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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

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

J. Kozdrój; J. D. van Elsas

2000-01-01

2

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

PubMed

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

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

2014-09-01

3

Carotenoids in a food chain along a pollution gradient  

Microsoft Academic Search

Carotenoids are synthesized by plants, therefore insects and birds must obtain them from their diet. They function in pigmentation and as antioxidants. We studied the carotenoid profiles in a model food chain (plant–insect–bird) in an air pollution gradient to find out whether heavy metal pollution affects the transfer of carotenoids across the trophic levels. Birch leaves showed higher ?-carotene and,

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

2008-01-01

4

Changes in Community Structure of Sediment Bacteria Along the Florida Coastal Everglades Marsh–Mangrove–Seagrass Salinity Gradient  

Microsoft Academic Search

Community structure of sediment bacteria in the Everglades freshwater marsh, fringing mangrove forest, and Florida Bay seagrass\\u000a meadows were described based on polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) patterns of 16S\\u000a rRNA gene fragments and by sequencing analysis of DGGE bands. The DGGE patterns were correlated with the environmental variables\\u000a by means of canonical correspondence analysis. There was no

Makoto Ikenaga; Rafael Guevara; Amanda L. Dean; Cristina Pisani; Joseph N. Boyer

2010-01-01

5

Mathematical Modeling and Simulation of Denaturation Temperature Gradient Polymerase Chain Reaction  

E-print Network

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

Yoo, SukIn

6

Detonation ignition from a temperature gradient for a two-step chain-branching kinetics model  

Microsoft Academic Search

The evolution from a linear temperature gradient to a detonation is investigated for combustible materials whose chemistry is governed by chain-branching kinetics, using a combination of high-activation-temperature asymptotics and numerical simulations. A two-step chemical model is used, which captures the main properties of detonations in chain-branching fuels. The first step is a thermally neutral induction time, representing chain initiation and

Gary J. Sharpe; Mark Short

2003-01-01

7

Detonation ignition from a temperature gradient for a two-step chain-branching kinetics model  

NASA Astrophysics Data System (ADS)

The evolution from a linear temperature gradient to a detonation is investigated for combustible materials whose chemistry is governed by chain-branching kinetics, using a combination of high-activation-temperature asymptotics and numerical simulations. A two-step chemical model is used, which captures the main properties of detonations in chain-branching fuels. The first step is a thermally neutral induction time, representing chain initiation and branching, which has a temperature-sensitive Arrhenius form of the reaction rate. At the end of the induction time is a transition point where the fuel is instantaneously converted into chain-radicals. The second step is the main exothermic reaction, representing chain termination, assumed to be temperature insensitive. Emphasis is on comparing and contrasting the results with previous studies that used simple one-step kinetics. It is shown that the largest temperature gradient for which a detonation can be successfully ignited depends on the heat release rate of the main reaction. The slower the heat release compared to the initial induction time, the shallower the gradient has to be for successful ignition. For example, when the rate of heat release is moderate or slow on the initial induction time scale, it was found that the path of the transition point marking the end of the induction stage should move supersonically, in which case its speed is determined only by the initial temperature gradient. For steeper gradients such that the transition point propagates subsonically from the outset, the rate of heat release must be very high for a detonation to be ignited. Detonation ignition for the two-step case apparently does not involve the formation of secondary shocks, unlike some cases when one-step kinetics is used.

Sharpe, Gary J.; Short, Mark

2003-02-01

8

Transfer and accumulation of metals in a soil–diet–wood mouse food chain along a metal pollution gradient  

Microsoft Academic Search

We studied the accumulation and transfer of As, Cd, Cu, Pb and Zn in the compartments of a soil–diet–wood mouse (Apodemus sylvaticus) food chain at five sites located along a metal pollution gradient. We observed a clear gradient in metal exposure at increasing distance from the smelter in all compartments of the food chain for the non-essential metals. The gradient

Damien Rogival; Jan Scheirs; Ronny Blust

2007-01-01

9

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

Microsoft Academic Search

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

José Luiz Attayde; Jörgen Ripa

2008-01-01

10

Profiling of a microbial community under confined conditions in a fed-batch garbage decomposer by denaturing gradient gel electrophoresis.  

PubMed

In order to determine the conditions for the maximum performance of a fed-batch composting (FBC) reactor, polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) was used to analyze the microbial communities established under the confined conditions of moisture content and environmental temperature. To evaluate the effects of microbial community structures on the performance of FBC reactors, degradation experiments using small-scale reactors and model waste were conducted under confined environmental conditions. A high degradation rate was observed under a wide range of MC conditions (30-60%) and at higher than usual temperatures (30-50 degrees C). The microbial communities that formed in the experimental FBC reactors were analyzed by DGGE of PCR-amplified 16S rRNA genes. The DGGE banding patterns at the same level as the degradation rates were similar even if the environmental conditions were different. Sequence analysis of the DGGE bands revealed the primary microbes which act in the reactor. PMID:17629695

Horisawa, Sakae; Sakuma, Yoh; Nakamura, Yasunori; Doi, Shuichi

2008-05-01

11

On the relation between gradient flows and the large-deviation principle, with applications to Markov chains and diffusion  

E-print Network

Motivated by the occurrence in rate functions of time-dependent large-deviation principles, we study a class of non-negative functions $\\mathscr L$ that induce a flow, given by $\\mathscr L(\\rho_t,\\dot\\rho_t)=0$. We derive necessary and sufficient conditions for the unique existence of a generalized gradient structure for the induced flow, as well as explicit formulas for the corresponding driving entropy and dissipation functional. In particular, we show how these conditions can be given a probabilistic interpretation when $\\mathscr L$ is associated to the large deviations of a microscopic particle system. Finally, we illustrate the theory for independent Brownian particles with drift, which leads to the entropy-Wasserstein gradient structure, and for independent Markovian particles on a finite state space, which leads to a previously unknown gradient structure.

Alexander Mielke; D. R. Michiel Renger; Mark A. Peletier

2013-12-29

12

Culture-based and denaturing gradient gel electrophoresis analysis of the bacterial community structure from the intestinal tracts of earthworms(Eisenia fetida).  

PubMed

The bacterial communities in the intestinal tracts of earthworm were investigated by culture-dependent and - independent approaches. In total, 72 and 55 pure cultures were isolated from the intestinal tracts of earthworms under aerobic and anaerobic conditions, respectively. Aerobic bacteria were classified as Aeromonas (40%), Bacillus (37%), Photobacterium (10%), Pseudomonas (7%), and Shewanella (6%). Anaerobic bacteria were classified as Aeromonas (52%), Bacillus (27%), Shewanella (12%), Paenibacillus (5%), Clostridium (2%), and Cellulosimicrobium (2%). The dominant microorganisms were Aeromonas and Bacillus species under both aerobic and anaerobic conditions. In all, 39 DNA fragments were identified by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis. Aeromonas sp. was the dominant microorganism in feeds, intestinal tracts, and casts of earthworms. The DGGE band intensity of Aeromonas from feeds, intestinal tracts, and casts of earthworms was 12.8%, 14.7%, and 15.1%, respectively. The other strains identified were Bacillus, Clostridium, Enterobacter, Photobacterium, Pseudomonas, Shewanella, Streptomyces, uncultured Chloroflexi bacterium, and uncultured bacterium. These results suggest that PCR-DGGE analysis was more efficient than the culture-dependent approach for the investigation of bacterial diversity and the identification of unculturable microorganisms. PMID:21952364

Hong, Sung Wook; Kim, In Su; Lee, Ju Sam; Chung, Kun Sub

2011-09-01

13

Heavy metal concentrations in a soil–plant–snail food chain along a terrestrial soil pollution gradient  

Microsoft Academic Search

We investigated concentrations of Zn, Cu, Cd and Pb in the compartments of a soil-plant (Urtica dioica)-snail (Cepaea nemoralis) food chain in four polluted locations in the Biesbosch floodplains, the Netherlands, and two reference locations. Total soil metal concentrations in the polluted locations were 4–20 times higher than those in the reference locations. Positive relationships between the generally low leaf

M. J. M. Notten; A. J. P. Oosthoek; J. Rozema; R. Aerts

2005-01-01

14

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

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

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

2012-01-01

15

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

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

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

16

Traditional Gradient Enhanced Gradient  

E-print Network

Recently deep learning has become a field of attention in machine learning (see [1, 2] for a review). Deep learning mainly focuses on applying a deep neural network to various machine learning applications where there are abundant amount of highdimensional training samples either labeled or unlabeled. Especially, it was shown that deep models are able to extract efficient, hierarchical features. Many recent advances in deep learning have shown performances that are far superior to conventional approaches inmany areas including image and speech recognition as wellas multi-modal learning. One of the most widely used models in deep learning is a deep belief network (DBN) which is built by stacking multiple layers ofrestrictedBoltzmannmachines(RBM).ArestrictedBoltzmannmachinethusconstitutesabasicbuildingblockwithitssimple bipartite structure. However, training even this simplified model has been difficult [6]. Training is sensitive to specific choice of learning hyper-parameters aswell as the datarepresentation. We have recently proposed and are developing learning algorithms that could facilitate learning parameters of RBMs. First of all, we proposed the enhanced gradient update rules that are invariant to flipping of variables in RBMs [5]. As shown in Fig. 1 it effectively makes a gradient of weight parameters with respect to hidden units more orthogonal to each other, hence, leading to a reacher set of features learned by RBMs. Then, the adaptive learning rate adapts the learning rate on-the-fly [5], which otherwise,wouldrequireextensivecross-validation. Thirdly,wehaveshownthatwithasimplere-parameterizationoftheenergy functiontrainingRBMswithGaussianvisiblevariablescouldbecomemucheasier[3]. Lastly,wehavedemonstratedthatabetter

Kyunghyun Cho; Juha Karhunen; Figure Theanglesbetweentheupdatedirectionsfortheweightsofanrbmwithhiddenneurons Whitepixelscorrespon

17

Evaluation of repetitive extragenic palindromic-polymerase chain reaction and denatured gradient gel electrophoresis in identifying Salmonella serotypes isolated from processed turkeys.  

PubMed

The current study was conducted to determine the usefulness of 2 molecular techniques, automated repetitive extragenic palindromic-PCR (REP-PCR) and denaturing gradient gel electrophoresis (DGGE), to identify Salmonella serotypes of poultry origin. Salmonella continues to be a foodborne pathogen of principal concern in the United States. The interspersed conserved repetitive sequence of the bacterial genome and the 16-23S rDNA intergenic spacer region were amplified for REP-PCR and DGGE, respectively. Fifty-four Salmonella isolates from 2 turkey processing plants (A and B) were used for this comparison. Serotypes consisted of Brandenburg, Derby, Hadar, and Typhimurium, with n=6, 21, 12, and 15, respectively. The REP-PCR was fully automated, whereas DGGE was run on an acrylamide gel and the image was captured digitally. Both dendrograms were created using the unweighted pair group method with arithmetic average. There were more variations in percentage similarity in DGGE when compared with REP-PCR. The banding patterns were more distinct and uniform in the REP-PCR group than with DGGE. The results from the REP-PCR were generated within 1 h, whereas the DGGE required approximately 1 d to run. These data suggest that DGGE and REP-PCR are useful tools for identifying Salmonella serotypes isolated from poultry production or processing environments. In addition, REP-PCR is more rapid, may have a higher discriminatory power, but may be less cost-effective than DGGE. However, more research may be needed to validate this argument. Both DGGE and REP-PCR displayed high sensitivity in discriminating among Salmonella serotypes and either method could be considered as an alternative to more expensive and time-consuming conventional antibody-based serotyping methodologies. PMID:20460676

Anderson, P N; Hume, M E; Byrd, J A; Hernandez, C; Stevens, S M; Stringfellow, K; Caldwell, D J

2010-06-01

18

On gradient field theories: gradient magnetostatics and gradient elasticity  

E-print Network

In this work the fundamentals of gradient field theories are presented and reviewed. In particular, the theories of gradient magnetostatics and gradient elasticity are investigated and compared. For gradient magnetostatics, non-singular expressions for the magnetic vector gauge potential, the Biot-Savart law, the Lorentz force and the mutual interaction energy of two electric current loops are derived and discussed. For gradient elasticity, non-singular forms of all dislocation key-formulas (Burgers equation, Mura equation, Peach-Koehler stress equation, Peach-Koehler force equation, and mutual interaction energy of two dislocation loops) are presented. In addition, similarities between an electric current loop and a dislocation loop are pointed out. The obtained fields for both gradient theories are non-singular due to a straightforward and self-consistent regularization.

Lazar, Markus

2014-01-01

19

Food Chains  

NSDL National Science Digital Library

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 ...

Hammond, Ms.

2009-10-21

20

Interactions of Bubbles in a Temperature Gradient  

Microsoft Academic Search

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

Huailiang Wei

1994-01-01

21

Scalar Field Gradient Model  

NSDL National Science Digital Library

The Scalar Field Gradient Model displays the gradient of a scalar field using a numerical approximation to the partial derivatives. This simple teaching model also shows how to display and model scalar and vector fields using the EJS. The EJS Scalar Field Gradient Model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_math_ScalarFieldGradient.jar file will run the program if Java is installed.

Christian, Wolfgang

2009-03-14

22

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

23

GRADIENT CONVERGENCE IN GRADIENT METHODS WITH ERRORS  

E-print Network

/backpropagation method for neural network training, the convergence of which has been the object of much recent analysis [Luo91], [Gai94], [Gri94], [LuT94], [MaS94], [Man93], [Ber95a] (see [BeT96] for our discussion of incre- mental gradient methods and their application to neural network training). The method where the errors wt

Bertsekas, Dimitri

24

Gradient index metamaterials  

Microsoft Academic Search

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

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

2005-01-01

25

A Natural Policy Gradient  

Microsoft Academic Search

We provide a natural gradient method that represents the steepestdescent direction based on the underlying structure of the parameterspace. Although gradient methods cannot make large changesin the values of the parameters, we show that the natural gradientis moving toward choosing a greedy optimal action rather thanjust a better action. These greedy optimal actions are those thatwould be chosen under one

Sham Kakade

2001-01-01

26

Polymer translocation through a gradient channel.  

PubMed

The translocation of polymer through a channel with a gradient interaction between the polymer and the channel is studied. The interaction is expressed by E = E0 + kx, where E0 is the initial potential energy at the entrance, x is the position of the monomer inside the channel, and k is the energy gradient. The mean first passage time ? is calculated by using Fokker-Planck equation for two cases (1) N > L and (2) N < L under the assumption that the diffusion rate D is a constant, here N is the polymer length and L is the length of channel. Results show that there is a minimum of ? at k = k(c) for both cases, and the value kc is dependent on E0 and driving force f. At large f, the scaling relation ? ? N is observed for long polymer chains. But the scaling relation is dependent on the energy gradient k for an unforced driving translocation. PMID:23902014

Zhang, Shuang; Wang, Chao; Sun, Li-Zhen; Li, Chao-Yang; Luo, Meng-Bo

2013-07-28

27

Identification of new Mamu-DRB alleles using DGGE and direct sequencing  

Microsoft Academic Search

Rhesus macaques represent important animal models for biomedical research. The ability to identify macaque major histocompatibility\\u000a complex (Mhc) alleles is crucial for fully understanding these models of autoimmune and infectious disease. Here we describe a rapid and\\u000a unambiguous way to distinguish DRB alleles in the rhesus macaque using the polymerase chain reaction, denaturing gradient gel electrophoresis (DGGE), and direct\\u000a sequencing.

L. A. Knapp; Luis F. Cadavid; Mary E. Eberle; Stuart J. Knechtle; Ronald E. Bontrop; David I. Watkins

1997-01-01

28

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

Microsoft Academic Search

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,

Danilo Ercolini

2004-01-01

29

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

Microsoft Academic Search

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

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

2002-01-01

30

Removal of soluble COD by a biofilm formed on a membrane in a jet loop type membrane bioreactor  

Microsoft Academic Search

The soluble chemical oxygen demand (COD) removal efficiency through a cake layer (biofilm) deposited on the surfaces of a membrane was investigated as a function of biofilm thickness in a jet loop type membrane bioreactor (JL-MBR). The mechanisms for the removal were investigated based on the microbial characteristics of the biofilm.Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) was used to

Jong-Sang Park; Chung-Hak Lee

2005-01-01

31

Molecular analysis of fungal communities of biodegradable plastics in two Japanese soils  

Microsoft Academic Search

This study aimed to elucidate the microbial communities responsible for the decomposition of poly-(?-caprolactone) (PCL), poly-(butylene succinate) (PBS), poly-(butylene succinate and adipate) (PBSA) and poly-lactide (PLA) in two soils using a culture-independent, polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) method with subsequent sequencing of the main DGGE bands. The PCL, PBS and PBSA films were considerably degraded within 50 days at

Masahiro Kamiya; Susumu Asakawa; Makoto Kimura

2007-01-01

32

Bulk soil and rhizosphere bacterial community PCR–DGGE profiles and ?-galactosidase activity as indicators of biological quality in soils contaminated by heavy metals and cultivated with Silene vulgaris (Moench) Garcke  

Microsoft Academic Search

The biological quality of two heavy metal contaminated soils (soil C: Typic Calcixerept, pH 8.3 and soil H: Typic Haploxeraf, pH 7.3) was investigated after growing the metal-tolerant plant Silene vulgaris (Moench) Garcke for two vegetative periods. The activity of the enzyme ?-galactosidase, which is sensitive to the presence of contaminants in soil, and the polymerase chain reaction-denaturing gradient gel

M. J. Martínez-Iñigo; A. Pérez-Sanz; I. Ortiz; J. Alonso; R. Alarcón; P. García; M. C. Lobo

2009-01-01

33

Culture-independent and -dependent methods to investigate the diversity of planktonic bacteria in the northern Bering Sea  

Microsoft Academic Search

Planktonic bacteria are abundant in the Bering Sea. However, very little is known about their diversity and the roles of various\\u000a bacteria in the ocean. Bacterioplankton diversity in the northern Bering Sea was investigated using a combination of molecular\\u000a and cultivation-based methods. Community fingerprint analysis using polymerase chain reaction-denaturing gradient gel electrophoresis\\u000a revealed an apparent difference in the bacterioplankton community

Yinxin Zeng; Yang Zou; Jacqueline M. Grebmeier; Jianfeng He; Tianling Zheng

34

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

Microsoft Academic Search

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

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

2008-01-01

35

Chain Teleportation  

E-print Network

By means of the idea of measurements on the crossed space-time nonlocal observables, we extend the mechanism for the two-way quantum teleportation to the chain teleportation among N spatially separated spin-1/2 systems. Since in the process only the local interactions are used, the microcausality is automatically satisfied.

Chien-er Lee

2004-09-24

36

Markov Chains  

NSDL National Science Digital Library

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.

Smith, David

2002-01-11

37

Electrochemically generated gradients.  

PubMed

This review surveys recent developments in the field of electrochemically generated gradients. The gradual variation of properties, which is a key characteristic of gradients, is of eminent importance in technology, for example, directional wetting, as well as biology, for example, chemotaxis. Electrochemical techniques offer many benefits, such as the generation of dynamic solution and surface gradients, integration with electronics, and compatibility with automation. An overview is given of newly developed methods, from purely electrochemical techniques to the combination of electrochemistry with other methods. Electrochemically fabricated gradients are employed extensively for biological and technological applications, such as high-throughput screening, high-throughput deposition, and device development, all of which are covered herein. Especially promising are developments towards the study and control of dynamic phenomena, such as the directional motion of molecules, droplets, and cells. PMID:24961906

Krabbenborg, Sven O; Huskens, Jurriaan

2014-08-25

38

Gradient Heterogeneous Surface  

NASA Astrophysics Data System (ADS)

The strength of the interfacial interaction and the length scale over which the interaction occurs are two important factors to understand the polymer blends (Lsp 100 nm), diblock copolymers (Lb 30 nm), cell recognition, random heteropolymer, adhesion (ex. Protein, cell) and wettability on a surface. This has important implications in pattern recognition applications, biosensors and random recognition processes. A gradient pattern is produced on a surface with two different surface energies, analogous to a gradient checkerbroad. Indirectly, this would give some insight on random heteropolymer and multifunctional disordered surfaces and biomimetic recognition between polymer and surfaces. To achieve this, a gradient surface is created to vary the lateral size scale correlation of heterogeneity. Two possible routes will be presented to vary different size scale, for example, from micron to nano scale. Then, the gradient surface will be used as a template to vary the surface interaction, i.e. having one domain hydrophilic and hydrophobic the other. And finally, this lateral size scale correlation having two different interaction sites is used to examine the phase separation of polymer blend films, cell recognition, and diblock copolymer films on this gradient heterogenous surface.

Tsai, Irene; Kimura, Masahiro; Lin, Zhiqun; Stockton, Rebecca; Fadeev, Alex; Jacobson, Bruce; Russell, Thomas P.

2002-03-01

39

Markov Chains  

NSDL National Science Digital Library

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

Siegrist, Kyle

2009-03-02

40

High gradient superconducting quadrupoles  

SciTech Connect

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.

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

41

Gradient enhanced spectroscopy  

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

42

High gradient electron guns  

SciTech Connect

Experiments have been conducted to determine peak operating gradients attainable in thermionic electron guns. These tests are part of a study of high-current-density, long-life cathodes suitable for use in high power klystrons. We also investigated the use of chromium oxide coating as a means of inhibiting electronic breakdown across the focus electrode anode gap. Field gradients in excess of 280 kV/cm have been achieved for a gun operating at 240 kV with a beam current of 228 A, at pulse widths of the order of 1 {mu}s. 3 refs., 5 figs.

Fant, K.S.; Caryotakis, G.; Koontz, R.F.; Vlieks, A.E. (Stanford Linear Accelerator Center, Menlo Park, CA (USA)); Miram, G. (Miram (G.), Atherton, CA (USA))

1990-08-01

43

Manipulating the Gradient  

ERIC Educational Resources Information Center

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…

Gaze, Eric C.

2005-01-01

44

Gradient Refractive Index Lenses.  

ERIC Educational Resources Information Center

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)

Morton, N.

1984-01-01

45

Gradient Heterogeneous Surface  

Microsoft Academic Search

The strength of the interfacial interaction and the length scale over which the interaction occurs are two important factors to understand the polymer blends (Lsp 100 nm), diblock copolymers (Lb 30 nm), cell recognition, random heteropolymer, adhesion (ex. Protein, cell) and wettability on a surface. This has important implications in pattern recognition applications, biosensors and random recognition processes. A gradient

Irene Tsai; Masahiro Kimura; Zhiqun Lin; Rebecca Stockton; Alex Fadeev; Bruce Jacobson; Thomas P. Russell

2002-01-01

46

Polymer brush gradients grafted from plasma-polymerized surfaces.  

PubMed

A new method for generating a surface density gradient of polymer chains is presented. A substrate-independent polymer deposition technique was used to coat materials with a chemical gradient based on plasma copolymerization of 1,7-octadiene and allylamine. This provided a uniform chemical gradient to which initiators for atom transfer radical polymerization (ATRP) were immobilized. After surface-initiated atom transfer radical polymerization (SI-ATRP), poly(2-hydroxyethyl methacrylate) (PHEMA) chains were grafted from the surface and the measured thickness profiles provided direct evidence for how surface crowding provides an entropic driving force resulting in chain extension away from the surface. Film thicknesses were found to increase with the position along the gradient surface, reflecting the gradual transition from collapsed to more extended surface-tethered polymer chains as the grafting density increased. The method described is novel in that the approach provides covalent linkages from the polymer coating to the substrate and is not limited to a particular surface chemistry of the starting material. PMID:24967529

Coad, Bryan R; Bilgic, Tugba; Klok, Harm-Anton

2014-07-22

47

Stress-gradient plasticity  

PubMed Central

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

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

2011-01-01

48

Food Chain & Food Web  

NSDL National Science Digital Library

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 ...

B, Ms.

2011-10-27

49

Food Chains and Webs  

NSDL National Science Digital Library

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 ...

Thompson, Ms.

2007-02-21

50

The Food Chain  

NSDL National Science Digital Library

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 ...

Jodi, Miss

2009-07-07

51

Pharmaceutical Supply Chain  

E-print Network

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

Nagurney, Anna

52

Hierarchically deflated conjugate gradient  

E-print Network

We present a multi-level algorithm for the solution of five dimensional chiral fermion formulations, including domain wall and Mobius Fermions. The algorithm operates on the red-black preconditioned Hermitian operator, and directly accelerates conjugate gradients on the normal equations. The coarse grid representation of this matrix is next-to-next-to-next-to-nearest neighbour and multiple algorithmic advances are introduced, which help minimise the overhead of the coarse grid. The treatment of the coarse grids is purely four dimensional, and the bulk of the coarse grid operations are nearest neighbour. The intrinsic cost of most of the coarse grid operations is therefore comparable to those for the Wilson case. We also document the implementation of this algorithm in the BAGEL/Bfm software package and report on the measured performance gains the algorithm brings to simulations at the physical point on IBM BlueGene/Q hardware.

P A Boyle

2014-02-11

53

Scanning temperature gradient focusing.  

PubMed

Temperature gradient focusing (TGF) is a recently developed technique for the simultaneous concentration and electrophoretic separation of ionic analytes in microfluidic channels. One drawback to TGF as it has previously been described is the limited peak capacity; only a small number of analyte peaks (approximately 2-3) can be simultaneously focused and separated. In this paper, we report on a variation of the TGF method whereby the bulk flow rate is varied over time so that a large number of analytes can be sequentially focused, moved past a fixed detection point, and flushed to waste. In addition to improved peak capacity, the detection limits of the scanning TGF method can be adjusted on-the-fly, as needed for different samples. Finally, scanning TGF provides a technique by which high-resolution, high-peak-capacity electrophoretic separations can be performed in simple, straight, and short microfluidic channels. PMID:17037919

Hoebel, Stacey J; Balss, Karin M; Jones, Barbara J; Malliaris, Constantin D; Munson, Matthew S; Vreeland, Wyatt N; Ross, David

2006-10-15

54

Charge gradient microscopy  

PubMed Central

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

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

2014-01-01

55

Charge gradient microscopy.  

PubMed

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

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

2014-05-01

56

Anisotropic Ion Temperature Gradient Instabilities  

Microsoft Academic Search

The effects of anisotropic temperature gradient and collisions on the ion-temperature-gradient (ITG) instabilities have been investigated by using kinetic theory. In the slab limit, the ITG mode is driven unstable by coupling between the transit resonance and ion temperature gradients. While eta_{rm i|} (eta_{rm i| } equiv partiallnT_ {i|}\\/partiallnn, where T_{rm i|} is the perpendicular ion temperature and n is

Hao Song

1994-01-01

57

Gradient optimization and nonlinear control  

NASA Technical Reports Server (NTRS)

The book represents an introduction to computation in control by an iterative, gradient, numerical method, where linearity is not assumed. The general language and approach used are those of elementary functional analysis. The particular gradient method that is emphasized and used is conjugate gradient descent, a well known method exhibiting quadratic convergence while requiring very little more computation than simple steepest descent. Constraints are not dealt with directly, but rather the approach is to introduce them as penalty terms in the criterion. General conjugate gradient descent methods are developed and applied to problems in control.

Hasdorff, L.

1976-01-01

58

Gradient boosting machines, a tutorial  

PubMed Central

Gradient boosting machines are a family of powerful machine-learning techniques that have shown considerable success in a wide range of practical applications. They are highly customizable to the particular needs of the application, like being learned with respect to different loss functions. This article gives a tutorial introduction into the methodology of gradient boosting methods with a strong focus on machine learning aspects of modeling. A theoretical information is complemented with descriptive examples and illustrations which cover all the stages of the gradient boosting model design. Considerations on handling the model complexity are discussed. Three practical examples of gradient boosting applications are presented and comprehensively analyzed. PMID:24409142

Natekin, Alexey; Knoll, Alois

2013-01-01

59

Critical gradient formula for toroidal electron temperature gradient modes  

Microsoft Academic Search

Under certain conditions, the electron heat transport induced 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 consistency (``stiffness''). Here, linear gyrokinetic simulations of toroidal ETG modes in tokamak core and edge plasmas are presented. An algebraic formula for the threshold

F. Jenko; W. Dorland; G. W. Hammett

2001-01-01

60

Geothermal gradient map of Colorado  

SciTech Connect

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.

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

1981-01-01

61

Thermal Gradient Fining of Glass  

NASA Technical Reports Server (NTRS)

Molten glass fined (cleared of bubbles) by heating with suitable temperature gradient, according to preliminary experiments. Temperature gradient produces force on gas bubbles trapped in molten glass pushing bubbles to higher temperature region where they are collected. Concept demonstrated in experiments on Earth and on rocket.

Wilcox, W.

1983-01-01

62

Empirical equation estimates geothermal gradients  

SciTech Connect

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

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

1995-01-02

63

Height and gradient from shading  

Microsoft Academic Search

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

Berthold K. P. Horn

1990-01-01

64

Laser amplifier chain  

DOEpatents

A laser amplifier chain has a plurality of laser amplifiers arranged in a chain to sequentially amplify a low-power signal beam to produce a significantly higher-power output beam. Overall efficiency of such a chain is improved if high-gain, low efficiency amplifiers are placed on the upstream side of the chain where only a very small fraction of the total pumped power is received by the chain and low-gain, high-efficiency amplifiers are placed on the downstream side where a majority of pumping energy is received by the chain.

Hackel, Richard P. (Livermore, CA)

1992-01-01

65

Gradient elution in capillary electrochromatography.  

PubMed

In analogy to pressure-driven gradient techniques in high-performance liquid chromatography, a system has been developed for delivering electroosmotically driven solvent gradients for capillary electrochromatography (CEC). Dynamic gradients with submicroliter per minute flow rates are generated by merging two electroosmotic flows that are regulated by computer-controlled voltages. These flows are delivered by two fused-silica capillary arms attached to a T-connector, where they mix and then flow into a capillary column that has been electrokinetically packed with 3-?m reversed-phase particles. The inlet of one capillary arm is placed in a solution reservoir containing one mobile phase, and the inlet of the other is placed in a second reservoir containing a second mobile phase. Two independent computer-controlled, programmable, high-voltage power supplies (0-50 kV) [Formula: see text] one providing an increasing ramp and the other providing a decreasing ramp [Formula: see text] are used to apply variable high-voltage potentials to the mobile phase reservoirs to regulate the electroosmotic flow in each arm. The ratio of the electroosmotic flow rates between the two arms is changed with time according to the computer-controlled voltages to deliver the required gradient profile to the separation column. Experiments were performed to confirm the composition of the mobile phase during a gradient run and to determine the change of the composition in response to the programmed voltage profile. To demonstrate the performance of electroosmotically driven gradient elution in CEC, a mixture of 16 polycyclic aromatic hydrocarbons was separated in less than 90 min. This gradient technique is expected to be well-suited for generating not only solvent gradients in CEC but also other types of gradients, such as pH and ionic strength gradients, in capillary electrokinetic separations and analyses. PMID:21619344

Yan, C; Dadoo, R; Zare, R N; Rakestraw, D J; Anex, D S

1996-09-01

66

Gradient zone boundary control in salt gradient solar ponds  

DOEpatents

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.

Hull, John R. (Downers Grove, IL)

1984-01-01

67

Serum Free Light Chains  

MedlinePLUS

... website will be limited. Search Help? Serum Free Light Chains Share this page: Was this page helpful? ... top 2. Should everyone have a serum free light chain test? This test is not intended to ...

68

NUFinancials Supply Chain  

E-print Network

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

Shull, Kenneth R.

69

NUFinancials Supply Chain  

E-print Network

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

Shull, Kenneth R.

70

NUFinancials Supply Chain  

E-print Network

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

Shull, Kenneth R.

71

Investigacin Supply chain collaboration  

E-print Network

Centro de Investigación Operativa I-2007-31 Supply chain collaboration Ana Meca and Judith Timmer Hernández de Elche Avda. de la Universidad s/n 03202 Elche (Alicante) #12;Chapter Number Supply Chain and increased competition among firms. Further, more and more products reach the customer through supply chains

Boucherie, Richard J.

72

The Supply Chain & Operations  

E-print Network

The Supply Chain & Operations Management Concentration The Manning School of Business www- tional business, management, management information systems, marketing and supply chain and operations. From the largest corporations to the smallest retailers, all companies are a part of a supply chain

Massachusetts at Lowell, University of

73

NUFinancials Supply Chain  

E-print Network

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

Shull, Kenneth R.

74

NUFinancials Supply Chain  

E-print Network

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

Shull, Kenneth R.

75

NUFinancials Supply Chain  

E-print Network

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

Shull, Kenneth R.

76

NUFinancials Supply Chain  

E-print Network

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

Shull, Kenneth R.

77

NUFinancials Supply Chain  

E-print Network

NUFinancials Supply Chain FMS801 & 803 Purchasing Glossary 03/31/2010 © 2010 Northwestern's school/department to whom the Shopper assigns their iBuyNU shopping cart. #12;NUFinancials Supply Chain to the requisition so it can be approved by all approvers. Bid Documentation See BD-1 #12;NUFinancials Supply Chain

Shull, Kenneth R.

78

Food Chain Game  

NSDL National Science Digital Library

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.

Science, Lawrence H.

1979-01-01

79

Shaping Morphogen Gradients by Proteoglycans  

PubMed Central

During development, secreted morphogens such as Wnt, Hedgehog (Hh), and BMP emit from their producing cells in a morphogenetic field, and specify different cell fates in a direct concentration-dependent manner. Understanding how morphogens form their concentration gradients to pattern tissues has been a central issue in developmental biology. Various experimental studies from Drosophila have led to several models to explain the formation of morphogen gradients. Over the past decade, one of the main findings in this field is the characterization of heparan sulfate proteoglycan (HSPG) as an essential regulator for morphogen gradient formation. Genetic and cell biological studies have showed that HSPGs can regulate morphogen activities at various steps including control of morphogen movement, signaling, and intracellular trafficking. Here, we review these data, highlighting recent findings that reveal mechanistic roles of HSPGs in controlling morphogen gradient formation. PMID:20066107

Yan, Dong; Lin, Xinhua

2009-01-01

80

Height and Gradient from Shading  

E-print Network

The method described here for recovering the shape of a surface from a shaded image can deal with complex, wrinkled surfaces. Integrability can be enforced easily because both surface height and gradient are represented. ...

Horn, Berthold K.P.

1989-05-01

81

Porosity gradients in marine sediments  

E-print Network

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... 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...

Mahmood, Khalid

2012-06-07

82

Electron temperature gradient driven turbulence  

Microsoft Academic Search

Collisionless electron-temperature-gradient-driven (ETG) turbulence in toroidal geometry is studied via nonlinear numerical simulations. To this aim, two massively parallel, fully gyrokinetic Vlasov codes are used, both including electromagnetic effects. Somewhat surprisingly, and unlike in the analogous case of ion-temperature-gradient-driven (ITG) turbulence, we find that the turbulent electron heat flux is significantly underpredicted by simple mixing length estimates in a certain

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

2000-01-01

83

Correlated Knowledge Gradients: Example alternatives  

E-print Network

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

Keinan, Alon

84

Gradient characterization in magnetic resonance imaging  

E-print Network

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

Cheng, Joseph Yitan

2007-01-01

85

40 CFR 230.25 - Salinity gradients.  

Code of Federal Regulations, 2010 CFR

...24 2010-07-01 2010-07-01 false Salinity gradients. 230.25 Section 230.25 ...Characteristics of the Aquatic Ecosystem § 230.25 Salinity gradients. (a) Salinity gradients form where salt water from the...

2010-07-01

86

40 CFR 230.25 - Salinity gradients.  

Code of Federal Regulations, 2011 CFR

...25 2011-07-01 2011-07-01 false Salinity gradients. 230.25 Section 230.25 ...Characteristics of the Aquatic Ecosystem § 230.25 Salinity gradients. (a) Salinity gradients form where salt water from the...

2011-07-01

87

Dynamic thermal gradient gas chromatography.  

PubMed

The use of negative axial thermal gradients in gas chromatography (TGGC) has intrigued chromatographers since the early 1950s because of the dramatic narrowing of analyte bands and concomitant raised expectations for improving resolving power. However, technical difficulties experienced in construction of TGGC instrumentation and control of the temperature along the column have made its implementation and, hence, detailed study difficult. In this work, we describe a TGGC system capable of rapidly producing and varying thermal gradient profiles by simultaneous use of resistive heating and convective cooling. Heating and cooling rates as high as 1200 and 2500°C/min, respectively, allowed the creation of dynamic temperature gradients. The separation characteristics of TGGC with dynamically changing temperature gradients are demonstrated. A gradient velocity of 2.22cm/s provided repetitive separations every 45s, and injection band widths of 45s duration were transformed into approximately 1-s peak widths. Peak tailing for basic compounds was nearly eliminated. Dynamic TGGC allows unique control over separations, oftentimes improving resolution and detection signal-to-noise. Thermally controlled elution in TGGC holds great promise for performing smart separations in which the separation time window is most efficiently utilized, and optimized separations can be quickly achieved. Rapid adjustment of relative compound elution can be used to greatly reduce GC method development time. PMID:23845755

Contreras, Jesse A; Wang, Anzi; Rockwood, Alan L; Tolley, H Dennis; Lee, Milton L

2013-08-01

88

Neuron Chain Tag  

NSDL National Science Digital Library

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.

Yoshioka, Melissa

2009-01-01

89

Sequential chain registry  

US Patent & Trademark Office Database

Systems and methods are disclosed for tracking an object as it traverses a sequential chain. The relationships between the object, its movement through space and time, and the entities associated with the object at a discreet point of time are captured by a sequential chain. A unique identifier may be created that is continuously modified as the object traverses the sequential chain. The unique identifier may be used to capture relationship information between the object and its related entities and movements.

2014-08-26

90

Chains of Skyrmions  

E-print Network

Skyrme chains are topologically-nontrivial solutions of the Skyrme model which are (quasi-)periodic in one spatial direction. We report numerical and analytic investigations which show that such solutions exist. Chains of 1-skyrmions are reasonably well approximated both as parallel vortex-antivortex pairs, and in terms of the holonomy of Yang-Mills calorons. As the period increases, the 1-skyrmions clump together, for example giving chains of 2-skyrmions or 4-skyrmions.

Derek Harland; R. S. Ward

2008-07-24

91

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.

92

Safe Chain Saw Operation.  

E-print Network

AND FELLING WEDGES I EXTI~bRJiSHER ~ ~ CHAIN FILING ~ ~ TOOLS FUEL CAN AND FUNNEL SHARP AX Figure 3. Use proper equipment to help you do the job safely. 2 /. SLEDGE HAMMER SHOVEL Special cautions: Electrically-powered chain saws re quire special...: ? Owner's manual in plastic bag ? Gasoline-oil fuel mixture stored in approved con tainer ? Chain oil ? Round file and guide for dressing (sharpening) chain ? Flat file and depth gauge to file the depth guides ? Wrenches to fit all nuts and lugs...

Nelson, Gary S.

1982-01-01

93

Thermalization and temperature distribution in a driven ion chain  

E-print Network

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.

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

2010-01-25

94

Myosin heavy chain isoforms in histochemically defined fiber types of rat muscle  

Microsoft Academic Search

Combined histochemical and biochemical analyses were performed on rat skeletal muscles in order to determine the myosin heavy chain patterns in specific fiber types. Four myosin heavy chain isoforms were separated by gradient polyacrylamide gel electrophoresis of extracts from single fibers and whole muscle homogenates. Their electrophoretic mobility increased in the order HCIIa, HCIIb, and HCI. HCIIa, HCIIb and HCI

A. Termin; R. S. Staron; D. Pette

1989-01-01

95

Gradient waveform synthesis for magnetic propulsion using MRI gradient coils  

Microsoft Academic Search

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

B H Han; S Y Lee

2008-01-01

96

Supply chain risk management  

Microsoft Academic Search

TSMC's risk management department (RM) initiated the first phase of its Supply Chain Risk Management Project in 2003, which included a risk assessment of the company's single-source raw material suppliers. RM worked jointly with the procurement department on this project to assess potential supply chain risks from single-source suppliers located in throughout the world. Suppliers participated in the risk assessment

J. T. Jeng

2004-01-01

97

Supply Chain Management Concentration  

E-print Network

UD Free Elective (300+ level) Non-Business Elective Free Elective Management Courses (21 credits-requisite(s)............................................................Semester(s) Offered Required Course: MGT478............Global Supply Chain Management..............................2Supply Chain Management Concentration While many rules and specific regulations apply to taking

Barnes, Elizabeth A.

98

Policy Gradient Methods for Robotics  

Microsoft Academic Search

The aquisition and improvement of motor skills and control policies for robotics from trial and error is of essential importance if robots should ever leave precisely pre-structured environments. However, to date only few existing reinforcement learning methods have been scaled into the domains of high- dimensional robots such as manipulator, legged or humanoid robots. Policy gradient methods remain one of

Jan Peters; Stefan Schaal

2006-01-01

99

Salt-gradient solar ponds  

NASA Astrophysics Data System (ADS)

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

Neeper, D. A.

100

Improved Gradient Layer Animal Calorimeter  

Microsoft Academic Search

A rapidly responding gradient layer calorimetry system for experimental animals is described. Monitoring of radiant and evaporative components of heat loss is accomplished by separate heat exchange systems that employ thermoelectric heat flowmeters.Calibration and test results with the equipment show the following: The response to energy input is linear in both the radiant heat exchange system (radiant calorimeter thermopile) and

Phillip D. Quattrone

1965-01-01

101

Microbial community dynamics in anaerobic bioreactors and algal tanks treating piggery wastewater  

Microsoft Academic Search

Integrated biosystem is becoming a major aspect of wastewater management practice. Microbial communities in piggery wastewater\\u000a sampled from anaerobic (thermophilic and mesophilic) and aerobic digesters (algal tanks) during waste remediation were analyzed\\u000a by culture-independent techniques based on polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). The\\u000a use of Muyzer's 314F-GC, 518R bacterial primers, and archaeal A934F, 1309R primers followed by partial

Sayali S. Patil; Martin S. Kumar; Andrew S. Ball

2010-01-01

102

Bt corn plants and their straw have no apparent impact on soil microbial communities  

Microsoft Academic Search

Polymerase chain reaction–denaturing gradient gel electrophoresis (PCR–DGGE) and sequences of the 16S and 18S rRNA genes were\\u000a used to access the effects of actively growing Bacillus thuringiensis (Bt) corn Pioneer 34B24 and Nongda 1246*1482, and plant straw (leaves plus stalks) of Bt hybrid Pioneer 34B24 and Nongda 61 on soil bacterial and fungal communities. Two-way indicator species analysis (TWINSPAN®),\\u000a and

Fengxiao Tan; Jianwu Wang; Yuanjiao Feng; Guoliang Chi; Hailan Kong; Huifeng Qiu; Suling Wei

2010-01-01

103

Corrosion in a temperature gradient  

SciTech Connect

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.

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

2003-01-01

104

Supply Chain Risk by Structure  

Microsoft Academic Search

A number of trends have made the supply chain more vulnerable and supply chain risk management has become a research area of its own. The aim of this paper is to describe the effect of supply chain structure to supply chain risk transfer and risk control. According to the characteristics of supply chain structure, the risk transfer processes can be

Cunlu Zhang; Peiqing Huang

2006-01-01

105

Magnetic Resonance Imaging with Composite (Dual) Gradients  

PubMed Central

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

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

2009-01-01

106

Carbon and Oxygen Galactic Gradients  

NASA Astrophysics Data System (ADS)

A chemical evolution model of the Galaxy has been computed to reproduce the O/H gradients from Galactic HII regions. This model solves the C enrichment problem because it fits the C/H and C/O gradients and the C and O histories of the solar vicinity. The model is based on C yields dependent on metallicity (Z) owing to stellar winds. The C yields of massive stars (MS) increase with Z and those of low and intermediate mass stars (LIMS) decrease with Z. An important result is that the fraction of carbon in the interstellar medium (ISM) due to MS and LIMS is strongly dependent on Z of the ISM, therefore, that fraction depends on time and on the Galactocentric distance. At present and in the solar vicinity about half of the C in the interstellar medium has been produced by MS and half by LIMS.

Carigi, L.; Peimbert, M.; Esteban, C.; García-Rojas, J.

2006-06-01

107

Improving supply chain resilience  

E-print Network

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 ...

Leung, Elsa Hiu Man

2009-01-01

108

European supply chain study  

E-print Network

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 ...

Puri, Mohitkumar

2009-01-01

109

Heavy Chain Diseases  

MedlinePLUS

... Multimedia Table Index In This Topic Blood Disorders Plasma Cell Disorders Heavy Chain Diseases Back to Top ... Blood Vessels Platelet Disorders White Blood Cell Disorders Plasma Cell Disorders Leukemias Lymphomas Myeloproliferative Disorders Spleen Disorders ...

110

Supply chain dynamics  

E-print Network

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 ...

Barbosa, Ricardo Wagner Lopes, 1976-

2003-01-01

111

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.

112

Atomic Chain Electronics  

NASA Technical Reports Server (NTRS)

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.

Yamada, Toshishige; Saini, Subhash (Technical Monitor)

1998-01-01

113

SCIENCE MATTERS KEY CHAIN  

NSDL National Science Digital Library

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

1900-01-01

114

Food Chains: Nature's Restaurant  

NSDL National Science Digital Library

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.

Schaffran, Jane

115

Food Chains and Webs  

NSDL National Science Digital Library

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.

Council, Biotechnology A.

2012-06-26

116

Writing on polymer chains.  

PubMed

Synthetic polymer materials are currently limited by their inability to store information in their chains, unlike some well-characterized biopolymers. Nucleic acids store and transmit genetic information, and amino acids encode the complex tridimensional structures and functions within proteins. To confer similar properties on synthetic materials, researchers must develop"writing" mechanisms, facile chemical pathways that allow control over the primary structure of synthetic polymer chains. The most obvious way to control the primary structure is to connect monomer units one-by-one in a given order using iterative chemistry. Although such synthesis strategies are commonly used to produce peptides and nucleic acids, they produce limited yields and are much slower than natural polymerization mechanisms. An alternative strategy would be to use multiblock copolymers with blocks that have specified sequences. In this case, however, the basic storage element is not a single molecular unit, but a longer block composed of several repeating units. However, the synthesis of multiblock copolymers is long and tedious. Therefore, researchers will need to develop other strategies for writing information onto polymer chains. In this Account, I describe our recent progress in the development of sequence controlled polymerization methods. Although our research focuses on different strategies, we have emphasized sequence-regulation in chain-growth polymerization processes. Chain-growth polymerizations, particularly radical polymerization, are very convenient methods for synthesizing polymers. However, in most cases, such approaches do not lead to controlled monomer sequences. During the last five years, we have shown that controlled/living chain-growth polymerization mechanisms offer interesting advantages for sequence regulation. In such mechanisms, the chains form gradually over time, and therefore the primary structure can be tuned by using time-controlled monomer additions. For example, the addition of small amounts of acceptor comonomers, such as N-substituted maleimides, during the controlled radical polymerization of a large excess of donor monomer, such as styrene, allows the writing of information onto polymer chains in a robust manner. Even with these advances, this strategy is not perfect and presents some of the drawbacks of chain-growth polymerizations, such as the formation of chain-to-chain sequence defects. On the other hand, this approach is experimentally easy, rapid, scalable, and very versatile. PMID:23886072

Lutz, Jean-François

2013-11-19

117

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.

2013-07-09

118

Thermal gradients in round TMF specimens  

Microsoft Academic Search

The effect of radial thermal gradients in thermomechanical fatigue (TMF) specimens on the number of cycles to failure has been studied. Different radial gradients were obtained by asymmetric placement of the specimen in the coil. And by using different induction heating frequencies. The different induction frequencies give different depths of penetration for the heat. A special thermal gradient specimen was

Henrik C. M. Andersson; Eva Sjöström

2008-01-01

119

Origin of Color Gradients in Elliptical Galaxies  

NASA Astrophysics Data System (ADS)

Stellar populations in an elliptical galaxy are not uniform. Colors in a galaxy become bluer with an increasing radius. Such a radial gradient of color has been naively assumed to originate from a metallicity variation inside a galaxy. However, this interpretation is premature because stellar populations of either higher metallicity or older age can make the galaxy redder. This problem, which is called the age-metallicity degeneracy, must be solved to know the origin of the gradients observed in elliptical galaxies. An evolution of a color gradient is a key to break the degeneracy, because the evolution of the gradient caused by a metallicity gradient is predicted to be different from that by an age gradient. Here, the model color gradients were constructed using a population synthesis model so as to reproduce color gradients in local ellipticals either by a metallicity gradient or by an age gradient, and the predicted evolutions were compared with the color gradient observed in the distant ellipticals in the HDF-N. Since the HDF-N is considered to represent field environment, we extended our study to cluster ellipticals using the HST archival deep imaging data of the distant clusters at redshifts from 0.37 to 0.56. Our studies indicate that the primary origin of the color gradients in an elliptical galaxy is not an age but a stellar metallicity, and this result does not depend on galaxy environment.

Tamura, Naoyuki

2004-02-01

120

MBA Supply Chain Case Competition Center for Supply Chain Management  

E-print Network

MBA Supply Chain Case Competition Center for Supply Chain Management February 1, 2013 1:00 ­ 4:00 p their skills in analyzing a real-world supply chain management case. Provide a chance for sponsoring companies of the Rutgers Center for Supply Chain Management to get to know top talent from RBS. The Schedule The case

Lin, Xiaodong

121

Pulsed Field Gradient Selection in Two-Dimensional Magic Angle Spinning NMR Spectroscopy of Dipolar Solids  

NASA Astrophysics Data System (ADS)

The utility of gradient selection in MAS spectroscopy of dipolar solids is explored in two examples. In the first, rotor-synchronized gradients of appropriate strength and duration are applied to select 1H double-quantum coherences. The resulting DQ MAS spectrum of adamantane is compared with that acquired by the corresponding phase-cycling technique. As a second example, a 1H 2D exchange MAS experiment is performed on an elastomer sample. In this experiment, a gradient is applied to remove undesired coherences that would otherwise distort the spectrum for short mixing times. The diagonal-peak intensities in the resulting spectrum show a linear decrease with increasing mixing time indicating cross-relaxation by slow chain motions as the relevant process. Both types of experiments demonstrate the potential of gradient-selection techniques for MAS spectroscopy of dipolar solids.

Fritzhanns, Tilo; Hafner, Siegfried; Demco, Dan E.; Spiess, Hans W.; Laukien, Frank H.

1998-10-01

122

Gradient-index contact lens  

NASA Astrophysics Data System (ADS)

A gradient-index (GRIN) contact lens (CL) is proposed to decrease spherical aberration and to increase the diopter. A plastic radial GRIN rod was successfully obtained by using the vapor-phase diffusion copolymerization technique. The resulting index distribution of the GRIN rod was almost parabolic against the distance from the center axis, and the Delta n value was -0.030. The GRIN CL was prepared by grinding and polishing the rod. It is theoretically and experimentally concluded that using the radial GRIN material can significantly improve the optical properties of CL's.

Koike, Yasuhiro; Asakawa, Akihiko; Wu, Shang Pin; Nihei, Eisuke

1995-08-01

123

Temperature Gradient in Hall Thrusters  

SciTech Connect

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.

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

2003-11-24

124

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

E-print Network

Density Gradient Stabilization of Electron Temperature Gradient Driven Turbulence in a Spherical 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

Princeton Plasma Physics Laboratory

125

Interim Director Supply Chain Management  

E-print Network

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

Habib, Ayman

126

Welcome from the Supply Chain  

E-print Network

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

Minnesota, University of

127

The Global Supply Chain Institute  

E-print Network

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

Tennessee, University of

128

Oscillator Chain Model  

NSDL National Science Digital Library

The EJS Oscillator Chain model shows a one-dimensional linear array of coupled harmonic oscillators with fixed ends. This model can be used to study the propagation of waves in a continuous medium and the vibrational modes of a crystalline lattice. The Ejs model shown here contains 31 coupled oscillators equally spaced within the interval [0, 2 pi] with fixed ends. Ejs Oscillator Chain model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_mech_osc_OscillatorChain.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models for classical mechanics are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Christian, Wolfgang

2008-11-06

129

Oscillator Chain JS Model  

NSDL National Science Digital Library

The EJS Oscillator Chain model shows a one-dimensional linear array of coupled harmonic oscillators with fixed ends. This model can be used to study the propagation of waves in a continuous medium and the vibrational modes of a crystalline lattice. The Ejs model shown here contains 31 coupled oscillators equally spaced within the interval [0, 2 pi] with fixed ends. The Oscillator Chain JS Model was developed using the Easy Java Simulations (Ejs) version 5. It is distributed as a ready-to-run html page and requires only a browser with JavaScript support.

Christian, Wolfgang

2013-08-25

130

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.

131

Natural Radioactive Decay Chains  

NASA Astrophysics Data System (ADS)

Shell effects on nuclear stability have created an island of relative stability for nuclides near A = 230-240 and Z = 90-92. Three nuclides, 232Th, 238U, and 235U, have half-lives long enough for significant amounts to have survived since the heavy elements in the Earth's crust were created. When one of these nuclides decays, it starts a journey that ends with an isotope of lead (Z = 82, A ? 208). The predominant steps in this journey are ? and ? decays, so that each of the long-lived parents heads a distinct chain. Each chain, as well as a fourth one that is extinct, is described.

Griffin, H. C.

132

Supply chain risk management  

Microsoft Academic Search

This article presents a secondary analysis of the literature, supplemented by case studies to determine if large companies increase their exposure to risk by having small- and medium-size enterprises (SMEs) as partners in business critical positions in the supply chain, and to make recommendations concerning best practice. A framework defining the information systems (IS) environment is used to structure the

Peter Finch

2004-01-01

133

Atwood's Heavy Chain  

ERIC Educational Resources Information Center

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

Beeken, Paul

2011-01-01

134

Dynamics of the Dorsal morphogen gradient  

PubMed Central

The dorsoventral (DV) patterning of the Drosophila embryo depends on the nuclear localization gradient of Dorsal (Dl), a protein related to the mammalian NF-?B transcription factors. Current understanding of how the Dl gradient works has been derived from studies of its transcriptional interpretation, but the gradient itself has not been quantified. In particular, it is not known whether the Dl gradient is stable or dynamic during the DV patterning of the embryo. To address this question, we developed a mathematical model of the Dl gradient and constrained its parameters by experimental data. Based on our computational analysis, we predict that the Dl gradient is dynamic and, to a first approximation, can be described as a concentration profile with increasing amplitude and constant shape. These time-dependent properties of the Dl gradient are different from those of the Bicoid and MAPK phosphorylation gradients, which pattern the anterior and terminal regions of the embryo. Specifically, the gradient of the nuclear levels of Bicoid is stable, whereas the pattern of MAPK phosphorylation changes in both shape and amplitude. We attribute these striking differences in the dynamics of maternal morphogen gradients to the differences in the initial conditions and chemistries of the anterior, DV, and terminal systems. PMID:19996178

Kanodia, Jitendra S.; Rikhy, Richa; Kim, Yoosik; Lund, Viktor K.; DeLotto, Robert; Lippincott-Schwartz, Jennifer; Shvartsman, Stanislav Y.

2009-01-01

135

Glass-transition temperature gradient in nanocomposites: evidence from nuclear magnetic resonance and differential scanning calorimetry.  

PubMed

The slowing-down of the dynamics of a polymer chain near a surface has been observed for many years now. Here we show that the behavior of model nanocomposites can be quantitatively described with a gradient of glass-transition temperature. We describe with a single parameter-the range of this gradient-the temperature and solvent effect on the spin relaxation dynamics. Moreover, this parameter allows a quantitative description of the nanocomposite calorimetric response from the one of the bulk polymer. PMID:22401088

Papon, Aurélie; Montes, Hélène; Hanafi, Mohamed; Lequeux, François; Guy, Laurent; Saalwächter, Kay

2012-02-10

136

Cosmic ray gradients in the heliosphere  

NASA Technical Reports Server (NTRS)

Early estimates of the radial gradient made in the inner heliosphere are presented. In a discussion of discoveries in the outer heliosphere, consideration is given to low radial gradients and nonradial transport, the identification of different components, the large-scale organization of the heliospheric magnetic field, propagating modulation features, and latitude gradients. Current estimates of the spatial distribution of the cosmic ray intensity are presented as well.

Fillius, Walker

1989-01-01

137

Further exploration of Galactic disk abundance gradients  

NASA Astrophysics Data System (ADS)

We examine the abundance gradient in the Milky Way disk via homogeneously determined data for 124 Galactic planetary nebulae (PNe). We present recent results from a detailed regression analysis of the O gradient. With O, Ne, S, Cl, and Ar available and a range of galactocentric distance (R g ) from 0.9 to 21 kpc, we present additional exploration of the disk radial gradient by statistically analyzing a series of short segments of increasing average R g .

Milingo, Jackie B.; Henry, Richard B. C.; Kwitter, Karen B.; Balick, Bruce

2012-08-01

138

Second order gradient ascent pulse engineering  

NASA Astrophysics Data System (ADS)

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.

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

2011-10-01

139

Temperature gradient sensor based on CNT composite  

NASA Astrophysics Data System (ADS)

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.

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

2014-08-01

140

Heat conduction in one-dimensional aperiodic quantum Ising chains.  

PubMed

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

Li, Wenjuan; Tong, Peiqing

2011-03-01

141

Cross-contact chain  

NASA Technical Reports Server (NTRS)

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.

Lieneweg, Udo (Inventor)

1988-01-01

142

Geothermal gradients of Alberta in Western Canada  

SciTech Connect

-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.

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

1984-01-01

143

Nanofiber Scaffold Gradients for Interfacial Tissue Engineering  

PubMed Central

We have designed a 2-spinnerette device that can directly electrospin nanofiber scaffolds containing a gradient in composition that can be used to engineer interfacial tissues such as ligament and tendon. Two types of nanofibers are simultaneously electrospun in an overlapping pattern to create a nonwoven mat of nanofibers containing a composition gradient. The approach is an advance over previous methods due to its versatility - gradients can be formed from any materials that can be electrospun. A dye was used to characterize the 2-spinnerette approach and applicability to tissue engineering was demonstrated by fabricating nanofibers with gradients in amorphous calcium phosphate nanoparticles (nACP). Adhesion and proliferation of osteogenic cells (MC3T3-E1 murine pre-osteoblasts) on gradients was enhanced on the regions of the gradients that contained higher nACP content yielding a graded osteoblast response. Since increases in soluble calcium and phosphate ions stimulate osteoblast function, we measured their release and observed significant release from nanofibers containing nACP. The nanofiber-nACP gradients fabricated herein can be applied to generate tissues with osteoblast gradients such as ligaments or tendons. In conclusion, these results introduce a versatile approach for fabricating nanofiber gradients that can have application for engineering graded tissues. PMID:22286209

Ramalingam, Murugan; Young, Marian F.; Thomas, Vinoy; Sun, Limin; Chow, Laurence C.; Tison, Christopher K.; Chatterjee, Kaushik; Miles, William C.; Simon, Carl G.

2012-01-01

144

The innovation value chain.  

PubMed

The challenges of coming up with fresh ideas and realizing profits from them are different for every company. One firm may excel at finding good ideas but may have weak systems for bringing them to market. Another organization may have a terrific process for funding and rolling out new products and services but a shortage of concepts to develop. In this article, Hansen and Birkinshaw caution executives against using the latest and greatest innovation approaches and tools without understanding the unique deficiencies in their companies' innovation systems. They offer a framework for evaluating innovation performance: the innovation value chain. It comprises the three main phases of innovation (idea generation, conversion, and diffusion) as well as the critical activities performed during those phases (looking for ideas inside your unit; looking for them in other units; looking for them externally; selecting ideas; funding them; and promoting and spreading ideas companywide). Using this framework, managers get an end-to-end view of their innovation efforts. They can pinpoint their weakest links and tailor innovation best practices appropriately to strengthen those links. Companies typically succumb to one of three broad "weakest-link" scenarios. They are idea poor, conversion poor, or diffusion poor. The article looks at the ways smart companies - including Intuit, P&G, Sara Lee, Shell, and Siemens- modify the best innovation practices and apply them to address those organizations' individual needs and flaws. The authors warn that adopting the chain-based view of innovation requires new measures of what can be delivered by each link in the chain. The approach also entails new roles for employees "external scouts" and "internal evangelists," for example. Indeed, in their search for new hires, companies should seek out those candidates who can help address particular weaknesses in the innovation value chain. PMID:17580654

Hansen, Morten T; Birkinshaw, Julian

2007-06-01

145

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.

146

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.

2010-10-05

147

Bucket chain excavator  

SciTech Connect

A machine is described for excavating, elevating and loading material comprising: a main frame having forward and rearward ends; undercarriage means having forward and rearward movement capability for supporting said main frame; a transverse axle rigidly located with respect to said main frame at the forward end thereof; rotating means mounted on said axle so as to extend cantilever wider than any other part of said machine for excavating and for discharging excavated material rearward at an elevated position; chain drive means mounted inwardly on said axle for driving said rotating means and for digging and elevating a portion of the width of a path so that said rotating means and said chain drive means together dig a path wider than any other part of said machine; conveyor means located behind said rotating means for receiving and taking away all material excavated by said chain drive means and said rotating means and conveying said material rearwardly to a material delivery position; and adjustment means for raising and lowering said rotating means relative to said undercarriage.

Bryan, J.F. Jr.

1993-07-20

148

Improved Scalable Hash Chain Traversal  

Microsoft Academic Search

\\u000a Yaron Sella recently proposed a scalable version of Jakobsson’s algorithm to traverse a hash chain of size n. Given the hash chain and a computation limit m (k=m+1 and b=kÖ{n}b=\\\\sqrt[k]{n}), Sella’s algorithm traverses the hash chain using a total of kb memory. We improve the memory usage to k(b-1). Because efficient hash chain traversal algorithms are aimed at devices with

Sung-ryul Kim

2003-01-01

149

The Supply Chain Management Processes  

Microsoft Academic Search

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

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

2001-01-01

150

Supply Chain Enter PO Receipt  

E-print Network

PeopleSoft Supply Chain FMS805 Enter PO Receipt 08/11/2008 © 2008 Northwestern University FMS805 1 Support Center at 847-491-HELP (4357) or email consultant@northwestern.edu #12;PeopleSoft Supply Chain FMS Received to receive remaining items. #12;PeopleSoft Supply Chain FMS805 Enter PO Receipt 08/11/2008 © 2008

Shull, Kenneth R.

151

Polymerase Chain Reaction Assay and  

E-print Network

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

Paris-Sud XI, Université de

152

Density Gradient Dependent Helicon Modes  

NASA Astrophysics Data System (ADS)

Radially localized helicon modes have been proposed to provide a fuller description of helicon discharges over a wide span of operating conditions and gas types [1]. These plasma modes could be of vital importance to the VASIMR engine. They depend on a radial density gradient and appear to operate over a range of frequencies inaccessible to traditional helicon discharges. Our work focuses on confirming experimentally the existence and properties of these helicon modes in Argon, Helium, and Hydrogen. We investigate the density profile, power deposition, wavefields, and dispersion relation of the new helicon modes which differ substantially from the properties of the traditional helicon plasma. We are using a set of dual half-turn helical antennas driven at 13.56 MHz. Our diagnostics includes a system for monitoring the plasma impedance, a set of Langmuir probes, a set of magnetic probes, as well as sensors for monitoring the pressure and DC magnetic field. *Work supported in part by Advanced Space Propulsion Lab, Johnson Space Center, NASA [1] B. N. Breizman and A. V. Arefiev, Phys. Rev. 84, 3863 (2000)

Panevsky, Martin; Bengtson, Roger

2002-11-01

153

An Inexpensive Digital Gradient Controller for HPLC.  

ERIC Educational Resources Information Center

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.…

Brady, James E.; Carr, Peter W.

1983-01-01

154

Hierarchical gradient methods for nonlinear LSQ problems  

Microsoft Academic Search

The idea of hierarchical gradient methods for optimization is considered. It is shown that the proposed approach provides powerful means to cope with some global convergence problems characteristic of the classical gradient methods. Concerning global convergence problems, four topics are addressed: The “detour” effect, the problem of multiscale models, the problem of highly ill-conditioned objective functions, and the problem of

M. F. Berger

1992-01-01

155

Strain gradient plasticity: Theory and experiment  

Microsoft Academic Search

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

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

1994-01-01

156

A reformulation of strain gradient plasticity  

Microsoft Academic Search

A class of phenomenological strain gradient plasticity theories is formulated to accommodate more than one material length parameter. The objective is a generalization of the classical J2 flow theory of plasticity to account for strain gradient effects that emerge in deformation phenomena at the micron scale. A special case involves a single length parameter and is of similar form to

N. A. Fleck; J. W. Hutchinson

2001-01-01

157

Microinstabilities in weak density gradient tokamak systems  

SciTech Connect

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.

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

1986-04-01

158

Bremsstrahlung from Plasma with Strong Temperature Gradient  

Microsoft Academic Search

Bremsstrahlung from unmagnetized plasma with temperature gradient and density gradient length scales short compared with the radiation wavelength is considered. A test particle formalism suitable for analyzing this problem has been developed.^1 The formalism reproduces the predictions of Kirchoff's law in the case of an abruptly bounded uniform temperature plasma, and reduces to the equation of radiative heat transfer in

H. L. Rappaport

2004-01-01

159

CARS thermometry in high temperature gradients  

Microsoft Academic Search

CARS is an effective non-intrusive technique for measuring gas temperature in combustion environments. In regions of high temperature gradient, however, the CARS signal is complicated by contributions from gas at different temperature. This paper examines theoretically the uncertainty associated with CARS thermometry in steep temperature gradients. In addition, the work compares the temperature predicted from CARS with the adiabatic mixed

J. Y. Zhu; D. Dunn-Rankin

1993-01-01

160

Gradient based image registration using importance sampling  

Microsoft Academic Search

Analytical gradient based non-rigid image registration meth- ods, using intensity based similarity measures (e.g. mutual in- formation), have proven to be capable of accurately handling many types of deformations. While their versatility is largely in part to their high degrees of freedom, the computation of the gradient of the similarity measure with respect to the many warp parameters becomes very

Roshni R. Bhagalia; Jeffrey A. Fessler; Boklye Kim

2006-01-01

161

Gradient Vector Flow Fast Geometric Active Contours  

E-print Network

for boundary extraction. To this end, we combine the geodesic active contour flow [3] and the gradient vector Terms--Boundary extraction, image segmentation, gradient vector flow, geodesic active contours, level-level geometric components such as lines, circles, and ellipses [15]. Point Distribution Models: A step further

Paragios, Nikos

162

Partial pressure gradients due to temperature gradients in a mixture of reactive gases  

Microsoft Academic Search

Partial pressure gradients due to temperature gradients in a mixture of reactive gases, limit the possible use of sensors. Problems arise when a partial pressure sensor is subjected to a temperature, different from that of the sample. A model is proposed that allows the calculation of the partial pressure distributions in a temperature gradient. Experiments conducted using O2, H2, and

O. Porat; I. Riess

1992-01-01

163

Approximate error conjugation gradient minimization methods  

DOEpatents

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.

Kallman, Jeffrey S

2013-05-21

164

Assessment of Microbial Populations Dynamics in a Blue Cheese by Culturing and Denaturing Gradient Gel Electrophoresis  

Microsoft Academic Search

The composition and development of microbial population during the manufacture and ripening of two batches of a blue-veined\\u000a cheese was examined by culturing and polymerase chain reaction (PCR) denaturing gradient gel electrophoresis (DGGE) (PCR–DGGE).\\u000a Nine selective and\\/or differential media were used to track the cultivable populations of total and indicator microbial groups.\\u000a For PCR–DGGE, the V3 hyper variable region of

Ángel Alegría; Renata González; Mario Díaz; Baltasar Mayo

2011-01-01

165

Radiology's value chain.  

PubMed

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

Enzmann, Dieter R

2012-04-01

166

Induced population gradients in galaxy merger remnants  

NASA Technical Reports Server (NTRS)

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

Mihos, J. Christopher; Hernquist, Lars

1994-01-01

167

Quantum estimation of magnetic-field gradient using W-state  

NASA Astrophysics Data System (ADS)

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

Ng, H. T.; Kim, K.

2014-11-01

168

Regulation of the photosynthetic electron transport chain.  

PubMed

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

Ott; Clarke; Birks; Johnson

1999-08-12

169

Microfluidic gradient PCR (MG-PCR): a new method for microfluidic DNA amplification.  

PubMed

This study develops a new microfluidic DNA amplification strategy for executing parallel DNA amplification in the microfluidic gradient polymerase chain reaction (MG-PCR) device. The developed temperature gradient microfluidic system is generated by using an innovative fin design. The device mainly consists of modular thermally conductive copper flake which is attached onto a finned aluminum heat sink with a small fan. In our microfluidic temperature gradient prototype, a non-linear temperature gradient is produced along the gradient direction. On the copper flake of length 45 mm, width 40 mm and thickness 4 mm, the temperature gradient easily spans the range from 97 to 52 degrees Celsius. By making full use of the hot (90-97 degrees Celsius) and cold (60-70 degrees Celsius) regions on the temperature gradient device, the parallel, two-temperature MG-PCR amplification is feasible. As a demonstration, the MG-PCR from three parallel reactions of 112-bp Escherichia coli DNA fragment is performed in a continuous-flow format, in which the flow of the PCR reagent in the closed loop is induced by the buoyancy-driven nature convection. Although the prototype is not optimized, the MG-PCR amplification can be completed in less than 45 min. However, the MG-PCR thermocycler presented herein can be further scaled-down, and thus the amplification times and reagent consumption can be further reduced. In addition, the currently developed temperature gradient technology can be applied onto other continuous-flow MG-PCR systems or used for other analytical purposes such as parallel and combination measurements, and fluorescent melting curve analysis. PMID:19757072

Zhang, Chunsun; Xing, Da

2010-02-01

170

[Amyloid light chain amyloidosis].  

PubMed

Primary amyloid light chain (AL) amyloidosis is the most common and most aggressive form of systemic amyloidosis. In AL amyloidosis, the products of free light chains (FLCs) of monoclonal amyloidogenic plasma cells deposit in the heart, kidneys, liver, gastrointestinal tract, autonomic nerve systems, and soft tissues, consequently leading to progressive disability and organ failure. Tissue biopsy (mainly bone marrow and subcutaneous fat aspirate) staining with Congo red to demonstrate amyloid deposits is required for diagnosis. Autologous stem cell transplant is the preferred treatment method; however, only 25% of patients are eligible. Non-transplant candidates can be offered melphalan-dexamethasone or clinical trials of new agents (thalidomide, lenalidomide, and bortezomib), which have been shown to improve survival. N-terminal pro-brain natriuretic peptide (>1800 ng/l), cardiac troponin T (>0.025 ng/ml), and dFLC (>180 mg/l) are known poor prognostic factors. Late diagnosis remains a major obstacle for initiating effective therapy while organ dysfunction is still recoverable. PMID:24998824

Suzuki, Kenshi; Shimizu, Toshiko

2014-07-01

171

Gradient composite materials for artificial intervertebral discs.  

PubMed

Composites with the gradient of Young's modulus constitute a new group of biomimetic materials which affect the proper distribution of stresses between the implant and the bone. The aim of this article was to examine the mechanical properties of gradient materials based on carbon fibre-polysulfone composite, and to compare them to the properties of a natural intervertebral disc. Gradient properties were provided by different orientation or volume fraction of carbon fibres in particular layers of composites. The results obtained during in vitro tests displayed a good durability of the gradient materials put under long-term static load. However, the configuration based on a change in the volume fraction of the fibres seems more advantageous than the one based on a change of the fibres' orientation. The materials under study were designed to replace the intervertebral disc. The effect of Young's modulus of the material layers on the stress distribution between the tissue and the implant was analyzed and the biomimetic character of the gradient composites was stated. Unlike gradient materials, the pure polysulfone and the non-gradient composite resulted in the stress concentration in the region of nucleus pulposus, which is highly disadvantageous and does not occur in the stress distribution of natural intervertebral discs. PMID:25306938

Migacz, Katarzyna; Ch?opek, Jan; Morawska-Chochó?, Anna; Ambroziak, Maciej

2014-01-01

172

BIOMIMETIC GRADIENT HYDROGELS FOR TISSUE ENGINEERING  

PubMed Central

During tissue morphogenesis and homeostasis, cells experience various signals in their environments, including gradients of physical and chemical cues. Spatial and temporal gradients regulate various cell behaviours such as proliferation, migration, and differentiation during development, inflammation, wound healing, and cancer. One of the goals of functional tissue engineering is to create microenvironments that mimic the cellular and tissue complexity found in vivo by incorporating physical, chemical, temporal, and spatial gradients within engineered three-dimensional (3D) scaffolds. Hydrogels are ideal materials for 3D tissue scaffolds that mimic the extracellular matrix (ECM). Various techniques from material science, microscale engineering, and microfluidics are used to synthesise biomimetic hydrogels with encapsulated cells and tailored microenvironments. In particular, a host of methods exist to incorporate micrometer to centimetre scale chemical and physical gradients within hydrogels to mimic the cellular cues found in vivo. In this review, we draw on specific biological examples to motivate hydrogel gradients as tools for studying cell–material interactions. We provide a brief overview of techniques to generate gradient hydrogels and showcase their use to study particular cell behaviours in two-dimensional (2D) and 3D environments. We conclude by summarizing the current and future trends in gradient hydrogels and cell–material interactions in context with the long-term goals of tissue engineering. PMID:21874065

Sant, Shilpa; Hancock, Matthew J.; Donnelly, Joseph P.; Iyer, Dharini; Khademhosseini, Ali

2011-01-01

173

Background gradient suppression in stimulated echo NMR diffusion studies using magic pulsed field gradient ratios.  

PubMed

By evaluating the spin echo attenuation for a generalized 13-interval PFG NMR sequence consisting of pulsed field gradients with four different effective intensities (F(p/r) and G(p/r)), magic pulsed field gradient (MPFG) ratios for the prepare (G(p)/F(p)) and the read (G(r)/F(r)) interval are derived, which suppress the cross term between background field gradients and the pulsed field gradients even in the cases where the background field gradients may change during the z-store interval of the pulse sequence. These MPFG ratios depend only on the timing of the pulsed gradients in the pulse sequence and allow a convenient experimental approach to background gradient suppression in NMR diffusion studies with heterogeneous systems, where the local properties of the (internal) background gradients are often unknown. If the pulsed field gradients are centered in the tau-intervals between the pi and pi/2 rf pulses, these two MPFG ratios coincide to eta=G(p/r)/F(p/r)=1-8/[1+(1/3)(delta/tau)(2)]. Since the width of the pulsed field gradients (delta) is bounded by 0< or =delta< or =tau, eta can only be in the range of 5< or =-eta< or =7. The predicted suppression of the unwanted cross terms is demonstrated experimentally using time-dependent external gradients which are controlled in the NMR experiment as well as spatially dependent internal background gradients generated by the magnetic properties of the sample itself. The theoretical and experimental results confirm and extend the approach of Sun et al. (J. Magn. Reson. 161 (2003) 168), who recently introduced a 13-interval type PFG NMR sequence with two asymmetric pulsed magnetic field gradients suitable to suppress unwanted cross terms with spatially dependent background field gradients. PMID:14729028

Galvosas, Petrik; Stallmach, Frank; Kärger, Jörg

2004-02-01

174

SUPPLY CHAIN MANAGEMENT CONCENTRATION FOR UNDERGRADUATES  

E-print Network

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

Salama, Khaled

175

Doping of Semiconducting Atomic Chains  

NASA Technical Reports Server (NTRS)

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.

Toshishige, Yamada; Kutler, Paul (Technical Monitor)

1997-01-01

176

A chain of evolution algebras  

E-print Network

We introduce a notion of chain of evolution algebras. The sequence of matrices of the structural constants for this chain of evolution algebras satisfies an analogue of Chapman-Kolmogorov equation. We give several examples (time homogenous, time non-homogenous, periodic, etc.) of such chains. For a periodic chain of evolution algebras we construct a continuum set of non-isomorphic evolution algebras and show that the corresponding discrete time chain of evolution algebras is dense in the set. We obtain a criteria for an evolution algebra to be baric and give a concept of a property transition. For several chains of evolution algebras we describe the behavior of the baric property depending on the time. For a chain of evolution algebras given by the matrix of a two-state evolution we define a baric property controller function and under some conditions on this controller we prove that the chain is not baric almost surely (with respect to Lebesgue measure). We also construct examples of the almost surely baric chains of evolution algebras. We show that there are chains of evolution algebras such that if it has a unique (resp. infinitely many) absolute nilpotent element at a fixed time, then it has unique (resp. infinitely many) absolute nilpotent element any time; also there are chains of evolution algebras which have not such property. For an example of two dimensional chain of evolution algebras we give the full set of idempotent elements and show that for some values of parameters the number of idempotent elements does not depend on time, but for other values of parameters there is a critical time $t_{c}$ such that the chain has only two idempotent elements if time $t\\geq t_{\\rm c}$ and it has four idempotent elements if time $t< t_{\\rm c}$

J. M. Casas; M. Ladra; U. A. Rozikov

2010-03-29

177

Pyrolysis of Di-tertiary Butyl Peroxide: Temperature Gradients and Chain Contribution to the Rate  

Microsoft Academic Search

An investigation of the pyrolysis of di-tertiary butyl peroxide over the range 27–130 mm Hg pressure and 130–160°C has shown that the experimental stoichiometry is 3.0 rather than the previously reported 2.9. Trace amounts of t-BuOH (0.5 to 1.0%), isobutylene oxide (1–2%) and t-BuOMe (0.02%) have been identified as well as biacetonyl and small amounts of other ketones. By using

Leslie Batt; Sidney W. Benson

1962-01-01

178

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

E-print Network

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

Lin, Xiaodong

179

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

E-print Network

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

Fork, Richard

180

Kinetics of Electron Transfer through the Respiratory Chain Qusheng Jin and Craig M. Bethke  

E-print Network

the mitochondrial inner membrane or prokaryotic cytoplasmic membrane. The rate expression, derived considering dependence of flux on electrical potential gradient, its hyperbolic dependence on substrate concen- tration chain in the inner mem- brane of mitochondria and cytoplasmic membrane of many bacteria conserves energy

Bethke, Craig

181

Polymerase chain reaction  

SciTech Connect

This paper discusses the polymerase chain reaction (PCR) an in-vitro method of amplifying DNA sequences. Beginning with DNA of any origin- bacterial, viral, plant, or animal- PCR can increase the amount of a DNA sequence hundreds of millions to billions of times. The procedure can amplify a targeted sequence even when it makes up less than one part in a million of the total initial sample. PCR is an enzymatic process that is carried out in discrete cycles of amplification, each of which can double the amount of target DNA in the sample. Thus, n cycles can produce 2{sup n} times as much target as was present to begin with. This paper discusses how PCR has had an impact on molecular biology, human genetics, infectious and genetic disease diagnosis, forensic science, and evolutionary biology.

Arnhelm, N. (Univ. of Southern California, CA (US)); Levenson, C.H. (Cetus Corp. (US))

1990-10-01

182

Statistical Methods in Markov Chains  

Microsoft Academic Search

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

Patrick Billingsley

1961-01-01

183

A DYNAMIC GRADIENT APPROACH TO PARETO OPTIMIZATION ...  

E-print Network

Jun 5, 2014 ... ative games; sparse optimization; inverse problems; gradient methods. ... whence the decentralized features of this dynamic. ...... point of the dynamics (see Figures 1 and 2), making the process realistic in engineering and human .... multi-

2014-06-06

184

Continuous spray forming of functionally gradient materials  

SciTech Connect

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.

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

1995-12-01

185

Coreless Concept for High Gradient Induction Cell  

SciTech Connect

An induction linac cell for a high gradient is discussed. The proposed solid state coreless approach for the induction linac topology (SLIM{reg_sign}) is based on nanosecond mode operation. This mode may have an acceleration gradient comparable with gradients of rf- accelerator structures. The discussed induction system has the high electric efficiency. The key elements are a solid state semiconductor switch and a high electric density dielectric with a thin section length. The energy in the induction system is storied in the magnetic field. The nanosecond current break-up produces the high voltage. The induced voltage is used for acceleration. This manner of an operation allows the use of low voltage elements in the booster part and achieves a high accelerating gradient. The proposed topology was tested in POP (proof of principle) experiments.

Krasnykh, Anatoly; /SLAC

2008-01-07

186

Sound focusing by gradient index sonic lenses  

E-print Network

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.

Alfonso Climente; Daniel Torrent; Jose Sanchez-Dehesa

2010-06-14

187

Sound focusing by gradient index sonic lenses  

E-print Network

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.

Climente, Alfonso; Sanchez-Dehesa, Jose

2010-01-01

188

Sound focusing by gradient index sonic lenses  

NASA Astrophysics Data System (ADS)

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.

Climente, Alfonso; Torrent, Daniel; Sánchez-Dehesa, José

2010-09-01

189

Topics in Dynamic Meteorology: Pressure Gradient Force  

NSDL National Science Digital Library

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.

Comet

2013-03-12

190

Electron heat transport down steep temperature gradients  

Microsoft Academic Search

Electron heat transport is studied by numerically solving the Fokker-Planck equation, with a spherical harmonic representation of the distribution function. The first two terms (fâ, fâ) suffice, even in steep temperature gradients. Deviations from the Spitzer-Haerm law appear for lambda\\/L\\/sub T\\/ ((mean free path)\\/(temperature gradient length))> or approx. =0.01, as a result of non-Maxwellian fâ. For lambda\\/L\\/sub T\\/> or approx.

J. P. Matte; J. Virmont

1982-01-01

191

Electrode temperature gradients in the electroslag process  

Microsoft Academic Search

A self-consistent model for electrode temperature gradients in an ESR process has been tested against experimental results.\\u000a The results indicate that when melting steels in the electrode and mold sizes studied, the electrode material spends approximately\\u000a 30 sec in the temperature gradient 1000‡C to the melting point. It is suggested that this would lead to a significant nonequilibrium\\u000a retention of

A. Mitchell; S. Joshi; J. Cameron

1971-01-01

192

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

NASA Technical Reports Server (NTRS)

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.

Tian, Pu; Smith, Grant D.

2003-01-01

193

Interplay between transport barriers and density gradient  

SciTech Connect

The present paper addresses two critical issues of zonal flows: the evidence of control parameters of their driving term, namely the Reynolds stress, and how they back-react on turbulence and transport. Kinetic nonlinear simulations are performed with the GYSELA code [V. Grandgirard et al., J. Comput. Phys. (to be published)], which models the slab branch of the ion temperature gradient driven instability in the four-dimensional drift-kinetic regime. First, the numerical results show that the gradient of the guiding center density, related to the general potential vorticity, is stabilizing both linearly, by increasing the instability threshold, and nonlinearly, by activating zonal flows. Accordingly, the Reynolds stress is found to scale like L{sub {omega}}{sup -2} in the quasilinear regime, L{sub {omega}} being the gradient length of the guiding center density. Second, the local temperature gradient appears to increase linearly with the curvature of the zonal flows, regardless of its sign. Such behavior agrees qualitatively with a perturbative theory. Indeed, while linear eigenmodes are localized at the maximum of the temperature gradient in the absence of zonal flows, they tend to be expelled if both exhibit a maximum at the same location. In this case, the reduction mechanism of the turbulent transport results from the ability of large zonal flow curvatures to render strong temperature gradients stable with respect to perturbations.

Sarazin, Y.; Grandgirard, V.; Dif-Pradalier, G.; Garbet, X.; Ghendrih, Ph. [Association Euratom-CEA, CEA/DSM/DRFC Centre de Cadarache, 13108 Saint-Paul-Lez-Durance (France)

2006-09-15

194

Impact of supply chain linkages on supply chain performance  

Microsoft Academic Search

Purpose – The purpose of this paper is to examine the impact of supply chain linkages on supply chain performance (SCP). It aims to define and describe linkage constructs for power, benefits, and risk reduction and develop multi-item scales for their measurement. It also aims to assess the relationships of the linkages with SCP. Design\\/methodology\\/approach – A total of 145

Pamela J. Zelbst; Kenneth W. Green Jr.; Victor E. Sower; Pedro Reyes

2009-01-01

195

Supply chain risk in an uncertain global supply chain environment  

Microsoft Academic Search

The breadth and scope of supply chain risks have broadened significantly in recent years. Even prior to the 2001 terrorist attacks, the creep of risks and uncertainties were widening with increased globalization, widening political reach by leading countries, and the rise of market producing and consuming economies. This article raises some essential supply chain questions as well as some that

Jack Barry

2004-01-01

196

Chain Migration of Neuronal Precursors  

Microsoft Academic Search

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

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

1996-01-01

197

Verifying the Hanging Chain Model  

ERIC Educational Resources Information Center

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…

Karls, Michael A.

2013-01-01

198

Practical Markov Chain Monte Carlo  

Microsoft Academic Search

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

Charles J. Geyer

1992-01-01

199

Best Practices in Supply Chain  

E-print Network

's dynamic market. #1) Begin with your customers. The goal of a sup- ply chain is to deliver products, and on the development of innovative prod- ucts,services and business processes. Allowing the mar- ket demand to drive a winning strategy and a business model that utilizes best practices in supply chain management (SCM

200

Acoustic Chains in Acousmatic Music  

Microsoft Academic Search

The notion of 'acoustic chains' will be posited. It will be argued that 'acoustic chains' link certain acousmatic works at what Denis Smalley terms the 'indicative listening mode' through their common 'affordances' - a term originally used by James Gibson to interpret visual culture and adapted by Luke Windsor to acousmatic music. It will be contended that the listener to

Mathew Adkins

201

Triple-A supply chain performance  

Microsoft Academic Search

Purpose – In 2004 Lee proposed that successful supply chains must be agile, adaptable, and aligned and described those chains as “Triple-A” supply chains. The purpose of this paper is to theorize a Triple-A supply chain performance model that incorporates Triple-A supply chain status as antecedent to supply chain performance and supply chain performance as antecedent to organizational performance. Design\\/methodology\\/approach

G. Dwayne Whitten; Kenneth W. Green Jr; Pamela J. Zelbst

2012-01-01

202

Quantum reservoirs with ion chains  

E-print Network

Ion chains are promising platforms for studying and simulating quantum reservoirs. One interesting feature is that their vibrational modes can mediate entanglement between two objects which are coupled through the vibrational modes of the chain. In this work we analyse entanglement between the transverse vibrations of two heavy impurity defects embedded in an ion chain, which is generated by the coupling with the chain vibrations. We verify general scaling properties of the defects dynamics and demonstrate that entanglement between the defects can be a stationary feature of these dynamics. We then analyse entanglement in chains composed of tens of ions and propose a measurement scheme which allows one to verify the existence of the predicted entangled state.

B. G. Taketani; T. Fogarty; E. Kajari; Th. Busch; Giovanna Morigi

2014-02-06

203

Agent Simulation of Chain Bankruptcy  

E-print Network

We have conducted an agent-based simulation of chain bankruptcy. The propagation of credit risk on a network, i.e., chain bankruptcy, is the key to nderstanding largesized bankruptcies. In our model, decrease of revenue by the loss of accounts payable is modeled by an interaction term, and bankruptcy is defined as a capital deficit. Model parameters were estimated using financial data for 1,077 listed Japanese firms. Simulations of chain bankruptcy on the real transaction network consisting of those 1,077 firms were made with the estimated model parameters. Given an initial bankrupt firm, a list of chain bankrupt firms was obtained. This model can be used to detect high-risk links in a transaction network, for the management of chain bankruptcy.

Ikeda, Yuichi; Souma, Wataru; Aoyama, Hideaki; Iyetomi, Hiroshi

2007-01-01

204

Age and metallicity gradients in fossil ellipticals  

NASA Astrophysics Data System (ADS)

Context. Fossil galaxy groups are speculated to be old and highly evolved systems of galaxies that formed early in the universe and had enough time to deplete their L? galaxies through successive mergers of member galaxies, building up one massive central elliptical, but retaining the group X-ray halo. Aims: Considering that fossils are the remnants of mergers in ordinary groups, the merger history of the progenitor group is expected to be imprinted in the fossil central galaxy (FCG). We present for the first time radial gradients of single-stellar population (SSP) ages and metallicites in a sample of FCGs to constrain their formation scenario. We also measure line-strength gradients for the strongest absorption features in these galaxies. Methods: We took deep spectra with the long-slit spectrograph ISIS at the William Herschel Telescope (WHT) for six FCGs. The obtained spectra are fit with Pegase HR SSP models within the full-spectrum fitting package ULySS yielding SSP ages and metallicities of the stellar populations. We measure radial gradients of SSP ages and metallicities along the major axes. Lick indices are measured for the strongest absorption features to determine line-strength gradients and compare with the full-spectrum fitting results. Results: Our sample comprises some of the most massive galaxies in the universe exhibiting an average central velocity dispersion of ?0 = 271 ± 28 km s-1. Metallicity gradients are throughout negative with comparatively flat slopes of ?[Fe/H] = -0.19 ± 0.08 while age gradients are found to be insignificant (?age = 0.00 ± 0.05). All FCGs lie on the fundamental plane, suggesting that they are virialised systems. We find that gradient strengths and central metallicities are similar to those found in cluster ellipticals of similar mass. Conclusions: The comparatively flat metallicity gradients with respect to those predicted by monolithic collapse (?Z = -0.5) suggest that fossils are indeed the result of multiple major mergers. Hence we conclude that fossils are not "failed groups" that formed with a top-heavy luminosity function. The low scatter of gradient slopes suggests a similar merging history for all galaxies in our sample. Figures 3 and 4 are available in electronic form at http://www.aanda.orgReduced spectra are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/553/A99

Eigenthaler, P.; Zeilinger, W. W.

2013-05-01

205

Performance optimization in electric field gradient focusing.  

PubMed

Electric field gradient focusing (EFGF) is a technique used to simultaneously separate and concentrate biomacromolecules, such as proteins, based on the opposing forces of an electric field gradient and a hydrodynamic flow. Recently, we reported EFGF devices fabricated completely from copolymers functionalized with poly(ethylene glycol), which display excellent resistance to protein adsorption. However, the previous devices did not provide the predicted linear electric field gradient and stable current. To improve performance, Tris-HCl buffer that was previously doped in the hydrogel was replaced with a phosphate buffer containing a salt (i.e., potassium chloride, KCl) with high mobility ions. The new devices exhibited stable current, good reproducibility, and a linear electric field distribution in agreement with the shaped gradient region design due to improved ion transport in the hydrogel. The field gradient was calculated based on theory to be approximately 5.76 V/cm(2) for R-phycoerythrin when the applied voltage was 500 V. The effect of EFGF separation channel dimensions was also investigated; a narrower focused band was achieved in a smaller diameter channel. The relationship between the bandwidth and channel diameter is consistent with theory. Three model proteins were resolved in an EFGF channel of this design. The improved device demonstrated 14,000-fold concentration of a protein sample (from 2 ng/mL to 27 microg/mL). PMID:19081099

Sun, Xuefei; Farnsworth, Paul B; Tolley, H Dennis; Warnick, Karl F; Woolley, Adam T; Lee, Milton L

2009-01-01

206

Gradient algorithm applied to laboratory quantum control  

SciTech Connect

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.

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

2009-05-15

207

Gradient algorithm applied to laboratory quantum control  

NASA Astrophysics Data System (ADS)

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.

Roslund, Jonathan; Rabitz, Herschel

2009-05-01

208

Importance of Ionospheric Gradients for error Correction  

NASA Astrophysics Data System (ADS)

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.

Ravula, Ramprasad

209

GradientShop: A gradient-domain optimization framework for image and video filtering  

Microsoft Academic Search

We present an optimization framework for exploring gradient-domain solutions for image and video processing. The proposed framework unifies many of the key ideas in the gradient-domain literature under a single optimization formulation. Our hope is that this generalized framework will allow the reader to quickly gain a general understanding of the field and contribute new ideas of their own. We

Pravin Bhat; C. Lawrence Zitnick; Michael Cohen; Brian Curless

2010-01-01

210

Color gradients in galactic spheroids. II - Gradient as a function of luminosity and morphology  

Microsoft Academic Search

Photoelectric surface photometry is presented for the stellar spheroids of galaxies covering a wide range in both luminosity and morphological type. Combining these data with those previously published has yielded a large, uniform sample of stellar spheroids with accurately measured color gradients. It is found that the bulges of spiral galaxies tend to have considerably larger color gradients perpendicular to

A. Wirth; R. Shaw

1983-01-01

211

Marine microbes see a sea of gradients.  

PubMed

Marine bacteria influence Earth's environmental dynamics in fundamental ways by controlling the biogeochemistry and productivity of the oceans. These large-scale consequences result from the combined effect of countless interactions occurring at the level of the individual cells. At these small scales, the ocean is surprisingly heterogeneous, and microbes experience an environment of pervasive and dynamic chemical and physical gradients. Many species actively exploit this heterogeneity, while others rely on gradient-independent adaptations. This is an exciting time to explore this frontier of oceanography, but understanding microbial behavior and competition in the context of the water column's microarchitecture calls for new ecological frameworks, such as a microbial optimal foraging theory, to determine the relevant trade-offs and global consequences of microbial life in a sea of gradients. PMID:23118182

Stocker, Roman

2012-11-01

212

Relativistic klystrons for high-gradient accelerators  

SciTech Connect

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.

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

213

Shadowgraph Study of Gradient Driven Fluctuations  

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

214

Recovering gradients from sparsely observed functional data  

PubMed Central

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

Loez-Pintado, Sara; McKeague, Ian W.

2013-01-01

215

Substrate curvature gradient drives rapid droplet motion.  

PubMed

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

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

2014-07-11

216

Improving supply chain resilience by multi-stage supply chain  

E-print Network

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 ...

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

2009-01-01

217

Improve supply chain resilience by multi-stage supply chain  

E-print Network

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 ...

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

2009-01-01

218

METALLICITY GRADIENTS OF THICK DISK DWARF STARS  

SciTech Connect

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.

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

219

GOCE Gravity Gradients in an Orbital Aspect  

NASA Astrophysics Data System (ADS)

This work includes a study of the possibility of the Gravity Field and Steady-State Ocean Circulation Explorer Mission (GOCE) satellite orbit improvement using gravity gradient observations. The orbit improvement is performed by a dedicated software package, called Orbital Computation System (OCS), which is based on the classical least squares method. In an iterative process, the corrections to the initial state vector components of the satellite are estimated, using dynamical models describing gravitational perturbations. An important component implemented in the OCS package is the Cowell 8th order numerical integration procedure, which directly generates the satellite orbit. Taking into account the GOCE real and simulated gravity gradients, different variants of solution of the orbit improvement process were obtained. The improved orbits were compared to the GOCE reference orbits (Precise Science Orbits of the GOCE satellite delivered by the European Space Agency) using the root mean squares (RMS) of the differences between the satellite positions on the improved orbits and on the reference ones. The comparison between the improved orbits and the reference ones was performed with respect to the inertial reference frame (IRF) at J2000.0 epoch. RMS values for the solutions based on the real gravity gradients measurements are at a level of hundreds of kilometers and more. This means that the orbit improvement using the real gravity gradients is ineffective. However, all solutions using the simulated gravity gradients, have RMS values below the threshold determined by RMS values for the computed orbits (without the improvement). The most promising results have been achieved here in the case of improving of short orbital arcs with the lengths from a few to tens of minutes. For these short arcs, RMS values reach the level of centimeters, which is close to the accuracy of Precise Science Orbit of GOCE satellite. Additional research have provided requirements for the effective orbit improvement in terms of the accuracy and spectral content of measured gravity gradients.

Bobojc, Andrzej; Drozyner, Andrzej

2014-05-01

220

Decoherence in quantum Markov chains  

NASA Astrophysics Data System (ADS)

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 classical hitting time. The detection problem under decoherence is also solved with quadratic speedup in this range.

Santos, Raqueline Azevedo Medeiros; Portugal, Renato; Fragoso, Marcelo Dutra

2013-11-01

221

Relativistic klystron research for high gradient accelerators  

SciTech Connect

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.

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

222

Time changes in gradient and observed winds  

E-print Network

equations foz the components of the grauient wind. The x- and y-components of the gradient wind equation can be derived by taking the dot product of Eq. (1) by i and by j, respectively. The compo- nents of the gradient wind in the x- and y... finite- difference technique (Carnahan et al. , 1964) over the grid system (Fig. 1, p. 13). 2) Trajectory curvature Curvature is defined as k= ~~ where Q is the angle between ds the trajectory and the x axis, and s is a distance along the trajec...

Carlson, Ronald Dale

2012-06-07

223

Sonic gradient index lens for aqueous applications  

NASA Astrophysics Data System (ADS)

We study the acoustic scattering properties of a phononic crystal designed to behave as a gradient index lens in water, both experimentally and theoretically. The gradient index lens is designed using a square lattice of stainless-steel cylinders based on a multiple scattering approach in the homogenization limit. We experimentally demonstrate that the lens follows the graded index equations derived for optics by mapping the pressure intensity generated from a spherical source at 20 kHz. We find good agreement between the experimental result and theoretical modeling based on multiple scattering theory.

Martin, Theodore P.; Nicholas, Michael; Orris, Gregory J.; Cai, Liang-Wu; Torrent, Daniel; Sánchez-Dehesa, José

2010-09-01

224

17 GHz High Gradient Accelerator Research  

SciTech Connect

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.

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

2013-07-10

225

Stiffness gradient in the crystalline lens  

Microsoft Academic Search

Background  While the overall stiffness of the lens has been measured in a number of studies, the knowledge about the stiffness distribution\\u000a within the lens is still limited. The purpose of this study was to determine the stiffness gradient in the human crystalline\\u000a lens. A secondary purpose was to determine whether the stiffness gradient depends on age.\\u000a \\u000a \\u000a \\u000a Methods  The local dynamic stiffness

Henk A. Weeber; Gabriele Eckert; Wolfgang Pechhold

2007-01-01

226

Short wavelength ion temperature gradient turbulence  

SciTech Connect

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.

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

227

Acceleration gradient of a plasma wakefield accelerator  

NASA Astrophysics Data System (ADS)

The phase velocity of the wakefield waves is identical to the electron beam velocity. A theoretical analysis indicates that the acceleration gradient of the wakefield accelerator normalized by the wave breaking amplitude is K0(?)/K1(?), where K0(?) and K1(?) are the modified Bessel functions of the second kind of order zero and one, respectively and ? is the beam parameter representing the beam intensity. It is also shown that the beam density must be considerably higher than the diffuse plasma density for the large radial velocity of plasma electrons that are required for a high acceleration gradient.

Uhm, Han S.

2008-02-01

228

JOHN GLENN CENTER Key Chain  

NSDL National Science Digital Library

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.

1900-01-01

229

Topological Aspects of Differential Chains  

E-print Network

In this paper we investigate the topological properties of the space of differential chains 'B(U) defined on an open subset U of a Riemannian manifold M. We show that 'B(U) is not generally reflexive, identifying a fundamental difference between currents and differential chains. We also give several new brief (though non-constructive) definitions of the space 'B(U), and prove that it is a separable ultrabornological (DF)-space. Differential chains are closed under dual versions of fundamental operators of the Cartan calculus on differential forms. The space has good properties some of which are not exhibited by currents B'(U) or D'(U). For example, chains supported in finitely many points are dense in 'B(U) for all open U in M, but not generally in the strong dual topology of B'(U).

Jenny Harrison; Harrison Pugh

2011-01-02

230

Total supply chain cost model  

E-print Network

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 ...

Wu, Claudia

2005-01-01

231

Effective contracts in supply chains  

E-print Network

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

Shum, Wanhang

2007-01-01

232

Invited Review Supply chain management and advanced  

E-print Network

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

Grossmann, Ignacio E.

233

RECTIFIABILITY OF FLAT CHAINS Brian White  

E-print Network

RECTIFIABILITY OF FLAT CHAINS Brian) that a fin* *ite-mass flat chain over any coefficient group is rectifiable if and only if almos* *t all of its 0- dimensional slices are rectifiable. This implies that every flat chain of

White, Brian

234

Supply Chain Network Design Under Profit Maximization  

E-print Network

Supply Chain Network Design Under Profit Maximization and Oligopolistic Competition Anna Nagurney, Massachusetts 01003 Anna Nagurney Supply Chain Network Design Under Competition #12;Outline Background and Motivation The Supply Chain Network Design Oligopoly Model Special Cases The Algorithm Numerical Examples

Nagurney, Anna

235

Performance analysis of multi-innovation gradient type identification methods  

Microsoft Academic Search

It is well-known that the stochastic gradient (SG) identification algorithm has poor convergence rate. In order to improve the convergence rate, we extend the SG algorithm from the viewpoint of innovation modification and present multi-innovation gradient type identification algorithms, including a multi-innovation stochastic gradient (MISG) algorithm and a multi-innovation forgetting gradient (MIFG) algorithm. Because the multi-innovation gradient type algorithms use

Feng Ding; Tongwen Chen

2007-01-01

236

Gradients of meteorological parameters in convective and nonconvective areas  

E-print Network

. Intensive examination of the gradients observed near squall lines revealed typical gradient patterns and trends in the magnitudes of the gradients associated with convective systems. Height gradients at 850 mb were largest ahead of the storms... in the vicinity of jet streams (Kreitzberg, 1968), or in squall lines (Fankhauser, 1969). It also was determined that direct analysis of geopotential height gradients on a mesoscale basis would not give reliable results because of the random errors in accuracy...

McCown, Milton Samuel

2012-06-07

237

THE KNOWLEDGE GRADIENT The knowledge gradient is the name we apply to the simple idea of measuring the  

E-print Network

at time n, there is a very simple #12;THE KNOWLEDGE GRADIENT FOR INDEPENDENT BELIEFS 91 1 2 3 4 5 Figure 5CHAPTER 5 THE KNOWLEDGE GRADIENT The knowledge gradient is the name we apply to the simple idea of the knowledge gradient in the context of ranking and selection problems, which limits our discussion to offline

Powell, Warren B.

238

Bioenergy supply chains and stakeholders  

Microsoft Academic Search

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

Stefan Gold

2011-01-01

239

Driven Diatomic Oscillator Chain Model  

NSDL National Science Digital Library

The Driven Diatomic Oscillator Chain model displays a one-dimensional diatomic chain of coupled harmonic oscillators with one end driven by an external force and the other end attached to a sliding rod shock absorber. The mass and Stoke's Law damping for the shock absorber are chosen to eliminate reflections at the driving frequency. The frequency of the driving force and the masses can be changed using the text boxes provided. You can change the initial position of the masses by dragging individual oscillators. You can also change the number of oscillators in the chain. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item. The Driven Diatomic Oscillator Chain model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_osc_chains_OscillatorChainDrivenDiatomic.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models for Newtonian mechanics are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Christian, Wolfgang

2008-07-05

240

Escalation of polymerization in a thermal gradient  

PubMed Central

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

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

2013-01-01

241

Magnetic Control of Concentration Gradient in Microgravity  

NASA Technical Reports Server (NTRS)

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.

Leslie, Fred; Ramachandran, Narayanan

2005-01-01

242

Time Rate Gradient Effects and Negative Mass  

Microsoft Academic Search

The Harvard tower Experiment and tests with accurate atomic clocks show that a clock at a high elevation indicates more elapsed time than a clock at a low elevation, both clocks properly measuring time at their locations. This fact mandates that Newton's first law of motion be rewritten to cite impulse balance rather than force balance. Time rate gradient effects

Edmond Miksch

2008-01-01

243

Magnetic Compensation For Gravitational Pressure Gradient  

NASA Technical Reports Server (NTRS)

In technique for partial simulation of low gravitation in diamagnetic or paramagnetic liquid, magnetic field having suitable gradient produces force counteracting gravitational force. Technique makes possible to perform low-gravity experiments on ground, at considerably less expense than in outer space.

Israelsson, Ulf E.; Jackson, Henry W.; Strayer, Donald M.

1993-01-01

244

CONJUGATE GRADIENT WITH SUBSPACE OPTIMIZATION 1 ...  

E-print Network

and Yudin. We apply the algorithm to solve unconstrained strictly convex problems. As with other ... Unlike some other conjugate gradient methods, our algorithm attains a theoretical complexity bound of ...... All the codes for CGSO, Ellipsoid method, and automatic differentiation are written in MATLAB. The Hessian of f1 and ...

2011-12-25

245

Low-complexity demosaicing via multiscale gradients  

NASA Astrophysics Data System (ADS)

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.

Su, Chung-Yen; Chen, Yuh-Horng

2014-01-01

246

On the Convergence of Decentralized Gradient Descent  

E-print Network

The same argument applies to the results .... the arguments in [20, pp. ..... iteration, which generally requires much more computing power that computing a gradient. ..... [13] M.-J. Lai and W. Yin, Augmented l1 and nuclear-norm models with a ...

Kun Yuan, Qing Ling, Wotao Yin

2014-02-07

247

Imbedding Gradient Estimators in Load Balancing Algorithms  

Microsoft Academic Search

The problem of efficiently determining the optimum threshold parameter values for a decentralized load balancing algorithm is investigated. Simulation is used to study the behavior of a gradient-based decentralized optimization algorithm for obtaining good values. The algorithm computes the incremental job delay as a function of changes in both the local and remote job arrival rate. Estimators for these two

Spiridon Pulidas; Donald F. Towsley; John A. Stankovic

1988-01-01

248

Stationary Spatial Temperature Gradient in Gas Chromatography  

Microsoft Academic Search

Imposing an increasing stationary temperature gradient along the length of a gas chromatographic column is proposed as a technique for improving separation. Side outlet ports with control valves would allow the process to have the same advantages of programmed temperature gas chromatography without the disadvantages of temperature transients. For a simple model of gas chromatography the analysis provides expressions for

P. E. Duarte; B. J. McCoy

1982-01-01

249

NEUTRON DIFFUSION IN A TEMPERATURE GRADIENT  

Microsoft Academic Search

The space energy distribution of neutrons diffusing in a source-free, ; nonabsorbing medium possessing a temperature gradient is obtained by solving the ; appropriate Boltzmann equation to a second order approximation using the ; expansion technique of Chipman and Enskog. The medium is assumed to possess a ; locally Maxwellian energy distributlon and the neutron scattering is taken to be

J. R. L. de Ladonchamps; L. M. Grossman

1962-01-01

250

Modeling Neuronal Response to Disparity Gradient  

Microsoft Academic Search

There is a rich literature of physiological studies that a subset of neurons in visual cortices is discriminative of 3-D surface orientation using only the disparity gradient information. One of the physiological models to account for this sensibility to surface slant is the dif-frequency disparity model. Although this model is physiologically plausible, no computational analysis is available to explain how

Lianqing Yu; Zhanyi Hu

2008-01-01

251

Gradient drift eigenmodes in the equatorial electrojet  

Microsoft Academic Search

The problem of kilometer-scale irregularities in the daytime equatorial electrojet is revisited by means of an eigenmode analysis of the gradient drift instability. Realistic physical parameters are used, including the modeled altitude variations of ion and electron collision frequencies and mobilities. The full fourth-order system of two coupled differential equations (each of second order) for the denisty and electrostatic potential

X.-H. Wang; A. Bhattacharjee

1994-01-01

252

Moving Forward: Mechanisms of Chemoattractant Gradient Sensing  

NSDL National Science Digital Library

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.

PhD Jonathan Franca-Koh (Johns Hopkins University School of Medicine Department of Cell Biology); PhD Peter N. Devreotes (Johns Hopkins University School of Medicine Department of Cell Biology)

2004-10-01

253

Geological problems in estimating mantle geothermal gradients  

Microsoft Academic Search

There are two major sets of problems in using mantle-derived ultramafic rocks as direct means of estimating mantle geothermal gradients. The first set includes the uncertainties in defining the appropriate reactions and determining their temperature and pressure depen- dence for a useful range of ultramafic compositions. Currently, no technique offers a fully determined or satisfactory answer, but preliminary estimates offer

D. MecGnrcon

254

Geological problems in estimating mantle geothermal gradients  

Microsoft Academic Search

There are two major sets of problems in using mantle-derived ultramatic rocks as direct means of estimating mantle geothermal gradients. The first set includes the uncertainties in defining the appropriate reactions and determining their temperature and pressure dependence for a useful range of ultramafic compositions. Currently, no technique offers a fully determined or satisfactory answer, but preliminary estimates offer a

I. D. MacGregor; A. R. Basu

1976-01-01

255

Conjugate Directions for Stochastic Gradient Descent ?  

E-print Network

of Computational Science ETH Zurich, Switzerland fschraudo,graepelg@inf.ethz.ch Abstract. The method of conjugate Stochastic Quadratic Optimization Deterministic bowl. The d-dimensional quadratic bowl provides us, nonlinear problems. The gradient here is #22; g = rf(w) = #22; H(w w #3; ). Stochastic bowl. The stochastic

Schraudolph, Nicol N.

256

High Gradient Wakefields in Dielectric Loaded Structures  

Microsoft Academic Search

Dielectric loaded wakefield structures have potential to be used as high gradient accelerator components. Using the high current drive beam at the Argonne Wakefield Accelerator Facility, we employed cylindrical dielectric loaded wakefield structures to generate accelerating fields of up to 86 MV\\/m, at 10 GHz. Short electron bunches of up to 86 nC are used to drive these fields, either

M. E. Conde; S. Antipov; F. Franchini; W. Gai; F. Gao; C. Jing; R. Konecny; W. Liu; J. G. Power; H. Wang; Z. Yusof; LLC Euclid Techlabs

2006-01-01

257

Globally Convergent Hybrid Conjugate Gradient Methods.  

National Technical Information Service (NTIS)

Two hybrid conjugate gradient methods are presented. The first hybrid, Hybrid 1, uses the Polak-Ribiere beta as long as it is positive and less than or equal to that of Fletcher-Reeves and uses the Fletcher-Reeves beta instead, otherwise. This condition e...

D. Touati-ahmed C. Storey

1986-01-01

258

Social Class Gradients and Health in Childhood  

Microsoft Academic Search

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

Barbara Starfield; Judy Robertson; Anne W. Riley

2002-01-01

259

Compositional gradients in natural silicic liquids  

SciTech Connect

Electron microprobe analyses of natural rhyolite glass reveal compositional gradients 10 to 15 ..mu..m wide adjacent to microphenocrysts of plagioclase, alkali feldspar, and magnetite. The presence of such gradients has previously been interpreted as indicative of disequilibrium between liquid and solid. If crystals and liquid are not in compositional equilibrium, temperatures determined from the compositions of coexisting mineral phases might be erroneous. Gradients may be attributed, however, to diffusion controlled crystallization. Because convection of magma is indicated based on a comparison of characteristic transport distances and thickness of compositional boundary layers the model of Tiller et al. (1953) is deemed inappropriate. The microprobe data are consistent with the model of Burton, Prim, and Slichter (1953) in which the liquid is stirred by convection and the crystals are surrounded by a diffusive-advective boundary layer. Computed apparent and equilibrium distribution coefficients for natural rhyolites, combined with published diffusion coefficients for K, yield linear growth rates for feldspars on the order of 7 x 10/sup -7/ cm sec/sup -1/, similar to experimentally determined equilibrium growth rates. The analytical data are consistent with a model of diffusion controlled crystallization in natural silicic liquids, and the utilization of coexisting phases for thermometry remains reasonable in the presence of narrow compositional gradients.

Evans, S.H. Jr.: Nash, W.P.

1980-09-01

260

Density Gradient Columns for Chemical Displays.  

ERIC Educational Resources Information Center

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)

Guenther, William B.

1986-01-01

261

Histograms of Oriented Gradients for Human Detection  

Microsoft Academic Search

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

Navneet Dalal; Bill Triggs

2005-01-01

262

Ballistic dispersion in temperature gradient focusing  

E-print Network

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

Santiago, Juan G.

263

Gradient methods for geophysical image inversions  

SciTech Connect

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.

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

1986-09-01

264

Fourier Accelerated Conjugate Gradient Lattice Gauge Fixing  

E-print Network

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

R. J. Hudspith

2014-05-22

265

Minimum maximum temperature gradient coil design.  

PubMed

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

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

2013-08-01

266

Snakes, shapes, and gradient vector flow  

Microsoft Academic Search

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

Chenyang Xu; Jerry L. Prince

1998-01-01

267

Social class gradients in health during adolescence  

PubMed Central

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

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

2002-01-01

268

Supply chain management in the cement industry .  

E-print Network

??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… (more)

Agudelo, Isabel

2009-01-01

269

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

PubMed Central

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

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

2012-01-01

270

Interhemispheric gradient of hydroxyl in the troposphere  

NASA Astrophysics Data System (ADS)

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.

Patra, P. K.

2013-12-01

271

Phase gradients from intensity gradients: a method of spatial carrier fringe pattern analysis.  

PubMed

In optical measurement, spatial carrier fringe pattern analysis is suitable for measuring dynamic events in real-time. This paper presents a novel technique for analyzing a spatial carrier fringe pattern. It estimates the local phase gradients at a pixel from its neighborhood, by use of statistics of the intensity gradients. Using the estimated phase gradients, the phase map of the fringe pattern is recovered by solving numerical partial derivative equations or using an adaptive spatial carrier phase shifting (SCPS) algorithm. Simulation and experimental results demonstrate this algorithm to be valid. PMID:25321714

Zhang, Ruihua; Guo, Hongwei

2014-09-22

272

Electrochemical fabrication of surface chemical gradients in thiol self-assembled monolayers with tailored work-functions.  

PubMed

The studies on surface chemical gradients are constantly gaining interest both for fundamental studies and for technological implications in materials science, nanofluidics, dewetting, and biological systems. Here we report on a new approach that is very simple and very efficient, to fabricate surface chemical gradients of alkanethiols, which combines electrochemical desorption/partial readsorption, with the withdrawal of the surface from the solution. The gradient is then stabilized by adding a complementary thiol terminated with a hydroxyl group with a chain length comparable to desorbed thiols. This procedure allows us to fabricate a chemical gradient of the wetting properties and the substrate work-function along a few centimeters with a gradient slope higher than 5°/cm. Samples were characterized by cyclic voltammetry during desorption, static contact angle, XPS analysis, and Kelvin probe. Computer simulations based on the Dissipative Particle Dynamics methods were carried out considering a water droplet on a mixed SAM surface. The results help to rationalize the composition of the chemical gradient at different position on the Au surface. PMID:25222857

Fioravanti, Giulia; Lugli, Francesca; Gentili, Denis; Mucciante, Vittoria; Leonardi, Francesca; Pasquali, Luca; Liscio, Andrea; Murgia, Mauro; Zerbetto, Francesco; Cavallini, Massimiliano

2014-10-01

273

Thermocapillary migration of a small chain of bubbles  

NASA Technical Reports Server (NTRS)

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

Wei, Huailiang; Subramanian, R. S.

1993-01-01

274

Characterization of Imaging Gradients in Diffusion Tensor Imaging  

PubMed Central

For obtaining a complete model the diffusion tensor imaging (DTI) method is derived in a new linear algebraic framework in order to include the effect of all of the magnetic field gradients on the MRI signal. In the framework, the coefficient matrix of the estimation equations consists of the sum of three matrices corresponding to diffusion gradients, imaging gradients and the cross–terms between them. The derivations demonstrate that there exists modeling incongruities originating from the choice of phase–encoding gradient magnitude and the read–out gradient affecting the entirety of the signal sample points. These reflect on the cross–terms and the imaging gradient coefficient matrix, revealing the DTI's inadequacy for the inclusion of imaging gradients. The linear algebraic framework mitigates the inadequacy by the utilization of center–symmetric gradient schemes. The observations are verified by the experimental results obtained from an isotropic phantom using several existing diffusion gradient schemes. PMID:20810298

Ozcan, Alpay

2010-01-01

275

Characterization of imaging gradients in diffusion tensor imaging  

NASA Astrophysics Data System (ADS)

For obtaining a complete model the diffusion tensor imaging (DTI) method is derived in a new linear algebraic framework in order to include the effect of all of the magnetic field gradients on the MRI signal. In the framework, the coefficient matrix of the estimation equations consists of the sum of three matrices corresponding to diffusion gradients, imaging gradients and the cross-terms between them. The derivations demonstrate that there exists modeling incongruities originating from the choice of phase-encoding gradient magnitude and the read-out gradient affecting the entirety of the signal sample points. These reflect on the cross-terms and the imaging gradient coefficient matrix, revealing the DTI's inadequacy for the inclusion of imaging gradients. The linear algebraic framework mitigates the inadequacy by the utilization of center-symmetric gradient schemes. The observations are verified by the experimental results obtained from an isotropic phantom using several existing diffusion gradient schemes.

Özcan, Alpay

2010-11-01

276

Characterization of imaging gradients in diffusion tensor imaging.  

PubMed

For obtaining a complete model the diffusion tensor imaging (DTI) method is derived in a new linear algebraic framework in order to include the effect of all of the magnetic field gradients on the MRI signal. In the framework, the coefficient matrix of the estimation equations consists of the sum of three matrices corresponding to diffusion gradients, imaging gradients and the cross-terms between them. The derivations demonstrate that there exists modeling incongruities originating from the choice of phase-encoding gradient magnitude and the read-out gradient affecting the entirety of the signal sample points. These reflect on the cross-terms and the imaging gradient coefficient matrix, revealing the DTI's inadequacy for the inclusion of imaging gradients. The linear algebraic framework mitigates the inadequacy by the utilization of center-symmetric gradient schemes. The observations are verified by the experimental results obtained from an isotropic phantom using several existing diffusion gradient schemes. PMID:20810298

Özcan, Alpay

2010-11-01

277

Iterative Method for Predistortion of MRI Gradient Waveforms  

PubMed Central

The purpose of this work is to correct for transient gradient waveform errors in magnetic resonance imaging (MRI), whether from eddy currents, group delay, or gradient amplifier nonlinearities, which are known to affect image quality. An iterative method is proposed to minimize error between desired and measured gradient waveforms, whose success does not depend on accurate knowledge of the gradient system impulse response. The method was applied to half-pulse excitation for 2-D ultra-short echo time (UTE) imaging on a small animal MRI system and to spiral 2-D excitation on a human 7T MRI system. Predistorted gradient waveforms reduced temporal signal variation caused by excitation gradient trajectory errors in 2-D UTE, and improved the quality of excitation patterns produced by spiral excitation pulses. Iterative gradient predistortion is useful for minimizing transient gradient errors without requiring accurate characterization of the gradient system impulse response. PMID:24801945

Harkins, Kevin D.; Does, Mark D.; Grissom, William A.

2014-01-01

278

Iterative method for predistortion of MRI gradient waveforms.  

PubMed

The purpose of this work is to correct for transient gradient waveform errors in magnetic resonance imaging (MRI), whether from eddy currents, group delay, or gradient amplifier nonlinearities, which are known to affect image quality. An iterative method is proposed to minimize error between desired and measured gradient waveforms, whose success does not depend on accurate knowledge of the gradient system impulse response. The method was applied to half-pulse excitation for 2-D ultra-short echo time (UTE) imaging on a small animal MRI system and to spiral 2-D excitation on a human 7T MRI system. Predistorted gradient waveforms reduced temporal signal variation caused by excitation gradient trajectory errors in 2-D UTE, and improved the quality of excitation patterns produced by spiral excitation pulses. Iterative gradient predistortion is useful for minimizing transient gradient errors without requiring accurate characterization of the gradient system impulse response. PMID:24801945

Harkins, Kevin D; Does, Mark D; Grissom, William A

2014-08-01

279

Length selective accumulation of oligonucleotides in thermal gradients  

NASA Astrophysics Data System (ADS)

Central to most Origin-of-Life scenarios is the possibility for pre-biotic organic molecules to interact in order to form increasingly complex, catalytic molecular machinery ultimately capable of autonomous replication. While strong evidence for the spontaneous synthesis of single nucleotides [1] recently arose, concentrations required to allow these building blocks to polymerize [2] and gain functionality, still seem improbable for early earth conditions. Here, we demonstrate experimentally that temperature gradients across pores, as found in rocks near hydrothermal vents [3], are sufficient to accumulate nucleotides efficiently from dilute solutions. In particular we show that depending on the pores' dimensions, it can act as a length-selective molecular filter. We suggest that equivalent systems could have served as meeting points for long and complex molecules, too rare to find each other in a dilute primordial ocean. Furthermore, we discuss under which conditions this selection could have triggered the evolutionary adaptation of molecular replicators, and how polymerase chain reaction assays could nowadays benefit from the presented concept. References: 1. M. Powner et al., Nature 459 (2009), 2. G. Costanzo et al., ChemBioChem 13 (2012), 3. P. Baaske et al., PNAS (2007)

Kreysing, Moritz; Lanzmich, Simon; Braun, Dieter

2013-03-01

280

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

E-print Network

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

Smith, Bradley D.

281

Bayesian Policy Gradient and Actor-Critic Algorithms Bayesian Policy Gradient and Actor-Critic Algorithms  

E-print Network

. 1 hal-00776608,version1-15Jan2013 #12;Ghavamzadeh and Engel suitable for solving problems in which Yaakov Engel yakiengel@gmail.com Editor: Abstract Policy gradient methods are reinforcement learning

Paris-Sud XI, Université de

282

High magnetic gradient environment causes alterations of cytoskeleton and cytoskeleton-associated genes in human osteoblasts cultured in vitro  

NASA Astrophysics Data System (ADS)

The effects of a high magnetic gradient environment (HMGE) on the cytoskeletal architecture and genes associated with the cytoskeleton in osteoblasts (MC3T3-E1 and MG-63 cells) were investigated using confocal microscopy, real-time polymerase chain reaction (PCR) and atomic force microscopy (AFM). The findings showed that, under diamagnetic levitation conditions, the architecture and average height of the cytoskeleton and surface roughness in osteoblasts were dramatically altered. HMGE affects cytoskeleton arrangement and cytoskeleton-associated gene expression.

Qian, A. R.; Yang, P. F.; Hu, L. F.; Zhang, W.; Di, S. M.; Wang, Z.; Han, J.; Gao, X.; Shang, P.

2010-09-01

283

Optimisation of gradient elution with serially-coupled columns. Part I: single linear gradients.  

PubMed

A mixture of compounds often cannot be resolved with a single chromatographic column, but the analysis can be successful using columns of different nature, serially combined through zero-dead volume junctions. In previous work (JCA 1281 (2013) 94), we developed an isocratic approach that optimised simultaneously the mobile phase composition, stationary phase nature and column length. In this work, we take the challenge of implementing optimal linear gradients for serial columns to decrease the analysis time for compounds covering a wide polarity range. For this purpose, five ACE columns of different selectivity (three C18 columns of different characteristics, a cyano and a phenyl column) were combined, aimed to resolve a mixture of 15 sulphonamides using acetonitrile-water gradients. A gradient predictive system, based on numerical integration, was built to simulate chromatograms under linear gradient profiles. Two approaches were compared: the optimisation of the combination of columns pre-selecting the gradient profile, developed by De Beer et al. (Anal. Chem. 82 (2010) 1733), and the optimisation of the gradient program after pre-selecting the column combination using isocratic elution, developed for this work. Several refinements concerning the gradient delays along the solute migration and peak half-width modelling were included to improve the realism of the predictions. Pareto plots (expressed as analysis time versus predicted global resolution) assisted in the selection of the best separation conditions. The massive computation time in the gradient optimisation, once the column combination was optimised, was reduced to ca. 3min by using genetic algorithms. PMID:24891161

Ortiz-Bolsico, C; Torres-Lapasió, J R; García-Alvarez-Coque, M C

2014-07-11

284

Data-driven backward chaining  

NASA Technical Reports Server (NTRS)

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.

Haley, Paul

1991-01-01

285

Program predicts reservoir temperature and geothermal gradient  

SciTech Connect

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.

Kutasov, I.M.

1992-06-01

286

Automated apparatus for producing gradient gels  

DOEpatents

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.

Anderson, N.L.

1983-11-10

287

Ecological gradients within a Pennsylvanian mire forest  

USGS Publications Warehouse

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.

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

2007-01-01

288

Opinion formation models on a gradient  

E-print Network

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, we also present a model where the width of the transition between opinions scales $\\propto g^{-1/4}$, not $\\propto g^{-4/7}$ as in independent percolation, and the cluster size distribution is consistent with first-order percolation.

Gastner, Michael T; Pruessner, Gunnar; Draief, Moez

2014-01-01

289

Electron profile stiffness and critical gradient studies  

SciTech Connect

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.

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

290

Electron profile stiffness and critical gradient studies  

NASA Astrophysics Data System (ADS)

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 ?Te. Electron stiffness was found to slowly increase with toroidal rotation velocity. A critical inverse temperature gradient scale length 1/LC ˜ 3 m-1 was identified at ? =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 -?Te, were fit reasonably well by a model containing a critical inverse temperature gradient scale length and varying linearly with 1/LT above the threshold.

DeBoo, J. C.; Petty, C. C.; White, A. E.; Burrell, K. H.; Doyle, E. J.; Hillesheim, J. C.; Holland, C.; McKee, G. R.; Rhodes, T. L.; Schmitz, L.; Smith, S. P.; Wang, G.; Zeng, L.

2012-08-01

291

Automated apparatus for producing gradient gels  

DOEpatents

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.

Anderson, Norman L. (Clarendon Hills, IL)

1986-01-01

292

Ecological gradients within a Pennsylvanian mire forest  

SciTech Connect

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.

DiMichele, W.A.; Falcon-Lang, H.J.; Nelson, W.J.; Brick, S.D.; Ames, P.R. [Smithsonian Institute, Washington, DC (United States)

2007-05-15

293

Temperature Gradient Driven Lasing and Stimulated Cooling  

NASA Astrophysics Data System (ADS)

A laser can be understood as a thermodynamic engine converting heat to a coherent single mode field close to Carnot efficiency. To achieve lasing, spectral shaping of the excitation light is used to generate 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 temperatures, we predict that lasing can also occur on an actual spatial temperature gradient between the pump and gain regions. Gain and narrow band laser emission require a sufficiently large temperature gradient and resonator quality. Lasing appears concurrent with amplified heat flow between the reservoirs and points to a new form of stimulated solid state cooling. In addition, such a mechanism could reduce intrinsic heating and thus extend the operating regime of quantum cascade lasers by substituting phonon emission driven injection by a phonon absorption step.

Sandner, K.; Ritsch, H.

2012-11-01

294

LOWER BOUNDS FOR LUCAS CHAINS MARTIN KUTZ  

E-print Network

LOWER BOUNDS FOR LUCAS CHAINS MARTIN KUTZ SIAM J. COMPUT. c 2002 Society for Industrial and Applied Mathematics Vol. 31, No. 6, pp. 1896­1908 Abstract. Lucas chains are a special type of addition chains and exponentiation, Lucas chains yield computation sequences for Lucas functions, a special kind of linear

Bernstein, Daniel

295

Simulation for supply Chain management: An Overview  

E-print Network

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

Paris-Sud XI, Université de

296

CALCULATING THE CARBON FOOTPRINT SUPPLY CHAIN FOR  

E-print Network

CALCULATING THE CARBON FOOTPRINT SUPPLY CHAIN FOR THE SEMICONDUCTOR INDUSTRY By: Yasser Dessouky #12;Carbon Footprint Supply Chain Carbon Trust defines carbon footprint of a supply chain as follows: "The carbon footprint of a product is the carbon dioxide emitted across the supply chain for a single

Su, Xiao

297

Laser-initiated chemical chain reactions  

Microsoft Academic Search

A detailed kinetic and experimental analysis is presented for chemical chain reaction processes initiated by well-controlled, low power laser pulses. Realtime evolution of the chain reaction is followed by direct detection of infrared chemiluminescence from vibrationally excited HCl product molecules produced by one of the propagation reactions in the chain. By appropriate choice of conditions, the chain reactions may be

David J. Nesbitt; Stephen R. Leone

1980-01-01

298

Automotive supply chain logistics cost management research  

Microsoft Academic Search

Automobile enterprises must be based on the survival of the entire supply chain's competitive edge relies on strengthening the supply chain, logistics cost management for enterprises increasingly become a priority project. In this paper, by using of supply chain management and logistics cost management theoretical knowledge, from the view of overall situation of automotive industry supply chain in China, logistics

Tang Liansheng; Xu Huajie; Nong Xia

2010-01-01

299

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

300

Scan chain clustering for test power reduction  

Microsoft Academic Search

An effective technique to save power during scan based test is to switch off unused scan chains. The results obtained with this method strongly depend on the mapping of scan flip-flops into scan chains, which determines how many chains can be deactivated per pattern. In this paper, a new method to cluster flip-flops into scan chains is presented, which minimizes

Melanie Elm; Hans-joachim Wunderlich; Michael E. Imhof; Christian G. Zoellin; Jens Leenstra; Nicolas Maeding

2008-01-01

301

Supply chain risk mitigation: modeling the enablers  

Microsoft Academic Search

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

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

2006-01-01

302

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

SciTech Connect

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.

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

1991-04-01

303

Precise Nanoelectronics with Adatom Chains  

NASA Technical Reports Server (NTRS)

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.

Yamada, Toshishige

1999-01-01

304

M-step preconditioned conjugate gradient methods  

NASA Technical Reports Server (NTRS)

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.

Adams, L.

1983-01-01

305

DC CHARACTERIZATION OF HIGH GRADIENT MULTILAYER INSULATORS  

SciTech Connect

We have developed a novel insulator concept that involves the use of alternating layers of conductors and insulators with periods less than 1 mm. We have demonstrated that these structures perform 2 to 5 times better than conventional insulators in long pulse, short pulse, and alternating polarity applications. We present new testing results showing exceptional behavior at DC, with gradients in excess of 110kV/cm in vacuum.

Watson, J A; Caporaso, G J; Sampayan, S E; Sanders, D M; Krogh, M L

2005-05-26

306

The salt-gradient solar pond  

NASA Astrophysics Data System (ADS)

The salt gradient solar pond was modeled both experimentally and numerically. The experimental model used a small scale tank with artificial sunlight. Both temperature and concentration measurements were taken. The numerical model used a one dimensional heat conduction model to describe the heating phenomena in the pond. The two models predicted the same type of behavior as that expected in full scale ponds. There were small differences in the two models. These differences arose from simplifications in the numerical model.

Brown, S. T.

1983-02-01

307

Electron transport and the critical temperature gradient  

Microsoft Academic Search

Tore Supra electron thermal fluxes, analyzed over a range of heating powers and plasma densities, are shown to vary parametrically according to the small-scale electron temperature gradient (ETG) model, rather than the ion inertial scale electrostatic gyro-Bohm model. Steady-state power balance analysis and time-varying interpretative transport simulations, performed on the Tore Supra Fast Wave Electron Heating database, validate the ETG

W. Horton; G. T. Hoang; C. Bourdelle; X. Garbet; M. Ottaviani; L. Colas

2004-01-01

308

Control of vortex breakdown by temperature gradients  

Microsoft Academic Search

An axial gradient of temperature can either suppress or enhance vortex breakdown (VB). The underlying mechanism of such VB control is centrifugal or\\/and gravitational convection. An additional thermal-convection flow directed oppositely to the base flow suppresses VB while a co-flow enhances VB. Our numerical simulations of a compressible flow in a sealed cylinder induced by a rotating bottom disk clearly

Miguel Angel Herrada; Vladimir Shtern

2003-01-01

309

Gaseous Diffusion in a Temperature Gradient  

Microsoft Academic Search

The theory of diffusion in a temperature gradient has been tested by comparing the results of gas mixing experiments and gas unmixing experiments, the unmixing being caused by thermal diffusion. Both types of measurements have been carried out in the same apparatuses with the same temperature distributions, so that corrections cancel on taking ratios. Measurements are reported on H2-37Ar, H2-85Kr,

E. A. Mason; Stanley Weissman

1965-01-01

310

Modeling neuronal response to disparity gradient  

Microsoft Academic Search

There is a rich literature of physiological studies that a subset of neurons in visual cortices is discriminative of 3-D surface\\u000a orientation using only the disparity gradient information. One of the physiological models to account for this sensibility\\u000a to surface slant is the dif-frequency disparity model. Although this model is physiologically plausible, no computational\\u000a analysis is available to explain how

Lianqing Yu; Zhanyi Hu

2009-01-01

311

Stochastic Gradient Descent Tricks Leon Bottou  

E-print Network

answer is y, and we choose a family F of functions fw(x) parametrized by a weight vector w. We seek the function f F that minimizes the loss Q(z, w) = (fw(x), y) averaged on the examples. Although we would like the empirical risk En(fw) using gradient descent (GD). Each iteration updates the weights w on the basis

Bottou, Léon

312

A gradient model of cardiac pacemaker myocytes  

Microsoft Academic Search

We have formulated a spatial-gradient model of action potential heterogeneity within the rabbit sinoatrial node (SAN), based on cell-specific ionic models of electrical activity from its central and peripheral regions. The ionic models are derived from a generic cell model, incorporating five background and exchange currents, and seven time-dependent currents based on three- or four-state Markov schemes. State transition rates

Nigel H. Lovell; Shaun L. Cloherty; Branko G. Celler; Socrates Dokos

2004-01-01

313

On Early Stopping in Gradient Descent Learning  

Microsoft Academic Search

In this paper we study a family of gradient descent algorithms to approximate the regression function from reproducing kernel\\u000a Hilbert spaces (RKHSs), the family being characterized by a polynomial decreasing rate of step sizes (or learning rate). By\\u000a solving a bias-variance trade-off we obtain an early stopping rule and some\\u000a probabilistic upper bounds for the convergence of the algorithms. We

Yuan Yao; Lorenzo Rosasco; Andrea Caponnetto

2007-01-01

314

Biogeochemical gradients in the lower Columbia River  

Microsoft Academic Search

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

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

1997-01-01

315

Measuring the vertical gradient of gravity  

NSDL National Science Digital Library

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

Sternberg, Rob

316

PLETHORA gradient formation mechanism separates auxin responses.  

PubMed

During plant growth, dividing cells in meristems must coordinate transitions from division to expansion and differentiation, thus generating three distinct developmental zones: the meristem, elongation zone and differentiation zone. Simultaneously, plants display tropisms, rapid adjustments of their direction of growth to adapt to environmental conditions. It is unclear how stable zonation is maintained during transient adjustments in growth direction. In Arabidopsis roots, many aspects of zonation are controlled by the phytohormone auxin and auxin-induced PLETHORA (PLT) transcription factors, both of which display a graded distribution with a maximum near the root tip. In addition, auxin is also pivotal for tropic responses. Here, using an iterative experimental and computational approach, we show how an interplay between auxin and PLTs controls zonation and gravitropism. We find that the PLT gradient is not a direct, proportionate readout of the auxin gradient. Rather, prolonged high auxin levels generate a narrow PLT transcription domain from which a gradient of PLT protein is subsequently generated through slow growth dilution and cell-to-cell movement. The resulting PLT levels define the location of developmental zones. In addition to slowly promoting PLT transcription, auxin also rapidly influences division, expansion and differentiation rates. We demonstrate how this specific regulatory design in which auxin cooperates with PLTs through different mechanisms and on different timescales enables both the fast tropic environmental responses and stable zonation dynamics necessary for coordinated cell differentiation. PMID:25156253

Mähönen, Ari Pekka; ten Tusscher, Kirsten; Siligato, Riccardo; Smetana, Ond?ej; Díaz-Triviño, Sara; Salojärvi, Jarkko; Wachsman, Guy; Prasad, Kalika; Heidstra, Renze; Scheres, Ben

2014-11-01

317

Phosphorescent imaging of oxygen gradients in tissues  

NASA Astrophysics Data System (ADS)

Until recently, the ability to measure the changing oxygen gradients in perfused tissues in response to metabolic demand, has been limited to point-measurements and/or averaged A-V oxygen differences during perfusion using oxygen electrodes. With the recent introduction of novel phosphorescent probes specifically quenched by oxygen, the ability to spacially map oxygen gradients in real-time may offer new insights into the dynamics of microvascular design and supply. Accordingly, this paper provides initial image data on Langendorff perfused rat hearts wherein the relative change in phosphorescent intensity of Pd-meso-tetra(4- carboxyphenyl)phorphine (2micrometers ) as the reporter probe, is quantitatively related to spacial oxygen gradients as seen on the left-ventricle during changing gassing conditions. Digital image analysis (frame advance), after proper calibration and alignment, provides images which can be usefully interpreted. Clinical applications of such emerging technologies could have wide-spread diagnostic applications not only as applied to the coronary bed, but other tissue surfaces displaying various degrees of aschemia and/or hypoxia.

Swanson, Curtis J.; Kitakis, F.

1995-08-01

318

Crosswind Shear Gradient Affect on Wake Vortices  

NASA Technical Reports Server (NTRS)

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

Proctor, Fred H.; Ahmad, Nashat N.

2011-01-01

319

SPEAR3 Gradient Dipole Core Fabrication  

SciTech Connect

Traditional means of core fabrication are to glue the laminations or weld them to form the yoke structure. These means result in good yoke assemblies for shorter (<0.6m) magnets. However, because of weld distortions or mechanical strength limitations, welding and/or gluing techniques are difficult to gain high mechanical precision for longer cores. The SPEAR3 gradient dipoles are up to 1.45m long and require distortions of <0.05mm. Therefore, the SPEAR3 gradient dipole core design incorporated an assembly technique, originally devised for the PEPII insertion quadrupoles and later adapted for the ALS gradient magnets. This technique involved fabricating a rigid frame for the core, precisely stacking and compressing the laminations using hydraulic jacks and granite surfaces and straight edges, and fixing the laminations in the frame by filling the grooves between the laminations and frame using steel loaded epoxy. Although this technique has been used in the past, it has never been fully described and published. This paper is written to provide a detailed description of the procedure and to present measurement data demonstrating the mechanical precision and stiffness of the resulting product.

Li, Nanyang

2003-07-29

320

Energy Gradient Theory of Hydrodynamic Instability  

E-print Network

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.

Hua-Shu Dou

2005-01-28

321

Gradient expansion, curvature perturbations, and magnetized plasmas  

SciTech Connect

The properties of magnetized plasmas are always investigated under the hypothesis that the relativistic inhomogeneities stemming from the fluid sources and from the geometry itself are sufficiently small to allow for a perturbative description prior to photon decoupling. The latter assumption is hereby relaxed and predecoupling plasmas are described within a suitable expansion where the inhomogeneities are treated to a given order in the spatial gradients. It is argued that the (general relativistic) gradient expansion shares the same features of the drift approximation, customarily employed in the description of cold plasmas, so that the two schemes are physically complementary in the large-scale limit and for the low-frequency branch of the spectrum of plasma modes. The two-fluid description, as well as the magnetohydrodynamical reduction, is derived and studied in the presence of the spatial gradients of the geometry. Various solutions of the coupled system of evolution equations in the anti-Newtonian regime and in the quasi-isotropic approximation are presented. The relation of this analysis to the so-called separate universe paradigm is outlined. The evolution of the magnetized curvature perturbations in the nonlinear regime is addressed for the magnetized adiabatic mode in the plasma frame.

Giovannini, Massimo [Department of Physics, Theory Division, CERN, 1211 Geneva 23 (Switzerland); INFN, Section of Milan-Bicocca, 20126 Milan (Italy); Rezaei, Zahra [Department of Physics, Theory Division, CERN, 1211 Geneva 23 (Switzerland); Isfahan University of Technology, Department of Physics, 84154 Isfahan (Iran, Islamic Republic of)

2011-04-15

322

Reconciling supply chain vulnerability, risk and supply chain management  

Microsoft Academic Search

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

H. Peck

2006-01-01

323

Quantum Crystals and Spin Chains  

E-print Network

In this note, we discuss the quantum version of the melting crystal corner in one, two, and three dimensions, generalizing the treatment for the quantum dimer model. Using a mapping to spin chains we find that the two--dimensional case (growth of random partitions) is integrable and leads directly to the Hamiltonian of the Heisenberg XXZ ferromagnet. The three--dimensional case of the melting crystal corner is described in terms of a system of coupled XXZ spin chains. We give a conjecture for its mass gap and analyze the system numerically.

Robbert Dijkgraaf; Domenico Orlando; Susanne Reffert

2008-03-13

324

Packaging of granular bead chain  

NASA Astrophysics Data System (ADS)

We find that a freely moving granular chain can be pushed, against the entropic force, into a confined cell if the passage to the cell is a channel of truncated-cone shape. In this setting, the granular chain, the cell and the channel can be considered as a mechanical analog of a DNA molecular, a bacteriophage and a portal motor, respectively. The force generated by the scaled-up analog of the mechanical motor and the packaging speed are found to be consistent with the real bacteriophage ?29 portal motor. Pauses and slips found in single-molecule experiments of DNA packaging of the bacteriophage are also observed in the analog system.

Jeng, Pei-Ren; Chen, KuanHua; Hwang, Gwo-jen; Tien, Chen-Man; Lien, Chenhsin; To, Kiwing; Chou, Y. C.

2011-11-01

325

Achieving consumer focus in supply chains  

Microsoft Academic Search

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

Keivan Zokaei; Peter Hines

2007-01-01

326

Characterizing electron temperature gradient turbulence via numerical simulation  

E-print Network

Characterizing electron temperature gradient turbulence via numerical simulation W. M. Nevins, California 94551 Received 8 June 2006; accepted 6 November 2006; published online 20 December 2006 Numerical simulations of electron temperature gradient ETG turbulence are presented that characterize the ETG

Hammett, Greg

327

Anisotropy of Brownian Motion Observed in a Temperature Gradient Gas  

Microsoft Academic Search

Random motion of submicron oil drops and smoke particles exhibit an anisotropy which appears to be a function of temperature gradient in the suspending gas. The Brownian motion is more significantly altered in a direction perpendicular to the gradient.

Richard M. Elrick

1969-01-01

328

Numerical Stochastic Perturbation Theory and the Gradient Flow  

E-print Network

We study the Yang-Mills gradient flow using numerical stochastic perturbation theory. As an application of the method we consider the recently proposed gradient flow coupling in the Schr\\"odinger functional for the pure SU(3) gauge theory.

Mattia Dalla Brida; Dirk Hesse

2013-11-15

329

Assignment of aliphatic side-chain 1HN/15N resonances in perdeuterated proteins.  

PubMed

The perdeuteration of aliphatic sites in large proteins has been shown to greatly facilitate the process of sequential backbone and side-chain 13C assignments and has also been utilized in obtaining long-range NOE distance restraints for structure calculations. To obtain the maximum information from a 4D 15N/15N-separated NOESY, as many main-chain and side-chain 1HN/15N resonances as possible must be assigned. Traditionally, only backbone amide 1HN/15N resonances are assigned by correlation experiments, whereas slowly exchanging side-chain amide, amino, and guanidino protons are assigned by NOEs to side-chain aliphatic protons. In a perdeuterated protein, however, there is a minimal number of such protons. We have therefore developed several gradient-enhanced and sensitivity-enhanced pulse sequences, containing water-flipback pulses, to provide through-bond correlations of the aliphatic side-chain 1HN/15N resonances to side-chain 13C resonances with high sensitivity: NH2-filtered 2D 1H-15N HSQC(H2N-HSQC), 3D H2N(CO)C gamma/beta and 3D H2N(COC gamma/beta)C beta/alpha for glutamine and asparagine side-chain amide groups; 2D refocused H(N epsilon/zeta)C delta/epsilon and H(N epsilon/zeta C delta/epsilon)C gamma/delta for arginine side-chain amino groups and non-refocused versions for lysine side-chain amino groups; and 2D refocused H(N epsilon)C zeta and nonrefocused H(N epsilon, eta)C zeta for arginine side-chain guanidino groups. These pulse sequences have been applied to perdeuterated 13C-/15N-labeled human carbonic anhydrase II (2H-HCA II). Because more than 95% of all side-chain 13C resonances in 2H-HCA II have already been assigned with the C(CC)(CO)NH experiment, the assignment of the side-chain 1HN/15N resonances has been straightforward using the pulse sequences mentioned above. The importance of assigning these side-chain HN protons has been demonstrated by recent studies in which the calculation of protein global folds was simulated using only 1HN-1HN NOE restraints. In these studies, the inclusion of NOE restraints to side-chain HN protons significantly improved the quality of the global fold that could be determined for a perdeuterated protein [R.A. Venters et al. (1995) J. Am. Chem. Soc., 117, 9592-9593]. PMID:8720832

Farmer, B T; Venters, R A

1996-01-01

330

Gradient chromatofocusing. versatile pH gradient separation of proteins in ion-exchange HPLC: characterization studies.  

PubMed

A new chromatofocusing technique called gradient chromatofocusing is characterized. Gradient chromatofocusing generates linear pH gradients on anion-exchange columns with inexpensive low molecular mass buffer components via HPLC gradient mixing. Gradient chromatofocusing results are compared with that of conventional chromatofocusing in the chromatography of several proteins on a Mono P column, including beta-lactoglobulin A and B, ovalbumin, BSA, and conalbumin. Gradient chromatofocusing shows superior performance, with resolution increases greater than 3-fold being realized for the entire protein mixture and up to 25-fold for a particular protein pair. This performance superiority arises from inherent advantages in the gradient chromatofocusing technique in optimizing conditions pertinent to separation, including buffer concentration and pH gradient slope. These resolution gains arise from both increases in separation factor and decreases in peak width achieved with the pH gradient chromatofocusing technique through the manipulation of buffer concentration and the pH gradient profile. Gradient chromatofocusing is also compared with conventional NaCl gradient ion-exchange chromatography using the same Mono P column, demonstrating 3-fold resolution gains, resulting from a 3-fold decrease in peak width. The present work demonstrates the significantly improved performance that gradient chromatofocusing has in protein separations compared to other ion-exchange chromatographic techniques. Mechanisms for the various effects are discussed. PMID:12433100

Shan, Lian; Anderson, David J

2002-11-01

331

Pore-pressure gradients, stresses, and induced earthquakes  

Microsoft Academic Search

In the theory of poroelasticity, spatial gradients in pore-pressure enter the equilibrium equations in the same way as distributed body forces. Pore-pressure gradients are thus associated with poroelastic stresses in the same way that temperature gradients associated with thermoelastic stresses. The author has suggested that pore-pressure gradients caused by pumping are responsible for earthquakes near some oil and gas fields.

Segall

1992-01-01

332

?-Conjugated Copolymers of Thiophene: Effect of Chain Architecture on the Physical and Optoelectronic Properties for Photovoltaic Applications  

NASA Astrophysics Data System (ADS)

We found that polymer chain architecture strongly influences phase separation capabilities of the donor-acceptor blend in bulk heterojunction organic photovoltaic devices. Ni-catalyzed controlled polymerization was utilized to access new conjugated copolymers of 3-hexylthiophene and 3-(hexyloxy)methylthiophene, two donor polymers. Monomer sequence was controlled along the copolymer chain by the rate of addition of the comonomers, to achieve diblock, random and gradient copolymer chain architectures. This allowed us to study the effect of copolymer sequence of polythiophene based copolymer/[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blend on the structure, nanoscale morphology and local charge transport properties using conductive and photoconductive atomic force microscopy. The gradient configuration showed the largest phase separation behavior with PCBM.

Amonoo, Jojo; Glynos, Emmanouil; Chen, Chelsea; Li, Anton; Locke, Jonas; McNeil, Anne; Green, Peter

2012-02-01

333

SUPPLY CHAIN MANAGER CHICAGO, IL  

E-print Network

is located in the Chicago area with multiple manufacturing operations and distribution facilities with broad responsibilities that include assessing, managing and improving the supply chain function-task in a fast paced environment. Intelligence, drive, integrity and flexibility are all important

Smilowitz, Karen

334

Novette chain design and performance  

SciTech Connect

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

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

1980-12-11

335

Gumdrop Chains and Shrinky Necklaces  

NSDL National Science Digital Library

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.

Watkiss, Gina

2003-01-01

336

Automotive Supply Chain Management Research  

Microsoft Academic Search

According to statistical analysis, the first half of 2009 once China surpassed the United States became the world's first automobile-producing country, while China's auto consumption, the proportion of total world consumption has reached 12%. In the trend of development of modern logistics, automobile enterprises must be based on the survival of the entire supply chain's competitive edge relies on strengthening

Liu Yanping; Zhang Baozhong; Wang Yong

2010-01-01

337

Gravity Waves from Chain Inflation  

E-print Network

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.

Amjad Ashoorioon; Katherine Freese

2008-11-14

338

InterplanetarySupply Chain Management &  

E-print Network

to system development. A simple example of this is standard and metric tools. In most cases, where Learned in NASA Space Flight Interplanetary Supply Chain Management & Logistics Architectures William A. In the consideration of these objectives, a need for a study on NASA Lessons Learned was recognized. The study

de Weck, Olivier L.

339

Spin chains and string theory  

Microsoft Academic Search

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

Martin Kruczenski

340

Evaluation of liquid lift approach to dual gradient drilling  

E-print Network

it is somewhat difficult to reach total depth with the single gradient system. This led to the invention of the dual gradient system. In the dual gradient method, heavy density fluid runs from the bottom hole to the mudline and a low density fluid from...

Okafor, Ugochukwu Nnamdi

2008-10-10

341

Evaluation of liquid lift approach to dual gradient  

E-print Network

it is somewhat difficult to reach total depth with the single gradient system. This led to the invention of the dual gradient system. In the dual gradient method, heavy density fluid runs from the bottom hole to the mudline and a low density fluid from...

Okafor, Ugochukwu Nnamdi

2009-05-15

342

Literacy Proficiency of Youth: Evidence of Converging Socioeconomic Gradients  

ERIC Educational Resources Information Center

In all countries that participated in the IALS, there is a strong relationship between the literacy skills of youth and family socioeconomic status. This relationship is referred to a socioeconomic gradient. One of the key findings of studies that examined socioeconomic gradients within countries is that gradients tend to converge at higher levels…

Willms, J. Douglas

2003-01-01

343

Characterization of imaging gradients in diffusion tensor imaging  

Microsoft Academic Search

For obtaining a complete model the diffusion tensor imaging (DTI) method is derived in a new linear algebraic framework in order to include the effect of all of the magnetic field gradients on the MRI signal. In the framework, the coefficient matrix of the estimation equations consists of the sum of three matrices corresponding to diffusion gradients, imaging gradients and

Alpay Özcan

2010-01-01

344

Minimizing Hot Spot Temperature in Asymmetric Gradient Coil Design  

Microsoft Academic Search

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

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

2011-01-01

345

Motion of aerosol particles in a temperature gradient  

Microsoft Academic Search

Theoretical and experimental results are presented which show that the thermal force on an aerosol particle in a temperature gradient depends on the velocity of the particle relative to the gas as well as the temperature gradient in the gas. It is shown that any motion of the particle along a line parallel to the temperature gradient tends to induce

Warren F. Phillips

1975-01-01

346

Thermal Force on an Aerosol Particle in a Temperature Gradient  

Microsoft Academic Search

Data on the thermal forces acting on aerosol particles in a temperature gradient are relatively few. Measurements are reported here on droplets of paraffin oil and castor oil suspended in air, showing the effect of temperature gradient, particle size, and particle material. The thermal force is directly proportional to the temperature gradient prevailing in the gas and to the particle

R. L. Saxton; W. E. Ranz

1952-01-01

347

Thermoacoustic mixture separation with an axial temperature gradient  

Microsoft Academic Search

thermoacoustic separation including now a finite temperature gradient lengthwise along the duct. We show in Sec. II by a simple model that there is a limiting temperature gradient at which the separation process ceases. In Secs. III and IV, we derive the mathematical details of the temperature gradient's effect on the separation. Then, in Sec. V, we describe an experimental

D. A. Gellera; G. W. Swift

2009-01-01

348

Supply chain challenges. building relationships.  

PubMed

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

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

2003-07-01

349

Chain Release Behavior of Gellan Gels  

NASA Astrophysics Data System (ADS)

The chain release behavior from gellan gels was studied by immersing the gel into water and monitoring the mass loss as a function of time. Concentration of released gellan in the external solution was determined for gels of different sizes using phenol-sulfuric acid method. The chain release process became faster with increasing total surface area and volume. However the concentration of released chain normalized by surface area and volume suggests that the chain release itself is governed not only by the ionic effect and the amount of unassociated chains in gel but other factors such as osmotic pressure may play an important role on the chain release from the gels. The diffusion coefficient was estimated from the chain release process which is in the same order of magnitude reported for an isolated gellan chain by light scattering. Rheological measurements also suggest that the unassociated gellan chains are released out when immersed in pure water while unassociated chains are restricted to release out when immersed in salt solution due to the intrusion of cations which is responsible for further association of the unassociated gellan chains being in agreement with the previously published results. The elastic modulus of gels was increased by immersion of gels in water and in salt solutions, which can be attributed as the stiffening of network chains due to gel swelling and the conversion from free and unassociated chains into network chains, respectively, leading to an increase in elastic modulus with time.

Hossain, Khandker S.; Nishinari, Katsuyoshi

350

Biogeochemistry of a temperate forest nitrogen gradient  

USGS Publications Warehouse

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.

Perakis, Steven S.; Sinkhorn, Emily R.

2011-01-01

351

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

E-print Network

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.

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

2008-10-01

352

Spin Gradient Demagnetization Cooling of Ultracold Atoms  

SciTech Connect

We demonstrate a new cooling method in which a time-varying magnetic field gradient is applied to an ultracold spin mixture. This enables preparation of isolated spin distributions at positive and negative effective spin temperatures of {+-}50 pK. The spin system can also be used to cool other degrees of freedom, and we have used this coupling to cool an apparently equilibrated Mott insulator of rubidium atoms to 350 pK. These are the lowest temperatures ever measured in any system. The entropy of the spin mixture is in the regime where magnetic ordering is expected.

Medley, Patrick; Weld, David M.; Miyake, Hirokazu; Pritchard, David E.; Ketterle, Wolfgang [MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2011-05-13

353

Pulsed Gradient Spin-Echo NMR  

NASA Astrophysics Data System (ADS)

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.

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

354

A Compact High Gradient Pulsed Magnetic Quadpole  

SciTech Connect

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

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

2005-07-05

355

COMPARISON OF GKS CALCULATED CRITICAL ION TEMPERATURE GRADIENTS AND ITG GROWTH RATES TO DIII-D MEASURED GRADIENTS AND DIFFUSIVITIES  

Microsoft Academic Search

OAK-B135 The gyrokinetic equations predict that various drift type waves or modes can be unstable in a tokamak. For some of these modes, such as the ion temperature gradient (ITG) mode and the electron temperature gradient mode, there exists a critical gradient, above which the mode is unstable. Since the existence of unstable modes can cause increased transport, plasmas which

GM STAEBLER; CC PETTY; CM GREENFIELD; TC LUCE

2003-01-01

356

A model of supply chain and supply chain decision-making complexity  

Microsoft Academic Search

Purpose – The objective of this paper is to develop a comprehensive model of supply chain and supply chain decision-making complexity that provides an understanding of the drivers of supply chain complexity and strategies to manage supply chain and supply chain decision-making complexity and outcomes. Design\\/methodology\\/approach – Grounded theory methodology is employed to build a theory of supply chain and

Ila Manuj; Funda Sahin

2011-01-01

357

Influence of petroleum deposit geometry on local gradient of electron acceptors and microbial catabolic potential.  

PubMed

A field survey was conducted following the Deepwater Horizon blowout and it was noted that resulting coastal petroleum deposits possessed distinct geometries, ranging from small tar balls to expansive horizontal oil sheets. A subsequent laboratory study evaluated the effect of oil deposit geometry on localized gradients of electron acceptors and microbial community composition, factors that are critical to accurately estimating biodegradation rates. One-dimensional top-flow sand columns with 12-h simulated tidal cycles compared two contrasting geometries (isolated tar "balls" versus horizontal "sheets") relative to an oil-free control. Significant differences in the effluent dissolved oxygen and sulfate concentrations were noted among the columns, indicating presence of anaerobic zones in the oiled columns, particularly in the sheet condition. Furthermore, quantification of genetic markers of terminal electron acceptor and catabolic processes via quantitative polymerase chain reaction of dsrA (sulfate-reduction), mcrA (methanogenesis), and cat23 (oxygenation of aromatics) genes in column cores suggested more extensive anaerobic conditions induced by the sheet relative to the ball geometry. Denaturing gradient gel electrophoresis similarly revealed that distinct gradients of bacterial communities established in response to the different geometries. Thus, petroleum deposit geometry impacts local dominant electron acceptor conditions and may be a key factor for advancing attenuation models and prioritizing cleanup. PMID:22574781

Singh, Gargi; Pruden, Amy; Widdowson, Mark A

2012-06-01

358

METALLICITY GRADIENTS AND GAS FLOWS IN GALAXY PAIRS  

SciTech Connect

We present the first systematic investigation into the metallicity gradients in galaxy close pairs. We determine the metallicity gradients for eight galaxies in close pairs using H II region metallicities obtained with high signal-to-noise multi-slit observations with the Keck LRIS Spectrograph. We show that the metallicity gradients in close pairs are significantly shallower than gradients in isolated spiral galaxies such as the Milky Way, M83, and M101. These observations provide the first solid evidence that metallicity gradients in interacting galaxies are systematically different from metallicity gradients in isolated spiral galaxies. Our results suggest that there is a strong relationship between metallicity gradients and the gas dynamics in galaxy interactions and mergers.

Kewley, Lisa J.; Rupke, David; Jabran Zahid, H. [Institute for Astronomy, 2680 Woodlawn Drive, University of Hawaii, Hilo, HI 96822 (United States); Geller, Margaret J. [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Barton, Elizabeth J., E-mail: kewley@ifa.hawaii.ed [University of California, Irvine, CA 92697 (United States)

2010-09-20

359

Effects of gradient coupling on amplitude death in nonidentical oscillators  

E-print Network

In this work, we investigate gradient coupling effect on amplitude death in an array of N cou- pled nonidentical oscillators with no-flux boundary conditions and periodic boundary conditions respectively. We find that the effects of gradient coupling on amplitude death in diffusive coupled nonidentical oscillators is quite different between those two boundaries conditions. With no-flux boundary conditions, there is a system size related critical gradient coupling $r_c$ within which the gradient coupling tends to monotonically enlarge the amplitude death domain in the parameter space. With the periodical boundary conditions, there is an optimal gradient coupling constant $r_o$ to realize largest AD domain. The gradient coupling first enlarges then decreases the amplitude death domain of diffusive coupled oscillators. The amplitude death domain of parameter space are analytically predicted for small number of gradient coupled oscillators.

Weiqing Liu; Jinghua Xiao; Lixiang Li; Ye Wu; Min Lu

2011-01-06

360

Gradient navigation model for pedestrian dynamics  

NASA Astrophysics Data System (ADS)

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.

Dietrich, Felix; Köster, Gerta

2014-06-01

361

Gradient navigation model for pedestrian dynamics.  

PubMed

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. PMID:25019827

Dietrich, Felix; Köster, Gerta

2014-06-01

362

Gradient Navigation Model for Pedestrian Dynamics  

E-print Network

We present a new microscopic 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, 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.

Felix Dietrich; Gerta Köster

2014-01-02

363

Doubly diffusive linear stability with nonconstant gradients  

NASA Astrophysics Data System (ADS)

The effect of variable stratification on thelinear bifurcations of a doubly diffusive plane parallel layer are examined numerically by expanding in a Fourier series. Because the motivation is analysis of solar pond stability, a Prandtl number of 7 and ratio of diffusivities of 1/80 is used in the study, with (large) solute Rayleigh numbers (Rs) ranging from 10,000 to 10 to the 12th power. Stratification of solute is a cubic antisymmetric about midlayer; because temprature has a higher diffusivity, it is given a linear stratification. The numerical results approach Walton's perturbation solution at large Rs, but differ significantly at smaller Rs (10 to the 8th power). While both exchange of stabilities and overstable modes display n expected tendency to localize about the point of minimum solute gradient, the overstable modes behave in oder, nonintuitive, ways. Localization, if extreme enough, can even stabilize small sublayers of reversed salinity gradient. Above Rs = 10 to the 12th power, computations become prohibitively expensive as a continuous spectrum is approached.

Zangrando, F.; Bertram, L.

1984-06-01

364

Asymmetric Uncertainty Expression for High Gradient Aerodynamics  

NASA Technical Reports Server (NTRS)

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.

Pinier, Jeremy T

2012-01-01

365

MRI gradient fields increase brain mannitol space.  

PubMed

Following nephrectomy and intravenous injection of tritiated mannitol, adult male rats were exposed to magnetic resonance imaging (MRI) procedures at 1.5 T, 0.5 T, and 0.3 T. Compared to rats similarly handled but not exposed to MRI procedures, brain mannitol concentration, expressed as a percentage of mean body concentration, was significantly increased at 0.3 T and 0.5 T but not at 1.5 T. At 0.3 T, exposure to gradient-field fluctuations used for imaging increased brain mannitol concentration, but exposures to static main field and pulsed radiofrequency energies did not. Increased brain mannitol associated with gradient-field flux may reflect increased blood-brain barrier permeability or blood volume in brain. MRI effects on brain mannitol space are of uncertain clinical significance, but are consistent with prior evidence of an MRI-induced increase of brain capillary endothelial cell transport observed with horseradish peroxidase. Further studies are needed to confirm these findings and to explore the processes underlying changes in mannitol distribution related to MRI. PMID:2517136

Garber, H J; Oldendorf, W H; Braun, L D; Lufkin, R B

1989-01-01

366

Template gradient matching in spherical images  

NASA Astrophysics Data System (ADS)

Most of today's robot vehicles are equipped with omnidirectional sensors which provide surround awareness and easier navigation. Due to the persistence of the appearance in omnidirectional images, many global navigation or formation control tasks, instead of using landmarks or fiducials, they need only reference images of target positions or objects. In this paper, we study the problem of template matching in spherical images. The natural transformation of a pattern on the sphere is a 3D rotation and template matching is the localization of a target in any orientation given by a reference image. Unfortunately, the support of the template is space variant on the Euler angle parameterization. Here we propose a new method which matches the gradients of the image and the template, with space-invariant operation. Using properties of the angular momentum, we have proved in fact that the gradient correlation can be very easily computed by the 3D Inverse Fourier Transform of a linear combination of spherical harmonics. An exhaustive search localizes the maximum of this correlation. Experimental results on real data show a very accurate localization with a variety of targets. In future work, we plan to address targets appearing in different scales.

Sorgi, Lorenzo; Daniilidis, Kostas

2004-05-01

367

Discovering the Chain Rule Graphically  

ERIC Educational Resources Information Center

The chain rule is one of the hardest ideas to convey to students in Calculus I. It is difficult to motivate, so that most students do not really see where it comes from; it is difficult to express in symbols even after it is developed; and it is awkward to put it into words, so that many students can not remember it and so can not apply it…

Gordon, Sheldon P.

2005-01-01

368

BranchedChain Amino Acids  

Microsoft Academic Search

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

Miroslav Pátek

369

Pumpernickel Valley Geothermal Project Thermal Gradient Wells  

SciTech Connect

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

Z. Adam Szybinski

2006-01-01

370

Food web complexity and stability across habitat connectivity gradients.  

PubMed

The effects of habitat connectivity on food webs have been studied both empirically and theoretically, yet the question of whether empirical results support theoretical predictions for any food web metric other than species richness has received little attention. Our synthesis brings together theory and empirical evidence for how habitat connectivity affects both food web stability and complexity. Food web stability is often predicted to be greatest at intermediate levels of connectivity, representing a compromise between the stabilizing effects of dispersal via rescue effects and prey switching, and the destabilizing effects of dispersal via regional synchronization of population dynamics. Empirical studies of food web stability generally support both this pattern and underlying mechanisms. Food chain length has been predicted to have both increasing and unimodal relationships with connectivity as a result of predators being constrained by the patch occupancy of their prey. Although both patterns have been documented empirically, the underlying mechanisms may differ from those predicted by models. In terms of other measures of food web complexity, habitat connectivity has been empirically found to generally increase link density but either reduce or have no effect on connectance, whereas a unimodal relationship is expected. In general, there is growing concordance between empirical patterns and theoretical predictions for some effects of habitat connectivity on food webs, but many predictions remain to be tested over a full connectivity gradient, and empirical metrics of complexity are rarely modeled. Closing these gaps will allow a deeper understanding of how natural and anthropogenic changes in connectivity can affect real food webs. PMID:25227679

LeCraw, Robin M; Kratina, Pavel; Srivastava, Diane S

2014-12-01

371

Using MR Elastography to Image Force Chains in a Quasi-Static Granular Assembly  

NASA Astrophysics Data System (ADS)

Questions about the internal structure of dense granular assemblies remain unanswered for lack of 3D experimental data. It is known from 2D observations and from the boundaries of 3D systems that non-uniform stresses are present on container boundaries as well as at the bottom of granular piles. These forces are seen in 2D to be distributed by force chains, where most of the stress is transmitted through a small number of chains with much of the assembly transmitting little or none of the force. However, force chains have yet to be fully visualized in 3D. We propose a variation of magnetic resonance elastography (MRE) to image 3D force chains within a densely packed granular assembly. MRE is an MRI technique whereby small periodic displacements within an elastic material can be measured. Multiple bipolar motion encoding gradients incorporated into a typical pulse sequence, and applied at the frequency of mechanical oscillations, are used to detect the displacements. We have verified our MRE technique using a gel (Perma-Gel). We now extend this method to image force chains within a 3D granular assembly of particles under stress, on top of which is superimposed a small-amplitude vibration. It is our hypothesis that significant coherent displacements will be found only along force chains while most particles will move randomly. Experimental results will be presented.

Sanfratello, L.; Altobelli, S. A.; Behringer, R. P.; Fukushima, E.

2008-03-01

372

An integrative framework for architecting supply chains  

E-print Network

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 ...

Cela Díaz, Fernando

2006-01-01

373

Managing flexibility in the supply chain  

E-print Network

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 ...

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

2003-01-01

374

Supply chain management in the cement industry  

E-print Network

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 ...

Agudelo, Isabel

2009-01-01

375

Loss of coordination in competitive supply chains  

E-print Network

The loss of coordination in supply chains quantifies the inefficiency (i.e. the loss of total profit) due to the presence of competition in the supply chain. In this thesis, we discuss four models: one model with multiple ...

Teo, Koon Soon

2009-01-01

376

Supply chain for mobile network operator  

E-print Network

The purpose of this study is to understand and get insights on the characteristics of mobile device supply chain management for mobile networks operators. The relationship between corporate strategy and supply chain strategy ...

Liu, Kenneth Lap Chi

2010-01-01

377

Pharmaceutical Supply Chain Networks with Outsourcing  

E-print Network

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

Nagurney, Anna

378

Pharmaceutical Supply Chain Networks with Outsourcing  

E-print Network

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

Nagurney, Anna

379

Inuence of elastic gradient proles on dynamically loaded functionally graded materials: cracks along the gradient  

E-print Network

In¯uence of elastic gradient pro®les on dynamically loaded functionally graded materials: cracks reserved. Keywords: Functionally graded materials; Material nonhomogeneity; Finite element modeling; Stress intensity factors; Dynamic fracture 1. Introduction Functionally graded materials (FGMs) are known to oer

Rousseau, Carl-Ernst

380

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

E-print Network

Evolutionary Algorithms, such as Genetic Algorithms, or is sequentially improved until finding a satisfactory limited here to 50. Under these circumstances, several authors have used gradient algorithms. The computational cost of raw "global" algorithms, such as Genetic Algorithms (GA), is generally a curb on their use

Paris-Sud XI, Université de

381

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

NASA Astrophysics Data System (ADS)

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.

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

382

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

PubMed

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

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

383

Influence of tetracycline on the microbial community composition and activity of nitrifying biofilms.  

PubMed

The present work aims to evaluate the bacterial composition and activity (carbon and nitrogen removal) of nitrifying biofilms exposed to 50?gL(-1) of tetracycline. The tetracycline removal efficiency and the occurrence of tetracycline resistance (tet) genes were also studied. Two sequencing batch biofilm reactors (SBBRs) fed with synthetic wastewater were operated without (SBBR1) and with (SBBR2) the antibiotic. Both SBBRs showed similar organic matter biodegradation and nitrification activity. Tetracycline removal was about 28% and biodegradation was probably the principal removal mechanism of the antibiotic. Polymerase chain reaction-denaturing gradient gel electrophoresis analysis of the bacterial community showed shifts leading to not only the fading of some ribotypes, but also the emergence of new ones in the biofilm with tetracycline. The study of the tet genes showed that tet(S) was only detected in the biofilm with tetracycline, suggesting a relationship between its occurrence and the presence of the antibiotic. PMID:25127228

Matos, Maria; Pereira, Maria A; Parpot, Pier; Brito, António G; Nogueira, Regina

2014-12-01

384

Relation chain based clustering analysis  

NASA Astrophysics Data System (ADS)

Clustering analysis is currently one of well-developed branches in data mining technology which is supposed to find the hidden structures in the multidimensional space called feature or pattern space. A datum in the space usually possesses a vector form and the elements in the vector represent several specifically selected features. These features are often of efficiency to the problem oriented. Generally, clustering analysis goes into two divisions: one is based on the agglomerative clustering method, and the other one is based on divisive clustering method. The former refers to a bottom-up process which regards each datum as a singleton cluster while the latter refers to a top-down process which regards entire data as a cluster. As the collected literatures, it is noted that the divisive clustering is currently overwhelming both in application and research. Although some famous divisive clustering methods are designed and well developed, clustering problems are still far from being solved. The k - means algorithm is the original divisive clustering method which initially assigns some important index values, such as the clustering number and the initial clustering prototype positions, and that could not be reasonable in some certain occasions. More than the initial problem, the k - means algorithm may also falls into local optimum, clusters in a rigid way and is not available for non-Gaussian distribution. One can see that seeking for a good or natural clustering result, in fact, originates from the one's understanding of the concept of clustering. Thus, the confusion or misunderstanding of the definition of clustering always derives some unsatisfied clustering results. One should consider the definition deeply and seriously. This paper demonstrates the nature of clustering, gives the way of understanding clustering, discusses the methodology of designing a clustering algorithm, and proposes a new clustering method based on relation chains among 2D patterns. In this paper, a new method called relation chain based clustering is presented. The given method demonstrates that arbitrary distribution shape and density are not the essential factors for clustering research, in another words, clusters described by some particular expressions should be considered as a uniform mathematical description which is called "relation chain" emphasized in this paper. The relation chain indicates the relation between each pair of the spatial points and gives the evaluation of the connection between the pair-wise points. This relation chain based clustering algorithm initially assigns the neighborhood evaluation radius of the points, then assesses the clustering result based on inner-cluster variance of each cluster while increasing the radius, adjusting the radius properly and finally gives the clustering result. Some experiments are conducted using the proposed method and the hidden data structure is well explored.

Zhang, Cheng-ning; Zhao, Ming-yang; Luo, Hai-bo

2011-08-01

385

The Definition of a Supply Chain Project  

Microsoft Academic Search

Supply Chain Management aims at improving competitiveness of the supply chain as a whole, by integrating organizational units\\u000a along the supply chain and by coordinating material, information and financial flows in order to fulfill (ultimate) customer\\u000a demands (Sect. 1.1). Supply Chain Management projects range from functional improvements on the IT level to large-scale change\\u000a programmes. Functional improvements might be the

Christoph Kilger

386

Updating ; !Chains James P. Delgrande, Arvind Gupta  

E-print Network

or from w to v. A Ÿ; !­chain is a chain where edges are labelled from fŸ; !g such that the chainUpdating Ÿ; !­Chains James P. Delgrande, Arvind Gupta School of Computing Science, Simon Fraser is a directed acyclic graph in which, for any two vertices v and w, there is either a directed path from v to w

Delgrande, James P.

387

A market orientation in supply chain management  

Microsoft Academic Search

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

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

2007-01-01

388

The Advancement Value Chain: An Exploratory Model  

ERIC Educational Resources Information Center

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…

Leonard, Edward F., III

2005-01-01

389

Supply chain focus dependent safety stock placement  

Microsoft Academic Search

Increasing globalization, growing product range diversity, and rising consumer awareness are making markets highly competitive, forcing supply chains to adapt constantly to different stimuli. Growing competition between supply chains (as well as players within them) is also warranting a priority for overall supply chain performance over the goals of individual players. It is now well established in the literature that,

Gangaraju Vanteddu; Æ Ratna; Babu Chinnam; Kai Yang; Oleg Gushikin

2008-01-01

390

The scope of supply chain management research  

Microsoft Academic Search

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

Stephen J. New

1997-01-01

391

Supply Chain Management Jayashankar M. Swaminathan  

E-print Network

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

Swaminathan, Jayashankar M.

392

Supply Chain Management Professional Education Review  

E-print Network

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

Lin, Xiaodong

393

Supply Chain Management Professional Education Review  

E-print Network

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

Lin, Xiaodong

394

Supply Chain Management Faculty Brian Fugate  

E-print Network

Supply 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 interests include logistics strategy & performance and managing information flows in the supply chain. His

395

Supply Chain Management Degree Curriculum Information Sheet  

E-print Network

Supply Chain Management Degree Curriculum Information Sheet 33:010:275-Intro. to Managerial (3) 33:630:301-Intro. to Marketing (3) 33:799:301-Intro. to Supply Chain Management (3) 33:630:301) OR 33:799:380-Intro. to Project Management (3)*** 3 Supply Chain electives (9) *Beginning Fall 2013

Lin, Xiaodong

396

IEMS 486: Supply Chain Management Summer 2012  

E-print Network

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

Smilowitz, Karen

397

Supply Chain Management Professional Education Review  

E-print Network

Supply Chain Management Professional Education Review A monthly eNewsletter by the Department of Supply Chain Management and Marketing Sciences June 2009 Upcoming Events 2009, it has broader implications for all supply chain managers. How many of us have examined ways

Lin, Xiaodong

398

Supply Chain Management Strategy PROFESSIONAL DEVELOPMENT SEMINAR  

E-print Network

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

Gilchrist, James F.

399

Performance measurement for green supply chain management  

Microsoft Academic Search

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

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

2005-01-01

400

Modeling carbon footprints across the supply chain  

Microsoft Academic Search

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

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

2010-01-01

401

RECTIFIABILITY OF FLAT CHAINS Brian White  

E-print Network

RECTIFIABILITY OF FLAT CHAINS Brian White September 4, 1996; revised July 1, 1998 In memory) that a finite­mass flat chain over any coefficient group is rectifiable if and only if almost all of its 0­dimensional slices are rectifiable. This implies that every flat chain of finite mass and finite size

White, Brian

402

Manufacturing Footprint: A Value Chain Approach  

Microsoft Academic Search

This paper presents a process based conceptual approach for the evaluation of manufacturing plant location decisions. The developed approach recognises the importance of global supply chains and their increasing role in achieving desired competitiveness. The decision making environment for manufacturing plant location is divided into manufacturing, supply chain and general environment. The manufacturing environment consists of intra-organisational factors, supply chain

Sami Farooq; Chris O'Brien; John Johansen

403

Supply Chain Networks: Challenges and Opportunities  

E-print Network

Supply Chain Networks: Challenges and Opportunities from Analysis to Design Anna Nagurney Isenberg Sciences, Faculty of Engineering University of Waterloo, Canada, April 11, 2011 Anna Nagurney Supply Chain and teaching always stimulating and rewarding. Anna Nagurney Supply Chain Networks #12;Outline Background

Nagurney, Anna

404

A chain rule for multivariate divided differences  

E-print Network

by the error analysis of parametric curve interpolation, a chain rule was derived for divided differencesA chain rule for multivariate divided differences Michael S. Floater Abstract In this paper we to rectangular grids of points. Letting the points coalesce yields a chain rule for partial derivatives

Floater, Michael S.

405

Supply Chain and Information Sciences Technology 2010  

E-print Network

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

Guiltinan, Mark

406

Global Supply Chain Networks Electric Power Networks  

E-print Network

Global Supply Chain Network Model under Risk and Uncertainty Euler Method Numerical Example Motivation Research Global Supply Chain Network Model under Risk and Uncertainty Euler Method Numerical Example Global Power Networks Future Research Global Supply Chain Network Model under Risk and Uncertainty Euler Method

Nagurney, Anna

407

Supply Chain Networks: Challenges and Opportunities  

E-print Network

risk and uncertainty can only be rigorously examined from the view of supply chains as network systemsSupply Chain Networks: Challenges and Opportunities from Analysis to Design Anna Nagurney Isenberg November 23, 2010 Anna Nagurney Supply Chain Networks #12;Acknowledgments I would like to thank Dr. Les

Nagurney, Anna

408

My Research Interests Supply Chain Risk  

E-print Network

My Research Interests · Supply Chain Risk · Finite Capacity Planning and Scheduling · IntegratedLogistics · Customer Service · Global Terrorism Impacts on the Supply Chain #12;Allen, S.J. and E.W. Schuster. 4 (1987): pp. 1 - 5. #12;What is the difference between Logistics and Supply Chain Management? #12

Brock, David

409

Supply Chain Risk Analysis: Open Source Simulator  

Microsoft Academic Search

The evaluation of information sharing risk has become of paramount importance in the Supply Chain scenario. Chain actors are demanded to release an increasing amount of sensitive data in order to compute more precise master plans. In such a context, privacy issues arise and semi-honest or selfish actors could try to break the chain to increase their market shares. The

Marco Anisetti; Valerio Bellandi; Ernesto Damiani; Fulvio Frati; Gabriele Gianini; Gwanggil Jeon; Jechang Jeong

2009-01-01

410

THE SMARTER SUPPLY CHAIN OF THE FUTURE  

E-print Network

, supply chain executives told us they struggle with five primary challenges: visibility, risk, cost greater visibil- ity across the supply chain, mitigate risk, reduce cost and manage rising complexity to evaluate increasingly complex and dynamic risks and con- straints and manage the supply chain more

411

Supply Chain Networks: Challenges and Opportunities  

E-print Network

risk and uncertainty can only be rigorously examined from the view of supply chains as network systemsSupply Chain Networks: Challenges and Opportunities from Analysis to Design Anna Nagurney Isenberg on Computational Management Science Vienna, Austria July 28-30, 2010 Anna Nagurney Supply Chain Networks #12

Nagurney, Anna

412

Supply chain risks: a review and typology  

Microsoft Academic Search

Purpose – The purpose of this paper is to review the growing literature examining supply chain risk management (SCRM) and to develop a typology of risks in the supply chain. Design\\/methodology\\/approach – The paper draws its insights and conclusions from a review of the literature on supply chain risk, and a synthesis of the broader domain of risk management. Findings

Shashank Rao; Thomas J. Goldsby

2009-01-01

413

System Measurement Research on Supply Chain  

Microsoft Academic Search

Supply Chain Management is the planning and controlling of the integration of the supply, production, storage, distribution, and sales functions in the most efficient and cost-effective manner to meet one's service requirements. Due to the complexity induced by the large number of related and interdependent activities in the supply chain, coordinating activities in a supply chain, however, is difficult. System

Xiao-yan Wang; Jian-hua Zhang

2010-01-01

414

Adaptive Markov Chain Monte Carlo through Regeneration  

Microsoft Academic Search

Markov chain Monte Carlo (MCMC) is used for evaluating expectations of functions of interest under a target distribution ?. This is done by calculating averages over the sample path of a Markov chain having ? as its stationary distribution. For computational efficiency, the Markov chain should be rapidly mixing. This sometimes can be achieved only by careful design of the

Walter R. Gilks; Gareth O. Roberts; Sujit K. Sahu

1998-01-01

415

Fabrication of gradient refractive index ball lenses  

NASA Astrophysics Data System (ADS)

The theoretical model of the Maxwell fish eye sphere lens has long been regarded as an absolute optical instrument without practical application since it was proposed. But the study on the theory of Maxwell fish eye micro-spherical lens shows that at certain condition it has fine image formation ability and coupling efficiency. Based on the Fick's diffusion equations, the distribution function of refractive index of gradient refractive index (GRIN) ball lenses is derived. Lithium-containing silicate glass is fabricated and GRIN ball lenses whose diameters are from 0.3 to 3.0 mm are made by ion exchange and the sagging method in sodium nitrate. Radial refractive index profiles of these GRIN ball lens are measured by interferometer. Results show that the distribution of the index of refraction is a parabolic curve and in concordance with the computational consequence and its ? n is 0.0002.

Lv, Hao; Shi, Bangren; Wu, Jijiang; Guo, Lijun; Liu, Aimei

2008-03-01

416

Constant field gradient planar coupled cavity structure  

DOEpatents

A cavity structure is disclosed having at least two opposing planar housing members spaced apart to accommodate the passage of a particle beam through the structure between the members. Each of the housing members have a plurality of serially aligned hollows defined therein, and also passages, formed in the members, which interconnect serially adjacent hollows to provide communication between the hollows. The opposing planar housing members are spaced and aligned such that the hollows in one member cooperate with corresponding hollows in the other member to form a plurality of resonant cavities aligned along the particle beam within the cavity structure. To facilitate the obtaining of a constant field gradient within the cavity structure, the passages are configured so as to be incrementally narrower in the direction of travel of the particle beam. In addition, the spacing distance between the opposing housing members is configured to be incrementally smaller in the direction of travel of the beam. 16 figs.

Kang, Y.W.; Kustom, R.L.

1999-07-27

417

Constant field gradient planar coupled cavity structure  

DOEpatents

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

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

1999-01-01

418

Constant field gradient planar cavity structure  

SciTech Connect

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

Kang, Yoon W.; Kustom, R.L.

1997-12-01

419

Implementation of the phase gradient algorithm  

SciTech Connect

The recently introduced Phase Gradient Autofocus (PGA) algorithm is a non-parametric autofocus technique which has been shown to be quite effective for phase correction of Synthetic Aperture Radar (SAR) imagery. This paper will show that this powerful algorithm can be executed at near real-time speeds and also be implemented in a relatively small piece of hardware. A brief review of the PGA will be presented along with an overview of some critical implementation considerations. In addition, a demonstration of the PGA algorithm running on a 7 in. {times} 10 in. printed circuit board containing a TMS320C30 digital signal processing (DSP) chip will be given. With this system, using only the 20 range bins which contain the brightest points in the image, the algorithm can correct a badly degraded 256 {times} 256 image in as little as 3 seconds. Using all range bins, the algorithm can correct the image in 9 seconds. 4 refs., 2 figs.

Wahl, D.E.; Eichel, P.H.; Jakowatz, C.V. Jr.

1990-01-01

420

A fast, preconditioned conjugate gradient Toeplitz solver  

NASA Technical Reports Server (NTRS)

A simple factorization is given of an arbitrary hermitian, positive definite matrix in which the factors are well-conditioned, hermitian, and positive definite. In fact, given knowledge of the extreme eigenvalues of the original matrix A, an optimal improvement can be achieved, making the condition numbers of each of the two factors equal to the square root of the condition number of A. This technique is to applied to the solution of hermitian, positive definite Toeplitz systems. Large linear systems with hermitian, positive definite Toeplitz matrices arise in some signal processing applications. A stable fast algorithm is given for solving these systems that is based on the preconditioned conjugate gradient method. The algorithm exploits Toeplitz structure to reduce the cost of an iteration to O(n log n) by applying the fast Fourier Transform to compute matrix-vector products. Matrix factorization is used as a preconditioner.

Pan, Victor; Schrieber, Robert

1989-01-01

421

Fractional calculus and morphogen gradient formation  

NASA Astrophysics Data System (ADS)

Some microscopic models for reactive systems where the reaction kinetics is limited by subdiffusion are described by means of reaction-subdiffusion equations where fractional derivatives play a key role. In particular, we consider subdiffusive particles described by means of a Continuous Time Random Walk (CTRW) model subject to a linear (first-order) death process. The resulting fractional equation is employed to study the developmental biology key problem of morphogen gradient formation for the case in which the morphogens are subdiffusive. If the morphogen degradation rate (reactivity) is constant, we find exponentially decreasing stationary concentration profiles, which are similar to the profiles found when the morphogens diffuse normally. However, for the case in which the degradation rate decays exponentially with the distance to the morphogen source, we find that the morphogen profiles are qualitatively different from the profiles obtained when the morphogens diffuse normally.

Yuste, Santos Bravo; Abad, Enrique; Lindenberg, Katja

2012-12-01

422

Gradient ion chromatography of inositol phosphates.  

PubMed

Inositol phosphates including phytic acid were separated in 30 min by gradient ion chromatography with postcolumn derivatization. All four pentakisphosphates were resolved, while four tetrakisphosphate peaks were detected. The limits of detection for all polyphosphates, including tris- and bisphosphates, were between 1 and 2 nmol. The method was used to compare nonenzymatic dephosphorylation of inositol hexakisphosphate at pH 4.0 versus pH 10.8. The only pentakisphosphate detected in calf brains was identified as myo-inositol 1,3,4,5,6-pentakisphosphate. The major pentakisphosphate in raw soybean seeds was myo-inositol 1,2,4,5,6-pentakisphosphate of unknown enantiomeric composition, while lesser amounts of myo-inositol 1,2,3,4,5-pentakisphosphate of unknown enantiomeric composition, myo-inositol 1,2,3,4,6-pentakisphosphate, and myo-inositol 1,3,4,5,6-pentakisphosphate were also present. PMID:3245565

Phillippy, B Q; Bland, J M

1988-11-15

423

Understanding Nanoscale Temperature Gradients in Magnetic Nanocontacts  

NASA Astrophysics Data System (ADS)

We have determined the temperature profile in magnetic nanocontacts under applied current densities typical of spin-torque oscillators (˜108A/cm2). The study combines experimental measurements of the electrical and magnetic properties of the nanocontacts and full three-dimensional simulations of the heat and current flow in these systems. It is found that the quadratic current-induced increase of the resistance due to Joule heating is independent of the applied temperature from 6 to 300 K. In terms of magnetization dynamics, the measured current-induced vortex nucleation, a thermally activated process, is found to be consistent with local temperatures increases of between 147 and 225 K. Simulations reproduce the experimental findings and show that significant thermal gradients exist out to 450 nm from the nanocontact.

Petit-Watelot, S.; Otxoa, R. M.; Manfrini, M.; Van Roy, W.; Lagae, L.; Kim, J.-V.; Devolder, T.

2012-12-01

424

Transformational acoustic metamaterials based on pressure gradients  

E-print Network

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

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

2014-09-18

425

Gradient theory of nucleation in polar fluids  

NASA Astrophysics Data System (ADS)

Gradient theory (GT), a form of density functional theory (DFT), was applied to water, methanol, and ethanol using the cubic perturbed hard body (CPHB) equation of state (EOS). Compared to the standard form of classical nucleation theory (CNT), the GT results for water showed an improved temperature dependence, but the supersaturation dependence was slightly poorer. GT and several forms of CNT were also found to be in good agreement with a single high T molecular dynamics rate for TIP4P water. The rates predicted by GT for methanol and ethanol were improved by several orders of magnitude compared to CNT, but no improvement in the predicted temperature dependence of the rates was found.

Obeidat, Abdalla; Wilemski, Gerald

2006-12-01

426

Large negative velocity gradients in Burgers turbulence.  

PubMed

We consider one-dimensional Burgers equation driven by large-scale white-in-time random force. The tails of the velocity gradients probability distribution function (PDF) are analyzed by saddle point approximation in the path integral describing the velocity statistics. The structure of the saddle-point (instanton), that is, the velocity field configuration realizing the maximum of probability, is studied numerically in details. The numerical results allow us to find analytical solution for the long-time part of the instanton. Its careful analysis confirms the result of Balkovsky et al. [Phys. Rev. Lett. 78, 1452 (1997)] based on short-time estimations that the left tail of PDF has the form ln P(u(x))infinity-/u(x)/(3/2). PMID:11497698

Chernykh, A I; Stepanov, M G

2001-08-01

427

Longitudinal chemical gradients in hot Jupiter atmospheres  

NASA Astrophysics Data System (ADS)

We have built a pseudo two-dimensional (altitude and longitude) model to study the chemistry in the atmosphere of hot Jupiters. Our model considers a vertical column of atmosphere that rotates along the equator, mimicking a superrotating wind. We have applied it to the well known exoplanets HD 209458b and HD 189733b. We find that below a certain pressure level, which may be located somewhere between 10 bar and 10 mbar depending on the molecule, the chemical composition is given by thermochemical equilibrium, while about such level, the dynamical time scales for vertical and horizontal mixing compete producing a complex abundance distribution with altitude and longitude. A main conclusion of our study is that some molecules such as CO, H2O, and N2 maintain rather constant abundances with altitude and longitude while others such as CO2, CH4, NH3, and HCN show important abundance gradients as a function of longitude.

Agundez, M.; Parmentier, V.; Venot, O.; Selsis, F.

2013-09-01

428

High Gradient Wakefields in Dielectric Loaded Structures  

SciTech Connect

Dielectric loaded wakefield structures have potential to be used as high gradient accelerator components. Using the high current drive beam at the Argonne Wakefield Accelerator Facility, we employed cylindrical dielectric loaded wakefield structures to generate accelerating fields of up to 86 MV/m, at 10 GHz. Short electron bunches of up to 86 nC are used to drive these fields, either as single bunches or as bunch trains. The structures consist of cylindrical ceramic tubes (cordierite) with a dielectric constant of 4.76, inserted into cylindrical copper waveguides. These standing-wave structures have a field probe near the outer diameter of the dielectric, in order to sample the RF fields generated by the electron bunches. Monitoring the field probe signal serves to verify the absence of electric breakdown in the structures. MAFIA simulations are used to calculate the amplitude of the fields generated by the traversing electrons bunches.

Conde, M. E.; Franchini, F.; Gai, W.; Konecny, R.; Liu, W.; Power, J. G.; Yusof, Z. [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Antipov, S.; Gao, F.; Wang, H. [Illinois Institute of Technology, 3300 South Federal Street, Chicago, IL 60616 (United States); Jing, C. [Euclid TechLabs, 5900 Harper Road, Solon, OH 44139 (United States)

2006-11-27

429

High gradient wakefields in dielectric loaded structures.  

SciTech Connect

Dielectric loaded wakefield structures have potential to be used as high gradient accelerator components. Using the high current drive beam at the Argonne Wakefield Accelerator Facility, we employed cylindrical dielectric loaded wakefield structures to generate accelerating fields of up to 86 MV/m, at 10 GHz. Short electron bunches of up to 86 nC are used to drive these fields, either as single bunches or as bunch trains. The structures consist of cylindrical ceramic tubes (cordierite) with a dielectric constant of 4.76, inserted into cylindrical copper waveguides. These standing-wave structures have a field probe near the outer diameter of the dielectric, in order to sample the RF fields generated by the electron bunches. Monitoring the field probe signal serves to verify the absence of electric breakdown in the structures. MAFIA simulations are used to calculate the amplitude of the fields generated by the traversing electrons bunches.

Conde, M.E.; Franchini, F.; Gai, W.; Konecny, R.; Power, J.G.; Yusof, Z.; Liu, W.; Jing, C.; Antipov, S.; Wang, H.; High Energy Physics; Euclid Techlabs, LLC; IIT

2006-01-01

430

Transformational acoustic metamaterials based on pressure gradients  

E-print Network

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

García-Meca, C; Barceló, C; Jannes, G; Sánchez-Dehesa, J; Martínez, A

2014-01-01

431

Experimental demonstration of gradient index plasmonics  

NASA Astrophysics Data System (ADS)

Plasmonics is an emerging field essential for bridging nanoelectronics and diffraction-limited photonics. One central objective of plasmonics research is modifying the propagation of surface plasmon polaritons (SPPs) in order to implement diverse functionalities in the context of two-dimensional optics. Here, we demonstrate an effective approach to manipulate SPPs by adiabatically tailoring the topology of a dielectric layer adjacent to a metal surface using grey-scale lithography. In such a way, we are able to continuously modify the propagation constant of SPPs, analogous to traditional gradient index optics. Applying this method, we design and experimentally demonstrate two different devices: a plasmonic Luneburg lens to focus SPPs and a plasmonic Eaton lens to bend SPPs.ootnotetextT. Zentgraf*, Y. Liu*, M. H. Mikkelsen*, J. Valentine, X. Zhang, Submitted, (2010) Our approach has the potential to achieve low-loss functional plasmonic elements and provides a scheme to realize more complex structures using transformation optics.

Mikkelsen, Maiken H.; Zentgraf, Thomas; Liu, Yongmin; Valentine, Jason; Zhang, Xiang

2011-03-01

432

High Gradient Wakefields in Dielectric Loaded Structures  

NASA Astrophysics Data System (ADS)

Dielectric loaded wakefield structures have potential to be used as high gradient accelerator components. Using the high current drive beam at the Argonne Wakefield Accelerator Facility, we employed cylindrical dielectric loaded wakefield structures to generate accelerating fields of up to 86 MV/m, at 10 GHz. Short electron bunches of up to 86 nC are used to drive these fields, either as single bunches or as bunch trains. The structures consist of cylindrical ceramic tubes (cordierite) with a dielectric constant of 4.76, inserted into cylindrical copper waveguides. These standing-wave structures have a field probe near the outer diameter of the dielectric, in order to sample the RF fields generated by the electron bunches. Monitoring the field probe signal serves to verify the absence of electric breakdown in the structures. MAFIA simulations are used to calculate the amplitude of the fields generated by the traversing electrons bunches.

Conde, M. E.; Antipov, S.; Franchini, F.; Gai, W.; Gao, F.; Jing, C.; Konecny, R.; Liu, W.; Power, J. G.; Wang, H.; Yusof, Z.

2006-11-01

433

Precision temperature gradient measurements on window glass  

NASA Technical Reports Server (NTRS)

Surface temperature gradients were measured with miniature thermocouples installed in a 58.5 cm (23-inch) square window. Test measurements at 25 locations were made under vacuum and with the window operating in radiant heat transfer mode. The analysis of thermocouple design and installation is presented along with a lead wire routing scheme to allow for both differential and absolute temperature measurements while using a minimum number of signal feedthru paths through the test chamber wall. Typical test data and operational precautions are presented along with the accuracy analysis for installation effects and measurement effects to support differential temperature measurement precision values of + or - 0.06 C RMS + or - 0.1 F RMS).

Mikk, G.; Petrie, W.

1977-01-01

434

Microfluidic quadrupole and floating concentration gradient  

PubMed Central

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

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

2014-01-01

435

High-gradient compact linear accelerator  

DOEpatents

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

Carder, Bruce M. (205 Rogue River Hwy., Gold Hill, OR 97525)

1998-01-01

436

High-gradient compact linear accelerator  

SciTech Connect

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

Carder, B.M.

1995-12-31

437

Supply Chain The effective supply chain has become a new organizational and operational  

E-print Network

MBA in Supply Chain Management #12;The effective supply chain has become a new organizational and operational model for the information age. Supply chain management is a business process that enables­Newark and New Brunswick, which offers an MBA concentration and PhD in supply chain management

Lin, Xiaodong

438

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

E-print Network

Supply Chain Management and Marketing Sciences Maximizing the Interface between Supply Chain-Enhanced Supply Chain Management Program is Key to its Success p.2 Six MBA Students Awarded Scholarships from howmarketinghadtoadapthowitcommunicatedwith #12;Supply Chain Management and Marketing Sciences 2 by Franco Libunao, Neha Mukherjee

Lin, Xiaodong

439

A Network Economic Model for Supply Chain versus Supply Chain Competition  

E-print Network

inequality problem. #12;Introduction To date, the major focus of the supply chain management literature has. This also reflects the philosophy that the firms' cooperation quest in supply chain management is to makeA Network Economic Model for Supply Chain versus Supply Chain Competition Ding Zhang School

Nagurney, Anna

440

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

E-print Network

Supply Chain Management and Marketing Sciences Maximizing the Interface between Supply Chain. Lyons is a research professor in the supply chain environmental management and archaeology departments Highlights Council of Supply Chain Management Professionals gives scholarships to RBS Students p.2 Roundtable

Lin, Xiaodong

441

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

E-print Network

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

Nagurney, Anna

442

Bilinear temperature gradient focusing in a hybrid PDMS/glass microfluidic chip integrated with planar heaters for generating temperature gradients.  

PubMed

Temperature gradient focusing (TGF) is a counterflow gradient focusing technique, which utilizes a temperature gradient across a microchannel or capillary to separate analytes. With an appropriate buffer, the temperature gradient creates a gradient in both the electric field and electrophoretic velocity. Combined with a bulk counter flow, ionic species concentrate at a unique point where the total velocity sums to zero and separate from each other. Scanning TGF uses varying bulk flow so that a large number of analytes that have large differences in electrophoretic mobility can be sequentially focused and passed by a single detection point. Up to now, scanning TGF examples have been performed using a linear temperature gradient which has limitations in improving peak capacity and resolution at the same time. In this work, we develop a bilinear temperature gradient along the separation channel that improves both peak capacity and separation resolution simultaneously. The temperature profile along the channel consists of a very sharp gradient used to preconcentrate the sample followed by a shallow gradient that increases separation resolution. A specialized design is developed for the heaters to achieve the bilinear profile using both analytical and numerical modeling. The heaters are integrated onto a hybrid PDMS/glass chip fabricated using conventional sputtering and soft-lithography techniques. Separation performance is characterized by separating several different dyes and amino acids that have close electrophoretic mobilities. Experiments show a dramatic improvement in peak capacity and resolution in comparison to the standard linear temperature gradient. PMID:22404579

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

2012-03-20

443

Optimal control of microstructural gradients during composite fabrication  

SciTech Connect

Microstructural observations of plasma sprayed thick films of nickel and laminated composites of Al{sub 2}O{sub 3}/MoSi{sub 2}, have been made. It is shown that the lack of control of temperature gradients across the thickness of the deposit results in enormous microstructural gradients. Computational algorithms have been developed which trace the development of temperature gradients across the deposit thickness during rapid solidification by plasma processing. Based on reduced order models of heat transfer, a control problem is set up in order to minimize the temperature gradients across the deposit thickness, which consequently results in the desired microstructure and minimum residual stresses. The impact of the lack of such a temperature gradient control on microstructural evolution of the deposit is investigated, and the necessity of temperature gradient control is emphasized.

Bhatkal, R.; Fradkov, V.; Kyriakopoulos, K.; Stephanou, H.E.; Rajan, K. [Rensselaer Polytechnic Institute, Troy, NY (United States)

1993-12-31

444

Gradient-zone erosion by extraction in solar ponds  

SciTech Connect

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

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

1995-05-01

445

Design of a High Thermal Gradient Bridgman Furnace  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

446

RRab Lyrae metallicity gradient in the Galactic bulge  

NASA Astrophysics Data System (ADS)

Aims: We revisit the presence and significance of the Galactic bulge metallicity gradients, using the OGlE-III RR Lyrae sample. Methods: We implemented a Monte Carlo simulation to account for observational uncertainties and systematic errors to test the presence, significance, and spatial variation of RR Lyr photometric metallicity gradients within the Galactic bulge. Furthermore, we take special consideration to identify and account for possible observational and statistical biases, which may introduce an apparent metallicity gradient into the sample. Results: We find a mean Galactic bulge RRab metallicity of -0.97 ± 0.29 dex, a global radial metallicity gradient of -0.016 ± 0.008 dex Kpc-1, and a global vertical metallicity gradient of -0.063 ± 0.013 dex Kpc-1. Furthermore, neither the global radial nor vertical gradients can be explained by random chance, unjustified extrapolation of the metallicity calibration law, or induced by a Malmquist bias.

Sans Fuentes, S. A.; De Ridder, J.

2014-11-01

447

COMPARISON OF GKS CALCULATED CRITICAL ION TEMPERATURE GRADIENTS AND ITG GROWTH RATES TO DIII-D MEASURED GRADIENTS AND DIFFUSIVITIES  

SciTech Connect

OAK-B135 The gyrokinetic equations predict that various drift type waves or modes can be unstable in a tokamak. For some of these modes, such as the ion temperature gradient (ITG) mode and the electron temperature gradient mode, there exists a critical gradient, above which the mode is unstable. Since the existence of unstable modes can cause increased transport, plasmas which are centrally heated tend to increase in temperature gradient until the modes become unstable. Under some conditions the increased transport can fix the gradient at the critical value. here they present a comparison between the measured ion temperature gradients and the critical gradient as calculated by a gyrokinetic linear stability (GKS) code. They also present the maximum linear growth rate as calculated by this code for comparison to experimentally derived transport coefficients. The results show that for low confinement mode (L-mode) discharges, the measured ion temperature gradient is significantly greater than the GKS calculated critical gradient over a large region of the plasma. This is the same region of the plasma where the ion thermal diffusivity is large. For high confinement mode (H-mode) discharges the ion temperature gradient is closer to the critical gradient, but often still greater than the critical gradient over some region. For the best H-mode discharges, the ion temperature is less than or equal to the critical gradient over the whole plasma. In general they find that the position in the plasma where the ion thermal diffusivity starts to increase rapidly is where the maximum linear growth rate is greater than the E x B shearing rate.

BAKER,DR; STAEBLER,GM; PETTY,CC; GREENFIELD,CM; LUCE,TC

2003-04-01

448

Force chains, microelasticity, and macroelasticity.  

PubMed

It has been claimed that quasistatic granular materials, as well as nanoscale materials, exhibit departures from elasticity even at small loadings. It is demonstrated, using 2D and 3D models with interparticle harmonic interactions, that such departures are expected at small scales [below O(100) particle diameters], at which continuum elasticity is invalid, and vanish at large scales. The models exhibit force chains on small scales, and force and stress distributions which agree with experimental findings. Effects of anisotropy, disorder, and boundary conditions are discussed as well. PMID:12190469

Goldenberg, C; Goldhirsch, I

2002-08-19

449

Force Chains, Microelasticity, and Macroelasticity  

NASA Astrophysics Data System (ADS)

It has been claimed that quasistatic granular materials, as well as nanoscale materials, exhibit departures from elasticity even at small loadings. It is demonstrated, using 2D and 3D models with interparticle harmonic interactions, that such departures are expected at small scales [below O(100) particle diameters], at which continuum elasticity is invalid, and vanish at large scales. The models exhibit force chains on small scales, and force and stress distributions which agree with experimental findings. Effects of anisotropy, disorder, and boundary conditions are discussed as well.

Goldenberg, C.; Goldhirsch, I.

2002-08-01

450

Noncommutative Torus from Fibonacci Chains via Foliation  

E-print Network

We classify the Fibonacci chains (F-chains) by their index sequences and construct an approximately finite dimensional (AF) $C^*$-algebra on the space of F-chains as Connes did on the space of Penrose tiling. The K-theory on this AF-algebra suggests a connection between the noncommutative torus and the space of F-chains. A noncommutative torus, which can be regarded as the $C^*$-algebra of a foliation on the torus, is explicitly embedded into the AF-algebra on the space of F-chains. As a counterpart of that, we obtain a relation between the space of F-chains and the leaf space of Kronecker foliation on the torus using the cut-procedure of constructing F-chains.

Hyeong-Chai Jeong; Eunsang Kim; Chang-Yeong Lee

2000-08-22

451

Effects of pressure gradients on turbulent premixed flames  

NASA Technical Reports Server (NTRS)

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

Veynante, D.; Poinsot, T.

1995-01-01

452

A scaled nonlinear conjugate gradient algorithm for unconstrained optimization  

Microsoft Academic Search

The best spectral conjugate gradient algorithm by (Birgin, E. and Martínez, J.M., 2001, A spectral conjugate gradient method for unconstrained optimization. Applied Mathematics and Optimization, 43, 117–128). which is mainly a scaled variant of (Perry, J.M., 1977, A class of Conjugate gradient algorithms with a two step varaiable metric memory, Discussion Paper 269, Center for Mathematical Studies in Economics and

Neculai Andrei

2008-01-01

453

Compressed ion temperature gradient turbulence in diverted tokamak edge  

Microsoft Academic Search

It is found from a heat-flux-driven full-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 without a pedestal structure, hence the normalized ion temperature gradient parameter ?i=(d log Ti\\/dr)\\/(d log n\\/dr) varies strongly from high (>4 at

C. S. Chang; S. Ku; P. H. Diamond; Z. Lin; S. Parker; T. S. Hahm; N. Samatova

2009-01-01

454

Evaluation of local geothermal gradients on North Slope of Alaska  

SciTech Connect

The US Geological Survey is conducting a detailed assessment of worldwide natural-gas hydrate occurrences. Thermodynamic conditions controlling hydrate occurrences of northern Alaska have been examined. Pressure and temperature conditions on the North Slope indicate that hydrates would be potentially stable both above and below the permafrost base. Geothermal gradients needed to predict the thickness of the hydrate stability zone are not easily obtained. A survey of preliminary data suggested wide variations in averaged regional geothermal gradients across the North Slope. To evaluate regional variations of geothermal gradients, 2 techniques were employed to calculate local gradients. The first method used bottom-hole temperatures recorded during successive wireline logging runs and corrected by Horner crossplots to determine undisturbed formation temperatures. The Horner crossplot method requires a series of recorded bottom-hole temperatures. However, in most of the North Slope production wells, only 2-3 log runs are conducted per well, thus limiting the number of bottom-hole temperatures. To overcome this limiting factor, a second method has been developed to evaluate local geothermal gradients. This new technique uses permafrost depths delineated from well-log data to project geothermal gradients. Gradients within the permafrost zone have been projected from the base of permafrost, which is in equilibrium at -1/sup 0/C. A series of mean ground temperatures has been used to project the upper extent of each gradient. Geothermal gradients change abruptly at the base of the permafrost. In order to calculate the gradient below the permafrost base, a constant generated from subsurface temperature data was used to correct for this change in geothermal gradient. Data from 398 wells were examined by each method to develop a series of geothermal gradient maps.

Collett, T.S.

1985-02-01

455

Engineering chemoattractant gradients using controlled release polysaccharide microspheres  

E-print Network

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

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

2012-01-01

456

Magnetic resonance imaging of rodent tumors using radiofrequency gradient echoes.  

PubMed

This paper evaluates the use of radiofrequency (RF) magnetic field gradient echoes to provide contrast in magnetic resonance (MR) images of model tumors. Decay of RF gradient echoes as a function of evolution time was measured and sensitivity of the decay to changes in blood pressure was evaluated. Previous investigators have demonstrated that static field (B0) gradient echoes provide MR image contrast which is sensitive to the rate of self-diffusion of tissue water and may also be sensitive to the rate of tissue perfusion. Gradient echoes produced by RF magnetic field gradients provide a useful alternative to the conventional B0 methods. Unlike B0 gradient echoes RF gradient echoes are relatively insensitive to local magnetic susceptibility gradients and to magnetic field gradients produced by eddy currents. Differences between the two methods may be particularly significant for studies of tumors where large concentrations of deoxyhemoglobin and other paramagnetic substances may cause significant susceptibility gradients. Mammary adenocarcinomas subcutaneously implanted in the flanks of female Fisher rats were studied. Magnetic resonance experiments were performed at 2 T. A surface coil was used to provide an RF gradient and to excite and detect signals from the tumors. The decay of echo amplitude as a function of evolution time was measured and the decay at short and long evolution times was analyzed independently to calculate two apparent diffusion coefficients (ADCs). The preparation was extremely stable and the standard error for 10 consecutive measurements of gradient echo amplitude made over 30-60 min with an RF gradient strength of 50 kHz/cm, gradient duration of 1 ms (i.e., 50 cycles/cm), and echo evolution time (td) of 1 s was generally +/- 0.8%. The ADC calculated from the decay at short evolution times was approximately 3 x 10(-5) cm2/s. The ADC calculated from the decay at longer evolution times was approximately 0.5 x 10(-5) cm2/s. Both ADCs decreased immediately following sacrifice and administration of Hydralazine. The experiments demonstrate that measurements of RF gradient echo amplitudes in tumors can be made in vivo with a high degree of reproducibility and suggest that RF gradient echo amplitudes are sensitive to acute physiological changes in tumors. This method may be useful for characterization of tumors and prediction and monitoring of effects of therapeutic agents. PMID:7968288

Karczmar, G S; River, J N; Goldman, Z; Li, J; Weisenberg, E; Lewis, M Z; Liu, K

1994-01-01

457

Effective Gradients in Porous Media Due to Susceptibility Differences  

PubMed

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

Hürlimann

1998-04-01

458

The LHC Lead Injector Chain  

E-print Network

A sizeable part of the LHC physics programme foresees lead-lead collisions with a design luminosity of 1027 cm-2 s-1. This will be achieved after an upgrade of the ion injector chain comprising Linac3, LEIR, PS and SPS machines [1,2]. Each LHC ring will be filled in 10 min by almost 600 bunches, each of 7×107 lead ions. Central to the scheme is the Low Energy Ion Ring (LEIR) [3,4], which transforms long pulses from Linac3 into high-brilliance bunches by means of multi-turn injection, electron cooling and accumulation. Major limitations along the chain, including space charge, intrabeam scattering, vacuum issues and emittance preservation are highlighted. The conversion from LEAR (Low Energy Antiproton Ring) to LEIR involves new magnets and power converters, high-current electron cooling, broadband RF cavities, and a UHV vacuum system with getter (NEG) coatings to achieve a few 10-12 mbar. Major hardware changes in Linac3 and the PS are also covered. An early ion scheme with fewer bunches (but each at nominal...

Beuret, A; Blas, A; Burkhardt, H; Carli, Christian; Chanel, M; Fowler, A; Gourber-Pace, M; Hancock, S; Hourican, M; Hill, C E; Jowett, John M; Kahle, K; Küchler, D; Lombardi, A M; Mahner, E; Manglunki, Django; Martini, M; Maury, S; Pedersen, F; Raich, U; Rossi, C; Royer, J P; Schindl, Karlheinz; Scrivens, R; Sermeus, L; Shaposhnikova, Elena; Tranquille, G; Vretenar, Maurizio; Zickler, T

2004-01-01

459

Elicited responding in chain schedules.  

PubMed Central

An omission procedure was employed to study elicited pecking in the first component of a two-component chain schedule. Both components were fixed-interval schedules correlated with colored keylights. The first response following the initial-link schedule produced a second fixed-interval schedule. We studied several fixed-interval lengths in two conditions: a standard response-dependent condition and an omission-contingent condition. The omission-contingent condition differed from the response-dependent condition in that responses during the initial fixed interval terminated the trial (omitting the terminal component and grain). If the terminal component was not omitted, a response following the terminal link's requirement produced 4-s access to grain. Pigeons responded during more than 70% of the initial links in the omission-contingent condition and responded during more than 90% of the initial links in the response-dependent condition. In general, rates of responding were consistent with the percentage data. The responding in the omission condition suggests that there may be elicited pecking, in chain schedules using pigeons, that is not the result of contingent conditioned reinforcement. PMID:1774540

Dougherty, D M; Lewis, P

1991-01-01

460

Soil Fertility Gradient in the Restinga Ecosystem  

NASA Astrophysics Data System (ADS)

The restinga ecosystem (coastal plain vegetation) can be termed as a set of plant communities that suffer strong influenced by fluvial and marine factors and is characterized as an ecosystem of great biological diversity, therefore, represents areas of great importance in the context of ecological preservation. The degradation processes from many forms of anthropogenic disturbances that has taken place since the colonization of the country, made studies on the characterization and dynamics of soil fertility of these areas even more important in relation to the maintenance of its biodiversity and conservation. The sites studied were the Cardoso Island and Comprida Island, and in these, we analyzed four physiognomies, restinga, low restinga, dune and antedune (from continent to ocean). Chemical analyses were performed and soil salinity in these areas in depths 0-5; 0-10; 0-20; 20-40; 40-60 cm. In all soils the cationic exchange capacity was intimately associated with the concentration of soil organic matter, which makes this parameter essential to the maintenance of soil fertility of these areas; in more superficial layers (0-20 cm) there was an increase of pH and base saturation and decline of organic matter, aluminum saturation and cationic exchange capacity in the nearby sea, physiognomies what determines the existence of fertility gradient towards the continent-coast; restinga forests showed a chemical standard that is heavily marked by sandy texture, high degree of leaching, nutrient poverty, low base saturation, high saturation by aluminum and acidity, opposite conditions to soils of the dunes and antedunes, with the exception of sandy texture; despite the existence of a chemical gradient of fertility among the physiognomies studied it is possible to determine the soil acts more strongly as a physical support than as provider of fertility; as for salinity, soil collected in Cardoso Island did not present salinity in any depth, a fact which can be explained due to intense washing these soils are exposed and associated with highly sandy texture what favors the leaching of salts throughout the profile. Comprida Island soils presented salinity in some ante dune that can be explained due to the geographical position that determines a system of frequent wetting of the soil by the sea water and thus facilitating the accumulation of salts in the profile.

América Castelar da Cunha, Joana; Casagrande, José Carlos; Soares, Marcio Roberto; Martins Bonilha, Rodolfo

2013-04-01

461

Service Oriented Approach for Autonomous Exception Management in Supply Chains  

E-print Network

Service Oriented Approach for Autonomous Exception Management in Supply Chains Armando Business Process to support Autonomous Exception Management in Supply chains. Keywords: Supply Chain and consequently this triggers a rescheduling task. Current Supply Chain Management Systems lack of systematic

Paris-Sud XI, Université de

462

Discontinuous and continuous purification of single-chain antibody fragments using immobilized metal ion affinity chromatography.  

PubMed

This work describes the adsorption-desorption behavior of a histidine-tagged single-chain Fragment variable antibody (D1.3 scFv) on a commercial immobilized metal ion affinity chromatography (IMAC) column. A clarified cell culture supernatant originating from Bacillus megaterium was characterized using single column experiments in a pH-gradient elution mode. The cell culture supernatant containing the antibody fragment D1.3 scFv could be treated in the chromatographic separation process as a pseudo-binary mixture. Adsorption equilibrium constants of the antibody fragment fraction (ABF) and the non-specifically retained protein impurity fraction (IMP) were determined experimentally at constant pH by reinjecting pulses of pooled fractions collected in preliminary batch gradient elution runs. Based on the estimated adsorption equilibrium constants a possible multicolumn open-loop three-zone two-step pH-gradient simulated moving bed (SMB) process is suggested and designed, which possesses the potential to isolate continuously the antibody fragment fraction (ABF) containing the single-chain antibody fragment D1.3 scFv. PMID:22985797

Martínez Cristancho, Carlos Andrés; David, Florian; Franco-Lara, Ezequiel; Seidel-Morgenstern, Andreas

2013-01-20

463

Continuous chain bit with downhole cycling capability  

DOEpatents

A continuous chain bit for hard rock drilling is capable of downhole cycling. A drill head assembly moves axially relative to a support body while the chain on the head assembly is held in position so that the bodily movement of the chain cycles the chain to present new composite links for drilling. A pair of spring fingers on opposite sides of the chain hold the chain against movement. The chain is held in tension by a spring-biased tensioning bar. A head at the working end of the chain supports the working links. The chain is centered by a reversing pawl and piston actuated by the pressure of the drilling mud. Detent pins lock the head assembly with respect to the support body and are also operated by the drilling mud pressure. A restricted nozzle with a divergent outlet sprays drilling mud into the cavity to remove debris. Indication of the centered position of the chain is provided by noting a low pressure reading indicating proper alignment of drilling mud slots on the links with the corresponding feed branches.

Ritter, Don F. (Albuquerque, NM); St. Clair, Jack A. (Albuquerque, NM); Togami, Henry K. (Albuquerque, NM)

1983-01-01

464

The triple-A supply chain.  

PubMed

Building a strong supply chain is essential for business success. But when it comes to improving their supply chains, few companies take the right approach. Many businesses work to make their chains faster or more cost-effective, assuming that those steps are the keys to competitive advantage. To the contrary: Supply chains that focus on speed and costs tend to deteriorate over time. The author has spent 15 years studying more than 60 companies to gain insight into this and other supply chain dilemmas. His conclusion: Only companies that build supply chains that are agile, adaptable, and aligned get ahead of their rivals. All three components are essential; without any one of them, supply chains break down. Great companies create supply chains that respond to abrupt changes in markets. Agility is critical because in most industries, both demand and supply fluctuate rapidly and widely. Supply chains typically cope by playing speed against costs, but agile ones respond both quickly and cost-efficiently. Great companies also adapt their supply networks when markets or strategies change. The best supply chains allow managers to identify structural shifts early by recording the latest data, filtering out noise, and tracking key patterns. Finally, great companies align the interests of the partners in their supply chains with their own. That's important because every firm is concerned solely with its own interests. If its goals are out of alignment with those of other partners in the supply chain, performance will suffer. When companies hear about the triple-A supply chain, they assume that building one will require increased technology and investment. But most firms already have the infrastructure in place to create one. A fresh attitude alone can go a long way toward making it happen. PMID:15559579

Lee, Hau L

2004-10-01

465

Nanoparticle-driven orientation transition and soft-shear alignment in diblock copolymer films via dynamic thermal gradient field.  

PubMed

Sharp dynamic thermal gradient (?T ? 45 °C mm(-1)) field-driven assembly of cylinder-forming block copolymer (c-BCP) films filled with PS-coated gold nanoparticles (AuNPs; dNP ? 3.6 nm, ?NP ? 0-0.1) is studied. The influence of increasing AuNP loading fraction on dispersion and assembly of AuNPs within c-BCP (PS-PMMA) films is investigated via both static and dynamic thermal gradient fields. With ?NP increasing, a sharp transition from vertical to random in-plane horizontal cylinder orientation is observed due to enrichment of AuNPs at the substrate side and favorable interaction of PMMA chains with gold cores. Furthermore, a detachable capping elastomer layer can self-align these random oriented PMMA microdomains into unidirectional hybrid AuNP/c-BCP nanolines, quantified with an alignment order parameter, S. PMID:24105959

Zhang, Ren; Singh, Gurpreet; Dang, Alei; Dai, Lu; Bockstaller, Michael R; Akgun, Bulent; Satija, Sushil; Karim, Alamgir

2013-10-01

466

Environmental inequality and circulatory disease mortality gradients  

PubMed Central

Study objective: Studies in Europe and North America have reported that living in a disadvantaged neighbourhood is associated with an increased incidence of coronary heart disease. The aim of this study was to test the hypotheses that exposure to traffic and air pollution might account for some of the socioeconomic differences in mortality rates in a city where residents are covered by universal health insurance. Design: Cohort mortality study. Individual postal codes used to derive: (1) socioeconomic status from census data; (2) mean air pollution levels from interpolation between governmental monitoring stations; (3) proximity to traffic from the geographical information system. Analysis conducted with Cox proportional hazards models. Setting: Hamilton Census Metropolitan Area, Ontario, Canada, on the western tip of Lake Ontario (population about 480 000). Participants: 5228 people, aged 40 years or more, identified from register of lung function laboratory at an academic respirology clinic between 1985 and 1999. Main results: Circulatory disease (cardiovascular and stroke) mortality rates were related to measures of neighbourhood deprivation. Circulatory disease mortality rates were also associated with indices of long term ambient pollution at the subjects' residences (relative risk 1.06, 1.00 to 1.13) and with proximity to traffic (relative risk 1.40, 1.08 to 1.81). Subjects in more deprived neighbourhoods had greater exposure to ambient particulate and gaseous pollutants and to traffic. Conclusions: At least some of the observed social gradients in circulatory mortality arise from inequalities in environmental exposure to background and traffic air pollutants. PMID:15911644

Finkelstein, M.; Jerrett, M.; Sears, M.

2005-01-01

467

Hydraulic gradient control for groundwater contaminant removal  

NASA Astrophysics Data System (ADS)

The Rocky Mountain Arsenal near Denver, Colorado, U.S.A., is used as a realistic setting for a hypothetical test of a procedure that plans the hydraulic stabilization and removal of a groundwater contaminant plume. A two-stage planning procedure successfully selects the best wells and their optimal pumping/recharge schedules to contain the plume while a well or system of wells within the plume removes the contaminated water. In stage I, a combined groundwater flow and solute transport model is used to simulate contaminant removal under an assumed velocity field. The result is the approximated plume boundary location as a function of time. In stage II, a linear program, which includes a groundwater flow model as part of the set of constraints, determines the optimal well selection and their optimal pumping/recharge schedules by minimizing total pumping and recharge. The simulation—management model eliminates wells far from the plume perimeter and activates wells near the perimeter as the plume decreases in size. This successfully stablizes the hydraulic gradient during aquifer cleanup.

Atwood, Dorothy Fisher; Gorelick, Steven M.

1985-01-01

468

Predicting shifts in generalization gradients with perceptrons.  

PubMed

Perceptron models have been used extensively to model perceptual learning and the effects of discrimination training on generalization, as well as to explore natural classification mechanisms. Here, we assess the ability of existing models to account for the time course of generalization shifts that occur when individuals learn to distinguish sounds. A set of simulations demonstrates that commonly used single-layer and multilayer perceptron networks do not predict transitory shifts in generalization over the course of training but that such dynamics can be accounted for when the output functions of these networks are modified to mimic the properties of cortical tuning curves. The simulations further suggest that prudent selection of stimuli and training criteria can allow for more precise predictions of learning-related shifts in generalization gradients in behavioral experiments. In particular, the simulations predict that individuals will show maximal peak shift after different numbers of trials, that easier contrasts will lead to slower development of shifted peaks, and that whether generalization shifts persist or dissipate will depend on which stimulus dimensions individuals use to distinguish stimuli and how those dimensions are neurally encoded. PMID:21983938

Wisniewski, Matthew G; Radell, Milen L; Guillette, Lauren M; Sturdy, Christopher B; Mercado, Eduardo

2012-06-01

469

Genotyping on a Thermal Gradient DNA Chip  

PubMed Central

Silicon-based chips with discrete, independently temperature-controlled islands have been developed for use in DNA microarray hybridization studies. Each island, containing a heater made of a diffusion layer and a temperature sensor based on a p–n junction, is created on a silicon dioxide/nitride surface by anisotropic etching. Different reactive groups are subsequently added to the surface of the islands, and allele-specific oligonucleotide probes are attached to discrete spots on the chip. Hybridization is performed with Cy5-tagged single-stranded targets derived by PCR from genomic DNA. Results are assessed by measuring fluorescence of bound dye-tagged targets after hybridization and washing. Temperatures at each island can be set at different values to obtain optimal distinction between perfect matches and mismatches. This approach facilitates definition of optimal temperatures for probe/target annealing and for distinction between perfectly matched versus mismatched solution-phase targets. The thermal gradient DNA chips were then tested for genotyping, and the results for four different loci in two genes are presented. Unambiguous typing was achieved for clinically relevant loci within the factor VII and hemochromatosis genes. PMID:12618377

Kajiyama, Tomoharu; Miyahara, Yuji; Kricka, Larry J.; Wilding, Peter; Graves, David J.; Surrey, Saul; Fortina, Paolo

2003-01-01

470

Evolution of slanted edge gradient SFR measurement  

NASA Astrophysics Data System (ADS)

The well-established Modulation Transfer Function (MTF) is an imaging performance parameter that is well suited to describing certain sources of detail loss, such as optical focus and motion blur. As performance standards have developed for digital imaging systems, the MTF concept has been adapted and applied as the spatial frequency response (SFR). The international standard for measuring digital camera resolution, ISO 12233, was adopted over a decade ago. Since then the slanted edge-gradient analysis method on which it was based has been improved and applied beyond digital camera evaluation. Practitioners have modified minor elements of the standard method to suit specific system characteristics, unique measurement needs, or computational shortcomings in the original method. Some of these adaptations have been documented and benchmarked, but a number have not. In this paper we describe several of these modifications, and how they have improved the reliability of the resulting system evaluations. We also review several ways the method has been adapted and applied beyond camera resolution.

Williams, Don; Burns, Peter D.

2014-01-01

471

Gradient drift eigenmodes in the equatorial electrojet  

NASA Technical Reports Server (NTRS)

The problem of kilometer-scale irregularities in the daytime equatorial electrojet is revisited by means of an eigenmode analysis of the gradient drift instability. Realistic physical parameters are used, including the modeled altitude variations of ion and electron collision frequencies and mobilities. The full fourth-order system of two coupled differential equations (each of second order) for the denisty and electrostatic potential perturbations is solved numerically by a relaxation technique. Under some approximations, the fourth-order system can be shown to reduce to a second-order differential equation for the perturbed potential or density. The latter is solved using a shooting technique and provides initial guesses for numerical solutions to the full problem. It is shown that the linear growth rate peaks for kilometer-scale waves, contrary to the findings of recent initial-value studies. This occurs because the equilibrium velocity shear is much more effective as a damping mechanism for short-wavelength modes than it is for the longer, kilometer-scale modes. These results provide a natural qualitative explanation for the observed dominance of kilometer-scale structures in the daytime electrojet spectrum.

Wang, X.-H.; Bhattacharjee, A.

1994-01-01

472

Climatic gradients of arms race coevolution.  

PubMed

In nature, spatiotemporally dynamic coevolutionary processes play major roles in the foundation and maintenance of biodiversity. Here, we examined the arms race coevolution involving a seed-eating weevil with a long snout and its camellia plant host with a thick fruit coat (pericarp) throughout the marked climatic gradient observed across the Japanese islands. Results demonstrated that female weevils, which bored holes through camellia pericarps to lay eggs into seeds, had evolved much longer snouts than males, especially in areas in which Japanese camellia pericarps were very thick. The thickness of the plant pericarp was heritable, and the camellia plant evolved a significantly thicker pericarp on islands with the weevil than on islands without it. Across populations with weevils, resource allocation to plant defense increased with increasing annual mean temperature or annual precipitation, thereby geographically differentiating the evolutionary and ecological interactions between the two species. Given that the coevolutionary relationship exhibited appreciable variation across a relatively small range of annual mean temperatures, ongoing global climatic change can dramatically alter the coevolutionary process, thereby changing the ecological interaction between these species. PMID:21508604

Toju, Hirokazu; Abe, Harue; Ueno, Saneyoshi; Miyazawa, Yoshiyuki; Taniguchi, Fumiya; Sota, Teiji; Yahara, Tetsukazu

2011-05-01

473

Environmental causes for plant biodiversity gradients.  

PubMed Central

One of the most pervasive patterns observed in biodiversity studies is the tendency for species richness to decline towards the poles. One possible explanation is that high levels of environmental energy promote higher species richness nearer the equator. Energy input may set a limit to the number of species that can coexist in an area or alternatively may influence evolutionary rates. Within flowering plants (angiosperms), families exposed to a high energy load tend to be both more species rich and possess faster evolutionary rates, although there is no evidence that one drives the other. Specific environmental effects are likely to vary among lineages, reflecting the interaction between biological traits and environmental conditions in which they are found. One example of this is demonstrated by the high species richness of the iris family (Iridaceae) in the Cape of South Africa, a likely product of biological traits associated with reproductive isolation and the steep ecological and climatic gradients of the region. Within any set of conditions some lineages will tend to be favoured over others; however, the identity of these lineages will fluctuate with a changing environment, explaining the highly labile nature of diversification rates observed among major lineages of flowering plants. PMID:15519979

Davies, T Jonathan; Barraclough, Timothy G; Savolainen, Vincent; Chase, Mark W

2004-01-01

474

RTK signaling modulates the Dorsal gradient  

PubMed Central

The dorsoventral (DV) axis of the Drosophila embryo is patterned by a nuclear gradient of the Rel family transcription factor, Dorsal (Dl), that activates or represses numerous target genes in a region-specific manner. Here, we demonstrate that signaling by receptor tyrosine kinases (RTK) reduces nuclear levels and transcriptional activity of Dl, both at the poles and in the mid-body of the embryo. These effects depend on wntD, which encodes a Dl antagonist belonging to the Wingless/Wnt family of secreted factors. Specifically, we show that, via relief of Groucho- and Capicua-mediated repression, the Torso and EGFR RTK pathways induce expression of WntD, which in turn limits Dl nuclear localization at the poles and along the DV axis. Furthermore, this RTK-dependent control of Dl is important for restricting expression of its targets in both contexts. Thus, our results reveal a new mechanism of crosstalk, whereby RTK signals modulate the spatial distribution and activity of a developmental morphogen in vivo. PMID:22791891

Helman, Aharon; Lim, Bomyi; Andreu, María José; Kim, Yoosik; Shestkin, Tatyana; Lu, Hang; Jiménez, Gerardo; Shvartsman, Stanislav Y.; Paroush, Ze’ev

2012-01-01

475

Frustrated lattices of Ising chains  

NASA Astrophysics Data System (ADS)

The magnetic structure and magnetization dynamics of systems of plane frustrated Ising chain lattices are reviewed for three groups of compounds: {Ca_3Co_2O_6}, {CsCoCl_3}, and {Sr_5Rh_4O_{12}}. The available experimental data are analyzed and compared in detail. It is shown that a high-temperature magnetic phase on a triangle lattice is normally and universally a partially disordered antiferromagnetic (PDA) structure. The diversity of low-temperature phases results from weak interactions that lift the degeneracy of a 2D antiferromagnetic Ising model on the triangle lattice. Mean-field models, Monte Carlo simulation results on the static magnetization curve, and results on slow magnetization dynamics obtained with Glauber's theory are discussed in detail.

Kudasov, Yurii B.; Korshunov, Aleksei S.; Pavlov, V. N.; Maslov, Dmitrii A.

2012-12-01

476

Spin chains and string theory.  

PubMed

Recently, an important test of the anti de Sitter/conformal field theory correspondence has been done using rotating strings with two angular momenta. We show that such a test can be described more generally as the agreement between two actions: one a low energy description of a spin chain appearing in the field theory side, and the other a limit of the string action in AdS5xS5. This gives a map between the mean value of the spin in the boundary theory and the position of the string in the bulk, and shows how a string action can emerge from a gauge theory in the large-N limit. PMID:15524978

Kruczenski, Martin

2004-10-15

477

An implicit gradient application to fatigue of complex structures  

Microsoft Academic Search

This paper presents a procedure to evaluate the stress gradient effect on the fatigue strength of steel welded joints and notched components. An effective stress is calculated by solving a second-order differential equation over all the component (the implicit gradient approach) independently of its geometric shape. The solution is obtained by assuming the isotropic linear elastic constitutive law for the

R. Tovo; P. Livieri

2008-01-01

478

Optimizing magnetization orientation of permanent magnets for maximal gradient force  

Microsoft Academic Search

The force exercised on a permanent magnet (PM) in a nonuniform field (gradient force) is dependent on the magnetization orientation of the magnet. In this paper, it is shown theoretically that the gradient force is greatest when the magnetization through the magnet, or at least at its surface, is collinear with the external field. The formulae for calculating the force

Arvi Kruusing

2001-01-01

479

The electric field gradient in heavy rare earth metals  

Microsoft Academic Search

Estimates of the electric field gradient in heavy rare earth metals have been evaluated from experimental hyperfine interaction data. In addition, the magnetic hyperfine fields are analyzed. In the metals the effective radial integrals r-3>4f of the magnetic and quadrupole hyperfine interaction are reduced at most by 10% compared with the free ion values. The electric field gradients due to

J. Pelzl; Fachbereich Physik

1972-01-01

480

MECHANISMS CREATING COMMUNITY STRUCTURE ACROSS A FRESHWATER HABITAT GRADIENT  

Microsoft Academic Search

Lentic freshwater habitats in temperate regions exist along a gradient from small ephemeral ponds to large permanent lakes. This environmental continuum is a useful axis for understanding how attributes of individuals ultimately generate structure at the level of the community. Community structure across the gradient is determined by both (a) physical factors, such as pond drying and winter anoxia, that

Gary A. Wellborn; David K. Skelly; Earl E. Werner

1996-01-01

481

High gradient acceleration in a 17 GHz photocathode RF gun  

Microsoft Academic Search

The physics and technological issues involved in high gradient particle acceleration at high microwave (RF) frequencies are under study at MIT. The 17 GHz photocathode RF gun has a 1½ cell room temperature copper cavity with a peak accelerating gradient of about 250 MV\\/m. The anticipated beam parameters, when operating with a photoemission cathode, are: energy 2 MeV, normalized emittance

S. C. Chen; J. Gonichon; L. C.-L. Lin; R. J. Temkin; S. Trotz; B. G. Danly; J. S. Wurtele

1993-01-01

482

Tunable, pulsatile chemical gradient generation via acoustically driven oscillating bubbles†  

PubMed Central

We present a novel concept of generating both static and pulsatile chemical gradients using acoustically activated bubbles designed in a ladder-like arrangement. Furthermore, by regulating the amplitude of the bubble oscillation, we demonstrate that the chemical gradient profiles can be effectively tuned. PMID:23254861

Ahmed, Daniel; Chan, Chung Yu; Lin, Sz-Chin Steven; Muddana, Hari S.; Nama, Nitesh; Benkovic, Stephen J.; Huang, Tony Jun

2014-01-01

483

Avoiding Redundant Processing in Gradient Based Edge Detection  

Microsoft Academic Search

nique can produce computational savings of up to fifty percent in some instances. Gradient based edge detection produces edge lo- cation information by convolving an image with a 11. THEORY kernel to calculate local intensity gradients. In many images, the area of the image that contains edge lo- The goal of image is de- cation information is small relative to

Martin J. J. Scott; Richard W. Prager

1994-01-01

484

Generalizability of Scaling Gradients on Direct Behavior Ratings  

ERIC Educational Resources Information Center

Generalizability theory is used to examine the impact of scaling gradients on a single-item Direct Behavior Rating (DBR). A DBR refers to a type of rating scale used to efficiently record target behavior(s) following an observation occasion. Variance components associated with scale gradients are estimated using a random effects design for persons…

Chafouleas, Sandra M.; Christ, Theodore J.; Riley-Tillman, T. Chris

2009-01-01

485

Integral Normalized Gradient Image A Novel Illumination Insensitive Representation  

Microsoft Academic Search

In this paper, we present a novel illumination insensitive image, called integral normalized gradient image (INIGI), for face recognition. Unlike previous model-based methods, which require training images or have many str constrains for implementation, the proposed representation is simple and generic. Based on the intrinsic and extrinsic factor definition, we firstly normalized the gradient with a smoothed version of input

S. Samsung

2005-01-01

486

Gradient Well-Formedness across the Morpheme Boundary  

ERIC Educational Resources Information Center

Recent theories of phonology hold that phonotactic well-formedness may be gradient, with some legal structures being more well-formed than others. Linguistic and psycholinguistic research has demonstrated that "within" morphemes, speakers encode both categorical (*n/Onset) and gradient (st/Onset greater than sin/Onset) phonotactic restrictions.…

Goldberg, Ariel M.

2010-01-01

487

New Roles for Lysosomal Trafficking in Morphogen Gradient Sensing  

NSDL National Science Digital Library

The way in which cells recognize their position in a gradient of morphogen controls differentiation during embryogenesis. New findings indicate that the rate at which internalized morphogen receptors are trafficked to lysosomes is key to the accurate and precise sensing of morphogen gradients and the appropriate initiation of differentiation programs during development.

Elena Rainero (Beatson Institute for Cancer Research;Integrin Cell Biology Laboratory REV); Jim C. Norman (Beatson Institute for Cancer Research;Integrin Cell Biology Laboratory REV)

2011-05-03

488

Near-surface temperature gradient in a coastal upwelling regime  

NASA Astrophysics Data System (ADS)

oceanography, a near homogeneous mixed layer extending from the surface to a seasonal thermocline is a common conceptual basis in physics, chemistry, and biology. In a coastal upwelling region 3 km off the coast in the Mexican Pacific, we measured vertical density gradients with a free-rising CTD and temperature gradients with thermographs at 1, 3, and 5 m depths logging every 5 min during more than a year. No significant salinity gradient was observed down to 10 m depth, and the CTD temperature and density gradients showed no pronounced discontinuity that would suggest a near-surface mixed layer. Thermographs generally logged decreasing temperature with depth with gradients higher than 0.2 K m-1 more than half of the time in the summer between 1 and 3 m, 3 and 5 m and in the winter between 1 and 3 m. Some negative temperature gradients were present and gradients were generally highly variable in time with high peaks lasting fractions of hours to hours. These temporal changes were too rapid to be explained by local heating or cooling. The pattern of positive and negative peaks might be explained by vertical stacks of water layers of different temperatures and different horizontal drift vectors. The observed near-surface gradient has implications for turbulent wind energy transfer, vertical exchange of dissolved and particulate water constituents, the interpretation of remotely sensed SST, and horizontal wind-induced transport.

Maske, H.; Ochoa, J.; Almeda-Jauregui, C. O.; Ruiz-de la Torre, M. C.; Cruz-López, R.; Villegas-Mendoza, J. R.

2014-08-01

489

Mechanism-based strain gradient plasticity— I. Theory  

Microsoft Academic Search

A mechanism-based theory of strain gradient plasticity (MSG) is proposed based on a multiscale framework linking the microscale notion of statistically stored and geometrically necessary dislocations to the mesoscale notion of plastic strain and strain gradient. This theory is motivated by our recent analysis of indentation experiments which strongly suggest a linear dependence of the square of plastic flow stress

H. Gao; Y. Huang; W. D. Nix; J. W. Hutchinson

1999-01-01

490

Elongated chambers for field studies across atmospheric CO2 gradients  

Microsoft Academic Search

Summary 1. We describe a field facility that controls CO 2 along continuous gradients from superambient to subambient concentrations. The facility consists of two transparent, tunnel-shaped chambers, each 1-m wide and tall and 60-m long. Pure CO 2 is injected into one chamber during daylight to initiate a superambient CO 2 gradient (550-350 ? mol mol -1 ). Ambient air

H. B. Johnson; H. W. Polley; R. P. Whitis

2000-01-01

491

Influence of intraparticle gradients in modeling of fixed bed combustion  

Microsoft Academic Search

The impact of using a porous media approximation, neglecting intraparticle gradients, for modeling fixed bed combustion has been investigated. This has been done by comparing the results from a bed model using the porous media approximation with the results from the same model, where the intraparticle gradients have been taken into account by a two-dimensional particle model. The particle model

R. Johansson; H. Thunman; B. Leckner

2007-01-01