Sample records for chain reaction-denaturing gradient

  1. Application of polymerase chain reaction-denaturing gradient gel electrophoresis for comparison of direct and indirect extraction methods of soil DNA used for microbial community fingerprinting

    Microsoft Academic Search

    J. Kozdrój; J. D. van Elsas

    2000-01-01

    We used polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) to compare bacterial community patterns\\u000a obtained with target DNA extracted from a soil by direct and indirect methods. For this purpose, two direct extraction methods,\\u000a i.e. cell lysis by bead beating and cell disruption by grinding in liquid N, and two indirect methods, i.e. cell extraction\\u000a followed by DNA extraction, and

  2. Effectiveness of Denaturation Temperature Gradient-Polymerase Chain Reaction for Biased DNAAlgorithms*

    E-print Network

    Effectiveness of Denaturation Temperature Gradient- Polymerase Chain Reaction for Biased algorithm to solve the graph problems with weighted edges was investigated [1]. A temperature-gradient based temperature (Tm): the denaturation temperature gradient-polymerase chain reaction (DTG

  3. 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. In a previous study, we introduced denaturation temperature gradient polymerase chain reaction (DTG- PCR, -T, Zhang, Temperature gradient-based DNA computing for graph problems with weighted edges, Lecture

  4. Positive correlation between aortic valve pressure gradient and mitochondrial respiratory chain capacity in hypertrophied human left ventricle

    Microsoft Academic Search

    I. Maurer; S. Zierz

    1992-01-01

    The effect of chronic left ventricular pressure overload on the activities of mitochondrial respiratory chain enzymes was investigated in myocardial biopsies from the left ventricular apex of 13 patients undergoing aortic valve replacement for aortic valve stenosis. Transvalvular pressure gradients measured by left-sided heart catheterization ranged from 52 to 100 mmHg. The specific activity of mitochondrial respiratory chain enzyme complexes

  5. Decrease in fungal biodiversity along an available phosphorous gradient in arable Andosol soils in Japan.

    PubMed

    Bao, Zhihua; Matsushita, Yuko; Morimoto, Sho; Hoshino, Yuko Takada; Suzuki, Chika; Nagaoka, Kazunari; Takenaka, Makoto; Murakami, Hiroharu; Kuroyanagi, Yukiko; Urashima, Yasufumi; Sekiguchi, Hiroyuki; Kushida, Atsuhiko; Toyota, Koki; Saito, Masanori; Tsushima, Seiya

    2013-06-01

    Andosols comprise one of the most important soil groups for agricultural activities in Japan because they cover about 46.5% of arable upland fields. In this soil group, available phosphorus (P) is accumulated by application of excessive fertilizer, but little is known about the influence of increasing P availability on microbial community diversity at large scales. We collected soil samples from 9 agro-geographical sites with Andosol soils across an available P gradient (2048.1-59.1 mg P2O5·kg(-1)) to examine the influence of P availability on the fungal community diversity. We used polymerase chain reaction - denaturing gradient gel electrophoresis to analyze the fungal communities based on 18S rRNA genes. Statistical analyses revealed a high negative correlation between available P and fungal diversity (H'). Fungal diversity across all sites exhibited a significant hump-shaped relationship with available P (R(2) = 0.38, P < 0.001). In addition, the composition of the fungal community was strongly correlated with the available P gradient. The ribotype F6, which was positively correlated with available P, was closely related to Mortierella. The results show that both the diversity and the composition of the fungal community were influenced by available P concentrations in Andosols, at a large scale. This represents an important step toward understanding the processes responsible for the maintenance of fungal diversity in Andosolic soils. PMID:23750950

  6. 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

  7. Comparison of bacterial community changes in fermenting kimchi at two different temperatures using a denaturing gradient gel electrophoresis analysis.

    PubMed

    Hong, Yeun; Yang, Hee-Seok; Chang, Hae-Choon; Kim, Hae-Yeong

    2013-01-01

    A polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) technique followed by sequencing of the 16S rDNA fragments eluted from the bands of interest on denaturing gradient gels was used to monitor changes in the bacterial microflora of two commercial kimchi, salted cabbage, and ingredient mix samples during 30 days of fermentation at 4°C and 10°C. Leuconostoc (Lc.) was the dominant lactic acid bacteria (LAB) over Lactobacillus (Lb.) species at 4°C. Weissella confusa was detected in the ingredient mix and also in kimchi samples throughout fermentation in both samples at 4°C and 10°C. Lc. gelidum was detected as the dominant LAB at 4°C in both samples. The temperature affected the LAB profile of kimchi by varing the pH, which was primarily caused by the temperature-dependent competition among different LAB species in kimchi. At 4°C, the sample variations in pH and titratable acidity were more conspicuous owing to the delayed growth of LAB. Temperature affected only initial decreases in pH and initial increases in viable cell counts, but affected both the initial increases and final values of titratable acidity. The initial microflora in the kimchi sample was probably determined by the microflora of the ingredient mix, not by that of the salted cabbage. The microbial distributions in the samples used in this study resembled across the different kimchi samples and the different fermentation temperatures as the numbers of LAB increased and titratable acidity decreased. PMID:23314371

  8. Mutation analyses of KRAS exon 1 comparing three different techniques: temporal temperature gradient electrophoresis, constant denaturant capillaryelectrophoresis and allele specific polymerase chain reaction

    Microsoft Academic Search

    Jens Bjørheim; Sigrid Lystad; Annika Lindblom; Ulf Kressner; Sophia Westring; Siobhan Wahlberg; Gudrun Lindmark; Gustav Gaudernack; Per Ekstrøm; Janne Røe; William G. Thilly; Anne-Lise Børresen-Dale

    1998-01-01

    Mutations in the KRAS gene is a key event in the carcinogenesis of many human cancers and may serve as a diagnostic marker and a target for therapeutic intervention. In this study we have applied three different techniques for mutation detection of KRAS exon 1 mutations: Allele specific polymerase chain reaction (AS-PCR), temporal temperature gradient electrophoresis (TTGE) and constant denaturant

  9. 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

  10. Quantitative determination of human cytomegalovirus target sequences in peripheral blood leukocytes by nested polymerase chain reaction and temperature gradient gel electrophoresis

    Microsoft Academic Search

    P. Schafer; Riidiger W. Braun; K. Mohring; Karsten Henco; Jie Kang; Thomas Wendland; J. E. Kuhn

    1993-01-01

    A competitive nested PCR-temperature gradient gel electrophoresis protocol (nPCR\\/TGGE) has been es- tablished for the quantification of human cytomegalo- virus (HCMV) target sequences. The measurement was achieved by co-amplification of a defined copy number of an internal standard (st) and separation of st and wild- type (wt) amplimers by temperature gradient gel electro- phoresis (TGGE). The number of HCMV target

  11. 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

  12. Neural Approximations and the Algebra of Gradients

    NASA Astrophysics Data System (ADS)

    Pacut, A.

    2003-12-01

    We characterize neural networks as approximators of functions and dynamic systems. Neural approximations, leading to nonlinear minimization in highly dimensional spaces, require effective gradient calculation typically realized by gradient backpropagation. We discuss the use of gradient backpropagation for static and for dynamic systems. We also show the essential difference between the common chain rule and backpropagation, which is rarely acknowledged.

  13. Successional changes in the genetic diversity of a marine bacterial assemblage during confinement

    Microsoft Academic Search

    Hendrik Schäfer; Pierre Servais; Gerard Muyzer

    2000-01-01

    The successional changes in the genetic diversity of Mediterranean bacterioplankton subjected to confinement were studied in an experimental 300 l seawater enclosure. Five samples were taken at different times and analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) fingerprinting to rapidly monitor changes in the bacterial genetic diversity. DGGE analysis clearly showed variations between the samples. Three of the

  14. 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

  15. 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

  16. Succession and phylogenetic composition of eubacterial communities in rice straw during decomposition on the surface of paddy field soil

    Microsoft Academic Search

    Naoko Asari; Rie Ishihara; Yasunori Nakajima; Makoto Kimura; Susumu Asakawa

    2007-01-01

    To estimate the bacterial communities in rice straw left on the soil surface of paddy fields, polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis was conducted. Rice straw samples were placed on the soil surface in a Japanese paddy field under drained conditions after harvest and under flooded conditions after the transplanting of rice. The residual samples on the soil

  17. 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.

  18. Linear gradient copolymer melt brushes

    NASA Astrophysics Data System (ADS)

    Pickett, Galen T.

    2003-02-01

    I consider a brush of gradient polymers, with the chains anchored at their pure A ends with the chemical composition changing linearly along the chain up to the untethered chain tips whose composition is pure B. Demixing of the A and B monomers results in the creation of a thermally-controllable zone from which free ends are excluded. For high temperatures, the zone is small and located near the grafting surface, but for lower temperatures the zone extends throughout the layer, giving a physical manifestation of an Alexander brush. This conclusion is supported by both scaling and numerical self-consistent field calculations.

  19. Irradiance gradients

    SciTech Connect

    Ward, G.J. (Lawrence Berkeley Lab., CA (United States) Ecole Polytechnique Federale, Lausanne (Switzerland)); Heckbert, P.S. (Carnegie-Mellon Univ., Pittsburgh, PA (United States). School of Computer Science Technische Hogeschool Delft (Netherlands). Dept. of Technical Mathematics and Informatics)

    1992-04-01

    A new method for improving the accuracy of a diffuse interreflection calculation is introduced in a ray tracing context. The information from a hemispherical sampling of the luminous environment is interpreted in a new way to predict the change in irradiance as a function of position and surface orientation. The additional computation involved is modest and the benefit is substantial. An improved interpolation of irradiance resulting from the gradient calculation produces smoother, more accurate renderings. This result is achieved through better utilization of ray samples rather than additional samples or alternate sampling strategies. Thus, the technique is applicable to a variety of global illumination algorithms that use hemicubes or Monte Carlo sampling techniques.

  20. Interactions of Bubbles in a Temperature Gradient

    Microsoft Academic Search

    Huailiang Wei

    1994-01-01

    A theoretical and experimental investigation of the hydrodynamic interactions of bubbles in the presence of a temperature gradient has been performed. Both theory and experiment correspond to motion at negligible values of the Reynolds and Peclet numbers so that convective transport of momentum and energy is unimportant. In the theoretical models, the thermocapillary migration of a small chain of spherical

  1. Food Chain

    NSDL National Science Digital Library

    2011-08-15

    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.

  2. 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 ...

  3. 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,

  4. Assessment of the diversity, and antagonism towards Rhizoctonia solani AG3, of Pseudomonas species in soil from different agricultural regimes

    Microsoft Academic Search

    Paolina Garbeva; Johannes Antonie van Veen; Jan Dirk van Elsas

    2004-01-01

    The genus Pseudomonas is one of the best-studied bacterial groups in soil, and includes numerous species of environmental interest. Pseudomonas species play key roles in soil, for instance in biological control of soil-borne plant pathogens and in bioremediation of pollutants. A polymerase chain reaction-denaturing gradient gel electrophoresis system that specifically describes the diversity of Pseudomonas spp. in soil was developed.

  5. Succession and phylogenetic profile of eukaryotic communities in rice straw incorporated into a rice field: Estimation by PCR-DGGE and sequence analyses

    Microsoft Academic Search

    Atsuo Sugano; Hidetaka Tsuchimoto; Cho Cho Tun; Susumu Asakawa; Makoto Kimura

    2007-01-01

    Succession and the phylogenetic profile of eukaryotic communities associated with rice straw decomposition in a rice field were studied using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis followed by 18S rDNA sequencing. Nylon mesh bags containing leaf sheaths or blades were buried in the plow layer of a rice field under flooded conditions after transplanting (Experiment 1) and under

  6. Spin chains with electrons in Penning traps

    E-print Network

    G. Ciaramicoli; I. Marzoli; P. Tombesi

    2007-03-22

    We demonstrate that spin chains are experimentally feasible using electrons confined in micro-Penning traps, supplemented with local magnetic field gradients. The resulting Heisenberg-like system is characterized by coupling strengths showing a dipolar decay. These spin chains can be used as a channel for short distance quantum communication. Our scheme offers high accuracy in reproducing an effective spin chain with relatively large transmission rate.

  7. TEMPERATURE GRADIENTS AND GLACIATION

    E-print Network

    Jones, Peter JS

    TEMPERATURE GRADIENTS AND GLACIATION Chris Brierley & Alexey Fedorov #12;Outline Recap on the warm gradients Heat Transfer Process Meridional SST Grad Zonal SST Grad Surface Temperature -3.2 oC -0.8 oC Water early Pliocene (as we have reconstructed it) Methodology to compare meridional SST gradient impacts

  8. 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

  9. Modelling the Bicoid gradient

    PubMed Central

    Grimm, Oliver; Coppey, Mathieu; Wieschaus, Eric

    2010-01-01

    Morphogen gradients provide embryonic tissues with positional information by inducing target genes at different concentration thresholds and thus at different positions. The Bicoid morphogen gradient in Drosophila melanogaster embryos has recently been analysed quantitatively, yet how it forms remains a matter of controversy. Several biophysical models that rely on production, diffusion and degradation have been formulated to account for the observed dynamics of the Bicoid gradient, but no one model can account for all its characteristics. Here, we discuss how existing data on this gradient fit the various proposed models and what aspects of gradient formation these models fail to explain. We suggest that knowing a few additional parameters, such as the lifetime of Bicoid, would help to identify and develop better models of Bicoid gradient formation. PMID:20570935

  10. Optimization in gradient networks.

    PubMed

    Gulbahce, Natali

    2007-06-01

    Gradient networks can be used to model the dominant structure of complex networks. Previous work has focused on random gradient networks. Here we study gradient networks that minimize jamming on substrate networks with scale-free and Erdos-Renyi structure. We introduce structural correlations and strongly reduce congestion occurring on the network by using a Monte Carlo optimization scheme. This optimization alters the degree distribution and other structural properties of the resulting gradient networks. These results are expected to be relevant for transport and other dynamical processes in real network systems. PMID:17614692

  11. Electron Temperature Gradient Turbulence

    Microsoft Academic Search

    W. Dorland; F. Jenko; M. Kotschenreuther; B. N. Rogers

    2000-01-01

    The first toroidal, gyrokinetic, electromagnetic simulations of small scale plasma turbulence are presented. The turbulence considered is driven by gradients in the electron temperature. It is found that electron temperature gradient (ETG) turbulence can induce experimentally relevant thermal losses in magnetic confinement fusion devices. For typical tokamak parameters, the transport is essentially electrostatic in character. The simulation results are qualitatively

  12. Multilayer Gradient Coil Design

    PubMed

    Bowtell; Robyr

    1998-04-01

    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 wires are allowed to spread out into multiple layers wound at increasing radii, a more favorable scaling of resistance with efficiency is achieved, thus allowing the design of more powerful gradient coils with acceptable resistance values. By extending the theory used to design standard cylindrical gradient coils, we have developed mathematical expressions which allow the design of multilayer coils, and the evaluation of their performance. These expressions have been used to design a four-layer, z-gradient coil of 8 mm inner diameter, which has an efficiency of 1.73 Tm-1 A-1, a resistance of 1.8 Omega, and an inductance of 50 µH. This coil produces a gradient which deviates from linearity by less than 5% within a central cylindrical region of 4.5 mm length and 4.5 mm diameter. A coil has been constructed from this design and tested in simple imaging and pulsed gradient spin echo experiments. The resulting data verify the predicted coil performance, thus demonstrating the advantages of using multilayer coils for experiments requiring very large magnetic field gradients. Copyright 1998 Academic Press. PMID:9571104

  13. 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

  14. Random gradient index metamaterials

    Microsoft Academic Search

    Ruopeng Liu; Chunlin Ji; J. J. Mock; Tiejun Cui; David R. Smith

    2008-01-01

    We report a broadband reflectionless gradient random medium design and experimental implementation by using metamaterial technology. This gradient random medium matches the impedance of the air and gradually change its refraction index randomly, creating a puzzle for wave propagation in front of a metal conductor. Thus, such type of coating is expected to diffuse the reflection waves from a conductor

  15. NIF optics phase gradient specfication

    SciTech Connect

    Williams, W.; Auerbach, J.; Hunt, J.; Lawson, L.; Manes, K.; Orth, C.; Sacks, R.; Trenholme, J.; Wegner, P.

    1997-05-02

    A root-mean-square (rms) phase gradient specification seems to allow a good connection between the NIP optics quality and focal spot requirements. Measurements on Beamlet optics individually, and as a chain, indicate they meet the assumptions necessary to use this specification, and that they have a typical rms phase gradient of {approximately}80 {angstrom}/cm. This may be sufficient for NIP to meet the proposed Stockpile Stewardship Management Program (SSMP) requirements of 80% of a high- power beam within a 200-250 micron diameter spot. Uncertainties include, especially, the scale length of the optics phase noise, the ability of the adaptive optic to correct against pump-induced distortions and optics noise, and the possibility of finding mitigation techniques against whole-beam self-focusing (e.g. a pre- correction optic). Further work is needed in these areas to better determine the NIF specifications. This memo is a written summary of a presentation on this topic given by W. Williams 24 April 1997 to NIP and LS&T personnel.

  16. Gradient Driven Fluctuations

    NASA Technical Reports Server (NTRS)

    Cannell, David

    2005-01-01

    We have worked with our collaborators at the University of Milan (Professor Marzio Giglio and his group-supported by ASI) to define the science required to measure gradient driven fluctuations in the microgravity environment. Such a study would provide an accurate test of the extent to which the theory of fluctuating hydrodynamics can be used to predict the properties of fluids maintained in a stressed, non-equilibrium state. As mentioned above, the results should also provide direct visual insight into the behavior of a variety of fluid systems containing gradients or interfaces, when placed in the microgravity environment. With support from the current grant, we have identified three key systems for detailed investigation. These three systems are: 1) A single-component fluid to be studied in the presence of a temperature gradient; 2) A mixture of two organic liquids to be studied both in the presence of a temperature gradient, which induces a steady-state concentration gradient, and with the temperature gradient removed, but while the concentration gradient is dying by means of diffusion; 3) Various pairs of liquids undergoing free diffusion, including a proteidbuffer solution and pairs of mixtures having different concentrations, to allow us to vary the differences in fluid properties in a controlled manner.

  17. 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.

  18. Temperature-gradient oven

    NASA Technical Reports Server (NTRS)

    Jue, S.

    1979-01-01

    Tubular oven operates on principle of lengthwise linear temperature gradient of homogeneous conductive rod in absence of radiative or convective heat loss. Oven can be applied to controlled heating or cooling of test specimens.

  19. Accelerated gradient projection

    Microsoft Academic Search

    Henry J. Kelley; Jason L. Speyer

    A version of the gradient projection algorithm is proposed for use with nonlinear constraints. Compatibility with the Davidon\\u000a process is examined and arguments on terminal phase convergence are given.

  20. 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

  1. 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.

  2. Gradient critical phenomena in the Ising quantum chain: surface behaviour

    E-print Network

    Boyer, Edmond

    , France Abstract. We consider the influence of a power-law deviation from the critical coupling even be suppressed. Besides this, the presence of spatially varying external fields (magnetic, gravitational or thermal) also influences the critical properties of a system. The effect of gravity on phase

  3. Gradient enhanced spectroscopy

    NASA Astrophysics Data System (ADS)

    van Zijl, Peter C.; Hurd, Ralph E.

    2011-12-01

    This paper provides a brief overview of the personal recollections of the authors regarding their contributions to the introduction of shielded gradient technology into NMR spectroscopy during the late 1980s and early 1990s. It provides some background into early probe design and details some of the early technical progress with the use of shielded magnetic field gradients for coherence selection in high resolution NMR and describes the developments at General Electric, the National Institutes of Health, Georgetown University and Johns Hopkins University School of Medicine that ultimately led to this technology becoming commonplace in modern NMR spectroscopy. Most of this early technical work was published in the Journal of Magnetic Resonance.

  4. 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.

  5. Manipulating the Gradient

    ERIC Educational Resources Information Center

    Gaze, Eric C.

    2005-01-01

    We introduce a cooperative learning, group lab for a Calculus III course to facilitate comprehension of the gradient vector and directional derivative concepts. The lab is a hands-on experience allowing students to manipulate a tangent plane and empirically measure the effect of partial derivatives on the direction of optimal ascent. (Contains 7…

  6. 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)

  7. Tumbling dynamics of isolated polymer chains in strong shear flows and the effects of chain resolution

    NASA Astrophysics Data System (ADS)

    Larson, Ronald; Saha Dalal, Indranil; Albaugh, Alex; Hoda, Nazish

    2012-02-01

    Using Brownian dynamics simulations, without hydrodynamic and excluded volume interactions, on polymer chain models encompassing a wide range of resolutions, we present a detailed investigation on the behavior of isolated chains in shear flow. We find a highly non-monotonic behavior for all models, with chain compression occurring at ultra-high shear rates that is consistent with the recent simulation studies. However, results obtained using highly refined models, with resolutions lower than a Kuhn step, reveal that this transition is an artifact of the level of chain discretization. Also, our results clearly indicate that, at high shear rates, the chain thickness in the shear-gradient direction is independent of the chain length, which differ from previously reported scaling law. We show that the chain thickness is fixed by the distance a sub-section of the chain can diffuse in the shear-gradient direction before convection stretches it out and suppresses further diffusion. Simple physical arguments are then used to derive the correct scaling laws for the coil width and the tumbling time at high shear rates. We believe that our findings presented here will provide the foundation for a better understanding of this basic problem in polymer dynamics.

  8. 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 ...

  9. 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 ...

  10. Stress-gradient plasticity

    PubMed Central

    Chakravarthy, Srinath S.; Curtin, W. A.

    2011-01-01

    A new model, stress-gradient plasticity, is presented that provides unique mechanistic insight into size-dependent phenomena in plasticity. This dislocation-based model predicts strengthening of materials when a gradient in stress acts over dislocation source–obstacle configurations. The model has a physical length scale, the spacing of dislocation obstacles, and is validated by several levels of discrete-dislocation simulations. When incorporated into a continuum viscoplastic model, predictions for bending and torsion in polycrystalline metals show excellent agreement with experiments in the initial strengthening and subsequent hardening as a function of both sample-size dependence and grain size, when the operative obstacle spacing is proportional to the grain size. PMID:21911403

  11. Gradient Particle Magnetohydrodynamics

    E-print Network

    Jason L. Maron; Gregory G. Howes

    2001-07-24

    We introduce Gradient Particle Magnetohydrodynamics (GPM), a new Lagrangian method for magnetohydrodynamics based on gradients corrected for the locally disordered particle distribution. The development of a numerical code for MHD simulation using the GPM algorithm is outlined. Validation tests simulating linear and nonlinear sound waves, linear MHD waves, advection of magnetic fields in a magnetized vortex, hydrodynamical shocks, and three-dimensional collapse are presented, demonstrating the viability of an MHD code using GPM. The characteristics of a GPM code are discussed and possible avenues for further development and refinement are mentioned. We conclude with a view of how GPM may complement other methods currently in development for the next generation of computational astrophysics.

  12. 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 ...

  13. Fast image processing on chain board of inverted tooth chain

    NASA Astrophysics Data System (ADS)

    Liu, Qing-min; Li, Guo-fa

    2007-12-01

    Discussed ordinary image processing technology of inverted tooth chain board, including noise reduction, image segmentation, edge detection and contour extraction etc.. Put forward a new kind of sub-pixel arithmetic for edge orientation of circle. The arithmetic first did edge detection to image by Canny arithmetic, so as to enhance primary orientation precision of edge, then calculated gradient direction, and then interpolated gradient image (image that was detected by Sobel arithmetic) along gradient direction, last obtained sub-pixel orientation of edge. Performed two kinds of least-square fitting methods for line edge to getting its sub-pixel orientation, from analysis and experiments, the orientation error of improved least-square linear fitting method was one quarter of ordinary least-square linear fitting error under small difference of orientation time. The sub-pixel orientation of circle made resolution of CCD increase 42 tines, which enhanced greatly orientation precision of image edge. For the need of quick on-line inspection next step, integrated the whole environment containing image preprocess, Hough conversion of line, setting orientation & direction of image, sub-pixel orientation of line and circle, output of calculation result. The whole quick processing course performed without operator, processing tine of single part is less than 0.3 second. The sub-pixel orientation method this paper posed fits precision orientation of image, and integration calculation method ensure requirement of quick inspection, and lays the foundations for on-line precision visual measurement of image.

  14. 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 is gratefully acknowledged. #12;Pharmaceutical Supply Chain Networks with Outsourcing Nagurney, Li, and Nagurney

  15. 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 systems. Keywords: microfluidics; temperature gradient focusing; kinematic dispersion; Taylor, in particular, microfluidic temperature gradient focusing. Temperature gradient focusing, hereafter `TGF' (Ross

  16. 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.

  17. Energy in density gradient

    E-print Network

    Vranjes, J

    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 cylindric 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 ...

  18. Density Gradient Stabilization of Electron Temperature Gradient Driven Turbulence in a Spherical Tokamak

    E-print Network

    Princeton Plasma Physics Laboratory

    Density Gradient Stabilization of Electron Temperature Gradient Driven Turbulence in a Spherical experimental observation of density gradient stabilization of electron temperature gradient driven turbulence electron mode (TEM), and electron temperature gradient (ETG) mode, could drive microturbulence, a major

  19. Nanoparticle manipulation by thermal gradient

    PubMed Central

    2012-01-01

    A method was proposed to manipulate nanoparticles through a thermal gradient. The motion of a fullerene molecule enclosed inside a (10, 10) carbon nanotube with a thermal gradient was studied by molecular dynamics simulations. We created a one-dimensional potential valley by imposing a symmetrical thermal gradient inside the nanotube. When the temperature gradient was large enough, the fullerene sank into the valley and became trapped. The escaping velocities of the fullerene were evaluated based on the relationship between thermal gradient and thermophoretic force. We then introduced a new way to manipulate the position of nanoparticles by translating the position of thermostats with desirable thermal gradients. Compared to nanomanipulation using a scanning tunneling microscope or an atomic force microscope, our method for nanomanipulation has a great advantage by not requiring a direct contact between the probe and the object. PMID:22364240

  20. 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

  1. Tectorial Membrane Stiffness Gradients

    PubMed Central

    Richter, Claus-Peter; Emadi, Gulam; Getnick, Geoffrey; Quesnel, Alicia; Dallos, Peter

    2007-01-01

    The mammalian inner ear processes sound with high sensitivity and fine resolution over a wide frequency range. The underlying mechanism for this remarkable ability is the “cochlear amplifier”, which operates by modifying cochlear micromechanics. However, it is largely unknown how the cochlea implements this modification. Although gradual improvements in experimental techniques have yielded ever-better descriptions of gross basilar membrane vibration, the internal workings of the organ of Corti and of the tectorial membrane have resisted exploration. Although measurements of cochlear function in mice with a gene mutation for ?-tectorin indicate the tectorial membrane's key role in the mechanoelectrical transformation by the inner ear, direct experimental data on the tectorial membrane's physical properties are limited, and only a few direct measurements on tectorial micromechanics are available. Using the hemicochlea, we are able to show that a tectorial membrane stiffness gradient exists along the cochlea, similar to that of the basilar membrane. In artificial perilymph (but with low calcium), the transversal and radial driving point stiffnesses change at a rate of –4.0 dB/mm and ?4.9 dB/mm, respectively, along the length of the cochlear spiral. In artificial endolymph, the stiffness gradient for the transversal component was –3.4 dB/mm. Combined with the changes in tectorial membrane dimensions from base to apex, the radial stiffness changes would be able to provide a second frequency-place map in the cochlea. Young's modulus, which was obtained from measurements performed in the transversal direction, decreased by ?2.6 dB/mm from base to apex. PMID:17496047

  2. Single polymer gating of channels under a solvent gradient

    E-print Network

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

    2013-10-28

    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 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 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 whilst the behavior of long chains is studied using transfer matrix techniques. The distribution of the monomer density across the layer suggests that a gate-like effect can be created, with potential applications as a sensor.

  3. The energy flow of discrete extended gradient systems

    NASA Astrophysics Data System (ADS)

    Slijep?evi?, Siniša

    2013-07-01

    We study the energy flow of spatially discrete, extended gradient systems (infinite lattices), allowing the total energy to be infinite and considering formally gradient dynamics. We show that in spatial dimensions 1,2, the flow is for almost all times arbitrarily close to the set of equilibria, and in dimensions ?3, the size of the set with non-equilibrium dynamics for a positive density of times is two dimensions less than the space dimension. The theory applies to first- and second-order dynamics of elastic chains in a periodic or polynomial potential, chains with interactions beyond the nearest neighbour, deterministic dynamics of spin glasses, the discrete complex Ginzburg-Landau equation, and others. In particular, we apply the theory to show the existence of coarsening dynamics for a class of generalized Frenkel-Kontorova models in bistable potential.

  4. Geothermal gradient map of Colorado

    SciTech Connect

    Repplier, F.N.; Fargo, R.L.

    1981-01-01

    Reported bottom hole temperatures (BHT) were taken from 12,000 oil and gas wells provided by the Colorado Oil and Gas Conservation Commission files. Average annual surface temperatures were subtracted from the BHT and then divided by the depth to give a gradient. To eliminate as many sources of error as possible, the gradient values were averaged for each township and contoured.

  5. Variable metric conjugate gradient methods

    Microsoft Academic Search

    Teri Barth; Thomas Manteuffel

    1994-01-01

    1.1 Motivation. In this paper we present a framework that includes many well known iterative methods for the solution of nonsymmetric linear systems of equations, Ax = b. Section 2 begins with a brief review of the conjugate gradient method. Next, we describe a broader class of methods, known as projection methods, to which the conjugate gradient (CG) method and

  6. technology offer Magnetic Gradient Sensor

    E-print Network

    Szmolyan, Peter

    The invention concerns a sensor for the magnetic field gradient and applies micromechanical structures. Lorentz-forces Lorentz-forces which excite specific vibration modes. Fig 1: Working principle of the magnetic gradient · Position sensing with magnetic elements · Angular measurement with permanent magnets Status Labor prototype

  7. 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

  8. 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.

  9. The impact of supply chain strategies on supply chain integration

    Microsoft Academic Search

    Qi Yi-nan; Chu Zhao-fang

    2009-01-01

    While supply chain strategies and supply chain integration have attracted considerable academic and practical attention and supply chain integration have been accepted as a better way to achieve supply chain success, there is still a need to understand how supply chain integration is linked with supply chain strategies. The literature shows some studies in what influence supply chain integration and

  10. Gradient zone boundary control in salt gradient solar ponds

    DOEpatents

    Hull, John R. (Downers Grove, IL)

    1984-01-01

    A method and apparatus for suppressing zone boundary migration in a salt gradient solar pond includes extending perforated membranes across the pond at the boundaries, between the convective and non-convective zones, the perforations being small enough in size to prevent individual turbulence disturbances from penetrating the hole, but being large enough to allow easy molecular diffusion of salt thereby preventing the formation of convective zones in the gradient layer. The total area of the perforations is a sizable fraction of the membrane area to allow sufficient salt diffusion while preventing turbulent entrainment into the gradient zone.

  11. Smiling Gurken gradient: An expansion of the Gurken gradient.

    PubMed

    Wang, Pei-Yu; Chang, Wei-Ling; Pai, Li-Mei

    2008-01-01

    Morphogen gradients provide unique positional information within a tissue. Cells that are sensitive to the concentration of the morphogen integrate this signal and develop an appropriately distinct cell fate. A morphogen gradient is usually generated by a restricted source and shaped by the speed of diffusion and stability of the signaling molecule. In addition, the availability of receptor and Heparan Sulfate Proteoglycans (HSPGs) help to shape the gradient. We have shown that overexpression of Dally-like protein (Dlp) causes an expansion of Gurken distribution and a loss of cell fates which are specified by high levels of epidermal growth factor receptor (Egfr) signaling. In this article, we discuss how D-Cbl mediated Egfr endocytosis and the levels of Dlp affect the shape of the Gurken gradient. PMID:18820480

  12. High field gradient particle accelerator

    DOEpatents

    Nation, John A. (Ithaca, NY); Greenwald, Shlomo (Haifa, IL)

    1989-01-01

    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. 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.

  13. 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.

  14. Exploring supply chain innovation

    Microsoft Academic Search

    Jan Stentoft Arlbjørn; Henning de Haas; Kristin Balslev Munksgaard

    2011-01-01

    Supply chain management promises competitive advantages for industrial organizations. The introduction of new products and\\u000a services, or entry into new markets, is likely to be more successful if accompanied by innovative supply chain designs, innovative\\u000a supply chain management practices, and enabling technology. This is a widely accepted premise in business practice today.\\u000a However, systematic research and knowledge about supply chain

  15. Food Chain Game

    NSDL National Science Digital Library

    Lawrence Hall of Science

    1979-01-01

    In this outdoor game, learners role play populations linked in a food chain. The resource suggests a chain with plant, grasshopper, frog, and hawk, but other food chains can be role-played, for example plankton, anchovy, salmon, sea lion. The more "animals" (learners!) the merrier for this active game.

  16. NUFinancials Supply Chain

    E-print Network

    Shull, Kenneth R.

    NUFinancials Supply Chain FMS807 Managing Employee Expense Reports & Advances 11/26/2013- RB © 2013;NUFinancials Supply Chain FMS807 Managing Employee Expense Reports & Advances 11/26/2013- RB © 2013 Supply Chain FMS807 Managing Employee Expense Reports & Advances 11/26/2013- RB © 2013 Northwestern

  17. NUFinancials Supply Chain

    E-print Network

    Shull, Kenneth R.

    NUFinancials Supply Chain FMS803 Non-Catalog Special Requisition: Grant Subcontract 02 consultant@northwestern.edu #12;NUFinancials Supply Chain FMS803 Non-Catalog Special Requisition: Grant Years #12;NUFinancials Supply Chain FMS803 Non-Catalog Special Requisition: Grant Subcontract 02

  18. NUFinancials Supply Chain

    E-print Network

    Shull, Kenneth R.

    NUFinancials Supply Chain FMS803 Non-Catalog Special Requisition: Blanket 02/17/2014 © 2014-491-HELP (4357) or email consultant@northwestern.edu #12;NUFinancials Supply Chain FMS803 Non Navigation: eProcurement Create Requisition 1. Define Requisition #12;NUFinancials Supply Chain FMS803 Non

  19. Measuring supply chain performance

    Microsoft Academic Search

    Benita M. Beamon

    1999-01-01

    The process of choosing appropriate supply chain performance measures is difficult due to the complexity of these systems. The paper presents an overview and evaluation of the performance measures used in supply chain models and also presents a framework for the selection of performance measurement systems for manufacturing supply chains. Three types of performance measures are identified as necessary components

  20. NUFinancials Supply Chain

    E-print Network

    Shull, Kenneth R.

    NUFinancials Supply Chain FMS801 Modify Hosted Items in a Shopping Cart 01/01/2011, vlr © 2011 Support Center at 847-491-HELP (4357) or email consultant@northwestern.edu #12;NUFinancials Supply Chain Step 1: Retrieve shopping cart(s) Navigation: home/shop page #12;NUFinancials Supply Chain FMS801

  1. NUFinancials Supply Chain

    E-print Network

    Shull, Kenneth R.

    NUFinancials Supply Chain FMS807 Requesting an Advance 2/5/2014 - rb © 2014 Northwestern University. #12;NUFinancials Supply Chain FMS807 Requesting an Advance 2/5/2014 - rb © 2014 Northwestern;NUFinancials Supply Chain FMS807 Requesting an Advance 2/5/2014 - rb © 2014 Northwestern University FMS807 3

  2. NUFinancials Supply Chain

    E-print Network

    Shull, Kenneth R.

    NUFinancials Supply Chain FMS803 Re-Open a Canceled Requisition 06/30/2008 © 2008 Northwestern Support Center at 847-491-HELP (4357or email consultant@northwestern.edu #12;NUFinancials Supply Chain FMS requisition Navigation: eProcurement Manage Requisitions #12;NUFinancials Supply Chain FMS803 Re

  3. NUFinancials Supply Chain

    E-print Network

    Shull, Kenneth R.

    NUFinancials Supply Chain FMS807 Common Errors for Expense Transactions 1/26/2009 © 2009-491-HELP (4357) or email consultant@northwestern.edu #12;NUFinancials Supply Chain FMS807 Common Errors must be entered. #12;NUFinancials Supply Chain FMS807 Common Errors for Expense Transactions 1

  4. Safe Chain Saw Operation.

    E-print Network

    Nelson, Gary S.

    1982-01-01

    Z TA24S.7 8873 NO.1409 B-1409 SAFE CHAIN SAW OPERATION Gary S. Nelson* A chain saw is a portable power cutting machine. Used properly, it will trim or cut down trees, clear land or cut fireplace wood. Improperly used, a chain saw can...

  5. Accelerated Stochastic Gradient Method for Composite Regularization

    E-print Network

    Kaski, Samuel

    Accelerated Stochastic Gradient Method for Composite Regularization Leon Wenliang Zhong James T theoretical convergence rate, it may be even slower than stochastic gradient descent in practice [21]. 1086 #12;Accelerated Stochastic Gradient Method for Composite Regularization To handle a combination

  6. Formation of the bicoid morphogen gradient: an mRNA gradient dictates the protein gradient

    PubMed Central

    Spirov, Alexander; Fahmy, Khalid; Schneider, Martina; Frei, Erich; Noll, Markus; Baumgartner, Stefan

    2009-01-01

    Summary The Bicoid (Bcd) protein gradient is generally believed to be established in pre-blastoderm Drosophila embryos by the diffusion of Bcd protein after translation of maternal mRNA, which serves as a strictly localized source of Bcd at the anterior pole. However, we previously published evidence that the Bcd gradient is preceded by a bcd mRNA gradient. Here, we have revisited and extended this observation by showing that the bcd mRNA and Bcd protein gradient profiles are virtually identical at all times. This confirms our previous conclusion that the Bcd gradient is produced by a bcd mRNA gradient rather than by diffusion. Based on our observation that bcd mRNA colocalizes with Staufen (Stau), we propose that the bcd mRNA gradient forms by a novel mechanism involving quasi-random active transport of a Stau-bcd mRNA complex through a nonpolar microtubular network, which confines the bcd mRNA to the cortex of the embryo. PMID:19168676

  7. Study of translational dynamics in molten polymer by variation of gradient pulse-width of PGSE.

    PubMed

    Stepišnik, Janez; Lahajnar, Gojmir; Zupan?i?, Ivan; Mohori?, Aleš

    2013-11-01

    Pulsed gradient spin echo is a method of measuring molecular translation. Changing ? makes it sensitive to diffusion spectrum. Spin translation effects the buildup of phase structure during the application of gradient pulses as well. The time scale of the self-diffusion measurement shortens if this is taken into account. The method of diffusion spectrometry with variable ? is also less sensitive to artifacts caused by spin relaxation and internal gradient fields. Here the method is demonstrated in the case of diffusion spectrometry of molten polyethylene. The results confirm a model of constraint release in a system of entangled polymer chains as a sort of tube Rouse motion. PMID:24051201

  8. Effect of Gradient Sequencing on Copolymer Order?Disorder Transitions: Phase Behavior of Styrene/n-Butyl Acrylate Block and Gradient Copolymers

    SciTech Connect

    Mok, Michelle M.; Ellison, Christopher J.; Torkelson, John M. (NWU); (UMM)

    2012-11-14

    We investigate the effect of gradient sequence distribution in copolymers on order-disorder transitions, using rheometry and small-angle X-ray scattering to compare the phase behavior of styrene/n-butyl acrylate (S/nBA) block and gradient copolymers. Relative to block sequencing, gradient sequencing increases the molecular weight necessary to induce phase segregation by over 3-fold, directly consistent with previous predictions from theory. Results also suggest the existence of both upper and lower order-disorder transitions in a higher molecular weight S/nBA gradient copolymer, made accessible by the shift in order-disorder temperatures from gradient sequencing. The combination of transitions is speculated to be inaccessible in S/nBA block copolymer systems due to their overlap at even modest molecular weights and also their location on the phase diagram relative to the polystyrene glass transition temperature. Finally, we discuss the potential impacts of polydispersity and chain-to-chain monomer sequence variation on gradient copolymer phase segregation.

  9. Thermalization and temperature distribution in a driven ion chain

    E-print Network

    G. -D. Lin; L. -M. Duan

    2010-01-25

    We study thermalization and non-equilibrium dynamics in a dissipative quantum many-body system -- a chain of ions with two points of the chain driven by thermal bath under different temperature. Instead of a simple linear temperature gradient as one expects from the classical heat diffusion process, the temperature distribution in the ion chain shows surprisingly rich patterns, which depend on the ion coupling rate to the bath, the location of the driven ions, and the dissipation rates of the other ions in the chain. Through simulation of the temperature evolution, we show that these unusual temperature distribution patterns in the ion chain can be quantitatively tested in experiments within a realistic time scale.

  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. Understanding the Chain Fountain

    E-print Network

    Biggins, John Simeon

    2013-01-01

    If a chain is initially at rest in a beaker at a height h1 above the ground, and the end of the chain is pulled over the rim of the beaker and down towards the ground and then released, the chain will spontaneously "flow" out of the beaker under gravity. Furthermore, if h1 is sufficient, the beads do not simply drag over the edge of the beaker but form a fountain reaching a height h2 above it. We show that the formation of a fountain requires that the beads come into motion not only by being pulled upwards by the part of the chain immediately above the pile, but also by being pushed upwards by an anomalous reaction force from the pile of stationary chain. We propose possible origins for this force, argue that its magnitude will be proportional to the square of the chain velocity, and predict and verify experimentally that h2 is proportional to h1.

  12. The Value Chain

    NSDL National Science Digital Library

    From Industry Week, The Value Chain is an online publication providing up-to-date information, articles, and resources on value chain management (VCM), a theory of management that considers every step of manufacturing a product, from raw materials "right down to disposing of the packaging after use." Along with feature articles and columns about value chain management, the site also contains a FAQ, which offers excellent basic advice about VCM, a New Roundup Weblog of breaking VCM news, and short research pieces.

  13. Neuron Chain Tag

    NSDL National Science Digital Library

    2012-06-26

    In this outdoor activity, learners play a game of Tag to discover how neurons attach themselves to each other to form a chain. The game starts with one learner who is "it" and represents the first neuron. When "it" tags another player, the tagger player must hold the hand of "it" and work together to form a long a chain. The game ends when all the players are part of the neuron chain.

  14. 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

  15. 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.

  16. Oxidation in a temperature gradient

    SciTech Connect

    Holcomb, Gordon R.; Covino, Bernard S., Jr.; Russell, James H.

    2001-01-01

    The effects of a temperature gradient and heat flux on point defect diffusion in protective oxide scales were examined. Irreversible thermodynamics were used to expand Fick's first law of diffusion to include a heat flux term--a Soret effect. Oxidation kinetics were developed for the oxidation of cobalt and for nickel doped with chromium. Research in progress is described to verify the effects of a heat flux by oxidizing pure cobalt in a temperature gradient above 800 C, and comparing the kinetics to isothermal oxidation. The tests are being carried out in the new high temperature gaseous corrosion and corrosion/erosion facility at the Albany Research Center.

  17. The Supply Chain & Operations

    E-print Network

    Massachusetts at Lowell, University of

    management we provide students with the broad range of skills necessary for success. Our Mission: The Manning that Supply Chain and Operations Management field growing and changing at a very fast pace. More and moreThe Supply Chain & Operations Management Concentration The Manning School of Business www.uml.edu/management

  18. Coordinated supply chain management

    Microsoft Academic Search

    Douglas J. Thomas; Paul M. Griffin

    1996-01-01

    Historically, the three fundamental stages of the supply chain, procurement, production and distribution, have been managed independently, buffered by large inventories. Increasing competitive pressures, and market globalization are forcing firms to develop supply chains that can quickly respond to customer needs. To remain competitive, these firms must reduce operating costs while continuously improving customer service. With recent advances in communications

  19. Chain Reaction Polymerization.

    ERIC Educational Resources Information Center

    McGrath, James E.

    1981-01-01

    The salient features and importance of chain-reaction polymerization are discussed, including such topics as the thermodynamics of polymerization, free-radical polymerization kinetics, radical polymerization processes, copolymers, and free-radical chain, anionic, cationic, coordination, and ring-opening polymerizations. (JN)

  20. Corrosion in a Temperature Gradient

    Microsoft Academic Search

    Bernard S. Covino; Gordon R. Holcomb; Stephen D. Cramer; Sophie J. Bullard; Margaret Ziomek-Moroz

    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

  1. caesar preprint Gradient Flow Registration

    E-print Network

    Rumpf, Martin

    caesar preprint Gradient Flow Registration A Streaming Implementation in DX9 Graphics Hardware Robert Strzodka, Marc Droske, Martin Rumpf Document info: Type: Preprint Group: caesar-smm Preprint ID IMPLEMENTATION IN DX9 GRAPHICS HARDWARE R. Strzodka research center caesar, D-53111 Bonn strzodka@caesar.de M

  2. Slow motion of gradient flows

    Microsoft Academic Search

    Felix Otto; Maria G. Reznikofiy

    2007-01-01

    We present sufficient conditions on an energy landscape in order for the associated gradient flow to exhibit slow motion or “dynamic metastability.” The first condition is a weak form of convexity transverse to the so-called slow manifold, N. The second condition is that the energy restricted to N is Lipschitz with a constant ??1. One feature of the abstract result

  3. 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.

  4. Gas Exchange, Partial Pressure Gradients,

    E-print Network

    Riba Sagarra, Jaume

    Gas Exchange, Partial Pressure Gradients, and the Oxygen Window Johnny E. Brian, Jr., M affect the precise gas exchange occurring in individual areas of the lungs and body tissues. To make of circulatory and gas transport physiology, and the best place to start is with normobaric physiology. LIFE

  5. stochastic gradient descent nonlinear transformation

    E-print Network

    Abu-Mostafa, Yaser S.

    ÁØ³× ÙÒ Ð ÓÙØ Ø Ö stochastic gradient descent nonlinear transformation overfitting data snooping deterministic noise noisy targets bias-variance tradeoff RBF SVM weight decay regularization soft supervised online active neural networks RBF nearest neighbors SVD linear SVM aggregation input processing

  6. Variable metric conjugate gradient methods

    SciTech Connect

    Barth, T.; Manteuffel, T.

    1994-07-01

    1.1 Motivation. In this paper we present a framework that includes many well known iterative methods for the solution of nonsymmetric linear systems of equations, Ax = b. Section 2 begins with a brief review of the conjugate gradient method. Next, we describe a broader class of methods, known as projection methods, to which the conjugate gradient (CG) method and most conjugate gradient-like methods belong. The concept of a method having either a fixed or a variable metric is introduced. Methods that have a metric are referred to as either fixed or variable metric methods. Some relationships between projection methods and fixed (variable) metric methods are discussed. The main emphasis of the remainder of this paper is on variable metric methods. In Section 3 we show how the biconjugate gradient (BCG), and the quasi-minimal residual (QMR) methods fit into this framework as variable metric methods. By modifying the underlying Lanczos biorthogonalization process used in the implementation of BCG and QMR, we obtain other variable metric methods. These, we refer to as generalizations of BCG and QMR.

  7. 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.

  8. Analysis of Bacterial Communities in Seagrass Bed Sediments by Double-Gradient Denaturing Gradient Gel Electrophoresis

    E-print Network

    Sherman, Tim

    -Gradient Denaturing Gradient Gel Electrophoresis of PCR-Amplified 16S rRNA Genes J.B. James1 , T.D. Sherman2 and R denaturing gradient gel electrophoresis (DG- DGGE) was used to generate banding patterns from

  9. A 2-CHAIN CAN INTERLOCK WITH AN OPEN 11-CHAIN

    E-print Network

    O'Rourke, Joseph

    A 2-CHAIN CAN INTERLOCK WITH AN OPEN 11-CHAIN JULIE GLASS, BIN LU, JOSEPH O'ROURKE, AND JIANYUAN K-chain can interlock with a flexible 2-chain. It was conjectured in [3] that the minimal k satisfies 6 k 11 this result to k 11 by proving that a flexible 2-chain can interlock with a flexible, open 11-chain. We offer

  10. The Apparel Global Value Chain

    E-print Network

    Richardson, David

    The Apparel Global Value Chain ECONOMIC UPGRADING AND WORKFORCE DEVELOPMENT Karina Fernandez CENTER on GLOBALIZATION, GOVERNANCE & COMPETITIVENESS #12;The Apparel Global Value Chain: Economic Upgrading and Workforce Development "Skills for Upgrading: Workforce Development and Global Value Chains

  11. 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 Upgrading and Workforce Development "Skills for Upgrading: Workforce Development and Global Value Chains

  12. 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.

  13. Porosity gradients in marine sediments

    E-print Network

    Mahmood, Khalid

    1990-01-01

    of Department) May 1990 ABSTRACT Porosity Gradients in Marine Sediments. (May 1990) Khalid Mahmood, B. Sc. , Punjab University; M. Sc. , Punjab University Chair of Advisory Committee: Dr. William R. Bryant Porosity versus depth profiles from over 110..., are composition (lithology and texture) and effective stress. Dedicated to Safia Khalid ACKNOWLEDGEMENTS The author greatly acknowledges the assistance and guidance of the chairman of his Graduate committee, Dr. W. R. Bryant, who provided the incentives...

  14. Generalized Gradient Approximation Made Simple

    Microsoft Academic Search

    John P. Perdew; Kieron Burke; Matthias Ernzerhof

    1996-01-01

    Generalized gradient approximations (GGA'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

  15. On the structure of gradient Yamabe solitons

    E-print Network

    Huai-Dong Cao; Xiaofeng Sun; Yingying Zhang

    2011-09-22

    We show that every complete nontrivial gradient Yamabe soliton admits a special global warped product structure with a one-dimensional base. Based on this, we prove a general classification theorem for complete nontrivial locally conformally flat gradient Yamabe solitons.

  16. 40 CFR 230.25 - Salinity gradients.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...OF DISPOSAL SITES FOR DREDGED OR FILL MATERIAL Potential Impacts on Physical and Chemical Characteristics of the Aquatic Ecosystem § 230.25 Salinity gradients. (a) Salinity gradients form where salt water from the ocean meets and mixes with...

  17. 40 CFR 230.25 - Salinity gradients.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...OF DISPOSAL SITES FOR DREDGED OR FILL MATERIAL Potential Impacts on Physical and Chemical Characteristics of the Aquatic Ecosystem § 230.25 Salinity gradients. (a) Salinity gradients form where salt water from the ocean meets and mixes with...

  18. 40 CFR 230.25 - Salinity gradients.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...OF DISPOSAL SITES FOR DREDGED OR FILL MATERIAL Potential Impacts on Physical and Chemical Characteristics of the Aquatic Ecosystem § 230.25 Salinity gradients. (a) Salinity gradients form where salt water from the ocean meets and mixes with...

  19. 40 CFR 230.25 - Salinity gradients.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...OF DISPOSAL SITES FOR DREDGED OR FILL MATERIAL Potential Impacts on Physical and Chemical Characteristics of the Aquatic Ecosystem § 230.25 Salinity gradients. (a) Salinity gradients form where salt water from the ocean meets and mixes with...

  20. 40 CFR 230.25 - Salinity gradients.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...OF DISPOSAL SITES FOR DREDGED OR FILL MATERIAL Potential Impacts on Physical and Chemical Characteristics of the Aquatic Ecosystem § 230.25 Salinity gradients. (a) Salinity gradients form where salt water from the ocean meets and mixes with...

  1. 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 ...

  2. 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.

  3. Atomic Chain Electronics

    NASA Technical Reports Server (NTRS)

    Yamada, Toshishige; Saini, Subhash (Technical Monitor)

    1998-01-01

    Adatom chains, precise structures artificially created on an atomically regulated surface, are the smallest possible candidates for future nanoelectronics. Since all the devices are created by combining adatom chains precisely prepared with atomic precision, device characteristics are predictable, and free from deviations due to accidental structural defects. In this atomic dimension, however, an analogy to the current semiconductor devices may not work. For example, Si structures are not always semiconducting. Adatom states do not always localize at the substrate surface when adatoms form chemical bonds to the substrate atoms. Transport properties are often determined for the entire system of the chain and electrodes, and not for chains only. These fundamental issues are discussed, which will be useful for future device considerations.

  4. 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.

  5. 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.

  6. European supply chain study

    E-print Network

    Puri, Mohitkumar

    2009-01-01

    Introduction: Supply chain management has been defined as, "..a set of approaches utilized to efficiently integrate suppliers, manufacturers, warehouses and stores, so that merchandise is produced and distributed at the ...

  7. 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.

  8. Supply chain dynamics

    E-print Network

    Barbosa, Ricardo Wagner Lopes, 1976-

    2003-01-01

    The strong bargaining power of major retailers and the higher requirements for speed, service excellence and customization have significantly contributed to transform the Supply Chain Management. These increasing challenges ...

  9. Heavy Chain Diseases

    MedlinePLUS

    ... Resources for Help and Information The One-Page Merck Manual of Health Medical Terms Conversion Tables Manuals available ... Significance (MGUS) Multiple Myeloma Macroglobulinemia Heavy Chain Diseases Merck Manual > Patients & Caregivers > Blood Disorders > Plasma Cell Disorders 4 ...

  10. 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

  11. 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.

  12. Polymerase Chain Reaction

    NSDL National Science Digital Library

    Polymerase chain reaction (PCR) enables researchers to produce millions of copies of a specific DNA sequence in approximately two hours. This automated process bypasses the need to use bacteria for amplifying DNA. This animation from Cold Spring Harbor Laboratory's Dolan DNA Learning Center presents Polymerase Chain Reaction through a series of illustrations of the processes involved. Users may view the animation online (Flash is required) or download it for PC or Mac.

  13. OSCILLATIONS AND CONCENTRATIONS IN SEQUENCES OF GRADIENTS

    E-print Network

    OSCILLATIONS AND CONCENTRATIONS IN SEQUENCES OF GRADIENTS By Agnieszka Kalamajska and Martin Kruz of Young measures to describe oscillations and concentrations in sequences of gradients, { uk}, bounded attempt to characterize both oscillations and concentrations in sequences of gradients is due to Fonseca

  14. Photopolymerization in Microfluidic Gradient Generators: Microscale

    E-print Network

    be achieved by tuning the crosslinker-concentration profile. Materials with gradients in crosslinker concentration that extend over several centimeters or millimeters can be generated easily using a gradient ma precursor solution with a defined gradient in the crosslinker concentration. Previously, we re- ported

  15. 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

  16. Privacy-Preserving Gradient-Descent Methods

    Microsoft Academic Search

    Shuguo Han; Wee Keong Ng; Li Wan; Vincent C. S. Lee

    2010-01-01

    Gradient descent is a widely used paradigm for solving many optimization problems. Gradient descent aims to minimize a target function in order to reach a local minimum. In machine learning or data mining, this function corresponds to a decision model that is to be discovered. In this paper, we propose a preliminary formulation of gradient descent with data privacy preservation.

  17. Natural Gradient Works Efficiently in Learning

    Microsoft Academic Search

    Shun-ichi Amari

    1998-01-01

    When a parameter space has a certain underlying structure, the ordinary gradient of a function does not represent its steepest direction, but the natural gradient does. Information geometry is used for calculating the natural gradients in the parameter space of perceptrons, the space of ma- trices (for blind source separation), and the space of linear dynamical systems (for blind source

  18. 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 by electron temperature gradient ETG streamers is sufficiently large and sensitive with respect to the normalized electron temperature gradient to represent a possible cause for electron temperature profile

  19. Protein gradient films of fibroin and gelatine.

    PubMed

    Claussen, Kai U; Lintz, Eileen S; Giesa, Reiner; Schmidt, Hans-Werner; Scheibel, Thomas

    2013-10-01

    Gradients are a natural design principle in biological systems that are used to diminish stress concentration where materials of differing mechanical properties connect. An interesting example of a natural gradient material is byssus, which anchors mussels to rocks and other hard substrata. Building upon previous work with synthetic polymers and inspired by byssal threads, protein gradient films are cast using glycerine-plasticized gelatine and fibroin exhibiting a highly reproducible and smooth mechanical gradient, which encompasses a large range of modulus from 160 to 550?MPa. The reproducible production of biocompatible gradient films represents a first step towards medical applications. PMID:23894133

  20. The Global Supply Chain Institute

    E-print Network

    Tennessee, University of

    The 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 is a world- class resource for global supply chain expertise. This one-stop shop offers a comprehensive menu

  1. Welcome from the Supply Chain

    E-print Network

    Minnesota, University of

    Welcome from the Council of Supply Chain Management Professionals #12;What is CSCMP? Your annually to a student in the supply chain field of study · Two students are also awarded attendance Join CSCMP? · To enhance your supply chain management career ·To become a more effective supply chain

  2. Interim Director Supply Chain Management

    E-print Network

    Habib, Ayman

    Interim Director Supply Chain Management Rita Neogy Manager Card & Travel Services Tyler Faso-Rae Eisenbeis Vacant Updated: May 28, 2014 SUPPLY CHAIN MANAGEMENT Organizational Chart SCM Administrator Sandra Supply Chain PeopleSoft Master Data Specialist Carllyn Colabella Supply Chain Consultant Customer Service

  3. Supply-Chain Optimization Template

    NASA Technical Reports Server (NTRS)

    Quiett, William F.; Sealing, Scott L.

    2009-01-01

    The Supply-Chain Optimization Template (SCOT) is an instructional guide for identifying, evaluating, and optimizing (including re-engineering) aerospace- oriented supply chains. The SCOT was derived from the Supply Chain Council s Supply-Chain Operations Reference (SCC SCOR) Model, which is more generic and more oriented toward achieving a competitive advantage in business.

  4. 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.

  5. 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.}

  6. Translocation of botulinum neurotoxin light chain protease by the heavy chain protein-conducting channel.

    PubMed

    Montal, Mauricio

    2009-10-01

    Clostridial botulinum neurotoxins (BoNTs) inhibit synaptic exocytosis; intoxication requires the di-chain protein to undergo conformational changes in response to pH and redox gradients across the endosomal membrane with consequent formation of a protein-conducting channel by the heavy chain (HC) that translocates the light chain (LC) protease into the cytosol, colocalizing it with the substrate SNARE proteins. We investigate the dynamics of protein translocation across membranes using a sensitive single-molecule assay to track translocation events with millisecond resolution on lipid bilayers and on membrane patches of Neuro 2A cells. Translocation of BoNT/A LC by the HC is observed in real time as changes of channel conductance: the channel is occluded by the light chain during transit, and open after completion of translocation and release of cargo, acting intriguingly similar to the protein-conducting/translocating channels of the endoplasmic reticulum, mitochondria, and chloroplasts. Our findings support the notion of an interdependent, tight interplay between the HC transmembrane chaperone and the LC cargo that prevents LC aggregation and dictates the productive passage of cargo through the channel and completion of translocation. The protein-conducting channel of BoNT, a key element in the process of neurotoxicity, emerges therefore as a target for antidote discovery - a novel paradigm of paramount significance to health science and biodefense. PMID:19111565

  7. Translocation of Botulinum neurotoxin light chain protease by the heavy chain protein-conducting channel

    PubMed Central

    Montal, Mauricio

    2009-01-01

    Clostridial botulinum neurotoxins (BoNTs) inhibit synaptic exocytosis; intoxication requires the di-chain protein to undergo conformational changes in response to pH and redox gradients across the endosomal membrane with consequent formation of a protein-conducting channel by the heavy chain (HC) that translocates the light chain (LC) protease into the cytosol, colocalizing it with the substrate SNARE proteins. We investigate the dynamics of protein-translocation across membranes using a sensitive single molecule assay to track translocation events with millisecond resolution on lipid bilayers and on membrane patches of Neuro 2A cells. Translocation of BoNT/A LC by the HC is observed in real time as changes of channel conductance: the channel is occluded by the light chain during transit, and open after completion of translocation and release of cargo, acting intriguingly similar to the protein-conducting/translocating channels of the endoplasmic reticulum, mitochondria, and chloroplasts. Our findings support the notion of an interdependent, tight interplay between the HC transmembrane chaperone and the LC cargo that prevents LC aggregation and dictates the productive passage of cargo through the channel and completion of translocation. The protein-conducting channel of BoNT, a key element in the process of neurotoxicity, emerges therefore as a target for antidote discovery –a novel paradigm of paramount significance to health science and biodefense. PMID:19111565

  8. 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.

  9. Supply chain dynamics

    Microsoft Academic Search

    D. R. TOWILL

    1991-01-01

    The application of system dynamics models to supply chains is reviewed. The most profitable area for system modelling and design concerns the demand amplification which is frequently observed in the medium-term operation of individual businesses, which behaviour is one manifestation of the Law of Industrial Dynamics. One cause of this amplification is the time delay incurred by both ‘value-added’ and

  10. Knowledge value chain

    Microsoft Academic Search

    Ching Chyi Lee; Jie Yang

    2000-01-01

    Introduces the knowledge value chain model as a knowledge management (KM) framework. The model consists of knowledge infrastructure (knowledge worker recruitment, knowledge storage capacity, customer\\/supplier relationship and CKO and management), the process of KM (knowledge acquisition, knowledge innovation, knowledge protection, knowledge integration, and knowledge dissemination), and the interaction among those components resulting in knowledge performance. Further to the discussion of

  11. Transforming the supply chain

    Microsoft Academic Search

    Evangelia D. Fassoula

    2006-01-01

    Purpose – Today's business environment emerges the need for organizations to continuously transform themselves, in order to maintain and reinforce their ability to compete successfully. The purpose of this paper is to present an analysis of the transformation process of supply chain in order to provide a modular structured management tool for planning, implementing and measure the effectiveness of supply

  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. 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.

  14. The Agile Supply Chain

    Microsoft Academic Search

    Martin Christopher

    2000-01-01

    Turbulent and volatile markets are becoming the norm as life cycles shorten and global economic and competitive forces create additional uncertainty. The risk attached to lengthy and slow-moving logistics “pipelines” has become unsustainable, forcing organizations to look again at how their supply chains are structured and managed. This paper suggests that the key to survival in these changed conditions is

  15. Modulation of the electronic and magnetic properties of the silicene nanoribbons by a single C chain

    Microsoft Academic Search

    Y.-L. Song; Y. Zhang; J.-M. Zhang; D.-B. Lu; K.-W. Xu

    2011-01-01

    Under the generalized gradient approximation (GGA), the electronic and magnetic properties are studied for H-terminated zigzag edge Si nanoribbon (ZSiNR) decorated with a single C chain by using the first-principles projector augmented wave (PAW) potential within the density function theory (DFT) framework. The results show that either a perfect ZSiNR or a single C chain decorated ZSiNR, the ferromagnetic state

  16. Controllable growth of gradient porous structures.

    PubMed

    Yao, Donggang; Zhang, Wei; Zhou, Jack G

    2009-05-11

    Cocontinuous phase structures of immiscible polymers can be developed under appropriate melt-blending conditions. Because of the presence of interfacial tension, such cocontinuous structures start to coarsen when heated to a temperature higher than the melting/softening temperature of both phases. In this study, a method for controllable growth of gradient porous structures utilizing variable coarsening rates in a gradient temperature field was investigated. The phase structure coarsens at a higher rate in higher temperature regions but at a slower rate in lower temperature regions, resulting in the generation of a gradient phase morphology. Subsequent dissolution of one phase in the binary blend yields a gradient porous structure made of the remaining polymer component. A polystyrene/poly(lactic acid) (PLA) blend was used as a model system. By designing proper thermal boundary conditions and introducing different thermal gradients during annealing, different types of gradient porous structures of PLA were created. PMID:19354280

  17. Application of alkaline sucrose gradient centrifugation in the analysis of DNA replication after DNA damage.

    PubMed

    Raschke, Sascha; Guan, Jun; Iliakis, George

    2009-01-01

    Sucrose density gradient ultracentrifugation is a powerful technique for fractionating macromolecules like DNA, RNA, and proteins. For this purpose, a sample containing a mixture of different size macromolecules is layered on the surface of a gradient whose density increases linearly from top to bottom. During centrifugation, different size macromolecules sediment through the gradient at different rates. The rate of sedimentation depends, in addition to centrifugal force, on the size, shape, and density of the macromolecules, as well as on the density and viscosity of the gradient. In this way, macromolecules are separated by size with larger ones sedimenting towards the bottom and lighter ones remaining close to the top of the gradient. The method has been particularly successful in the size fractionation of large DNA molecules and has been extensively used to measure induction and repair of DNA breaks after exposure to clastogenic factors. Here, we describe an adaptation of this method that can be used in the analysis of newly synthesized DNA formed during DNA replication. Through size analysis of nascent DNA in alkaline sucrose gradients, variations in replication activity can be measured after exposure of cells to DNA-damaging agents. The method is particularly useful as it allows distinction between DNA damage-mediated effects on chain elongation vs. replicon initiation, which is essential for an in-depth analysis of the intra-S-phase checkpoint. This ability makes the technique unique and justifies its somewhat labour-intensive nature. PMID:19563115

  18. Transformations between aeromagnetic gradients in frequency domain

    Microsoft Academic Search

    Haixia Li; Shizhe Xu; Hailong Yu; Wei Wei; Jiangqi Fang

    2010-01-01

    Aeromagnetic gradients are often used to enhance details or add new insights for interpretation. The gradients may be measured\\u000a or derived from the total field or from transformation between horizontal and vertical gradients. At present, vertical, horizontal,\\u000a and triaxial aeromagnetic gradiometers are in operation throughout the world, while the first two are used more widely. Transformations\\u000a between horizontal and vertical

  19. 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.

  20. Second order gradient ascent pulse engineering

    NASA Astrophysics Data System (ADS)

    de Fouquieres, P.; Schirmer, S. G.; Glaser, S. J.; Kuprov, Ilya

    2011-10-01

    We report some improvements to the gradient ascent pulse engineering (GRAPE) algorithm for optimal control of spin ensembles and other quantum systems. These include more accurate gradients, convergence acceleration using the Broyden-Fletcher-Goldfarb-Shanno (BFGS) quasi-Newton algorithm as well as faster control derivative calculation algorithms. In all test systems, the wall clock time and the convergence rates show a considerable improvement over the approximate gradient ascent.

  1. Second order gradient ascent pulse engineering.

    PubMed

    de Fouquieres, P; Schirmer, S G; Glaser, S J; Kuprov, Ilya

    2011-10-01

    We report some improvements to the gradient ascent pulse engineering (GRAPE) algorithm for optimal control of spin ensembles and other quantum systems. These include more accurate gradients, convergence acceleration using the Broyden-Fletcher-Goldfarb-Shanno (BFGS) quasi-Newton algorithm as well as faster control derivative calculation algorithms. In all test systems, the wall clock time and the convergence rates show a considerable improvement over the approximate gradient ascent. PMID:21885306

  2. 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.

  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. Geothermal gradients of Alberta in Western Canada

    SciTech Connect

    Lam, H.L.; Jones, F.W.

    1984-01-01

    -55,246 bottom hole temperature (BHT) values from petroleum exploration well logs of 28,260 wells have been used to estimate geothermal gradients in Alberta. A general decrease in geothermal gradient towards the east is apparent. High gradient areas occur in the Hinton - Edson area of westcentral Alberta, in the Fort McMurray area of northeast Alberta, in the Steen River area of northwest Alberta, and at the northwest corner of the province. Comparison with gravity, aeromagnetic and relief maps indicates close correspondence between topographic features and geothermal gradients. It is suggested that subsurface temperature distribution in Alberta is strongly influenced by groundwater motion.

  6. Continuous spray forming of functionally gradient materials

    SciTech Connect

    McKechnie, T.N.; Richardson, E.H. [Plasma Processes Inc., Huntsville, AL (United States); Watson, R.D. [Sandia National Labs., Albuquerque, NM (United States)

    1995-12-31

    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 processing are also presented. Applications for this functional gradient structural material range from fusion reactor plasma facing components to missile nose cones to boilers.

  7. Stellar population gradients in brightest cluster galaxies

    NASA Astrophysics Data System (ADS)

    Loubser, S. I.; Sánchez-Blázquez, P.

    2013-07-01

    We present the stellar population and velocity dispersion gradients for a sample of 24 brightest cluster galaxies (BCGs) in the nearby Universe for which we have obtained high quality long-slit spectra at the Gemini telescopes. With the aim of studying the possible connection between the formation of the BCGs and their host clusters, we explore the relations between the stellar population gradients and properties of the host clusters, as well as the possible connections between the stellar population gradients and other properties of the galaxies. We find mean stellar population gradients (negative ?[Z/H]/log r gradient of - 0.285 +/- 0.064; small positive ?log(age)/log r gradient of +0.069 +/- 0.049; and null ?[E/Fe]/log r gradient of -0.008 +/- 0.032), that are consistent with those of normal massive elliptical galaxies. However, we find a trend between metallicity gradients and velocity dispersion (with a negative slope of - 1.616 +/- 0.539), that is not found for the most massive ellipticals. Furthermore, we find trends between the metallicity gradients and K-band luminosities (with a slope of 0.173 +/- 0.081) as well as the distance from the BCG to the X-ray peak of the host cluster (with a slope of - 7.546 +/- 2.752). The latter indicates a possible relation between the formation of the cluster and that of the central galaxy.

  8. 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

  9. Molecular mobility and microscopic structure changes in ?-carrageenan solutions studied by gradient NMR.

    PubMed

    Zhao, Qiuhua; Brenner, Tom; Matsukawa, Shingo

    2013-06-01

    Changes in the molecular mobility of ?-carrageenan were observed by the pulsed field gradient stimulated echo (PGSTE) and Carr-Purcell-Meiboom-Gill (CPMG) methods for elucidating the molecular aspect of the sol-to-gel transition. The echo signal intensity of ?-carrageenan without a gradient, Ikap(0), decreased steeply near the sol-to-gel temperature (Tsg), suggesting that ?-carrageenan chains formed aggregates and a network structure. Below Tsg, the spin-spin relaxation time T2 and the diffusion coefficient of ?-carrageenan (Dkap) increased with decreasing temperature, indicating that the solute ?-carrageenan chains have a lower molecular weight Mw than chains involved in the aggregation. The diffusion coefficient of pullulan (Dpul) added as a probe molecule in ?-carrageenan solutions was measured, and the characteristic hydrodynamic screening length, ?, was then estimated from the degree of diffusion restriction. Below a certain temperature, Dkap reached a higher value than that of Dpul, suggesting that the Mw of solute ?-carrageenan became lower than that of pullulan. GPC measurements confirmed the presence of ?-carrageenan chains with a lower Mw than that of pullulan. A simple physical model of the structural change in ?-carrageenan solution was proposed with a bimodal distribution of ?-carrageenan with higher and lower Mw than the pullulan probe. The higher Mw chains form the gel network restricting the probe's diffusion, and the lower Mw chains increase the effective viscosity. The concentration of the high Mw solute ?-carrageenan chains in 1%, 2% and 4% ?-carrageenan solutions was estimated from Ikap(0) and the total ?-carrageenan concentration, and the relation with pullulan diffusion was studied. PMID:23618293

  10. 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.

  11. 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.

  12. Chain Transfer Mechanisms

    Microsoft Academic Search

    Piet W. N. M. Leeuwen

    \\u000a Chain initiation and termination immediately came into focus when the first well-defined and relatively fast palladium catalysts\\u000a for copolymerization, containing as a characteristic weakly coordinating anions, were introduced in 1982 [1]. The palladium chloride based catalysts studied in the sixties and seventies required high temperatures and usually led\\u000a to palladium metal formation, in spite of the high carbon monoxide pressures

  13. 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

  14. Polymerase Chain Reaction

    NSDL National Science Digital Library

    Teachers' Domain presents this interactive, adapted from the University of Nebraska's Library of Crop Technologies, with reading material and animations to help students learn the basic steps of polymerase chain reaction. Following the introduction, the lesson is divided four parts: Finding and Isolating DNA, Creating the DNA Solution, Begin Thermal Cycling, and Replication. Animations help students visualize each step of the processes described. On the site, visitors will also find a supplemental background essay, discussion questions, and standards alignment from Teachers' Domain.

  15. 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.

  16. Folding of polyglutamine chains

    NASA Astrophysics Data System (ADS)

    Chopra, Manan; Reddy, Allam S.; Abbott, N. L.; de Pablo, J. J.

    2008-10-01

    Long polyglutamine chains have been associated with a number of neurodegenerative diseases. These include Huntington's disease, where expanded polyglutamine (PolyQ) sequences longer than 36 residues are correlated with the onset of symptoms. In this paper we study the folding pathway of a 54-residue PolyQ chain into a ?-helical structure. Transition path sampling Monte Carlo simulations are used to generate unbiased reactive pathways between unfolded configurations and the folded ?-helical structure of the polyglutamine chain. The folding process is examined in both explicit water and an implicit solvent. Both models reveal that the formation of a few critical contacts is necessary and sufficient for the molecule to fold. Once the primary contacts are formed, the fate of the protein is sealed and it is largely committed to fold. We find that, consistent with emerging hypotheses about PolyQ aggregation, a stable ?-helical structure could serve as the nucleus for subsequent polymerization of amyloid fibrils. Our results indicate that PolyQ sequences shorter than 36 residues cannot form that nucleus, and it is also shown that specific mutations inferred from an analysis of the simulated folding pathway exacerbate its stability.

  17. 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/l, Applied Biosystems Cloned Pfu DNA polymerase 100U, 2.5U/l, CAT#600153-81, Stratagene #12;Temperature Gradient Capillary Electrophoresis (TGCE) Related Protocols 2 PCR program used to denature/re-anneal mixed

  18. Density Gradient Stabilization of Electron Temperature Gradient Driven Turbulence in a Spherical Tokamak

    SciTech Connect

    Ren, Y; Mazzucato, E; Guttenfelder, W; Bell, R E; Domier, C W; LeBlanc, B P; Lee, K C; Luhmann Jr, N C; Smith, D R

    2011-03-21

    In this letter we report the first clear experimental observation of density gradient stabilization of electron temperature gradient driven turbulence in a fusion plasma. It is observed that longer wavelength modes, k??s ?10, are most stabilized by density gradient, and the stabilization is accompanied by about a factor of two decrease in the plasma effective thermal diffusivity.

  19. 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.

  20. The Supply Chain Management Processes

    Microsoft Academic Search

    Keely L. Croxton; Sebastián J. García-Dastugue; Douglas M. Lambert; Dale S. Rogers

    2001-01-01

    Increasingly, supply chain management is being recognized as the management of key business processes across the network of organizations that comprise the supply chain. While many have recognized the benefits of a process approach to managing the business and the supply chain, most are vague about what processes are to be considered, what sub-processes and activities are contained in each

  1. Best Practices in Supply Chain

    E-print Network

    Best Practices in Supply Chain Management DESPITE THE TURMOIL OF U.S. ECONOMY, companies that have a winning strategy and a business model that utilizes best practices in supply chain management (SCM), will remain strong and continue to grow in marketplace. "Supply chain management encompasses the planning

  2. Polymerase Chain Reaction Assay and

    E-print Network

    Paris-Sud XI, Université de

    Polymerase 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) and the national reference center for menin- gitis in Niger. The polymerase chain reaction (PCR) method

  3. 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.

  4. Statistical Inference about Markov Chains

    Microsoft Academic Search

    T. W. Anderson; Leo A. Goodman

    1957-01-01

    Maximum likelihood estimates and their asymptotic distribution are obtained for the transition probabilities in a Markov chain of arbitrary order when there are repeated observations of the chain. Likelihood ratio tests and $\\\\chi^2$-tests of the form used in contingency tables are obtained for testing the following hypotheses: (a) that the transition probabilities of a first order chain are constant, (b)

  5. Improved chemical composition separation of ethylene-propylene random copolymers by high-temperature solvent gradient interaction chromatography.

    PubMed

    Cheruthazhekatt, Sadiqali; Pasch, Harald

    2013-10-01

    High-temperature solvent gradient interaction chromatography (HT-SGIC) is a fast and efficient fractionation technique for the chemical composition analysis of olefin copolymers. The separation of ethylene-propylene random copolymers (EPRs) was achieved on a graphitic stationary phase, Hypercarb, at 160 °C by using linear solvent gradient elution from 1-decanol to 1,2,4-trichlorobenzene (TCB). In the present work, the solvent gradient profile was modified to improve the chromatographic separation of EPRs. With the aim to obtain a better resolution in separation, a slow increase in the volume fraction of TCB was applied. This allowed for a relatively large retention region for linear polyethylene (PE) chains on the column; thereby, a broader elution volume zone between the start of the gradient and the PE elution was achieved. The efficiency of this new gradient profile was demonstrated by analysing two fully amorphous EPR samples. Clear differences in the chemical composition of these EPR samples with similar ethylene contents have been proven by using this modified solvent gradient. The comprehensive chemical composition and microstructure analysis of the SGIC-separated fractions by FTIR revealed that ethylene/propylene (EP) copolymer chains were eluted according to their ethylene/propylene contents and E or P sequence lengths, even though they are distributed in a random manner. These results showed that the solvent composition is an important factor to affect the interactive adsorption or desorption behaviour of EP chains on Hypercarb. In this way, for the first time, the determination of the complex composition and chain structure of EPR samples was achieved within short analysis time, which is not possible till now using other fractionation techniques reported. PMID:23907688

  6. Influences of Slope Gradient on Soil Erosion

    Microsoft Academic Search

    Qing-quan Liu; Li Chen; Jia-chun Li

    2001-01-01

    The main factors influencing soil erosion include the net rain excess, the water depth, the velocity, the shear stress of overland flows, and the erosion-resisting capacity of soil. The laws of these factors varying with the slope gradient were investigated by using the kinematic wave theory. Furthermore, the critical slope gradient of erosion was driven. The analysis shows that the

  7. Plant physiology Peroxidase isoenzyme gradients in Capsicum

    E-print Network

    Paris-Sud XI, Université de

    Plant physiology Peroxidase isoenzyme gradients in Capsicum annuum leaves and their expression; accepted 24 January 1994) Summary - The expression of peroxidases (EC 1 11 1 7) during leaf development has of Capsicum annuum (var annuum) to assess the nature, subcellular localization and gradients of the peroxidase

  8. Temperature-Gradient Furnace for Solidification Experiments

    NASA Technical Reports Server (NTRS)

    Aldrich, B. R.; Whitt, W. D.

    1985-01-01

    Gradients are controllable from zero to 500 degrees C/cm. Typical temperature profile superimposed on partial cross section of furnace. Steepness of gradient varied by adjusting flow of energy to and from different zones of furnace. Specimen placed in ampoule moved inside ceramic tube according to needs of experiment. Furnace provides axial temperature profiles for material processing experiments.

  9. Temperature Gradients in Semiconductor Alloying Technology

    Microsoft Academic Search

    E. P. EerNisse; H. W. Thompson

    1965-01-01

    Experiments have been conducted with Ge and Si to define the metallurgical effects of temperature gradients in the alloying technology. These effects are defined in terms of the electrical characteristics of alloyed diodes and transistors and in terms of the physical appearance of the p-n junction. The presence of temperature gradients during the dissolution phase of an alloy cycle results

  10. Bending behavior of Functionally Gradient Materials

    Microsoft Academic Search

    Tilo Hauke; Azamat Kouvatov; Ralf Steinhausen; Wolfgang Seifert; Horst Beige; Hans Theo; Langhammer; Hans-Peter Abicht

    2000-01-01

    In the last years the suitability of Functionally Gradient Materials (FGM) for monolithic bending actuators was shown. However, there is a lack of detailed models for the bending behavior of FGM. Recently we have developed a analytical model for the calculation of the bending behavior of FGM with an arbitrary gradient of piezoelectric properties. From the modeling it seems to

  11. 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.…

  12. 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...

  13. On lower order strain gradient plasticity theories

    Microsoft Academic Search

    Christian F. Niordson; John W. Hutchinson

    2003-01-01

    By way of numerical examples, this paper explores the nature of solutions to a class of strain gradient plasticity theories that employ conventional stresses, equilibrium equations and boundary conditions. Strain gradients come into play in these modified conventional theories only to alter the tangent moduli governing increments of stress and strain. It is shown that the modification is far from

  14. Thermal gradient-hydro generation cycle \\/TGUC

    Microsoft Academic Search

    S. A. Parker

    1978-01-01

    The described thermal gradient utilization cycle (TGUC) makes use of the vertical atmospheric temperature difference. TGUC is a closed loop system. Thermal vapor is pumped to higher elevations where condensation occurs, and power is derived by a conventional hydro-prime mover along with a conventional regenerative Rankine cycle. TGUC and ocean thermal energy conversion are contrasted; in oceans the thermal gradient

  15. 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

  16. 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.

  17. Stochastic Gradient Descent with Only One Projection

    E-print Network

    , such as celebrated Stochastic Gradient Descent (SGD) [16, 2] and its online counterpart Online Gradient Descent (OGD, the lightweight computation per iteration makes SGD attractive for many large-scale learning problems. To find a solution within the domain K that optimizes the given objective function f(x), SGD computes an unbiased

  18. Stochastic Gradient Descent Tricks Leon Bottou

    E-print Network

    Bottou, Léon

    gradient descent (SGD). This chapter provides background material, explains why SGD is a good learning an instance of a more general technique called stochastic gradient descent (SGD). This chapter provides background material, explains why SGD is a good learning algorithm when the training set is large

  19. Approximate error conjugation gradient minimization methods

    SciTech Connect

    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.

  20. 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.

  1. Photoaffinity labeling of the primary fibrin polymerization site: localization of the label to gamma-chain Tyr-363.

    PubMed

    Yamazumi, K; Doolittle, R F

    1992-04-01

    Fragment D prepared from human fibrinogen was labeled specifically by photoactivation of the peptide [14C]Gly-Pro-Arg-N-(4-azido-2-nitrophenyl)Lys amide. The preparation was freed of excess labeling reagents and then reduced and alkylated. The component alpha, beta, and gamma chains were purified by chromatography on carboxymethylcellulose and the radioactivity was found to be restricted to the gamma chain. Isolated gamma chains were digested with various endopeptidases, both alone and in tandem, and the products were fractionated by gradient HPLC. The amino acid compositions of all labeled peptides led to the conclusion that the modification occurs exclusively on gamma-chain Tyr-363. PMID:1557396

  2. Value chain analysis: an approach to supply chain improvement in agri-food chains

    Microsoft Academic Search

    David H. Taylor

    2005-01-01

    Purpose – To develop an innovative methodology to apply lean value chain improvement techniques to a complete supply chain for a food product from farm to consumer. Design\\/methodology\\/approach – Action research based on a UK case study involving farmers, a food processor and a major retailer. Findings – Value stream analysis (VCA) highlights significant opportunities to improve supply chain performance,

  3. 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.

  4. 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

  5. Monte Carlo without chains

    SciTech Connect

    Chorin, Alexandre J.

    2007-12-12

    A sampling method for spin systems is presented. The spin lattice is written as the union of a nested sequence of sublattices, all but the last with conditionally independent spins, which are sampled in succession using their marginals. The marginals are computed concurrently by a fast algorithm; errors in the evaluation of the marginals are offset by weights. There are no Markov chains and each sample is independent of the previous ones; the cost of a sample is proportional to the number of spins (but the number of samples needed for good statistics may grow with array size). The examples include the Edwards-Anderson spin glass in three dimensions.

  6. SUPPLY CHAIN MANAGEMENT CONCENTRATION FOR UNDERGRADUATES

    E-print Network

    Salama, Khaled

    SUPPLY 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 Networks, Innovation, and Value Creation Optional Supply Chain Management Concentration Course MGMT 4460

  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. Intracellular chemical gradients: morphing principle in bacteria

    PubMed Central

    2012-01-01

    Advances in computational biology allow systematic investigations to ascertain whether internal chemical gradients can be maintained in bacteria – an open question at the resolution limit of fluorescence microscopy. While it was previously believed that the small bacterial cell size and fast diffusion in the cytoplasm effectively remove any such gradient, a new computational study published in BMC Biophysics supports the emerging view that gradients can exist. The study arose from the recent observation that phosphorylated CtrA forms a gradient prior to cell division in Caulobacter crescentus, a bacterium known for its complicated cell cycle. Tropini et al. (2012) postulate that such gradients can provide an internal chemical compass, directing protein localization, cell division and cell development. More specifically, they describe biochemical and physical constraints on the formation of such gradients and explore a number of existing bacterial cell morphologies. These chemical gradients may limit in vitro analyses, and may ensure timing control and robustness to fluctuations during critical stages in cell development. PMID:22954369

  9. Seismic velocity gradients in the upper mantle

    SciTech Connect

    Kennett, B.L.N.

    1991-06-01

    The radial velocity gradients for P- and S- waves in the upper mantle are of considerable interest for petrological studies of the upper mantle but are difficult to constrain directly. Comparison of three different styles of velocity model, constructed within a common parameterization to give a good fit to the travel times of P- and S-waves to 30{degree}, provide a useful framework for constructing bounds on the radial gradients. For depths from 250-1,000 km a somewhat subjective set of bounds are suggested for the velocity gradients and velocity contrasts at the major discontinuities in an average mantle. One of the most significant factors affecting the estimation of radial gradients is the presence of small-scale heterogeneity in the mantle. Modest heterogeneity, around 1 percent perturbations on scale lengths of about 300 km, can give rise to horizontal velocity gradients which can overwhelm the radial gradients in the shallower parts of the mantle and still be a quarter of the size of the radial gradients at greater depths. However such scales of heterogeneity are unlikely to simulate the presence of additional upper mantle discontinuities for ray paths travelling near vertical.

  10. Extraordinary strain hardening by gradient structure.

    PubMed

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

    2014-05-20

    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

  11. ATLAS3D Stellar Population Gradients

    NASA Astrophysics Data System (ADS)

    Kuntschner, Harald

    2015-04-01

    We present stellar population gradients of early-type galaxies from the ATLAS3D survey: a complete, volume-limited multi-wavelength survey of 260 early-type galaxies in the local 42 Mpc volume. Using emission-corrected spectra integrated within elliptical annuli we measure line-strength indices and apply single stellar population (SSP) models to derive SSP-equivalent values of stellar age, metallicity, and alpha enhancement as function of radius. For all galaxies we derive basic linear stellar population gradients versus radius logR/Re). These gradients are examined on their own and versus three mass-sensitive parameters: K-band luminosity MK, velocity dispersion within one effective radius log ?e, and our dynamical mass MJAM. We find a correlation between positive age gradients (younger centre) and steeper negative metallicity gradients with a Spearman rank correlation coefficient of -0.46 and a significance of 7.65 × 10-15. Furthermore, we find a robustly estimated mean metallicity gradient of ?[Z/H] = -0.37 +/- 0.01 for the sample with a significant trend for more massive galaxies to have shallower profiles. While there is no clear distinction between fast and slow rotators or signs of environmental influence, we do detect a significantly larger range of [Z/H]-gradients towards low mass galaxies.

  12. Supply Chain Management and Marketing Sciences Maximizing the Interface between Supply Chain & Marketing

    E-print Network

    Lin, Xiaodong

    Supply Chain Management and Marketing Sciences Maximizing the Interface between Supply Chain.Inordertocontinuethetraditionofsuccess,the SCSIleanedonitsconnectionsinthesupplychainindustrymorethanever. SCSImembersareinvolvedinavarietyofstrongSupplyChain professionalorganizations.TheCouncilofSupplyChainManagement.Inaddition,SCSImemberstookpartinmanymeetingsofthese organizationsinordertonetworkandexpandonwhattheylearninthe classroom. TheSCSIalsocontinuedtoworkwiththeRutgersCenterforSupplyChain Management

  13. Supply Chain Management Understand and apply essential supply chain management concepts.

    E-print Network

    Fork, Richard

    Supply Chain Management Understand and apply essential supply chain management concepts. Gain In Integrated Supply Chain Management Certificate awarded after completion of: · Supply Chain Management Foundation · Supply Chain Relationship Management · Demand Management · Operations Systems Management

  14. 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.

  15. Algorithm for image retrieval based on edge gradient orientation statistical code.

    PubMed

    Zeng, Jiexian; Zhao, Yonggang; Li, Weiye; Fu, Xiang

    2014-01-01

    Image edge gradient direction not only contains important information of the shape, but also has a simple, lower complexity characteristic. Considering that the edge gradient direction histograms and edge direction autocorrelogram do not have the rotation invariance, we put forward the image retrieval algorithm which is based on edge gradient orientation statistical code (hereinafter referred to as EGOSC) by sharing the application of the statistics method in the edge direction of the chain code in eight neighborhoods to the statistics of the edge gradient direction. Firstly, we construct the n-direction vector and make maximal summation restriction on EGOSC to make sure this algorithm is invariable for rotation effectively. Then, we use Euclidean distance of edge gradient direction entropy to measure shape similarity, so that this method is not sensitive to scaling, color, and illumination change. The experimental results and the algorithm analysis demonstrate that the algorithm can be used for content-based image retrieval and has good retrieval results. PMID:24892074

  16. Doping of Semiconducting Atomic Chains

    NASA Technical Reports Server (NTRS)

    Toshishige, Yamada; Kutler, Paul (Technical Monitor)

    1997-01-01

    Due to the rapid progress in atom manipulation technology, atomic chain electronics would not be a dream, where foreign atoms are placed on a substrate to form a chain, and its electronic properties are designed by controlling the lattice constant d. It has been shown theoretically that a Si atomic chain is metallic regardless of d and that a Mg atomic chain is semiconducting or insulating with a band gap modified with d. For electronic applications, it is essential to establish a method to dope a semiconducting chain, which is to control the Fermi energy position without altering the original band structure. If we replace some of the chain atoms with dopant atoms randomly, the electrons will see random potential along the chain and will be localized strongly in space (Anderson localization). However, if we replace periodically, although the electrons can spread over the chain, there will generally appear new bands and band gaps reflecting the new periodicity of dopant atoms. This will change the original band structure significantly. In order to overcome this dilemma, we may place a dopant atom beside the chain at every N lattice periods (N > 1). Because of the periodic arrangement of dopant atoms, we can avoid the unwanted Anderson localization. Moreover, since the dopant atoms do not constitute the chain, the overlap interaction between them is minimized, and the band structure modification can be made smallest. Some tight-binding results will be discussed to demonstrate the present idea.

  17. Artificial photosynthesis: Light-activated calcium gradients

    NASA Astrophysics Data System (ADS)

    Thompson, David H.

    2002-12-01

    Photosynthetic organisms use light to create chemical gradients across bilayer membranes that drive energetically unfavourable reactions. Synthetic systems that accomplish the same feat may find uses in a variety of biological and non-biological applications.

  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. 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 ...

  20. Measurements on a Thermal Gradient Gas Lens

    Microsoft Academic Search

    W. H. Steier

    1965-01-01

    A thermal gradient gas lens has been investigated experimentally for a variety of conditions and gases. The results in general show good agreement with the theory and indicate that these lenses may be useful in long distance optical transmission lines.

  1. TEK twisted gradient flow running coupling

    E-print Network

    Margarita García Pérez; Antonio González-Arroyo; Liam Keegan; Masanori Okawa

    2014-11-02

    We measure the running of the twisted gradient flow coupling in the Twisted Eguchi-Kawai (TEK) model, the SU(N) gauge theory on a single site lattice with twisted boundary conditions in the large N limit.

  2. Incremental Accelerated Gradient Methods for SVM Classification ...

    E-print Network

    2013-05-02

    We also propose to take benefit from recent research on gradient techniques ...... [18] Y.J. Lee, O.L. Mangasarian, and W.H. Wolberg, Breast Cancer Survival and. Chemotherapy: A Support Vector Machine Analysis, Data Mining Institute Tech-.

  3. Velocity gradients and microturbulence in Cepheids

    NASA Technical Reports Server (NTRS)

    Karp, A. H.

    1972-01-01

    Variations of the microturbulent velocity with phase and height in the atmosphere were reported in classical Cepheids. It is shown that these effects can be understood in terms of variations of the velocity gradient in the atmospheres of these stars.

  4. GOCE gravity gradient data for lithospheric modeling

    NASA Astrophysics Data System (ADS)

    Bouman, Johannes; Ebbing, Jörg; Meekes, Sjef; Abdul Fattah, Rader; Fuchs, Martin; Gradmann, Sofie; Haagmans, Roger; Lieb, Verena; Schmidt, Michael; Dettmering, Denise; Bosch, Wolfgang

    2015-03-01

    The Gravity field and steady-state Ocean Circulation Explorer (GOCE) is the European Space Agency's (ESA) satellite gravity mission to determine the Earth's mean gravity field. GOCE delivers gravity gradients, a new type of satellite data. We study how these data can improve modeling of the Earth's lithosphere. We discuss the use of the original GOCE gravity gradients versus the use of gravity gradients in grids at satellite altitude or close the Earth's surface and conclude that grids are easier to handle than the original data because one does not have to deal with very different error characteristics of the different gradients, given in a rotating frame at varying heights. The downward continuation to the surface enhances signal and better reflects the near-surface geology. But this does not outweigh the amplification of noise and omission errors, which is why we recommend using the field at mean satellite altitude for lithospheric modeling. The North-East Atlantic region is ideal to analyze the additional value of GOCE gravity gradients because it is a well-studied region in terms of regional geophysics. We calculated the gradient sensitivity for crustal depth slices using a 3D lithospheric model. This reveals that especially interfaces with large density contrasts have a distinct signal in the gravity gradients, but that they are quite insensitive to intra-crustal density sources, which can have quite a large effect on surface gravity data. We also show that the satellite gradients have a depth sensitivity well suited to study the upper mantle density structure, making them complementary to gravity and seismic tomography. In the underexplored Rub'al-Khali area the GOCE vertical gradient was used to invert for crustal thickness. The updated Moho model gives a good fit to four of the six gradients and independent depths from seismic stations. The Moho model was used to update the heat flow model and source rock maturity maps, which are generally consistent with known source rock maturity trends in the surrounding regions. GOCE gradients are therefore useful to map crustal thickness and deep regional structures for frontier areas. In combination with other data, heat flow can be modeled which is essential for basin maturity evaluation.

  5. chain 2chain 3 4row of 6 racks and 2 row of 5 racks

    E-print Network

    chain 1 chain 2chain 3 4row of 6 racks and 2 row of 5 racks chain 4 chain 10 6 5 4 3 2 1 chain 5 chain 6 f b fb f b b f f b b f 1 2 3 4 5 6 1 2 3 4 5 1:50 Rack A with 52 HU (2500*900*600) door door HV.0 1840.0 300.0 #12;chain 10 Layout of 2nd floorchain 4 chain 3 chain 2 chain 5 chain 6 chain 101:50 Rack

  6. Sound focusing by gradient index sonic lenses

    E-print Network

    Alfonso Climente; Daniel Torrent; Jose Sanchez-Dehesa

    2010-06-14

    Gradient index sonic lenses based on two-dimensional sonic crystals are here designed, fabricated and characterized. The index-gradient is achieved in these type of flat lenses by a gradual modification of the sonic crystal filling fraction along the direction perpendicular to the lens axis. The focusing performance is well described by an analytical model based on ray theory as well as by numerical simulations based on the multiple-scattering theory.

  7. Pressure Gradient Evolution and Substorm Onset

    NASA Astrophysics Data System (ADS)

    Zhonghua, Y.; Pu, Z.; Cao, X.; Nishimura, T.; Zhang, H.; Fu, S.; Xie, L.; Guo, R.

    2011-12-01

    Near-Earth current disruption (NECD) and substorm current wedge (SCW) formation are two related key phenomena for substorm onset. They are believed to be in close association with evolution of pressure gradient near the inner edge of plasma sheet. In the past, a few attempts have been made to investigate the pressure gradient in the late growth phase based on one- or two-spacecraft observations (e.g. , Korth et al., 1991; Pu et al., 1992; Shiokawa et al., 1998; Xing et al., 2010, 2011,etc). In this paper, with linearization assumption in the inner-probe region, we use THEMIS three-probe measurements to estimate the pressure gradient near the inner edge of the equatorward and duskward (dawnward) plasma sheet where pressure gradient in the Z-direction is almost vanished. We therefore can roughly get the two-dimensional pressure gradient in the X- and Y-direction simultaneously. Our observations indicate that the pressure gradients in both the X- and Y-direction enhance right after (within one minute) substorm onset. The enhanced pressure gradient in the Y-direction is duskward (dawnward) when the probes are in the duskside (dawnside) of the enhanced earthward flow in the growth phase. The enhanced dawn-dusk pressure gradients can drive downward field-aligned current (FAC) on the dawnside and upward FAC on the duskside, thus make contributions to the NECD and formation of SCW. THEMIS in situ data and all-sky auroral images for two events are presented, followed by a brief discussion.

  8. Scaled conjugate gradient algorithms for unconstrained optimization

    Microsoft Academic Search

    Neculai Andrei

    2007-01-01

    In this work we present and analyze a new scaled conjugate gradient algorithm and its implementation, based on an interpretation\\u000a of the secant equation and on the inexact Wolfe line search conditions. The best spectral conjugate gradient algorithm SCG\\u000a by Birgin and Martínez (2001), which is mainly a scaled variant of Perry’s (1977), is modified in such a manner to

  9. Topics in Dynamic Meteorology: Pressure Gradient Force

    NSDL National Science Digital Library

    2014-09-14

    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.

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

    Microsoft Academic Search

    Antonio Gelsomino; Anneke C Keijzer-Wolters; Giovanni Cacco; Jan Dirk van Elsas

    1999-01-01

    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

  11. 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

  12. Gradient estimation using wide support operators.

    PubMed

    Senel, Hakan Guray

    2009-04-01

    One of the fastest methods of localizing edges in images is based on small gradient kernels, such as Sobel, Prewitt, and Roberts. Although small gradient kernels provide a fast way of computing the gradients, they have little control over noise, edge location, and edge orientation. They are known to be only sensitive to step edges and fail to detect smooth boundaries. On the other hand, large kernels provide superior noise suppression characteristics, but they suffer from wide response area around edges. They cause edges of neighboring objects to merge due to their wide support. Problems associated with large gradient kernels prevent their widespread usage. This paper presents a fuzzy topology-based method to facilitate the use of larger gradient kernels. The new method effectively limits the response area around the edge and prevents neighboring objects to affect each other. Synthetic images are used to show the superior noise suppression properties and response characteristics to both step and ramp edges. Natural images are also used to assess the performance of the newly proposed topological gradient estimation qualitatively. PMID:19278923

  13. 3D Gradient coil design - Toroidal surfaces

    NASA Astrophysics Data System (ADS)

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

    2009-05-01

    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 coils was obtained as part of the optimisation process. Regularisation is used to solve for the toroidal current densities, whereby the field error is minimised in conjunction with the total power of the coil. The method is applied to the design of unshielded and shielded, whole-body and head coil gradient systems. Preliminary coil windings displaying high gradient homogeneity, low inductance, high efficiency and good force balancing are displayed and discussed. Potential benefits associated with this morphology include self-shielding gradient sets, greater access to cooling mechanisms, a reduction in acoustic noise due to force-balancing, a lessening of patient claustrophobia and greater patient access for clinicians.

  14. Natural Gradient Learning Algorithms for RBF Networks.

    PubMed

    Zhao, Junsheng; Wei, Haikun; Zhang, Chi; Li, Weiling; Guo, Weili; Zhang, Kanjian

    2015-02-01

    Radial basis function (RBF) networks are one of the most widely used models for function approximation and classification. There are many strange behaviors in the learning process of RBF networks, such as slow learning speed and the existence of the plateaus. The natural gradient learning method can overcome these disadvantages effectively. It can accelerate the dynamics of learning and avoid plateaus. In this letter, we assume that the probability density function (pdf) of the input and the activation function are gaussian. First, we introduce natural gradient learning to the RBF networks and give the explicit forms of the Fisher information matrix and its inverse. Second, since it is difficult to calculate the Fisher information matrix and its inverse when the numbers of the hidden units and the dimensions of the input are large, we introduce the adaptive method to the natural gradient learning algorithms. Finally, we give an explicit form of the adaptive natural gradient learning algorithm and compare it to the conventional gradient descent method. Simulations show that the proposed adaptive natural gradient method, which can avoid the plateaus effectively, has a good performance when RBF networks are used for nonlinear functions approximation. PMID:25380332

  15. 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.

  16. 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.

  17. Sulfation of the bikunin chondroitin sulfate chain determines heavy chain·hyaluronan complex formation.

    PubMed

    Lord, Megan S; Day, Anthony J; Youssef, Peter; Zhuo, Lisheng; Watanabe, Hideto; Caterson, Bruce; Whitelock, John M

    2013-08-01

    Inter-?-trypsin inhibitor (I?I) is a complex comprising two heavy chains (HCs) that are covalently bound by an ester bond to chondroitin sulfate (CS), which itself is attached to Ser-10 of bikunin. I?I is essential for the trans-esterification of HCs onto hyaluronan (HA). This process is important for the stabilization of HA-rich matrices during ovulation and some inflammatory processes. Bikunin has been isolated previously by anion exchange chromatography with a salt gradient up to 0.5 M NaCl and found to contain unsulfated and 4-sulfated CS disaccharides. In this study, bikunin-containing fractions in plasma and urine were separated by anion exchange chromatography with a salt gradient of 0.1-1.0 M NaCl, and fractions were analyzed for their reactivity with the 4-sulfated CS linkage region antibody (2B6). The fractions that reacted with the 2B6 antibody (0.5-0.8 M NaCl) were found to predominantly contain sulfated CS disaccharides, including disulfated disaccharides, whereas the fractions that did not react with this antibody (0.1-0.5 M NaCl) contained unsulfated and 4-sulfated CS disaccharides. I?I in the 0.5-0.8 M NaCl plasma fraction was able to promote the trans-esterification of HCs to HA in the presence of TSG-6, whereas the 0.1-0.5 M NaCl fraction had a much reduced ability to transfer HC proteins to HA, suggesting that the CS containing 4-sulfated linkage region structures and disulfated disaccharides are involved in the HC transfer. Furthermore, these data highlight that the structure of the CS attached to bikunin is important for the transfer of HC onto HA and emphasize a specific role of CS chain sulfation. PMID:23801333

  18. Density Gradient Stabilization of Electron Temperature Gradient Driven Turbulence in a Spherical Tokamak

    SciTech Connect

    Ren, Y.; Kaye, S. M.; Mazzucato, E.; Guttenfelder, W.; Bell, R. E.; LeBlanc, B. P. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Domier, C. W.; Lee, K. C.; Luhmann, N. C. Jr. [University of California at Davis, Davis, California 95616 (United States); Smith, D. R. [University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Yuh, H. [Nova Photonics, Inc., Princeton, New Jersey 08540 (United States)

    2011-04-22

    In this Letter we report the first clear experimental observation of density gradient stabilization of electron temperature gradient driven turbulence in a fusion plasma. It is observed that longer wavelength modes, k{sub perpendicular{rho}s} < or approx. 10, are most stabilized by density gradient, and the stabilization is accompanied by about a factor of 2 decrease in the plasma effective thermal diffusivity.

  19. 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.

  20. Magnon localization and Bloch oscillations in finite Heisenberg spin chains in an inhomogeneous magnetic field.

    PubMed

    Kosevich, Yuriy A; Gann, Vladimir V

    2013-06-19

    We study the localization of magnon states in finite defect-free Heisenberg spin-1/2 ferromagnetic chains placed in an inhomogeneous magnetic field with a constant spatial gradient. Continuous transformation from the extended magnon states to the localized Wannier-Zeeman states in a finite spin chain placed in an inhomogeneous field is described both analytically and numerically. We describe for the first time the non-monotonic dependence of the energy levels of magnons, both long and short wavelength, on the magnetic field gradient, which is a consequence of magnon localization in a finite spin chain. We show that, in contrast to the destruction of the magnon band and the establishment of the Wannier-Stark ladder in a vanishingly small field gradient in an infinite chain, the localization of magnon states at the chain ends preserves the memory of the magnon band. Essentially, the localization at the lower- or higher-field chain end resembles the localization of the positive- or negative-effective-mass band quasiparticles. We also show how the beat dynamics of coherent superposition of extended spin waves in a finite chain in a homogeneous or weakly inhomogeneous field transforms into magnon Bloch oscillations of the superposition of localized Wannier-Zeeman states in a strongly inhomogeneous field. We provide a semiclassical description of the magnon Bloch oscillations and show that the correspondence between the quantum and semiclassical descriptions is most accurate for Bloch oscillations of the magnon coherent states, which are built from a coherent superposition of a large number of the nearest-neighbour Wannier-Zeeman states. PMID:23709517

  1. 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

  2. Supply chain design and analysis

    Microsoft Academic Search

    Benita M. Beamon

    1998-01-01

    For years, researchers and practitioners have primarily investigated the various processes within manufacturing supply chains individually. Recently, however, there has been increasing attention placed on the performance, design, and analysis of the supply chain as a whole. This attention is largely a result of the rising costs of manufacturing, the shrinking resources of manufacturing bases, shortened product life cycles, the

  3. Verifying the Hanging Chain Model

    ERIC Educational Resources Information Center

    Karls, Michael A.

    2013-01-01

    The wave equation with variable tension is a classic partial differential equation that can be used to describe the horizontal displacements of a vertical hanging chain with one end fixed and the other end free to move. Using a web camera and TRACKER software to record displacement data from a vibrating hanging chain, we verify a modified version…

  4. Issues in Supply Chain Management

    Microsoft Academic Search

    Douglas M Lambert; Martha C Cooper

    2000-01-01

    Successful supply chain management requires cross-functional integration and marketing must play a critical role. The challenge is to determine how to successfully accomplish this integration. We present a framework for supply chain management as well as questions for how it might be implemented and questions for future research. Case studies conducted at several companies and involving multiple members of supply

  5. 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

  6. SSCM: Service Supply Chain Management

    Microsoft Academic Search

    Arash Shahin

    2010-01-01

    Although service sector is expanding globally, service productivity does not grow as fast as the size and the role of this sector. It can be said that quality design and management issues such as Supply Chain Management (SCM) in the service sector is becoming increasingly important and this importance will continue to grow over this century. Service Supply Chain Management

  7. Cardiolipin biosynthesis and mitochondrial respiratory chain function are interdependent.

    PubMed

    Gohil, Vishal M; Hayes, Paulette; Matsuyama, Shigemi; Schägger, Hermann; Schlame, Michael; Greenberg, Miriam L

    2004-10-01

    Cardiolipin (CL) is an acidic phospholipid present almost exclusively in membranes harboring respiratory chain complexes. We have previously shown that, in Saccharomyces cerevisiae, CL provides stability to respiratory chain supercomplexes and CL synthase enzyme activity is reduced in several respiratory complex assembly mutants. In the current study, we investigated the interdependence of the mitochondrial respiratory chain and CL biosynthesis. Pulse-labeling experiments showed that in vivo CL biosynthesis was reduced in respiratory complexes III (ubiquinol:cytochrome c oxidoreductase) and IV (cytochrome c oxidase) and oxidative phosphorylation complex V (ATP synthase) assembly mutants. CL synthesis was decreased in the presence of CCCP, an inhibitor of oxidative phosphorylation that reduces the pH gradient but not by valinomycin or oligomycin, both of which reduce the membrane potential and inhibit ATP synthase, respectively. The inhibitors had no effect on phosphatidylglycerol biosynthesis or CRD1 gene expression. These results are consistent with the hypothesis that in vivo CL biosynthesis is regulated at the level of CL synthase activity by the DeltapH component of the proton-motive force generated by the functional electron transport chain. This is the first report of regulation of phospholipid biosynthesis by alteration of subcellular compartment pH. PMID:15292198

  8. 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.

  9. 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.

  10. 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.

  11. Nonparametric modeling of neural point processes via stochastic gradient boosting regression.

    PubMed

    Truccolo, Wilson; Donoghue, John P

    2007-03-01

    Statistical nonparametric modeling tools that enable the discovery and approximation of functional forms (e.g., tuning functions) relating neural spiking activity to relevant covariates are desirable tools in neuroscience. In this article, we show how stochastic gradient boosting regression can be successfully extended to the modeling of spiking activity data while preserving their point process nature, thus providing a robust nonparametric modeling tool. We formulate stochastic gradient boosting in terms of approximating the conditional intensity function of a point process in discrete time and use the standard likelihood of the process to derive the loss function for the approximation problem. To illustrate the approach, we apply the algorithm to the modeling of primary motor and parietal spiking activity as a function of spiking history and kinematics during a two-dimensional reaching task. Model selection, goodness of fit via the time rescaling theorem, model interpretation via partial dependence plots, ranking of covariates according to their relative importance, and prediction of peri-event time histograms are illustrated and discussed. Additionally, we use the tenfold cross-validated log likelihood of the modeled neural processes (67 cells) to compare the performance of gradient boosting regression to two alternative approaches: standard generalized linear models (GLMs) and Bayesian P-splines with Markov chain Monte Carlo (MCMC) sampling. In our data set, gradient boosting outperformed both Bayesian P-splines (in approximately 90% of the cells) and GLMs (100%). Because of its good performance and computational efficiency, we propose stochastic gradient boosting regression as an off-the-shelf nonparametric tool for initial analyses of large neural data sets (e.g., more than 50 cells; more than 10(5) samples per cell) with corresponding multidimensional covariate spaces (e.g., more than four covariates). In the cases where a functional form might be amenable to a more compact representation, gradient boosting might also lead to the discovery of simpler, parametric models. PMID:17298229

  12. Application of denaturing gradient gel electrophoresis (DGGE) and temperature gradient gel electrophoresis (TGGE) in microbial ecology

    Microsoft Academic Search

    Gerard Muyzer; Kornelia Smalla

    1998-01-01

    Here, the state of the art of the application of denaturing gradient gel electrophoresis (DGGE) and temperature gradient gel electrophoresis (TGGE) in microbial ecology will be presented. Furthermore, the potentials and limitations of these techniques will be discussed, and it will be indicated why their use in ecological studies has become so important. Abbreviations: ARDRA - amplified ribosomal DNA restriction

  13. 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

  14. Gradient, Non-Gradient and Hybrid Algorithms for Optimizing 3D Forging Sequences with Uncertainties

    E-print Network

    Paris-Sud XI, Université de

    in order to minimize the potential of fold formation. Keywords: Optimization Algorithm, Response Surface be substituted to the exact evaluations of the objective function within costly global algorithmsGradient, Non-Gradient and Hybrid Algorithms for Optimizing 3D Forging Sequences with Uncertainties

  15. Synthesis of Gradient Copolymers with a Controlled Composition Profile

    E-print Network

    Petta, Jason

    11 21 2 11 1 2 frfffr fffr F ++ + = #12;PSnBA Gradient Copolymer ­ H3 · Initial Concentration of 100Synthesis of Gradient Copolymers with a Controlled Composition Profile Ha-Kyung Kwon #12;Synthesis of Gradient Copolymers · Goal: ­ To control the composition profile of gradient copolymers · Motivation

  16. Membrane properties of cholesterol analogs with an unbranched aliphatic side chain.

    PubMed

    Meyer, Thomas; Baek, Dong Jae; Bittman, Robert; Haralampiev, Ivan; Müller, Peter; Herrmann, Andreas; Huster, Daniel; Scheidt, Holger A

    2014-12-01

    The interactions between cholesterol and other membrane molecules determine important membrane properties. It was shown that even small changes in the molecular structure of cholesterol have a crucial influence on these interactions. We recently reported that in addition to alterations in the tetracyclic ring structure, the iso-branched side chain of cholesterol also has a significant impact on membrane properties (Scheidt et al., 2013). Here we used synthetic cholesterol analogs to investigate the influence of an unbranched aliphatic side chain of different length. The (2)H NMR order parameter of the phospholipid chains and therefore the molecular packing of the phospholipid molecules shows a significant dependence on the sterol's alkyl side chain length, while, membrane permeation studied by a dithionite ion permeation assay and lateral diffusion measured by (1)H MAS pulsed field gradient NMR are less influenced. To achieve the same molecular packing effect similar to that of an iso-branched aliphatic side chain, a longer unbranched side chain (n-dodecyl instead of n-octyl) at C17 of cholesterol is required. Obviously, sterols having a branched iso-alkyl chain with two terminal methyl groups exhibit altered cholesterol-phospholipid interactions compared to analogous molecules with a straight unbranched chain. PMID:25173446

  17. Gradient maintenance using discrete brine injections in a salt gradient solar pond

    SciTech Connect

    Sherman, B.S. (CSIRO, Canberra (Australia))

    1992-10-01

    A method for the maintenance of the stratification in the gradient zone of a salt gradient solar pond is presented. The method is unique for solar ponds in that it involves the injection of highly turbulent columnar jets into homogeneous convective zones. This contrasts with the more common practice of traversing the gradient zone with a disk-shaped diffuser while injecting fluid at low exit Froude numbers. Using turbulent jet theory which is well understood for columnar buoyant jets, the method allows a priori determination of the resulting salinity gradient with a reasonable level of confidence. The simple injector is easily constructed and deployed. Field data collected at the Alice Springs solar pond show that the technique can quickly remove internal convective zones as well as extend the top of the gradient into the surface layer, providing a valuable tool for the operators of solar ponds.

  18. Ceramic transactions: Functionally gradient materials. Volume 34

    SciTech Connect

    Holt, J.B.; Koizumi, Mitsue; Hirai, Toshio; Munir, Z.A. (eds.)

    1993-01-01

    A functionally gradient material (FGM) is a composite that smoothly transitions from one material at one surface to another material at the opposite surface. Metals and ceramics are usually the materials that are combined in a controlled manner to optimize a specific property. The First International Symposium on Functionally Gradient Materials was held in Sendai, Japan, in August 1990. Contained in the present volume are the Proceedings of the Second International Symposium on Functionally Gradient Materials, presented at the Third International Ceramic Science and Technology Congress, held in San Francisco, CA, November 1-4, 1992. The papers presented here are divided into eight sections: the concept of FGM; mathematical modeling; methods of fabrication; material evaluation; applications; joining processes in FGM; process characterization; and design considerations. Separate abstracts are provided for each of the 54 papers.

  19. Variable gradient permanent-magnet quadrupole lenses

    SciTech Connect

    O'Shea, P.G.; Zaugg, T.J.; Maggs, R.G.; Schafstall, P.; Dyson, J.E.

    1989-01-01

    Rare earth (RE) permanent-magnet quadrupoles (PMQs) have been used for many applications in particle accelerators. They have the advantage over electromagnets of being lightweight and reliable. One difficulty associated with PMQs is that the quadrupole gradient is not easily adjusted. Over a certain range, the magnetization of RE magnets is a reversible function of temperature. We have developed a scheme to use this property to make variable gradient PMQs. The field gradient changes required for tuning are typically on the order of a few percent. For many RE magnets, this requires temperature changes of a few tens of degrees centigrade and is accomplished by actively heating or cooling the quadrupoles. 8 refs., 7 figs.

  20. Relativistic klystrons for high-gradient accelerators

    SciTech Connect

    Westenskow, G.A.; Aalberts, D.P.; Boyd, J.K.; Deis, G.A.; Houck, T.L.; Orzechowski, T.J.; Ryne, R.D.; Yu, S.S. (Lawrence Livermore National Lab., CA (USA)); Allen, M.A.; Callin, R.S.; Deruyter, H.; Eppley, K.R.; Fant, K.S.; Fowkes, W.R.; Hoag, H.A.; Koontz, R.F.; Lavine, T.L.; Loew, G.A.; Miller, R.H.; Ruth, R.D.; Vlieks, A.E.; Wang, J.W. (Stanford Linear Accelerator Center, Menlo Park, CA (USA)); Haimson, J.; Mecklen

    1990-09-05

    Experimental work is being performed by collaborators at LLNL, SLAC, and LBL to investigate relativistic klystrons as a possible rf power source for future high-gradient accelerators. We have learned how to overcome or previously reported problem of high power rf pulse shortening and have achieved peak rf power levels of 330 MW using an 11.4-GHz high-gain tube with multiple output structures. In these experiments the rf pulse is of the same duration as the beam current pulse. In addition, experiments have been performed on two short sections of a high-gradient accelerator using the rf power from a relativistic klystron. An average accelerating gradient of 84 MV/m has been achieved with 80-MW of rf power.

  1. 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

  2. Recovering gradients from sparsely observed functional data

    PubMed Central

    Lóez-Pintado, Sara; McKeague, Ian W.

    2013-01-01

    The recovery of gradients of sparsely observed functional data is a challenging ill-posed inverse problem. Given observations of smooth curves (e.g., growth curves) at isolated time points, the aim is to provide estimates of the underlying gradients (or growth velocities). To address this problem, we develop a Bayesian inversion approach that models the gradient in the gaps between the observation times by a tied-down Brownian motion, conditionally on its values at the observation times. The posterior mean and covariance kernel of the growth velocities are then found to have explicit and computationally tractable representations in terms of quadratic splines. The hyperparameters in the prior are specified via nonparametric empirical Bayes, with the prior precision matrix at the observation times estimated by constrained ?1 minimization. The infinitessimal variance of the Brownian motion prior is selected by cross-validation. The approach is illustrated using both simulated and real data examples. PMID:23409753

  3. Bacterial chemotaxis without gradient-sensing.

    PubMed

    Yoon, Changwook; Kim, Yong-Jung

    2015-05-01

    Chemotaxis models are based on spatial or temporal gradient measurements by individual organisms. The key contribution of Keller and Segel (J Theor Biol 30:225-234, 1971a; J Theor Biol 30:235-248, 1971b) is showing that erratic measurements of individuals may result in an accurate chemotaxis phenomenon as a group. In this paper we provide another option to understand chemotactic behavior when individuals do not sense the gradient of chemical concentration by any means. We show that, if individuals increase their dispersal rate to find food when there is not enough food, an accurate chemotactic behavior may be obtained without sensing the gradient. Such a dispersal has been suggested by Cho and Kim (Bull Math Biol 75:845-870, 2013) and was called starvation driven diffusion. This model is surprisingly similar to the original Keller-Segel model. A comprehensive picture of traveling bands and fronts is provided. PMID:24865467

  4. Density Gradient Centrifugation Studies on Rabies Virus

    PubMed Central

    Neurath, A. Robert; Wiktor, Tadeusz J.; Koprowski, Hilary

    1966-01-01

    Neurath, A. Robert (The Wistar Institute, Philadelphia, Pa.), Tadeusz J. Wiktor, and Hilary Koprowski. Density gradient centrifugation studies on rabies virus. J. Bacteriol. 92:102–106. 1966.—Cesium chloride density gradient centrifugation of rabies virus revealed a heterogeneous population of infectious virus particles, the majority of which showed a density of 1.20 g/ml. From results obtained by rate zonal centrifugation in preformed sucrose gradients, it was possible to calculate a sedimentation coefficient of about 600S for rabies virus. Sedimentation coefficients of about 23S and 10S were calculated for two soluble rabies antigens present in infected tissue-culture fluids, and they showed a density of 1.26 g/ml in cesium chloride solutions. PMID:5941269

  5. Substrate curvature gradient drives rapid droplet motion.

    PubMed

    Lv, Cunjing; Chen, Chao; Chuang, Yin-Chuan; Tseng, Fan-Gang; Yin, Yajun; Grey, Francois; Zheng, Quanshui

    2014-07-11

    Making small liquid droplets move spontaneously on solid surfaces is a key challenge in lab-on-chip and heat exchanger technologies. Here, we report that a substrate curvature gradient can accelerate micro- and nanodroplets to high speeds on both hydrophilic and hydrophobic substrates. Experiments for microscale water droplets on tapered surfaces show a maximum speed of 0.42??m/s, 2 orders of magnitude higher than with a wettability gradient. We show that the total free energy and driving force exerted on a droplet are determined by the substrate curvature and substrate curvature gradient, respectively. Using molecular dynamics simulations, we predict nanoscale droplets moving spontaneously at over 100??m/s on tapered surfaces. PMID:25062213

  6. Gradient Sensing in Reactive, Ternary Membranes

    NASA Astrophysics Data System (ADS)

    Kuksenok, Olga; Balazs, Anna C.

    2009-03-01

    Using computer simulations, we investigate the behavior of reactive ternary ABC membranes that are subjected to an external, spatially nonuniform stimulus, which controls the rate of interconversion between the A and B components. We assume that A and B have different spontaneous curvatures. Furthermore, the C component is taken to be nonreactive and incompatible with both A and B. We find that a gradient in the applied stimulus causes the dynamic reconstruction of the membrane, with a preferential reorientation of the reactive AB domains along the gradient. In addition, the external gradient effectively controls the transport of the nonreactive C component within the membrane. The latter effect could potentially be exploited for cleaning the membrane of the nonreactive C impurities or for the targeted delivery of the C component to specific locations.

  7. METALLICITY GRADIENTS OF THICK DISK DWARF STARS

    SciTech Connect

    Carrell, Kenneth; Chen Yuqin; Zhao Gang, E-mail: carrell@nao.cas.cn [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

    2012-12-01

    We examine the metallicity distribution of the Galactic thick disk using F, G, and K dwarf stars selected from the Sloan Digital Sky Survey, Data Release 8. Using the large sample of dwarf stars with proper motions and spectroscopically determined stellar parameters, metallicity gradients in the radial direction for various heights above the Galactic plane and in the vertical direction for various radial distances from the Galaxy center have been found. In particular, we find a vertical metallicity gradient of -0.113 {+-} 0.010 (-0.125 {+-} 0.008) dex kpc{sup -1} using an isochrone (photometric) distance determination in the range 1 kpc <|Z| < 3 kpc, which is the vertical height range most consistent with the thick disk of our Galaxy. In the radial direction, we find metallicity gradients between +0.02 and +0.03 dex kpc{sup -1} for bins in the vertical direction between 1 kpc <|Z| < 3 kpc. Both of these results agree with similar values determined from other populations of stars, but this is the first time a radial metallicity gradient for the thick disk has been found at these vertical heights. We are also able to separate thin and thick disk stars based on kinematic and spatial probabilities in the vertical height range where there is significant overlap of these two populations. This should aid further studies of the metallicity gradients of the disk for vertical heights lower than those studied here but above the solar neighborhood. Metallicity gradients in the thin and thick disks are important probes into possible formation scenarios for our Galaxy and a consistent picture is beginning to emerge from results using large spectroscopic surveys, such as the ones presented here.

  8. 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.

  9. Density gradient expansion of correlation functions

    NASA Astrophysics Data System (ADS)

    van Leeuwen, Robert

    2013-04-01

    We present a general scheme based on nonlinear response theory to calculate the expansion of correlation functions such as the pair-correlation function or the exchange-correlation hole of an inhomogeneous many-particle system in terms of density derivatives of arbitrary order. We further derive a consistency condition that is necessary for the existence of the gradient expansion. This condition is used to carry out an infinite summation of terms involving response functions up to infinite order from which it follows that the coefficient functions of the gradient expansion can be expressed in terms of the local density profile rather than the background density around which the expansion is carried out. We apply the method to the calculation of the gradient expansion of the one-particle density matrix to second order in the density gradients and recover in an alternative manner the result of Gross and Dreizler [Gross and Dreizler, Z. Phys. AZPAADB0340-219310.1007/BF01413038 302, 103 (1981)], which was derived using the Kirzhnits method. The nonlinear response method is more general and avoids the turning point problem of the Kirzhnits expansion. We further give a description of the exchange hole in momentum space and confirm the wave vector analysis of Langreth and Perdew [Langreth and Perdew, Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.21.5469 21, 5469 (1980)] for this case. This is used to derive that the second-order gradient expansion of the system averaged exchange hole satisfies the hole sum rule and to calculate the gradient coefficient of the exchange energy without the need to regularize divergent integrals.

  10. Chains-into-Bins Processes

    NASA Astrophysics Data System (ADS)

    Batu, Tu?kan; Berenbrink, Petra; Cooper, Colin

    The study of balls-into-bins processes or occupancy problems has a long history. These processes can be used to translate realistic problems into mathematical ones in a natural way. In general, the goal of a balls-into-bins process is to allocate a set of independent objects (tasks, jobs, balls) to a set of resources (servers, bins, urns) and, thereby, to minimize the maximum load. In this paper, we analyze the maximum load for the chains-into-bins problem, which is defined as follows. There are n bins, and m objects to be allocated. Each object consists of balls connected into a chain of length ?, so that there are m ? balls in total. We assume the chains cannot be broken, and that the balls in one chain have to be allocated to ? consecutive bins. We allow each chain d independent and uniformly random bin choices for its starting position. The chain is allocated using the rule that the maximum load of any bin receiving a ball of that chain is minimized. We show that, for d ? 2 and m·?= O(n), the maximum load is ((ln ln m)/ln d) + O(1) with probability 1-tilde O(1/m^{d-1}).

  11. 17 GHz High Gradient Accelerator Research

    SciTech Connect

    Temkin, Richard J. [MIT] [MIT; Shapiro, Michael A. [MIT] [MIT

    2013-07-10

    This is a report on the MIT High Gradient Accelerator Research program which has included: Operation of the 17 GHz, 25 MeV MIT/Haimson Research Corp. electron accelerator at MIT, the highest frequency, stand-alone accelerator in the world; collaboration with members of the US High Gradient Collaboration, including the design and test of novel structures at SLAC at 11.4 GHz; the design, construction and testing of photonic bandgap structures, including metallic and dielectric structures; the investigation of the wakefields in novel structures; and the training of the next generation of graduate students and postdoctoral associates in accelerator physics.

  12. Critique of the vertical gradient of gravity

    NASA Technical Reports Server (NTRS)

    Hammer, Sigmund

    1989-01-01

    Growing interest in high precision studies of the Earth's gravitational field warrant a critical review of precision requirements to yield useful results. Several problems are now under consideration. All of these problems involve, more or less, the precise value of the vertical gradients of gravity. The principle conclusion from this review is that the essential absence of Free Air Vertical Gravity Gradient control and actual values of gravimeter calibrations require serious attention. Large errors in high topography on official published gravity maps also cannot be ignored.

  13. Short wavelength ion temperature gradient turbulence

    SciTech Connect

    Chowdhury, J.; Ganesh, R. [Institute for Plasma Research, Bhat, Gandhinagar (India); Brunner, S.; Lapillonne, X.; Villard, L. [CRPP, Association EURATOM-Confederation Suisse, EPFL, 1015 Lausanne (Switzerland); Jenko, F. [Max-Planck-Institut fuer Plasmaphysik Boltzmannstr. 2, D-85748 Garching (Germany)

    2012-10-15

    The ion temperature gradient (ITG) mode in the high wavenumber regime (k{sub y}{rho}{sub s}>1), referred to as short wavelength ion temperature gradient mode (SWITG) is studied using the nonlinear gyrokinetic electromagnetic code GENE. It is shown that, although the SWITG mode may be linearly more unstable than the standard long wavelength (k{sub y}{rho}{sub s}<1) ITG mode, nonlinearly its contribution to the total thermal ion heat transport is found to be low. We interpret this as resulting from an increased zonal flow shearing effect on the SWITG mode suppression.

  14. 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.

  15. High-pressure liquid chromatographic gradient mixer

    DOEpatents

    Daughton, C.G.; Sakaji, R.H.

    1982-09-08

    A gradient mixer effects the continuous mixing of any two miscible solvents without excessive decay or dispersion of the resultant isocratic effluent or of a linear or exponential gradient. The two solvents are fed under low or high pressure by means of two high performance liquid chromatographic pumps. The mixer comprises a series of ultra-low dead volume stainless steel tubes and low dead volume chambers. The two solvent streams impinge head-on at high fluxes. This initial nonhomogeneous mixture is then passed through a chamber packed with spirally-wound wires which cause turbulent mixing thereby homogenizing the mixture with minimum band-broadening.

  16. High pressure liquid chromatographic gradient mixer

    DOEpatents

    Daughton, Christian G. (San Pablo, CA); Sakaji, Richard H. (El Cerrito, CA)

    1985-01-01

    A gradient mixer which effects the continuous mixing of any two miscible solvents without excessive decay or dispersion of the resultant isocratic effluent or of a linear or exponential gradient. The two solvents are fed under low or high pressure by means of two high performance liquid chromatographic pumps. The mixer comprises a series of ultra-low dead volume stainless steel tubes and low dead volume chambers. The two solvent streams impinge head-on at high fluxes. This initial nonhomogeneous mixture is then passed through a chamber packed with spirally-wound wires which cause turbulent mixing thereby homogenizing the mixture with minimum "band-broadening".

  17. A new nonlinear conjugate gradient method

    NASA Astrophysics Data System (ADS)

    Abdelrahman, Awad; Mamat, Mustafa; Mohd, Ismail bin; Rivaie, Mohd; Omer, Osman

    2015-02-01

    Conjugate gradient (CG) methods are essential for solving large-scale unconstrained optimization problems. Many of studies and modifications have been practiced to improve this method. In this paper, a new class of conjugate gradient coefficients (?k) with a new parameter m = ?g/k? ?dk-1? that possess global convergence properties is presented. The global convergence and sufficient decent property result is established using inexact line searches to determine the step size of CG, denoted as ?k. Numerical result shows that the new formula is superior and more efficient when compared to other CG coefficients.

  18. 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

  19. Design of spherical symmetric gradient index lenses

    NASA Astrophysics Data System (ADS)

    Miñano, Juan C.; Grabovi?ki?, Dejan; Benítez, Pablo; González, Juan C.; Santamaría, Asunción

    2012-10-01

    Spherical symmetric refractive index distributions also known as Gradient Index lenses such as the Maxwell-Fish-Eye (MFE), the Luneburg or the Eaton lenses have always played an important role in Optics. The recent development of the technique called Transformation Optics has renewed the interest in these gradient index lenses. For instance, Perfect Imaging within the Wave Optics framework has recently been proved using the MFE distribution. We review here the design problem of these lenses, classify them in two groups (Luneburg moveable-limits and fixed-limits type), and establish a new design techniques for each type of problem.

  20. Microfabricated refractive index gradient based detector for reversed-phase liquid chromatography with mobile phase gradient elution

    Microsoft Academic Search

    Adam D. McBrady; Robert E. Synovec

    2006-01-01

    Typical refractive index (RI) detectors for liquid chromatography (LC) are not well suited to application with mobile phase gradient elution, due to the difficulty in correcting for the detected baseline shift during the gradient. We report a sensitive, highly reproducible, microfabricated refractive index gradient (micro-RIG) detector that performs well with mobile phase gradient elution LC. Since the micro-RIG signal remains

  1. Axonal Gradient of Arachidonic Acid-containing Phosphatidylcholine and Its Dependence on Actin Dynamics*

    PubMed Central

    Yang, Hyun-Jeong; Sugiura, Yuki; Ikegami, Koji; Konishi, Yoshiyuki; Setou, Mitsutoshi

    2012-01-01

    Phosphatidylcholine (PC) is the most abundant component of lipid bilayers and exists in various molecular forms, through combinations of two acylated fatty acids. Arachidonic acid (AA)-containing PC (AA-PC) can be a source of AA, which is a crucial mediator of synaptic transmission and intracellular signaling. However, the distribution of AA-PC within neurons has not been indicated. In the present study, we used imaging mass spectrometry to characterize the distribution of PC species in cultured neurons of superior cervical ganglia. Intriguingly, PC species exhibited a unique distribution that was dependent on the acyl chains at the sn-2 position. In particular, we found that AA-PC is enriched within the axon and is distributed across a proximal-to-distal gradient. Inhibitors of actin dynamics (cytochalasin D and phallacidin) disrupted this gradient. This is the first report of the gradual distribution of AA-PC along the axon and its association with actin dynamics. PMID:22207757

  2. 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.

  3. Sequential sludge digestion after diverse pre-treatment conditions: sludge removal, methane production and microbial community changes.

    PubMed

    Park, Sang Kyu; Jang, Hyun Min; Ha, Jeong Hyub; Park, Jong Moon

    2014-06-01

    A lab-scale sequential sludge digestion process which consists of a mesophilic anaerobic digester (MAD) and a thermophilic aerobic digester (TAD) was developed. Thermal, thermal-alkaline and long-term alkaline pre-treatments were applied to the feed sludge to examine their effects on sludge removal and methane production. Especially after thermal-alkaline pre-treatment, high COD removal was maintained; methane production rate was also drastically increased by improving the hydrolysis step of sludge degradation. Polymerase chain reaction-denaturing gel gradient electrophoresis indicated that bacterial communities were represented by three phyla (Firmicutes, Proteobacteria, Actinobacteria) and that Clostridium straminisolvens was the major bacterial species in MAD. Quantitative real-time PCR results indicated that Methanosaeta concilli was the major archaeal species in MAD, and that Ureibacillus sp. was the most abundant bacterial species in TAD. PMID:24768888

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

    PubMed Central

    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

    2014-01-01

    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. PMID:25141868

  5. 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 ...

  6. 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 ...

  7. Gradient and counter-gradient scalar transport in turbulent premixed flames

    NASA Astrophysics Data System (ADS)

    Veynante, D.; Trouvé, A.; Bray, K. N. C.; Mantel, T.

    1997-02-01

    In premixed turbulent combustion, the modelling of the turbulent flux of the mean reaction progress variable c˜, rho;u[double prime or second]ic[double prime or second], remains, remains somewhat controversial. Classical gradient transport assumptions based on the eddy viscosity concept are often used while both experimental data and theoretical analysis have pointed out the existence of counter-gradient turbulent diffusion. Direct numerical simulation (DNS) is used in this paper to provide basic information on the turbulent flux of c˜ and study the occurrence of counter-gradient transport. The numerical configuration corresponds to two- or three-dimensional premixed flames in isotropic turbulent flow. The simulations correspond to various flame and flow conditions that are representative of flamelet combustion. They reveal that different flames will feature different turbulent transport properties and that these differences can be related to basic dynamical differences in the flame flow interactions: counter-gradient diffusion occurs when the flow field near the flame is dominated by thermal dilatation due to chemical reaction, whereas gradient diffusion occurs when the flow field near the flame is dominated by the turbulent motions. The DNS-based analysis leads to a simple expression to describe the turbulent flux of c˜, which in turn leads to a simple criterion to delineate between the gradient and counter-gradient turbulent diffusion regimes. This criterion suggests that the occurrence of one regime or the other is determined primarily by the ratio of turbulence intensity divided by the laminar flame speed, u[prime prime or minute]/sL, and by the flame heat release factor, [tau] [identical with] (Tb [minus sign] Tu)/Tu, where Tu and Tb are respectively the temperature within unburnt and burnt gas. Consistent with the Bray Moss Libby theory, counter-gradient (gradient) diffusion is promoted by low (high) values of u[prime prime or minute]/sL and high (low) values of [tau]. DNS also shows that these results are not restricted to the turbulent transport of c˜. Similar results are found for the turbulent transport of flame surface density, [Sigma]. The turbulent fluxes of c˜ and [Sigma] are strongly correlated in the simulated flames and counter-gradient (gradient) diffusion of c˜ always coincides with counter-gradient (gradient) diffusion of [Sigma].

  8. 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.

  9. Decoherence in Quantum Markov Chains

    E-print Network

    Raqueline A. M. Santos; Renato Portugal; Marcelo D. Fragoso

    2015-02-23

    It is known that under some assumptions the hitting time in quantum Markov chains is quadratically smaller than the hitting time in classical Markov chains. This work extends this result for decoherent quantum Markov chains. The decoherence is introduced using a percolation-like graph model, which allows us to define a decoherent quantum hitting time and to establish a decoherent-intensity range for which the decoherent quantum hitting time is quadratically smaller than the the classical hitting time. The detection problem under decoherence is also solved with quadratic speedup in this range.

  10. Dynamic Supply Chains, Transportation Network Equilibria,

    E-print Network

    Nagurney, Anna

    Dynamic Supply Chains, Transportation Network Equilibria, and Evolutionary Variational Inequalities have described the various networks that underlie supply chain analysis and management with the goal presented apparently the first supply chain network equilibrium model. · The objective of this research

  11. Dynamic Supply Chains, Transportation Network Equilibria,

    E-print Network

    Nagurney, Anna

    Dynamic Supply Chains, Transportation Network Equilibria, and Evolutionary Variational Inequalities Isenberg School of Management University of Massachusetts Amherst Fifth Annual Florida Supply Chain;Outline · Research Motivation · Overview of the Supply Chain Network Equilibrium Model · Overview

  12. The Offshore Services Global Value Chain

    E-print Network

    Richardson, David

    The Offshore Services Global Value Chain ECONOMIC UPGRADING AND WORKFORCE DEVELOPMENT Karina & COMPETITIVENESS #12;The Offshore Services Global Value Chain: Economic Upgrading and Workforce Development "Skills for Upgrading: Workforce Development and Global Value Chains in Developing Countries" This research project

  13. Invited Review Supply chain management and advanced

    E-print Network

    Grossmann, Ignacio E.

    Invited Review Supply chain management and advanced planning­­basics, overview and challenges Hartmut Stadtler Fachgebiet Produktion & Supply Chain Management, Institut fur Betriebswirtschaftslehre Abstract Literature on supply chain management (SCM) covers several disciplines and is growing rapidly

  14. Design of Sustainable Supply Chains Sustainable Cities

    E-print Network

    Nagurney, Anna

    Chains The Sustainable Supply Chain Network Model with Frequency of Activities Numerical Examples Summary their own needs (World Commission Environment and Development (WCED) (1987)). Anna Nagurney SustainabilityDesign of Sustainable Supply Chains for Sustainable Cities Anna Nagurney Isenberg School

  15. Total supply chain cost model

    E-print Network

    Wu, Claudia

    2005-01-01

    Sourcing and outsourcing decisions have taken on increased importance within Teradyne to improve efficiency and competitiveness. This project delivered a conceptual framework and a software tool to analyze supply chain ...

  16. JOHN GLENN CENTER Key Chain

    NSDL National Science Digital Library

    1900-01-01

    Brushed Stainless steel key chain with LED light, color engraved with the John Glenn Center for Science Education logo. All proceeds from the sale of this item go to fund the John Glenn Center for Science Education.

  17. 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.

  18. First-principle study on energetics and electronic structure of a single copper atomic chain bound in carbon nanotube

    Microsoft Academic Search

    X.-J. Du; J.-M. Zhang; S.-F. Wang; K.-W. Xu; V. Ji

    2009-01-01

    Under the generalized gradient approximation (GGA), the energy and electronic structure of a single copper atomic chain bound in an armchair (6, 6) or zigzag (10, 0) carbon nanotube (CNT) have been investigated by using the first-principles projector-augmented wave (PAW) potential within the density function theory (DFT) framework. The results show that both CNTs are nearly ideal to bind a

  19. Adhesion and Chaining of Magnetic Particles K. German, H. Mizes, L. Belkhir and R. Lewis, Xerox Corporation, Webster, NY 14580

    E-print Network

    are permanent magnets that sit on a non-magnetic surface, called a sleeve. Below the surface are a series by the competing magnetic forces. For two magnetic dipoles, the interaction is attractive if the south pole of one. This forces the chains that fonn to align with the magnetic field. However, if there is a gradient

  20. 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.

  1. 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

  2. Learning to rank using gradient descent

    Microsoft Academic Search

    Christopher J. C. Burges; Tal Shaked; Erin Renshaw; Ari Lazier; Matt Deeds; Nicole Hamilton; Gregory N. Hullender

    2005-01-01

    We investigate using gradient descent meth- ods for learning ranking functions; we pro- pose a simple probabilistic cost function, and we introduce RankNet, an implementation of these ideas using a neural network to model the underlying ranking function. We present test results on toy data and on data from a commercial internet search engine.

  3. Latitudinal temperature gradients and climate change

    Microsoft Academic Search

    D. Rind

    1998-01-01

    The effects of a change in the latitudinal sea surface temperature gradient are investigated in several GCM experiments. Sea surface temperatures are increased\\/decreased in the tropics and polar regions, with little change in the global average surface air temperature. Then the experiments are repeated with colder\\/warmer conditions globally. Expectations generated from these runs are compared with the resulting climate changes

  4. Scaling of vertical temperature gradient spectra

    Microsoft Academic Search

    D. R. Caldwell; T. M. Dillon; J. M. Brubaker; P. A. Newberger; C. A. Paulson

    1980-01-01

    Tests of a formula derived for the cutoff wave number of vertical temperature gradient spectra, using data taken in the upper layers of the North Pacific, show encouraging results. To derive this formula, the cutoff wave number is assumed to be the Batchelor wave number, with kinetic energy dissipation calculated by combining a form used in the atmosphere for caLculating

  5. Permeability of granite in a temperature gradient

    Microsoft Academic Search

    C. Morrow; D. Lockner; D. Moore; J. Byerlee

    1981-01-01

    Changes in permeability of granite were measured as water flowed through samples in a temperature gradient. The experimental conditions simulated those around the 'very deep hole concept' nuclear waste repository. Temperature was maintained between 200° and 310°C, in a borehole of a cylindrical sample. Confining pressures of 30 and 60 MPa, with corresponding pore pressures of 10 and 20 MPa,

  6. Thermal fracture of functionally gradient ceramics

    Microsoft Academic Search

    Zhi-He Jin; Yiu-Wing Mai

    1996-01-01

    An edge crack in a strip of functionally gradient ceramics (FGC) is studied under thermal loading conditions. Two FGC materials are considered, i.e., one with a spatial variation of shear modulus and the other with a spatial variation of thermal conductivity. Thermal stress intensity factors (TSIF) are numerically calculated based on singular integral equations derived for the dislocation density along

  7. Title: DISTINGUISHING MODES OF EUKARYTIC GRADIENT SENSING

    E-print Network

    Anlage, Steven

    that allows biological cells to detect and respond to external gradients of small molecules with directed chemotaxis, is essential for biological functions ranging from immune response in higher animals to the food Directed By: Professor Wolfgang Losert and Dr. Ralph Nossal The behaviors of biological systems depend

  8. Gradient Clock Synchronization in Wireless Sensor Networks

    E-print Network

    Gradient Clock Synchronization in Wireless Sensor Networks Philipp Sommer Computer Engineering- olution. Without doubt, time is a first-class citizen in wireless sensor networks. Without accurate time if the nodes in the wireless sensor network manage to have an adequate agreement of time. Indeed

  9. Time changes in gradient and observed winds

    E-print Network

    Carlson, Ronald Dale

    1972-01-01

    and the tangen- tial acceleration. It would be'nice to conclude that any differences between changes in the gradient wind and changes in the actual wind are due to the frictional force and/or tangential acceleration. However, Mantis (1968) points out...

  10. Joining of Tungsten Armor Using Functional Gradients

    SciTech Connect

    John Scott O'Dell

    2006-12-31

    The joining of low thermal expansion armor materials such as tungsten to high thermal expansion heat sink materials has been a major problem in plasma facing component (PFC) development. Conventional planar bonding techniques have been unable to withstand the high thermal induced stresses resulting from fabrication and high heat flux testing. During this investigation, innovative functional gradient joints produced using vacuum plasma spray forming techniques have been developed for joining tungsten armor to copper alloy heat sinks. A model was developed to select the optimum gradient architecture. Based on the modeling effort, a 2mm copper rich gradient was selected. Vacuum plasma pray parameters and procedures were then developed to produce the functional gradient joint. Using these techniques, dual cooling channel, medium scale mockups (32mm wide x 400mm length) were produced with vacuum plasma spray formed tungsten armor. The thickness of the tungsten armor was up to 5mm thick. No evidence of debonding at the interface between the heat sink and the vacuum plasma sprayed material was observed.

  11. 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

  12. Gradient methods for geophysical image inversions

    SciTech Connect

    Frank, M.S.; Balanis, C.A.

    1986-09-01

    This paper presents a conjugate-gradient algorithm adapted to solve the linear equations, Ax = b, arising from simulated electromagnetic geophysical data. Four test cases are considered, and reconstructions are obtained that compare favorably with those obtained using the standard ART algorithms.

  13. Density Gradient Columns for Chemical Displays.

    ERIC Educational Resources Information Center

    Guenther, William B.

    1986-01-01

    Procedures for preparing density gradient columns for chemical displays are presented. They include displays illustrating acid-base reactions, metal ion equilibria, and liquid density. The lifetime of these metastable displays is surprising, some lasting for months in display cabinets. (JN)

  14. Moving Forward: Mechanisms of Chemoattractant Gradient Sensing

    NSDL National Science Digital Library

    PhD Jonathan Franca-Koh (Johns Hopkins University School of Medicine Department of Cell Biology)

    2004-10-01

    Cells use an internal compass to sense the direction of chemoattractant gradients. This is used to bias pseudopod extension at the front of the cell and to orient cell polarization. Recent studies have highlighted the important roles played by phosphoinositide-3,4,5-triphosphate and small G proteins, but many questions remain.

  15. Inexact projected gradient method for vector optimization

    E-print Network

    2011-06-15

    Keywords: Weak efficiency; Multiobjective optimization; Projected gradient .... points. Finally, we mention that the proposed method can also be seen as a direct ... ness hypothesis on the cone and adding some new conditions, we establish ... proof a technical result, which cannot be found on the aforementioned papers, ...

  16. Social Class Gradients and Health in Childhood

    Microsoft Academic Search

    Barbara Starfield; Judy Robertson; Anne W. Riley

    2002-01-01

    Objective.— To determine if there are social class gradients in health in children aged 6 to 11 years. Methods.— Self and parent reports of health of children in 5 sites across the United States were assessed using the Child Health and Illness Profile-Child Edition. Distribution of scores in 4 domains: satisfaction (with health); comfort; resilience; and risk avoidance were used

  17. Stochastic Compositional Gradient Descent: Algorithms for ...

    E-print Network

    2014-11-14

    and quasi-gradient has a long history in the literature of SA; see for example Kiefer and ... under basic assumptions; see also [11] Section 6.7 for a brief discussion. ... update incrementally by making use of one component at a time, through a ...

  18. The microbial food web along salinity gradients

    Microsoft Academic Search

    Carlos Pedrós-Alió; Juan I Calderón-Paz; Marlie H MacLean; Glòria Medina; Cèlia Marrasé; Josep M Gasol; Núria Guixa-Boixereu

    2000-01-01

    The microbial food web was studied along a gradient of salinity in two solar salterns used for the commercial production of salt. The different ponds in the salterns provide a wide range of ecosystems with food webs of different complexities. Abundance of prokaryotes, cell volume, prokaryotic heterotrophic production, chlorophyll a, abundance of heterotrophic flagellates, ciliates and phytoplankton were determined in

  19. High-gradient continuous-casting furnace

    NASA Technical Reports Server (NTRS)

    Scheuermann, C. M.; Flemings, M. C.; Neff, M. A.; Rickinson, B. A.; Young, K. P.

    1979-01-01

    High gradient allows rapid growth rates in directionally-solidified eutectic alloys. Furnace design permits cost reductions in directional solidification process through its increased solidification rates, which reduces melt/mold interaction. It produces structural engineering materials for any application requiring properties directionally-solidified eutectic materials.

  20. Gradient-index lenses as flux concentrators

    NASA Astrophysics Data System (ADS)

    Gordon, Jeffrey M.

    2001-11-01

    While gradient-index lenses are usually analyzed in terms of image fidelity, they are also capable of high flux concentration. In the first part of this presentation, the simplest class of gradient-index problems is revisited. An alterative way to obtain established solution of the refractive index profiles that produce perfect imaging is derived form the method of Fermat's strings and skewness conservation. The degree to which difference classes of such spherical lenses can realize the thermodynamic limit to flux concentration is explored. An answer is also sought to the intriguing question of the extent to which the spherical gradient-index lens of the fish eye is a modified Luneburg lens optimized subject to material constraints. The second half of this presentation addresses gradient-index rod lense. Both analytic methods and computer raytrace simulations are used for a comprehensive evaluation of their concentration and collection efficiency. They appear to be well suited as concentrators for the distal end of laser fiber-optic surgical units.

  1. 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

  2. Velocity gradients and microturbulence in Cepheids.

    NASA Technical Reports Server (NTRS)

    Karp, A. H.

    1973-01-01

    Variations of the microturbulent velocity with phase and height in the atmosphere have been reported in classical Cepheids. It is shown that these effects can be understood in terms of variations of the velocity gradient in the atmospheres of these stars.

  3. Face recognition using Histograms of Oriented Gradients

    Microsoft Academic Search

    O. Déniz; G. Bueno; J. Salido; F. De la Torre

    2011-01-01

    Face recognition has been a long standing problem in computer vision. Recently, Histograms of Oriented Gradients (HOGs) have proven to be an effective descriptor for object recognition in general and face recognition in particular. In this paper, we investigate a simple but powerful approach to make robust use of HOG features for face recognition. The three main contributions of this

  4. Hydromagnetic Gradient Waves in the Ionosphere

    Microsoft Academic Search

    I. Tolstoy

    1967-01-01

    Hydromagnetic gradient (HMG) waves are a magnetohydrodynamic analog of Rossby waves. It is shown here that conditions for their existence are approximately satisfied in the so-called dynamo layer of the atmosphere. As a result, it appears plausible to assume the existence of HMG waves as traveling perturbations of the $q current system. Corresponding micropulsations of the earth's magnetic field are

  5. Low-complexity demosaicing via multiscale gradients

    NASA Astrophysics Data System (ADS)

    Su, Chung-Yen; Chen, Yuh-Horng

    2014-01-01

    Demosaicing of the color filter array is one of the most important parts of the image processing pipeline for single sensor digital cameras. In recent years, one of the most successful algorithms is the multiscale gradients (MSG) algorithm. In this paper, several modifications were made to the MSG algorithm such that the computational complexity is significantly reduced while maintaining image quality.

  6. Social class gradients in health during adolescence

    PubMed Central

    Starfield, B; Riley, A; Witt, W; Robertson, J

    2002-01-01

    Study objective: To review existing data on social class gradients in adolescent health and to examine whether such gradients exist in new data concerning US adolescents. Design: Review of relevant publications and unpublished data; regression analyses using adolescent self reported health status data to determine whether there are gradients by social class, using three classes categorised by adolescent reported parental work status and education. Participants: Adolescents of ages 11–17. Main results: Findings from the literature indicate the presence of social class gradients in some but not all aspects of adolescent health. Results from new data showed social class gradients in several domains of health and in profiles of health. The likelihood of being satisfied with one's health, of being more resilient (better family involvement, better problem solving, more physical activity, better home safety), having higher school achievement, and of being in the best health profiles were significantly and progressively greater as social class rose. Moreover, the probability of being in the poorest health profile type group was progressively higher as social class declined. Conclusions: The review of existing data and the new findings support the existence of social class gradients in satisfaction with one's health, in resilience to health threats, in school achievement, and in being in the best health overall (as manifested by the health profiles composed of four major domains of health). The study had two especially notable findings: (1) the paucity of studies using the same or similar indicators, and (2) the consistent existence of social class gradients in characteristics related to subsequent health, particularly intake of nutritional foods and physical activity. The sparseness of existing data and the different aspects of health investigated in the relatively few studies underscore the need for (1) the development of conceptual models specifically focused on adolescent health and social class; (2) additional inquiry into the measurement of social class and adolescent perceptions of class; (3) inclusion of contextual variables in study design; and (4) longitudinal cohort studies to better understand the specific determinants of health during adolescence. PMID:11964432

  7. Gradient zone-boundary control in salt-gradient solar ponds

    DOEpatents

    Hull, J.R.

    1982-09-29

    A method and apparatus for suppressing zone boundary migration in a salt gradient solar pond includes extending perforated membranes across the pond at the boundaries, between the convective and non-convective zones, the perforations being small enough in size to prevent individual turbulence disturbances from penetrating the hole, but being large enough to allow easy molecular diffusion of salt thereby preventing the formation of convective zones in the gradient layer. The total area of the perforations is a sizeable fraction of the membrane area to allow sufficient salt diffusion while preventing turbulent entrainment into the gradient zone.

  8. Supply Chain Coordination in Hospitals

    Microsoft Academic Search

    Nazaré Rego; Jorge Pinho De Sousa

    2009-01-01

    This paper presents an innovative approach to support the definition of strategies for the design of alternative configurations\\u000a of hospital supply chains. This approach was developed around a hybrid Tabu Search \\/ Variable Neighbourhood Search metaheuristic,\\u000a that uses several neighbourhood structures. The flexibility of the procedure allows its application to supply chains with\\u000a different topologies and atypical cost characteristics. A

  9. Supply chain management and hypercompetition

    Microsoft Academic Search

    Herbert Kotzab; David B. Grant; Christoph Teller; Árni Halldórsson

    2009-01-01

    Firms nowadays face significant challenges in their operating environments, which have been characterised in two different\\u000a ways. From a strategic management perspective these environments are in a state of hypercompetition while from a logistics\\u000a or supply chain perspective these environments require market responsiveness predicated upon agile supply chains. However,\\u000a firms must also rely on many inter-organisational relationships to ensure efficient

  10. 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

  11. 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.

  12. Ground waves in atomic chains with bi-monomial double-well potential

    E-print Network

    Michael Herrmann

    2012-07-06

    Ground waves in atomic chains are traveling waves that corresponds to minimal non-trivial critical values of the underlying action functional. In this paper we study FPU-type chains with bi-monomial double-well potential and prove the existence of both periodic and solitary ground waves. To this end we minimize the action on the Nehari manifold and show that periodic ground waves converge to solitary ones. Finally, we compute ground waves numerically by a suitable discretization of a constrained gradient flow.

  13. 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.

  14. Interhemispheric gradient of hydroxyl in the troposphere

    NASA Astrophysics Data System (ADS)

    Patra, P. K.

    2013-12-01

    The hydroxyl radical (OH) in the atmosphere plays a significant role in air pollution chemistry by modulating the oxidizing capacity of the atmosphere and removal of important non-CO2 greenhouse gases. Although the global total OH abundance in the troposphere and its interannual variability have been estimated from observations, the interhemispheric (meridional) gradient remains poorly constraine. Because of the high reactivity of OH, direct observations are challenging and therefore limited in space and time. Emissions of CH3CCl3 have been a small fraction of the atmospheric burden since the late 1990s, and during the 2000s the north-south distribution of CH3CCl3 has been determined mainly by NH/SH OH gradients with little uncertainty contributed by remaining emission estimates. We use an atmospheric transport model that compares very well with HIPPO measured SF6 for interhemispheric transport throughout the troposphere to show that on an annual basis, the NH/SH OH ratio is close to one. This disagrees markedly from commonly used global atmospheric chemistry models that estimate OH ratios as high as 1.4. The NH/SH gradient in CH3CCl3 is decreasing over time. We show that for each year from 2004-2011, the model-predicted annual-mean NH/SH gradient in CH3CCl3 is a tight linear function of the NH/SH gradient in annual-mean OH. Optimizing the model to fit two AGAGE instruments, NOAA network and HIPPO campaign data in each year gives ratios of 0.92×0.08.

  15. 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

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

    SciTech Connect

    Connolly, J.P. (HydroQual, Inc., Mahwah, NJ (United States) Manhattan Coll., Riverdale, NY (United States))

    1991-04-01

    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. The model indicated that PCB concentrations in the flounder and, to a lesser extent, in the lobster are derived from the sediment. Dietary uptake exceeds uptake across the gill for all four homologues and becomes the dominant route at the higher chlorinated homologues. The assimilation efficiency of ingested PCB apparently declines from relatively high values for tri-chlorobiphenyl to relatively low values for hexachlorobiphenyl. Differences in observed lobster and flounder PCB concentrations appear to be due to differences in the importance of the benthic component of the food chains of these animals and differences in whole body lipid content.

  17. 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

  18. Gradient parameter and axial and field rays in the gradient-index crystalline lens model

    NASA Astrophysics Data System (ADS)

    Pérez, M. V.; Bao, C.; Flores-Arias, M. T.; Rama, M. A.; Gómez-Reino, C.

    2003-09-01

    Gradient-index models of the human lens have received wide attention in optometry and vision sciences for considering how changes in the refractive index profile with age and accommodation may affect refractive power. This paper uses the continuous asymmetric bi-elliptical model to determine gradient parameter and axial and field rays of the human lens in order to study the paraxial propagation of light through the crystalline lens of the eye.

  19. Solar energy storage by salinity gradient solar pond: Pilot plant construction and gradient control

    Microsoft Academic Search

    César Valderrama; Oriol Gibert; Jordina Arcal; Pau Solano; Aliakbar Akbarzadeh; Enric Larrotcha; José Luis Cortina

    2011-01-01

    An experimental solar pond pilot plant was constructed in Solvay-Martorell, facilities, Catalonia (NE part of the Iberian Peninsula) to capture and store solar energy. The body of the pond is a cylindrical reinforced concrete tank, 3m height, 8m diameter and total area of 50m2. Salinity and thermal gradient were properly established by using the salinity distribution methodology. The gradient in

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

    PubMed

    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 ((1)H-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

  1. 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

  2. Self-organization of intracellular gradients during mitosis

    PubMed Central

    2010-01-01

    Gradients are used in a number of biological systems to transmit spatial information over a range of distances. The best studied are morphogen gradients where information is transmitted over many cell lengths. Smaller mitotic gradients reflect the need to organize several distinct events along the length of the mitotic spindle. The intracellular gradients that characterize mitosis are emerging as important regulatory paradigms. Intracellular gradients utilize intrinsic auto-regulatory feedback loops and diffusion to establish stable regions of activity within the mitotic cytosol. We review three recently described intracellular mitotic gradients. The Ran GTP gradient with its elaborate cascade of nuclear transport receptors and cargoes is the best characterized, yet the dynamics underlying the robust gradient of Ran-GTP have received little attention. Gradients of phosphorylation have been observed on Aurora B kinase substrates both before and after anaphase onset. In both instances the phosphorylation gradient appears to result from a soluble gradient of Aurora B kinase activity. Regulatory properties that support gradient formation are highlighted. Intracellular activity gradients that regulate localized mitotic events bare several hallmarks of self-organizing biologic systems that designate spatial information during pattern formation. Intracellular pattern formation represents a new paradigm in mitotic regulation. PMID:20181052

  3. Supply Chain Analysis Center for Transportation Analysis

    E-print Network

    Supply Chain Analysis Center for Transportation Analysis 2360 Cherahala Boulevard Knoxville, TN Contract number DE-AC05-00OR22725 Research Areas Freight Flows Passenger Flows Supply Chain Efficiency experience in supply chain analysis and automated support for supply chain systems. ORNL's Capabilities

  4. 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

  5. Simulation for supply Chain management: An Overview

    E-print Network

    Paris-Sud XI, Université de

    Chapter 1 Simulation for supply Chain management: An Overview C. THIERRY, A. THOMAS, G. BEL 1.1. Supply chain management In this book we are concerned with the simulation for Supply Chain Management, strategic implications of the tactical activities involved in managing the various flows in a supply chain

  6. Web Mashups in the Supply Chain

    E-print Network

    Zeets, Matthew Joseph

    2010-10-22

    between parties in a supply chain. This paper focuses on analyzing the potential use of web mashups by enterprises in the supply chain industry. Web mashups, the supply chain, and the security implications of using web mashups in the supply chain...

  7. 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

  8. 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.

  9. 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.

  10. Colloidal attraction induced by a temperature gradient

    E-print Network

    R. Di Leonardo; F. Ianni; G. Ruocco

    2008-11-19

    Colloidal crystals are of extreme importance for applied research, such as photonic crystals technology, and for fundamental studies in statistical mechanics. Long range attractive interactions, such as capillary forces, can drive the spontaneous assembly of such mesoscopic ordered structures. However long range attractive forces are very rare in the colloidal realm. Here we report a novel strong and long ranged attraction induced by a thermal gradient in the presence of a wall. Switching on and off the thermal gradient we can rapidly and reversibly form stable hexagonal 2D crystals. We show that the observed attraction is hydrodynamic in nature and arises from thermal induced slip flow on particle surfaces. We used optical tweezers to directly measure the force law and compare it to an analytic prediction based on Stokes flow driven by Marangoni forces.

  11. Temperature gradient driven lasing and stimulated cooling

    E-print Network

    K. Sandner; H. Ritsch

    2012-05-31

    A laser can be understood as thermodynamic engine converting heat to a coherent single mode field close to Carnot efficiency. From this perspective spectral shaping of the excitation light generates a higher effective temperature on the pump than on the gain transition. Here, using a toy model of a quantum well structure with two suitably designed tunnel-coupled wells kept at different temperature, we study a laser operated on an actual spatial temperature gradient between pump and gain region. We predict gain and narrow band laser emission for a sufficient temperature gradient and resonator quality. Lasing appears concurrent with amplified heat flow and points to a new form of stimulated solid state cooling. Such a mechanism could raise the operating temperature limit of quantum cascade lasers by substituting phonon emission driven injection, which generates intrinsic heat, by an extended model with phonon absorption steps.

  12. Opinion Formation Models on a Gradient

    PubMed Central

    Gastner, Michael T.; Markou, Nikolitsa; Pruessner, Gunnar; Draief, Moez

    2014-01-01

    Statistical physicists have become interested in models of collective social behavior such as opinion formation, where individuals change their inherently preferred opinion if their friends disagree. Real preferences often depend on regional cultural differences, which we model here as a spatial gradient g in the initial opinion. The gradient does not only add reality to the model. It can also reveal that opinion clusters in two dimensions are typically in the standard (i.e., independent) percolation universality class, thus settling a recent controversy about a non-consensus model. However, using analytical and numerical tools, we also present a model where the width of the transition between opinions scales , not as in independent percolation, and the cluster size distribution is consistent with first-order percolation. PMID:25474528

  13. 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.

  14. A mesh gradient technique for numerical optimization

    NASA Technical Reports Server (NTRS)

    Willis, E. A., Jr.

    1973-01-01

    A class of successive-improvement optimization methods in which directions of descent are defined in the state space along each trial trajectory are considered. The given problem is first decomposed into two discrete levels by imposing mesh points. Level 1 consists of running optimal subarcs between each successive pair of mesh points. For normal systems, these optimal two-point boundary value problems can be solved by following a routine prescription if the mesh spacing is sufficiently close. A spacing criterion is given. Under appropriate conditions, the criterion value depends only on the coordinates of the mesh points, and its gradient with respect to those coordinates may be defined by interpreting the adjoint variables as partial derivatives of the criterion value function. In level 2, the gradient data is used to generate improvement steps or search directions in the state space which satisfy the boundary values and constraints of the given problem.

  15. 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.

  16. Electron profile stiffness and critical gradient studies

    SciTech Connect

    DeBoo, J. C.; Petty, C. C.; Burrell, K. H.; Smith, S. P. [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States); White, A. E. [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Doyle, E. J.; Hillesheim, J. C.; Rhodes, T. L.; Schmitz, L.; Wang, G.; Zeng, L. [University of California-Los Angeles, Los Angeles, California 90095-7099 (United States); Holland, C. [University of California-San Diego, La Jolla, California 92093-0417 (United States); McKee, G. R. [University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

    2012-08-15

    Electron profile stiffness was studied in DIII-D L-mode discharges by systematically varying the heat flux in a narrow region with electron cyclotron heating and measuring the local change produced in {nabla}T{sub e}. Electron stiffness was found to slowly increase with toroidal rotation velocity. A critical inverse temperature gradient scale length 1/L{sub C} {approx} 3 m{sup -1} was identified at {rho}=0.6 and found to be independent of rotation. Both the heat pulse diffusivity and the power balance diffusivity, the latter determined by integrating the measured dependence of the heat pulse diffusivity on -{nabla}T{sub e}, were fit reasonably well by a model containing a critical inverse temperature gradient scale length and varying linearly with 1/L{sub T} above the threshold.

  17. Automated apparatus for producing gradient gels

    DOEpatents

    Anderson, N.L.

    1983-11-10

    Apparatus for producing a gradient gel which serves as a standard medium for a two-dimensional analysis of proteins, the gel having a density gradient along its height formed by a variation in gel composition, with the apparatus including first and second pumping means each including a plurality of pumps on a common shaft and driven by a stepping motor capable of providing small incremental changes in pump outputs for the gel ingredients, the motors being controlled, by digital signals from a digital computer, a hollow form or cassette for receiving the gel composition, means for transferring the gel composition including a filler tube extending near the bottom of the cassette, adjustable horizontal and vertical arms for automatically removing and relocating the filler tube in the next cassette, and a digital computer programmed to automatically control the stepping motors, arm movements, and associated sensing operations involving the filling operation.

  18. Ecological gradients within a Pennsylvanian mire forest

    USGS Publications Warehouse

    DiMichele, W.A.; Falcon-Lang, H. J.; Nelson, W.J.; Elrick, S.D.; Ames, P.R.

    2007-01-01

    Pennsylvanian coals represent remains of the earliest peat-forming rain forests, but there is no current consensus on forest ecology. Localized studies of fossil forests suggest intermixture of taxa (heterogeneity), while, in contrast, coal ball and palynological analyses imply the existence of pronounced ecological gradients. Here, we report the discovery of a spectacular fossil forest preserved over ???1000 ha on top of the Pennsylvanian (Desmoinesian) Herrin (No. 6) Coal of Illinois, United States. The forest was abruptly drowned when fault movement dropped a segment of coastal mire below sea level. In the largest study of its kind to date, forest composition is statistically analyzed within a well-constrained paleogeographic context. Findings resolve apparent conflicts in models of Pennsylvanian mire ecology by confirming the existence of forest heterogeneity at the local scale, while additionally demonstrating the emergence of ecological gradients at landscape scale. ?? 2007 The Geological Society of America.

  19. Gradient LPWG structures based on Pyrex glass

    NASA Astrophysics Data System (ADS)

    Kotyczka, Tomasz; Rogozi?ski, Roman

    2014-05-01

    This paper presents the calculations showing the possibility of the implementation of the Long Period Waveguide Grating (LPWG) structures in glass with gradient refractive profile. As the substrate material the Pyrex glass has been chosen, which is characterized by good optical properties. Calculations were performed for the actual material properties (refraction and chromatic dispersion) of this glass. The real technological processes of the Ag+?Na+ ion exchange in Pyrex glass used for the production of the gradient areas were also included. The obtained results showed the potential to generate such structures in Pyrex glass for applications in the visible spectrum. Simulations of ion exchange processes in this glass have been carried out taking into account experimentally determined temperature coefficients of the diffusion of exchanged ions.

  20. Laws of Energy Gradient for Instabilities

    E-print Network

    Hua-Shu Dou

    2005-06-25

    Transition to turbulence is due to the instability of a laminar flow subject to a disturbance. This complicated problem can be explained using a new proposed energy gradient theory in our previous study. This theory is extended to the instability of fluid material systems in this study. The instability of fluid material systems may lead to the evolution of natural environments and the occurrence of catastrophic events in the world. To better describe these phenomena and to understand the physical mechanism behind them are very important. In order to more generally describe the instability of fluid material systems, laws of energy gradient are summarized for static and motion systems, respectively. These laws could be applicable to various flow problems and material systems. Examples are shown that many events in the world could be explained using these laws.

  1. Strain gradients and size effects in composites

    SciTech Connect

    Ning, J.; Aifantis, E.C. [Michigan Technological Univ., Houghton, MI (United States)

    1995-12-31

    To interpret deformation inhomogeneity and the related size effect in the plastic deformation of composites, we employ and properly extend the gradient approach as developed earlier by the second author and his co-workers to model deformation patterning in metallic and granular materials. A self-consistent argument is utilized, a rule of mixtures is used and a micromechanics model is developed to illustrate the effects of spacing and size of fibers on the overall plastic properties of the composites.

  2. Controlled Temperature Gradient Improves Freezing Alloy

    NASA Technical Reports Server (NTRS)

    Schmidt, Deborah; Alter, Wendy S.; Hamilton, William D.

    1991-01-01

    Controlled gradient of temperature in advancing zone of solidification increases fatigue life of directionally solidified nickel-base superalloy. Improved solidification process eliminates, reduces, or controls microstructure of deleterious brittle phases, including carbides and gamma/gamma prime eutectic. Also reduces microsegregation and makes discrete carbides (if present) become fine and blocky. Expected to improve properties of other alloys, of both directionally-solidified polycrystalline and single-crystal forms.

  3. Texturing of REBCO using temperature gradient

    Microsoft Academic Search

    K. Salama; S. P. Athur; U. Balachandran

    2001-01-01

    Isothermal melt texturing is currently a well-established technique for manufacturing superconducting materials with high trapped magnetic field and levitation forces. For conductor applications, however, a temperature gradient needs to be employed in order to align the oriented domains with the a–b planes where the current will be flowing over long lengths. Melt-textured Y-123 bars of length 100 mm with Jc

  4. The lattice gradient flow at tree level

    E-print Network

    Zoltan Fodor; Kieran Holland; Julius Kuti; Santanu Mondal; Daniel Nogradi; Chik Him Wong

    2014-10-31

    The cut-off effects of the lattice gradient flow -- often called Wilson flow -- are calculated on a periodic 4-torus at leading order in the gauge coupling. A large class of discretizations is considered which includes all frequently used cases in practice. It is shown how the results lead to a smoother continuum extrapolation for the beta-function of SU(3) gauge theory with N_f = 4 flavors of fermions.

  5. 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.

  6. 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.

  7. Biogeochemical gradients in the lower Columbia River

    Microsoft Academic Search

    F. G. Prahl; L. F. Small; B. A. Sullivan; J. Cordell; C. A. Simenstad; B. C. Crump; J. A. Baross

    1997-01-01

    Water, suspended particulate materials (SPM), and biota were sampled between June 14 and 22, 1992 at forty-five mid-channel sites along a downstream gradient in the lower 350 km of the Columbia River drainage, at four mid-channel sites in the lower 27 km of the Willamette drainage and at the mouths of nine smaller tributaries to the Columbia. Water samples were

  8. Hepatic Venous Pressure Gradient: Worth Another Look?

    Microsoft Academic Search

    Sameer Parikh

    2009-01-01

    Portal hypertension is one of the most important complications of chronic liver disease and accounts for significant morbidity\\u000a and mortality. Measurement of the hepatic venous pressure gradient (HVPG) is a simple, invasive, and reproducible method of\\u000a assessing portal venous pressure. Measurement of HVPG provides the clinician an estimate of the degree of intrahepatic portal\\u000a flow resistance, guides therapy for variceal

  9. 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.

  10. Exploration of very high gradient cavities

    SciTech Connect

    Grigory Eremeev

    2011-07-01

    Several of the 9-cell ILC cavities processed at Jlab within ongoing ILC R&D program have shown interesting behavior at high fields, such as mode mixing and sudden field emission turn-on during quench. Equipped with thermometry and oscillating superleak transducer (OST) system for quench detection, we couple our RF measurements with local dissipation measurements. In this contribution we report on our findings with high gradient SRF cavities.

  11. Observation of a Gradient Catastrophe Generating Solitons

    SciTech Connect

    Conti, Claudio [Research Center SOFT INFM-CNR, Universita di Roma 'La Sapienza', P. A. Moro 2, 00185 Roma (Italy); Fratalocchi, Andrea; Peccianti, Marco [Research Center SOFT INFM-CNR, Universita di Roma 'La Sapienza', P. A. Moro 2, 00185 Roma (Italy); Centro Studi e Ricerche 'Enrico Fermi', Via Panisperna 89/A, 00184 Roma (Italy); Ruocco, Giancarlo [Research Center SOFT INFM-CNR, Universita di Roma 'La Sapienza', P. A. Moro 2, 00185 Roma (Italy); Dipartimento di Fisica, Universita di Roma 'La Sapienza', P. A. Moro 2, 00185 Roma (Italy); Trillo, Stefano [Research Center SOFT INFM-CNR, Universita di Roma 'La Sapienza', P. A. Moro 2, 00185 Roma (Italy); Dipartimento di Ingegneria, Universita di Ferrara, Via Saragat 1, 44100 Ferrara (Italy)

    2009-02-27

    We investigate the propagation of a dark beam in a defocusing medium in the strong nonlinear regime. We observe for the first time a shock fan filled with noninteracting one-dimensional gray solitons that emanates from a gradient catastrophe developing around a null of the optical intensity. This scenario turns out to be very robust, persisting also when the material nonlocal response averages the nonlinearity over dimensions much larger than the emerging soliton filaments.

  12. A gentle Hessian for efficient gradient descent

    Microsoft Academic Search

    Ronan Collobert; Samy Bengio

    2004-01-01

    Several second-order optimization methods for gradient descent algorithms have been proposed over the years, but they usually need to compute the inverse of the Hessian of the cost function (or an approximation of this inverse) during training. In most cases, this leads to an O(n2) cost in time and space per iteration, where n is the number of parameters, which

  13. Aberrations of Gradient-Index Lenses.

    NASA Astrophysics Data System (ADS)

    Matthews, A. L.

    Available from UMI in association with The British Library. In this thesis, the primary aberrations of lenses with a radial focussing gradient-of-index are analysed. Such a lens has a refractive index profile which decreases continuously and radially outward from the optical axis, so that the surfaces of constant refractive index are circular cylinders which are coaxial with the optical axis. Current applications of these lenses include photocopiers, medical endoscopes, telecommunications systems and compact disc systems. Closed formulae for the primary wavefront aberrations for a gradient-index lens with curved or plane entry and exit faces are obtained from the differential equations of such a lens to assess the primary transverse ray aberrations that it introduces. Identical expressions are then obtained by using the difference in optical path length produced between two rays by the lens. This duplication of the derivations of the primary wavefront aberrations acts as a confirmation of the validity of the expressions. One advantage of these equations is that the contributions due to the primary spherical aberration, coma, astigmatism, field curvature and distortion can be assessed individually. A Fortran 77 program has been written to calculate each of these individual contributions, the total primary wavefront aberrations and the primary transverse ray aberrations. Further confirmation of the validity of the expressions is obtained by using this program to show that the coma and distortion were both zero for fully symmetric systems working at unit magnification. The program is then used to assess the primary wavefront aberrations for a gradient-index lens which is currently of interest to the telecommunications industry. These results are compared with values obtained using a finite ray-tracing program for the total wavefront aberrations. This shows that the primary wavefront aberrations are the completely dominant contribution to the total wavefront aberrations of this gradient-index lens.

  14. Temperature gradient and electric field driven electrostatic instabilities

    NASA Technical Reports Server (NTRS)

    Morrison, P. J.; Ionson, J. A.

    1982-01-01

    The stability of electrostatic waves to thermodynamic and electric potential gradients was investigated. It is shown that thermodynamic gradients drive instabilities even when the internal electric field vanishes. Skewing of the distribution function is not included in the dielectric.

  15. Spin Gradient Thermometry for Ultracold Atoms in Optical Lattices

    E-print Network

    Weld, David M.

    We demonstrate spin gradient thermometry, a new general method of measuring the temperature of ultracold atoms in optical lattices. We realize a mixture of spins separated by a magnetic field gradient. Measurement of the ...

  16. 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.

  17. The Boussinesq Problem in Dipolar Gradient Elasticity

    E-print Network

    H. G. Georgiadis; P. A. Gourgiotis; D. S. Anagnostou

    2014-03-31

    The three-dimensional axisymmetric Boussinesq problem of an isotropic half-space subjected to a concentrated normal quasi-static load is studied within the framework of linear dipolar gradient elasticity. Our main concern is to determine possible deviations from the predictions of classical linear elastostatics when a more refined theory is employed to attack the problem. Of special importance is the behavior of the new solution near to the point of application of the load where pathological singularities exist in the classical solution. The use of the theory of gradient elasticity is intended here to model the response of materials with microstructure in a manner that the classical theory cannot afford. A linear version of this theory results by considering a linear isotropic expression for the strain-energy density that depends on strain-gradient terms, in addition to the standard strain terms appearing in classical elasticity. Through this formulation, a microstructural material constant is introduced, in addition to the standard Lam\\'e constants. The solution method is based on integral transforms and is exact. The present results show significant departure from the predictions of classical elasticity. Indeed, continuous and bounded displacements are predicted at the points of application of the concentrated load. Such a behavior of the displacement field is, of course, more natural than the singular behavior exhibited in the classical solution.

  18. Gradient field microscopy of unstained specimens

    PubMed Central

    Kim, Taewoo; Sridharan, Shamira; Popescu, Gabriel

    2012-01-01

    We present a phase derivative microscopy technique referred to as gradient field microscopy (GFM), which provides the first-order derivatives of the phase associated with an optical field passing through a transparent specimen. GFM utilizes spatial light modulation at the Fourier plane of a bright field microscope to optically obtain the derivatives of the phase and increase the contrast of the final image. The controllable spatial modulation pattern allows us to obtain both one component of the field gradient (derivative along one direction) and the gradient intensity, which offers some advantages over the regular differential interference contrast (DIC) microscopy. Most importantly, unlike DIC, GFM does not use polarizing optics and, thus, it is applicable to birefringent samples. We demonstrate these features of GFM with studies of static and dynamic biological cells (HeLa cells and red blood cells). We show that GFM is capable of qualitatively providing information about cell membrane fluctuations. Specifically, we captured the disappearance of the bending mode of fluctuations in osmotically swollen red blood cells. PMID:22418558

  19. 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.

  20. Strong gradients for spatially resolved diffusion measurements.

    PubMed

    Snaar, J E; Robyr, P; Bowtell, R

    1998-01-01

    A new multilayer approach to gradient coil design, which allows the production of very strong gradient coils with reasonable resistance and consequent power dissipation, has been developed. Using this approach we have designed and built a strong z-gradient coil that will accommodate vertically mounted samples contained in 5-mm nuclear magnetic resonance tubes. The coil has an efficiency of 1.73 Tm-1A-1, an inductance of 49 microH, and a resistance of 1.8 omega, with a homogeneous volume consisting of a central cylinder of 4.5-mm length and diameter. This coil has been used to monitor the diffusion of water in Nylon 6.6 at room temperature, during desorption. This system is difficult to monitor via nuclear magnetic resonance (NMR), because the diffusion coefficients are typically less than 10(-13) m2s-1, while the T2 relaxation time is less than 1 ms even when the sample is fully saturated. The resulting measurements show a strong concentration dependence of the T2 relaxation time and self-diffusion coefficient of the absorbed water. The measured concentration profiles are consistent with a Fickian diffusion process with a concentration-dependent diffusion coefficient. The measured self-diffusion values are in reasonable agreement with those inferred from the variation of the concentration profiles as a function of time, using the one-dimensional Fickian diffusion equation. PMID:9803915

  1. Resolution requirements for velocity gradients in turbulence

    NASA Technical Reports Server (NTRS)

    Jimenez, Javier

    1994-01-01

    Since high resolution numerical simulations of turbulent flows, or experiments at high Reynolds numbers, represent a substantial investment in resources, the estimation of the minimum resolution required for the study of a given property has been the subject of continued interest. Different properties require, in general, different resolutions, and the present paper is dedicated to the requirements for the measurement of the probability distribution functions of the velocity gradients and, in particular, of their low order moments. The deviation of these quantities from the values corresponding to a Gaussian distribution was one of the first indications of the presence of Reynolds number-dependent intermittency and has been the object of recent interest as numerical simulations have become able to explore the distribution of gradients in the low Reynolds number range, while new experiments have extended the range to increasingly high Reynolds numbers. We will use progressive filtering of the results of numerical simulations of isotropic turbulence as a model for the effect of a sensor of finite size. The numerical issues will be addressed first to ensure that the simulations are fully resolved from the point of view of the velocity gradients. This will also give us an estimate for the numerical resolution required for the different quantities.

  2. 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.

  3. Energy Gradient Theory of Hydrodynamic Instability

    E-print Network

    Hua-Shu Dou

    2005-01-29

    A new universal theory for flow instability and turbulent transition is proposed in this study. Flow instability and turbulence transition have been challenging subjects for fluid dynamics for a century. The critical condition of turbulent transition from theory and experiments differs largely from each other for Poiseuille flows. In this paper, a new mechanism of flow instability and turbulence transition is presented for parallel shear flows and the energy gradient theory of hydrodynamic instability is proposed. It is stated that the total energy gradient in the transverse direction and that in the streamwise direction of the main flow dominate the disturbance amplification or decay. A new dimensionless parameter K for characterizing flow instability is proposed for wall bounded shear flows, which is expressed as the ratio of the energy gradients in the two directions. It is thought that flow instability should first occur at the position of Kmax which may be the most dangerous position. This speculation is confirmed by Nishioka et al's experimental data. Comparison with experimental data for plane Poiseuille flow and pipe Poiseuille flow indicates that the proposed idea is really valid. It is found that the turbulence transition takes place at a critical value of Kmax of about 385 for both plane Poiseuille flow and pipe Poiseuille flow, below which no turbulence will occur regardless the disturbance. More studies show that the theory is also valid for plane Couette flows and Taylor-Couette flows between concentric rotating cylinders.

  4. BROOKHAVEN NATIONAL LABORATORY Alternating Gradient Synchrotron Department

    E-print Network

    McDonald, Kirk

    Crowbar. The RF crowbar triggers a spark plug in the cavity, dumping the cavity stored energy into the arc. In addition RF cooling water, cavity vacuum and tunnel security systems remain operational. This will greatly facilitate the use of the Hilac cavity as our test load. It appears that four phased locked amplifier chains

  5. 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.

  6. Ligand chain length conveys thermochromism.

    PubMed

    Ganguly, Mainak; Panigrahi, Sudipa; Chandrakumar, K R S; Sasmal, Anup Kumar; Pal, Anjali; Pal, Tarasankar

    2014-08-14

    Thermochromic properties of a series of non-ionic copper compounds have been reported. Herein, we demonstrate that Cu(II) ion with straight-chain primary amine (A) and alpha-linolenic (fatty acid, AL) co-jointly exhibit thermochromic properties. In the current case, we determined that thermochromism becomes ligand chain length-dependent and at least one of the ligands (A or AL) must be long chain. Thermochromism is attributed to a balanced competition between the fatty acids and amines for the copper(II) centre. The structure-property relationship of the non-ionic copper compounds Cu(AL)2(A)2 has been substantiated by various physical measurements along with detailed theoretical studies based on time-dependent density functional theory. It is presumed from our results that the compound would be a useful material for temperature-sensor applications. PMID:24943491

  7. Scaling of the spanning threshold in gradient percolation

    NASA Astrophysics Data System (ADS)

    Paterson, Lincoln

    2015-02-01

    A simple and fast way to apply correlations in percolation simulations is to apply a uniform gradient to the occupancy probabilities. For small networks, exact results are presented here for the spanning thresholds in site percolation with a gradient for networks up to 4 ×4 in two dimensions and 2 ×2 ×2 in three dimensions. Numerical results are provided for larger networks that extrapolate to a linear modification of the threshold proportional to the gradient for moderate values of the gradient.

  8. 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

  9. MBA Supply Chain Case Competition Center for Supply Chain Management

    E-print Network

    Lin, Xiaodong

    , the student teams will identify the key issues in the company's supply chain and operations, point out how bring its presentation to the competition on a USB memory stick to be loaded onto a Rutgers. In particular, Identification of key business issues Thoroughness of analysis Feasibility of solutions Poise

  10. Differential evolution Markov chain with snooker updater and fewer chains

    SciTech Connect

    Vrugt, Jasper A [Los Alamos National Laboratory; Ter Braak, Cajo J F [NON LANL

    2008-01-01

    Differential Evolution Markov Chain (DE-MC) is an adaptive MCMC algorithm, in which multiple chains are run in parallel. Standard DE-MC requires at least N=2d chains to be run in parallel, where d is the dimensionality of the posterior. This paper extends DE-MC with a snooker updater and shows by simulation and real examples that DE-MC can work for d up to 50--100 with fewer parallel chains (e.g. N=3) by exploiting information from their past by generating jumps from differences of pairs of past states. This approach extends the practical applicability of DE-MC and is shown to be about 5--26 times more efficient than the optimal Normal random walk Metropolis sampler for the 97.5% point of a variable from a 25--50 dimensional Student T{sub 3} distribution. In a nonlinear mixed effects model example the approach outperformed a block-updater geared to the specific features of the model.

  11. Polymers are Chains (K-2)

    NSDL National Science Digital Library

    2012-06-26

    In this activity, learners make a paper model of a polymer, then make Silly Putty, an actual polymer. For the model, learners make chains of paper dolls and color them in different ways to represent different types of monomers. The doll stencil is not included, but can be improvised. Shaking the chains in a bag simulates making the polymer. For the Silly Putty, learners mix saturated borax with Elmer's glue. There are two versions of this activity, one written for grades K-2, one for 3-6, with the older version including some additional materials testing, and some variation in the Silly Putty mixture.

  12. Bridging organization theory and supply chain management: The case of best value supply chains

    Microsoft Academic Search

    David J. Ketchen; G. Tomas M. Hult

    2007-01-01

    Rivalry is increasingly being contested at the supply chain level of analysis. Rather than competing “firm versus firm,” today's organizations are battling “supply chain versus supply chain.” Within this context, best value supply chains are emerging as a means to create competitive advantages and superior performance. While traditional supply chains often focus primarily on one key outcome such as speed

  13. Sec. 2.4 Chain configurations and elasticity 42 2.4 Chain configurations and elasticity

    E-print Network

    Boal, David

    : the most likely value of ree 2 for a freely jointed chain is not far from its mean value of Nb2Sec. 2.4 ­ Chain configurations and elasticity 42 2.4 Chain configurations and elasticity Averaged the behavior of chains or filaments. In this section, we develop a more complete picture of chain geometry

  14. The study of supply chain competition model and cooperative innovation between supply chains

    Microsoft Academic Search

    Teng Chun-xian; Hu Yin-xia; Zhou Yan-shan

    2010-01-01

    Through providing the new definitions of supply chain economy, market pertinent chain, operation link and interface link, we establish the supply chain economy model with electronic commerce based on variational inequality theory and spatial price theory. Furthermore, we have analyzed the characteristics and feasible conditions of cooperative innovation between supply chains, and added the cooperative innovation into the supply chain

  15. Reese 4/2004 GRADIENT GELS FOR SDS-PAGE

    E-print Network

    Doering, Tamara

    Reese 4/2004 GRADIENT GELS FOR SDS-PAGE OVERVIEW This protocol is for pouring 4-10% gradient SDS-PAGE gels with the Hoefer Multi-Gel system. If a different range of gel concentration is needed the stock well, rinse with acetone and dry. 2. Set up gradient system - Assemble multi-caster with plates (do

  16. Regulation of the MEX-5 Gradient by a Spatially Segregated

    E-print Network

    Seydoux, Geraldine

    concentration gradients encode spatial in- formation across cells and tissues and often depend on spatially and dephosphorylation reactions are sufficient to generate stable protein concentration gradients in the cytoplasm and uniform protein degradation across the egg generate a concentration gradient over the course of $2 hr

  17. Template-Assisted Formation of Gradient Concentric Gold Rings

    E-print Network

    Lin, Zhiqun

    Template-Assisted Formation of Gradient Concentric Gold Rings Suck Won Hong, Jun Xu, and Zhiqun Lin, 2006; Revised Manuscript Received November 1, 2006 ABSTRACT Gradient concentric rings of polymers-organized gradient concentric ring patterns have been produced by constraining a drop of polymer solution

  18. SIMULATION OF ION-TEMPERATURE-GRADIENT TURBULENCE IN TOKAMAKS1

    E-print Network

    Hammett, Greg

    SIMULATION OF ION-TEMPERATURE-GRADIENT TURBULENCE IN TOKAMAKS1 A.M. DIMITS, B.I. COHEN, N. MATTOR gyrokinetic simulations of toroidal ion temperature gradient ITG turbulence and transport. The ion thermal uxes are found to have an o set linear dependence on the temperature gradient and are signi cantly

  19. Role of nonlinear toroidal coupling in electron temperature gradient turbulencea...

    E-print Network

    Zonca, Fulvio

    Role of nonlinear toroidal coupling in electron temperature gradient turbulencea... Z. Linb and L gyrokinetic theory find that electron temperature gradient ETG instability saturates via nonlinear toroidal: 10.1063/1.1894766 I. INTRODUCTION Electron temperature gradients in magnetically confined plasmas

  20. Electric Charge Transfer Associated with Temperature Gradients in Ice

    Microsoft Academic Search

    J. Latham; B. J. Mason

    1961-01-01

    The development of electric potentials in ice crystals under the influence of temperature gradients is investigated both theoretically and experimentally. The maintenance of a steady temperature gradient across a piece of ice is accompanied by concentration gradients of H^+ and OH^- ions; because of the much greater mobility of H^+ ions, these diffuse more rapidly into the colder part of

  1. Compressed ion temperature gradient turbulence in diverted tokamak edgea...

    E-print Network

    Lin, Zhihong

    Compressed ion temperature gradient turbulence in diverted tokamak edgea... C. S. Chang,1,2,b S. Ku-f gyrokinetic particle simulation that there is ion temperature gradient ITG turbulence across an entire L-mode-like edge density pedestal in a diverted tokamak plasma in which the ion temperature gradient is mild

  2. Entropy and temperature gradients thermomechanics: dissipation, heat conduction

    E-print Network

    Boyer, Edmond

    Entropy and temperature gradients thermomechanics: dissipation, heat conduction inequality and heat Rendus Mécanique 340, 6 (2012) 434-443" DOI : 10.1016/j.crme.2012.04.001 #12;temperature and its gradient and the first n spatial gradients of the temperature, they showed that the internal energy and the en- tropy

  3. Minimal Skew Clock Embedding Considering Time Variant Temperature Gradient

    E-print Network

    He, Lei

    - ing points can be shifted with presence of the temperature gradient. As a result, it requires a clockMinimal Skew Clock Embedding Considering Time Variant Temperature Gradient Hao Yu, Yu Hu, Chunchen-aware clock embedding assumes a time-invariant temperature gradient. However, it is not solved how to find

  4. Nonmonotone Spectral Projected Gradient Methods on Convex Sets

    Microsoft Academic Search

    Ernesto G. Birgin; José Mario Martínez; Marcos Raydan

    2000-01-01

    Nonmonotone projected gradient techniques are considered for the minimization of dieren tiable functions on closed convex sets. The classical projected gradient schemes are extended to include a nonmonotone steplength strategy that is based on the Grippo-Lampariello-Lucidi nonmonotone line search. In particular, the nonmono- tone strategy is combined with the spectral gradient choice of steplength to accelerate the convergence process. In

  5. Creation of a Sog Morphogen Gradient in the Drosophila Embryo

    Microsoft Academic Search

    Shaila Srinivasan; Kay E. Rashka; Ethan Bier

    2002-01-01

    A variety of genetic evidence suggests that a gradient of Decapentaplegic (Dpp) activity determines distinct cell fates in the dorsal region of the Drosophila embryo, and that this gradient may be generated indirectly by an inverse gradient of the BMP antagonist Short gastrulation (Sog). It has been proposed that Sog diffuses dorsally from the lateral neuroectoderm where it is produced,

  6. A Strain-Gradient Virtual-Internal-Bond Model

    E-print Network

    Vainchtein, Anna

    into the VIB model is to employ a strain- gradient nonlinear elasticity theory. Phenomenological models of the strain-gradient theory in the one-dimensional case given by Triantafyllidis and Bardenhagen (1993 part of the paper, the derivation of the strain-gradient theory in higher dimensions given

  7. GRADIENT THEORY FOR PLASTICITY VIA HOMOGENIZATION OF DISCRETE DISLOCATIONS

    E-print Network

    , relaxation, plasticity, strain gradient theories, stress concentration, dislocations. 2000 Mathematics effects due to dislocations, such as the so called strain gradient theories. The aim of this paper is to provide a rigorous derivation of a strain gradient theory for plasticity as a mesoscopic limit of systems

  8. Gradient limitations in room temperature and superconducting acceleration structures

    Microsoft Academic Search

    N. A. Solyak

    2008-01-01

    Accelerating gradient is a key parameter of the accelerating structure in large linac facilities, like future Linear Collider. In room temperature accelerating structures the gradient is limited mostly by breakdown phenomena, caused by high surface electric fields or pulse surface heating. High power processing is a necessary procedure to clean surface and improve the gradient. In the best tested X-band

  9. Gradient Limitations in Room Temperature and Superconducting Acceleration Structures

    Microsoft Academic Search

    N. A. Solyak

    2009-01-01

    Accelerating gradient is a key parameter of the accelerating structure in large linac facilities, like future Linear Collider. In room temperature accelerating structures the gradient is limited mostly by breakdown phenomena, caused by high surface electric fields or pulse surface heating. High power processing is a necessary procedure to clean surface and improve the gradient. In the best tested X-band

  10. 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

  11. SCREENING PLATELET – SURFACE INTERACTIONS USING NEGATIVE SURFACE CHARGE GRADIENTS

    PubMed Central

    Corum, Lindsey E.; Hlady, Vladimir

    2012-01-01

    Negative surface charge density gradients were prepared on fused silica slides using selective oxidation of a 3-mercaptopropyltrimethoxysilane (MTS) monolayer converting surface thiol groups (-SH) into negatively charged sulfonate (-SO3-) groups. The sulfonate-to-thiol gradient samples were characterized by water contact angle and electron spectroscopy for chemical analysis (ESCA). Gradients were pre-adsorbed with proteins from three different solutions: platelet free plasma (PFP), fibrinogen, or albumin in phosphate buffered saline (PBS). Washed platelets were perfused over gradient samples in a parallel plate flow chamber and platelet adhesion was measured across the gradients using differential interference contrast (DIC) microscopy. Gradients pre-adsorbed with PFP showed adhesion contrast inversely related to the negative surface charge density. The magnitude of the adhesion contrast along the gradient was also dependent on PFP concentration. Gradients pre-adsorbed with fibrinogen showed an adhesion maximum in the center of the gradient region. Albumin coating of the gradients resulted in low overall platelet adhesion with increased adhesion in regions of high negative charge density. The effect of gradient orientation with respect to the flow was also investigated. Gradients pre-adsorbed with 10% PFP showed different adhesion contrast when the platelets were perfused in opposite directions. This suggests that platelet adhesion is, in addition to responding to the local surface properties, also dependent on the upstream conditions. PMID:20149436

  12. Accelerated Gradient Methods for Stochastic Optimization and Online Learning

    E-print Network

    Kwok, James Tin-Yau

    Accelerated Gradient Methods for Stochastic Optimization and Online Learning Chonghai Hu , James T to converge slowly. In this paper, we develop a novel accelerated gradient method for stochastic optimization SAGE (Stochastic Accelerated GradiEnt), exhibits fast convergence rates on stochastic composite

  13. Semi-Stochastic Gradient Descent Methods Jakub Konecny Peter Richtarik

    E-print Network

    Edinburgh, University of

    to evaluate full gradient at each iteration. Stochastic Gradient Descent (SGD) picks i {1, 2, . . . , n} uniformly at random, and sets xj+1 = xj - hfi (xj). SGD drastically reduces the amount of work that needs the work efficiency of SGD. 2. The Algorithm (S2GD) In the S2GD algorithm, we compute full gradient (gj

  14. Creating gradients of two proteins by differential passive adsorption onto a PEG-density gradient.

    PubMed

    Vasilev, Krasimir; Mierczynska, Agnieszka; Hook, Andrew L; Chan, Joseph; Voelcker, Nicolas H; Short, Rob D

    2010-01-01

    Many fundamental biological processes, including early embryo development, immune responses and the progression of pathogens, are mediated by gradients of biological molecules. Understanding these vital physiological processes requires the development of biomaterial platforms that can mimic them in-vitro. Such platforms include laboratory generated surface gradients of biological molecules. In this work, we report a method for the generation of surface gradients of two proteins. We used a surface grafting density gradient of polyethylene glycol (PEG) to control protein adsorption. In addition, we used protein size as a tool to control the position and the adsorbed amount of both proteins. To demonstrate our concept, we used fibrinogen as an example of a large protein and lysozyme as an example of a small protein. However, we speculate that the same strategy could be extended to any other pair of large and small proteins. We used X-ray photoelectron spectroscopy and sessile drop contact angle measurements to determine the chemical composition and wettability of the gradients. Protein adsorption was studied by surface plasmon resonance imaging. PMID:19811821

  15. A supply chain disturbances classification

    Microsoft Academic Search

    Ana P. Barroso; Virgínia H. Machado; V. Cruz Machado

    2008-01-01

    Nowadays, organizations and supply chains have to deal with a number of disturbances. The pressures to grow revenues, to take advantage of new technologies, to reduce costs, and to improve working capital and streamline operational procedures, pushed many organizations to establish strategies which increase risk exposure. As a result, companies can loose the ability to act quickly and effectively in

  16. Gravity Waves from Chain Inflation

    E-print Network

    Amjad Ashoorioon; Katherine Freese

    2008-11-14

    Chain inflation proceeds through a series of first order phase transitions, which can release considerable gravitational waves (GW). We demonstrate that bubble collisions can leave an observable signature for future high-frequency probes of GWs, such as advanced LIGO, LISA and BBO. A "smoking gun" for chain inflation would be wiggles in the spectrum (and consequently in the tensor spectral index) due to the multiple phase transitions. The spectrum could also be distinguished from a single first order phase transition by a small difference in the amplitude at low frequency. A second origin of GWs in chain inflation are tensor modes from quantum fluctuations; these GW can dominate and be observed on large scales. The consistency relation between scalar and tensor modes is different for chain inflation than for standard rolling models and is testable by Cosmic Microwave Background experiments. If inflation happened through a series of rapid tunnelings in the string landscape, future high frequency probes of GW can shed light on the structure of the landscape.

  17. GTEx Chain of Custody Form

    Cancer.gov

    GTEx Chain of Custody Form OP-0002-F1 VER. 1.0.1 Effective Date: 08/30/2011 Page 1 of 3 Note: If this is the last part of the form you are completing at this time, please send the form to Study Management Group. Be sure to include the Specimen and

  18. 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

  19. 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

  20. 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

  1. Supply Chain Enter PO Receipt

    E-print Network

    Shull, Kenneth R.

    PeopleSoft Supply Chain FMS805 Enter PO Receipt 08/11/2008 © 2008 Northwestern University FMS805 1 Enter PO Receipt for Non-Catalog Items & Services This is a training guide to step you through receiving non-catalog items and services after a PO has been dispatched and goods or services have been

  2. Gumdrop Chains and Shrinky Necklaces

    NSDL National Science Digital Library

    Gina Watkiss

    2003-01-01

    In this activity, learners thread gumdrops together to make a model of a polymer. Then they thread the chains together to mimic crosslinks, and discover how crosslinked polymers act differently than uncrosslinked ones. Use this activity to illustrate about the various structures of polymers.

  3. Effect of Temperature Gradient on Thick Film Selective Emitter Emittance

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.; Good, Brian S.; Clark, Eric B.; Chen, Zheng

    1997-01-01

    A temperature gradient across a thick (greater than or equal to .1 mm) film selective emitter will produce a significant reduction in the spectral emittance from the no temperature gradient case. Thick film selective emitters of rare earth doped host materials such as yttrium-aluminum-garnet (YAG) are examples where temperature gradient effects are important. In this paper a model is developed for the spectral emittance assuming a linear temperature gradient across the film. Results of the model indicate that temperature gradients will result in reductions the order of 20% or more in the spectral emittance.

  4. Introduction The Sustainable Supply Chain Taxes Permits Integration Future Research Sustainable Supply Chains

    E-print Network

    Nagurney, Anna

    Introduction The Sustainable Supply Chain Taxes Permits Integration Future Research Sustainable Supply Chains: Multicriteria Decision-Making and Policy Analysis for the Environment Trisha D. Woolley;Introduction The Sustainable Supply Chain Taxes Permits Integration Future Research 1 Introduction 2

  5. Gravity gradient preliminary investigations, part 2: Lunar tidal gravity gradients and stresses (exhibit C)

    NASA Technical Reports Server (NTRS)

    Houston, M. H.; Thompson, L. G. D.

    1971-01-01

    Preliminary analysis of the gravity gradients associated with gravity tides on the moon caused by the earth indicates that the relative changes in the gradients are very irregular, and large, and about 15 times greater than those experienced on earth. Thus gradients, in preference to gravity tides themselves, may well be an important key in correlating tide effects with lunar transient events and moonquakes, and also in determining triggering mechanisms for crustal movement and faulting. Preliminary analysis of lunar crustal stresses and strains caused by lunar gravity tides indicates that these factors may be more direct causative agents or triggering mechanisms. In particular, the cubic dilation undergoes relatively large changes and is about 11 times greater on the moon than on earth. Thus it should be correspondingly more important.

  6. 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.

  7. 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.

  8. New Techniques for Studying Calcium Gradients

    NASA Technical Reports Server (NTRS)

    Tsien, R. Y.

    1985-01-01

    Improved techniques for detecting and manipulating spatial gradients of cytosolic free Ca(2+) concentrations (Ca(2)) sub i and intracellular stores are discussed. Three areas of progress are: (1) development of new fluorescent indicators for Ca(2+) that are the first to be suitable for measuring Ca(2+)) sub i and its inhomogeneities in individual cells; (2) invention of photolabile chelators which shift irreversibly from high to low affinity for Ca(2+) upon illumination, permitting light-controlled jumps in (Ca(2+)) sub i; and (3) fixation methods to trap dynamic intraorganellar Ca stores in a form readily visible by electron microscopy.

  9. Radial gradients in the SLUGGS survey

    NASA Astrophysics Data System (ADS)

    Foster, Caroline

    2015-02-01

    The SAGES Legacy Unifying Galaxies and GlobularS (SLUGGS) survey probes the outskirts of early-type galaxies (ETGs). SLUGGS uses the DEIMOS spectrograph on Keck to simultaneously obtain globular cluster and spatially resolved galaxy spectra. The galaxy spectra allow for the reconstruction of kinematic maps out to ~3 effective radii (R e ), while globular clusters (GCs) push the galactocentric limit out to ~8-10R e . Stellar population parameters (abundances) can also be recovered. This provides a unique dataset for exploring the outer gradients (abundance and/or kinematic transition). We briefly present recent and salient results of the SLUGGS survey so far.

  10. 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.

  11. High gradient experiments on NLCTA accelerator structures

    SciTech Connect

    Wang, J.W.; Eichner, J.P.; Fant, K.H. [and others

    1996-08-01

    This paper presents new results of high-gradient studies performed on a 1.8 m traveling-wave accelerator section with detuned high-order deflecting modes. This structure was designed initially for studies of detuned structures and will be installed in the Next Linear Collider Test Accelerator (NLCTA). The paper describes the test set-up in the Accelerator Structure Test Area (ASTA) including electron gun, prebuncher, pre-accelerator, spectrometer, Faraday cups, 200 MW SLED-II power compression system, Magic-T type phase shifters and attenuators. Rf processing, detailed dark current analysis, radiation problems, and beam acceleration measurements are discussed.

  12. Pulsed Gradient Spin-Echo NMR

    NASA Astrophysics Data System (ADS)

    Zheng, Gang; Krause-Heuer, Anwen M.; Price, William S.

    Translational diffusion (also referred to as self-diffusion, Brownian motion, or random walks) plays a vital role in all sorts of molecular dynamics in biological systems (e.g., ligand-DNA interactions, lipid-macromolecule interactions, and macromolecule aggregation). Due to its non-invasive nature, pulsed gradient spin-echo (PGSE) NMR has become a method of choice for the study of molecular dynamics and structural details of biological systems [1, 2]; in combination with magnetic resonance imaging (MRI), it allows (localised) in vivo diffusion measurements.

  13. Salt gradient solar pond development. Final report

    SciTech Connect

    Nielsen, C.E.

    1981-01-01

    A research solar pond was constructed. From the operation of this pond and the continuing operation of the Farm Science review pond completed in 1975 important new information on pond performance and operating procedures has been obtained. Work discussed here includes design and construction of the research pond, measurement of energy balance and efficiency, measurements of salinity profiles and their use in determining salt transport rate, study of surface zone growth and the processes responsible for it, study of the processes involved in the interface between convective and gradient zones, tests of heat extraction systems, and measurement and control of water quality.

  14. Projected gradient methods for nonnegative matrix factorization.

    PubMed

    Lin, Chih-Jen

    2007-10-01

    Nonnegative matrix factorization (NMF) can be formulated as a minimization problem with bound constraints. Although bound-constrained optimization has been studied extensively in both theory and practice, so far no study has formally applied its techniques to NMF. In this letter, we propose two projected gradient methods for NMF, both of which exhibit strong optimization properties. We discuss efficient implementations and demonstrate that one of the proposed methods converges faster than the popular multiplicative update approach. A simple Matlab code is also provided. PMID:17716011

  15. Nonreciprocal propagating electromagnetic modes without phase gradients

    NASA Astrophysics Data System (ADS)

    Guo, Rui-Peng; Wu, Li-Ting; Yang, Mu; Guo, Tian-Jing; Cui, Hai-Xu; Cao, Xue-Wei; Chen, Jing

    2015-02-01

    We introduce a concept of a k -zero mode, an electromagnetic wave with a nonzero group velocity (? ? /? k ?0 ) but a null phase gradient (k =0 ) . Existence conditions of k -zero modes are discussed. We emphasize that the existence of k -zero modes is closely related to the the unique nonzero lateral displacement when reflected from a magneto-optical (MO) medium at normal incidence. Consequently, the waveguide should be suitably designed to avoid a destructive interference between the lateral displacements at different MO-dielectric interfaces. Numerical full-field simulation proves our analysis. The importance of this study is discussed.

  16. Observations of Warm Carbon Chain Chemistry in NGC 3576

    NASA Astrophysics Data System (ADS)

    Saul, M.; Tothill, N. F. H.; Purcell, C. R.

    2015-01-01

    We report observations of warm carbon chain chemistry (WCCC) in NGC 3576, including high angular resolution imaging of an ionization source candidate and the first detection of C5H in a massive star-forming region. In order to investigate the environment associated with birthline emergence, we ask how observed chemical conditions relate to Class 0/1 core differentiation: a systemic shift in peak position between species correlates with giant molecular cloud core gradients in turbulence and age. Emission in several molecular lines including HC3N (11-10), NH3 (1, 1), and C5H supports the G291.3-0.7 ionization front—transitional pre-main-sequence core interaction regulating the WCCC environment.

  17. Markov chains and embedded Markov chains in geology

    Microsoft Academic Search

    W. C. Krumbein; Michael F. Dacey

    1969-01-01

    Geological data are structured as first-order, discrete-state discrete-time Markov chains in two main ways. In one, observations are spaced equally in time or space to yield transition probability matrices with nonzero elements in the main diagonal; in the other, only state transitions are recorded, to yield matrices with diagonal elements exactly equal to zero. The mathematical differences in these two

  18. Coordinated supply chain dynamic production planning model

    NASA Astrophysics Data System (ADS)

    Chandra, Charu; Grabis, Janis

    2001-10-01

    Coordination of different and often contradicting interests of individual supply chain members is one of the important issues in supply chain management because the individual members can not succeed without success of the supply chain and vice versa. This paper investigates a supply chain dynamic production planning problem with emphasis on coordination. A planning problem is formally described using a supply chain kernel, which defines supply chain configuration, management policies, available resources and objectives both at supply chain or macro and supply chain member or micro levels. The coordinated model is solved in order to balance decisions made at the macro and micro levels and members' profitability is used as the coordination criterion. The coordinated model is used to determine inventory levels and production capacity across the supply chain. Application of the coordinated model distributes costs burden uniformly among supply chain members and preserves overall efficiency of the supply chain. Influence of the demand series uncertainty is investigated. The production planning model is a part of the integrated supply chain decision modeling system, which is shared among the supply chain members across the Internet.

  19. Temporal gradients in shear, but not spatial gradients, stimulate ERK1/2 activation in human endothelial cells.

    PubMed

    White, Charles R; Stevens, Hazel Y; Haidekker, Mark; Frangos, John A

    2005-12-01

    We have previously demonstrated temporal gradients in shear stress stimulate endothelial cell proliferation, whereas spatial gradients do not. In the present study, the extracellular signal-regulated kinases 1 and 2 (ERK1/2) pathway was investigated as a possible mediator for the promitogenic effect of temporal gradients. The sudden expansion flow chamber (SEFC) model was used to differentiate the effect of temporal gradients in shear from that of spatial gradients on ERK1/2 activation in human umbilical vein endothelial cells (HUVEC). ERK1/2 activation in the SEFC was not significantly different from control when HUVEC were exposed to spatial gradients alone. When a single temporal impulse was superimposed on spatial gradients, ERK1/2 activation was stimulated 330% (relative to spatial alone) within the region of spatial gradients. Inhibition of the ERK1/2 pathway with U-0126 abolished all effects of temporal gradients. To further separate temporal and spatial gradients, a conventional parallel plate flow chamber was utilized. Acute exposure to oscillations in flow at a frequency of 1 Hz stimulated ERK1/2 activation 620 +/- 88% relative to control, whereas a single impulse of flow increased ERK1/2 activation 166 +/- 19%. Flow without the temporal component did not significantly activate ERK1/2. These results suggest that the ERK1/2 pathway directly mediates the promitogenic effects of temporal gradients in shear stress. PMID:16284106

  20. 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.

  1. Gradient navigation model for pedestrian dynamics

    NASA Astrophysics Data System (ADS)

    Dietrich, Felix; Köster, Gerta

    2014-06-01

    We present a microscopic ordinary differential equation (ODE)-based model for pedestrian dynamics: the gradient navigation model. The model uses a superposition of gradients of distance functions to directly change the direction of the velocity vector. The velocity is then integrated to obtain the location. The approach differs fundamentally from force-based models needing only three equations to derive the ODE system, as opposed to four in, e.g., the social force model. Also, as a result, pedestrians are no longer subject to inertia. Several other advantages ensue: Model-induced oscillations are avoided completely since no actual forces are present. The derivatives in the equations of motion are smooth and therefore allow the use of fast and accurate high-order numerical integrators. At the same time, the existence and uniqueness of the solution to the ODE system follow almost directly from the smoothness properties. In addition, we introduce a method to calibrate parameters by theoretical arguments based on empirically validated assumptions rather than by numerical tests. These parameters, combined with the accurate integration, yield simulation results with no collisions of pedestrians. Several empirically observed system phenomena emerge without the need to recalibrate the parameter set for each scenario: obstacle avoidance, lane formation, stop-and-go waves, and congestion at bottlenecks. The density evolution in the latter is shown to be quantitatively close to controlled experiments. Likewise, we observe a dependence of the crowd velocity on the local density that compares well with benchmark fundamental diagrams.

  2. Droplet microfluidics driven by gradients of confinement.

    PubMed

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

    2013-01-15

    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

  3. Intergenerational and socioeconomic gradients of child obesity.

    PubMed

    Costa-Font, Joan; Gil, Joan

    2013-09-01

    Can the rise in obesity among children be attributed to the intergenerational transmission of parental influences? Does this trend affect the influence of parent's socioeconomic status on obesity? This paper documents evidence of an emerging social gradient of obesity in pre-school children resulting from a combination of both socio-economic status and less intensive childcare associated with maternal employment, when different forms of intergenerational transmission are controlled for. We also estimate and decompose income related inequalities in child obesity. We take advantage of a uniquely constructed dataset from Spain that contains records form 13,358 individuals for a time period (years 2003-2006) in which a significant spike in the growth of child obesity was observed. Our results suggest robust evidence of both socioeconomic and intergenerational gradients. Results are suggestive of a high income effect in child obesity, alongside evidence that income inequalities have doubled in just three years with a pure income effect accounting for as much as 72-66% of these income inequality estimates, even when intergenerational transmission is accounted for. Although, intergenerational transmission does not appear to be gender specific, when accounted for, mother's labour market participation only explains obesity among boys but not among girls. Hence, it appears income and parental influences are the central determinants of obesity among children. PMID:23906118

  4. Cortical thickness gradients in structural hierarchies.

    PubMed

    Wagstyl, Konrad; Ronan, Lisa; Goodyer, Ian M; Fletcher, Paul C

    2015-05-01

    MRI, enabling in vivo analysis of cortical morphology, offers a powerful tool in the assessment of brain development and pathology. One of the most ubiquitous measures used-the thickness of the cortex-shows abnormalities in a number of diseases and conditions, but the functional and biological correlates of such alterations are unclear. If the functional connotations of structural MRI measures are to be understood, we must strive to clarify the relationship between measures such as cortical thickness and their cytoarchitectural determinants. We therefore sought to determine whether patterns of cortical thickness mirror a key motif of the cortex, specifically its structural hierarchical organisation. We delineated three sensory hierarchies (visual, somatosensory and auditory) in two species-macaque and human-and explored whether cortical thickness was correlated with specific cytoarchitectural characteristics. Importantly, we controlled for cortical folding which impacts upon thickness and may obscure regional differences. Our results suggest that an easily measurable macroscopic brain parameter, namely, cortical thickness, is systematically related to cytoarchitecture and to the structural hierarchical organisation of the cortex. We argue that the measurement of cortical thickness gradients may become an important way to develop our understanding of brain structure-function relationships. The identification of alterations in such gradients may complement the observation of regionally localised cortical thickness changes in our understanding of normal development and neuropsychiatric illnesses. PMID:25725468

  5. Nappe emplacement under lateral pressure gradient

    NASA Astrophysics Data System (ADS)

    Podladchikov, Yury; Schmalholz, Stefan

    2014-05-01

    New thin viscous approximation is under development specifically targeted to model spontaneous initiation and tens of kilometers horizontal displacement of tectonic nappes. Nappes are few kilometers thing and tens of kilometers long rock units trusted towards foreland often preserving internal lithological consistency and laying at near horizontal position at the end of the emplacement. Significant shear stresses and deviation of principal stresses from vertical is required to explain this very peculiar strain localization style from mechanical point of view. There is also a need for the explanation of their common appearances in most collisional settings. Both pure shear thin sheet and flexural models kinematically eliminate nappes formation. Spreading viscous sheet models, such as used to model glaciers, are also not applicable as the direction of motion is upward, against gravity. The reason for this discrepancy is the hydrostatic pressure approximation of the gravity-driven spreading models. Actually, the thin sheet approximation is not sensitive to the assumptions made on pressure profile. Lateral non-lithostatic pressure gradient-driven viscous sheet model is appropriate for modeling of nappes. In turn, significant non-lithostatic pressure must be supported by flexural rigidity of overlying and underlying units. Lateral gradients of this non-lithostatic pressure are responsible for the significant shear stress and, therefore, deviation of principal stress from vertical.

  6. 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.

  7. The phenotypic variance gradient – a novel concept

    PubMed Central

    Pertoldi, Cino; Bundgaard, Jørgen; Loeschcke, Volker; Barker, James Stuart Flinton

    2014-01-01

    Evolutionary ecologists commonly use reaction norms, which show the range of phenotypes produced by a set of genotypes exposed to different environments, to quantify the degree of phenotypic variance and the magnitude of plasticity of morphometric and life-history traits. Significant differences among the values of the slopes of the reaction norms are interpreted as significant differences in phenotypic plasticity, whereas significant differences among phenotypic variances (variance or coefficient of variation) are interpreted as differences in the degree of developmental instability or canalization. We highlight some potential problems with this approach to quantifying phenotypic variance and suggest a novel and more informative way to plot reaction norms: namely “a plot of log (variance) on the y-axis versus log (mean) on the x-axis, with a reference line added”. This approach gives an immediate impression of how the degree of phenotypic variance varies across an environmental gradient, taking into account the consequences of the scaling effect of the variance with the mean. The evolutionary implications of the variation in the degree of phenotypic variance, which we call a “phenotypic variance gradient”, are discussed together with its potential interactions with variation in the degree of phenotypic plasticity and canalization. PMID:25540685

  8. The phenotypic variance gradient - a novel concept.

    PubMed

    Pertoldi, Cino; Bundgaard, Jørgen; Loeschcke, Volker; Barker, James Stuart Flinton

    2014-11-01

    Evolutionary ecologists commonly use reaction norms, which show the range of phenotypes produced by a set of genotypes exposed to different environments, to quantify the degree of phenotypic variance and the magnitude of plasticity of morphometric and life-history traits. Significant differences among the values of the slopes of the reaction norms are interpreted as significant differences in phenotypic plasticity, whereas significant differences among phenotypic variances (variance or coefficient of variation) are interpreted as differences in the degree of developmental instability or canalization. We highlight some potential problems with this approach to quantifying phenotypic variance and suggest a novel and more informative way to plot reaction norms: namely "a plot of log (variance) on the y-axis versus log (mean) on the x-axis, with a reference line added". This approach gives an immediate impression of how the degree of phenotypic variance varies across an environmental gradient, taking into account the consequences of the scaling effect of the variance with the mean. The evolutionary implications of the variation in the degree of phenotypic variance, which we call a "phenotypic variance gradient", are discussed together with its potential interactions with variation in the degree of phenotypic plasticity and canalization. PMID:25540685

  9. The microbial food web along salinity gradients.

    PubMed

    Pedrós-Alió; Calderón-Paz; MacLean; Medina; Marrasé; Gasol; Guixa-Boixereu

    2000-04-01

    The microbial food web was studied along a gradient of salinity in two solar salterns used for the commercial production of salt. The different ponds in the salterns provide a wide range of ecosystems with food webs of different complexities. Abundance of prokaryotes, cell volume, prokaryotic heterotrophic production, chlorophyll a, abundance of heterotrophic flagellates, ciliates and phytoplankton were determined in several ponds in each saltern. Increases in salinity resulted in a progressive reduction in the abundance and number of different groups of eukaryotic microorganisms present, but an increase in biomass of prokaryotes. Maximal activity of both phyto- and bacterioplankton was found at a salinity of around 100 per thousand, where there was also a maximum in chlorophyll a concentration. Growth rates of heterotrophic prokaryotes decreased with increasing salinity. Bacterivory disappeared above 250 per thousand salinity, whereas other loss factors such as viral lysis appeared to be of minor importance throughout the gradient [Guixa-Boixereu et al. (1996) Aquat. Microb. Ecol. 11, 215-227]. PMID:10817867

  10. Gradients of O2 concentration in hepatocytes.

    PubMed

    Jones, D P; Mason, H S

    1978-07-25

    1. Cytochrome P/450-dependent mixed function oxidations of hexobarbital, phenyramidol, and alprenolol in intact hepatocytes were examined at different steady state oxygen concentrations. Apparent Kmo2 values were determined to be 6.4 +/- 1.7, 3.6 +/- 0.6, and 9.8 +/- 1.2 micronM, respectively. 2. Apparent Kmo2 values for metabolism of hexobarbital and alprenolol by liver microsomes were 4.3 +/- 0.4 and 8.7 +/- 0.7 micronM, similar to the corresponding values for whole cells. Therefore, no detectable gradient of O2 concentration exists between extracellular space and endoplasmic reticulum of hepatocytes at these oxygen concentrations. 3. Steady state concentrations of ATP, ADP, AMP, lactate, and pyruvate at different steady state oxygen concentrations were used as indicators of mitochondrial oxygen dependence in intact hepatocytes. Half-maximal changes occurred at [O2] = 12.6 micronM for cytoplasmic [NAD+]/[NADH] (estimated from [lactate]/[pyruvate]), at 7.0 micronM for [ATP]/[ADP], and at 2.8 micronM for adenylate energy charge. The apparent cellular respiratory Kmo2 was 1.90 +/- 0.18 micronM. 4. Comparison of values for oxygen dependence of mitochondrial functions in isolated hepatocytes with published values for isolated mitochondria suggests that a substantial intracellular oxygen gradient exists between the outer cellular membrane and the mitochondrial inner membrane at po2 values below the critical O2 tensions. PMID:209020

  11. 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

  12. Gradientes de abundâncias em galáxias espirais

    NASA Astrophysics Data System (ADS)

    Dors, O. L.., Jr.; Copetti, M. V. F.

    2003-08-01

    Gradientes de abundâncias obtidos através de observações de regiões H II têm um papel importante no estudo de formação e evolução de galáxias espirais. Determinações diretas de abundâncias somente são obtidas quando linhas de emissão sensíveis à temperatura eletrônica (e.g., [O III]l4363) são detectadas. Infelizmente estas linhas são fracas ou não observadas em regiões H II de baixa excitação. Nestes casos métodos empíricos são utilizados para estimar as abundâncias químicas. Entretanto, diferentes métodos têm produzido diferentes estimativas de gradientes de abundâncias. Neste trabalho, nós construímos modelos de fotoionização com o objetivo de descrever diagramas de diagnósticos construídos com dados publicados de algumas galáxias espirais normais e barradas. Comparações entre nossas estimativas de abundâncias e de outros métodos mostram que quando não há acordo entre eles, nossos modelos superestimam as abundâncias de O/H e N/H por um fator de 0.3 dex em relação a estimativas diretas de abundâncias, e por fator de 0.2 dex em relação a outros métodos empíricos. A origem da produção de nitrogênio nas galáxias estudadas é discutida.

  13. 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

  14. Parameter inference for discretely observed stochastic kinetic models using stochastic gradient descent

    PubMed Central

    2010-01-01

    Background Stochastic effects can be important for the behavior of processes involving small population numbers, so the study of stochastic models has become an important topic in the burgeoning field of computational systems biology. However analysis techniques for stochastic models have tended to lag behind their deterministic cousins due to the heavier computational demands of the statistical approaches for fitting the models to experimental data. There is a continuing need for more effective and efficient algorithms. In this article we focus on the parameter inference problem for stochastic kinetic models of biochemical reactions given discrete time-course observations of either some or all of the molecular species. Results We propose an algorithm for inference of kinetic rate parameters based upon maximum likelihood using stochastic gradient descent (SGD). We derive a general formula for the gradient of the likelihood function given discrete time-course observations. The formula applies to any explicit functional form of the kinetic rate laws such as mass-action, Michaelis-Menten, etc. Our algorithm estimates the gradient of the likelihood function by reversible jump Markov chain Monte Carlo sampling (RJMCMC), and then gradient descent method is employed to obtain the maximum likelihood estimation of parameter values. Furthermore, we utilize flux balance analysis and show how to automatically construct reversible jump samplers for arbitrary biochemical reaction models. We provide RJMCMC sampling algorithms for both fully observed and partially observed time-course observation data. Our methods are illustrated with two examples: a birth-death model and an auto-regulatory gene network. We find good agreement of the inferred parameters with the actual parameters in both models. Conclusions The SGD method proposed in the paper presents a general framework of inferring parameters for stochastic kinetic models. The method is computationally efficient and is effective for both partially and fully observed systems. Automatic construction of reversible jump samplers and general formulation of the likelihood gradient function makes our method applicable to a wide range of stochastic models. Furthermore our derivations can be useful for other purposes such as using the gradient information for parametric sensitivity analysis or using the reversible jump samplers for full Bayesian inference. The software implementing the algorithms is publicly available at http://cbcl.ics.uci.edu/sgd PMID:20663171

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

    E-print Network

    Peacor, Scott

    production plays a critical role in the Great Lakes ecosystem, and vertical migration, which is exhibited The production of zooplankton is important to Great Lakes eco- systems, as zooplankton serve as a critical food of a day which can in turn affect zooplankton production. Gradients in water temperature and food resources

  16. Development of high-gradient and open-gradient magnetic separation

    SciTech Connect

    Hise, E C

    1981-01-01

    This paper was prepared: to review the accomplishments in both high-gradient magnetic separation (HGMS) and open-gradient magnetic separation (OGMS) by the Oak Ridge National Laboratory (ORNL) group during the past three years; to show, through the medium of motion pictures, the operation of the various separation methods and devices used and developed; to show qualitative results of the separation performed; and to make available, to those interested, detailed reports of the experimental procedures and the resulting data. The qualitative separation of pyritic sulfur and ash forming minerals from fine coal by high gradient magnetic separation has been demonstrated at feed rates up to one ton per hour, and in a machine that is commercially produced in sizes for feed rates up to several hundred tons per hour. The quantitative separation of pyritic sulfur and ash forming minerals from fine coal by free fall open gradient magnetic separation has been demonstrated at a laboratory scale and at 300 kg per hour in a solenoidal magnet configuration. A magnet modeling analysis has shown that an optimum magnet can be designed with practical physical constraints which can generate separating forces two to three times those of the existing solenoidal configuration and with a large processing capacity. The analytical predictions of the behavior of particles traversing these separating forces have been experimentally confirmed within 15% in existing magnets.

  17. 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 ...

  18. Managing flexibility in the supply chain

    E-print Network

    Taylor, James B. (James Boyd), 1975-

    2003-01-01

    Supply chain flexibility is introduced and its importance is discussed. This is followed by a review of the flexibility literature in manufacturing, supply chain, economics, strategy, organizational design, and industrial ...

  19. An integrative framework for architecting supply chains

    E-print Network

    Cela Díaz, Fernando

    2006-01-01

    This thesis explores the limitations of classic models of supply chain management, and proposes a new view based on the concept of value-driven supply chains, and a method of analysis and design based on the concepts of ...

  20. Polymerization as a Model Chain Reaction

    ERIC Educational Resources Information Center

    Morton, Maurice

    1973-01-01

    Describes the features of the free radical, anionic, and cationic mechanisms of chain addition polymerization. Indicates that the nature of chain reactions can be best taught through the study of macromolecules. (CC)

  1. 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, Massachusetts 01003 2Department of Electrical and Computer Engineering University of Massachusetts Amherst Pharmaceutical Supply Chain Networks with Outsourcing #12;Acknowledgments This research

  2. Pharmaceutical Supply Chain Networks with Outsourcing

    E-print Network

    Nagurney, Anna

    Pharmaceutical Supply Chain Networks with Outsourcing Under Price and Quality Competition Anna, Amherst, Massachusetts 01003 2Department of Electrical and Computer Engineering University of Hartford Amherst Pharmaceutical Supply Chain Networks with Outsourcing #12;Acknowledgments This research

  3. Single-chain polymer nanoparticles.

    PubMed

    Aiertza, Miren Karmele; Odriozola, Ibon; Cabañero, Germán; Grande, Hans-Jürgen; Loinaz, Iraida

    2012-02-01

    The synthesis of polymer nanoparticles (NPs) with controlled characteristics has become an appealing research topic lately. Nanomedicine, and especially drug delivery and imaging, are fields that require particles of a controlled size and with a tailored arrangement of functional groups. Intramolecular cross-linking or collapse of single polymer chains has emerged as an efficient alternative for the synthesis of well-defined polymer NPs. This technique allows the generation of 1.5-20 nm particles with a wide variety of chemical compositions and functionalities. This review begins by gathering synthetic strategies described in the literature and groups them into four main synthetic methods: homo-functional collapse, hetero-functional collapse, crosslinker-mediated collapse, and one-block collapse of diblock or triblock copolymers. Afterwards, the main characterization techniques and physical properties of single-chain polymer NPs (SCPNs) are exposed. Finally, several applications in nanomedicine are mentioned followed by some future perspectives. PMID:22015611

  4. 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

  5. Modeling carbon footprints across the supply chain

    Microsoft Academic Search

    Balan Sundarakani; Robert de Souza; Mark Goh; Stephan M. Wagner; Sushmera Manikandan

    2010-01-01

    Environmental consciousness has become critical in the design and operation of globally integrated supply chain networks. This research examines the carbon footprint across supply chains and thus contributes to the knowledge and practice of green supply chain management. The analytical model uses the long-range Lagrangian and the Eulerian transport methods. Analytical and finite difference methods are used to approximate the

  6. The Risk Management of Supply Chain

    Microsoft Academic Search

    Yuan Jianlin

    2010-01-01

    With the globalization, a product is assembled by various parts of the product that are produced in different countries. How to finish the task? It depends on the supply chain. The products are transported different area of the worlds by the supply chain; the enterprise gets the profit when the products are sold. But the supply chain suffers the different

  7. Supply Chains and Transportation Networks Anna Nagurney

    E-print Network

    Nagurney, Anna

    Supply Chains and Transportation Networks Anna Nagurney Department of Finance and Operations behavioral principles. We emphasize that the foundations of supply chains as network systems can be found, and accompanying methodologies have enabled the advancement of supply chain network models from a system

  8. Learning to Integrate: Supply Chains Reconceptualised

    ERIC Educational Resources Information Center

    Sense, Andrew J.; Clements, Michael D. J.

    2007-01-01

    This paper introduces and explains a conception of supply chains from a situated learning perspective. This non-conventional supply chain perspective invites the reader to consider supply chain scenarios as "situated learning opportunities involving multiple communities of practice" interacting and participating together. It is argued that by…

  9. 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

  10. Visualisation for System Learning in Supply Chains

    ERIC Educational Resources Information Center

    Lindskog, Magnus; Abrahamsson, Mats; Aronsson, Hakan

    2007-01-01

    Contemporary supply chains are vastly complex, and decisions made by actors have system-wide consequences that these might not be able to foresee. There are gaps between "best practice"-founded theory and actual practice in supply chains. To remedy this, we argue, the supply chain actors need to enhance systems knowledge. There is a need to…

  11. Decentralized Supply Chains Subject to Information Delays

    Microsoft Academic Search

    Fangruo Chen

    1999-01-01

    We consider a supply chain whose members are divisions of the same firm. The divisions are managed by different individuals with only local inventory information. Both the material and information flows in the supply chain are subject to delays. Under the assumption that the division managers share a common goal to optimize the overall performance of the supply chain (i.e.,

  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. 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…

  14. The Value Chain of Colorado Agriculture

    E-print Network

    The Value Chain of Colorado Agriculture Gregory Graff, Ryan Mortenson, Rebecca Goldbach, Dawn citation: Graff, Mortenson, Goldbach, et al, The Value Chain of Colorado Agriculture, Department. © 2013 Colorado State University, Fort Collins, Colorado 80523 USA #12;iThe Value Chain of Colorado

  15. 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…

  16. Value Chain Partnerships Phase III, Year 1

    E-print Network

    Debinski, Diane M.

    Value Chain Partnerships Phase III, Year 1 Evaluation Results and Discussion Corry Bregendahl, Assistant Scientist North Central Regional Center for Rural Development Prepared for the Value Chain The Value Chain Partnerships project creates and supports Communities of Practice (CoPs) that facilitate

  17. 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

  18. Supply Chain Management Professional Education Review

    E-print Network

    Lin, Xiaodong

    of Supply Chain Management and Marketing Science A majority of the US pharmaceutical/biotech manufacturers Supply Chain Management Professional Education Review A monthly eNewsletter by the Department of Supply Chain Management and Marketing Sciences June 2009 Upcoming Events 2009

  19. The scope of supply chain management research

    Microsoft Academic Search

    Stephen J. New

    1997-01-01

    Advocates an expanded scope for supply chain management research which accounts for the social function and the political and economic implications of supply chain developments. Argues that the research agenda must not be driven by the notion of efficiency alone, but should also be developed around the concept of the just supply chain. Provides a framework which sets out the

  20. Supply Chain Management Jayashankar M. Swaminathan

    E-print Network

    Swaminathan, Jayashankar M.

    1 Supply Chain Management July 2000 Jayashankar M. Swaminathan The Kenan-Flagler Business School work ever in Social and Behavioral Sciences). #12;2 1. Introduction Supply chain management is one management. #12;3 2. Definition Supply chain management is a vast topic as a result people often give

  1. Supply Chain Management Strategy PROFESSIONAL DEVELOPMENT SEMINAR

    E-print Network

    Gilchrist, James F.

    Supply Chain Management Strategy PROFESSIONAL DEVELOPMENT SEMINAR Saturday, June 14th, and Friday with the College of Business and Economics Graduate Programs Office invites you to attend Supply Chain Management Strategy on June 14 and June 20. WHAT YOU WILL LEARN For many companies, Supply Chain Management has become

  2. Supply Chain Management Professional Education Review

    E-print Network

    Lin, Xiaodong

    Supply Chain Management Professional Education Review A monthly eNewsletter by the Department of Supply Chain Management and Marketing Sciences May 2009 Upcoming Events. In this month's issue 1. Exactly two years ago, the Rutgers Center for Supply Chain Management convened

  3. Performance measurement for green supply chain management

    Microsoft Academic Search

    Aref A. Hervani; Marilyn M. Helms; Joseph Sarkis

    2005-01-01

    Purpose – To introduce and provide an overview of the various issues related to environmental (green) supply chain management performance measurement. Design\\/methodology\\/approach – The work relies on experiences, case studies and other literature related to performance measurement in environmental supply chains. It seeks to integrate works in supply chain management, environmental management, and performance management into one framework. A systems

  4. IEMS 486: Supply Chain Management Summer 2012

    E-print Network

    Smilowitz, Karen

    IEMS 486: Supply Chain Management Summer 2012 Instructor: Karen Smilowitz Office: Tech M233 Office:30-9:30 (FORD 1.350) Course Description Supply chain management is unique and, to some degree, represents of business. Supply chain system activities - information sharing, inventory management, warehousing

  5. Supply Chain Management Degree Curriculum Information Sheet

    E-print Network

    Lin, Xiaodong

    Supply Chain Management Degree Curriculum Information Sheet Business Core 33:010:275-Intro to double major in Supply Chain and Finance should take Financial Management for Finance Majors (33 to Project Management will be counted as a Supply Chain elective. #12;SSUUPPPPLLYY CCHHAAIINN AANNDD

  6. Agent-Oriented Supply-Chain Management

    Microsoft Academic Search

    MARK S. FOX; MIHAI BARBUCEANU; RUNE TEIGEN

    2000-01-01

    The supply chain is a worldwide network of suppliers, factories, warehouses, distribution centers, and retailers through which raw materials are acquired, transformed, and delivered to customers. In recent years, a new software architecture for managing the supply chain at the tactical and operational levels has emerged. It views the supply chain as composed of a set of intelligent software agents,

  7. Supply Chain Management Professional Education Review

    E-print Network

    Lin, Xiaodong

    Supply Chain Management Professional Education Review A monthly eNewsletter by the Department of Supply Chain Management and Marketing Sciences December 2009 Upcoming Events for Supply Chain Management is providing customized training for a U.S. manufacturing company, a Pharma R

  8. Supply Chain Integration: Challenges and Solutions

    Microsoft Academic Search

    Edward Sweeney

    2011-01-01

    Rapid changes in technological development are forcing businesses to continuously innovate to improve their competitiveness, which is particularly evident in logistics and supply chain management (SCM), where innovation impacts both the strategic and operational levels. Supply Chain Innovation for Competing in Highly Dynamic Markets: Challenges and Solutions investigates the role of innovation in the management of supply chains of today.

  9. 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

  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. IT—Enabled Supply Chain Management

    Microsoft Academic Search

    Jari Salo; Heikki Karjaluoto

    2006-01-01

    Supply chain management and information technology are two areas of research, which have attracted a lot of attention in academic and practitioner's camps over the last decades. The discussion related to the deployment of information technology and electronic commerce in supply chain management has fostered a discussion about information technology enabled supply chains. The authors pinpoint, there is a lack

  12. 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,

  13. Fashion Supply Chain Network Competition Ecolabelling

    E-print Network

    Nagurney, Anna

    Fashion Supply Chain Network Competition with Ecolabelling Anna Nagurney1,2 , Min Yu3 , and Jonas April 2014; revised June 2014 To appear in Sustainable Fashion Supply Chain Management: From Sourcing supply chain network model for fashion that in- corporates ecolabelling. We capture the individual profit

  14. Supply Chain Management Faculty Brian Fugate

    E-print Network

    significant industry experience including positions in quality assurance and supply chain management. DanSupply Chain Management Faculty Brian Fugate Brian S. Fugate (Ph.D University of Tennessee) is an Associate Professor of Supply Chain Management at Colorado State University. Brian worked in logistics

  15. 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

  16. Experience using the IBM supply chain simulator

    Microsoft Academic Search

    Sugato Bagchi; Stephen J. Buckley; Marcus Ettl; Grace Y. Lin

    1998-01-01

    The IBM Supply Chain Simulator (SCS) is a software tool that can help a company or a group of companies make strategic business decisions about the design and operation of its supply chain. SCS and its predecessors were originally developed by IBM Research to improve IBM's internal supply chains. The tool has played an important role in the resurgence of

  17. Tunnel current across linear homocatenated germanium chains

    SciTech Connect

    Matsuura, Yukihito, E-mail: matsuura@chem.nara-k.ac.jp [Department of Chemical Engineering, Nara National College of Technology Yatacho 22, Yamato-koriyama, Nara 539-1080 (Japan)

    2014-01-28

    The electronic transport properties of germanium oligomers catenating into linear chains (linear Ge chains) have been theoretically studied using first principle methods. The conduction mechanism of a Ge chain sandwiched between gold electrodes was analyzed based on the density of states and the eigenstates of the molecule in a two-probe environment. Like that of silicon chains (Si chains), the highest occupied molecular orbital of Ge chains contains the extended ?-conjugation of Ge 4p orbitals at energy levels close to the Fermi level; this is in contrast to the electronic properties of linear carbon chains. Furthermore, the conductance of a Ge chain is expected to decrease exponentially with molecular length L. The decay constant ?, which is defined as e{sup ??L}, of a Ge chain is similar to that of a Si chain, whereas the conductance of the Ge chains is higher than that of Si chains even though the Ge–Ge bond length is longer than the Si–Si bond length.

  18. INFORMS `03, Atlanta GA, October 19-21 A Supply Chain Network EconomyA Supply Chain Network Economy

    E-print Network

    Nagurney, Anna

    INFORMS `03, Atlanta GA, October 19-21 A Supply Chain Network EconomyA Supply Chain Network Economy competition. But a supply chain vs. a supply chain competition in many marketplaces today. #12;INFORMS Atlanta, GA, October 19-22, 2003 Supply Chain EconomySupply Chain Economy Supply Chain Economy (SCE

  19. Determination of gradient elastic tensors: stress and strain dependencies of electric field gradients in cubic and hexagonal systems.

    PubMed

    Brüsewitz, C; Vetter, U; Hofsäss, H

    2015-02-11

    We present ab-initio calculations of the independent components of gradient elastic tensors, so-called gradient elastic constants, which relate electric field gradient tensors to stress or strain tensors. The constants of cubic and hexagonal metals, MAX phases, and zinc oxide were determined within the framework of density functional theory by using the augmented plane waves plus local orbitals method implemented in the WIEN2k code. Comparison with experimental gradient elastic constants and electric field gradients' stress dependencies suggest an accuracy of about 30% of the calculated constants, independent of the probe that detects the field gradient being self- or foreign-atom. Changes in the electric field gradient take place by strain-induced asymmetric occupations of the p and d states in the valence region for all investigated materials. Volume and structural dependencies of the electric field gradient can directly be determined from this fundamental approach and are, for hexagonal closed packed metals, consistent with vanishing electric field gradients around ideal close packing and volume dependencies larger than one. The concept of these calculations is applicable in any hyperfine interaction method and, thus, can be used to gain information about intrinsic strains in systems where the experimental gradient elastic constants are inaccessible. PMID:25614685

  20. Determination of gradient elastic tensors: stress and strain dependencies of electric field gradients in cubic and hexagonal systems

    NASA Astrophysics Data System (ADS)

    Brüsewitz, C.; Vetter, U.; Hofsäss, H.

    2015-02-01

    We present ab-initio calculations of the independent components of gradient elastic tensors, so-called gradient elastic constants, which relate electric field gradient tensors to stress or strain tensors. The constants of cubic and hexagonal metals, MAX phases, and zinc oxide were determined within the framework of density functional theory by using the augmented plane waves plus local orbitals method implemented in the WIEN2k code. Comparison with experimental gradient elastic constants and electric field gradients' stress dependencies suggest an accuracy of about 30% of the calculated constants, independent of the probe that detects the field gradient being self- or foreign-atom. Changes in the electric field gradient take place by strain-induced asymmetric occupations of the p and d states in the valence region for all investigated materials. Volume and structural dependencies of the electric field gradient can directly be determined from this fundamental approach and are, for hexagonal closed packed metals, consistent with vanishing electric field gradients around ideal close packing and volume dependencies larger than one. The concept of these calculations is applicable in any hyperfine interaction method and, thus, can be used to gain information about intrinsic strains in systems where the experimental gradient elastic constants are inaccessible.