3D geometry of

  14. FSA design of a gradient coil set for head imaging

    Microsoft Academic Search

    D. Tomasi

    2001-01-01

    In this work the fast-simulated annealing method has been applied to the design of a gradient coil set for head imaging. This stochastic approach is based on the optimization of a parametrized stream function and allows the design of very short self-shielded gradient coils. The main advantage of this technique is its ability to enlarge the homogeneous gradient volume produced

  15. A Quadratic Gradient Equation for pricing Mortgage-Backed Securities

    E-print Network

    Monneau, Régis

    A Quadratic Gradient Equation for pricing Mortgage-Backed Securities Marco Papi Institute for Applied Computing - CNR Rome (Italy) A Quadratic Gradient Equation for pricing Mortgage-Backed Securities call option on a corresponding fixed-rate bond. A Quadratic Gradient Equation for pricing Mortgage

  16. A hybrid optimization method for biplanar transverse gradient coil design

    Microsoft Academic Search

    Qi Feng; Tang Xin; Jin Zhe; Jiang Zhongde; Shen Yifei; Meng bin; Zu Donglin; Wang Weimin

    2007-01-01

    The optimization of transverse gradient coils is one of the fundamental problems in designing magnetic resonance imaging gradient systems. A new approach is presented in this paper to optimize the transverse gradient coils' performance. First, in the traditional spherical harmonic target field method, high order coefficients, which are commonly ignored, are used in the first stage of the optimization process

  17. SUPPLY CHAIN MANAGEMENT CONCENTRATION FOR UNDERGRADUATES

    E-print Network

    Salama, Khaled

    , logistics manager, and warehouse manager. Supply Chain Management Faculty Please see our list of facultySUPPLY CHAIN MANAGEMENT CONCENTRATION FOR UNDERGRADUATES The supply chain management concentration, like a major, focuses on the design and management of supply chains in manufacturing and service

  18. Chain and network science: A research framework

    Microsoft Academic Search

    Jacques H. Trienekens; George Beers

    2001-01-01

    In this first article of the Journal on Chain and Network Science the base-line is set for a discussion on contents and scope of chain and network theory. Chain and network research is clustered into four main 'streams': Network theory, social capital theory, supply chain management and business economics and organizational theory. Furthermore a research agenda is formulated. The article

  19. Collaborative supply chain planning using electronic marketplaces

    Microsoft Academic Search

    Martin Rudberg; Niklas Klingenberg; Kristoffer Kronhamn

    2002-01-01

    The purpose of this paper is to show how the functionality of electronic marketplaces can facilitate collaborative supply chain planning. Supply chain planning processes are identified and analysed using a supply chain management focus. The paper also gives a brief introduction to a framework for supply chain management and to the typical structure of electronic marketplaces. Furthermore, three collaborative supply

  20. Indian cold chain: modeling the inhibitors

    Microsoft Academic Search

    Rohit Joshi; Devinder Kumar Banwet; Ravi Shankar

    2009-01-01

    Purpose – The cold chain has become an integral part of the supply chain of perishable items. Recent studies have shown a critical absence of a strong and dependable cold chain in developing economies. The purpose of this paper is to set out to identify and inter-relate the inhibitors that significantly influence the efficiency of a cold chain in developing

  1. Humanitarian aid: an agile supply chain?

    Microsoft Academic Search

    Richard Oloruntoba; Richard Gray

    2006-01-01

    Purpose – The purpose of this article is to investigate the nature of the humanitarian aid supply chain and discuss the extent to which certain business supply chain concepts, particularly supply chain agility, are relevant to humanitarian aid. Design\\/methodology\\/approach – The paper identifies elements of good practice in conventional business supply chains and applies them to the humanitarian aid supply

  2. Managing Supply Chain at High Technology Companies

    Microsoft Academic Search

    Soin Singh; Latif Al-Hakim

    2009-01-01

    There is an expectation that high technology companies use unique and leading edge technology to gain competitive advantage by investing heavily in supply chain management. This research uses multiple case study methodology to determine factors affecting the supply chain management at high technology companies. The research compares the supply chain performance of these high technology companies against the supply chain

  3. Knowledge redundancy in supply chains: a framework

    Microsoft Academic Search

    K. Sivakumar; Subroto Roy

    2004-01-01

    Knowledge redundancy is a powerful concept in understanding supply chain performance including supply chain value creation and competitive advantage. This paper argues that knowledge redundancy is not about “redundancy” that might suggest a waste or duplication of knowledge. In contrast, knowledge redundancy between adjacent members of the supply chain is critical to superior supply chain performance. The paper examines the

  4. Assessing security risk in global supply chains

    Microsoft Academic Search

    Mary J. Meixell; Mario Norbis

    2011-01-01

    Supply chain security has become a primary concern for supply chain practitioners, and especially so for global supply chains where security related risk is a particular concern. The challenges of security-related risk may be viewed through the lens of the risk management process, which involves identifying, assessing, mitigating and controlling the vulnerabilities that are faced by supply chain managers in

  5. Supply chain risk mitigation: modeling the enablers

    Microsoft Academic Search

    Mohd Nishat Faisal; D. K. Banwet; Ravi Shankar

    2006-01-01

    Purpose – Supply chain risk management assumes importance in the wake of organizations understanding that their risk susceptibility is dependent on other constituents of their supply chain. The purpose of this paper is to present an approach to effective supply chain risk mitigation by understanding the dynamics between various enablers that help to mitigate risk in a supply chain. Design\\/methodology\\/approach

  6. Towards the design of Secure Supply Chains

    Microsoft Academic Search

    M. W. Ludema

    2009-01-01

    Supply chains are the life-lines of society and disturbances or disruptions should be avoided where possible. Secured by adequate protection is possible, but this is based on supply chain designs that are already in place. Designing secure supply chains means to understand security in relation to other supply chain design issues. What the right issues are and how to apply

  7. CALCULATING THE CARBON FOOTPRINT SUPPLY CHAIN FOR

    E-print Network

    Su, Xiao

    a supply chain. The studies were conducted for Walkers, a snack food company, and Trinity MirrorCALCULATING THE CARBON FOOTPRINT SUPPLY CHAIN FOR THE SEMICONDUCTOR INDUSTRY By: Yasser Dessouky September 2008 #12;Supply Chain Definition Supply chains are defined as an integrated process wherein

  8. A Simple Relationship for High Efficiency–Gradient Uniformity Tradeoff in Multilayer Asymmetric Gradient Coils for Magnetic Resonance Imaging

    Microsoft Academic Search

    H. Sanchez; F. Liu; A. Trakic; S. Crozier

    2007-01-01

    High-quality gradient coils are pivotal to advances in magnetic resonance imaging (MRI). We have studied the influence of coil dimensions and target requirements in multilayer, asymmetric, transverse gradient coils. We developed a simple linear function that defines the optimal coil length to produce a maximum figure of merit given an imaging region size and location, coil radius, and gradient nonuniformity.

  9. Biomedical text summarisation using concept chains.

    PubMed

    Reeve, Lawrence H; Han, Hyoil; Brooks, Ari D

    2007-01-01

    BioChainSumm is a biomedical text summariser utilising concept chaining (called BioChain) to link semantically-related concepts within biomedical text together. The BioChain process is adapted from existing lexical chaining approaches which chain semantically-related terms rather than concepts. The BioChain concept chains are used to identify salient candidate sentences which are extracted to produce a summary of the biomedical text. The Unified Medical Language System Metathesaurus and Semantic Network semantic resources identify related biomedical concepts. BioChainSumm is evaluated using the ROUGE system along with several existing, publicly-available summarisers. Our results show BioChain provides a promising methodology for biomedical text summarisation. PMID:18402049

  10. Chains of Mean Field Models

    E-print Network

    Hassani, S Hamed; Urbanke, Ruediger

    2011-01-01

    We consider a collection of mean field spin systems, each of which is placed on the positions of a one-dimensional chain, coupled together by a Kac-type interaction along the chain. We analyze the simplest possible cases where the individual system is a Curie-Weiss model, possibly with a random field. We are interested in the regime where the size of each mean field model tends to infinity and, the length of the chain and range of the Kac interaction are large but finite. Below the critical temperature, there appears a series of equilibrium states representing kink-like interfaces between the two equilibrium states of the individual system. The van der Waals curve oscillates periodically around the Maxwell plateau. These oscillations have a period inversely proportional to the chain length and an amplitude exponentially small in the range of the interaction; in other words the spinodal points of the chain model lie exponentially close to the phase transition threshold. The amplitude of the oscillations is clo...

  11. Semiflexible chains in confined spaces

    NASA Astrophysics Data System (ADS)

    Morrison, Greg; Thirumalai, D.

    2009-01-01

    We develop an analytical method for studying the properties of a noninteracting wormlike chain (WLC) in confined geometries. The mean-field-like theory replaces the rigid constraints of confinement with average constraints, thus allowing us to develop a tractable method for treating a WLC wrapped on the surface of a sphere, and fully encapsulated within it. The efficacy of the theory is established by reproducing the exact correlation functions for a WLC confined to the surface of a sphere. In addition, the coefficients in the free energy are exactly calculated. We also describe the behavior of a surface-confined chain under external tension that is relevant for single molecule experiments on histone-DNA complexes. The force-extension curves display spatial oscillations, and the extension of the chain, whose maximum value is bounded by the sphere diameter, scales as f-1 at large forces, in contrast to the unconfined chain that approaches the contour length as f-1/2 . A WLC encapsulated in a sphere, that is relevant for the study of the viral encapsulation of DNA, can also be treated using the mean-field approach. The predictions of the theory for various correlation functions are in excellent agreement with Langevin simulations. We find that strongly confined chains are highly structured by examining the correlations using a local winding axis. The predicted pressure of the system is in excellent agreement with simulations but, as is known, is significantly lower than the pressures seen for DNA packaged in viral capsids.

  12. Data-driven backward chaining

    NASA Technical Reports Server (NTRS)

    Haley, Paul

    1991-01-01

    The C Language Integrated Production System (CLIPS) cannot effectively perform sound and complete logical inference in most real-world contexts. The problem facing CLIPS is its lack of goal generation. Without automatic goal generation and maintenance, forward chaining can only deduce all instances of a relationship. Backward chaining, which requires goal generation, allows deduction of only that subset of what is logically true which is also relevant to ongoing problem solving. Goal generation can be mimicked in simple cases using forward chaining. However, such mimicry requires manual coding of additional rules which can assert an inadequate goal representation for every condition in every rule that can have corresponding facts derived by backward chaining. In general, for N rules with an average of M conditions per rule the number of goal generation rules required is on the order of N*M. This is clearly intractable from a program maintenance perspective. We describe the support in Eclipse for backward chaining which it automatically asserts as it checks rule conditions. Important characteristics of this extension are that it does not assert goals which cannot match any rule conditions, that 2 equivalent goals are never asserted, and that goals persist as long as, but no longer than, they remain relevant.

  13. Achieving consumer focus in supply chains

    Microsoft Academic Search

    Keivan Zokaei; Peter Hines

    2007-01-01

    Purpose – Supply chain performance is two-dimensional: efficiency and effectiveness. The purpose of this paper is to further define and explore the demarcation between supply chain effectiveness and supply chain efficiency. Design\\/methodology\\/approach – A case-study research method is adopted in this paper. This contribution discusses an approach for the improvement of supply chain effectiveness, i.e. Supply Chain Kano-QFD. Findings –

  14. Spatially resolved solid-state 1H NMR for evaluation of gradient-composition polymeric libraries.

    PubMed

    Leisen, Johannes; Gomez, Ismael J; Roper, John A; Meredith, J Carson; Beckham, Haskell W

    2012-07-01

    Polyurethane libraries consisting of films with composition gradients of aliphatic polyisocyanate and hydroxy-terminated polyacrylate resin were characterized using methods of (1)H NMR microimaging (i.e., magnetic resonance imaging, (MRI)) and solid-state NMR. Molecular mobilities and underlying structural information were extracted as a function of the relative content of each of the two components. Routine NMR microimaging using the spin-echo sequence only allows investigations of transverse relaxation of magnetization at echo times >2 ms. A single-exponential decay was found, which is likely due to free, noncross-linked polymer chains. The mobility of these chains decreases with increasing content of the aliphatic polyisocyanate. The concept of a 1D NMR profiler is introduced as a novel modality for library screening, which allows the convenient measurement of static solid-state NMR spectra as a function of spatial location along a library sample that is repositioned in the rf coil between experiments. With this setup the complete transverse relaxation function was measured using Bloch decays and spin echoes. For all positions within the gradient-composition film, relaxation data consisted of at least three components that were attributed to a rigid highly cross-linked resin, an intermediate cross-linked but mobile constituent, and the highly mobile free polymer chains (the latter is also detectable by MRI). Analysis of this overall relaxation function measured via Bloch decays and spin echoes revealed only minor changes in the mobilities of the individual fractions. Findings with respect to the most mobile components are consistent with the results obtained by NMR microimaging. The major effect is the significant increase in the rigid-component fraction with the addition of the hydroxy-terminated polyacrylate resin. PMID:22676634

  15. Polarized Na+/H+ exchange function is pliable in response to transepithelial gradients of propionate.

    PubMed Central

    Rowe, W A; Lesho, M J; Montrose, M H

    1994-01-01

    Short-chain fatty acids are produced at high concentration in the colonic lumen and stimulate electroneutral Na+ absorption by activating apical Na+/H+ exchange in colonocytes. We used an epithelial cell line derived from a human colon carcinoma (HT29-18-C1) to study activation of apical and basolateral Na+/H+ exchange by a short-chain fatty acid, propionate. Confluent cell monolayers on membrane filters were loaded with 2',7'-bis(2-carboxyethyl)-5 (and 6)-carboxyfluorescein (a fluorescent pH indicator) and intracellular pH was monitored with a digital fluorescence imaging microscope. Cells acidified by transient exposure to NH4Cl demonstrated both apical and basolateral Na+/H+ exchange. In this condition, apical Na+/H+ exchange was 50% of the total Na+/H+ exchange activity. Similar results were obtained when cells were bilaterally perfused with apical and basolateral propionate in an isosmotic medium (130 mM propionate at each membrane surface). However, apical Na+/H+ exchange was a significantly larger fraction (76%) of the total Na+/H+ exchange activity when cells were acidified by exposure to apical propionate alone. Conversely, in cells acidified by basolateral propionate alone, apical Na+/H+ exchange was 21% of the total Na+/H+ exchange activity. The change in relative activity was observed in individual cells which expressed both apical and basolateral Na+/H+ exchange and occurred rapidly (within 7 min). In the presence of transepithelial propionate gradients, all Na(+)-dependent alkalinization was sensitive to 3 microM 5-(N-ethyl-N-isopropyl)amiloride, a potent Na+/H+ exchange inhibitor. These results suggest that transepithelial gradients of short-chain fatty acids, which occur in vivo, can cause preferential activation of apical Na+/H+ exchange. PMID:8016132

  16. Spherical integral formulas for upward/downward continuation of gravitational gradients onto gravitational gradients

    NASA Astrophysics Data System (ADS)

    Šprlák, Michal; Sebera, Josef; Val'ko, Miloš; Novák, Pavel

    2014-02-01

    New integral formulas for upward/downward continuation of gravitational gradients onto gravitational gradients are derived in this article. They provide more options for continuation of gravitational gradient combinations and extend available mathematical apparatus formulated for this purpose up to now. The starting point represents the analytical solution of the spherical gradiometric boundary value problem in the spatial domain. Applying corresponding differential operators on the analytical solution of the spherical gradiometric boundary value problem, a total of 18 integral formulas are provided. Spatial and spectral forms of isotropic kernels are given and their behaviour for parameters of a GOCE-like satellite is investigated. Correctness of the new integral formulas and the isotropic kernels is tested in a closed-loop simulation. The derived integral formulas and the isotropic kernels form a theoretical basis for validation purposes and geophysical applications of satellite gradiometric data as provided currently by the GOCE mission. They also extend the well-known Meissl scheme.

  17. The effect of concomitant gradient fields on diffusion tensor imaging.

    PubMed

    Baron, C A; Lebel, R M; Wilman, A H; Beaulieu, C

    2012-10-01

    Concomitant gradient fields are transverse magnetic field components that are necessarily present to satisfy Maxwell's equations when magnetic field gradients are utilized in magnetic resonance imaging. They can have deleterious effects that are more prominent at lower static fields and/or higher gradient strengths. In diffusion tensor imaging schemes that employ large gradients that are not symmetric about a refocusing radiofrequency pulse (unlike Stejskal-Tanner, which is symmetric), concomitant fields may cause phase accrual that could corrupt the diffusion measurement. Theory predicting the error from this dephasing is described and experimentally validated for both Reese twice-refocused and split gradient single spin-echo diffusion gradient schemes. Bias in apparent diffusion coefficient values was experimentally found to worsen with distance from isocenter and with increasing duration of gradient asymmetry in both a phantom and in the brain. The amount of error from concomitant gradient fields depends on many variables, including the diffusion gradient pattern, pulse sequence timing, maximum effective gradient amplitude, static magnetic field strength, voxel size, slice distance from isocenter, and partial Fourier fraction. A prospective correction scheme that can reduce concomitant gradient errors is proposed and verified for diffusion imaging. PMID:22851517

  18. Cell orientation gradients on an inverse opal substrate.

    PubMed

    Lu, Jie; Zou, Xin; Zhao, Ze; Mu, Zhongde; Zhao, Yuanjin; Gu, Zhongze

    2015-05-20

    The generation of cell gradients is critical for understanding many biological systems and realizing the unique functionality of many implanted biomaterials. However, most previous work can only control the gradient of cell density and this has no effect on the gradient of cell orientation, which has an important role in regulating the functions of many connecting tissues. Here, we report on a simple stretched inverse opal substrate for establishing desired cell orientation gradients. It was demonstrated that tendon fibroblasts on the stretched inverse opal gradient showed a corresponding alignment along with the elongation gradient of the substrate. This "random-to-aligned" cell gradient reproduces the insertion part of many connecting tissues, and thus, will have important applications in tissue engineering. PMID:25942047

  19. Gradient coil design considerations for iron core interventional magnets.

    PubMed

    Ersahin, A; Bronskill, M J; Henkelman, R M; Collick, B; Hinks, R S

    1998-01-01

    The requirements for access and imaging performance compete in the design of open-concept MR magnets and gradient coils. We conducted a theoretical and experimental investigation of gradient coil design using both solid and laminated pole piece construction to determine whether adequate eddy current control can be obtained without shielded gradient coils while maintaining good patient access and high gradient performance. Eddy currents, gradient characteristics, gradient efficiency, and magnet openness are compared and contrasted for various construction options based on a compact, .27 T iron yoke magnet. The resulting pole pieces and gradient coils have high efficiency for an interventional open-configuration magnet while taking up minimal space between the poles for improved patient access. PMID:9786154

  20. Unshielded gradient coils design for magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Hidalgo, S. S.; Gadzinski, C.; Rutt, B.

    2012-10-01

    One of the most important concepts for obtaining an image using MRI is the use of magnetic field gradients. There have been developed different techniques to improve the quality of the magnetic field gradients that allow high strength gradient fields that can be rapidly switched on and off for fast imaging modalities, large homogeneous-gradient-volume or minimum inductance. This work is focused on a comparison between two methods based in the target field method proposed by Turner to build cylindrical unshielded gradient coils. Carlson proposed a current distribution using a Fourier series for a coil of finite length (CAHM). Another solution was proposed by Chronik [4] that adds a set of current constraints forcing the current to lie over a certain length (CCMI). A transverse head gradient coil for imaging application has been implemented in the MATLAB software language and used to create a gradient coil using the CCMI and CAHM methods.

  1. Galactic abundance gradients from Cepheids : On the iron abundance gradient around 10-12 kpc

    E-print Network

    B. Lemasle; P. Francois; A. Piersimoni; S. Pedicelli; G. Bono; C. D. Laney; F. Primas; M. Romaniello

    2008-10-01

    Context: Classical Cepheids can be adopted to trace the chemical evolution of the Galactic disk since their distances can be estimated with very high accuracy. Aims: Homogeneous iron abundance measurements for 33 Galactic Cepheids located in the outer disk together with accurate distance determinations based on near-infrared photometry are adopted to constrain the Galactic iron gradient beyond 10 kpc. Methods: Iron abundances were determined using high resolution Cepheid spectra collected with three different observational instruments: ESPaDOnS@CFHT, Narval@TBL and FEROS@2.2m ESO/MPG telescope. Cepheid distances were estimated using near-infrared (J,H,K-band) period-luminosity relations and data from SAAO and the 2MASS catalog. Results: The least squares solution over the entire data set indicates that the iron gradient in the Galactic disk presents a slope of -0.052+/-0.003 dex/kpc in the 5-17 kpc range. However, the change of the iron abundance across the disk seems to be better described by a linear regime inside the solar circle and a flattening of the gradient toward the outer disk (beyond 10 kpc). In the latter region the iron gradient presents a shallower slope, i.e. -0.012+/-0.014 dex/kpc. In the outer disk (10-12 kpc) we also found that Cepheids present an increase in the spread in iron abundance. Current evidence indicates that the spread in metallicity depends on the Galactocentric longitude. Finally, current data do not support the hypothesis of a discontinuity in the iron gradient at Galactocentric distances of 10-12 kpc. Conclusions: The occurrence of a spread in iron abundance as a function of the Galactocentric longitude indicates that linear radial gradients should be cautiously treated to constrain the chemical evolution across the disk.

  2. Precise Nanoelectronics with Adatom Chains

    NASA Technical Reports Server (NTRS)

    Yamada, Toshishige

    1999-01-01

    Adatom chains on an atomically regulated substrate will be building components in future precise nanoelectronics. Adatoms need to be secured with chemical bonding, but then electronic isolation between the adatom and substrate systems is not guaranteed. A one-dimensional model shows that good isolation with existence of surface states is expected on an s-p crossing substrate such as Si, Ge, or GaAs, reflecting the bulk nature of the substrate. Isolation is better if adatoms are electronically similar to the substrate atoms, and can be manipulated by hydrogenation. Chain structures with group IV adatoms with two chemical bonds, or group III adatoms with one chemical bond, are semiconducting, reflecting the surface nature of the substrate. These structures are unintentionally doped due to the charge transfer across the chemical bonds. Physical properties of adatom chains have to be determined for the unified adatom-substrate system.

  3. Biogeochemistry of a temperate forest nitrogen gradient

    USGS Publications Warehouse

    Perakis, Steven S.; Sinkhorn, Emily R.

    2011-01-01

    Wide natural gradients of soil nitrogen (N) can be used to examine fundamental relationships between plant–soil–microbial N cycling and hydrologic N loss, and to test N-saturation theory as a general framework for understanding ecosystem N dynamics. We characterized plant production, N uptake and return in litterfall, soil gross and net N mineralization rates, and hydrologic N losses of nine Douglas-fir (Pseudotsuga menziesii) forests across a wide soil N gradient in the Oregon Coast Range (USA). Surface mineral soil N (0–10 cm) ranged nearly three-fold from 0.29% to 0.78% N, and in contrast to predictions of N-saturation theory, was linearly related to 10-fold variation in net N mineralization, from 8 to 82 kg N·ha?1·yr?1. Net N mineralization was unrelated to soil C:N, soil texture, precipitation, and temperature differences among sites. Net nitrification was negatively related to soil pH, and accounted for ?1·yr?1. Aboveground net primary production per unit net N mineralization varied inversely with soil N, suggesting progressive saturation of plant N demands at high soil N. Hydrologic N losses were dominated by dissolved organic N at low-N sites, with increased nitrate loss causing a shift to dominance by nitrate at high-N sites, particularly where net nitrification exceeded plant N demands. With the exception of N mineralization patterns, our results broadly support the application of the N-saturation model developed from studies of anthropogenic N deposition to understand N cycling and saturation of plant and microbial sinks along natural soil N gradients. This convergence of behavior in unpolluted and polluted forest N cycles suggests that where future reductions in deposition to polluted sites do occur, symptoms of N saturation are most likely to persist where soil N content remains elevated.

  4. Stellar population gradients in early-type cluster galaxies

    NASA Astrophysics Data System (ADS)

    Rawle, T. D.; Smith, Russell J.; Lucey, J. R.

    2010-01-01

    We present a study of internal stellar population gradients in early-type cluster galaxies. Using the Very Large Telescope (VLT) Visible Multi-Object Spectrograph (VIMOS) integral field unit, we observed 19 galaxies in the core of the Shapley supercluster (z = 0.048). The radial trends in nine absorption lines (H?F to Fe5406) were measured to the effective radius for 14 galaxies, from which we derived the gradients in age, total metallicity and ?-element overabundance. We combine these with results from 11 galaxies studied in our previous VIMOS work. We observe a mean metallicity gradient of -0.13 +/- 0.04dex-1 and, in common with the findings of previous studies, galaxies with log? >~ 2.1 have a sizeable intrinsic scatter in metallicity gradient. The mean log(age/Gyr) gradient is -0.02 +/- 0.06dex-1, although several galaxies have significant positive or negative age gradients. The mean gradient in ?-element enhancement is -0.10 +/- 0.04dex-1. We find that stellar population gradients are primarily related to the central metallicity: early-type galaxies with supersolar centres have steep negative metallicity gradients and positive age gradients; those with solar metallicity centres have negligible [Z/H] gradients and negative age gradients. There is a strong observed anticorrelation between the gradients in age and metallicity. While a part of this trend can be attributed to the correlation of measurement errors, we demonstrate that there is an underlying intrinsic relation. For the Shapley galaxies, B - R colour gradients predicted from spectroscopic age and metallicity generally agree well with those measured directly from photometry. Based on observations from the European Organisation for Astronomical Research in the Southern Hemisphere, Chile (programmes: 078.B-0539, 081.B-0539). E-mail: t.d.rawle@durham.ac.uk

  5. GradientOptimizer: an open-source graphical environment for calculating optimized gradients in reversed-phase liquid chromatography.

    PubMed

    Moruz, Luminita; Käll, Lukas

    2014-06-01

    We here present GradientOptimizer, an intuitive, lightweight graphical user interface to design nonlinear gradients for separation of peptides by reversed-phase liquid chromatography. The software allows to calculate three types of nonlinear gradients, each of them optimizing a certain retention time distribution of interest. GradientOptimizer is straightforward to use, requires minimum processing of the input files, and is supported under Windows, Linux, and OS X platforms. The software is open-source and can be downloaded under an Apache 2.0 license at https://github.com/statisticalbiotechnology/NonlinearGradientsUI. PMID:24700534

  6. A Compact High Gradient Pulsed Magnetic Quadpole

    SciTech Connect

    Shuman, D.; Faltens, A.; Kajiyama, Y.; Kireeff-Covo, M.; Seidl, P.

    2005-07-05

    A design for a high gradient, low inductance pulsed quadrupole magnet is presented. The magnet is a circular current dominated design with a circular iron return yoke. Conductor angles are determined by a method of direct multipole elimination which theoretically eliminates the first four higher order multipole field components. Coils are fabricated from solid round film-insulated conductor, wound as a single layer ''non-spiral bedstead'' coil having a diagonal leadout entirely within one upturned end. The coils are wound and stretched straight in a special winder, then bent in simple fixtures to form the upturned ends.

  7. Diffusion Effects in Gradient Echo Memory

    E-print Network

    X. -W. Luo; J. J. Hope; B. Hillman; T. M. Stace

    2013-03-18

    We study the effects of diffusion on a $\\Lambda$-gradient echo memory, which is a coherent optical quantum memory using thermal gases. The efficiency of this memory is high for short storage time, but decreases exponentially due to decoherence as the storage time is increased. We study the effects of both longitudinal and transverse diffusion in this memory system, and give both analytical and numerical results that are in good agreement. Our results show that diffusion has a significant effect on the efficiency. Further, we suggest ways to reduce these effects to improve storage efficiency.

  8. Alternating-Gradient Photodetector For Far Infrared

    NASA Technical Reports Server (NTRS)

    Overhauser, Albert W.; Maserjian, Joseph

    1989-01-01

    Proposed detector of photons of wavelengths in range of 30 to 200 micrometer made of alternating layers of lightly and heavily negatively doped germanium. Formed in sequence by conventional chemical-vapor deposition. Alternating-gradient structure enhances collection of photogenerated charge carriers while suppressing dark current, thus achieving high detectivity. Alternating layers of n+ and n- germanium provides high detectivity in far-infrared spectral region. Also possible to make similar structures with positive doping and with other semiconductors as silicon or gallium arsenide to obtain various spectral response.

  9. Temperature gradients in the core overshooting region

    NASA Astrophysics Data System (ADS)

    Godart, M.

    2007-06-01

    The term overshooting is used to describe two situations: the chemical mixing induced by the convective elements crossing the boundary given by Schwarzschild's criterion (overshooting), or, in addition to that mixing, the change in the temperature gradient in the overshoot region when convection is efficient enough (penetration; Zahn 1991). We show that for models with the same mass of the mixed central region the oscillation frequencies are sensitive to the kind of overshoot treatment adopted. This effect is especially obvious for SPB stars and is high enough to be detected by CoRoT long run observations. That would imply the possibility of disentangling penetration from overshooting.

  10. Reconciling supply chain vulnerability, risk and supply chain management

    Microsoft Academic Search

    H. Peck

    2006-01-01

    Supply chain vulnerability has become a fashionable area of management research. The purpose of this paper is to provide a critique of the extant canon and to review of the positioning of research in the field, together with literature drawn from several relevant and overlapping fields of research and practice. The aim is to foster a more explicit understanding of

  11. Automatic nuclear cataract grading using image gradients

    PubMed Central

    Srivastava, Ruchir; Gao, Xinting; Yin, Fengshou; Wong, Damon W. K.; Liu, Jiang; Cheung, Carol Y.; Wong, Tien Yin

    2014-01-01

    Abstract. This paper deals with automatic grading of nuclear cataract (NC) from slit-lamp images in order to reduce the efforts in traditional manual grading. Existing works on this topic have mostly used brightness and color of the eye lens for the task but not the visibility of lens parts. The main contribution of this paper is in utilizing the visibility cue by proposing gray level image gradient-based features for automatic grading of NC. Gradients are important for the task because in a healthy eye, clear visibility of lens parts leads to distinct edges in the lens region, but these edges fade as severity of cataract increases. Experiments performed on a large dataset of over 5000 slit-lamp images reveal that the proposed features perform better than the state-of-the-art features in terms of both speed and accuracy. Moreover, fusion of the proposed features with the prior ones gives results better than any of the two used alone.

  12. Droplet microfluidics driven by gradients of confinement

    PubMed Central

    Dangla, Rémi; Kayi, S. Cagri; Baroud, Charles N.

    2013-01-01

    The miniaturization of droplet manipulation methods has led to drops being proposed as microreactors in many applications of biology and chemistry. In parallel, microfluidic methods have been applied to generate monodisperse emulsions for applications in the pharmaceuticals, cosmetics, and food industries. To date, microfluidic droplet production has been dominated by a few designs that use hydrodynamic forces, resulting from the flowing fluids, to break drops at a junction. Here we present a platform for droplet generation and manipulation that does not depend on the fluid flows. Instead, we use devices that incorporate height variations to subject the immiscible interfaces to gradients of confinement. The resulting curvature imbalance along the interface causes the detachment of monodisperse droplets, without the need for a flow of the external phase. Once detached, the drops are self-propelled due to the gradient of surface energy. We show that the size of the drops is determined by the device geometry; it is insensitive to the physical fluid properties and depends very weakly on the flow rate of the dispersed phase. This allows us to propose a geometric theoretical model that predicts the dependence of droplet size on the geometric parameters, which is in agreement with experimental measurements. The approach presented here can be applied in a wide range of standard applications, while simplifying the device operations. We demonstrate examples for single-droplet operations and high-throughput generation of emulsions, all of which are performed in simple and inexpensive devices. PMID:23284169

  13. Shape optimization of pressure gradient microphones

    NASA Technical Reports Server (NTRS)

    Norum, T. D.; Seiner, J. M.

    1977-01-01

    Recently developed finite element computer programs were utilized to investigate the influence of the shape of a body on its scattering field with the aim of determining the optimal shape for a Pressure Gradient Microphone (PGM). Circular cylinders of various aspect ratios were evaluated to choose the length to diameter ratio best suited for a dual element PGM application. Alterations of the basic cylindrical shape by rounding the edges and recessing at the centerline were also studied. It was found that for a + or - 1 db deviation from a linear pressure gradient response, a circular cylinder of aspect ratio near 0.5 was most suitable, yielding a useful upper frequency corresponding to ka = 1.8. The maximum increase in this upper frequency limit obtained through a number of shape alterations was only about 20 percent. An initial experimental evaluation of a single element cylindrical PGM of aspect ratio 0.18 utilizing a piezoresistive type sensor was also performed and is compared to the analytical results.

  14. Asymmetric Uncertainty Expression for High Gradient Aerodynamics

    NASA Technical Reports Server (NTRS)

    Pinier, Jeremy T

    2012-01-01

    When the physics of the flow around an aircraft changes very abruptly either in time or space (e.g., flow separation/reattachment, boundary layer transition, unsteadiness, shocks, etc), the measurements that are performed in a simulated environment like a wind tunnel test or a computational simulation will most likely incorrectly predict the exact location of where (or when) the change in physics happens. There are many reasons for this, includ- ing the error introduced by simulating a real system at a smaller scale and at non-ideal conditions, or the error due to turbulence models in a computational simulation. The un- certainty analysis principles that have been developed and are being implemented today do not fully account for uncertainty in the knowledge of the location of abrupt physics changes or sharp gradients, leading to a potentially underestimated uncertainty in those areas. To address this problem, a new asymmetric aerodynamic uncertainty expression containing an extra term to account for a phase-uncertainty, the magnitude of which is emphasized in the high-gradient aerodynamic regions is proposed in this paper. Additionally, based on previous work, a method for dispersing aerodynamic data within asymmetric uncer- tainty bounds in a more realistic way has been developed for use within Monte Carlo-type analyses.

  15. Dynamic separation of macromolecules under temperature gradient

    NASA Astrophysics Data System (ADS)

    Maeda, Yusuke; Buguin, Axel; Libchaber, Albert

    2011-03-01

    Thermophoresis is a motion of suspensions in a fluid that are subjected to a temperature gradient. Although its effect is widely studied in case of single solute in water, little is known about how the mixture of different solutes is affected. We heated water with an infrared laser by ?Tmax = 5C and ? T = 0.25C/um to induce thermophoresis of polyethylene glycol (PEG) and DNA. PEG is depleted from the hot region and results in a stationary gradient of its high volume fraction ? . Under this high concentration of PEG, DNA of small concentration is submitted to thermophoresis and osmotic pressure difference. The DNA shows regime of depletion, ring-like localization and accumulation as the volume fraction of PEG increases. As the osmotic force depends on the size of trapped solutes, DNA of different size accumulates at different regions. Depending whether the DNA size is below or above 5kbp a different scaling of position versus DNA size is observed. Thermal separation is a general phenomenon. It applies also to RNA and microbeads. YTM is supported by JSPS fellowship and M.Josee-H.Kravis fellowship from the Rockefeller University.

  16. Neutrophil migration under spatially-varying chemoattractant gradient profiles.

    PubMed

    Halilovic, Iris; Wu, Jiandong; Alexander, Murray; Lin, Francis

    2015-06-01

    Chemotaxis plays an important role in biological processes such as cancer metastasis, embryogenesis, wound healing, and immune response. Neutrophils are the frontline defenders against invasion of foreign microorganisms into our bodies. To achieve this important immune function, a neutrophil can sense minute chemoattractant concentration differences across its cell body and effectively migrate toward the chemoattractant source. Furthermore, it has been demonstrated in various studies that neutrophils are highly sensitive to changes in the surrounding chemoattractant environments, suggesting the role of a chemotactic memory for processing the complex spatiotemporal chemical guiding signals. Using a microfluidic device, in the present study we characterized neutrophil migration under spatially varying profiles of interleukine-8 gradients, which consist of three spatially ordered regions of a shallow gradient, a steep gradient and a nearly saturated gradient. This design allowed us to examine how neutrophils migrate under different chemoattractant gradient profiles, and how the migratory response is affected when the cell moves from one gradient profile to another in a single experiment. Our results show robust neutrophil chemotaxis in the shallow and steep gradient, but not the saturated gradient. Furthermore, neutrophils display a transition from chemotaxis to flowtaxis when they migrate across the steep gradient interface, and the relative efficiency of this transition depends on the cell's chemotaxis history. Finally, some neutrophils were observed to adjust their morphology to different gradient profiles. PMID:25998723

  17. Molecules and chains in a strong magnetic field - Statistical treatment

    NASA Technical Reports Server (NTRS)

    Abrahams, Andrew M.; Shapiro, Stuart L.

    1991-01-01

    A Thomas-Fermi-Dirac-Weizsaecker statistical model is developed and employed to investigate diatomic molecules and infinite molecular chains in strong magnetic fields. The standard magnetic Thomas-Fermi-Dirac kinetic, potential, and exchange energy functionals are supplemented by a gradient correction to the kinetic energy. The numerical method used for solving this system in two spatial dimensions is detailed. Numerical solutions for a wide range of magnetic strengths and elements are presented to demonstrate the robustness, as well as the limitations, of the statistical approach. These calculations qualitatively reproduce many of the results of detailed quantum mechanical treatments. For example, the fractional binding energy is greatest for low atomic numbers and for strong magnetic fields.

  18. Pumpernickel Valley Geothermal Project Thermal Gradient Wells

    SciTech Connect

    Z. Adam Szybinski

    2006-01-01

    The Pumpernickel Valley geothermal project area is located near the eastern edge of the Sonoma Range and is positioned within the structurally complex Winnemucca fold and thrust belt of north-central Nevada. A series of approximately north-northeast-striking faults related to the Basin and Range tectonics are superimposed on the earlier structures within the project area, and are responsible for the final overall geometry and distribution of the pre-existing structural features on the property. Two of these faults, the Pumpernickel Valley fault and Edna Mountain fault, are range-bounding and display numerous characteristics typical of strike-slip fault systems. These characteristics, when combined with geophysical data from Shore (2005), indicate the presence of a pull-apart basin, formed within the releasing bend of the Pumpernickel Valley – Edna Mountain fault system. A substantial body of evidence exists, in the form of available geothermal, geological and geophysical information, to suggest that the property and the pull-apart basin host a structurally controlled, extensive geothermal field. The most evident manifestations of the geothermal activity in the valley are two areas with hot springs, seepages, and wet ground/vegetation anomalies near the Pumpernickel Valley fault, which indicate that the fault focuses the fluid up-flow. There has not been any geothermal production from the Pumpernickel Valley area, but it was the focus of a limited exploration effort by Magma Power Company. In 1974, the company drilled one exploration/temperature gradient borehole east of the Pumpernickel Valley fault and recorded a thermal gradient of 160oC/km. The 1982 temperature data from five unrelated mineral exploration holes to the north of the Magma well indicated geothermal gradients in a range from 66 to 249oC/km for wells west of the fault, and ~283oC/km in a well next to the fault. In 2005, Nevada Geothermal Power Company drilled four geothermal gradient wells, PVTG-1, -2, -3, and -4, and all four encountered geothermal fluids. The holes provided valuable water geochemistry, supporting the geothermometry results obtained from the hot springs and Magma well. The temperature data gathered from all the wells clearly indicates the presence of a major plume of thermal water centered on the Pumpernickel Valley fault, and suggests that the main plume is controlled, at least in part, by flow from this fault system. The temperature data also defines the geothermal resource with gradients >100oC/km, which covers an area a minimum of 8 km2. Structural blocks, down dropped with respect to the Pumpernickel Valley fault, may define an immediate reservoir. The geothermal system almost certainly continues beyond the recently drilled holes and might be open to the east and south, whereas the heat source responsible for the temperatures associated with this plume has not been intersected and must be at a depth greater than 920 meters (depth of the deepest well – Magma well). The geological and structural setting and other characteristics of the Pumpernickel Valley geothermal project area are markedly similar to the portions of the nearby Dixie Valley geothermal field. These similarities include, among others, the numerous, unexposed en echelon faults and large-scale pull-apart structure, which in Dixie Valley may host part of the geothermal field. The Pumpernickel Valley project area, for the majority of which Nevada Geothermal Power Company has geothermal rights, represents a geothermal site with a potential for the discovery of a relatively high temperature reservoir suitable for electric power production. Among locations not previously identified as having high geothermal potential, Pumpernickel Valley has been ranked as one of four sites with the highest potential for electrical power production in Nevada (Shevenell and Garside, 2003). Richards and Blackwell (2002) estimated the total heat loss and the preliminary production capacity for the entire Pumpernickel Valley geothermal system to be at 35MW. A more conservative estimate, for

  19. Temperature gradients, not food resource gradients, affect growth rate of migrating Daphnia mendotae in Lake Michigan

    Microsoft Academic Search

    Kevin L. Pangle; Scott D. Peacor

    2010-01-01

    Zooplankton production plays a critical role in the Great Lakes ecosystem, and vertical migration, which is exhibited by many zooplankton species, could affect production. We examined the effects of water temperature and food resource gradients on the growth rate of zooplankton undergoing vertical migration in Lake Michigan. In three laboratory experiments, juvenile Daphnia mendotae, native herbivorous cladocerans, were incubated for

  20. Novette chain design and performance

    SciTech Connect

    Hunt, J.T.; Speck, D.R.

    1980-12-11

    The design and performance of the Novette laser system, which is a two-beam, two-wavelength (1.05 ..mu.. and 0.53 ..mu..) target irradiation facility using phosphate glass laser chains, are discussed with information on the glass properties, controlling factors in the design selection, and projected performance with varying operating conditions. (LCL)

  1. Greening the aluminium supply chain

    Microsoft Academic Search

    I. Ferretti; S. Zanoni; L. Zavanella; A. Diana

    2007-01-01

    This paper originated from an industrial case study in the field of the aluminium supply chain. In particular, the most original aspects of the study are linked to the use of an alternative supply method for raw material (aluminium) in manufacturing. This method consists in the possibility of the company receiving the aluminium alloy from its supplier (refiner and remelter

  2. Automating supply-chain management

    Microsoft Academic Search

    Michael N. Huhns; Larry M. Stephens; Nenad Ivezic

    2002-01-01

    This paper explores a linguistic approach to coordination modeling as a formal basis for supply-chain management (SCM) in manufacturing. The approach promotes the interchange of standard documents: enterprises need only describe their supply processes using OAG business object documents and UML interaction diagrams. Our methodology and tools analyze the documents and interactions in terms of four linguistic primitives and convert

  3. Chain configurations in light nuclei

    E-print Network

    S. Yu. Torilov; K. A. Gridnev

    2007-02-16

    The model of nuclear matter built from alpha-particles is proposed. The strong deformed shape for doubly even N=Z nuclides from carbon to magnesium has been determined according to this model. In this paper we undertake very simple approach, which assumes the existence of low lying chain configurations.

  4. Realities of supply chain collaboration

    Microsoft Academic Search

    R. P. Kampstra; J. Ashayeri; J. L. Gattorna

    2006-01-01

    Purpose – This paper aims to investigate the gap between the interests in supply chain collaboration (SCC) and the relatively few recorded cases of successful applications – this is the reality of SCC. Design\\/methodology\\/approach – The research represents the viewpoints of the authors based on their collective field experiences and literature reviews. Findings – Three realities of SCC are identified

  5. Supply chain collaboration for sustainability

    Microsoft Academic Search

    Kovács Gyöngyi

    Corporations have recently started to acknowledge that they cannot tackle their social and environmental responsibilities alone. Concepts such as extended producer responsibility and life cycle assessment approaches have drawn attention to the product chain beyond immediate buyer-supplier interfaces. In fact, consumers and end users hold a corporation liable even for the actions of its suppliers. At the same time, approaches

  6. The causal chain of loyalty

    Microsoft Academic Search

    Manel KHADRAOUI; Jamel-Eddine GHARBI; Michel Plaisent

    Loyalty is considered as a key concept in the establishment and maintenance of long term relationships. In this work in progress communication, a theoretical framework is proposed on the basis of the relationship marketing paradigm and commitment trust theory. Loyalty is conceived according to Oliver (1997) as a causal chain composed by cognitive loyalty, affective loyalty, conative loyalty and action

  7. Spin chains and string theory

    Microsoft Academic Search

    Martin Kruczenski

    Recently, an impressive agreement was found between anomalous dimen- sions of certain operators in N = 4 SYM and rotating strings with two angular mo- menta in the bulk of AdS5 × S5. A one-loop field theory computation, which involves solving a Heisenberg chain by means of the Bethe ansatz agrees with the large angular momentum limit of a rotating

  8. Verifying Continuous Time Markov Chains

    Microsoft Academic Search

    Adnan Aziz; Kumud Sanwal; Vigyan Singhal; Robert K. Brayton

    1996-01-01

    . We present a logical formalism for expressing properties ofcontinuous time Markov chains. The semantics for such properties ariseas a natural extension of previous work on discrete time Markov chainsto continuous time. The major result is that the verification problemis decidable; this is shown using results in algebraic and transcendentalnumber theory.IntroductionRecent work on formal verification has addressed systems with stochastic

  9. Remarks on food chain dynamics

    Microsoft Academic Search

    S Rinaldi

    1996-01-01

    The main modes of behavior of a food chain model composed of logistic prey and Holling type II predator and superpredator are discussed in this paper. The study is carried out through bifurcation analysis, alternating between a normal form approach and numerical continuation. The two-parameter bifurcation diagram of the model contains Hopf, fold, and transcritical bifurcation curves of equilibria as

  10. Remarks on food chain dynamics

    Microsoft Academic Search

    Yu. a. Kuznetsov; S. Rinaldi

    1995-01-01

    The main modes of behavior of a food chain model, composed of logistic prey and Holling type II predator and superpredator, are discussed in this paper. The study is carried out through bifurcation analysis, alternating between a normal form approach and numerical continuation. The two-parameter bifurcation diagram of the model contains Hopf, fold and transcritical bifurcation curves of equilibria as

  11. Supply chain challenges. building relationships.

    PubMed

    Beth, Scott; Burt, David N; Copacino, William; Gopal, Chris; Lee, Hau L; Lynch, Robert Porter; Morris, Sandra

    2003-07-01

    Supply chain management is all about software and systems, right? Put in the best technology, sit back, and watch as your processes run smoothly and the savings roll in? Apparently not. When HBR convened a panel of leading thinkers in the field of supply chain management, technology was not top of mind. People and relationships were the dominant issues of the day. The opportunities and problems created by globalization, for example, are requiring companies to establish relationships with new types of suppliers. The ever-present pressure for speed and cost containment is making it even more important to break down stubbornly high internal barriers and establish more effective cross-functional relationships. The costs of failure have never been higher. The leading supply chain performers are applying new technology, new innovations, and process thinking to far greater advantage than the laggards, reaping tremendous gains in all the variables that affect shareholder value: cost, customer service, asset productivity, and revenue generation. And the gap between the leaders and the losers is growing in almost every industry. This roundtable gathered many of the leading thinkers and doers in the field of supply chain management, including practitioners Scott Beth of Intuit, Sandra Morris of Intel, and Chris Gopal of Unisys. David Burt of the University of San Diego and Stanford's Hau Lee bring the latest research from academia. Accenture's William Copacino and the Warren Company's Robert Porter Lynch offer the consultant's perspectives. Together, they take a wide-ranging view of such topics as developing talent, the role of the chief executive, and the latest technologies, exploring both the tactical and the strategic in the current state of supply chain management. PMID:12858712

  12. A versatile magnetic field gradient control system for NMR imaging

    NASA Astrophysics Data System (ADS)

    Bottomley, P. A.

    1981-09-01

    A complete digitally controlled magnetic field gradient system for NMR imaging is described; the device is capable of operating in the projection reconstruction (PR), the sensitive line (SL), and the sensitive point (SP) modes. Gradient scanning is achieved via clocked eight-bit counters which step either a digital vector generator when operating in the PR mode, or a series of MDACs when in the SL or SP modes. Versatile control of the image array size, the spatial resolution, the orientation of projections, and the positioning of sensitive lines and points is provided without the use of moving parts or microprocessors and with little or no computer interfacing. The device will function either independent of a conventional NMR Fourier transform spectrometer system when manual gradient scanning is employed, or synchronously with the spectrometer when gradients are scanned automatically. A gradient coil design and criteria for establishing the gradient amplitudes are discussed, and some NMR images which were generated with the system are presented.

  13. Thermoacoustic mixture separation with an axial temperature gradient.

    PubMed

    Geller, D A; Swift, G W

    2009-05-01

    The theory of thermoacoustic mixture separation is extended to include the effect of a nonzero axial temperature gradient. The analysis yields a new term in the second-order mole flux that is proportional to the temperature gradient and to the square of the volumetric velocity and is independent of the phasing of the wave. Because of this new term, thermoacoustic separation stops at a critical temperature gradient and changes direction above that gradient. For a traveling wave, this gradient is somewhat higher than that predicted by a simple four-step model. An experiment tests the theory for temperature gradients from 0 to 416 K/m in 50-50 He-Ar mixtures. PMID:19425637

  14. Thermoacoustic mixture separation with an axial temperature gradient

    SciTech Connect

    Geller, Drew W [Los Alamos National Laboratory; Swift, Gregory A [Los Alamos National Laboratory

    2008-01-01

    The theory of thermoacoustic mixture separation is extended to include the effect of a nonzero axial temperature gradient. The analysis yields a new term in the second-order mole flux that is proportional to the temperature gradient and to the square of the volumetric velocity and is independent of the phasing of the wave. Because of this new term, thermoacoustic separation stops at a critical temperature gradient and changes direction above that gradient. For a traveling wave, this gradient is somewhat higher than that predicted by a simple four-step model. An experiment tests the theory for temperature gradients from 0 to 416 K/m in 50-50 He-Ar mixtures.

  15. Fabrication of arrays of polymer gradients using inkjet printing.

    PubMed

    Hansen, Anne; Zhang, Rong; Bradley, Mark

    2012-07-13

    Arrays of 84 polymer gradients, fabricated on a single glass microscope slide, were generated by inkjet printing, allowing a combination of high-throughput and true combinatorial methods. The gradual change of composition within the polymer gradients, consisting of two different monomers and a cross-linker, was validated by XPS and fluorescence analysis. Cellular screening of the gradients allowed the rapid identification of optimal polymer compositions for binding of the suspension cell line K562 and the adherent cell line HeLa. The polymers identified were identical to those identified by previous microarray data, providing proof of concept for the successful application of the polymer gradient arrays as a screening tool. In addition, the polymer gradients could be readily modified by conjugation enabling the generation of bio-molecule gradients. PMID:22528882

  16. Design of a High Thermal Gradient Bridgman Furnace

    NASA Technical Reports Server (NTRS)

    LeCroy, J. E.; Popok, D. P.

    1994-01-01

    The Advanced Automated Directional Solidification Furnace (AADSF) is a Bridgman-Stockbarger microgravity processing facility, designed and manifested to first fly aboard the second United States Microgravity Payload (USMP-2) Space Shuttle mission. The AADSF was principally designed to produce high axial thermal gradients, and is particularly suitable for metals solidification experiments, including non-dilute alloys. To accommodate a wider range of experimental conditions, the AADSF is equipped with a reconfigurable gradient zone. The overall design of the AADSF and the relationship between gradient zone design and furnace performance are described. Parametric thermal analysis was performed and used to select gradient zone design features that fulfill the high thermal gradient requirements of the USMP-2 experiment. The thermal model and analytical procedure, and parametric results leading to the first flight gradient zone configuration, are presented. Performance for the USMP-2 flight experiment is also predicted, and analysis results are compared to test data.

  17. Gradient-zone erosion by extraction in solar ponds

    SciTech Connect

    Estevadeordal, J.; Kleis, S.J. [Univ. of Houston, TX (United States). Dept. of Mechanical Engineering

    1995-05-01

    The erosion of the dynamically stable gradient zone of a salinity-gradient solar pond, due to the extraction of fluid from the storage zone, is numerically investigated. The effects of fluid withdrawal rate, density stratification level, pond and diffuser geometries, and diffuser placement are considered. It is found, for a typical salinity-gradient solar pond with uniform salinity in the storage zone and a continuous salinity gradient above that a finite amount of fluid entrainment from the gradient zone is inevitable. That is, a finite density difference across the interface is always required for a finite extraction rate under steady-state conditions. The magnitude of the density difference is predicted as a function of the geometric and flow parameters. From the results, it is possible to predict the total amount of fluid entrained from the gradient zone as the pond reaches steady-state for prescribed operating conditions.

  18. Gradient descent algorithms for quantile regression with smooth approximation

    Microsoft Academic Search

    Songfeng Zheng

    Gradient based optimization methods often converge quickly to a local optimum. However, the check loss function used by quantile\\u000a regression model is not everywhere differentiable, which prevents the gradient based optimization methods from being applicable.\\u000a As such, this paper introduces a smooth function to approximate the check loss function so that the gradient based optimization\\u000a methods could be employed for

  19. Effects of pressure gradients on turbulent premixed flames

    NASA Technical Reports Server (NTRS)

    Veynante, D.; Poinsot, T.

    1995-01-01

    The influence of a constant acceleration on a turbulent premixed flame is studied by direct numerical simulation. This acceleration induces a mean pressure gradient across the flame brush, leading to a modification of the turbulent flame structure due to differential buoyancy mechanisms between heavy cold fresh and light hot burnt gases. Such a pressure gradient may be encountered in practical applications in ducted flames. A favorable pressure gradient, i.e. the pressure decreases from unburnt to burnt gases, is found to decrease the flame wrinkling, the flame brush thickness, and the turbulent flame speed. A favorable pressure gradient also promotes counter-gradient turbulent transport. On the other hand, adverse pressure gradients tend to increase the flame brush thickness and turbulent flame speed, and promote classical gradient turbulent transport. The balance equation for the turbulent flux of the Favre averaged progress variable is also analyzed. The first results show that the fluctuating pressure term, cannot be neglected as generally assumed in models. Simple models assuming that a high mean pressure gradient may only be balanced by the cross-dissipation term seem too approximate. This analysis has to be continued to compare simulation data and closure schemes proposed for the transport equation. The analysis developed by Veynante et al.(1995) has been extended to imposed acceleration and mean pressure gradients. A simple model for the turbulent flux is proposed and validated from simulation data. Then, a modified criterion is derived to delineate between counter-gradient and gradient turbulent diffusion. In fact, counter-gradient diffusion may occur in most practical applications, especially for ducted flames.

  20. Semi-Analytic Models of Abundance Gradients in External Galaxies

    NASA Astrophysics Data System (ADS)

    Ashenfelter, T. P.; Mathews, G. J.

    2001-12-01

    We analyze observed abundance gradients as a function of Galactocentric radius for the external Galaxies NGC4254 and NGC4303. We model the abundance gradients of Nitrogen, Oxygen, and Sulfur for several semi-analytic models. These models isolate the affect of the low metallicity infall term. We conclude that the low metallicity infall models can not adequately explain the steep abundance gradients in these spiral galaxies. Therefore, additional chemical and dynamical mechanisms must be responsible for the observed abundances.

  1. Effective anisotropy gradient in pressure graded [Co/Pd] multilayers

    NASA Astrophysics Data System (ADS)

    Kirby, B. J.; Greene, P. K.; Maranville, B. B.; Davies, J. E.; Liu, Kai

    2015-02-01

    We have used polarized neutron reflectometry to show that controlled variation of growth pressure during deposition of Co/Pd multilayers can be used to achieve a significant vertical gradient in the effective anisotropy. This gradient is strongly dependent on deposition order (low to high pressure or vice versa), and is accompanied by a corresponding gradient in saturation magnetization. These results demonstrate pressure-grading as an attractively simple technique for tailoring the anisotropy profile of magnetic media.

  2. Directional solidification at ultra-high thermal gradient

    NASA Technical Reports Server (NTRS)

    Flemings, M. C.; Lee, D. S.; Neff, M. A.

    1980-01-01

    A high gradient controlled solidification (HGC) furnace was designed and operated at gradients up to 1800 C/cm to continuously produce aluminum alloys. Rubber '0' rings for the water cooling chamber were eliminated, while still maintaining water cooling directly onto the solidified metal. An HGC unit for high temperature ferrous alloys was also designed. Successful runs were made with cast iron, at thermal gradients up to 500 C/cm.

  3. Simulation and analysis of split gradient coil performance in MRI

    Microsoft Academic Search

    Limei Liu; Hector Sanchez-Lopez; Michael Poole; Feng Liu; Stuart Crozier

    2011-01-01

    Split magnet systems for hybrid imaging, such as positron emission tomography-magnetic resonance imaging (PET-MRI) and Radiotherapy-MRI, require gradient coils designed with similar shapes as their corresponding main magnet. This introduces challenges in the gradient coil design of good performance and manufacturing. In this paper the effect of the gap size in shielded transverse split gradient coils and split cryostat “warm”

  4. Minimum inductance optimal design for the gradient coil

    Microsoft Academic Search

    Chen Yin-ping; Zhu Guo-qiang

    2002-01-01

    In MRI (Magnetic Resonance Imaging), a crucial role of gradient coils is to image organism, meanwhile the inductance of the\\u000a coils determines the speed of imaging. So it is of great importance to optimize designs of the gradient coils. The target\\u000a field approach is an effective method to design the gradient coils. Having applied this method and performing many numerical

  5. Controlled E-field gradient coils for MRI

    Microsoft Academic Search

    P Mansfield; B Haywood

    2008-01-01

    Peripheral neural stimulation is a major problem in current gradient coil designs. Induced current problems in patients relate directly to gradient strength and modulation frequency. Present designs of gradient coil tend to limit ultra-high-speed imaging methods such as echo-planar imaging (EPI) and echo-volumar imaging (EVI) because of the effect of induced currents in the patient which produce neural stimulation resulting

  6. Comparison of genetic algorithms with conjugate gradient methods

    NASA Technical Reports Server (NTRS)

    Bosworth, J. L.; Foo, N. Y.; Zeigler, B. P.

    1972-01-01

    Genetic algorithms for mathematical function optimization are modeled on search strategies employed in natural adaptation. Comparisons of genetic algorithms with conjugate gradient methods, which were made on an IBM 1800 digital computer, show that genetic algorithms display superior performance over gradient methods for functions which are poorly behaved mathematically, for multimodal functions, and for functions obscured by additive random noise. Genetic methods offer performance comparable to gradient methods for many of the standard functions.

  7. Model-reduced gradient-based history matching

    Microsoft Academic Search

    Ma?gorzata P. Kaleta; Remus G. Hanea; Arnold W. Heemink; Jan-Dirk Jansen

    2011-01-01

    Gradient-based history matching algorithms can be used to adapt the uncertain parameters in a reservoir model using production\\u000a data. They require, however, the implementation of an adjoint model to compute the gradients, which is usually an enormous\\u000a programming effort. We propose a new approach to gradient-based history matching which is based on model reduction, where\\u000a the original (nonlinear and high-order)

  8. Quasiminimal excellent classes Chains, existence, and definability

    E-print Network

    Kirby, Jonathan

    Quasiminimal excellent classes Chains, existence, and definability Conclusions On Quasiminimal Excellent Classes Jonathan Kirby University of Oxford 5th October, 2007 Jonathan Kirby Definability of Quasiminimal Excellent Classes #12;Quasiminimal excellent classes Chains, existence, and definability

  9. Supply chain management in the cement industry

    E-print Network

    Agudelo, Isabel

    2009-01-01

    Traditionally supply chain management has played an operational role within cement and mineral extraction commodity companies. Recently, cost reduction projects have brought supply chain management into the limelight. In ...

  10. Supply Chain Logistics Post Recovery Landscape

    E-print Network

    Minnesota, University of

    1 Supply Chain Logistics ­ Post Recovery Landscape Freight and Logistics Symposium Center & CEO & Past Chair Council of Supply Chain Management Professionals (CSCMP) Center For Transportation / Consumer Demands, Geographic "Mega Regions," Land Prices Impacts, Freight Security / Theft, Network Design

  11. Higher-order force gradient symplectic algorithms

    PubMed

    Chin; Kidwell

    2000-12-01

    We show that a recently discovered fourth order symplectic algorithm, which requires one evaluation of force gradient in addition to three evaluations of the force, when iterated to higher order, yielded algorithms that are far superior to similarly iterated higher order algorithms based on the standard Forest-Ruth algorithm. We gauge the accuracy of each algorithm by comparing the step-size independent error functions associated with energy conservation and the rotation of the Laplace-Runge-Lenz vector when solving a highly eccentric Kepler problem. For orders 6, 8, 10, and 12, the new algorithms are approximately a factor of 10(3), 10(4), 10(4), and 10(5) better. PMID:11138177

  12. Microfluidic quadrupole and floating concentration gradient

    PubMed Central

    Qasaimeh, Mohammad A.; Gervais, Thomas; Juncker, David

    2014-01-01

    The concept of fluidic multipoles, in analogy to electrostatics, has long been known as a particular class of solutions of the Navier-Stokes equation in potential flows, however, experimental observations of fluidic multipoles and of their characteristics have not been reported yet. Here we present a two-dimensional microfluidic quadrupole and a theoretical analysis consistent with the experimental observations. The microfluidic quadrupole was formed by simultaneously injecting and aspirating fluids from two pairs of opposing apertures in a narrow gap formed between a microfluidic probe and a substrate. A stagnation point was formed at the center of the microfluidic quadrupole, and its position could be rapidly adjusted hydrodynamically. Following the injection of a solute through one of the poles, a stationary, tunable, and movable – i.e. “floating” – concentration gradient was formed at the stagnation point. Our results lay the foundation for future combined experimental and theoretical exploration of microfluidic planar multipoles including convective-diffusive phenomena. PMID:21897375

  13. A matrix analysis of conjugate gradient algorithms

    SciTech Connect

    Ashby, S.F. [Lawrence Livermore National Lab., CA (United States); Gutknecht, M.H. [Eidgenoessische Technische Hochschule, Zurich (Switzerland)

    1993-04-01

    This paper explores the relationships between the conjugate gradient algorithms Orthodir, Orthomin, and Orthores. To facilitate this exploration, a matrix formulation for each algorithm is given. It is shown that Orthodir directly computes a Hessenberg matrix H{sub k} at step k. Orthores also computes a Hessenberg matrix, G{sub k}, which is similar to a Hessenberg matrix obtained from H{sub k} by perturbing its last column. (This perturbation vanishes at convergence.) Orthomin, on the other hand, computes a UL and LU factorization of the perturbed H{sub k} and G{sub k}, respectively. The breakdown of Orthomin and Orthores are interpreted in terms of these underlying matrix factorizations. A connection with Lanczos algorithms is also examined, as is the special case of B-normal(1) matrices (for which efficient three-term CG algorithms exist).

  14. Implementation of the phase-gradient algorithm

    NASA Astrophysics Data System (ADS)

    Wahl, Daniel E.; Eichel, Paul H.; Jakowatz, Charles V., Jr.

    1990-11-01

    The recently introduced Phase Gradient Autofocus (PGA) algorithm is a non-parametric autofocus technique which has been shown to be quite effective for phase correction of Synthetic Aperture Radar (SAR) imagery. This paper will show that this powerful algorithm can be executed at near real-ume speeds and also be implemented in a relatively small piece of hardware. A briefreview ofthe PGA wiibe presented along with an overview ofsome critical implementation considerations. In addition a demonstration of the PGA algorithm running on a 7" xlO" printed circuit board containing a TMS32OC3O digital signal pro cessing (DSP) chip wilibe given. With this system using only the 20 range bins which contain the brightest points in the image the algorithm can correct a badly degraded 256x256 image in as little as 3 seconds. Using all range bins the algorithm can correct the image in 9 seconds.

  15. Constant field gradient planar coupled cavity structure

    DOEpatents

    Kang, Yoon W. (Naperville, IL); Kustom, Robert L. (Oswego, IL)

    1999-01-01

    A cavity structure having at least two opposing planar housing members spaced apart to accommodate the passage of a particle beam through the structure between the members. Each of the housing members have a plurality of serially aligned hollows defined therein, and also passages, formed in the members, which interconnect serially adjacent hollows to provide communication between the hollows. The opposing planar housing members are spaced and aligned such that the hollows in one member cooperate with corresponding hollows in the other member to form a plurality of resonant cavities aligned along the particle beam within the cavity structure. To facilitate the obtaining of a constant field gradient within the cavity structure, the passages are configured so as to be incrementally narrower in the direction of travel of the particle beam. In addition, the spacing distance between the opposing housing members is configured to be incrementally smaller in the direction of travel of the beam.

  16. Gradient estimation in dendritic reinforcement learning

    PubMed Central

    2012-01-01

    We study synaptic plasticity in a complex neuronal cell model where NMDA-spikes can arise in certain dendritic zones. In the context of reinforcement learning, two kinds of plasticity rules are derived, zone reinforcement (ZR) and cell reinforcement (CR), which both optimize the expected reward by stochastic gradient ascent. For ZR, the synaptic plasticity response to the external reward signal is modulated exclusively by quantities which are local to the NMDA-spike initiation zone in which the synapse is situated. CR, in addition, uses nonlocal feedback from the soma of the cell, provided by mechanisms such as the backpropagating action potential. Simulation results show that, compared to ZR, the use of nonlocal feedback in CR can drastically enhance learning performance. We suggest that the availability of nonlocal feedback for learning is a key advantage of complex neurons over networks of simple point neurons, which have previously been found to be largely equivalent with regard to computational capability. PMID:22657827

  17. Passive Magnetic Shielding in Gradient Fields

    E-print Network

    Bidinosti, C P

    2013-01-01

    The effect of passive magnetic shielding on dc magnetic field gradients imposed by both external and internal sources is studied. It is found that for concentric cylindrical or spherical shells of high permeability material, higher order multipoles in the magnetic field are shielded progressively better, by a factor related to the order of the multipole. In regard to the design of internal coil systems for the generation of uniform internal fields, we show how one can take advantage of the coupling of the coils to the innermost magnetic shield to further optimize the uniformity of the field. These results demonstrate quantitatively a phenomenon that was previously well-known qualitatively: that the resultant magnetic field within a passively magnetically shielded region can be much more uniform than the applied magnetic field itself. Furthermore we provide formulae relevant to active magnetic compensation systems which attempt to stabilize the interior fields by sensing and cancelling the exterior fields clos...

  18. Error Analysis of Stochastic Gradient Descent Ranking.

    PubMed

    Chen, Hong; Tang, Yi; Li, Luoqing; Yuan, Yuan; Li, Xuelong; Tang, Yuanyan

    2012-12-31

    Ranking is always an important task in machine learning and information retrieval, e.g., collaborative filtering, recommender systems, drug discovery, etc. A kernel-based stochastic gradient descent algorithm with the least squares loss is proposed for ranking in this paper. The implementation of this algorithm is simple, and an expression of the solution is derived via a sampling operator and an integral operator. An explicit convergence rate for leaning a ranking function is given in terms of the suitable choices of the step size and the regularization parameter. The analysis technique used here is capacity independent and is novel in error analysis of ranking learning. Experimental results on real-world data have shown the effectiveness of the proposed algorithm in ranking tasks, which verifies the theoretical analysis in ranking error. PMID:23292808

  19. Error analysis of stochastic gradient descent ranking.

    PubMed

    Chen, Hong; Tang, Yi; Li, Luoqing; Yuan, Yuan; Li, Xuelong; Tang, Yuanyan

    2013-06-01

    Ranking is always an important task in machine learning and information retrieval, e.g., collaborative filtering, recommender systems, drug discovery, etc. A kernel-based stochastic gradient descent algorithm with the least squares loss is proposed for ranking in this paper. The implementation of this algorithm is simple, and an expression of the solution is derived via a sampling operator and an integral operator. An explicit convergence rate for leaning a ranking function is given in terms of the suitable choices of the step size and the regularization parameter. The analysis technique used here is capacity independent and is novel in error analysis of ranking learning. Experimental results on real-world data have shown the effectiveness of the proposed algorithm in ranking tasks, which verifies the theoretical analysis in ranking error. PMID:24083315

  20. High gradient lens for charged particle beam

    SciTech Connect

    Chen, Yu-Jiuan

    2014-04-29

    Methods and devices enable shaping of a charged particle beam. A dynamically adjustable electric lens includes a series of alternating a series of alternating layers of insulators and conductors with a hollow center. The series of alternating layers when stacked together form a high gradient insulator (HGI) tube to allow propagation of the charged particle beam through the hollow center of the HGI tube. A plurality of transmission lines are connected to a plurality of sections of the HGI tube, and one or more voltage sources are provided to supply an adjustable voltage value to each transmission line of the plurality of transmission lines. By changing the voltage values supplied to each section of the HGI tube, any desired electric field can be established across the HGI tube. This way various functionalities including focusing, defocusing, acceleration, deceleration, intensity modulation and others can be effectuated on a time varying basis.

  1. Implications of Abundance Gradients in Intracluster Gas

    E-print Network

    Raymond E. White III; Renato A. Dupke

    2000-01-18

    Analysis of spatially resolved ASCA spectra of the intracluster gas in Abell 496 confirms that metal abundances increase toward the center. We also find spatial gradients in several abundance ratios, indicating that the fraction of iron from SN Ia increases toward the cluster center. The dominant metal enrichment mechanism near the cluster center must therefore be different than in the outer parts. We show that ram pressure stripping of gas from cluster galaxies cannot account for the central abundance enhancement. We suggest that two successive stages of galactic winds contaminate intracluster gas: protogalactic winds driven by SN II, followed by less energetic winds driven by SN Ia, which have longer lived progenitors than SN II. The less energetic secondary wind from a cD galaxy may be suppressed, due to its location at the cluster center, leading to the observed central enhancement of SN Ia ejecta.

  2. Transformational acoustic metamaterials based on pressure gradients

    E-print Network

    C. García-Meca; S. Carloni; C. Barceló; G. Jannes; J. Sánchez-Dehesa; A. Martínez

    2014-09-18

    We apply a homogenization process to the acoustic velocity potential wave equation. The study of various examples shows that the resulting effective properties are different from those of the homogenized pressure wave equation for the same underlying acoustic parameters. A careful analysis reveals that a given set of inhomogeneous parameters represents an entirely different physical system depending on the considered equation. Our findings unveil a different way of tailoring acoustic properties through gradients of the static pressure. In contrast to standard metafluids based on isobaric composites, this alternative kind of metafluids is suitable for the implementation of transformational devices designed via the velocity potential equation. This includes acoustic systems in a moving background or arising from general space-time transformations. As an example, we design a device able to cloak the acoustic velocity potential.

  3. The Curlometer and Other Gradient Based Methods

    NASA Astrophysics Data System (ADS)

    Dunlop, Malcolm W.; Eastwood, Jonathan P.

    The magnetic field measurements on the four Cluster spacecraft can be combined to produce a determination of the electric current density, j, point by point in time, from Ampere's law, i.e., through an estimate of the curl of the magnetic field, B, assuming the displacement current may be neglected (an assumption nearly always true in space plasmas). This combination of spatial gradients is named the Curlometer technique, first introduced by Dunlop et al. [1988], and first used on Cluster measurements by Dunlop et al. [2002b]. Although estimates of current density from single and dual spacecraft have been attempted in the past [e.g. van Allen and Adnan, 1992] (a simple 1-D current layer, sampled from an individual spacecraft, can at least give an estimate of the current magnitude), these estimates also depend on accurate knowledge of relative orientation and motion in order to obtain positions within a current layer (the finite region where the cur- rent density is distributed). The Curlometer technique independently estimates the current vector at each time in the data stream and can be understood in a number of different ways, as outlined in Chapters 12, 14, 15, and 16 of ISSI SR-001. In using the Curlometer, a clear understanding of the associated caveats is important, the main one being that only linear estimates of B and B can be made. Multi-spacecraft analysis also depends upon temporal behaviour, and most methods assume some degree of stationarity in their interpretation. The Curlometer is an important part of the analysis of spatial gradients as measured by four spacecraft, and this general problem was addressed in part in ISSI SR- 001. A number of additional methods have since been introduced which are also based on the use of spatial gradients and we also deal briefly with these below, or reference them. The four Cluster spacecraft fly in an evolving configuration, which repeats every or- bit (apart from minor perturbations), but which has been changed at intervals during the mission to cover a large range of spacecraft separation distances (100-10,000 km) at the magnetopause and in the magnetotail. The results presented here therefore have been con- firmed over a variety of spatial scales, and have been used in a number of different investigations, and below we list those papers that have used the technique in these circumstances. Through these studies, an understanding of the applicability of the method has developed. For example, the thickness of a planar current layer can be accurately estimated from its magnetic profile at each spacecraft and the corresponding boundary crossing times; the latter also giving a determination of boundary motion relative to the Cluster array, which scales the corresponding current profile through the current layer. The estimate of electric current density can be representative even when the configuration of Cluster spacecraft approaches the thickness of the current layer and minimum variance analysis on the Curlometer measurements can estimate the current normal. The other gradient methods can be used to calculate a number of other properties, such as the dimensionality of the structure.

  4. Origin of stress gradients induced in capped, copper metallization

    SciTech Connect

    Murray, Conal E., E-mail: conal@us.ibm.com [IBM T.J. Watson Research Center, Yorktown Heights, New York 10598 (United States)

    2014-02-24

    Stress gradients generated near the top surface of Cu thin films by capping layers, as measured using a combination of conventional and glancing incidence x-ray diffraction, exhibit heterogeneous behavior that is directly related to plastic anisotropy within the Cu grains. A comparison of stress gradients measured from several x-ray reflections to their corresponding Schmid factors yields a consistent, critical resolved shear stress. The results experimentally verify that dislocation-mediated plasticity is responsible for the creation of stress gradients at the Cu film/cap interface. Depth-dependent measurements reveal that the observed gradients are localized to within 200?nm of this interface.

  5. Engineering chemoattractant gradients using controlled release polysaccharide microspheres

    E-print Network

    Wang, Yana, Ph. D. Massachusetts Institute of Technology

    2012-01-01

    Chemoattractant gradients play important roles in the normal function of immune system, from lymphocyte homeostasis to mounting efficient immune responses against infection. Improved fundamental knowledge about the role ...

  6. Generalized Defect Energy in a Gradient Plasticity Framework

    E-print Network

    Bayerschen, E

    2015-01-01

    A gradient plasticity model is presented that includes a generalized, power-law type defect energy depending on the gradient of an equivalent plastic strain. Numerical regularization for the case of vanishing gradients is employed in the finite element discretization of the theory. Three exemplary choices of the defect energy exponent are compared in finite element simulations of elastic-plastic tricrystals under tensile loading. The influence of the power-law exponent is discussed related to the distribution of gradients and in regard to size effects. In addition, an analytical solution is presented for the single slip case and allows to interpret the numerical findings.

  7. Better Mini-Batch Algorithms via Accelerated Gradient Methods

    E-print Network

    Better Mini-Batch Algorithms via Accelerated Gradient Methods Andrew Cotter Toyota Technological Toyota Technological Institute at Chicago nati@ttic.edu Karthik Sridharan Toyota Technological Institute

  8. Unconventional gradient coil designs in magnetic resonance imaging.

    PubMed

    Zhu, Minhua; Xia, Ling; Liu, Feng

    2014-01-01

    In magnetic resonance imaging (MRI), the gradient coils are used to encode the spatial positions of protons by varying the magnetic field linearly across the imaging subject. With the latest development of MRI technique and new clinical and research applications, the gradient coil system requires increasingly innovative designs. In this paper, four unconventional gradient coil designs are reviewed: (1) local gradient coils; (2) new coil configurations with reduced peripheral nerve stimulation (PNS); (3) dedicated structures designed for hybrid systems (combining MRI with other medical devices); and (4) the full 3D coil designs. For the first type, the development of local gradient coils (mainly head coils) is discussed chronologically and divided into three stages: the "golden" stage in the 1990s, the "wane" stage in the 2000s, and the "revival" stage in the 2010s. For the second type, various designs for the reduction of PNS problems have been described, including local and whole-body gradient coil systems. For the third design, a dedicated gradient coil design for multi-modality combination is illustrated with an MRI-LINAC system. Finally, gradient systems with non-layered coil structure are described in the fourth design type. We hope that this review on unconventional gradient coil designs will be useful for the new development of MRI technology and emerging medical applications. PMID:25955713

  9. Effective Gradients in Porous Media Due to Susceptibility Differences

    PubMed

    Hürlimann

    1998-04-01

    In porous media, magnetic susceptibility differences between the solid phase and the fluid filling the pore space lead to field inhomogeneities inside the pore space. In many cases, diffusion of the spins in the fluid phase through these internal inhomogeneities controls the transverse decay rate of the NMR signal. In disordered porous media such as sedimentary rocks, a detailed evaluation of this process is in practice not possible because the field inhomogeneities depend not only on the susceptibility difference but also on the details of the pore geometry. In this report, the major features of diffusion in internal gradients are analyzed with the concept of effective gradients. Effective gradients are related to the field inhomogeneities over the dephasing length, the typical length over which the spins diffuse before they dephase. For the CPMG sequence, the dependence of relaxation rate on echo spacing can be described to first order by a distribution of effective gradients. It is argued that for a given susceptibility difference, there is a maximum value for these effective gradients, gmax, that depends on only the diffusion coefficient, the Larmor frequency, and the susceptibility difference. This analysis is applied to the case of water-saturated sedimentary rocks. From a set of NMR measurements and a compilation of a large number of susceptibility measurements, we conclude that the effective gradients in carbonates are typically smaller than gradients of current NMR well logging tools, whereas in many sandstones, internal gradients can be comparable to or larger than tool gradients. Copyright 1998 Academic Press. PMID:9571098

  10. Aggregation-fragmentation model of robust concentration gradient formation

    NASA Astrophysics Data System (ADS)

    Saunders, Timothy E.

    2015-02-01

    Concentration gradients of signaling molecules are essential for patterning during development and they have been observed in both unicellular and multicellular systems. In subcellular systems, clustering of the signaling molecule has been observed. We develop a theoretical model of cluster-mediated concentration gradient formation based on the Becker-Döring equations of aggregation-fragmentation processes. We show that such a mechanism produces robust concentration gradients on realistic time and spatial scales so long as the process of clustering does not significantly stabilize the signaling molecule. Finally, we demonstrate that such a model is applicable to the pom1p subcellular gradient in fission yeast.

  11. Abundance Gradients in Clusters of Galaxies

    NASA Astrophysics Data System (ADS)

    Dupke, Renato De Alencar

    This dissertation presents the analysis of spatially resolved ASCA satellite X-ray spectra for four clusters of galaxies (Abell 496, Abell 2199, Abell 3571 and Abell 1060). The abundance distributions of Abell 496, Abell 2199 and Abell 3571 are shown to be centrally enhanced. The distribution of elemental abundance ratios, combined with calculations of supernovae rates, shows that the central abundance enhancement in these galaxy clusters is dominated by supernova, Type 1a iron, while the outer parts are dominated by supernovae Type II iron and the most likely mechanism proposed to produce this central iron is ram-pressure stripping, rather than accumulated stellar mass loss from the central dominant galaxy. At least 50% (by mass) of the iron in the central regions is from supernovae Type Ia, varying slightly from cluster to cluster. Although the analysis of Abell 1060 reveals no significant central abundance enhancement, supernovae Type Ia are shown to contribute significantly to the iron content of the central regions. However, accumulated stellar mass loss from the two central dominant galaxies in this cluster can account for all of the supernovae Type la iron in the central regions. The nickel to iron abundance ratio shows that delayed detonation explosion models for supernovae Type la are inconsistent with the observed abundance ratios in the inner regions of Abell 496, Abell 2199 and Abell 3571. A comparison of the distributions of iron mass and the luminosity of early type galaxies in four clusters, three of them having central abundance enhancements (Virgo, Abell 496 and Centaurus) and one having a flat abundance distribution (Coma), indicates that the iron mass traces the luminosity of early type galaxies in abundance gradient clusters better than in flat abundance clusters. This suggests that abundance gradients can be washed out by cluster mergers.

  12. High-gradient compact linear accelerator

    SciTech Connect

    Carder, B.M.

    1995-12-31

    A high-gradient linear accelerator comprises a solid-state stack in a vacuum of five sets of disc-shaped Blumlein modules each having a center hole through which particles are sequentially accelerated. Each Blumlein module is a sandwich of two outer conductive plates that bracket an inner conductive plate positioned between two dielectric plates with different thicknesses and dielectric constants. A third dielectric core in the shape of a hollow cylinder forms a casing down the series of center holes, and it has a dielectric constant different that the two dielectric plates that sandwich the inner conductive plate. In operation, all the inner conductive plates are charged to the same DC potential relative to the outer conductive plates. Next, all the inner conductive plates are simultaneously shorted to the outer conductive plates at the outer diameters. The signal short will propagate to the inner diameters at two different rates in each Blumlein module. A faster wave propagates quicker to the third dielectric core across the dielectric plates with the closer spacing and lower dielectric constant. When the faster wave reaches the inner extents of the outer and inner conductive plates, it reflects back outward and reverses the field in that segment of the dielectric core. All the field segments in the dielectric core are then in unipolar agreement until the slower wave finally propagates to the third dielectric core across the dielectric plates with the wider spacing and higher dielectric constant. During such unipolar agreement, particles in the core are accelerated with gradients that exceed twenty megavolts per meter.

  13. Transition delay by introducing spanwise velocity gradients

    NASA Astrophysics Data System (ADS)

    Fallenius, B. E. G.; Barckmann, K.; Fransson, J. H. M.; Grundmann, S.

    2013-11-01

    For stabilizing a boundary layer it has been shown both numerically and experimentally that the control idea of introducing steady spanwise velocity gradients is far more effective than what could be foreseen. Different devices have been analyzed experimentally, which can modulate the boundary layer in a controlled way, and so far miniature vortex generators have shown to be the most coveted for transition delay. Currently, a popular control device in the control community is the plasma actuator, which mainly has shown its potential for separation control, but lately also for transition delay. In a wind tunnel investigation at KTH, the plasma actuators have been tested in a configuration aimed at making use of above control idea and its potential for transition delay will be discussed. For stabilizing a boundary layer it has been shown both numerically and experimentally that the control idea of introducing steady spanwise velocity gradients is far more effective than what could be foreseen. Different devices have been analyzed experimentally, which can modulate the boundary layer in a controlled way, and so far miniature vortex generators have shown to be the most coveted for transition delay. Currently, a popular control device in the control community is the plasma actuator, which mainly has shown its potential for separation control, but lately also for transition delay. In a wind tunnel investigation at KTH, the plasma actuators have been tested in a configuration aimed at making use of above control idea and its potential for transition delay will be discussed. Support from the European Research Council is acknowledged.

  14. High-gradient compact linear accelerator

    DOEpatents

    Carder, B.M.

    1998-05-26

    A high-gradient linear accelerator comprises a solid-state stack in a vacuum of five sets of disc-shaped Blumlein modules each having a center hole through which particles are sequentially accelerated. Each Blumlein module is a sandwich of two outer conductive plates that bracket an inner conductive plate positioned between two dielectric plates with different thicknesses and dielectric constants. A third dielectric core in the shape of a hollow cylinder forms a casing down the series of center holes, and it has a dielectric constant different that the two dielectric plates that sandwich the inner conductive plate. In operation, all the inner conductive plates are charged to the same DC potential relative to the outer conductive plates. Next, all the inner conductive plates are simultaneously shorted to the outer conductive plates at the outer diameters. The signal short will propagate to the inner diameters at two different rates in each Blumlein module. A faster wave propagates quicker to the third dielectric core across the dielectric plates with the closer spacing and lower dielectric constant. When the faster wave reaches the inner extents of the outer and inner conductive plates, it reflects back outward and reverses the field in that segment of the dielectric core. All the field segments in the dielectric core are then in unipolar agreement until the slower wave finally propagates to the third dielectric core across the dielectric plates with the wider spacing and higher dielectric constant. During such unipolar agreement, particles in the core are accelerated with gradients that exceed twenty megavolts per meter. 10 figs.

  15. Gradient reversed-phase high-performance liquid chromatography of saturated, unsaturated and oxygenated free fatty acids and their methyl esters

    Microsoft Academic Search

    Jiann-Tsyh Lin; Thomas A. McKeon; Allan E. Stafford

    1995-01-01

    Reversed-phase C18 high-performance liquid chromatography (HPLC) separation of 49 free fatty acids and their methyl esters is reported here. Separation is achieved using methanol\\/water gradients and detection by either UV absorbance or evaporative light scattering. The factors decreasing retention times are: keto group, hydroxy group, epoxy group, triple bond, shortened chain length (C2H4 shorter), cyclopropenyl group, double bond, and cyclopropanyl

  16. Assessing the State of Supply Chain Management

    Microsoft Academic Search

    Thomas W. Speh

    The great promise of supply chain management has always been that firms working collaboratively in their respective supply\\u000a chains will be able to leverage the strong relationships that have been created to build quantum leaps in performance for\\u000a the entire supply chain. As we survey the landscape of supply chain management we do find many instances of companies who\\u000a have

  17. A market orientation in supply chain management

    Microsoft Academic Search

    Soonhong Min; John T. Mentzer; Robert T. Ladd

    2007-01-01

    Despite the logical association between market orientation (MO) and the supply chain management concepts of supply chain orientation\\u000a (SCO) and supply chain management (SCM), and the potential mediating role of SCO and SCM in the MO-firm business performance\\u000a (PERF) relationship, there have been few, if any, attempts to investigate MO in a supply chain context. Thus, this study tests\\u000a the

  18. Disaster chains initiated by the Wenchuan earthquake

    Microsoft Academic Search

    Mengzhen Xu; Zhaoyin Wang; Lijian Qi; Le Liu; Kang Zhang

    The Wenchuan earthquake caused numerous landslides and avalanches, which initiated causal chains of geological and ecological\\u000a disasters. Field investigations and field experiments were performed in the earthquake area in 2008 and 2009 to study the\\u000a disaster chains. Four types of disaster chains have been identified and seven cases have been studied. In the disaster chains,\\u000a each episode was caused by

  19. Nonlinear dynamics of electrostatic ion-temperature-gradient modes in a dust-contaminated plasma with variable charge and sheared ion flows

    SciTech Connect

    Azimi, Leila; Mirza, Arshad M.; Khan, M. Yaqub [Theoretical Plasma Physics Group, Department of Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan)

    2006-08-15

    By employing Braginskii transport equations for ions and Boltzmann distribution for electrons in a dust-contaminated plasma with equilibrium density, temperature, and magnetic field gradients, the nonlinear set of equations are derived. New ion-temperature-gradient driven modes are obtained and various limiting cases are discussed. It is shown that the ion-temperature-gradient driven mode of drift-waves are attenuated in the presence of dust-charge fluctuations. It has been found that dust charging is always dissipative and the growth rate of various modes are damped. Furthermore, the possible stationary solution of the nonlinear mode coupling equations can be represented in the form of dipolar and vortex chains type solutions. The results of the present investigation should be helpful in understanding the fluctuations and transport phenomena in magnetically confined dustcontaminated tokamak plasma.

  20. Model checking quantum Markov chains

    E-print Network

    Yuan Feng; Nengkun Yu; Mingsheng Ying

    2013-11-14

    Although the security of quantum cryptography is provable based on the principles of quantum mechanics, it can be compromised by the flaws in the design of quantum protocols and the noise in their physical implementations. So, it is indispensable to develop techniques of verifying and debugging quantum cryptographic systems. Model-checking has proved to be effective in the verification of classical cryptographic protocols, but an essential difficulty arises when it is applied to quantum systems: the state space of a quantum system is always a continuum even when its dimension is finite. To overcome this difficulty, we introduce a novel notion of quantum Markov chain, specially suited to model quantum cryptographic protocols, in which quantum effects are entirely encoded into super-operators labelling transitions, leaving the location information (nodes) being classical. Then we define a quantum extension of probabilistic computation tree logic (PCTL) and develop a model-checking algorithm for quantum Markov chains.

  1. Extending the "Knowledge Advantage": Creating Learning Chains

    ERIC Educational Resources Information Center

    Maqsood, Tayyab; Walker, Derek; Finegan, Andrew

    2007-01-01

    Purpose: The purpose of this paper is to develop a synergy between the approaches of knowledge management in a learning organisation and supply chain management so that learning chains can be created in order to unleash innovation and creativity by managing knowledge in supply chains. Design/methodology/approach: Through extensive literature…

  2. Pharmaceutical Supply Chain Networks with Outsourcing

    E-print Network

    Nagurney, Anna

    Pharmaceutical Supply Chain Networks with Outsourcing Under Price and Quality Competition Anna of Massachusetts Amherst Pharmaceutical Supply Chain Networks with Outsourcing #12;Acknowledgments This research Supply Chain Networks with Outsourcing #12;This presentation is based on the paper: Nagurney, A., Li, D

  3. The Advancement Value Chain: An Exploratory Model

    ERIC Educational Resources Information Center

    Leonard, Edward F., III

    2005-01-01

    Since the introduction of the value chain concept in 1985, several varying, yet virtually similar, value chains have been developed for the business enterprise. Shifting to higher education, can a value chain be found that links together the various activities of advancement so that an institution's leaders can actually look at the philanthropic…

  4. Geochemical Evolution of the Louisville Seamount Chain

    Microsoft Academic Search

    L. Vanderkluysen; J. J. Mahoney; A. A. Koppers; P. F. Lonsdale

    2007-01-01

    The Louisville seamount chain is a 4300 km long chain of submarine volcanoes in the southwestern Pacific that is commonly thought to represent a hotspot track. It spans an ~80 Myr age range, comparable to that of the Hawaiian-Emperor chain (Koppers et al., G-cubed, 5 (6), 2004). The few previously dredged igneous samples are dominantly basaltic and alkalic, and have

  5. Supply Chain Supernetworks Suppliers Risk Diversification

    E-print Network

    Nagurney, Anna

    Supply Chain Supernetworks with Suppliers Risk Diversification June Dong School of Business State #12;Reliable Supply Chain Starts from reliable suppliers Supplier selection multicriteria Benefits vs Market demands are elastic that are functions of market prices #12;Supply Chain Supernetwork 1 Ni 1 1 j M

  6. Inauguration de la chaire Supply Chain

    E-print Network

    Bezerianos, Anastasia

    1 Inauguration de la chaire Supply Chain de l'École Centrale Paris 27 octobre 2008, Press Club #12 Chengbin CHU Présentation des 6 partenaires Présentation du Groupement Centrale Paris Achats & Supply Chain sa chaire d'enseignement et de recherche « Supply Chain », une initiative originale soutenue par six

  7. Supply Chain Collaboration and Disruption Mitigation Capability

    Microsoft Academic Search

    Shao Xiao-Feng; Pan Yu

    2009-01-01

    Today's market is characterized by high levels of uncertainty and turbulence. Outsourcing and globalization have created longer and more complex supply chains, which are more vulnerable to business disruptions. Thus it is critical for firms to enhance supply chain disruption mitigation capabilities. This research investigates the impact of supply chain collaboration on disruption mitigation capability. Through the use of the

  8. Agents on the Web Supply Chains

    E-print Network

    Almor, Amit

    Agents on the Web Automating Supply Chains 90 JULY · AUGUST 2001 http://computer.org/internet/ 1089 M. Stephens · University of South Carolina · stephens@sc.edu A recent study found that supply-chain of which is projected to be e-commerce sales),2 it's easy to see that effective supply-chain management

  9. Information architecture for supply chain quality management

    Microsoft Academic Search

    Li Da Xu

    2011-01-01

    As quality requirements play a crucial role in supply chain management (SCM), enterprises require appropriate information architecture to address evolving supply chain needs. Information architecture for supply chain quality management has drawn much attention from the research community and the industry in recent years. Recent research explores the role of service-oriented architecture (SOA), RFID, agent, workflow management, and the Internet

  10. Triggered amplification by hybridization chain reaction

    E-print Network

    Pierce, Niles A.

    Triggered amplification by hybridization chain reaction Robert M. Dirks and Niles A. Pierce chain reaction (HCR), in which stable DNA monomers assemble only upon exposure to a target DNA fragment termed hybridization chain reaction (HCR). This class of mech- anisms suggests the possibility

  11. The Logical Chain Reaction (aka Mathematical Induction)

    E-print Network

    Pego, Robert

    The Logical Chain Reaction (aka Mathematical Induction) Robert Pego Department of Mathematical infinitum. This is the logical chain reaction -- it proves that A(n) is in fact true for every postitive an infinite chain of implications: A(1) A(2) A(3) . . . A(37) A(38) . . . ad infinitum. The fuse is set

  12. The Bullwhip Effect in Supply Chains

    Microsoft Academic Search

    Hau L Lee; V. Padmanabhan; Seungjin Whang

    1997-01-01

    The bullwhip effect occurs when the demand order variabilities in the supply chain are amplified as they moved up the supply chain. Distorted information from one end of a supply chain to the other can lead to tremendous inefficiencies. Companies can effectively counteract the bullwhip effect by thoroughly understanding its underlying causes. Industry leaders are implementing innovative strategies that pose

  13. Supply Chain and Information Sciences Technology 2010

    E-print Network

    Guiltinan, Mark

    Supply Chain and Information Sciences Technology 2010 Supply Chain and Information Systems Technology Minor SCIST Minor Application Department of Supply Chain & Information Systems College of Information Sciences and Technology Overview The minor in SCIST is structured to provide students not majoring

  14. OM386: SUPPLY CHAIN MANAGEMENT SPRING, 2012

    E-print Network

    Ghosh, Joydeep

    communication and collaboration skills. Many of the cases that we discuss involve global supply chainsOM386: SUPPLY CHAIN MANAGEMENT SPRING, 2012 Professor Professor Stephen M. Gilbert Office CBA 3) Course Objectives Supply Chain Management involves the flows of materials and information among all

  15. Benchmarking supply chain collaboration : An empirical study

    Microsoft Academic Search

    Togar M. Simatupang; Ramaswami Sridharan

    2004-01-01

    Supply chain collaboration enables firms to achieve better performance. It requires close arrangements of collaborative practices among the participating members. Searching for better practices and ideas that lead to superior performance means that the chain members also need to benchmark their current collaborative practices to other collaborative supply chains. Benchmarking enables them to identify the highest standards of excellence in

  16. An integrative framework for supply chain collaboration

    Microsoft Academic Search

    Togar M. Simatupang; Ramaswami Sridharan

    2005-01-01

    Purpose – This paper proposes an integrative framework for supply chain collaboration which is based on the reciprocal approach. Design\\/methodology\\/approach – A reciprocal approach is adopted to capture the interaction phenomenon of different features of collaboration in attaining overall supply chain performance. Findings – A collaborative supply chain framework is composed of five connecting features of collaboration, namely collaborative performance

  17. OM386: SUPPLY CHAIN MANAGEMENT SPRING, 2013

    E-print Network

    Ghosh, Joydeep

    communication and collaboration skills. Many of the cases that we discuss involve global supply chainsOM386: SUPPLY CHAIN MANAGEMENT SPRING, 2013 Professor Professor Stephen M. Gilbert Office CBA 3) Course Objectives Supply Chain Management involves the flows of materials and information among all

  18. Performance measurement in humanitarian relief chains

    Microsoft Academic Search

    Benita M. Beamon; Burcu Balcik

    2008-01-01

    Purpose – The purpose of this paper is to compare performance measurement in the humanitarian relief chain with performance measurement in the commercial supply chain, develop performance metrics for the humanitarian relief chain, and present a framework that can be used as a basis for a performance measurement system in the relief sector. Design\\/methodology\\/approach – The performance measurement analysis is

  19. HUMANITARIAN RELIEF CHAINS: ISSUES AND CHALLENGES

    Microsoft Academic Search

    Benita M. Beamon

    The objectives of this paper are to define, compare and contrast the commercial supply chain and the humanitarian relief chain, discuss an approach to performance measurement in the domain of humanitarian relief, and identify the challenges faced by relief chain logisticians in practice and research.

  20. Planning for Disruptions in Supply Chain Networks

    Microsoft Academic Search

    Lawrence V. Snyder; Maria P. Scaparra; Mark S. Daskin; Richard L. Church

    Recent events have highlighted the need for planners to consider the risk of disruptions when designing supply chain networks. Supply chain disruptions have a number of causes and may take a number of forms. Once a disruption occurs, there is very little recourse regarding supply chain infrastructure because these strategic decisions can- not be changed quickly. Therefore, it is critical

  1. Optimal supply chain configurations in semiconductor manufacturing

    Microsoft Academic Search

    David Chiang; Ruey-Shan Guo; Argon Chen; Meng-Tse Cheng; Cheng-Bang Chen

    2007-01-01

    As a semiconductor supply chain becomes widespread and the competition pressure is very fierce, the detrimental effects of increasing varieties and variations are magnified in the supply chain. But many important issues, such as different service priorities, adaptability, controllability and scalability of performance metrics, have not been addressed in the literature. Conventional modelling techniques of supply chain operations are no

  2. Supply chain agent decision aid system (SCADAS)

    Microsoft Academic Search

    Anurag Gupta; Larry Whitman; Ramesh K. Agarwal

    2001-01-01

    Supply chain decisions are improved with access to global information. However, supply chain partners are frequently hesitant to provide full access to all the information within an enterprise. A mechanism to make decisions based on global information without complete access to that information is required for improved supply chain decision making. Mobile agents can support this requirement and these are

  3. Cold Chain Equipment Planning with CCEM

    E-print Network

    Anderson, Richard

    1/24/2011 1 Cold Chain Equipment Planning with CCEM Richard Anderson, Sophie Newland, John Lloyd, David Lubinski, Stefano Malvolti, John Wecker, Kate Wilson Cold Chain Equipment Planning with CCEM January 4, 2011 Vaccine Introduction Timeline Cold Chain Equipment Manager 2 IVAC VIMS report, March 2010

  4. SINGULARLY PERTURBED FINITE MARKOV CHAINS WITH GENERAL

    E-print Network

    Avrachenkov, Konstantin

    SINGULARLY PERTURBED FINITE MARKOV CHAINS WITH GENERAL ERGODIC STRUCTURE Konstantin E. Avrachenkov.avrachenkov@sophia.inria.fr Keywords: Finite Markov chains, singular perturbations, asymptotic power series. Abstract We analyse singularly perturbed Markov chains. Most previous research has been done under the assumption

  5. Supply Chain Analysis Center for Transportation Analysis

    E-print Network

    exchange and in-transit visibility; Security analysis for supply chains; Business case analysis can in-transit visibility be enhanced? What can be done to increase security in the supply chainSupply Chain Analysis Center for Transportation Analysis 2360 Cherahala Boulevard Knoxville, TN

  6. Supply Chain Security Management: an overview

    Microsoft Academic Search

    Juha Hintsa; Ximena Gutierrez; Philip Wieser; Ari-Pekka Hameri

    2009-01-01

    Supply Chain Security Management (SCSM) is a relatively new discipline in the field of Operations Management Research, thus lacking introductory and tutorial papers. The recent concerns on security in global supply chains are driving the introduction of new security initiatives, standards and measures to such an extent that they are becoming an integral part of supply chain management. This paper

  7. An empirical investigation into supply chain vulnerability

    Microsoft Academic Search

    Stephan M. Wagner; Christoph Bode

    2006-01-01

    A growing number of academicians and practitioners have put supply chain risks on their agendas, particularly triggered by a recent series of catastrophic events that have disrupted economies and supply chains around the globe. Given the increasing awareness of this important topic, the purpose of this research was to study supply chain risks in more detail and to investigate the

  8. Finite subcategories and heredity chains Bangming Deng

    E-print Network

    Bielefeld, University of

    Finite subcategories and heredity chains Bangming Deng Department of Mathematics, Beijing Normal and define left and right splitting filtrations of S. Heredity chains of A S associated--modules and obtained in this way a heredity chain of ideals of A(\\Lambda). In the present paper we deal with finite

  9. Stretch the Chain and See the Light

    NSDL National Science Digital Library

    2012-06-26

    In this activity, learners use their strength to light a light bulb. A chain made from paper clips is placed in series with a battery and flashlight bulb. When the chain is stretched, the light bulb glows brighter. The explanation lies in decreased electrical resistance due to better contact between the paper clips as the chain is stretched.

  10. Environmental Correlates of Food Chain Length

    Microsoft Academic Search

    Frederic Briand; Joel E. Cohen

    1987-01-01

    In 113 community food webs from natural communities, the average and maximal lengths of food chains are independent of primary productivity, contrary to the hypothesis that longer food chains should arise when more energy is available at their base. Environmental variability alone also does not appear to constrain average or maximal chain length. Environments that are three dimensional or solid,

  11. Food Supply Chains with Vertical Integration

    E-print Network

    Nagurney, Anna

    Food Supply Chains with Vertical Integration SOM 822 Research Paper Diogo Souza-Monteiro Dep. of Resource Economics 05/10/2004 #12;Introduction Food Supply chains are becoming increasingly complex in different tiers of food chains. Barkena and Drabenstott (1995) claim that contracts are quickly taking

  12. [Mitochondrial disorders associated with mitochondrial respiratory chain complex V deficiency].

    PubMed

    Li, Xi-Yuan; Yang, Yan-Ling

    2013-07-01

    The mammalian mitochondrial ATP synthase, also as known as mitochondrial respiratory chain complex V, is a large protein complex located in the mitochondrial inner membrane, where it catalyzes ATP synthesis from ADP, Pi, and Mg2+ at the expense of an electrochemical gradient of protons generated by the electron transport chain. Complex V is composed of 2 functional domains F0 and F1. The clinical features of patients are significantly heterogeneous depending on the involved organs. Most patients with complex V deficiency had clinical onset in the neonatal period with severe brain damage or multi-organ failure resulting in a high mortality. Neuromuscular disorders, cardiomyopathy, lactic acidosis and 3-methylglutaconic aciduria are common findings. Complex V consists of 16 subunits encoded by both mitochondrial DNA and nuclear DNA. On MT-ATP6, MT-ATP8, ATPAF2, TMEM70 and ATP5E gene of mitochondrial DNA, many mutations associated with Complex V deficiency have been identified. Here, the pathology, clinical features, diagnosis, treatment and molecular genetics of Complex V deficiency were summarized. PMID:23866288

  13. BranchedChain Amino Acids

    Microsoft Academic Search

    Miroslav Pátek

    The branched-chain amino acids (BCAAs) leucine, isoleucine, and valine are synthesized by bacteria,\\u000a fungi, and plants, but are essential for vertebrates including humans, who must receive them from their\\u000a diet. The interest to construct overproducing industrial strains therefore stems from the need to supplement\\u000a the food or feed with these amino acids to use them in medical treatment and as

  14. Thermal Entanglement in Ferrimagnetic Chains

    E-print Network

    Xiaoguang Wang; Z. D. Wang

    2006-04-13

    A formula to evaluate the entanglement in an one-dimensional ferrimagnetic system is derived. Based on the formula, we find that the thermal entanglement in a small size spin-1/2 and spin-s ferrimagnetic chain is rather robust against temperature, and the threshold temperature may be arbitrarily high when s is sufficiently large. This intriguing result answers unambiguously a fundamental question: ``can entanglement and quantum behavior in physical systems survive at arbitrary high temperatures?"

  15. Normalized full gradient of full tensor gravity gradient based on adaptive iterative Tikhonov regularization downward continuation

    NASA Astrophysics Data System (ADS)

    Zhou, Wenna

    2015-07-01

    Normalized full gradient (NFG) method depends on the downward continuation of NFG values of gravity data. In this paper, I deduce an improved NFG method of full tensor gravity gradient (FTG) data by using x-, y- and z-directional analytic signals of FTG data. During the calculation, I introduce the adaptive iterative Tikhonov regularization downward continuation method in the calculation process to improve the stability of the NFG method. The new approach is tested on various model data with and without noise, and satisfactory results are obtained. It demonstrates that the new NFG method of FTG can improve the lateral resolution and describe the gravity bodies in more detail. In addition, the method is applied to a real field FTG data acquired over the Vinton Salt Dome, Louisiana, USA. All results demonstrate that the new method can accurately detect the depth of the geologic sources while providing enhanced information of the sources simultaneously.

  16. Deletions in immunoglobulin mu chains.

    PubMed Central

    Köhler, G; Potash, M J; Lehrach, H; Shulman, M J

    1982-01-01

    Eight mutant hybridoma lines are described, which synthesize short immunoglobulin mu chains. Four internal deletions were mapped by Southern blot analysis. They are shown to remove DNA from either part or all of the first, and first and second, constant mu exons. The sizes of the deletions range between 0.6 and 5 kb, leaving an equal or unequal number of splice signals. Shorter mu RNA of one size was found irrespective of whether an exon was completely or only partially deleted. These results preclude exclusive 3' (constant region) to 5' (variable region) directional splicing of the mu RNA. No important signals seem to reside in the deleted DNA stretches affecting the transcription or the correct RNA splicing of the remaining exons. The internal mu protein deletions revealed unusual covalent light chain attachment demonstrating functional homology between the first (normally used) and fourth mu constant domain. The other mu protein deletions (10, 11, and 12 kd) involved neither gross DNA nor RNA lesions and are considered to be due to premature chain termination. Since secretion is found in most of the mutant IgM-producing lines, no single one of the four mu constant domains (including the C-terminal one which contains the so-called secretory piece) is necessary for secretion. Images Fig. 1. Fig. 2. Fig. 3. Fig. 4. Fig. 5. Fig. 6. PMID:6329690

  17. An E-commerce Based Supply Chain Model of Chain Catering Enterprises

    Microsoft Academic Search

    Weijie Guo; Huan Qi; Qiujun Guo

    2009-01-01

    By means of comparing the traditional and e-commerce based supply chain of chain catering enterprises, a mathematical model of the latter is given. This model is built according to costs and profits, combined with characters of supply chain of chain catering and the merits of e-commerce. By quantizing factors of all concerns, the corresponding equations are given. The optimization method

  18. Alternative spring force law for bead-spring chain models of the worm-like chain

    E-print Network

    Doyle, Patrick S.

    Alternative spring force law for bead-spring chain models of the worm-like chain Patrick T We have developed a new spring force law which can be used in bead-spring chain models of the worm The Society of Rheology. DOI: 10.1122/1.2206713 I. INTRODUCTION The worm-like chain WLC model has been used

  19. ""Leap FrogLeap Frog"" TechnologiesTechnologies for Supply Chain andfor Supply Chain and

    E-print Network

    Cheyer, Adam

    Pg 1 ""Leap FrogLeap Frog"" TechnologiesTechnologies for Supply Chain andfor Supply ChainProgram Director, AI Center SRI InternationalSRI International At theAt the JAMPRO Supply Chain Management SymposiumJAMPRO Supply Chain Management Symposium November 18, 2005November 18, 2005 #12;Pg 2 BioBio ­­ Adam

  20. On geoid heights derived from GEOS 3 altimeter data along the Hawaiian-Emperor seamount chain

    NASA Technical Reports Server (NTRS)

    Watts, A. B.

    1979-01-01

    The geoid heights derived from preliminary GEOS 3 satellite radar altimeter data over the Hawaiian-Emperor seamount chain are examined. Two objectives are pursued: (1) to evaluate the contribution of the topography of the seamount chain and its compensation to the marine geoid; and (2) to determine whether geoid heights derived from GEOS 3 altimeter data can be used to provide information on isostasy at geological features such as the Hawaiian-Emperor seamount chain which formed as relatively young loads on the oceanic lithosphere. Short-wavelength geoid highs of 5-12 m over the crest of the seamount chain and geoid lows over flanking regions are observed. The geological undulations can be explained by a simple model in which the seamount-chain load is supported by a strong rigid lithospheric plate. The elastic thickness estimates agree with values based on surface ship gravity and bathymetry observations, and provide further support to the hypothesis that the elastic thickness acquired at a surface load depends on the temperature gradient of the lithosphere at the time of loading.